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1/*
2 * Routines having to do with the 'struct sk_buff' memory handlers.
3 *
4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
5 * Florian La Roche <rzsfl@rz.uni-sb.de>
6 *
7 * Fixes:
8 * Alan Cox : Fixed the worst of the load
9 * balancer bugs.
10 * Dave Platt : Interrupt stacking fix.
11 * Richard Kooijman : Timestamp fixes.
12 * Alan Cox : Changed buffer format.
13 * Alan Cox : destructor hook for AF_UNIX etc.
14 * Linus Torvalds : Better skb_clone.
15 * Alan Cox : Added skb_copy.
16 * Alan Cox : Added all the changed routines Linus
17 * only put in the headers
18 * Ray VanTassle : Fixed --skb->lock in free
19 * Alan Cox : skb_copy copy arp field
20 * Andi Kleen : slabified it.
21 * Robert Olsson : Removed skb_head_pool
22 *
23 * NOTE:
24 * The __skb_ routines should be called with interrupts
25 * disabled, or you better be *real* sure that the operation is atomic
26 * with respect to whatever list is being frobbed (e.g. via lock_sock()
27 * or via disabling bottom half handlers, etc).
28 *
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
33 */
34
35/*
36 * The functions in this file will not compile correctly with gcc 2.4.x
37 */
38
39#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
40
41#include <linux/module.h>
42#include <linux/types.h>
43#include <linux/kernel.h>
44#include <linux/kmemcheck.h>
45#include <linux/mm.h>
46#include <linux/interrupt.h>
47#include <linux/in.h>
48#include <linux/inet.h>
49#include <linux/slab.h>
50#include <linux/netdevice.h>
51#ifdef CONFIG_NET_CLS_ACT
52#include <net/pkt_sched.h>
53#endif
54#include <linux/string.h>
55#include <linux/skbuff.h>
56#include <linux/splice.h>
57#include <linux/cache.h>
58#include <linux/rtnetlink.h>
59#include <linux/init.h>
60#include <linux/scatterlist.h>
61#include <linux/errqueue.h>
62#include <linux/prefetch.h>
63
64#include <net/protocol.h>
65#include <net/dst.h>
66#include <net/sock.h>
67#include <net/checksum.h>
68#include <net/xfrm.h>
69
70#include <asm/uaccess.h>
71#include <trace/events/skb.h>
72#include <linux/highmem.h>
73
74struct 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 pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n",
124 __func__, here, skb->len, sz, skb->head, skb->data,
125 (unsigned long)skb->tail, (unsigned long)skb->end,
126 skb->dev ? skb->dev->name : "<NULL>");
127 BUG();
128}
129
130/**
131 * skb_under_panic - private function
132 * @skb: buffer
133 * @sz: size
134 * @here: address
135 *
136 * Out of line support code for skb_push(). Not user callable.
137 */
138
139static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
140{
141 pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n",
142 __func__, here, skb->len, sz, skb->head, skb->data,
143 (unsigned long)skb->tail, (unsigned long)skb->end,
144 skb->dev ? skb->dev->name : "<NULL>");
145 BUG();
146}
147
148/* Allocate a new skbuff. We do this ourselves so we can fill in a few
149 * 'private' fields and also do memory statistics to find all the
150 * [BEEP] leaks.
151 *
152 */
153
154/**
155 * __alloc_skb - allocate a network buffer
156 * @size: size to allocate
157 * @gfp_mask: allocation mask
158 * @fclone: allocate from fclone cache instead of head cache
159 * and allocate a cloned (child) skb
160 * @node: numa node to allocate memory on
161 *
162 * Allocate a new &sk_buff. The returned buffer has no headroom and a
163 * tail room of size bytes. The object has a reference count of one.
164 * The return is the buffer. On a failure the return is %NULL.
165 *
166 * Buffers may only be allocated from interrupts using a @gfp_mask of
167 * %GFP_ATOMIC.
168 */
169struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
170 int fclone, int node)
171{
172 struct kmem_cache *cache;
173 struct skb_shared_info *shinfo;
174 struct sk_buff *skb;
175 u8 *data;
176
177 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
178
179 /* Get the HEAD */
180 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
181 if (!skb)
182 goto out;
183 prefetchw(skb);
184
185 /* We do our best to align skb_shared_info on a separate cache
186 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
187 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
188 * Both skb->head and skb_shared_info are cache line aligned.
189 */
190 size = SKB_DATA_ALIGN(size);
191 size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
192 data = kmalloc_node_track_caller(size, gfp_mask, node);
193 if (!data)
194 goto nodata;
195 /* kmalloc(size) might give us more room than requested.
196 * Put skb_shared_info exactly at the end of allocated zone,
197 * to allow max possible filling before reallocation.
198 */
199 size = SKB_WITH_OVERHEAD(ksize(data));
200 prefetchw(data + size);
201
202 /*
203 * Only clear those fields we need to clear, not those that we will
204 * actually initialise below. Hence, don't put any more fields after
205 * the tail pointer in struct sk_buff!
206 */
207 memset(skb, 0, offsetof(struct sk_buff, tail));
208 /* Account for allocated memory : skb + skb->head */
209 skb->truesize = SKB_TRUESIZE(size);
210 atomic_set(&skb->users, 1);
211 skb->head = data;
212 skb->data = data;
213 skb_reset_tail_pointer(skb);
214 skb->end = skb->tail + size;
215#ifdef NET_SKBUFF_DATA_USES_OFFSET
216 skb->mac_header = ~0U;
217#endif
218
219 /* make sure we initialize shinfo sequentially */
220 shinfo = skb_shinfo(skb);
221 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
222 atomic_set(&shinfo->dataref, 1);
223 kmemcheck_annotate_variable(shinfo->destructor_arg);
224
225 if (fclone) {
226 struct sk_buff *child = skb + 1;
227 atomic_t *fclone_ref = (atomic_t *) (child + 1);
228
229 kmemcheck_annotate_bitfield(child, flags1);
230 kmemcheck_annotate_bitfield(child, flags2);
231 skb->fclone = SKB_FCLONE_ORIG;
232 atomic_set(fclone_ref, 1);
233
234 child->fclone = SKB_FCLONE_UNAVAILABLE;
235 }
236out:
237 return skb;
238nodata:
239 kmem_cache_free(cache, skb);
240 skb = NULL;
241 goto out;
242}
243EXPORT_SYMBOL(__alloc_skb);
244
245/**
246 * build_skb - build a network buffer
247 * @data: data buffer provided by caller
248 * @frag_size: size of fragment, or 0 if head was kmalloced
249 *
250 * Allocate a new &sk_buff. Caller provides space holding head and
251 * skb_shared_info. @data must have been allocated by kmalloc()
252 * The return is the new skb buffer.
253 * On a failure the return is %NULL, and @data is not freed.
254 * Notes :
255 * Before IO, driver allocates only data buffer where NIC put incoming frame
256 * Driver should add room at head (NET_SKB_PAD) and
257 * MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
258 * After IO, driver calls build_skb(), to allocate sk_buff and populate it
259 * before giving packet to stack.
260 * RX rings only contains data buffers, not full skbs.
261 */
262struct sk_buff *build_skb(void *data, unsigned int frag_size)
263{
264 struct skb_shared_info *shinfo;
265 struct sk_buff *skb;
266 unsigned int size = frag_size ? : ksize(data);
267
268 skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
269 if (!skb)
270 return NULL;
271
272 size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
273
274 memset(skb, 0, offsetof(struct sk_buff, tail));
275 skb->truesize = SKB_TRUESIZE(size);
276 skb->head_frag = frag_size != 0;
277 atomic_set(&skb->users, 1);
278 skb->head = data;
279 skb->data = data;
280 skb_reset_tail_pointer(skb);
281 skb->end = skb->tail + size;
282#ifdef NET_SKBUFF_DATA_USES_OFFSET
283 skb->mac_header = ~0U;
284#endif
285
286 /* make sure we initialize shinfo sequentially */
287 shinfo = skb_shinfo(skb);
288 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
289 atomic_set(&shinfo->dataref, 1);
290 kmemcheck_annotate_variable(shinfo->destructor_arg);
291
292 return skb;
293}
294EXPORT_SYMBOL(build_skb);
295
296struct netdev_alloc_cache {
297 struct page *page;
298 unsigned int offset;
299};
300static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
301
302/**
303 * netdev_alloc_frag - allocate a page fragment
304 * @fragsz: fragment size
305 *
306 * Allocates a frag from a page for receive buffer.
307 * Uses GFP_ATOMIC allocations.
308 */
309void *netdev_alloc_frag(unsigned int fragsz)
310{
311 struct netdev_alloc_cache *nc;
312 void *data = NULL;
313 unsigned long flags;
314
315 local_irq_save(flags);
316 nc = &__get_cpu_var(netdev_alloc_cache);
317 if (unlikely(!nc->page)) {
318refill:
319 nc->page = alloc_page(GFP_ATOMIC | __GFP_COLD);
320 nc->offset = 0;
321 }
322 if (likely(nc->page)) {
323 if (nc->offset + fragsz > PAGE_SIZE) {
324 put_page(nc->page);
325 goto refill;
326 }
327 data = page_address(nc->page) + nc->offset;
328 nc->offset += fragsz;
329 get_page(nc->page);
330 }
331 local_irq_restore(flags);
332 return data;
333}
334EXPORT_SYMBOL(netdev_alloc_frag);
335
336/**
337 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
338 * @dev: network device to receive on
339 * @length: length to allocate
340 * @gfp_mask: get_free_pages mask, passed to alloc_skb
341 *
342 * Allocate a new &sk_buff and assign it a usage count of one. The
343 * buffer has unspecified headroom built in. Users should allocate
344 * the headroom they think they need without accounting for the
345 * built in space. The built in space is used for optimisations.
346 *
347 * %NULL is returned if there is no free memory.
348 */
349struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
350 unsigned int length, gfp_t gfp_mask)
351{
352 struct sk_buff *skb = NULL;
353 unsigned int fragsz = SKB_DATA_ALIGN(length + NET_SKB_PAD) +
354 SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
355
356 if (fragsz <= PAGE_SIZE && !(gfp_mask & (__GFP_WAIT | GFP_DMA))) {
357 void *data = netdev_alloc_frag(fragsz);
358
359 if (likely(data)) {
360 skb = build_skb(data, fragsz);
361 if (unlikely(!skb))
362 put_page(virt_to_head_page(data));
363 }
364 } else {
365 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
366 }
367 if (likely(skb)) {
368 skb_reserve(skb, NET_SKB_PAD);
369 skb->dev = dev;
370 }
371 return skb;
372}
373EXPORT_SYMBOL(__netdev_alloc_skb);
374
375void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
376 int size, unsigned int truesize)
377{
378 skb_fill_page_desc(skb, i, page, off, size);
379 skb->len += size;
380 skb->data_len += size;
381 skb->truesize += truesize;
382}
383EXPORT_SYMBOL(skb_add_rx_frag);
384
385static void skb_drop_list(struct sk_buff **listp)
386{
387 struct sk_buff *list = *listp;
388
389 *listp = NULL;
390
391 do {
392 struct sk_buff *this = list;
393 list = list->next;
394 kfree_skb(this);
395 } while (list);
396}
397
398static inline void skb_drop_fraglist(struct sk_buff *skb)
399{
400 skb_drop_list(&skb_shinfo(skb)->frag_list);
401}
402
403static void skb_clone_fraglist(struct sk_buff *skb)
404{
405 struct sk_buff *list;
406
407 skb_walk_frags(skb, list)
408 skb_get(list);
409}
410
411static void skb_free_head(struct sk_buff *skb)
412{
413 if (skb->head_frag)
414 put_page(virt_to_head_page(skb->head));
415 else
416 kfree(skb->head);
417}
418
419static void skb_release_data(struct sk_buff *skb)
420{
421 if (!skb->cloned ||
422 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
423 &skb_shinfo(skb)->dataref)) {
424 if (skb_shinfo(skb)->nr_frags) {
425 int i;
426 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
427 skb_frag_unref(skb, i);
428 }
429
430 /*
431 * If skb buf is from userspace, we need to notify the caller
432 * the lower device DMA has done;
433 */
434 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
435 struct ubuf_info *uarg;
436
437 uarg = skb_shinfo(skb)->destructor_arg;
438 if (uarg->callback)
439 uarg->callback(uarg);
440 }
441
442 if (skb_has_frag_list(skb))
443 skb_drop_fraglist(skb);
444
445 skb_free_head(skb);
446 }
447}
448
449/*
450 * Free an skbuff by memory without cleaning the state.
451 */
452static void kfree_skbmem(struct sk_buff *skb)
453{
454 struct sk_buff *other;
455 atomic_t *fclone_ref;
456
457 switch (skb->fclone) {
458 case SKB_FCLONE_UNAVAILABLE:
459 kmem_cache_free(skbuff_head_cache, skb);
460 break;
461
462 case SKB_FCLONE_ORIG:
463 fclone_ref = (atomic_t *) (skb + 2);
464 if (atomic_dec_and_test(fclone_ref))
465 kmem_cache_free(skbuff_fclone_cache, skb);
466 break;
467
468 case SKB_FCLONE_CLONE:
469 fclone_ref = (atomic_t *) (skb + 1);
470 other = skb - 1;
471
472 /* The clone portion is available for
473 * fast-cloning again.
474 */
475 skb->fclone = SKB_FCLONE_UNAVAILABLE;
476
477 if (atomic_dec_and_test(fclone_ref))
478 kmem_cache_free(skbuff_fclone_cache, other);
479 break;
480 }
481}
482
483static void skb_release_head_state(struct sk_buff *skb)
484{
485 skb_dst_drop(skb);
486#ifdef CONFIG_XFRM
487 secpath_put(skb->sp);
488#endif
489 if (skb->destructor) {
490 WARN_ON(in_irq());
491 skb->destructor(skb);
492 }
493#if IS_ENABLED(CONFIG_NF_CONNTRACK)
494 nf_conntrack_put(skb->nfct);
495#endif
496#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
497 nf_conntrack_put_reasm(skb->nfct_reasm);
498#endif
499#ifdef CONFIG_BRIDGE_NETFILTER
500 nf_bridge_put(skb->nf_bridge);
501#endif
502/* XXX: IS this still necessary? - JHS */
503#ifdef CONFIG_NET_SCHED
504 skb->tc_index = 0;
505#ifdef CONFIG_NET_CLS_ACT
506 skb->tc_verd = 0;
507#endif
508#endif
509}
510
511/* Free everything but the sk_buff shell. */
512static void skb_release_all(struct sk_buff *skb)
513{
514 skb_release_head_state(skb);
515 skb_release_data(skb);
516}
517
518/**
519 * __kfree_skb - private function
520 * @skb: buffer
521 *
522 * Free an sk_buff. Release anything attached to the buffer.
523 * Clean the state. This is an internal helper function. Users should
524 * always call kfree_skb
525 */
526
527void __kfree_skb(struct sk_buff *skb)
528{
529 skb_release_all(skb);
530 kfree_skbmem(skb);
531}
532EXPORT_SYMBOL(__kfree_skb);
533
534/**
535 * kfree_skb - free an sk_buff
536 * @skb: buffer to free
537 *
538 * Drop a reference to the buffer and free it if the usage count has
539 * hit zero.
540 */
541void kfree_skb(struct sk_buff *skb)
542{
543 if (unlikely(!skb))
544 return;
545 if (likely(atomic_read(&skb->users) == 1))
546 smp_rmb();
547 else if (likely(!atomic_dec_and_test(&skb->users)))
548 return;
549 trace_kfree_skb(skb, __builtin_return_address(0));
550 __kfree_skb(skb);
551}
552EXPORT_SYMBOL(kfree_skb);
553
554/**
555 * consume_skb - free an skbuff
556 * @skb: buffer to free
557 *
558 * Drop a ref to the buffer and free it if the usage count has hit zero
559 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
560 * is being dropped after a failure and notes that
561 */
562void consume_skb(struct sk_buff *skb)
563{
564 if (unlikely(!skb))
565 return;
566 if (likely(atomic_read(&skb->users) == 1))
567 smp_rmb();
568 else if (likely(!atomic_dec_and_test(&skb->users)))
569 return;
570 trace_consume_skb(skb);
571 __kfree_skb(skb);
572}
573EXPORT_SYMBOL(consume_skb);
574
575/**
576 * skb_recycle - clean up an skb for reuse
577 * @skb: buffer
578 *
579 * Recycles the skb to be reused as a receive buffer. This
580 * function does any necessary reference count dropping, and
581 * cleans up the skbuff as if it just came from __alloc_skb().
582 */
583void skb_recycle(struct sk_buff *skb)
584{
585 struct skb_shared_info *shinfo;
586
587 skb_release_head_state(skb);
588
589 shinfo = skb_shinfo(skb);
590 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
591 atomic_set(&shinfo->dataref, 1);
592
593 memset(skb, 0, offsetof(struct sk_buff, tail));
594 skb->data = skb->head + NET_SKB_PAD;
595 skb_reset_tail_pointer(skb);
596}
597EXPORT_SYMBOL(skb_recycle);
598
599/**
600 * skb_recycle_check - check if skb can be reused for receive
601 * @skb: buffer
602 * @skb_size: minimum receive buffer size
603 *
604 * Checks that the skb passed in is not shared or cloned, and
605 * that it is linear and its head portion at least as large as
606 * skb_size so that it can be recycled as a receive buffer.
607 * If these conditions are met, this function does any necessary
608 * reference count dropping and cleans up the skbuff as if it
609 * just came from __alloc_skb().
610 */
611bool skb_recycle_check(struct sk_buff *skb, int skb_size)
612{
613 if (!skb_is_recycleable(skb, skb_size))
614 return false;
615
616 skb_recycle(skb);
617
618 return true;
619}
620EXPORT_SYMBOL(skb_recycle_check);
621
622static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
623{
624 new->tstamp = old->tstamp;
625 new->dev = old->dev;
626 new->transport_header = old->transport_header;
627 new->network_header = old->network_header;
628 new->mac_header = old->mac_header;
629 skb_dst_copy(new, old);
630 new->rxhash = old->rxhash;
631 new->ooo_okay = old->ooo_okay;
632 new->l4_rxhash = old->l4_rxhash;
633 new->no_fcs = old->no_fcs;
634#ifdef CONFIG_XFRM
635 new->sp = secpath_get(old->sp);
636#endif
637 memcpy(new->cb, old->cb, sizeof(old->cb));
638 new->csum = old->csum;
639 new->local_df = old->local_df;
640 new->pkt_type = old->pkt_type;
641 new->ip_summed = old->ip_summed;
642 skb_copy_queue_mapping(new, old);
643 new->priority = old->priority;
644#if IS_ENABLED(CONFIG_IP_VS)
645 new->ipvs_property = old->ipvs_property;
646#endif
647 new->protocol = old->protocol;
648 new->mark = old->mark;
649 new->skb_iif = old->skb_iif;
650 __nf_copy(new, old);
651#if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)
652 new->nf_trace = old->nf_trace;
653#endif
654#ifdef CONFIG_NET_SCHED
655 new->tc_index = old->tc_index;
656#ifdef CONFIG_NET_CLS_ACT
657 new->tc_verd = old->tc_verd;
658#endif
659#endif
660 new->vlan_tci = old->vlan_tci;
661
662 skb_copy_secmark(new, old);
663}
664
665/*
666 * You should not add any new code to this function. Add it to
667 * __copy_skb_header above instead.
668 */
669static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
670{
671#define C(x) n->x = skb->x
672
673 n->next = n->prev = NULL;
674 n->sk = NULL;
675 __copy_skb_header(n, skb);
676
677 C(len);
678 C(data_len);
679 C(mac_len);
680 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
681 n->cloned = 1;
682 n->nohdr = 0;
683 n->destructor = NULL;
684 C(tail);
685 C(end);
686 C(head);
687 C(head_frag);
688 C(data);
689 C(truesize);
690 atomic_set(&n->users, 1);
691
692 atomic_inc(&(skb_shinfo(skb)->dataref));
693 skb->cloned = 1;
694
695 return n;
696#undef C
697}
698
699/**
700 * skb_morph - morph one skb into another
701 * @dst: the skb to receive the contents
702 * @src: the skb to supply the contents
703 *
704 * This is identical to skb_clone except that the target skb is
705 * supplied by the user.
706 *
707 * The target skb is returned upon exit.
708 */
709struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
710{
711 skb_release_all(dst);
712 return __skb_clone(dst, src);
713}
714EXPORT_SYMBOL_GPL(skb_morph);
715
716/* skb_copy_ubufs - copy userspace skb frags buffers to kernel
717 * @skb: the skb to modify
718 * @gfp_mask: allocation priority
719 *
720 * This must be called on SKBTX_DEV_ZEROCOPY skb.
721 * It will copy all frags into kernel and drop the reference
722 * to userspace pages.
723 *
724 * If this function is called from an interrupt gfp_mask() must be
725 * %GFP_ATOMIC.
726 *
727 * Returns 0 on success or a negative error code on failure
728 * to allocate kernel memory to copy to.
729 */
730int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
731{
732 int i;
733 int num_frags = skb_shinfo(skb)->nr_frags;
734 struct page *page, *head = NULL;
735 struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;
736
737 for (i = 0; i < num_frags; i++) {
738 u8 *vaddr;
739 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
740
741 page = alloc_page(GFP_ATOMIC);
742 if (!page) {
743 while (head) {
744 struct page *next = (struct page *)head->private;
745 put_page(head);
746 head = next;
747 }
748 return -ENOMEM;
749 }
750 vaddr = kmap_atomic(skb_frag_page(f));
751 memcpy(page_address(page),
752 vaddr + f->page_offset, skb_frag_size(f));
753 kunmap_atomic(vaddr);
754 page->private = (unsigned long)head;
755 head = page;
756 }
757
758 /* skb frags release userspace buffers */
759 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
760 skb_frag_unref(skb, i);
761
762 uarg->callback(uarg);
763
764 /* skb frags point to kernel buffers */
765 for (i = skb_shinfo(skb)->nr_frags; i > 0; i--) {
766 __skb_fill_page_desc(skb, i-1, head, 0,
767 skb_shinfo(skb)->frags[i - 1].size);
768 head = (struct page *)head->private;
769 }
770
771 skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
772 return 0;
773}
774
775
776/**
777 * skb_clone - duplicate an sk_buff
778 * @skb: buffer to clone
779 * @gfp_mask: allocation priority
780 *
781 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
782 * copies share the same packet data but not structure. The new
783 * buffer has a reference count of 1. If the allocation fails the
784 * function returns %NULL otherwise the new buffer is returned.
785 *
786 * If this function is called from an interrupt gfp_mask() must be
787 * %GFP_ATOMIC.
788 */
789
790struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
791{
792 struct sk_buff *n;
793
794 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
795 if (skb_copy_ubufs(skb, gfp_mask))
796 return NULL;
797 }
798
799 n = skb + 1;
800 if (skb->fclone == SKB_FCLONE_ORIG &&
801 n->fclone == SKB_FCLONE_UNAVAILABLE) {
802 atomic_t *fclone_ref = (atomic_t *) (n + 1);
803 n->fclone = SKB_FCLONE_CLONE;
804 atomic_inc(fclone_ref);
805 } else {
806 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
807 if (!n)
808 return NULL;
809
810 kmemcheck_annotate_bitfield(n, flags1);
811 kmemcheck_annotate_bitfield(n, flags2);
812 n->fclone = SKB_FCLONE_UNAVAILABLE;
813 }
814
815 return __skb_clone(n, skb);
816}
817EXPORT_SYMBOL(skb_clone);
818
819static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
820{
821#ifndef NET_SKBUFF_DATA_USES_OFFSET
822 /*
823 * Shift between the two data areas in bytes
824 */
825 unsigned long offset = new->data - old->data;
826#endif
827
828 __copy_skb_header(new, old);
829
830#ifndef NET_SKBUFF_DATA_USES_OFFSET
831 /* {transport,network,mac}_header are relative to skb->head */
832 new->transport_header += offset;
833 new->network_header += offset;
834 if (skb_mac_header_was_set(new))
835 new->mac_header += offset;
836#endif
837 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
838 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
839 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
840}
841
842/**
843 * skb_copy - create private copy of an sk_buff
844 * @skb: buffer to copy
845 * @gfp_mask: allocation priority
846 *
847 * Make a copy of both an &sk_buff and its data. This is used when the
848 * caller wishes to modify the data and needs a private copy of the
849 * data to alter. Returns %NULL on failure or the pointer to the buffer
850 * on success. The returned buffer has a reference count of 1.
851 *
852 * As by-product this function converts non-linear &sk_buff to linear
853 * one, so that &sk_buff becomes completely private and caller is allowed
854 * to modify all the data of returned buffer. This means that this
855 * function is not recommended for use in circumstances when only
856 * header is going to be modified. Use pskb_copy() instead.
857 */
858
859struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
860{
861 int headerlen = skb_headroom(skb);
862 unsigned int size = skb_end_offset(skb) + skb->data_len;
863 struct sk_buff *n = alloc_skb(size, gfp_mask);
864
865 if (!n)
866 return NULL;
867
868 /* Set the data pointer */
869 skb_reserve(n, headerlen);
870 /* Set the tail pointer and length */
871 skb_put(n, skb->len);
872
873 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
874 BUG();
875
876 copy_skb_header(n, skb);
877 return n;
878}
879EXPORT_SYMBOL(skb_copy);
880
881/**
882 * __pskb_copy - create copy of an sk_buff with private head.
883 * @skb: buffer to copy
884 * @headroom: headroom of new skb
885 * @gfp_mask: allocation priority
886 *
887 * Make a copy of both an &sk_buff and part of its data, located
888 * in header. Fragmented data remain shared. This is used when
889 * the caller wishes to modify only header of &sk_buff and needs
890 * private copy of the header to alter. Returns %NULL on failure
891 * or the pointer to the buffer on success.
892 * The returned buffer has a reference count of 1.
893 */
894
895struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom, gfp_t gfp_mask)
896{
897 unsigned int size = skb_headlen(skb) + headroom;
898 struct sk_buff *n = alloc_skb(size, gfp_mask);
899
900 if (!n)
901 goto out;
902
903 /* Set the data pointer */
904 skb_reserve(n, headroom);
905 /* Set the tail pointer and length */
906 skb_put(n, skb_headlen(skb));
907 /* Copy the bytes */
908 skb_copy_from_linear_data(skb, n->data, n->len);
909
910 n->truesize += skb->data_len;
911 n->data_len = skb->data_len;
912 n->len = skb->len;
913
914 if (skb_shinfo(skb)->nr_frags) {
915 int i;
916
917 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
918 if (skb_copy_ubufs(skb, gfp_mask)) {
919 kfree_skb(n);
920 n = NULL;
921 goto out;
922 }
923 }
924 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
925 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
926 skb_frag_ref(skb, i);
927 }
928 skb_shinfo(n)->nr_frags = i;
929 }
930
931 if (skb_has_frag_list(skb)) {
932 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
933 skb_clone_fraglist(n);
934 }
935
936 copy_skb_header(n, skb);
937out:
938 return n;
939}
940EXPORT_SYMBOL(__pskb_copy);
941
942/**
943 * pskb_expand_head - reallocate header of &sk_buff
944 * @skb: buffer to reallocate
945 * @nhead: room to add at head
946 * @ntail: room to add at tail
947 * @gfp_mask: allocation priority
948 *
949 * Expands (or creates identical copy, if &nhead and &ntail are zero)
950 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
951 * reference count of 1. Returns zero in the case of success or error,
952 * if expansion failed. In the last case, &sk_buff is not changed.
953 *
954 * All the pointers pointing into skb header may change and must be
955 * reloaded after call to this function.
956 */
957
958int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
959 gfp_t gfp_mask)
960{
961 int i;
962 u8 *data;
963 int size = nhead + skb_end_offset(skb) + ntail;
964 long off;
965
966 BUG_ON(nhead < 0);
967
968 if (skb_shared(skb))
969 BUG();
970
971 size = SKB_DATA_ALIGN(size);
972
973 data = kmalloc(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
974 gfp_mask);
975 if (!data)
976 goto nodata;
977 size = SKB_WITH_OVERHEAD(ksize(data));
978
979 /* Copy only real data... and, alas, header. This should be
980 * optimized for the cases when header is void.
981 */
982 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
983
984 memcpy((struct skb_shared_info *)(data + size),
985 skb_shinfo(skb),
986 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
987
988 /*
989 * if shinfo is shared we must drop the old head gracefully, but if it
990 * is not we can just drop the old head and let the existing refcount
991 * be since all we did is relocate the values
992 */
993 if (skb_cloned(skb)) {
994 /* copy this zero copy skb frags */
995 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
996 if (skb_copy_ubufs(skb, gfp_mask))
997 goto nofrags;
998 }
999 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1000 skb_frag_ref(skb, i);
1001
1002 if (skb_has_frag_list(skb))
1003 skb_clone_fraglist(skb);
1004
1005 skb_release_data(skb);
1006 } else {
1007 skb_free_head(skb);
1008 }
1009 off = (data + nhead) - skb->head;
1010
1011 skb->head = data;
1012 skb->head_frag = 0;
1013 skb->data += off;
1014#ifdef NET_SKBUFF_DATA_USES_OFFSET
1015 skb->end = size;
1016 off = nhead;
1017#else
1018 skb->end = skb->head + size;
1019#endif
1020 /* {transport,network,mac}_header and tail are relative to skb->head */
1021 skb->tail += off;
1022 skb->transport_header += off;
1023 skb->network_header += off;
1024 if (skb_mac_header_was_set(skb))
1025 skb->mac_header += off;
1026 /* Only adjust this if it actually is csum_start rather than csum */
1027 if (skb->ip_summed == CHECKSUM_PARTIAL)
1028 skb->csum_start += nhead;
1029 skb->cloned = 0;
1030 skb->hdr_len = 0;
1031 skb->nohdr = 0;
1032 atomic_set(&skb_shinfo(skb)->dataref, 1);
1033 return 0;
1034
1035nofrags:
1036 kfree(data);
1037nodata:
1038 return -ENOMEM;
1039}
1040EXPORT_SYMBOL(pskb_expand_head);
1041
1042/* Make private copy of skb with writable head and some headroom */
1043
1044struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1045{
1046 struct sk_buff *skb2;
1047 int delta = headroom - skb_headroom(skb);
1048
1049 if (delta <= 0)
1050 skb2 = pskb_copy(skb, GFP_ATOMIC);
1051 else {
1052 skb2 = skb_clone(skb, GFP_ATOMIC);
1053 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1054 GFP_ATOMIC)) {
1055 kfree_skb(skb2);
1056 skb2 = NULL;
1057 }
1058 }
1059 return skb2;
1060}
1061EXPORT_SYMBOL(skb_realloc_headroom);
1062
1063/**
1064 * skb_copy_expand - copy and expand sk_buff
1065 * @skb: buffer to copy
1066 * @newheadroom: new free bytes at head
1067 * @newtailroom: new free bytes at tail
1068 * @gfp_mask: allocation priority
1069 *
1070 * Make a copy of both an &sk_buff and its data and while doing so
1071 * allocate additional space.
1072 *
1073 * This is used when the caller wishes to modify the data and needs a
1074 * private copy of the data to alter as well as more space for new fields.
1075 * Returns %NULL on failure or the pointer to the buffer
1076 * on success. The returned buffer has a reference count of 1.
1077 *
1078 * You must pass %GFP_ATOMIC as the allocation priority if this function
1079 * is called from an interrupt.
1080 */
1081struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
1082 int newheadroom, int newtailroom,
1083 gfp_t gfp_mask)
1084{
1085 /*
1086 * Allocate the copy buffer
1087 */
1088 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
1089 gfp_mask);
1090 int oldheadroom = skb_headroom(skb);
1091 int head_copy_len, head_copy_off;
1092 int off;
1093
1094 if (!n)
1095 return NULL;
1096
1097 skb_reserve(n, newheadroom);
1098
1099 /* Set the tail pointer and length */
1100 skb_put(n, skb->len);
1101
1102 head_copy_len = oldheadroom;
1103 head_copy_off = 0;
1104 if (newheadroom <= head_copy_len)
1105 head_copy_len = newheadroom;
1106 else
1107 head_copy_off = newheadroom - head_copy_len;
1108
1109 /* Copy the linear header and data. */
1110 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1111 skb->len + head_copy_len))
1112 BUG();
1113
1114 copy_skb_header(n, skb);
1115
1116 off = newheadroom - oldheadroom;
1117 if (n->ip_summed == CHECKSUM_PARTIAL)
1118 n->csum_start += off;
1119#ifdef NET_SKBUFF_DATA_USES_OFFSET
1120 n->transport_header += off;
1121 n->network_header += off;
1122 if (skb_mac_header_was_set(skb))
1123 n->mac_header += off;
1124#endif
1125
1126 return n;
1127}
1128EXPORT_SYMBOL(skb_copy_expand);
1129
1130/**
1131 * skb_pad - zero pad the tail of an skb
1132 * @skb: buffer to pad
1133 * @pad: space to pad
1134 *
1135 * Ensure that a buffer is followed by a padding area that is zero
1136 * filled. Used by network drivers which may DMA or transfer data
1137 * beyond the buffer end onto the wire.
1138 *
1139 * May return error in out of memory cases. The skb is freed on error.
1140 */
1141
1142int skb_pad(struct sk_buff *skb, int pad)
1143{
1144 int err;
1145 int ntail;
1146
1147 /* If the skbuff is non linear tailroom is always zero.. */
1148 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1149 memset(skb->data+skb->len, 0, pad);
1150 return 0;
1151 }
1152
1153 ntail = skb->data_len + pad - (skb->end - skb->tail);
1154 if (likely(skb_cloned(skb) || ntail > 0)) {
1155 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1156 if (unlikely(err))
1157 goto free_skb;
1158 }
1159
1160 /* FIXME: The use of this function with non-linear skb's really needs
1161 * to be audited.
1162 */
1163 err = skb_linearize(skb);
1164 if (unlikely(err))
1165 goto free_skb;
1166
1167 memset(skb->data + skb->len, 0, pad);
1168 return 0;
1169
1170free_skb:
1171 kfree_skb(skb);
1172 return err;
1173}
1174EXPORT_SYMBOL(skb_pad);
1175
1176/**
1177 * skb_put - add data to a buffer
1178 * @skb: buffer to use
1179 * @len: amount of data to add
1180 *
1181 * This function extends the used data area of the buffer. If this would
1182 * exceed the total buffer size the kernel will panic. A pointer to the
1183 * first byte of the extra data is returned.
1184 */
1185unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
1186{
1187 unsigned char *tmp = skb_tail_pointer(skb);
1188 SKB_LINEAR_ASSERT(skb);
1189 skb->tail += len;
1190 skb->len += len;
1191 if (unlikely(skb->tail > skb->end))
1192 skb_over_panic(skb, len, __builtin_return_address(0));
1193 return tmp;
1194}
1195EXPORT_SYMBOL(skb_put);
1196
1197/**
1198 * skb_push - add data to the start of a buffer
1199 * @skb: buffer to use
1200 * @len: amount of data to add
1201 *
1202 * This function extends the used data area of the buffer at the buffer
1203 * start. If this would exceed the total buffer headroom the kernel will
1204 * panic. A pointer to the first byte of the extra data is returned.
1205 */
1206unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1207{
1208 skb->data -= len;
1209 skb->len += len;
1210 if (unlikely(skb->data<skb->head))
1211 skb_under_panic(skb, len, __builtin_return_address(0));
1212 return skb->data;
1213}
1214EXPORT_SYMBOL(skb_push);
1215
1216/**
1217 * skb_pull - remove data from the start of a buffer
1218 * @skb: buffer to use
1219 * @len: amount of data to remove
1220 *
1221 * This function removes data from the start of a buffer, returning
1222 * the memory to the headroom. A pointer to the next data in the buffer
1223 * is returned. Once the data has been pulled future pushes will overwrite
1224 * the old data.
1225 */
1226unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1227{
1228 return skb_pull_inline(skb, len);
1229}
1230EXPORT_SYMBOL(skb_pull);
1231
1232/**
1233 * skb_trim - remove end from a buffer
1234 * @skb: buffer to alter
1235 * @len: new length
1236 *
1237 * Cut the length of a buffer down by removing data from the tail. If
1238 * the buffer is already under the length specified it is not modified.
1239 * The skb must be linear.
1240 */
1241void skb_trim(struct sk_buff *skb, unsigned int len)
1242{
1243 if (skb->len > len)
1244 __skb_trim(skb, len);
1245}
1246EXPORT_SYMBOL(skb_trim);
1247
1248/* Trims skb to length len. It can change skb pointers.
1249 */
1250
1251int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1252{
1253 struct sk_buff **fragp;
1254 struct sk_buff *frag;
1255 int offset = skb_headlen(skb);
1256 int nfrags = skb_shinfo(skb)->nr_frags;
1257 int i;
1258 int err;
1259
1260 if (skb_cloned(skb) &&
1261 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1262 return err;
1263
1264 i = 0;
1265 if (offset >= len)
1266 goto drop_pages;
1267
1268 for (; i < nfrags; i++) {
1269 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
1270
1271 if (end < len) {
1272 offset = end;
1273 continue;
1274 }
1275
1276 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
1277
1278drop_pages:
1279 skb_shinfo(skb)->nr_frags = i;
1280
1281 for (; i < nfrags; i++)
1282 skb_frag_unref(skb, i);
1283
1284 if (skb_has_frag_list(skb))
1285 skb_drop_fraglist(skb);
1286 goto done;
1287 }
1288
1289 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1290 fragp = &frag->next) {
1291 int end = offset + frag->len;
1292
1293 if (skb_shared(frag)) {
1294 struct sk_buff *nfrag;
1295
1296 nfrag = skb_clone(frag, GFP_ATOMIC);
1297 if (unlikely(!nfrag))
1298 return -ENOMEM;
1299
1300 nfrag->next = frag->next;
1301 consume_skb(frag);
1302 frag = nfrag;
1303 *fragp = frag;
1304 }
1305
1306 if (end < len) {
1307 offset = end;
1308 continue;
1309 }
1310
1311 if (end > len &&
1312 unlikely((err = pskb_trim(frag, len - offset))))
1313 return err;
1314
1315 if (frag->next)
1316 skb_drop_list(&frag->next);
1317 break;
1318 }
1319
1320done:
1321 if (len > skb_headlen(skb)) {
1322 skb->data_len -= skb->len - len;
1323 skb->len = len;
1324 } else {
1325 skb->len = len;
1326 skb->data_len = 0;
1327 skb_set_tail_pointer(skb, len);
1328 }
1329
1330 return 0;
1331}
1332EXPORT_SYMBOL(___pskb_trim);
1333
1334/**
1335 * __pskb_pull_tail - advance tail of skb header
1336 * @skb: buffer to reallocate
1337 * @delta: number of bytes to advance tail
1338 *
1339 * The function makes a sense only on a fragmented &sk_buff,
1340 * it expands header moving its tail forward and copying necessary
1341 * data from fragmented part.
1342 *
1343 * &sk_buff MUST have reference count of 1.
1344 *
1345 * Returns %NULL (and &sk_buff does not change) if pull failed
1346 * or value of new tail of skb in the case of success.
1347 *
1348 * All the pointers pointing into skb header may change and must be
1349 * reloaded after call to this function.
1350 */
1351
1352/* Moves tail of skb head forward, copying data from fragmented part,
1353 * when it is necessary.
1354 * 1. It may fail due to malloc failure.
1355 * 2. It may change skb pointers.
1356 *
1357 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1358 */
1359unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1360{
1361 /* If skb has not enough free space at tail, get new one
1362 * plus 128 bytes for future expansions. If we have enough
1363 * room at tail, reallocate without expansion only if skb is cloned.
1364 */
1365 int i, k, eat = (skb->tail + delta) - skb->end;
1366
1367 if (eat > 0 || skb_cloned(skb)) {
1368 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1369 GFP_ATOMIC))
1370 return NULL;
1371 }
1372
1373 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1374 BUG();
1375
1376 /* Optimization: no fragments, no reasons to preestimate
1377 * size of pulled pages. Superb.
1378 */
1379 if (!skb_has_frag_list(skb))
1380 goto pull_pages;
1381
1382 /* Estimate size of pulled pages. */
1383 eat = delta;
1384 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1385 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1386
1387 if (size >= eat)
1388 goto pull_pages;
1389 eat -= size;
1390 }
1391
1392 /* If we need update frag list, we are in troubles.
1393 * Certainly, it possible to add an offset to skb data,
1394 * but taking into account that pulling is expected to
1395 * be very rare operation, it is worth to fight against
1396 * further bloating skb head and crucify ourselves here instead.
1397 * Pure masohism, indeed. 8)8)
1398 */
1399 if (eat) {
1400 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1401 struct sk_buff *clone = NULL;
1402 struct sk_buff *insp = NULL;
1403
1404 do {
1405 BUG_ON(!list);
1406
1407 if (list->len <= eat) {
1408 /* Eaten as whole. */
1409 eat -= list->len;
1410 list = list->next;
1411 insp = list;
1412 } else {
1413 /* Eaten partially. */
1414
1415 if (skb_shared(list)) {
1416 /* Sucks! We need to fork list. :-( */
1417 clone = skb_clone(list, GFP_ATOMIC);
1418 if (!clone)
1419 return NULL;
1420 insp = list->next;
1421 list = clone;
1422 } else {
1423 /* This may be pulled without
1424 * problems. */
1425 insp = list;
1426 }
1427 if (!pskb_pull(list, eat)) {
1428 kfree_skb(clone);
1429 return NULL;
1430 }
1431 break;
1432 }
1433 } while (eat);
1434
1435 /* Free pulled out fragments. */
1436 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1437 skb_shinfo(skb)->frag_list = list->next;
1438 kfree_skb(list);
1439 }
1440 /* And insert new clone at head. */
1441 if (clone) {
1442 clone->next = list;
1443 skb_shinfo(skb)->frag_list = clone;
1444 }
1445 }
1446 /* Success! Now we may commit changes to skb data. */
1447
1448pull_pages:
1449 eat = delta;
1450 k = 0;
1451 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1452 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1453
1454 if (size <= eat) {
1455 skb_frag_unref(skb, i);
1456 eat -= size;
1457 } else {
1458 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1459 if (eat) {
1460 skb_shinfo(skb)->frags[k].page_offset += eat;
1461 skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
1462 eat = 0;
1463 }
1464 k++;
1465 }
1466 }
1467 skb_shinfo(skb)->nr_frags = k;
1468
1469 skb->tail += delta;
1470 skb->data_len -= delta;
1471
1472 return skb_tail_pointer(skb);
1473}
1474EXPORT_SYMBOL(__pskb_pull_tail);
1475
1476/**
1477 * skb_copy_bits - copy bits from skb to kernel buffer
1478 * @skb: source skb
1479 * @offset: offset in source
1480 * @to: destination buffer
1481 * @len: number of bytes to copy
1482 *
1483 * Copy the specified number of bytes from the source skb to the
1484 * destination buffer.
1485 *
1486 * CAUTION ! :
1487 * If its prototype is ever changed,
1488 * check arch/{*}/net/{*}.S files,
1489 * since it is called from BPF assembly code.
1490 */
1491int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1492{
1493 int start = skb_headlen(skb);
1494 struct sk_buff *frag_iter;
1495 int i, copy;
1496
1497 if (offset > (int)skb->len - len)
1498 goto fault;
1499
1500 /* Copy header. */
1501 if ((copy = start - offset) > 0) {
1502 if (copy > len)
1503 copy = len;
1504 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1505 if ((len -= copy) == 0)
1506 return 0;
1507 offset += copy;
1508 to += copy;
1509 }
1510
1511 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1512 int end;
1513 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1514
1515 WARN_ON(start > offset + len);
1516
1517 end = start + skb_frag_size(f);
1518 if ((copy = end - offset) > 0) {
1519 u8 *vaddr;
1520
1521 if (copy > len)
1522 copy = len;
1523
1524 vaddr = kmap_atomic(skb_frag_page(f));
1525 memcpy(to,
1526 vaddr + f->page_offset + offset - start,
1527 copy);
1528 kunmap_atomic(vaddr);
1529
1530 if ((len -= copy) == 0)
1531 return 0;
1532 offset += copy;
1533 to += copy;
1534 }
1535 start = end;
1536 }
1537
1538 skb_walk_frags(skb, frag_iter) {
1539 int end;
1540
1541 WARN_ON(start > offset + len);
1542
1543 end = start + frag_iter->len;
1544 if ((copy = end - offset) > 0) {
1545 if (copy > len)
1546 copy = len;
1547 if (skb_copy_bits(frag_iter, offset - start, to, copy))
1548 goto fault;
1549 if ((len -= copy) == 0)
1550 return 0;
1551 offset += copy;
1552 to += copy;
1553 }
1554 start = end;
1555 }
1556
1557 if (!len)
1558 return 0;
1559
1560fault:
1561 return -EFAULT;
1562}
1563EXPORT_SYMBOL(skb_copy_bits);
1564
1565/*
1566 * Callback from splice_to_pipe(), if we need to release some pages
1567 * at the end of the spd in case we error'ed out in filling the pipe.
1568 */
1569static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1570{
1571 put_page(spd->pages[i]);
1572}
1573
1574static struct page *linear_to_page(struct page *page, unsigned int *len,
1575 unsigned int *offset,
1576 struct sk_buff *skb, struct sock *sk)
1577{
1578 struct page *p = sk->sk_sndmsg_page;
1579 unsigned int off;
1580
1581 if (!p) {
1582new_page:
1583 p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0);
1584 if (!p)
1585 return NULL;
1586
1587 off = sk->sk_sndmsg_off = 0;
1588 /* hold one ref to this page until it's full */
1589 } else {
1590 unsigned int mlen;
1591
1592 /* If we are the only user of the page, we can reset offset */
1593 if (page_count(p) == 1)
1594 sk->sk_sndmsg_off = 0;
1595 off = sk->sk_sndmsg_off;
1596 mlen = PAGE_SIZE - off;
1597 if (mlen < 64 && mlen < *len) {
1598 put_page(p);
1599 goto new_page;
1600 }
1601
1602 *len = min_t(unsigned int, *len, mlen);
1603 }
1604
1605 memcpy(page_address(p) + off, page_address(page) + *offset, *len);
1606 sk->sk_sndmsg_off += *len;
1607 *offset = off;
1608
1609 return p;
1610}
1611
1612static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
1613 struct page *page,
1614 unsigned int offset)
1615{
1616 return spd->nr_pages &&
1617 spd->pages[spd->nr_pages - 1] == page &&
1618 (spd->partial[spd->nr_pages - 1].offset +
1619 spd->partial[spd->nr_pages - 1].len == offset);
1620}
1621
1622/*
1623 * Fill page/offset/length into spd, if it can hold more pages.
1624 */
1625static bool spd_fill_page(struct splice_pipe_desc *spd,
1626 struct pipe_inode_info *pipe, struct page *page,
1627 unsigned int *len, unsigned int offset,
1628 struct sk_buff *skb, bool linear,
1629 struct sock *sk)
1630{
1631 if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
1632 return true;
1633
1634 if (linear) {
1635 page = linear_to_page(page, len, &offset, skb, sk);
1636 if (!page)
1637 return true;
1638 }
1639 if (spd_can_coalesce(spd, page, offset)) {
1640 spd->partial[spd->nr_pages - 1].len += *len;
1641 return false;
1642 }
1643 get_page(page);
1644 spd->pages[spd->nr_pages] = page;
1645 spd->partial[spd->nr_pages].len = *len;
1646 spd->partial[spd->nr_pages].offset = offset;
1647 spd->nr_pages++;
1648
1649 return false;
1650}
1651
1652static inline void __segment_seek(struct page **page, unsigned int *poff,
1653 unsigned int *plen, unsigned int off)
1654{
1655 unsigned long n;
1656
1657 *poff += off;
1658 n = *poff / PAGE_SIZE;
1659 if (n)
1660 *page = nth_page(*page, n);
1661
1662 *poff = *poff % PAGE_SIZE;
1663 *plen -= off;
1664}
1665
1666static bool __splice_segment(struct page *page, unsigned int poff,
1667 unsigned int plen, unsigned int *off,
1668 unsigned int *len, struct sk_buff *skb,
1669 struct splice_pipe_desc *spd, bool linear,
1670 struct sock *sk,
1671 struct pipe_inode_info *pipe)
1672{
1673 if (!*len)
1674 return true;
1675
1676 /* skip this segment if already processed */
1677 if (*off >= plen) {
1678 *off -= plen;
1679 return false;
1680 }
1681
1682 /* ignore any bits we already processed */
1683 if (*off) {
1684 __segment_seek(&page, &poff, &plen, *off);
1685 *off = 0;
1686 }
1687
1688 do {
1689 unsigned int flen = min(*len, plen);
1690
1691 /* the linear region may spread across several pages */
1692 flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
1693
1694 if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
1695 return true;
1696
1697 __segment_seek(&page, &poff, &plen, flen);
1698 *len -= flen;
1699
1700 } while (*len && plen);
1701
1702 return false;
1703}
1704
1705/*
1706 * Map linear and fragment data from the skb to spd. It reports true if the
1707 * pipe is full or if we already spliced the requested length.
1708 */
1709static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
1710 unsigned int *offset, unsigned int *len,
1711 struct splice_pipe_desc *spd, struct sock *sk)
1712{
1713 int seg;
1714
1715 /* map the linear part :
1716 * If skb->head_frag is set, this 'linear' part is backed by a
1717 * fragment, and if the head is not shared with any clones then
1718 * we can avoid a copy since we own the head portion of this page.
1719 */
1720 if (__splice_segment(virt_to_page(skb->data),
1721 (unsigned long) skb->data & (PAGE_SIZE - 1),
1722 skb_headlen(skb),
1723 offset, len, skb, spd,
1724 skb_head_is_locked(skb),
1725 sk, pipe))
1726 return true;
1727
1728 /*
1729 * then map the fragments
1730 */
1731 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1732 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1733
1734 if (__splice_segment(skb_frag_page(f),
1735 f->page_offset, skb_frag_size(f),
1736 offset, len, skb, spd, false, sk, pipe))
1737 return true;
1738 }
1739
1740 return false;
1741}
1742
1743/*
1744 * Map data from the skb to a pipe. Should handle both the linear part,
1745 * the fragments, and the frag list. It does NOT handle frag lists within
1746 * the frag list, if such a thing exists. We'd probably need to recurse to
1747 * handle that cleanly.
1748 */
1749int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
1750 struct pipe_inode_info *pipe, unsigned int tlen,
1751 unsigned int flags)
1752{
1753 struct partial_page partial[MAX_SKB_FRAGS];
1754 struct page *pages[MAX_SKB_FRAGS];
1755 struct splice_pipe_desc spd = {
1756 .pages = pages,
1757 .partial = partial,
1758 .nr_pages_max = MAX_SKB_FRAGS,
1759 .flags = flags,
1760 .ops = &sock_pipe_buf_ops,
1761 .spd_release = sock_spd_release,
1762 };
1763 struct sk_buff *frag_iter;
1764 struct sock *sk = skb->sk;
1765 int ret = 0;
1766
1767 /*
1768 * __skb_splice_bits() only fails if the output has no room left,
1769 * so no point in going over the frag_list for the error case.
1770 */
1771 if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
1772 goto done;
1773 else if (!tlen)
1774 goto done;
1775
1776 /*
1777 * now see if we have a frag_list to map
1778 */
1779 skb_walk_frags(skb, frag_iter) {
1780 if (!tlen)
1781 break;
1782 if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
1783 break;
1784 }
1785
1786done:
1787 if (spd.nr_pages) {
1788 /*
1789 * Drop the socket lock, otherwise we have reverse
1790 * locking dependencies between sk_lock and i_mutex
1791 * here as compared to sendfile(). We enter here
1792 * with the socket lock held, and splice_to_pipe() will
1793 * grab the pipe inode lock. For sendfile() emulation,
1794 * we call into ->sendpage() with the i_mutex lock held
1795 * and networking will grab the socket lock.
1796 */
1797 release_sock(sk);
1798 ret = splice_to_pipe(pipe, &spd);
1799 lock_sock(sk);
1800 }
1801
1802 return ret;
1803}
1804
1805/**
1806 * skb_store_bits - store bits from kernel buffer to skb
1807 * @skb: destination buffer
1808 * @offset: offset in destination
1809 * @from: source buffer
1810 * @len: number of bytes to copy
1811 *
1812 * Copy the specified number of bytes from the source buffer to the
1813 * destination skb. This function handles all the messy bits of
1814 * traversing fragment lists and such.
1815 */
1816
1817int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1818{
1819 int start = skb_headlen(skb);
1820 struct sk_buff *frag_iter;
1821 int i, copy;
1822
1823 if (offset > (int)skb->len - len)
1824 goto fault;
1825
1826 if ((copy = start - offset) > 0) {
1827 if (copy > len)
1828 copy = len;
1829 skb_copy_to_linear_data_offset(skb, offset, from, copy);
1830 if ((len -= copy) == 0)
1831 return 0;
1832 offset += copy;
1833 from += copy;
1834 }
1835
1836 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1837 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1838 int end;
1839
1840 WARN_ON(start > offset + len);
1841
1842 end = start + skb_frag_size(frag);
1843 if ((copy = end - offset) > 0) {
1844 u8 *vaddr;
1845
1846 if (copy > len)
1847 copy = len;
1848
1849 vaddr = kmap_atomic(skb_frag_page(frag));
1850 memcpy(vaddr + frag->page_offset + offset - start,
1851 from, copy);
1852 kunmap_atomic(vaddr);
1853
1854 if ((len -= copy) == 0)
1855 return 0;
1856 offset += copy;
1857 from += copy;
1858 }
1859 start = end;
1860 }
1861
1862 skb_walk_frags(skb, frag_iter) {
1863 int end;
1864
1865 WARN_ON(start > offset + len);
1866
1867 end = start + frag_iter->len;
1868 if ((copy = end - offset) > 0) {
1869 if (copy > len)
1870 copy = len;
1871 if (skb_store_bits(frag_iter, offset - start,
1872 from, copy))
1873 goto fault;
1874 if ((len -= copy) == 0)
1875 return 0;
1876 offset += copy;
1877 from += copy;
1878 }
1879 start = end;
1880 }
1881 if (!len)
1882 return 0;
1883
1884fault:
1885 return -EFAULT;
1886}
1887EXPORT_SYMBOL(skb_store_bits);
1888
1889/* Checksum skb data. */
1890
1891__wsum skb_checksum(const struct sk_buff *skb, int offset,
1892 int len, __wsum csum)
1893{
1894 int start = skb_headlen(skb);
1895 int i, copy = start - offset;
1896 struct sk_buff *frag_iter;
1897 int pos = 0;
1898
1899 /* Checksum header. */
1900 if (copy > 0) {
1901 if (copy > len)
1902 copy = len;
1903 csum = csum_partial(skb->data + offset, copy, csum);
1904 if ((len -= copy) == 0)
1905 return csum;
1906 offset += copy;
1907 pos = copy;
1908 }
1909
1910 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1911 int end;
1912 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1913
1914 WARN_ON(start > offset + len);
1915
1916 end = start + skb_frag_size(frag);
1917 if ((copy = end - offset) > 0) {
1918 __wsum csum2;
1919 u8 *vaddr;
1920
1921 if (copy > len)
1922 copy = len;
1923 vaddr = kmap_atomic(skb_frag_page(frag));
1924 csum2 = csum_partial(vaddr + frag->page_offset +
1925 offset - start, copy, 0);
1926 kunmap_atomic(vaddr);
1927 csum = csum_block_add(csum, csum2, pos);
1928 if (!(len -= copy))
1929 return csum;
1930 offset += copy;
1931 pos += copy;
1932 }
1933 start = end;
1934 }
1935
1936 skb_walk_frags(skb, frag_iter) {
1937 int end;
1938
1939 WARN_ON(start > offset + len);
1940
1941 end = start + frag_iter->len;
1942 if ((copy = end - offset) > 0) {
1943 __wsum csum2;
1944 if (copy > len)
1945 copy = len;
1946 csum2 = skb_checksum(frag_iter, offset - start,
1947 copy, 0);
1948 csum = csum_block_add(csum, csum2, pos);
1949 if ((len -= copy) == 0)
1950 return csum;
1951 offset += copy;
1952 pos += copy;
1953 }
1954 start = end;
1955 }
1956 BUG_ON(len);
1957
1958 return csum;
1959}
1960EXPORT_SYMBOL(skb_checksum);
1961
1962/* Both of above in one bottle. */
1963
1964__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1965 u8 *to, int len, __wsum csum)
1966{
1967 int start = skb_headlen(skb);
1968 int i, copy = start - offset;
1969 struct sk_buff *frag_iter;
1970 int pos = 0;
1971
1972 /* Copy header. */
1973 if (copy > 0) {
1974 if (copy > len)
1975 copy = len;
1976 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1977 copy, csum);
1978 if ((len -= copy) == 0)
1979 return csum;
1980 offset += copy;
1981 to += copy;
1982 pos = copy;
1983 }
1984
1985 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1986 int end;
1987
1988 WARN_ON(start > offset + len);
1989
1990 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
1991 if ((copy = end - offset) > 0) {
1992 __wsum csum2;
1993 u8 *vaddr;
1994 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1995
1996 if (copy > len)
1997 copy = len;
1998 vaddr = kmap_atomic(skb_frag_page(frag));
1999 csum2 = csum_partial_copy_nocheck(vaddr +
2000 frag->page_offset +
2001 offset - start, to,
2002 copy, 0);
2003 kunmap_atomic(vaddr);
2004 csum = csum_block_add(csum, csum2, pos);
2005 if (!(len -= copy))
2006 return csum;
2007 offset += copy;
2008 to += copy;
2009 pos += copy;
2010 }
2011 start = end;
2012 }
2013
2014 skb_walk_frags(skb, frag_iter) {
2015 __wsum csum2;
2016 int end;
2017
2018 WARN_ON(start > offset + len);
2019
2020 end = start + frag_iter->len;
2021 if ((copy = end - offset) > 0) {
2022 if (copy > len)
2023 copy = len;
2024 csum2 = skb_copy_and_csum_bits(frag_iter,
2025 offset - start,
2026 to, copy, 0);
2027 csum = csum_block_add(csum, csum2, pos);
2028 if ((len -= copy) == 0)
2029 return csum;
2030 offset += copy;
2031 to += copy;
2032 pos += copy;
2033 }
2034 start = end;
2035 }
2036 BUG_ON(len);
2037 return csum;
2038}
2039EXPORT_SYMBOL(skb_copy_and_csum_bits);
2040
2041void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
2042{
2043 __wsum csum;
2044 long csstart;
2045
2046 if (skb->ip_summed == CHECKSUM_PARTIAL)
2047 csstart = skb_checksum_start_offset(skb);
2048 else
2049 csstart = skb_headlen(skb);
2050
2051 BUG_ON(csstart > skb_headlen(skb));
2052
2053 skb_copy_from_linear_data(skb, to, csstart);
2054
2055 csum = 0;
2056 if (csstart != skb->len)
2057 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
2058 skb->len - csstart, 0);
2059
2060 if (skb->ip_summed == CHECKSUM_PARTIAL) {
2061 long csstuff = csstart + skb->csum_offset;
2062
2063 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
2064 }
2065}
2066EXPORT_SYMBOL(skb_copy_and_csum_dev);
2067
2068/**
2069 * skb_dequeue - remove from the head of the queue
2070 * @list: list to dequeue from
2071 *
2072 * Remove the head of the list. The list lock is taken so the function
2073 * may be used safely with other locking list functions. The head item is
2074 * returned or %NULL if the list is empty.
2075 */
2076
2077struct sk_buff *skb_dequeue(struct sk_buff_head *list)
2078{
2079 unsigned long flags;
2080 struct sk_buff *result;
2081
2082 spin_lock_irqsave(&list->lock, flags);
2083 result = __skb_dequeue(list);
2084 spin_unlock_irqrestore(&list->lock, flags);
2085 return result;
2086}
2087EXPORT_SYMBOL(skb_dequeue);
2088
2089/**
2090 * skb_dequeue_tail - remove from the tail of the queue
2091 * @list: list to dequeue from
2092 *
2093 * Remove the tail of the list. The list lock is taken so the function
2094 * may be used safely with other locking list functions. The tail item is
2095 * returned or %NULL if the list is empty.
2096 */
2097struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
2098{
2099 unsigned long flags;
2100 struct sk_buff *result;
2101
2102 spin_lock_irqsave(&list->lock, flags);
2103 result = __skb_dequeue_tail(list);
2104 spin_unlock_irqrestore(&list->lock, flags);
2105 return result;
2106}
2107EXPORT_SYMBOL(skb_dequeue_tail);
2108
2109/**
2110 * skb_queue_purge - empty a list
2111 * @list: list to empty
2112 *
2113 * Delete all buffers on an &sk_buff list. Each buffer is removed from
2114 * the list and one reference dropped. This function takes the list
2115 * lock and is atomic with respect to other list locking functions.
2116 */
2117void skb_queue_purge(struct sk_buff_head *list)
2118{
2119 struct sk_buff *skb;
2120 while ((skb = skb_dequeue(list)) != NULL)
2121 kfree_skb(skb);
2122}
2123EXPORT_SYMBOL(skb_queue_purge);
2124
2125/**
2126 * skb_queue_head - queue a buffer at the list head
2127 * @list: list to use
2128 * @newsk: buffer to queue
2129 *
2130 * Queue a buffer at the start of the list. This function takes the
2131 * list lock and can be used safely with other locking &sk_buff functions
2132 * safely.
2133 *
2134 * A buffer cannot be placed on two lists at the same time.
2135 */
2136void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
2137{
2138 unsigned long flags;
2139
2140 spin_lock_irqsave(&list->lock, flags);
2141 __skb_queue_head(list, newsk);
2142 spin_unlock_irqrestore(&list->lock, flags);
2143}
2144EXPORT_SYMBOL(skb_queue_head);
2145
2146/**
2147 * skb_queue_tail - queue a buffer at the list tail
2148 * @list: list to use
2149 * @newsk: buffer to queue
2150 *
2151 * Queue a buffer at the tail of the list. This function takes the
2152 * list lock and can be used safely with other locking &sk_buff functions
2153 * safely.
2154 *
2155 * A buffer cannot be placed on two lists at the same time.
2156 */
2157void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
2158{
2159 unsigned long flags;
2160
2161 spin_lock_irqsave(&list->lock, flags);
2162 __skb_queue_tail(list, newsk);
2163 spin_unlock_irqrestore(&list->lock, flags);
2164}
2165EXPORT_SYMBOL(skb_queue_tail);
2166
2167/**
2168 * skb_unlink - remove a buffer from a list
2169 * @skb: buffer to remove
2170 * @list: list to use
2171 *
2172 * Remove a packet from a list. The list locks are taken and this
2173 * function is atomic with respect to other list locked calls
2174 *
2175 * You must know what list the SKB is on.
2176 */
2177void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
2178{
2179 unsigned long flags;
2180
2181 spin_lock_irqsave(&list->lock, flags);
2182 __skb_unlink(skb, list);
2183 spin_unlock_irqrestore(&list->lock, flags);
2184}
2185EXPORT_SYMBOL(skb_unlink);
2186
2187/**
2188 * skb_append - append a buffer
2189 * @old: buffer to insert after
2190 * @newsk: buffer to insert
2191 * @list: list to use
2192 *
2193 * Place a packet after a given packet in a list. The list locks are taken
2194 * and this function is atomic with respect to other list locked calls.
2195 * A buffer cannot be placed on two lists at the same time.
2196 */
2197void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2198{
2199 unsigned long flags;
2200
2201 spin_lock_irqsave(&list->lock, flags);
2202 __skb_queue_after(list, old, newsk);
2203 spin_unlock_irqrestore(&list->lock, flags);
2204}
2205EXPORT_SYMBOL(skb_append);
2206
2207/**
2208 * skb_insert - insert a buffer
2209 * @old: buffer to insert before
2210 * @newsk: buffer to insert
2211 * @list: list to use
2212 *
2213 * Place a packet before a given packet in a list. The list locks are
2214 * taken and this function is atomic with respect to other list locked
2215 * calls.
2216 *
2217 * A buffer cannot be placed on two lists at the same time.
2218 */
2219void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2220{
2221 unsigned long flags;
2222
2223 spin_lock_irqsave(&list->lock, flags);
2224 __skb_insert(newsk, old->prev, old, list);
2225 spin_unlock_irqrestore(&list->lock, flags);
2226}
2227EXPORT_SYMBOL(skb_insert);
2228
2229static inline void skb_split_inside_header(struct sk_buff *skb,
2230 struct sk_buff* skb1,
2231 const u32 len, const int pos)
2232{
2233 int i;
2234
2235 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2236 pos - len);
2237 /* And move data appendix as is. */
2238 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2239 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2240
2241 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2242 skb_shinfo(skb)->nr_frags = 0;
2243 skb1->data_len = skb->data_len;
2244 skb1->len += skb1->data_len;
2245 skb->data_len = 0;
2246 skb->len = len;
2247 skb_set_tail_pointer(skb, len);
2248}
2249
2250static inline void skb_split_no_header(struct sk_buff *skb,
2251 struct sk_buff* skb1,
2252 const u32 len, int pos)
2253{
2254 int i, k = 0;
2255 const int nfrags = skb_shinfo(skb)->nr_frags;
2256
2257 skb_shinfo(skb)->nr_frags = 0;
2258 skb1->len = skb1->data_len = skb->len - len;
2259 skb->len = len;
2260 skb->data_len = len - pos;
2261
2262 for (i = 0; i < nfrags; i++) {
2263 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2264
2265 if (pos + size > len) {
2266 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2267
2268 if (pos < len) {
2269 /* Split frag.
2270 * We have two variants in this case:
2271 * 1. Move all the frag to the second
2272 * part, if it is possible. F.e.
2273 * this approach is mandatory for TUX,
2274 * where splitting is expensive.
2275 * 2. Split is accurately. We make this.
2276 */
2277 skb_frag_ref(skb, i);
2278 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2279 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
2280 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
2281 skb_shinfo(skb)->nr_frags++;
2282 }
2283 k++;
2284 } else
2285 skb_shinfo(skb)->nr_frags++;
2286 pos += size;
2287 }
2288 skb_shinfo(skb1)->nr_frags = k;
2289}
2290
2291/**
2292 * skb_split - Split fragmented skb to two parts at length len.
2293 * @skb: the buffer to split
2294 * @skb1: the buffer to receive the second part
2295 * @len: new length for skb
2296 */
2297void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2298{
2299 int pos = skb_headlen(skb);
2300
2301 if (len < pos) /* Split line is inside header. */
2302 skb_split_inside_header(skb, skb1, len, pos);
2303 else /* Second chunk has no header, nothing to copy. */
2304 skb_split_no_header(skb, skb1, len, pos);
2305}
2306EXPORT_SYMBOL(skb_split);
2307
2308/* Shifting from/to a cloned skb is a no-go.
2309 *
2310 * Caller cannot keep skb_shinfo related pointers past calling here!
2311 */
2312static int skb_prepare_for_shift(struct sk_buff *skb)
2313{
2314 return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2315}
2316
2317/**
2318 * skb_shift - Shifts paged data partially from skb to another
2319 * @tgt: buffer into which tail data gets added
2320 * @skb: buffer from which the paged data comes from
2321 * @shiftlen: shift up to this many bytes
2322 *
2323 * Attempts to shift up to shiftlen worth of bytes, which may be less than
2324 * the length of the skb, from skb to tgt. Returns number bytes shifted.
2325 * It's up to caller to free skb if everything was shifted.
2326 *
2327 * If @tgt runs out of frags, the whole operation is aborted.
2328 *
2329 * Skb cannot include anything else but paged data while tgt is allowed
2330 * to have non-paged data as well.
2331 *
2332 * TODO: full sized shift could be optimized but that would need
2333 * specialized skb free'er to handle frags without up-to-date nr_frags.
2334 */
2335int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2336{
2337 int from, to, merge, todo;
2338 struct skb_frag_struct *fragfrom, *fragto;
2339
2340 BUG_ON(shiftlen > skb->len);
2341 BUG_ON(skb_headlen(skb)); /* Would corrupt stream */
2342
2343 todo = shiftlen;
2344 from = 0;
2345 to = skb_shinfo(tgt)->nr_frags;
2346 fragfrom = &skb_shinfo(skb)->frags[from];
2347
2348 /* Actual merge is delayed until the point when we know we can
2349 * commit all, so that we don't have to undo partial changes
2350 */
2351 if (!to ||
2352 !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
2353 fragfrom->page_offset)) {
2354 merge = -1;
2355 } else {
2356 merge = to - 1;
2357
2358 todo -= skb_frag_size(fragfrom);
2359 if (todo < 0) {
2360 if (skb_prepare_for_shift(skb) ||
2361 skb_prepare_for_shift(tgt))
2362 return 0;
2363
2364 /* All previous frag pointers might be stale! */
2365 fragfrom = &skb_shinfo(skb)->frags[from];
2366 fragto = &skb_shinfo(tgt)->frags[merge];
2367
2368 skb_frag_size_add(fragto, shiftlen);
2369 skb_frag_size_sub(fragfrom, shiftlen);
2370 fragfrom->page_offset += shiftlen;
2371
2372 goto onlymerged;
2373 }
2374
2375 from++;
2376 }
2377
2378 /* Skip full, not-fitting skb to avoid expensive operations */
2379 if ((shiftlen == skb->len) &&
2380 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2381 return 0;
2382
2383 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2384 return 0;
2385
2386 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2387 if (to == MAX_SKB_FRAGS)
2388 return 0;
2389
2390 fragfrom = &skb_shinfo(skb)->frags[from];
2391 fragto = &skb_shinfo(tgt)->frags[to];
2392
2393 if (todo >= skb_frag_size(fragfrom)) {
2394 *fragto = *fragfrom;
2395 todo -= skb_frag_size(fragfrom);
2396 from++;
2397 to++;
2398
2399 } else {
2400 __skb_frag_ref(fragfrom);
2401 fragto->page = fragfrom->page;
2402 fragto->page_offset = fragfrom->page_offset;
2403 skb_frag_size_set(fragto, todo);
2404
2405 fragfrom->page_offset += todo;
2406 skb_frag_size_sub(fragfrom, todo);
2407 todo = 0;
2408
2409 to++;
2410 break;
2411 }
2412 }
2413
2414 /* Ready to "commit" this state change to tgt */
2415 skb_shinfo(tgt)->nr_frags = to;
2416
2417 if (merge >= 0) {
2418 fragfrom = &skb_shinfo(skb)->frags[0];
2419 fragto = &skb_shinfo(tgt)->frags[merge];
2420
2421 skb_frag_size_add(fragto, skb_frag_size(fragfrom));
2422 __skb_frag_unref(fragfrom);
2423 }
2424
2425 /* Reposition in the original skb */
2426 to = 0;
2427 while (from < skb_shinfo(skb)->nr_frags)
2428 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2429 skb_shinfo(skb)->nr_frags = to;
2430
2431 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2432
2433onlymerged:
2434 /* Most likely the tgt won't ever need its checksum anymore, skb on
2435 * the other hand might need it if it needs to be resent
2436 */
2437 tgt->ip_summed = CHECKSUM_PARTIAL;
2438 skb->ip_summed = CHECKSUM_PARTIAL;
2439
2440 /* Yak, is it really working this way? Some helper please? */
2441 skb->len -= shiftlen;
2442 skb->data_len -= shiftlen;
2443 skb->truesize -= shiftlen;
2444 tgt->len += shiftlen;
2445 tgt->data_len += shiftlen;
2446 tgt->truesize += shiftlen;
2447
2448 return shiftlen;
2449}
2450
2451/**
2452 * skb_prepare_seq_read - Prepare a sequential read of skb data
2453 * @skb: the buffer to read
2454 * @from: lower offset of data to be read
2455 * @to: upper offset of data to be read
2456 * @st: state variable
2457 *
2458 * Initializes the specified state variable. Must be called before
2459 * invoking skb_seq_read() for the first time.
2460 */
2461void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2462 unsigned int to, struct skb_seq_state *st)
2463{
2464 st->lower_offset = from;
2465 st->upper_offset = to;
2466 st->root_skb = st->cur_skb = skb;
2467 st->frag_idx = st->stepped_offset = 0;
2468 st->frag_data = NULL;
2469}
2470EXPORT_SYMBOL(skb_prepare_seq_read);
2471
2472/**
2473 * skb_seq_read - Sequentially read skb data
2474 * @consumed: number of bytes consumed by the caller so far
2475 * @data: destination pointer for data to be returned
2476 * @st: state variable
2477 *
2478 * Reads a block of skb data at &consumed relative to the
2479 * lower offset specified to skb_prepare_seq_read(). Assigns
2480 * the head of the data block to &data and returns the length
2481 * of the block or 0 if the end of the skb data or the upper
2482 * offset has been reached.
2483 *
2484 * The caller is not required to consume all of the data
2485 * returned, i.e. &consumed is typically set to the number
2486 * of bytes already consumed and the next call to
2487 * skb_seq_read() will return the remaining part of the block.
2488 *
2489 * Note 1: The size of each block of data returned can be arbitrary,
2490 * this limitation is the cost for zerocopy seqeuental
2491 * reads of potentially non linear data.
2492 *
2493 * Note 2: Fragment lists within fragments are not implemented
2494 * at the moment, state->root_skb could be replaced with
2495 * a stack for this purpose.
2496 */
2497unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2498 struct skb_seq_state *st)
2499{
2500 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2501 skb_frag_t *frag;
2502
2503 if (unlikely(abs_offset >= st->upper_offset))
2504 return 0;
2505
2506next_skb:
2507 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2508
2509 if (abs_offset < block_limit && !st->frag_data) {
2510 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2511 return block_limit - abs_offset;
2512 }
2513
2514 if (st->frag_idx == 0 && !st->frag_data)
2515 st->stepped_offset += skb_headlen(st->cur_skb);
2516
2517 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2518 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2519 block_limit = skb_frag_size(frag) + st->stepped_offset;
2520
2521 if (abs_offset < block_limit) {
2522 if (!st->frag_data)
2523 st->frag_data = kmap_atomic(skb_frag_page(frag));
2524
2525 *data = (u8 *) st->frag_data + frag->page_offset +
2526 (abs_offset - st->stepped_offset);
2527
2528 return block_limit - abs_offset;
2529 }
2530
2531 if (st->frag_data) {
2532 kunmap_atomic(st->frag_data);
2533 st->frag_data = NULL;
2534 }
2535
2536 st->frag_idx++;
2537 st->stepped_offset += skb_frag_size(frag);
2538 }
2539
2540 if (st->frag_data) {
2541 kunmap_atomic(st->frag_data);
2542 st->frag_data = NULL;
2543 }
2544
2545 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
2546 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2547 st->frag_idx = 0;
2548 goto next_skb;
2549 } else if (st->cur_skb->next) {
2550 st->cur_skb = st->cur_skb->next;
2551 st->frag_idx = 0;
2552 goto next_skb;
2553 }
2554
2555 return 0;
2556}
2557EXPORT_SYMBOL(skb_seq_read);
2558
2559/**
2560 * skb_abort_seq_read - Abort a sequential read of skb data
2561 * @st: state variable
2562 *
2563 * Must be called if skb_seq_read() was not called until it
2564 * returned 0.
2565 */
2566void skb_abort_seq_read(struct skb_seq_state *st)
2567{
2568 if (st->frag_data)
2569 kunmap_atomic(st->frag_data);
2570}
2571EXPORT_SYMBOL(skb_abort_seq_read);
2572
2573#define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
2574
2575static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2576 struct ts_config *conf,
2577 struct ts_state *state)
2578{
2579 return skb_seq_read(offset, text, TS_SKB_CB(state));
2580}
2581
2582static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2583{
2584 skb_abort_seq_read(TS_SKB_CB(state));
2585}
2586
2587/**
2588 * skb_find_text - Find a text pattern in skb data
2589 * @skb: the buffer to look in
2590 * @from: search offset
2591 * @to: search limit
2592 * @config: textsearch configuration
2593 * @state: uninitialized textsearch state variable
2594 *
2595 * Finds a pattern in the skb data according to the specified
2596 * textsearch configuration. Use textsearch_next() to retrieve
2597 * subsequent occurrences of the pattern. Returns the offset
2598 * to the first occurrence or UINT_MAX if no match was found.
2599 */
2600unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2601 unsigned int to, struct ts_config *config,
2602 struct ts_state *state)
2603{
2604 unsigned int ret;
2605
2606 config->get_next_block = skb_ts_get_next_block;
2607 config->finish = skb_ts_finish;
2608
2609 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
2610
2611 ret = textsearch_find(config, state);
2612 return (ret <= to - from ? ret : UINT_MAX);
2613}
2614EXPORT_SYMBOL(skb_find_text);
2615
2616/**
2617 * skb_append_datato_frags: - append the user data to a skb
2618 * @sk: sock structure
2619 * @skb: skb structure to be appened with user data.
2620 * @getfrag: call back function to be used for getting the user data
2621 * @from: pointer to user message iov
2622 * @length: length of the iov message
2623 *
2624 * Description: This procedure append the user data in the fragment part
2625 * of the skb if any page alloc fails user this procedure returns -ENOMEM
2626 */
2627int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2628 int (*getfrag)(void *from, char *to, int offset,
2629 int len, int odd, struct sk_buff *skb),
2630 void *from, int length)
2631{
2632 int frg_cnt = 0;
2633 skb_frag_t *frag = NULL;
2634 struct page *page = NULL;
2635 int copy, left;
2636 int offset = 0;
2637 int ret;
2638
2639 do {
2640 /* Return error if we don't have space for new frag */
2641 frg_cnt = skb_shinfo(skb)->nr_frags;
2642 if (frg_cnt >= MAX_SKB_FRAGS)
2643 return -EFAULT;
2644
2645 /* allocate a new page for next frag */
2646 page = alloc_pages(sk->sk_allocation, 0);
2647
2648 /* If alloc_page fails just return failure and caller will
2649 * free previous allocated pages by doing kfree_skb()
2650 */
2651 if (page == NULL)
2652 return -ENOMEM;
2653
2654 /* initialize the next frag */
2655 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
2656 skb->truesize += PAGE_SIZE;
2657 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
2658
2659 /* get the new initialized frag */
2660 frg_cnt = skb_shinfo(skb)->nr_frags;
2661 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
2662
2663 /* copy the user data to page */
2664 left = PAGE_SIZE - frag->page_offset;
2665 copy = (length > left)? left : length;
2666
2667 ret = getfrag(from, skb_frag_address(frag) + skb_frag_size(frag),
2668 offset, copy, 0, skb);
2669 if (ret < 0)
2670 return -EFAULT;
2671
2672 /* copy was successful so update the size parameters */
2673 skb_frag_size_add(frag, copy);
2674 skb->len += copy;
2675 skb->data_len += copy;
2676 offset += copy;
2677 length -= copy;
2678
2679 } while (length > 0);
2680
2681 return 0;
2682}
2683EXPORT_SYMBOL(skb_append_datato_frags);
2684
2685/**
2686 * skb_pull_rcsum - pull skb and update receive checksum
2687 * @skb: buffer to update
2688 * @len: length of data pulled
2689 *
2690 * This function performs an skb_pull on the packet and updates
2691 * the CHECKSUM_COMPLETE checksum. It should be used on
2692 * receive path processing instead of skb_pull unless you know
2693 * that the checksum difference is zero (e.g., a valid IP header)
2694 * or you are setting ip_summed to CHECKSUM_NONE.
2695 */
2696unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
2697{
2698 BUG_ON(len > skb->len);
2699 skb->len -= len;
2700 BUG_ON(skb->len < skb->data_len);
2701 skb_postpull_rcsum(skb, skb->data, len);
2702 return skb->data += len;
2703}
2704EXPORT_SYMBOL_GPL(skb_pull_rcsum);
2705
2706/**
2707 * skb_segment - Perform protocol segmentation on skb.
2708 * @skb: buffer to segment
2709 * @features: features for the output path (see dev->features)
2710 *
2711 * This function performs segmentation on the given skb. It returns
2712 * a pointer to the first in a list of new skbs for the segments.
2713 * In case of error it returns ERR_PTR(err).
2714 */
2715struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
2716{
2717 struct sk_buff *segs = NULL;
2718 struct sk_buff *tail = NULL;
2719 struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
2720 unsigned int mss = skb_shinfo(skb)->gso_size;
2721 unsigned int doffset = skb->data - skb_mac_header(skb);
2722 unsigned int offset = doffset;
2723 unsigned int headroom;
2724 unsigned int len;
2725 int sg = !!(features & NETIF_F_SG);
2726 int nfrags = skb_shinfo(skb)->nr_frags;
2727 int err = -ENOMEM;
2728 int i = 0;
2729 int pos;
2730
2731 __skb_push(skb, doffset);
2732 headroom = skb_headroom(skb);
2733 pos = skb_headlen(skb);
2734
2735 do {
2736 struct sk_buff *nskb;
2737 skb_frag_t *frag;
2738 int hsize;
2739 int size;
2740
2741 len = skb->len - offset;
2742 if (len > mss)
2743 len = mss;
2744
2745 hsize = skb_headlen(skb) - offset;
2746 if (hsize < 0)
2747 hsize = 0;
2748 if (hsize > len || !sg)
2749 hsize = len;
2750
2751 if (!hsize && i >= nfrags) {
2752 BUG_ON(fskb->len != len);
2753
2754 pos += len;
2755 nskb = skb_clone(fskb, GFP_ATOMIC);
2756 fskb = fskb->next;
2757
2758 if (unlikely(!nskb))
2759 goto err;
2760
2761 hsize = skb_end_offset(nskb);
2762 if (skb_cow_head(nskb, doffset + headroom)) {
2763 kfree_skb(nskb);
2764 goto err;
2765 }
2766
2767 nskb->truesize += skb_end_offset(nskb) - hsize;
2768 skb_release_head_state(nskb);
2769 __skb_push(nskb, doffset);
2770 } else {
2771 nskb = alloc_skb(hsize + doffset + headroom,
2772 GFP_ATOMIC);
2773
2774 if (unlikely(!nskb))
2775 goto err;
2776
2777 skb_reserve(nskb, headroom);
2778 __skb_put(nskb, doffset);
2779 }
2780
2781 if (segs)
2782 tail->next = nskb;
2783 else
2784 segs = nskb;
2785 tail = nskb;
2786
2787 __copy_skb_header(nskb, skb);
2788 nskb->mac_len = skb->mac_len;
2789
2790 /* nskb and skb might have different headroom */
2791 if (nskb->ip_summed == CHECKSUM_PARTIAL)
2792 nskb->csum_start += skb_headroom(nskb) - headroom;
2793
2794 skb_reset_mac_header(nskb);
2795 skb_set_network_header(nskb, skb->mac_len);
2796 nskb->transport_header = (nskb->network_header +
2797 skb_network_header_len(skb));
2798 skb_copy_from_linear_data(skb, nskb->data, doffset);
2799
2800 if (fskb != skb_shinfo(skb)->frag_list)
2801 continue;
2802
2803 if (!sg) {
2804 nskb->ip_summed = CHECKSUM_NONE;
2805 nskb->csum = skb_copy_and_csum_bits(skb, offset,
2806 skb_put(nskb, len),
2807 len, 0);
2808 continue;
2809 }
2810
2811 frag = skb_shinfo(nskb)->frags;
2812
2813 skb_copy_from_linear_data_offset(skb, offset,
2814 skb_put(nskb, hsize), hsize);
2815
2816 while (pos < offset + len && i < nfrags) {
2817 *frag = skb_shinfo(skb)->frags[i];
2818 __skb_frag_ref(frag);
2819 size = skb_frag_size(frag);
2820
2821 if (pos < offset) {
2822 frag->page_offset += offset - pos;
2823 skb_frag_size_sub(frag, offset - pos);
2824 }
2825
2826 skb_shinfo(nskb)->nr_frags++;
2827
2828 if (pos + size <= offset + len) {
2829 i++;
2830 pos += size;
2831 } else {
2832 skb_frag_size_sub(frag, pos + size - (offset + len));
2833 goto skip_fraglist;
2834 }
2835
2836 frag++;
2837 }
2838
2839 if (pos < offset + len) {
2840 struct sk_buff *fskb2 = fskb;
2841
2842 BUG_ON(pos + fskb->len != offset + len);
2843
2844 pos += fskb->len;
2845 fskb = fskb->next;
2846
2847 if (fskb2->next) {
2848 fskb2 = skb_clone(fskb2, GFP_ATOMIC);
2849 if (!fskb2)
2850 goto err;
2851 } else
2852 skb_get(fskb2);
2853
2854 SKB_FRAG_ASSERT(nskb);
2855 skb_shinfo(nskb)->frag_list = fskb2;
2856 }
2857
2858skip_fraglist:
2859 nskb->data_len = len - hsize;
2860 nskb->len += nskb->data_len;
2861 nskb->truesize += nskb->data_len;
2862 } while ((offset += len) < skb->len);
2863
2864 return segs;
2865
2866err:
2867 while ((skb = segs)) {
2868 segs = skb->next;
2869 kfree_skb(skb);
2870 }
2871 return ERR_PTR(err);
2872}
2873EXPORT_SYMBOL_GPL(skb_segment);
2874
2875int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2876{
2877 struct sk_buff *p = *head;
2878 struct sk_buff *nskb;
2879 struct skb_shared_info *skbinfo = skb_shinfo(skb);
2880 struct skb_shared_info *pinfo = skb_shinfo(p);
2881 unsigned int headroom;
2882 unsigned int len = skb_gro_len(skb);
2883 unsigned int offset = skb_gro_offset(skb);
2884 unsigned int headlen = skb_headlen(skb);
2885 unsigned int delta_truesize;
2886
2887 if (p->len + len >= 65536)
2888 return -E2BIG;
2889
2890 if (pinfo->frag_list)
2891 goto merge;
2892 else if (headlen <= offset) {
2893 skb_frag_t *frag;
2894 skb_frag_t *frag2;
2895 int i = skbinfo->nr_frags;
2896 int nr_frags = pinfo->nr_frags + i;
2897
2898 offset -= headlen;
2899
2900 if (nr_frags > MAX_SKB_FRAGS)
2901 return -E2BIG;
2902
2903 pinfo->nr_frags = nr_frags;
2904 skbinfo->nr_frags = 0;
2905
2906 frag = pinfo->frags + nr_frags;
2907 frag2 = skbinfo->frags + i;
2908 do {
2909 *--frag = *--frag2;
2910 } while (--i);
2911
2912 frag->page_offset += offset;
2913 skb_frag_size_sub(frag, offset);
2914
2915 /* all fragments truesize : remove (head size + sk_buff) */
2916 delta_truesize = skb->truesize -
2917 SKB_TRUESIZE(skb_end_offset(skb));
2918
2919 skb->truesize -= skb->data_len;
2920 skb->len -= skb->data_len;
2921 skb->data_len = 0;
2922
2923 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
2924 goto done;
2925 } else if (skb->head_frag) {
2926 int nr_frags = pinfo->nr_frags;
2927 skb_frag_t *frag = pinfo->frags + nr_frags;
2928 struct page *page = virt_to_head_page(skb->head);
2929 unsigned int first_size = headlen - offset;
2930 unsigned int first_offset;
2931
2932 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
2933 return -E2BIG;
2934
2935 first_offset = skb->data -
2936 (unsigned char *)page_address(page) +
2937 offset;
2938
2939 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
2940
2941 frag->page.p = page;
2942 frag->page_offset = first_offset;
2943 skb_frag_size_set(frag, first_size);
2944
2945 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
2946 /* We dont need to clear skbinfo->nr_frags here */
2947
2948 delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
2949 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
2950 goto done;
2951 } else if (skb_gro_len(p) != pinfo->gso_size)
2952 return -E2BIG;
2953
2954 headroom = skb_headroom(p);
2955 nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
2956 if (unlikely(!nskb))
2957 return -ENOMEM;
2958
2959 __copy_skb_header(nskb, p);
2960 nskb->mac_len = p->mac_len;
2961
2962 skb_reserve(nskb, headroom);
2963 __skb_put(nskb, skb_gro_offset(p));
2964
2965 skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
2966 skb_set_network_header(nskb, skb_network_offset(p));
2967 skb_set_transport_header(nskb, skb_transport_offset(p));
2968
2969 __skb_pull(p, skb_gro_offset(p));
2970 memcpy(skb_mac_header(nskb), skb_mac_header(p),
2971 p->data - skb_mac_header(p));
2972
2973 *NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p);
2974 skb_shinfo(nskb)->frag_list = p;
2975 skb_shinfo(nskb)->gso_size = pinfo->gso_size;
2976 pinfo->gso_size = 0;
2977 skb_header_release(p);
2978 nskb->prev = p;
2979
2980 nskb->data_len += p->len;
2981 nskb->truesize += p->truesize;
2982 nskb->len += p->len;
2983
2984 *head = nskb;
2985 nskb->next = p->next;
2986 p->next = NULL;
2987
2988 p = nskb;
2989
2990merge:
2991 delta_truesize = skb->truesize;
2992 if (offset > headlen) {
2993 unsigned int eat = offset - headlen;
2994
2995 skbinfo->frags[0].page_offset += eat;
2996 skb_frag_size_sub(&skbinfo->frags[0], eat);
2997 skb->data_len -= eat;
2998 skb->len -= eat;
2999 offset = headlen;
3000 }
3001
3002 __skb_pull(skb, offset);
3003
3004 p->prev->next = skb;
3005 p->prev = skb;
3006 skb_header_release(skb);
3007
3008done:
3009 NAPI_GRO_CB(p)->count++;
3010 p->data_len += len;
3011 p->truesize += delta_truesize;
3012 p->len += len;
3013
3014 NAPI_GRO_CB(skb)->same_flow = 1;
3015 return 0;
3016}
3017EXPORT_SYMBOL_GPL(skb_gro_receive);
3018
3019void __init skb_init(void)
3020{
3021 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
3022 sizeof(struct sk_buff),
3023 0,
3024 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
3025 NULL);
3026 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
3027 (2*sizeof(struct sk_buff)) +
3028 sizeof(atomic_t),
3029 0,
3030 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
3031 NULL);
3032}
3033
3034/**
3035 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
3036 * @skb: Socket buffer containing the buffers to be mapped
3037 * @sg: The scatter-gather list to map into
3038 * @offset: The offset into the buffer's contents to start mapping
3039 * @len: Length of buffer space to be mapped
3040 *
3041 * Fill the specified scatter-gather list with mappings/pointers into a
3042 * region of the buffer space attached to a socket buffer.
3043 */
3044static int
3045__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3046{
3047 int start = skb_headlen(skb);
3048 int i, copy = start - offset;
3049 struct sk_buff *frag_iter;
3050 int elt = 0;
3051
3052 if (copy > 0) {
3053 if (copy > len)
3054 copy = len;
3055 sg_set_buf(sg, skb->data + offset, copy);
3056 elt++;
3057 if ((len -= copy) == 0)
3058 return elt;
3059 offset += copy;
3060 }
3061
3062 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3063 int end;
3064
3065 WARN_ON(start > offset + len);
3066
3067 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3068 if ((copy = end - offset) > 0) {
3069 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3070
3071 if (copy > len)
3072 copy = len;
3073 sg_set_page(&sg[elt], skb_frag_page(frag), copy,
3074 frag->page_offset+offset-start);
3075 elt++;
3076 if (!(len -= copy))
3077 return elt;
3078 offset += copy;
3079 }
3080 start = end;
3081 }
3082
3083 skb_walk_frags(skb, frag_iter) {
3084 int end;
3085
3086 WARN_ON(start > offset + len);
3087
3088 end = start + frag_iter->len;
3089 if ((copy = end - offset) > 0) {
3090 if (copy > len)
3091 copy = len;
3092 elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
3093 copy);
3094 if ((len -= copy) == 0)
3095 return elt;
3096 offset += copy;
3097 }
3098 start = end;
3099 }
3100 BUG_ON(len);
3101 return elt;
3102}
3103
3104int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3105{
3106 int nsg = __skb_to_sgvec(skb, sg, offset, len);
3107
3108 sg_mark_end(&sg[nsg - 1]);
3109
3110 return nsg;
3111}
3112EXPORT_SYMBOL_GPL(skb_to_sgvec);
3113
3114/**
3115 * skb_cow_data - Check that a socket buffer's data buffers are writable
3116 * @skb: The socket buffer to check.
3117 * @tailbits: Amount of trailing space to be added
3118 * @trailer: Returned pointer to the skb where the @tailbits space begins
3119 *
3120 * Make sure that the data buffers attached to a socket buffer are
3121 * writable. If they are not, private copies are made of the data buffers
3122 * and the socket buffer is set to use these instead.
3123 *
3124 * If @tailbits is given, make sure that there is space to write @tailbits
3125 * bytes of data beyond current end of socket buffer. @trailer will be
3126 * set to point to the skb in which this space begins.
3127 *
3128 * The number of scatterlist elements required to completely map the
3129 * COW'd and extended socket buffer will be returned.
3130 */
3131int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
3132{
3133 int copyflag;
3134 int elt;
3135 struct sk_buff *skb1, **skb_p;
3136
3137 /* If skb is cloned or its head is paged, reallocate
3138 * head pulling out all the pages (pages are considered not writable
3139 * at the moment even if they are anonymous).
3140 */
3141 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
3142 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
3143 return -ENOMEM;
3144
3145 /* Easy case. Most of packets will go this way. */
3146 if (!skb_has_frag_list(skb)) {
3147 /* A little of trouble, not enough of space for trailer.
3148 * This should not happen, when stack is tuned to generate
3149 * good frames. OK, on miss we reallocate and reserve even more
3150 * space, 128 bytes is fair. */
3151
3152 if (skb_tailroom(skb) < tailbits &&
3153 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
3154 return -ENOMEM;
3155
3156 /* Voila! */
3157 *trailer = skb;
3158 return 1;
3159 }
3160
3161 /* Misery. We are in troubles, going to mincer fragments... */
3162
3163 elt = 1;
3164 skb_p = &skb_shinfo(skb)->frag_list;
3165 copyflag = 0;
3166
3167 while ((skb1 = *skb_p) != NULL) {
3168 int ntail = 0;
3169
3170 /* The fragment is partially pulled by someone,
3171 * this can happen on input. Copy it and everything
3172 * after it. */
3173
3174 if (skb_shared(skb1))
3175 copyflag = 1;
3176
3177 /* If the skb is the last, worry about trailer. */
3178
3179 if (skb1->next == NULL && tailbits) {
3180 if (skb_shinfo(skb1)->nr_frags ||
3181 skb_has_frag_list(skb1) ||
3182 skb_tailroom(skb1) < tailbits)
3183 ntail = tailbits + 128;
3184 }
3185
3186 if (copyflag ||
3187 skb_cloned(skb1) ||
3188 ntail ||
3189 skb_shinfo(skb1)->nr_frags ||
3190 skb_has_frag_list(skb1)) {
3191 struct sk_buff *skb2;
3192
3193 /* Fuck, we are miserable poor guys... */
3194 if (ntail == 0)
3195 skb2 = skb_copy(skb1, GFP_ATOMIC);
3196 else
3197 skb2 = skb_copy_expand(skb1,
3198 skb_headroom(skb1),
3199 ntail,
3200 GFP_ATOMIC);
3201 if (unlikely(skb2 == NULL))
3202 return -ENOMEM;
3203
3204 if (skb1->sk)
3205 skb_set_owner_w(skb2, skb1->sk);
3206
3207 /* Looking around. Are we still alive?
3208 * OK, link new skb, drop old one */
3209
3210 skb2->next = skb1->next;
3211 *skb_p = skb2;
3212 kfree_skb(skb1);
3213 skb1 = skb2;
3214 }
3215 elt++;
3216 *trailer = skb1;
3217 skb_p = &skb1->next;
3218 }
3219
3220 return elt;
3221}
3222EXPORT_SYMBOL_GPL(skb_cow_data);
3223
3224static void sock_rmem_free(struct sk_buff *skb)
3225{
3226 struct sock *sk = skb->sk;
3227
3228 atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
3229}
3230
3231/*
3232 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
3233 */
3234int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
3235{
3236 int len = skb->len;
3237
3238 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
3239 (unsigned int)sk->sk_rcvbuf)
3240 return -ENOMEM;
3241
3242 skb_orphan(skb);
3243 skb->sk = sk;
3244 skb->destructor = sock_rmem_free;
3245 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
3246
3247 /* before exiting rcu section, make sure dst is refcounted */
3248 skb_dst_force(skb);
3249
3250 skb_queue_tail(&sk->sk_error_queue, skb);
3251 if (!sock_flag(sk, SOCK_DEAD))
3252 sk->sk_data_ready(sk, len);
3253 return 0;
3254}
3255EXPORT_SYMBOL(sock_queue_err_skb);
3256
3257void skb_tstamp_tx(struct sk_buff *orig_skb,
3258 struct skb_shared_hwtstamps *hwtstamps)
3259{
3260 struct sock *sk = orig_skb->sk;
3261 struct sock_exterr_skb *serr;
3262 struct sk_buff *skb;
3263 int err;
3264
3265 if (!sk)
3266 return;
3267
3268 skb = skb_clone(orig_skb, GFP_ATOMIC);
3269 if (!skb)
3270 return;
3271
3272 if (hwtstamps) {
3273 *skb_hwtstamps(skb) =
3274 *hwtstamps;
3275 } else {
3276 /*
3277 * no hardware time stamps available,
3278 * so keep the shared tx_flags and only
3279 * store software time stamp
3280 */
3281 skb->tstamp = ktime_get_real();
3282 }
3283
3284 serr = SKB_EXT_ERR(skb);
3285 memset(serr, 0, sizeof(*serr));
3286 serr->ee.ee_errno = ENOMSG;
3287 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3288
3289 err = sock_queue_err_skb(sk, skb);
3290
3291 if (err)
3292 kfree_skb(skb);
3293}
3294EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3295
3296void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
3297{
3298 struct sock *sk = skb->sk;
3299 struct sock_exterr_skb *serr;
3300 int err;
3301
3302 skb->wifi_acked_valid = 1;
3303 skb->wifi_acked = acked;
3304
3305 serr = SKB_EXT_ERR(skb);
3306 memset(serr, 0, sizeof(*serr));
3307 serr->ee.ee_errno = ENOMSG;
3308 serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
3309
3310 err = sock_queue_err_skb(sk, skb);
3311 if (err)
3312 kfree_skb(skb);
3313}
3314EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
3315
3316
3317/**
3318 * skb_partial_csum_set - set up and verify partial csum values for packet
3319 * @skb: the skb to set
3320 * @start: the number of bytes after skb->data to start checksumming.
3321 * @off: the offset from start to place the checksum.
3322 *
3323 * For untrusted partially-checksummed packets, we need to make sure the values
3324 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3325 *
3326 * This function checks and sets those values and skb->ip_summed: if this
3327 * returns false you should drop the packet.
3328 */
3329bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3330{
3331 if (unlikely(start > skb_headlen(skb)) ||
3332 unlikely((int)start + off > skb_headlen(skb) - 2)) {
3333 net_warn_ratelimited("bad partial csum: csum=%u/%u len=%u\n",
3334 start, off, skb_headlen(skb));
3335 return false;
3336 }
3337 skb->ip_summed = CHECKSUM_PARTIAL;
3338 skb->csum_start = skb_headroom(skb) + start;
3339 skb->csum_offset = off;
3340 return true;
3341}
3342EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3343
3344void __skb_warn_lro_forwarding(const struct sk_buff *skb)
3345{
3346 net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
3347 skb->dev->name);
3348}
3349EXPORT_SYMBOL(__skb_warn_lro_forwarding);
3350
3351void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
3352{
3353 if (head_stolen)
3354 kmem_cache_free(skbuff_head_cache, skb);
3355 else
3356 __kfree_skb(skb);
3357}
3358EXPORT_SYMBOL(kfree_skb_partial);
3359
3360/**
3361 * skb_try_coalesce - try to merge skb to prior one
3362 * @to: prior buffer
3363 * @from: buffer to add
3364 * @fragstolen: pointer to boolean
3365 * @delta_truesize: how much more was allocated than was requested
3366 */
3367bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
3368 bool *fragstolen, int *delta_truesize)
3369{
3370 int i, delta, len = from->len;
3371
3372 *fragstolen = false;
3373
3374 if (skb_cloned(to))
3375 return false;
3376
3377 if (len <= skb_tailroom(to)) {
3378 BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
3379 *delta_truesize = 0;
3380 return true;
3381 }
3382
3383 if (skb_has_frag_list(to) || skb_has_frag_list(from))
3384 return false;
3385
3386 if (skb_headlen(from) != 0) {
3387 struct page *page;
3388 unsigned int offset;
3389
3390 if (skb_shinfo(to)->nr_frags +
3391 skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
3392 return false;
3393
3394 if (skb_head_is_locked(from))
3395 return false;
3396
3397 delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
3398
3399 page = virt_to_head_page(from->head);
3400 offset = from->data - (unsigned char *)page_address(page);
3401
3402 skb_fill_page_desc(to, skb_shinfo(to)->nr_frags,
3403 page, offset, skb_headlen(from));
3404 *fragstolen = true;
3405 } else {
3406 if (skb_shinfo(to)->nr_frags +
3407 skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS)
3408 return false;
3409
3410 delta = from->truesize -
3411 SKB_TRUESIZE(skb_end_pointer(from) - from->head);
3412 }
3413
3414 WARN_ON_ONCE(delta < len);
3415
3416 memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags,
3417 skb_shinfo(from)->frags,
3418 skb_shinfo(from)->nr_frags * sizeof(skb_frag_t));
3419 skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags;
3420
3421 if (!skb_cloned(from))
3422 skb_shinfo(from)->nr_frags = 0;
3423
3424 /* if the skb is cloned this does nothing since we set nr_frags to 0 */
3425 for (i = 0; i < skb_shinfo(from)->nr_frags; i++)
3426 skb_frag_ref(from, i);
3427
3428 to->truesize += delta;
3429 to->len += len;
3430 to->data_len += len;
3431
3432 *delta_truesize = delta;
3433 return true;
3434}
3435EXPORT_SYMBOL(skb_try_coalesce);
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/if_vlan.h>
62#include <linux/mpls.h>
63#include <linux/kcov.h>
64
65#include <net/protocol.h>
66#include <net/dst.h>
67#include <net/sock.h>
68#include <net/checksum.h>
69#include <net/ip6_checksum.h>
70#include <net/xfrm.h>
71#include <net/mpls.h>
72#include <net/mptcp.h>
73#include <net/mctp.h>
74#include <net/page_pool.h>
75
76#include <linux/uaccess.h>
77#include <trace/events/skb.h>
78#include <linux/highmem.h>
79#include <linux/capability.h>
80#include <linux/user_namespace.h>
81#include <linux/indirect_call_wrapper.h>
82
83#include "dev.h"
84#include "sock_destructor.h"
85
86struct kmem_cache *skbuff_head_cache __ro_after_init;
87static struct kmem_cache *skbuff_fclone_cache __ro_after_init;
88#ifdef CONFIG_SKB_EXTENSIONS
89static struct kmem_cache *skbuff_ext_cache __ro_after_init;
90#endif
91int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
92EXPORT_SYMBOL(sysctl_max_skb_frags);
93
94#undef FN
95#define FN(reason) [SKB_DROP_REASON_##reason] = #reason,
96const char * const drop_reasons[] = {
97 [SKB_CONSUMED] = "CONSUMED",
98 DEFINE_DROP_REASON(FN, FN)
99};
100EXPORT_SYMBOL(drop_reasons);
101
102/**
103 * skb_panic - private function for out-of-line support
104 * @skb: buffer
105 * @sz: size
106 * @addr: address
107 * @msg: skb_over_panic or skb_under_panic
108 *
109 * Out-of-line support for skb_put() and skb_push().
110 * Called via the wrapper skb_over_panic() or skb_under_panic().
111 * Keep out of line to prevent kernel bloat.
112 * __builtin_return_address is not used because it is not always reliable.
113 */
114static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
115 const char msg[])
116{
117 pr_emerg("%s: text:%px len:%d put:%d head:%px data:%px tail:%#lx end:%#lx dev:%s\n",
118 msg, addr, skb->len, sz, skb->head, skb->data,
119 (unsigned long)skb->tail, (unsigned long)skb->end,
120 skb->dev ? skb->dev->name : "<NULL>");
121 BUG();
122}
123
124static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
125{
126 skb_panic(skb, sz, addr, __func__);
127}
128
129static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
130{
131 skb_panic(skb, sz, addr, __func__);
132}
133
134#define NAPI_SKB_CACHE_SIZE 64
135#define NAPI_SKB_CACHE_BULK 16
136#define NAPI_SKB_CACHE_HALF (NAPI_SKB_CACHE_SIZE / 2)
137
138#if PAGE_SIZE == SZ_4K
139
140#define NAPI_HAS_SMALL_PAGE_FRAG 1
141#define NAPI_SMALL_PAGE_PFMEMALLOC(nc) ((nc).pfmemalloc)
142
143/* specialized page frag allocator using a single order 0 page
144 * and slicing it into 1K sized fragment. Constrained to systems
145 * with a very limited amount of 1K fragments fitting a single
146 * page - to avoid excessive truesize underestimation
147 */
148
149struct page_frag_1k {
150 void *va;
151 u16 offset;
152 bool pfmemalloc;
153};
154
155static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp)
156{
157 struct page *page;
158 int offset;
159
160 offset = nc->offset - SZ_1K;
161 if (likely(offset >= 0))
162 goto use_frag;
163
164 page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
165 if (!page)
166 return NULL;
167
168 nc->va = page_address(page);
169 nc->pfmemalloc = page_is_pfmemalloc(page);
170 offset = PAGE_SIZE - SZ_1K;
171 page_ref_add(page, offset / SZ_1K);
172
173use_frag:
174 nc->offset = offset;
175 return nc->va + offset;
176}
177#else
178
179/* the small page is actually unused in this build; add dummy helpers
180 * to please the compiler and avoid later preprocessor's conditionals
181 */
182#define NAPI_HAS_SMALL_PAGE_FRAG 0
183#define NAPI_SMALL_PAGE_PFMEMALLOC(nc) false
184
185struct page_frag_1k {
186};
187
188static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp_mask)
189{
190 return NULL;
191}
192
193#endif
194
195struct napi_alloc_cache {
196 struct page_frag_cache page;
197 struct page_frag_1k page_small;
198 unsigned int skb_count;
199 void *skb_cache[NAPI_SKB_CACHE_SIZE];
200};
201
202static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
203static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache);
204
205/* Double check that napi_get_frags() allocates skbs with
206 * skb->head being backed by slab, not a page fragment.
207 * This is to make sure bug fixed in 3226b158e67c
208 * ("net: avoid 32 x truesize under-estimation for tiny skbs")
209 * does not accidentally come back.
210 */
211void napi_get_frags_check(struct napi_struct *napi)
212{
213 struct sk_buff *skb;
214
215 local_bh_disable();
216 skb = napi_get_frags(napi);
217 WARN_ON_ONCE(!NAPI_HAS_SMALL_PAGE_FRAG && skb && skb->head_frag);
218 napi_free_frags(napi);
219 local_bh_enable();
220}
221
222void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
223{
224 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
225
226 fragsz = SKB_DATA_ALIGN(fragsz);
227
228 return page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC, align_mask);
229}
230EXPORT_SYMBOL(__napi_alloc_frag_align);
231
232void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
233{
234 void *data;
235
236 fragsz = SKB_DATA_ALIGN(fragsz);
237 if (in_hardirq() || irqs_disabled()) {
238 struct page_frag_cache *nc = this_cpu_ptr(&netdev_alloc_cache);
239
240 data = page_frag_alloc_align(nc, fragsz, GFP_ATOMIC, align_mask);
241 } else {
242 struct napi_alloc_cache *nc;
243
244 local_bh_disable();
245 nc = this_cpu_ptr(&napi_alloc_cache);
246 data = page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC, align_mask);
247 local_bh_enable();
248 }
249 return data;
250}
251EXPORT_SYMBOL(__netdev_alloc_frag_align);
252
253static struct sk_buff *napi_skb_cache_get(void)
254{
255 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
256 struct sk_buff *skb;
257
258 if (unlikely(!nc->skb_count)) {
259 nc->skb_count = kmem_cache_alloc_bulk(skbuff_head_cache,
260 GFP_ATOMIC,
261 NAPI_SKB_CACHE_BULK,
262 nc->skb_cache);
263 if (unlikely(!nc->skb_count))
264 return NULL;
265 }
266
267 skb = nc->skb_cache[--nc->skb_count];
268 kasan_unpoison_object_data(skbuff_head_cache, skb);
269
270 return skb;
271}
272
273static inline void __finalize_skb_around(struct sk_buff *skb, void *data,
274 unsigned int size)
275{
276 struct skb_shared_info *shinfo;
277
278 size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
279
280 /* Assumes caller memset cleared SKB */
281 skb->truesize = SKB_TRUESIZE(size);
282 refcount_set(&skb->users, 1);
283 skb->head = data;
284 skb->data = data;
285 skb_reset_tail_pointer(skb);
286 skb_set_end_offset(skb, size);
287 skb->mac_header = (typeof(skb->mac_header))~0U;
288 skb->transport_header = (typeof(skb->transport_header))~0U;
289 skb->alloc_cpu = raw_smp_processor_id();
290 /* make sure we initialize shinfo sequentially */
291 shinfo = skb_shinfo(skb);
292 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
293 atomic_set(&shinfo->dataref, 1);
294
295 skb_set_kcov_handle(skb, kcov_common_handle());
296}
297
298static inline void *__slab_build_skb(struct sk_buff *skb, void *data,
299 unsigned int *size)
300{
301 void *resized;
302
303 /* Must find the allocation size (and grow it to match). */
304 *size = ksize(data);
305 /* krealloc() will immediately return "data" when
306 * "ksize(data)" is requested: it is the existing upper
307 * bounds. As a result, GFP_ATOMIC will be ignored. Note
308 * that this "new" pointer needs to be passed back to the
309 * caller for use so the __alloc_size hinting will be
310 * tracked correctly.
311 */
312 resized = krealloc(data, *size, GFP_ATOMIC);
313 WARN_ON_ONCE(resized != data);
314 return resized;
315}
316
317/* build_skb() variant which can operate on slab buffers.
318 * Note that this should be used sparingly as slab buffers
319 * cannot be combined efficiently by GRO!
320 */
321struct sk_buff *slab_build_skb(void *data)
322{
323 struct sk_buff *skb;
324 unsigned int size;
325
326 skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
327 if (unlikely(!skb))
328 return NULL;
329
330 memset(skb, 0, offsetof(struct sk_buff, tail));
331 data = __slab_build_skb(skb, data, &size);
332 __finalize_skb_around(skb, data, size);
333
334 return skb;
335}
336EXPORT_SYMBOL(slab_build_skb);
337
338/* Caller must provide SKB that is memset cleared */
339static void __build_skb_around(struct sk_buff *skb, void *data,
340 unsigned int frag_size)
341{
342 unsigned int size = frag_size;
343
344 /* frag_size == 0 is considered deprecated now. Callers
345 * using slab buffer should use slab_build_skb() instead.
346 */
347 if (WARN_ONCE(size == 0, "Use slab_build_skb() instead"))
348 data = __slab_build_skb(skb, data, &size);
349
350 __finalize_skb_around(skb, data, size);
351}
352
353/**
354 * __build_skb - build a network buffer
355 * @data: data buffer provided by caller
356 * @frag_size: size of data (must not be 0)
357 *
358 * Allocate a new &sk_buff. Caller provides space holding head and
359 * skb_shared_info. @data must have been allocated from the page
360 * allocator or vmalloc(). (A @frag_size of 0 to indicate a kmalloc()
361 * allocation is deprecated, and callers should use slab_build_skb()
362 * instead.)
363 * The return is the new skb buffer.
364 * On a failure the return is %NULL, and @data is not freed.
365 * Notes :
366 * Before IO, driver allocates only data buffer where NIC put incoming frame
367 * Driver should add room at head (NET_SKB_PAD) and
368 * MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
369 * After IO, driver calls build_skb(), to allocate sk_buff and populate it
370 * before giving packet to stack.
371 * RX rings only contains data buffers, not full skbs.
372 */
373struct sk_buff *__build_skb(void *data, unsigned int frag_size)
374{
375 struct sk_buff *skb;
376
377 skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
378 if (unlikely(!skb))
379 return NULL;
380
381 memset(skb, 0, offsetof(struct sk_buff, tail));
382 __build_skb_around(skb, data, frag_size);
383
384 return skb;
385}
386
387/* build_skb() is wrapper over __build_skb(), that specifically
388 * takes care of skb->head and skb->pfmemalloc
389 * This means that if @frag_size is not zero, then @data must be backed
390 * by a page fragment, not kmalloc() or vmalloc()
391 */
392struct sk_buff *build_skb(void *data, unsigned int frag_size)
393{
394 struct sk_buff *skb = __build_skb(data, frag_size);
395
396 if (skb && frag_size) {
397 skb->head_frag = 1;
398 if (page_is_pfmemalloc(virt_to_head_page(data)))
399 skb->pfmemalloc = 1;
400 }
401 return skb;
402}
403EXPORT_SYMBOL(build_skb);
404
405/**
406 * build_skb_around - build a network buffer around provided skb
407 * @skb: sk_buff provide by caller, must be memset cleared
408 * @data: data buffer provided by caller
409 * @frag_size: size of data, or 0 if head was kmalloced
410 */
411struct sk_buff *build_skb_around(struct sk_buff *skb,
412 void *data, unsigned int frag_size)
413{
414 if (unlikely(!skb))
415 return NULL;
416
417 __build_skb_around(skb, data, frag_size);
418
419 if (frag_size) {
420 skb->head_frag = 1;
421 if (page_is_pfmemalloc(virt_to_head_page(data)))
422 skb->pfmemalloc = 1;
423 }
424 return skb;
425}
426EXPORT_SYMBOL(build_skb_around);
427
428/**
429 * __napi_build_skb - build a network buffer
430 * @data: data buffer provided by caller
431 * @frag_size: size of data, or 0 if head was kmalloced
432 *
433 * Version of __build_skb() that uses NAPI percpu caches to obtain
434 * skbuff_head instead of inplace allocation.
435 *
436 * Returns a new &sk_buff on success, %NULL on allocation failure.
437 */
438static struct sk_buff *__napi_build_skb(void *data, unsigned int frag_size)
439{
440 struct sk_buff *skb;
441
442 skb = napi_skb_cache_get();
443 if (unlikely(!skb))
444 return NULL;
445
446 memset(skb, 0, offsetof(struct sk_buff, tail));
447 __build_skb_around(skb, data, frag_size);
448
449 return skb;
450}
451
452/**
453 * napi_build_skb - build a network buffer
454 * @data: data buffer provided by caller
455 * @frag_size: size of data, or 0 if head was kmalloced
456 *
457 * Version of __napi_build_skb() that takes care of skb->head_frag
458 * and skb->pfmemalloc when the data is a page or page fragment.
459 *
460 * Returns a new &sk_buff on success, %NULL on allocation failure.
461 */
462struct sk_buff *napi_build_skb(void *data, unsigned int frag_size)
463{
464 struct sk_buff *skb = __napi_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
471 return skb;
472}
473EXPORT_SYMBOL(napi_build_skb);
474
475/*
476 * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
477 * the caller if emergency pfmemalloc reserves are being used. If it is and
478 * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
479 * may be used. Otherwise, the packet data may be discarded until enough
480 * memory is free
481 */
482static void *kmalloc_reserve(size_t size, gfp_t flags, int node,
483 bool *pfmemalloc)
484{
485 void *obj;
486 bool ret_pfmemalloc = false;
487
488 /*
489 * Try a regular allocation, when that fails and we're not entitled
490 * to the reserves, fail.
491 */
492 obj = kmalloc_node_track_caller(size,
493 flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
494 node);
495 if (obj || !(gfp_pfmemalloc_allowed(flags)))
496 goto out;
497
498 /* Try again but now we are using pfmemalloc reserves */
499 ret_pfmemalloc = true;
500 obj = kmalloc_node_track_caller(size, flags, node);
501
502out:
503 if (pfmemalloc)
504 *pfmemalloc = ret_pfmemalloc;
505
506 return obj;
507}
508
509/* Allocate a new skbuff. We do this ourselves so we can fill in a few
510 * 'private' fields and also do memory statistics to find all the
511 * [BEEP] leaks.
512 *
513 */
514
515/**
516 * __alloc_skb - allocate a network buffer
517 * @size: size to allocate
518 * @gfp_mask: allocation mask
519 * @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
520 * instead of head cache and allocate a cloned (child) skb.
521 * If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
522 * allocations in case the data is required for writeback
523 * @node: numa node to allocate memory on
524 *
525 * Allocate a new &sk_buff. The returned buffer has no headroom and a
526 * tail room of at least size bytes. The object has a reference count
527 * of one. The return is the buffer. On a failure the return is %NULL.
528 *
529 * Buffers may only be allocated from interrupts using a @gfp_mask of
530 * %GFP_ATOMIC.
531 */
532struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
533 int flags, int node)
534{
535 struct kmem_cache *cache;
536 struct sk_buff *skb;
537 unsigned int osize;
538 bool pfmemalloc;
539 u8 *data;
540
541 cache = (flags & SKB_ALLOC_FCLONE)
542 ? skbuff_fclone_cache : skbuff_head_cache;
543
544 if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
545 gfp_mask |= __GFP_MEMALLOC;
546
547 /* Get the HEAD */
548 if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI)) == SKB_ALLOC_NAPI &&
549 likely(node == NUMA_NO_NODE || node == numa_mem_id()))
550 skb = napi_skb_cache_get();
551 else
552 skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node);
553 if (unlikely(!skb))
554 return NULL;
555 prefetchw(skb);
556
557 /* We do our best to align skb_shared_info on a separate cache
558 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
559 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
560 * Both skb->head and skb_shared_info are cache line aligned.
561 */
562 size = SKB_DATA_ALIGN(size);
563 size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
564 osize = kmalloc_size_roundup(size);
565 data = kmalloc_reserve(osize, gfp_mask, node, &pfmemalloc);
566 if (unlikely(!data))
567 goto nodata;
568 /* kmalloc_size_roundup() might give us more room than requested.
569 * Put skb_shared_info exactly at the end of allocated zone,
570 * to allow max possible filling before reallocation.
571 */
572 size = SKB_WITH_OVERHEAD(osize);
573 prefetchw(data + size);
574
575 /*
576 * Only clear those fields we need to clear, not those that we will
577 * actually initialise below. Hence, don't put any more fields after
578 * the tail pointer in struct sk_buff!
579 */
580 memset(skb, 0, offsetof(struct sk_buff, tail));
581 __build_skb_around(skb, data, osize);
582 skb->pfmemalloc = pfmemalloc;
583
584 if (flags & SKB_ALLOC_FCLONE) {
585 struct sk_buff_fclones *fclones;
586
587 fclones = container_of(skb, struct sk_buff_fclones, skb1);
588
589 skb->fclone = SKB_FCLONE_ORIG;
590 refcount_set(&fclones->fclone_ref, 1);
591 }
592
593 return skb;
594
595nodata:
596 kmem_cache_free(cache, skb);
597 return NULL;
598}
599EXPORT_SYMBOL(__alloc_skb);
600
601/**
602 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
603 * @dev: network device to receive on
604 * @len: length to allocate
605 * @gfp_mask: get_free_pages mask, passed to alloc_skb
606 *
607 * Allocate a new &sk_buff and assign it a usage count of one. The
608 * buffer has NET_SKB_PAD headroom built in. Users should allocate
609 * the headroom they think they need without accounting for the
610 * built in space. The built in space is used for optimisations.
611 *
612 * %NULL is returned if there is no free memory.
613 */
614struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
615 gfp_t gfp_mask)
616{
617 struct page_frag_cache *nc;
618 struct sk_buff *skb;
619 bool pfmemalloc;
620 void *data;
621
622 len += NET_SKB_PAD;
623
624 /* If requested length is either too small or too big,
625 * we use kmalloc() for skb->head allocation.
626 */
627 if (len <= SKB_WITH_OVERHEAD(1024) ||
628 len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
629 (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
630 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
631 if (!skb)
632 goto skb_fail;
633 goto skb_success;
634 }
635
636 len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
637 len = SKB_DATA_ALIGN(len);
638
639 if (sk_memalloc_socks())
640 gfp_mask |= __GFP_MEMALLOC;
641
642 if (in_hardirq() || irqs_disabled()) {
643 nc = this_cpu_ptr(&netdev_alloc_cache);
644 data = page_frag_alloc(nc, len, gfp_mask);
645 pfmemalloc = nc->pfmemalloc;
646 } else {
647 local_bh_disable();
648 nc = this_cpu_ptr(&napi_alloc_cache.page);
649 data = page_frag_alloc(nc, len, gfp_mask);
650 pfmemalloc = nc->pfmemalloc;
651 local_bh_enable();
652 }
653
654 if (unlikely(!data))
655 return NULL;
656
657 skb = __build_skb(data, len);
658 if (unlikely(!skb)) {
659 skb_free_frag(data);
660 return NULL;
661 }
662
663 if (pfmemalloc)
664 skb->pfmemalloc = 1;
665 skb->head_frag = 1;
666
667skb_success:
668 skb_reserve(skb, NET_SKB_PAD);
669 skb->dev = dev;
670
671skb_fail:
672 return skb;
673}
674EXPORT_SYMBOL(__netdev_alloc_skb);
675
676/**
677 * __napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
678 * @napi: napi instance this buffer was allocated for
679 * @len: length to allocate
680 * @gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
681 *
682 * Allocate a new sk_buff for use in NAPI receive. This buffer will
683 * attempt to allocate the head from a special reserved region used
684 * only for NAPI Rx allocation. By doing this we can save several
685 * CPU cycles by avoiding having to disable and re-enable IRQs.
686 *
687 * %NULL is returned if there is no free memory.
688 */
689struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
690 gfp_t gfp_mask)
691{
692 struct napi_alloc_cache *nc;
693 struct sk_buff *skb;
694 bool pfmemalloc;
695 void *data;
696
697 DEBUG_NET_WARN_ON_ONCE(!in_softirq());
698 len += NET_SKB_PAD + NET_IP_ALIGN;
699
700 /* If requested length is either too small or too big,
701 * we use kmalloc() for skb->head allocation.
702 * When the small frag allocator is available, prefer it over kmalloc
703 * for small fragments
704 */
705 if ((!NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) ||
706 len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
707 (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
708 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX | SKB_ALLOC_NAPI,
709 NUMA_NO_NODE);
710 if (!skb)
711 goto skb_fail;
712 goto skb_success;
713 }
714
715 nc = this_cpu_ptr(&napi_alloc_cache);
716
717 if (sk_memalloc_socks())
718 gfp_mask |= __GFP_MEMALLOC;
719
720 if (NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) {
721 /* we are artificially inflating the allocation size, but
722 * that is not as bad as it may look like, as:
723 * - 'len' less than GRO_MAX_HEAD makes little sense
724 * - On most systems, larger 'len' values lead to fragment
725 * size above 512 bytes
726 * - kmalloc would use the kmalloc-1k slab for such values
727 * - Builds with smaller GRO_MAX_HEAD will very likely do
728 * little networking, as that implies no WiFi and no
729 * tunnels support, and 32 bits arches.
730 */
731 len = SZ_1K;
732
733 data = page_frag_alloc_1k(&nc->page_small, gfp_mask);
734 pfmemalloc = NAPI_SMALL_PAGE_PFMEMALLOC(nc->page_small);
735 } else {
736 len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
737 len = SKB_DATA_ALIGN(len);
738
739 data = page_frag_alloc(&nc->page, len, gfp_mask);
740 pfmemalloc = nc->page.pfmemalloc;
741 }
742
743 if (unlikely(!data))
744 return NULL;
745
746 skb = __napi_build_skb(data, len);
747 if (unlikely(!skb)) {
748 skb_free_frag(data);
749 return NULL;
750 }
751
752 if (pfmemalloc)
753 skb->pfmemalloc = 1;
754 skb->head_frag = 1;
755
756skb_success:
757 skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
758 skb->dev = napi->dev;
759
760skb_fail:
761 return skb;
762}
763EXPORT_SYMBOL(__napi_alloc_skb);
764
765void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
766 int size, unsigned int truesize)
767{
768 skb_fill_page_desc(skb, i, page, off, size);
769 skb->len += size;
770 skb->data_len += size;
771 skb->truesize += truesize;
772}
773EXPORT_SYMBOL(skb_add_rx_frag);
774
775void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
776 unsigned int truesize)
777{
778 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
779
780 skb_frag_size_add(frag, size);
781 skb->len += size;
782 skb->data_len += size;
783 skb->truesize += truesize;
784}
785EXPORT_SYMBOL(skb_coalesce_rx_frag);
786
787static void skb_drop_list(struct sk_buff **listp)
788{
789 kfree_skb_list(*listp);
790 *listp = NULL;
791}
792
793static inline void skb_drop_fraglist(struct sk_buff *skb)
794{
795 skb_drop_list(&skb_shinfo(skb)->frag_list);
796}
797
798static void skb_clone_fraglist(struct sk_buff *skb)
799{
800 struct sk_buff *list;
801
802 skb_walk_frags(skb, list)
803 skb_get(list);
804}
805
806static bool skb_pp_recycle(struct sk_buff *skb, void *data)
807{
808 if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
809 return false;
810 return page_pool_return_skb_page(virt_to_page(data));
811}
812
813static void skb_free_head(struct sk_buff *skb)
814{
815 unsigned char *head = skb->head;
816
817 if (skb->head_frag) {
818 if (skb_pp_recycle(skb, head))
819 return;
820 skb_free_frag(head);
821 } else {
822 kfree(head);
823 }
824}
825
826static void skb_release_data(struct sk_buff *skb, enum skb_drop_reason reason)
827{
828 struct skb_shared_info *shinfo = skb_shinfo(skb);
829 int i;
830
831 if (skb->cloned &&
832 atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
833 &shinfo->dataref))
834 goto exit;
835
836 if (skb_zcopy(skb)) {
837 bool skip_unref = shinfo->flags & SKBFL_MANAGED_FRAG_REFS;
838
839 skb_zcopy_clear(skb, true);
840 if (skip_unref)
841 goto free_head;
842 }
843
844 for (i = 0; i < shinfo->nr_frags; i++)
845 __skb_frag_unref(&shinfo->frags[i], skb->pp_recycle);
846
847free_head:
848 if (shinfo->frag_list)
849 kfree_skb_list_reason(shinfo->frag_list, reason);
850
851 skb_free_head(skb);
852exit:
853 /* When we clone an SKB we copy the reycling bit. The pp_recycle
854 * bit is only set on the head though, so in order to avoid races
855 * while trying to recycle fragments on __skb_frag_unref() we need
856 * to make one SKB responsible for triggering the recycle path.
857 * So disable the recycling bit if an SKB is cloned and we have
858 * additional references to the fragmented part of the SKB.
859 * Eventually the last SKB will have the recycling bit set and it's
860 * dataref set to 0, which will trigger the recycling
861 */
862 skb->pp_recycle = 0;
863}
864
865/*
866 * Free an skbuff by memory without cleaning the state.
867 */
868static void kfree_skbmem(struct sk_buff *skb)
869{
870 struct sk_buff_fclones *fclones;
871
872 switch (skb->fclone) {
873 case SKB_FCLONE_UNAVAILABLE:
874 kmem_cache_free(skbuff_head_cache, skb);
875 return;
876
877 case SKB_FCLONE_ORIG:
878 fclones = container_of(skb, struct sk_buff_fclones, skb1);
879
880 /* We usually free the clone (TX completion) before original skb
881 * This test would have no chance to be true for the clone,
882 * while here, branch prediction will be good.
883 */
884 if (refcount_read(&fclones->fclone_ref) == 1)
885 goto fastpath;
886 break;
887
888 default: /* SKB_FCLONE_CLONE */
889 fclones = container_of(skb, struct sk_buff_fclones, skb2);
890 break;
891 }
892 if (!refcount_dec_and_test(&fclones->fclone_ref))
893 return;
894fastpath:
895 kmem_cache_free(skbuff_fclone_cache, fclones);
896}
897
898void skb_release_head_state(struct sk_buff *skb)
899{
900 skb_dst_drop(skb);
901 if (skb->destructor) {
902 DEBUG_NET_WARN_ON_ONCE(in_hardirq());
903 skb->destructor(skb);
904 }
905#if IS_ENABLED(CONFIG_NF_CONNTRACK)
906 nf_conntrack_put(skb_nfct(skb));
907#endif
908 skb_ext_put(skb);
909}
910
911/* Free everything but the sk_buff shell. */
912static void skb_release_all(struct sk_buff *skb, enum skb_drop_reason reason)
913{
914 skb_release_head_state(skb);
915 if (likely(skb->head))
916 skb_release_data(skb, reason);
917}
918
919/**
920 * __kfree_skb - private function
921 * @skb: buffer
922 *
923 * Free an sk_buff. Release anything attached to the buffer.
924 * Clean the state. This is an internal helper function. Users should
925 * always call kfree_skb
926 */
927
928void __kfree_skb(struct sk_buff *skb)
929{
930 skb_release_all(skb, SKB_DROP_REASON_NOT_SPECIFIED);
931 kfree_skbmem(skb);
932}
933EXPORT_SYMBOL(__kfree_skb);
934
935/**
936 * kfree_skb_reason - free an sk_buff with special reason
937 * @skb: buffer to free
938 * @reason: reason why this skb is dropped
939 *
940 * Drop a reference to the buffer and free it if the usage count has
941 * hit zero. Meanwhile, pass the drop reason to 'kfree_skb'
942 * tracepoint.
943 */
944void __fix_address
945kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
946{
947 if (unlikely(!skb_unref(skb)))
948 return;
949
950 DEBUG_NET_WARN_ON_ONCE(reason <= 0 || reason >= SKB_DROP_REASON_MAX);
951
952 if (reason == SKB_CONSUMED)
953 trace_consume_skb(skb);
954 else
955 trace_kfree_skb(skb, __builtin_return_address(0), reason);
956 __kfree_skb(skb);
957}
958EXPORT_SYMBOL(kfree_skb_reason);
959
960void kfree_skb_list_reason(struct sk_buff *segs,
961 enum skb_drop_reason reason)
962{
963 while (segs) {
964 struct sk_buff *next = segs->next;
965
966 kfree_skb_reason(segs, reason);
967 segs = next;
968 }
969}
970EXPORT_SYMBOL(kfree_skb_list_reason);
971
972/* Dump skb information and contents.
973 *
974 * Must only be called from net_ratelimit()-ed paths.
975 *
976 * Dumps whole packets if full_pkt, only headers otherwise.
977 */
978void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt)
979{
980 struct skb_shared_info *sh = skb_shinfo(skb);
981 struct net_device *dev = skb->dev;
982 struct sock *sk = skb->sk;
983 struct sk_buff *list_skb;
984 bool has_mac, has_trans;
985 int headroom, tailroom;
986 int i, len, seg_len;
987
988 if (full_pkt)
989 len = skb->len;
990 else
991 len = min_t(int, skb->len, MAX_HEADER + 128);
992
993 headroom = skb_headroom(skb);
994 tailroom = skb_tailroom(skb);
995
996 has_mac = skb_mac_header_was_set(skb);
997 has_trans = skb_transport_header_was_set(skb);
998
999 printk("%sskb len=%u headroom=%u headlen=%u tailroom=%u\n"
1000 "mac=(%d,%d) net=(%d,%d) trans=%d\n"
1001 "shinfo(txflags=%u nr_frags=%u gso(size=%hu type=%u segs=%hu))\n"
1002 "csum(0x%x ip_summed=%u complete_sw=%u valid=%u level=%u)\n"
1003 "hash(0x%x sw=%u l4=%u) proto=0x%04x pkttype=%u iif=%d\n",
1004 level, skb->len, headroom, skb_headlen(skb), tailroom,
1005 has_mac ? skb->mac_header : -1,
1006 has_mac ? skb_mac_header_len(skb) : -1,
1007 skb->network_header,
1008 has_trans ? skb_network_header_len(skb) : -1,
1009 has_trans ? skb->transport_header : -1,
1010 sh->tx_flags, sh->nr_frags,
1011 sh->gso_size, sh->gso_type, sh->gso_segs,
1012 skb->csum, skb->ip_summed, skb->csum_complete_sw,
1013 skb->csum_valid, skb->csum_level,
1014 skb->hash, skb->sw_hash, skb->l4_hash,
1015 ntohs(skb->protocol), skb->pkt_type, skb->skb_iif);
1016
1017 if (dev)
1018 printk("%sdev name=%s feat=%pNF\n",
1019 level, dev->name, &dev->features);
1020 if (sk)
1021 printk("%ssk family=%hu type=%u proto=%u\n",
1022 level, sk->sk_family, sk->sk_type, sk->sk_protocol);
1023
1024 if (full_pkt && headroom)
1025 print_hex_dump(level, "skb headroom: ", DUMP_PREFIX_OFFSET,
1026 16, 1, skb->head, headroom, false);
1027
1028 seg_len = min_t(int, skb_headlen(skb), len);
1029 if (seg_len)
1030 print_hex_dump(level, "skb linear: ", DUMP_PREFIX_OFFSET,
1031 16, 1, skb->data, seg_len, false);
1032 len -= seg_len;
1033
1034 if (full_pkt && tailroom)
1035 print_hex_dump(level, "skb tailroom: ", DUMP_PREFIX_OFFSET,
1036 16, 1, skb_tail_pointer(skb), tailroom, false);
1037
1038 for (i = 0; len && i < skb_shinfo(skb)->nr_frags; i++) {
1039 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1040 u32 p_off, p_len, copied;
1041 struct page *p;
1042 u8 *vaddr;
1043
1044 skb_frag_foreach_page(frag, skb_frag_off(frag),
1045 skb_frag_size(frag), p, p_off, p_len,
1046 copied) {
1047 seg_len = min_t(int, p_len, len);
1048 vaddr = kmap_atomic(p);
1049 print_hex_dump(level, "skb frag: ",
1050 DUMP_PREFIX_OFFSET,
1051 16, 1, vaddr + p_off, seg_len, false);
1052 kunmap_atomic(vaddr);
1053 len -= seg_len;
1054 if (!len)
1055 break;
1056 }
1057 }
1058
1059 if (full_pkt && skb_has_frag_list(skb)) {
1060 printk("skb fraglist:\n");
1061 skb_walk_frags(skb, list_skb)
1062 skb_dump(level, list_skb, true);
1063 }
1064}
1065EXPORT_SYMBOL(skb_dump);
1066
1067/**
1068 * skb_tx_error - report an sk_buff xmit error
1069 * @skb: buffer that triggered an error
1070 *
1071 * Report xmit error if a device callback is tracking this skb.
1072 * skb must be freed afterwards.
1073 */
1074void skb_tx_error(struct sk_buff *skb)
1075{
1076 if (skb) {
1077 skb_zcopy_downgrade_managed(skb);
1078 skb_zcopy_clear(skb, true);
1079 }
1080}
1081EXPORT_SYMBOL(skb_tx_error);
1082
1083#ifdef CONFIG_TRACEPOINTS
1084/**
1085 * consume_skb - free an skbuff
1086 * @skb: buffer to free
1087 *
1088 * Drop a ref to the buffer and free it if the usage count has hit zero
1089 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
1090 * is being dropped after a failure and notes that
1091 */
1092void consume_skb(struct sk_buff *skb)
1093{
1094 if (!skb_unref(skb))
1095 return;
1096
1097 trace_consume_skb(skb);
1098 __kfree_skb(skb);
1099}
1100EXPORT_SYMBOL(consume_skb);
1101#endif
1102
1103/**
1104 * __consume_stateless_skb - free an skbuff, assuming it is stateless
1105 * @skb: buffer to free
1106 *
1107 * Alike consume_skb(), but this variant assumes that this is the last
1108 * skb reference and all the head states have been already dropped
1109 */
1110void __consume_stateless_skb(struct sk_buff *skb)
1111{
1112 trace_consume_skb(skb);
1113 skb_release_data(skb, SKB_CONSUMED);
1114 kfree_skbmem(skb);
1115}
1116
1117static void napi_skb_cache_put(struct sk_buff *skb)
1118{
1119 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
1120 u32 i;
1121
1122 kasan_poison_object_data(skbuff_head_cache, skb);
1123 nc->skb_cache[nc->skb_count++] = skb;
1124
1125 if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
1126 for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
1127 kasan_unpoison_object_data(skbuff_head_cache,
1128 nc->skb_cache[i]);
1129
1130 kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_HALF,
1131 nc->skb_cache + NAPI_SKB_CACHE_HALF);
1132 nc->skb_count = NAPI_SKB_CACHE_HALF;
1133 }
1134}
1135
1136void __kfree_skb_defer(struct sk_buff *skb)
1137{
1138 skb_release_all(skb, SKB_DROP_REASON_NOT_SPECIFIED);
1139 napi_skb_cache_put(skb);
1140}
1141
1142void napi_skb_free_stolen_head(struct sk_buff *skb)
1143{
1144 if (unlikely(skb->slow_gro)) {
1145 nf_reset_ct(skb);
1146 skb_dst_drop(skb);
1147 skb_ext_put(skb);
1148 skb_orphan(skb);
1149 skb->slow_gro = 0;
1150 }
1151 napi_skb_cache_put(skb);
1152}
1153
1154void napi_consume_skb(struct sk_buff *skb, int budget)
1155{
1156 /* Zero budget indicate non-NAPI context called us, like netpoll */
1157 if (unlikely(!budget)) {
1158 dev_consume_skb_any(skb);
1159 return;
1160 }
1161
1162 DEBUG_NET_WARN_ON_ONCE(!in_softirq());
1163
1164 if (!skb_unref(skb))
1165 return;
1166
1167 /* if reaching here SKB is ready to free */
1168 trace_consume_skb(skb);
1169
1170 /* if SKB is a clone, don't handle this case */
1171 if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
1172 __kfree_skb(skb);
1173 return;
1174 }
1175
1176 skb_release_all(skb, SKB_CONSUMED);
1177 napi_skb_cache_put(skb);
1178}
1179EXPORT_SYMBOL(napi_consume_skb);
1180
1181/* Make sure a field is contained by headers group */
1182#define CHECK_SKB_FIELD(field) \
1183 BUILD_BUG_ON(offsetof(struct sk_buff, field) != \
1184 offsetof(struct sk_buff, headers.field)); \
1185
1186static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
1187{
1188 new->tstamp = old->tstamp;
1189 /* We do not copy old->sk */
1190 new->dev = old->dev;
1191 memcpy(new->cb, old->cb, sizeof(old->cb));
1192 skb_dst_copy(new, old);
1193 __skb_ext_copy(new, old);
1194 __nf_copy(new, old, false);
1195
1196 /* Note : this field could be in the headers group.
1197 * It is not yet because we do not want to have a 16 bit hole
1198 */
1199 new->queue_mapping = old->queue_mapping;
1200
1201 memcpy(&new->headers, &old->headers, sizeof(new->headers));
1202 CHECK_SKB_FIELD(protocol);
1203 CHECK_SKB_FIELD(csum);
1204 CHECK_SKB_FIELD(hash);
1205 CHECK_SKB_FIELD(priority);
1206 CHECK_SKB_FIELD(skb_iif);
1207 CHECK_SKB_FIELD(vlan_proto);
1208 CHECK_SKB_FIELD(vlan_tci);
1209 CHECK_SKB_FIELD(transport_header);
1210 CHECK_SKB_FIELD(network_header);
1211 CHECK_SKB_FIELD(mac_header);
1212 CHECK_SKB_FIELD(inner_protocol);
1213 CHECK_SKB_FIELD(inner_transport_header);
1214 CHECK_SKB_FIELD(inner_network_header);
1215 CHECK_SKB_FIELD(inner_mac_header);
1216 CHECK_SKB_FIELD(mark);
1217#ifdef CONFIG_NETWORK_SECMARK
1218 CHECK_SKB_FIELD(secmark);
1219#endif
1220#ifdef CONFIG_NET_RX_BUSY_POLL
1221 CHECK_SKB_FIELD(napi_id);
1222#endif
1223 CHECK_SKB_FIELD(alloc_cpu);
1224#ifdef CONFIG_XPS
1225 CHECK_SKB_FIELD(sender_cpu);
1226#endif
1227#ifdef CONFIG_NET_SCHED
1228 CHECK_SKB_FIELD(tc_index);
1229#endif
1230
1231}
1232
1233/*
1234 * You should not add any new code to this function. Add it to
1235 * __copy_skb_header above instead.
1236 */
1237static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
1238{
1239#define C(x) n->x = skb->x
1240
1241 n->next = n->prev = NULL;
1242 n->sk = NULL;
1243 __copy_skb_header(n, skb);
1244
1245 C(len);
1246 C(data_len);
1247 C(mac_len);
1248 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
1249 n->cloned = 1;
1250 n->nohdr = 0;
1251 n->peeked = 0;
1252 C(pfmemalloc);
1253 C(pp_recycle);
1254 n->destructor = NULL;
1255 C(tail);
1256 C(end);
1257 C(head);
1258 C(head_frag);
1259 C(data);
1260 C(truesize);
1261 refcount_set(&n->users, 1);
1262
1263 atomic_inc(&(skb_shinfo(skb)->dataref));
1264 skb->cloned = 1;
1265
1266 return n;
1267#undef C
1268}
1269
1270/**
1271 * alloc_skb_for_msg() - allocate sk_buff to wrap frag list forming a msg
1272 * @first: first sk_buff of the msg
1273 */
1274struct sk_buff *alloc_skb_for_msg(struct sk_buff *first)
1275{
1276 struct sk_buff *n;
1277
1278 n = alloc_skb(0, GFP_ATOMIC);
1279 if (!n)
1280 return NULL;
1281
1282 n->len = first->len;
1283 n->data_len = first->len;
1284 n->truesize = first->truesize;
1285
1286 skb_shinfo(n)->frag_list = first;
1287
1288 __copy_skb_header(n, first);
1289 n->destructor = NULL;
1290
1291 return n;
1292}
1293EXPORT_SYMBOL_GPL(alloc_skb_for_msg);
1294
1295/**
1296 * skb_morph - morph one skb into another
1297 * @dst: the skb to receive the contents
1298 * @src: the skb to supply the contents
1299 *
1300 * This is identical to skb_clone except that the target skb is
1301 * supplied by the user.
1302 *
1303 * The target skb is returned upon exit.
1304 */
1305struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
1306{
1307 skb_release_all(dst, SKB_CONSUMED);
1308 return __skb_clone(dst, src);
1309}
1310EXPORT_SYMBOL_GPL(skb_morph);
1311
1312int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
1313{
1314 unsigned long max_pg, num_pg, new_pg, old_pg;
1315 struct user_struct *user;
1316
1317 if (capable(CAP_IPC_LOCK) || !size)
1318 return 0;
1319
1320 num_pg = (size >> PAGE_SHIFT) + 2; /* worst case */
1321 max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
1322 user = mmp->user ? : current_user();
1323
1324 old_pg = atomic_long_read(&user->locked_vm);
1325 do {
1326 new_pg = old_pg + num_pg;
1327 if (new_pg > max_pg)
1328 return -ENOBUFS;
1329 } while (!atomic_long_try_cmpxchg(&user->locked_vm, &old_pg, new_pg));
1330
1331 if (!mmp->user) {
1332 mmp->user = get_uid(user);
1333 mmp->num_pg = num_pg;
1334 } else {
1335 mmp->num_pg += num_pg;
1336 }
1337
1338 return 0;
1339}
1340EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
1341
1342void mm_unaccount_pinned_pages(struct mmpin *mmp)
1343{
1344 if (mmp->user) {
1345 atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
1346 free_uid(mmp->user);
1347 }
1348}
1349EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
1350
1351static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
1352{
1353 struct ubuf_info_msgzc *uarg;
1354 struct sk_buff *skb;
1355
1356 WARN_ON_ONCE(!in_task());
1357
1358 skb = sock_omalloc(sk, 0, GFP_KERNEL);
1359 if (!skb)
1360 return NULL;
1361
1362 BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
1363 uarg = (void *)skb->cb;
1364 uarg->mmp.user = NULL;
1365
1366 if (mm_account_pinned_pages(&uarg->mmp, size)) {
1367 kfree_skb(skb);
1368 return NULL;
1369 }
1370
1371 uarg->ubuf.callback = msg_zerocopy_callback;
1372 uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
1373 uarg->len = 1;
1374 uarg->bytelen = size;
1375 uarg->zerocopy = 1;
1376 uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
1377 refcount_set(&uarg->ubuf.refcnt, 1);
1378 sock_hold(sk);
1379
1380 return &uarg->ubuf;
1381}
1382
1383static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
1384{
1385 return container_of((void *)uarg, struct sk_buff, cb);
1386}
1387
1388struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
1389 struct ubuf_info *uarg)
1390{
1391 if (uarg) {
1392 struct ubuf_info_msgzc *uarg_zc;
1393 const u32 byte_limit = 1 << 19; /* limit to a few TSO */
1394 u32 bytelen, next;
1395
1396 /* there might be non MSG_ZEROCOPY users */
1397 if (uarg->callback != msg_zerocopy_callback)
1398 return NULL;
1399
1400 /* realloc only when socket is locked (TCP, UDP cork),
1401 * so uarg->len and sk_zckey access is serialized
1402 */
1403 if (!sock_owned_by_user(sk)) {
1404 WARN_ON_ONCE(1);
1405 return NULL;
1406 }
1407
1408 uarg_zc = uarg_to_msgzc(uarg);
1409 bytelen = uarg_zc->bytelen + size;
1410 if (uarg_zc->len == USHRT_MAX - 1 || bytelen > byte_limit) {
1411 /* TCP can create new skb to attach new uarg */
1412 if (sk->sk_type == SOCK_STREAM)
1413 goto new_alloc;
1414 return NULL;
1415 }
1416
1417 next = (u32)atomic_read(&sk->sk_zckey);
1418 if ((u32)(uarg_zc->id + uarg_zc->len) == next) {
1419 if (mm_account_pinned_pages(&uarg_zc->mmp, size))
1420 return NULL;
1421 uarg_zc->len++;
1422 uarg_zc->bytelen = bytelen;
1423 atomic_set(&sk->sk_zckey, ++next);
1424
1425 /* no extra ref when appending to datagram (MSG_MORE) */
1426 if (sk->sk_type == SOCK_STREAM)
1427 net_zcopy_get(uarg);
1428
1429 return uarg;
1430 }
1431 }
1432
1433new_alloc:
1434 return msg_zerocopy_alloc(sk, size);
1435}
1436EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
1437
1438static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
1439{
1440 struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
1441 u32 old_lo, old_hi;
1442 u64 sum_len;
1443
1444 old_lo = serr->ee.ee_info;
1445 old_hi = serr->ee.ee_data;
1446 sum_len = old_hi - old_lo + 1ULL + len;
1447
1448 if (sum_len >= (1ULL << 32))
1449 return false;
1450
1451 if (lo != old_hi + 1)
1452 return false;
1453
1454 serr->ee.ee_data += len;
1455 return true;
1456}
1457
1458static void __msg_zerocopy_callback(struct ubuf_info_msgzc *uarg)
1459{
1460 struct sk_buff *tail, *skb = skb_from_uarg(uarg);
1461 struct sock_exterr_skb *serr;
1462 struct sock *sk = skb->sk;
1463 struct sk_buff_head *q;
1464 unsigned long flags;
1465 bool is_zerocopy;
1466 u32 lo, hi;
1467 u16 len;
1468
1469 mm_unaccount_pinned_pages(&uarg->mmp);
1470
1471 /* if !len, there was only 1 call, and it was aborted
1472 * so do not queue a completion notification
1473 */
1474 if (!uarg->len || sock_flag(sk, SOCK_DEAD))
1475 goto release;
1476
1477 len = uarg->len;
1478 lo = uarg->id;
1479 hi = uarg->id + len - 1;
1480 is_zerocopy = uarg->zerocopy;
1481
1482 serr = SKB_EXT_ERR(skb);
1483 memset(serr, 0, sizeof(*serr));
1484 serr->ee.ee_errno = 0;
1485 serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
1486 serr->ee.ee_data = hi;
1487 serr->ee.ee_info = lo;
1488 if (!is_zerocopy)
1489 serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
1490
1491 q = &sk->sk_error_queue;
1492 spin_lock_irqsave(&q->lock, flags);
1493 tail = skb_peek_tail(q);
1494 if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
1495 !skb_zerocopy_notify_extend(tail, lo, len)) {
1496 __skb_queue_tail(q, skb);
1497 skb = NULL;
1498 }
1499 spin_unlock_irqrestore(&q->lock, flags);
1500
1501 sk_error_report(sk);
1502
1503release:
1504 consume_skb(skb);
1505 sock_put(sk);
1506}
1507
1508void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
1509 bool success)
1510{
1511 struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
1512
1513 uarg_zc->zerocopy = uarg_zc->zerocopy & success;
1514
1515 if (refcount_dec_and_test(&uarg->refcnt))
1516 __msg_zerocopy_callback(uarg_zc);
1517}
1518EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
1519
1520void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
1521{
1522 struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
1523
1524 atomic_dec(&sk->sk_zckey);
1525 uarg_to_msgzc(uarg)->len--;
1526
1527 if (have_uref)
1528 msg_zerocopy_callback(NULL, uarg, true);
1529}
1530EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
1531
1532int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
1533 struct msghdr *msg, int len,
1534 struct ubuf_info *uarg)
1535{
1536 struct ubuf_info *orig_uarg = skb_zcopy(skb);
1537 int err, orig_len = skb->len;
1538
1539 /* An skb can only point to one uarg. This edge case happens when
1540 * TCP appends to an skb, but zerocopy_realloc triggered a new alloc.
1541 */
1542 if (orig_uarg && uarg != orig_uarg)
1543 return -EEXIST;
1544
1545 err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len);
1546 if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
1547 struct sock *save_sk = skb->sk;
1548
1549 /* Streams do not free skb on error. Reset to prev state. */
1550 iov_iter_revert(&msg->msg_iter, skb->len - orig_len);
1551 skb->sk = sk;
1552 ___pskb_trim(skb, orig_len);
1553 skb->sk = save_sk;
1554 return err;
1555 }
1556
1557 skb_zcopy_set(skb, uarg, NULL);
1558 return skb->len - orig_len;
1559}
1560EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
1561
1562void __skb_zcopy_downgrade_managed(struct sk_buff *skb)
1563{
1564 int i;
1565
1566 skb_shinfo(skb)->flags &= ~SKBFL_MANAGED_FRAG_REFS;
1567 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1568 skb_frag_ref(skb, i);
1569}
1570EXPORT_SYMBOL_GPL(__skb_zcopy_downgrade_managed);
1571
1572static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
1573 gfp_t gfp_mask)
1574{
1575 if (skb_zcopy(orig)) {
1576 if (skb_zcopy(nskb)) {
1577 /* !gfp_mask callers are verified to !skb_zcopy(nskb) */
1578 if (!gfp_mask) {
1579 WARN_ON_ONCE(1);
1580 return -ENOMEM;
1581 }
1582 if (skb_uarg(nskb) == skb_uarg(orig))
1583 return 0;
1584 if (skb_copy_ubufs(nskb, GFP_ATOMIC))
1585 return -EIO;
1586 }
1587 skb_zcopy_set(nskb, skb_uarg(orig), NULL);
1588 }
1589 return 0;
1590}
1591
1592/**
1593 * skb_copy_ubufs - copy userspace skb frags buffers to kernel
1594 * @skb: the skb to modify
1595 * @gfp_mask: allocation priority
1596 *
1597 * This must be called on skb with SKBFL_ZEROCOPY_ENABLE.
1598 * It will copy all frags into kernel and drop the reference
1599 * to userspace pages.
1600 *
1601 * If this function is called from an interrupt gfp_mask() must be
1602 * %GFP_ATOMIC.
1603 *
1604 * Returns 0 on success or a negative error code on failure
1605 * to allocate kernel memory to copy to.
1606 */
1607int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
1608{
1609 int num_frags = skb_shinfo(skb)->nr_frags;
1610 struct page *page, *head = NULL;
1611 int i, new_frags;
1612 u32 d_off;
1613
1614 if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
1615 return -EINVAL;
1616
1617 if (!num_frags)
1618 goto release;
1619
1620 new_frags = (__skb_pagelen(skb) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1621 for (i = 0; i < new_frags; i++) {
1622 page = alloc_page(gfp_mask);
1623 if (!page) {
1624 while (head) {
1625 struct page *next = (struct page *)page_private(head);
1626 put_page(head);
1627 head = next;
1628 }
1629 return -ENOMEM;
1630 }
1631 set_page_private(page, (unsigned long)head);
1632 head = page;
1633 }
1634
1635 page = head;
1636 d_off = 0;
1637 for (i = 0; i < num_frags; i++) {
1638 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1639 u32 p_off, p_len, copied;
1640 struct page *p;
1641 u8 *vaddr;
1642
1643 skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
1644 p, p_off, p_len, copied) {
1645 u32 copy, done = 0;
1646 vaddr = kmap_atomic(p);
1647
1648 while (done < p_len) {
1649 if (d_off == PAGE_SIZE) {
1650 d_off = 0;
1651 page = (struct page *)page_private(page);
1652 }
1653 copy = min_t(u32, PAGE_SIZE - d_off, p_len - done);
1654 memcpy(page_address(page) + d_off,
1655 vaddr + p_off + done, copy);
1656 done += copy;
1657 d_off += copy;
1658 }
1659 kunmap_atomic(vaddr);
1660 }
1661 }
1662
1663 /* skb frags release userspace buffers */
1664 for (i = 0; i < num_frags; i++)
1665 skb_frag_unref(skb, i);
1666
1667 /* skb frags point to kernel buffers */
1668 for (i = 0; i < new_frags - 1; i++) {
1669 __skb_fill_page_desc(skb, i, head, 0, PAGE_SIZE);
1670 head = (struct page *)page_private(head);
1671 }
1672 __skb_fill_page_desc(skb, new_frags - 1, head, 0, d_off);
1673 skb_shinfo(skb)->nr_frags = new_frags;
1674
1675release:
1676 skb_zcopy_clear(skb, false);
1677 return 0;
1678}
1679EXPORT_SYMBOL_GPL(skb_copy_ubufs);
1680
1681/**
1682 * skb_clone - duplicate an sk_buff
1683 * @skb: buffer to clone
1684 * @gfp_mask: allocation priority
1685 *
1686 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
1687 * copies share the same packet data but not structure. The new
1688 * buffer has a reference count of 1. If the allocation fails the
1689 * function returns %NULL otherwise the new buffer is returned.
1690 *
1691 * If this function is called from an interrupt gfp_mask() must be
1692 * %GFP_ATOMIC.
1693 */
1694
1695struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
1696{
1697 struct sk_buff_fclones *fclones = container_of(skb,
1698 struct sk_buff_fclones,
1699 skb1);
1700 struct sk_buff *n;
1701
1702 if (skb_orphan_frags(skb, gfp_mask))
1703 return NULL;
1704
1705 if (skb->fclone == SKB_FCLONE_ORIG &&
1706 refcount_read(&fclones->fclone_ref) == 1) {
1707 n = &fclones->skb2;
1708 refcount_set(&fclones->fclone_ref, 2);
1709 n->fclone = SKB_FCLONE_CLONE;
1710 } else {
1711 if (skb_pfmemalloc(skb))
1712 gfp_mask |= __GFP_MEMALLOC;
1713
1714 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
1715 if (!n)
1716 return NULL;
1717
1718 n->fclone = SKB_FCLONE_UNAVAILABLE;
1719 }
1720
1721 return __skb_clone(n, skb);
1722}
1723EXPORT_SYMBOL(skb_clone);
1724
1725void skb_headers_offset_update(struct sk_buff *skb, int off)
1726{
1727 /* Only adjust this if it actually is csum_start rather than csum */
1728 if (skb->ip_summed == CHECKSUM_PARTIAL)
1729 skb->csum_start += off;
1730 /* {transport,network,mac}_header and tail are relative to skb->head */
1731 skb->transport_header += off;
1732 skb->network_header += off;
1733 if (skb_mac_header_was_set(skb))
1734 skb->mac_header += off;
1735 skb->inner_transport_header += off;
1736 skb->inner_network_header += off;
1737 skb->inner_mac_header += off;
1738}
1739EXPORT_SYMBOL(skb_headers_offset_update);
1740
1741void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
1742{
1743 __copy_skb_header(new, old);
1744
1745 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
1746 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
1747 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
1748}
1749EXPORT_SYMBOL(skb_copy_header);
1750
1751static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
1752{
1753 if (skb_pfmemalloc(skb))
1754 return SKB_ALLOC_RX;
1755 return 0;
1756}
1757
1758/**
1759 * skb_copy - create private copy of an sk_buff
1760 * @skb: buffer to copy
1761 * @gfp_mask: allocation priority
1762 *
1763 * Make a copy of both an &sk_buff and its data. This is used when the
1764 * caller wishes to modify the data and needs a private copy of the
1765 * data to alter. Returns %NULL on failure or the pointer to the buffer
1766 * on success. The returned buffer has a reference count of 1.
1767 *
1768 * As by-product this function converts non-linear &sk_buff to linear
1769 * one, so that &sk_buff becomes completely private and caller is allowed
1770 * to modify all the data of returned buffer. This means that this
1771 * function is not recommended for use in circumstances when only
1772 * header is going to be modified. Use pskb_copy() instead.
1773 */
1774
1775struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
1776{
1777 int headerlen = skb_headroom(skb);
1778 unsigned int size = skb_end_offset(skb) + skb->data_len;
1779 struct sk_buff *n = __alloc_skb(size, gfp_mask,
1780 skb_alloc_rx_flag(skb), NUMA_NO_NODE);
1781
1782 if (!n)
1783 return NULL;
1784
1785 /* Set the data pointer */
1786 skb_reserve(n, headerlen);
1787 /* Set the tail pointer and length */
1788 skb_put(n, skb->len);
1789
1790 BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
1791
1792 skb_copy_header(n, skb);
1793 return n;
1794}
1795EXPORT_SYMBOL(skb_copy);
1796
1797/**
1798 * __pskb_copy_fclone - create copy of an sk_buff with private head.
1799 * @skb: buffer to copy
1800 * @headroom: headroom of new skb
1801 * @gfp_mask: allocation priority
1802 * @fclone: if true allocate the copy of the skb from the fclone
1803 * cache instead of the head cache; it is recommended to set this
1804 * to true for the cases where the copy will likely be cloned
1805 *
1806 * Make a copy of both an &sk_buff and part of its data, located
1807 * in header. Fragmented data remain shared. This is used when
1808 * the caller wishes to modify only header of &sk_buff and needs
1809 * private copy of the header to alter. Returns %NULL on failure
1810 * or the pointer to the buffer on success.
1811 * The returned buffer has a reference count of 1.
1812 */
1813
1814struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
1815 gfp_t gfp_mask, bool fclone)
1816{
1817 unsigned int size = skb_headlen(skb) + headroom;
1818 int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
1819 struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
1820
1821 if (!n)
1822 goto out;
1823
1824 /* Set the data pointer */
1825 skb_reserve(n, headroom);
1826 /* Set the tail pointer and length */
1827 skb_put(n, skb_headlen(skb));
1828 /* Copy the bytes */
1829 skb_copy_from_linear_data(skb, n->data, n->len);
1830
1831 n->truesize += skb->data_len;
1832 n->data_len = skb->data_len;
1833 n->len = skb->len;
1834
1835 if (skb_shinfo(skb)->nr_frags) {
1836 int i;
1837
1838 if (skb_orphan_frags(skb, gfp_mask) ||
1839 skb_zerocopy_clone(n, skb, gfp_mask)) {
1840 kfree_skb(n);
1841 n = NULL;
1842 goto out;
1843 }
1844 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1845 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
1846 skb_frag_ref(skb, i);
1847 }
1848 skb_shinfo(n)->nr_frags = i;
1849 }
1850
1851 if (skb_has_frag_list(skb)) {
1852 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
1853 skb_clone_fraglist(n);
1854 }
1855
1856 skb_copy_header(n, skb);
1857out:
1858 return n;
1859}
1860EXPORT_SYMBOL(__pskb_copy_fclone);
1861
1862/**
1863 * pskb_expand_head - reallocate header of &sk_buff
1864 * @skb: buffer to reallocate
1865 * @nhead: room to add at head
1866 * @ntail: room to add at tail
1867 * @gfp_mask: allocation priority
1868 *
1869 * Expands (or creates identical copy, if @nhead and @ntail are zero)
1870 * header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
1871 * reference count of 1. Returns zero in the case of success or error,
1872 * if expansion failed. In the last case, &sk_buff is not changed.
1873 *
1874 * All the pointers pointing into skb header may change and must be
1875 * reloaded after call to this function.
1876 */
1877
1878int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
1879 gfp_t gfp_mask)
1880{
1881 unsigned int osize = skb_end_offset(skb);
1882 unsigned int size = osize + nhead + ntail;
1883 long off;
1884 u8 *data;
1885 int i;
1886
1887 BUG_ON(nhead < 0);
1888
1889 BUG_ON(skb_shared(skb));
1890
1891 skb_zcopy_downgrade_managed(skb);
1892
1893 if (skb_pfmemalloc(skb))
1894 gfp_mask |= __GFP_MEMALLOC;
1895
1896 size = SKB_DATA_ALIGN(size);
1897 size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
1898 size = kmalloc_size_roundup(size);
1899 data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL);
1900 if (!data)
1901 goto nodata;
1902 size = SKB_WITH_OVERHEAD(size);
1903
1904 /* Copy only real data... and, alas, header. This should be
1905 * optimized for the cases when header is void.
1906 */
1907 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
1908
1909 memcpy((struct skb_shared_info *)(data + size),
1910 skb_shinfo(skb),
1911 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
1912
1913 /*
1914 * if shinfo is shared we must drop the old head gracefully, but if it
1915 * is not we can just drop the old head and let the existing refcount
1916 * be since all we did is relocate the values
1917 */
1918 if (skb_cloned(skb)) {
1919 if (skb_orphan_frags(skb, gfp_mask))
1920 goto nofrags;
1921 if (skb_zcopy(skb))
1922 refcount_inc(&skb_uarg(skb)->refcnt);
1923 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1924 skb_frag_ref(skb, i);
1925
1926 if (skb_has_frag_list(skb))
1927 skb_clone_fraglist(skb);
1928
1929 skb_release_data(skb, SKB_CONSUMED);
1930 } else {
1931 skb_free_head(skb);
1932 }
1933 off = (data + nhead) - skb->head;
1934
1935 skb->head = data;
1936 skb->head_frag = 0;
1937 skb->data += off;
1938
1939 skb_set_end_offset(skb, size);
1940#ifdef NET_SKBUFF_DATA_USES_OFFSET
1941 off = nhead;
1942#endif
1943 skb->tail += off;
1944 skb_headers_offset_update(skb, nhead);
1945 skb->cloned = 0;
1946 skb->hdr_len = 0;
1947 skb->nohdr = 0;
1948 atomic_set(&skb_shinfo(skb)->dataref, 1);
1949
1950 skb_metadata_clear(skb);
1951
1952 /* It is not generally safe to change skb->truesize.
1953 * For the moment, we really care of rx path, or
1954 * when skb is orphaned (not attached to a socket).
1955 */
1956 if (!skb->sk || skb->destructor == sock_edemux)
1957 skb->truesize += size - osize;
1958
1959 return 0;
1960
1961nofrags:
1962 kfree(data);
1963nodata:
1964 return -ENOMEM;
1965}
1966EXPORT_SYMBOL(pskb_expand_head);
1967
1968/* Make private copy of skb with writable head and some headroom */
1969
1970struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1971{
1972 struct sk_buff *skb2;
1973 int delta = headroom - skb_headroom(skb);
1974
1975 if (delta <= 0)
1976 skb2 = pskb_copy(skb, GFP_ATOMIC);
1977 else {
1978 skb2 = skb_clone(skb, GFP_ATOMIC);
1979 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1980 GFP_ATOMIC)) {
1981 kfree_skb(skb2);
1982 skb2 = NULL;
1983 }
1984 }
1985 return skb2;
1986}
1987EXPORT_SYMBOL(skb_realloc_headroom);
1988
1989int __skb_unclone_keeptruesize(struct sk_buff *skb, gfp_t pri)
1990{
1991 unsigned int saved_end_offset, saved_truesize;
1992 struct skb_shared_info *shinfo;
1993 int res;
1994
1995 saved_end_offset = skb_end_offset(skb);
1996 saved_truesize = skb->truesize;
1997
1998 res = pskb_expand_head(skb, 0, 0, pri);
1999 if (res)
2000 return res;
2001
2002 skb->truesize = saved_truesize;
2003
2004 if (likely(skb_end_offset(skb) == saved_end_offset))
2005 return 0;
2006
2007 shinfo = skb_shinfo(skb);
2008
2009 /* We are about to change back skb->end,
2010 * we need to move skb_shinfo() to its new location.
2011 */
2012 memmove(skb->head + saved_end_offset,
2013 shinfo,
2014 offsetof(struct skb_shared_info, frags[shinfo->nr_frags]));
2015
2016 skb_set_end_offset(skb, saved_end_offset);
2017
2018 return 0;
2019}
2020
2021/**
2022 * skb_expand_head - reallocate header of &sk_buff
2023 * @skb: buffer to reallocate
2024 * @headroom: needed headroom
2025 *
2026 * Unlike skb_realloc_headroom, this one does not allocate a new skb
2027 * if possible; copies skb->sk to new skb as needed
2028 * and frees original skb in case of failures.
2029 *
2030 * It expect increased headroom and generates warning otherwise.
2031 */
2032
2033struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom)
2034{
2035 int delta = headroom - skb_headroom(skb);
2036 int osize = skb_end_offset(skb);
2037 struct sock *sk = skb->sk;
2038
2039 if (WARN_ONCE(delta <= 0,
2040 "%s is expecting an increase in the headroom", __func__))
2041 return skb;
2042
2043 delta = SKB_DATA_ALIGN(delta);
2044 /* pskb_expand_head() might crash, if skb is shared. */
2045 if (skb_shared(skb) || !is_skb_wmem(skb)) {
2046 struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
2047
2048 if (unlikely(!nskb))
2049 goto fail;
2050
2051 if (sk)
2052 skb_set_owner_w(nskb, sk);
2053 consume_skb(skb);
2054 skb = nskb;
2055 }
2056 if (pskb_expand_head(skb, delta, 0, GFP_ATOMIC))
2057 goto fail;
2058
2059 if (sk && is_skb_wmem(skb)) {
2060 delta = skb_end_offset(skb) - osize;
2061 refcount_add(delta, &sk->sk_wmem_alloc);
2062 skb->truesize += delta;
2063 }
2064 return skb;
2065
2066fail:
2067 kfree_skb(skb);
2068 return NULL;
2069}
2070EXPORT_SYMBOL(skb_expand_head);
2071
2072/**
2073 * skb_copy_expand - copy and expand sk_buff
2074 * @skb: buffer to copy
2075 * @newheadroom: new free bytes at head
2076 * @newtailroom: new free bytes at tail
2077 * @gfp_mask: allocation priority
2078 *
2079 * Make a copy of both an &sk_buff and its data and while doing so
2080 * allocate additional space.
2081 *
2082 * This is used when the caller wishes to modify the data and needs a
2083 * private copy of the data to alter as well as more space for new fields.
2084 * Returns %NULL on failure or the pointer to the buffer
2085 * on success. The returned buffer has a reference count of 1.
2086 *
2087 * You must pass %GFP_ATOMIC as the allocation priority if this function
2088 * is called from an interrupt.
2089 */
2090struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
2091 int newheadroom, int newtailroom,
2092 gfp_t gfp_mask)
2093{
2094 /*
2095 * Allocate the copy buffer
2096 */
2097 struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
2098 gfp_mask, skb_alloc_rx_flag(skb),
2099 NUMA_NO_NODE);
2100 int oldheadroom = skb_headroom(skb);
2101 int head_copy_len, head_copy_off;
2102
2103 if (!n)
2104 return NULL;
2105
2106 skb_reserve(n, newheadroom);
2107
2108 /* Set the tail pointer and length */
2109 skb_put(n, skb->len);
2110
2111 head_copy_len = oldheadroom;
2112 head_copy_off = 0;
2113 if (newheadroom <= head_copy_len)
2114 head_copy_len = newheadroom;
2115 else
2116 head_copy_off = newheadroom - head_copy_len;
2117
2118 /* Copy the linear header and data. */
2119 BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
2120 skb->len + head_copy_len));
2121
2122 skb_copy_header(n, skb);
2123
2124 skb_headers_offset_update(n, newheadroom - oldheadroom);
2125
2126 return n;
2127}
2128EXPORT_SYMBOL(skb_copy_expand);
2129
2130/**
2131 * __skb_pad - zero pad the tail of an skb
2132 * @skb: buffer to pad
2133 * @pad: space to pad
2134 * @free_on_error: free buffer on error
2135 *
2136 * Ensure that a buffer is followed by a padding area that is zero
2137 * filled. Used by network drivers which may DMA or transfer data
2138 * beyond the buffer end onto the wire.
2139 *
2140 * May return error in out of memory cases. The skb is freed on error
2141 * if @free_on_error is true.
2142 */
2143
2144int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
2145{
2146 int err;
2147 int ntail;
2148
2149 /* If the skbuff is non linear tailroom is always zero.. */
2150 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
2151 memset(skb->data+skb->len, 0, pad);
2152 return 0;
2153 }
2154
2155 ntail = skb->data_len + pad - (skb->end - skb->tail);
2156 if (likely(skb_cloned(skb) || ntail > 0)) {
2157 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
2158 if (unlikely(err))
2159 goto free_skb;
2160 }
2161
2162 /* FIXME: The use of this function with non-linear skb's really needs
2163 * to be audited.
2164 */
2165 err = skb_linearize(skb);
2166 if (unlikely(err))
2167 goto free_skb;
2168
2169 memset(skb->data + skb->len, 0, pad);
2170 return 0;
2171
2172free_skb:
2173 if (free_on_error)
2174 kfree_skb(skb);
2175 return err;
2176}
2177EXPORT_SYMBOL(__skb_pad);
2178
2179/**
2180 * pskb_put - add data to the tail of a potentially fragmented buffer
2181 * @skb: start of the buffer to use
2182 * @tail: tail fragment of the buffer to use
2183 * @len: amount of data to add
2184 *
2185 * This function extends the used data area of the potentially
2186 * fragmented buffer. @tail must be the last fragment of @skb -- or
2187 * @skb itself. If this would exceed the total buffer size the kernel
2188 * will panic. A pointer to the first byte of the extra data is
2189 * returned.
2190 */
2191
2192void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
2193{
2194 if (tail != skb) {
2195 skb->data_len += len;
2196 skb->len += len;
2197 }
2198 return skb_put(tail, len);
2199}
2200EXPORT_SYMBOL_GPL(pskb_put);
2201
2202/**
2203 * skb_put - add data to a buffer
2204 * @skb: buffer to use
2205 * @len: amount of data to add
2206 *
2207 * This function extends the used data area of the buffer. If this would
2208 * exceed the total buffer size the kernel will panic. A pointer to the
2209 * first byte of the extra data is returned.
2210 */
2211void *skb_put(struct sk_buff *skb, unsigned int len)
2212{
2213 void *tmp = skb_tail_pointer(skb);
2214 SKB_LINEAR_ASSERT(skb);
2215 skb->tail += len;
2216 skb->len += len;
2217 if (unlikely(skb->tail > skb->end))
2218 skb_over_panic(skb, len, __builtin_return_address(0));
2219 return tmp;
2220}
2221EXPORT_SYMBOL(skb_put);
2222
2223/**
2224 * skb_push - add data to the start of a buffer
2225 * @skb: buffer to use
2226 * @len: amount of data to add
2227 *
2228 * This function extends the used data area of the buffer at the buffer
2229 * start. If this would exceed the total buffer headroom the kernel will
2230 * panic. A pointer to the first byte of the extra data is returned.
2231 */
2232void *skb_push(struct sk_buff *skb, unsigned int len)
2233{
2234 skb->data -= len;
2235 skb->len += len;
2236 if (unlikely(skb->data < skb->head))
2237 skb_under_panic(skb, len, __builtin_return_address(0));
2238 return skb->data;
2239}
2240EXPORT_SYMBOL(skb_push);
2241
2242/**
2243 * skb_pull - remove data from the start of a buffer
2244 * @skb: buffer to use
2245 * @len: amount of data to remove
2246 *
2247 * This function removes data from the start of a buffer, returning
2248 * the memory to the headroom. A pointer to the next data in the buffer
2249 * is returned. Once the data has been pulled future pushes will overwrite
2250 * the old data.
2251 */
2252void *skb_pull(struct sk_buff *skb, unsigned int len)
2253{
2254 return skb_pull_inline(skb, len);
2255}
2256EXPORT_SYMBOL(skb_pull);
2257
2258/**
2259 * skb_pull_data - remove data from the start of a buffer returning its
2260 * original position.
2261 * @skb: buffer to use
2262 * @len: amount of data to remove
2263 *
2264 * This function removes data from the start of a buffer, returning
2265 * the memory to the headroom. A pointer to the original data in the buffer
2266 * is returned after checking if there is enough data to pull. Once the
2267 * data has been pulled future pushes will overwrite the old data.
2268 */
2269void *skb_pull_data(struct sk_buff *skb, size_t len)
2270{
2271 void *data = skb->data;
2272
2273 if (skb->len < len)
2274 return NULL;
2275
2276 skb_pull(skb, len);
2277
2278 return data;
2279}
2280EXPORT_SYMBOL(skb_pull_data);
2281
2282/**
2283 * skb_trim - remove end from a buffer
2284 * @skb: buffer to alter
2285 * @len: new length
2286 *
2287 * Cut the length of a buffer down by removing data from the tail. If
2288 * the buffer is already under the length specified it is not modified.
2289 * The skb must be linear.
2290 */
2291void skb_trim(struct sk_buff *skb, unsigned int len)
2292{
2293 if (skb->len > len)
2294 __skb_trim(skb, len);
2295}
2296EXPORT_SYMBOL(skb_trim);
2297
2298/* Trims skb to length len. It can change skb pointers.
2299 */
2300
2301int ___pskb_trim(struct sk_buff *skb, unsigned int len)
2302{
2303 struct sk_buff **fragp;
2304 struct sk_buff *frag;
2305 int offset = skb_headlen(skb);
2306 int nfrags = skb_shinfo(skb)->nr_frags;
2307 int i;
2308 int err;
2309
2310 if (skb_cloned(skb) &&
2311 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
2312 return err;
2313
2314 i = 0;
2315 if (offset >= len)
2316 goto drop_pages;
2317
2318 for (; i < nfrags; i++) {
2319 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2320
2321 if (end < len) {
2322 offset = end;
2323 continue;
2324 }
2325
2326 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
2327
2328drop_pages:
2329 skb_shinfo(skb)->nr_frags = i;
2330
2331 for (; i < nfrags; i++)
2332 skb_frag_unref(skb, i);
2333
2334 if (skb_has_frag_list(skb))
2335 skb_drop_fraglist(skb);
2336 goto done;
2337 }
2338
2339 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
2340 fragp = &frag->next) {
2341 int end = offset + frag->len;
2342
2343 if (skb_shared(frag)) {
2344 struct sk_buff *nfrag;
2345
2346 nfrag = skb_clone(frag, GFP_ATOMIC);
2347 if (unlikely(!nfrag))
2348 return -ENOMEM;
2349
2350 nfrag->next = frag->next;
2351 consume_skb(frag);
2352 frag = nfrag;
2353 *fragp = frag;
2354 }
2355
2356 if (end < len) {
2357 offset = end;
2358 continue;
2359 }
2360
2361 if (end > len &&
2362 unlikely((err = pskb_trim(frag, len - offset))))
2363 return err;
2364
2365 if (frag->next)
2366 skb_drop_list(&frag->next);
2367 break;
2368 }
2369
2370done:
2371 if (len > skb_headlen(skb)) {
2372 skb->data_len -= skb->len - len;
2373 skb->len = len;
2374 } else {
2375 skb->len = len;
2376 skb->data_len = 0;
2377 skb_set_tail_pointer(skb, len);
2378 }
2379
2380 if (!skb->sk || skb->destructor == sock_edemux)
2381 skb_condense(skb);
2382 return 0;
2383}
2384EXPORT_SYMBOL(___pskb_trim);
2385
2386/* Note : use pskb_trim_rcsum() instead of calling this directly
2387 */
2388int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
2389{
2390 if (skb->ip_summed == CHECKSUM_COMPLETE) {
2391 int delta = skb->len - len;
2392
2393 skb->csum = csum_block_sub(skb->csum,
2394 skb_checksum(skb, len, delta, 0),
2395 len);
2396 } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
2397 int hdlen = (len > skb_headlen(skb)) ? skb_headlen(skb) : len;
2398 int offset = skb_checksum_start_offset(skb) + skb->csum_offset;
2399
2400 if (offset + sizeof(__sum16) > hdlen)
2401 return -EINVAL;
2402 }
2403 return __pskb_trim(skb, len);
2404}
2405EXPORT_SYMBOL(pskb_trim_rcsum_slow);
2406
2407/**
2408 * __pskb_pull_tail - advance tail of skb header
2409 * @skb: buffer to reallocate
2410 * @delta: number of bytes to advance tail
2411 *
2412 * The function makes a sense only on a fragmented &sk_buff,
2413 * it expands header moving its tail forward and copying necessary
2414 * data from fragmented part.
2415 *
2416 * &sk_buff MUST have reference count of 1.
2417 *
2418 * Returns %NULL (and &sk_buff does not change) if pull failed
2419 * or value of new tail of skb in the case of success.
2420 *
2421 * All the pointers pointing into skb header may change and must be
2422 * reloaded after call to this function.
2423 */
2424
2425/* Moves tail of skb head forward, copying data from fragmented part,
2426 * when it is necessary.
2427 * 1. It may fail due to malloc failure.
2428 * 2. It may change skb pointers.
2429 *
2430 * It is pretty complicated. Luckily, it is called only in exceptional cases.
2431 */
2432void *__pskb_pull_tail(struct sk_buff *skb, int delta)
2433{
2434 /* If skb has not enough free space at tail, get new one
2435 * plus 128 bytes for future expansions. If we have enough
2436 * room at tail, reallocate without expansion only if skb is cloned.
2437 */
2438 int i, k, eat = (skb->tail + delta) - skb->end;
2439
2440 if (eat > 0 || skb_cloned(skb)) {
2441 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
2442 GFP_ATOMIC))
2443 return NULL;
2444 }
2445
2446 BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
2447 skb_tail_pointer(skb), delta));
2448
2449 /* Optimization: no fragments, no reasons to preestimate
2450 * size of pulled pages. Superb.
2451 */
2452 if (!skb_has_frag_list(skb))
2453 goto pull_pages;
2454
2455 /* Estimate size of pulled pages. */
2456 eat = delta;
2457 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2458 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2459
2460 if (size >= eat)
2461 goto pull_pages;
2462 eat -= size;
2463 }
2464
2465 /* If we need update frag list, we are in troubles.
2466 * Certainly, it is possible to add an offset to skb data,
2467 * but taking into account that pulling is expected to
2468 * be very rare operation, it is worth to fight against
2469 * further bloating skb head and crucify ourselves here instead.
2470 * Pure masohism, indeed. 8)8)
2471 */
2472 if (eat) {
2473 struct sk_buff *list = skb_shinfo(skb)->frag_list;
2474 struct sk_buff *clone = NULL;
2475 struct sk_buff *insp = NULL;
2476
2477 do {
2478 if (list->len <= eat) {
2479 /* Eaten as whole. */
2480 eat -= list->len;
2481 list = list->next;
2482 insp = list;
2483 } else {
2484 /* Eaten partially. */
2485 if (skb_is_gso(skb) && !list->head_frag &&
2486 skb_headlen(list))
2487 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
2488
2489 if (skb_shared(list)) {
2490 /* Sucks! We need to fork list. :-( */
2491 clone = skb_clone(list, GFP_ATOMIC);
2492 if (!clone)
2493 return NULL;
2494 insp = list->next;
2495 list = clone;
2496 } else {
2497 /* This may be pulled without
2498 * problems. */
2499 insp = list;
2500 }
2501 if (!pskb_pull(list, eat)) {
2502 kfree_skb(clone);
2503 return NULL;
2504 }
2505 break;
2506 }
2507 } while (eat);
2508
2509 /* Free pulled out fragments. */
2510 while ((list = skb_shinfo(skb)->frag_list) != insp) {
2511 skb_shinfo(skb)->frag_list = list->next;
2512 consume_skb(list);
2513 }
2514 /* And insert new clone at head. */
2515 if (clone) {
2516 clone->next = list;
2517 skb_shinfo(skb)->frag_list = clone;
2518 }
2519 }
2520 /* Success! Now we may commit changes to skb data. */
2521
2522pull_pages:
2523 eat = delta;
2524 k = 0;
2525 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2526 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2527
2528 if (size <= eat) {
2529 skb_frag_unref(skb, i);
2530 eat -= size;
2531 } else {
2532 skb_frag_t *frag = &skb_shinfo(skb)->frags[k];
2533
2534 *frag = skb_shinfo(skb)->frags[i];
2535 if (eat) {
2536 skb_frag_off_add(frag, eat);
2537 skb_frag_size_sub(frag, eat);
2538 if (!i)
2539 goto end;
2540 eat = 0;
2541 }
2542 k++;
2543 }
2544 }
2545 skb_shinfo(skb)->nr_frags = k;
2546
2547end:
2548 skb->tail += delta;
2549 skb->data_len -= delta;
2550
2551 if (!skb->data_len)
2552 skb_zcopy_clear(skb, false);
2553
2554 return skb_tail_pointer(skb);
2555}
2556EXPORT_SYMBOL(__pskb_pull_tail);
2557
2558/**
2559 * skb_copy_bits - copy bits from skb to kernel buffer
2560 * @skb: source skb
2561 * @offset: offset in source
2562 * @to: destination buffer
2563 * @len: number of bytes to copy
2564 *
2565 * Copy the specified number of bytes from the source skb to the
2566 * destination buffer.
2567 *
2568 * CAUTION ! :
2569 * If its prototype is ever changed,
2570 * check arch/{*}/net/{*}.S files,
2571 * since it is called from BPF assembly code.
2572 */
2573int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
2574{
2575 int start = skb_headlen(skb);
2576 struct sk_buff *frag_iter;
2577 int i, copy;
2578
2579 if (offset > (int)skb->len - len)
2580 goto fault;
2581
2582 /* Copy header. */
2583 if ((copy = start - offset) > 0) {
2584 if (copy > len)
2585 copy = len;
2586 skb_copy_from_linear_data_offset(skb, offset, to, copy);
2587 if ((len -= copy) == 0)
2588 return 0;
2589 offset += copy;
2590 to += copy;
2591 }
2592
2593 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2594 int end;
2595 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
2596
2597 WARN_ON(start > offset + len);
2598
2599 end = start + skb_frag_size(f);
2600 if ((copy = end - offset) > 0) {
2601 u32 p_off, p_len, copied;
2602 struct page *p;
2603 u8 *vaddr;
2604
2605 if (copy > len)
2606 copy = len;
2607
2608 skb_frag_foreach_page(f,
2609 skb_frag_off(f) + offset - start,
2610 copy, p, p_off, p_len, copied) {
2611 vaddr = kmap_atomic(p);
2612 memcpy(to + copied, vaddr + p_off, p_len);
2613 kunmap_atomic(vaddr);
2614 }
2615
2616 if ((len -= copy) == 0)
2617 return 0;
2618 offset += copy;
2619 to += copy;
2620 }
2621 start = end;
2622 }
2623
2624 skb_walk_frags(skb, frag_iter) {
2625 int end;
2626
2627 WARN_ON(start > offset + len);
2628
2629 end = start + frag_iter->len;
2630 if ((copy = end - offset) > 0) {
2631 if (copy > len)
2632 copy = len;
2633 if (skb_copy_bits(frag_iter, offset - start, to, copy))
2634 goto fault;
2635 if ((len -= copy) == 0)
2636 return 0;
2637 offset += copy;
2638 to += copy;
2639 }
2640 start = end;
2641 }
2642
2643 if (!len)
2644 return 0;
2645
2646fault:
2647 return -EFAULT;
2648}
2649EXPORT_SYMBOL(skb_copy_bits);
2650
2651/*
2652 * Callback from splice_to_pipe(), if we need to release some pages
2653 * at the end of the spd in case we error'ed out in filling the pipe.
2654 */
2655static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
2656{
2657 put_page(spd->pages[i]);
2658}
2659
2660static struct page *linear_to_page(struct page *page, unsigned int *len,
2661 unsigned int *offset,
2662 struct sock *sk)
2663{
2664 struct page_frag *pfrag = sk_page_frag(sk);
2665
2666 if (!sk_page_frag_refill(sk, pfrag))
2667 return NULL;
2668
2669 *len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
2670
2671 memcpy(page_address(pfrag->page) + pfrag->offset,
2672 page_address(page) + *offset, *len);
2673 *offset = pfrag->offset;
2674 pfrag->offset += *len;
2675
2676 return pfrag->page;
2677}
2678
2679static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
2680 struct page *page,
2681 unsigned int offset)
2682{
2683 return spd->nr_pages &&
2684 spd->pages[spd->nr_pages - 1] == page &&
2685 (spd->partial[spd->nr_pages - 1].offset +
2686 spd->partial[spd->nr_pages - 1].len == offset);
2687}
2688
2689/*
2690 * Fill page/offset/length into spd, if it can hold more pages.
2691 */
2692static bool spd_fill_page(struct splice_pipe_desc *spd,
2693 struct pipe_inode_info *pipe, struct page *page,
2694 unsigned int *len, unsigned int offset,
2695 bool linear,
2696 struct sock *sk)
2697{
2698 if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
2699 return true;
2700
2701 if (linear) {
2702 page = linear_to_page(page, len, &offset, sk);
2703 if (!page)
2704 return true;
2705 }
2706 if (spd_can_coalesce(spd, page, offset)) {
2707 spd->partial[spd->nr_pages - 1].len += *len;
2708 return false;
2709 }
2710 get_page(page);
2711 spd->pages[spd->nr_pages] = page;
2712 spd->partial[spd->nr_pages].len = *len;
2713 spd->partial[spd->nr_pages].offset = offset;
2714 spd->nr_pages++;
2715
2716 return false;
2717}
2718
2719static bool __splice_segment(struct page *page, unsigned int poff,
2720 unsigned int plen, unsigned int *off,
2721 unsigned int *len,
2722 struct splice_pipe_desc *spd, bool linear,
2723 struct sock *sk,
2724 struct pipe_inode_info *pipe)
2725{
2726 if (!*len)
2727 return true;
2728
2729 /* skip this segment if already processed */
2730 if (*off >= plen) {
2731 *off -= plen;
2732 return false;
2733 }
2734
2735 /* ignore any bits we already processed */
2736 poff += *off;
2737 plen -= *off;
2738 *off = 0;
2739
2740 do {
2741 unsigned int flen = min(*len, plen);
2742
2743 if (spd_fill_page(spd, pipe, page, &flen, poff,
2744 linear, sk))
2745 return true;
2746 poff += flen;
2747 plen -= flen;
2748 *len -= flen;
2749 } while (*len && plen);
2750
2751 return false;
2752}
2753
2754/*
2755 * Map linear and fragment data from the skb to spd. It reports true if the
2756 * pipe is full or if we already spliced the requested length.
2757 */
2758static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
2759 unsigned int *offset, unsigned int *len,
2760 struct splice_pipe_desc *spd, struct sock *sk)
2761{
2762 int seg;
2763 struct sk_buff *iter;
2764
2765 /* map the linear part :
2766 * If skb->head_frag is set, this 'linear' part is backed by a
2767 * fragment, and if the head is not shared with any clones then
2768 * we can avoid a copy since we own the head portion of this page.
2769 */
2770 if (__splice_segment(virt_to_page(skb->data),
2771 (unsigned long) skb->data & (PAGE_SIZE - 1),
2772 skb_headlen(skb),
2773 offset, len, spd,
2774 skb_head_is_locked(skb),
2775 sk, pipe))
2776 return true;
2777
2778 /*
2779 * then map the fragments
2780 */
2781 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
2782 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
2783
2784 if (__splice_segment(skb_frag_page(f),
2785 skb_frag_off(f), skb_frag_size(f),
2786 offset, len, spd, false, sk, pipe))
2787 return true;
2788 }
2789
2790 skb_walk_frags(skb, iter) {
2791 if (*offset >= iter->len) {
2792 *offset -= iter->len;
2793 continue;
2794 }
2795 /* __skb_splice_bits() only fails if the output has no room
2796 * left, so no point in going over the frag_list for the error
2797 * case.
2798 */
2799 if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
2800 return true;
2801 }
2802
2803 return false;
2804}
2805
2806/*
2807 * Map data from the skb to a pipe. Should handle both the linear part,
2808 * the fragments, and the frag list.
2809 */
2810int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
2811 struct pipe_inode_info *pipe, unsigned int tlen,
2812 unsigned int flags)
2813{
2814 struct partial_page partial[MAX_SKB_FRAGS];
2815 struct page *pages[MAX_SKB_FRAGS];
2816 struct splice_pipe_desc spd = {
2817 .pages = pages,
2818 .partial = partial,
2819 .nr_pages_max = MAX_SKB_FRAGS,
2820 .ops = &nosteal_pipe_buf_ops,
2821 .spd_release = sock_spd_release,
2822 };
2823 int ret = 0;
2824
2825 __skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
2826
2827 if (spd.nr_pages)
2828 ret = splice_to_pipe(pipe, &spd);
2829
2830 return ret;
2831}
2832EXPORT_SYMBOL_GPL(skb_splice_bits);
2833
2834static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg,
2835 struct kvec *vec, size_t num, size_t size)
2836{
2837 struct socket *sock = sk->sk_socket;
2838
2839 if (!sock)
2840 return -EINVAL;
2841 return kernel_sendmsg(sock, msg, vec, num, size);
2842}
2843
2844static int sendpage_unlocked(struct sock *sk, struct page *page, int offset,
2845 size_t size, int flags)
2846{
2847 struct socket *sock = sk->sk_socket;
2848
2849 if (!sock)
2850 return -EINVAL;
2851 return kernel_sendpage(sock, page, offset, size, flags);
2852}
2853
2854typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg,
2855 struct kvec *vec, size_t num, size_t size);
2856typedef int (*sendpage_func)(struct sock *sk, struct page *page, int offset,
2857 size_t size, int flags);
2858static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
2859 int len, sendmsg_func sendmsg, sendpage_func sendpage)
2860{
2861 unsigned int orig_len = len;
2862 struct sk_buff *head = skb;
2863 unsigned short fragidx;
2864 int slen, ret;
2865
2866do_frag_list:
2867
2868 /* Deal with head data */
2869 while (offset < skb_headlen(skb) && len) {
2870 struct kvec kv;
2871 struct msghdr msg;
2872
2873 slen = min_t(int, len, skb_headlen(skb) - offset);
2874 kv.iov_base = skb->data + offset;
2875 kv.iov_len = slen;
2876 memset(&msg, 0, sizeof(msg));
2877 msg.msg_flags = MSG_DONTWAIT;
2878
2879 ret = INDIRECT_CALL_2(sendmsg, kernel_sendmsg_locked,
2880 sendmsg_unlocked, sk, &msg, &kv, 1, slen);
2881 if (ret <= 0)
2882 goto error;
2883
2884 offset += ret;
2885 len -= ret;
2886 }
2887
2888 /* All the data was skb head? */
2889 if (!len)
2890 goto out;
2891
2892 /* Make offset relative to start of frags */
2893 offset -= skb_headlen(skb);
2894
2895 /* Find where we are in frag list */
2896 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
2897 skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
2898
2899 if (offset < skb_frag_size(frag))
2900 break;
2901
2902 offset -= skb_frag_size(frag);
2903 }
2904
2905 for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
2906 skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
2907
2908 slen = min_t(size_t, len, skb_frag_size(frag) - offset);
2909
2910 while (slen) {
2911 ret = INDIRECT_CALL_2(sendpage, kernel_sendpage_locked,
2912 sendpage_unlocked, sk,
2913 skb_frag_page(frag),
2914 skb_frag_off(frag) + offset,
2915 slen, MSG_DONTWAIT);
2916 if (ret <= 0)
2917 goto error;
2918
2919 len -= ret;
2920 offset += ret;
2921 slen -= ret;
2922 }
2923
2924 offset = 0;
2925 }
2926
2927 if (len) {
2928 /* Process any frag lists */
2929
2930 if (skb == head) {
2931 if (skb_has_frag_list(skb)) {
2932 skb = skb_shinfo(skb)->frag_list;
2933 goto do_frag_list;
2934 }
2935 } else if (skb->next) {
2936 skb = skb->next;
2937 goto do_frag_list;
2938 }
2939 }
2940
2941out:
2942 return orig_len - len;
2943
2944error:
2945 return orig_len == len ? ret : orig_len - len;
2946}
2947
2948/* Send skb data on a socket. Socket must be locked. */
2949int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
2950 int len)
2951{
2952 return __skb_send_sock(sk, skb, offset, len, kernel_sendmsg_locked,
2953 kernel_sendpage_locked);
2954}
2955EXPORT_SYMBOL_GPL(skb_send_sock_locked);
2956
2957/* Send skb data on a socket. Socket must be unlocked. */
2958int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
2959{
2960 return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked,
2961 sendpage_unlocked);
2962}
2963
2964/**
2965 * skb_store_bits - store bits from kernel buffer to skb
2966 * @skb: destination buffer
2967 * @offset: offset in destination
2968 * @from: source buffer
2969 * @len: number of bytes to copy
2970 *
2971 * Copy the specified number of bytes from the source buffer to the
2972 * destination skb. This function handles all the messy bits of
2973 * traversing fragment lists and such.
2974 */
2975
2976int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
2977{
2978 int start = skb_headlen(skb);
2979 struct sk_buff *frag_iter;
2980 int i, copy;
2981
2982 if (offset > (int)skb->len - len)
2983 goto fault;
2984
2985 if ((copy = start - offset) > 0) {
2986 if (copy > len)
2987 copy = len;
2988 skb_copy_to_linear_data_offset(skb, offset, from, copy);
2989 if ((len -= copy) == 0)
2990 return 0;
2991 offset += copy;
2992 from += copy;
2993 }
2994
2995 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2996 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2997 int end;
2998
2999 WARN_ON(start > offset + len);
3000
3001 end = start + skb_frag_size(frag);
3002 if ((copy = end - offset) > 0) {
3003 u32 p_off, p_len, copied;
3004 struct page *p;
3005 u8 *vaddr;
3006
3007 if (copy > len)
3008 copy = len;
3009
3010 skb_frag_foreach_page(frag,
3011 skb_frag_off(frag) + offset - start,
3012 copy, p, p_off, p_len, copied) {
3013 vaddr = kmap_atomic(p);
3014 memcpy(vaddr + p_off, from + copied, p_len);
3015 kunmap_atomic(vaddr);
3016 }
3017
3018 if ((len -= copy) == 0)
3019 return 0;
3020 offset += copy;
3021 from += copy;
3022 }
3023 start = end;
3024 }
3025
3026 skb_walk_frags(skb, frag_iter) {
3027 int end;
3028
3029 WARN_ON(start > offset + len);
3030
3031 end = start + frag_iter->len;
3032 if ((copy = end - offset) > 0) {
3033 if (copy > len)
3034 copy = len;
3035 if (skb_store_bits(frag_iter, offset - start,
3036 from, copy))
3037 goto fault;
3038 if ((len -= copy) == 0)
3039 return 0;
3040 offset += copy;
3041 from += copy;
3042 }
3043 start = end;
3044 }
3045 if (!len)
3046 return 0;
3047
3048fault:
3049 return -EFAULT;
3050}
3051EXPORT_SYMBOL(skb_store_bits);
3052
3053/* Checksum skb data. */
3054__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3055 __wsum csum, const struct skb_checksum_ops *ops)
3056{
3057 int start = skb_headlen(skb);
3058 int i, copy = start - offset;
3059 struct sk_buff *frag_iter;
3060 int pos = 0;
3061
3062 /* Checksum header. */
3063 if (copy > 0) {
3064 if (copy > len)
3065 copy = len;
3066 csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,
3067 skb->data + offset, copy, csum);
3068 if ((len -= copy) == 0)
3069 return csum;
3070 offset += copy;
3071 pos = copy;
3072 }
3073
3074 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3075 int end;
3076 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3077
3078 WARN_ON(start > offset + len);
3079
3080 end = start + skb_frag_size(frag);
3081 if ((copy = end - offset) > 0) {
3082 u32 p_off, p_len, copied;
3083 struct page *p;
3084 __wsum csum2;
3085 u8 *vaddr;
3086
3087 if (copy > len)
3088 copy = len;
3089
3090 skb_frag_foreach_page(frag,
3091 skb_frag_off(frag) + offset - start,
3092 copy, p, p_off, p_len, copied) {
3093 vaddr = kmap_atomic(p);
3094 csum2 = INDIRECT_CALL_1(ops->update,
3095 csum_partial_ext,
3096 vaddr + p_off, p_len, 0);
3097 kunmap_atomic(vaddr);
3098 csum = INDIRECT_CALL_1(ops->combine,
3099 csum_block_add_ext, csum,
3100 csum2, pos, p_len);
3101 pos += p_len;
3102 }
3103
3104 if (!(len -= copy))
3105 return csum;
3106 offset += copy;
3107 }
3108 start = end;
3109 }
3110
3111 skb_walk_frags(skb, frag_iter) {
3112 int end;
3113
3114 WARN_ON(start > offset + len);
3115
3116 end = start + frag_iter->len;
3117 if ((copy = end - offset) > 0) {
3118 __wsum csum2;
3119 if (copy > len)
3120 copy = len;
3121 csum2 = __skb_checksum(frag_iter, offset - start,
3122 copy, 0, ops);
3123 csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,
3124 csum, csum2, pos, copy);
3125 if ((len -= copy) == 0)
3126 return csum;
3127 offset += copy;
3128 pos += copy;
3129 }
3130 start = end;
3131 }
3132 BUG_ON(len);
3133
3134 return csum;
3135}
3136EXPORT_SYMBOL(__skb_checksum);
3137
3138__wsum skb_checksum(const struct sk_buff *skb, int offset,
3139 int len, __wsum csum)
3140{
3141 const struct skb_checksum_ops ops = {
3142 .update = csum_partial_ext,
3143 .combine = csum_block_add_ext,
3144 };
3145
3146 return __skb_checksum(skb, offset, len, csum, &ops);
3147}
3148EXPORT_SYMBOL(skb_checksum);
3149
3150/* Both of above in one bottle. */
3151
3152__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
3153 u8 *to, int len)
3154{
3155 int start = skb_headlen(skb);
3156 int i, copy = start - offset;
3157 struct sk_buff *frag_iter;
3158 int pos = 0;
3159 __wsum csum = 0;
3160
3161 /* Copy header. */
3162 if (copy > 0) {
3163 if (copy > len)
3164 copy = len;
3165 csum = csum_partial_copy_nocheck(skb->data + offset, to,
3166 copy);
3167 if ((len -= copy) == 0)
3168 return csum;
3169 offset += copy;
3170 to += copy;
3171 pos = copy;
3172 }
3173
3174 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3175 int end;
3176
3177 WARN_ON(start > offset + len);
3178
3179 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3180 if ((copy = end - offset) > 0) {
3181 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3182 u32 p_off, p_len, copied;
3183 struct page *p;
3184 __wsum csum2;
3185 u8 *vaddr;
3186
3187 if (copy > len)
3188 copy = len;
3189
3190 skb_frag_foreach_page(frag,
3191 skb_frag_off(frag) + offset - start,
3192 copy, p, p_off, p_len, copied) {
3193 vaddr = kmap_atomic(p);
3194 csum2 = csum_partial_copy_nocheck(vaddr + p_off,
3195 to + copied,
3196 p_len);
3197 kunmap_atomic(vaddr);
3198 csum = csum_block_add(csum, csum2, pos);
3199 pos += p_len;
3200 }
3201
3202 if (!(len -= copy))
3203 return csum;
3204 offset += copy;
3205 to += copy;
3206 }
3207 start = end;
3208 }
3209
3210 skb_walk_frags(skb, frag_iter) {
3211 __wsum csum2;
3212 int end;
3213
3214 WARN_ON(start > offset + len);
3215
3216 end = start + frag_iter->len;
3217 if ((copy = end - offset) > 0) {
3218 if (copy > len)
3219 copy = len;
3220 csum2 = skb_copy_and_csum_bits(frag_iter,
3221 offset - start,
3222 to, copy);
3223 csum = csum_block_add(csum, csum2, pos);
3224 if ((len -= copy) == 0)
3225 return csum;
3226 offset += copy;
3227 to += copy;
3228 pos += copy;
3229 }
3230 start = end;
3231 }
3232 BUG_ON(len);
3233 return csum;
3234}
3235EXPORT_SYMBOL(skb_copy_and_csum_bits);
3236
3237__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
3238{
3239 __sum16 sum;
3240
3241 sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
3242 /* See comments in __skb_checksum_complete(). */
3243 if (likely(!sum)) {
3244 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
3245 !skb->csum_complete_sw)
3246 netdev_rx_csum_fault(skb->dev, skb);
3247 }
3248 if (!skb_shared(skb))
3249 skb->csum_valid = !sum;
3250 return sum;
3251}
3252EXPORT_SYMBOL(__skb_checksum_complete_head);
3253
3254/* This function assumes skb->csum already holds pseudo header's checksum,
3255 * which has been changed from the hardware checksum, for example, by
3256 * __skb_checksum_validate_complete(). And, the original skb->csum must
3257 * have been validated unsuccessfully for CHECKSUM_COMPLETE case.
3258 *
3259 * It returns non-zero if the recomputed checksum is still invalid, otherwise
3260 * zero. The new checksum is stored back into skb->csum unless the skb is
3261 * shared.
3262 */
3263__sum16 __skb_checksum_complete(struct sk_buff *skb)
3264{
3265 __wsum csum;
3266 __sum16 sum;
3267
3268 csum = skb_checksum(skb, 0, skb->len, 0);
3269
3270 sum = csum_fold(csum_add(skb->csum, csum));
3271 /* This check is inverted, because we already knew the hardware
3272 * checksum is invalid before calling this function. So, if the
3273 * re-computed checksum is valid instead, then we have a mismatch
3274 * between the original skb->csum and skb_checksum(). This means either
3275 * the original hardware checksum is incorrect or we screw up skb->csum
3276 * when moving skb->data around.
3277 */
3278 if (likely(!sum)) {
3279 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
3280 !skb->csum_complete_sw)
3281 netdev_rx_csum_fault(skb->dev, skb);
3282 }
3283
3284 if (!skb_shared(skb)) {
3285 /* Save full packet checksum */
3286 skb->csum = csum;
3287 skb->ip_summed = CHECKSUM_COMPLETE;
3288 skb->csum_complete_sw = 1;
3289 skb->csum_valid = !sum;
3290 }
3291
3292 return sum;
3293}
3294EXPORT_SYMBOL(__skb_checksum_complete);
3295
3296static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
3297{
3298 net_warn_ratelimited(
3299 "%s: attempt to compute crc32c without libcrc32c.ko\n",
3300 __func__);
3301 return 0;
3302}
3303
3304static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
3305 int offset, int len)
3306{
3307 net_warn_ratelimited(
3308 "%s: attempt to compute crc32c without libcrc32c.ko\n",
3309 __func__);
3310 return 0;
3311}
3312
3313static const struct skb_checksum_ops default_crc32c_ops = {
3314 .update = warn_crc32c_csum_update,
3315 .combine = warn_crc32c_csum_combine,
3316};
3317
3318const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
3319 &default_crc32c_ops;
3320EXPORT_SYMBOL(crc32c_csum_stub);
3321
3322 /**
3323 * skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
3324 * @from: source buffer
3325 *
3326 * Calculates the amount of linear headroom needed in the 'to' skb passed
3327 * into skb_zerocopy().
3328 */
3329unsigned int
3330skb_zerocopy_headlen(const struct sk_buff *from)
3331{
3332 unsigned int hlen = 0;
3333
3334 if (!from->head_frag ||
3335 skb_headlen(from) < L1_CACHE_BYTES ||
3336 skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) {
3337 hlen = skb_headlen(from);
3338 if (!hlen)
3339 hlen = from->len;
3340 }
3341
3342 if (skb_has_frag_list(from))
3343 hlen = from->len;
3344
3345 return hlen;
3346}
3347EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
3348
3349/**
3350 * skb_zerocopy - Zero copy skb to skb
3351 * @to: destination buffer
3352 * @from: source buffer
3353 * @len: number of bytes to copy from source buffer
3354 * @hlen: size of linear headroom in destination buffer
3355 *
3356 * Copies up to `len` bytes from `from` to `to` by creating references
3357 * to the frags in the source buffer.
3358 *
3359 * The `hlen` as calculated by skb_zerocopy_headlen() specifies the
3360 * headroom in the `to` buffer.
3361 *
3362 * Return value:
3363 * 0: everything is OK
3364 * -ENOMEM: couldn't orphan frags of @from due to lack of memory
3365 * -EFAULT: skb_copy_bits() found some problem with skb geometry
3366 */
3367int
3368skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
3369{
3370 int i, j = 0;
3371 int plen = 0; /* length of skb->head fragment */
3372 int ret;
3373 struct page *page;
3374 unsigned int offset;
3375
3376 BUG_ON(!from->head_frag && !hlen);
3377
3378 /* dont bother with small payloads */
3379 if (len <= skb_tailroom(to))
3380 return skb_copy_bits(from, 0, skb_put(to, len), len);
3381
3382 if (hlen) {
3383 ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
3384 if (unlikely(ret))
3385 return ret;
3386 len -= hlen;
3387 } else {
3388 plen = min_t(int, skb_headlen(from), len);
3389 if (plen) {
3390 page = virt_to_head_page(from->head);
3391 offset = from->data - (unsigned char *)page_address(page);
3392 __skb_fill_page_desc(to, 0, page, offset, plen);
3393 get_page(page);
3394 j = 1;
3395 len -= plen;
3396 }
3397 }
3398
3399 skb_len_add(to, len + plen);
3400
3401 if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
3402 skb_tx_error(from);
3403 return -ENOMEM;
3404 }
3405 skb_zerocopy_clone(to, from, GFP_ATOMIC);
3406
3407 for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
3408 int size;
3409
3410 if (!len)
3411 break;
3412 skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
3413 size = min_t(int, skb_frag_size(&skb_shinfo(to)->frags[j]),
3414 len);
3415 skb_frag_size_set(&skb_shinfo(to)->frags[j], size);
3416 len -= size;
3417 skb_frag_ref(to, j);
3418 j++;
3419 }
3420 skb_shinfo(to)->nr_frags = j;
3421
3422 return 0;
3423}
3424EXPORT_SYMBOL_GPL(skb_zerocopy);
3425
3426void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
3427{
3428 __wsum csum;
3429 long csstart;
3430
3431 if (skb->ip_summed == CHECKSUM_PARTIAL)
3432 csstart = skb_checksum_start_offset(skb);
3433 else
3434 csstart = skb_headlen(skb);
3435
3436 BUG_ON(csstart > skb_headlen(skb));
3437
3438 skb_copy_from_linear_data(skb, to, csstart);
3439
3440 csum = 0;
3441 if (csstart != skb->len)
3442 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
3443 skb->len - csstart);
3444
3445 if (skb->ip_summed == CHECKSUM_PARTIAL) {
3446 long csstuff = csstart + skb->csum_offset;
3447
3448 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
3449 }
3450}
3451EXPORT_SYMBOL(skb_copy_and_csum_dev);
3452
3453/**
3454 * skb_dequeue - remove from the head of the queue
3455 * @list: list to dequeue from
3456 *
3457 * Remove the head of the list. The list lock is taken so the function
3458 * may be used safely with other locking list functions. The head item is
3459 * returned or %NULL if the list is empty.
3460 */
3461
3462struct sk_buff *skb_dequeue(struct sk_buff_head *list)
3463{
3464 unsigned long flags;
3465 struct sk_buff *result;
3466
3467 spin_lock_irqsave(&list->lock, flags);
3468 result = __skb_dequeue(list);
3469 spin_unlock_irqrestore(&list->lock, flags);
3470 return result;
3471}
3472EXPORT_SYMBOL(skb_dequeue);
3473
3474/**
3475 * skb_dequeue_tail - remove from the tail of the queue
3476 * @list: list to dequeue from
3477 *
3478 * Remove the tail of the list. The list lock is taken so the function
3479 * may be used safely with other locking list functions. The tail item is
3480 * returned or %NULL if the list is empty.
3481 */
3482struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
3483{
3484 unsigned long flags;
3485 struct sk_buff *result;
3486
3487 spin_lock_irqsave(&list->lock, flags);
3488 result = __skb_dequeue_tail(list);
3489 spin_unlock_irqrestore(&list->lock, flags);
3490 return result;
3491}
3492EXPORT_SYMBOL(skb_dequeue_tail);
3493
3494/**
3495 * skb_queue_purge - empty a list
3496 * @list: list to empty
3497 *
3498 * Delete all buffers on an &sk_buff list. Each buffer is removed from
3499 * the list and one reference dropped. This function takes the list
3500 * lock and is atomic with respect to other list locking functions.
3501 */
3502void skb_queue_purge(struct sk_buff_head *list)
3503{
3504 struct sk_buff *skb;
3505 while ((skb = skb_dequeue(list)) != NULL)
3506 kfree_skb(skb);
3507}
3508EXPORT_SYMBOL(skb_queue_purge);
3509
3510/**
3511 * skb_rbtree_purge - empty a skb rbtree
3512 * @root: root of the rbtree to empty
3513 * Return value: the sum of truesizes of all purged skbs.
3514 *
3515 * Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
3516 * the list and one reference dropped. This function does not take
3517 * any lock. Synchronization should be handled by the caller (e.g., TCP
3518 * out-of-order queue is protected by the socket lock).
3519 */
3520unsigned int skb_rbtree_purge(struct rb_root *root)
3521{
3522 struct rb_node *p = rb_first(root);
3523 unsigned int sum = 0;
3524
3525 while (p) {
3526 struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
3527
3528 p = rb_next(p);
3529 rb_erase(&skb->rbnode, root);
3530 sum += skb->truesize;
3531 kfree_skb(skb);
3532 }
3533 return sum;
3534}
3535
3536/**
3537 * skb_queue_head - queue a buffer at the list head
3538 * @list: list to use
3539 * @newsk: buffer to queue
3540 *
3541 * Queue a buffer at the start of the list. This function takes the
3542 * list lock and can be used safely with other locking &sk_buff functions
3543 * safely.
3544 *
3545 * A buffer cannot be placed on two lists at the same time.
3546 */
3547void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
3548{
3549 unsigned long flags;
3550
3551 spin_lock_irqsave(&list->lock, flags);
3552 __skb_queue_head(list, newsk);
3553 spin_unlock_irqrestore(&list->lock, flags);
3554}
3555EXPORT_SYMBOL(skb_queue_head);
3556
3557/**
3558 * skb_queue_tail - queue a buffer at the list tail
3559 * @list: list to use
3560 * @newsk: buffer to queue
3561 *
3562 * Queue a buffer at the tail of the list. This function takes the
3563 * list lock and can be used safely with other locking &sk_buff functions
3564 * safely.
3565 *
3566 * A buffer cannot be placed on two lists at the same time.
3567 */
3568void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
3569{
3570 unsigned long flags;
3571
3572 spin_lock_irqsave(&list->lock, flags);
3573 __skb_queue_tail(list, newsk);
3574 spin_unlock_irqrestore(&list->lock, flags);
3575}
3576EXPORT_SYMBOL(skb_queue_tail);
3577
3578/**
3579 * skb_unlink - remove a buffer from a list
3580 * @skb: buffer to remove
3581 * @list: list to use
3582 *
3583 * Remove a packet from a list. The list locks are taken and this
3584 * function is atomic with respect to other list locked calls
3585 *
3586 * You must know what list the SKB is on.
3587 */
3588void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
3589{
3590 unsigned long flags;
3591
3592 spin_lock_irqsave(&list->lock, flags);
3593 __skb_unlink(skb, list);
3594 spin_unlock_irqrestore(&list->lock, flags);
3595}
3596EXPORT_SYMBOL(skb_unlink);
3597
3598/**
3599 * skb_append - append a buffer
3600 * @old: buffer to insert after
3601 * @newsk: buffer to insert
3602 * @list: list to use
3603 *
3604 * Place a packet after a given packet in a list. The list locks are taken
3605 * and this function is atomic with respect to other list locked calls.
3606 * A buffer cannot be placed on two lists at the same time.
3607 */
3608void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
3609{
3610 unsigned long flags;
3611
3612 spin_lock_irqsave(&list->lock, flags);
3613 __skb_queue_after(list, old, newsk);
3614 spin_unlock_irqrestore(&list->lock, flags);
3615}
3616EXPORT_SYMBOL(skb_append);
3617
3618static inline void skb_split_inside_header(struct sk_buff *skb,
3619 struct sk_buff* skb1,
3620 const u32 len, const int pos)
3621{
3622 int i;
3623
3624 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
3625 pos - len);
3626 /* And move data appendix as is. */
3627 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
3628 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
3629
3630 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
3631 skb_shinfo(skb)->nr_frags = 0;
3632 skb1->data_len = skb->data_len;
3633 skb1->len += skb1->data_len;
3634 skb->data_len = 0;
3635 skb->len = len;
3636 skb_set_tail_pointer(skb, len);
3637}
3638
3639static inline void skb_split_no_header(struct sk_buff *skb,
3640 struct sk_buff* skb1,
3641 const u32 len, int pos)
3642{
3643 int i, k = 0;
3644 const int nfrags = skb_shinfo(skb)->nr_frags;
3645
3646 skb_shinfo(skb)->nr_frags = 0;
3647 skb1->len = skb1->data_len = skb->len - len;
3648 skb->len = len;
3649 skb->data_len = len - pos;
3650
3651 for (i = 0; i < nfrags; i++) {
3652 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
3653
3654 if (pos + size > len) {
3655 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
3656
3657 if (pos < len) {
3658 /* Split frag.
3659 * We have two variants in this case:
3660 * 1. Move all the frag to the second
3661 * part, if it is possible. F.e.
3662 * this approach is mandatory for TUX,
3663 * where splitting is expensive.
3664 * 2. Split is accurately. We make this.
3665 */
3666 skb_frag_ref(skb, i);
3667 skb_frag_off_add(&skb_shinfo(skb1)->frags[0], len - pos);
3668 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
3669 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
3670 skb_shinfo(skb)->nr_frags++;
3671 }
3672 k++;
3673 } else
3674 skb_shinfo(skb)->nr_frags++;
3675 pos += size;
3676 }
3677 skb_shinfo(skb1)->nr_frags = k;
3678}
3679
3680/**
3681 * skb_split - Split fragmented skb to two parts at length len.
3682 * @skb: the buffer to split
3683 * @skb1: the buffer to receive the second part
3684 * @len: new length for skb
3685 */
3686void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
3687{
3688 int pos = skb_headlen(skb);
3689 const int zc_flags = SKBFL_SHARED_FRAG | SKBFL_PURE_ZEROCOPY;
3690
3691 skb_zcopy_downgrade_managed(skb);
3692
3693 skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & zc_flags;
3694 skb_zerocopy_clone(skb1, skb, 0);
3695 if (len < pos) /* Split line is inside header. */
3696 skb_split_inside_header(skb, skb1, len, pos);
3697 else /* Second chunk has no header, nothing to copy. */
3698 skb_split_no_header(skb, skb1, len, pos);
3699}
3700EXPORT_SYMBOL(skb_split);
3701
3702/* Shifting from/to a cloned skb is a no-go.
3703 *
3704 * Caller cannot keep skb_shinfo related pointers past calling here!
3705 */
3706static int skb_prepare_for_shift(struct sk_buff *skb)
3707{
3708 return skb_unclone_keeptruesize(skb, GFP_ATOMIC);
3709}
3710
3711/**
3712 * skb_shift - Shifts paged data partially from skb to another
3713 * @tgt: buffer into which tail data gets added
3714 * @skb: buffer from which the paged data comes from
3715 * @shiftlen: shift up to this many bytes
3716 *
3717 * Attempts to shift up to shiftlen worth of bytes, which may be less than
3718 * the length of the skb, from skb to tgt. Returns number bytes shifted.
3719 * It's up to caller to free skb if everything was shifted.
3720 *
3721 * If @tgt runs out of frags, the whole operation is aborted.
3722 *
3723 * Skb cannot include anything else but paged data while tgt is allowed
3724 * to have non-paged data as well.
3725 *
3726 * TODO: full sized shift could be optimized but that would need
3727 * specialized skb free'er to handle frags without up-to-date nr_frags.
3728 */
3729int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
3730{
3731 int from, to, merge, todo;
3732 skb_frag_t *fragfrom, *fragto;
3733
3734 BUG_ON(shiftlen > skb->len);
3735
3736 if (skb_headlen(skb))
3737 return 0;
3738 if (skb_zcopy(tgt) || skb_zcopy(skb))
3739 return 0;
3740
3741 todo = shiftlen;
3742 from = 0;
3743 to = skb_shinfo(tgt)->nr_frags;
3744 fragfrom = &skb_shinfo(skb)->frags[from];
3745
3746 /* Actual merge is delayed until the point when we know we can
3747 * commit all, so that we don't have to undo partial changes
3748 */
3749 if (!to ||
3750 !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
3751 skb_frag_off(fragfrom))) {
3752 merge = -1;
3753 } else {
3754 merge = to - 1;
3755
3756 todo -= skb_frag_size(fragfrom);
3757 if (todo < 0) {
3758 if (skb_prepare_for_shift(skb) ||
3759 skb_prepare_for_shift(tgt))
3760 return 0;
3761
3762 /* All previous frag pointers might be stale! */
3763 fragfrom = &skb_shinfo(skb)->frags[from];
3764 fragto = &skb_shinfo(tgt)->frags[merge];
3765
3766 skb_frag_size_add(fragto, shiftlen);
3767 skb_frag_size_sub(fragfrom, shiftlen);
3768 skb_frag_off_add(fragfrom, shiftlen);
3769
3770 goto onlymerged;
3771 }
3772
3773 from++;
3774 }
3775
3776 /* Skip full, not-fitting skb to avoid expensive operations */
3777 if ((shiftlen == skb->len) &&
3778 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
3779 return 0;
3780
3781 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
3782 return 0;
3783
3784 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
3785 if (to == MAX_SKB_FRAGS)
3786 return 0;
3787
3788 fragfrom = &skb_shinfo(skb)->frags[from];
3789 fragto = &skb_shinfo(tgt)->frags[to];
3790
3791 if (todo >= skb_frag_size(fragfrom)) {
3792 *fragto = *fragfrom;
3793 todo -= skb_frag_size(fragfrom);
3794 from++;
3795 to++;
3796
3797 } else {
3798 __skb_frag_ref(fragfrom);
3799 skb_frag_page_copy(fragto, fragfrom);
3800 skb_frag_off_copy(fragto, fragfrom);
3801 skb_frag_size_set(fragto, todo);
3802
3803 skb_frag_off_add(fragfrom, todo);
3804 skb_frag_size_sub(fragfrom, todo);
3805 todo = 0;
3806
3807 to++;
3808 break;
3809 }
3810 }
3811
3812 /* Ready to "commit" this state change to tgt */
3813 skb_shinfo(tgt)->nr_frags = to;
3814
3815 if (merge >= 0) {
3816 fragfrom = &skb_shinfo(skb)->frags[0];
3817 fragto = &skb_shinfo(tgt)->frags[merge];
3818
3819 skb_frag_size_add(fragto, skb_frag_size(fragfrom));
3820 __skb_frag_unref(fragfrom, skb->pp_recycle);
3821 }
3822
3823 /* Reposition in the original skb */
3824 to = 0;
3825 while (from < skb_shinfo(skb)->nr_frags)
3826 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
3827 skb_shinfo(skb)->nr_frags = to;
3828
3829 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
3830
3831onlymerged:
3832 /* Most likely the tgt won't ever need its checksum anymore, skb on
3833 * the other hand might need it if it needs to be resent
3834 */
3835 tgt->ip_summed = CHECKSUM_PARTIAL;
3836 skb->ip_summed = CHECKSUM_PARTIAL;
3837
3838 skb_len_add(skb, -shiftlen);
3839 skb_len_add(tgt, shiftlen);
3840
3841 return shiftlen;
3842}
3843
3844/**
3845 * skb_prepare_seq_read - Prepare a sequential read of skb data
3846 * @skb: the buffer to read
3847 * @from: lower offset of data to be read
3848 * @to: upper offset of data to be read
3849 * @st: state variable
3850 *
3851 * Initializes the specified state variable. Must be called before
3852 * invoking skb_seq_read() for the first time.
3853 */
3854void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
3855 unsigned int to, struct skb_seq_state *st)
3856{
3857 st->lower_offset = from;
3858 st->upper_offset = to;
3859 st->root_skb = st->cur_skb = skb;
3860 st->frag_idx = st->stepped_offset = 0;
3861 st->frag_data = NULL;
3862 st->frag_off = 0;
3863}
3864EXPORT_SYMBOL(skb_prepare_seq_read);
3865
3866/**
3867 * skb_seq_read - Sequentially read skb data
3868 * @consumed: number of bytes consumed by the caller so far
3869 * @data: destination pointer for data to be returned
3870 * @st: state variable
3871 *
3872 * Reads a block of skb data at @consumed relative to the
3873 * lower offset specified to skb_prepare_seq_read(). Assigns
3874 * the head of the data block to @data and returns the length
3875 * of the block or 0 if the end of the skb data or the upper
3876 * offset has been reached.
3877 *
3878 * The caller is not required to consume all of the data
3879 * returned, i.e. @consumed is typically set to the number
3880 * of bytes already consumed and the next call to
3881 * skb_seq_read() will return the remaining part of the block.
3882 *
3883 * Note 1: The size of each block of data returned can be arbitrary,
3884 * this limitation is the cost for zerocopy sequential
3885 * reads of potentially non linear data.
3886 *
3887 * Note 2: Fragment lists within fragments are not implemented
3888 * at the moment, state->root_skb could be replaced with
3889 * a stack for this purpose.
3890 */
3891unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
3892 struct skb_seq_state *st)
3893{
3894 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
3895 skb_frag_t *frag;
3896
3897 if (unlikely(abs_offset >= st->upper_offset)) {
3898 if (st->frag_data) {
3899 kunmap_atomic(st->frag_data);
3900 st->frag_data = NULL;
3901 }
3902 return 0;
3903 }
3904
3905next_skb:
3906 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
3907
3908 if (abs_offset < block_limit && !st->frag_data) {
3909 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
3910 return block_limit - abs_offset;
3911 }
3912
3913 if (st->frag_idx == 0 && !st->frag_data)
3914 st->stepped_offset += skb_headlen(st->cur_skb);
3915
3916 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
3917 unsigned int pg_idx, pg_off, pg_sz;
3918
3919 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
3920
3921 pg_idx = 0;
3922 pg_off = skb_frag_off(frag);
3923 pg_sz = skb_frag_size(frag);
3924
3925 if (skb_frag_must_loop(skb_frag_page(frag))) {
3926 pg_idx = (pg_off + st->frag_off) >> PAGE_SHIFT;
3927 pg_off = offset_in_page(pg_off + st->frag_off);
3928 pg_sz = min_t(unsigned int, pg_sz - st->frag_off,
3929 PAGE_SIZE - pg_off);
3930 }
3931
3932 block_limit = pg_sz + st->stepped_offset;
3933 if (abs_offset < block_limit) {
3934 if (!st->frag_data)
3935 st->frag_data = kmap_atomic(skb_frag_page(frag) + pg_idx);
3936
3937 *data = (u8 *)st->frag_data + pg_off +
3938 (abs_offset - st->stepped_offset);
3939
3940 return block_limit - abs_offset;
3941 }
3942
3943 if (st->frag_data) {
3944 kunmap_atomic(st->frag_data);
3945 st->frag_data = NULL;
3946 }
3947
3948 st->stepped_offset += pg_sz;
3949 st->frag_off += pg_sz;
3950 if (st->frag_off == skb_frag_size(frag)) {
3951 st->frag_off = 0;
3952 st->frag_idx++;
3953 }
3954 }
3955
3956 if (st->frag_data) {
3957 kunmap_atomic(st->frag_data);
3958 st->frag_data = NULL;
3959 }
3960
3961 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
3962 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
3963 st->frag_idx = 0;
3964 goto next_skb;
3965 } else if (st->cur_skb->next) {
3966 st->cur_skb = st->cur_skb->next;
3967 st->frag_idx = 0;
3968 goto next_skb;
3969 }
3970
3971 return 0;
3972}
3973EXPORT_SYMBOL(skb_seq_read);
3974
3975/**
3976 * skb_abort_seq_read - Abort a sequential read of skb data
3977 * @st: state variable
3978 *
3979 * Must be called if skb_seq_read() was not called until it
3980 * returned 0.
3981 */
3982void skb_abort_seq_read(struct skb_seq_state *st)
3983{
3984 if (st->frag_data)
3985 kunmap_atomic(st->frag_data);
3986}
3987EXPORT_SYMBOL(skb_abort_seq_read);
3988
3989#define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
3990
3991static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
3992 struct ts_config *conf,
3993 struct ts_state *state)
3994{
3995 return skb_seq_read(offset, text, TS_SKB_CB(state));
3996}
3997
3998static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
3999{
4000 skb_abort_seq_read(TS_SKB_CB(state));
4001}
4002
4003/**
4004 * skb_find_text - Find a text pattern in skb data
4005 * @skb: the buffer to look in
4006 * @from: search offset
4007 * @to: search limit
4008 * @config: textsearch configuration
4009 *
4010 * Finds a pattern in the skb data according to the specified
4011 * textsearch configuration. Use textsearch_next() to retrieve
4012 * subsequent occurrences of the pattern. Returns the offset
4013 * to the first occurrence or UINT_MAX if no match was found.
4014 */
4015unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
4016 unsigned int to, struct ts_config *config)
4017{
4018 struct ts_state state;
4019 unsigned int ret;
4020
4021 BUILD_BUG_ON(sizeof(struct skb_seq_state) > sizeof(state.cb));
4022
4023 config->get_next_block = skb_ts_get_next_block;
4024 config->finish = skb_ts_finish;
4025
4026 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
4027
4028 ret = textsearch_find(config, &state);
4029 return (ret <= to - from ? ret : UINT_MAX);
4030}
4031EXPORT_SYMBOL(skb_find_text);
4032
4033int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
4034 int offset, size_t size)
4035{
4036 int i = skb_shinfo(skb)->nr_frags;
4037
4038 if (skb_can_coalesce(skb, i, page, offset)) {
4039 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
4040 } else if (i < MAX_SKB_FRAGS) {
4041 skb_zcopy_downgrade_managed(skb);
4042 get_page(page);
4043 skb_fill_page_desc_noacc(skb, i, page, offset, size);
4044 } else {
4045 return -EMSGSIZE;
4046 }
4047
4048 return 0;
4049}
4050EXPORT_SYMBOL_GPL(skb_append_pagefrags);
4051
4052/**
4053 * skb_pull_rcsum - pull skb and update receive checksum
4054 * @skb: buffer to update
4055 * @len: length of data pulled
4056 *
4057 * This function performs an skb_pull on the packet and updates
4058 * the CHECKSUM_COMPLETE checksum. It should be used on
4059 * receive path processing instead of skb_pull unless you know
4060 * that the checksum difference is zero (e.g., a valid IP header)
4061 * or you are setting ip_summed to CHECKSUM_NONE.
4062 */
4063void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
4064{
4065 unsigned char *data = skb->data;
4066
4067 BUG_ON(len > skb->len);
4068 __skb_pull(skb, len);
4069 skb_postpull_rcsum(skb, data, len);
4070 return skb->data;
4071}
4072EXPORT_SYMBOL_GPL(skb_pull_rcsum);
4073
4074static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
4075{
4076 skb_frag_t head_frag;
4077 struct page *page;
4078
4079 page = virt_to_head_page(frag_skb->head);
4080 __skb_frag_set_page(&head_frag, page);
4081 skb_frag_off_set(&head_frag, frag_skb->data -
4082 (unsigned char *)page_address(page));
4083 skb_frag_size_set(&head_frag, skb_headlen(frag_skb));
4084 return head_frag;
4085}
4086
4087struct sk_buff *skb_segment_list(struct sk_buff *skb,
4088 netdev_features_t features,
4089 unsigned int offset)
4090{
4091 struct sk_buff *list_skb = skb_shinfo(skb)->frag_list;
4092 unsigned int tnl_hlen = skb_tnl_header_len(skb);
4093 unsigned int delta_truesize = 0;
4094 unsigned int delta_len = 0;
4095 struct sk_buff *tail = NULL;
4096 struct sk_buff *nskb, *tmp;
4097 int len_diff, err;
4098
4099 skb_push(skb, -skb_network_offset(skb) + offset);
4100
4101 skb_shinfo(skb)->frag_list = NULL;
4102
4103 while (list_skb) {
4104 nskb = list_skb;
4105 list_skb = list_skb->next;
4106
4107 err = 0;
4108 delta_truesize += nskb->truesize;
4109 if (skb_shared(nskb)) {
4110 tmp = skb_clone(nskb, GFP_ATOMIC);
4111 if (tmp) {
4112 consume_skb(nskb);
4113 nskb = tmp;
4114 err = skb_unclone(nskb, GFP_ATOMIC);
4115 } else {
4116 err = -ENOMEM;
4117 }
4118 }
4119
4120 if (!tail)
4121 skb->next = nskb;
4122 else
4123 tail->next = nskb;
4124
4125 if (unlikely(err)) {
4126 nskb->next = list_skb;
4127 goto err_linearize;
4128 }
4129
4130 tail = nskb;
4131
4132 delta_len += nskb->len;
4133
4134 skb_push(nskb, -skb_network_offset(nskb) + offset);
4135
4136 skb_release_head_state(nskb);
4137 len_diff = skb_network_header_len(nskb) - skb_network_header_len(skb);
4138 __copy_skb_header(nskb, skb);
4139
4140 skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
4141 nskb->transport_header += len_diff;
4142 skb_copy_from_linear_data_offset(skb, -tnl_hlen,
4143 nskb->data - tnl_hlen,
4144 offset + tnl_hlen);
4145
4146 if (skb_needs_linearize(nskb, features) &&
4147 __skb_linearize(nskb))
4148 goto err_linearize;
4149 }
4150
4151 skb->truesize = skb->truesize - delta_truesize;
4152 skb->data_len = skb->data_len - delta_len;
4153 skb->len = skb->len - delta_len;
4154
4155 skb_gso_reset(skb);
4156
4157 skb->prev = tail;
4158
4159 if (skb_needs_linearize(skb, features) &&
4160 __skb_linearize(skb))
4161 goto err_linearize;
4162
4163 skb_get(skb);
4164
4165 return skb;
4166
4167err_linearize:
4168 kfree_skb_list(skb->next);
4169 skb->next = NULL;
4170 return ERR_PTR(-ENOMEM);
4171}
4172EXPORT_SYMBOL_GPL(skb_segment_list);
4173
4174/**
4175 * skb_segment - Perform protocol segmentation on skb.
4176 * @head_skb: buffer to segment
4177 * @features: features for the output path (see dev->features)
4178 *
4179 * This function performs segmentation on the given skb. It returns
4180 * a pointer to the first in a list of new skbs for the segments.
4181 * In case of error it returns ERR_PTR(err).
4182 */
4183struct sk_buff *skb_segment(struct sk_buff *head_skb,
4184 netdev_features_t features)
4185{
4186 struct sk_buff *segs = NULL;
4187 struct sk_buff *tail = NULL;
4188 struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
4189 skb_frag_t *frag = skb_shinfo(head_skb)->frags;
4190 unsigned int mss = skb_shinfo(head_skb)->gso_size;
4191 unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
4192 struct sk_buff *frag_skb = head_skb;
4193 unsigned int offset = doffset;
4194 unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
4195 unsigned int partial_segs = 0;
4196 unsigned int headroom;
4197 unsigned int len = head_skb->len;
4198 __be16 proto;
4199 bool csum, sg;
4200 int nfrags = skb_shinfo(head_skb)->nr_frags;
4201 int err = -ENOMEM;
4202 int i = 0;
4203 int pos;
4204
4205 if ((skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY) &&
4206 mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb)) {
4207 struct sk_buff *check_skb;
4208
4209 for (check_skb = list_skb; check_skb; check_skb = check_skb->next) {
4210 if (skb_headlen(check_skb) && !check_skb->head_frag) {
4211 /* gso_size is untrusted, and we have a frag_list with
4212 * a linear non head_frag item.
4213 *
4214 * If head_skb's headlen does not fit requested gso_size,
4215 * it means that the frag_list members do NOT terminate
4216 * on exact gso_size boundaries. Hence we cannot perform
4217 * skb_frag_t page sharing. Therefore we must fallback to
4218 * copying the frag_list skbs; we do so by disabling SG.
4219 */
4220 features &= ~NETIF_F_SG;
4221 break;
4222 }
4223 }
4224 }
4225
4226 __skb_push(head_skb, doffset);
4227 proto = skb_network_protocol(head_skb, NULL);
4228 if (unlikely(!proto))
4229 return ERR_PTR(-EINVAL);
4230
4231 sg = !!(features & NETIF_F_SG);
4232 csum = !!can_checksum_protocol(features, proto);
4233
4234 if (sg && csum && (mss != GSO_BY_FRAGS)) {
4235 if (!(features & NETIF_F_GSO_PARTIAL)) {
4236 struct sk_buff *iter;
4237 unsigned int frag_len;
4238
4239 if (!list_skb ||
4240 !net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
4241 goto normal;
4242
4243 /* If we get here then all the required
4244 * GSO features except frag_list are supported.
4245 * Try to split the SKB to multiple GSO SKBs
4246 * with no frag_list.
4247 * Currently we can do that only when the buffers don't
4248 * have a linear part and all the buffers except
4249 * the last are of the same length.
4250 */
4251 frag_len = list_skb->len;
4252 skb_walk_frags(head_skb, iter) {
4253 if (frag_len != iter->len && iter->next)
4254 goto normal;
4255 if (skb_headlen(iter) && !iter->head_frag)
4256 goto normal;
4257
4258 len -= iter->len;
4259 }
4260
4261 if (len != frag_len)
4262 goto normal;
4263 }
4264
4265 /* GSO partial only requires that we trim off any excess that
4266 * doesn't fit into an MSS sized block, so take care of that
4267 * now.
4268 */
4269 partial_segs = len / mss;
4270 if (partial_segs > 1)
4271 mss *= partial_segs;
4272 else
4273 partial_segs = 0;
4274 }
4275
4276normal:
4277 headroom = skb_headroom(head_skb);
4278 pos = skb_headlen(head_skb);
4279
4280 do {
4281 struct sk_buff *nskb;
4282 skb_frag_t *nskb_frag;
4283 int hsize;
4284 int size;
4285
4286 if (unlikely(mss == GSO_BY_FRAGS)) {
4287 len = list_skb->len;
4288 } else {
4289 len = head_skb->len - offset;
4290 if (len > mss)
4291 len = mss;
4292 }
4293
4294 hsize = skb_headlen(head_skb) - offset;
4295
4296 if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
4297 (skb_headlen(list_skb) == len || sg)) {
4298 BUG_ON(skb_headlen(list_skb) > len);
4299
4300 i = 0;
4301 nfrags = skb_shinfo(list_skb)->nr_frags;
4302 frag = skb_shinfo(list_skb)->frags;
4303 frag_skb = list_skb;
4304 pos += skb_headlen(list_skb);
4305
4306 while (pos < offset + len) {
4307 BUG_ON(i >= nfrags);
4308
4309 size = skb_frag_size(frag);
4310 if (pos + size > offset + len)
4311 break;
4312
4313 i++;
4314 pos += size;
4315 frag++;
4316 }
4317
4318 nskb = skb_clone(list_skb, GFP_ATOMIC);
4319 list_skb = list_skb->next;
4320
4321 if (unlikely(!nskb))
4322 goto err;
4323
4324 if (unlikely(pskb_trim(nskb, len))) {
4325 kfree_skb(nskb);
4326 goto err;
4327 }
4328
4329 hsize = skb_end_offset(nskb);
4330 if (skb_cow_head(nskb, doffset + headroom)) {
4331 kfree_skb(nskb);
4332 goto err;
4333 }
4334
4335 nskb->truesize += skb_end_offset(nskb) - hsize;
4336 skb_release_head_state(nskb);
4337 __skb_push(nskb, doffset);
4338 } else {
4339 if (hsize < 0)
4340 hsize = 0;
4341 if (hsize > len || !sg)
4342 hsize = len;
4343
4344 nskb = __alloc_skb(hsize + doffset + headroom,
4345 GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
4346 NUMA_NO_NODE);
4347
4348 if (unlikely(!nskb))
4349 goto err;
4350
4351 skb_reserve(nskb, headroom);
4352 __skb_put(nskb, doffset);
4353 }
4354
4355 if (segs)
4356 tail->next = nskb;
4357 else
4358 segs = nskb;
4359 tail = nskb;
4360
4361 __copy_skb_header(nskb, head_skb);
4362
4363 skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
4364 skb_reset_mac_len(nskb);
4365
4366 skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
4367 nskb->data - tnl_hlen,
4368 doffset + tnl_hlen);
4369
4370 if (nskb->len == len + doffset)
4371 goto perform_csum_check;
4372
4373 if (!sg) {
4374 if (!csum) {
4375 if (!nskb->remcsum_offload)
4376 nskb->ip_summed = CHECKSUM_NONE;
4377 SKB_GSO_CB(nskb)->csum =
4378 skb_copy_and_csum_bits(head_skb, offset,
4379 skb_put(nskb,
4380 len),
4381 len);
4382 SKB_GSO_CB(nskb)->csum_start =
4383 skb_headroom(nskb) + doffset;
4384 } else {
4385 if (skb_copy_bits(head_skb, offset, skb_put(nskb, len), len))
4386 goto err;
4387 }
4388 continue;
4389 }
4390
4391 nskb_frag = skb_shinfo(nskb)->frags;
4392
4393 skb_copy_from_linear_data_offset(head_skb, offset,
4394 skb_put(nskb, hsize), hsize);
4395
4396 skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
4397 SKBFL_SHARED_FRAG;
4398
4399 if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
4400 skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
4401 goto err;
4402
4403 while (pos < offset + len) {
4404 if (i >= nfrags) {
4405 i = 0;
4406 nfrags = skb_shinfo(list_skb)->nr_frags;
4407 frag = skb_shinfo(list_skb)->frags;
4408 frag_skb = list_skb;
4409 if (!skb_headlen(list_skb)) {
4410 BUG_ON(!nfrags);
4411 } else {
4412 BUG_ON(!list_skb->head_frag);
4413
4414 /* to make room for head_frag. */
4415 i--;
4416 frag--;
4417 }
4418 if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
4419 skb_zerocopy_clone(nskb, frag_skb,
4420 GFP_ATOMIC))
4421 goto err;
4422
4423 list_skb = list_skb->next;
4424 }
4425
4426 if (unlikely(skb_shinfo(nskb)->nr_frags >=
4427 MAX_SKB_FRAGS)) {
4428 net_warn_ratelimited(
4429 "skb_segment: too many frags: %u %u\n",
4430 pos, mss);
4431 err = -EINVAL;
4432 goto err;
4433 }
4434
4435 *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
4436 __skb_frag_ref(nskb_frag);
4437 size = skb_frag_size(nskb_frag);
4438
4439 if (pos < offset) {
4440 skb_frag_off_add(nskb_frag, offset - pos);
4441 skb_frag_size_sub(nskb_frag, offset - pos);
4442 }
4443
4444 skb_shinfo(nskb)->nr_frags++;
4445
4446 if (pos + size <= offset + len) {
4447 i++;
4448 frag++;
4449 pos += size;
4450 } else {
4451 skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
4452 goto skip_fraglist;
4453 }
4454
4455 nskb_frag++;
4456 }
4457
4458skip_fraglist:
4459 nskb->data_len = len - hsize;
4460 nskb->len += nskb->data_len;
4461 nskb->truesize += nskb->data_len;
4462
4463perform_csum_check:
4464 if (!csum) {
4465 if (skb_has_shared_frag(nskb) &&
4466 __skb_linearize(nskb))
4467 goto err;
4468
4469 if (!nskb->remcsum_offload)
4470 nskb->ip_summed = CHECKSUM_NONE;
4471 SKB_GSO_CB(nskb)->csum =
4472 skb_checksum(nskb, doffset,
4473 nskb->len - doffset, 0);
4474 SKB_GSO_CB(nskb)->csum_start =
4475 skb_headroom(nskb) + doffset;
4476 }
4477 } while ((offset += len) < head_skb->len);
4478
4479 /* Some callers want to get the end of the list.
4480 * Put it in segs->prev to avoid walking the list.
4481 * (see validate_xmit_skb_list() for example)
4482 */
4483 segs->prev = tail;
4484
4485 if (partial_segs) {
4486 struct sk_buff *iter;
4487 int type = skb_shinfo(head_skb)->gso_type;
4488 unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
4489
4490 /* Update type to add partial and then remove dodgy if set */
4491 type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
4492 type &= ~SKB_GSO_DODGY;
4493
4494 /* Update GSO info and prepare to start updating headers on
4495 * our way back down the stack of protocols.
4496 */
4497 for (iter = segs; iter; iter = iter->next) {
4498 skb_shinfo(iter)->gso_size = gso_size;
4499 skb_shinfo(iter)->gso_segs = partial_segs;
4500 skb_shinfo(iter)->gso_type = type;
4501 SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
4502 }
4503
4504 if (tail->len - doffset <= gso_size)
4505 skb_shinfo(tail)->gso_size = 0;
4506 else if (tail != segs)
4507 skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
4508 }
4509
4510 /* Following permits correct backpressure, for protocols
4511 * using skb_set_owner_w().
4512 * Idea is to tranfert ownership from head_skb to last segment.
4513 */
4514 if (head_skb->destructor == sock_wfree) {
4515 swap(tail->truesize, head_skb->truesize);
4516 swap(tail->destructor, head_skb->destructor);
4517 swap(tail->sk, head_skb->sk);
4518 }
4519 return segs;
4520
4521err:
4522 kfree_skb_list(segs);
4523 return ERR_PTR(err);
4524}
4525EXPORT_SYMBOL_GPL(skb_segment);
4526
4527#ifdef CONFIG_SKB_EXTENSIONS
4528#define SKB_EXT_ALIGN_VALUE 8
4529#define SKB_EXT_CHUNKSIZEOF(x) (ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE)
4530
4531static const u8 skb_ext_type_len[] = {
4532#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4533 [SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info),
4534#endif
4535#ifdef CONFIG_XFRM
4536 [SKB_EXT_SEC_PATH] = SKB_EXT_CHUNKSIZEOF(struct sec_path),
4537#endif
4538#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4539 [TC_SKB_EXT] = SKB_EXT_CHUNKSIZEOF(struct tc_skb_ext),
4540#endif
4541#if IS_ENABLED(CONFIG_MPTCP)
4542 [SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext),
4543#endif
4544#if IS_ENABLED(CONFIG_MCTP_FLOWS)
4545 [SKB_EXT_MCTP] = SKB_EXT_CHUNKSIZEOF(struct mctp_flow),
4546#endif
4547};
4548
4549static __always_inline unsigned int skb_ext_total_length(void)
4550{
4551 return SKB_EXT_CHUNKSIZEOF(struct skb_ext) +
4552#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4553 skb_ext_type_len[SKB_EXT_BRIDGE_NF] +
4554#endif
4555#ifdef CONFIG_XFRM
4556 skb_ext_type_len[SKB_EXT_SEC_PATH] +
4557#endif
4558#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4559 skb_ext_type_len[TC_SKB_EXT] +
4560#endif
4561#if IS_ENABLED(CONFIG_MPTCP)
4562 skb_ext_type_len[SKB_EXT_MPTCP] +
4563#endif
4564#if IS_ENABLED(CONFIG_MCTP_FLOWS)
4565 skb_ext_type_len[SKB_EXT_MCTP] +
4566#endif
4567 0;
4568}
4569
4570static void skb_extensions_init(void)
4571{
4572 BUILD_BUG_ON(SKB_EXT_NUM >= 8);
4573 BUILD_BUG_ON(skb_ext_total_length() > 255);
4574
4575 skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache",
4576 SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),
4577 0,
4578 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4579 NULL);
4580}
4581#else
4582static void skb_extensions_init(void) {}
4583#endif
4584
4585void __init skb_init(void)
4586{
4587 skbuff_head_cache = kmem_cache_create_usercopy("skbuff_head_cache",
4588 sizeof(struct sk_buff),
4589 0,
4590 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4591 offsetof(struct sk_buff, cb),
4592 sizeof_field(struct sk_buff, cb),
4593 NULL);
4594 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
4595 sizeof(struct sk_buff_fclones),
4596 0,
4597 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4598 NULL);
4599 skb_extensions_init();
4600}
4601
4602static int
4603__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len,
4604 unsigned int recursion_level)
4605{
4606 int start = skb_headlen(skb);
4607 int i, copy = start - offset;
4608 struct sk_buff *frag_iter;
4609 int elt = 0;
4610
4611 if (unlikely(recursion_level >= 24))
4612 return -EMSGSIZE;
4613
4614 if (copy > 0) {
4615 if (copy > len)
4616 copy = len;
4617 sg_set_buf(sg, skb->data + offset, copy);
4618 elt++;
4619 if ((len -= copy) == 0)
4620 return elt;
4621 offset += copy;
4622 }
4623
4624 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
4625 int end;
4626
4627 WARN_ON(start > offset + len);
4628
4629 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
4630 if ((copy = end - offset) > 0) {
4631 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
4632 if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4633 return -EMSGSIZE;
4634
4635 if (copy > len)
4636 copy = len;
4637 sg_set_page(&sg[elt], skb_frag_page(frag), copy,
4638 skb_frag_off(frag) + offset - start);
4639 elt++;
4640 if (!(len -= copy))
4641 return elt;
4642 offset += copy;
4643 }
4644 start = end;
4645 }
4646
4647 skb_walk_frags(skb, frag_iter) {
4648 int end, ret;
4649
4650 WARN_ON(start > offset + len);
4651
4652 end = start + frag_iter->len;
4653 if ((copy = end - offset) > 0) {
4654 if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4655 return -EMSGSIZE;
4656
4657 if (copy > len)
4658 copy = len;
4659 ret = __skb_to_sgvec(frag_iter, sg+elt, offset - start,
4660 copy, recursion_level + 1);
4661 if (unlikely(ret < 0))
4662 return ret;
4663 elt += ret;
4664 if ((len -= copy) == 0)
4665 return elt;
4666 offset += copy;
4667 }
4668 start = end;
4669 }
4670 BUG_ON(len);
4671 return elt;
4672}
4673
4674/**
4675 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
4676 * @skb: Socket buffer containing the buffers to be mapped
4677 * @sg: The scatter-gather list to map into
4678 * @offset: The offset into the buffer's contents to start mapping
4679 * @len: Length of buffer space to be mapped
4680 *
4681 * Fill the specified scatter-gather list with mappings/pointers into a
4682 * region of the buffer space attached to a socket buffer. Returns either
4683 * the number of scatterlist items used, or -EMSGSIZE if the contents
4684 * could not fit.
4685 */
4686int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
4687{
4688 int nsg = __skb_to_sgvec(skb, sg, offset, len, 0);
4689
4690 if (nsg <= 0)
4691 return nsg;
4692
4693 sg_mark_end(&sg[nsg - 1]);
4694
4695 return nsg;
4696}
4697EXPORT_SYMBOL_GPL(skb_to_sgvec);
4698
4699/* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
4700 * sglist without mark the sg which contain last skb data as the end.
4701 * So the caller can mannipulate sg list as will when padding new data after
4702 * the first call without calling sg_unmark_end to expend sg list.
4703 *
4704 * Scenario to use skb_to_sgvec_nomark:
4705 * 1. sg_init_table
4706 * 2. skb_to_sgvec_nomark(payload1)
4707 * 3. skb_to_sgvec_nomark(payload2)
4708 *
4709 * This is equivalent to:
4710 * 1. sg_init_table
4711 * 2. skb_to_sgvec(payload1)
4712 * 3. sg_unmark_end
4713 * 4. skb_to_sgvec(payload2)
4714 *
4715 * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
4716 * is more preferable.
4717 */
4718int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
4719 int offset, int len)
4720{
4721 return __skb_to_sgvec(skb, sg, offset, len, 0);
4722}
4723EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
4724
4725
4726
4727/**
4728 * skb_cow_data - Check that a socket buffer's data buffers are writable
4729 * @skb: The socket buffer to check.
4730 * @tailbits: Amount of trailing space to be added
4731 * @trailer: Returned pointer to the skb where the @tailbits space begins
4732 *
4733 * Make sure that the data buffers attached to a socket buffer are
4734 * writable. If they are not, private copies are made of the data buffers
4735 * and the socket buffer is set to use these instead.
4736 *
4737 * If @tailbits is given, make sure that there is space to write @tailbits
4738 * bytes of data beyond current end of socket buffer. @trailer will be
4739 * set to point to the skb in which this space begins.
4740 *
4741 * The number of scatterlist elements required to completely map the
4742 * COW'd and extended socket buffer will be returned.
4743 */
4744int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
4745{
4746 int copyflag;
4747 int elt;
4748 struct sk_buff *skb1, **skb_p;
4749
4750 /* If skb is cloned or its head is paged, reallocate
4751 * head pulling out all the pages (pages are considered not writable
4752 * at the moment even if they are anonymous).
4753 */
4754 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
4755 !__pskb_pull_tail(skb, __skb_pagelen(skb)))
4756 return -ENOMEM;
4757
4758 /* Easy case. Most of packets will go this way. */
4759 if (!skb_has_frag_list(skb)) {
4760 /* A little of trouble, not enough of space for trailer.
4761 * This should not happen, when stack is tuned to generate
4762 * good frames. OK, on miss we reallocate and reserve even more
4763 * space, 128 bytes is fair. */
4764
4765 if (skb_tailroom(skb) < tailbits &&
4766 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
4767 return -ENOMEM;
4768
4769 /* Voila! */
4770 *trailer = skb;
4771 return 1;
4772 }
4773
4774 /* Misery. We are in troubles, going to mincer fragments... */
4775
4776 elt = 1;
4777 skb_p = &skb_shinfo(skb)->frag_list;
4778 copyflag = 0;
4779
4780 while ((skb1 = *skb_p) != NULL) {
4781 int ntail = 0;
4782
4783 /* The fragment is partially pulled by someone,
4784 * this can happen on input. Copy it and everything
4785 * after it. */
4786
4787 if (skb_shared(skb1))
4788 copyflag = 1;
4789
4790 /* If the skb is the last, worry about trailer. */
4791
4792 if (skb1->next == NULL && tailbits) {
4793 if (skb_shinfo(skb1)->nr_frags ||
4794 skb_has_frag_list(skb1) ||
4795 skb_tailroom(skb1) < tailbits)
4796 ntail = tailbits + 128;
4797 }
4798
4799 if (copyflag ||
4800 skb_cloned(skb1) ||
4801 ntail ||
4802 skb_shinfo(skb1)->nr_frags ||
4803 skb_has_frag_list(skb1)) {
4804 struct sk_buff *skb2;
4805
4806 /* Fuck, we are miserable poor guys... */
4807 if (ntail == 0)
4808 skb2 = skb_copy(skb1, GFP_ATOMIC);
4809 else
4810 skb2 = skb_copy_expand(skb1,
4811 skb_headroom(skb1),
4812 ntail,
4813 GFP_ATOMIC);
4814 if (unlikely(skb2 == NULL))
4815 return -ENOMEM;
4816
4817 if (skb1->sk)
4818 skb_set_owner_w(skb2, skb1->sk);
4819
4820 /* Looking around. Are we still alive?
4821 * OK, link new skb, drop old one */
4822
4823 skb2->next = skb1->next;
4824 *skb_p = skb2;
4825 kfree_skb(skb1);
4826 skb1 = skb2;
4827 }
4828 elt++;
4829 *trailer = skb1;
4830 skb_p = &skb1->next;
4831 }
4832
4833 return elt;
4834}
4835EXPORT_SYMBOL_GPL(skb_cow_data);
4836
4837static void sock_rmem_free(struct sk_buff *skb)
4838{
4839 struct sock *sk = skb->sk;
4840
4841 atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
4842}
4843
4844static void skb_set_err_queue(struct sk_buff *skb)
4845{
4846 /* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
4847 * So, it is safe to (mis)use it to mark skbs on the error queue.
4848 */
4849 skb->pkt_type = PACKET_OUTGOING;
4850 BUILD_BUG_ON(PACKET_OUTGOING == 0);
4851}
4852
4853/*
4854 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
4855 */
4856int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
4857{
4858 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
4859 (unsigned int)READ_ONCE(sk->sk_rcvbuf))
4860 return -ENOMEM;
4861
4862 skb_orphan(skb);
4863 skb->sk = sk;
4864 skb->destructor = sock_rmem_free;
4865 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
4866 skb_set_err_queue(skb);
4867
4868 /* before exiting rcu section, make sure dst is refcounted */
4869 skb_dst_force(skb);
4870
4871 skb_queue_tail(&sk->sk_error_queue, skb);
4872 if (!sock_flag(sk, SOCK_DEAD))
4873 sk_error_report(sk);
4874 return 0;
4875}
4876EXPORT_SYMBOL(sock_queue_err_skb);
4877
4878static bool is_icmp_err_skb(const struct sk_buff *skb)
4879{
4880 return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
4881 SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6);
4882}
4883
4884struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
4885{
4886 struct sk_buff_head *q = &sk->sk_error_queue;
4887 struct sk_buff *skb, *skb_next = NULL;
4888 bool icmp_next = false;
4889 unsigned long flags;
4890
4891 spin_lock_irqsave(&q->lock, flags);
4892 skb = __skb_dequeue(q);
4893 if (skb && (skb_next = skb_peek(q))) {
4894 icmp_next = is_icmp_err_skb(skb_next);
4895 if (icmp_next)
4896 sk->sk_err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
4897 }
4898 spin_unlock_irqrestore(&q->lock, flags);
4899
4900 if (is_icmp_err_skb(skb) && !icmp_next)
4901 sk->sk_err = 0;
4902
4903 if (skb_next)
4904 sk_error_report(sk);
4905
4906 return skb;
4907}
4908EXPORT_SYMBOL(sock_dequeue_err_skb);
4909
4910/**
4911 * skb_clone_sk - create clone of skb, and take reference to socket
4912 * @skb: the skb to clone
4913 *
4914 * This function creates a clone of a buffer that holds a reference on
4915 * sk_refcnt. Buffers created via this function are meant to be
4916 * returned using sock_queue_err_skb, or free via kfree_skb.
4917 *
4918 * When passing buffers allocated with this function to sock_queue_err_skb
4919 * it is necessary to wrap the call with sock_hold/sock_put in order to
4920 * prevent the socket from being released prior to being enqueued on
4921 * the sk_error_queue.
4922 */
4923struct sk_buff *skb_clone_sk(struct sk_buff *skb)
4924{
4925 struct sock *sk = skb->sk;
4926 struct sk_buff *clone;
4927
4928 if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
4929 return NULL;
4930
4931 clone = skb_clone(skb, GFP_ATOMIC);
4932 if (!clone) {
4933 sock_put(sk);
4934 return NULL;
4935 }
4936
4937 clone->sk = sk;
4938 clone->destructor = sock_efree;
4939
4940 return clone;
4941}
4942EXPORT_SYMBOL(skb_clone_sk);
4943
4944static void __skb_complete_tx_timestamp(struct sk_buff *skb,
4945 struct sock *sk,
4946 int tstype,
4947 bool opt_stats)
4948{
4949 struct sock_exterr_skb *serr;
4950 int err;
4951
4952 BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));
4953
4954 serr = SKB_EXT_ERR(skb);
4955 memset(serr, 0, sizeof(*serr));
4956 serr->ee.ee_errno = ENOMSG;
4957 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
4958 serr->ee.ee_info = tstype;
4959 serr->opt_stats = opt_stats;
4960 serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0;
4961 if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) {
4962 serr->ee.ee_data = skb_shinfo(skb)->tskey;
4963 if (sk_is_tcp(sk))
4964 serr->ee.ee_data -= atomic_read(&sk->sk_tskey);
4965 }
4966
4967 err = sock_queue_err_skb(sk, skb);
4968
4969 if (err)
4970 kfree_skb(skb);
4971}
4972
4973static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
4974{
4975 bool ret;
4976
4977 if (likely(READ_ONCE(sysctl_tstamp_allow_data) || tsonly))
4978 return true;
4979
4980 read_lock_bh(&sk->sk_callback_lock);
4981 ret = sk->sk_socket && sk->sk_socket->file &&
4982 file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
4983 read_unlock_bh(&sk->sk_callback_lock);
4984 return ret;
4985}
4986
4987void skb_complete_tx_timestamp(struct sk_buff *skb,
4988 struct skb_shared_hwtstamps *hwtstamps)
4989{
4990 struct sock *sk = skb->sk;
4991
4992 if (!skb_may_tx_timestamp(sk, false))
4993 goto err;
4994
4995 /* Take a reference to prevent skb_orphan() from freeing the socket,
4996 * but only if the socket refcount is not zero.
4997 */
4998 if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
4999 *skb_hwtstamps(skb) = *hwtstamps;
5000 __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
5001 sock_put(sk);
5002 return;
5003 }
5004
5005err:
5006 kfree_skb(skb);
5007}
5008EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
5009
5010void __skb_tstamp_tx(struct sk_buff *orig_skb,
5011 const struct sk_buff *ack_skb,
5012 struct skb_shared_hwtstamps *hwtstamps,
5013 struct sock *sk, int tstype)
5014{
5015 struct sk_buff *skb;
5016 bool tsonly, opt_stats = false;
5017
5018 if (!sk)
5019 return;
5020
5021 if (!hwtstamps && !(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
5022 skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
5023 return;
5024
5025 tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
5026 if (!skb_may_tx_timestamp(sk, tsonly))
5027 return;
5028
5029 if (tsonly) {
5030#ifdef CONFIG_INET
5031 if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
5032 sk_is_tcp(sk)) {
5033 skb = tcp_get_timestamping_opt_stats(sk, orig_skb,
5034 ack_skb);
5035 opt_stats = true;
5036 } else
5037#endif
5038 skb = alloc_skb(0, GFP_ATOMIC);
5039 } else {
5040 skb = skb_clone(orig_skb, GFP_ATOMIC);
5041 }
5042 if (!skb)
5043 return;
5044
5045 if (tsonly) {
5046 skb_shinfo(skb)->tx_flags |= skb_shinfo(orig_skb)->tx_flags &
5047 SKBTX_ANY_TSTAMP;
5048 skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
5049 }
5050
5051 if (hwtstamps)
5052 *skb_hwtstamps(skb) = *hwtstamps;
5053 else
5054 __net_timestamp(skb);
5055
5056 __skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
5057}
5058EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
5059
5060void skb_tstamp_tx(struct sk_buff *orig_skb,
5061 struct skb_shared_hwtstamps *hwtstamps)
5062{
5063 return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,
5064 SCM_TSTAMP_SND);
5065}
5066EXPORT_SYMBOL_GPL(skb_tstamp_tx);
5067
5068void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
5069{
5070 struct sock *sk = skb->sk;
5071 struct sock_exterr_skb *serr;
5072 int err = 1;
5073
5074 skb->wifi_acked_valid = 1;
5075 skb->wifi_acked = acked;
5076
5077 serr = SKB_EXT_ERR(skb);
5078 memset(serr, 0, sizeof(*serr));
5079 serr->ee.ee_errno = ENOMSG;
5080 serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
5081
5082 /* Take a reference to prevent skb_orphan() from freeing the socket,
5083 * but only if the socket refcount is not zero.
5084 */
5085 if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
5086 err = sock_queue_err_skb(sk, skb);
5087 sock_put(sk);
5088 }
5089 if (err)
5090 kfree_skb(skb);
5091}
5092EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
5093
5094/**
5095 * skb_partial_csum_set - set up and verify partial csum values for packet
5096 * @skb: the skb to set
5097 * @start: the number of bytes after skb->data to start checksumming.
5098 * @off: the offset from start to place the checksum.
5099 *
5100 * For untrusted partially-checksummed packets, we need to make sure the values
5101 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
5102 *
5103 * This function checks and sets those values and skb->ip_summed: if this
5104 * returns false you should drop the packet.
5105 */
5106bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
5107{
5108 u32 csum_end = (u32)start + (u32)off + sizeof(__sum16);
5109 u32 csum_start = skb_headroom(skb) + (u32)start;
5110
5111 if (unlikely(csum_start > U16_MAX || csum_end > skb_headlen(skb))) {
5112 net_warn_ratelimited("bad partial csum: csum=%u/%u headroom=%u headlen=%u\n",
5113 start, off, skb_headroom(skb), skb_headlen(skb));
5114 return false;
5115 }
5116 skb->ip_summed = CHECKSUM_PARTIAL;
5117 skb->csum_start = csum_start;
5118 skb->csum_offset = off;
5119 skb_set_transport_header(skb, start);
5120 return true;
5121}
5122EXPORT_SYMBOL_GPL(skb_partial_csum_set);
5123
5124static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
5125 unsigned int max)
5126{
5127 if (skb_headlen(skb) >= len)
5128 return 0;
5129
5130 /* If we need to pullup then pullup to the max, so we
5131 * won't need to do it again.
5132 */
5133 if (max > skb->len)
5134 max = skb->len;
5135
5136 if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
5137 return -ENOMEM;
5138
5139 if (skb_headlen(skb) < len)
5140 return -EPROTO;
5141
5142 return 0;
5143}
5144
5145#define MAX_TCP_HDR_LEN (15 * 4)
5146
5147static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
5148 typeof(IPPROTO_IP) proto,
5149 unsigned int off)
5150{
5151 int err;
5152
5153 switch (proto) {
5154 case IPPROTO_TCP:
5155 err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
5156 off + MAX_TCP_HDR_LEN);
5157 if (!err && !skb_partial_csum_set(skb, off,
5158 offsetof(struct tcphdr,
5159 check)))
5160 err = -EPROTO;
5161 return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
5162
5163 case IPPROTO_UDP:
5164 err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
5165 off + sizeof(struct udphdr));
5166 if (!err && !skb_partial_csum_set(skb, off,
5167 offsetof(struct udphdr,
5168 check)))
5169 err = -EPROTO;
5170 return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
5171 }
5172
5173 return ERR_PTR(-EPROTO);
5174}
5175
5176/* This value should be large enough to cover a tagged ethernet header plus
5177 * maximally sized IP and TCP or UDP headers.
5178 */
5179#define MAX_IP_HDR_LEN 128
5180
5181static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
5182{
5183 unsigned int off;
5184 bool fragment;
5185 __sum16 *csum;
5186 int err;
5187
5188 fragment = false;
5189
5190 err = skb_maybe_pull_tail(skb,
5191 sizeof(struct iphdr),
5192 MAX_IP_HDR_LEN);
5193 if (err < 0)
5194 goto out;
5195
5196 if (ip_is_fragment(ip_hdr(skb)))
5197 fragment = true;
5198
5199 off = ip_hdrlen(skb);
5200
5201 err = -EPROTO;
5202
5203 if (fragment)
5204 goto out;
5205
5206 csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
5207 if (IS_ERR(csum))
5208 return PTR_ERR(csum);
5209
5210 if (recalculate)
5211 *csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
5212 ip_hdr(skb)->daddr,
5213 skb->len - off,
5214 ip_hdr(skb)->protocol, 0);
5215 err = 0;
5216
5217out:
5218 return err;
5219}
5220
5221/* This value should be large enough to cover a tagged ethernet header plus
5222 * an IPv6 header, all options, and a maximal TCP or UDP header.
5223 */
5224#define MAX_IPV6_HDR_LEN 256
5225
5226#define OPT_HDR(type, skb, off) \
5227 (type *)(skb_network_header(skb) + (off))
5228
5229static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
5230{
5231 int err;
5232 u8 nexthdr;
5233 unsigned int off;
5234 unsigned int len;
5235 bool fragment;
5236 bool done;
5237 __sum16 *csum;
5238
5239 fragment = false;
5240 done = false;
5241
5242 off = sizeof(struct ipv6hdr);
5243
5244 err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
5245 if (err < 0)
5246 goto out;
5247
5248 nexthdr = ipv6_hdr(skb)->nexthdr;
5249
5250 len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
5251 while (off <= len && !done) {
5252 switch (nexthdr) {
5253 case IPPROTO_DSTOPTS:
5254 case IPPROTO_HOPOPTS:
5255 case IPPROTO_ROUTING: {
5256 struct ipv6_opt_hdr *hp;
5257
5258 err = skb_maybe_pull_tail(skb,
5259 off +
5260 sizeof(struct ipv6_opt_hdr),
5261 MAX_IPV6_HDR_LEN);
5262 if (err < 0)
5263 goto out;
5264
5265 hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
5266 nexthdr = hp->nexthdr;
5267 off += ipv6_optlen(hp);
5268 break;
5269 }
5270 case IPPROTO_AH: {
5271 struct ip_auth_hdr *hp;
5272
5273 err = skb_maybe_pull_tail(skb,
5274 off +
5275 sizeof(struct ip_auth_hdr),
5276 MAX_IPV6_HDR_LEN);
5277 if (err < 0)
5278 goto out;
5279
5280 hp = OPT_HDR(struct ip_auth_hdr, skb, off);
5281 nexthdr = hp->nexthdr;
5282 off += ipv6_authlen(hp);
5283 break;
5284 }
5285 case IPPROTO_FRAGMENT: {
5286 struct frag_hdr *hp;
5287
5288 err = skb_maybe_pull_tail(skb,
5289 off +
5290 sizeof(struct frag_hdr),
5291 MAX_IPV6_HDR_LEN);
5292 if (err < 0)
5293 goto out;
5294
5295 hp = OPT_HDR(struct frag_hdr, skb, off);
5296
5297 if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
5298 fragment = true;
5299
5300 nexthdr = hp->nexthdr;
5301 off += sizeof(struct frag_hdr);
5302 break;
5303 }
5304 default:
5305 done = true;
5306 break;
5307 }
5308 }
5309
5310 err = -EPROTO;
5311
5312 if (!done || fragment)
5313 goto out;
5314
5315 csum = skb_checksum_setup_ip(skb, nexthdr, off);
5316 if (IS_ERR(csum))
5317 return PTR_ERR(csum);
5318
5319 if (recalculate)
5320 *csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
5321 &ipv6_hdr(skb)->daddr,
5322 skb->len - off, nexthdr, 0);
5323 err = 0;
5324
5325out:
5326 return err;
5327}
5328
5329/**
5330 * skb_checksum_setup - set up partial checksum offset
5331 * @skb: the skb to set up
5332 * @recalculate: if true the pseudo-header checksum will be recalculated
5333 */
5334int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
5335{
5336 int err;
5337
5338 switch (skb->protocol) {
5339 case htons(ETH_P_IP):
5340 err = skb_checksum_setup_ipv4(skb, recalculate);
5341 break;
5342
5343 case htons(ETH_P_IPV6):
5344 err = skb_checksum_setup_ipv6(skb, recalculate);
5345 break;
5346
5347 default:
5348 err = -EPROTO;
5349 break;
5350 }
5351
5352 return err;
5353}
5354EXPORT_SYMBOL(skb_checksum_setup);
5355
5356/**
5357 * skb_checksum_maybe_trim - maybe trims the given skb
5358 * @skb: the skb to check
5359 * @transport_len: the data length beyond the network header
5360 *
5361 * Checks whether the given skb has data beyond the given transport length.
5362 * If so, returns a cloned skb trimmed to this transport length.
5363 * Otherwise returns the provided skb. Returns NULL in error cases
5364 * (e.g. transport_len exceeds skb length or out-of-memory).
5365 *
5366 * Caller needs to set the skb transport header and free any returned skb if it
5367 * differs from the provided skb.
5368 */
5369static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
5370 unsigned int transport_len)
5371{
5372 struct sk_buff *skb_chk;
5373 unsigned int len = skb_transport_offset(skb) + transport_len;
5374 int ret;
5375
5376 if (skb->len < len)
5377 return NULL;
5378 else if (skb->len == len)
5379 return skb;
5380
5381 skb_chk = skb_clone(skb, GFP_ATOMIC);
5382 if (!skb_chk)
5383 return NULL;
5384
5385 ret = pskb_trim_rcsum(skb_chk, len);
5386 if (ret) {
5387 kfree_skb(skb_chk);
5388 return NULL;
5389 }
5390
5391 return skb_chk;
5392}
5393
5394/**
5395 * skb_checksum_trimmed - validate checksum of an skb
5396 * @skb: the skb to check
5397 * @transport_len: the data length beyond the network header
5398 * @skb_chkf: checksum function to use
5399 *
5400 * Applies the given checksum function skb_chkf to the provided skb.
5401 * Returns a checked and maybe trimmed skb. Returns NULL on error.
5402 *
5403 * If the skb has data beyond the given transport length, then a
5404 * trimmed & cloned skb is checked and returned.
5405 *
5406 * Caller needs to set the skb transport header and free any returned skb if it
5407 * differs from the provided skb.
5408 */
5409struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
5410 unsigned int transport_len,
5411 __sum16(*skb_chkf)(struct sk_buff *skb))
5412{
5413 struct sk_buff *skb_chk;
5414 unsigned int offset = skb_transport_offset(skb);
5415 __sum16 ret;
5416
5417 skb_chk = skb_checksum_maybe_trim(skb, transport_len);
5418 if (!skb_chk)
5419 goto err;
5420
5421 if (!pskb_may_pull(skb_chk, offset))
5422 goto err;
5423
5424 skb_pull_rcsum(skb_chk, offset);
5425 ret = skb_chkf(skb_chk);
5426 skb_push_rcsum(skb_chk, offset);
5427
5428 if (ret)
5429 goto err;
5430
5431 return skb_chk;
5432
5433err:
5434 if (skb_chk && skb_chk != skb)
5435 kfree_skb(skb_chk);
5436
5437 return NULL;
5438
5439}
5440EXPORT_SYMBOL(skb_checksum_trimmed);
5441
5442void __skb_warn_lro_forwarding(const struct sk_buff *skb)
5443{
5444 net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
5445 skb->dev->name);
5446}
5447EXPORT_SYMBOL(__skb_warn_lro_forwarding);
5448
5449void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
5450{
5451 if (head_stolen) {
5452 skb_release_head_state(skb);
5453 kmem_cache_free(skbuff_head_cache, skb);
5454 } else {
5455 __kfree_skb(skb);
5456 }
5457}
5458EXPORT_SYMBOL(kfree_skb_partial);
5459
5460/**
5461 * skb_try_coalesce - try to merge skb to prior one
5462 * @to: prior buffer
5463 * @from: buffer to add
5464 * @fragstolen: pointer to boolean
5465 * @delta_truesize: how much more was allocated than was requested
5466 */
5467bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
5468 bool *fragstolen, int *delta_truesize)
5469{
5470 struct skb_shared_info *to_shinfo, *from_shinfo;
5471 int i, delta, len = from->len;
5472
5473 *fragstolen = false;
5474
5475 if (skb_cloned(to))
5476 return false;
5477
5478 /* In general, avoid mixing slab allocated and page_pool allocated
5479 * pages within the same SKB. However when @to is not pp_recycle and
5480 * @from is cloned, we can transition frag pages from page_pool to
5481 * reference counted.
5482 *
5483 * On the other hand, don't allow coalescing two pp_recycle SKBs if
5484 * @from is cloned, in case the SKB is using page_pool fragment
5485 * references (PP_FLAG_PAGE_FRAG). Since we only take full page
5486 * references for cloned SKBs at the moment that would result in
5487 * inconsistent reference counts.
5488 */
5489 if (to->pp_recycle != (from->pp_recycle && !skb_cloned(from)))
5490 return false;
5491
5492 if (len <= skb_tailroom(to)) {
5493 if (len)
5494 BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
5495 *delta_truesize = 0;
5496 return true;
5497 }
5498
5499 to_shinfo = skb_shinfo(to);
5500 from_shinfo = skb_shinfo(from);
5501 if (to_shinfo->frag_list || from_shinfo->frag_list)
5502 return false;
5503 if (skb_zcopy(to) || skb_zcopy(from))
5504 return false;
5505
5506 if (skb_headlen(from) != 0) {
5507 struct page *page;
5508 unsigned int offset;
5509
5510 if (to_shinfo->nr_frags +
5511 from_shinfo->nr_frags >= MAX_SKB_FRAGS)
5512 return false;
5513
5514 if (skb_head_is_locked(from))
5515 return false;
5516
5517 delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
5518
5519 page = virt_to_head_page(from->head);
5520 offset = from->data - (unsigned char *)page_address(page);
5521
5522 skb_fill_page_desc(to, to_shinfo->nr_frags,
5523 page, offset, skb_headlen(from));
5524 *fragstolen = true;
5525 } else {
5526 if (to_shinfo->nr_frags +
5527 from_shinfo->nr_frags > MAX_SKB_FRAGS)
5528 return false;
5529
5530 delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
5531 }
5532
5533 WARN_ON_ONCE(delta < len);
5534
5535 memcpy(to_shinfo->frags + to_shinfo->nr_frags,
5536 from_shinfo->frags,
5537 from_shinfo->nr_frags * sizeof(skb_frag_t));
5538 to_shinfo->nr_frags += from_shinfo->nr_frags;
5539
5540 if (!skb_cloned(from))
5541 from_shinfo->nr_frags = 0;
5542
5543 /* if the skb is not cloned this does nothing
5544 * since we set nr_frags to 0.
5545 */
5546 for (i = 0; i < from_shinfo->nr_frags; i++)
5547 __skb_frag_ref(&from_shinfo->frags[i]);
5548
5549 to->truesize += delta;
5550 to->len += len;
5551 to->data_len += len;
5552
5553 *delta_truesize = delta;
5554 return true;
5555}
5556EXPORT_SYMBOL(skb_try_coalesce);
5557
5558/**
5559 * skb_scrub_packet - scrub an skb
5560 *
5561 * @skb: buffer to clean
5562 * @xnet: packet is crossing netns
5563 *
5564 * skb_scrub_packet can be used after encapsulating or decapsulting a packet
5565 * into/from a tunnel. Some information have to be cleared during these
5566 * operations.
5567 * skb_scrub_packet can also be used to clean a skb before injecting it in
5568 * another namespace (@xnet == true). We have to clear all information in the
5569 * skb that could impact namespace isolation.
5570 */
5571void skb_scrub_packet(struct sk_buff *skb, bool xnet)
5572{
5573 skb->pkt_type = PACKET_HOST;
5574 skb->skb_iif = 0;
5575 skb->ignore_df = 0;
5576 skb_dst_drop(skb);
5577 skb_ext_reset(skb);
5578 nf_reset_ct(skb);
5579 nf_reset_trace(skb);
5580
5581#ifdef CONFIG_NET_SWITCHDEV
5582 skb->offload_fwd_mark = 0;
5583 skb->offload_l3_fwd_mark = 0;
5584#endif
5585
5586 if (!xnet)
5587 return;
5588
5589 ipvs_reset(skb);
5590 skb->mark = 0;
5591 skb_clear_tstamp(skb);
5592}
5593EXPORT_SYMBOL_GPL(skb_scrub_packet);
5594
5595/**
5596 * skb_gso_transport_seglen - Return length of individual segments of a gso packet
5597 *
5598 * @skb: GSO skb
5599 *
5600 * skb_gso_transport_seglen is used to determine the real size of the
5601 * individual segments, including Layer4 headers (TCP/UDP).
5602 *
5603 * The MAC/L2 or network (IP, IPv6) headers are not accounted for.
5604 */
5605static unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
5606{
5607 const struct skb_shared_info *shinfo = skb_shinfo(skb);
5608 unsigned int thlen = 0;
5609
5610 if (skb->encapsulation) {
5611 thlen = skb_inner_transport_header(skb) -
5612 skb_transport_header(skb);
5613
5614 if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
5615 thlen += inner_tcp_hdrlen(skb);
5616 } else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
5617 thlen = tcp_hdrlen(skb);
5618 } else if (unlikely(skb_is_gso_sctp(skb))) {
5619 thlen = sizeof(struct sctphdr);
5620 } else if (shinfo->gso_type & SKB_GSO_UDP_L4) {
5621 thlen = sizeof(struct udphdr);
5622 }
5623 /* UFO sets gso_size to the size of the fragmentation
5624 * payload, i.e. the size of the L4 (UDP) header is already
5625 * accounted for.
5626 */
5627 return thlen + shinfo->gso_size;
5628}
5629
5630/**
5631 * skb_gso_network_seglen - Return length of individual segments of a gso packet
5632 *
5633 * @skb: GSO skb
5634 *
5635 * skb_gso_network_seglen is used to determine the real size of the
5636 * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
5637 *
5638 * The MAC/L2 header is not accounted for.
5639 */
5640static unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
5641{
5642 unsigned int hdr_len = skb_transport_header(skb) -
5643 skb_network_header(skb);
5644
5645 return hdr_len + skb_gso_transport_seglen(skb);
5646}
5647
5648/**
5649 * skb_gso_mac_seglen - Return length of individual segments of a gso packet
5650 *
5651 * @skb: GSO skb
5652 *
5653 * skb_gso_mac_seglen is used to determine the real size of the
5654 * individual segments, including MAC/L2, Layer3 (IP, IPv6) and L4
5655 * headers (TCP/UDP).
5656 */
5657static unsigned int skb_gso_mac_seglen(const struct sk_buff *skb)
5658{
5659 unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
5660
5661 return hdr_len + skb_gso_transport_seglen(skb);
5662}
5663
5664/**
5665 * skb_gso_size_check - check the skb size, considering GSO_BY_FRAGS
5666 *
5667 * There are a couple of instances where we have a GSO skb, and we
5668 * want to determine what size it would be after it is segmented.
5669 *
5670 * We might want to check:
5671 * - L3+L4+payload size (e.g. IP forwarding)
5672 * - L2+L3+L4+payload size (e.g. sanity check before passing to driver)
5673 *
5674 * This is a helper to do that correctly considering GSO_BY_FRAGS.
5675 *
5676 * @skb: GSO skb
5677 *
5678 * @seg_len: The segmented length (from skb_gso_*_seglen). In the
5679 * GSO_BY_FRAGS case this will be [header sizes + GSO_BY_FRAGS].
5680 *
5681 * @max_len: The maximum permissible length.
5682 *
5683 * Returns true if the segmented length <= max length.
5684 */
5685static inline bool skb_gso_size_check(const struct sk_buff *skb,
5686 unsigned int seg_len,
5687 unsigned int max_len) {
5688 const struct skb_shared_info *shinfo = skb_shinfo(skb);
5689 const struct sk_buff *iter;
5690
5691 if (shinfo->gso_size != GSO_BY_FRAGS)
5692 return seg_len <= max_len;
5693
5694 /* Undo this so we can re-use header sizes */
5695 seg_len -= GSO_BY_FRAGS;
5696
5697 skb_walk_frags(skb, iter) {
5698 if (seg_len + skb_headlen(iter) > max_len)
5699 return false;
5700 }
5701
5702 return true;
5703}
5704
5705/**
5706 * skb_gso_validate_network_len - Will a split GSO skb fit into a given MTU?
5707 *
5708 * @skb: GSO skb
5709 * @mtu: MTU to validate against
5710 *
5711 * skb_gso_validate_network_len validates if a given skb will fit a
5712 * wanted MTU once split. It considers L3 headers, L4 headers, and the
5713 * payload.
5714 */
5715bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu)
5716{
5717 return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu);
5718}
5719EXPORT_SYMBOL_GPL(skb_gso_validate_network_len);
5720
5721/**
5722 * skb_gso_validate_mac_len - Will a split GSO skb fit in a given length?
5723 *
5724 * @skb: GSO skb
5725 * @len: length to validate against
5726 *
5727 * skb_gso_validate_mac_len validates if a given skb will fit a wanted
5728 * length once split, including L2, L3 and L4 headers and the payload.
5729 */
5730bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len)
5731{
5732 return skb_gso_size_check(skb, skb_gso_mac_seglen(skb), len);
5733}
5734EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len);
5735
5736static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
5737{
5738 int mac_len, meta_len;
5739 void *meta;
5740
5741 if (skb_cow(skb, skb_headroom(skb)) < 0) {
5742 kfree_skb(skb);
5743 return NULL;
5744 }
5745
5746 mac_len = skb->data - skb_mac_header(skb);
5747 if (likely(mac_len > VLAN_HLEN + ETH_TLEN)) {
5748 memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
5749 mac_len - VLAN_HLEN - ETH_TLEN);
5750 }
5751
5752 meta_len = skb_metadata_len(skb);
5753 if (meta_len) {
5754 meta = skb_metadata_end(skb) - meta_len;
5755 memmove(meta + VLAN_HLEN, meta, meta_len);
5756 }
5757
5758 skb->mac_header += VLAN_HLEN;
5759 return skb;
5760}
5761
5762struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
5763{
5764 struct vlan_hdr *vhdr;
5765 u16 vlan_tci;
5766
5767 if (unlikely(skb_vlan_tag_present(skb))) {
5768 /* vlan_tci is already set-up so leave this for another time */
5769 return skb;
5770 }
5771
5772 skb = skb_share_check(skb, GFP_ATOMIC);
5773 if (unlikely(!skb))
5774 goto err_free;
5775 /* We may access the two bytes after vlan_hdr in vlan_set_encap_proto(). */
5776 if (unlikely(!pskb_may_pull(skb, VLAN_HLEN + sizeof(unsigned short))))
5777 goto err_free;
5778
5779 vhdr = (struct vlan_hdr *)skb->data;
5780 vlan_tci = ntohs(vhdr->h_vlan_TCI);
5781 __vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
5782
5783 skb_pull_rcsum(skb, VLAN_HLEN);
5784 vlan_set_encap_proto(skb, vhdr);
5785
5786 skb = skb_reorder_vlan_header(skb);
5787 if (unlikely(!skb))
5788 goto err_free;
5789
5790 skb_reset_network_header(skb);
5791 if (!skb_transport_header_was_set(skb))
5792 skb_reset_transport_header(skb);
5793 skb_reset_mac_len(skb);
5794
5795 return skb;
5796
5797err_free:
5798 kfree_skb(skb);
5799 return NULL;
5800}
5801EXPORT_SYMBOL(skb_vlan_untag);
5802
5803int skb_ensure_writable(struct sk_buff *skb, unsigned int write_len)
5804{
5805 if (!pskb_may_pull(skb, write_len))
5806 return -ENOMEM;
5807
5808 if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
5809 return 0;
5810
5811 return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
5812}
5813EXPORT_SYMBOL(skb_ensure_writable);
5814
5815/* remove VLAN header from packet and update csum accordingly.
5816 * expects a non skb_vlan_tag_present skb with a vlan tag payload
5817 */
5818int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
5819{
5820 struct vlan_hdr *vhdr;
5821 int offset = skb->data - skb_mac_header(skb);
5822 int err;
5823
5824 if (WARN_ONCE(offset,
5825 "__skb_vlan_pop got skb with skb->data not at mac header (offset %d)\n",
5826 offset)) {
5827 return -EINVAL;
5828 }
5829
5830 err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
5831 if (unlikely(err))
5832 return err;
5833
5834 skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
5835
5836 vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
5837 *vlan_tci = ntohs(vhdr->h_vlan_TCI);
5838
5839 memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
5840 __skb_pull(skb, VLAN_HLEN);
5841
5842 vlan_set_encap_proto(skb, vhdr);
5843 skb->mac_header += VLAN_HLEN;
5844
5845 if (skb_network_offset(skb) < ETH_HLEN)
5846 skb_set_network_header(skb, ETH_HLEN);
5847
5848 skb_reset_mac_len(skb);
5849
5850 return err;
5851}
5852EXPORT_SYMBOL(__skb_vlan_pop);
5853
5854/* Pop a vlan tag either from hwaccel or from payload.
5855 * Expects skb->data at mac header.
5856 */
5857int skb_vlan_pop(struct sk_buff *skb)
5858{
5859 u16 vlan_tci;
5860 __be16 vlan_proto;
5861 int err;
5862
5863 if (likely(skb_vlan_tag_present(skb))) {
5864 __vlan_hwaccel_clear_tag(skb);
5865 } else {
5866 if (unlikely(!eth_type_vlan(skb->protocol)))
5867 return 0;
5868
5869 err = __skb_vlan_pop(skb, &vlan_tci);
5870 if (err)
5871 return err;
5872 }
5873 /* move next vlan tag to hw accel tag */
5874 if (likely(!eth_type_vlan(skb->protocol)))
5875 return 0;
5876
5877 vlan_proto = skb->protocol;
5878 err = __skb_vlan_pop(skb, &vlan_tci);
5879 if (unlikely(err))
5880 return err;
5881
5882 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
5883 return 0;
5884}
5885EXPORT_SYMBOL(skb_vlan_pop);
5886
5887/* Push a vlan tag either into hwaccel or into payload (if hwaccel tag present).
5888 * Expects skb->data at mac header.
5889 */
5890int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
5891{
5892 if (skb_vlan_tag_present(skb)) {
5893 int offset = skb->data - skb_mac_header(skb);
5894 int err;
5895
5896 if (WARN_ONCE(offset,
5897 "skb_vlan_push got skb with skb->data not at mac header (offset %d)\n",
5898 offset)) {
5899 return -EINVAL;
5900 }
5901
5902 err = __vlan_insert_tag(skb, skb->vlan_proto,
5903 skb_vlan_tag_get(skb));
5904 if (err)
5905 return err;
5906
5907 skb->protocol = skb->vlan_proto;
5908 skb->mac_len += VLAN_HLEN;
5909
5910 skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
5911 }
5912 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
5913 return 0;
5914}
5915EXPORT_SYMBOL(skb_vlan_push);
5916
5917/**
5918 * skb_eth_pop() - Drop the Ethernet header at the head of a packet
5919 *
5920 * @skb: Socket buffer to modify
5921 *
5922 * Drop the Ethernet header of @skb.
5923 *
5924 * Expects that skb->data points to the mac header and that no VLAN tags are
5925 * present.
5926 *
5927 * Returns 0 on success, -errno otherwise.
5928 */
5929int skb_eth_pop(struct sk_buff *skb)
5930{
5931 if (!pskb_may_pull(skb, ETH_HLEN) || skb_vlan_tagged(skb) ||
5932 skb_network_offset(skb) < ETH_HLEN)
5933 return -EPROTO;
5934
5935 skb_pull_rcsum(skb, ETH_HLEN);
5936 skb_reset_mac_header(skb);
5937 skb_reset_mac_len(skb);
5938
5939 return 0;
5940}
5941EXPORT_SYMBOL(skb_eth_pop);
5942
5943/**
5944 * skb_eth_push() - Add a new Ethernet header at the head of a packet
5945 *
5946 * @skb: Socket buffer to modify
5947 * @dst: Destination MAC address of the new header
5948 * @src: Source MAC address of the new header
5949 *
5950 * Prepend @skb with a new Ethernet header.
5951 *
5952 * Expects that skb->data points to the mac header, which must be empty.
5953 *
5954 * Returns 0 on success, -errno otherwise.
5955 */
5956int skb_eth_push(struct sk_buff *skb, const unsigned char *dst,
5957 const unsigned char *src)
5958{
5959 struct ethhdr *eth;
5960 int err;
5961
5962 if (skb_network_offset(skb) || skb_vlan_tag_present(skb))
5963 return -EPROTO;
5964
5965 err = skb_cow_head(skb, sizeof(*eth));
5966 if (err < 0)
5967 return err;
5968
5969 skb_push(skb, sizeof(*eth));
5970 skb_reset_mac_header(skb);
5971 skb_reset_mac_len(skb);
5972
5973 eth = eth_hdr(skb);
5974 ether_addr_copy(eth->h_dest, dst);
5975 ether_addr_copy(eth->h_source, src);
5976 eth->h_proto = skb->protocol;
5977
5978 skb_postpush_rcsum(skb, eth, sizeof(*eth));
5979
5980 return 0;
5981}
5982EXPORT_SYMBOL(skb_eth_push);
5983
5984/* Update the ethertype of hdr and the skb csum value if required. */
5985static void skb_mod_eth_type(struct sk_buff *skb, struct ethhdr *hdr,
5986 __be16 ethertype)
5987{
5988 if (skb->ip_summed == CHECKSUM_COMPLETE) {
5989 __be16 diff[] = { ~hdr->h_proto, ethertype };
5990
5991 skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
5992 }
5993
5994 hdr->h_proto = ethertype;
5995}
5996
5997/**
5998 * skb_mpls_push() - push a new MPLS header after mac_len bytes from start of
5999 * the packet
6000 *
6001 * @skb: buffer
6002 * @mpls_lse: MPLS label stack entry to push
6003 * @mpls_proto: ethertype of the new MPLS header (expects 0x8847 or 0x8848)
6004 * @mac_len: length of the MAC header
6005 * @ethernet: flag to indicate if the resulting packet after skb_mpls_push is
6006 * ethernet
6007 *
6008 * Expects skb->data at mac header.
6009 *
6010 * Returns 0 on success, -errno otherwise.
6011 */
6012int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
6013 int mac_len, bool ethernet)
6014{
6015 struct mpls_shim_hdr *lse;
6016 int err;
6017
6018 if (unlikely(!eth_p_mpls(mpls_proto)))
6019 return -EINVAL;
6020
6021 /* Networking stack does not allow simultaneous Tunnel and MPLS GSO. */
6022 if (skb->encapsulation)
6023 return -EINVAL;
6024
6025 err = skb_cow_head(skb, MPLS_HLEN);
6026 if (unlikely(err))
6027 return err;
6028
6029 if (!skb->inner_protocol) {
6030 skb_set_inner_network_header(skb, skb_network_offset(skb));
6031 skb_set_inner_protocol(skb, skb->protocol);
6032 }
6033
6034 skb_push(skb, MPLS_HLEN);
6035 memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
6036 mac_len);
6037 skb_reset_mac_header(skb);
6038 skb_set_network_header(skb, mac_len);
6039 skb_reset_mac_len(skb);
6040
6041 lse = mpls_hdr(skb);
6042 lse->label_stack_entry = mpls_lse;
6043 skb_postpush_rcsum(skb, lse, MPLS_HLEN);
6044
6045 if (ethernet && mac_len >= ETH_HLEN)
6046 skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
6047 skb->protocol = mpls_proto;
6048
6049 return 0;
6050}
6051EXPORT_SYMBOL_GPL(skb_mpls_push);
6052
6053/**
6054 * skb_mpls_pop() - pop the outermost MPLS header
6055 *
6056 * @skb: buffer
6057 * @next_proto: ethertype of header after popped MPLS header
6058 * @mac_len: length of the MAC header
6059 * @ethernet: flag to indicate if the packet is ethernet
6060 *
6061 * Expects skb->data at mac header.
6062 *
6063 * Returns 0 on success, -errno otherwise.
6064 */
6065int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
6066 bool ethernet)
6067{
6068 int err;
6069
6070 if (unlikely(!eth_p_mpls(skb->protocol)))
6071 return 0;
6072
6073 err = skb_ensure_writable(skb, mac_len + MPLS_HLEN);
6074 if (unlikely(err))
6075 return err;
6076
6077 skb_postpull_rcsum(skb, mpls_hdr(skb), MPLS_HLEN);
6078 memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
6079 mac_len);
6080
6081 __skb_pull(skb, MPLS_HLEN);
6082 skb_reset_mac_header(skb);
6083 skb_set_network_header(skb, mac_len);
6084
6085 if (ethernet && mac_len >= ETH_HLEN) {
6086 struct ethhdr *hdr;
6087
6088 /* use mpls_hdr() to get ethertype to account for VLANs. */
6089 hdr = (struct ethhdr *)((void *)mpls_hdr(skb) - ETH_HLEN);
6090 skb_mod_eth_type(skb, hdr, next_proto);
6091 }
6092 skb->protocol = next_proto;
6093
6094 return 0;
6095}
6096EXPORT_SYMBOL_GPL(skb_mpls_pop);
6097
6098/**
6099 * skb_mpls_update_lse() - modify outermost MPLS header and update csum
6100 *
6101 * @skb: buffer
6102 * @mpls_lse: new MPLS label stack entry to update to
6103 *
6104 * Expects skb->data at mac header.
6105 *
6106 * Returns 0 on success, -errno otherwise.
6107 */
6108int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse)
6109{
6110 int err;
6111
6112 if (unlikely(!eth_p_mpls(skb->protocol)))
6113 return -EINVAL;
6114
6115 err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
6116 if (unlikely(err))
6117 return err;
6118
6119 if (skb->ip_summed == CHECKSUM_COMPLETE) {
6120 __be32 diff[] = { ~mpls_hdr(skb)->label_stack_entry, mpls_lse };
6121
6122 skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
6123 }
6124
6125 mpls_hdr(skb)->label_stack_entry = mpls_lse;
6126
6127 return 0;
6128}
6129EXPORT_SYMBOL_GPL(skb_mpls_update_lse);
6130
6131/**
6132 * skb_mpls_dec_ttl() - decrement the TTL of the outermost MPLS header
6133 *
6134 * @skb: buffer
6135 *
6136 * Expects skb->data at mac header.
6137 *
6138 * Returns 0 on success, -errno otherwise.
6139 */
6140int skb_mpls_dec_ttl(struct sk_buff *skb)
6141{
6142 u32 lse;
6143 u8 ttl;
6144
6145 if (unlikely(!eth_p_mpls(skb->protocol)))
6146 return -EINVAL;
6147
6148 if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN))
6149 return -ENOMEM;
6150
6151 lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry);
6152 ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
6153 if (!--ttl)
6154 return -EINVAL;
6155
6156 lse &= ~MPLS_LS_TTL_MASK;
6157 lse |= ttl << MPLS_LS_TTL_SHIFT;
6158
6159 return skb_mpls_update_lse(skb, cpu_to_be32(lse));
6160}
6161EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl);
6162
6163/**
6164 * alloc_skb_with_frags - allocate skb with page frags
6165 *
6166 * @header_len: size of linear part
6167 * @data_len: needed length in frags
6168 * @max_page_order: max page order desired.
6169 * @errcode: pointer to error code if any
6170 * @gfp_mask: allocation mask
6171 *
6172 * This can be used to allocate a paged skb, given a maximal order for frags.
6173 */
6174struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
6175 unsigned long data_len,
6176 int max_page_order,
6177 int *errcode,
6178 gfp_t gfp_mask)
6179{
6180 int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
6181 unsigned long chunk;
6182 struct sk_buff *skb;
6183 struct page *page;
6184 int i;
6185
6186 *errcode = -EMSGSIZE;
6187 /* Note this test could be relaxed, if we succeed to allocate
6188 * high order pages...
6189 */
6190 if (npages > MAX_SKB_FRAGS)
6191 return NULL;
6192
6193 *errcode = -ENOBUFS;
6194 skb = alloc_skb(header_len, gfp_mask);
6195 if (!skb)
6196 return NULL;
6197
6198 skb->truesize += npages << PAGE_SHIFT;
6199
6200 for (i = 0; npages > 0; i++) {
6201 int order = max_page_order;
6202
6203 while (order) {
6204 if (npages >= 1 << order) {
6205 page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
6206 __GFP_COMP |
6207 __GFP_NOWARN,
6208 order);
6209 if (page)
6210 goto fill_page;
6211 /* Do not retry other high order allocations */
6212 order = 1;
6213 max_page_order = 0;
6214 }
6215 order--;
6216 }
6217 page = alloc_page(gfp_mask);
6218 if (!page)
6219 goto failure;
6220fill_page:
6221 chunk = min_t(unsigned long, data_len,
6222 PAGE_SIZE << order);
6223 skb_fill_page_desc(skb, i, page, 0, chunk);
6224 data_len -= chunk;
6225 npages -= 1 << order;
6226 }
6227 return skb;
6228
6229failure:
6230 kfree_skb(skb);
6231 return NULL;
6232}
6233EXPORT_SYMBOL(alloc_skb_with_frags);
6234
6235/* carve out the first off bytes from skb when off < headlen */
6236static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
6237 const int headlen, gfp_t gfp_mask)
6238{
6239 int i;
6240 unsigned int size = skb_end_offset(skb);
6241 int new_hlen = headlen - off;
6242 u8 *data;
6243
6244 if (skb_pfmemalloc(skb))
6245 gfp_mask |= __GFP_MEMALLOC;
6246
6247 size = SKB_DATA_ALIGN(size);
6248 size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
6249 size = kmalloc_size_roundup(size);
6250 data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL);
6251 if (!data)
6252 return -ENOMEM;
6253 size = SKB_WITH_OVERHEAD(size);
6254
6255 /* Copy real data, and all frags */
6256 skb_copy_from_linear_data_offset(skb, off, data, new_hlen);
6257 skb->len -= off;
6258
6259 memcpy((struct skb_shared_info *)(data + size),
6260 skb_shinfo(skb),
6261 offsetof(struct skb_shared_info,
6262 frags[skb_shinfo(skb)->nr_frags]));
6263 if (skb_cloned(skb)) {
6264 /* drop the old head gracefully */
6265 if (skb_orphan_frags(skb, gfp_mask)) {
6266 kfree(data);
6267 return -ENOMEM;
6268 }
6269 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
6270 skb_frag_ref(skb, i);
6271 if (skb_has_frag_list(skb))
6272 skb_clone_fraglist(skb);
6273 skb_release_data(skb, SKB_CONSUMED);
6274 } else {
6275 /* we can reuse existing recount- all we did was
6276 * relocate values
6277 */
6278 skb_free_head(skb);
6279 }
6280
6281 skb->head = data;
6282 skb->data = data;
6283 skb->head_frag = 0;
6284 skb_set_end_offset(skb, size);
6285 skb_set_tail_pointer(skb, skb_headlen(skb));
6286 skb_headers_offset_update(skb, 0);
6287 skb->cloned = 0;
6288 skb->hdr_len = 0;
6289 skb->nohdr = 0;
6290 atomic_set(&skb_shinfo(skb)->dataref, 1);
6291
6292 return 0;
6293}
6294
6295static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
6296
6297/* carve out the first eat bytes from skb's frag_list. May recurse into
6298 * pskb_carve()
6299 */
6300static int pskb_carve_frag_list(struct sk_buff *skb,
6301 struct skb_shared_info *shinfo, int eat,
6302 gfp_t gfp_mask)
6303{
6304 struct sk_buff *list = shinfo->frag_list;
6305 struct sk_buff *clone = NULL;
6306 struct sk_buff *insp = NULL;
6307
6308 do {
6309 if (!list) {
6310 pr_err("Not enough bytes to eat. Want %d\n", eat);
6311 return -EFAULT;
6312 }
6313 if (list->len <= eat) {
6314 /* Eaten as whole. */
6315 eat -= list->len;
6316 list = list->next;
6317 insp = list;
6318 } else {
6319 /* Eaten partially. */
6320 if (skb_shared(list)) {
6321 clone = skb_clone(list, gfp_mask);
6322 if (!clone)
6323 return -ENOMEM;
6324 insp = list->next;
6325 list = clone;
6326 } else {
6327 /* This may be pulled without problems. */
6328 insp = list;
6329 }
6330 if (pskb_carve(list, eat, gfp_mask) < 0) {
6331 kfree_skb(clone);
6332 return -ENOMEM;
6333 }
6334 break;
6335 }
6336 } while (eat);
6337
6338 /* Free pulled out fragments. */
6339 while ((list = shinfo->frag_list) != insp) {
6340 shinfo->frag_list = list->next;
6341 consume_skb(list);
6342 }
6343 /* And insert new clone at head. */
6344 if (clone) {
6345 clone->next = list;
6346 shinfo->frag_list = clone;
6347 }
6348 return 0;
6349}
6350
6351/* carve off first len bytes from skb. Split line (off) is in the
6352 * non-linear part of skb
6353 */
6354static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
6355 int pos, gfp_t gfp_mask)
6356{
6357 int i, k = 0;
6358 unsigned int size = skb_end_offset(skb);
6359 u8 *data;
6360 const int nfrags = skb_shinfo(skb)->nr_frags;
6361 struct skb_shared_info *shinfo;
6362
6363 if (skb_pfmemalloc(skb))
6364 gfp_mask |= __GFP_MEMALLOC;
6365
6366 size = SKB_DATA_ALIGN(size);
6367 size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
6368 size = kmalloc_size_roundup(size);
6369 data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL);
6370 if (!data)
6371 return -ENOMEM;
6372 size = SKB_WITH_OVERHEAD(size);
6373
6374 memcpy((struct skb_shared_info *)(data + size),
6375 skb_shinfo(skb), offsetof(struct skb_shared_info, frags[0]));
6376 if (skb_orphan_frags(skb, gfp_mask)) {
6377 kfree(data);
6378 return -ENOMEM;
6379 }
6380 shinfo = (struct skb_shared_info *)(data + size);
6381 for (i = 0; i < nfrags; i++) {
6382 int fsize = skb_frag_size(&skb_shinfo(skb)->frags[i]);
6383
6384 if (pos + fsize > off) {
6385 shinfo->frags[k] = skb_shinfo(skb)->frags[i];
6386
6387 if (pos < off) {
6388 /* Split frag.
6389 * We have two variants in this case:
6390 * 1. Move all the frag to the second
6391 * part, if it is possible. F.e.
6392 * this approach is mandatory for TUX,
6393 * where splitting is expensive.
6394 * 2. Split is accurately. We make this.
6395 */
6396 skb_frag_off_add(&shinfo->frags[0], off - pos);
6397 skb_frag_size_sub(&shinfo->frags[0], off - pos);
6398 }
6399 skb_frag_ref(skb, i);
6400 k++;
6401 }
6402 pos += fsize;
6403 }
6404 shinfo->nr_frags = k;
6405 if (skb_has_frag_list(skb))
6406 skb_clone_fraglist(skb);
6407
6408 /* split line is in frag list */
6409 if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
6410 /* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
6411 if (skb_has_frag_list(skb))
6412 kfree_skb_list(skb_shinfo(skb)->frag_list);
6413 kfree(data);
6414 return -ENOMEM;
6415 }
6416 skb_release_data(skb, SKB_CONSUMED);
6417
6418 skb->head = data;
6419 skb->head_frag = 0;
6420 skb->data = data;
6421 skb_set_end_offset(skb, size);
6422 skb_reset_tail_pointer(skb);
6423 skb_headers_offset_update(skb, 0);
6424 skb->cloned = 0;
6425 skb->hdr_len = 0;
6426 skb->nohdr = 0;
6427 skb->len -= off;
6428 skb->data_len = skb->len;
6429 atomic_set(&skb_shinfo(skb)->dataref, 1);
6430 return 0;
6431}
6432
6433/* remove len bytes from the beginning of the skb */
6434static int pskb_carve(struct sk_buff *skb, const u32 len, gfp_t gfp)
6435{
6436 int headlen = skb_headlen(skb);
6437
6438 if (len < headlen)
6439 return pskb_carve_inside_header(skb, len, headlen, gfp);
6440 else
6441 return pskb_carve_inside_nonlinear(skb, len, headlen, gfp);
6442}
6443
6444/* Extract to_copy bytes starting at off from skb, and return this in
6445 * a new skb
6446 */
6447struct sk_buff *pskb_extract(struct sk_buff *skb, int off,
6448 int to_copy, gfp_t gfp)
6449{
6450 struct sk_buff *clone = skb_clone(skb, gfp);
6451
6452 if (!clone)
6453 return NULL;
6454
6455 if (pskb_carve(clone, off, gfp) < 0 ||
6456 pskb_trim(clone, to_copy)) {
6457 kfree_skb(clone);
6458 return NULL;
6459 }
6460 return clone;
6461}
6462EXPORT_SYMBOL(pskb_extract);
6463
6464/**
6465 * skb_condense - try to get rid of fragments/frag_list if possible
6466 * @skb: buffer
6467 *
6468 * Can be used to save memory before skb is added to a busy queue.
6469 * If packet has bytes in frags and enough tail room in skb->head,
6470 * pull all of them, so that we can free the frags right now and adjust
6471 * truesize.
6472 * Notes:
6473 * We do not reallocate skb->head thus can not fail.
6474 * Caller must re-evaluate skb->truesize if needed.
6475 */
6476void skb_condense(struct sk_buff *skb)
6477{
6478 if (skb->data_len) {
6479 if (skb->data_len > skb->end - skb->tail ||
6480 skb_cloned(skb))
6481 return;
6482
6483 /* Nice, we can free page frag(s) right now */
6484 __pskb_pull_tail(skb, skb->data_len);
6485 }
6486 /* At this point, skb->truesize might be over estimated,
6487 * because skb had a fragment, and fragments do not tell
6488 * their truesize.
6489 * When we pulled its content into skb->head, fragment
6490 * was freed, but __pskb_pull_tail() could not possibly
6491 * adjust skb->truesize, not knowing the frag truesize.
6492 */
6493 skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
6494}
6495EXPORT_SYMBOL(skb_condense);
6496
6497#ifdef CONFIG_SKB_EXTENSIONS
6498static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id)
6499{
6500 return (void *)ext + (ext->offset[id] * SKB_EXT_ALIGN_VALUE);
6501}
6502
6503/**
6504 * __skb_ext_alloc - allocate a new skb extensions storage
6505 *
6506 * @flags: See kmalloc().
6507 *
6508 * Returns the newly allocated pointer. The pointer can later attached to a
6509 * skb via __skb_ext_set().
6510 * Note: caller must handle the skb_ext as an opaque data.
6511 */
6512struct skb_ext *__skb_ext_alloc(gfp_t flags)
6513{
6514 struct skb_ext *new = kmem_cache_alloc(skbuff_ext_cache, flags);
6515
6516 if (new) {
6517 memset(new->offset, 0, sizeof(new->offset));
6518 refcount_set(&new->refcnt, 1);
6519 }
6520
6521 return new;
6522}
6523
6524static struct skb_ext *skb_ext_maybe_cow(struct skb_ext *old,
6525 unsigned int old_active)
6526{
6527 struct skb_ext *new;
6528
6529 if (refcount_read(&old->refcnt) == 1)
6530 return old;
6531
6532 new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC);
6533 if (!new)
6534 return NULL;
6535
6536 memcpy(new, old, old->chunks * SKB_EXT_ALIGN_VALUE);
6537 refcount_set(&new->refcnt, 1);
6538
6539#ifdef CONFIG_XFRM
6540 if (old_active & (1 << SKB_EXT_SEC_PATH)) {
6541 struct sec_path *sp = skb_ext_get_ptr(old, SKB_EXT_SEC_PATH);
6542 unsigned int i;
6543
6544 for (i = 0; i < sp->len; i++)
6545 xfrm_state_hold(sp->xvec[i]);
6546 }
6547#endif
6548 __skb_ext_put(old);
6549 return new;
6550}
6551
6552/**
6553 * __skb_ext_set - attach the specified extension storage to this skb
6554 * @skb: buffer
6555 * @id: extension id
6556 * @ext: extension storage previously allocated via __skb_ext_alloc()
6557 *
6558 * Existing extensions, if any, are cleared.
6559 *
6560 * Returns the pointer to the extension.
6561 */
6562void *__skb_ext_set(struct sk_buff *skb, enum skb_ext_id id,
6563 struct skb_ext *ext)
6564{
6565 unsigned int newlen, newoff = SKB_EXT_CHUNKSIZEOF(*ext);
6566
6567 skb_ext_put(skb);
6568 newlen = newoff + skb_ext_type_len[id];
6569 ext->chunks = newlen;
6570 ext->offset[id] = newoff;
6571 skb->extensions = ext;
6572 skb->active_extensions = 1 << id;
6573 return skb_ext_get_ptr(ext, id);
6574}
6575
6576/**
6577 * skb_ext_add - allocate space for given extension, COW if needed
6578 * @skb: buffer
6579 * @id: extension to allocate space for
6580 *
6581 * Allocates enough space for the given extension.
6582 * If the extension is already present, a pointer to that extension
6583 * is returned.
6584 *
6585 * If the skb was cloned, COW applies and the returned memory can be
6586 * modified without changing the extension space of clones buffers.
6587 *
6588 * Returns pointer to the extension or NULL on allocation failure.
6589 */
6590void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id)
6591{
6592 struct skb_ext *new, *old = NULL;
6593 unsigned int newlen, newoff;
6594
6595 if (skb->active_extensions) {
6596 old = skb->extensions;
6597
6598 new = skb_ext_maybe_cow(old, skb->active_extensions);
6599 if (!new)
6600 return NULL;
6601
6602 if (__skb_ext_exist(new, id))
6603 goto set_active;
6604
6605 newoff = new->chunks;
6606 } else {
6607 newoff = SKB_EXT_CHUNKSIZEOF(*new);
6608
6609 new = __skb_ext_alloc(GFP_ATOMIC);
6610 if (!new)
6611 return NULL;
6612 }
6613
6614 newlen = newoff + skb_ext_type_len[id];
6615 new->chunks = newlen;
6616 new->offset[id] = newoff;
6617set_active:
6618 skb->slow_gro = 1;
6619 skb->extensions = new;
6620 skb->active_extensions |= 1 << id;
6621 return skb_ext_get_ptr(new, id);
6622}
6623EXPORT_SYMBOL(skb_ext_add);
6624
6625#ifdef CONFIG_XFRM
6626static void skb_ext_put_sp(struct sec_path *sp)
6627{
6628 unsigned int i;
6629
6630 for (i = 0; i < sp->len; i++)
6631 xfrm_state_put(sp->xvec[i]);
6632}
6633#endif
6634
6635#ifdef CONFIG_MCTP_FLOWS
6636static void skb_ext_put_mctp(struct mctp_flow *flow)
6637{
6638 if (flow->key)
6639 mctp_key_unref(flow->key);
6640}
6641#endif
6642
6643void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
6644{
6645 struct skb_ext *ext = skb->extensions;
6646
6647 skb->active_extensions &= ~(1 << id);
6648 if (skb->active_extensions == 0) {
6649 skb->extensions = NULL;
6650 __skb_ext_put(ext);
6651#ifdef CONFIG_XFRM
6652 } else if (id == SKB_EXT_SEC_PATH &&
6653 refcount_read(&ext->refcnt) == 1) {
6654 struct sec_path *sp = skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH);
6655
6656 skb_ext_put_sp(sp);
6657 sp->len = 0;
6658#endif
6659 }
6660}
6661EXPORT_SYMBOL(__skb_ext_del);
6662
6663void __skb_ext_put(struct skb_ext *ext)
6664{
6665 /* If this is last clone, nothing can increment
6666 * it after check passes. Avoids one atomic op.
6667 */
6668 if (refcount_read(&ext->refcnt) == 1)
6669 goto free_now;
6670
6671 if (!refcount_dec_and_test(&ext->refcnt))
6672 return;
6673free_now:
6674#ifdef CONFIG_XFRM
6675 if (__skb_ext_exist(ext, SKB_EXT_SEC_PATH))
6676 skb_ext_put_sp(skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH));
6677#endif
6678#ifdef CONFIG_MCTP_FLOWS
6679 if (__skb_ext_exist(ext, SKB_EXT_MCTP))
6680 skb_ext_put_mctp(skb_ext_get_ptr(ext, SKB_EXT_MCTP));
6681#endif
6682
6683 kmem_cache_free(skbuff_ext_cache, ext);
6684}
6685EXPORT_SYMBOL(__skb_ext_put);
6686#endif /* CONFIG_SKB_EXTENSIONS */
6687
6688/**
6689 * skb_attempt_defer_free - queue skb for remote freeing
6690 * @skb: buffer
6691 *
6692 * Put @skb in a per-cpu list, using the cpu which
6693 * allocated the skb/pages to reduce false sharing
6694 * and memory zone spinlock contention.
6695 */
6696void skb_attempt_defer_free(struct sk_buff *skb)
6697{
6698 int cpu = skb->alloc_cpu;
6699 struct softnet_data *sd;
6700 unsigned long flags;
6701 unsigned int defer_max;
6702 bool kick;
6703
6704 if (WARN_ON_ONCE(cpu >= nr_cpu_ids) ||
6705 !cpu_online(cpu) ||
6706 cpu == raw_smp_processor_id()) {
6707nodefer: __kfree_skb(skb);
6708 return;
6709 }
6710
6711 sd = &per_cpu(softnet_data, cpu);
6712 defer_max = READ_ONCE(sysctl_skb_defer_max);
6713 if (READ_ONCE(sd->defer_count) >= defer_max)
6714 goto nodefer;
6715
6716 spin_lock_irqsave(&sd->defer_lock, flags);
6717 /* Send an IPI every time queue reaches half capacity. */
6718 kick = sd->defer_count == (defer_max >> 1);
6719 /* Paired with the READ_ONCE() few lines above */
6720 WRITE_ONCE(sd->defer_count, sd->defer_count + 1);
6721
6722 skb->next = sd->defer_list;
6723 /* Paired with READ_ONCE() in skb_defer_free_flush() */
6724 WRITE_ONCE(sd->defer_list, skb);
6725 spin_unlock_irqrestore(&sd->defer_lock, flags);
6726
6727 /* Make sure to trigger NET_RX_SOFTIRQ on the remote CPU
6728 * if we are unlucky enough (this seems very unlikely).
6729 */
6730 if (unlikely(kick) && !cmpxchg(&sd->defer_ipi_scheduled, 0, 1))
6731 smp_call_function_single_async(cpu, &sd->defer_csd);
6732}