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