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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/*
2 * Routines having to do with the 'struct sk_buff' memory handlers.
3 *
4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
5 * Florian La Roche <rzsfl@rz.uni-sb.de>
6 *
7 * Fixes:
8 * Alan Cox : Fixed the worst of the load
9 * balancer bugs.
10 * Dave Platt : Interrupt stacking fix.
11 * Richard Kooijman : Timestamp fixes.
12 * Alan Cox : Changed buffer format.
13 * Alan Cox : destructor hook for AF_UNIX etc.
14 * Linus Torvalds : Better skb_clone.
15 * Alan Cox : Added skb_copy.
16 * Alan Cox : Added all the changed routines Linus
17 * only put in the headers
18 * Ray VanTassle : Fixed --skb->lock in free
19 * Alan Cox : skb_copy copy arp field
20 * Andi Kleen : slabified it.
21 * Robert Olsson : Removed skb_head_pool
22 *
23 * NOTE:
24 * The __skb_ routines should be called with interrupts
25 * disabled, or you better be *real* sure that the operation is atomic
26 * with respect to whatever list is being frobbed (e.g. via lock_sock()
27 * or via disabling bottom half handlers, etc).
28 *
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
33 */
34
35/*
36 * The functions in this file will not compile correctly with gcc 2.4.x
37 */
38
39#include <linux/module.h>
40#include <linux/types.h>
41#include <linux/kernel.h>
42#include <linux/kmemcheck.h>
43#include <linux/mm.h>
44#include <linux/interrupt.h>
45#include <linux/in.h>
46#include <linux/inet.h>
47#include <linux/slab.h>
48#include <linux/netdevice.h>
49#ifdef CONFIG_NET_CLS_ACT
50#include <net/pkt_sched.h>
51#endif
52#include <linux/string.h>
53#include <linux/skbuff.h>
54#include <linux/splice.h>
55#include <linux/cache.h>
56#include <linux/rtnetlink.h>
57#include <linux/init.h>
58#include <linux/scatterlist.h>
59#include <linux/errqueue.h>
60#include <linux/prefetch.h>
61
62#include <net/protocol.h>
63#include <net/dst.h>
64#include <net/sock.h>
65#include <net/checksum.h>
66#include <net/xfrm.h>
67
68#include <asm/uaccess.h>
69#include <asm/system.h>
70#include <trace/events/skb.h>
71
72#include "kmap_skb.h"
73
74static struct kmem_cache *skbuff_head_cache __read_mostly;
75static struct kmem_cache *skbuff_fclone_cache __read_mostly;
76
77static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
78 struct pipe_buffer *buf)
79{
80 put_page(buf->page);
81}
82
83static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
84 struct pipe_buffer *buf)
85{
86 get_page(buf->page);
87}
88
89static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
90 struct pipe_buffer *buf)
91{
92 return 1;
93}
94
95
96/* Pipe buffer operations for a socket. */
97static const struct pipe_buf_operations sock_pipe_buf_ops = {
98 .can_merge = 0,
99 .map = generic_pipe_buf_map,
100 .unmap = generic_pipe_buf_unmap,
101 .confirm = generic_pipe_buf_confirm,
102 .release = sock_pipe_buf_release,
103 .steal = sock_pipe_buf_steal,
104 .get = sock_pipe_buf_get,
105};
106
107/*
108 * Keep out-of-line to prevent kernel bloat.
109 * __builtin_return_address is not used because it is not always
110 * reliable.
111 */
112
113/**
114 * skb_over_panic - private function
115 * @skb: buffer
116 * @sz: size
117 * @here: address
118 *
119 * Out of line support code for skb_put(). Not user callable.
120 */
121static void skb_over_panic(struct sk_buff *skb, int sz, void *here)
122{
123 printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p "
124 "data:%p tail:%#lx end:%#lx dev:%s\n",
125 here, skb->len, sz, skb->head, skb->data,
126 (unsigned long)skb->tail, (unsigned long)skb->end,
127 skb->dev ? skb->dev->name : "<NULL>");
128 BUG();
129}
130
131/**
132 * skb_under_panic - private function
133 * @skb: buffer
134 * @sz: size
135 * @here: address
136 *
137 * Out of line support code for skb_push(). Not user callable.
138 */
139
140static void skb_under_panic(struct sk_buff *skb, int sz, void *here)
141{
142 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p "
143 "data:%p tail:%#lx end:%#lx dev:%s\n",
144 here, skb->len, sz, skb->head, skb->data,
145 (unsigned long)skb->tail, (unsigned long)skb->end,
146 skb->dev ? skb->dev->name : "<NULL>");
147 BUG();
148}
149
150/* Allocate a new skbuff. We do this ourselves so we can fill in a few
151 * 'private' fields and also do memory statistics to find all the
152 * [BEEP] leaks.
153 *
154 */
155
156/**
157 * __alloc_skb - allocate a network buffer
158 * @size: size to allocate
159 * @gfp_mask: allocation mask
160 * @fclone: allocate from fclone cache instead of head cache
161 * and allocate a cloned (child) skb
162 * @node: numa node to allocate memory on
163 *
164 * Allocate a new &sk_buff. The returned buffer has no headroom and a
165 * tail room of size bytes. The object has a reference count of one.
166 * The return is the buffer. On a failure the return is %NULL.
167 *
168 * Buffers may only be allocated from interrupts using a @gfp_mask of
169 * %GFP_ATOMIC.
170 */
171struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
172 int fclone, int node)
173{
174 struct kmem_cache *cache;
175 struct skb_shared_info *shinfo;
176 struct sk_buff *skb;
177 u8 *data;
178
179 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache;
180
181 /* Get the HEAD */
182 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
183 if (!skb)
184 goto out;
185 prefetchw(skb);
186
187 size = SKB_DATA_ALIGN(size);
188 data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
189 gfp_mask, node);
190 if (!data)
191 goto nodata;
192 prefetchw(data + size);
193
194 /*
195 * Only clear those fields we need to clear, not those that we will
196 * actually initialise below. Hence, don't put any more fields after
197 * the tail pointer in struct sk_buff!
198 */
199 memset(skb, 0, offsetof(struct sk_buff, tail));
200 skb->truesize = size + sizeof(struct sk_buff);
201 atomic_set(&skb->users, 1);
202 skb->head = data;
203 skb->data = data;
204 skb_reset_tail_pointer(skb);
205 skb->end = skb->tail + size;
206#ifdef NET_SKBUFF_DATA_USES_OFFSET
207 skb->mac_header = ~0U;
208#endif
209
210 /* make sure we initialize shinfo sequentially */
211 shinfo = skb_shinfo(skb);
212 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
213 atomic_set(&shinfo->dataref, 1);
214 kmemcheck_annotate_variable(shinfo->destructor_arg);
215
216 if (fclone) {
217 struct sk_buff *child = skb + 1;
218 atomic_t *fclone_ref = (atomic_t *) (child + 1);
219
220 kmemcheck_annotate_bitfield(child, flags1);
221 kmemcheck_annotate_bitfield(child, flags2);
222 skb->fclone = SKB_FCLONE_ORIG;
223 atomic_set(fclone_ref, 1);
224
225 child->fclone = SKB_FCLONE_UNAVAILABLE;
226 }
227out:
228 return skb;
229nodata:
230 kmem_cache_free(cache, skb);
231 skb = NULL;
232 goto out;
233}
234EXPORT_SYMBOL(__alloc_skb);
235
236/**
237 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
238 * @dev: network device to receive on
239 * @length: length to allocate
240 * @gfp_mask: get_free_pages mask, passed to alloc_skb
241 *
242 * Allocate a new &sk_buff and assign it a usage count of one. The
243 * buffer has unspecified headroom built in. Users should allocate
244 * the headroom they think they need without accounting for the
245 * built in space. The built in space is used for optimisations.
246 *
247 * %NULL is returned if there is no free memory.
248 */
249struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
250 unsigned int length, gfp_t gfp_mask)
251{
252 struct sk_buff *skb;
253
254 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, NUMA_NO_NODE);
255 if (likely(skb)) {
256 skb_reserve(skb, NET_SKB_PAD);
257 skb->dev = dev;
258 }
259 return skb;
260}
261EXPORT_SYMBOL(__netdev_alloc_skb);
262
263void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
264 int size)
265{
266 skb_fill_page_desc(skb, i, page, off, size);
267 skb->len += size;
268 skb->data_len += size;
269 skb->truesize += size;
270}
271EXPORT_SYMBOL(skb_add_rx_frag);
272
273/**
274 * dev_alloc_skb - allocate an skbuff for receiving
275 * @length: length to allocate
276 *
277 * Allocate a new &sk_buff and assign it a usage count of one. The
278 * buffer has unspecified headroom built in. Users should allocate
279 * the headroom they think they need without accounting for the
280 * built in space. The built in space is used for optimisations.
281 *
282 * %NULL is returned if there is no free memory. Although this function
283 * allocates memory it can be called from an interrupt.
284 */
285struct sk_buff *dev_alloc_skb(unsigned int length)
286{
287 /*
288 * There is more code here than it seems:
289 * __dev_alloc_skb is an inline
290 */
291 return __dev_alloc_skb(length, GFP_ATOMIC);
292}
293EXPORT_SYMBOL(dev_alloc_skb);
294
295static void skb_drop_list(struct sk_buff **listp)
296{
297 struct sk_buff *list = *listp;
298
299 *listp = NULL;
300
301 do {
302 struct sk_buff *this = list;
303 list = list->next;
304 kfree_skb(this);
305 } while (list);
306}
307
308static inline void skb_drop_fraglist(struct sk_buff *skb)
309{
310 skb_drop_list(&skb_shinfo(skb)->frag_list);
311}
312
313static void skb_clone_fraglist(struct sk_buff *skb)
314{
315 struct sk_buff *list;
316
317 skb_walk_frags(skb, list)
318 skb_get(list);
319}
320
321static void skb_release_data(struct sk_buff *skb)
322{
323 if (!skb->cloned ||
324 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
325 &skb_shinfo(skb)->dataref)) {
326 if (skb_shinfo(skb)->nr_frags) {
327 int i;
328 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
329 put_page(skb_shinfo(skb)->frags[i].page);
330 }
331
332 /*
333 * If skb buf is from userspace, we need to notify the caller
334 * the lower device DMA has done;
335 */
336 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
337 struct ubuf_info *uarg;
338
339 uarg = skb_shinfo(skb)->destructor_arg;
340 if (uarg->callback)
341 uarg->callback(uarg);
342 }
343
344 if (skb_has_frag_list(skb))
345 skb_drop_fraglist(skb);
346
347 kfree(skb->head);
348 }
349}
350
351/*
352 * Free an skbuff by memory without cleaning the state.
353 */
354static void kfree_skbmem(struct sk_buff *skb)
355{
356 struct sk_buff *other;
357 atomic_t *fclone_ref;
358
359 switch (skb->fclone) {
360 case SKB_FCLONE_UNAVAILABLE:
361 kmem_cache_free(skbuff_head_cache, skb);
362 break;
363
364 case SKB_FCLONE_ORIG:
365 fclone_ref = (atomic_t *) (skb + 2);
366 if (atomic_dec_and_test(fclone_ref))
367 kmem_cache_free(skbuff_fclone_cache, skb);
368 break;
369
370 case SKB_FCLONE_CLONE:
371 fclone_ref = (atomic_t *) (skb + 1);
372 other = skb - 1;
373
374 /* The clone portion is available for
375 * fast-cloning again.
376 */
377 skb->fclone = SKB_FCLONE_UNAVAILABLE;
378
379 if (atomic_dec_and_test(fclone_ref))
380 kmem_cache_free(skbuff_fclone_cache, other);
381 break;
382 }
383}
384
385static void skb_release_head_state(struct sk_buff *skb)
386{
387 skb_dst_drop(skb);
388#ifdef CONFIG_XFRM
389 secpath_put(skb->sp);
390#endif
391 if (skb->destructor) {
392 WARN_ON(in_irq());
393 skb->destructor(skb);
394 }
395#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
396 nf_conntrack_put(skb->nfct);
397#endif
398#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
399 nf_conntrack_put_reasm(skb->nfct_reasm);
400#endif
401#ifdef CONFIG_BRIDGE_NETFILTER
402 nf_bridge_put(skb->nf_bridge);
403#endif
404/* XXX: IS this still necessary? - JHS */
405#ifdef CONFIG_NET_SCHED
406 skb->tc_index = 0;
407#ifdef CONFIG_NET_CLS_ACT
408 skb->tc_verd = 0;
409#endif
410#endif
411}
412
413/* Free everything but the sk_buff shell. */
414static void skb_release_all(struct sk_buff *skb)
415{
416 skb_release_head_state(skb);
417 skb_release_data(skb);
418}
419
420/**
421 * __kfree_skb - private function
422 * @skb: buffer
423 *
424 * Free an sk_buff. Release anything attached to the buffer.
425 * Clean the state. This is an internal helper function. Users should
426 * always call kfree_skb
427 */
428
429void __kfree_skb(struct sk_buff *skb)
430{
431 skb_release_all(skb);
432 kfree_skbmem(skb);
433}
434EXPORT_SYMBOL(__kfree_skb);
435
436/**
437 * kfree_skb - free an sk_buff
438 * @skb: buffer to free
439 *
440 * Drop a reference to the buffer and free it if the usage count has
441 * hit zero.
442 */
443void kfree_skb(struct sk_buff *skb)
444{
445 if (unlikely(!skb))
446 return;
447 if (likely(atomic_read(&skb->users) == 1))
448 smp_rmb();
449 else if (likely(!atomic_dec_and_test(&skb->users)))
450 return;
451 trace_kfree_skb(skb, __builtin_return_address(0));
452 __kfree_skb(skb);
453}
454EXPORT_SYMBOL(kfree_skb);
455
456/**
457 * consume_skb - free an skbuff
458 * @skb: buffer to free
459 *
460 * Drop a ref to the buffer and free it if the usage count has hit zero
461 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
462 * is being dropped after a failure and notes that
463 */
464void consume_skb(struct sk_buff *skb)
465{
466 if (unlikely(!skb))
467 return;
468 if (likely(atomic_read(&skb->users) == 1))
469 smp_rmb();
470 else if (likely(!atomic_dec_and_test(&skb->users)))
471 return;
472 trace_consume_skb(skb);
473 __kfree_skb(skb);
474}
475EXPORT_SYMBOL(consume_skb);
476
477/**
478 * skb_recycle_check - check if skb can be reused for receive
479 * @skb: buffer
480 * @skb_size: minimum receive buffer size
481 *
482 * Checks that the skb passed in is not shared or cloned, and
483 * that it is linear and its head portion at least as large as
484 * skb_size so that it can be recycled as a receive buffer.
485 * If these conditions are met, this function does any necessary
486 * reference count dropping and cleans up the skbuff as if it
487 * just came from __alloc_skb().
488 */
489bool skb_recycle_check(struct sk_buff *skb, int skb_size)
490{
491 struct skb_shared_info *shinfo;
492
493 if (irqs_disabled())
494 return false;
495
496 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)
497 return false;
498
499 if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
500 return false;
501
502 skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
503 if (skb_end_pointer(skb) - skb->head < skb_size)
504 return false;
505
506 if (skb_shared(skb) || skb_cloned(skb))
507 return false;
508
509 skb_release_head_state(skb);
510
511 shinfo = skb_shinfo(skb);
512 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
513 atomic_set(&shinfo->dataref, 1);
514
515 memset(skb, 0, offsetof(struct sk_buff, tail));
516 skb->data = skb->head + NET_SKB_PAD;
517 skb_reset_tail_pointer(skb);
518
519 return true;
520}
521EXPORT_SYMBOL(skb_recycle_check);
522
523static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
524{
525 new->tstamp = old->tstamp;
526 new->dev = old->dev;
527 new->transport_header = old->transport_header;
528 new->network_header = old->network_header;
529 new->mac_header = old->mac_header;
530 skb_dst_copy(new, old);
531 new->rxhash = old->rxhash;
532#ifdef CONFIG_XFRM
533 new->sp = secpath_get(old->sp);
534#endif
535 memcpy(new->cb, old->cb, sizeof(old->cb));
536 new->csum = old->csum;
537 new->local_df = old->local_df;
538 new->pkt_type = old->pkt_type;
539 new->ip_summed = old->ip_summed;
540 skb_copy_queue_mapping(new, old);
541 new->priority = old->priority;
542#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
543 new->ipvs_property = old->ipvs_property;
544#endif
545 new->protocol = old->protocol;
546 new->mark = old->mark;
547 new->skb_iif = old->skb_iif;
548 __nf_copy(new, old);
549#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
550 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
551 new->nf_trace = old->nf_trace;
552#endif
553#ifdef CONFIG_NET_SCHED
554 new->tc_index = old->tc_index;
555#ifdef CONFIG_NET_CLS_ACT
556 new->tc_verd = old->tc_verd;
557#endif
558#endif
559 new->vlan_tci = old->vlan_tci;
560
561 skb_copy_secmark(new, old);
562}
563
564/*
565 * You should not add any new code to this function. Add it to
566 * __copy_skb_header above instead.
567 */
568static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
569{
570#define C(x) n->x = skb->x
571
572 n->next = n->prev = NULL;
573 n->sk = NULL;
574 __copy_skb_header(n, skb);
575
576 C(len);
577 C(data_len);
578 C(mac_len);
579 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
580 n->cloned = 1;
581 n->nohdr = 0;
582 n->destructor = NULL;
583 C(tail);
584 C(end);
585 C(head);
586 C(data);
587 C(truesize);
588 atomic_set(&n->users, 1);
589
590 atomic_inc(&(skb_shinfo(skb)->dataref));
591 skb->cloned = 1;
592
593 return n;
594#undef C
595}
596
597/**
598 * skb_morph - morph one skb into another
599 * @dst: the skb to receive the contents
600 * @src: the skb to supply the contents
601 *
602 * This is identical to skb_clone except that the target skb is
603 * supplied by the user.
604 *
605 * The target skb is returned upon exit.
606 */
607struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
608{
609 skb_release_all(dst);
610 return __skb_clone(dst, src);
611}
612EXPORT_SYMBOL_GPL(skb_morph);
613
614/* skb_copy_ubufs - copy userspace skb frags buffers to kernel
615 * @skb: the skb to modify
616 * @gfp_mask: allocation priority
617 *
618 * This must be called on SKBTX_DEV_ZEROCOPY skb.
619 * It will copy all frags into kernel and drop the reference
620 * to userspace pages.
621 *
622 * If this function is called from an interrupt gfp_mask() must be
623 * %GFP_ATOMIC.
624 *
625 * Returns 0 on success or a negative error code on failure
626 * to allocate kernel memory to copy to.
627 */
628int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
629{
630 int i;
631 int num_frags = skb_shinfo(skb)->nr_frags;
632 struct page *page, *head = NULL;
633 struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;
634
635 for (i = 0; i < num_frags; i++) {
636 u8 *vaddr;
637 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
638
639 page = alloc_page(GFP_ATOMIC);
640 if (!page) {
641 while (head) {
642 struct page *next = (struct page *)head->private;
643 put_page(head);
644 head = next;
645 }
646 return -ENOMEM;
647 }
648 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
649 memcpy(page_address(page),
650 vaddr + f->page_offset, f->size);
651 kunmap_skb_frag(vaddr);
652 page->private = (unsigned long)head;
653 head = page;
654 }
655
656 /* skb frags release userspace buffers */
657 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
658 put_page(skb_shinfo(skb)->frags[i].page);
659
660 uarg->callback(uarg);
661
662 /* skb frags point to kernel buffers */
663 for (i = skb_shinfo(skb)->nr_frags; i > 0; i--) {
664 skb_shinfo(skb)->frags[i - 1].page_offset = 0;
665 skb_shinfo(skb)->frags[i - 1].page = head;
666 head = (struct page *)head->private;
667 }
668
669 skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
670 return 0;
671}
672
673
674/**
675 * skb_clone - duplicate an sk_buff
676 * @skb: buffer to clone
677 * @gfp_mask: allocation priority
678 *
679 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
680 * copies share the same packet data but not structure. The new
681 * buffer has a reference count of 1. If the allocation fails the
682 * function returns %NULL otherwise the new buffer is returned.
683 *
684 * If this function is called from an interrupt gfp_mask() must be
685 * %GFP_ATOMIC.
686 */
687
688struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
689{
690 struct sk_buff *n;
691
692 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
693 if (skb_copy_ubufs(skb, gfp_mask))
694 return NULL;
695 }
696
697 n = skb + 1;
698 if (skb->fclone == SKB_FCLONE_ORIG &&
699 n->fclone == SKB_FCLONE_UNAVAILABLE) {
700 atomic_t *fclone_ref = (atomic_t *) (n + 1);
701 n->fclone = SKB_FCLONE_CLONE;
702 atomic_inc(fclone_ref);
703 } else {
704 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
705 if (!n)
706 return NULL;
707
708 kmemcheck_annotate_bitfield(n, flags1);
709 kmemcheck_annotate_bitfield(n, flags2);
710 n->fclone = SKB_FCLONE_UNAVAILABLE;
711 }
712
713 return __skb_clone(n, skb);
714}
715EXPORT_SYMBOL(skb_clone);
716
717static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
718{
719#ifndef NET_SKBUFF_DATA_USES_OFFSET
720 /*
721 * Shift between the two data areas in bytes
722 */
723 unsigned long offset = new->data - old->data;
724#endif
725
726 __copy_skb_header(new, old);
727
728#ifndef NET_SKBUFF_DATA_USES_OFFSET
729 /* {transport,network,mac}_header are relative to skb->head */
730 new->transport_header += offset;
731 new->network_header += offset;
732 if (skb_mac_header_was_set(new))
733 new->mac_header += offset;
734#endif
735 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
736 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
737 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
738}
739
740/**
741 * skb_copy - create private copy of an sk_buff
742 * @skb: buffer to copy
743 * @gfp_mask: allocation priority
744 *
745 * Make a copy of both an &sk_buff and its data. This is used when the
746 * caller wishes to modify the data and needs a private copy of the
747 * data to alter. Returns %NULL on failure or the pointer to the buffer
748 * on success. The returned buffer has a reference count of 1.
749 *
750 * As by-product this function converts non-linear &sk_buff to linear
751 * one, so that &sk_buff becomes completely private and caller is allowed
752 * to modify all the data of returned buffer. This means that this
753 * function is not recommended for use in circumstances when only
754 * header is going to be modified. Use pskb_copy() instead.
755 */
756
757struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
758{
759 int headerlen = skb_headroom(skb);
760 unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
761 struct sk_buff *n = alloc_skb(size, gfp_mask);
762
763 if (!n)
764 return NULL;
765
766 /* Set the data pointer */
767 skb_reserve(n, headerlen);
768 /* Set the tail pointer and length */
769 skb_put(n, skb->len);
770
771 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
772 BUG();
773
774 copy_skb_header(n, skb);
775 return n;
776}
777EXPORT_SYMBOL(skb_copy);
778
779/**
780 * pskb_copy - create copy of an sk_buff with private head.
781 * @skb: buffer to copy
782 * @gfp_mask: allocation priority
783 *
784 * Make a copy of both an &sk_buff and part of its data, located
785 * in header. Fragmented data remain shared. This is used when
786 * the caller wishes to modify only header of &sk_buff and needs
787 * private copy of the header to alter. Returns %NULL on failure
788 * or the pointer to the buffer on success.
789 * The returned buffer has a reference count of 1.
790 */
791
792struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
793{
794 unsigned int size = skb_end_pointer(skb) - skb->head;
795 struct sk_buff *n = alloc_skb(size, gfp_mask);
796
797 if (!n)
798 goto out;
799
800 /* Set the data pointer */
801 skb_reserve(n, skb_headroom(skb));
802 /* Set the tail pointer and length */
803 skb_put(n, skb_headlen(skb));
804 /* Copy the bytes */
805 skb_copy_from_linear_data(skb, n->data, n->len);
806
807 n->truesize += skb->data_len;
808 n->data_len = skb->data_len;
809 n->len = skb->len;
810
811 if (skb_shinfo(skb)->nr_frags) {
812 int i;
813
814 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
815 if (skb_copy_ubufs(skb, gfp_mask)) {
816 kfree_skb(n);
817 n = NULL;
818 goto out;
819 }
820 }
821 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
822 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
823 get_page(skb_shinfo(n)->frags[i].page);
824 }
825 skb_shinfo(n)->nr_frags = i;
826 }
827
828 if (skb_has_frag_list(skb)) {
829 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
830 skb_clone_fraglist(n);
831 }
832
833 copy_skb_header(n, skb);
834out:
835 return n;
836}
837EXPORT_SYMBOL(pskb_copy);
838
839/**
840 * pskb_expand_head - reallocate header of &sk_buff
841 * @skb: buffer to reallocate
842 * @nhead: room to add at head
843 * @ntail: room to add at tail
844 * @gfp_mask: allocation priority
845 *
846 * Expands (or creates identical copy, if &nhead and &ntail are zero)
847 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have
848 * reference count of 1. Returns zero in the case of success or error,
849 * if expansion failed. In the last case, &sk_buff is not changed.
850 *
851 * All the pointers pointing into skb header may change and must be
852 * reloaded after call to this function.
853 */
854
855int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
856 gfp_t gfp_mask)
857{
858 int i;
859 u8 *data;
860 int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail;
861 long off;
862 bool fastpath;
863
864 BUG_ON(nhead < 0);
865
866 if (skb_shared(skb))
867 BUG();
868
869 size = SKB_DATA_ALIGN(size);
870
871 /* Check if we can avoid taking references on fragments if we own
872 * the last reference on skb->head. (see skb_release_data())
873 */
874 if (!skb->cloned)
875 fastpath = true;
876 else {
877 int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;
878 fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
879 }
880
881 if (fastpath &&
882 size + sizeof(struct skb_shared_info) <= ksize(skb->head)) {
883 memmove(skb->head + size, skb_shinfo(skb),
884 offsetof(struct skb_shared_info,
885 frags[skb_shinfo(skb)->nr_frags]));
886 memmove(skb->head + nhead, skb->head,
887 skb_tail_pointer(skb) - skb->head);
888 off = nhead;
889 goto adjust_others;
890 }
891
892 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
893 if (!data)
894 goto nodata;
895
896 /* Copy only real data... and, alas, header. This should be
897 * optimized for the cases when header is void.
898 */
899 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
900
901 memcpy((struct skb_shared_info *)(data + size),
902 skb_shinfo(skb),
903 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
904
905 if (fastpath) {
906 kfree(skb->head);
907 } else {
908 /* copy this zero copy skb frags */
909 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
910 if (skb_copy_ubufs(skb, gfp_mask))
911 goto nofrags;
912 }
913 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
914 get_page(skb_shinfo(skb)->frags[i].page);
915
916 if (skb_has_frag_list(skb))
917 skb_clone_fraglist(skb);
918
919 skb_release_data(skb);
920 }
921 off = (data + nhead) - skb->head;
922
923 skb->head = data;
924adjust_others:
925 skb->data += off;
926#ifdef NET_SKBUFF_DATA_USES_OFFSET
927 skb->end = size;
928 off = nhead;
929#else
930 skb->end = skb->head + size;
931#endif
932 /* {transport,network,mac}_header and tail are relative to skb->head */
933 skb->tail += off;
934 skb->transport_header += off;
935 skb->network_header += off;
936 if (skb_mac_header_was_set(skb))
937 skb->mac_header += off;
938 /* Only adjust this if it actually is csum_start rather than csum */
939 if (skb->ip_summed == CHECKSUM_PARTIAL)
940 skb->csum_start += nhead;
941 skb->cloned = 0;
942 skb->hdr_len = 0;
943 skb->nohdr = 0;
944 atomic_set(&skb_shinfo(skb)->dataref, 1);
945 return 0;
946
947nofrags:
948 kfree(data);
949nodata:
950 return -ENOMEM;
951}
952EXPORT_SYMBOL(pskb_expand_head);
953
954/* Make private copy of skb with writable head and some headroom */
955
956struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
957{
958 struct sk_buff *skb2;
959 int delta = headroom - skb_headroom(skb);
960
961 if (delta <= 0)
962 skb2 = pskb_copy(skb, GFP_ATOMIC);
963 else {
964 skb2 = skb_clone(skb, GFP_ATOMIC);
965 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
966 GFP_ATOMIC)) {
967 kfree_skb(skb2);
968 skb2 = NULL;
969 }
970 }
971 return skb2;
972}
973EXPORT_SYMBOL(skb_realloc_headroom);
974
975/**
976 * skb_copy_expand - copy and expand sk_buff
977 * @skb: buffer to copy
978 * @newheadroom: new free bytes at head
979 * @newtailroom: new free bytes at tail
980 * @gfp_mask: allocation priority
981 *
982 * Make a copy of both an &sk_buff and its data and while doing so
983 * allocate additional space.
984 *
985 * This is used when the caller wishes to modify the data and needs a
986 * private copy of the data to alter as well as more space for new fields.
987 * Returns %NULL on failure or the pointer to the buffer
988 * on success. The returned buffer has a reference count of 1.
989 *
990 * You must pass %GFP_ATOMIC as the allocation priority if this function
991 * is called from an interrupt.
992 */
993struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
994 int newheadroom, int newtailroom,
995 gfp_t gfp_mask)
996{
997 /*
998 * Allocate the copy buffer
999 */
1000 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
1001 gfp_mask);
1002 int oldheadroom = skb_headroom(skb);
1003 int head_copy_len, head_copy_off;
1004 int off;
1005
1006 if (!n)
1007 return NULL;
1008
1009 skb_reserve(n, newheadroom);
1010
1011 /* Set the tail pointer and length */
1012 skb_put(n, skb->len);
1013
1014 head_copy_len = oldheadroom;
1015 head_copy_off = 0;
1016 if (newheadroom <= head_copy_len)
1017 head_copy_len = newheadroom;
1018 else
1019 head_copy_off = newheadroom - head_copy_len;
1020
1021 /* Copy the linear header and data. */
1022 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1023 skb->len + head_copy_len))
1024 BUG();
1025
1026 copy_skb_header(n, skb);
1027
1028 off = newheadroom - oldheadroom;
1029 if (n->ip_summed == CHECKSUM_PARTIAL)
1030 n->csum_start += off;
1031#ifdef NET_SKBUFF_DATA_USES_OFFSET
1032 n->transport_header += off;
1033 n->network_header += off;
1034 if (skb_mac_header_was_set(skb))
1035 n->mac_header += off;
1036#endif
1037
1038 return n;
1039}
1040EXPORT_SYMBOL(skb_copy_expand);
1041
1042/**
1043 * skb_pad - zero pad the tail of an skb
1044 * @skb: buffer to pad
1045 * @pad: space to pad
1046 *
1047 * Ensure that a buffer is followed by a padding area that is zero
1048 * filled. Used by network drivers which may DMA or transfer data
1049 * beyond the buffer end onto the wire.
1050 *
1051 * May return error in out of memory cases. The skb is freed on error.
1052 */
1053
1054int skb_pad(struct sk_buff *skb, int pad)
1055{
1056 int err;
1057 int ntail;
1058
1059 /* If the skbuff is non linear tailroom is always zero.. */
1060 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1061 memset(skb->data+skb->len, 0, pad);
1062 return 0;
1063 }
1064
1065 ntail = skb->data_len + pad - (skb->end - skb->tail);
1066 if (likely(skb_cloned(skb) || ntail > 0)) {
1067 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1068 if (unlikely(err))
1069 goto free_skb;
1070 }
1071
1072 /* FIXME: The use of this function with non-linear skb's really needs
1073 * to be audited.
1074 */
1075 err = skb_linearize(skb);
1076 if (unlikely(err))
1077 goto free_skb;
1078
1079 memset(skb->data + skb->len, 0, pad);
1080 return 0;
1081
1082free_skb:
1083 kfree_skb(skb);
1084 return err;
1085}
1086EXPORT_SYMBOL(skb_pad);
1087
1088/**
1089 * skb_put - add data to a buffer
1090 * @skb: buffer to use
1091 * @len: amount of data to add
1092 *
1093 * This function extends the used data area of the buffer. If this would
1094 * exceed the total buffer size the kernel will panic. A pointer to the
1095 * first byte of the extra data is returned.
1096 */
1097unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
1098{
1099 unsigned char *tmp = skb_tail_pointer(skb);
1100 SKB_LINEAR_ASSERT(skb);
1101 skb->tail += len;
1102 skb->len += len;
1103 if (unlikely(skb->tail > skb->end))
1104 skb_over_panic(skb, len, __builtin_return_address(0));
1105 return tmp;
1106}
1107EXPORT_SYMBOL(skb_put);
1108
1109/**
1110 * skb_push - add data to the start of a buffer
1111 * @skb: buffer to use
1112 * @len: amount of data to add
1113 *
1114 * This function extends the used data area of the buffer at the buffer
1115 * start. If this would exceed the total buffer headroom the kernel will
1116 * panic. A pointer to the first byte of the extra data is returned.
1117 */
1118unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1119{
1120 skb->data -= len;
1121 skb->len += len;
1122 if (unlikely(skb->data<skb->head))
1123 skb_under_panic(skb, len, __builtin_return_address(0));
1124 return skb->data;
1125}
1126EXPORT_SYMBOL(skb_push);
1127
1128/**
1129 * skb_pull - remove data from the start of a buffer
1130 * @skb: buffer to use
1131 * @len: amount of data to remove
1132 *
1133 * This function removes data from the start of a buffer, returning
1134 * the memory to the headroom. A pointer to the next data in the buffer
1135 * is returned. Once the data has been pulled future pushes will overwrite
1136 * the old data.
1137 */
1138unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1139{
1140 return skb_pull_inline(skb, len);
1141}
1142EXPORT_SYMBOL(skb_pull);
1143
1144/**
1145 * skb_trim - remove end from a buffer
1146 * @skb: buffer to alter
1147 * @len: new length
1148 *
1149 * Cut the length of a buffer down by removing data from the tail. If
1150 * the buffer is already under the length specified it is not modified.
1151 * The skb must be linear.
1152 */
1153void skb_trim(struct sk_buff *skb, unsigned int len)
1154{
1155 if (skb->len > len)
1156 __skb_trim(skb, len);
1157}
1158EXPORT_SYMBOL(skb_trim);
1159
1160/* Trims skb to length len. It can change skb pointers.
1161 */
1162
1163int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1164{
1165 struct sk_buff **fragp;
1166 struct sk_buff *frag;
1167 int offset = skb_headlen(skb);
1168 int nfrags = skb_shinfo(skb)->nr_frags;
1169 int i;
1170 int err;
1171
1172 if (skb_cloned(skb) &&
1173 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1174 return err;
1175
1176 i = 0;
1177 if (offset >= len)
1178 goto drop_pages;
1179
1180 for (; i < nfrags; i++) {
1181 int end = offset + skb_shinfo(skb)->frags[i].size;
1182
1183 if (end < len) {
1184 offset = end;
1185 continue;
1186 }
1187
1188 skb_shinfo(skb)->frags[i++].size = len - offset;
1189
1190drop_pages:
1191 skb_shinfo(skb)->nr_frags = i;
1192
1193 for (; i < nfrags; i++)
1194 put_page(skb_shinfo(skb)->frags[i].page);
1195
1196 if (skb_has_frag_list(skb))
1197 skb_drop_fraglist(skb);
1198 goto done;
1199 }
1200
1201 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1202 fragp = &frag->next) {
1203 int end = offset + frag->len;
1204
1205 if (skb_shared(frag)) {
1206 struct sk_buff *nfrag;
1207
1208 nfrag = skb_clone(frag, GFP_ATOMIC);
1209 if (unlikely(!nfrag))
1210 return -ENOMEM;
1211
1212 nfrag->next = frag->next;
1213 kfree_skb(frag);
1214 frag = nfrag;
1215 *fragp = frag;
1216 }
1217
1218 if (end < len) {
1219 offset = end;
1220 continue;
1221 }
1222
1223 if (end > len &&
1224 unlikely((err = pskb_trim(frag, len - offset))))
1225 return err;
1226
1227 if (frag->next)
1228 skb_drop_list(&frag->next);
1229 break;
1230 }
1231
1232done:
1233 if (len > skb_headlen(skb)) {
1234 skb->data_len -= skb->len - len;
1235 skb->len = len;
1236 } else {
1237 skb->len = len;
1238 skb->data_len = 0;
1239 skb_set_tail_pointer(skb, len);
1240 }
1241
1242 return 0;
1243}
1244EXPORT_SYMBOL(___pskb_trim);
1245
1246/**
1247 * __pskb_pull_tail - advance tail of skb header
1248 * @skb: buffer to reallocate
1249 * @delta: number of bytes to advance tail
1250 *
1251 * The function makes a sense only on a fragmented &sk_buff,
1252 * it expands header moving its tail forward and copying necessary
1253 * data from fragmented part.
1254 *
1255 * &sk_buff MUST have reference count of 1.
1256 *
1257 * Returns %NULL (and &sk_buff does not change) if pull failed
1258 * or value of new tail of skb in the case of success.
1259 *
1260 * All the pointers pointing into skb header may change and must be
1261 * reloaded after call to this function.
1262 */
1263
1264/* Moves tail of skb head forward, copying data from fragmented part,
1265 * when it is necessary.
1266 * 1. It may fail due to malloc failure.
1267 * 2. It may change skb pointers.
1268 *
1269 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1270 */
1271unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1272{
1273 /* If skb has not enough free space at tail, get new one
1274 * plus 128 bytes for future expansions. If we have enough
1275 * room at tail, reallocate without expansion only if skb is cloned.
1276 */
1277 int i, k, eat = (skb->tail + delta) - skb->end;
1278
1279 if (eat > 0 || skb_cloned(skb)) {
1280 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1281 GFP_ATOMIC))
1282 return NULL;
1283 }
1284
1285 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1286 BUG();
1287
1288 /* Optimization: no fragments, no reasons to preestimate
1289 * size of pulled pages. Superb.
1290 */
1291 if (!skb_has_frag_list(skb))
1292 goto pull_pages;
1293
1294 /* Estimate size of pulled pages. */
1295 eat = delta;
1296 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1297 if (skb_shinfo(skb)->frags[i].size >= eat)
1298 goto pull_pages;
1299 eat -= skb_shinfo(skb)->frags[i].size;
1300 }
1301
1302 /* If we need update frag list, we are in troubles.
1303 * Certainly, it possible to add an offset to skb data,
1304 * but taking into account that pulling is expected to
1305 * be very rare operation, it is worth to fight against
1306 * further bloating skb head and crucify ourselves here instead.
1307 * Pure masohism, indeed. 8)8)
1308 */
1309 if (eat) {
1310 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1311 struct sk_buff *clone = NULL;
1312 struct sk_buff *insp = NULL;
1313
1314 do {
1315 BUG_ON(!list);
1316
1317 if (list->len <= eat) {
1318 /* Eaten as whole. */
1319 eat -= list->len;
1320 list = list->next;
1321 insp = list;
1322 } else {
1323 /* Eaten partially. */
1324
1325 if (skb_shared(list)) {
1326 /* Sucks! We need to fork list. :-( */
1327 clone = skb_clone(list, GFP_ATOMIC);
1328 if (!clone)
1329 return NULL;
1330 insp = list->next;
1331 list = clone;
1332 } else {
1333 /* This may be pulled without
1334 * problems. */
1335 insp = list;
1336 }
1337 if (!pskb_pull(list, eat)) {
1338 kfree_skb(clone);
1339 return NULL;
1340 }
1341 break;
1342 }
1343 } while (eat);
1344
1345 /* Free pulled out fragments. */
1346 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1347 skb_shinfo(skb)->frag_list = list->next;
1348 kfree_skb(list);
1349 }
1350 /* And insert new clone at head. */
1351 if (clone) {
1352 clone->next = list;
1353 skb_shinfo(skb)->frag_list = clone;
1354 }
1355 }
1356 /* Success! Now we may commit changes to skb data. */
1357
1358pull_pages:
1359 eat = delta;
1360 k = 0;
1361 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1362 if (skb_shinfo(skb)->frags[i].size <= eat) {
1363 put_page(skb_shinfo(skb)->frags[i].page);
1364 eat -= skb_shinfo(skb)->frags[i].size;
1365 } else {
1366 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1367 if (eat) {
1368 skb_shinfo(skb)->frags[k].page_offset += eat;
1369 skb_shinfo(skb)->frags[k].size -= eat;
1370 eat = 0;
1371 }
1372 k++;
1373 }
1374 }
1375 skb_shinfo(skb)->nr_frags = k;
1376
1377 skb->tail += delta;
1378 skb->data_len -= delta;
1379
1380 return skb_tail_pointer(skb);
1381}
1382EXPORT_SYMBOL(__pskb_pull_tail);
1383
1384/**
1385 * skb_copy_bits - copy bits from skb to kernel buffer
1386 * @skb: source skb
1387 * @offset: offset in source
1388 * @to: destination buffer
1389 * @len: number of bytes to copy
1390 *
1391 * Copy the specified number of bytes from the source skb to the
1392 * destination buffer.
1393 *
1394 * CAUTION ! :
1395 * If its prototype is ever changed,
1396 * check arch/{*}/net/{*}.S files,
1397 * since it is called from BPF assembly code.
1398 */
1399int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1400{
1401 int start = skb_headlen(skb);
1402 struct sk_buff *frag_iter;
1403 int i, copy;
1404
1405 if (offset > (int)skb->len - len)
1406 goto fault;
1407
1408 /* Copy header. */
1409 if ((copy = start - offset) > 0) {
1410 if (copy > len)
1411 copy = len;
1412 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1413 if ((len -= copy) == 0)
1414 return 0;
1415 offset += copy;
1416 to += copy;
1417 }
1418
1419 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1420 int end;
1421
1422 WARN_ON(start > offset + len);
1423
1424 end = start + skb_shinfo(skb)->frags[i].size;
1425 if ((copy = end - offset) > 0) {
1426 u8 *vaddr;
1427
1428 if (copy > len)
1429 copy = len;
1430
1431 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
1432 memcpy(to,
1433 vaddr + skb_shinfo(skb)->frags[i].page_offset+
1434 offset - start, copy);
1435 kunmap_skb_frag(vaddr);
1436
1437 if ((len -= copy) == 0)
1438 return 0;
1439 offset += copy;
1440 to += copy;
1441 }
1442 start = end;
1443 }
1444
1445 skb_walk_frags(skb, frag_iter) {
1446 int end;
1447
1448 WARN_ON(start > offset + len);
1449
1450 end = start + frag_iter->len;
1451 if ((copy = end - offset) > 0) {
1452 if (copy > len)
1453 copy = len;
1454 if (skb_copy_bits(frag_iter, offset - start, to, copy))
1455 goto fault;
1456 if ((len -= copy) == 0)
1457 return 0;
1458 offset += copy;
1459 to += copy;
1460 }
1461 start = end;
1462 }
1463
1464 if (!len)
1465 return 0;
1466
1467fault:
1468 return -EFAULT;
1469}
1470EXPORT_SYMBOL(skb_copy_bits);
1471
1472/*
1473 * Callback from splice_to_pipe(), if we need to release some pages
1474 * at the end of the spd in case we error'ed out in filling the pipe.
1475 */
1476static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1477{
1478 put_page(spd->pages[i]);
1479}
1480
1481static inline struct page *linear_to_page(struct page *page, unsigned int *len,
1482 unsigned int *offset,
1483 struct sk_buff *skb, struct sock *sk)
1484{
1485 struct page *p = sk->sk_sndmsg_page;
1486 unsigned int off;
1487
1488 if (!p) {
1489new_page:
1490 p = sk->sk_sndmsg_page = alloc_pages(sk->sk_allocation, 0);
1491 if (!p)
1492 return NULL;
1493
1494 off = sk->sk_sndmsg_off = 0;
1495 /* hold one ref to this page until it's full */
1496 } else {
1497 unsigned int mlen;
1498
1499 off = sk->sk_sndmsg_off;
1500 mlen = PAGE_SIZE - off;
1501 if (mlen < 64 && mlen < *len) {
1502 put_page(p);
1503 goto new_page;
1504 }
1505
1506 *len = min_t(unsigned int, *len, mlen);
1507 }
1508
1509 memcpy(page_address(p) + off, page_address(page) + *offset, *len);
1510 sk->sk_sndmsg_off += *len;
1511 *offset = off;
1512 get_page(p);
1513
1514 return p;
1515}
1516
1517/*
1518 * Fill page/offset/length into spd, if it can hold more pages.
1519 */
1520static inline int spd_fill_page(struct splice_pipe_desc *spd,
1521 struct pipe_inode_info *pipe, struct page *page,
1522 unsigned int *len, unsigned int offset,
1523 struct sk_buff *skb, int linear,
1524 struct sock *sk)
1525{
1526 if (unlikely(spd->nr_pages == pipe->buffers))
1527 return 1;
1528
1529 if (linear) {
1530 page = linear_to_page(page, len, &offset, skb, sk);
1531 if (!page)
1532 return 1;
1533 } else
1534 get_page(page);
1535
1536 spd->pages[spd->nr_pages] = page;
1537 spd->partial[spd->nr_pages].len = *len;
1538 spd->partial[spd->nr_pages].offset = offset;
1539 spd->nr_pages++;
1540
1541 return 0;
1542}
1543
1544static inline void __segment_seek(struct page **page, unsigned int *poff,
1545 unsigned int *plen, unsigned int off)
1546{
1547 unsigned long n;
1548
1549 *poff += off;
1550 n = *poff / PAGE_SIZE;
1551 if (n)
1552 *page = nth_page(*page, n);
1553
1554 *poff = *poff % PAGE_SIZE;
1555 *plen -= off;
1556}
1557
1558static inline int __splice_segment(struct page *page, unsigned int poff,
1559 unsigned int plen, unsigned int *off,
1560 unsigned int *len, struct sk_buff *skb,
1561 struct splice_pipe_desc *spd, int linear,
1562 struct sock *sk,
1563 struct pipe_inode_info *pipe)
1564{
1565 if (!*len)
1566 return 1;
1567
1568 /* skip this segment if already processed */
1569 if (*off >= plen) {
1570 *off -= plen;
1571 return 0;
1572 }
1573
1574 /* ignore any bits we already processed */
1575 if (*off) {
1576 __segment_seek(&page, &poff, &plen, *off);
1577 *off = 0;
1578 }
1579
1580 do {
1581 unsigned int flen = min(*len, plen);
1582
1583 /* the linear region may spread across several pages */
1584 flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
1585
1586 if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
1587 return 1;
1588
1589 __segment_seek(&page, &poff, &plen, flen);
1590 *len -= flen;
1591
1592 } while (*len && plen);
1593
1594 return 0;
1595}
1596
1597/*
1598 * Map linear and fragment data from the skb to spd. It reports failure if the
1599 * pipe is full or if we already spliced the requested length.
1600 */
1601static int __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
1602 unsigned int *offset, unsigned int *len,
1603 struct splice_pipe_desc *spd, struct sock *sk)
1604{
1605 int seg;
1606
1607 /*
1608 * map the linear part
1609 */
1610 if (__splice_segment(virt_to_page(skb->data),
1611 (unsigned long) skb->data & (PAGE_SIZE - 1),
1612 skb_headlen(skb),
1613 offset, len, skb, spd, 1, sk, pipe))
1614 return 1;
1615
1616 /*
1617 * then map the fragments
1618 */
1619 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1620 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1621
1622 if (__splice_segment(f->page, f->page_offset, f->size,
1623 offset, len, skb, spd, 0, sk, pipe))
1624 return 1;
1625 }
1626
1627 return 0;
1628}
1629
1630/*
1631 * Map data from the skb to a pipe. Should handle both the linear part,
1632 * the fragments, and the frag list. It does NOT handle frag lists within
1633 * the frag list, if such a thing exists. We'd probably need to recurse to
1634 * handle that cleanly.
1635 */
1636int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
1637 struct pipe_inode_info *pipe, unsigned int tlen,
1638 unsigned int flags)
1639{
1640 struct partial_page partial[PIPE_DEF_BUFFERS];
1641 struct page *pages[PIPE_DEF_BUFFERS];
1642 struct splice_pipe_desc spd = {
1643 .pages = pages,
1644 .partial = partial,
1645 .flags = flags,
1646 .ops = &sock_pipe_buf_ops,
1647 .spd_release = sock_spd_release,
1648 };
1649 struct sk_buff *frag_iter;
1650 struct sock *sk = skb->sk;
1651 int ret = 0;
1652
1653 if (splice_grow_spd(pipe, &spd))
1654 return -ENOMEM;
1655
1656 /*
1657 * __skb_splice_bits() only fails if the output has no room left,
1658 * so no point in going over the frag_list for the error case.
1659 */
1660 if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
1661 goto done;
1662 else if (!tlen)
1663 goto done;
1664
1665 /*
1666 * now see if we have a frag_list to map
1667 */
1668 skb_walk_frags(skb, frag_iter) {
1669 if (!tlen)
1670 break;
1671 if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
1672 break;
1673 }
1674
1675done:
1676 if (spd.nr_pages) {
1677 /*
1678 * Drop the socket lock, otherwise we have reverse
1679 * locking dependencies between sk_lock and i_mutex
1680 * here as compared to sendfile(). We enter here
1681 * with the socket lock held, and splice_to_pipe() will
1682 * grab the pipe inode lock. For sendfile() emulation,
1683 * we call into ->sendpage() with the i_mutex lock held
1684 * and networking will grab the socket lock.
1685 */
1686 release_sock(sk);
1687 ret = splice_to_pipe(pipe, &spd);
1688 lock_sock(sk);
1689 }
1690
1691 splice_shrink_spd(pipe, &spd);
1692 return ret;
1693}
1694
1695/**
1696 * skb_store_bits - store bits from kernel buffer to skb
1697 * @skb: destination buffer
1698 * @offset: offset in destination
1699 * @from: source buffer
1700 * @len: number of bytes to copy
1701 *
1702 * Copy the specified number of bytes from the source buffer to the
1703 * destination skb. This function handles all the messy bits of
1704 * traversing fragment lists and such.
1705 */
1706
1707int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1708{
1709 int start = skb_headlen(skb);
1710 struct sk_buff *frag_iter;
1711 int i, copy;
1712
1713 if (offset > (int)skb->len - len)
1714 goto fault;
1715
1716 if ((copy = start - offset) > 0) {
1717 if (copy > len)
1718 copy = len;
1719 skb_copy_to_linear_data_offset(skb, offset, from, copy);
1720 if ((len -= copy) == 0)
1721 return 0;
1722 offset += copy;
1723 from += copy;
1724 }
1725
1726 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1727 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1728 int end;
1729
1730 WARN_ON(start > offset + len);
1731
1732 end = start + frag->size;
1733 if ((copy = end - offset) > 0) {
1734 u8 *vaddr;
1735
1736 if (copy > len)
1737 copy = len;
1738
1739 vaddr = kmap_skb_frag(frag);
1740 memcpy(vaddr + frag->page_offset + offset - start,
1741 from, copy);
1742 kunmap_skb_frag(vaddr);
1743
1744 if ((len -= copy) == 0)
1745 return 0;
1746 offset += copy;
1747 from += copy;
1748 }
1749 start = end;
1750 }
1751
1752 skb_walk_frags(skb, frag_iter) {
1753 int end;
1754
1755 WARN_ON(start > offset + len);
1756
1757 end = start + frag_iter->len;
1758 if ((copy = end - offset) > 0) {
1759 if (copy > len)
1760 copy = len;
1761 if (skb_store_bits(frag_iter, offset - start,
1762 from, copy))
1763 goto fault;
1764 if ((len -= copy) == 0)
1765 return 0;
1766 offset += copy;
1767 from += copy;
1768 }
1769 start = end;
1770 }
1771 if (!len)
1772 return 0;
1773
1774fault:
1775 return -EFAULT;
1776}
1777EXPORT_SYMBOL(skb_store_bits);
1778
1779/* Checksum skb data. */
1780
1781__wsum skb_checksum(const struct sk_buff *skb, int offset,
1782 int len, __wsum csum)
1783{
1784 int start = skb_headlen(skb);
1785 int i, copy = start - offset;
1786 struct sk_buff *frag_iter;
1787 int pos = 0;
1788
1789 /* Checksum header. */
1790 if (copy > 0) {
1791 if (copy > len)
1792 copy = len;
1793 csum = csum_partial(skb->data + offset, copy, csum);
1794 if ((len -= copy) == 0)
1795 return csum;
1796 offset += copy;
1797 pos = copy;
1798 }
1799
1800 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1801 int end;
1802
1803 WARN_ON(start > offset + len);
1804
1805 end = start + skb_shinfo(skb)->frags[i].size;
1806 if ((copy = end - offset) > 0) {
1807 __wsum csum2;
1808 u8 *vaddr;
1809 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1810
1811 if (copy > len)
1812 copy = len;
1813 vaddr = kmap_skb_frag(frag);
1814 csum2 = csum_partial(vaddr + frag->page_offset +
1815 offset - start, copy, 0);
1816 kunmap_skb_frag(vaddr);
1817 csum = csum_block_add(csum, csum2, pos);
1818 if (!(len -= copy))
1819 return csum;
1820 offset += copy;
1821 pos += copy;
1822 }
1823 start = end;
1824 }
1825
1826 skb_walk_frags(skb, frag_iter) {
1827 int end;
1828
1829 WARN_ON(start > offset + len);
1830
1831 end = start + frag_iter->len;
1832 if ((copy = end - offset) > 0) {
1833 __wsum csum2;
1834 if (copy > len)
1835 copy = len;
1836 csum2 = skb_checksum(frag_iter, offset - start,
1837 copy, 0);
1838 csum = csum_block_add(csum, csum2, pos);
1839 if ((len -= copy) == 0)
1840 return csum;
1841 offset += copy;
1842 pos += copy;
1843 }
1844 start = end;
1845 }
1846 BUG_ON(len);
1847
1848 return csum;
1849}
1850EXPORT_SYMBOL(skb_checksum);
1851
1852/* Both of above in one bottle. */
1853
1854__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
1855 u8 *to, int len, __wsum csum)
1856{
1857 int start = skb_headlen(skb);
1858 int i, copy = start - offset;
1859 struct sk_buff *frag_iter;
1860 int pos = 0;
1861
1862 /* Copy header. */
1863 if (copy > 0) {
1864 if (copy > len)
1865 copy = len;
1866 csum = csum_partial_copy_nocheck(skb->data + offset, to,
1867 copy, csum);
1868 if ((len -= copy) == 0)
1869 return csum;
1870 offset += copy;
1871 to += copy;
1872 pos = copy;
1873 }
1874
1875 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1876 int end;
1877
1878 WARN_ON(start > offset + len);
1879
1880 end = start + skb_shinfo(skb)->frags[i].size;
1881 if ((copy = end - offset) > 0) {
1882 __wsum csum2;
1883 u8 *vaddr;
1884 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1885
1886 if (copy > len)
1887 copy = len;
1888 vaddr = kmap_skb_frag(frag);
1889 csum2 = csum_partial_copy_nocheck(vaddr +
1890 frag->page_offset +
1891 offset - start, to,
1892 copy, 0);
1893 kunmap_skb_frag(vaddr);
1894 csum = csum_block_add(csum, csum2, pos);
1895 if (!(len -= copy))
1896 return csum;
1897 offset += copy;
1898 to += copy;
1899 pos += copy;
1900 }
1901 start = end;
1902 }
1903
1904 skb_walk_frags(skb, frag_iter) {
1905 __wsum csum2;
1906 int end;
1907
1908 WARN_ON(start > offset + len);
1909
1910 end = start + frag_iter->len;
1911 if ((copy = end - offset) > 0) {
1912 if (copy > len)
1913 copy = len;
1914 csum2 = skb_copy_and_csum_bits(frag_iter,
1915 offset - start,
1916 to, copy, 0);
1917 csum = csum_block_add(csum, csum2, pos);
1918 if ((len -= copy) == 0)
1919 return csum;
1920 offset += copy;
1921 to += copy;
1922 pos += copy;
1923 }
1924 start = end;
1925 }
1926 BUG_ON(len);
1927 return csum;
1928}
1929EXPORT_SYMBOL(skb_copy_and_csum_bits);
1930
1931void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
1932{
1933 __wsum csum;
1934 long csstart;
1935
1936 if (skb->ip_summed == CHECKSUM_PARTIAL)
1937 csstart = skb_checksum_start_offset(skb);
1938 else
1939 csstart = skb_headlen(skb);
1940
1941 BUG_ON(csstart > skb_headlen(skb));
1942
1943 skb_copy_from_linear_data(skb, to, csstart);
1944
1945 csum = 0;
1946 if (csstart != skb->len)
1947 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
1948 skb->len - csstart, 0);
1949
1950 if (skb->ip_summed == CHECKSUM_PARTIAL) {
1951 long csstuff = csstart + skb->csum_offset;
1952
1953 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
1954 }
1955}
1956EXPORT_SYMBOL(skb_copy_and_csum_dev);
1957
1958/**
1959 * skb_dequeue - remove from the head of the queue
1960 * @list: list to dequeue from
1961 *
1962 * Remove the head of the list. The list lock is taken so the function
1963 * may be used safely with other locking list functions. The head item is
1964 * returned or %NULL if the list is empty.
1965 */
1966
1967struct sk_buff *skb_dequeue(struct sk_buff_head *list)
1968{
1969 unsigned long flags;
1970 struct sk_buff *result;
1971
1972 spin_lock_irqsave(&list->lock, flags);
1973 result = __skb_dequeue(list);
1974 spin_unlock_irqrestore(&list->lock, flags);
1975 return result;
1976}
1977EXPORT_SYMBOL(skb_dequeue);
1978
1979/**
1980 * skb_dequeue_tail - remove from the tail of the queue
1981 * @list: list to dequeue from
1982 *
1983 * Remove the tail of the list. The list lock is taken so the function
1984 * may be used safely with other locking list functions. The tail item is
1985 * returned or %NULL if the list is empty.
1986 */
1987struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
1988{
1989 unsigned long flags;
1990 struct sk_buff *result;
1991
1992 spin_lock_irqsave(&list->lock, flags);
1993 result = __skb_dequeue_tail(list);
1994 spin_unlock_irqrestore(&list->lock, flags);
1995 return result;
1996}
1997EXPORT_SYMBOL(skb_dequeue_tail);
1998
1999/**
2000 * skb_queue_purge - empty a list
2001 * @list: list to empty
2002 *
2003 * Delete all buffers on an &sk_buff list. Each buffer is removed from
2004 * the list and one reference dropped. This function takes the list
2005 * lock and is atomic with respect to other list locking functions.
2006 */
2007void skb_queue_purge(struct sk_buff_head *list)
2008{
2009 struct sk_buff *skb;
2010 while ((skb = skb_dequeue(list)) != NULL)
2011 kfree_skb(skb);
2012}
2013EXPORT_SYMBOL(skb_queue_purge);
2014
2015/**
2016 * skb_queue_head - queue a buffer at the list head
2017 * @list: list to use
2018 * @newsk: buffer to queue
2019 *
2020 * Queue a buffer at the start of the list. This function takes the
2021 * list lock and can be used safely with other locking &sk_buff functions
2022 * safely.
2023 *
2024 * A buffer cannot be placed on two lists at the same time.
2025 */
2026void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
2027{
2028 unsigned long flags;
2029
2030 spin_lock_irqsave(&list->lock, flags);
2031 __skb_queue_head(list, newsk);
2032 spin_unlock_irqrestore(&list->lock, flags);
2033}
2034EXPORT_SYMBOL(skb_queue_head);
2035
2036/**
2037 * skb_queue_tail - queue a buffer at the list tail
2038 * @list: list to use
2039 * @newsk: buffer to queue
2040 *
2041 * Queue a buffer at the tail of the list. This function takes the
2042 * list lock and can be used safely with other locking &sk_buff functions
2043 * safely.
2044 *
2045 * A buffer cannot be placed on two lists at the same time.
2046 */
2047void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
2048{
2049 unsigned long flags;
2050
2051 spin_lock_irqsave(&list->lock, flags);
2052 __skb_queue_tail(list, newsk);
2053 spin_unlock_irqrestore(&list->lock, flags);
2054}
2055EXPORT_SYMBOL(skb_queue_tail);
2056
2057/**
2058 * skb_unlink - remove a buffer from a list
2059 * @skb: buffer to remove
2060 * @list: list to use
2061 *
2062 * Remove a packet from a list. The list locks are taken and this
2063 * function is atomic with respect to other list locked calls
2064 *
2065 * You must know what list the SKB is on.
2066 */
2067void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
2068{
2069 unsigned long flags;
2070
2071 spin_lock_irqsave(&list->lock, flags);
2072 __skb_unlink(skb, list);
2073 spin_unlock_irqrestore(&list->lock, flags);
2074}
2075EXPORT_SYMBOL(skb_unlink);
2076
2077/**
2078 * skb_append - append a buffer
2079 * @old: buffer to insert after
2080 * @newsk: buffer to insert
2081 * @list: list to use
2082 *
2083 * Place a packet after a given packet in a list. The list locks are taken
2084 * and this function is atomic with respect to other list locked calls.
2085 * A buffer cannot be placed on two lists at the same time.
2086 */
2087void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2088{
2089 unsigned long flags;
2090
2091 spin_lock_irqsave(&list->lock, flags);
2092 __skb_queue_after(list, old, newsk);
2093 spin_unlock_irqrestore(&list->lock, flags);
2094}
2095EXPORT_SYMBOL(skb_append);
2096
2097/**
2098 * skb_insert - insert a buffer
2099 * @old: buffer to insert before
2100 * @newsk: buffer to insert
2101 * @list: list to use
2102 *
2103 * Place a packet before a given packet in a list. The list locks are
2104 * taken and this function is atomic with respect to other list locked
2105 * calls.
2106 *
2107 * A buffer cannot be placed on two lists at the same time.
2108 */
2109void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2110{
2111 unsigned long flags;
2112
2113 spin_lock_irqsave(&list->lock, flags);
2114 __skb_insert(newsk, old->prev, old, list);
2115 spin_unlock_irqrestore(&list->lock, flags);
2116}
2117EXPORT_SYMBOL(skb_insert);
2118
2119static inline void skb_split_inside_header(struct sk_buff *skb,
2120 struct sk_buff* skb1,
2121 const u32 len, const int pos)
2122{
2123 int i;
2124
2125 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2126 pos - len);
2127 /* And move data appendix as is. */
2128 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2129 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2130
2131 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2132 skb_shinfo(skb)->nr_frags = 0;
2133 skb1->data_len = skb->data_len;
2134 skb1->len += skb1->data_len;
2135 skb->data_len = 0;
2136 skb->len = len;
2137 skb_set_tail_pointer(skb, len);
2138}
2139
2140static inline void skb_split_no_header(struct sk_buff *skb,
2141 struct sk_buff* skb1,
2142 const u32 len, int pos)
2143{
2144 int i, k = 0;
2145 const int nfrags = skb_shinfo(skb)->nr_frags;
2146
2147 skb_shinfo(skb)->nr_frags = 0;
2148 skb1->len = skb1->data_len = skb->len - len;
2149 skb->len = len;
2150 skb->data_len = len - pos;
2151
2152 for (i = 0; i < nfrags; i++) {
2153 int size = skb_shinfo(skb)->frags[i].size;
2154
2155 if (pos + size > len) {
2156 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2157
2158 if (pos < len) {
2159 /* Split frag.
2160 * We have two variants in this case:
2161 * 1. Move all the frag to the second
2162 * part, if it is possible. F.e.
2163 * this approach is mandatory for TUX,
2164 * where splitting is expensive.
2165 * 2. Split is accurately. We make this.
2166 */
2167 get_page(skb_shinfo(skb)->frags[i].page);
2168 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2169 skb_shinfo(skb1)->frags[0].size -= len - pos;
2170 skb_shinfo(skb)->frags[i].size = len - pos;
2171 skb_shinfo(skb)->nr_frags++;
2172 }
2173 k++;
2174 } else
2175 skb_shinfo(skb)->nr_frags++;
2176 pos += size;
2177 }
2178 skb_shinfo(skb1)->nr_frags = k;
2179}
2180
2181/**
2182 * skb_split - Split fragmented skb to two parts at length len.
2183 * @skb: the buffer to split
2184 * @skb1: the buffer to receive the second part
2185 * @len: new length for skb
2186 */
2187void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2188{
2189 int pos = skb_headlen(skb);
2190
2191 if (len < pos) /* Split line is inside header. */
2192 skb_split_inside_header(skb, skb1, len, pos);
2193 else /* Second chunk has no header, nothing to copy. */
2194 skb_split_no_header(skb, skb1, len, pos);
2195}
2196EXPORT_SYMBOL(skb_split);
2197
2198/* Shifting from/to a cloned skb is a no-go.
2199 *
2200 * Caller cannot keep skb_shinfo related pointers past calling here!
2201 */
2202static int skb_prepare_for_shift(struct sk_buff *skb)
2203{
2204 return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2205}
2206
2207/**
2208 * skb_shift - Shifts paged data partially from skb to another
2209 * @tgt: buffer into which tail data gets added
2210 * @skb: buffer from which the paged data comes from
2211 * @shiftlen: shift up to this many bytes
2212 *
2213 * Attempts to shift up to shiftlen worth of bytes, which may be less than
2214 * the length of the skb, from tgt to skb. Returns number bytes shifted.
2215 * It's up to caller to free skb if everything was shifted.
2216 *
2217 * If @tgt runs out of frags, the whole operation is aborted.
2218 *
2219 * Skb cannot include anything else but paged data while tgt is allowed
2220 * to have non-paged data as well.
2221 *
2222 * TODO: full sized shift could be optimized but that would need
2223 * specialized skb free'er to handle frags without up-to-date nr_frags.
2224 */
2225int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2226{
2227 int from, to, merge, todo;
2228 struct skb_frag_struct *fragfrom, *fragto;
2229
2230 BUG_ON(shiftlen > skb->len);
2231 BUG_ON(skb_headlen(skb)); /* Would corrupt stream */
2232
2233 todo = shiftlen;
2234 from = 0;
2235 to = skb_shinfo(tgt)->nr_frags;
2236 fragfrom = &skb_shinfo(skb)->frags[from];
2237
2238 /* Actual merge is delayed until the point when we know we can
2239 * commit all, so that we don't have to undo partial changes
2240 */
2241 if (!to ||
2242 !skb_can_coalesce(tgt, to, fragfrom->page, fragfrom->page_offset)) {
2243 merge = -1;
2244 } else {
2245 merge = to - 1;
2246
2247 todo -= fragfrom->size;
2248 if (todo < 0) {
2249 if (skb_prepare_for_shift(skb) ||
2250 skb_prepare_for_shift(tgt))
2251 return 0;
2252
2253 /* All previous frag pointers might be stale! */
2254 fragfrom = &skb_shinfo(skb)->frags[from];
2255 fragto = &skb_shinfo(tgt)->frags[merge];
2256
2257 fragto->size += shiftlen;
2258 fragfrom->size -= shiftlen;
2259 fragfrom->page_offset += shiftlen;
2260
2261 goto onlymerged;
2262 }
2263
2264 from++;
2265 }
2266
2267 /* Skip full, not-fitting skb to avoid expensive operations */
2268 if ((shiftlen == skb->len) &&
2269 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2270 return 0;
2271
2272 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2273 return 0;
2274
2275 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2276 if (to == MAX_SKB_FRAGS)
2277 return 0;
2278
2279 fragfrom = &skb_shinfo(skb)->frags[from];
2280 fragto = &skb_shinfo(tgt)->frags[to];
2281
2282 if (todo >= fragfrom->size) {
2283 *fragto = *fragfrom;
2284 todo -= fragfrom->size;
2285 from++;
2286 to++;
2287
2288 } else {
2289 get_page(fragfrom->page);
2290 fragto->page = fragfrom->page;
2291 fragto->page_offset = fragfrom->page_offset;
2292 fragto->size = todo;
2293
2294 fragfrom->page_offset += todo;
2295 fragfrom->size -= todo;
2296 todo = 0;
2297
2298 to++;
2299 break;
2300 }
2301 }
2302
2303 /* Ready to "commit" this state change to tgt */
2304 skb_shinfo(tgt)->nr_frags = to;
2305
2306 if (merge >= 0) {
2307 fragfrom = &skb_shinfo(skb)->frags[0];
2308 fragto = &skb_shinfo(tgt)->frags[merge];
2309
2310 fragto->size += fragfrom->size;
2311 put_page(fragfrom->page);
2312 }
2313
2314 /* Reposition in the original skb */
2315 to = 0;
2316 while (from < skb_shinfo(skb)->nr_frags)
2317 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2318 skb_shinfo(skb)->nr_frags = to;
2319
2320 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2321
2322onlymerged:
2323 /* Most likely the tgt won't ever need its checksum anymore, skb on
2324 * the other hand might need it if it needs to be resent
2325 */
2326 tgt->ip_summed = CHECKSUM_PARTIAL;
2327 skb->ip_summed = CHECKSUM_PARTIAL;
2328
2329 /* Yak, is it really working this way? Some helper please? */
2330 skb->len -= shiftlen;
2331 skb->data_len -= shiftlen;
2332 skb->truesize -= shiftlen;
2333 tgt->len += shiftlen;
2334 tgt->data_len += shiftlen;
2335 tgt->truesize += shiftlen;
2336
2337 return shiftlen;
2338}
2339
2340/**
2341 * skb_prepare_seq_read - Prepare a sequential read of skb data
2342 * @skb: the buffer to read
2343 * @from: lower offset of data to be read
2344 * @to: upper offset of data to be read
2345 * @st: state variable
2346 *
2347 * Initializes the specified state variable. Must be called before
2348 * invoking skb_seq_read() for the first time.
2349 */
2350void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2351 unsigned int to, struct skb_seq_state *st)
2352{
2353 st->lower_offset = from;
2354 st->upper_offset = to;
2355 st->root_skb = st->cur_skb = skb;
2356 st->frag_idx = st->stepped_offset = 0;
2357 st->frag_data = NULL;
2358}
2359EXPORT_SYMBOL(skb_prepare_seq_read);
2360
2361/**
2362 * skb_seq_read - Sequentially read skb data
2363 * @consumed: number of bytes consumed by the caller so far
2364 * @data: destination pointer for data to be returned
2365 * @st: state variable
2366 *
2367 * Reads a block of skb data at &consumed relative to the
2368 * lower offset specified to skb_prepare_seq_read(). Assigns
2369 * the head of the data block to &data and returns the length
2370 * of the block or 0 if the end of the skb data or the upper
2371 * offset has been reached.
2372 *
2373 * The caller is not required to consume all of the data
2374 * returned, i.e. &consumed is typically set to the number
2375 * of bytes already consumed and the next call to
2376 * skb_seq_read() will return the remaining part of the block.
2377 *
2378 * Note 1: The size of each block of data returned can be arbitrary,
2379 * this limitation is the cost for zerocopy seqeuental
2380 * reads of potentially non linear data.
2381 *
2382 * Note 2: Fragment lists within fragments are not implemented
2383 * at the moment, state->root_skb could be replaced with
2384 * a stack for this purpose.
2385 */
2386unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2387 struct skb_seq_state *st)
2388{
2389 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2390 skb_frag_t *frag;
2391
2392 if (unlikely(abs_offset >= st->upper_offset))
2393 return 0;
2394
2395next_skb:
2396 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2397
2398 if (abs_offset < block_limit && !st->frag_data) {
2399 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2400 return block_limit - abs_offset;
2401 }
2402
2403 if (st->frag_idx == 0 && !st->frag_data)
2404 st->stepped_offset += skb_headlen(st->cur_skb);
2405
2406 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2407 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2408 block_limit = frag->size + st->stepped_offset;
2409
2410 if (abs_offset < block_limit) {
2411 if (!st->frag_data)
2412 st->frag_data = kmap_skb_frag(frag);
2413
2414 *data = (u8 *) st->frag_data + frag->page_offset +
2415 (abs_offset - st->stepped_offset);
2416
2417 return block_limit - abs_offset;
2418 }
2419
2420 if (st->frag_data) {
2421 kunmap_skb_frag(st->frag_data);
2422 st->frag_data = NULL;
2423 }
2424
2425 st->frag_idx++;
2426 st->stepped_offset += frag->size;
2427 }
2428
2429 if (st->frag_data) {
2430 kunmap_skb_frag(st->frag_data);
2431 st->frag_data = NULL;
2432 }
2433
2434 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
2435 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2436 st->frag_idx = 0;
2437 goto next_skb;
2438 } else if (st->cur_skb->next) {
2439 st->cur_skb = st->cur_skb->next;
2440 st->frag_idx = 0;
2441 goto next_skb;
2442 }
2443
2444 return 0;
2445}
2446EXPORT_SYMBOL(skb_seq_read);
2447
2448/**
2449 * skb_abort_seq_read - Abort a sequential read of skb data
2450 * @st: state variable
2451 *
2452 * Must be called if skb_seq_read() was not called until it
2453 * returned 0.
2454 */
2455void skb_abort_seq_read(struct skb_seq_state *st)
2456{
2457 if (st->frag_data)
2458 kunmap_skb_frag(st->frag_data);
2459}
2460EXPORT_SYMBOL(skb_abort_seq_read);
2461
2462#define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
2463
2464static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2465 struct ts_config *conf,
2466 struct ts_state *state)
2467{
2468 return skb_seq_read(offset, text, TS_SKB_CB(state));
2469}
2470
2471static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2472{
2473 skb_abort_seq_read(TS_SKB_CB(state));
2474}
2475
2476/**
2477 * skb_find_text - Find a text pattern in skb data
2478 * @skb: the buffer to look in
2479 * @from: search offset
2480 * @to: search limit
2481 * @config: textsearch configuration
2482 * @state: uninitialized textsearch state variable
2483 *
2484 * Finds a pattern in the skb data according to the specified
2485 * textsearch configuration. Use textsearch_next() to retrieve
2486 * subsequent occurrences of the pattern. Returns the offset
2487 * to the first occurrence or UINT_MAX if no match was found.
2488 */
2489unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2490 unsigned int to, struct ts_config *config,
2491 struct ts_state *state)
2492{
2493 unsigned int ret;
2494
2495 config->get_next_block = skb_ts_get_next_block;
2496 config->finish = skb_ts_finish;
2497
2498 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
2499
2500 ret = textsearch_find(config, state);
2501 return (ret <= to - from ? ret : UINT_MAX);
2502}
2503EXPORT_SYMBOL(skb_find_text);
2504
2505/**
2506 * skb_append_datato_frags: - append the user data to a skb
2507 * @sk: sock structure
2508 * @skb: skb structure to be appened with user data.
2509 * @getfrag: call back function to be used for getting the user data
2510 * @from: pointer to user message iov
2511 * @length: length of the iov message
2512 *
2513 * Description: This procedure append the user data in the fragment part
2514 * of the skb if any page alloc fails user this procedure returns -ENOMEM
2515 */
2516int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2517 int (*getfrag)(void *from, char *to, int offset,
2518 int len, int odd, struct sk_buff *skb),
2519 void *from, int length)
2520{
2521 int frg_cnt = 0;
2522 skb_frag_t *frag = NULL;
2523 struct page *page = NULL;
2524 int copy, left;
2525 int offset = 0;
2526 int ret;
2527
2528 do {
2529 /* Return error if we don't have space for new frag */
2530 frg_cnt = skb_shinfo(skb)->nr_frags;
2531 if (frg_cnt >= MAX_SKB_FRAGS)
2532 return -EFAULT;
2533
2534 /* allocate a new page for next frag */
2535 page = alloc_pages(sk->sk_allocation, 0);
2536
2537 /* If alloc_page fails just return failure and caller will
2538 * free previous allocated pages by doing kfree_skb()
2539 */
2540 if (page == NULL)
2541 return -ENOMEM;
2542
2543 /* initialize the next frag */
2544 skb_fill_page_desc(skb, frg_cnt, page, 0, 0);
2545 skb->truesize += PAGE_SIZE;
2546 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
2547
2548 /* get the new initialized frag */
2549 frg_cnt = skb_shinfo(skb)->nr_frags;
2550 frag = &skb_shinfo(skb)->frags[frg_cnt - 1];
2551
2552 /* copy the user data to page */
2553 left = PAGE_SIZE - frag->page_offset;
2554 copy = (length > left)? left : length;
2555
2556 ret = getfrag(from, (page_address(frag->page) +
2557 frag->page_offset + frag->size),
2558 offset, copy, 0, skb);
2559 if (ret < 0)
2560 return -EFAULT;
2561
2562 /* copy was successful so update the size parameters */
2563 frag->size += copy;
2564 skb->len += copy;
2565 skb->data_len += copy;
2566 offset += copy;
2567 length -= copy;
2568
2569 } while (length > 0);
2570
2571 return 0;
2572}
2573EXPORT_SYMBOL(skb_append_datato_frags);
2574
2575/**
2576 * skb_pull_rcsum - pull skb and update receive checksum
2577 * @skb: buffer to update
2578 * @len: length of data pulled
2579 *
2580 * This function performs an skb_pull on the packet and updates
2581 * the CHECKSUM_COMPLETE checksum. It should be used on
2582 * receive path processing instead of skb_pull unless you know
2583 * that the checksum difference is zero (e.g., a valid IP header)
2584 * or you are setting ip_summed to CHECKSUM_NONE.
2585 */
2586unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
2587{
2588 BUG_ON(len > skb->len);
2589 skb->len -= len;
2590 BUG_ON(skb->len < skb->data_len);
2591 skb_postpull_rcsum(skb, skb->data, len);
2592 return skb->data += len;
2593}
2594EXPORT_SYMBOL_GPL(skb_pull_rcsum);
2595
2596/**
2597 * skb_segment - Perform protocol segmentation on skb.
2598 * @skb: buffer to segment
2599 * @features: features for the output path (see dev->features)
2600 *
2601 * This function performs segmentation on the given skb. It returns
2602 * a pointer to the first in a list of new skbs for the segments.
2603 * In case of error it returns ERR_PTR(err).
2604 */
2605struct sk_buff *skb_segment(struct sk_buff *skb, u32 features)
2606{
2607 struct sk_buff *segs = NULL;
2608 struct sk_buff *tail = NULL;
2609 struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
2610 unsigned int mss = skb_shinfo(skb)->gso_size;
2611 unsigned int doffset = skb->data - skb_mac_header(skb);
2612 unsigned int offset = doffset;
2613 unsigned int headroom;
2614 unsigned int len;
2615 int sg = !!(features & NETIF_F_SG);
2616 int nfrags = skb_shinfo(skb)->nr_frags;
2617 int err = -ENOMEM;
2618 int i = 0;
2619 int pos;
2620
2621 __skb_push(skb, doffset);
2622 headroom = skb_headroom(skb);
2623 pos = skb_headlen(skb);
2624
2625 do {
2626 struct sk_buff *nskb;
2627 skb_frag_t *frag;
2628 int hsize;
2629 int size;
2630
2631 len = skb->len - offset;
2632 if (len > mss)
2633 len = mss;
2634
2635 hsize = skb_headlen(skb) - offset;
2636 if (hsize < 0)
2637 hsize = 0;
2638 if (hsize > len || !sg)
2639 hsize = len;
2640
2641 if (!hsize && i >= nfrags) {
2642 BUG_ON(fskb->len != len);
2643
2644 pos += len;
2645 nskb = skb_clone(fskb, GFP_ATOMIC);
2646 fskb = fskb->next;
2647
2648 if (unlikely(!nskb))
2649 goto err;
2650
2651 hsize = skb_end_pointer(nskb) - nskb->head;
2652 if (skb_cow_head(nskb, doffset + headroom)) {
2653 kfree_skb(nskb);
2654 goto err;
2655 }
2656
2657 nskb->truesize += skb_end_pointer(nskb) - nskb->head -
2658 hsize;
2659 skb_release_head_state(nskb);
2660 __skb_push(nskb, doffset);
2661 } else {
2662 nskb = alloc_skb(hsize + doffset + headroom,
2663 GFP_ATOMIC);
2664
2665 if (unlikely(!nskb))
2666 goto err;
2667
2668 skb_reserve(nskb, headroom);
2669 __skb_put(nskb, doffset);
2670 }
2671
2672 if (segs)
2673 tail->next = nskb;
2674 else
2675 segs = nskb;
2676 tail = nskb;
2677
2678 __copy_skb_header(nskb, skb);
2679 nskb->mac_len = skb->mac_len;
2680
2681 /* nskb and skb might have different headroom */
2682 if (nskb->ip_summed == CHECKSUM_PARTIAL)
2683 nskb->csum_start += skb_headroom(nskb) - headroom;
2684
2685 skb_reset_mac_header(nskb);
2686 skb_set_network_header(nskb, skb->mac_len);
2687 nskb->transport_header = (nskb->network_header +
2688 skb_network_header_len(skb));
2689 skb_copy_from_linear_data(skb, nskb->data, doffset);
2690
2691 if (fskb != skb_shinfo(skb)->frag_list)
2692 continue;
2693
2694 if (!sg) {
2695 nskb->ip_summed = CHECKSUM_NONE;
2696 nskb->csum = skb_copy_and_csum_bits(skb, offset,
2697 skb_put(nskb, len),
2698 len, 0);
2699 continue;
2700 }
2701
2702 frag = skb_shinfo(nskb)->frags;
2703
2704 skb_copy_from_linear_data_offset(skb, offset,
2705 skb_put(nskb, hsize), hsize);
2706
2707 while (pos < offset + len && i < nfrags) {
2708 *frag = skb_shinfo(skb)->frags[i];
2709 get_page(frag->page);
2710 size = frag->size;
2711
2712 if (pos < offset) {
2713 frag->page_offset += offset - pos;
2714 frag->size -= offset - pos;
2715 }
2716
2717 skb_shinfo(nskb)->nr_frags++;
2718
2719 if (pos + size <= offset + len) {
2720 i++;
2721 pos += size;
2722 } else {
2723 frag->size -= pos + size - (offset + len);
2724 goto skip_fraglist;
2725 }
2726
2727 frag++;
2728 }
2729
2730 if (pos < offset + len) {
2731 struct sk_buff *fskb2 = fskb;
2732
2733 BUG_ON(pos + fskb->len != offset + len);
2734
2735 pos += fskb->len;
2736 fskb = fskb->next;
2737
2738 if (fskb2->next) {
2739 fskb2 = skb_clone(fskb2, GFP_ATOMIC);
2740 if (!fskb2)
2741 goto err;
2742 } else
2743 skb_get(fskb2);
2744
2745 SKB_FRAG_ASSERT(nskb);
2746 skb_shinfo(nskb)->frag_list = fskb2;
2747 }
2748
2749skip_fraglist:
2750 nskb->data_len = len - hsize;
2751 nskb->len += nskb->data_len;
2752 nskb->truesize += nskb->data_len;
2753 } while ((offset += len) < skb->len);
2754
2755 return segs;
2756
2757err:
2758 while ((skb = segs)) {
2759 segs = skb->next;
2760 kfree_skb(skb);
2761 }
2762 return ERR_PTR(err);
2763}
2764EXPORT_SYMBOL_GPL(skb_segment);
2765
2766int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2767{
2768 struct sk_buff *p = *head;
2769 struct sk_buff *nskb;
2770 struct skb_shared_info *skbinfo = skb_shinfo(skb);
2771 struct skb_shared_info *pinfo = skb_shinfo(p);
2772 unsigned int headroom;
2773 unsigned int len = skb_gro_len(skb);
2774 unsigned int offset = skb_gro_offset(skb);
2775 unsigned int headlen = skb_headlen(skb);
2776
2777 if (p->len + len >= 65536)
2778 return -E2BIG;
2779
2780 if (pinfo->frag_list)
2781 goto merge;
2782 else if (headlen <= offset) {
2783 skb_frag_t *frag;
2784 skb_frag_t *frag2;
2785 int i = skbinfo->nr_frags;
2786 int nr_frags = pinfo->nr_frags + i;
2787
2788 offset -= headlen;
2789
2790 if (nr_frags > MAX_SKB_FRAGS)
2791 return -E2BIG;
2792
2793 pinfo->nr_frags = nr_frags;
2794 skbinfo->nr_frags = 0;
2795
2796 frag = pinfo->frags + nr_frags;
2797 frag2 = skbinfo->frags + i;
2798 do {
2799 *--frag = *--frag2;
2800 } while (--i);
2801
2802 frag->page_offset += offset;
2803 frag->size -= offset;
2804
2805 skb->truesize -= skb->data_len;
2806 skb->len -= skb->data_len;
2807 skb->data_len = 0;
2808
2809 NAPI_GRO_CB(skb)->free = 1;
2810 goto done;
2811 } else if (skb_gro_len(p) != pinfo->gso_size)
2812 return -E2BIG;
2813
2814 headroom = skb_headroom(p);
2815 nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
2816 if (unlikely(!nskb))
2817 return -ENOMEM;
2818
2819 __copy_skb_header(nskb, p);
2820 nskb->mac_len = p->mac_len;
2821
2822 skb_reserve(nskb, headroom);
2823 __skb_put(nskb, skb_gro_offset(p));
2824
2825 skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
2826 skb_set_network_header(nskb, skb_network_offset(p));
2827 skb_set_transport_header(nskb, skb_transport_offset(p));
2828
2829 __skb_pull(p, skb_gro_offset(p));
2830 memcpy(skb_mac_header(nskb), skb_mac_header(p),
2831 p->data - skb_mac_header(p));
2832
2833 *NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p);
2834 skb_shinfo(nskb)->frag_list = p;
2835 skb_shinfo(nskb)->gso_size = pinfo->gso_size;
2836 pinfo->gso_size = 0;
2837 skb_header_release(p);
2838 nskb->prev = p;
2839
2840 nskb->data_len += p->len;
2841 nskb->truesize += p->len;
2842 nskb->len += p->len;
2843
2844 *head = nskb;
2845 nskb->next = p->next;
2846 p->next = NULL;
2847
2848 p = nskb;
2849
2850merge:
2851 if (offset > headlen) {
2852 unsigned int eat = offset - headlen;
2853
2854 skbinfo->frags[0].page_offset += eat;
2855 skbinfo->frags[0].size -= eat;
2856 skb->data_len -= eat;
2857 skb->len -= eat;
2858 offset = headlen;
2859 }
2860
2861 __skb_pull(skb, offset);
2862
2863 p->prev->next = skb;
2864 p->prev = skb;
2865 skb_header_release(skb);
2866
2867done:
2868 NAPI_GRO_CB(p)->count++;
2869 p->data_len += len;
2870 p->truesize += len;
2871 p->len += len;
2872
2873 NAPI_GRO_CB(skb)->same_flow = 1;
2874 return 0;
2875}
2876EXPORT_SYMBOL_GPL(skb_gro_receive);
2877
2878void __init skb_init(void)
2879{
2880 skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
2881 sizeof(struct sk_buff),
2882 0,
2883 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2884 NULL);
2885 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
2886 (2*sizeof(struct sk_buff)) +
2887 sizeof(atomic_t),
2888 0,
2889 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
2890 NULL);
2891}
2892
2893/**
2894 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
2895 * @skb: Socket buffer containing the buffers to be mapped
2896 * @sg: The scatter-gather list to map into
2897 * @offset: The offset into the buffer's contents to start mapping
2898 * @len: Length of buffer space to be mapped
2899 *
2900 * Fill the specified scatter-gather list with mappings/pointers into a
2901 * region of the buffer space attached to a socket buffer.
2902 */
2903static int
2904__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2905{
2906 int start = skb_headlen(skb);
2907 int i, copy = start - offset;
2908 struct sk_buff *frag_iter;
2909 int elt = 0;
2910
2911 if (copy > 0) {
2912 if (copy > len)
2913 copy = len;
2914 sg_set_buf(sg, skb->data + offset, copy);
2915 elt++;
2916 if ((len -= copy) == 0)
2917 return elt;
2918 offset += copy;
2919 }
2920
2921 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2922 int end;
2923
2924 WARN_ON(start > offset + len);
2925
2926 end = start + skb_shinfo(skb)->frags[i].size;
2927 if ((copy = end - offset) > 0) {
2928 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2929
2930 if (copy > len)
2931 copy = len;
2932 sg_set_page(&sg[elt], frag->page, copy,
2933 frag->page_offset+offset-start);
2934 elt++;
2935 if (!(len -= copy))
2936 return elt;
2937 offset += copy;
2938 }
2939 start = end;
2940 }
2941
2942 skb_walk_frags(skb, frag_iter) {
2943 int end;
2944
2945 WARN_ON(start > offset + len);
2946
2947 end = start + frag_iter->len;
2948 if ((copy = end - offset) > 0) {
2949 if (copy > len)
2950 copy = len;
2951 elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
2952 copy);
2953 if ((len -= copy) == 0)
2954 return elt;
2955 offset += copy;
2956 }
2957 start = end;
2958 }
2959 BUG_ON(len);
2960 return elt;
2961}
2962
2963int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
2964{
2965 int nsg = __skb_to_sgvec(skb, sg, offset, len);
2966
2967 sg_mark_end(&sg[nsg - 1]);
2968
2969 return nsg;
2970}
2971EXPORT_SYMBOL_GPL(skb_to_sgvec);
2972
2973/**
2974 * skb_cow_data - Check that a socket buffer's data buffers are writable
2975 * @skb: The socket buffer to check.
2976 * @tailbits: Amount of trailing space to be added
2977 * @trailer: Returned pointer to the skb where the @tailbits space begins
2978 *
2979 * Make sure that the data buffers attached to a socket buffer are
2980 * writable. If they are not, private copies are made of the data buffers
2981 * and the socket buffer is set to use these instead.
2982 *
2983 * If @tailbits is given, make sure that there is space to write @tailbits
2984 * bytes of data beyond current end of socket buffer. @trailer will be
2985 * set to point to the skb in which this space begins.
2986 *
2987 * The number of scatterlist elements required to completely map the
2988 * COW'd and extended socket buffer will be returned.
2989 */
2990int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
2991{
2992 int copyflag;
2993 int elt;
2994 struct sk_buff *skb1, **skb_p;
2995
2996 /* If skb is cloned or its head is paged, reallocate
2997 * head pulling out all the pages (pages are considered not writable
2998 * at the moment even if they are anonymous).
2999 */
3000 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
3001 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
3002 return -ENOMEM;
3003
3004 /* Easy case. Most of packets will go this way. */
3005 if (!skb_has_frag_list(skb)) {
3006 /* A little of trouble, not enough of space for trailer.
3007 * This should not happen, when stack is tuned to generate
3008 * good frames. OK, on miss we reallocate and reserve even more
3009 * space, 128 bytes is fair. */
3010
3011 if (skb_tailroom(skb) < tailbits &&
3012 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
3013 return -ENOMEM;
3014
3015 /* Voila! */
3016 *trailer = skb;
3017 return 1;
3018 }
3019
3020 /* Misery. We are in troubles, going to mincer fragments... */
3021
3022 elt = 1;
3023 skb_p = &skb_shinfo(skb)->frag_list;
3024 copyflag = 0;
3025
3026 while ((skb1 = *skb_p) != NULL) {
3027 int ntail = 0;
3028
3029 /* The fragment is partially pulled by someone,
3030 * this can happen on input. Copy it and everything
3031 * after it. */
3032
3033 if (skb_shared(skb1))
3034 copyflag = 1;
3035
3036 /* If the skb is the last, worry about trailer. */
3037
3038 if (skb1->next == NULL && tailbits) {
3039 if (skb_shinfo(skb1)->nr_frags ||
3040 skb_has_frag_list(skb1) ||
3041 skb_tailroom(skb1) < tailbits)
3042 ntail = tailbits + 128;
3043 }
3044
3045 if (copyflag ||
3046 skb_cloned(skb1) ||
3047 ntail ||
3048 skb_shinfo(skb1)->nr_frags ||
3049 skb_has_frag_list(skb1)) {
3050 struct sk_buff *skb2;
3051
3052 /* Fuck, we are miserable poor guys... */
3053 if (ntail == 0)
3054 skb2 = skb_copy(skb1, GFP_ATOMIC);
3055 else
3056 skb2 = skb_copy_expand(skb1,
3057 skb_headroom(skb1),
3058 ntail,
3059 GFP_ATOMIC);
3060 if (unlikely(skb2 == NULL))
3061 return -ENOMEM;
3062
3063 if (skb1->sk)
3064 skb_set_owner_w(skb2, skb1->sk);
3065
3066 /* Looking around. Are we still alive?
3067 * OK, link new skb, drop old one */
3068
3069 skb2->next = skb1->next;
3070 *skb_p = skb2;
3071 kfree_skb(skb1);
3072 skb1 = skb2;
3073 }
3074 elt++;
3075 *trailer = skb1;
3076 skb_p = &skb1->next;
3077 }
3078
3079 return elt;
3080}
3081EXPORT_SYMBOL_GPL(skb_cow_data);
3082
3083static void sock_rmem_free(struct sk_buff *skb)
3084{
3085 struct sock *sk = skb->sk;
3086
3087 atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
3088}
3089
3090/*
3091 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
3092 */
3093int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
3094{
3095 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
3096 (unsigned)sk->sk_rcvbuf)
3097 return -ENOMEM;
3098
3099 skb_orphan(skb);
3100 skb->sk = sk;
3101 skb->destructor = sock_rmem_free;
3102 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
3103
3104 /* before exiting rcu section, make sure dst is refcounted */
3105 skb_dst_force(skb);
3106
3107 skb_queue_tail(&sk->sk_error_queue, skb);
3108 if (!sock_flag(sk, SOCK_DEAD))
3109 sk->sk_data_ready(sk, skb->len);
3110 return 0;
3111}
3112EXPORT_SYMBOL(sock_queue_err_skb);
3113
3114void skb_tstamp_tx(struct sk_buff *orig_skb,
3115 struct skb_shared_hwtstamps *hwtstamps)
3116{
3117 struct sock *sk = orig_skb->sk;
3118 struct sock_exterr_skb *serr;
3119 struct sk_buff *skb;
3120 int err;
3121
3122 if (!sk)
3123 return;
3124
3125 skb = skb_clone(orig_skb, GFP_ATOMIC);
3126 if (!skb)
3127 return;
3128
3129 if (hwtstamps) {
3130 *skb_hwtstamps(skb) =
3131 *hwtstamps;
3132 } else {
3133 /*
3134 * no hardware time stamps available,
3135 * so keep the shared tx_flags and only
3136 * store software time stamp
3137 */
3138 skb->tstamp = ktime_get_real();
3139 }
3140
3141 serr = SKB_EXT_ERR(skb);
3142 memset(serr, 0, sizeof(*serr));
3143 serr->ee.ee_errno = ENOMSG;
3144 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3145
3146 err = sock_queue_err_skb(sk, skb);
3147
3148 if (err)
3149 kfree_skb(skb);
3150}
3151EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3152
3153
3154/**
3155 * skb_partial_csum_set - set up and verify partial csum values for packet
3156 * @skb: the skb to set
3157 * @start: the number of bytes after skb->data to start checksumming.
3158 * @off: the offset from start to place the checksum.
3159 *
3160 * For untrusted partially-checksummed packets, we need to make sure the values
3161 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3162 *
3163 * This function checks and sets those values and skb->ip_summed: if this
3164 * returns false you should drop the packet.
3165 */
3166bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3167{
3168 if (unlikely(start > skb_headlen(skb)) ||
3169 unlikely((int)start + off > skb_headlen(skb) - 2)) {
3170 if (net_ratelimit())
3171 printk(KERN_WARNING
3172 "bad partial csum: csum=%u/%u len=%u\n",
3173 start, off, skb_headlen(skb));
3174 return false;
3175 }
3176 skb->ip_summed = CHECKSUM_PARTIAL;
3177 skb->csum_start = skb_headroom(skb) + start;
3178 skb->csum_offset = off;
3179 return true;
3180}
3181EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3182
3183void __skb_warn_lro_forwarding(const struct sk_buff *skb)
3184{
3185 if (net_ratelimit())
3186 pr_warning("%s: received packets cannot be forwarded"
3187 " while LRO is enabled\n", skb->dev->name);
3188}
3189EXPORT_SYMBOL(__skb_warn_lro_forwarding);