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1/*
2 * Routines having to do with the 'struct sk_buff' memory handlers.
3 *
4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
5 * Florian La Roche <rzsfl@rz.uni-sb.de>
6 *
7 * Fixes:
8 * Alan Cox : Fixed the worst of the load
9 * balancer bugs.
10 * Dave Platt : Interrupt stacking fix.
11 * Richard Kooijman : Timestamp fixes.
12 * Alan Cox : Changed buffer format.
13 * Alan Cox : destructor hook for AF_UNIX etc.
14 * Linus Torvalds : Better skb_clone.
15 * Alan Cox : Added skb_copy.
16 * Alan Cox : Added all the changed routines Linus
17 * only put in the headers
18 * Ray VanTassle : Fixed --skb->lock in free
19 * Alan Cox : skb_copy copy arp field
20 * Andi Kleen : slabified it.
21 * Robert Olsson : Removed skb_head_pool
22 *
23 * NOTE:
24 * The __skb_ routines should be called with interrupts
25 * disabled, or you better be *real* sure that the operation is atomic
26 * with respect to whatever list is being frobbed (e.g. via lock_sock()
27 * or via disabling bottom half handlers, etc).
28 *
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
33 */
34
35/*
36 * The functions in this file will not compile correctly with gcc 2.4.x
37 */
38
39#include <linux/module.h>
40#include <linux/types.h>
41#include <linux/kernel.h>
42#include <linux/kmemcheck.h>
43#include <linux/mm.h>
44#include <linux/interrupt.h>
45#include <linux/in.h>
46#include <linux/inet.h>
47#include <linux/slab.h>
48#include <linux/netdevice.h>
49#ifdef CONFIG_NET_CLS_ACT
50#include <net/pkt_sched.h>
51#endif
52#include <linux/string.h>
53#include <linux/skbuff.h>
54#include <linux/splice.h>
55#include <linux/cache.h>
56#include <linux/rtnetlink.h>
57#include <linux/init.h>
58#include <linux/scatterlist.h>
59#include <linux/errqueue.h>
60#include <linux/prefetch.h>
61
62#include <net/protocol.h>
63#include <net/dst.h>
64#include <net/sock.h>
65#include <net/checksum.h>
66#include <net/xfrm.h>
67
68#include <asm/uaccess.h>
69#include <asm/system.h>
70#include <trace/events/skb.h>
71
72#include "kmap_skb.h"
73
74static struct kmem_cache *skbuff_head_cache __read_mostly;
75static struct kmem_cache *skbuff_fclone_cache __read_mostly;
76
77static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
78 struct pipe_buffer *buf)
79{
80 put_page(buf->page);
81}
82
83static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
84 struct pipe_buffer *buf)
85{
86 get_page(buf->page);
87}
88
89static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
90 struct pipe_buffer *buf)
91{
92 return 1;
93}
94
95
96/* Pipe buffer operations for a socket. */
97static const struct pipe_buf_operations sock_pipe_buf_ops = {
98 .can_merge = 0,
99 .map = generic_pipe_buf_map,
100 .unmap = generic_pipe_buf_unmap,
101 .confirm = generic_pipe_buf_confirm,
102 .release = sock_pipe_buf_release,
103 .steal = sock_pipe_buf_steal,
104 .get = sock_pipe_buf_get,
105};
106
107/*
108 * Keep out-of-line to prevent kernel bloat.
109 * __builtin_return_address is not used because it is not always
110 * reliable.
111 */
112
113/**
114 * skb_over_panic - private function
115 * @skb: buffer
116 * @sz: size
117 * @here: address
118 *
119 * Out of line support code for skb_put(). Not user callable.
120 */
121static void skb_over_panic(struct sk_buff *skb, int sz, void *here)
122{
123 printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
124 "data:%p tail:%#lx end:%#lx dev:%s\n",
125 here, skb->len, sz, skb->head, skb->data,
126 (unsigned long)skb->tail, (unsigned long)skb->end,
127 skb->dev ? skb->dev->name : "<NULL>");
128 BUG();
129}
130
131/**
132 * skb_under_panic - private function
133 * @skb: buffer
134 * @sz: size
135 * @here: address
136 *
137 * Out of line support code for skb_push(). Not user callable.
138 */
139
140static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
141{
142 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
143 "data:%p tail:%#lx end:%#lx dev:%s\n",
144 here, skb->len, sz, skb->head, skb->data,
145 (unsigned long)skb->tail, (unsigned long)skb->end,
146 skb->dev ? skb->dev->name : "<NULL>");
147 BUG();
148}
149
150/* Allocate a new skbuff. We do this ourselves so we can fill in a few
151 * 'private' fields and also do memory statistics to find all the
152 * [BEEP] leaks.
153 *
154 */
155
156/**
157 * __alloc_skb - allocate a network buffer
158 * @size: size to allocate
159 * @gfp_mask: allocation mask
160 * @fclone: allocate from fclone cache instead of head cache
161 * and allocate a cloned (child) skb
162 * @node: numa node to allocate memory on
163 *
164 * Allocate a new &sk_buff. The returned buffer has no headroom and a
165 * tail room of size bytes. The object has a reference count of one.
166 * The return is the buffer. On a failure the return is %NULL.
167 *
168 * Buffers may only be allocated from interrupts using a @gfp_mask of
169 * %GFP_ATOMIC.
170 */
171struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
172 int fclone, int node)
173{
174 struct kmem_cache *cache;
175 struct skb_shared_info *shinfo;
176 struct sk_buff *skb;
177 u8 *data;
178
179 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
180
181 /* Get the HEAD */
182 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
183 if (!skb)
184 goto out;
185 prefetchw(skb);
186
187 size = SKB_DATA_ALIGN(size);
188 data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
189 gfp_mask, node);
190 if (!data)
191 goto nodata;
192 prefetchw(data + size);
193
194 /*
195 * Only clear those fields we need to clear, not those that we will
196 * actually initialise below. Hence, don't put any more fields after
197 * the tail pointer in struct sk_buff!
198 */
199 memset(skb, 0, offsetof(struct sk_buff, tail));
200 skb->truesize = size + sizeof(struct sk_buff);
201 atomic_set(&skb->users, 1);
202 skb->head = data;
203 skb->data = data;
204 skb_reset_tail_pointer(skb);
205 skb->end = skb->tail + size;
206#ifdef NET_SKBUFF_DATA_USES_OFFSET
207 skb->mac_header = ~0U;
208#endif
209
210 /* make sure we initialize shinfo sequentially */
211 shinfo = skb_shinfo(skb);
212 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
213 atomic_set(&shinfo->dataref, 1);
214 kmemcheck_annotate_variable(shinfo->destructor_arg);
215
216 if (fclone) {
217 struct sk_buff *child = skb + 1;
218 atomic_t *fclone_ref = (atomic_t *) (child + 1);
219
220 kmemcheck_annotate_bitfield(child, flags1);
221 kmemcheck_annotate_bitfield(child, flags2);
222 skb->fclone = SKB_FCLONE_ORIG;
223 atomic_set(fclone_ref, 1);
224
225 child->fclone = SKB_FCLONE_UNAVAILABLE;
226 }
227out:
228 return skb;
229nodata:
230 kmem_cache_free(cache, skb);
231 skb = NULL;
232 goto out;
233}
234EXPORT_SYMBOL(__alloc_skb);
235
236/**
237 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
238 * @dev: network device to receive on
239 * @length: length to allocate
240 * @gfp_mask: get_free_pages mask, passed to alloc_skb
241 *
242 * Allocate a new &sk_buff and assign it a usage count of one. The
243 * buffer has unspecified headroom built in. Users should allocate
244 * the headroom they think they need without accounting for the
245 * built in space. The built in space is used for optimisations.
246 *
247 * %NULL is returned if there is no free memory.
248 */
249struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
250 unsigned int length, gfp_t gfp_mask)
251{
252 struct sk_buff *skb;
253
254 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
255 if (likely(skb)) {
256 skb_reserve(skb, NET_SKB_PAD);
257 skb->dev = dev;
258 }
259 return skb;
260}
261EXPORT_SYMBOL(__netdev_alloc_skb);
262
263void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
264 int size)
265{
266 skb_fill_page_desc(skb, i, page, off, size);
267 skb->len += size;
268 skb->data_len += size;
269 skb->truesize += size;
270}
271EXPORT_SYMBOL(skb_add_rx_frag);
272
273/**
274 * dev_alloc_skb - allocate an skbuff for receiving
275 * @length: length to allocate
276 *
277 * Allocate a new &sk_buff and assign it a usage count of one. The
278 * buffer has unspecified headroom built in. Users should allocate
279 * the headroom they think they need without accounting for the
280 * built in space. The built in space is used for optimisations.
281 *
282 * %NULL is returned if there is no free memory. Although this function
283 * allocates memory it can be called from an interrupt.
284 */
285struct sk_buff *dev_alloc_skb(unsigned int length)
286{
287 /*
288 * There is more code here than it seems:
289 * __dev_alloc_skb is an inline
290 */
291 return __dev_alloc_skb(length, GFP_ATOMIC);
292}
293EXPORT_SYMBOL(dev_alloc_skb);
294
295static void skb_drop_list(struct sk_buff **listp)
296{
297 struct sk_buff *list = *listp;
298
299 *listp = NULL;
300
301 do {
302 struct sk_buff *this = list;
303 list = list->next;
304 kfree_skb(this);
305 } while (list);
306}
307
308static inline void skb_drop_fraglist(struct sk_buff *skb)
309{
310 skb_drop_list(&skb_shinfo(skb)->frag_list);
311}
312
313static void skb_clone_fraglist(struct sk_buff *skb)
314{
315 struct sk_buff *list;
316
317 skb_walk_frags(skb, list)
318 skb_get(list);
319}
320
321static void skb_release_data(struct sk_buff *skb)
322{
323 if (!skb->cloned ||
324 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
325 &skb_shinfo(skb)->dataref)) {
326 if (skb_shinfo(skb)->nr_frags) {
327 int i;
328 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
329 put_page(skb_shinfo(skb)->frags[i].page);
330 }
331
332 /*
333 * If skb buf is from userspace, we need to notify the caller
334 * the lower device DMA has done;
335 */
336 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
337 struct ubuf_info *uarg;
338
339 uarg = skb_shinfo(skb)->destructor_arg;
340 if (uarg->callback)
341 uarg->callback(uarg);
342 }
343
344 if (skb_has_frag_list(skb))
345 skb_drop_fraglist(skb);
346
347 kfree(skb->head);
348 }
349}
350
351/*
352 * Free an skbuff by memory without cleaning the state.
353 */
354static void kfree_skbmem(struct sk_buff *skb)
355{
356 struct sk_buff *other;
357 atomic_t *fclone_ref;
358
359 switch (skb->fclone) {
360 case SKB_FCLONE_UNAVAILABLE:
361 kmem_cache_free(skbuff_head_cache, skb);
362 break;
363
364 case SKB_FCLONE_ORIG:
365 fclone_ref = (atomic_t *) (skb + 2);
366 if (atomic_dec_and_test(fclone_ref))
367 kmem_cache_free(skbuff_fclone_cache, skb);
368 break;
369
370 case SKB_FCLONE_CLONE:
371 fclone_ref = (atomic_t *) (skb + 1);
372 other = skb - 1;
373
374 /* The clone portion is available for
375 * fast-cloning again.
376 */
377 skb->fclone = SKB_FCLONE_UNAVAILABLE;
378
379 if (atomic_dec_and_test(fclone_ref))
380 kmem_cache_free(skbuff_fclone_cache, other);
381 break;
382 }
383}
384
385static void skb_release_head_state(struct sk_buff *skb)
386{
387 skb_dst_drop(skb);
388#ifdef CONFIG_XFRM
389 secpath_put(skb->sp);
390#endif
391 if (skb->destructor) {
392 WARN_ON(in_irq());
393 skb->destructor(skb);
394 }
395#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
396 nf_conntrack_put(skb->nfct);
397#endif
398#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
399 nf_conntrack_put_reasm(skb->nfct_reasm);
400#endif
401#ifdef CONFIG_BRIDGE_NETFILTER
402 nf_bridge_put(skb->nf_bridge);
403#endif
404/* XXX: IS this still necessary? - JHS */
405#ifdef CONFIG_NET_SCHED
406 skb->tc_index = 0;
407#ifdef CONFIG_NET_CLS_ACT
408 skb->tc_verd = 0;
409#endif
410#endif
411}
412
413/* Free everything but the sk_buff shell. */
414static void skb_release_all(struct sk_buff *skb)
415{
416 skb_release_head_state(skb);
417 skb_release_data(skb);
418}
419
420/**
421 * __kfree_skb - private function
422 * @skb: buffer
423 *
424 * Free an sk_buff. Release anything attached to the buffer.
425 * Clean the state. This is an internal helper function. Users should
426 * always call kfree_skb
427 */
428
429void __kfree_skb(struct sk_buff *skb)
430{
431 skb_release_all(skb);
432 kfree_skbmem(skb);
433}
434EXPORT_SYMBOL(__kfree_skb);
435
436/**
437 * kfree_skb - free an sk_buff
438 * @skb: buffer to free
439 *
440 * Drop a reference to the buffer and free it if the usage count has
441 * hit zero.
442 */
443void kfree_skb(struct sk_buff *skb)
444{
445 if (unlikely(!skb))
446 return;
447 if (likely(atomic_read(&skb->users) == 1))
448 smp_rmb();
449 else if (likely(!atomic_dec_and_test(&skb->users)))
450 return;
451 trace_kfree_skb(skb, __builtin_return_address(0));
452 __kfree_skb(skb);
453}
454EXPORT_SYMBOL(kfree_skb);
455
456/**
457 * consume_skb - free an skbuff
458 * @skb: buffer to free
459 *
460 * Drop a ref to the buffer and free it if the usage count has hit zero
461 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
462 * is being dropped after a failure and notes that
463 */
464void consume_skb(struct sk_buff *skb)
465{
466 if (unlikely(!skb))
467 return;
468 if (likely(atomic_read(&skb->users) == 1))
469 smp_rmb();
470 else if (likely(!atomic_dec_and_test(&skb->users)))
471 return;
472 trace_consume_skb(skb);
473 __kfree_skb(skb);
474}
475EXPORT_SYMBOL(consume_skb);
476
477/**
478 * skb_recycle_check - check if skb can be reused for receive
479 * @skb: buffer
480 * @skb_size: minimum receive buffer size
481 *
482 * Checks that the skb passed in is not shared or cloned, and
483 * that it is linear and its head portion at least as large as
484 * skb_size so that it can be recycled as a receive buffer.
485 * If these conditions are met, this function does any necessary
486 * reference count dropping and cleans up the skbuff as if it
487 * just came from __alloc_skb().
488 */
489bool skb_recycle_check(struct sk_buff *skb, int skb_size)
490{
491 struct skb_shared_info *shinfo;
492
493 if (irqs_disabled())
494 return false;
495
496 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)
497 return false;
498
499 if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
500 return false;
501
502 skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
503 if (skb_end_pointer(skb) - skb->head < skb_size)
504 return false;
505
506 if (skb_shared(skb) || skb_cloned(skb))
507 return false;
508
509 skb_release_head_state(skb);
510
511 shinfo = skb_shinfo(skb);
512 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
513 atomic_set(&shinfo->dataref, 1);
514
515 memset(skb, 0, offsetof(struct sk_buff, tail));
516 skb->data = skb->head + NET_SKB_PAD;
517 skb_reset_tail_pointer(skb);
518
519 return true;
520}
521EXPORT_SYMBOL(skb_recycle_check);
522
523static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
524{
525 new->tstamp = old->tstamp;
526 new->dev = old->dev;
527 new->transport_header = old->transport_header;
528 new->network_header = old->network_header;
529 new->mac_header = old->mac_header;
530 skb_dst_copy(new, old);
531 new->rxhash = old->rxhash;
532#ifdef CONFIG_XFRM
533 new->sp = secpath_get(old->sp);
534#endif
535 memcpy(new->cb, old->cb, sizeof(old->cb));
536 new->csum = old->csum;
537 new->local_df = old->local_df;
538 new->pkt_type = old->pkt_type;
539 new->ip_summed = old->ip_summed;
540 skb_copy_queue_mapping(new, old);
541 new->priority = old->priority;
542#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
543 new->ipvs_property = old->ipvs_property;
544#endif
545 new->protocol = old->protocol;
546 new->mark = old->mark;
547 new->skb_iif = old->skb_iif;
548 __nf_copy(new, old);
549#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
550 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
551 new->nf_trace = old->nf_trace;
552#endif
553#ifdef CONFIG_NET_SCHED
554 new->tc_index = old->tc_index;
555#ifdef CONFIG_NET_CLS_ACT
556 new->tc_verd = old->tc_verd;
557#endif
558#endif
559 new->vlan_tci = old->vlan_tci;
560
561 skb_copy_secmark(new, old);
562}
563
564/*
565 * You should not add any new code to this function. Add it to
566 * __copy_skb_header above instead.
567 */
568static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
569{
570#define C(x) n->x = skb->x
571
572 n->next = n->prev = NULL;
573 n->sk = NULL;
574 __copy_skb_header(n, skb);
575
576 C(len);
577 C(data_len);
578 C(mac_len);
579 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
580 n->cloned = 1;
581 n->nohdr = 0;
582 n->destructor = NULL;
583 C(tail);
584 C(end);
585 C(head);
586 C(data);
587 C(truesize);
588 atomic_set(&n->users, 1);
589
590 atomic_inc(&(skb_shinfo(skb)->dataref));
591 skb->cloned = 1;
592
593 return n;
594#undef C
595}
596
597/**
598 * skb_morph - morph one skb into another
599 * @dst: the skb to receive the contents
600 * @src: the skb to supply the contents
601 *
602 * This is identical to skb_clone except that the target skb is
603 * supplied by the user.
604 *
605 * The target skb is returned upon exit.
606 */
607struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
608{
609 skb_release_all(dst);
610 return __skb_clone(dst, src);
611}
612EXPORT_SYMBOL_GPL(skb_morph);
613
614/* skb_copy_ubufs - copy userspace skb frags buffers to kernel
615 * @skb: the skb to modify
616 * @gfp_mask: allocation priority
617 *
618 * This must be called on SKBTX_DEV_ZEROCOPY skb.
619 * It will copy all frags into kernel and drop the reference
620 * to userspace pages.
621 *
622 * If this function is called from an interrupt gfp_mask() must be
623 * %GFP_ATOMIC.
624 *
625 * Returns 0 on success or a negative error code on failure
626 * to allocate kernel memory to copy to.
627 */
628int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
629{
630 int i;
631 int num_frags = skb_shinfo(skb)->nr_frags;
632 struct page *page, *head = NULL;
633 struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;
634
635 for (i = 0; i < num_frags; i++) {
636 u8 *vaddr;
637 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
638
639 page = alloc_page(GFP_ATOMIC);
640 if (!page) {
641 while (head) {
642 struct page *next = (struct page *)head->private;
643 put_page(head);
644 head = next;
645 }
646 return -ENOMEM;
647 }
648 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
649 memcpy(page_address(page),
650 vaddr + f->page_offset, f->size);
651 kunmap_skb_frag(vaddr);
652 page->private = (unsigned long)head;
653 head = page;
654 }
655
656 /* skb frags release userspace buffers */
657 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
658 put_page(skb_shinfo(skb)->frags[i].page);
659
660 uarg->callback(uarg);
661
662 /* skb frags point to kernel buffers */
663 for (i = skb_shinfo(skb)->nr_frags; i > 0; i--) {
664 skb_shinfo(skb)->frags[i - 1].page_offset = 0;
665 skb_shinfo(skb)->frags[i - 1].page = head;
666 head = (struct page *)head->private;
667 }
668
669 skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
670 return 0;
671}
672
673
674/**
675 * skb_clone - duplicate an sk_buff
676 * @skb: buffer to clone
677 * @gfp_mask: allocation priority
678 *
679 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
680 * copies share the same packet data but not structure. The new
681 * buffer has a reference count of 1. If the allocation fails the
682 * function returns %NULL otherwise the new buffer is returned.
683 *
684 * If this function is called from an interrupt gfp_mask() must be
685 * %GFP_ATOMIC.
686 */
687
688struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
689{
690 struct sk_buff *n;
691
692 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
693 if (skb_copy_ubufs(skb, gfp_mask))
694 return NULL;
695 }
696
697 n = skb + 1;
698 if (skb->fclone == SKB_FCLONE_ORIG &&
699 n->fclone == SKB_FCLONE_UNAVAILABLE) {
700 atomic_t *fclone_ref = (atomic_t *) (n + 1);
701 n->fclone = SKB_FCLONE_CLONE;
702 atomic_inc(fclone_ref);
703 } else {
704 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
705 if (!n)
706 return NULL;
707
708 kmemcheck_annotate_bitfield(n, flags1);
709 kmemcheck_annotate_bitfield(n, flags2);
710 n->fclone = SKB_FCLONE_UNAVAILABLE;
711 }
712
713 return __skb_clone(n, skb);
714}
715EXPORT_SYMBOL(skb_clone);
716
717static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
718{
719#ifndef NET_SKBUFF_DATA_USES_OFFSET
720 /*
721 * Shift between the two data areas in bytes
722 */
723 unsigned long offset = new->data - old->data;
724#endif
725
726 __copy_skb_header(new, old);
727
728#ifndef NET_SKBUFF_DATA_USES_OFFSET
729 /* {transport,network,mac}_header are relative to skb->head */
730 new->transport_header += offset;
731 new->network_header += offset;
732 if (skb_mac_header_was_set(new))
733 new->mac_header += offset;
734#endif
735 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
736 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
737 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
738}
739
740/**
741 * skb_copy - create private copy of an sk_buff
742 * @skb: buffer to copy
743 * @gfp_mask: allocation priority
744 *
745 * Make a copy of both an &sk_buff and its data. This is used when the
746 * caller wishes to modify the data and needs a private copy of the
747 * data to alter. Returns %NULL on failure or the pointer to the buffer
748 * on success. The returned buffer has a reference count of 1.
749 *
750 * As by-product this function converts non-linear &sk_buff to linear
751 * one, so that &sk_buff becomes completely private and caller is allowed
752 * to modify all the data of returned buffer. This means that this
753 * function is not recommended for use in circumstances when only
754 * header is going to be modified. Use pskb_copy() instead.
755 */
756
757struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
758{
759 int headerlen = skb_headroom(skb);
760 unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
761 struct sk_buff *n = alloc_skb(size, gfp_mask);
762
763 if (!n)
764 return NULL;
765
766 /* Set the data pointer */
767 skb_reserve(n, headerlen);
768 /* Set the tail pointer and length */
769 skb_put(n, skb->len);
770
771 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
772 BUG();
773
774 copy_skb_header(n, skb);
775 return n;
776}
777EXPORT_SYMBOL(skb_copy);
778
779/**
780 * pskb_copy - create copy of an sk_buff with private head.
781 * @skb: buffer to copy
782 * @gfp_mask: allocation priority
783 *
784 * Make a copy of both an &sk_buff and part of its data, located
785 * in header. Fragmented data remain shared. This is used when
786 * the caller wishes to modify only header of &sk_buff and needs
787 * private copy of the header to alter. Returns %NULL on failure
788 * or the pointer to the buffer on success.
789 * The returned buffer has a reference count of 1.
790 */
791
792struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
793{
794 unsigned int size = skb_end_pointer(skb) - skb->head;
795 struct sk_buff *n = alloc_skb(size, gfp_mask);
796
797 if (!n)
798 goto out;
799
800 /* Set the data pointer */
801 skb_reserve(n, skb_headroom(skb));
802 /* Set the tail pointer and length */
803 skb_put(n, skb_headlen(skb));
804 /* Copy the bytes */
805 skb_copy_from_linear_data(skb, n->data, n->len);
806
807 n->truesize += skb->data_len;
808 n->data_len = skb->data_len;
809 n->len = skb->len;
810
811 if (skb_shinfo(skb)->nr_frags) {
812 int i;
813
814 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
815 if (skb_copy_ubufs(skb, gfp_mask)) {
816 kfree_skb(n);
817 n = NULL;
818 goto out;
819 }
820 }
821 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
822 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
823 get_page(skb_shinfo(n)->frags[i].page);
824 }
825 skb_shinfo(n)->nr_frags = i;
826 }
827
828 if (skb_has_frag_list(skb)) {
829 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
830 skb_clone_fraglist(n);
831 }
832
833 copy_skb_header(n, skb);
834out:
835 return n;
836}
837EXPORT_SYMBOL(pskb_copy);
838
839/**
840 * pskb_expand_head - reallocate header of &sk_buff
841 * @skb: buffer to reallocate
842 * @nhead: room to add at head
843 * @ntail: room to add at tail
844 * @gfp_mask: allocation priority
845 *
846 * Expands (or creates identical copy, if &nhead and &ntail are zero)
847 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
848 * reference count of 1. Returns zero in the case of success or error,
849 * if expansion failed. In the last case, &sk_buff is not changed.
850 *
851 * All the pointers pointing into skb header may change and must be
852 * reloaded after call to this function.
853 */
854
855int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
856 gfp_t gfp_mask)
857{
858 int i;
859 u8 *data;
860 int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail;
861 long off;
862 bool fastpath;
863
864 BUG_ON(nhead < 0);
865
866 if (skb_shared(skb))
867 BUG();
868
869 size = SKB_DATA_ALIGN(size);
870
871 /* Check if we can avoid taking references on fragments if we own
872 * the last reference on skb->head. (see skb_release_data())
873 */
874 if (!skb->cloned)
875 fastpath = true;
876 else {
877 int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;
878 fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
879 }
880
881 if (fastpath &&
882 size + sizeof(struct skb_shared_info) <= ksize(skb->head)) {
883 memmove(skb->head + size, skb_shinfo(skb),
884 offsetof(struct skb_shared_info,
885 frags[skb_shinfo(skb)->nr_frags]));
886 memmove(skb->head + nhead, skb->head,
887 skb_tail_pointer(skb) - skb->head);
888 off = nhead;
889 goto adjust_others;
890 }
891
892 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
893 if (!data)
894 goto nodata;
895
896 /* Copy only real data... and, alas, header. This should be
897 * optimized for the cases when header is void.
898 */
899 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
900
901 memcpy((struct skb_shared_info *)(data + size),
902 skb_shinfo(skb),
903 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
904
905 if (fastpath) {
906 kfree(skb->head);
907 } else {
908 /* copy this zero copy skb frags */
909 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
910 if (skb_copy_ubufs(skb, gfp_mask))
911 goto nofrags;
912 }
913 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
914 get_page(skb_shinfo(skb)->frags[i].page);
915
916 if (skb_has_frag_list(skb))
917 skb_clone_fraglist(skb);
918
919 skb_release_data(skb);
920 }
921 off = (data + nhead) - skb->head;
922
923 skb->head = data;
924adjust_others:
925 skb->data += off;
926#ifdef NET_SKBUFF_DATA_USES_OFFSET
927 skb->end = size;
928 off = nhead;
929#else
930 skb->end = skb->head + size;
931#endif
932 /* {transport,network,mac}_header and tail are relative to skb->head */
933 skb->tail += off;
934 skb->transport_header += off;
935 skb->network_header += off;
936 if (skb_mac_header_was_set(skb))
937 skb->mac_header += off;
938 /* Only adjust this if it actually is csum_start rather than csum */
939 if (skb->ip_summed == CHECKSUM_PARTIAL)
940 skb->csum_start += nhead;
941 skb->cloned = 0;
942 skb->hdr_len = 0;
943 skb->nohdr = 0;
944 atomic_set(&skb_shinfo(skb)->dataref, 1);
945 return 0;
946
947nofrags:
948 kfree(data);
949nodata:
950 return -ENOMEM;
951}
952EXPORT_SYMBOL(pskb_expand_head);
953
954/* Make private copy of skb with writable head and some headroom */
955
956struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
957{
958 struct sk_buff *skb2;
959 int delta = headroom - skb_headroom(skb);
960
961 if (delta <= 0)
962 skb2 = pskb_copy(skb, GFP_ATOMIC);
963 else {
964 skb2 = skb_clone(skb, GFP_ATOMIC);
965 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
966 GFP_ATOMIC)) {
967 kfree_skb(skb2);
968 skb2 = NULL;
969 }
970 }
971 return skb2;
972}
973EXPORT_SYMBOL(skb_realloc_headroom);
974
975/**
976 * skb_copy_expand - copy and expand sk_buff
977 * @skb: buffer to copy
978 * @newheadroom: new free bytes at head
979 * @newtailroom: new free bytes at tail
980 * @gfp_mask: allocation priority
981 *
982 * Make a copy of both an &sk_buff and its data and while doing so
983 * allocate additional space.
984 *
985 * This is used when the caller wishes to modify the data and needs a
986 * private copy of the data to alter as well as more space for new fields.
987 * Returns %NULL on failure or the pointer to the buffer
988 * on success. The returned buffer has a reference count of 1.
989 *
990 * You must pass %GFP_ATOMIC as the allocation priority if this function
991 * is called from an interrupt.
992 */
993struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
994 int newheadroom, int newtailroom,
995 gfp_t gfp_mask)
996{
997 /*
998 * Allocate the copy buffer
999 */
1000 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
1001 gfp_mask);
1002 int oldheadroom = skb_headroom(skb);
1003 int head_copy_len, head_copy_off;
1004 int off;
1005
1006 if (!n)
1007 return NULL;
1008
1009 skb_reserve(n, newheadroom);
1010
1011 /* Set the tail pointer and length */
1012 skb_put(n, skb->len);
1013
1014 head_copy_len = oldheadroom;
1015 head_copy_off = 0;
1016 if (newheadroom <= head_copy_len)
1017 head_copy_len = newheadroom;
1018 else
1019 head_copy_off = newheadroom - head_copy_len;
1020
1021 /* Copy the linear header and data. */
1022 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1023 skb->len + head_copy_len))
1024 BUG();
1025
1026 copy_skb_header(n, skb);
1027
1028 off = newheadroom - oldheadroom;
1029 if (n->ip_summed == CHECKSUM_PARTIAL)
1030 n->csum_start += off;
1031#ifdef NET_SKBUFF_DATA_USES_OFFSET
1032 n->transport_header += off;
1033 n->network_header += off;
1034 if (skb_mac_header_was_set(skb))
1035 n->mac_header += off;
1036#endif
1037
1038 return n;
1039}
1040EXPORT_SYMBOL(skb_copy_expand);
1041
1042/**
1043 * skb_pad - zero pad the tail of an skb
1044 * @skb: buffer to pad
1045 * @pad: space to pad
1046 *
1047 * Ensure that a buffer is followed by a padding area that is zero
1048 * filled. Used by network drivers which may DMA or transfer data
1049 * beyond the buffer end onto the wire.
1050 *
1051 * May return error in out of memory cases. The skb is freed on error.
1052 */
1053
1054int skb_pad(struct sk_buff *skb, int pad)
1055{
1056 int err;
1057 int ntail;
1058
1059 /* If the skbuff is non linear tailroom is always zero.. */
1060 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1061 memset(skb->data+skb->len, 0, pad);
1062 return 0;
1063 }
1064
1065 ntail = skb->data_len + pad - (skb->end - skb->tail);
1066 if (likely(skb_cloned(skb) || ntail > 0)) {
1067 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1068 if (unlikely(err))
1069 goto free_skb;
1070 }
1071
1072 /* FIXME: The use of this function with non-linear skb's really needs
1073 * to be audited.
1074 */
1075 err = skb_linearize(skb);
1076 if (unlikely(err))
1077 goto free_skb;
1078
1079 memset(skb->data + skb->len, 0, pad);
1080 return 0;
1081
1082free_skb:
1083 kfree_skb(skb);
1084 return err;
1085}
1086EXPORT_SYMBOL(skb_pad);
1087
1088/**
1089 * skb_put - add data to a buffer
1090 * @skb: buffer to use
1091 * @len: amount of data to add
1092 *
1093 * This function extends the used data area of the buffer. If this would
1094 * exceed the total buffer size the kernel will panic. A pointer to the
1095 * first byte of the extra data is returned.
1096 */
1097unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
1098{
1099 unsigned char *tmp = skb_tail_pointer(skb);
1100 SKB_LINEAR_ASSERT(skb);
1101 skb->tail += len;
1102 skb->len += len;
1103 if (unlikely(skb->tail > skb->end))
1104 skb_over_panic(skb, len, __builtin_return_address(0));
1105 return tmp;
1106}
1107EXPORT_SYMBOL(skb_put);
1108
1109/**
1110 * skb_push - add data to the start of a buffer
1111 * @skb: buffer to use
1112 * @len: amount of data to add
1113 *
1114 * This function extends the used data area of the buffer at the buffer
1115 * start. If this would exceed the total buffer headroom the kernel will
1116 * panic. A pointer to the first byte of the extra data is returned.
1117 */
1118unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1119{
1120 skb->data -= len;
1121 skb->len += len;
1122 if (unlikely(skb->data<skb->head))
1123 skb_under_panic(skb, len, __builtin_return_address(0));
1124 return skb->data;
1125}
1126EXPORT_SYMBOL(skb_push);
1127
1128/**
1129 * skb_pull - remove data from the start of a buffer
1130 * @skb: buffer to use
1131 * @len: amount of data to remove
1132 *
1133 * This function removes data from the start of a buffer, returning
1134 * the memory to the headroom. A pointer to the next data in the buffer
1135 * is returned. Once the data has been pulled future pushes will overwrite
1136 * the old data.
1137 */
1138unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1139{
1140 return skb_pull_inline(skb, len);
1141}
1142EXPORT_SYMBOL(skb_pull);
1143
1144/**
1145 * skb_trim - remove end from a buffer
1146 * @skb: buffer to alter
1147 * @len: new length
1148 *
1149 * Cut the length of a buffer down by removing data from the tail. If
1150 * the buffer is already under the length specified it is not modified.
1151 * The skb must be linear.
1152 */
1153void skb_trim(struct sk_buff *skb, unsigned int len)
1154{
1155 if (skb->len > len)
1156 __skb_trim(skb, len);
1157}
1158EXPORT_SYMBOL(skb_trim);
1159
1160/* Trims skb to length len. It can change skb pointers.
1161 */
1162
1163int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1164{
1165 struct sk_buff **fragp;
1166 struct sk_buff *frag;
1167 int offset = skb_headlen(skb);
1168 int nfrags = skb_shinfo(skb)->nr_frags;
1169 int i;
1170 int err;
1171
1172 if (skb_cloned(skb) &&
1173 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1174 return err;
1175
1176 i = 0;
1177 if (offset >= len)
1178 goto drop_pages;
1179
1180 for (; i < nfrags; i++) {
1181 int end = offset + skb_shinfo(skb)->frags[i].size;
1182
1183 if (end < len) {
1184 offset = end;
1185 continue;
1186 }
1187
1188 skb_shinfo(skb)->frags[i++].size = len - offset;
1189
1190drop_pages:
1191 skb_shinfo(skb)->nr_frags = i;
1192
1193 for (; i < nfrags; i++)
1194 put_page(skb_shinfo(skb)->frags[i].page);
1195
1196 if (skb_has_frag_list(skb))
1197 skb_drop_fraglist(skb);
1198 goto done;
1199 }
1200
1201 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1202 fragp = &frag->next) {
1203 int end = offset + frag->len;
1204
1205 if (skb_shared(frag)) {
1206 struct sk_buff *nfrag;
1207
1208 nfrag = skb_clone(frag, GFP_ATOMIC);
1209 if (unlikely(!nfrag))
1210 return -ENOMEM;
1211
1212 nfrag->next = frag->next;
1213 kfree_skb(frag);
1214 frag = nfrag;
1215 *fragp = frag;
1216 }
1217
1218 if (end < len) {
1219 offset = end;
1220 continue;
1221 }
1222
1223 if (end > len &&
1224 unlikely((err = pskb_trim(frag, len - offset))))
1225 return err;
1226
1227 if (frag->next)
1228 skb_drop_list(&frag->next);
1229 break;
1230 }
1231
1232done:
1233 if (len > skb_headlen(skb)) {
1234 skb->data_len -= skb->len - len;
1235 skb->len = len;
1236 } else {
1237 skb->len = len;
1238 skb->data_len = 0;
1239 skb_set_tail_pointer(skb, len);
1240 }
1241
1242 return 0;
1243}
1244EXPORT_SYMBOL(___pskb_trim);
1245
1246/**
1247 * __pskb_pull_tail - advance tail of skb header
1248 * @skb: buffer to reallocate
1249 * @delta: number of bytes to advance tail
1250 *
1251 * The function makes a sense only on a fragmented &sk_buff,
1252 * it expands header moving its tail forward and copying necessary
1253 * data from fragmented part.
1254 *
1255 * &sk_buff MUST have reference count of 1.
1256 *
1257 * Returns %NULL (and &sk_buff does not change) if pull failed
1258 * or value of new tail of skb in the case of success.
1259 *
1260 * All the pointers pointing into skb header may change and must be
1261 * reloaded after call to this function.
1262 */
1263
1264/* Moves tail of skb head forward, copying data from fragmented part,
1265 * when it is necessary.
1266 * 1. It may fail due to malloc failure.
1267 * 2. It may change skb pointers.
1268 *
1269 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1270 */
1271unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1272{
1273 /* If skb has not enough free space at tail, get new one
1274 * plus 128 bytes for future expansions. If we have enough
1275 * room at tail, reallocate without expansion only if skb is cloned.
1276 */
1277 int i, k, eat = (skb->tail + delta) - skb->end;
1278
1279 if (eat > 0 || skb_cloned(skb)) {
1280 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1281 GFP_ATOMIC))
1282 return NULL;
1283 }
1284
1285 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1286 BUG();
1287
1288 /* Optimization: no fragments, no reasons to preestimate
1289 * size of pulled pages. Superb.
1290 */
1291 if (!skb_has_frag_list(skb))
1292 goto pull_pages;
1293
1294 /* Estimate size of pulled pages. */
1295 eat = delta;
1296 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1297 if (skb_shinfo(skb)->frags[i].size >= eat)
1298 goto pull_pages;
1299 eat -= skb_shinfo(skb)->frags[i].size;
1300 }
1301
1302 /* If we need update frag list, we are in troubles.
1303 * Certainly, it possible to add an offset to skb data,
1304 * but taking into account that pulling is expected to
1305 * be very rare operation, it is worth to fight against
1306 * further bloating skb head and crucify ourselves here instead.
1307 * Pure masohism, indeed. 8)8)
1308 */
1309 if (eat) {
1310 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1311 struct sk_buff *clone = NULL;
1312 struct sk_buff *insp = NULL;
1313
1314 do {
1315 BUG_ON(!list);
1316
1317 if (list->len <= eat) {
1318 /* Eaten as whole. */
1319 eat -= list->len;
1320 list = list->next;
1321 insp = list;
1322 } else {
1323 /* Eaten partially. */
1324
1325 if (skb_shared(list)) {
1326 /* Sucks! We need to fork list. :-( */
1327 clone = skb_clone(list, GFP_ATOMIC);
1328 if (!clone)
1329 return NULL;
1330 insp = list->next;
1331 list = clone;
1332 } else {
1333 /* This may be pulled without
1334 * problems. */
1335 insp = list;
1336 }
1337 if (!pskb_pull(list, eat)) {
1338 kfree_skb(clone);
1339 return NULL;
1340 }
1341 break;
1342 }
1343 } while (eat);
1344
1345 /* Free pulled out fragments. */
1346 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1347 skb_shinfo(skb)->frag_list = list->next;
1348 kfree_skb(list);
1349 }
1350 /* And insert new clone at head. */
1351 if (clone) {
1352 clone->next = list;
1353 skb_shinfo(skb)->frag_list = clone;
1354 }
1355 }
1356 /* Success! Now we may commit changes to skb data. */
1357
1358pull_pages:
1359 eat = delta;
1360 k = 0;
1361 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1362 if (skb_shinfo(skb)->frags[i].size <= eat) {
1363 put_page(skb_shinfo(skb)->frags[i].page);
1364 eat -= skb_shinfo(skb)->frags[i].size;
1365 } else {
1366 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1367 if (eat) {
1368 skb_shinfo(skb)->frags[k].page_offset += eat;
1369 skb_shinfo(skb)->frags[k].size -= eat;
1370 eat = 0;
1371 }
1372 k++;
1373 }
1374 }
1375 skb_shinfo(skb)->nr_frags = k;
1376
1377 skb->tail += delta;
1378 skb->data_len -= delta;
1379
1380 return skb_tail_pointer(skb);
1381}
1382EXPORT_SYMBOL(__pskb_pull_tail);
1383
1384/**
1385 * skb_copy_bits - copy bits from skb to kernel buffer
1386 * @skb: source skb
1387 * @offset: offset in source
1388 * @to: destination buffer
1389 * @len: number of bytes to copy
1390 *
1391 * Copy the specified number of bytes from the source skb to the
1392 * destination buffer.
1393 *
1394 * CAUTION ! :
1395 * If its prototype is ever changed,
1396 * check arch/{*}/net/{*}.S files,
1397 * since it is called from BPF assembly code.
1398 */
1399int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1400{
1401 int start = skb_headlen(skb);
1402 struct sk_buff *frag_iter;
1403 int i, copy;
1404
1405 if (offset > (int)skb->len - len)
1406 goto fault;
1407
1408 /* Copy header. */
1409 if ((copy = start - offset) > 0) {
1410 if (copy > len)
1411 copy = len;
1412 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1413 if ((len -= copy) == 0)
1414 return 0;
1415 offset += copy;
1416 to += copy;
1417 }
1418
1419 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1420 int end;
1421
1422 WARN_ON(start > offset + len);
1423
1424 end = start + skb_shinfo(skb)->frags[i].size;
1425 if ((copy = end - offset) > 0) {
1426 u8 *vaddr;
1427
1428 if (copy > len)
1429 copy = len;
1430
1431 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
1432 memcpy(to,
1433 vaddr + skb_shinfo(skb)->frags[i].page_offset+
1434 offset - start, copy);
1435 kunmap_skb_frag(vaddr);
1436
1437 if ((len -= copy) == 0)
1438 return 0;
1439 offset += copy;
1440 to += copy;
1441 }
1442 start = end;
1443 }
1444
1445 skb_walk_frags(skb, frag_iter) {
1446 int end;
1447
1448 WARN_ON(start > offset + len);
1449
1450 end = start + frag_iter->len;
1451 if ((copy = end - offset) > 0) {
1452 if (copy > len)
1453 copy = len;
1454 if (skb_copy_bits(frag_iter, offset - start, to, copy))
1455 goto fault;
1456 if ((len -= copy) == 0)
1457 return 0;
1458 offset += copy;
1459 to += copy;
1460 }
1461 start = end;
1462 }
1463
1464 if (!len)
1465 return 0;
1466
1467fault:
1468 return -EFAULT;
1469}
1470EXPORT_SYMBOL(skb_copy_bits);
1471
1472/*
1473 * Callback from splice_to_pipe(), if we need to release some pages
1474 * at the end of the spd in case we error'ed out in filling the pipe.
1475 */
1476static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1477{
1478 put_page(spd->pages[i]);
1479}
1480
1481static inline struct page *linear_to_page(struct page *page, unsigned int *len,
1482 unsigned int *offset,
1483 struct sk_buff *skb, struct sock *sk)
1484{
1485 struct page *p = sk->sk_sndmsg_page;
1486 unsigned int off;
1487
1488 if (!p) {
1489new_page:
1490 p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0);
1491 if (!p)
1492 return NULL;
1493
1494 off = sk->sk_sndmsg_off = 0;
1495 /* hold one ref to this page until it's full */
1496 } else {
1497 unsigned int mlen;
1498
1499 off = sk->sk_sndmsg_off;
1500 mlen = PAGE_SIZE - off;
1501 if (mlen < 64 && mlen < *len) {
1502 put_page(p);
1503 goto new_page;
1504 }
1505
1506 *len = min_t(unsigned int, *len, mlen);
1507 }
1508
1509 memcpy(page_address(p) + off, page_address(page) + *offset, *len);
1510 sk->sk_sndmsg_off += *len;
1511 *offset = off;
1512 get_page(p);
1513
1514 return p;
1515}
1516
1517/*
1518 * Fill page/offset/length into spd, if it can hold more pages.
1519 */
1520static inline int spd_fill_page(struct splice_pipe_desc *spd,
1521 struct pipe_inode_info *pipe, struct page *page,
1522 unsigned int *len, unsigned int offset,
1523 struct sk_buff *skb, int linear,
1524 struct sock *sk)
1525{
1526 if (unlikely(spd->nr_pages == pipe->buffers))
1527 return 1;
1528
1529 if (linear) {
1530 page = linear_to_page(page, len, &offset, skb, sk);
1531 if (!page)
1532 return 1;
1533 } else
1534 get_page(page);
1535
1536 spd->pages[spd->nr_pages] = page;
1537 spd->partial[spd->nr_pages].len = *len;
1538 spd->partial[spd->nr_pages].offset = offset;
1539 spd->nr_pages++;
1540
1541 return 0;
1542}
1543
1544static inline void __segment_seek(struct page **page, unsigned int *poff,
1545 unsigned int *plen, unsigned int off)
1546{
1547 unsigned long n;
1548
1549 *poff += off;
1550 n = *poff / PAGE_SIZE;
1551 if (n)
1552 *page = nth_page(*page, n);
1553
1554 *poff = *poff % PAGE_SIZE;
1555 *plen -= off;
1556}
1557
1558static inline int __splice_segment(struct page *page, unsigned int poff,
1559 unsigned int plen, unsigned int *off,
1560 unsigned int *len, struct sk_buff *skb,
1561 struct splice_pipe_desc *spd, int linear,
1562 struct sock *sk,
1563 struct pipe_inode_info *pipe)
1564{
1565 if (!*len)
1566 return 1;
1567
1568 /* skip this segment if already processed */
1569 if (*off >= plen) {
1570 *off -= plen;
1571 return 0;
1572 }
1573
1574 /* ignore any bits we already processed */
1575 if (*off) {
1576 __segment_seek(&page, &poff, &plen, *off);
1577 *off = 0;
1578 }
1579
1580 do {
1581 unsigned int flen = min(*len, plen);
1582
1583 /* the linear region may spread across several pages */
1584 flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
1585
1586 if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
1587 return 1;
1588
1589 __segment_seek(&page, &poff, &plen, flen);
1590 *len -= flen;
1591
1592 } while (*len && plen);
1593
1594 return 0;
1595}
1596
1597/*
1598 * Map linear and fragment data from the skb to spd. It reports failure if the
1599 * pipe is full or if we already spliced the requested length.
1600 */
1601static int __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
1602 unsigned int *offset, unsigned int *len,
1603 struct splice_pipe_desc *spd, struct sock *sk)
1604{
1605 int seg;
1606
1607 /*
1608 * map the linear part
1609 */
1610 if (__splice_segment(virt_to_page(skb->data),
1611 (unsigned long) skb->data & (PAGE_SIZE - 1),
1612 skb_headlen(skb),
1613 offset, len, skb, spd, 1, sk, pipe))
1614 return 1;
1615
1616 /*
1617 * then map the fragments
1618 */
1619 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1620 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1621
1622 if (__splice_segment(f->page, f->page_offset, f->size,
1623 offset, len, skb, spd, 0, sk, pipe))
1624 return 1;
1625 }
1626
1627 return 0;
1628}
1629
1630/*
1631 * Map data from the skb to a pipe. Should handle both the linear part,
1632 * the fragments, and the frag list. It does NOT handle frag lists within
1633 * the frag list, if such a thing exists. We'd probably need to recurse to
1634 * handle that cleanly.
1635 */
1636int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
1637 struct pipe_inode_info *pipe, unsigned int tlen,
1638 unsigned int flags)
1639{
1640 struct partial_page partial[PIPE_DEF_BUFFERS];
1641 struct page *pages[PIPE_DEF_BUFFERS];
1642 struct splice_pipe_desc spd = {
1643 .pages = pages,
1644 .partial = partial,
1645 .flags = flags,
1646 .ops = &sock_pipe_buf_ops,
1647 .spd_release = sock_spd_release,
1648 };
1649 struct sk_buff *frag_iter;
1650 struct sock *sk = skb->sk;
1651 int ret = 0;
1652
1653 if (splice_grow_spd(pipe, &spd))
1654 return -ENOMEM;
1655
1656 /*
1657 * __skb_splice_bits() only fails if the output has no room left,
1658 * so no point in going over the frag_list for the error case.
1659 */
1660 if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
1661 goto done;
1662 else if (!tlen)
1663 goto done;
1664
1665 /*
1666 * now see if we have a frag_list to map
1667 */
1668 skb_walk_frags(skb, frag_iter) {
1669 if (!tlen)
1670 break;
1671 if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
1672 break;
1673 }
1674
1675done:
1676 if (spd.nr_pages) {
1677 /*
1678 * Drop the socket lock, otherwise we have reverse
1679 * locking dependencies between sk_lock and i_mutex
1680 * here as compared to sendfile(). We enter here
1681 * with the socket lock held, and splice_to_pipe() will
1682 * grab the pipe inode lock. For sendfile() emulation,
1683 * we call into ->sendpage() with the i_mutex lock held
1684 * and networking will grab the socket lock.
1685 */
1686 release_sock(sk);
1687 ret = splice_to_pipe(pipe, &spd);
1688 lock_sock(sk);
1689 }
1690
1691 splice_shrink_spd(pipe, &spd);
1692 return ret;
1693}
1694
1695/**
1696 * skb_store_bits - store bits from kernel buffer to skb
1697 * @skb: destination buffer
1698 * @offset: offset in destination
1699 * @from: source buffer
1700 * @len: number of bytes to copy
1701 *
1702 * Copy the specified number of bytes from the source buffer to the
1703 * destination skb. This function handles all the messy bits of
1704 * traversing fragment lists and such.
1705 */
1706
1707int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1708{
1709 int start = skb_headlen(skb);
1710 struct sk_buff *frag_iter;
1711 int i, copy;
1712
1713 if (offset > (int)skb->len - len)
1714 goto fault;
1715
1716 if ((copy = start - offset) > 0) {
1717 if (copy > len)
1718 copy = len;
1719 skb_copy_to_linear_data_offset(skb, offset, from, copy);
1720 if ((len -= copy) == 0)
1721 return 0;
1722 offset += copy;
1723 from += copy;
1724 }
1725
1726 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1727 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1728 int end;
1729
1730 WARN_ON(start > offset + len);
1731
1732 end = start + frag->size;
1733 if ((copy = end - offset) > 0) {
1734 u8 *vaddr;
1735
1736 if (copy > len)
1737 copy = len;
1738
1739 vaddr = kmap_skb_frag(frag);
1740 memcpy(vaddr + frag->page_offset + offset - start,
1741 from, copy);
1742 kunmap_skb_frag(vaddr);
1743
1744 if ((len -= copy) == 0)
1745 return 0;
1746 offset += copy;
1747 from += copy;
1748 }
1749 start = end;
1750 }
1751
1752 skb_walk_frags(skb, frag_iter) {
1753 int end;
1754
1755 WARN_ON(start > offset + len);
1756
1757 end = start + frag_iter->len;
1758 if ((copy = end - offset) > 0) {
1759 if (copy > len)
1760 copy = len;
1761 if (skb_store_bits(frag_iter, offset - start,
1762 from, copy))
1763 goto fault;
1764 if ((len -= copy) == 0)
1765 return 0;
1766 offset += copy;
1767 from += copy;
1768 }
1769 start = end;
1770 }
1771 if (!len)
1772 return 0;
1773
1774fault:
1775 return -EFAULT;
1776}
1777EXPORT_SYMBOL(skb_store_bits);
1778
1779/* Checksum skb data. */
1780
1781__wsum skb_checksum(const struct sk_buff *skb, int offset,
1782 int len, __wsum csum)
1783{
1784 int start = skb_headlen(skb);
1785 int i, copy = start - offset;
1786 struct sk_buff *frag_iter;
1787 int pos = 0;
1788
1789 /* Checksum header. */
1790 if (copy > 0) {
1791 if (copy > len)
1792 copy = len;
1793 csum = csum_partial(skb->data + offset, copy, csum);
1794 if ((len -= copy) == 0)
1795 return csum;
1796 offset += copy;
1797 pos = copy;
1798 }
1799
1800 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1801 int end;
1802
1803 WARN_ON(start > offset + len);
1804
1805 end = start + skb_shinfo(skb)->frags[i].size;
1806 if ((copy = end - offset) > 0) {
1807 __wsum csum2;
1808 u8 *vaddr;
1809 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1810
1811 if (copy > len)
1812 copy = len;
1813 vaddr = kmap_skb_frag(frag);
1814 csum2 = csum_partial(vaddr + frag->page_offset +
1815 offset - start, copy, 0);
1816 kunmap_skb_frag(vaddr);
1817 csum = csum_block_add(csum, csum2, pos);
1818 if (!(len -= copy))
1819 return csum;
1820 offset += copy;
1821 pos += copy;
1822 }
1823 start = end;
1824 }
1825
1826 skb_walk_frags(skb, frag_iter) {
1827 int end;
1828
1829 WARN_ON(start > offset + len);
1830
1831 end = start + frag_iter->len;
1832 if ((copy = end - offset) > 0) {
1833 __wsum csum2;
1834 if (copy > len)
1835 copy = len;
1836 csum2 = skb_checksum(frag_iter, offset - start,
1837 copy, 0);
1838 csum = csum_block_add(csum, csum2, pos);
1839 if ((len -= copy) == 0)
1840 return csum;
1841 offset += copy;
1842 pos += copy;
1843 }
1844 start = end;
1845 }
1846 BUG_ON(len);
1847
1848 return csum;
1849}
1850EXPORT_SYMBOL(skb_checksum);
1851
1852/* Both of above in one bottle. */
1853
1854__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1855 u8 *to, int len, __wsum csum)
1856{
1857 int start = skb_headlen(skb);
1858 int i, copy = start - offset;
1859 struct sk_buff *frag_iter;
1860 int pos = 0;
1861
1862 /* Copy header. */
1863 if (copy > 0) {
1864 if (copy > len)
1865 copy = len;
1866 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1867 copy, csum);
1868 if ((len -= copy) == 0)
1869 return csum;
1870 offset += copy;
1871 to += copy;
1872 pos = copy;
1873 }
1874
1875 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1876 int end;
1877
1878 WARN_ON(start > offset + len);
1879
1880 end = start + skb_shinfo(skb)->frags[i].size;
1881 if ((copy = end - offset) > 0) {
1882 __wsum csum2;
1883 u8 *vaddr;
1884 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1885
1886 if (copy > len)
1887 copy = len;
1888 vaddr = kmap_skb_frag(frag);
1889 csum2 = csum_partial_copy_nocheck(vaddr +
1890 frag->page_offset +
1891 offset - start, to,
1892 copy, 0);
1893 kunmap_skb_frag(vaddr);
1894 csum = csum_block_add(csum, csum2, pos);
1895 if (!(len -= copy))
1896 return csum;
1897 offset += copy;
1898 to += copy;
1899 pos += copy;
1900 }
1901 start = end;
1902 }
1903
1904 skb_walk_frags(skb, frag_iter) {
1905 __wsum csum2;
1906 int end;
1907
1908 WARN_ON(start > offset + len);
1909
1910 end = start + frag_iter->len;
1911 if ((copy = end - offset) > 0) {
1912 if (copy > len)
1913 copy = len;
1914 csum2 = skb_copy_and_csum_bits(frag_iter,
1915 offset - start,
1916 to, copy, 0);
1917 csum = csum_block_add(csum, csum2, pos);
1918 if ((len -= copy) == 0)
1919 return csum;
1920 offset += copy;
1921 to += copy;
1922 pos += copy;
1923 }
1924 start = end;
1925 }
1926 BUG_ON(len);
1927 return csum;
1928}
1929EXPORT_SYMBOL(skb_copy_and_csum_bits);
1930
1931void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
1932{
1933 __wsum csum;
1934 long csstart;
1935
1936 if (skb->ip_summed == CHECKSUM_PARTIAL)
1937 csstart = skb_checksum_start_offset(skb);
1938 else
1939 csstart = skb_headlen(skb);
1940
1941 BUG_ON(csstart > skb_headlen(skb));
1942
1943 skb_copy_from_linear_data(skb, to, csstart);
1944
1945 csum = 0;
1946 if (csstart != skb->len)
1947 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
1948 skb->len - csstart, 0);
1949
1950 if (skb->ip_summed == CHECKSUM_PARTIAL) {
1951 long csstuff = csstart + skb->csum_offset;
1952
1953 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
1954 }
1955}
1956EXPORT_SYMBOL(skb_copy_and_csum_dev);
1957
1958/**
1959 * skb_dequeue - remove from the head of the queue
1960 * @list: list to dequeue from
1961 *
1962 * Remove the head of the list. The list lock is taken so the function
1963 * may be used safely with other locking list functions. The head item is
1964 * returned or %NULL if the list is empty.
1965 */
1966
1967struct sk_buff *skb_dequeue(struct sk_buff_head *list)
1968{
1969 unsigned long flags;
1970 struct sk_buff *result;
1971
1972 spin_lock_irqsave(&list->lock, flags);
1973 result = __skb_dequeue(list);
1974 spin_unlock_irqrestore(&list->lock, flags);
1975 return result;
1976}
1977EXPORT_SYMBOL(skb_dequeue);
1978
1979/**
1980 * skb_dequeue_tail - remove from the tail of the queue
1981 * @list: list to dequeue from
1982 *
1983 * Remove the tail of the list. The list lock is taken so the function
1984 * may be used safely with other locking list functions. The tail item is
1985 * returned or %NULL if the list is empty.
1986 */
1987struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
1988{
1989 unsigned long flags;
1990 struct sk_buff *result;
1991
1992 spin_lock_irqsave(&list->lock, flags);
1993 result = __skb_dequeue_tail(list);
1994 spin_unlock_irqrestore(&list->lock, flags);
1995 return result;
1996}
1997EXPORT_SYMBOL(skb_dequeue_tail);
1998
1999/**
2000 * skb_queue_purge - empty a list
2001 * @list: list to empty
2002 *
2003 * Delete all buffers on an &sk_buff list. Each buffer is removed from
2004 * the list and one reference dropped. This function takes the list
2005 * lock and is atomic with respect to other list locking functions.
2006 */
2007void skb_queue_purge(struct sk_buff_head *list)
2008{
2009 struct sk_buff *skb;
2010 while ((skb = skb_dequeue(list)) != NULL)
2011 kfree_skb(skb);
2012}
2013EXPORT_SYMBOL(skb_queue_purge);
2014
2015/**
2016 * skb_queue_head - queue a buffer at the list head
2017 * @list: list to use
2018 * @newsk: buffer to queue
2019 *
2020 * Queue a buffer at the start of the list. This function takes the
2021 * list lock and can be used safely with other locking &sk_buff functions
2022 * safely.
2023 *
2024 * A buffer cannot be placed on two lists at the same time.
2025 */
2026void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
2027{
2028 unsigned long flags;
2029
2030 spin_lock_irqsave(&list->lock, flags);
2031 __skb_queue_head(list, newsk);
2032 spin_unlock_irqrestore(&list->lock, flags);
2033}
2034EXPORT_SYMBOL(skb_queue_head);
2035
2036/**
2037 * skb_queue_tail - queue a buffer at the list tail
2038 * @list: list to use
2039 * @newsk: buffer to queue
2040 *
2041 * Queue a buffer at the tail of the list. This function takes the
2042 * list lock and can be used safely with other locking &sk_buff functions
2043 * safely.
2044 *
2045 * A buffer cannot be placed on two lists at the same time.
2046 */
2047void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
2048{
2049 unsigned long flags;
2050
2051 spin_lock_irqsave(&list->lock, flags);
2052 __skb_queue_tail(list, newsk);
2053 spin_unlock_irqrestore(&list->lock, flags);
2054}
2055EXPORT_SYMBOL(skb_queue_tail);
2056
2057/**
2058 * skb_unlink - remove a buffer from a list
2059 * @skb: buffer to remove
2060 * @list: list to use
2061 *
2062 * Remove a packet from a list. The list locks are taken and this
2063 * function is atomic with respect to other list locked calls
2064 *
2065 * You must know what list the SKB is on.
2066 */
2067void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
2068{
2069 unsigned long flags;
2070
2071 spin_lock_irqsave(&list->lock, flags);
2072 __skb_unlink(skb, list);
2073 spin_unlock_irqrestore(&list->lock, flags);
2074}
2075EXPORT_SYMBOL(skb_unlink);
2076
2077/**
2078 * skb_append - append a buffer
2079 * @old: buffer to insert after
2080 * @newsk: buffer to insert
2081 * @list: list to use
2082 *
2083 * Place a packet after a given packet in a list. The list locks are taken
2084 * and this function is atomic with respect to other list locked calls.
2085 * A buffer cannot be placed on two lists at the same time.
2086 */
2087void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2088{
2089 unsigned long flags;
2090
2091 spin_lock_irqsave(&list->lock, flags);
2092 __skb_queue_after(list, old, newsk);
2093 spin_unlock_irqrestore(&list->lock, flags);
2094}
2095EXPORT_SYMBOL(skb_append);
2096
2097/**
2098 * skb_insert - insert a buffer
2099 * @old: buffer to insert before
2100 * @newsk: buffer to insert
2101 * @list: list to use
2102 *
2103 * Place a packet before a given packet in a list. The list locks are
2104 * taken and this function is atomic with respect to other list locked
2105 * calls.
2106 *
2107 * A buffer cannot be placed on two lists at the same time.
2108 */
2109void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2110{
2111 unsigned long flags;
2112
2113 spin_lock_irqsave(&list->lock, flags);
2114 __skb_insert(newsk, old->prev, old, list);
2115 spin_unlock_irqrestore(&list->lock, flags);
2116}
2117EXPORT_SYMBOL(skb_insert);
2118
2119static inline void skb_split_inside_header(struct sk_buff *skb,
2120 struct sk_buff* skb1,
2121 const u32 len, const int pos)
2122{
2123 int i;
2124
2125 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2126 pos - len);
2127 /* And move data appendix as is. */
2128 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2129 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2130
2131 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2132 skb_shinfo(skb)->nr_frags = 0;
2133 skb1->data_len = skb->data_len;
2134 skb1->len += skb1->data_len;
2135 skb->data_len = 0;
2136 skb->len = len;
2137 skb_set_tail_pointer(skb, len);
2138}
2139
2140static inline void skb_split_no_header(struct sk_buff *skb,
2141 struct sk_buff* skb1,
2142 const u32 len, int pos)
2143{
2144 int i, k = 0;
2145 const int nfrags = skb_shinfo(skb)->nr_frags;
2146
2147 skb_shinfo(skb)->nr_frags = 0;
2148 skb1->len = skb1->data_len = skb->len - len;
2149 skb->len = len;
2150 skb->data_len = len - pos;
2151
2152 for (i = 0; i < nfrags; i++) {
2153 int size = skb_shinfo(skb)->frags[i].size;
2154
2155 if (pos + size > len) {
2156 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2157
2158 if (pos < len) {
2159 /* Split frag.
2160 * We have two variants in this case:
2161 * 1. Move all the frag to the second
2162 * part, if it is possible. F.e.
2163 * this approach is mandatory for TUX,
2164 * where splitting is expensive.
2165 * 2. Split is accurately. We make this.
2166 */
2167 get_page(skb_shinfo(skb)->frags[i].page);
2168 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2169 skb_shinfo(skb1)->frags[0].size -= len - pos;
2170 skb_shinfo(skb)->frags[i].size = len - pos;
2171 skb_shinfo(skb)->nr_frags++;
2172 }
2173 k++;
2174 } else
2175 skb_shinfo(skb)->nr_frags++;
2176 pos += size;
2177 }
2178 skb_shinfo(skb1)->nr_frags = k;
2179}
2180
2181/**
2182 * skb_split - Split fragmented skb to two parts at length len.
2183 * @skb: the buffer to split
2184 * @skb1: the buffer to receive the second part
2185 * @len: new length for skb
2186 */
2187void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2188{
2189 int pos = skb_headlen(skb);
2190
2191 if (len < pos) /* Split line is inside header. */
2192 skb_split_inside_header(skb, skb1, len, pos);
2193 else /* Second chunk has no header, nothing to copy. */
2194 skb_split_no_header(skb, skb1, len, pos);
2195}
2196EXPORT_SYMBOL(skb_split);
2197
2198/* Shifting from/to a cloned skb is a no-go.
2199 *
2200 * Caller cannot keep skb_shinfo related pointers past calling here!
2201 */
2202static int skb_prepare_for_shift(struct sk_buff *skb)
2203{
2204 return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2205}
2206
2207/**
2208 * skb_shift - Shifts paged data partially from skb to another
2209 * @tgt: buffer into which tail data gets added
2210 * @skb: buffer from which the paged data comes from
2211 * @shiftlen: shift up to this many bytes
2212 *
2213 * Attempts to shift up to shiftlen worth of bytes, which may be less than
2214 * the length of the skb, from tgt to skb. Returns number bytes shifted.
2215 * It's up to caller to free skb if everything was shifted.
2216 *
2217 * If @tgt runs out of frags, the whole operation is aborted.
2218 *
2219 * Skb cannot include anything else but paged data while tgt is allowed
2220 * to have non-paged data as well.
2221 *
2222 * TODO: full sized shift could be optimized but that would need
2223 * specialized skb free'er to handle frags without up-to-date nr_frags.
2224 */
2225int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2226{
2227 int from, to, merge, todo;
2228 struct skb_frag_struct *fragfrom, *fragto;
2229
2230 BUG_ON(shiftlen > skb->len);
2231 BUG_ON(skb_headlen(skb)); /* Would corrupt stream */
2232
2233 todo = shiftlen;
2234 from = 0;
2235 to = skb_shinfo(tgt)->nr_frags;
2236 fragfrom = &skb_shinfo(skb)->frags[from];
2237
2238 /* Actual merge is delayed until the point when we know we can
2239 * commit all, so that we don't have to undo partial changes
2240 */
2241 if (!to ||
2242 !skb_can_coalesce(tgt, to, fragfrom->page, fragfrom->page_offset)) {
2243 merge = -1;
2244 } else {
2245 merge = to - 1;
2246
2247 todo -= fragfrom->size;
2248 if (todo < 0) {
2249 if (skb_prepare_for_shift(skb) ||
2250 skb_prepare_for_shift(tgt))
2251 return 0;
2252
2253 /* All previous frag pointers might be stale! */
2254 fragfrom = &skb_shinfo(skb)->frags[from];
2255 fragto = &skb_shinfo(tgt)->frags[merge];
2256
2257 fragto->size += shiftlen;
2258 fragfrom->size -= shiftlen;
2259 fragfrom->page_offset += shiftlen;
2260
2261 goto onlymerged;
2262 }
2263
2264 from++;
2265 }
2266
2267 /* Skip full, not-fitting skb to avoid expensive operations */
2268 if ((shiftlen == skb->len) &&
2269 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2270 return 0;
2271
2272 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2273 return 0;
2274
2275 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2276 if (to == MAX_SKB_FRAGS)
2277 return 0;
2278
2279 fragfrom = &skb_shinfo(skb)->frags[from];
2280 fragto = &skb_shinfo(tgt)->frags[to];
2281
2282 if (todo >= fragfrom->size) {
2283 *fragto = *fragfrom;
2284 todo -= fragfrom->size;
2285 from++;
2286 to++;
2287
2288 } else {
2289 get_page(fragfrom->page);
2290 fragto->page = fragfrom->page;
2291 fragto->page_offset = fragfrom->page_offset;
2292 fragto->size = todo;
2293
2294 fragfrom->page_offset += todo;
2295 fragfrom->size -= todo;
2296 todo = 0;
2297
2298 to++;
2299 break;
2300 }
2301 }
2302
2303 /* Ready to "commit" this state change to tgt */
2304 skb_shinfo(tgt)->nr_frags = to;
2305
2306 if (merge >= 0) {
2307 fragfrom = &skb_shinfo(skb)->frags[0];
2308 fragto = &skb_shinfo(tgt)->frags[merge];
2309
2310 fragto->size += fragfrom->size;
2311 put_page(fragfrom->page);
2312 }
2313
2314 /* Reposition in the original skb */
2315 to = 0;
2316 while (from < skb_shinfo(skb)->nr_frags)
2317 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2318 skb_shinfo(skb)->nr_frags = to;
2319
2320 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2321
2322onlymerged:
2323 /* Most likely the tgt won't ever need its checksum anymore, skb on
2324 * the other hand might need it if it needs to be resent
2325 */
2326 tgt->ip_summed = CHECKSUM_PARTIAL;
2327 skb->ip_summed = CHECKSUM_PARTIAL;
2328
2329 /* Yak, is it really working this way? Some helper please? */
2330 skb->len -= shiftlen;
2331 skb->data_len -= shiftlen;
2332 skb->truesize -= shiftlen;
2333 tgt->len += shiftlen;
2334 tgt->data_len += shiftlen;
2335 tgt->truesize += shiftlen;
2336
2337 return shiftlen;
2338}
2339
2340/**
2341 * skb_prepare_seq_read - Prepare a sequential read of skb data
2342 * @skb: the buffer to read
2343 * @from: lower offset of data to be read
2344 * @to: upper offset of data to be read
2345 * @st: state variable
2346 *
2347 * Initializes the specified state variable. Must be called before
2348 * invoking skb_seq_read() for the first time.
2349 */
2350void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2351 unsigned int to, struct skb_seq_state *st)
2352{
2353 st->lower_offset = from;
2354 st->upper_offset = to;
2355 st->root_skb = st->cur_skb = skb;
2356 st->frag_idx = st->stepped_offset = 0;
2357 st->frag_data = NULL;
2358}
2359EXPORT_SYMBOL(skb_prepare_seq_read);
2360
2361/**
2362 * skb_seq_read - Sequentially read skb data
2363 * @consumed: number of bytes consumed by the caller so far
2364 * @data: destination pointer for data to be returned
2365 * @st: state variable
2366 *
2367 * Reads a block of skb data at &consumed relative to the
2368 * lower offset specified to skb_prepare_seq_read(). Assigns
2369 * the head of the data block to &data and returns the length
2370 * of the block or 0 if the end of the skb data or the upper
2371 * offset has been reached.
2372 *
2373 * The caller is not required to consume all of the data
2374 * returned, i.e. &consumed is typically set to the number
2375 * of bytes already consumed and the next call to
2376 * skb_seq_read() will return the remaining part of the block.
2377 *
2378 * Note 1: The size of each block of data returned can be arbitrary,
2379 * this limitation is the cost for zerocopy seqeuental
2380 * reads of potentially non linear data.
2381 *
2382 * Note 2: Fragment lists within fragments are not implemented
2383 * at the moment, state->root_skb could be replaced with
2384 * a stack for this purpose.
2385 */
2386unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2387 struct skb_seq_state *st)
2388{
2389 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2390 skb_frag_t *frag;
2391
2392 if (unlikely(abs_offset >= st->upper_offset))
2393 return 0;
2394
2395next_skb:
2396 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2397
2398 if (abs_offset < block_limit && !st->frag_data) {
2399 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2400 return block_limit - abs_offset;
2401 }
2402
2403 if (st->frag_idx == 0 && !st->frag_data)
2404 st->stepped_offset += skb_headlen(st->cur_skb);
2405
2406 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2407 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2408 block_limit = frag->size + st->stepped_offset;
2409
2410 if (abs_offset < block_limit) {
2411 if (!st->frag_data)
2412 st->frag_data = kmap_skb_frag(frag);
2413
2414 *data = (u8 *) st->frag_data + frag->page_offset +
2415 (abs_offset - st->stepped_offset);
2416
2417 return block_limit - abs_offset;
2418 }
2419
2420 if (st->frag_data) {
2421 kunmap_skb_frag(st->frag_data);
2422 st->frag_data = NULL;
2423 }
2424
2425 st->frag_idx++;
2426 st->stepped_offset += frag->size;
2427 }
2428
2429 if (st->frag_data) {
2430 kunmap_skb_frag(st->frag_data);
2431 st->frag_data = NULL;
2432 }
2433
2434 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
2435 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2436 st->frag_idx = 0;
2437 goto next_skb;
2438 } else if (st->cur_skb->next) {
2439 st->cur_skb = st->cur_skb->next;
2440 st->frag_idx = 0;
2441 goto next_skb;
2442 }
2443
2444 return 0;
2445}
2446EXPORT_SYMBOL(skb_seq_read);
2447
2448/**
2449 * skb_abort_seq_read - Abort a sequential read of skb data
2450 * @st: state variable
2451 *
2452 * Must be called if skb_seq_read() was not called until it
2453 * returned 0.
2454 */
2455void skb_abort_seq_read(struct skb_seq_state *st)
2456{
2457 if (st->frag_data)
2458 kunmap_skb_frag(st->frag_data);
2459}
2460EXPORT_SYMBOL(skb_abort_seq_read);
2461
2462#define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
2463
2464static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2465 struct ts_config *conf,
2466 struct ts_state *state)
2467{
2468 return skb_seq_read(offset, text, TS_SKB_CB(state));
2469}
2470
2471static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2472{
2473 skb_abort_seq_read(TS_SKB_CB(state));
2474}
2475
2476/**
2477 * skb_find_text - Find a text pattern in skb data
2478 * @skb: the buffer to look in
2479 * @from: search offset
2480 * @to: search limit
2481 * @config: textsearch configuration
2482 * @state: uninitialized textsearch state variable
2483 *
2484 * Finds a pattern in the skb data according to the specified
2485 * textsearch configuration. Use textsearch_next() to retrieve
2486 * subsequent occurrences of the pattern. Returns the offset
2487 * to the first occurrence or UINT_MAX if no match was found.
2488 */
2489unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2490 unsigned int to, struct ts_config *config,
2491 struct ts_state *state)
2492{
2493 unsigned int ret;
2494
2495 config->get_next_block = skb_ts_get_next_block;
2496 config->finish = skb_ts_finish;
2497
2498 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
2499
2500 ret = textsearch_find(config, state);
2501 return (ret <= to - from ? ret : UINT_MAX);
2502}
2503EXPORT_SYMBOL(skb_find_text);
2504
2505/**
2506 * skb_append_datato_frags: - append the user data to a skb
2507 * @sk: sock structure
2508 * @skb: skb structure to be appened with user data.
2509 * @getfrag: call back function to be used for getting the user data
2510 * @from: pointer to user message iov
2511 * @length: length of the iov message
2512 *
2513 * Description: This procedure append the user data in the fragment part
2514 * of the skb if any page alloc fails user this procedure returns -ENOMEM
2515 */
2516int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2517 int (*getfrag)(void *from, char *to, int offset,
2518 int len, int odd, struct sk_buff *skb),
2519 void *from, int length)
2520{
2521 int frg_cnt = 0;
2522 skb_frag_t *frag = NULL;
2523 struct page *page = NULL;
2524 int copy, left;
2525 int offset = 0;
2526 int ret;
2527
2528 do {
2529 /* Return error if we don't have space for new frag */
2530 frg_cnt = skb_shinfo(skb)->nr_frags;
2531 if (frg_cnt >= MAX_SKB_FRAGS)
2532 return -EFAULT;
2533
2534 /* allocate a new page for next frag */
2535 page = alloc_pages(sk->sk_allocation, 0);
2536
2537 /* If alloc_page fails just return failure and caller will
2538 * free previous allocated pages by doing kfree_skb()
2539 */
2540 if (page == NULL)
2541 return -ENOMEM;
2542
2543 /* initialize the next frag */
2544 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
2545 skb->truesize += PAGE_SIZE;
2546 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
2547
2548 /* get the new initialized frag */
2549 frg_cnt = skb_shinfo(skb)->nr_frags;
2550 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
2551
2552 /* copy the user data to page */
2553 left = PAGE_SIZE - frag->page_offset;
2554 copy = (length > left)? left : length;
2555
2556 ret = getfrag(from, (page_address(frag->page) +
2557 frag->page_offset + frag->size),
2558 offset, copy, 0, skb);
2559 if (ret < 0)
2560 return -EFAULT;
2561
2562 /* copy was successful so update the size parameters */
2563 frag->size += copy;
2564 skb->len += copy;
2565 skb->data_len += copy;
2566 offset += copy;
2567 length -= copy;
2568
2569 } while (length > 0);
2570
2571 return 0;
2572}
2573EXPORT_SYMBOL(skb_append_datato_frags);
2574
2575/**
2576 * skb_pull_rcsum - pull skb and update receive checksum
2577 * @skb: buffer to update
2578 * @len: length of data pulled
2579 *
2580 * This function performs an skb_pull on the packet and updates
2581 * the CHECKSUM_COMPLETE checksum. It should be used on
2582 * receive path processing instead of skb_pull unless you know
2583 * that the checksum difference is zero (e.g., a valid IP header)
2584 * or you are setting ip_summed to CHECKSUM_NONE.
2585 */
2586unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
2587{
2588 BUG_ON(len > skb->len);
2589 skb->len -= len;
2590 BUG_ON(skb->len < skb->data_len);
2591 skb_postpull_rcsum(skb, skb->data, len);
2592 return skb->data += len;
2593}
2594EXPORT_SYMBOL_GPL(skb_pull_rcsum);
2595
2596/**
2597 * skb_segment - Perform protocol segmentation on skb.
2598 * @skb: buffer to segment
2599 * @features: features for the output path (see dev->features)
2600 *
2601 * This function performs segmentation on the given skb. It returns
2602 * a pointer to the first in a list of new skbs for the segments.
2603 * In case of error it returns ERR_PTR(err).
2604 */
2605struct sk_buff *skb_segment(struct sk_buff *skb, u32 features)
2606{
2607 struct sk_buff *segs = NULL;
2608 struct sk_buff *tail = NULL;
2609 struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
2610 unsigned int mss = skb_shinfo(skb)->gso_size;
2611 unsigned int doffset = skb->data - skb_mac_header(skb);
2612 unsigned int offset = doffset;
2613 unsigned int headroom;
2614 unsigned int len;
2615 int sg = !!(features & NETIF_F_SG);
2616 int nfrags = skb_shinfo(skb)->nr_frags;
2617 int err = -ENOMEM;
2618 int i = 0;
2619 int pos;
2620
2621 __skb_push(skb, doffset);
2622 headroom = skb_headroom(skb);
2623 pos = skb_headlen(skb);
2624
2625 do {
2626 struct sk_buff *nskb;
2627 skb_frag_t *frag;
2628 int hsize;
2629 int size;
2630
2631 len = skb->len - offset;
2632 if (len > mss)
2633 len = mss;
2634
2635 hsize = skb_headlen(skb) - offset;
2636 if (hsize < 0)
2637 hsize = 0;
2638 if (hsize > len || !sg)
2639 hsize = len;
2640
2641 if (!hsize && i >= nfrags) {
2642 BUG_ON(fskb->len != len);
2643
2644 pos += len;
2645 nskb = skb_clone(fskb, GFP_ATOMIC);
2646 fskb = fskb->next;
2647
2648 if (unlikely(!nskb))
2649 goto err;
2650
2651 hsize = skb_end_pointer(nskb) - nskb->head;
2652 if (skb_cow_head(nskb, doffset + headroom)) {
2653 kfree_skb(nskb);
2654 goto err;
2655 }
2656
2657 nskb->truesize += skb_end_pointer(nskb) - nskb->head -
2658 hsize;
2659 skb_release_head_state(nskb);
2660 __skb_push(nskb, doffset);
2661 } else {
2662 nskb = alloc_skb(hsize + doffset + headroom,
2663 GFP_ATOMIC);
2664
2665 if (unlikely(!nskb))
2666 goto err;
2667
2668 skb_reserve(nskb, headroom);
2669 __skb_put(nskb, doffset);
2670 }
2671
2672 if (segs)
2673 tail->next = nskb;
2674 else
2675 segs = nskb;
2676 tail = nskb;
2677
2678 __copy_skb_header(nskb, skb);
2679 nskb->mac_len = skb->mac_len;
2680
2681 /* nskb and skb might have different headroom */
2682 if (nskb->ip_summed == CHECKSUM_PARTIAL)
2683 nskb->csum_start += skb_headroom(nskb) - headroom;
2684
2685 skb_reset_mac_header(nskb);
2686 skb_set_network_header(nskb, skb->mac_len);
2687 nskb->transport_header = (nskb->network_header +
2688 skb_network_header_len(skb));
2689 skb_copy_from_linear_data(skb, nskb->data, doffset);
2690
2691 if (fskb != skb_shinfo(skb)->frag_list)
2692 continue;
2693
2694 if (!sg) {
2695 nskb->ip_summed = CHECKSUM_NONE;
2696 nskb->csum = skb_copy_and_csum_bits(skb, offset,
2697 skb_put(nskb, len),
2698 len, 0);
2699 continue;
2700 }
2701
2702 frag = skb_shinfo(nskb)->frags;
2703
2704 skb_copy_from_linear_data_offset(skb, offset,
2705 skb_put(nskb, hsize), hsize);
2706
2707 while (pos < offset + len && i < nfrags) {
2708 *frag = skb_shinfo(skb)->frags[i];
2709 get_page(frag->page);
2710 size = frag->size;
2711
2712 if (pos < offset) {
2713 frag->page_offset += offset - pos;
2714 frag->size -= offset - pos;
2715 }
2716
2717 skb_shinfo(nskb)->nr_frags++;
2718
2719 if (pos + size <= offset + len) {
2720 i++;
2721 pos += size;
2722 } else {
2723 frag->size -= pos + size - (offset + len);
2724 goto skip_fraglist;
2725 }
2726
2727 frag++;
2728 }
2729
2730 if (pos < offset + len) {
2731 struct sk_buff *fskb2 = fskb;
2732
2733 BUG_ON(pos + fskb->len != offset + len);
2734
2735 pos += fskb->len;
2736 fskb = fskb->next;
2737
2738 if (fskb2->next) {
2739 fskb2 = skb_clone(fskb2, GFP_ATOMIC);
2740 if (!fskb2)
2741 goto err;
2742 } else
2743 skb_get(fskb2);
2744
2745 SKB_FRAG_ASSERT(nskb);
2746 skb_shinfo(nskb)->frag_list = fskb2;
2747 }
2748
2749skip_fraglist:
2750 nskb->data_len = len - hsize;
2751 nskb->len += nskb->data_len;
2752 nskb->truesize += nskb->data_len;
2753 } while ((offset += len) < skb->len);
2754
2755 return segs;
2756
2757err:
2758 while ((skb = segs)) {
2759 segs = skb->next;
2760 kfree_skb(skb);
2761 }
2762 return ERR_PTR(err);
2763}
2764EXPORT_SYMBOL_GPL(skb_segment);
2765
2766int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2767{
2768 struct sk_buff *p = *head;
2769 struct sk_buff *nskb;
2770 struct skb_shared_info *skbinfo = skb_shinfo(skb);
2771 struct skb_shared_info *pinfo = skb_shinfo(p);
2772 unsigned int headroom;
2773 unsigned int len = skb_gro_len(skb);
2774 unsigned int offset = skb_gro_offset(skb);
2775 unsigned int headlen = skb_headlen(skb);
2776
2777 if (p->len + len >= 65536)
2778 return -E2BIG;
2779
2780 if (pinfo->frag_list)
2781 goto merge;
2782 else if (headlen <= offset) {
2783 skb_frag_t *frag;
2784 skb_frag_t *frag2;
2785 int i = skbinfo->nr_frags;
2786 int nr_frags = pinfo->nr_frags + i;
2787
2788 offset -= headlen;
2789
2790 if (nr_frags > MAX_SKB_FRAGS)
2791 return -E2BIG;
2792
2793 pinfo->nr_frags = nr_frags;
2794 skbinfo->nr_frags = 0;
2795
2796 frag = pinfo->frags + nr_frags;
2797 frag2 = skbinfo->frags + i;
2798 do {
2799 *--frag = *--frag2;
2800 } while (--i);
2801
2802 frag->page_offset += offset;
2803 frag->size -= offset;
2804
2805 skb->truesize -= skb->data_len;
2806 skb->len -= skb->data_len;
2807 skb->data_len = 0;
2808
2809 NAPI_GRO_CB(skb)->free = 1;
2810 goto done;
2811 } else if (skb_gro_len(p) != pinfo->gso_size)
2812 return -E2BIG;
2813
2814 headroom = skb_headroom(p);
2815 nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
2816 if (unlikely(!nskb))
2817 return -ENOMEM;
2818
2819 __copy_skb_header(nskb, p);
2820 nskb->mac_len = p->mac_len;
2821
2822 skb_reserve(nskb, headroom);
2823 __skb_put(nskb, skb_gro_offset(p));
2824
2825 skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
2826 skb_set_network_header(nskb, skb_network_offset(p));
2827 skb_set_transport_header(nskb, skb_transport_offset(p));
2828
2829 __skb_pull(p, skb_gro_offset(p));
2830 memcpy(skb_mac_header(nskb), skb_mac_header(p),
2831 p->data - skb_mac_header(p));
2832
2833 *NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p);
2834 skb_shinfo(nskb)->frag_list = p;
2835 skb_shinfo(nskb)->gso_size = pinfo->gso_size;
2836 pinfo->gso_size = 0;
2837 skb_header_release(p);
2838 nskb->prev = p;
2839
2840 nskb->data_len += p->len;
2841 nskb->truesize += p->len;
2842 nskb->len += p->len;
2843
2844 *head = nskb;
2845 nskb->next = p->next;
2846 p->next = NULL;
2847
2848 p = nskb;
2849
2850merge:
2851 if (offset > headlen) {
2852 unsigned int eat = offset - headlen;
2853
2854 skbinfo->frags[0].page_offset += eat;
2855 skbinfo->frags[0].size -= eat;
2856 skb->data_len -= eat;
2857 skb->len -= eat;
2858 offset = headlen;
2859 }
2860
2861 __skb_pull(skb, offset);
2862
2863 p->prev->next = skb;
2864 p->prev = skb;
2865 skb_header_release(skb);
2866
2867done:
2868 NAPI_GRO_CB(p)->count++;
2869 p->data_len += len;
2870 p->truesize += len;
2871 p->len += len;
2872
2873 NAPI_GRO_CB(skb)->same_flow = 1;
2874 return 0;
2875}
2876EXPORT_SYMBOL_GPL(skb_gro_receive);
2877
2878void __init skb_init(void)
2879{
2880 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
2881 sizeof(struct sk_buff),
2882 0,
2883 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2884 NULL);
2885 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
2886 (2*sizeof(struct sk_buff)) +
2887 sizeof(atomic_t),
2888 0,
2889 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2890 NULL);
2891}
2892
2893/**
2894 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
2895 * @skb: Socket buffer containing the buffers to be mapped
2896 * @sg: The scatter-gather list to map into
2897 * @offset: The offset into the buffer's contents to start mapping
2898 * @len: Length of buffer space to be mapped
2899 *
2900 * Fill the specified scatter-gather list with mappings/pointers into a
2901 * region of the buffer space attached to a socket buffer.
2902 */
2903static int
2904__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2905{
2906 int start = skb_headlen(skb);
2907 int i, copy = start - offset;
2908 struct sk_buff *frag_iter;
2909 int elt = 0;
2910
2911 if (copy > 0) {
2912 if (copy > len)
2913 copy = len;
2914 sg_set_buf(sg, skb->data + offset, copy);
2915 elt++;
2916 if ((len -= copy) == 0)
2917 return elt;
2918 offset += copy;
2919 }
2920
2921 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2922 int end;
2923
2924 WARN_ON(start > offset + len);
2925
2926 end = start + skb_shinfo(skb)->frags[i].size;
2927 if ((copy = end - offset) > 0) {
2928 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2929
2930 if (copy > len)
2931 copy = len;
2932 sg_set_page(&sg[elt], frag->page, copy,
2933 frag->page_offset+offset-start);
2934 elt++;
2935 if (!(len -= copy))
2936 return elt;
2937 offset += copy;
2938 }
2939 start = end;
2940 }
2941
2942 skb_walk_frags(skb, frag_iter) {
2943 int end;
2944
2945 WARN_ON(start > offset + len);
2946
2947 end = start + frag_iter->len;
2948 if ((copy = end - offset) > 0) {
2949 if (copy > len)
2950 copy = len;
2951 elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
2952 copy);
2953 if ((len -= copy) == 0)
2954 return elt;
2955 offset += copy;
2956 }
2957 start = end;
2958 }
2959 BUG_ON(len);
2960 return elt;
2961}
2962
2963int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2964{
2965 int nsg = __skb_to_sgvec(skb, sg, offset, len);
2966
2967 sg_mark_end(&sg[nsg - 1]);
2968
2969 return nsg;
2970}
2971EXPORT_SYMBOL_GPL(skb_to_sgvec);
2972
2973/**
2974 * skb_cow_data - Check that a socket buffer's data buffers are writable
2975 * @skb: The socket buffer to check.
2976 * @tailbits: Amount of trailing space to be added
2977 * @trailer: Returned pointer to the skb where the @tailbits space begins
2978 *
2979 * Make sure that the data buffers attached to a socket buffer are
2980 * writable. If they are not, private copies are made of the data buffers
2981 * and the socket buffer is set to use these instead.
2982 *
2983 * If @tailbits is given, make sure that there is space to write @tailbits
2984 * bytes of data beyond current end of socket buffer. @trailer will be
2985 * set to point to the skb in which this space begins.
2986 *
2987 * The number of scatterlist elements required to completely map the
2988 * COW'd and extended socket buffer will be returned.
2989 */
2990int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
2991{
2992 int copyflag;
2993 int elt;
2994 struct sk_buff *skb1, **skb_p;
2995
2996 /* If skb is cloned or its head is paged, reallocate
2997 * head pulling out all the pages (pages are considered not writable
2998 * at the moment even if they are anonymous).
2999 */
3000 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
3001 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
3002 return -ENOMEM;
3003
3004 /* Easy case. Most of packets will go this way. */
3005 if (!skb_has_frag_list(skb)) {
3006 /* A little of trouble, not enough of space for trailer.
3007 * This should not happen, when stack is tuned to generate
3008 * good frames. OK, on miss we reallocate and reserve even more
3009 * space, 128 bytes is fair. */
3010
3011 if (skb_tailroom(skb) < tailbits &&
3012 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
3013 return -ENOMEM;
3014
3015 /* Voila! */
3016 *trailer = skb;
3017 return 1;
3018 }
3019
3020 /* Misery. We are in troubles, going to mincer fragments... */
3021
3022 elt = 1;
3023 skb_p = &skb_shinfo(skb)->frag_list;
3024 copyflag = 0;
3025
3026 while ((skb1 = *skb_p) != NULL) {
3027 int ntail = 0;
3028
3029 /* The fragment is partially pulled by someone,
3030 * this can happen on input. Copy it and everything
3031 * after it. */
3032
3033 if (skb_shared(skb1))
3034 copyflag = 1;
3035
3036 /* If the skb is the last, worry about trailer. */
3037
3038 if (skb1->next == NULL && tailbits) {
3039 if (skb_shinfo(skb1)->nr_frags ||
3040 skb_has_frag_list(skb1) ||
3041 skb_tailroom(skb1) < tailbits)
3042 ntail = tailbits + 128;
3043 }
3044
3045 if (copyflag ||
3046 skb_cloned(skb1) ||
3047 ntail ||
3048 skb_shinfo(skb1)->nr_frags ||
3049 skb_has_frag_list(skb1)) {
3050 struct sk_buff *skb2;
3051
3052 /* Fuck, we are miserable poor guys... */
3053 if (ntail == 0)
3054 skb2 = skb_copy(skb1, GFP_ATOMIC);
3055 else
3056 skb2 = skb_copy_expand(skb1,
3057 skb_headroom(skb1),
3058 ntail,
3059 GFP_ATOMIC);
3060 if (unlikely(skb2 == NULL))
3061 return -ENOMEM;
3062
3063 if (skb1->sk)
3064 skb_set_owner_w(skb2, skb1->sk);
3065
3066 /* Looking around. Are we still alive?
3067 * OK, link new skb, drop old one */
3068
3069 skb2->next = skb1->next;
3070 *skb_p = skb2;
3071 kfree_skb(skb1);
3072 skb1 = skb2;
3073 }
3074 elt++;
3075 *trailer = skb1;
3076 skb_p = &skb1->next;
3077 }
3078
3079 return elt;
3080}
3081EXPORT_SYMBOL_GPL(skb_cow_data);
3082
3083static void sock_rmem_free(struct sk_buff *skb)
3084{
3085 struct sock *sk = skb->sk;
3086
3087 atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
3088}
3089
3090/*
3091 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
3092 */
3093int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
3094{
3095 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
3096 (unsigned)sk->sk_rcvbuf)
3097 return -ENOMEM;
3098
3099 skb_orphan(skb);
3100 skb->sk = sk;
3101 skb->destructor = sock_rmem_free;
3102 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
3103
3104 /* before exiting rcu section, make sure dst is refcounted */
3105 skb_dst_force(skb);
3106
3107 skb_queue_tail(&sk->sk_error_queue, skb);
3108 if (!sock_flag(sk, SOCK_DEAD))
3109 sk->sk_data_ready(sk, skb->len);
3110 return 0;
3111}
3112EXPORT_SYMBOL(sock_queue_err_skb);
3113
3114void skb_tstamp_tx(struct sk_buff *orig_skb,
3115 struct skb_shared_hwtstamps *hwtstamps)
3116{
3117 struct sock *sk = orig_skb->sk;
3118 struct sock_exterr_skb *serr;
3119 struct sk_buff *skb;
3120 int err;
3121
3122 if (!sk)
3123 return;
3124
3125 skb = skb_clone(orig_skb, GFP_ATOMIC);
3126 if (!skb)
3127 return;
3128
3129 if (hwtstamps) {
3130 *skb_hwtstamps(skb) =
3131 *hwtstamps;
3132 } else {
3133 /*
3134 * no hardware time stamps available,
3135 * so keep the shared tx_flags and only
3136 * store software time stamp
3137 */
3138 skb->tstamp = ktime_get_real();
3139 }
3140
3141 serr = SKB_EXT_ERR(skb);
3142 memset(serr, 0, sizeof(*serr));
3143 serr->ee.ee_errno = ENOMSG;
3144 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3145
3146 err = sock_queue_err_skb(sk, skb);
3147
3148 if (err)
3149 kfree_skb(skb);
3150}
3151EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3152
3153
3154/**
3155 * skb_partial_csum_set - set up and verify partial csum values for packet
3156 * @skb: the skb to set
3157 * @start: the number of bytes after skb->data to start checksumming.
3158 * @off: the offset from start to place the checksum.
3159 *
3160 * For untrusted partially-checksummed packets, we need to make sure the values
3161 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3162 *
3163 * This function checks and sets those values and skb->ip_summed: if this
3164 * returns false you should drop the packet.
3165 */
3166bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3167{
3168 if (unlikely(start > skb_headlen(skb)) ||
3169 unlikely((int)start + off > skb_headlen(skb) - 2)) {
3170 if (net_ratelimit())
3171 printk(KERN_WARNING
3172 "bad partial csum: csum=%u/%u len=%u\n",
3173 start, off, skb_headlen(skb));
3174 return false;
3175 }
3176 skb->ip_summed = CHECKSUM_PARTIAL;
3177 skb->csum_start = skb_headroom(skb) + start;
3178 skb->csum_offset = off;
3179 return true;
3180}
3181EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3182
3183void __skb_warn_lro_forwarding(const struct sk_buff *skb)
3184{
3185 if (net_ratelimit())
3186 pr_warning("%s: received packets cannot be forwarded"
3187 " while LRO is enabled\n", skb->dev->name);
3188}
3189EXPORT_SYMBOL(__skb_warn_lro_forwarding);
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Routines having to do with the 'struct sk_buff' memory handlers.
4 *
5 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
6 * Florian La Roche <rzsfl@rz.uni-sb.de>
7 *
8 * Fixes:
9 * Alan Cox : Fixed the worst of the load
10 * balancer bugs.
11 * Dave Platt : Interrupt stacking fix.
12 * Richard Kooijman : Timestamp fixes.
13 * Alan Cox : Changed buffer format.
14 * Alan Cox : destructor hook for AF_UNIX etc.
15 * Linus Torvalds : Better skb_clone.
16 * Alan Cox : Added skb_copy.
17 * Alan Cox : Added all the changed routines Linus
18 * only put in the headers
19 * Ray VanTassle : Fixed --skb->lock in free
20 * Alan Cox : skb_copy copy arp field
21 * Andi Kleen : slabified it.
22 * Robert Olsson : Removed skb_head_pool
23 *
24 * NOTE:
25 * The __skb_ routines should be called with interrupts
26 * disabled, or you better be *real* sure that the operation is atomic
27 * with respect to whatever list is being frobbed (e.g. via lock_sock()
28 * or via disabling bottom half handlers, etc).
29 */
30
31/*
32 * The functions in this file will not compile correctly with gcc 2.4.x
33 */
34
35#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
36
37#include <linux/module.h>
38#include <linux/types.h>
39#include <linux/kernel.h>
40#include <linux/mm.h>
41#include <linux/interrupt.h>
42#include <linux/in.h>
43#include <linux/inet.h>
44#include <linux/slab.h>
45#include <linux/tcp.h>
46#include <linux/udp.h>
47#include <linux/sctp.h>
48#include <linux/netdevice.h>
49#ifdef CONFIG_NET_CLS_ACT
50#include <net/pkt_sched.h>
51#endif
52#include <linux/string.h>
53#include <linux/skbuff.h>
54#include <linux/skbuff_ref.h>
55#include <linux/splice.h>
56#include <linux/cache.h>
57#include <linux/rtnetlink.h>
58#include <linux/init.h>
59#include <linux/scatterlist.h>
60#include <linux/errqueue.h>
61#include <linux/prefetch.h>
62#include <linux/bitfield.h>
63#include <linux/if_vlan.h>
64#include <linux/mpls.h>
65#include <linux/kcov.h>
66#include <linux/iov_iter.h>
67
68#include <net/protocol.h>
69#include <net/dst.h>
70#include <net/sock.h>
71#include <net/checksum.h>
72#include <net/gro.h>
73#include <net/gso.h>
74#include <net/hotdata.h>
75#include <net/ip6_checksum.h>
76#include <net/xfrm.h>
77#include <net/mpls.h>
78#include <net/mptcp.h>
79#include <net/mctp.h>
80#include <net/page_pool/helpers.h>
81#include <net/dropreason.h>
82
83#include <linux/uaccess.h>
84#include <trace/events/skb.h>
85#include <linux/highmem.h>
86#include <linux/capability.h>
87#include <linux/user_namespace.h>
88#include <linux/indirect_call_wrapper.h>
89#include <linux/textsearch.h>
90
91#include "dev.h"
92#include "netmem_priv.h"
93#include "sock_destructor.h"
94
95#ifdef CONFIG_SKB_EXTENSIONS
96static struct kmem_cache *skbuff_ext_cache __ro_after_init;
97#endif
98
99#define GRO_MAX_HEAD_PAD (GRO_MAX_HEAD + NET_SKB_PAD + NET_IP_ALIGN)
100#define SKB_SMALL_HEAD_SIZE SKB_HEAD_ALIGN(max(MAX_TCP_HEADER, \
101 GRO_MAX_HEAD_PAD))
102
103/* We want SKB_SMALL_HEAD_CACHE_SIZE to not be a power of two.
104 * This should ensure that SKB_SMALL_HEAD_HEADROOM is a unique
105 * size, and we can differentiate heads from skb_small_head_cache
106 * vs system slabs by looking at their size (skb_end_offset()).
107 */
108#define SKB_SMALL_HEAD_CACHE_SIZE \
109 (is_power_of_2(SKB_SMALL_HEAD_SIZE) ? \
110 (SKB_SMALL_HEAD_SIZE + L1_CACHE_BYTES) : \
111 SKB_SMALL_HEAD_SIZE)
112
113#define SKB_SMALL_HEAD_HEADROOM \
114 SKB_WITH_OVERHEAD(SKB_SMALL_HEAD_CACHE_SIZE)
115
116/* kcm_write_msgs() relies on casting paged frags to bio_vec to use
117 * iov_iter_bvec(). These static asserts ensure the cast is valid is long as the
118 * netmem is a page.
119 */
120static_assert(offsetof(struct bio_vec, bv_page) ==
121 offsetof(skb_frag_t, netmem));
122static_assert(sizeof_field(struct bio_vec, bv_page) ==
123 sizeof_field(skb_frag_t, netmem));
124
125static_assert(offsetof(struct bio_vec, bv_len) == offsetof(skb_frag_t, len));
126static_assert(sizeof_field(struct bio_vec, bv_len) ==
127 sizeof_field(skb_frag_t, len));
128
129static_assert(offsetof(struct bio_vec, bv_offset) ==
130 offsetof(skb_frag_t, offset));
131static_assert(sizeof_field(struct bio_vec, bv_offset) ==
132 sizeof_field(skb_frag_t, offset));
133
134#undef FN
135#define FN(reason) [SKB_DROP_REASON_##reason] = #reason,
136static const char * const drop_reasons[] = {
137 [SKB_CONSUMED] = "CONSUMED",
138 DEFINE_DROP_REASON(FN, FN)
139};
140
141static const struct drop_reason_list drop_reasons_core = {
142 .reasons = drop_reasons,
143 .n_reasons = ARRAY_SIZE(drop_reasons),
144};
145
146const struct drop_reason_list __rcu *
147drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM] = {
148 [SKB_DROP_REASON_SUBSYS_CORE] = RCU_INITIALIZER(&drop_reasons_core),
149};
150EXPORT_SYMBOL(drop_reasons_by_subsys);
151
152/**
153 * drop_reasons_register_subsys - register another drop reason subsystem
154 * @subsys: the subsystem to register, must not be the core
155 * @list: the list of drop reasons within the subsystem, must point to
156 * a statically initialized list
157 */
158void drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,
159 const struct drop_reason_list *list)
160{
161 if (WARN(subsys <= SKB_DROP_REASON_SUBSYS_CORE ||
162 subsys >= ARRAY_SIZE(drop_reasons_by_subsys),
163 "invalid subsystem %d\n", subsys))
164 return;
165
166 /* must point to statically allocated memory, so INIT is OK */
167 RCU_INIT_POINTER(drop_reasons_by_subsys[subsys], list);
168}
169EXPORT_SYMBOL_GPL(drop_reasons_register_subsys);
170
171/**
172 * drop_reasons_unregister_subsys - unregister a drop reason subsystem
173 * @subsys: the subsystem to remove, must not be the core
174 *
175 * Note: This will synchronize_rcu() to ensure no users when it returns.
176 */
177void drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys)
178{
179 if (WARN(subsys <= SKB_DROP_REASON_SUBSYS_CORE ||
180 subsys >= ARRAY_SIZE(drop_reasons_by_subsys),
181 "invalid subsystem %d\n", subsys))
182 return;
183
184 RCU_INIT_POINTER(drop_reasons_by_subsys[subsys], NULL);
185
186 synchronize_rcu();
187}
188EXPORT_SYMBOL_GPL(drop_reasons_unregister_subsys);
189
190/**
191 * skb_panic - private function for out-of-line support
192 * @skb: buffer
193 * @sz: size
194 * @addr: address
195 * @msg: skb_over_panic or skb_under_panic
196 *
197 * Out-of-line support for skb_put() and skb_push().
198 * Called via the wrapper skb_over_panic() or skb_under_panic().
199 * Keep out of line to prevent kernel bloat.
200 * __builtin_return_address is not used because it is not always reliable.
201 */
202static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
203 const char msg[])
204{
205 pr_emerg("%s: text:%px len:%d put:%d head:%px data:%px tail:%#lx end:%#lx dev:%s\n",
206 msg, addr, skb->len, sz, skb->head, skb->data,
207 (unsigned long)skb->tail, (unsigned long)skb->end,
208 skb->dev ? skb->dev->name : "<NULL>");
209 BUG();
210}
211
212static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
213{
214 skb_panic(skb, sz, addr, __func__);
215}
216
217static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
218{
219 skb_panic(skb, sz, addr, __func__);
220}
221
222#define NAPI_SKB_CACHE_SIZE 64
223#define NAPI_SKB_CACHE_BULK 16
224#define NAPI_SKB_CACHE_HALF (NAPI_SKB_CACHE_SIZE / 2)
225
226#if PAGE_SIZE == SZ_4K
227
228#define NAPI_HAS_SMALL_PAGE_FRAG 1
229#define NAPI_SMALL_PAGE_PFMEMALLOC(nc) ((nc).pfmemalloc)
230
231/* specialized page frag allocator using a single order 0 page
232 * and slicing it into 1K sized fragment. Constrained to systems
233 * with a very limited amount of 1K fragments fitting a single
234 * page - to avoid excessive truesize underestimation
235 */
236
237struct page_frag_1k {
238 void *va;
239 u16 offset;
240 bool pfmemalloc;
241};
242
243static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp)
244{
245 struct page *page;
246 int offset;
247
248 offset = nc->offset - SZ_1K;
249 if (likely(offset >= 0))
250 goto use_frag;
251
252 page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
253 if (!page)
254 return NULL;
255
256 nc->va = page_address(page);
257 nc->pfmemalloc = page_is_pfmemalloc(page);
258 offset = PAGE_SIZE - SZ_1K;
259 page_ref_add(page, offset / SZ_1K);
260
261use_frag:
262 nc->offset = offset;
263 return nc->va + offset;
264}
265#else
266
267/* the small page is actually unused in this build; add dummy helpers
268 * to please the compiler and avoid later preprocessor's conditionals
269 */
270#define NAPI_HAS_SMALL_PAGE_FRAG 0
271#define NAPI_SMALL_PAGE_PFMEMALLOC(nc) false
272
273struct page_frag_1k {
274};
275
276static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp_mask)
277{
278 return NULL;
279}
280
281#endif
282
283struct napi_alloc_cache {
284 local_lock_t bh_lock;
285 struct page_frag_cache page;
286 struct page_frag_1k page_small;
287 unsigned int skb_count;
288 void *skb_cache[NAPI_SKB_CACHE_SIZE];
289};
290
291static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
292static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache) = {
293 .bh_lock = INIT_LOCAL_LOCK(bh_lock),
294};
295
296/* Double check that napi_get_frags() allocates skbs with
297 * skb->head being backed by slab, not a page fragment.
298 * This is to make sure bug fixed in 3226b158e67c
299 * ("net: avoid 32 x truesize under-estimation for tiny skbs")
300 * does not accidentally come back.
301 */
302void napi_get_frags_check(struct napi_struct *napi)
303{
304 struct sk_buff *skb;
305
306 local_bh_disable();
307 skb = napi_get_frags(napi);
308 WARN_ON_ONCE(!NAPI_HAS_SMALL_PAGE_FRAG && skb && skb->head_frag);
309 napi_free_frags(napi);
310 local_bh_enable();
311}
312
313void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
314{
315 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
316 void *data;
317
318 fragsz = SKB_DATA_ALIGN(fragsz);
319
320 local_lock_nested_bh(&napi_alloc_cache.bh_lock);
321 data = __page_frag_alloc_align(&nc->page, fragsz,
322 GFP_ATOMIC | __GFP_NOWARN, align_mask);
323 local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
324 return data;
325
326}
327EXPORT_SYMBOL(__napi_alloc_frag_align);
328
329void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
330{
331 void *data;
332
333 if (in_hardirq() || irqs_disabled()) {
334 struct page_frag_cache *nc = this_cpu_ptr(&netdev_alloc_cache);
335
336 fragsz = SKB_DATA_ALIGN(fragsz);
337 data = __page_frag_alloc_align(nc, fragsz,
338 GFP_ATOMIC | __GFP_NOWARN,
339 align_mask);
340 } else {
341 local_bh_disable();
342 data = __napi_alloc_frag_align(fragsz, align_mask);
343 local_bh_enable();
344 }
345 return data;
346}
347EXPORT_SYMBOL(__netdev_alloc_frag_align);
348
349static struct sk_buff *napi_skb_cache_get(void)
350{
351 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
352 struct sk_buff *skb;
353
354 local_lock_nested_bh(&napi_alloc_cache.bh_lock);
355 if (unlikely(!nc->skb_count)) {
356 nc->skb_count = kmem_cache_alloc_bulk(net_hotdata.skbuff_cache,
357 GFP_ATOMIC | __GFP_NOWARN,
358 NAPI_SKB_CACHE_BULK,
359 nc->skb_cache);
360 if (unlikely(!nc->skb_count)) {
361 local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
362 return NULL;
363 }
364 }
365
366 skb = nc->skb_cache[--nc->skb_count];
367 local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
368 kasan_mempool_unpoison_object(skb, kmem_cache_size(net_hotdata.skbuff_cache));
369
370 return skb;
371}
372
373static inline void __finalize_skb_around(struct sk_buff *skb, void *data,
374 unsigned int size)
375{
376 struct skb_shared_info *shinfo;
377
378 size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
379
380 /* Assumes caller memset cleared SKB */
381 skb->truesize = SKB_TRUESIZE(size);
382 refcount_set(&skb->users, 1);
383 skb->head = data;
384 skb->data = data;
385 skb_reset_tail_pointer(skb);
386 skb_set_end_offset(skb, size);
387 skb->mac_header = (typeof(skb->mac_header))~0U;
388 skb->transport_header = (typeof(skb->transport_header))~0U;
389 skb->alloc_cpu = raw_smp_processor_id();
390 /* make sure we initialize shinfo sequentially */
391 shinfo = skb_shinfo(skb);
392 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
393 atomic_set(&shinfo->dataref, 1);
394
395 skb_set_kcov_handle(skb, kcov_common_handle());
396}
397
398static inline void *__slab_build_skb(struct sk_buff *skb, void *data,
399 unsigned int *size)
400{
401 void *resized;
402
403 /* Must find the allocation size (and grow it to match). */
404 *size = ksize(data);
405 /* krealloc() will immediately return "data" when
406 * "ksize(data)" is requested: it is the existing upper
407 * bounds. As a result, GFP_ATOMIC will be ignored. Note
408 * that this "new" pointer needs to be passed back to the
409 * caller for use so the __alloc_size hinting will be
410 * tracked correctly.
411 */
412 resized = krealloc(data, *size, GFP_ATOMIC);
413 WARN_ON_ONCE(resized != data);
414 return resized;
415}
416
417/* build_skb() variant which can operate on slab buffers.
418 * Note that this should be used sparingly as slab buffers
419 * cannot be combined efficiently by GRO!
420 */
421struct sk_buff *slab_build_skb(void *data)
422{
423 struct sk_buff *skb;
424 unsigned int size;
425
426 skb = kmem_cache_alloc(net_hotdata.skbuff_cache,
427 GFP_ATOMIC | __GFP_NOWARN);
428 if (unlikely(!skb))
429 return NULL;
430
431 memset(skb, 0, offsetof(struct sk_buff, tail));
432 data = __slab_build_skb(skb, data, &size);
433 __finalize_skb_around(skb, data, size);
434
435 return skb;
436}
437EXPORT_SYMBOL(slab_build_skb);
438
439/* Caller must provide SKB that is memset cleared */
440static void __build_skb_around(struct sk_buff *skb, void *data,
441 unsigned int frag_size)
442{
443 unsigned int size = frag_size;
444
445 /* frag_size == 0 is considered deprecated now. Callers
446 * using slab buffer should use slab_build_skb() instead.
447 */
448 if (WARN_ONCE(size == 0, "Use slab_build_skb() instead"))
449 data = __slab_build_skb(skb, data, &size);
450
451 __finalize_skb_around(skb, data, size);
452}
453
454/**
455 * __build_skb - build a network buffer
456 * @data: data buffer provided by caller
457 * @frag_size: size of data (must not be 0)
458 *
459 * Allocate a new &sk_buff. Caller provides space holding head and
460 * skb_shared_info. @data must have been allocated from the page
461 * allocator or vmalloc(). (A @frag_size of 0 to indicate a kmalloc()
462 * allocation is deprecated, and callers should use slab_build_skb()
463 * instead.)
464 * The return is the new skb buffer.
465 * On a failure the return is %NULL, and @data is not freed.
466 * Notes :
467 * Before IO, driver allocates only data buffer where NIC put incoming frame
468 * Driver should add room at head (NET_SKB_PAD) and
469 * MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
470 * After IO, driver calls build_skb(), to allocate sk_buff and populate it
471 * before giving packet to stack.
472 * RX rings only contains data buffers, not full skbs.
473 */
474struct sk_buff *__build_skb(void *data, unsigned int frag_size)
475{
476 struct sk_buff *skb;
477
478 skb = kmem_cache_alloc(net_hotdata.skbuff_cache,
479 GFP_ATOMIC | __GFP_NOWARN);
480 if (unlikely(!skb))
481 return NULL;
482
483 memset(skb, 0, offsetof(struct sk_buff, tail));
484 __build_skb_around(skb, data, frag_size);
485
486 return skb;
487}
488
489/* build_skb() is wrapper over __build_skb(), that specifically
490 * takes care of skb->head and skb->pfmemalloc
491 */
492struct sk_buff *build_skb(void *data, unsigned int frag_size)
493{
494 struct sk_buff *skb = __build_skb(data, frag_size);
495
496 if (likely(skb && frag_size)) {
497 skb->head_frag = 1;
498 skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
499 }
500 return skb;
501}
502EXPORT_SYMBOL(build_skb);
503
504/**
505 * build_skb_around - build a network buffer around provided skb
506 * @skb: sk_buff provide by caller, must be memset cleared
507 * @data: data buffer provided by caller
508 * @frag_size: size of data
509 */
510struct sk_buff *build_skb_around(struct sk_buff *skb,
511 void *data, unsigned int frag_size)
512{
513 if (unlikely(!skb))
514 return NULL;
515
516 __build_skb_around(skb, data, frag_size);
517
518 if (frag_size) {
519 skb->head_frag = 1;
520 skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
521 }
522 return skb;
523}
524EXPORT_SYMBOL(build_skb_around);
525
526/**
527 * __napi_build_skb - build a network buffer
528 * @data: data buffer provided by caller
529 * @frag_size: size of data
530 *
531 * Version of __build_skb() that uses NAPI percpu caches to obtain
532 * skbuff_head instead of inplace allocation.
533 *
534 * Returns a new &sk_buff on success, %NULL on allocation failure.
535 */
536static struct sk_buff *__napi_build_skb(void *data, unsigned int frag_size)
537{
538 struct sk_buff *skb;
539
540 skb = napi_skb_cache_get();
541 if (unlikely(!skb))
542 return NULL;
543
544 memset(skb, 0, offsetof(struct sk_buff, tail));
545 __build_skb_around(skb, data, frag_size);
546
547 return skb;
548}
549
550/**
551 * napi_build_skb - build a network buffer
552 * @data: data buffer provided by caller
553 * @frag_size: size of data
554 *
555 * Version of __napi_build_skb() that takes care of skb->head_frag
556 * and skb->pfmemalloc when the data is a page or page fragment.
557 *
558 * Returns a new &sk_buff on success, %NULL on allocation failure.
559 */
560struct sk_buff *napi_build_skb(void *data, unsigned int frag_size)
561{
562 struct sk_buff *skb = __napi_build_skb(data, frag_size);
563
564 if (likely(skb) && frag_size) {
565 skb->head_frag = 1;
566 skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
567 }
568
569 return skb;
570}
571EXPORT_SYMBOL(napi_build_skb);
572
573/*
574 * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
575 * the caller if emergency pfmemalloc reserves are being used. If it is and
576 * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
577 * may be used. Otherwise, the packet data may be discarded until enough
578 * memory is free
579 */
580static void *kmalloc_reserve(unsigned int *size, gfp_t flags, int node,
581 bool *pfmemalloc)
582{
583 bool ret_pfmemalloc = false;
584 size_t obj_size;
585 void *obj;
586
587 obj_size = SKB_HEAD_ALIGN(*size);
588 if (obj_size <= SKB_SMALL_HEAD_CACHE_SIZE &&
589 !(flags & KMALLOC_NOT_NORMAL_BITS)) {
590 obj = kmem_cache_alloc_node(net_hotdata.skb_small_head_cache,
591 flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
592 node);
593 *size = SKB_SMALL_HEAD_CACHE_SIZE;
594 if (obj || !(gfp_pfmemalloc_allowed(flags)))
595 goto out;
596 /* Try again but now we are using pfmemalloc reserves */
597 ret_pfmemalloc = true;
598 obj = kmem_cache_alloc_node(net_hotdata.skb_small_head_cache, flags, node);
599 goto out;
600 }
601
602 obj_size = kmalloc_size_roundup(obj_size);
603 /* The following cast might truncate high-order bits of obj_size, this
604 * is harmless because kmalloc(obj_size >= 2^32) will fail anyway.
605 */
606 *size = (unsigned int)obj_size;
607
608 /*
609 * Try a regular allocation, when that fails and we're not entitled
610 * to the reserves, fail.
611 */
612 obj = kmalloc_node_track_caller(obj_size,
613 flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
614 node);
615 if (obj || !(gfp_pfmemalloc_allowed(flags)))
616 goto out;
617
618 /* Try again but now we are using pfmemalloc reserves */
619 ret_pfmemalloc = true;
620 obj = kmalloc_node_track_caller(obj_size, flags, node);
621
622out:
623 if (pfmemalloc)
624 *pfmemalloc = ret_pfmemalloc;
625
626 return obj;
627}
628
629/* Allocate a new skbuff. We do this ourselves so we can fill in a few
630 * 'private' fields and also do memory statistics to find all the
631 * [BEEP] leaks.
632 *
633 */
634
635/**
636 * __alloc_skb - allocate a network buffer
637 * @size: size to allocate
638 * @gfp_mask: allocation mask
639 * @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
640 * instead of head cache and allocate a cloned (child) skb.
641 * If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
642 * allocations in case the data is required for writeback
643 * @node: numa node to allocate memory on
644 *
645 * Allocate a new &sk_buff. The returned buffer has no headroom and a
646 * tail room of at least size bytes. The object has a reference count
647 * of one. The return is the buffer. On a failure the return is %NULL.
648 *
649 * Buffers may only be allocated from interrupts using a @gfp_mask of
650 * %GFP_ATOMIC.
651 */
652struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
653 int flags, int node)
654{
655 struct kmem_cache *cache;
656 struct sk_buff *skb;
657 bool pfmemalloc;
658 u8 *data;
659
660 cache = (flags & SKB_ALLOC_FCLONE)
661 ? net_hotdata.skbuff_fclone_cache : net_hotdata.skbuff_cache;
662
663 if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
664 gfp_mask |= __GFP_MEMALLOC;
665
666 /* Get the HEAD */
667 if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI)) == SKB_ALLOC_NAPI &&
668 likely(node == NUMA_NO_NODE || node == numa_mem_id()))
669 skb = napi_skb_cache_get();
670 else
671 skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node);
672 if (unlikely(!skb))
673 return NULL;
674 prefetchw(skb);
675
676 /* We do our best to align skb_shared_info on a separate cache
677 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
678 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
679 * Both skb->head and skb_shared_info are cache line aligned.
680 */
681 data = kmalloc_reserve(&size, gfp_mask, node, &pfmemalloc);
682 if (unlikely(!data))
683 goto nodata;
684 /* kmalloc_size_roundup() might give us more room than requested.
685 * Put skb_shared_info exactly at the end of allocated zone,
686 * to allow max possible filling before reallocation.
687 */
688 prefetchw(data + SKB_WITH_OVERHEAD(size));
689
690 /*
691 * Only clear those fields we need to clear, not those that we will
692 * actually initialise below. Hence, don't put any more fields after
693 * the tail pointer in struct sk_buff!
694 */
695 memset(skb, 0, offsetof(struct sk_buff, tail));
696 __build_skb_around(skb, data, size);
697 skb->pfmemalloc = pfmemalloc;
698
699 if (flags & SKB_ALLOC_FCLONE) {
700 struct sk_buff_fclones *fclones;
701
702 fclones = container_of(skb, struct sk_buff_fclones, skb1);
703
704 skb->fclone = SKB_FCLONE_ORIG;
705 refcount_set(&fclones->fclone_ref, 1);
706 }
707
708 return skb;
709
710nodata:
711 kmem_cache_free(cache, skb);
712 return NULL;
713}
714EXPORT_SYMBOL(__alloc_skb);
715
716/**
717 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
718 * @dev: network device to receive on
719 * @len: length to allocate
720 * @gfp_mask: get_free_pages mask, passed to alloc_skb
721 *
722 * Allocate a new &sk_buff and assign it a usage count of one. The
723 * buffer has NET_SKB_PAD headroom built in. Users should allocate
724 * the headroom they think they need without accounting for the
725 * built in space. The built in space is used for optimisations.
726 *
727 * %NULL is returned if there is no free memory.
728 */
729struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
730 gfp_t gfp_mask)
731{
732 struct page_frag_cache *nc;
733 struct sk_buff *skb;
734 bool pfmemalloc;
735 void *data;
736
737 len += NET_SKB_PAD;
738
739 /* If requested length is either too small or too big,
740 * we use kmalloc() for skb->head allocation.
741 */
742 if (len <= SKB_WITH_OVERHEAD(SKB_SMALL_HEAD_CACHE_SIZE) ||
743 len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
744 (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
745 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
746 if (!skb)
747 goto skb_fail;
748 goto skb_success;
749 }
750
751 len = SKB_HEAD_ALIGN(len);
752
753 if (sk_memalloc_socks())
754 gfp_mask |= __GFP_MEMALLOC;
755
756 if (in_hardirq() || irqs_disabled()) {
757 nc = this_cpu_ptr(&netdev_alloc_cache);
758 data = page_frag_alloc(nc, len, gfp_mask);
759 pfmemalloc = page_frag_cache_is_pfmemalloc(nc);
760 } else {
761 local_bh_disable();
762 local_lock_nested_bh(&napi_alloc_cache.bh_lock);
763
764 nc = this_cpu_ptr(&napi_alloc_cache.page);
765 data = page_frag_alloc(nc, len, gfp_mask);
766 pfmemalloc = page_frag_cache_is_pfmemalloc(nc);
767
768 local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
769 local_bh_enable();
770 }
771
772 if (unlikely(!data))
773 return NULL;
774
775 skb = __build_skb(data, len);
776 if (unlikely(!skb)) {
777 skb_free_frag(data);
778 return NULL;
779 }
780
781 if (pfmemalloc)
782 skb->pfmemalloc = 1;
783 skb->head_frag = 1;
784
785skb_success:
786 skb_reserve(skb, NET_SKB_PAD);
787 skb->dev = dev;
788
789skb_fail:
790 return skb;
791}
792EXPORT_SYMBOL(__netdev_alloc_skb);
793
794/**
795 * napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
796 * @napi: napi instance this buffer was allocated for
797 * @len: length to allocate
798 *
799 * Allocate a new sk_buff for use in NAPI receive. This buffer will
800 * attempt to allocate the head from a special reserved region used
801 * only for NAPI Rx allocation. By doing this we can save several
802 * CPU cycles by avoiding having to disable and re-enable IRQs.
803 *
804 * %NULL is returned if there is no free memory.
805 */
806struct sk_buff *napi_alloc_skb(struct napi_struct *napi, unsigned int len)
807{
808 gfp_t gfp_mask = GFP_ATOMIC | __GFP_NOWARN;
809 struct napi_alloc_cache *nc;
810 struct sk_buff *skb;
811 bool pfmemalloc;
812 void *data;
813
814 DEBUG_NET_WARN_ON_ONCE(!in_softirq());
815 len += NET_SKB_PAD + NET_IP_ALIGN;
816
817 /* If requested length is either too small or too big,
818 * we use kmalloc() for skb->head allocation.
819 * When the small frag allocator is available, prefer it over kmalloc
820 * for small fragments
821 */
822 if ((!NAPI_HAS_SMALL_PAGE_FRAG &&
823 len <= SKB_WITH_OVERHEAD(SKB_SMALL_HEAD_CACHE_SIZE)) ||
824 len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
825 (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
826 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX | SKB_ALLOC_NAPI,
827 NUMA_NO_NODE);
828 if (!skb)
829 goto skb_fail;
830 goto skb_success;
831 }
832
833 if (sk_memalloc_socks())
834 gfp_mask |= __GFP_MEMALLOC;
835
836 local_lock_nested_bh(&napi_alloc_cache.bh_lock);
837 nc = this_cpu_ptr(&napi_alloc_cache);
838 if (NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) {
839 /* we are artificially inflating the allocation size, but
840 * that is not as bad as it may look like, as:
841 * - 'len' less than GRO_MAX_HEAD makes little sense
842 * - On most systems, larger 'len' values lead to fragment
843 * size above 512 bytes
844 * - kmalloc would use the kmalloc-1k slab for such values
845 * - Builds with smaller GRO_MAX_HEAD will very likely do
846 * little networking, as that implies no WiFi and no
847 * tunnels support, and 32 bits arches.
848 */
849 len = SZ_1K;
850
851 data = page_frag_alloc_1k(&nc->page_small, gfp_mask);
852 pfmemalloc = NAPI_SMALL_PAGE_PFMEMALLOC(nc->page_small);
853 } else {
854 len = SKB_HEAD_ALIGN(len);
855
856 data = page_frag_alloc(&nc->page, len, gfp_mask);
857 pfmemalloc = page_frag_cache_is_pfmemalloc(&nc->page);
858 }
859 local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
860
861 if (unlikely(!data))
862 return NULL;
863
864 skb = __napi_build_skb(data, len);
865 if (unlikely(!skb)) {
866 skb_free_frag(data);
867 return NULL;
868 }
869
870 if (pfmemalloc)
871 skb->pfmemalloc = 1;
872 skb->head_frag = 1;
873
874skb_success:
875 skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
876 skb->dev = napi->dev;
877
878skb_fail:
879 return skb;
880}
881EXPORT_SYMBOL(napi_alloc_skb);
882
883void skb_add_rx_frag_netmem(struct sk_buff *skb, int i, netmem_ref netmem,
884 int off, int size, unsigned int truesize)
885{
886 DEBUG_NET_WARN_ON_ONCE(size > truesize);
887
888 skb_fill_netmem_desc(skb, i, netmem, off, size);
889 skb->len += size;
890 skb->data_len += size;
891 skb->truesize += truesize;
892}
893EXPORT_SYMBOL(skb_add_rx_frag_netmem);
894
895void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
896 unsigned int truesize)
897{
898 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
899
900 DEBUG_NET_WARN_ON_ONCE(size > truesize);
901
902 skb_frag_size_add(frag, size);
903 skb->len += size;
904 skb->data_len += size;
905 skb->truesize += truesize;
906}
907EXPORT_SYMBOL(skb_coalesce_rx_frag);
908
909static void skb_drop_list(struct sk_buff **listp)
910{
911 kfree_skb_list(*listp);
912 *listp = NULL;
913}
914
915static inline void skb_drop_fraglist(struct sk_buff *skb)
916{
917 skb_drop_list(&skb_shinfo(skb)->frag_list);
918}
919
920static void skb_clone_fraglist(struct sk_buff *skb)
921{
922 struct sk_buff *list;
923
924 skb_walk_frags(skb, list)
925 skb_get(list);
926}
927
928static bool is_pp_netmem(netmem_ref netmem)
929{
930 return (netmem_get_pp_magic(netmem) & ~0x3UL) == PP_SIGNATURE;
931}
932
933int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
934 unsigned int headroom)
935{
936#if IS_ENABLED(CONFIG_PAGE_POOL)
937 u32 size, truesize, len, max_head_size, off;
938 struct sk_buff *skb = *pskb, *nskb;
939 int err, i, head_off;
940 void *data;
941
942 /* XDP does not support fraglist so we need to linearize
943 * the skb.
944 */
945 if (skb_has_frag_list(skb))
946 return -EOPNOTSUPP;
947
948 max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE - headroom);
949 if (skb->len > max_head_size + MAX_SKB_FRAGS * PAGE_SIZE)
950 return -ENOMEM;
951
952 size = min_t(u32, skb->len, max_head_size);
953 truesize = SKB_HEAD_ALIGN(size) + headroom;
954 data = page_pool_dev_alloc_va(pool, &truesize);
955 if (!data)
956 return -ENOMEM;
957
958 nskb = napi_build_skb(data, truesize);
959 if (!nskb) {
960 page_pool_free_va(pool, data, true);
961 return -ENOMEM;
962 }
963
964 skb_reserve(nskb, headroom);
965 skb_copy_header(nskb, skb);
966 skb_mark_for_recycle(nskb);
967
968 err = skb_copy_bits(skb, 0, nskb->data, size);
969 if (err) {
970 consume_skb(nskb);
971 return err;
972 }
973 skb_put(nskb, size);
974
975 head_off = skb_headroom(nskb) - skb_headroom(skb);
976 skb_headers_offset_update(nskb, head_off);
977
978 off = size;
979 len = skb->len - off;
980 for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
981 struct page *page;
982 u32 page_off;
983
984 size = min_t(u32, len, PAGE_SIZE);
985 truesize = size;
986
987 page = page_pool_dev_alloc(pool, &page_off, &truesize);
988 if (!page) {
989 consume_skb(nskb);
990 return -ENOMEM;
991 }
992
993 skb_add_rx_frag(nskb, i, page, page_off, size, truesize);
994 err = skb_copy_bits(skb, off, page_address(page) + page_off,
995 size);
996 if (err) {
997 consume_skb(nskb);
998 return err;
999 }
1000
1001 len -= size;
1002 off += size;
1003 }
1004
1005 consume_skb(skb);
1006 *pskb = nskb;
1007
1008 return 0;
1009#else
1010 return -EOPNOTSUPP;
1011#endif
1012}
1013EXPORT_SYMBOL(skb_pp_cow_data);
1014
1015int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
1016 struct bpf_prog *prog)
1017{
1018 if (!prog->aux->xdp_has_frags)
1019 return -EINVAL;
1020
1021 return skb_pp_cow_data(pool, pskb, XDP_PACKET_HEADROOM);
1022}
1023EXPORT_SYMBOL(skb_cow_data_for_xdp);
1024
1025#if IS_ENABLED(CONFIG_PAGE_POOL)
1026bool napi_pp_put_page(netmem_ref netmem)
1027{
1028 netmem = netmem_compound_head(netmem);
1029
1030 /* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
1031 * in order to preserve any existing bits, such as bit 0 for the
1032 * head page of compound page and bit 1 for pfmemalloc page, so
1033 * mask those bits for freeing side when doing below checking,
1034 * and page_is_pfmemalloc() is checked in __page_pool_put_page()
1035 * to avoid recycling the pfmemalloc page.
1036 */
1037 if (unlikely(!is_pp_netmem(netmem)))
1038 return false;
1039
1040 page_pool_put_full_netmem(netmem_get_pp(netmem), netmem, false);
1041
1042 return true;
1043}
1044EXPORT_SYMBOL(napi_pp_put_page);
1045#endif
1046
1047static bool skb_pp_recycle(struct sk_buff *skb, void *data)
1048{
1049 if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
1050 return false;
1051 return napi_pp_put_page(page_to_netmem(virt_to_page(data)));
1052}
1053
1054/**
1055 * skb_pp_frag_ref() - Increase fragment references of a page pool aware skb
1056 * @skb: page pool aware skb
1057 *
1058 * Increase the fragment reference count (pp_ref_count) of a skb. This is
1059 * intended to gain fragment references only for page pool aware skbs,
1060 * i.e. when skb->pp_recycle is true, and not for fragments in a
1061 * non-pp-recycling skb. It has a fallback to increase references on normal
1062 * pages, as page pool aware skbs may also have normal page fragments.
1063 */
1064static int skb_pp_frag_ref(struct sk_buff *skb)
1065{
1066 struct skb_shared_info *shinfo;
1067 netmem_ref head_netmem;
1068 int i;
1069
1070 if (!skb->pp_recycle)
1071 return -EINVAL;
1072
1073 shinfo = skb_shinfo(skb);
1074
1075 for (i = 0; i < shinfo->nr_frags; i++) {
1076 head_netmem = netmem_compound_head(shinfo->frags[i].netmem);
1077 if (likely(is_pp_netmem(head_netmem)))
1078 page_pool_ref_netmem(head_netmem);
1079 else
1080 page_ref_inc(netmem_to_page(head_netmem));
1081 }
1082 return 0;
1083}
1084
1085static void skb_kfree_head(void *head, unsigned int end_offset)
1086{
1087 if (end_offset == SKB_SMALL_HEAD_HEADROOM)
1088 kmem_cache_free(net_hotdata.skb_small_head_cache, head);
1089 else
1090 kfree(head);
1091}
1092
1093static void skb_free_head(struct sk_buff *skb)
1094{
1095 unsigned char *head = skb->head;
1096
1097 if (skb->head_frag) {
1098 if (skb_pp_recycle(skb, head))
1099 return;
1100 skb_free_frag(head);
1101 } else {
1102 skb_kfree_head(head, skb_end_offset(skb));
1103 }
1104}
1105
1106static void skb_release_data(struct sk_buff *skb, enum skb_drop_reason reason)
1107{
1108 struct skb_shared_info *shinfo = skb_shinfo(skb);
1109 int i;
1110
1111 if (!skb_data_unref(skb, shinfo))
1112 goto exit;
1113
1114 if (skb_zcopy(skb)) {
1115 bool skip_unref = shinfo->flags & SKBFL_MANAGED_FRAG_REFS;
1116
1117 skb_zcopy_clear(skb, true);
1118 if (skip_unref)
1119 goto free_head;
1120 }
1121
1122 for (i = 0; i < shinfo->nr_frags; i++)
1123 __skb_frag_unref(&shinfo->frags[i], skb->pp_recycle);
1124
1125free_head:
1126 if (shinfo->frag_list)
1127 kfree_skb_list_reason(shinfo->frag_list, reason);
1128
1129 skb_free_head(skb);
1130exit:
1131 /* When we clone an SKB we copy the reycling bit. The pp_recycle
1132 * bit is only set on the head though, so in order to avoid races
1133 * while trying to recycle fragments on __skb_frag_unref() we need
1134 * to make one SKB responsible for triggering the recycle path.
1135 * So disable the recycling bit if an SKB is cloned and we have
1136 * additional references to the fragmented part of the SKB.
1137 * Eventually the last SKB will have the recycling bit set and it's
1138 * dataref set to 0, which will trigger the recycling
1139 */
1140 skb->pp_recycle = 0;
1141}
1142
1143/*
1144 * Free an skbuff by memory without cleaning the state.
1145 */
1146static void kfree_skbmem(struct sk_buff *skb)
1147{
1148 struct sk_buff_fclones *fclones;
1149
1150 switch (skb->fclone) {
1151 case SKB_FCLONE_UNAVAILABLE:
1152 kmem_cache_free(net_hotdata.skbuff_cache, skb);
1153 return;
1154
1155 case SKB_FCLONE_ORIG:
1156 fclones = container_of(skb, struct sk_buff_fclones, skb1);
1157
1158 /* We usually free the clone (TX completion) before original skb
1159 * This test would have no chance to be true for the clone,
1160 * while here, branch prediction will be good.
1161 */
1162 if (refcount_read(&fclones->fclone_ref) == 1)
1163 goto fastpath;
1164 break;
1165
1166 default: /* SKB_FCLONE_CLONE */
1167 fclones = container_of(skb, struct sk_buff_fclones, skb2);
1168 break;
1169 }
1170 if (!refcount_dec_and_test(&fclones->fclone_ref))
1171 return;
1172fastpath:
1173 kmem_cache_free(net_hotdata.skbuff_fclone_cache, fclones);
1174}
1175
1176void skb_release_head_state(struct sk_buff *skb)
1177{
1178 skb_dst_drop(skb);
1179 if (skb->destructor) {
1180 DEBUG_NET_WARN_ON_ONCE(in_hardirq());
1181 skb->destructor(skb);
1182 }
1183#if IS_ENABLED(CONFIG_NF_CONNTRACK)
1184 nf_conntrack_put(skb_nfct(skb));
1185#endif
1186 skb_ext_put(skb);
1187}
1188
1189/* Free everything but the sk_buff shell. */
1190static void skb_release_all(struct sk_buff *skb, enum skb_drop_reason reason)
1191{
1192 skb_release_head_state(skb);
1193 if (likely(skb->head))
1194 skb_release_data(skb, reason);
1195}
1196
1197/**
1198 * __kfree_skb - private function
1199 * @skb: buffer
1200 *
1201 * Free an sk_buff. Release anything attached to the buffer.
1202 * Clean the state. This is an internal helper function. Users should
1203 * always call kfree_skb
1204 */
1205
1206void __kfree_skb(struct sk_buff *skb)
1207{
1208 skb_release_all(skb, SKB_DROP_REASON_NOT_SPECIFIED);
1209 kfree_skbmem(skb);
1210}
1211EXPORT_SYMBOL(__kfree_skb);
1212
1213static __always_inline
1214bool __sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb,
1215 enum skb_drop_reason reason)
1216{
1217 if (unlikely(!skb_unref(skb)))
1218 return false;
1219
1220 DEBUG_NET_WARN_ON_ONCE(reason == SKB_NOT_DROPPED_YET ||
1221 u32_get_bits(reason,
1222 SKB_DROP_REASON_SUBSYS_MASK) >=
1223 SKB_DROP_REASON_SUBSYS_NUM);
1224
1225 if (reason == SKB_CONSUMED)
1226 trace_consume_skb(skb, __builtin_return_address(0));
1227 else
1228 trace_kfree_skb(skb, __builtin_return_address(0), reason, sk);
1229 return true;
1230}
1231
1232/**
1233 * sk_skb_reason_drop - free an sk_buff with special reason
1234 * @sk: the socket to receive @skb, or NULL if not applicable
1235 * @skb: buffer to free
1236 * @reason: reason why this skb is dropped
1237 *
1238 * Drop a reference to the buffer and free it if the usage count has hit
1239 * zero. Meanwhile, pass the receiving socket and drop reason to
1240 * 'kfree_skb' tracepoint.
1241 */
1242void __fix_address
1243sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb, enum skb_drop_reason reason)
1244{
1245 if (__sk_skb_reason_drop(sk, skb, reason))
1246 __kfree_skb(skb);
1247}
1248EXPORT_SYMBOL(sk_skb_reason_drop);
1249
1250#define KFREE_SKB_BULK_SIZE 16
1251
1252struct skb_free_array {
1253 unsigned int skb_count;
1254 void *skb_array[KFREE_SKB_BULK_SIZE];
1255};
1256
1257static void kfree_skb_add_bulk(struct sk_buff *skb,
1258 struct skb_free_array *sa,
1259 enum skb_drop_reason reason)
1260{
1261 /* if SKB is a clone, don't handle this case */
1262 if (unlikely(skb->fclone != SKB_FCLONE_UNAVAILABLE)) {
1263 __kfree_skb(skb);
1264 return;
1265 }
1266
1267 skb_release_all(skb, reason);
1268 sa->skb_array[sa->skb_count++] = skb;
1269
1270 if (unlikely(sa->skb_count == KFREE_SKB_BULK_SIZE)) {
1271 kmem_cache_free_bulk(net_hotdata.skbuff_cache, KFREE_SKB_BULK_SIZE,
1272 sa->skb_array);
1273 sa->skb_count = 0;
1274 }
1275}
1276
1277void __fix_address
1278kfree_skb_list_reason(struct sk_buff *segs, enum skb_drop_reason reason)
1279{
1280 struct skb_free_array sa;
1281
1282 sa.skb_count = 0;
1283
1284 while (segs) {
1285 struct sk_buff *next = segs->next;
1286
1287 if (__sk_skb_reason_drop(NULL, segs, reason)) {
1288 skb_poison_list(segs);
1289 kfree_skb_add_bulk(segs, &sa, reason);
1290 }
1291
1292 segs = next;
1293 }
1294
1295 if (sa.skb_count)
1296 kmem_cache_free_bulk(net_hotdata.skbuff_cache, sa.skb_count, sa.skb_array);
1297}
1298EXPORT_SYMBOL(kfree_skb_list_reason);
1299
1300/* Dump skb information and contents.
1301 *
1302 * Must only be called from net_ratelimit()-ed paths.
1303 *
1304 * Dumps whole packets if full_pkt, only headers otherwise.
1305 */
1306void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt)
1307{
1308 struct skb_shared_info *sh = skb_shinfo(skb);
1309 struct net_device *dev = skb->dev;
1310 struct sock *sk = skb->sk;
1311 struct sk_buff *list_skb;
1312 bool has_mac, has_trans;
1313 int headroom, tailroom;
1314 int i, len, seg_len;
1315
1316 if (full_pkt)
1317 len = skb->len;
1318 else
1319 len = min_t(int, skb->len, MAX_HEADER + 128);
1320
1321 headroom = skb_headroom(skb);
1322 tailroom = skb_tailroom(skb);
1323
1324 has_mac = skb_mac_header_was_set(skb);
1325 has_trans = skb_transport_header_was_set(skb);
1326
1327 printk("%sskb len=%u headroom=%u headlen=%u tailroom=%u\n"
1328 "mac=(%d,%d) mac_len=%u net=(%d,%d) trans=%d\n"
1329 "shinfo(txflags=%u nr_frags=%u gso(size=%hu type=%u segs=%hu))\n"
1330 "csum(0x%x start=%u offset=%u ip_summed=%u complete_sw=%u valid=%u level=%u)\n"
1331 "hash(0x%x sw=%u l4=%u) proto=0x%04x pkttype=%u iif=%d\n"
1332 "priority=0x%x mark=0x%x alloc_cpu=%u vlan_all=0x%x\n"
1333 "encapsulation=%d inner(proto=0x%04x, mac=%u, net=%u, trans=%u)\n",
1334 level, skb->len, headroom, skb_headlen(skb), tailroom,
1335 has_mac ? skb->mac_header : -1,
1336 has_mac ? skb_mac_header_len(skb) : -1,
1337 skb->mac_len,
1338 skb->network_header,
1339 has_trans ? skb_network_header_len(skb) : -1,
1340 has_trans ? skb->transport_header : -1,
1341 sh->tx_flags, sh->nr_frags,
1342 sh->gso_size, sh->gso_type, sh->gso_segs,
1343 skb->csum, skb->csum_start, skb->csum_offset, skb->ip_summed,
1344 skb->csum_complete_sw, skb->csum_valid, skb->csum_level,
1345 skb->hash, skb->sw_hash, skb->l4_hash,
1346 ntohs(skb->protocol), skb->pkt_type, skb->skb_iif,
1347 skb->priority, skb->mark, skb->alloc_cpu, skb->vlan_all,
1348 skb->encapsulation, skb->inner_protocol, skb->inner_mac_header,
1349 skb->inner_network_header, skb->inner_transport_header);
1350
1351 if (dev)
1352 printk("%sdev name=%s feat=%pNF\n",
1353 level, dev->name, &dev->features);
1354 if (sk)
1355 printk("%ssk family=%hu type=%u proto=%u\n",
1356 level, sk->sk_family, sk->sk_type, sk->sk_protocol);
1357
1358 if (full_pkt && headroom)
1359 print_hex_dump(level, "skb headroom: ", DUMP_PREFIX_OFFSET,
1360 16, 1, skb->head, headroom, false);
1361
1362 seg_len = min_t(int, skb_headlen(skb), len);
1363 if (seg_len)
1364 print_hex_dump(level, "skb linear: ", DUMP_PREFIX_OFFSET,
1365 16, 1, skb->data, seg_len, false);
1366 len -= seg_len;
1367
1368 if (full_pkt && tailroom)
1369 print_hex_dump(level, "skb tailroom: ", DUMP_PREFIX_OFFSET,
1370 16, 1, skb_tail_pointer(skb), tailroom, false);
1371
1372 for (i = 0; len && i < skb_shinfo(skb)->nr_frags; i++) {
1373 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1374 u32 p_off, p_len, copied;
1375 struct page *p;
1376 u8 *vaddr;
1377
1378 if (skb_frag_is_net_iov(frag)) {
1379 printk("%sskb frag %d: not readable\n", level, i);
1380 len -= skb_frag_size(frag);
1381 if (!len)
1382 break;
1383 continue;
1384 }
1385
1386 skb_frag_foreach_page(frag, skb_frag_off(frag),
1387 skb_frag_size(frag), p, p_off, p_len,
1388 copied) {
1389 seg_len = min_t(int, p_len, len);
1390 vaddr = kmap_atomic(p);
1391 print_hex_dump(level, "skb frag: ",
1392 DUMP_PREFIX_OFFSET,
1393 16, 1, vaddr + p_off, seg_len, false);
1394 kunmap_atomic(vaddr);
1395 len -= seg_len;
1396 if (!len)
1397 break;
1398 }
1399 }
1400
1401 if (full_pkt && skb_has_frag_list(skb)) {
1402 printk("skb fraglist:\n");
1403 skb_walk_frags(skb, list_skb)
1404 skb_dump(level, list_skb, true);
1405 }
1406}
1407EXPORT_SYMBOL(skb_dump);
1408
1409/**
1410 * skb_tx_error - report an sk_buff xmit error
1411 * @skb: buffer that triggered an error
1412 *
1413 * Report xmit error if a device callback is tracking this skb.
1414 * skb must be freed afterwards.
1415 */
1416void skb_tx_error(struct sk_buff *skb)
1417{
1418 if (skb) {
1419 skb_zcopy_downgrade_managed(skb);
1420 skb_zcopy_clear(skb, true);
1421 }
1422}
1423EXPORT_SYMBOL(skb_tx_error);
1424
1425#ifdef CONFIG_TRACEPOINTS
1426/**
1427 * consume_skb - free an skbuff
1428 * @skb: buffer to free
1429 *
1430 * Drop a ref to the buffer and free it if the usage count has hit zero
1431 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
1432 * is being dropped after a failure and notes that
1433 */
1434void consume_skb(struct sk_buff *skb)
1435{
1436 if (!skb_unref(skb))
1437 return;
1438
1439 trace_consume_skb(skb, __builtin_return_address(0));
1440 __kfree_skb(skb);
1441}
1442EXPORT_SYMBOL(consume_skb);
1443#endif
1444
1445/**
1446 * __consume_stateless_skb - free an skbuff, assuming it is stateless
1447 * @skb: buffer to free
1448 *
1449 * Alike consume_skb(), but this variant assumes that this is the last
1450 * skb reference and all the head states have been already dropped
1451 */
1452void __consume_stateless_skb(struct sk_buff *skb)
1453{
1454 trace_consume_skb(skb, __builtin_return_address(0));
1455 skb_release_data(skb, SKB_CONSUMED);
1456 kfree_skbmem(skb);
1457}
1458
1459static void napi_skb_cache_put(struct sk_buff *skb)
1460{
1461 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
1462 u32 i;
1463
1464 if (!kasan_mempool_poison_object(skb))
1465 return;
1466
1467 local_lock_nested_bh(&napi_alloc_cache.bh_lock);
1468 nc->skb_cache[nc->skb_count++] = skb;
1469
1470 if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
1471 for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
1472 kasan_mempool_unpoison_object(nc->skb_cache[i],
1473 kmem_cache_size(net_hotdata.skbuff_cache));
1474
1475 kmem_cache_free_bulk(net_hotdata.skbuff_cache, NAPI_SKB_CACHE_HALF,
1476 nc->skb_cache + NAPI_SKB_CACHE_HALF);
1477 nc->skb_count = NAPI_SKB_CACHE_HALF;
1478 }
1479 local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
1480}
1481
1482void __napi_kfree_skb(struct sk_buff *skb, enum skb_drop_reason reason)
1483{
1484 skb_release_all(skb, reason);
1485 napi_skb_cache_put(skb);
1486}
1487
1488void napi_skb_free_stolen_head(struct sk_buff *skb)
1489{
1490 if (unlikely(skb->slow_gro)) {
1491 nf_reset_ct(skb);
1492 skb_dst_drop(skb);
1493 skb_ext_put(skb);
1494 skb_orphan(skb);
1495 skb->slow_gro = 0;
1496 }
1497 napi_skb_cache_put(skb);
1498}
1499
1500void napi_consume_skb(struct sk_buff *skb, int budget)
1501{
1502 /* Zero budget indicate non-NAPI context called us, like netpoll */
1503 if (unlikely(!budget)) {
1504 dev_consume_skb_any(skb);
1505 return;
1506 }
1507
1508 DEBUG_NET_WARN_ON_ONCE(!in_softirq());
1509
1510 if (!skb_unref(skb))
1511 return;
1512
1513 /* if reaching here SKB is ready to free */
1514 trace_consume_skb(skb, __builtin_return_address(0));
1515
1516 /* if SKB is a clone, don't handle this case */
1517 if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
1518 __kfree_skb(skb);
1519 return;
1520 }
1521
1522 skb_release_all(skb, SKB_CONSUMED);
1523 napi_skb_cache_put(skb);
1524}
1525EXPORT_SYMBOL(napi_consume_skb);
1526
1527/* Make sure a field is contained by headers group */
1528#define CHECK_SKB_FIELD(field) \
1529 BUILD_BUG_ON(offsetof(struct sk_buff, field) != \
1530 offsetof(struct sk_buff, headers.field)); \
1531
1532static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
1533{
1534 new->tstamp = old->tstamp;
1535 /* We do not copy old->sk */
1536 new->dev = old->dev;
1537 memcpy(new->cb, old->cb, sizeof(old->cb));
1538 skb_dst_copy(new, old);
1539 __skb_ext_copy(new, old);
1540 __nf_copy(new, old, false);
1541
1542 /* Note : this field could be in the headers group.
1543 * It is not yet because we do not want to have a 16 bit hole
1544 */
1545 new->queue_mapping = old->queue_mapping;
1546
1547 memcpy(&new->headers, &old->headers, sizeof(new->headers));
1548 CHECK_SKB_FIELD(protocol);
1549 CHECK_SKB_FIELD(csum);
1550 CHECK_SKB_FIELD(hash);
1551 CHECK_SKB_FIELD(priority);
1552 CHECK_SKB_FIELD(skb_iif);
1553 CHECK_SKB_FIELD(vlan_proto);
1554 CHECK_SKB_FIELD(vlan_tci);
1555 CHECK_SKB_FIELD(transport_header);
1556 CHECK_SKB_FIELD(network_header);
1557 CHECK_SKB_FIELD(mac_header);
1558 CHECK_SKB_FIELD(inner_protocol);
1559 CHECK_SKB_FIELD(inner_transport_header);
1560 CHECK_SKB_FIELD(inner_network_header);
1561 CHECK_SKB_FIELD(inner_mac_header);
1562 CHECK_SKB_FIELD(mark);
1563#ifdef CONFIG_NETWORK_SECMARK
1564 CHECK_SKB_FIELD(secmark);
1565#endif
1566#ifdef CONFIG_NET_RX_BUSY_POLL
1567 CHECK_SKB_FIELD(napi_id);
1568#endif
1569 CHECK_SKB_FIELD(alloc_cpu);
1570#ifdef CONFIG_XPS
1571 CHECK_SKB_FIELD(sender_cpu);
1572#endif
1573#ifdef CONFIG_NET_SCHED
1574 CHECK_SKB_FIELD(tc_index);
1575#endif
1576
1577}
1578
1579/*
1580 * You should not add any new code to this function. Add it to
1581 * __copy_skb_header above instead.
1582 */
1583static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
1584{
1585#define C(x) n->x = skb->x
1586
1587 n->next = n->prev = NULL;
1588 n->sk = NULL;
1589 __copy_skb_header(n, skb);
1590
1591 C(len);
1592 C(data_len);
1593 C(mac_len);
1594 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
1595 n->cloned = 1;
1596 n->nohdr = 0;
1597 n->peeked = 0;
1598 C(pfmemalloc);
1599 C(pp_recycle);
1600 n->destructor = NULL;
1601 C(tail);
1602 C(end);
1603 C(head);
1604 C(head_frag);
1605 C(data);
1606 C(truesize);
1607 refcount_set(&n->users, 1);
1608
1609 atomic_inc(&(skb_shinfo(skb)->dataref));
1610 skb->cloned = 1;
1611
1612 return n;
1613#undef C
1614}
1615
1616/**
1617 * alloc_skb_for_msg() - allocate sk_buff to wrap frag list forming a msg
1618 * @first: first sk_buff of the msg
1619 */
1620struct sk_buff *alloc_skb_for_msg(struct sk_buff *first)
1621{
1622 struct sk_buff *n;
1623
1624 n = alloc_skb(0, GFP_ATOMIC);
1625 if (!n)
1626 return NULL;
1627
1628 n->len = first->len;
1629 n->data_len = first->len;
1630 n->truesize = first->truesize;
1631
1632 skb_shinfo(n)->frag_list = first;
1633
1634 __copy_skb_header(n, first);
1635 n->destructor = NULL;
1636
1637 return n;
1638}
1639EXPORT_SYMBOL_GPL(alloc_skb_for_msg);
1640
1641/**
1642 * skb_morph - morph one skb into another
1643 * @dst: the skb to receive the contents
1644 * @src: the skb to supply the contents
1645 *
1646 * This is identical to skb_clone except that the target skb is
1647 * supplied by the user.
1648 *
1649 * The target skb is returned upon exit.
1650 */
1651struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
1652{
1653 skb_release_all(dst, SKB_CONSUMED);
1654 return __skb_clone(dst, src);
1655}
1656EXPORT_SYMBOL_GPL(skb_morph);
1657
1658int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
1659{
1660 unsigned long max_pg, num_pg, new_pg, old_pg, rlim;
1661 struct user_struct *user;
1662
1663 if (capable(CAP_IPC_LOCK) || !size)
1664 return 0;
1665
1666 rlim = rlimit(RLIMIT_MEMLOCK);
1667 if (rlim == RLIM_INFINITY)
1668 return 0;
1669
1670 num_pg = (size >> PAGE_SHIFT) + 2; /* worst case */
1671 max_pg = rlim >> PAGE_SHIFT;
1672 user = mmp->user ? : current_user();
1673
1674 old_pg = atomic_long_read(&user->locked_vm);
1675 do {
1676 new_pg = old_pg + num_pg;
1677 if (new_pg > max_pg)
1678 return -ENOBUFS;
1679 } while (!atomic_long_try_cmpxchg(&user->locked_vm, &old_pg, new_pg));
1680
1681 if (!mmp->user) {
1682 mmp->user = get_uid(user);
1683 mmp->num_pg = num_pg;
1684 } else {
1685 mmp->num_pg += num_pg;
1686 }
1687
1688 return 0;
1689}
1690EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
1691
1692void mm_unaccount_pinned_pages(struct mmpin *mmp)
1693{
1694 if (mmp->user) {
1695 atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
1696 free_uid(mmp->user);
1697 }
1698}
1699EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
1700
1701static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
1702{
1703 struct ubuf_info_msgzc *uarg;
1704 struct sk_buff *skb;
1705
1706 WARN_ON_ONCE(!in_task());
1707
1708 skb = sock_omalloc(sk, 0, GFP_KERNEL);
1709 if (!skb)
1710 return NULL;
1711
1712 BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
1713 uarg = (void *)skb->cb;
1714 uarg->mmp.user = NULL;
1715
1716 if (mm_account_pinned_pages(&uarg->mmp, size)) {
1717 kfree_skb(skb);
1718 return NULL;
1719 }
1720
1721 uarg->ubuf.ops = &msg_zerocopy_ubuf_ops;
1722 uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
1723 uarg->len = 1;
1724 uarg->bytelen = size;
1725 uarg->zerocopy = 1;
1726 uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
1727 refcount_set(&uarg->ubuf.refcnt, 1);
1728 sock_hold(sk);
1729
1730 return &uarg->ubuf;
1731}
1732
1733static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
1734{
1735 return container_of((void *)uarg, struct sk_buff, cb);
1736}
1737
1738struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
1739 struct ubuf_info *uarg)
1740{
1741 if (uarg) {
1742 struct ubuf_info_msgzc *uarg_zc;
1743 const u32 byte_limit = 1 << 19; /* limit to a few TSO */
1744 u32 bytelen, next;
1745
1746 /* there might be non MSG_ZEROCOPY users */
1747 if (uarg->ops != &msg_zerocopy_ubuf_ops)
1748 return NULL;
1749
1750 /* realloc only when socket is locked (TCP, UDP cork),
1751 * so uarg->len and sk_zckey access is serialized
1752 */
1753 if (!sock_owned_by_user(sk)) {
1754 WARN_ON_ONCE(1);
1755 return NULL;
1756 }
1757
1758 uarg_zc = uarg_to_msgzc(uarg);
1759 bytelen = uarg_zc->bytelen + size;
1760 if (uarg_zc->len == USHRT_MAX - 1 || bytelen > byte_limit) {
1761 /* TCP can create new skb to attach new uarg */
1762 if (sk->sk_type == SOCK_STREAM)
1763 goto new_alloc;
1764 return NULL;
1765 }
1766
1767 next = (u32)atomic_read(&sk->sk_zckey);
1768 if ((u32)(uarg_zc->id + uarg_zc->len) == next) {
1769 if (mm_account_pinned_pages(&uarg_zc->mmp, size))
1770 return NULL;
1771 uarg_zc->len++;
1772 uarg_zc->bytelen = bytelen;
1773 atomic_set(&sk->sk_zckey, ++next);
1774
1775 /* no extra ref when appending to datagram (MSG_MORE) */
1776 if (sk->sk_type == SOCK_STREAM)
1777 net_zcopy_get(uarg);
1778
1779 return uarg;
1780 }
1781 }
1782
1783new_alloc:
1784 return msg_zerocopy_alloc(sk, size);
1785}
1786EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
1787
1788static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
1789{
1790 struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
1791 u32 old_lo, old_hi;
1792 u64 sum_len;
1793
1794 old_lo = serr->ee.ee_info;
1795 old_hi = serr->ee.ee_data;
1796 sum_len = old_hi - old_lo + 1ULL + len;
1797
1798 if (sum_len >= (1ULL << 32))
1799 return false;
1800
1801 if (lo != old_hi + 1)
1802 return false;
1803
1804 serr->ee.ee_data += len;
1805 return true;
1806}
1807
1808static void __msg_zerocopy_callback(struct ubuf_info_msgzc *uarg)
1809{
1810 struct sk_buff *tail, *skb = skb_from_uarg(uarg);
1811 struct sock_exterr_skb *serr;
1812 struct sock *sk = skb->sk;
1813 struct sk_buff_head *q;
1814 unsigned long flags;
1815 bool is_zerocopy;
1816 u32 lo, hi;
1817 u16 len;
1818
1819 mm_unaccount_pinned_pages(&uarg->mmp);
1820
1821 /* if !len, there was only 1 call, and it was aborted
1822 * so do not queue a completion notification
1823 */
1824 if (!uarg->len || sock_flag(sk, SOCK_DEAD))
1825 goto release;
1826
1827 len = uarg->len;
1828 lo = uarg->id;
1829 hi = uarg->id + len - 1;
1830 is_zerocopy = uarg->zerocopy;
1831
1832 serr = SKB_EXT_ERR(skb);
1833 memset(serr, 0, sizeof(*serr));
1834 serr->ee.ee_errno = 0;
1835 serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
1836 serr->ee.ee_data = hi;
1837 serr->ee.ee_info = lo;
1838 if (!is_zerocopy)
1839 serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
1840
1841 q = &sk->sk_error_queue;
1842 spin_lock_irqsave(&q->lock, flags);
1843 tail = skb_peek_tail(q);
1844 if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
1845 !skb_zerocopy_notify_extend(tail, lo, len)) {
1846 __skb_queue_tail(q, skb);
1847 skb = NULL;
1848 }
1849 spin_unlock_irqrestore(&q->lock, flags);
1850
1851 sk_error_report(sk);
1852
1853release:
1854 consume_skb(skb);
1855 sock_put(sk);
1856}
1857
1858static void msg_zerocopy_complete(struct sk_buff *skb, struct ubuf_info *uarg,
1859 bool success)
1860{
1861 struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
1862
1863 uarg_zc->zerocopy = uarg_zc->zerocopy & success;
1864
1865 if (refcount_dec_and_test(&uarg->refcnt))
1866 __msg_zerocopy_callback(uarg_zc);
1867}
1868
1869void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
1870{
1871 struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
1872
1873 atomic_dec(&sk->sk_zckey);
1874 uarg_to_msgzc(uarg)->len--;
1875
1876 if (have_uref)
1877 msg_zerocopy_complete(NULL, uarg, true);
1878}
1879EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
1880
1881const struct ubuf_info_ops msg_zerocopy_ubuf_ops = {
1882 .complete = msg_zerocopy_complete,
1883};
1884EXPORT_SYMBOL_GPL(msg_zerocopy_ubuf_ops);
1885
1886int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
1887 struct msghdr *msg, int len,
1888 struct ubuf_info *uarg)
1889{
1890 int err, orig_len = skb->len;
1891
1892 if (uarg->ops->link_skb) {
1893 err = uarg->ops->link_skb(skb, uarg);
1894 if (err)
1895 return err;
1896 } else {
1897 struct ubuf_info *orig_uarg = skb_zcopy(skb);
1898
1899 /* An skb can only point to one uarg. This edge case happens
1900 * when TCP appends to an skb, but zerocopy_realloc triggered
1901 * a new alloc.
1902 */
1903 if (orig_uarg && uarg != orig_uarg)
1904 return -EEXIST;
1905 }
1906
1907 err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len);
1908 if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
1909 struct sock *save_sk = skb->sk;
1910
1911 /* Streams do not free skb on error. Reset to prev state. */
1912 iov_iter_revert(&msg->msg_iter, skb->len - orig_len);
1913 skb->sk = sk;
1914 ___pskb_trim(skb, orig_len);
1915 skb->sk = save_sk;
1916 return err;
1917 }
1918
1919 skb_zcopy_set(skb, uarg, NULL);
1920 return skb->len - orig_len;
1921}
1922EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
1923
1924void __skb_zcopy_downgrade_managed(struct sk_buff *skb)
1925{
1926 int i;
1927
1928 skb_shinfo(skb)->flags &= ~SKBFL_MANAGED_FRAG_REFS;
1929 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1930 skb_frag_ref(skb, i);
1931}
1932EXPORT_SYMBOL_GPL(__skb_zcopy_downgrade_managed);
1933
1934static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
1935 gfp_t gfp_mask)
1936{
1937 if (skb_zcopy(orig)) {
1938 if (skb_zcopy(nskb)) {
1939 /* !gfp_mask callers are verified to !skb_zcopy(nskb) */
1940 if (!gfp_mask) {
1941 WARN_ON_ONCE(1);
1942 return -ENOMEM;
1943 }
1944 if (skb_uarg(nskb) == skb_uarg(orig))
1945 return 0;
1946 if (skb_copy_ubufs(nskb, GFP_ATOMIC))
1947 return -EIO;
1948 }
1949 skb_zcopy_set(nskb, skb_uarg(orig), NULL);
1950 }
1951 return 0;
1952}
1953
1954/**
1955 * skb_copy_ubufs - copy userspace skb frags buffers to kernel
1956 * @skb: the skb to modify
1957 * @gfp_mask: allocation priority
1958 *
1959 * This must be called on skb with SKBFL_ZEROCOPY_ENABLE.
1960 * It will copy all frags into kernel and drop the reference
1961 * to userspace pages.
1962 *
1963 * If this function is called from an interrupt gfp_mask() must be
1964 * %GFP_ATOMIC.
1965 *
1966 * Returns 0 on success or a negative error code on failure
1967 * to allocate kernel memory to copy to.
1968 */
1969int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
1970{
1971 int num_frags = skb_shinfo(skb)->nr_frags;
1972 struct page *page, *head = NULL;
1973 int i, order, psize, new_frags;
1974 u32 d_off;
1975
1976 if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
1977 return -EINVAL;
1978
1979 if (!skb_frags_readable(skb))
1980 return -EFAULT;
1981
1982 if (!num_frags)
1983 goto release;
1984
1985 /* We might have to allocate high order pages, so compute what minimum
1986 * page order is needed.
1987 */
1988 order = 0;
1989 while ((PAGE_SIZE << order) * MAX_SKB_FRAGS < __skb_pagelen(skb))
1990 order++;
1991 psize = (PAGE_SIZE << order);
1992
1993 new_frags = (__skb_pagelen(skb) + psize - 1) >> (PAGE_SHIFT + order);
1994 for (i = 0; i < new_frags; i++) {
1995 page = alloc_pages(gfp_mask | __GFP_COMP, order);
1996 if (!page) {
1997 while (head) {
1998 struct page *next = (struct page *)page_private(head);
1999 put_page(head);
2000 head = next;
2001 }
2002 return -ENOMEM;
2003 }
2004 set_page_private(page, (unsigned long)head);
2005 head = page;
2006 }
2007
2008 page = head;
2009 d_off = 0;
2010 for (i = 0; i < num_frags; i++) {
2011 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
2012 u32 p_off, p_len, copied;
2013 struct page *p;
2014 u8 *vaddr;
2015
2016 skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
2017 p, p_off, p_len, copied) {
2018 u32 copy, done = 0;
2019 vaddr = kmap_atomic(p);
2020
2021 while (done < p_len) {
2022 if (d_off == psize) {
2023 d_off = 0;
2024 page = (struct page *)page_private(page);
2025 }
2026 copy = min_t(u32, psize - d_off, p_len - done);
2027 memcpy(page_address(page) + d_off,
2028 vaddr + p_off + done, copy);
2029 done += copy;
2030 d_off += copy;
2031 }
2032 kunmap_atomic(vaddr);
2033 }
2034 }
2035
2036 /* skb frags release userspace buffers */
2037 for (i = 0; i < num_frags; i++)
2038 skb_frag_unref(skb, i);
2039
2040 /* skb frags point to kernel buffers */
2041 for (i = 0; i < new_frags - 1; i++) {
2042 __skb_fill_netmem_desc(skb, i, page_to_netmem(head), 0, psize);
2043 head = (struct page *)page_private(head);
2044 }
2045 __skb_fill_netmem_desc(skb, new_frags - 1, page_to_netmem(head), 0,
2046 d_off);
2047 skb_shinfo(skb)->nr_frags = new_frags;
2048
2049release:
2050 skb_zcopy_clear(skb, false);
2051 return 0;
2052}
2053EXPORT_SYMBOL_GPL(skb_copy_ubufs);
2054
2055/**
2056 * skb_clone - duplicate an sk_buff
2057 * @skb: buffer to clone
2058 * @gfp_mask: allocation priority
2059 *
2060 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
2061 * copies share the same packet data but not structure. The new
2062 * buffer has a reference count of 1. If the allocation fails the
2063 * function returns %NULL otherwise the new buffer is returned.
2064 *
2065 * If this function is called from an interrupt gfp_mask() must be
2066 * %GFP_ATOMIC.
2067 */
2068
2069struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
2070{
2071 struct sk_buff_fclones *fclones = container_of(skb,
2072 struct sk_buff_fclones,
2073 skb1);
2074 struct sk_buff *n;
2075
2076 if (skb_orphan_frags(skb, gfp_mask))
2077 return NULL;
2078
2079 if (skb->fclone == SKB_FCLONE_ORIG &&
2080 refcount_read(&fclones->fclone_ref) == 1) {
2081 n = &fclones->skb2;
2082 refcount_set(&fclones->fclone_ref, 2);
2083 n->fclone = SKB_FCLONE_CLONE;
2084 } else {
2085 if (skb_pfmemalloc(skb))
2086 gfp_mask |= __GFP_MEMALLOC;
2087
2088 n = kmem_cache_alloc(net_hotdata.skbuff_cache, gfp_mask);
2089 if (!n)
2090 return NULL;
2091
2092 n->fclone = SKB_FCLONE_UNAVAILABLE;
2093 }
2094
2095 return __skb_clone(n, skb);
2096}
2097EXPORT_SYMBOL(skb_clone);
2098
2099void skb_headers_offset_update(struct sk_buff *skb, int off)
2100{
2101 /* Only adjust this if it actually is csum_start rather than csum */
2102 if (skb->ip_summed == CHECKSUM_PARTIAL)
2103 skb->csum_start += off;
2104 /* {transport,network,mac}_header and tail are relative to skb->head */
2105 skb->transport_header += off;
2106 skb->network_header += off;
2107 if (skb_mac_header_was_set(skb))
2108 skb->mac_header += off;
2109 skb->inner_transport_header += off;
2110 skb->inner_network_header += off;
2111 skb->inner_mac_header += off;
2112}
2113EXPORT_SYMBOL(skb_headers_offset_update);
2114
2115void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
2116{
2117 __copy_skb_header(new, old);
2118
2119 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
2120 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
2121 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
2122}
2123EXPORT_SYMBOL(skb_copy_header);
2124
2125static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
2126{
2127 if (skb_pfmemalloc(skb))
2128 return SKB_ALLOC_RX;
2129 return 0;
2130}
2131
2132/**
2133 * skb_copy - create private copy of an sk_buff
2134 * @skb: buffer to copy
2135 * @gfp_mask: allocation priority
2136 *
2137 * Make a copy of both an &sk_buff and its data. This is used when the
2138 * caller wishes to modify the data and needs a private copy of the
2139 * data to alter. Returns %NULL on failure or the pointer to the buffer
2140 * on success. The returned buffer has a reference count of 1.
2141 *
2142 * As by-product this function converts non-linear &sk_buff to linear
2143 * one, so that &sk_buff becomes completely private and caller is allowed
2144 * to modify all the data of returned buffer. This means that this
2145 * function is not recommended for use in circumstances when only
2146 * header is going to be modified. Use pskb_copy() instead.
2147 */
2148
2149struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
2150{
2151 struct sk_buff *n;
2152 unsigned int size;
2153 int headerlen;
2154
2155 if (!skb_frags_readable(skb))
2156 return NULL;
2157
2158 if (WARN_ON_ONCE(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST))
2159 return NULL;
2160
2161 headerlen = skb_headroom(skb);
2162 size = skb_end_offset(skb) + skb->data_len;
2163 n = __alloc_skb(size, gfp_mask,
2164 skb_alloc_rx_flag(skb), NUMA_NO_NODE);
2165 if (!n)
2166 return NULL;
2167
2168 /* Set the data pointer */
2169 skb_reserve(n, headerlen);
2170 /* Set the tail pointer and length */
2171 skb_put(n, skb->len);
2172
2173 BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
2174
2175 skb_copy_header(n, skb);
2176 return n;
2177}
2178EXPORT_SYMBOL(skb_copy);
2179
2180/**
2181 * __pskb_copy_fclone - create copy of an sk_buff with private head.
2182 * @skb: buffer to copy
2183 * @headroom: headroom of new skb
2184 * @gfp_mask: allocation priority
2185 * @fclone: if true allocate the copy of the skb from the fclone
2186 * cache instead of the head cache; it is recommended to set this
2187 * to true for the cases where the copy will likely be cloned
2188 *
2189 * Make a copy of both an &sk_buff and part of its data, located
2190 * in header. Fragmented data remain shared. This is used when
2191 * the caller wishes to modify only header of &sk_buff and needs
2192 * private copy of the header to alter. Returns %NULL on failure
2193 * or the pointer to the buffer on success.
2194 * The returned buffer has a reference count of 1.
2195 */
2196
2197struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
2198 gfp_t gfp_mask, bool fclone)
2199{
2200 unsigned int size = skb_headlen(skb) + headroom;
2201 int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
2202 struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
2203
2204 if (!n)
2205 goto out;
2206
2207 /* Set the data pointer */
2208 skb_reserve(n, headroom);
2209 /* Set the tail pointer and length */
2210 skb_put(n, skb_headlen(skb));
2211 /* Copy the bytes */
2212 skb_copy_from_linear_data(skb, n->data, n->len);
2213
2214 n->truesize += skb->data_len;
2215 n->data_len = skb->data_len;
2216 n->len = skb->len;
2217
2218 if (skb_shinfo(skb)->nr_frags) {
2219 int i;
2220
2221 if (skb_orphan_frags(skb, gfp_mask) ||
2222 skb_zerocopy_clone(n, skb, gfp_mask)) {
2223 kfree_skb(n);
2224 n = NULL;
2225 goto out;
2226 }
2227 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2228 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
2229 skb_frag_ref(skb, i);
2230 }
2231 skb_shinfo(n)->nr_frags = i;
2232 }
2233
2234 if (skb_has_frag_list(skb)) {
2235 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
2236 skb_clone_fraglist(n);
2237 }
2238
2239 skb_copy_header(n, skb);
2240out:
2241 return n;
2242}
2243EXPORT_SYMBOL(__pskb_copy_fclone);
2244
2245/**
2246 * pskb_expand_head - reallocate header of &sk_buff
2247 * @skb: buffer to reallocate
2248 * @nhead: room to add at head
2249 * @ntail: room to add at tail
2250 * @gfp_mask: allocation priority
2251 *
2252 * Expands (or creates identical copy, if @nhead and @ntail are zero)
2253 * header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
2254 * reference count of 1. Returns zero in the case of success or error,
2255 * if expansion failed. In the last case, &sk_buff is not changed.
2256 *
2257 * All the pointers pointing into skb header may change and must be
2258 * reloaded after call to this function.
2259 */
2260
2261int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
2262 gfp_t gfp_mask)
2263{
2264 unsigned int osize = skb_end_offset(skb);
2265 unsigned int size = osize + nhead + ntail;
2266 long off;
2267 u8 *data;
2268 int i;
2269
2270 BUG_ON(nhead < 0);
2271
2272 BUG_ON(skb_shared(skb));
2273
2274 skb_zcopy_downgrade_managed(skb);
2275
2276 if (skb_pfmemalloc(skb))
2277 gfp_mask |= __GFP_MEMALLOC;
2278
2279 data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
2280 if (!data)
2281 goto nodata;
2282 size = SKB_WITH_OVERHEAD(size);
2283
2284 /* Copy only real data... and, alas, header. This should be
2285 * optimized for the cases when header is void.
2286 */
2287 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
2288
2289 memcpy((struct skb_shared_info *)(data + size),
2290 skb_shinfo(skb),
2291 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
2292
2293 /*
2294 * if shinfo is shared we must drop the old head gracefully, but if it
2295 * is not we can just drop the old head and let the existing refcount
2296 * be since all we did is relocate the values
2297 */
2298 if (skb_cloned(skb)) {
2299 if (skb_orphan_frags(skb, gfp_mask))
2300 goto nofrags;
2301 if (skb_zcopy(skb))
2302 refcount_inc(&skb_uarg(skb)->refcnt);
2303 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2304 skb_frag_ref(skb, i);
2305
2306 if (skb_has_frag_list(skb))
2307 skb_clone_fraglist(skb);
2308
2309 skb_release_data(skb, SKB_CONSUMED);
2310 } else {
2311 skb_free_head(skb);
2312 }
2313 off = (data + nhead) - skb->head;
2314
2315 skb->head = data;
2316 skb->head_frag = 0;
2317 skb->data += off;
2318
2319 skb_set_end_offset(skb, size);
2320#ifdef NET_SKBUFF_DATA_USES_OFFSET
2321 off = nhead;
2322#endif
2323 skb->tail += off;
2324 skb_headers_offset_update(skb, nhead);
2325 skb->cloned = 0;
2326 skb->hdr_len = 0;
2327 skb->nohdr = 0;
2328 atomic_set(&skb_shinfo(skb)->dataref, 1);
2329
2330 skb_metadata_clear(skb);
2331
2332 /* It is not generally safe to change skb->truesize.
2333 * For the moment, we really care of rx path, or
2334 * when skb is orphaned (not attached to a socket).
2335 */
2336 if (!skb->sk || skb->destructor == sock_edemux)
2337 skb->truesize += size - osize;
2338
2339 return 0;
2340
2341nofrags:
2342 skb_kfree_head(data, size);
2343nodata:
2344 return -ENOMEM;
2345}
2346EXPORT_SYMBOL(pskb_expand_head);
2347
2348/* Make private copy of skb with writable head and some headroom */
2349
2350struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
2351{
2352 struct sk_buff *skb2;
2353 int delta = headroom - skb_headroom(skb);
2354
2355 if (delta <= 0)
2356 skb2 = pskb_copy(skb, GFP_ATOMIC);
2357 else {
2358 skb2 = skb_clone(skb, GFP_ATOMIC);
2359 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
2360 GFP_ATOMIC)) {
2361 kfree_skb(skb2);
2362 skb2 = NULL;
2363 }
2364 }
2365 return skb2;
2366}
2367EXPORT_SYMBOL(skb_realloc_headroom);
2368
2369/* Note: We plan to rework this in linux-6.4 */
2370int __skb_unclone_keeptruesize(struct sk_buff *skb, gfp_t pri)
2371{
2372 unsigned int saved_end_offset, saved_truesize;
2373 struct skb_shared_info *shinfo;
2374 int res;
2375
2376 saved_end_offset = skb_end_offset(skb);
2377 saved_truesize = skb->truesize;
2378
2379 res = pskb_expand_head(skb, 0, 0, pri);
2380 if (res)
2381 return res;
2382
2383 skb->truesize = saved_truesize;
2384
2385 if (likely(skb_end_offset(skb) == saved_end_offset))
2386 return 0;
2387
2388 /* We can not change skb->end if the original or new value
2389 * is SKB_SMALL_HEAD_HEADROOM, as it might break skb_kfree_head().
2390 */
2391 if (saved_end_offset == SKB_SMALL_HEAD_HEADROOM ||
2392 skb_end_offset(skb) == SKB_SMALL_HEAD_HEADROOM) {
2393 /* We think this path should not be taken.
2394 * Add a temporary trace to warn us just in case.
2395 */
2396 pr_err_once("__skb_unclone_keeptruesize() skb_end_offset() %u -> %u\n",
2397 saved_end_offset, skb_end_offset(skb));
2398 WARN_ON_ONCE(1);
2399 return 0;
2400 }
2401
2402 shinfo = skb_shinfo(skb);
2403
2404 /* We are about to change back skb->end,
2405 * we need to move skb_shinfo() to its new location.
2406 */
2407 memmove(skb->head + saved_end_offset,
2408 shinfo,
2409 offsetof(struct skb_shared_info, frags[shinfo->nr_frags]));
2410
2411 skb_set_end_offset(skb, saved_end_offset);
2412
2413 return 0;
2414}
2415
2416/**
2417 * skb_expand_head - reallocate header of &sk_buff
2418 * @skb: buffer to reallocate
2419 * @headroom: needed headroom
2420 *
2421 * Unlike skb_realloc_headroom, this one does not allocate a new skb
2422 * if possible; copies skb->sk to new skb as needed
2423 * and frees original skb in case of failures.
2424 *
2425 * It expect increased headroom and generates warning otherwise.
2426 */
2427
2428struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom)
2429{
2430 int delta = headroom - skb_headroom(skb);
2431 int osize = skb_end_offset(skb);
2432 struct sock *sk = skb->sk;
2433
2434 if (WARN_ONCE(delta <= 0,
2435 "%s is expecting an increase in the headroom", __func__))
2436 return skb;
2437
2438 delta = SKB_DATA_ALIGN(delta);
2439 /* pskb_expand_head() might crash, if skb is shared. */
2440 if (skb_shared(skb) || !is_skb_wmem(skb)) {
2441 struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
2442
2443 if (unlikely(!nskb))
2444 goto fail;
2445
2446 if (sk)
2447 skb_set_owner_w(nskb, sk);
2448 consume_skb(skb);
2449 skb = nskb;
2450 }
2451 if (pskb_expand_head(skb, delta, 0, GFP_ATOMIC))
2452 goto fail;
2453
2454 if (sk && is_skb_wmem(skb)) {
2455 delta = skb_end_offset(skb) - osize;
2456 refcount_add(delta, &sk->sk_wmem_alloc);
2457 skb->truesize += delta;
2458 }
2459 return skb;
2460
2461fail:
2462 kfree_skb(skb);
2463 return NULL;
2464}
2465EXPORT_SYMBOL(skb_expand_head);
2466
2467/**
2468 * skb_copy_expand - copy and expand sk_buff
2469 * @skb: buffer to copy
2470 * @newheadroom: new free bytes at head
2471 * @newtailroom: new free bytes at tail
2472 * @gfp_mask: allocation priority
2473 *
2474 * Make a copy of both an &sk_buff and its data and while doing so
2475 * allocate additional space.
2476 *
2477 * This is used when the caller wishes to modify the data and needs a
2478 * private copy of the data to alter as well as more space for new fields.
2479 * Returns %NULL on failure or the pointer to the buffer
2480 * on success. The returned buffer has a reference count of 1.
2481 *
2482 * You must pass %GFP_ATOMIC as the allocation priority if this function
2483 * is called from an interrupt.
2484 */
2485struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
2486 int newheadroom, int newtailroom,
2487 gfp_t gfp_mask)
2488{
2489 /*
2490 * Allocate the copy buffer
2491 */
2492 int head_copy_len, head_copy_off;
2493 struct sk_buff *n;
2494 int oldheadroom;
2495
2496 if (!skb_frags_readable(skb))
2497 return NULL;
2498
2499 if (WARN_ON_ONCE(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST))
2500 return NULL;
2501
2502 oldheadroom = skb_headroom(skb);
2503 n = __alloc_skb(newheadroom + skb->len + newtailroom,
2504 gfp_mask, skb_alloc_rx_flag(skb),
2505 NUMA_NO_NODE);
2506 if (!n)
2507 return NULL;
2508
2509 skb_reserve(n, newheadroom);
2510
2511 /* Set the tail pointer and length */
2512 skb_put(n, skb->len);
2513
2514 head_copy_len = oldheadroom;
2515 head_copy_off = 0;
2516 if (newheadroom <= head_copy_len)
2517 head_copy_len = newheadroom;
2518 else
2519 head_copy_off = newheadroom - head_copy_len;
2520
2521 /* Copy the linear header and data. */
2522 BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
2523 skb->len + head_copy_len));
2524
2525 skb_copy_header(n, skb);
2526
2527 skb_headers_offset_update(n, newheadroom - oldheadroom);
2528
2529 return n;
2530}
2531EXPORT_SYMBOL(skb_copy_expand);
2532
2533/**
2534 * __skb_pad - zero pad the tail of an skb
2535 * @skb: buffer to pad
2536 * @pad: space to pad
2537 * @free_on_error: free buffer on error
2538 *
2539 * Ensure that a buffer is followed by a padding area that is zero
2540 * filled. Used by network drivers which may DMA or transfer data
2541 * beyond the buffer end onto the wire.
2542 *
2543 * May return error in out of memory cases. The skb is freed on error
2544 * if @free_on_error is true.
2545 */
2546
2547int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
2548{
2549 int err;
2550 int ntail;
2551
2552 /* If the skbuff is non linear tailroom is always zero.. */
2553 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
2554 memset(skb->data+skb->len, 0, pad);
2555 return 0;
2556 }
2557
2558 ntail = skb->data_len + pad - (skb->end - skb->tail);
2559 if (likely(skb_cloned(skb) || ntail > 0)) {
2560 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
2561 if (unlikely(err))
2562 goto free_skb;
2563 }
2564
2565 /* FIXME: The use of this function with non-linear skb's really needs
2566 * to be audited.
2567 */
2568 err = skb_linearize(skb);
2569 if (unlikely(err))
2570 goto free_skb;
2571
2572 memset(skb->data + skb->len, 0, pad);
2573 return 0;
2574
2575free_skb:
2576 if (free_on_error)
2577 kfree_skb(skb);
2578 return err;
2579}
2580EXPORT_SYMBOL(__skb_pad);
2581
2582/**
2583 * pskb_put - add data to the tail of a potentially fragmented buffer
2584 * @skb: start of the buffer to use
2585 * @tail: tail fragment of the buffer to use
2586 * @len: amount of data to add
2587 *
2588 * This function extends the used data area of the potentially
2589 * fragmented buffer. @tail must be the last fragment of @skb -- or
2590 * @skb itself. If this would exceed the total buffer size the kernel
2591 * will panic. A pointer to the first byte of the extra data is
2592 * returned.
2593 */
2594
2595void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
2596{
2597 if (tail != skb) {
2598 skb->data_len += len;
2599 skb->len += len;
2600 }
2601 return skb_put(tail, len);
2602}
2603EXPORT_SYMBOL_GPL(pskb_put);
2604
2605/**
2606 * skb_put - add data to a buffer
2607 * @skb: buffer to use
2608 * @len: amount of data to add
2609 *
2610 * This function extends the used data area of the buffer. If this would
2611 * exceed the total buffer size the kernel will panic. A pointer to the
2612 * first byte of the extra data is returned.
2613 */
2614void *skb_put(struct sk_buff *skb, unsigned int len)
2615{
2616 void *tmp = skb_tail_pointer(skb);
2617 SKB_LINEAR_ASSERT(skb);
2618 skb->tail += len;
2619 skb->len += len;
2620 if (unlikely(skb->tail > skb->end))
2621 skb_over_panic(skb, len, __builtin_return_address(0));
2622 return tmp;
2623}
2624EXPORT_SYMBOL(skb_put);
2625
2626/**
2627 * skb_push - add data to the start of a buffer
2628 * @skb: buffer to use
2629 * @len: amount of data to add
2630 *
2631 * This function extends the used data area of the buffer at the buffer
2632 * start. If this would exceed the total buffer headroom the kernel will
2633 * panic. A pointer to the first byte of the extra data is returned.
2634 */
2635void *skb_push(struct sk_buff *skb, unsigned int len)
2636{
2637 skb->data -= len;
2638 skb->len += len;
2639 if (unlikely(skb->data < skb->head))
2640 skb_under_panic(skb, len, __builtin_return_address(0));
2641 return skb->data;
2642}
2643EXPORT_SYMBOL(skb_push);
2644
2645/**
2646 * skb_pull - remove data from the start of a buffer
2647 * @skb: buffer to use
2648 * @len: amount of data to remove
2649 *
2650 * This function removes data from the start of a buffer, returning
2651 * the memory to the headroom. A pointer to the next data in the buffer
2652 * is returned. Once the data has been pulled future pushes will overwrite
2653 * the old data.
2654 */
2655void *skb_pull(struct sk_buff *skb, unsigned int len)
2656{
2657 return skb_pull_inline(skb, len);
2658}
2659EXPORT_SYMBOL(skb_pull);
2660
2661/**
2662 * skb_pull_data - remove data from the start of a buffer returning its
2663 * original position.
2664 * @skb: buffer to use
2665 * @len: amount of data to remove
2666 *
2667 * This function removes data from the start of a buffer, returning
2668 * the memory to the headroom. A pointer to the original data in the buffer
2669 * is returned after checking if there is enough data to pull. Once the
2670 * data has been pulled future pushes will overwrite the old data.
2671 */
2672void *skb_pull_data(struct sk_buff *skb, size_t len)
2673{
2674 void *data = skb->data;
2675
2676 if (skb->len < len)
2677 return NULL;
2678
2679 skb_pull(skb, len);
2680
2681 return data;
2682}
2683EXPORT_SYMBOL(skb_pull_data);
2684
2685/**
2686 * skb_trim - remove end from a buffer
2687 * @skb: buffer to alter
2688 * @len: new length
2689 *
2690 * Cut the length of a buffer down by removing data from the tail. If
2691 * the buffer is already under the length specified it is not modified.
2692 * The skb must be linear.
2693 */
2694void skb_trim(struct sk_buff *skb, unsigned int len)
2695{
2696 if (skb->len > len)
2697 __skb_trim(skb, len);
2698}
2699EXPORT_SYMBOL(skb_trim);
2700
2701/* Trims skb to length len. It can change skb pointers.
2702 */
2703
2704int ___pskb_trim(struct sk_buff *skb, unsigned int len)
2705{
2706 struct sk_buff **fragp;
2707 struct sk_buff *frag;
2708 int offset = skb_headlen(skb);
2709 int nfrags = skb_shinfo(skb)->nr_frags;
2710 int i;
2711 int err;
2712
2713 if (skb_cloned(skb) &&
2714 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
2715 return err;
2716
2717 i = 0;
2718 if (offset >= len)
2719 goto drop_pages;
2720
2721 for (; i < nfrags; i++) {
2722 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2723
2724 if (end < len) {
2725 offset = end;
2726 continue;
2727 }
2728
2729 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
2730
2731drop_pages:
2732 skb_shinfo(skb)->nr_frags = i;
2733
2734 for (; i < nfrags; i++)
2735 skb_frag_unref(skb, i);
2736
2737 if (skb_has_frag_list(skb))
2738 skb_drop_fraglist(skb);
2739 goto done;
2740 }
2741
2742 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
2743 fragp = &frag->next) {
2744 int end = offset + frag->len;
2745
2746 if (skb_shared(frag)) {
2747 struct sk_buff *nfrag;
2748
2749 nfrag = skb_clone(frag, GFP_ATOMIC);
2750 if (unlikely(!nfrag))
2751 return -ENOMEM;
2752
2753 nfrag->next = frag->next;
2754 consume_skb(frag);
2755 frag = nfrag;
2756 *fragp = frag;
2757 }
2758
2759 if (end < len) {
2760 offset = end;
2761 continue;
2762 }
2763
2764 if (end > len &&
2765 unlikely((err = pskb_trim(frag, len - offset))))
2766 return err;
2767
2768 if (frag->next)
2769 skb_drop_list(&frag->next);
2770 break;
2771 }
2772
2773done:
2774 if (len > skb_headlen(skb)) {
2775 skb->data_len -= skb->len - len;
2776 skb->len = len;
2777 } else {
2778 skb->len = len;
2779 skb->data_len = 0;
2780 skb_set_tail_pointer(skb, len);
2781 }
2782
2783 if (!skb->sk || skb->destructor == sock_edemux)
2784 skb_condense(skb);
2785 return 0;
2786}
2787EXPORT_SYMBOL(___pskb_trim);
2788
2789/* Note : use pskb_trim_rcsum() instead of calling this directly
2790 */
2791int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
2792{
2793 if (skb->ip_summed == CHECKSUM_COMPLETE) {
2794 int delta = skb->len - len;
2795
2796 skb->csum = csum_block_sub(skb->csum,
2797 skb_checksum(skb, len, delta, 0),
2798 len);
2799 } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
2800 int hdlen = (len > skb_headlen(skb)) ? skb_headlen(skb) : len;
2801 int offset = skb_checksum_start_offset(skb) + skb->csum_offset;
2802
2803 if (offset + sizeof(__sum16) > hdlen)
2804 return -EINVAL;
2805 }
2806 return __pskb_trim(skb, len);
2807}
2808EXPORT_SYMBOL(pskb_trim_rcsum_slow);
2809
2810/**
2811 * __pskb_pull_tail - advance tail of skb header
2812 * @skb: buffer to reallocate
2813 * @delta: number of bytes to advance tail
2814 *
2815 * The function makes a sense only on a fragmented &sk_buff,
2816 * it expands header moving its tail forward and copying necessary
2817 * data from fragmented part.
2818 *
2819 * &sk_buff MUST have reference count of 1.
2820 *
2821 * Returns %NULL (and &sk_buff does not change) if pull failed
2822 * or value of new tail of skb in the case of success.
2823 *
2824 * All the pointers pointing into skb header may change and must be
2825 * reloaded after call to this function.
2826 */
2827
2828/* Moves tail of skb head forward, copying data from fragmented part,
2829 * when it is necessary.
2830 * 1. It may fail due to malloc failure.
2831 * 2. It may change skb pointers.
2832 *
2833 * It is pretty complicated. Luckily, it is called only in exceptional cases.
2834 */
2835void *__pskb_pull_tail(struct sk_buff *skb, int delta)
2836{
2837 /* If skb has not enough free space at tail, get new one
2838 * plus 128 bytes for future expansions. If we have enough
2839 * room at tail, reallocate without expansion only if skb is cloned.
2840 */
2841 int i, k, eat = (skb->tail + delta) - skb->end;
2842
2843 if (!skb_frags_readable(skb))
2844 return NULL;
2845
2846 if (eat > 0 || skb_cloned(skb)) {
2847 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
2848 GFP_ATOMIC))
2849 return NULL;
2850 }
2851
2852 BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
2853 skb_tail_pointer(skb), delta));
2854
2855 /* Optimization: no fragments, no reasons to preestimate
2856 * size of pulled pages. Superb.
2857 */
2858 if (!skb_has_frag_list(skb))
2859 goto pull_pages;
2860
2861 /* Estimate size of pulled pages. */
2862 eat = delta;
2863 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2864 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2865
2866 if (size >= eat)
2867 goto pull_pages;
2868 eat -= size;
2869 }
2870
2871 /* If we need update frag list, we are in troubles.
2872 * Certainly, it is possible to add an offset to skb data,
2873 * but taking into account that pulling is expected to
2874 * be very rare operation, it is worth to fight against
2875 * further bloating skb head and crucify ourselves here instead.
2876 * Pure masohism, indeed. 8)8)
2877 */
2878 if (eat) {
2879 struct sk_buff *list = skb_shinfo(skb)->frag_list;
2880 struct sk_buff *clone = NULL;
2881 struct sk_buff *insp = NULL;
2882
2883 do {
2884 if (list->len <= eat) {
2885 /* Eaten as whole. */
2886 eat -= list->len;
2887 list = list->next;
2888 insp = list;
2889 } else {
2890 /* Eaten partially. */
2891 if (skb_is_gso(skb) && !list->head_frag &&
2892 skb_headlen(list))
2893 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
2894
2895 if (skb_shared(list)) {
2896 /* Sucks! We need to fork list. :-( */
2897 clone = skb_clone(list, GFP_ATOMIC);
2898 if (!clone)
2899 return NULL;
2900 insp = list->next;
2901 list = clone;
2902 } else {
2903 /* This may be pulled without
2904 * problems. */
2905 insp = list;
2906 }
2907 if (!pskb_pull(list, eat)) {
2908 kfree_skb(clone);
2909 return NULL;
2910 }
2911 break;
2912 }
2913 } while (eat);
2914
2915 /* Free pulled out fragments. */
2916 while ((list = skb_shinfo(skb)->frag_list) != insp) {
2917 skb_shinfo(skb)->frag_list = list->next;
2918 consume_skb(list);
2919 }
2920 /* And insert new clone at head. */
2921 if (clone) {
2922 clone->next = list;
2923 skb_shinfo(skb)->frag_list = clone;
2924 }
2925 }
2926 /* Success! Now we may commit changes to skb data. */
2927
2928pull_pages:
2929 eat = delta;
2930 k = 0;
2931 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2932 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2933
2934 if (size <= eat) {
2935 skb_frag_unref(skb, i);
2936 eat -= size;
2937 } else {
2938 skb_frag_t *frag = &skb_shinfo(skb)->frags[k];
2939
2940 *frag = skb_shinfo(skb)->frags[i];
2941 if (eat) {
2942 skb_frag_off_add(frag, eat);
2943 skb_frag_size_sub(frag, eat);
2944 if (!i)
2945 goto end;
2946 eat = 0;
2947 }
2948 k++;
2949 }
2950 }
2951 skb_shinfo(skb)->nr_frags = k;
2952
2953end:
2954 skb->tail += delta;
2955 skb->data_len -= delta;
2956
2957 if (!skb->data_len)
2958 skb_zcopy_clear(skb, false);
2959
2960 return skb_tail_pointer(skb);
2961}
2962EXPORT_SYMBOL(__pskb_pull_tail);
2963
2964/**
2965 * skb_copy_bits - copy bits from skb to kernel buffer
2966 * @skb: source skb
2967 * @offset: offset in source
2968 * @to: destination buffer
2969 * @len: number of bytes to copy
2970 *
2971 * Copy the specified number of bytes from the source skb to the
2972 * destination buffer.
2973 *
2974 * CAUTION ! :
2975 * If its prototype is ever changed,
2976 * check arch/{*}/net/{*}.S files,
2977 * since it is called from BPF assembly code.
2978 */
2979int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
2980{
2981 int start = skb_headlen(skb);
2982 struct sk_buff *frag_iter;
2983 int i, copy;
2984
2985 if (offset > (int)skb->len - len)
2986 goto fault;
2987
2988 /* Copy header. */
2989 if ((copy = start - offset) > 0) {
2990 if (copy > len)
2991 copy = len;
2992 skb_copy_from_linear_data_offset(skb, offset, to, copy);
2993 if ((len -= copy) == 0)
2994 return 0;
2995 offset += copy;
2996 to += copy;
2997 }
2998
2999 if (!skb_frags_readable(skb))
3000 goto fault;
3001
3002 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3003 int end;
3004 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
3005
3006 WARN_ON(start > offset + len);
3007
3008 end = start + skb_frag_size(f);
3009 if ((copy = end - offset) > 0) {
3010 u32 p_off, p_len, copied;
3011 struct page *p;
3012 u8 *vaddr;
3013
3014 if (copy > len)
3015 copy = len;
3016
3017 skb_frag_foreach_page(f,
3018 skb_frag_off(f) + offset - start,
3019 copy, p, p_off, p_len, copied) {
3020 vaddr = kmap_atomic(p);
3021 memcpy(to + copied, vaddr + p_off, p_len);
3022 kunmap_atomic(vaddr);
3023 }
3024
3025 if ((len -= copy) == 0)
3026 return 0;
3027 offset += copy;
3028 to += copy;
3029 }
3030 start = end;
3031 }
3032
3033 skb_walk_frags(skb, frag_iter) {
3034 int end;
3035
3036 WARN_ON(start > offset + len);
3037
3038 end = start + frag_iter->len;
3039 if ((copy = end - offset) > 0) {
3040 if (copy > len)
3041 copy = len;
3042 if (skb_copy_bits(frag_iter, offset - start, to, copy))
3043 goto fault;
3044 if ((len -= copy) == 0)
3045 return 0;
3046 offset += copy;
3047 to += copy;
3048 }
3049 start = end;
3050 }
3051
3052 if (!len)
3053 return 0;
3054
3055fault:
3056 return -EFAULT;
3057}
3058EXPORT_SYMBOL(skb_copy_bits);
3059
3060/*
3061 * Callback from splice_to_pipe(), if we need to release some pages
3062 * at the end of the spd in case we error'ed out in filling the pipe.
3063 */
3064static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
3065{
3066 put_page(spd->pages[i]);
3067}
3068
3069static struct page *linear_to_page(struct page *page, unsigned int *len,
3070 unsigned int *offset,
3071 struct sock *sk)
3072{
3073 struct page_frag *pfrag = sk_page_frag(sk);
3074
3075 if (!sk_page_frag_refill(sk, pfrag))
3076 return NULL;
3077
3078 *len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
3079
3080 memcpy(page_address(pfrag->page) + pfrag->offset,
3081 page_address(page) + *offset, *len);
3082 *offset = pfrag->offset;
3083 pfrag->offset += *len;
3084
3085 return pfrag->page;
3086}
3087
3088static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
3089 struct page *page,
3090 unsigned int offset)
3091{
3092 return spd->nr_pages &&
3093 spd->pages[spd->nr_pages - 1] == page &&
3094 (spd->partial[spd->nr_pages - 1].offset +
3095 spd->partial[spd->nr_pages - 1].len == offset);
3096}
3097
3098/*
3099 * Fill page/offset/length into spd, if it can hold more pages.
3100 */
3101static bool spd_fill_page(struct splice_pipe_desc *spd,
3102 struct pipe_inode_info *pipe, struct page *page,
3103 unsigned int *len, unsigned int offset,
3104 bool linear,
3105 struct sock *sk)
3106{
3107 if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
3108 return true;
3109
3110 if (linear) {
3111 page = linear_to_page(page, len, &offset, sk);
3112 if (!page)
3113 return true;
3114 }
3115 if (spd_can_coalesce(spd, page, offset)) {
3116 spd->partial[spd->nr_pages - 1].len += *len;
3117 return false;
3118 }
3119 get_page(page);
3120 spd->pages[spd->nr_pages] = page;
3121 spd->partial[spd->nr_pages].len = *len;
3122 spd->partial[spd->nr_pages].offset = offset;
3123 spd->nr_pages++;
3124
3125 return false;
3126}
3127
3128static bool __splice_segment(struct page *page, unsigned int poff,
3129 unsigned int plen, unsigned int *off,
3130 unsigned int *len,
3131 struct splice_pipe_desc *spd, bool linear,
3132 struct sock *sk,
3133 struct pipe_inode_info *pipe)
3134{
3135 if (!*len)
3136 return true;
3137
3138 /* skip this segment if already processed */
3139 if (*off >= plen) {
3140 *off -= plen;
3141 return false;
3142 }
3143
3144 /* ignore any bits we already processed */
3145 poff += *off;
3146 plen -= *off;
3147 *off = 0;
3148
3149 do {
3150 unsigned int flen = min(*len, plen);
3151
3152 if (spd_fill_page(spd, pipe, page, &flen, poff,
3153 linear, sk))
3154 return true;
3155 poff += flen;
3156 plen -= flen;
3157 *len -= flen;
3158 } while (*len && plen);
3159
3160 return false;
3161}
3162
3163/*
3164 * Map linear and fragment data from the skb to spd. It reports true if the
3165 * pipe is full or if we already spliced the requested length.
3166 */
3167static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
3168 unsigned int *offset, unsigned int *len,
3169 struct splice_pipe_desc *spd, struct sock *sk)
3170{
3171 int seg;
3172 struct sk_buff *iter;
3173
3174 /* map the linear part :
3175 * If skb->head_frag is set, this 'linear' part is backed by a
3176 * fragment, and if the head is not shared with any clones then
3177 * we can avoid a copy since we own the head portion of this page.
3178 */
3179 if (__splice_segment(virt_to_page(skb->data),
3180 (unsigned long) skb->data & (PAGE_SIZE - 1),
3181 skb_headlen(skb),
3182 offset, len, spd,
3183 skb_head_is_locked(skb),
3184 sk, pipe))
3185 return true;
3186
3187 /*
3188 * then map the fragments
3189 */
3190 if (!skb_frags_readable(skb))
3191 return false;
3192
3193 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
3194 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
3195
3196 if (WARN_ON_ONCE(!skb_frag_page(f)))
3197 return false;
3198
3199 if (__splice_segment(skb_frag_page(f),
3200 skb_frag_off(f), skb_frag_size(f),
3201 offset, len, spd, false, sk, pipe))
3202 return true;
3203 }
3204
3205 skb_walk_frags(skb, iter) {
3206 if (*offset >= iter->len) {
3207 *offset -= iter->len;
3208 continue;
3209 }
3210 /* __skb_splice_bits() only fails if the output has no room
3211 * left, so no point in going over the frag_list for the error
3212 * case.
3213 */
3214 if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
3215 return true;
3216 }
3217
3218 return false;
3219}
3220
3221/*
3222 * Map data from the skb to a pipe. Should handle both the linear part,
3223 * the fragments, and the frag list.
3224 */
3225int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
3226 struct pipe_inode_info *pipe, unsigned int tlen,
3227 unsigned int flags)
3228{
3229 struct partial_page partial[MAX_SKB_FRAGS];
3230 struct page *pages[MAX_SKB_FRAGS];
3231 struct splice_pipe_desc spd = {
3232 .pages = pages,
3233 .partial = partial,
3234 .nr_pages_max = MAX_SKB_FRAGS,
3235 .ops = &nosteal_pipe_buf_ops,
3236 .spd_release = sock_spd_release,
3237 };
3238 int ret = 0;
3239
3240 __skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
3241
3242 if (spd.nr_pages)
3243 ret = splice_to_pipe(pipe, &spd);
3244
3245 return ret;
3246}
3247EXPORT_SYMBOL_GPL(skb_splice_bits);
3248
3249static int sendmsg_locked(struct sock *sk, struct msghdr *msg)
3250{
3251 struct socket *sock = sk->sk_socket;
3252 size_t size = msg_data_left(msg);
3253
3254 if (!sock)
3255 return -EINVAL;
3256
3257 if (!sock->ops->sendmsg_locked)
3258 return sock_no_sendmsg_locked(sk, msg, size);
3259
3260 return sock->ops->sendmsg_locked(sk, msg, size);
3261}
3262
3263static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg)
3264{
3265 struct socket *sock = sk->sk_socket;
3266
3267 if (!sock)
3268 return -EINVAL;
3269 return sock_sendmsg(sock, msg);
3270}
3271
3272typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg);
3273static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
3274 int len, sendmsg_func sendmsg)
3275{
3276 unsigned int orig_len = len;
3277 struct sk_buff *head = skb;
3278 unsigned short fragidx;
3279 int slen, ret;
3280
3281do_frag_list:
3282
3283 /* Deal with head data */
3284 while (offset < skb_headlen(skb) && len) {
3285 struct kvec kv;
3286 struct msghdr msg;
3287
3288 slen = min_t(int, len, skb_headlen(skb) - offset);
3289 kv.iov_base = skb->data + offset;
3290 kv.iov_len = slen;
3291 memset(&msg, 0, sizeof(msg));
3292 msg.msg_flags = MSG_DONTWAIT;
3293
3294 iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &kv, 1, slen);
3295 ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
3296 sendmsg_unlocked, sk, &msg);
3297 if (ret <= 0)
3298 goto error;
3299
3300 offset += ret;
3301 len -= ret;
3302 }
3303
3304 /* All the data was skb head? */
3305 if (!len)
3306 goto out;
3307
3308 /* Make offset relative to start of frags */
3309 offset -= skb_headlen(skb);
3310
3311 /* Find where we are in frag list */
3312 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
3313 skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
3314
3315 if (offset < skb_frag_size(frag))
3316 break;
3317
3318 offset -= skb_frag_size(frag);
3319 }
3320
3321 for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
3322 skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
3323
3324 slen = min_t(size_t, len, skb_frag_size(frag) - offset);
3325
3326 while (slen) {
3327 struct bio_vec bvec;
3328 struct msghdr msg = {
3329 .msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT,
3330 };
3331
3332 bvec_set_page(&bvec, skb_frag_page(frag), slen,
3333 skb_frag_off(frag) + offset);
3334 iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1,
3335 slen);
3336
3337 ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
3338 sendmsg_unlocked, sk, &msg);
3339 if (ret <= 0)
3340 goto error;
3341
3342 len -= ret;
3343 offset += ret;
3344 slen -= ret;
3345 }
3346
3347 offset = 0;
3348 }
3349
3350 if (len) {
3351 /* Process any frag lists */
3352
3353 if (skb == head) {
3354 if (skb_has_frag_list(skb)) {
3355 skb = skb_shinfo(skb)->frag_list;
3356 goto do_frag_list;
3357 }
3358 } else if (skb->next) {
3359 skb = skb->next;
3360 goto do_frag_list;
3361 }
3362 }
3363
3364out:
3365 return orig_len - len;
3366
3367error:
3368 return orig_len == len ? ret : orig_len - len;
3369}
3370
3371/* Send skb data on a socket. Socket must be locked. */
3372int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
3373 int len)
3374{
3375 return __skb_send_sock(sk, skb, offset, len, sendmsg_locked);
3376}
3377EXPORT_SYMBOL_GPL(skb_send_sock_locked);
3378
3379/* Send skb data on a socket. Socket must be unlocked. */
3380int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
3381{
3382 return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked);
3383}
3384
3385/**
3386 * skb_store_bits - store bits from kernel buffer to skb
3387 * @skb: destination buffer
3388 * @offset: offset in destination
3389 * @from: source buffer
3390 * @len: number of bytes to copy
3391 *
3392 * Copy the specified number of bytes from the source buffer to the
3393 * destination skb. This function handles all the messy bits of
3394 * traversing fragment lists and such.
3395 */
3396
3397int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
3398{
3399 int start = skb_headlen(skb);
3400 struct sk_buff *frag_iter;
3401 int i, copy;
3402
3403 if (offset > (int)skb->len - len)
3404 goto fault;
3405
3406 if ((copy = start - offset) > 0) {
3407 if (copy > len)
3408 copy = len;
3409 skb_copy_to_linear_data_offset(skb, offset, from, copy);
3410 if ((len -= copy) == 0)
3411 return 0;
3412 offset += copy;
3413 from += copy;
3414 }
3415
3416 if (!skb_frags_readable(skb))
3417 goto fault;
3418
3419 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3420 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3421 int end;
3422
3423 WARN_ON(start > offset + len);
3424
3425 end = start + skb_frag_size(frag);
3426 if ((copy = end - offset) > 0) {
3427 u32 p_off, p_len, copied;
3428 struct page *p;
3429 u8 *vaddr;
3430
3431 if (copy > len)
3432 copy = len;
3433
3434 skb_frag_foreach_page(frag,
3435 skb_frag_off(frag) + offset - start,
3436 copy, p, p_off, p_len, copied) {
3437 vaddr = kmap_atomic(p);
3438 memcpy(vaddr + p_off, from + copied, p_len);
3439 kunmap_atomic(vaddr);
3440 }
3441
3442 if ((len -= copy) == 0)
3443 return 0;
3444 offset += copy;
3445 from += copy;
3446 }
3447 start = end;
3448 }
3449
3450 skb_walk_frags(skb, frag_iter) {
3451 int end;
3452
3453 WARN_ON(start > offset + len);
3454
3455 end = start + frag_iter->len;
3456 if ((copy = end - offset) > 0) {
3457 if (copy > len)
3458 copy = len;
3459 if (skb_store_bits(frag_iter, offset - start,
3460 from, copy))
3461 goto fault;
3462 if ((len -= copy) == 0)
3463 return 0;
3464 offset += copy;
3465 from += copy;
3466 }
3467 start = end;
3468 }
3469 if (!len)
3470 return 0;
3471
3472fault:
3473 return -EFAULT;
3474}
3475EXPORT_SYMBOL(skb_store_bits);
3476
3477/* Checksum skb data. */
3478__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3479 __wsum csum, const struct skb_checksum_ops *ops)
3480{
3481 int start = skb_headlen(skb);
3482 int i, copy = start - offset;
3483 struct sk_buff *frag_iter;
3484 int pos = 0;
3485
3486 /* Checksum header. */
3487 if (copy > 0) {
3488 if (copy > len)
3489 copy = len;
3490 csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,
3491 skb->data + offset, copy, csum);
3492 if ((len -= copy) == 0)
3493 return csum;
3494 offset += copy;
3495 pos = copy;
3496 }
3497
3498 if (WARN_ON_ONCE(!skb_frags_readable(skb)))
3499 return 0;
3500
3501 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3502 int end;
3503 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3504
3505 WARN_ON(start > offset + len);
3506
3507 end = start + skb_frag_size(frag);
3508 if ((copy = end - offset) > 0) {
3509 u32 p_off, p_len, copied;
3510 struct page *p;
3511 __wsum csum2;
3512 u8 *vaddr;
3513
3514 if (copy > len)
3515 copy = len;
3516
3517 skb_frag_foreach_page(frag,
3518 skb_frag_off(frag) + offset - start,
3519 copy, p, p_off, p_len, copied) {
3520 vaddr = kmap_atomic(p);
3521 csum2 = INDIRECT_CALL_1(ops->update,
3522 csum_partial_ext,
3523 vaddr + p_off, p_len, 0);
3524 kunmap_atomic(vaddr);
3525 csum = INDIRECT_CALL_1(ops->combine,
3526 csum_block_add_ext, csum,
3527 csum2, pos, p_len);
3528 pos += p_len;
3529 }
3530
3531 if (!(len -= copy))
3532 return csum;
3533 offset += copy;
3534 }
3535 start = end;
3536 }
3537
3538 skb_walk_frags(skb, frag_iter) {
3539 int end;
3540
3541 WARN_ON(start > offset + len);
3542
3543 end = start + frag_iter->len;
3544 if ((copy = end - offset) > 0) {
3545 __wsum csum2;
3546 if (copy > len)
3547 copy = len;
3548 csum2 = __skb_checksum(frag_iter, offset - start,
3549 copy, 0, ops);
3550 csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,
3551 csum, csum2, pos, copy);
3552 if ((len -= copy) == 0)
3553 return csum;
3554 offset += copy;
3555 pos += copy;
3556 }
3557 start = end;
3558 }
3559 BUG_ON(len);
3560
3561 return csum;
3562}
3563EXPORT_SYMBOL(__skb_checksum);
3564
3565__wsum skb_checksum(const struct sk_buff *skb, int offset,
3566 int len, __wsum csum)
3567{
3568 const struct skb_checksum_ops ops = {
3569 .update = csum_partial_ext,
3570 .combine = csum_block_add_ext,
3571 };
3572
3573 return __skb_checksum(skb, offset, len, csum, &ops);
3574}
3575EXPORT_SYMBOL(skb_checksum);
3576
3577/* Both of above in one bottle. */
3578
3579__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
3580 u8 *to, int len)
3581{
3582 int start = skb_headlen(skb);
3583 int i, copy = start - offset;
3584 struct sk_buff *frag_iter;
3585 int pos = 0;
3586 __wsum csum = 0;
3587
3588 /* Copy header. */
3589 if (copy > 0) {
3590 if (copy > len)
3591 copy = len;
3592 csum = csum_partial_copy_nocheck(skb->data + offset, to,
3593 copy);
3594 if ((len -= copy) == 0)
3595 return csum;
3596 offset += copy;
3597 to += copy;
3598 pos = copy;
3599 }
3600
3601 if (!skb_frags_readable(skb))
3602 return 0;
3603
3604 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3605 int end;
3606
3607 WARN_ON(start > offset + len);
3608
3609 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3610 if ((copy = end - offset) > 0) {
3611 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3612 u32 p_off, p_len, copied;
3613 struct page *p;
3614 __wsum csum2;
3615 u8 *vaddr;
3616
3617 if (copy > len)
3618 copy = len;
3619
3620 skb_frag_foreach_page(frag,
3621 skb_frag_off(frag) + offset - start,
3622 copy, p, p_off, p_len, copied) {
3623 vaddr = kmap_atomic(p);
3624 csum2 = csum_partial_copy_nocheck(vaddr + p_off,
3625 to + copied,
3626 p_len);
3627 kunmap_atomic(vaddr);
3628 csum = csum_block_add(csum, csum2, pos);
3629 pos += p_len;
3630 }
3631
3632 if (!(len -= copy))
3633 return csum;
3634 offset += copy;
3635 to += copy;
3636 }
3637 start = end;
3638 }
3639
3640 skb_walk_frags(skb, frag_iter) {
3641 __wsum csum2;
3642 int end;
3643
3644 WARN_ON(start > offset + len);
3645
3646 end = start + frag_iter->len;
3647 if ((copy = end - offset) > 0) {
3648 if (copy > len)
3649 copy = len;
3650 csum2 = skb_copy_and_csum_bits(frag_iter,
3651 offset - start,
3652 to, copy);
3653 csum = csum_block_add(csum, csum2, pos);
3654 if ((len -= copy) == 0)
3655 return csum;
3656 offset += copy;
3657 to += copy;
3658 pos += copy;
3659 }
3660 start = end;
3661 }
3662 BUG_ON(len);
3663 return csum;
3664}
3665EXPORT_SYMBOL(skb_copy_and_csum_bits);
3666
3667__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
3668{
3669 __sum16 sum;
3670
3671 sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
3672 /* See comments in __skb_checksum_complete(). */
3673 if (likely(!sum)) {
3674 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
3675 !skb->csum_complete_sw)
3676 netdev_rx_csum_fault(skb->dev, skb);
3677 }
3678 if (!skb_shared(skb))
3679 skb->csum_valid = !sum;
3680 return sum;
3681}
3682EXPORT_SYMBOL(__skb_checksum_complete_head);
3683
3684/* This function assumes skb->csum already holds pseudo header's checksum,
3685 * which has been changed from the hardware checksum, for example, by
3686 * __skb_checksum_validate_complete(). And, the original skb->csum must
3687 * have been validated unsuccessfully for CHECKSUM_COMPLETE case.
3688 *
3689 * It returns non-zero if the recomputed checksum is still invalid, otherwise
3690 * zero. The new checksum is stored back into skb->csum unless the skb is
3691 * shared.
3692 */
3693__sum16 __skb_checksum_complete(struct sk_buff *skb)
3694{
3695 __wsum csum;
3696 __sum16 sum;
3697
3698 csum = skb_checksum(skb, 0, skb->len, 0);
3699
3700 sum = csum_fold(csum_add(skb->csum, csum));
3701 /* This check is inverted, because we already knew the hardware
3702 * checksum is invalid before calling this function. So, if the
3703 * re-computed checksum is valid instead, then we have a mismatch
3704 * between the original skb->csum and skb_checksum(). This means either
3705 * the original hardware checksum is incorrect or we screw up skb->csum
3706 * when moving skb->data around.
3707 */
3708 if (likely(!sum)) {
3709 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
3710 !skb->csum_complete_sw)
3711 netdev_rx_csum_fault(skb->dev, skb);
3712 }
3713
3714 if (!skb_shared(skb)) {
3715 /* Save full packet checksum */
3716 skb->csum = csum;
3717 skb->ip_summed = CHECKSUM_COMPLETE;
3718 skb->csum_complete_sw = 1;
3719 skb->csum_valid = !sum;
3720 }
3721
3722 return sum;
3723}
3724EXPORT_SYMBOL(__skb_checksum_complete);
3725
3726static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
3727{
3728 net_warn_ratelimited(
3729 "%s: attempt to compute crc32c without libcrc32c.ko\n",
3730 __func__);
3731 return 0;
3732}
3733
3734static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
3735 int offset, int len)
3736{
3737 net_warn_ratelimited(
3738 "%s: attempt to compute crc32c without libcrc32c.ko\n",
3739 __func__);
3740 return 0;
3741}
3742
3743static const struct skb_checksum_ops default_crc32c_ops = {
3744 .update = warn_crc32c_csum_update,
3745 .combine = warn_crc32c_csum_combine,
3746};
3747
3748const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
3749 &default_crc32c_ops;
3750EXPORT_SYMBOL(crc32c_csum_stub);
3751
3752 /**
3753 * skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
3754 * @from: source buffer
3755 *
3756 * Calculates the amount of linear headroom needed in the 'to' skb passed
3757 * into skb_zerocopy().
3758 */
3759unsigned int
3760skb_zerocopy_headlen(const struct sk_buff *from)
3761{
3762 unsigned int hlen = 0;
3763
3764 if (!from->head_frag ||
3765 skb_headlen(from) < L1_CACHE_BYTES ||
3766 skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) {
3767 hlen = skb_headlen(from);
3768 if (!hlen)
3769 hlen = from->len;
3770 }
3771
3772 if (skb_has_frag_list(from))
3773 hlen = from->len;
3774
3775 return hlen;
3776}
3777EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
3778
3779/**
3780 * skb_zerocopy - Zero copy skb to skb
3781 * @to: destination buffer
3782 * @from: source buffer
3783 * @len: number of bytes to copy from source buffer
3784 * @hlen: size of linear headroom in destination buffer
3785 *
3786 * Copies up to `len` bytes from `from` to `to` by creating references
3787 * to the frags in the source buffer.
3788 *
3789 * The `hlen` as calculated by skb_zerocopy_headlen() specifies the
3790 * headroom in the `to` buffer.
3791 *
3792 * Return value:
3793 * 0: everything is OK
3794 * -ENOMEM: couldn't orphan frags of @from due to lack of memory
3795 * -EFAULT: skb_copy_bits() found some problem with skb geometry
3796 */
3797int
3798skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
3799{
3800 int i, j = 0;
3801 int plen = 0; /* length of skb->head fragment */
3802 int ret;
3803 struct page *page;
3804 unsigned int offset;
3805
3806 BUG_ON(!from->head_frag && !hlen);
3807
3808 /* dont bother with small payloads */
3809 if (len <= skb_tailroom(to))
3810 return skb_copy_bits(from, 0, skb_put(to, len), len);
3811
3812 if (hlen) {
3813 ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
3814 if (unlikely(ret))
3815 return ret;
3816 len -= hlen;
3817 } else {
3818 plen = min_t(int, skb_headlen(from), len);
3819 if (plen) {
3820 page = virt_to_head_page(from->head);
3821 offset = from->data - (unsigned char *)page_address(page);
3822 __skb_fill_netmem_desc(to, 0, page_to_netmem(page),
3823 offset, plen);
3824 get_page(page);
3825 j = 1;
3826 len -= plen;
3827 }
3828 }
3829
3830 skb_len_add(to, len + plen);
3831
3832 if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
3833 skb_tx_error(from);
3834 return -ENOMEM;
3835 }
3836 skb_zerocopy_clone(to, from, GFP_ATOMIC);
3837
3838 for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
3839 int size;
3840
3841 if (!len)
3842 break;
3843 skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
3844 size = min_t(int, skb_frag_size(&skb_shinfo(to)->frags[j]),
3845 len);
3846 skb_frag_size_set(&skb_shinfo(to)->frags[j], size);
3847 len -= size;
3848 skb_frag_ref(to, j);
3849 j++;
3850 }
3851 skb_shinfo(to)->nr_frags = j;
3852
3853 return 0;
3854}
3855EXPORT_SYMBOL_GPL(skb_zerocopy);
3856
3857void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
3858{
3859 __wsum csum;
3860 long csstart;
3861
3862 if (skb->ip_summed == CHECKSUM_PARTIAL)
3863 csstart = skb_checksum_start_offset(skb);
3864 else
3865 csstart = skb_headlen(skb);
3866
3867 BUG_ON(csstart > skb_headlen(skb));
3868
3869 skb_copy_from_linear_data(skb, to, csstart);
3870
3871 csum = 0;
3872 if (csstart != skb->len)
3873 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
3874 skb->len - csstart);
3875
3876 if (skb->ip_summed == CHECKSUM_PARTIAL) {
3877 long csstuff = csstart + skb->csum_offset;
3878
3879 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
3880 }
3881}
3882EXPORT_SYMBOL(skb_copy_and_csum_dev);
3883
3884/**
3885 * skb_dequeue - remove from the head of the queue
3886 * @list: list to dequeue from
3887 *
3888 * Remove the head of the list. The list lock is taken so the function
3889 * may be used safely with other locking list functions. The head item is
3890 * returned or %NULL if the list is empty.
3891 */
3892
3893struct sk_buff *skb_dequeue(struct sk_buff_head *list)
3894{
3895 unsigned long flags;
3896 struct sk_buff *result;
3897
3898 spin_lock_irqsave(&list->lock, flags);
3899 result = __skb_dequeue(list);
3900 spin_unlock_irqrestore(&list->lock, flags);
3901 return result;
3902}
3903EXPORT_SYMBOL(skb_dequeue);
3904
3905/**
3906 * skb_dequeue_tail - remove from the tail of the queue
3907 * @list: list to dequeue from
3908 *
3909 * Remove the tail of the list. The list lock is taken so the function
3910 * may be used safely with other locking list functions. The tail item is
3911 * returned or %NULL if the list is empty.
3912 */
3913struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
3914{
3915 unsigned long flags;
3916 struct sk_buff *result;
3917
3918 spin_lock_irqsave(&list->lock, flags);
3919 result = __skb_dequeue_tail(list);
3920 spin_unlock_irqrestore(&list->lock, flags);
3921 return result;
3922}
3923EXPORT_SYMBOL(skb_dequeue_tail);
3924
3925/**
3926 * skb_queue_purge_reason - empty a list
3927 * @list: list to empty
3928 * @reason: drop reason
3929 *
3930 * Delete all buffers on an &sk_buff list. Each buffer is removed from
3931 * the list and one reference dropped. This function takes the list
3932 * lock and is atomic with respect to other list locking functions.
3933 */
3934void skb_queue_purge_reason(struct sk_buff_head *list,
3935 enum skb_drop_reason reason)
3936{
3937 struct sk_buff_head tmp;
3938 unsigned long flags;
3939
3940 if (skb_queue_empty_lockless(list))
3941 return;
3942
3943 __skb_queue_head_init(&tmp);
3944
3945 spin_lock_irqsave(&list->lock, flags);
3946 skb_queue_splice_init(list, &tmp);
3947 spin_unlock_irqrestore(&list->lock, flags);
3948
3949 __skb_queue_purge_reason(&tmp, reason);
3950}
3951EXPORT_SYMBOL(skb_queue_purge_reason);
3952
3953/**
3954 * skb_rbtree_purge - empty a skb rbtree
3955 * @root: root of the rbtree to empty
3956 * Return value: the sum of truesizes of all purged skbs.
3957 *
3958 * Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
3959 * the list and one reference dropped. This function does not take
3960 * any lock. Synchronization should be handled by the caller (e.g., TCP
3961 * out-of-order queue is protected by the socket lock).
3962 */
3963unsigned int skb_rbtree_purge(struct rb_root *root)
3964{
3965 struct rb_node *p = rb_first(root);
3966 unsigned int sum = 0;
3967
3968 while (p) {
3969 struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
3970
3971 p = rb_next(p);
3972 rb_erase(&skb->rbnode, root);
3973 sum += skb->truesize;
3974 kfree_skb(skb);
3975 }
3976 return sum;
3977}
3978
3979void skb_errqueue_purge(struct sk_buff_head *list)
3980{
3981 struct sk_buff *skb, *next;
3982 struct sk_buff_head kill;
3983 unsigned long flags;
3984
3985 __skb_queue_head_init(&kill);
3986
3987 spin_lock_irqsave(&list->lock, flags);
3988 skb_queue_walk_safe(list, skb, next) {
3989 if (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ZEROCOPY ||
3990 SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING)
3991 continue;
3992 __skb_unlink(skb, list);
3993 __skb_queue_tail(&kill, skb);
3994 }
3995 spin_unlock_irqrestore(&list->lock, flags);
3996 __skb_queue_purge(&kill);
3997}
3998EXPORT_SYMBOL(skb_errqueue_purge);
3999
4000/**
4001 * skb_queue_head - queue a buffer at the list head
4002 * @list: list to use
4003 * @newsk: buffer to queue
4004 *
4005 * Queue a buffer at the start of the list. This function takes the
4006 * list lock and can be used safely with other locking &sk_buff functions
4007 * safely.
4008 *
4009 * A buffer cannot be placed on two lists at the same time.
4010 */
4011void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
4012{
4013 unsigned long flags;
4014
4015 spin_lock_irqsave(&list->lock, flags);
4016 __skb_queue_head(list, newsk);
4017 spin_unlock_irqrestore(&list->lock, flags);
4018}
4019EXPORT_SYMBOL(skb_queue_head);
4020
4021/**
4022 * skb_queue_tail - queue a buffer at the list tail
4023 * @list: list to use
4024 * @newsk: buffer to queue
4025 *
4026 * Queue a buffer at the tail of the list. This function takes the
4027 * list lock and can be used safely with other locking &sk_buff functions
4028 * safely.
4029 *
4030 * A buffer cannot be placed on two lists at the same time.
4031 */
4032void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
4033{
4034 unsigned long flags;
4035
4036 spin_lock_irqsave(&list->lock, flags);
4037 __skb_queue_tail(list, newsk);
4038 spin_unlock_irqrestore(&list->lock, flags);
4039}
4040EXPORT_SYMBOL(skb_queue_tail);
4041
4042/**
4043 * skb_unlink - remove a buffer from a list
4044 * @skb: buffer to remove
4045 * @list: list to use
4046 *
4047 * Remove a packet from a list. The list locks are taken and this
4048 * function is atomic with respect to other list locked calls
4049 *
4050 * You must know what list the SKB is on.
4051 */
4052void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
4053{
4054 unsigned long flags;
4055
4056 spin_lock_irqsave(&list->lock, flags);
4057 __skb_unlink(skb, list);
4058 spin_unlock_irqrestore(&list->lock, flags);
4059}
4060EXPORT_SYMBOL(skb_unlink);
4061
4062/**
4063 * skb_append - append a buffer
4064 * @old: buffer to insert after
4065 * @newsk: buffer to insert
4066 * @list: list to use
4067 *
4068 * Place a packet after a given packet in a list. The list locks are taken
4069 * and this function is atomic with respect to other list locked calls.
4070 * A buffer cannot be placed on two lists at the same time.
4071 */
4072void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
4073{
4074 unsigned long flags;
4075
4076 spin_lock_irqsave(&list->lock, flags);
4077 __skb_queue_after(list, old, newsk);
4078 spin_unlock_irqrestore(&list->lock, flags);
4079}
4080EXPORT_SYMBOL(skb_append);
4081
4082static inline void skb_split_inside_header(struct sk_buff *skb,
4083 struct sk_buff* skb1,
4084 const u32 len, const int pos)
4085{
4086 int i;
4087
4088 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
4089 pos - len);
4090 /* And move data appendix as is. */
4091 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
4092 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
4093
4094 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
4095 skb1->unreadable = skb->unreadable;
4096 skb_shinfo(skb)->nr_frags = 0;
4097 skb1->data_len = skb->data_len;
4098 skb1->len += skb1->data_len;
4099 skb->data_len = 0;
4100 skb->len = len;
4101 skb_set_tail_pointer(skb, len);
4102}
4103
4104static inline void skb_split_no_header(struct sk_buff *skb,
4105 struct sk_buff* skb1,
4106 const u32 len, int pos)
4107{
4108 int i, k = 0;
4109 const int nfrags = skb_shinfo(skb)->nr_frags;
4110
4111 skb_shinfo(skb)->nr_frags = 0;
4112 skb1->len = skb1->data_len = skb->len - len;
4113 skb->len = len;
4114 skb->data_len = len - pos;
4115
4116 for (i = 0; i < nfrags; i++) {
4117 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
4118
4119 if (pos + size > len) {
4120 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
4121
4122 if (pos < len) {
4123 /* Split frag.
4124 * We have two variants in this case:
4125 * 1. Move all the frag to the second
4126 * part, if it is possible. F.e.
4127 * this approach is mandatory for TUX,
4128 * where splitting is expensive.
4129 * 2. Split is accurately. We make this.
4130 */
4131 skb_frag_ref(skb, i);
4132 skb_frag_off_add(&skb_shinfo(skb1)->frags[0], len - pos);
4133 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
4134 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
4135 skb_shinfo(skb)->nr_frags++;
4136 }
4137 k++;
4138 } else
4139 skb_shinfo(skb)->nr_frags++;
4140 pos += size;
4141 }
4142 skb_shinfo(skb1)->nr_frags = k;
4143
4144 skb1->unreadable = skb->unreadable;
4145}
4146
4147/**
4148 * skb_split - Split fragmented skb to two parts at length len.
4149 * @skb: the buffer to split
4150 * @skb1: the buffer to receive the second part
4151 * @len: new length for skb
4152 */
4153void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
4154{
4155 int pos = skb_headlen(skb);
4156 const int zc_flags = SKBFL_SHARED_FRAG | SKBFL_PURE_ZEROCOPY;
4157
4158 skb_zcopy_downgrade_managed(skb);
4159
4160 skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & zc_flags;
4161 skb_zerocopy_clone(skb1, skb, 0);
4162 if (len < pos) /* Split line is inside header. */
4163 skb_split_inside_header(skb, skb1, len, pos);
4164 else /* Second chunk has no header, nothing to copy. */
4165 skb_split_no_header(skb, skb1, len, pos);
4166}
4167EXPORT_SYMBOL(skb_split);
4168
4169/* Shifting from/to a cloned skb is a no-go.
4170 *
4171 * Caller cannot keep skb_shinfo related pointers past calling here!
4172 */
4173static int skb_prepare_for_shift(struct sk_buff *skb)
4174{
4175 return skb_unclone_keeptruesize(skb, GFP_ATOMIC);
4176}
4177
4178/**
4179 * skb_shift - Shifts paged data partially from skb to another
4180 * @tgt: buffer into which tail data gets added
4181 * @skb: buffer from which the paged data comes from
4182 * @shiftlen: shift up to this many bytes
4183 *
4184 * Attempts to shift up to shiftlen worth of bytes, which may be less than
4185 * the length of the skb, from skb to tgt. Returns number bytes shifted.
4186 * It's up to caller to free skb if everything was shifted.
4187 *
4188 * If @tgt runs out of frags, the whole operation is aborted.
4189 *
4190 * Skb cannot include anything else but paged data while tgt is allowed
4191 * to have non-paged data as well.
4192 *
4193 * TODO: full sized shift could be optimized but that would need
4194 * specialized skb free'er to handle frags without up-to-date nr_frags.
4195 */
4196int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
4197{
4198 int from, to, merge, todo;
4199 skb_frag_t *fragfrom, *fragto;
4200
4201 BUG_ON(shiftlen > skb->len);
4202
4203 if (skb_headlen(skb))
4204 return 0;
4205 if (skb_zcopy(tgt) || skb_zcopy(skb))
4206 return 0;
4207
4208 DEBUG_NET_WARN_ON_ONCE(tgt->pp_recycle != skb->pp_recycle);
4209 DEBUG_NET_WARN_ON_ONCE(skb_cmp_decrypted(tgt, skb));
4210
4211 todo = shiftlen;
4212 from = 0;
4213 to = skb_shinfo(tgt)->nr_frags;
4214 fragfrom = &skb_shinfo(skb)->frags[from];
4215
4216 /* Actual merge is delayed until the point when we know we can
4217 * commit all, so that we don't have to undo partial changes
4218 */
4219 if (!skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
4220 skb_frag_off(fragfrom))) {
4221 merge = -1;
4222 } else {
4223 merge = to - 1;
4224
4225 todo -= skb_frag_size(fragfrom);
4226 if (todo < 0) {
4227 if (skb_prepare_for_shift(skb) ||
4228 skb_prepare_for_shift(tgt))
4229 return 0;
4230
4231 /* All previous frag pointers might be stale! */
4232 fragfrom = &skb_shinfo(skb)->frags[from];
4233 fragto = &skb_shinfo(tgt)->frags[merge];
4234
4235 skb_frag_size_add(fragto, shiftlen);
4236 skb_frag_size_sub(fragfrom, shiftlen);
4237 skb_frag_off_add(fragfrom, shiftlen);
4238
4239 goto onlymerged;
4240 }
4241
4242 from++;
4243 }
4244
4245 /* Skip full, not-fitting skb to avoid expensive operations */
4246 if ((shiftlen == skb->len) &&
4247 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
4248 return 0;
4249
4250 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
4251 return 0;
4252
4253 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
4254 if (to == MAX_SKB_FRAGS)
4255 return 0;
4256
4257 fragfrom = &skb_shinfo(skb)->frags[from];
4258 fragto = &skb_shinfo(tgt)->frags[to];
4259
4260 if (todo >= skb_frag_size(fragfrom)) {
4261 *fragto = *fragfrom;
4262 todo -= skb_frag_size(fragfrom);
4263 from++;
4264 to++;
4265
4266 } else {
4267 __skb_frag_ref(fragfrom);
4268 skb_frag_page_copy(fragto, fragfrom);
4269 skb_frag_off_copy(fragto, fragfrom);
4270 skb_frag_size_set(fragto, todo);
4271
4272 skb_frag_off_add(fragfrom, todo);
4273 skb_frag_size_sub(fragfrom, todo);
4274 todo = 0;
4275
4276 to++;
4277 break;
4278 }
4279 }
4280
4281 /* Ready to "commit" this state change to tgt */
4282 skb_shinfo(tgt)->nr_frags = to;
4283
4284 if (merge >= 0) {
4285 fragfrom = &skb_shinfo(skb)->frags[0];
4286 fragto = &skb_shinfo(tgt)->frags[merge];
4287
4288 skb_frag_size_add(fragto, skb_frag_size(fragfrom));
4289 __skb_frag_unref(fragfrom, skb->pp_recycle);
4290 }
4291
4292 /* Reposition in the original skb */
4293 to = 0;
4294 while (from < skb_shinfo(skb)->nr_frags)
4295 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
4296 skb_shinfo(skb)->nr_frags = to;
4297
4298 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
4299
4300onlymerged:
4301 /* Most likely the tgt won't ever need its checksum anymore, skb on
4302 * the other hand might need it if it needs to be resent
4303 */
4304 tgt->ip_summed = CHECKSUM_PARTIAL;
4305 skb->ip_summed = CHECKSUM_PARTIAL;
4306
4307 skb_len_add(skb, -shiftlen);
4308 skb_len_add(tgt, shiftlen);
4309
4310 return shiftlen;
4311}
4312
4313/**
4314 * skb_prepare_seq_read - Prepare a sequential read of skb data
4315 * @skb: the buffer to read
4316 * @from: lower offset of data to be read
4317 * @to: upper offset of data to be read
4318 * @st: state variable
4319 *
4320 * Initializes the specified state variable. Must be called before
4321 * invoking skb_seq_read() for the first time.
4322 */
4323void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
4324 unsigned int to, struct skb_seq_state *st)
4325{
4326 st->lower_offset = from;
4327 st->upper_offset = to;
4328 st->root_skb = st->cur_skb = skb;
4329 st->frag_idx = st->stepped_offset = 0;
4330 st->frag_data = NULL;
4331 st->frag_off = 0;
4332}
4333EXPORT_SYMBOL(skb_prepare_seq_read);
4334
4335/**
4336 * skb_seq_read - Sequentially read skb data
4337 * @consumed: number of bytes consumed by the caller so far
4338 * @data: destination pointer for data to be returned
4339 * @st: state variable
4340 *
4341 * Reads a block of skb data at @consumed relative to the
4342 * lower offset specified to skb_prepare_seq_read(). Assigns
4343 * the head of the data block to @data and returns the length
4344 * of the block or 0 if the end of the skb data or the upper
4345 * offset has been reached.
4346 *
4347 * The caller is not required to consume all of the data
4348 * returned, i.e. @consumed is typically set to the number
4349 * of bytes already consumed and the next call to
4350 * skb_seq_read() will return the remaining part of the block.
4351 *
4352 * Note 1: The size of each block of data returned can be arbitrary,
4353 * this limitation is the cost for zerocopy sequential
4354 * reads of potentially non linear data.
4355 *
4356 * Note 2: Fragment lists within fragments are not implemented
4357 * at the moment, state->root_skb could be replaced with
4358 * a stack for this purpose.
4359 */
4360unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
4361 struct skb_seq_state *st)
4362{
4363 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
4364 skb_frag_t *frag;
4365
4366 if (unlikely(abs_offset >= st->upper_offset)) {
4367 if (st->frag_data) {
4368 kunmap_atomic(st->frag_data);
4369 st->frag_data = NULL;
4370 }
4371 return 0;
4372 }
4373
4374next_skb:
4375 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
4376
4377 if (abs_offset < block_limit && !st->frag_data) {
4378 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
4379 return block_limit - abs_offset;
4380 }
4381
4382 if (!skb_frags_readable(st->cur_skb))
4383 return 0;
4384
4385 if (st->frag_idx == 0 && !st->frag_data)
4386 st->stepped_offset += skb_headlen(st->cur_skb);
4387
4388 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
4389 unsigned int pg_idx, pg_off, pg_sz;
4390
4391 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
4392
4393 pg_idx = 0;
4394 pg_off = skb_frag_off(frag);
4395 pg_sz = skb_frag_size(frag);
4396
4397 if (skb_frag_must_loop(skb_frag_page(frag))) {
4398 pg_idx = (pg_off + st->frag_off) >> PAGE_SHIFT;
4399 pg_off = offset_in_page(pg_off + st->frag_off);
4400 pg_sz = min_t(unsigned int, pg_sz - st->frag_off,
4401 PAGE_SIZE - pg_off);
4402 }
4403
4404 block_limit = pg_sz + st->stepped_offset;
4405 if (abs_offset < block_limit) {
4406 if (!st->frag_data)
4407 st->frag_data = kmap_atomic(skb_frag_page(frag) + pg_idx);
4408
4409 *data = (u8 *)st->frag_data + pg_off +
4410 (abs_offset - st->stepped_offset);
4411
4412 return block_limit - abs_offset;
4413 }
4414
4415 if (st->frag_data) {
4416 kunmap_atomic(st->frag_data);
4417 st->frag_data = NULL;
4418 }
4419
4420 st->stepped_offset += pg_sz;
4421 st->frag_off += pg_sz;
4422 if (st->frag_off == skb_frag_size(frag)) {
4423 st->frag_off = 0;
4424 st->frag_idx++;
4425 }
4426 }
4427
4428 if (st->frag_data) {
4429 kunmap_atomic(st->frag_data);
4430 st->frag_data = NULL;
4431 }
4432
4433 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
4434 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
4435 st->frag_idx = 0;
4436 goto next_skb;
4437 } else if (st->cur_skb->next) {
4438 st->cur_skb = st->cur_skb->next;
4439 st->frag_idx = 0;
4440 goto next_skb;
4441 }
4442
4443 return 0;
4444}
4445EXPORT_SYMBOL(skb_seq_read);
4446
4447/**
4448 * skb_abort_seq_read - Abort a sequential read of skb data
4449 * @st: state variable
4450 *
4451 * Must be called if skb_seq_read() was not called until it
4452 * returned 0.
4453 */
4454void skb_abort_seq_read(struct skb_seq_state *st)
4455{
4456 if (st->frag_data)
4457 kunmap_atomic(st->frag_data);
4458}
4459EXPORT_SYMBOL(skb_abort_seq_read);
4460
4461/**
4462 * skb_copy_seq_read() - copy from a skb_seq_state to a buffer
4463 * @st: source skb_seq_state
4464 * @offset: offset in source
4465 * @to: destination buffer
4466 * @len: number of bytes to copy
4467 *
4468 * Copy @len bytes from @offset bytes into the source @st to the destination
4469 * buffer @to. `offset` should increase (or be unchanged) with each subsequent
4470 * call to this function. If offset needs to decrease from the previous use `st`
4471 * should be reset first.
4472 *
4473 * Return: 0 on success or -EINVAL if the copy ended early
4474 */
4475int skb_copy_seq_read(struct skb_seq_state *st, int offset, void *to, int len)
4476{
4477 const u8 *data;
4478 u32 sqlen;
4479
4480 for (;;) {
4481 sqlen = skb_seq_read(offset, &data, st);
4482 if (sqlen == 0)
4483 return -EINVAL;
4484 if (sqlen >= len) {
4485 memcpy(to, data, len);
4486 return 0;
4487 }
4488 memcpy(to, data, sqlen);
4489 to += sqlen;
4490 offset += sqlen;
4491 len -= sqlen;
4492 }
4493}
4494EXPORT_SYMBOL(skb_copy_seq_read);
4495
4496#define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
4497
4498static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
4499 struct ts_config *conf,
4500 struct ts_state *state)
4501{
4502 return skb_seq_read(offset, text, TS_SKB_CB(state));
4503}
4504
4505static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
4506{
4507 skb_abort_seq_read(TS_SKB_CB(state));
4508}
4509
4510/**
4511 * skb_find_text - Find a text pattern in skb data
4512 * @skb: the buffer to look in
4513 * @from: search offset
4514 * @to: search limit
4515 * @config: textsearch configuration
4516 *
4517 * Finds a pattern in the skb data according to the specified
4518 * textsearch configuration. Use textsearch_next() to retrieve
4519 * subsequent occurrences of the pattern. Returns the offset
4520 * to the first occurrence or UINT_MAX if no match was found.
4521 */
4522unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
4523 unsigned int to, struct ts_config *config)
4524{
4525 unsigned int patlen = config->ops->get_pattern_len(config);
4526 struct ts_state state;
4527 unsigned int ret;
4528
4529 BUILD_BUG_ON(sizeof(struct skb_seq_state) > sizeof(state.cb));
4530
4531 config->get_next_block = skb_ts_get_next_block;
4532 config->finish = skb_ts_finish;
4533
4534 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
4535
4536 ret = textsearch_find(config, &state);
4537 return (ret + patlen <= to - from ? ret : UINT_MAX);
4538}
4539EXPORT_SYMBOL(skb_find_text);
4540
4541int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
4542 int offset, size_t size, size_t max_frags)
4543{
4544 int i = skb_shinfo(skb)->nr_frags;
4545
4546 if (skb_can_coalesce(skb, i, page, offset)) {
4547 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
4548 } else if (i < max_frags) {
4549 skb_zcopy_downgrade_managed(skb);
4550 get_page(page);
4551 skb_fill_page_desc_noacc(skb, i, page, offset, size);
4552 } else {
4553 return -EMSGSIZE;
4554 }
4555
4556 return 0;
4557}
4558EXPORT_SYMBOL_GPL(skb_append_pagefrags);
4559
4560/**
4561 * skb_pull_rcsum - pull skb and update receive checksum
4562 * @skb: buffer to update
4563 * @len: length of data pulled
4564 *
4565 * This function performs an skb_pull on the packet and updates
4566 * the CHECKSUM_COMPLETE checksum. It should be used on
4567 * receive path processing instead of skb_pull unless you know
4568 * that the checksum difference is zero (e.g., a valid IP header)
4569 * or you are setting ip_summed to CHECKSUM_NONE.
4570 */
4571void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
4572{
4573 unsigned char *data = skb->data;
4574
4575 BUG_ON(len > skb->len);
4576 __skb_pull(skb, len);
4577 skb_postpull_rcsum(skb, data, len);
4578 return skb->data;
4579}
4580EXPORT_SYMBOL_GPL(skb_pull_rcsum);
4581
4582static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
4583{
4584 skb_frag_t head_frag;
4585 struct page *page;
4586
4587 page = virt_to_head_page(frag_skb->head);
4588 skb_frag_fill_page_desc(&head_frag, page, frag_skb->data -
4589 (unsigned char *)page_address(page),
4590 skb_headlen(frag_skb));
4591 return head_frag;
4592}
4593
4594struct sk_buff *skb_segment_list(struct sk_buff *skb,
4595 netdev_features_t features,
4596 unsigned int offset)
4597{
4598 struct sk_buff *list_skb = skb_shinfo(skb)->frag_list;
4599 unsigned int tnl_hlen = skb_tnl_header_len(skb);
4600 unsigned int delta_truesize = 0;
4601 unsigned int delta_len = 0;
4602 struct sk_buff *tail = NULL;
4603 struct sk_buff *nskb, *tmp;
4604 int len_diff, err;
4605
4606 skb_push(skb, -skb_network_offset(skb) + offset);
4607
4608 /* Ensure the head is writeable before touching the shared info */
4609 err = skb_unclone(skb, GFP_ATOMIC);
4610 if (err)
4611 goto err_linearize;
4612
4613 skb_shinfo(skb)->frag_list = NULL;
4614
4615 while (list_skb) {
4616 nskb = list_skb;
4617 list_skb = list_skb->next;
4618
4619 err = 0;
4620 delta_truesize += nskb->truesize;
4621 if (skb_shared(nskb)) {
4622 tmp = skb_clone(nskb, GFP_ATOMIC);
4623 if (tmp) {
4624 consume_skb(nskb);
4625 nskb = tmp;
4626 err = skb_unclone(nskb, GFP_ATOMIC);
4627 } else {
4628 err = -ENOMEM;
4629 }
4630 }
4631
4632 if (!tail)
4633 skb->next = nskb;
4634 else
4635 tail->next = nskb;
4636
4637 if (unlikely(err)) {
4638 nskb->next = list_skb;
4639 goto err_linearize;
4640 }
4641
4642 tail = nskb;
4643
4644 delta_len += nskb->len;
4645
4646 skb_push(nskb, -skb_network_offset(nskb) + offset);
4647
4648 skb_release_head_state(nskb);
4649 len_diff = skb_network_header_len(nskb) - skb_network_header_len(skb);
4650 __copy_skb_header(nskb, skb);
4651
4652 skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
4653 nskb->transport_header += len_diff;
4654 skb_copy_from_linear_data_offset(skb, -tnl_hlen,
4655 nskb->data - tnl_hlen,
4656 offset + tnl_hlen);
4657
4658 if (skb_needs_linearize(nskb, features) &&
4659 __skb_linearize(nskb))
4660 goto err_linearize;
4661 }
4662
4663 skb->truesize = skb->truesize - delta_truesize;
4664 skb->data_len = skb->data_len - delta_len;
4665 skb->len = skb->len - delta_len;
4666
4667 skb_gso_reset(skb);
4668
4669 skb->prev = tail;
4670
4671 if (skb_needs_linearize(skb, features) &&
4672 __skb_linearize(skb))
4673 goto err_linearize;
4674
4675 skb_get(skb);
4676
4677 return skb;
4678
4679err_linearize:
4680 kfree_skb_list(skb->next);
4681 skb->next = NULL;
4682 return ERR_PTR(-ENOMEM);
4683}
4684EXPORT_SYMBOL_GPL(skb_segment_list);
4685
4686/**
4687 * skb_segment - Perform protocol segmentation on skb.
4688 * @head_skb: buffer to segment
4689 * @features: features for the output path (see dev->features)
4690 *
4691 * This function performs segmentation on the given skb. It returns
4692 * a pointer to the first in a list of new skbs for the segments.
4693 * In case of error it returns ERR_PTR(err).
4694 */
4695struct sk_buff *skb_segment(struct sk_buff *head_skb,
4696 netdev_features_t features)
4697{
4698 struct sk_buff *segs = NULL;
4699 struct sk_buff *tail = NULL;
4700 struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
4701 unsigned int mss = skb_shinfo(head_skb)->gso_size;
4702 unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
4703 unsigned int offset = doffset;
4704 unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
4705 unsigned int partial_segs = 0;
4706 unsigned int headroom;
4707 unsigned int len = head_skb->len;
4708 struct sk_buff *frag_skb;
4709 skb_frag_t *frag;
4710 __be16 proto;
4711 bool csum, sg;
4712 int err = -ENOMEM;
4713 int i = 0;
4714 int nfrags, pos;
4715
4716 if ((skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY) &&
4717 mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb)) {
4718 struct sk_buff *check_skb;
4719
4720 for (check_skb = list_skb; check_skb; check_skb = check_skb->next) {
4721 if (skb_headlen(check_skb) && !check_skb->head_frag) {
4722 /* gso_size is untrusted, and we have a frag_list with
4723 * a linear non head_frag item.
4724 *
4725 * If head_skb's headlen does not fit requested gso_size,
4726 * it means that the frag_list members do NOT terminate
4727 * on exact gso_size boundaries. Hence we cannot perform
4728 * skb_frag_t page sharing. Therefore we must fallback to
4729 * copying the frag_list skbs; we do so by disabling SG.
4730 */
4731 features &= ~NETIF_F_SG;
4732 break;
4733 }
4734 }
4735 }
4736
4737 __skb_push(head_skb, doffset);
4738 proto = skb_network_protocol(head_skb, NULL);
4739 if (unlikely(!proto))
4740 return ERR_PTR(-EINVAL);
4741
4742 sg = !!(features & NETIF_F_SG);
4743 csum = !!can_checksum_protocol(features, proto);
4744
4745 if (sg && csum && (mss != GSO_BY_FRAGS)) {
4746 if (!(features & NETIF_F_GSO_PARTIAL)) {
4747 struct sk_buff *iter;
4748 unsigned int frag_len;
4749
4750 if (!list_skb ||
4751 !net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
4752 goto normal;
4753
4754 /* If we get here then all the required
4755 * GSO features except frag_list are supported.
4756 * Try to split the SKB to multiple GSO SKBs
4757 * with no frag_list.
4758 * Currently we can do that only when the buffers don't
4759 * have a linear part and all the buffers except
4760 * the last are of the same length.
4761 */
4762 frag_len = list_skb->len;
4763 skb_walk_frags(head_skb, iter) {
4764 if (frag_len != iter->len && iter->next)
4765 goto normal;
4766 if (skb_headlen(iter) && !iter->head_frag)
4767 goto normal;
4768
4769 len -= iter->len;
4770 }
4771
4772 if (len != frag_len)
4773 goto normal;
4774 }
4775
4776 /* GSO partial only requires that we trim off any excess that
4777 * doesn't fit into an MSS sized block, so take care of that
4778 * now.
4779 * Cap len to not accidentally hit GSO_BY_FRAGS.
4780 */
4781 partial_segs = min(len, GSO_BY_FRAGS - 1) / mss;
4782 if (partial_segs > 1)
4783 mss *= partial_segs;
4784 else
4785 partial_segs = 0;
4786 }
4787
4788normal:
4789 headroom = skb_headroom(head_skb);
4790 pos = skb_headlen(head_skb);
4791
4792 if (skb_orphan_frags(head_skb, GFP_ATOMIC))
4793 return ERR_PTR(-ENOMEM);
4794
4795 nfrags = skb_shinfo(head_skb)->nr_frags;
4796 frag = skb_shinfo(head_skb)->frags;
4797 frag_skb = head_skb;
4798
4799 do {
4800 struct sk_buff *nskb;
4801 skb_frag_t *nskb_frag;
4802 int hsize;
4803 int size;
4804
4805 if (unlikely(mss == GSO_BY_FRAGS)) {
4806 len = list_skb->len;
4807 } else {
4808 len = head_skb->len - offset;
4809 if (len > mss)
4810 len = mss;
4811 }
4812
4813 hsize = skb_headlen(head_skb) - offset;
4814
4815 if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
4816 (skb_headlen(list_skb) == len || sg)) {
4817 BUG_ON(skb_headlen(list_skb) > len);
4818
4819 nskb = skb_clone(list_skb, GFP_ATOMIC);
4820 if (unlikely(!nskb))
4821 goto err;
4822
4823 i = 0;
4824 nfrags = skb_shinfo(list_skb)->nr_frags;
4825 frag = skb_shinfo(list_skb)->frags;
4826 frag_skb = list_skb;
4827 pos += skb_headlen(list_skb);
4828
4829 while (pos < offset + len) {
4830 BUG_ON(i >= nfrags);
4831
4832 size = skb_frag_size(frag);
4833 if (pos + size > offset + len)
4834 break;
4835
4836 i++;
4837 pos += size;
4838 frag++;
4839 }
4840
4841 list_skb = list_skb->next;
4842
4843 if (unlikely(pskb_trim(nskb, len))) {
4844 kfree_skb(nskb);
4845 goto err;
4846 }
4847
4848 hsize = skb_end_offset(nskb);
4849 if (skb_cow_head(nskb, doffset + headroom)) {
4850 kfree_skb(nskb);
4851 goto err;
4852 }
4853
4854 nskb->truesize += skb_end_offset(nskb) - hsize;
4855 skb_release_head_state(nskb);
4856 __skb_push(nskb, doffset);
4857 } else {
4858 if (hsize < 0)
4859 hsize = 0;
4860 if (hsize > len || !sg)
4861 hsize = len;
4862
4863 nskb = __alloc_skb(hsize + doffset + headroom,
4864 GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
4865 NUMA_NO_NODE);
4866
4867 if (unlikely(!nskb))
4868 goto err;
4869
4870 skb_reserve(nskb, headroom);
4871 __skb_put(nskb, doffset);
4872 }
4873
4874 if (segs)
4875 tail->next = nskb;
4876 else
4877 segs = nskb;
4878 tail = nskb;
4879
4880 __copy_skb_header(nskb, head_skb);
4881
4882 skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
4883 skb_reset_mac_len(nskb);
4884
4885 skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
4886 nskb->data - tnl_hlen,
4887 doffset + tnl_hlen);
4888
4889 if (nskb->len == len + doffset)
4890 goto perform_csum_check;
4891
4892 if (!sg) {
4893 if (!csum) {
4894 if (!nskb->remcsum_offload)
4895 nskb->ip_summed = CHECKSUM_NONE;
4896 SKB_GSO_CB(nskb)->csum =
4897 skb_copy_and_csum_bits(head_skb, offset,
4898 skb_put(nskb,
4899 len),
4900 len);
4901 SKB_GSO_CB(nskb)->csum_start =
4902 skb_headroom(nskb) + doffset;
4903 } else {
4904 if (skb_copy_bits(head_skb, offset, skb_put(nskb, len), len))
4905 goto err;
4906 }
4907 continue;
4908 }
4909
4910 nskb_frag = skb_shinfo(nskb)->frags;
4911
4912 skb_copy_from_linear_data_offset(head_skb, offset,
4913 skb_put(nskb, hsize), hsize);
4914
4915 skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
4916 SKBFL_SHARED_FRAG;
4917
4918 if (skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
4919 goto err;
4920
4921 while (pos < offset + len) {
4922 if (i >= nfrags) {
4923 if (skb_orphan_frags(list_skb, GFP_ATOMIC) ||
4924 skb_zerocopy_clone(nskb, list_skb,
4925 GFP_ATOMIC))
4926 goto err;
4927
4928 i = 0;
4929 nfrags = skb_shinfo(list_skb)->nr_frags;
4930 frag = skb_shinfo(list_skb)->frags;
4931 frag_skb = list_skb;
4932 if (!skb_headlen(list_skb)) {
4933 BUG_ON(!nfrags);
4934 } else {
4935 BUG_ON(!list_skb->head_frag);
4936
4937 /* to make room for head_frag. */
4938 i--;
4939 frag--;
4940 }
4941
4942 list_skb = list_skb->next;
4943 }
4944
4945 if (unlikely(skb_shinfo(nskb)->nr_frags >=
4946 MAX_SKB_FRAGS)) {
4947 net_warn_ratelimited(
4948 "skb_segment: too many frags: %u %u\n",
4949 pos, mss);
4950 err = -EINVAL;
4951 goto err;
4952 }
4953
4954 *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
4955 __skb_frag_ref(nskb_frag);
4956 size = skb_frag_size(nskb_frag);
4957
4958 if (pos < offset) {
4959 skb_frag_off_add(nskb_frag, offset - pos);
4960 skb_frag_size_sub(nskb_frag, offset - pos);
4961 }
4962
4963 skb_shinfo(nskb)->nr_frags++;
4964
4965 if (pos + size <= offset + len) {
4966 i++;
4967 frag++;
4968 pos += size;
4969 } else {
4970 skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
4971 goto skip_fraglist;
4972 }
4973
4974 nskb_frag++;
4975 }
4976
4977skip_fraglist:
4978 nskb->data_len = len - hsize;
4979 nskb->len += nskb->data_len;
4980 nskb->truesize += nskb->data_len;
4981
4982perform_csum_check:
4983 if (!csum) {
4984 if (skb_has_shared_frag(nskb) &&
4985 __skb_linearize(nskb))
4986 goto err;
4987
4988 if (!nskb->remcsum_offload)
4989 nskb->ip_summed = CHECKSUM_NONE;
4990 SKB_GSO_CB(nskb)->csum =
4991 skb_checksum(nskb, doffset,
4992 nskb->len - doffset, 0);
4993 SKB_GSO_CB(nskb)->csum_start =
4994 skb_headroom(nskb) + doffset;
4995 }
4996 } while ((offset += len) < head_skb->len);
4997
4998 /* Some callers want to get the end of the list.
4999 * Put it in segs->prev to avoid walking the list.
5000 * (see validate_xmit_skb_list() for example)
5001 */
5002 segs->prev = tail;
5003
5004 if (partial_segs) {
5005 struct sk_buff *iter;
5006 int type = skb_shinfo(head_skb)->gso_type;
5007 unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
5008
5009 /* Update type to add partial and then remove dodgy if set */
5010 type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
5011 type &= ~SKB_GSO_DODGY;
5012
5013 /* Update GSO info and prepare to start updating headers on
5014 * our way back down the stack of protocols.
5015 */
5016 for (iter = segs; iter; iter = iter->next) {
5017 skb_shinfo(iter)->gso_size = gso_size;
5018 skb_shinfo(iter)->gso_segs = partial_segs;
5019 skb_shinfo(iter)->gso_type = type;
5020 SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
5021 }
5022
5023 if (tail->len - doffset <= gso_size)
5024 skb_shinfo(tail)->gso_size = 0;
5025 else if (tail != segs)
5026 skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
5027 }
5028
5029 /* Following permits correct backpressure, for protocols
5030 * using skb_set_owner_w().
5031 * Idea is to tranfert ownership from head_skb to last segment.
5032 */
5033 if (head_skb->destructor == sock_wfree) {
5034 swap(tail->truesize, head_skb->truesize);
5035 swap(tail->destructor, head_skb->destructor);
5036 swap(tail->sk, head_skb->sk);
5037 }
5038 return segs;
5039
5040err:
5041 kfree_skb_list(segs);
5042 return ERR_PTR(err);
5043}
5044EXPORT_SYMBOL_GPL(skb_segment);
5045
5046#ifdef CONFIG_SKB_EXTENSIONS
5047#define SKB_EXT_ALIGN_VALUE 8
5048#define SKB_EXT_CHUNKSIZEOF(x) (ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE)
5049
5050static const u8 skb_ext_type_len[] = {
5051#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
5052 [SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info),
5053#endif
5054#ifdef CONFIG_XFRM
5055 [SKB_EXT_SEC_PATH] = SKB_EXT_CHUNKSIZEOF(struct sec_path),
5056#endif
5057#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
5058 [TC_SKB_EXT] = SKB_EXT_CHUNKSIZEOF(struct tc_skb_ext),
5059#endif
5060#if IS_ENABLED(CONFIG_MPTCP)
5061 [SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext),
5062#endif
5063#if IS_ENABLED(CONFIG_MCTP_FLOWS)
5064 [SKB_EXT_MCTP] = SKB_EXT_CHUNKSIZEOF(struct mctp_flow),
5065#endif
5066};
5067
5068static __always_inline unsigned int skb_ext_total_length(void)
5069{
5070 unsigned int l = SKB_EXT_CHUNKSIZEOF(struct skb_ext);
5071 int i;
5072
5073 for (i = 0; i < ARRAY_SIZE(skb_ext_type_len); i++)
5074 l += skb_ext_type_len[i];
5075
5076 return l;
5077}
5078
5079static void skb_extensions_init(void)
5080{
5081 BUILD_BUG_ON(SKB_EXT_NUM >= 8);
5082#if !IS_ENABLED(CONFIG_KCOV_INSTRUMENT_ALL)
5083 BUILD_BUG_ON(skb_ext_total_length() > 255);
5084#endif
5085
5086 skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache",
5087 SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),
5088 0,
5089 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
5090 NULL);
5091}
5092#else
5093static void skb_extensions_init(void) {}
5094#endif
5095
5096/* The SKB kmem_cache slab is critical for network performance. Never
5097 * merge/alias the slab with similar sized objects. This avoids fragmentation
5098 * that hurts performance of kmem_cache_{alloc,free}_bulk APIs.
5099 */
5100#ifndef CONFIG_SLUB_TINY
5101#define FLAG_SKB_NO_MERGE SLAB_NO_MERGE
5102#else /* CONFIG_SLUB_TINY - simple loop in kmem_cache_alloc_bulk */
5103#define FLAG_SKB_NO_MERGE 0
5104#endif
5105
5106void __init skb_init(void)
5107{
5108 net_hotdata.skbuff_cache = kmem_cache_create_usercopy("skbuff_head_cache",
5109 sizeof(struct sk_buff),
5110 0,
5111 SLAB_HWCACHE_ALIGN|SLAB_PANIC|
5112 FLAG_SKB_NO_MERGE,
5113 offsetof(struct sk_buff, cb),
5114 sizeof_field(struct sk_buff, cb),
5115 NULL);
5116 net_hotdata.skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
5117 sizeof(struct sk_buff_fclones),
5118 0,
5119 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
5120 NULL);
5121 /* usercopy should only access first SKB_SMALL_HEAD_HEADROOM bytes.
5122 * struct skb_shared_info is located at the end of skb->head,
5123 * and should not be copied to/from user.
5124 */
5125 net_hotdata.skb_small_head_cache = kmem_cache_create_usercopy("skbuff_small_head",
5126 SKB_SMALL_HEAD_CACHE_SIZE,
5127 0,
5128 SLAB_HWCACHE_ALIGN | SLAB_PANIC,
5129 0,
5130 SKB_SMALL_HEAD_HEADROOM,
5131 NULL);
5132 skb_extensions_init();
5133}
5134
5135static int
5136__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len,
5137 unsigned int recursion_level)
5138{
5139 int start = skb_headlen(skb);
5140 int i, copy = start - offset;
5141 struct sk_buff *frag_iter;
5142 int elt = 0;
5143
5144 if (unlikely(recursion_level >= 24))
5145 return -EMSGSIZE;
5146
5147 if (copy > 0) {
5148 if (copy > len)
5149 copy = len;
5150 sg_set_buf(sg, skb->data + offset, copy);
5151 elt++;
5152 if ((len -= copy) == 0)
5153 return elt;
5154 offset += copy;
5155 }
5156
5157 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
5158 int end;
5159
5160 WARN_ON(start > offset + len);
5161
5162 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
5163 if ((copy = end - offset) > 0) {
5164 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
5165 if (unlikely(elt && sg_is_last(&sg[elt - 1])))
5166 return -EMSGSIZE;
5167
5168 if (copy > len)
5169 copy = len;
5170 sg_set_page(&sg[elt], skb_frag_page(frag), copy,
5171 skb_frag_off(frag) + offset - start);
5172 elt++;
5173 if (!(len -= copy))
5174 return elt;
5175 offset += copy;
5176 }
5177 start = end;
5178 }
5179
5180 skb_walk_frags(skb, frag_iter) {
5181 int end, ret;
5182
5183 WARN_ON(start > offset + len);
5184
5185 end = start + frag_iter->len;
5186 if ((copy = end - offset) > 0) {
5187 if (unlikely(elt && sg_is_last(&sg[elt - 1])))
5188 return -EMSGSIZE;
5189
5190 if (copy > len)
5191 copy = len;
5192 ret = __skb_to_sgvec(frag_iter, sg+elt, offset - start,
5193 copy, recursion_level + 1);
5194 if (unlikely(ret < 0))
5195 return ret;
5196 elt += ret;
5197 if ((len -= copy) == 0)
5198 return elt;
5199 offset += copy;
5200 }
5201 start = end;
5202 }
5203 BUG_ON(len);
5204 return elt;
5205}
5206
5207/**
5208 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
5209 * @skb: Socket buffer containing the buffers to be mapped
5210 * @sg: The scatter-gather list to map into
5211 * @offset: The offset into the buffer's contents to start mapping
5212 * @len: Length of buffer space to be mapped
5213 *
5214 * Fill the specified scatter-gather list with mappings/pointers into a
5215 * region of the buffer space attached to a socket buffer. Returns either
5216 * the number of scatterlist items used, or -EMSGSIZE if the contents
5217 * could not fit.
5218 */
5219int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
5220{
5221 int nsg = __skb_to_sgvec(skb, sg, offset, len, 0);
5222
5223 if (nsg <= 0)
5224 return nsg;
5225
5226 sg_mark_end(&sg[nsg - 1]);
5227
5228 return nsg;
5229}
5230EXPORT_SYMBOL_GPL(skb_to_sgvec);
5231
5232/* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
5233 * sglist without mark the sg which contain last skb data as the end.
5234 * So the caller can mannipulate sg list as will when padding new data after
5235 * the first call without calling sg_unmark_end to expend sg list.
5236 *
5237 * Scenario to use skb_to_sgvec_nomark:
5238 * 1. sg_init_table
5239 * 2. skb_to_sgvec_nomark(payload1)
5240 * 3. skb_to_sgvec_nomark(payload2)
5241 *
5242 * This is equivalent to:
5243 * 1. sg_init_table
5244 * 2. skb_to_sgvec(payload1)
5245 * 3. sg_unmark_end
5246 * 4. skb_to_sgvec(payload2)
5247 *
5248 * When mapping multiple payload conditionally, skb_to_sgvec_nomark
5249 * is more preferable.
5250 */
5251int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
5252 int offset, int len)
5253{
5254 return __skb_to_sgvec(skb, sg, offset, len, 0);
5255}
5256EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
5257
5258
5259
5260/**
5261 * skb_cow_data - Check that a socket buffer's data buffers are writable
5262 * @skb: The socket buffer to check.
5263 * @tailbits: Amount of trailing space to be added
5264 * @trailer: Returned pointer to the skb where the @tailbits space begins
5265 *
5266 * Make sure that the data buffers attached to a socket buffer are
5267 * writable. If they are not, private copies are made of the data buffers
5268 * and the socket buffer is set to use these instead.
5269 *
5270 * If @tailbits is given, make sure that there is space to write @tailbits
5271 * bytes of data beyond current end of socket buffer. @trailer will be
5272 * set to point to the skb in which this space begins.
5273 *
5274 * The number of scatterlist elements required to completely map the
5275 * COW'd and extended socket buffer will be returned.
5276 */
5277int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
5278{
5279 int copyflag;
5280 int elt;
5281 struct sk_buff *skb1, **skb_p;
5282
5283 /* If skb is cloned or its head is paged, reallocate
5284 * head pulling out all the pages (pages are considered not writable
5285 * at the moment even if they are anonymous).
5286 */
5287 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
5288 !__pskb_pull_tail(skb, __skb_pagelen(skb)))
5289 return -ENOMEM;
5290
5291 /* Easy case. Most of packets will go this way. */
5292 if (!skb_has_frag_list(skb)) {
5293 /* A little of trouble, not enough of space for trailer.
5294 * This should not happen, when stack is tuned to generate
5295 * good frames. OK, on miss we reallocate and reserve even more
5296 * space, 128 bytes is fair. */
5297
5298 if (skb_tailroom(skb) < tailbits &&
5299 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
5300 return -ENOMEM;
5301
5302 /* Voila! */
5303 *trailer = skb;
5304 return 1;
5305 }
5306
5307 /* Misery. We are in troubles, going to mincer fragments... */
5308
5309 elt = 1;
5310 skb_p = &skb_shinfo(skb)->frag_list;
5311 copyflag = 0;
5312
5313 while ((skb1 = *skb_p) != NULL) {
5314 int ntail = 0;
5315
5316 /* The fragment is partially pulled by someone,
5317 * this can happen on input. Copy it and everything
5318 * after it. */
5319
5320 if (skb_shared(skb1))
5321 copyflag = 1;
5322
5323 /* If the skb is the last, worry about trailer. */
5324
5325 if (skb1->next == NULL && tailbits) {
5326 if (skb_shinfo(skb1)->nr_frags ||
5327 skb_has_frag_list(skb1) ||
5328 skb_tailroom(skb1) < tailbits)
5329 ntail = tailbits + 128;
5330 }
5331
5332 if (copyflag ||
5333 skb_cloned(skb1) ||
5334 ntail ||
5335 skb_shinfo(skb1)->nr_frags ||
5336 skb_has_frag_list(skb1)) {
5337 struct sk_buff *skb2;
5338
5339 /* Fuck, we are miserable poor guys... */
5340 if (ntail == 0)
5341 skb2 = skb_copy(skb1, GFP_ATOMIC);
5342 else
5343 skb2 = skb_copy_expand(skb1,
5344 skb_headroom(skb1),
5345 ntail,
5346 GFP_ATOMIC);
5347 if (unlikely(skb2 == NULL))
5348 return -ENOMEM;
5349
5350 if (skb1->sk)
5351 skb_set_owner_w(skb2, skb1->sk);
5352
5353 /* Looking around. Are we still alive?
5354 * OK, link new skb, drop old one */
5355
5356 skb2->next = skb1->next;
5357 *skb_p = skb2;
5358 kfree_skb(skb1);
5359 skb1 = skb2;
5360 }
5361 elt++;
5362 *trailer = skb1;
5363 skb_p = &skb1->next;
5364 }
5365
5366 return elt;
5367}
5368EXPORT_SYMBOL_GPL(skb_cow_data);
5369
5370static void sock_rmem_free(struct sk_buff *skb)
5371{
5372 struct sock *sk = skb->sk;
5373
5374 atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
5375}
5376
5377static void skb_set_err_queue(struct sk_buff *skb)
5378{
5379 /* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
5380 * So, it is safe to (mis)use it to mark skbs on the error queue.
5381 */
5382 skb->pkt_type = PACKET_OUTGOING;
5383 BUILD_BUG_ON(PACKET_OUTGOING == 0);
5384}
5385
5386/*
5387 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
5388 */
5389int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
5390{
5391 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
5392 (unsigned int)READ_ONCE(sk->sk_rcvbuf))
5393 return -ENOMEM;
5394
5395 skb_orphan(skb);
5396 skb->sk = sk;
5397 skb->destructor = sock_rmem_free;
5398 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
5399 skb_set_err_queue(skb);
5400
5401 /* before exiting rcu section, make sure dst is refcounted */
5402 skb_dst_force(skb);
5403
5404 skb_queue_tail(&sk->sk_error_queue, skb);
5405 if (!sock_flag(sk, SOCK_DEAD))
5406 sk_error_report(sk);
5407 return 0;
5408}
5409EXPORT_SYMBOL(sock_queue_err_skb);
5410
5411static bool is_icmp_err_skb(const struct sk_buff *skb)
5412{
5413 return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
5414 SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6);
5415}
5416
5417struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
5418{
5419 struct sk_buff_head *q = &sk->sk_error_queue;
5420 struct sk_buff *skb, *skb_next = NULL;
5421 bool icmp_next = false;
5422 unsigned long flags;
5423
5424 if (skb_queue_empty_lockless(q))
5425 return NULL;
5426
5427 spin_lock_irqsave(&q->lock, flags);
5428 skb = __skb_dequeue(q);
5429 if (skb && (skb_next = skb_peek(q))) {
5430 icmp_next = is_icmp_err_skb(skb_next);
5431 if (icmp_next)
5432 sk->sk_err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
5433 }
5434 spin_unlock_irqrestore(&q->lock, flags);
5435
5436 if (is_icmp_err_skb(skb) && !icmp_next)
5437 sk->sk_err = 0;
5438
5439 if (skb_next)
5440 sk_error_report(sk);
5441
5442 return skb;
5443}
5444EXPORT_SYMBOL(sock_dequeue_err_skb);
5445
5446/**
5447 * skb_clone_sk - create clone of skb, and take reference to socket
5448 * @skb: the skb to clone
5449 *
5450 * This function creates a clone of a buffer that holds a reference on
5451 * sk_refcnt. Buffers created via this function are meant to be
5452 * returned using sock_queue_err_skb, or free via kfree_skb.
5453 *
5454 * When passing buffers allocated with this function to sock_queue_err_skb
5455 * it is necessary to wrap the call with sock_hold/sock_put in order to
5456 * prevent the socket from being released prior to being enqueued on
5457 * the sk_error_queue.
5458 */
5459struct sk_buff *skb_clone_sk(struct sk_buff *skb)
5460{
5461 struct sock *sk = skb->sk;
5462 struct sk_buff *clone;
5463
5464 if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
5465 return NULL;
5466
5467 clone = skb_clone(skb, GFP_ATOMIC);
5468 if (!clone) {
5469 sock_put(sk);
5470 return NULL;
5471 }
5472
5473 clone->sk = sk;
5474 clone->destructor = sock_efree;
5475
5476 return clone;
5477}
5478EXPORT_SYMBOL(skb_clone_sk);
5479
5480static void __skb_complete_tx_timestamp(struct sk_buff *skb,
5481 struct sock *sk,
5482 int tstype,
5483 bool opt_stats)
5484{
5485 struct sock_exterr_skb *serr;
5486 int err;
5487
5488 BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));
5489
5490 serr = SKB_EXT_ERR(skb);
5491 memset(serr, 0, sizeof(*serr));
5492 serr->ee.ee_errno = ENOMSG;
5493 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
5494 serr->ee.ee_info = tstype;
5495 serr->opt_stats = opt_stats;
5496 serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0;
5497 if (READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) {
5498 serr->ee.ee_data = skb_shinfo(skb)->tskey;
5499 if (sk_is_tcp(sk))
5500 serr->ee.ee_data -= atomic_read(&sk->sk_tskey);
5501 }
5502
5503 err = sock_queue_err_skb(sk, skb);
5504
5505 if (err)
5506 kfree_skb(skb);
5507}
5508
5509static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
5510{
5511 bool ret;
5512
5513 if (likely(tsonly || READ_ONCE(sock_net(sk)->core.sysctl_tstamp_allow_data)))
5514 return true;
5515
5516 read_lock_bh(&sk->sk_callback_lock);
5517 ret = sk->sk_socket && sk->sk_socket->file &&
5518 file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
5519 read_unlock_bh(&sk->sk_callback_lock);
5520 return ret;
5521}
5522
5523void skb_complete_tx_timestamp(struct sk_buff *skb,
5524 struct skb_shared_hwtstamps *hwtstamps)
5525{
5526 struct sock *sk = skb->sk;
5527
5528 if (!skb_may_tx_timestamp(sk, false))
5529 goto err;
5530
5531 /* Take a reference to prevent skb_orphan() from freeing the socket,
5532 * but only if the socket refcount is not zero.
5533 */
5534 if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
5535 *skb_hwtstamps(skb) = *hwtstamps;
5536 __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
5537 sock_put(sk);
5538 return;
5539 }
5540
5541err:
5542 kfree_skb(skb);
5543}
5544EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
5545
5546void __skb_tstamp_tx(struct sk_buff *orig_skb,
5547 const struct sk_buff *ack_skb,
5548 struct skb_shared_hwtstamps *hwtstamps,
5549 struct sock *sk, int tstype)
5550{
5551 struct sk_buff *skb;
5552 bool tsonly, opt_stats = false;
5553 u32 tsflags;
5554
5555 if (!sk)
5556 return;
5557
5558 tsflags = READ_ONCE(sk->sk_tsflags);
5559 if (!hwtstamps && !(tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
5560 skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
5561 return;
5562
5563 tsonly = tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
5564 if (!skb_may_tx_timestamp(sk, tsonly))
5565 return;
5566
5567 if (tsonly) {
5568#ifdef CONFIG_INET
5569 if ((tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
5570 sk_is_tcp(sk)) {
5571 skb = tcp_get_timestamping_opt_stats(sk, orig_skb,
5572 ack_skb);
5573 opt_stats = true;
5574 } else
5575#endif
5576 skb = alloc_skb(0, GFP_ATOMIC);
5577 } else {
5578 skb = skb_clone(orig_skb, GFP_ATOMIC);
5579
5580 if (skb_orphan_frags_rx(skb, GFP_ATOMIC)) {
5581 kfree_skb(skb);
5582 return;
5583 }
5584 }
5585 if (!skb)
5586 return;
5587
5588 if (tsonly) {
5589 skb_shinfo(skb)->tx_flags |= skb_shinfo(orig_skb)->tx_flags &
5590 SKBTX_ANY_TSTAMP;
5591 skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
5592 }
5593
5594 if (hwtstamps)
5595 *skb_hwtstamps(skb) = *hwtstamps;
5596 else
5597 __net_timestamp(skb);
5598
5599 __skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
5600}
5601EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
5602
5603void skb_tstamp_tx(struct sk_buff *orig_skb,
5604 struct skb_shared_hwtstamps *hwtstamps)
5605{
5606 return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,
5607 SCM_TSTAMP_SND);
5608}
5609EXPORT_SYMBOL_GPL(skb_tstamp_tx);
5610
5611#ifdef CONFIG_WIRELESS
5612void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
5613{
5614 struct sock *sk = skb->sk;
5615 struct sock_exterr_skb *serr;
5616 int err = 1;
5617
5618 skb->wifi_acked_valid = 1;
5619 skb->wifi_acked = acked;
5620
5621 serr = SKB_EXT_ERR(skb);
5622 memset(serr, 0, sizeof(*serr));
5623 serr->ee.ee_errno = ENOMSG;
5624 serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
5625
5626 /* Take a reference to prevent skb_orphan() from freeing the socket,
5627 * but only if the socket refcount is not zero.
5628 */
5629 if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
5630 err = sock_queue_err_skb(sk, skb);
5631 sock_put(sk);
5632 }
5633 if (err)
5634 kfree_skb(skb);
5635}
5636EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
5637#endif /* CONFIG_WIRELESS */
5638
5639/**
5640 * skb_partial_csum_set - set up and verify partial csum values for packet
5641 * @skb: the skb to set
5642 * @start: the number of bytes after skb->data to start checksumming.
5643 * @off: the offset from start to place the checksum.
5644 *
5645 * For untrusted partially-checksummed packets, we need to make sure the values
5646 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
5647 *
5648 * This function checks and sets those values and skb->ip_summed: if this
5649 * returns false you should drop the packet.
5650 */
5651bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
5652{
5653 u32 csum_end = (u32)start + (u32)off + sizeof(__sum16);
5654 u32 csum_start = skb_headroom(skb) + (u32)start;
5655
5656 if (unlikely(csum_start >= U16_MAX || csum_end > skb_headlen(skb))) {
5657 net_warn_ratelimited("bad partial csum: csum=%u/%u headroom=%u headlen=%u\n",
5658 start, off, skb_headroom(skb), skb_headlen(skb));
5659 return false;
5660 }
5661 skb->ip_summed = CHECKSUM_PARTIAL;
5662 skb->csum_start = csum_start;
5663 skb->csum_offset = off;
5664 skb->transport_header = csum_start;
5665 return true;
5666}
5667EXPORT_SYMBOL_GPL(skb_partial_csum_set);
5668
5669static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
5670 unsigned int max)
5671{
5672 if (skb_headlen(skb) >= len)
5673 return 0;
5674
5675 /* If we need to pullup then pullup to the max, so we
5676 * won't need to do it again.
5677 */
5678 if (max > skb->len)
5679 max = skb->len;
5680
5681 if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
5682 return -ENOMEM;
5683
5684 if (skb_headlen(skb) < len)
5685 return -EPROTO;
5686
5687 return 0;
5688}
5689
5690#define MAX_TCP_HDR_LEN (15 * 4)
5691
5692static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
5693 typeof(IPPROTO_IP) proto,
5694 unsigned int off)
5695{
5696 int err;
5697
5698 switch (proto) {
5699 case IPPROTO_TCP:
5700 err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
5701 off + MAX_TCP_HDR_LEN);
5702 if (!err && !skb_partial_csum_set(skb, off,
5703 offsetof(struct tcphdr,
5704 check)))
5705 err = -EPROTO;
5706 return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
5707
5708 case IPPROTO_UDP:
5709 err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
5710 off + sizeof(struct udphdr));
5711 if (!err && !skb_partial_csum_set(skb, off,
5712 offsetof(struct udphdr,
5713 check)))
5714 err = -EPROTO;
5715 return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
5716 }
5717
5718 return ERR_PTR(-EPROTO);
5719}
5720
5721/* This value should be large enough to cover a tagged ethernet header plus
5722 * maximally sized IP and TCP or UDP headers.
5723 */
5724#define MAX_IP_HDR_LEN 128
5725
5726static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
5727{
5728 unsigned int off;
5729 bool fragment;
5730 __sum16 *csum;
5731 int err;
5732
5733 fragment = false;
5734
5735 err = skb_maybe_pull_tail(skb,
5736 sizeof(struct iphdr),
5737 MAX_IP_HDR_LEN);
5738 if (err < 0)
5739 goto out;
5740
5741 if (ip_is_fragment(ip_hdr(skb)))
5742 fragment = true;
5743
5744 off = ip_hdrlen(skb);
5745
5746 err = -EPROTO;
5747
5748 if (fragment)
5749 goto out;
5750
5751 csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
5752 if (IS_ERR(csum))
5753 return PTR_ERR(csum);
5754
5755 if (recalculate)
5756 *csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
5757 ip_hdr(skb)->daddr,
5758 skb->len - off,
5759 ip_hdr(skb)->protocol, 0);
5760 err = 0;
5761
5762out:
5763 return err;
5764}
5765
5766/* This value should be large enough to cover a tagged ethernet header plus
5767 * an IPv6 header, all options, and a maximal TCP or UDP header.
5768 */
5769#define MAX_IPV6_HDR_LEN 256
5770
5771#define OPT_HDR(type, skb, off) \
5772 (type *)(skb_network_header(skb) + (off))
5773
5774static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
5775{
5776 int err;
5777 u8 nexthdr;
5778 unsigned int off;
5779 unsigned int len;
5780 bool fragment;
5781 bool done;
5782 __sum16 *csum;
5783
5784 fragment = false;
5785 done = false;
5786
5787 off = sizeof(struct ipv6hdr);
5788
5789 err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
5790 if (err < 0)
5791 goto out;
5792
5793 nexthdr = ipv6_hdr(skb)->nexthdr;
5794
5795 len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
5796 while (off <= len && !done) {
5797 switch (nexthdr) {
5798 case IPPROTO_DSTOPTS:
5799 case IPPROTO_HOPOPTS:
5800 case IPPROTO_ROUTING: {
5801 struct ipv6_opt_hdr *hp;
5802
5803 err = skb_maybe_pull_tail(skb,
5804 off +
5805 sizeof(struct ipv6_opt_hdr),
5806 MAX_IPV6_HDR_LEN);
5807 if (err < 0)
5808 goto out;
5809
5810 hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
5811 nexthdr = hp->nexthdr;
5812 off += ipv6_optlen(hp);
5813 break;
5814 }
5815 case IPPROTO_AH: {
5816 struct ip_auth_hdr *hp;
5817
5818 err = skb_maybe_pull_tail(skb,
5819 off +
5820 sizeof(struct ip_auth_hdr),
5821 MAX_IPV6_HDR_LEN);
5822 if (err < 0)
5823 goto out;
5824
5825 hp = OPT_HDR(struct ip_auth_hdr, skb, off);
5826 nexthdr = hp->nexthdr;
5827 off += ipv6_authlen(hp);
5828 break;
5829 }
5830 case IPPROTO_FRAGMENT: {
5831 struct frag_hdr *hp;
5832
5833 err = skb_maybe_pull_tail(skb,
5834 off +
5835 sizeof(struct frag_hdr),
5836 MAX_IPV6_HDR_LEN);
5837 if (err < 0)
5838 goto out;
5839
5840 hp = OPT_HDR(struct frag_hdr, skb, off);
5841
5842 if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
5843 fragment = true;
5844
5845 nexthdr = hp->nexthdr;
5846 off += sizeof(struct frag_hdr);
5847 break;
5848 }
5849 default:
5850 done = true;
5851 break;
5852 }
5853 }
5854
5855 err = -EPROTO;
5856
5857 if (!done || fragment)
5858 goto out;
5859
5860 csum = skb_checksum_setup_ip(skb, nexthdr, off);
5861 if (IS_ERR(csum))
5862 return PTR_ERR(csum);
5863
5864 if (recalculate)
5865 *csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
5866 &ipv6_hdr(skb)->daddr,
5867 skb->len - off, nexthdr, 0);
5868 err = 0;
5869
5870out:
5871 return err;
5872}
5873
5874/**
5875 * skb_checksum_setup - set up partial checksum offset
5876 * @skb: the skb to set up
5877 * @recalculate: if true the pseudo-header checksum will be recalculated
5878 */
5879int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
5880{
5881 int err;
5882
5883 switch (skb->protocol) {
5884 case htons(ETH_P_IP):
5885 err = skb_checksum_setup_ipv4(skb, recalculate);
5886 break;
5887
5888 case htons(ETH_P_IPV6):
5889 err = skb_checksum_setup_ipv6(skb, recalculate);
5890 break;
5891
5892 default:
5893 err = -EPROTO;
5894 break;
5895 }
5896
5897 return err;
5898}
5899EXPORT_SYMBOL(skb_checksum_setup);
5900
5901/**
5902 * skb_checksum_maybe_trim - maybe trims the given skb
5903 * @skb: the skb to check
5904 * @transport_len: the data length beyond the network header
5905 *
5906 * Checks whether the given skb has data beyond the given transport length.
5907 * If so, returns a cloned skb trimmed to this transport length.
5908 * Otherwise returns the provided skb. Returns NULL in error cases
5909 * (e.g. transport_len exceeds skb length or out-of-memory).
5910 *
5911 * Caller needs to set the skb transport header and free any returned skb if it
5912 * differs from the provided skb.
5913 */
5914static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
5915 unsigned int transport_len)
5916{
5917 struct sk_buff *skb_chk;
5918 unsigned int len = skb_transport_offset(skb) + transport_len;
5919 int ret;
5920
5921 if (skb->len < len)
5922 return NULL;
5923 else if (skb->len == len)
5924 return skb;
5925
5926 skb_chk = skb_clone(skb, GFP_ATOMIC);
5927 if (!skb_chk)
5928 return NULL;
5929
5930 ret = pskb_trim_rcsum(skb_chk, len);
5931 if (ret) {
5932 kfree_skb(skb_chk);
5933 return NULL;
5934 }
5935
5936 return skb_chk;
5937}
5938
5939/**
5940 * skb_checksum_trimmed - validate checksum of an skb
5941 * @skb: the skb to check
5942 * @transport_len: the data length beyond the network header
5943 * @skb_chkf: checksum function to use
5944 *
5945 * Applies the given checksum function skb_chkf to the provided skb.
5946 * Returns a checked and maybe trimmed skb. Returns NULL on error.
5947 *
5948 * If the skb has data beyond the given transport length, then a
5949 * trimmed & cloned skb is checked and returned.
5950 *
5951 * Caller needs to set the skb transport header and free any returned skb if it
5952 * differs from the provided skb.
5953 */
5954struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
5955 unsigned int transport_len,
5956 __sum16(*skb_chkf)(struct sk_buff *skb))
5957{
5958 struct sk_buff *skb_chk;
5959 unsigned int offset = skb_transport_offset(skb);
5960 __sum16 ret;
5961
5962 skb_chk = skb_checksum_maybe_trim(skb, transport_len);
5963 if (!skb_chk)
5964 goto err;
5965
5966 if (!pskb_may_pull(skb_chk, offset))
5967 goto err;
5968
5969 skb_pull_rcsum(skb_chk, offset);
5970 ret = skb_chkf(skb_chk);
5971 skb_push_rcsum(skb_chk, offset);
5972
5973 if (ret)
5974 goto err;
5975
5976 return skb_chk;
5977
5978err:
5979 if (skb_chk && skb_chk != skb)
5980 kfree_skb(skb_chk);
5981
5982 return NULL;
5983
5984}
5985EXPORT_SYMBOL(skb_checksum_trimmed);
5986
5987void __skb_warn_lro_forwarding(const struct sk_buff *skb)
5988{
5989 net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
5990 skb->dev->name);
5991}
5992EXPORT_SYMBOL(__skb_warn_lro_forwarding);
5993
5994void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
5995{
5996 if (head_stolen) {
5997 skb_release_head_state(skb);
5998 kmem_cache_free(net_hotdata.skbuff_cache, skb);
5999 } else {
6000 __kfree_skb(skb);
6001 }
6002}
6003EXPORT_SYMBOL(kfree_skb_partial);
6004
6005/**
6006 * skb_try_coalesce - try to merge skb to prior one
6007 * @to: prior buffer
6008 * @from: buffer to add
6009 * @fragstolen: pointer to boolean
6010 * @delta_truesize: how much more was allocated than was requested
6011 */
6012bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
6013 bool *fragstolen, int *delta_truesize)
6014{
6015 struct skb_shared_info *to_shinfo, *from_shinfo;
6016 int i, delta, len = from->len;
6017
6018 *fragstolen = false;
6019
6020 if (skb_cloned(to))
6021 return false;
6022
6023 /* In general, avoid mixing page_pool and non-page_pool allocated
6024 * pages within the same SKB. In theory we could take full
6025 * references if @from is cloned and !@to->pp_recycle but its
6026 * tricky (due to potential race with the clone disappearing) and
6027 * rare, so not worth dealing with.
6028 */
6029 if (to->pp_recycle != from->pp_recycle)
6030 return false;
6031
6032 if (skb_frags_readable(from) != skb_frags_readable(to))
6033 return false;
6034
6035 if (len <= skb_tailroom(to) && skb_frags_readable(from)) {
6036 if (len)
6037 BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
6038 *delta_truesize = 0;
6039 return true;
6040 }
6041
6042 to_shinfo = skb_shinfo(to);
6043 from_shinfo = skb_shinfo(from);
6044 if (to_shinfo->frag_list || from_shinfo->frag_list)
6045 return false;
6046 if (skb_zcopy(to) || skb_zcopy(from))
6047 return false;
6048
6049 if (skb_headlen(from) != 0) {
6050 struct page *page;
6051 unsigned int offset;
6052
6053 if (to_shinfo->nr_frags +
6054 from_shinfo->nr_frags >= MAX_SKB_FRAGS)
6055 return false;
6056
6057 if (skb_head_is_locked(from))
6058 return false;
6059
6060 delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
6061
6062 page = virt_to_head_page(from->head);
6063 offset = from->data - (unsigned char *)page_address(page);
6064
6065 skb_fill_page_desc(to, to_shinfo->nr_frags,
6066 page, offset, skb_headlen(from));
6067 *fragstolen = true;
6068 } else {
6069 if (to_shinfo->nr_frags +
6070 from_shinfo->nr_frags > MAX_SKB_FRAGS)
6071 return false;
6072
6073 delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
6074 }
6075
6076 WARN_ON_ONCE(delta < len);
6077
6078 memcpy(to_shinfo->frags + to_shinfo->nr_frags,
6079 from_shinfo->frags,
6080 from_shinfo->nr_frags * sizeof(skb_frag_t));
6081 to_shinfo->nr_frags += from_shinfo->nr_frags;
6082
6083 if (!skb_cloned(from))
6084 from_shinfo->nr_frags = 0;
6085
6086 /* if the skb is not cloned this does nothing
6087 * since we set nr_frags to 0.
6088 */
6089 if (skb_pp_frag_ref(from)) {
6090 for (i = 0; i < from_shinfo->nr_frags; i++)
6091 __skb_frag_ref(&from_shinfo->frags[i]);
6092 }
6093
6094 to->truesize += delta;
6095 to->len += len;
6096 to->data_len += len;
6097
6098 *delta_truesize = delta;
6099 return true;
6100}
6101EXPORT_SYMBOL(skb_try_coalesce);
6102
6103/**
6104 * skb_scrub_packet - scrub an skb
6105 *
6106 * @skb: buffer to clean
6107 * @xnet: packet is crossing netns
6108 *
6109 * skb_scrub_packet can be used after encapsulating or decapsulating a packet
6110 * into/from a tunnel. Some information have to be cleared during these
6111 * operations.
6112 * skb_scrub_packet can also be used to clean a skb before injecting it in
6113 * another namespace (@xnet == true). We have to clear all information in the
6114 * skb that could impact namespace isolation.
6115 */
6116void skb_scrub_packet(struct sk_buff *skb, bool xnet)
6117{
6118 skb->pkt_type = PACKET_HOST;
6119 skb->skb_iif = 0;
6120 skb->ignore_df = 0;
6121 skb_dst_drop(skb);
6122 skb_ext_reset(skb);
6123 nf_reset_ct(skb);
6124 nf_reset_trace(skb);
6125
6126#ifdef CONFIG_NET_SWITCHDEV
6127 skb->offload_fwd_mark = 0;
6128 skb->offload_l3_fwd_mark = 0;
6129#endif
6130 ipvs_reset(skb);
6131
6132 if (!xnet)
6133 return;
6134
6135 skb->mark = 0;
6136 skb_clear_tstamp(skb);
6137}
6138EXPORT_SYMBOL_GPL(skb_scrub_packet);
6139
6140static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
6141{
6142 int mac_len, meta_len;
6143 void *meta;
6144
6145 if (skb_cow(skb, skb_headroom(skb)) < 0) {
6146 kfree_skb(skb);
6147 return NULL;
6148 }
6149
6150 mac_len = skb->data - skb_mac_header(skb);
6151 if (likely(mac_len > VLAN_HLEN + ETH_TLEN)) {
6152 memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
6153 mac_len - VLAN_HLEN - ETH_TLEN);
6154 }
6155
6156 meta_len = skb_metadata_len(skb);
6157 if (meta_len) {
6158 meta = skb_metadata_end(skb) - meta_len;
6159 memmove(meta + VLAN_HLEN, meta, meta_len);
6160 }
6161
6162 skb->mac_header += VLAN_HLEN;
6163 return skb;
6164}
6165
6166struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
6167{
6168 struct vlan_hdr *vhdr;
6169 u16 vlan_tci;
6170
6171 if (unlikely(skb_vlan_tag_present(skb))) {
6172 /* vlan_tci is already set-up so leave this for another time */
6173 return skb;
6174 }
6175
6176 skb = skb_share_check(skb, GFP_ATOMIC);
6177 if (unlikely(!skb))
6178 goto err_free;
6179 /* We may access the two bytes after vlan_hdr in vlan_set_encap_proto(). */
6180 if (unlikely(!pskb_may_pull(skb, VLAN_HLEN + sizeof(unsigned short))))
6181 goto err_free;
6182
6183 vhdr = (struct vlan_hdr *)skb->data;
6184 vlan_tci = ntohs(vhdr->h_vlan_TCI);
6185 __vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
6186
6187 skb_pull_rcsum(skb, VLAN_HLEN);
6188 vlan_set_encap_proto(skb, vhdr);
6189
6190 skb = skb_reorder_vlan_header(skb);
6191 if (unlikely(!skb))
6192 goto err_free;
6193
6194 skb_reset_network_header(skb);
6195 if (!skb_transport_header_was_set(skb))
6196 skb_reset_transport_header(skb);
6197 skb_reset_mac_len(skb);
6198
6199 return skb;
6200
6201err_free:
6202 kfree_skb(skb);
6203 return NULL;
6204}
6205EXPORT_SYMBOL(skb_vlan_untag);
6206
6207int skb_ensure_writable(struct sk_buff *skb, unsigned int write_len)
6208{
6209 if (!pskb_may_pull(skb, write_len))
6210 return -ENOMEM;
6211
6212 if (!skb_frags_readable(skb))
6213 return -EFAULT;
6214
6215 if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
6216 return 0;
6217
6218 return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
6219}
6220EXPORT_SYMBOL(skb_ensure_writable);
6221
6222int skb_ensure_writable_head_tail(struct sk_buff *skb, struct net_device *dev)
6223{
6224 int needed_headroom = dev->needed_headroom;
6225 int needed_tailroom = dev->needed_tailroom;
6226
6227 /* For tail taggers, we need to pad short frames ourselves, to ensure
6228 * that the tail tag does not fail at its role of being at the end of
6229 * the packet, once the conduit interface pads the frame. Account for
6230 * that pad length here, and pad later.
6231 */
6232 if (unlikely(needed_tailroom && skb->len < ETH_ZLEN))
6233 needed_tailroom += ETH_ZLEN - skb->len;
6234 /* skb_headroom() returns unsigned int... */
6235 needed_headroom = max_t(int, needed_headroom - skb_headroom(skb), 0);
6236 needed_tailroom = max_t(int, needed_tailroom - skb_tailroom(skb), 0);
6237
6238 if (likely(!needed_headroom && !needed_tailroom && !skb_cloned(skb)))
6239 /* No reallocation needed, yay! */
6240 return 0;
6241
6242 return pskb_expand_head(skb, needed_headroom, needed_tailroom,
6243 GFP_ATOMIC);
6244}
6245EXPORT_SYMBOL(skb_ensure_writable_head_tail);
6246
6247/* remove VLAN header from packet and update csum accordingly.
6248 * expects a non skb_vlan_tag_present skb with a vlan tag payload
6249 */
6250int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
6251{
6252 int offset = skb->data - skb_mac_header(skb);
6253 int err;
6254
6255 if (WARN_ONCE(offset,
6256 "__skb_vlan_pop got skb with skb->data not at mac header (offset %d)\n",
6257 offset)) {
6258 return -EINVAL;
6259 }
6260
6261 err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
6262 if (unlikely(err))
6263 return err;
6264
6265 skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
6266
6267 vlan_remove_tag(skb, vlan_tci);
6268
6269 skb->mac_header += VLAN_HLEN;
6270
6271 if (skb_network_offset(skb) < ETH_HLEN)
6272 skb_set_network_header(skb, ETH_HLEN);
6273
6274 skb_reset_mac_len(skb);
6275
6276 return err;
6277}
6278EXPORT_SYMBOL(__skb_vlan_pop);
6279
6280/* Pop a vlan tag either from hwaccel or from payload.
6281 * Expects skb->data at mac header.
6282 */
6283int skb_vlan_pop(struct sk_buff *skb)
6284{
6285 u16 vlan_tci;
6286 __be16 vlan_proto;
6287 int err;
6288
6289 if (likely(skb_vlan_tag_present(skb))) {
6290 __vlan_hwaccel_clear_tag(skb);
6291 } else {
6292 if (unlikely(!eth_type_vlan(skb->protocol)))
6293 return 0;
6294
6295 err = __skb_vlan_pop(skb, &vlan_tci);
6296 if (err)
6297 return err;
6298 }
6299 /* move next vlan tag to hw accel tag */
6300 if (likely(!eth_type_vlan(skb->protocol)))
6301 return 0;
6302
6303 vlan_proto = skb->protocol;
6304 err = __skb_vlan_pop(skb, &vlan_tci);
6305 if (unlikely(err))
6306 return err;
6307
6308 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
6309 return 0;
6310}
6311EXPORT_SYMBOL(skb_vlan_pop);
6312
6313/* Push a vlan tag either into hwaccel or into payload (if hwaccel tag present).
6314 * Expects skb->data at mac header.
6315 */
6316int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
6317{
6318 if (skb_vlan_tag_present(skb)) {
6319 int offset = skb->data - skb_mac_header(skb);
6320 int err;
6321
6322 if (WARN_ONCE(offset,
6323 "skb_vlan_push got skb with skb->data not at mac header (offset %d)\n",
6324 offset)) {
6325 return -EINVAL;
6326 }
6327
6328 err = __vlan_insert_tag(skb, skb->vlan_proto,
6329 skb_vlan_tag_get(skb));
6330 if (err)
6331 return err;
6332
6333 skb->protocol = skb->vlan_proto;
6334 skb->network_header -= VLAN_HLEN;
6335
6336 skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
6337 }
6338 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
6339 return 0;
6340}
6341EXPORT_SYMBOL(skb_vlan_push);
6342
6343/**
6344 * skb_eth_pop() - Drop the Ethernet header at the head of a packet
6345 *
6346 * @skb: Socket buffer to modify
6347 *
6348 * Drop the Ethernet header of @skb.
6349 *
6350 * Expects that skb->data points to the mac header and that no VLAN tags are
6351 * present.
6352 *
6353 * Returns 0 on success, -errno otherwise.
6354 */
6355int skb_eth_pop(struct sk_buff *skb)
6356{
6357 if (!pskb_may_pull(skb, ETH_HLEN) || skb_vlan_tagged(skb) ||
6358 skb_network_offset(skb) < ETH_HLEN)
6359 return -EPROTO;
6360
6361 skb_pull_rcsum(skb, ETH_HLEN);
6362 skb_reset_mac_header(skb);
6363 skb_reset_mac_len(skb);
6364
6365 return 0;
6366}
6367EXPORT_SYMBOL(skb_eth_pop);
6368
6369/**
6370 * skb_eth_push() - Add a new Ethernet header at the head of a packet
6371 *
6372 * @skb: Socket buffer to modify
6373 * @dst: Destination MAC address of the new header
6374 * @src: Source MAC address of the new header
6375 *
6376 * Prepend @skb with a new Ethernet header.
6377 *
6378 * Expects that skb->data points to the mac header, which must be empty.
6379 *
6380 * Returns 0 on success, -errno otherwise.
6381 */
6382int skb_eth_push(struct sk_buff *skb, const unsigned char *dst,
6383 const unsigned char *src)
6384{
6385 struct ethhdr *eth;
6386 int err;
6387
6388 if (skb_network_offset(skb) || skb_vlan_tag_present(skb))
6389 return -EPROTO;
6390
6391 err = skb_cow_head(skb, sizeof(*eth));
6392 if (err < 0)
6393 return err;
6394
6395 skb_push(skb, sizeof(*eth));
6396 skb_reset_mac_header(skb);
6397 skb_reset_mac_len(skb);
6398
6399 eth = eth_hdr(skb);
6400 ether_addr_copy(eth->h_dest, dst);
6401 ether_addr_copy(eth->h_source, src);
6402 eth->h_proto = skb->protocol;
6403
6404 skb_postpush_rcsum(skb, eth, sizeof(*eth));
6405
6406 return 0;
6407}
6408EXPORT_SYMBOL(skb_eth_push);
6409
6410/* Update the ethertype of hdr and the skb csum value if required. */
6411static void skb_mod_eth_type(struct sk_buff *skb, struct ethhdr *hdr,
6412 __be16 ethertype)
6413{
6414 if (skb->ip_summed == CHECKSUM_COMPLETE) {
6415 __be16 diff[] = { ~hdr->h_proto, ethertype };
6416
6417 skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
6418 }
6419
6420 hdr->h_proto = ethertype;
6421}
6422
6423/**
6424 * skb_mpls_push() - push a new MPLS header after mac_len bytes from start of
6425 * the packet
6426 *
6427 * @skb: buffer
6428 * @mpls_lse: MPLS label stack entry to push
6429 * @mpls_proto: ethertype of the new MPLS header (expects 0x8847 or 0x8848)
6430 * @mac_len: length of the MAC header
6431 * @ethernet: flag to indicate if the resulting packet after skb_mpls_push is
6432 * ethernet
6433 *
6434 * Expects skb->data at mac header.
6435 *
6436 * Returns 0 on success, -errno otherwise.
6437 */
6438int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
6439 int mac_len, bool ethernet)
6440{
6441 struct mpls_shim_hdr *lse;
6442 int err;
6443
6444 if (unlikely(!eth_p_mpls(mpls_proto)))
6445 return -EINVAL;
6446
6447 /* Networking stack does not allow simultaneous Tunnel and MPLS GSO. */
6448 if (skb->encapsulation)
6449 return -EINVAL;
6450
6451 err = skb_cow_head(skb, MPLS_HLEN);
6452 if (unlikely(err))
6453 return err;
6454
6455 if (!skb->inner_protocol) {
6456 skb_set_inner_network_header(skb, skb_network_offset(skb));
6457 skb_set_inner_protocol(skb, skb->protocol);
6458 }
6459
6460 skb_push(skb, MPLS_HLEN);
6461 memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
6462 mac_len);
6463 skb_reset_mac_header(skb);
6464 skb_set_network_header(skb, mac_len);
6465 skb_reset_mac_len(skb);
6466
6467 lse = mpls_hdr(skb);
6468 lse->label_stack_entry = mpls_lse;
6469 skb_postpush_rcsum(skb, lse, MPLS_HLEN);
6470
6471 if (ethernet && mac_len >= ETH_HLEN)
6472 skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
6473 skb->protocol = mpls_proto;
6474
6475 return 0;
6476}
6477EXPORT_SYMBOL_GPL(skb_mpls_push);
6478
6479/**
6480 * skb_mpls_pop() - pop the outermost MPLS header
6481 *
6482 * @skb: buffer
6483 * @next_proto: ethertype of header after popped MPLS header
6484 * @mac_len: length of the MAC header
6485 * @ethernet: flag to indicate if the packet is ethernet
6486 *
6487 * Expects skb->data at mac header.
6488 *
6489 * Returns 0 on success, -errno otherwise.
6490 */
6491int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
6492 bool ethernet)
6493{
6494 int err;
6495
6496 if (unlikely(!eth_p_mpls(skb->protocol)))
6497 return 0;
6498
6499 err = skb_ensure_writable(skb, mac_len + MPLS_HLEN);
6500 if (unlikely(err))
6501 return err;
6502
6503 skb_postpull_rcsum(skb, mpls_hdr(skb), MPLS_HLEN);
6504 memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
6505 mac_len);
6506
6507 __skb_pull(skb, MPLS_HLEN);
6508 skb_reset_mac_header(skb);
6509 skb_set_network_header(skb, mac_len);
6510
6511 if (ethernet && mac_len >= ETH_HLEN) {
6512 struct ethhdr *hdr;
6513
6514 /* use mpls_hdr() to get ethertype to account for VLANs. */
6515 hdr = (struct ethhdr *)((void *)mpls_hdr(skb) - ETH_HLEN);
6516 skb_mod_eth_type(skb, hdr, next_proto);
6517 }
6518 skb->protocol = next_proto;
6519
6520 return 0;
6521}
6522EXPORT_SYMBOL_GPL(skb_mpls_pop);
6523
6524/**
6525 * skb_mpls_update_lse() - modify outermost MPLS header and update csum
6526 *
6527 * @skb: buffer
6528 * @mpls_lse: new MPLS label stack entry to update to
6529 *
6530 * Expects skb->data at mac header.
6531 *
6532 * Returns 0 on success, -errno otherwise.
6533 */
6534int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse)
6535{
6536 int err;
6537
6538 if (unlikely(!eth_p_mpls(skb->protocol)))
6539 return -EINVAL;
6540
6541 err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
6542 if (unlikely(err))
6543 return err;
6544
6545 if (skb->ip_summed == CHECKSUM_COMPLETE) {
6546 __be32 diff[] = { ~mpls_hdr(skb)->label_stack_entry, mpls_lse };
6547
6548 skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
6549 }
6550
6551 mpls_hdr(skb)->label_stack_entry = mpls_lse;
6552
6553 return 0;
6554}
6555EXPORT_SYMBOL_GPL(skb_mpls_update_lse);
6556
6557/**
6558 * skb_mpls_dec_ttl() - decrement the TTL of the outermost MPLS header
6559 *
6560 * @skb: buffer
6561 *
6562 * Expects skb->data at mac header.
6563 *
6564 * Returns 0 on success, -errno otherwise.
6565 */
6566int skb_mpls_dec_ttl(struct sk_buff *skb)
6567{
6568 u32 lse;
6569 u8 ttl;
6570
6571 if (unlikely(!eth_p_mpls(skb->protocol)))
6572 return -EINVAL;
6573
6574 if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN))
6575 return -ENOMEM;
6576
6577 lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry);
6578 ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
6579 if (!--ttl)
6580 return -EINVAL;
6581
6582 lse &= ~MPLS_LS_TTL_MASK;
6583 lse |= ttl << MPLS_LS_TTL_SHIFT;
6584
6585 return skb_mpls_update_lse(skb, cpu_to_be32(lse));
6586}
6587EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl);
6588
6589/**
6590 * alloc_skb_with_frags - allocate skb with page frags
6591 *
6592 * @header_len: size of linear part
6593 * @data_len: needed length in frags
6594 * @order: max page order desired.
6595 * @errcode: pointer to error code if any
6596 * @gfp_mask: allocation mask
6597 *
6598 * This can be used to allocate a paged skb, given a maximal order for frags.
6599 */
6600struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
6601 unsigned long data_len,
6602 int order,
6603 int *errcode,
6604 gfp_t gfp_mask)
6605{
6606 unsigned long chunk;
6607 struct sk_buff *skb;
6608 struct page *page;
6609 int nr_frags = 0;
6610
6611 *errcode = -EMSGSIZE;
6612 if (unlikely(data_len > MAX_SKB_FRAGS * (PAGE_SIZE << order)))
6613 return NULL;
6614
6615 *errcode = -ENOBUFS;
6616 skb = alloc_skb(header_len, gfp_mask);
6617 if (!skb)
6618 return NULL;
6619
6620 while (data_len) {
6621 if (nr_frags == MAX_SKB_FRAGS - 1)
6622 goto failure;
6623 while (order && PAGE_ALIGN(data_len) < (PAGE_SIZE << order))
6624 order--;
6625
6626 if (order) {
6627 page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
6628 __GFP_COMP |
6629 __GFP_NOWARN,
6630 order);
6631 if (!page) {
6632 order--;
6633 continue;
6634 }
6635 } else {
6636 page = alloc_page(gfp_mask);
6637 if (!page)
6638 goto failure;
6639 }
6640 chunk = min_t(unsigned long, data_len,
6641 PAGE_SIZE << order);
6642 skb_fill_page_desc(skb, nr_frags, page, 0, chunk);
6643 nr_frags++;
6644 skb->truesize += (PAGE_SIZE << order);
6645 data_len -= chunk;
6646 }
6647 return skb;
6648
6649failure:
6650 kfree_skb(skb);
6651 return NULL;
6652}
6653EXPORT_SYMBOL(alloc_skb_with_frags);
6654
6655/* carve out the first off bytes from skb when off < headlen */
6656static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
6657 const int headlen, gfp_t gfp_mask)
6658{
6659 int i;
6660 unsigned int size = skb_end_offset(skb);
6661 int new_hlen = headlen - off;
6662 u8 *data;
6663
6664 if (skb_pfmemalloc(skb))
6665 gfp_mask |= __GFP_MEMALLOC;
6666
6667 data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
6668 if (!data)
6669 return -ENOMEM;
6670 size = SKB_WITH_OVERHEAD(size);
6671
6672 /* Copy real data, and all frags */
6673 skb_copy_from_linear_data_offset(skb, off, data, new_hlen);
6674 skb->len -= off;
6675
6676 memcpy((struct skb_shared_info *)(data + size),
6677 skb_shinfo(skb),
6678 offsetof(struct skb_shared_info,
6679 frags[skb_shinfo(skb)->nr_frags]));
6680 if (skb_cloned(skb)) {
6681 /* drop the old head gracefully */
6682 if (skb_orphan_frags(skb, gfp_mask)) {
6683 skb_kfree_head(data, size);
6684 return -ENOMEM;
6685 }
6686 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
6687 skb_frag_ref(skb, i);
6688 if (skb_has_frag_list(skb))
6689 skb_clone_fraglist(skb);
6690 skb_release_data(skb, SKB_CONSUMED);
6691 } else {
6692 /* we can reuse existing recount- all we did was
6693 * relocate values
6694 */
6695 skb_free_head(skb);
6696 }
6697
6698 skb->head = data;
6699 skb->data = data;
6700 skb->head_frag = 0;
6701 skb_set_end_offset(skb, size);
6702 skb_set_tail_pointer(skb, skb_headlen(skb));
6703 skb_headers_offset_update(skb, 0);
6704 skb->cloned = 0;
6705 skb->hdr_len = 0;
6706 skb->nohdr = 0;
6707 atomic_set(&skb_shinfo(skb)->dataref, 1);
6708
6709 return 0;
6710}
6711
6712static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
6713
6714/* carve out the first eat bytes from skb's frag_list. May recurse into
6715 * pskb_carve()
6716 */
6717static int pskb_carve_frag_list(struct sk_buff *skb,
6718 struct skb_shared_info *shinfo, int eat,
6719 gfp_t gfp_mask)
6720{
6721 struct sk_buff *list = shinfo->frag_list;
6722 struct sk_buff *clone = NULL;
6723 struct sk_buff *insp = NULL;
6724
6725 do {
6726 if (!list) {
6727 pr_err("Not enough bytes to eat. Want %d\n", eat);
6728 return -EFAULT;
6729 }
6730 if (list->len <= eat) {
6731 /* Eaten as whole. */
6732 eat -= list->len;
6733 list = list->next;
6734 insp = list;
6735 } else {
6736 /* Eaten partially. */
6737 if (skb_shared(list)) {
6738 clone = skb_clone(list, gfp_mask);
6739 if (!clone)
6740 return -ENOMEM;
6741 insp = list->next;
6742 list = clone;
6743 } else {
6744 /* This may be pulled without problems. */
6745 insp = list;
6746 }
6747 if (pskb_carve(list, eat, gfp_mask) < 0) {
6748 kfree_skb(clone);
6749 return -ENOMEM;
6750 }
6751 break;
6752 }
6753 } while (eat);
6754
6755 /* Free pulled out fragments. */
6756 while ((list = shinfo->frag_list) != insp) {
6757 shinfo->frag_list = list->next;
6758 consume_skb(list);
6759 }
6760 /* And insert new clone at head. */
6761 if (clone) {
6762 clone->next = list;
6763 shinfo->frag_list = clone;
6764 }
6765 return 0;
6766}
6767
6768/* carve off first len bytes from skb. Split line (off) is in the
6769 * non-linear part of skb
6770 */
6771static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
6772 int pos, gfp_t gfp_mask)
6773{
6774 int i, k = 0;
6775 unsigned int size = skb_end_offset(skb);
6776 u8 *data;
6777 const int nfrags = skb_shinfo(skb)->nr_frags;
6778 struct skb_shared_info *shinfo;
6779
6780 if (skb_pfmemalloc(skb))
6781 gfp_mask |= __GFP_MEMALLOC;
6782
6783 data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
6784 if (!data)
6785 return -ENOMEM;
6786 size = SKB_WITH_OVERHEAD(size);
6787
6788 memcpy((struct skb_shared_info *)(data + size),
6789 skb_shinfo(skb), offsetof(struct skb_shared_info, frags[0]));
6790 if (skb_orphan_frags(skb, gfp_mask)) {
6791 skb_kfree_head(data, size);
6792 return -ENOMEM;
6793 }
6794 shinfo = (struct skb_shared_info *)(data + size);
6795 for (i = 0; i < nfrags; i++) {
6796 int fsize = skb_frag_size(&skb_shinfo(skb)->frags[i]);
6797
6798 if (pos + fsize > off) {
6799 shinfo->frags[k] = skb_shinfo(skb)->frags[i];
6800
6801 if (pos < off) {
6802 /* Split frag.
6803 * We have two variants in this case:
6804 * 1. Move all the frag to the second
6805 * part, if it is possible. F.e.
6806 * this approach is mandatory for TUX,
6807 * where splitting is expensive.
6808 * 2. Split is accurately. We make this.
6809 */
6810 skb_frag_off_add(&shinfo->frags[0], off - pos);
6811 skb_frag_size_sub(&shinfo->frags[0], off - pos);
6812 }
6813 skb_frag_ref(skb, i);
6814 k++;
6815 }
6816 pos += fsize;
6817 }
6818 shinfo->nr_frags = k;
6819 if (skb_has_frag_list(skb))
6820 skb_clone_fraglist(skb);
6821
6822 /* split line is in frag list */
6823 if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
6824 /* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
6825 if (skb_has_frag_list(skb))
6826 kfree_skb_list(skb_shinfo(skb)->frag_list);
6827 skb_kfree_head(data, size);
6828 return -ENOMEM;
6829 }
6830 skb_release_data(skb, SKB_CONSUMED);
6831
6832 skb->head = data;
6833 skb->head_frag = 0;
6834 skb->data = data;
6835 skb_set_end_offset(skb, size);
6836 skb_reset_tail_pointer(skb);
6837 skb_headers_offset_update(skb, 0);
6838 skb->cloned = 0;
6839 skb->hdr_len = 0;
6840 skb->nohdr = 0;
6841 skb->len -= off;
6842 skb->data_len = skb->len;
6843 atomic_set(&skb_shinfo(skb)->dataref, 1);
6844 return 0;
6845}
6846
6847/* remove len bytes from the beginning of the skb */
6848static int pskb_carve(struct sk_buff *skb, const u32 len, gfp_t gfp)
6849{
6850 int headlen = skb_headlen(skb);
6851
6852 if (len < headlen)
6853 return pskb_carve_inside_header(skb, len, headlen, gfp);
6854 else
6855 return pskb_carve_inside_nonlinear(skb, len, headlen, gfp);
6856}
6857
6858/* Extract to_copy bytes starting at off from skb, and return this in
6859 * a new skb
6860 */
6861struct sk_buff *pskb_extract(struct sk_buff *skb, int off,
6862 int to_copy, gfp_t gfp)
6863{
6864 struct sk_buff *clone = skb_clone(skb, gfp);
6865
6866 if (!clone)
6867 return NULL;
6868
6869 if (pskb_carve(clone, off, gfp) < 0 ||
6870 pskb_trim(clone, to_copy)) {
6871 kfree_skb(clone);
6872 return NULL;
6873 }
6874 return clone;
6875}
6876EXPORT_SYMBOL(pskb_extract);
6877
6878/**
6879 * skb_condense - try to get rid of fragments/frag_list if possible
6880 * @skb: buffer
6881 *
6882 * Can be used to save memory before skb is added to a busy queue.
6883 * If packet has bytes in frags and enough tail room in skb->head,
6884 * pull all of them, so that we can free the frags right now and adjust
6885 * truesize.
6886 * Notes:
6887 * We do not reallocate skb->head thus can not fail.
6888 * Caller must re-evaluate skb->truesize if needed.
6889 */
6890void skb_condense(struct sk_buff *skb)
6891{
6892 if (skb->data_len) {
6893 if (skb->data_len > skb->end - skb->tail ||
6894 skb_cloned(skb) || !skb_frags_readable(skb))
6895 return;
6896
6897 /* Nice, we can free page frag(s) right now */
6898 __pskb_pull_tail(skb, skb->data_len);
6899 }
6900 /* At this point, skb->truesize might be over estimated,
6901 * because skb had a fragment, and fragments do not tell
6902 * their truesize.
6903 * When we pulled its content into skb->head, fragment
6904 * was freed, but __pskb_pull_tail() could not possibly
6905 * adjust skb->truesize, not knowing the frag truesize.
6906 */
6907 skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
6908}
6909EXPORT_SYMBOL(skb_condense);
6910
6911#ifdef CONFIG_SKB_EXTENSIONS
6912static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id)
6913{
6914 return (void *)ext + (ext->offset[id] * SKB_EXT_ALIGN_VALUE);
6915}
6916
6917/**
6918 * __skb_ext_alloc - allocate a new skb extensions storage
6919 *
6920 * @flags: See kmalloc().
6921 *
6922 * Returns the newly allocated pointer. The pointer can later attached to a
6923 * skb via __skb_ext_set().
6924 * Note: caller must handle the skb_ext as an opaque data.
6925 */
6926struct skb_ext *__skb_ext_alloc(gfp_t flags)
6927{
6928 struct skb_ext *new = kmem_cache_alloc(skbuff_ext_cache, flags);
6929
6930 if (new) {
6931 memset(new->offset, 0, sizeof(new->offset));
6932 refcount_set(&new->refcnt, 1);
6933 }
6934
6935 return new;
6936}
6937
6938static struct skb_ext *skb_ext_maybe_cow(struct skb_ext *old,
6939 unsigned int old_active)
6940{
6941 struct skb_ext *new;
6942
6943 if (refcount_read(&old->refcnt) == 1)
6944 return old;
6945
6946 new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC);
6947 if (!new)
6948 return NULL;
6949
6950 memcpy(new, old, old->chunks * SKB_EXT_ALIGN_VALUE);
6951 refcount_set(&new->refcnt, 1);
6952
6953#ifdef CONFIG_XFRM
6954 if (old_active & (1 << SKB_EXT_SEC_PATH)) {
6955 struct sec_path *sp = skb_ext_get_ptr(old, SKB_EXT_SEC_PATH);
6956 unsigned int i;
6957
6958 for (i = 0; i < sp->len; i++)
6959 xfrm_state_hold(sp->xvec[i]);
6960 }
6961#endif
6962#ifdef CONFIG_MCTP_FLOWS
6963 if (old_active & (1 << SKB_EXT_MCTP)) {
6964 struct mctp_flow *flow = skb_ext_get_ptr(old, SKB_EXT_MCTP);
6965
6966 if (flow->key)
6967 refcount_inc(&flow->key->refs);
6968 }
6969#endif
6970 __skb_ext_put(old);
6971 return new;
6972}
6973
6974/**
6975 * __skb_ext_set - attach the specified extension storage to this skb
6976 * @skb: buffer
6977 * @id: extension id
6978 * @ext: extension storage previously allocated via __skb_ext_alloc()
6979 *
6980 * Existing extensions, if any, are cleared.
6981 *
6982 * Returns the pointer to the extension.
6983 */
6984void *__skb_ext_set(struct sk_buff *skb, enum skb_ext_id id,
6985 struct skb_ext *ext)
6986{
6987 unsigned int newlen, newoff = SKB_EXT_CHUNKSIZEOF(*ext);
6988
6989 skb_ext_put(skb);
6990 newlen = newoff + skb_ext_type_len[id];
6991 ext->chunks = newlen;
6992 ext->offset[id] = newoff;
6993 skb->extensions = ext;
6994 skb->active_extensions = 1 << id;
6995 return skb_ext_get_ptr(ext, id);
6996}
6997
6998/**
6999 * skb_ext_add - allocate space for given extension, COW if needed
7000 * @skb: buffer
7001 * @id: extension to allocate space for
7002 *
7003 * Allocates enough space for the given extension.
7004 * If the extension is already present, a pointer to that extension
7005 * is returned.
7006 *
7007 * If the skb was cloned, COW applies and the returned memory can be
7008 * modified without changing the extension space of clones buffers.
7009 *
7010 * Returns pointer to the extension or NULL on allocation failure.
7011 */
7012void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id)
7013{
7014 struct skb_ext *new, *old = NULL;
7015 unsigned int newlen, newoff;
7016
7017 if (skb->active_extensions) {
7018 old = skb->extensions;
7019
7020 new = skb_ext_maybe_cow(old, skb->active_extensions);
7021 if (!new)
7022 return NULL;
7023
7024 if (__skb_ext_exist(new, id))
7025 goto set_active;
7026
7027 newoff = new->chunks;
7028 } else {
7029 newoff = SKB_EXT_CHUNKSIZEOF(*new);
7030
7031 new = __skb_ext_alloc(GFP_ATOMIC);
7032 if (!new)
7033 return NULL;
7034 }
7035
7036 newlen = newoff + skb_ext_type_len[id];
7037 new->chunks = newlen;
7038 new->offset[id] = newoff;
7039set_active:
7040 skb->slow_gro = 1;
7041 skb->extensions = new;
7042 skb->active_extensions |= 1 << id;
7043 return skb_ext_get_ptr(new, id);
7044}
7045EXPORT_SYMBOL(skb_ext_add);
7046
7047#ifdef CONFIG_XFRM
7048static void skb_ext_put_sp(struct sec_path *sp)
7049{
7050 unsigned int i;
7051
7052 for (i = 0; i < sp->len; i++)
7053 xfrm_state_put(sp->xvec[i]);
7054}
7055#endif
7056
7057#ifdef CONFIG_MCTP_FLOWS
7058static void skb_ext_put_mctp(struct mctp_flow *flow)
7059{
7060 if (flow->key)
7061 mctp_key_unref(flow->key);
7062}
7063#endif
7064
7065void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
7066{
7067 struct skb_ext *ext = skb->extensions;
7068
7069 skb->active_extensions &= ~(1 << id);
7070 if (skb->active_extensions == 0) {
7071 skb->extensions = NULL;
7072 __skb_ext_put(ext);
7073#ifdef CONFIG_XFRM
7074 } else if (id == SKB_EXT_SEC_PATH &&
7075 refcount_read(&ext->refcnt) == 1) {
7076 struct sec_path *sp = skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH);
7077
7078 skb_ext_put_sp(sp);
7079 sp->len = 0;
7080#endif
7081 }
7082}
7083EXPORT_SYMBOL(__skb_ext_del);
7084
7085void __skb_ext_put(struct skb_ext *ext)
7086{
7087 /* If this is last clone, nothing can increment
7088 * it after check passes. Avoids one atomic op.
7089 */
7090 if (refcount_read(&ext->refcnt) == 1)
7091 goto free_now;
7092
7093 if (!refcount_dec_and_test(&ext->refcnt))
7094 return;
7095free_now:
7096#ifdef CONFIG_XFRM
7097 if (__skb_ext_exist(ext, SKB_EXT_SEC_PATH))
7098 skb_ext_put_sp(skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH));
7099#endif
7100#ifdef CONFIG_MCTP_FLOWS
7101 if (__skb_ext_exist(ext, SKB_EXT_MCTP))
7102 skb_ext_put_mctp(skb_ext_get_ptr(ext, SKB_EXT_MCTP));
7103#endif
7104
7105 kmem_cache_free(skbuff_ext_cache, ext);
7106}
7107EXPORT_SYMBOL(__skb_ext_put);
7108#endif /* CONFIG_SKB_EXTENSIONS */
7109
7110static void kfree_skb_napi_cache(struct sk_buff *skb)
7111{
7112 /* if SKB is a clone, don't handle this case */
7113 if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
7114 __kfree_skb(skb);
7115 return;
7116 }
7117
7118 local_bh_disable();
7119 __napi_kfree_skb(skb, SKB_CONSUMED);
7120 local_bh_enable();
7121}
7122
7123/**
7124 * skb_attempt_defer_free - queue skb for remote freeing
7125 * @skb: buffer
7126 *
7127 * Put @skb in a per-cpu list, using the cpu which
7128 * allocated the skb/pages to reduce false sharing
7129 * and memory zone spinlock contention.
7130 */
7131void skb_attempt_defer_free(struct sk_buff *skb)
7132{
7133 int cpu = skb->alloc_cpu;
7134 struct softnet_data *sd;
7135 unsigned int defer_max;
7136 bool kick;
7137
7138 if (cpu == raw_smp_processor_id() ||
7139 WARN_ON_ONCE(cpu >= nr_cpu_ids) ||
7140 !cpu_online(cpu)) {
7141nodefer: kfree_skb_napi_cache(skb);
7142 return;
7143 }
7144
7145 DEBUG_NET_WARN_ON_ONCE(skb_dst(skb));
7146 DEBUG_NET_WARN_ON_ONCE(skb->destructor);
7147
7148 sd = &per_cpu(softnet_data, cpu);
7149 defer_max = READ_ONCE(net_hotdata.sysctl_skb_defer_max);
7150 if (READ_ONCE(sd->defer_count) >= defer_max)
7151 goto nodefer;
7152
7153 spin_lock_bh(&sd->defer_lock);
7154 /* Send an IPI every time queue reaches half capacity. */
7155 kick = sd->defer_count == (defer_max >> 1);
7156 /* Paired with the READ_ONCE() few lines above */
7157 WRITE_ONCE(sd->defer_count, sd->defer_count + 1);
7158
7159 skb->next = sd->defer_list;
7160 /* Paired with READ_ONCE() in skb_defer_free_flush() */
7161 WRITE_ONCE(sd->defer_list, skb);
7162 spin_unlock_bh(&sd->defer_lock);
7163
7164 /* Make sure to trigger NET_RX_SOFTIRQ on the remote CPU
7165 * if we are unlucky enough (this seems very unlikely).
7166 */
7167 if (unlikely(kick))
7168 kick_defer_list_purge(sd, cpu);
7169}
7170
7171static void skb_splice_csum_page(struct sk_buff *skb, struct page *page,
7172 size_t offset, size_t len)
7173{
7174 const char *kaddr;
7175 __wsum csum;
7176
7177 kaddr = kmap_local_page(page);
7178 csum = csum_partial(kaddr + offset, len, 0);
7179 kunmap_local(kaddr);
7180 skb->csum = csum_block_add(skb->csum, csum, skb->len);
7181}
7182
7183/**
7184 * skb_splice_from_iter - Splice (or copy) pages to skbuff
7185 * @skb: The buffer to add pages to
7186 * @iter: Iterator representing the pages to be added
7187 * @maxsize: Maximum amount of pages to be added
7188 * @gfp: Allocation flags
7189 *
7190 * This is a common helper function for supporting MSG_SPLICE_PAGES. It
7191 * extracts pages from an iterator and adds them to the socket buffer if
7192 * possible, copying them to fragments if not possible (such as if they're slab
7193 * pages).
7194 *
7195 * Returns the amount of data spliced/copied or -EMSGSIZE if there's
7196 * insufficient space in the buffer to transfer anything.
7197 */
7198ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter,
7199 ssize_t maxsize, gfp_t gfp)
7200{
7201 size_t frag_limit = READ_ONCE(net_hotdata.sysctl_max_skb_frags);
7202 struct page *pages[8], **ppages = pages;
7203 ssize_t spliced = 0, ret = 0;
7204 unsigned int i;
7205
7206 while (iter->count > 0) {
7207 ssize_t space, nr, len;
7208 size_t off;
7209
7210 ret = -EMSGSIZE;
7211 space = frag_limit - skb_shinfo(skb)->nr_frags;
7212 if (space < 0)
7213 break;
7214
7215 /* We might be able to coalesce without increasing nr_frags */
7216 nr = clamp_t(size_t, space, 1, ARRAY_SIZE(pages));
7217
7218 len = iov_iter_extract_pages(iter, &ppages, maxsize, nr, 0, &off);
7219 if (len <= 0) {
7220 ret = len ?: -EIO;
7221 break;
7222 }
7223
7224 i = 0;
7225 do {
7226 struct page *page = pages[i++];
7227 size_t part = min_t(size_t, PAGE_SIZE - off, len);
7228
7229 ret = -EIO;
7230 if (WARN_ON_ONCE(!sendpage_ok(page)))
7231 goto out;
7232
7233 ret = skb_append_pagefrags(skb, page, off, part,
7234 frag_limit);
7235 if (ret < 0) {
7236 iov_iter_revert(iter, len);
7237 goto out;
7238 }
7239
7240 if (skb->ip_summed == CHECKSUM_NONE)
7241 skb_splice_csum_page(skb, page, off, part);
7242
7243 off = 0;
7244 spliced += part;
7245 maxsize -= part;
7246 len -= part;
7247 } while (len > 0);
7248
7249 if (maxsize <= 0)
7250 break;
7251 }
7252
7253out:
7254 skb_len_add(skb, spliced);
7255 return spliced ?: ret;
7256}
7257EXPORT_SYMBOL(skb_splice_from_iter);
7258
7259static __always_inline
7260size_t memcpy_from_iter_csum(void *iter_from, size_t progress,
7261 size_t len, void *to, void *priv2)
7262{
7263 __wsum *csum = priv2;
7264 __wsum next = csum_partial_copy_nocheck(iter_from, to + progress, len);
7265
7266 *csum = csum_block_add(*csum, next, progress);
7267 return 0;
7268}
7269
7270static __always_inline
7271size_t copy_from_user_iter_csum(void __user *iter_from, size_t progress,
7272 size_t len, void *to, void *priv2)
7273{
7274 __wsum next, *csum = priv2;
7275
7276 next = csum_and_copy_from_user(iter_from, to + progress, len);
7277 *csum = csum_block_add(*csum, next, progress);
7278 return next ? 0 : len;
7279}
7280
7281bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
7282 __wsum *csum, struct iov_iter *i)
7283{
7284 size_t copied;
7285
7286 if (WARN_ON_ONCE(!i->data_source))
7287 return false;
7288 copied = iterate_and_advance2(i, bytes, addr, csum,
7289 copy_from_user_iter_csum,
7290 memcpy_from_iter_csum);
7291 if (likely(copied == bytes))
7292 return true;
7293 iov_iter_revert(i, copied);
7294 return false;
7295}
7296EXPORT_SYMBOL(csum_and_copy_from_iter_full);