Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5

Linux/net/core/skbuff.c

  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/tcp.h>
 51 #include <linux/udp.h>
 52 #include <linux/netdevice.h>
 53 #ifdef CONFIG_NET_CLS_ACT
 54 #include <net/pkt_sched.h>
 55 #endif
 56 #include <linux/string.h>
 57 #include <linux/skbuff.h>
 58 #include <linux/splice.h>
 59 #include <linux/cache.h>
 60 #include <linux/rtnetlink.h>
 61 #include <linux/init.h>
 62 #include <linux/scatterlist.h>
 63 #include <linux/errqueue.h>
 64 #include <linux/prefetch.h>
 65 #include <linux/if_vlan.h>
 66 
 67 #include <net/protocol.h>
 68 #include <net/dst.h>
 69 #include <net/sock.h>
 70 #include <net/checksum.h>
 71 #include <net/ip6_checksum.h>
 72 #include <net/xfrm.h>
 73 
 74 #include <asm/uaccess.h>
 75 #include <trace/events/skb.h>
 76 #include <linux/highmem.h>
 77 #include <linux/capability.h>
 78 #include <linux/user_namespace.h>
 79 
 80 struct kmem_cache *skbuff_head_cache __read_mostly;
 81 static struct kmem_cache *skbuff_fclone_cache __read_mostly;
 82 int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
 83 EXPORT_SYMBOL(sysctl_max_skb_frags);
 84 
 85 /**
 86  *      skb_panic - private function for out-of-line support
 87  *      @skb:   buffer
 88  *      @sz:    size
 89  *      @addr:  address
 90  *      @msg:   skb_over_panic or skb_under_panic
 91  *
 92  *      Out-of-line support for skb_put() and skb_push().
 93  *      Called via the wrapper skb_over_panic() or skb_under_panic().
 94  *      Keep out of line to prevent kernel bloat.
 95  *      __builtin_return_address is not used because it is not always reliable.
 96  */
 97 static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
 98                       const char msg[])
 99 {
100         pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n",
101                  msg, addr, skb->len, sz, skb->head, skb->data,
102                  (unsigned long)skb->tail, (unsigned long)skb->end,
103                  skb->dev ? skb->dev->name : "<NULL>");
104         BUG();
105 }
106 
107 static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
108 {
109         skb_panic(skb, sz, addr, __func__);
110 }
111 
112 static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
113 {
114         skb_panic(skb, sz, addr, __func__);
115 }
116 
117 /*
118  * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
119  * the caller if emergency pfmemalloc reserves are being used. If it is and
120  * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
121  * may be used. Otherwise, the packet data may be discarded until enough
122  * memory is free
123  */
124 #define kmalloc_reserve(size, gfp, node, pfmemalloc) \
125          __kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc)
126 
127 static void *__kmalloc_reserve(size_t size, gfp_t flags, int node,
128                                unsigned long ip, bool *pfmemalloc)
129 {
130         void *obj;
131         bool ret_pfmemalloc = false;
132 
133         /*
134          * Try a regular allocation, when that fails and we're not entitled
135          * to the reserves, fail.
136          */
137         obj = kmalloc_node_track_caller(size,
138                                         flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
139                                         node);
140         if (obj || !(gfp_pfmemalloc_allowed(flags)))
141                 goto out;
142 
143         /* Try again but now we are using pfmemalloc reserves */
144         ret_pfmemalloc = true;
145         obj = kmalloc_node_track_caller(size, flags, node);
146 
147 out:
148         if (pfmemalloc)
149                 *pfmemalloc = ret_pfmemalloc;
150 
151         return obj;
152 }
153 
154 /*      Allocate a new skbuff. We do this ourselves so we can fill in a few
155  *      'private' fields and also do memory statistics to find all the
156  *      [BEEP] leaks.
157  *
158  */
159 
160 struct sk_buff *__alloc_skb_head(gfp_t gfp_mask, int node)
161 {
162         struct sk_buff *skb;
163 
164         /* Get the HEAD */
165         skb = kmem_cache_alloc_node(skbuff_head_cache,
166                                     gfp_mask & ~__GFP_DMA, node);
167         if (!skb)
168                 goto out;
169 
170         /*
171          * Only clear those fields we need to clear, not those that we will
172          * actually initialise below. Hence, don't put any more fields after
173          * the tail pointer in struct sk_buff!
174          */
175         memset(skb, 0, offsetof(struct sk_buff, tail));
176         skb->head = NULL;
177         skb->truesize = sizeof(struct sk_buff);
178         atomic_set(&skb->users, 1);
179 
180         skb->mac_header = (typeof(skb->mac_header))~0U;
181 out:
182         return skb;
183 }
184 
185 /**
186  *      __alloc_skb     -       allocate a network buffer
187  *      @size: size to allocate
188  *      @gfp_mask: allocation mask
189  *      @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
190  *              instead of head cache and allocate a cloned (child) skb.
191  *              If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
192  *              allocations in case the data is required for writeback
193  *      @node: numa node to allocate memory on
194  *
195  *      Allocate a new &sk_buff. The returned buffer has no headroom and a
196  *      tail room of at least size bytes. The object has a reference count
197  *      of one. The return is the buffer. On a failure the return is %NULL.
198  *
199  *      Buffers may only be allocated from interrupts using a @gfp_mask of
200  *      %GFP_ATOMIC.
201  */
202 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
203                             int flags, int node)
204 {
205         struct kmem_cache *cache;
206         struct skb_shared_info *shinfo;
207         struct sk_buff *skb;
208         u8 *data;
209         bool pfmemalloc;
210 
211         cache = (flags & SKB_ALLOC_FCLONE)
212                 ? skbuff_fclone_cache : skbuff_head_cache;
213 
214         if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
215                 gfp_mask |= __GFP_MEMALLOC;
216 
217         /* Get the HEAD */
218         skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
219         if (!skb)
220                 goto out;
221         prefetchw(skb);
222 
223         /* We do our best to align skb_shared_info on a separate cache
224          * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
225          * aligned memory blocks, unless SLUB/SLAB debug is enabled.
226          * Both skb->head and skb_shared_info are cache line aligned.
227          */
228         size = SKB_DATA_ALIGN(size);
229         size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
230         data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
231         if (!data)
232                 goto nodata;
233         /* kmalloc(size) might give us more room than requested.
234          * Put skb_shared_info exactly at the end of allocated zone,
235          * to allow max possible filling before reallocation.
236          */
237         size = SKB_WITH_OVERHEAD(ksize(data));
238         prefetchw(data + size);
239 
240         /*
241          * Only clear those fields we need to clear, not those that we will
242          * actually initialise below. Hence, don't put any more fields after
243          * the tail pointer in struct sk_buff!
244          */
245         memset(skb, 0, offsetof(struct sk_buff, tail));
246         /* Account for allocated memory : skb + skb->head */
247         skb->truesize = SKB_TRUESIZE(size);
248         skb->pfmemalloc = pfmemalloc;
249         atomic_set(&skb->users, 1);
250         skb->head = data;
251         skb->data = data;
252         skb_reset_tail_pointer(skb);
253         skb->end = skb->tail + size;
254         skb->mac_header = (typeof(skb->mac_header))~0U;
255         skb->transport_header = (typeof(skb->transport_header))~0U;
256 
257         /* make sure we initialize shinfo sequentially */
258         shinfo = skb_shinfo(skb);
259         memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
260         atomic_set(&shinfo->dataref, 1);
261         kmemcheck_annotate_variable(shinfo->destructor_arg);
262 
263         if (flags & SKB_ALLOC_FCLONE) {
264                 struct sk_buff_fclones *fclones;
265 
266                 fclones = container_of(skb, struct sk_buff_fclones, skb1);
267 
268                 kmemcheck_annotate_bitfield(&fclones->skb2, flags1);
269                 skb->fclone = SKB_FCLONE_ORIG;
270                 atomic_set(&fclones->fclone_ref, 1);
271 
272                 fclones->skb2.fclone = SKB_FCLONE_CLONE;
273                 fclones->skb2.pfmemalloc = pfmemalloc;
274         }
275 out:
276         return skb;
277 nodata:
278         kmem_cache_free(cache, skb);
279         skb = NULL;
280         goto out;
281 }
282 EXPORT_SYMBOL(__alloc_skb);
283 
284 /**
285  * __build_skb - build a network buffer
286  * @data: data buffer provided by caller
287  * @frag_size: size of data, or 0 if head was kmalloced
288  *
289  * Allocate a new &sk_buff. Caller provides space holding head and
290  * skb_shared_info. @data must have been allocated by kmalloc() only if
291  * @frag_size is 0, otherwise data should come from the page allocator
292  *  or vmalloc()
293  * The return is the new skb buffer.
294  * On a failure the return is %NULL, and @data is not freed.
295  * Notes :
296  *  Before IO, driver allocates only data buffer where NIC put incoming frame
297  *  Driver should add room at head (NET_SKB_PAD) and
298  *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
299  *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
300  *  before giving packet to stack.
301  *  RX rings only contains data buffers, not full skbs.
302  */
303 struct sk_buff *__build_skb(void *data, unsigned int frag_size)
304 {
305         struct skb_shared_info *shinfo;
306         struct sk_buff *skb;
307         unsigned int size = frag_size ? : ksize(data);
308 
309         skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
310         if (!skb)
311                 return NULL;
312 
313         size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
314 
315         memset(skb, 0, offsetof(struct sk_buff, tail));
316         skb->truesize = SKB_TRUESIZE(size);
317         atomic_set(&skb->users, 1);
318         skb->head = data;
319         skb->data = data;
320         skb_reset_tail_pointer(skb);
321         skb->end = skb->tail + size;
322         skb->mac_header = (typeof(skb->mac_header))~0U;
323         skb->transport_header = (typeof(skb->transport_header))~0U;
324 
325         /* make sure we initialize shinfo sequentially */
326         shinfo = skb_shinfo(skb);
327         memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
328         atomic_set(&shinfo->dataref, 1);
329         kmemcheck_annotate_variable(shinfo->destructor_arg);
330 
331         return skb;
332 }
333 
334 /* build_skb() is wrapper over __build_skb(), that specifically
335  * takes care of skb->head and skb->pfmemalloc
336  * This means that if @frag_size is not zero, then @data must be backed
337  * by a page fragment, not kmalloc() or vmalloc()
338  */
339 struct sk_buff *build_skb(void *data, unsigned int frag_size)
340 {
341         struct sk_buff *skb = __build_skb(data, frag_size);
342 
343         if (skb && frag_size) {
344                 skb->head_frag = 1;
345                 if (page_is_pfmemalloc(virt_to_head_page(data)))
346                         skb->pfmemalloc = 1;
347         }
348         return skb;
349 }
350 EXPORT_SYMBOL(build_skb);
351 
352 static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
353 static DEFINE_PER_CPU(struct page_frag_cache, napi_alloc_cache);
354 
355 static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
356 {
357         struct page_frag_cache *nc;
358         unsigned long flags;
359         void *data;
360 
361         local_irq_save(flags);
362         nc = this_cpu_ptr(&netdev_alloc_cache);
363         data = __alloc_page_frag(nc, fragsz, gfp_mask);
364         local_irq_restore(flags);
365         return data;
366 }
367 
368 /**
369  * netdev_alloc_frag - allocate a page fragment
370  * @fragsz: fragment size
371  *
372  * Allocates a frag from a page for receive buffer.
373  * Uses GFP_ATOMIC allocations.
374  */
375 void *netdev_alloc_frag(unsigned int fragsz)
376 {
377         return __netdev_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD);
378 }
379 EXPORT_SYMBOL(netdev_alloc_frag);
380 
381 static void *__napi_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
382 {
383         struct page_frag_cache *nc = this_cpu_ptr(&napi_alloc_cache);
384 
385         return __alloc_page_frag(nc, fragsz, gfp_mask);
386 }
387 
388 void *napi_alloc_frag(unsigned int fragsz)
389 {
390         return __napi_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD);
391 }
392 EXPORT_SYMBOL(napi_alloc_frag);
393 
394 /**
395  *      __netdev_alloc_skb - allocate an skbuff for rx on a specific device
396  *      @dev: network device to receive on
397  *      @len: length to allocate
398  *      @gfp_mask: get_free_pages mask, passed to alloc_skb
399  *
400  *      Allocate a new &sk_buff and assign it a usage count of one. The
401  *      buffer has NET_SKB_PAD headroom built in. Users should allocate
402  *      the headroom they think they need without accounting for the
403  *      built in space. The built in space is used for optimisations.
404  *
405  *      %NULL is returned if there is no free memory.
406  */
407 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
408                                    gfp_t gfp_mask)
409 {
410         struct page_frag_cache *nc;
411         unsigned long flags;
412         struct sk_buff *skb;
413         bool pfmemalloc;
414         void *data;
415 
416         len += NET_SKB_PAD;
417 
418         if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
419             (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
420                 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
421                 if (!skb)
422                         goto skb_fail;
423                 goto skb_success;
424         }
425 
426         len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
427         len = SKB_DATA_ALIGN(len);
428 
429         if (sk_memalloc_socks())
430                 gfp_mask |= __GFP_MEMALLOC;
431 
432         local_irq_save(flags);
433 
434         nc = this_cpu_ptr(&netdev_alloc_cache);
435         data = __alloc_page_frag(nc, len, gfp_mask);
436         pfmemalloc = nc->pfmemalloc;
437 
438         local_irq_restore(flags);
439 
440         if (unlikely(!data))
441                 return NULL;
442 
443         skb = __build_skb(data, len);
444         if (unlikely(!skb)) {
445                 skb_free_frag(data);
446                 return NULL;
447         }
448 
449         /* use OR instead of assignment to avoid clearing of bits in mask */
450         if (pfmemalloc)
451                 skb->pfmemalloc = 1;
452         skb->head_frag = 1;
453 
454 skb_success:
455         skb_reserve(skb, NET_SKB_PAD);
456         skb->dev = dev;
457 
458 skb_fail:
459         return skb;
460 }
461 EXPORT_SYMBOL(__netdev_alloc_skb);
462 
463 /**
464  *      __napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
465  *      @napi: napi instance this buffer was allocated for
466  *      @len: length to allocate
467  *      @gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
468  *
469  *      Allocate a new sk_buff for use in NAPI receive.  This buffer will
470  *      attempt to allocate the head from a special reserved region used
471  *      only for NAPI Rx allocation.  By doing this we can save several
472  *      CPU cycles by avoiding having to disable and re-enable IRQs.
473  *
474  *      %NULL is returned if there is no free memory.
475  */
476 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
477                                  gfp_t gfp_mask)
478 {
479         struct page_frag_cache *nc = this_cpu_ptr(&napi_alloc_cache);
480         struct sk_buff *skb;
481         void *data;
482 
483         len += NET_SKB_PAD + NET_IP_ALIGN;
484 
485         if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
486             (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
487                 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
488                 if (!skb)
489                         goto skb_fail;
490                 goto skb_success;
491         }
492 
493         len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
494         len = SKB_DATA_ALIGN(len);
495 
496         if (sk_memalloc_socks())
497                 gfp_mask |= __GFP_MEMALLOC;
498 
499         data = __alloc_page_frag(nc, len, gfp_mask);
500         if (unlikely(!data))
501                 return NULL;
502 
503         skb = __build_skb(data, len);
504         if (unlikely(!skb)) {
505                 skb_free_frag(data);
506                 return NULL;
507         }
508 
509         /* use OR instead of assignment to avoid clearing of bits in mask */
510         if (nc->pfmemalloc)
511                 skb->pfmemalloc = 1;
512         skb->head_frag = 1;
513 
514 skb_success:
515         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
516         skb->dev = napi->dev;
517 
518 skb_fail:
519         return skb;
520 }
521 EXPORT_SYMBOL(__napi_alloc_skb);
522 
523 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
524                      int size, unsigned int truesize)
525 {
526         skb_fill_page_desc(skb, i, page, off, size);
527         skb->len += size;
528         skb->data_len += size;
529         skb->truesize += truesize;
530 }
531 EXPORT_SYMBOL(skb_add_rx_frag);
532 
533 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
534                           unsigned int truesize)
535 {
536         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
537 
538         skb_frag_size_add(frag, size);
539         skb->len += size;
540         skb->data_len += size;
541         skb->truesize += truesize;
542 }
543 EXPORT_SYMBOL(skb_coalesce_rx_frag);
544 
545 static void skb_drop_list(struct sk_buff **listp)
546 {
547         kfree_skb_list(*listp);
548         *listp = NULL;
549 }
550 
551 static inline void skb_drop_fraglist(struct sk_buff *skb)
552 {
553         skb_drop_list(&skb_shinfo(skb)->frag_list);
554 }
555 
556 static void skb_clone_fraglist(struct sk_buff *skb)
557 {
558         struct sk_buff *list;
559 
560         skb_walk_frags(skb, list)
561                 skb_get(list);
562 }
563 
564 static void skb_free_head(struct sk_buff *skb)
565 {
566         unsigned char *head = skb->head;
567 
568         if (skb->head_frag)
569                 skb_free_frag(head);
570         else
571                 kfree(head);
572 }
573 
574 static void skb_release_data(struct sk_buff *skb)
575 {
576         struct skb_shared_info *shinfo = skb_shinfo(skb);
577         int i;
578 
579         if (skb->cloned &&
580             atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
581                               &shinfo->dataref))
582                 return;
583 
584         for (i = 0; i < shinfo->nr_frags; i++)
585                 __skb_frag_unref(&shinfo->frags[i]);
586 
587         /*
588          * If skb buf is from userspace, we need to notify the caller
589          * the lower device DMA has done;
590          */
591         if (shinfo->tx_flags & SKBTX_DEV_ZEROCOPY) {
592                 struct ubuf_info *uarg;
593 
594                 uarg = shinfo->destructor_arg;
595                 if (uarg->callback)
596                         uarg->callback(uarg, true);
597         }
598 
599         if (shinfo->frag_list)
600                 kfree_skb_list(shinfo->frag_list);
601 
602         skb_free_head(skb);
603 }
604 
605 /*
606  *      Free an skbuff by memory without cleaning the state.
607  */
608 static void kfree_skbmem(struct sk_buff *skb)
609 {
610         struct sk_buff_fclones *fclones;
611 
612         switch (skb->fclone) {
613         case SKB_FCLONE_UNAVAILABLE:
614                 kmem_cache_free(skbuff_head_cache, skb);
615                 return;
616 
617         case SKB_FCLONE_ORIG:
618                 fclones = container_of(skb, struct sk_buff_fclones, skb1);
619 
620                 /* We usually free the clone (TX completion) before original skb
621                  * This test would have no chance to be true for the clone,
622                  * while here, branch prediction will be good.
623                  */
624                 if (atomic_read(&fclones->fclone_ref) == 1)
625                         goto fastpath;
626                 break;
627 
628         default: /* SKB_FCLONE_CLONE */
629                 fclones = container_of(skb, struct sk_buff_fclones, skb2);
630                 break;
631         }
632         if (!atomic_dec_and_test(&fclones->fclone_ref))
633                 return;
634 fastpath:
635         kmem_cache_free(skbuff_fclone_cache, fclones);
636 }
637 
638 static void skb_release_head_state(struct sk_buff *skb)
639 {
640         skb_dst_drop(skb);
641 #ifdef CONFIG_XFRM
642         secpath_put(skb->sp);
643 #endif
644         if (skb->destructor) {
645                 WARN_ON(in_irq());
646                 skb->destructor(skb);
647         }
648 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
649         nf_conntrack_put(skb->nfct);
650 #endif
651 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
652         nf_bridge_put(skb->nf_bridge);
653 #endif
654 }
655 
656 /* Free everything but the sk_buff shell. */
657 static void skb_release_all(struct sk_buff *skb)
658 {
659         skb_release_head_state(skb);
660         if (likely(skb->head))
661                 skb_release_data(skb);
662 }
663 
664 /**
665  *      __kfree_skb - private function
666  *      @skb: buffer
667  *
668  *      Free an sk_buff. Release anything attached to the buffer.
669  *      Clean the state. This is an internal helper function. Users should
670  *      always call kfree_skb
671  */
672 
673 void __kfree_skb(struct sk_buff *skb)
674 {
675         skb_release_all(skb);
676         kfree_skbmem(skb);
677 }
678 EXPORT_SYMBOL(__kfree_skb);
679 
680 /**
681  *      kfree_skb - free an sk_buff
682  *      @skb: buffer to free
683  *
684  *      Drop a reference to the buffer and free it if the usage count has
685  *      hit zero.
686  */
687 void kfree_skb(struct sk_buff *skb)
688 {
689         if (unlikely(!skb))
690                 return;
691         if (likely(atomic_read(&skb->users) == 1))
692                 smp_rmb();
693         else if (likely(!atomic_dec_and_test(&skb->users)))
694                 return;
695         trace_kfree_skb(skb, __builtin_return_address(0));
696         __kfree_skb(skb);
697 }
698 EXPORT_SYMBOL(kfree_skb);
699 
700 void kfree_skb_list(struct sk_buff *segs)
701 {
702         while (segs) {
703                 struct sk_buff *next = segs->next;
704 
705                 kfree_skb(segs);
706                 segs = next;
707         }
708 }
709 EXPORT_SYMBOL(kfree_skb_list);
710 
711 /**
712  *      skb_tx_error - report an sk_buff xmit error
713  *      @skb: buffer that triggered an error
714  *
715  *      Report xmit error if a device callback is tracking this skb.
716  *      skb must be freed afterwards.
717  */
718 void skb_tx_error(struct sk_buff *skb)
719 {
720         if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
721                 struct ubuf_info *uarg;
722 
723                 uarg = skb_shinfo(skb)->destructor_arg;
724                 if (uarg->callback)
725                         uarg->callback(uarg, false);
726                 skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
727         }
728 }
729 EXPORT_SYMBOL(skb_tx_error);
730 
731 /**
732  *      consume_skb - free an skbuff
733  *      @skb: buffer to free
734  *
735  *      Drop a ref to the buffer and free it if the usage count has hit zero
736  *      Functions identically to kfree_skb, but kfree_skb assumes that the frame
737  *      is being dropped after a failure and notes that
738  */
739 void consume_skb(struct sk_buff *skb)
740 {
741         if (unlikely(!skb))
742                 return;
743         if (likely(atomic_read(&skb->users) == 1))
744                 smp_rmb();
745         else if (likely(!atomic_dec_and_test(&skb->users)))
746                 return;
747         trace_consume_skb(skb);
748         __kfree_skb(skb);
749 }
750 EXPORT_SYMBOL(consume_skb);
751 
752 /* Make sure a field is enclosed inside headers_start/headers_end section */
753 #define CHECK_SKB_FIELD(field) \
754         BUILD_BUG_ON(offsetof(struct sk_buff, field) <          \
755                      offsetof(struct sk_buff, headers_start));  \
756         BUILD_BUG_ON(offsetof(struct sk_buff, field) >          \
757                      offsetof(struct sk_buff, headers_end));    \
758 
759 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
760 {
761         new->tstamp             = old->tstamp;
762         /* We do not copy old->sk */
763         new->dev                = old->dev;
764         memcpy(new->cb, old->cb, sizeof(old->cb));
765         skb_dst_copy(new, old);
766 #ifdef CONFIG_XFRM
767         new->sp                 = secpath_get(old->sp);
768 #endif
769         __nf_copy(new, old, false);
770 
771         /* Note : this field could be in headers_start/headers_end section
772          * It is not yet because we do not want to have a 16 bit hole
773          */
774         new->queue_mapping = old->queue_mapping;
775 
776         memcpy(&new->headers_start, &old->headers_start,
777                offsetof(struct sk_buff, headers_end) -
778                offsetof(struct sk_buff, headers_start));
779         CHECK_SKB_FIELD(protocol);
780         CHECK_SKB_FIELD(csum);
781         CHECK_SKB_FIELD(hash);
782         CHECK_SKB_FIELD(priority);
783         CHECK_SKB_FIELD(skb_iif);
784         CHECK_SKB_FIELD(vlan_proto);
785         CHECK_SKB_FIELD(vlan_tci);
786         CHECK_SKB_FIELD(transport_header);
787         CHECK_SKB_FIELD(network_header);
788         CHECK_SKB_FIELD(mac_header);
789         CHECK_SKB_FIELD(inner_protocol);
790         CHECK_SKB_FIELD(inner_transport_header);
791         CHECK_SKB_FIELD(inner_network_header);
792         CHECK_SKB_FIELD(inner_mac_header);
793         CHECK_SKB_FIELD(mark);
794 #ifdef CONFIG_NETWORK_SECMARK
795         CHECK_SKB_FIELD(secmark);
796 #endif
797 #ifdef CONFIG_NET_RX_BUSY_POLL
798         CHECK_SKB_FIELD(napi_id);
799 #endif
800 #ifdef CONFIG_XPS
801         CHECK_SKB_FIELD(sender_cpu);
802 #endif
803 #ifdef CONFIG_NET_SCHED
804         CHECK_SKB_FIELD(tc_index);
805 #ifdef CONFIG_NET_CLS_ACT
806         CHECK_SKB_FIELD(tc_verd);
807 #endif
808 #endif
809 
810 }
811 
812 /*
813  * You should not add any new code to this function.  Add it to
814  * __copy_skb_header above instead.
815  */
816 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
817 {
818 #define C(x) n->x = skb->x
819 
820         n->next = n->prev = NULL;
821         n->sk = NULL;
822         __copy_skb_header(n, skb);
823 
824         C(len);
825         C(data_len);
826         C(mac_len);
827         n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
828         n->cloned = 1;
829         n->nohdr = 0;
830         n->destructor = NULL;
831         C(tail);
832         C(end);
833         C(head);
834         C(head_frag);
835         C(data);
836         C(truesize);
837         atomic_set(&n->users, 1);
838 
839         atomic_inc(&(skb_shinfo(skb)->dataref));
840         skb->cloned = 1;
841 
842         return n;
843 #undef C
844 }
845 
846 /**
847  *      skb_morph       -       morph one skb into another
848  *      @dst: the skb to receive the contents
849  *      @src: the skb to supply the contents
850  *
851  *      This is identical to skb_clone except that the target skb is
852  *      supplied by the user.
853  *
854  *      The target skb is returned upon exit.
855  */
856 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
857 {
858         skb_release_all(dst);
859         return __skb_clone(dst, src);
860 }
861 EXPORT_SYMBOL_GPL(skb_morph);
862 
863 /**
864  *      skb_copy_ubufs  -       copy userspace skb frags buffers to kernel
865  *      @skb: the skb to modify
866  *      @gfp_mask: allocation priority
867  *
868  *      This must be called on SKBTX_DEV_ZEROCOPY skb.
869  *      It will copy all frags into kernel and drop the reference
870  *      to userspace pages.
871  *
872  *      If this function is called from an interrupt gfp_mask() must be
873  *      %GFP_ATOMIC.
874  *
875  *      Returns 0 on success or a negative error code on failure
876  *      to allocate kernel memory to copy to.
877  */
878 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
879 {
880         int i;
881         int num_frags = skb_shinfo(skb)->nr_frags;
882         struct page *page, *head = NULL;
883         struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;
884 
885         for (i = 0; i < num_frags; i++) {
886                 u8 *vaddr;
887                 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
888 
889                 page = alloc_page(gfp_mask);
890                 if (!page) {
891                         while (head) {
892                                 struct page *next = (struct page *)page_private(head);
893                                 put_page(head);
894                                 head = next;
895                         }
896                         return -ENOMEM;
897                 }
898                 vaddr = kmap_atomic(skb_frag_page(f));
899                 memcpy(page_address(page),
900                        vaddr + f->page_offset, skb_frag_size(f));
901                 kunmap_atomic(vaddr);
902                 set_page_private(page, (unsigned long)head);
903                 head = page;
904         }
905 
906         /* skb frags release userspace buffers */
907         for (i = 0; i < num_frags; i++)
908                 skb_frag_unref(skb, i);
909 
910         uarg->callback(uarg, false);
911 
912         /* skb frags point to kernel buffers */
913         for (i = num_frags - 1; i >= 0; i--) {
914                 __skb_fill_page_desc(skb, i, head, 0,
915                                      skb_shinfo(skb)->frags[i].size);
916                 head = (struct page *)page_private(head);
917         }
918 
919         skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
920         return 0;
921 }
922 EXPORT_SYMBOL_GPL(skb_copy_ubufs);
923 
924 /**
925  *      skb_clone       -       duplicate an sk_buff
926  *      @skb: buffer to clone
927  *      @gfp_mask: allocation priority
928  *
929  *      Duplicate an &sk_buff. The new one is not owned by a socket. Both
930  *      copies share the same packet data but not structure. The new
931  *      buffer has a reference count of 1. If the allocation fails the
932  *      function returns %NULL otherwise the new buffer is returned.
933  *
934  *      If this function is called from an interrupt gfp_mask() must be
935  *      %GFP_ATOMIC.
936  */
937 
938 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
939 {
940         struct sk_buff_fclones *fclones = container_of(skb,
941                                                        struct sk_buff_fclones,
942                                                        skb1);
943         struct sk_buff *n;
944 
945         if (skb_orphan_frags(skb, gfp_mask))
946                 return NULL;
947 
948         if (skb->fclone == SKB_FCLONE_ORIG &&
949             atomic_read(&fclones->fclone_ref) == 1) {
950                 n = &fclones->skb2;
951                 atomic_set(&fclones->fclone_ref, 2);
952         } else {
953                 if (skb_pfmemalloc(skb))
954                         gfp_mask |= __GFP_MEMALLOC;
955 
956                 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
957                 if (!n)
958                         return NULL;
959 
960                 kmemcheck_annotate_bitfield(n, flags1);
961                 n->fclone = SKB_FCLONE_UNAVAILABLE;
962         }
963 
964         return __skb_clone(n, skb);
965 }
966 EXPORT_SYMBOL(skb_clone);
967 
968 static void skb_headers_offset_update(struct sk_buff *skb, int off)
969 {
970         /* Only adjust this if it actually is csum_start rather than csum */
971         if (skb->ip_summed == CHECKSUM_PARTIAL)
972                 skb->csum_start += off;
973         /* {transport,network,mac}_header and tail are relative to skb->head */
974         skb->transport_header += off;
975         skb->network_header   += off;
976         if (skb_mac_header_was_set(skb))
977                 skb->mac_header += off;
978         skb->inner_transport_header += off;
979         skb->inner_network_header += off;
980         skb->inner_mac_header += off;
981 }
982 
983 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
984 {
985         __copy_skb_header(new, old);
986 
987         skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
988         skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
989         skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
990 }
991 
992 static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
993 {
994         if (skb_pfmemalloc(skb))
995                 return SKB_ALLOC_RX;
996         return 0;
997 }
998 
999 /**
1000  *      skb_copy        -       create private copy of an sk_buff
1001  *      @skb: buffer to copy
1002  *      @gfp_mask: allocation priority
1003  *
1004  *      Make a copy of both an &sk_buff and its data. This is used when the
1005  *      caller wishes to modify the data and needs a private copy of the
1006  *      data to alter. Returns %NULL on failure or the pointer to the buffer
1007  *      on success. The returned buffer has a reference count of 1.
1008  *
1009  *      As by-product this function converts non-linear &sk_buff to linear
1010  *      one, so that &sk_buff becomes completely private and caller is allowed
1011  *      to modify all the data of returned buffer. This means that this
1012  *      function is not recommended for use in circumstances when only
1013  *      header is going to be modified. Use pskb_copy() instead.
1014  */
1015 
1016 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
1017 {
1018         int headerlen = skb_headroom(skb);
1019         unsigned int size = skb_end_offset(skb) + skb->data_len;
1020         struct sk_buff *n = __alloc_skb(size, gfp_mask,
1021                                         skb_alloc_rx_flag(skb), NUMA_NO_NODE);
1022 
1023         if (!n)
1024                 return NULL;
1025 
1026         /* Set the data pointer */
1027         skb_reserve(n, headerlen);
1028         /* Set the tail pointer and length */
1029         skb_put(n, skb->len);
1030 
1031         if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
1032                 BUG();
1033 
1034         copy_skb_header(n, skb);
1035         return n;
1036 }
1037 EXPORT_SYMBOL(skb_copy);
1038 
1039 /**
1040  *      __pskb_copy_fclone      -  create copy of an sk_buff with private head.
1041  *      @skb: buffer to copy
1042  *      @headroom: headroom of new skb
1043  *      @gfp_mask: allocation priority
1044  *      @fclone: if true allocate the copy of the skb from the fclone
1045  *      cache instead of the head cache; it is recommended to set this
1046  *      to true for the cases where the copy will likely be cloned
1047  *
1048  *      Make a copy of both an &sk_buff and part of its data, located
1049  *      in header. Fragmented data remain shared. This is used when
1050  *      the caller wishes to modify only header of &sk_buff and needs
1051  *      private copy of the header to alter. Returns %NULL on failure
1052  *      or the pointer to the buffer on success.
1053  *      The returned buffer has a reference count of 1.
1054  */
1055 
1056 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
1057                                    gfp_t gfp_mask, bool fclone)
1058 {
1059         unsigned int size = skb_headlen(skb) + headroom;
1060         int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
1061         struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
1062 
1063         if (!n)
1064                 goto out;
1065 
1066         /* Set the data pointer */
1067         skb_reserve(n, headroom);
1068         /* Set the tail pointer and length */
1069         skb_put(n, skb_headlen(skb));
1070         /* Copy the bytes */
1071         skb_copy_from_linear_data(skb, n->data, n->len);
1072 
1073         n->truesize += skb->data_len;
1074         n->data_len  = skb->data_len;
1075         n->len       = skb->len;
1076 
1077         if (skb_shinfo(skb)->nr_frags) {
1078                 int i;
1079 
1080                 if (skb_orphan_frags(skb, gfp_mask)) {
1081                         kfree_skb(n);
1082                         n = NULL;
1083                         goto out;
1084                 }
1085                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1086                         skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
1087                         skb_frag_ref(skb, i);
1088                 }
1089                 skb_shinfo(n)->nr_frags = i;
1090         }
1091 
1092         if (skb_has_frag_list(skb)) {
1093                 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
1094                 skb_clone_fraglist(n);
1095         }
1096 
1097         copy_skb_header(n, skb);
1098 out:
1099         return n;
1100 }
1101 EXPORT_SYMBOL(__pskb_copy_fclone);
1102 
1103 /**
1104  *      pskb_expand_head - reallocate header of &sk_buff
1105  *      @skb: buffer to reallocate
1106  *      @nhead: room to add at head
1107  *      @ntail: room to add at tail
1108  *      @gfp_mask: allocation priority
1109  *
1110  *      Expands (or creates identical copy, if @nhead and @ntail are zero)
1111  *      header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
1112  *      reference count of 1. Returns zero in the case of success or error,
1113  *      if expansion failed. In the last case, &sk_buff is not changed.
1114  *
1115  *      All the pointers pointing into skb header may change and must be
1116  *      reloaded after call to this function.
1117  */
1118 
1119 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
1120                      gfp_t gfp_mask)
1121 {
1122         int i;
1123         u8 *data;
1124         int size = nhead + skb_end_offset(skb) + ntail;
1125         long off;
1126 
1127         BUG_ON(nhead < 0);
1128 
1129         if (skb_shared(skb))
1130                 BUG();
1131 
1132         size = SKB_DATA_ALIGN(size);
1133 
1134         if (skb_pfmemalloc(skb))
1135                 gfp_mask |= __GFP_MEMALLOC;
1136         data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
1137                                gfp_mask, NUMA_NO_NODE, NULL);
1138         if (!data)
1139                 goto nodata;
1140         size = SKB_WITH_OVERHEAD(ksize(data));
1141 
1142         /* Copy only real data... and, alas, header. This should be
1143          * optimized for the cases when header is void.
1144          */
1145         memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
1146 
1147         memcpy((struct skb_shared_info *)(data + size),
1148                skb_shinfo(skb),
1149                offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
1150 
1151         /*
1152          * if shinfo is shared we must drop the old head gracefully, but if it
1153          * is not we can just drop the old head and let the existing refcount
1154          * be since all we did is relocate the values
1155          */
1156         if (skb_cloned(skb)) {
1157                 /* copy this zero copy skb frags */
1158                 if (skb_orphan_frags(skb, gfp_mask))
1159                         goto nofrags;
1160                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1161                         skb_frag_ref(skb, i);
1162 
1163                 if (skb_has_frag_list(skb))
1164                         skb_clone_fraglist(skb);
1165 
1166                 skb_release_data(skb);
1167         } else {
1168                 skb_free_head(skb);
1169         }
1170         off = (data + nhead) - skb->head;
1171 
1172         skb->head     = data;
1173         skb->head_frag = 0;
1174         skb->data    += off;
1175 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1176         skb->end      = size;
1177         off           = nhead;
1178 #else
1179         skb->end      = skb->head + size;
1180 #endif
1181         skb->tail             += off;
1182         skb_headers_offset_update(skb, nhead);
1183         skb->cloned   = 0;
1184         skb->hdr_len  = 0;
1185         skb->nohdr    = 0;
1186         atomic_set(&skb_shinfo(skb)->dataref, 1);
1187         return 0;
1188 
1189 nofrags:
1190         kfree(data);
1191 nodata:
1192         return -ENOMEM;
1193 }
1194 EXPORT_SYMBOL(pskb_expand_head);
1195 
1196 /* Make private copy of skb with writable head and some headroom */
1197 
1198 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1199 {
1200         struct sk_buff *skb2;
1201         int delta = headroom - skb_headroom(skb);
1202 
1203         if (delta <= 0)
1204                 skb2 = pskb_copy(skb, GFP_ATOMIC);
1205         else {
1206                 skb2 = skb_clone(skb, GFP_ATOMIC);
1207                 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1208                                              GFP_ATOMIC)) {
1209                         kfree_skb(skb2);
1210                         skb2 = NULL;
1211                 }
1212         }
1213         return skb2;
1214 }
1215 EXPORT_SYMBOL(skb_realloc_headroom);
1216 
1217 /**
1218  *      skb_copy_expand -       copy and expand sk_buff
1219  *      @skb: buffer to copy
1220  *      @newheadroom: new free bytes at head
1221  *      @newtailroom: new free bytes at tail
1222  *      @gfp_mask: allocation priority
1223  *
1224  *      Make a copy of both an &sk_buff and its data and while doing so
1225  *      allocate additional space.
1226  *
1227  *      This is used when the caller wishes to modify the data and needs a
1228  *      private copy of the data to alter as well as more space for new fields.
1229  *      Returns %NULL on failure or the pointer to the buffer
1230  *      on success. The returned buffer has a reference count of 1.
1231  *
1232  *      You must pass %GFP_ATOMIC as the allocation priority if this function
1233  *      is called from an interrupt.
1234  */
1235 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
1236                                 int newheadroom, int newtailroom,
1237                                 gfp_t gfp_mask)
1238 {
1239         /*
1240          *      Allocate the copy buffer
1241          */
1242         struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
1243                                         gfp_mask, skb_alloc_rx_flag(skb),
1244                                         NUMA_NO_NODE);
1245         int oldheadroom = skb_headroom(skb);
1246         int head_copy_len, head_copy_off;
1247 
1248         if (!n)
1249                 return NULL;
1250 
1251         skb_reserve(n, newheadroom);
1252 
1253         /* Set the tail pointer and length */
1254         skb_put(n, skb->len);
1255 
1256         head_copy_len = oldheadroom;
1257         head_copy_off = 0;
1258         if (newheadroom <= head_copy_len)
1259                 head_copy_len = newheadroom;
1260         else
1261                 head_copy_off = newheadroom - head_copy_len;
1262 
1263         /* Copy the linear header and data. */
1264         if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1265                           skb->len + head_copy_len))
1266                 BUG();
1267 
1268         copy_skb_header(n, skb);
1269 
1270         skb_headers_offset_update(n, newheadroom - oldheadroom);
1271 
1272         return n;
1273 }
1274 EXPORT_SYMBOL(skb_copy_expand);
1275 
1276 /**
1277  *      skb_pad                 -       zero pad the tail of an skb
1278  *      @skb: buffer to pad
1279  *      @pad: space to pad
1280  *
1281  *      Ensure that a buffer is followed by a padding area that is zero
1282  *      filled. Used by network drivers which may DMA or transfer data
1283  *      beyond the buffer end onto the wire.
1284  *
1285  *      May return error in out of memory cases. The skb is freed on error.
1286  */
1287 
1288 int skb_pad(struct sk_buff *skb, int pad)
1289 {
1290         int err;
1291         int ntail;
1292 
1293         /* If the skbuff is non linear tailroom is always zero.. */
1294         if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1295                 memset(skb->data+skb->len, 0, pad);
1296                 return 0;
1297         }
1298 
1299         ntail = skb->data_len + pad - (skb->end - skb->tail);
1300         if (likely(skb_cloned(skb) || ntail > 0)) {
1301                 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1302                 if (unlikely(err))
1303                         goto free_skb;
1304         }
1305 
1306         /* FIXME: The use of this function with non-linear skb's really needs
1307          * to be audited.
1308          */
1309         err = skb_linearize(skb);
1310         if (unlikely(err))
1311                 goto free_skb;
1312 
1313         memset(skb->data + skb->len, 0, pad);
1314         return 0;
1315 
1316 free_skb:
1317         kfree_skb(skb);
1318         return err;
1319 }
1320 EXPORT_SYMBOL(skb_pad);
1321 
1322 /**
1323  *      pskb_put - add data to the tail of a potentially fragmented buffer
1324  *      @skb: start of the buffer to use
1325  *      @tail: tail fragment of the buffer to use
1326  *      @len: amount of data to add
1327  *
1328  *      This function extends the used data area of the potentially
1329  *      fragmented buffer. @tail must be the last fragment of @skb -- or
1330  *      @skb itself. If this would exceed the total buffer size the kernel
1331  *      will panic. A pointer to the first byte of the extra data is
1332  *      returned.
1333  */
1334 
1335 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
1336 {
1337         if (tail != skb) {
1338                 skb->data_len += len;
1339                 skb->len += len;
1340         }
1341         return skb_put(tail, len);
1342 }
1343 EXPORT_SYMBOL_GPL(pskb_put);
1344 
1345 /**
1346  *      skb_put - add data to a buffer
1347  *      @skb: buffer to use
1348  *      @len: amount of data to add
1349  *
1350  *      This function extends the used data area of the buffer. If this would
1351  *      exceed the total buffer size the kernel will panic. A pointer to the
1352  *      first byte of the extra data is returned.
1353  */
1354 unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
1355 {
1356         unsigned char *tmp = skb_tail_pointer(skb);
1357         SKB_LINEAR_ASSERT(skb);
1358         skb->tail += len;
1359         skb->len  += len;
1360         if (unlikely(skb->tail > skb->end))
1361                 skb_over_panic(skb, len, __builtin_return_address(0));
1362         return tmp;
1363 }
1364 EXPORT_SYMBOL(skb_put);
1365 
1366 /**
1367  *      skb_push - add data to the start of a buffer
1368  *      @skb: buffer to use
1369  *      @len: amount of data to add
1370  *
1371  *      This function extends the used data area of the buffer at the buffer
1372  *      start. If this would exceed the total buffer headroom the kernel will
1373  *      panic. A pointer to the first byte of the extra data is returned.
1374  */
1375 unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1376 {
1377         skb->data -= len;
1378         skb->len  += len;
1379         if (unlikely(skb->data<skb->head))
1380                 skb_under_panic(skb, len, __builtin_return_address(0));
1381         return skb->data;
1382 }
1383 EXPORT_SYMBOL(skb_push);
1384 
1385 /**
1386  *      skb_pull - remove data from the start of a buffer
1387  *      @skb: buffer to use
1388  *      @len: amount of data to remove
1389  *
1390  *      This function removes data from the start of a buffer, returning
1391  *      the memory to the headroom. A pointer to the next data in the buffer
1392  *      is returned. Once the data has been pulled future pushes will overwrite
1393  *      the old data.
1394  */
1395 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1396 {
1397         return skb_pull_inline(skb, len);
1398 }
1399 EXPORT_SYMBOL(skb_pull);
1400 
1401 /**
1402  *      skb_trim - remove end from a buffer
1403  *      @skb: buffer to alter
1404  *      @len: new length
1405  *
1406  *      Cut the length of a buffer down by removing data from the tail. If
1407  *      the buffer is already under the length specified it is not modified.
1408  *      The skb must be linear.
1409  */
1410 void skb_trim(struct sk_buff *skb, unsigned int len)
1411 {
1412         if (skb->len > len)
1413                 __skb_trim(skb, len);
1414 }
1415 EXPORT_SYMBOL(skb_trim);
1416 
1417 /* Trims skb to length len. It can change skb pointers.
1418  */
1419 
1420 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1421 {
1422         struct sk_buff **fragp;
1423         struct sk_buff *frag;
1424         int offset = skb_headlen(skb);
1425         int nfrags = skb_shinfo(skb)->nr_frags;
1426         int i;
1427         int err;
1428 
1429         if (skb_cloned(skb) &&
1430             unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1431                 return err;
1432 
1433         i = 0;
1434         if (offset >= len)
1435                 goto drop_pages;
1436 
1437         for (; i < nfrags; i++) {
1438                 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
1439 
1440                 if (end < len) {
1441                         offset = end;
1442                         continue;
1443                 }
1444 
1445                 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
1446 
1447 drop_pages:
1448                 skb_shinfo(skb)->nr_frags = i;
1449 
1450                 for (; i < nfrags; i++)
1451                         skb_frag_unref(skb, i);
1452 
1453                 if (skb_has_frag_list(skb))
1454                         skb_drop_fraglist(skb);
1455                 goto done;
1456         }
1457 
1458         for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1459              fragp = &frag->next) {
1460                 int end = offset + frag->len;
1461 
1462                 if (skb_shared(frag)) {
1463                         struct sk_buff *nfrag;
1464 
1465                         nfrag = skb_clone(frag, GFP_ATOMIC);
1466                         if (unlikely(!nfrag))
1467                                 return -ENOMEM;
1468 
1469                         nfrag->next = frag->next;
1470                         consume_skb(frag);
1471                         frag = nfrag;
1472                         *fragp = frag;
1473                 }
1474 
1475                 if (end < len) {
1476                         offset = end;
1477                         continue;
1478                 }
1479 
1480                 if (end > len &&
1481                     unlikely((err = pskb_trim(frag, len - offset))))
1482                         return err;
1483 
1484                 if (frag->next)
1485                         skb_drop_list(&frag->next);
1486                 break;
1487         }
1488 
1489 done:
1490         if (len > skb_headlen(skb)) {
1491                 skb->data_len -= skb->len - len;
1492                 skb->len       = len;
1493         } else {
1494                 skb->len       = len;
1495                 skb->data_len  = 0;
1496                 skb_set_tail_pointer(skb, len);
1497         }
1498 
1499         return 0;
1500 }
1501 EXPORT_SYMBOL(___pskb_trim);
1502 
1503 /**
1504  *      __pskb_pull_tail - advance tail of skb header
1505  *      @skb: buffer to reallocate
1506  *      @delta: number of bytes to advance tail
1507  *
1508  *      The function makes a sense only on a fragmented &sk_buff,
1509  *      it expands header moving its tail forward and copying necessary
1510  *      data from fragmented part.
1511  *
1512  *      &sk_buff MUST have reference count of 1.
1513  *
1514  *      Returns %NULL (and &sk_buff does not change) if pull failed
1515  *      or value of new tail of skb in the case of success.
1516  *
1517  *      All the pointers pointing into skb header may change and must be
1518  *      reloaded after call to this function.
1519  */
1520 
1521 /* Moves tail of skb head forward, copying data from fragmented part,
1522  * when it is necessary.
1523  * 1. It may fail due to malloc failure.
1524  * 2. It may change skb pointers.
1525  *
1526  * It is pretty complicated. Luckily, it is called only in exceptional cases.
1527  */
1528 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1529 {
1530         /* If skb has not enough free space at tail, get new one
1531          * plus 128 bytes for future expansions. If we have enough
1532          * room at tail, reallocate without expansion only if skb is cloned.
1533          */
1534         int i, k, eat = (skb->tail + delta) - skb->end;
1535 
1536         if (eat > 0 || skb_cloned(skb)) {
1537                 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1538                                      GFP_ATOMIC))
1539                         return NULL;
1540         }
1541 
1542         if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1543                 BUG();
1544 
1545         /* Optimization: no fragments, no reasons to preestimate
1546          * size of pulled pages. Superb.
1547          */
1548         if (!skb_has_frag_list(skb))
1549                 goto pull_pages;
1550 
1551         /* Estimate size of pulled pages. */
1552         eat = delta;
1553         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1554                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1555 
1556                 if (size >= eat)
1557                         goto pull_pages;
1558                 eat -= size;
1559         }
1560 
1561         /* If we need update frag list, we are in troubles.
1562          * Certainly, it possible to add an offset to skb data,
1563          * but taking into account that pulling is expected to
1564          * be very rare operation, it is worth to fight against
1565          * further bloating skb head and crucify ourselves here instead.
1566          * Pure masohism, indeed. 8)8)
1567          */
1568         if (eat) {
1569                 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1570                 struct sk_buff *clone = NULL;
1571                 struct sk_buff *insp = NULL;
1572 
1573                 do {
1574                         BUG_ON(!list);
1575 
1576                         if (list->len <= eat) {
1577                                 /* Eaten as whole. */
1578                                 eat -= list->len;
1579                                 list = list->next;
1580                                 insp = list;
1581                         } else {
1582                                 /* Eaten partially. */
1583 
1584                                 if (skb_shared(list)) {
1585                                         /* Sucks! We need to fork list. :-( */
1586                                         clone = skb_clone(list, GFP_ATOMIC);
1587                                         if (!clone)
1588                                                 return NULL;
1589                                         insp = list->next;
1590                                         list = clone;
1591                                 } else {
1592                                         /* This may be pulled without
1593                                          * problems. */
1594                                         insp = list;
1595                                 }
1596                                 if (!pskb_pull(list, eat)) {
1597                                         kfree_skb(clone);
1598                                         return NULL;
1599                                 }
1600                                 break;
1601                         }
1602                 } while (eat);
1603 
1604                 /* Free pulled out fragments. */
1605                 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1606                         skb_shinfo(skb)->frag_list = list->next;
1607                         kfree_skb(list);
1608                 }
1609                 /* And insert new clone at head. */
1610                 if (clone) {
1611                         clone->next = list;
1612                         skb_shinfo(skb)->frag_list = clone;
1613                 }
1614         }
1615         /* Success! Now we may commit changes to skb data. */
1616 
1617 pull_pages:
1618         eat = delta;
1619         k = 0;
1620         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1621                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1622 
1623                 if (size <= eat) {
1624                         skb_frag_unref(skb, i);
1625                         eat -= size;
1626                 } else {
1627                         skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1628                         if (eat) {
1629                                 skb_shinfo(skb)->frags[k].page_offset += eat;
1630                                 skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
1631                                 eat = 0;
1632                         }
1633                         k++;
1634                 }
1635         }
1636         skb_shinfo(skb)->nr_frags = k;
1637 
1638         skb->tail     += delta;
1639         skb->data_len -= delta;
1640 
1641         return skb_tail_pointer(skb);
1642 }
1643 EXPORT_SYMBOL(__pskb_pull_tail);
1644 
1645 /**
1646  *      skb_copy_bits - copy bits from skb to kernel buffer
1647  *      @skb: source skb
1648  *      @offset: offset in source
1649  *      @to: destination buffer
1650  *      @len: number of bytes to copy
1651  *
1652  *      Copy the specified number of bytes from the source skb to the
1653  *      destination buffer.
1654  *
1655  *      CAUTION ! :
1656  *              If its prototype is ever changed,
1657  *              check arch/{*}/net/{*}.S files,
1658  *              since it is called from BPF assembly code.
1659  */
1660 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1661 {
1662         int start = skb_headlen(skb);
1663         struct sk_buff *frag_iter;
1664         int i, copy;
1665 
1666         if (offset > (int)skb->len - len)
1667                 goto fault;
1668 
1669         /* Copy header. */
1670         if ((copy = start - offset) > 0) {
1671                 if (copy > len)
1672                         copy = len;
1673                 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1674                 if ((len -= copy) == 0)
1675                         return 0;
1676                 offset += copy;
1677                 to     += copy;
1678         }
1679 
1680         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1681                 int end;
1682                 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1683 
1684                 WARN_ON(start > offset + len);
1685 
1686                 end = start + skb_frag_size(f);
1687                 if ((copy = end - offset) > 0) {
1688                         u8 *vaddr;
1689 
1690                         if (copy > len)
1691                                 copy = len;
1692 
1693                         vaddr = kmap_atomic(skb_frag_page(f));
1694                         memcpy(to,
1695                                vaddr + f->page_offset + offset - start,
1696                                copy);
1697                         kunmap_atomic(vaddr);
1698 
1699                         if ((len -= copy) == 0)
1700                                 return 0;
1701                         offset += copy;
1702                         to     += copy;
1703                 }
1704                 start = end;
1705         }
1706 
1707         skb_walk_frags(skb, frag_iter) {
1708                 int end;
1709 
1710                 WARN_ON(start > offset + len);
1711 
1712                 end = start + frag_iter->len;
1713                 if ((copy = end - offset) > 0) {
1714                         if (copy > len)
1715                                 copy = len;
1716                         if (skb_copy_bits(frag_iter, offset - start, to, copy))
1717                                 goto fault;
1718                         if ((len -= copy) == 0)
1719                                 return 0;
1720                         offset += copy;
1721                         to     += copy;
1722                 }
1723                 start = end;
1724         }
1725 
1726         if (!len)
1727                 return 0;
1728 
1729 fault:
1730         return -EFAULT;
1731 }
1732 EXPORT_SYMBOL(skb_copy_bits);
1733 
1734 /*
1735  * Callback from splice_to_pipe(), if we need to release some pages
1736  * at the end of the spd in case we error'ed out in filling the pipe.
1737  */
1738 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1739 {
1740         put_page(spd->pages[i]);
1741 }
1742 
1743 static struct page *linear_to_page(struct page *page, unsigned int *len,
1744                                    unsigned int *offset,
1745                                    struct sock *sk)
1746 {
1747         struct page_frag *pfrag = sk_page_frag(sk);
1748 
1749         if (!sk_page_frag_refill(sk, pfrag))
1750                 return NULL;
1751 
1752         *len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
1753 
1754         memcpy(page_address(pfrag->page) + pfrag->offset,
1755                page_address(page) + *offset, *len);
1756         *offset = pfrag->offset;
1757         pfrag->offset += *len;
1758 
1759         return pfrag->page;
1760 }
1761 
1762 static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
1763                              struct page *page,
1764                              unsigned int offset)
1765 {
1766         return  spd->nr_pages &&
1767                 spd->pages[spd->nr_pages - 1] == page &&
1768                 (spd->partial[spd->nr_pages - 1].offset +
1769                  spd->partial[spd->nr_pages - 1].len == offset);
1770 }
1771 
1772 /*
1773  * Fill page/offset/length into spd, if it can hold more pages.
1774  */
1775 static bool spd_fill_page(struct splice_pipe_desc *spd,
1776                           struct pipe_inode_info *pipe, struct page *page,
1777                           unsigned int *len, unsigned int offset,
1778                           bool linear,
1779                           struct sock *sk)
1780 {
1781         if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
1782                 return true;
1783 
1784         if (linear) {
1785                 page = linear_to_page(page, len, &offset, sk);
1786                 if (!page)
1787                         return true;
1788         }
1789         if (spd_can_coalesce(spd, page, offset)) {
1790                 spd->partial[spd->nr_pages - 1].len += *len;
1791                 return false;
1792         }
1793         get_page(page);
1794         spd->pages[spd->nr_pages] = page;
1795         spd->partial[spd->nr_pages].len = *len;
1796         spd->partial[spd->nr_pages].offset = offset;
1797         spd->nr_pages++;
1798 
1799         return false;
1800 }
1801 
1802 static bool __splice_segment(struct page *page, unsigned int poff,
1803                              unsigned int plen, unsigned int *off,
1804                              unsigned int *len,
1805                              struct splice_pipe_desc *spd, bool linear,
1806                              struct sock *sk,
1807                              struct pipe_inode_info *pipe)
1808 {
1809         if (!*len)
1810                 return true;
1811 
1812         /* skip this segment if already processed */
1813         if (*off >= plen) {
1814                 *off -= plen;
1815                 return false;
1816         }
1817 
1818         /* ignore any bits we already processed */
1819         poff += *off;
1820         plen -= *off;
1821         *off = 0;
1822 
1823         do {
1824                 unsigned int flen = min(*len, plen);
1825 
1826                 if (spd_fill_page(spd, pipe, page, &flen, poff,
1827                                   linear, sk))
1828                         return true;
1829                 poff += flen;
1830                 plen -= flen;
1831                 *len -= flen;
1832         } while (*len && plen);
1833 
1834         return false;
1835 }
1836 
1837 /*
1838  * Map linear and fragment data from the skb to spd. It reports true if the
1839  * pipe is full or if we already spliced the requested length.
1840  */
1841 static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
1842                               unsigned int *offset, unsigned int *len,
1843                               struct splice_pipe_desc *spd, struct sock *sk)
1844 {
1845         int seg;
1846 
1847         /* map the linear part :
1848          * If skb->head_frag is set, this 'linear' part is backed by a
1849          * fragment, and if the head is not shared with any clones then
1850          * we can avoid a copy since we own the head portion of this page.
1851          */
1852         if (__splice_segment(virt_to_page(skb->data),
1853                              (unsigned long) skb->data & (PAGE_SIZE - 1),
1854                              skb_headlen(skb),
1855                              offset, len, spd,
1856                              skb_head_is_locked(skb),
1857                              sk, pipe))
1858                 return true;
1859 
1860         /*
1861          * then map the fragments
1862          */
1863         for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1864                 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1865 
1866                 if (__splice_segment(skb_frag_page(f),
1867                                      f->page_offset, skb_frag_size(f),
1868                                      offset, len, spd, false, sk, pipe))
1869                         return true;
1870         }
1871 
1872         return false;
1873 }
1874 
1875 ssize_t skb_socket_splice(struct sock *sk,
1876                           struct pipe_inode_info *pipe,
1877                           struct splice_pipe_desc *spd)
1878 {
1879         int ret;
1880 
1881         /* Drop the socket lock, otherwise we have reverse
1882          * locking dependencies between sk_lock and i_mutex
1883          * here as compared to sendfile(). We enter here
1884          * with the socket lock held, and splice_to_pipe() will
1885          * grab the pipe inode lock. For sendfile() emulation,
1886          * we call into ->sendpage() with the i_mutex lock held
1887          * and networking will grab the socket lock.
1888          */
1889         release_sock(sk);
1890         ret = splice_to_pipe(pipe, spd);
1891         lock_sock(sk);
1892 
1893         return ret;
1894 }
1895 
1896 /*
1897  * Map data from the skb to a pipe. Should handle both the linear part,
1898  * the fragments, and the frag list. It does NOT handle frag lists within
1899  * the frag list, if such a thing exists. We'd probably need to recurse to
1900  * handle that cleanly.
1901  */
1902 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
1903                     struct pipe_inode_info *pipe, unsigned int tlen,
1904                     unsigned int flags,
1905                     ssize_t (*splice_cb)(struct sock *,
1906                                          struct pipe_inode_info *,
1907                                          struct splice_pipe_desc *))
1908 {
1909         struct partial_page partial[MAX_SKB_FRAGS];
1910         struct page *pages[MAX_SKB_FRAGS];
1911         struct splice_pipe_desc spd = {
1912                 .pages = pages,
1913                 .partial = partial,
1914                 .nr_pages_max = MAX_SKB_FRAGS,
1915                 .flags = flags,
1916                 .ops = &nosteal_pipe_buf_ops,
1917                 .spd_release = sock_spd_release,
1918         };
1919         struct sk_buff *frag_iter;
1920         int ret = 0;
1921 
1922         /*
1923          * __skb_splice_bits() only fails if the output has no room left,
1924          * so no point in going over the frag_list for the error case.
1925          */
1926         if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
1927                 goto done;
1928         else if (!tlen)
1929                 goto done;
1930 
1931         /*
1932          * now see if we have a frag_list to map
1933          */
1934         skb_walk_frags(skb, frag_iter) {
1935                 if (!tlen)
1936                         break;
1937                 if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
1938                         break;
1939         }
1940 
1941 done:
1942         if (spd.nr_pages)
1943                 ret = splice_cb(sk, pipe, &spd);
1944 
1945         return ret;
1946 }
1947 EXPORT_SYMBOL_GPL(skb_splice_bits);
1948 
1949 /**
1950  *      skb_store_bits - store bits from kernel buffer to skb
1951  *      @skb: destination buffer
1952  *      @offset: offset in destination
1953  *      @from: source buffer
1954  *      @len: number of bytes to copy
1955  *
1956  *      Copy the specified number of bytes from the source buffer to the
1957  *      destination skb.  This function handles all the messy bits of
1958  *      traversing fragment lists and such.
1959  */
1960 
1961 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1962 {
1963         int start = skb_headlen(skb);
1964         struct sk_buff *frag_iter;
1965         int i, copy;
1966 
1967         if (offset > (int)skb->len - len)
1968                 goto fault;
1969 
1970         if ((copy = start - offset) > 0) {
1971                 if (copy > len)
1972                         copy = len;
1973                 skb_copy_to_linear_data_offset(skb, offset, from, copy);
1974                 if ((len -= copy) == 0)
1975                         return 0;
1976                 offset += copy;
1977                 from += copy;
1978         }
1979 
1980         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1981                 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1982                 int end;
1983 
1984                 WARN_ON(start > offset + len);
1985 
1986                 end = start + skb_frag_size(frag);
1987                 if ((copy = end - offset) > 0) {
1988                         u8 *vaddr;
1989 
1990                         if (copy > len)
1991                                 copy = len;
1992 
1993                         vaddr = kmap_atomic(skb_frag_page(frag));
1994                         memcpy(vaddr + frag->page_offset + offset - start,
1995                                from, copy);
1996                         kunmap_atomic(vaddr);
1997 
1998                         if ((len -= copy) == 0)
1999                                 return 0;
2000                         offset += copy;
2001                         from += copy;
2002                 }
2003                 start = end;
2004         }
2005 
2006         skb_walk_frags(skb, frag_iter) {
2007                 int end;
2008 
2009                 WARN_ON(start > offset + len);
2010 
2011                 end = start + frag_iter->len;
2012                 if ((copy = end - offset) > 0) {
2013                         if (copy > len)
2014                                 copy = len;
2015                         if (skb_store_bits(frag_iter, offset - start,
2016                                            from, copy))
2017                                 goto fault;
2018                         if ((len -= copy) == 0)
2019                                 return 0;
2020                         offset += copy;
2021                         from += copy;
2022                 }
2023                 start = end;
2024         }
2025         if (!len)
2026                 return 0;
2027 
2028 fault:
2029         return -EFAULT;
2030 }
2031 EXPORT_SYMBOL(skb_store_bits);
2032 
2033 /* Checksum skb data. */
2034 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2035                       __wsum csum, const struct skb_checksum_ops *ops)
2036 {
2037         int start = skb_headlen(skb);
2038         int i, copy = start - offset;
2039         struct sk_buff *frag_iter;
2040         int pos = 0;
2041 
2042         /* Checksum header. */
2043         if (copy > 0) {
2044                 if (copy > len)
2045                         copy = len;
2046                 csum = ops->update(skb->data + offset, copy, csum);
2047                 if ((len -= copy) == 0)
2048                         return csum;
2049                 offset += copy;
2050                 pos     = copy;
2051         }
2052 
2053         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2054                 int end;
2055                 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2056 
2057                 WARN_ON(start > offset + len);
2058 
2059                 end = start + skb_frag_size(frag);
2060                 if ((copy = end - offset) > 0) {
2061                         __wsum csum2;
2062                         u8 *vaddr;
2063 
2064                         if (copy > len)
2065                                 copy = len;
2066                         vaddr = kmap_atomic(skb_frag_page(frag));
2067                         csum2 = ops->update(vaddr + frag->page_offset +
2068                                             offset - start, copy, 0);
2069                         kunmap_atomic(vaddr);
2070                         csum = ops->combine(csum, csum2, pos, copy);
2071                         if (!(len -= copy))
2072                                 return csum;
2073                         offset += copy;
2074                         pos    += copy;
2075                 }
2076                 start = end;
2077         }
2078 
2079         skb_walk_frags(skb, frag_iter) {
2080                 int end;
2081 
2082                 WARN_ON(start > offset + len);
2083 
2084                 end = start + frag_iter->len;
2085                 if ((copy = end - offset) > 0) {
2086                         __wsum csum2;
2087                         if (copy > len)
2088                                 copy = len;
2089                         csum2 = __skb_checksum(frag_iter, offset - start,
2090                                                copy, 0, ops);
2091                         csum = ops->combine(csum, csum2, pos, copy);
2092                         if ((len -= copy) == 0)
2093                                 return csum;
2094                         offset += copy;
2095                         pos    += copy;
2096                 }
2097                 start = end;
2098         }
2099         BUG_ON(len);
2100 
2101         return csum;
2102 }
2103 EXPORT_SYMBOL(__skb_checksum);
2104 
2105 __wsum skb_checksum(const struct sk_buff *skb, int offset,
2106                     int len, __wsum csum)
2107 {
2108         const struct skb_checksum_ops ops = {
2109                 .update  = csum_partial_ext,
2110                 .combine = csum_block_add_ext,
2111         };
2112 
2113         return __skb_checksum(skb, offset, len, csum, &ops);
2114 }
2115 EXPORT_SYMBOL(skb_checksum);
2116 
2117 /* Both of above in one bottle. */
2118 
2119 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
2120                                     u8 *to, int len, __wsum csum)
2121 {
2122         int start = skb_headlen(skb);
2123         int i, copy = start - offset;
2124         struct sk_buff *frag_iter;
2125         int pos = 0;
2126 
2127         /* Copy header. */
2128         if (copy > 0) {
2129                 if (copy > len)
2130                         copy = len;
2131                 csum = csum_partial_copy_nocheck(skb->data + offset, to,
2132                                                  copy, csum);
2133                 if ((len -= copy) == 0)
2134                         return csum;
2135                 offset += copy;
2136                 to     += copy;
2137                 pos     = copy;
2138         }
2139 
2140         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2141                 int end;
2142 
2143                 WARN_ON(start > offset + len);
2144 
2145                 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2146                 if ((copy = end - offset) > 0) {
2147                         __wsum csum2;
2148                         u8 *vaddr;
2149                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2150 
2151                         if (copy > len)
2152                                 copy = len;
2153                         vaddr = kmap_atomic(skb_frag_page(frag));
2154                         csum2 = csum_partial_copy_nocheck(vaddr +
2155                                                           frag->page_offset +
2156                                                           offset - start, to,
2157                                                           copy, 0);
2158                         kunmap_atomic(vaddr);
2159                         csum = csum_block_add(csum, csum2, pos);
2160                         if (!(len -= copy))
2161                                 return csum;
2162                         offset += copy;
2163                         to     += copy;
2164                         pos    += copy;
2165                 }
2166                 start = end;
2167         }
2168 
2169         skb_walk_frags(skb, frag_iter) {
2170                 __wsum csum2;
2171                 int end;
2172 
2173                 WARN_ON(start > offset + len);
2174 
2175                 end = start + frag_iter->len;
2176                 if ((copy = end - offset) > 0) {
2177                         if (copy > len)
2178                                 copy = len;
2179                         csum2 = skb_copy_and_csum_bits(frag_iter,
2180                                                        offset - start,
2181                                                        to, copy, 0);
2182                         csum = csum_block_add(csum, csum2, pos);
2183                         if ((len -= copy) == 0)
2184                                 return csum;
2185                         offset += copy;
2186                         to     += copy;
2187                         pos    += copy;
2188                 }
2189                 start = end;
2190         }
2191         BUG_ON(len);
2192         return csum;
2193 }
2194 EXPORT_SYMBOL(skb_copy_and_csum_bits);
2195 
2196  /**
2197  *      skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
2198  *      @from: source buffer
2199  *
2200  *      Calculates the amount of linear headroom needed in the 'to' skb passed
2201  *      into skb_zerocopy().
2202  */
2203 unsigned int
2204 skb_zerocopy_headlen(const struct sk_buff *from)
2205 {
2206         unsigned int hlen = 0;
2207 
2208         if (!from->head_frag ||
2209             skb_headlen(from) < L1_CACHE_BYTES ||
2210             skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
2211                 hlen = skb_headlen(from);
2212 
2213         if (skb_has_frag_list(from))
2214                 hlen = from->len;
2215 
2216         return hlen;
2217 }
2218 EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
2219 
2220 /**
2221  *      skb_zerocopy - Zero copy skb to skb
2222  *      @to: destination buffer
2223  *      @from: source buffer
2224  *      @len: number of bytes to copy from source buffer
2225  *      @hlen: size of linear headroom in destination buffer
2226  *
2227  *      Copies up to `len` bytes from `from` to `to` by creating references
2228  *      to the frags in the source buffer.
2229  *
2230  *      The `hlen` as calculated by skb_zerocopy_headlen() specifies the
2231  *      headroom in the `to` buffer.
2232  *
2233  *      Return value:
2234  *      0: everything is OK
2235  *      -ENOMEM: couldn't orphan frags of @from due to lack of memory
2236  *      -EFAULT: skb_copy_bits() found some problem with skb geometry
2237  */
2238 int
2239 skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
2240 {
2241         int i, j = 0;
2242         int plen = 0; /* length of skb->head fragment */
2243         int ret;
2244         struct page *page;
2245         unsigned int offset;
2246 
2247         BUG_ON(!from->head_frag && !hlen);
2248 
2249         /* dont bother with small payloads */
2250         if (len <= skb_tailroom(to))
2251                 return skb_copy_bits(from, 0, skb_put(to, len), len);
2252 
2253         if (hlen) {
2254                 ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
2255                 if (unlikely(ret))
2256                         return ret;
2257                 len -= hlen;
2258         } else {
2259                 plen = min_t(int, skb_headlen(from), len);
2260                 if (plen) {
2261                         page = virt_to_head_page(from->head);
2262                         offset = from->data - (unsigned char *)page_address(page);
2263                         __skb_fill_page_desc(to, 0, page, offset, plen);
2264                         get_page(page);
2265                         j = 1;
2266                         len -= plen;
2267                 }
2268         }
2269 
2270         to->truesize += len + plen;
2271         to->len += len + plen;
2272         to->data_len += len + plen;
2273 
2274         if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
2275                 skb_tx_error(from);
2276                 return -ENOMEM;
2277         }
2278 
2279         for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
2280                 if (!len)
2281                         break;
2282                 skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
2283                 skb_shinfo(to)->frags[j].size = min_t(int, skb_shinfo(to)->frags[j].size, len);
2284                 len -= skb_shinfo(to)->frags[j].size;
2285                 skb_frag_ref(to, j);
2286                 j++;
2287         }
2288         skb_shinfo(to)->nr_frags = j;
2289 
2290         return 0;
2291 }
2292 EXPORT_SYMBOL_GPL(skb_zerocopy);
2293 
2294 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
2295 {
2296         __wsum csum;
2297         long csstart;
2298 
2299         if (skb->ip_summed == CHECKSUM_PARTIAL)
2300                 csstart = skb_checksum_start_offset(skb);
2301         else
2302                 csstart = skb_headlen(skb);
2303 
2304         BUG_ON(csstart > skb_headlen(skb));
2305 
2306         skb_copy_from_linear_data(skb, to, csstart);
2307 
2308         csum = 0;
2309         if (csstart != skb->len)
2310                 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
2311                                               skb->len - csstart, 0);
2312 
2313         if (skb->ip_summed == CHECKSUM_PARTIAL) {
2314                 long csstuff = csstart + skb->csum_offset;
2315 
2316                 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
2317         }
2318 }
2319 EXPORT_SYMBOL(skb_copy_and_csum_dev);
2320 
2321 /**
2322  *      skb_dequeue - remove from the head of the queue
2323  *      @list: list to dequeue from
2324  *
2325  *      Remove the head of the list. The list lock is taken so the function
2326  *      may be used safely with other locking list functions. The head item is
2327  *      returned or %NULL if the list is empty.
2328  */
2329 
2330 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
2331 {
2332         unsigned long flags;
2333         struct sk_buff *result;
2334 
2335         spin_lock_irqsave(&list->lock, flags);
2336         result = __skb_dequeue(list);
2337         spin_unlock_irqrestore(&list->lock, flags);
2338         return result;
2339 }
2340 EXPORT_SYMBOL(skb_dequeue);
2341 
2342 /**
2343  *      skb_dequeue_tail - remove from the tail of the queue
2344  *      @list: list to dequeue from
2345  *
2346  *      Remove the tail of the list. The list lock is taken so the function
2347  *      may be used safely with other locking list functions. The tail item is
2348  *      returned or %NULL if the list is empty.
2349  */
2350 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
2351 {
2352         unsigned long flags;
2353         struct sk_buff *result;
2354 
2355         spin_lock_irqsave(&list->lock, flags);
2356         result = __skb_dequeue_tail(list);
2357         spin_unlock_irqrestore(&list->lock, flags);
2358         return result;
2359 }
2360 EXPORT_SYMBOL(skb_dequeue_tail);
2361 
2362 /**
2363  *      skb_queue_purge - empty a list
2364  *      @list: list to empty
2365  *
2366  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2367  *      the list and one reference dropped. This function takes the list
2368  *      lock and is atomic with respect to other list locking functions.
2369  */
2370 void skb_queue_purge(struct sk_buff_head *list)
2371 {
2372         struct sk_buff *skb;
2373         while ((skb = skb_dequeue(list)) != NULL)
2374                 kfree_skb(skb);
2375 }
2376 EXPORT_SYMBOL(skb_queue_purge);
2377 
2378 /**
2379  *      skb_queue_head - queue a buffer at the list head
2380  *      @list: list to use
2381  *      @newsk: buffer to queue
2382  *
2383  *      Queue a buffer at the start of the list. This function takes the
2384  *      list lock and can be used safely with other locking &sk_buff functions
2385  *      safely.
2386  *
2387  *      A buffer cannot be placed on two lists at the same time.
2388  */
2389 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
2390 {
2391         unsigned long flags;
2392 
2393         spin_lock_irqsave(&list->lock, flags);
2394         __skb_queue_head(list, newsk);
2395         spin_unlock_irqrestore(&list->lock, flags);
2396 }
2397 EXPORT_SYMBOL(skb_queue_head);
2398 
2399 /**
2400  *      skb_queue_tail - queue a buffer at the list tail
2401  *      @list: list to use
2402  *      @newsk: buffer to queue
2403  *
2404  *      Queue a buffer at the tail of the list. This function takes the
2405  *      list lock and can be used safely with other locking &sk_buff functions
2406  *      safely.
2407  *
2408  *      A buffer cannot be placed on two lists at the same time.
2409  */
2410 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
2411 {
2412         unsigned long flags;
2413 
2414         spin_lock_irqsave(&list->lock, flags);
2415         __skb_queue_tail(list, newsk);
2416         spin_unlock_irqrestore(&list->lock, flags);
2417 }
2418 EXPORT_SYMBOL(skb_queue_tail);
2419 
2420 /**
2421  *      skb_unlink      -       remove a buffer from a list
2422  *      @skb: buffer to remove
2423  *      @list: list to use
2424  *
2425  *      Remove a packet from a list. The list locks are taken and this
2426  *      function is atomic with respect to other list locked calls
2427  *
2428  *      You must know what list the SKB is on.
2429  */
2430 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
2431 {
2432         unsigned long flags;
2433 
2434         spin_lock_irqsave(&list->lock, flags);
2435         __skb_unlink(skb, list);
2436         spin_unlock_irqrestore(&list->lock, flags);
2437 }
2438 EXPORT_SYMBOL(skb_unlink);
2439 
2440 /**
2441  *      skb_append      -       append a buffer
2442  *      @old: buffer to insert after
2443  *      @newsk: buffer to insert
2444  *      @list: list to use
2445  *
2446  *      Place a packet after a given packet in a list. The list locks are taken
2447  *      and this function is atomic with respect to other list locked calls.
2448  *      A buffer cannot be placed on two lists at the same time.
2449  */
2450 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2451 {
2452         unsigned long flags;
2453 
2454         spin_lock_irqsave(&list->lock, flags);
2455         __skb_queue_after(list, old, newsk);
2456         spin_unlock_irqrestore(&list->lock, flags);
2457 }
2458 EXPORT_SYMBOL(skb_append);
2459 
2460 /**
2461  *      skb_insert      -       insert a buffer
2462  *      @old: buffer to insert before
2463  *      @newsk: buffer to insert
2464  *      @list: list to use
2465  *
2466  *      Place a packet before a given packet in a list. The list locks are
2467  *      taken and this function is atomic with respect to other list locked
2468  *      calls.
2469  *
2470  *      A buffer cannot be placed on two lists at the same time.
2471  */
2472 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2473 {
2474         unsigned long flags;
2475 
2476         spin_lock_irqsave(&list->lock, flags);
2477         __skb_insert(newsk, old->prev, old, list);
2478         spin_unlock_irqrestore(&list->lock, flags);
2479 }
2480 EXPORT_SYMBOL(skb_insert);
2481 
2482 static inline void skb_split_inside_header(struct sk_buff *skb,
2483                                            struct sk_buff* skb1,
2484                                            const u32 len, const int pos)
2485 {
2486         int i;
2487 
2488         skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2489                                          pos - len);
2490         /* And move data appendix as is. */
2491         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2492                 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2493 
2494         skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2495         skb_shinfo(skb)->nr_frags  = 0;
2496         skb1->data_len             = skb->data_len;
2497         skb1->len                  += skb1->data_len;
2498         skb->data_len              = 0;
2499         skb->len                   = len;
2500         skb_set_tail_pointer(skb, len);
2501 }
2502 
2503 static inline void skb_split_no_header(struct sk_buff *skb,
2504                                        struct sk_buff* skb1,
2505                                        const u32 len, int pos)
2506 {
2507         int i, k = 0;
2508         const int nfrags = skb_shinfo(skb)->nr_frags;
2509 
2510         skb_shinfo(skb)->nr_frags = 0;
2511         skb1->len                 = skb1->data_len = skb->len - len;
2512         skb->len                  = len;
2513         skb->data_len             = len - pos;
2514 
2515         for (i = 0; i < nfrags; i++) {
2516                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2517 
2518                 if (pos + size > len) {
2519                         skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2520 
2521                         if (pos < len) {
2522                                 /* Split frag.
2523                                  * We have two variants in this case:
2524                                  * 1. Move all the frag to the second
2525                                  *    part, if it is possible. F.e.
2526                                  *    this approach is mandatory for TUX,
2527                                  *    where splitting is expensive.
2528                                  * 2. Split is accurately. We make this.
2529                                  */
2530                                 skb_frag_ref(skb, i);
2531                                 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2532                                 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
2533                                 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
2534                                 skb_shinfo(skb)->nr_frags++;
2535                         }
2536                         k++;
2537                 } else
2538                         skb_shinfo(skb)->nr_frags++;
2539                 pos += size;
2540         }
2541         skb_shinfo(skb1)->nr_frags = k;
2542 }
2543 
2544 /**
2545  * skb_split - Split fragmented skb to two parts at length len.
2546  * @skb: the buffer to split
2547  * @skb1: the buffer to receive the second part
2548  * @len: new length for skb
2549  */
2550 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2551 {
2552         int pos = skb_headlen(skb);
2553 
2554         skb_shinfo(skb1)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2555         if (len < pos)  /* Split line is inside header. */
2556                 skb_split_inside_header(skb, skb1, len, pos);
2557         else            /* Second chunk has no header, nothing to copy. */
2558                 skb_split_no_header(skb, skb1, len, pos);
2559 }
2560 EXPORT_SYMBOL(skb_split);
2561 
2562 /* Shifting from/to a cloned skb is a no-go.
2563  *
2564  * Caller cannot keep skb_shinfo related pointers past calling here!
2565  */
2566 static int skb_prepare_for_shift(struct sk_buff *skb)
2567 {
2568         return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2569 }
2570 
2571 /**
2572  * skb_shift - Shifts paged data partially from skb to another
2573  * @tgt: buffer into which tail data gets added
2574  * @skb: buffer from which the paged data comes from
2575  * @shiftlen: shift up to this many bytes
2576  *
2577  * Attempts to shift up to shiftlen worth of bytes, which may be less than
2578  * the length of the skb, from skb to tgt. Returns number bytes shifted.
2579  * It's up to caller to free skb if everything was shifted.
2580  *
2581  * If @tgt runs out of frags, the whole operation is aborted.
2582  *
2583  * Skb cannot include anything else but paged data while tgt is allowed
2584  * to have non-paged data as well.
2585  *
2586  * TODO: full sized shift could be optimized but that would need
2587  * specialized skb free'er to handle frags without up-to-date nr_frags.
2588  */
2589 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2590 {
2591         int from, to, merge, todo;
2592         struct skb_frag_struct *fragfrom, *fragto;
2593 
2594         BUG_ON(shiftlen > skb->len);
2595         BUG_ON(skb_headlen(skb));       /* Would corrupt stream */
2596 
2597         todo = shiftlen;
2598         from = 0;
2599         to = skb_shinfo(tgt)->nr_frags;
2600         fragfrom = &skb_shinfo(skb)->frags[from];
2601 
2602         /* Actual merge is delayed until the point when we know we can
2603          * commit all, so that we don't have to undo partial changes
2604          */
2605         if (!to ||
2606             !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
2607                               fragfrom->page_offset)) {
2608                 merge = -1;
2609         } else {
2610                 merge = to - 1;
2611 
2612                 todo -= skb_frag_size(fragfrom);
2613                 if (todo < 0) {
2614                         if (skb_prepare_for_shift(skb) ||
2615                             skb_prepare_for_shift(tgt))
2616                                 return 0;
2617 
2618                         /* All previous frag pointers might be stale! */
2619                         fragfrom = &skb_shinfo(skb)->frags[from];
2620                         fragto = &skb_shinfo(tgt)->frags[merge];
2621 
2622                         skb_frag_size_add(fragto, shiftlen);
2623                         skb_frag_size_sub(fragfrom, shiftlen);
2624                         fragfrom->page_offset += shiftlen;
2625 
2626                         goto onlymerged;
2627                 }
2628 
2629                 from++;
2630         }
2631 
2632         /* Skip full, not-fitting skb to avoid expensive operations */
2633         if ((shiftlen == skb->len) &&
2634             (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2635                 return 0;
2636 
2637         if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2638                 return 0;
2639 
2640         while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2641                 if (to == MAX_SKB_FRAGS)
2642                         return 0;
2643 
2644                 fragfrom = &skb_shinfo(skb)->frags[from];
2645                 fragto = &skb_shinfo(tgt)->frags[to];
2646 
2647                 if (todo >= skb_frag_size(fragfrom)) {
2648                         *fragto = *fragfrom;
2649                         todo -= skb_frag_size(fragfrom);
2650                         from++;
2651                         to++;
2652 
2653                 } else {
2654                         __skb_frag_ref(fragfrom);
2655                         fragto->page = fragfrom->page;
2656                         fragto->page_offset = fragfrom->page_offset;
2657                         skb_frag_size_set(fragto, todo);
2658 
2659                         fragfrom->page_offset += todo;
2660                         skb_frag_size_sub(fragfrom, todo);
2661                         todo = 0;
2662 
2663                         to++;
2664                         break;
2665                 }
2666         }
2667 
2668         /* Ready to "commit" this state change to tgt */
2669         skb_shinfo(tgt)->nr_frags = to;
2670 
2671         if (merge >= 0) {
2672                 fragfrom = &skb_shinfo(skb)->frags[0];
2673                 fragto = &skb_shinfo(tgt)->frags[merge];
2674 
2675                 skb_frag_size_add(fragto, skb_frag_size(fragfrom));
2676                 __skb_frag_unref(fragfrom);
2677         }
2678 
2679         /* Reposition in the original skb */
2680         to = 0;
2681         while (from < skb_shinfo(skb)->nr_frags)
2682                 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2683         skb_shinfo(skb)->nr_frags = to;
2684 
2685         BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2686 
2687 onlymerged:
2688         /* Most likely the tgt won't ever need its checksum anymore, skb on
2689          * the other hand might need it if it needs to be resent
2690          */
2691         tgt->ip_summed = CHECKSUM_PARTIAL;
2692         skb->ip_summed = CHECKSUM_PARTIAL;
2693 
2694         /* Yak, is it really working this way? Some helper please? */
2695         skb->len -= shiftlen;
2696         skb->data_len -= shiftlen;
2697         skb->truesize -= shiftlen;
2698         tgt->len += shiftlen;
2699         tgt->data_len += shiftlen;
2700         tgt->truesize += shiftlen;
2701 
2702         return shiftlen;
2703 }
2704 
2705 /**
2706  * skb_prepare_seq_read - Prepare a sequential read of skb data
2707  * @skb: the buffer to read
2708  * @from: lower offset of data to be read
2709  * @to: upper offset of data to be read
2710  * @st: state variable
2711  *
2712  * Initializes the specified state variable. Must be called before
2713  * invoking skb_seq_read() for the first time.
2714  */
2715 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2716                           unsigned int to, struct skb_seq_state *st)
2717 {
2718         st->lower_offset = from;
2719         st->upper_offset = to;
2720         st->root_skb = st->cur_skb = skb;
2721         st->frag_idx = st->stepped_offset = 0;
2722         st->frag_data = NULL;
2723 }
2724 EXPORT_SYMBOL(skb_prepare_seq_read);
2725 
2726 /**
2727  * skb_seq_read - Sequentially read skb data
2728  * @consumed: number of bytes consumed by the caller so far
2729  * @data: destination pointer for data to be returned
2730  * @st: state variable
2731  *
2732  * Reads a block of skb data at @consumed relative to the
2733  * lower offset specified to skb_prepare_seq_read(). Assigns
2734  * the head of the data block to @data and returns the length
2735  * of the block or 0 if the end of the skb data or the upper
2736  * offset has been reached.
2737  *
2738  * The caller is not required to consume all of the data
2739  * returned, i.e. @consumed is typically set to the number
2740  * of bytes already consumed and the next call to
2741  * skb_seq_read() will return the remaining part of the block.
2742  *
2743  * Note 1: The size of each block of data returned can be arbitrary,
2744  *       this limitation is the cost for zerocopy sequential
2745  *       reads of potentially non linear data.
2746  *
2747  * Note 2: Fragment lists within fragments are not implemented
2748  *       at the moment, state->root_skb could be replaced with
2749  *       a stack for this purpose.
2750  */
2751 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2752                           struct skb_seq_state *st)
2753 {
2754         unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2755         skb_frag_t *frag;
2756 
2757         if (unlikely(abs_offset >= st->upper_offset)) {
2758                 if (st->frag_data) {
2759                         kunmap_atomic(st->frag_data);
2760                         st->frag_data = NULL;
2761                 }
2762                 return 0;
2763         }
2764 
2765 next_skb:
2766         block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2767 
2768         if (abs_offset < block_limit && !st->frag_data) {
2769                 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2770                 return block_limit - abs_offset;
2771         }
2772 
2773         if (st->frag_idx == 0 && !st->frag_data)
2774                 st->stepped_offset += skb_headlen(st->cur_skb);
2775 
2776         while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2777                 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2778                 block_limit = skb_frag_size(frag) + st->stepped_offset;
2779 
2780                 if (abs_offset < block_limit) {
2781                         if (!st->frag_data)
2782                                 st->frag_data = kmap_atomic(skb_frag_page(frag));
2783 
2784                         *data = (u8 *) st->frag_data + frag->page_offset +
2785                                 (abs_offset - st->stepped_offset);
2786 
2787                         return block_limit - abs_offset;
2788                 }
2789 
2790                 if (st->frag_data) {
2791                         kunmap_atomic(st->frag_data);
2792                         st->frag_data = NULL;
2793                 }
2794 
2795                 st->frag_idx++;
2796                 st->stepped_offset += skb_frag_size(frag);
2797         }
2798 
2799         if (st->frag_data) {
2800                 kunmap_atomic(st->frag_data);
2801                 st->frag_data = NULL;
2802         }
2803 
2804         if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
2805                 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2806                 st->frag_idx = 0;
2807                 goto next_skb;
2808         } else if (st->cur_skb->next) {
2809                 st->cur_skb = st->cur_skb->next;
2810                 st->frag_idx = 0;
2811                 goto next_skb;
2812         }
2813 
2814         return 0;
2815 }
2816 EXPORT_SYMBOL(skb_seq_read);
2817 
2818 /**
2819  * skb_abort_seq_read - Abort a sequential read of skb data
2820  * @st: state variable
2821  *
2822  * Must be called if skb_seq_read() was not called until it
2823  * returned 0.
2824  */
2825 void skb_abort_seq_read(struct skb_seq_state *st)
2826 {
2827         if (st->frag_data)
2828                 kunmap_atomic(st->frag_data);
2829 }
2830 EXPORT_SYMBOL(skb_abort_seq_read);
2831 
2832 #define TS_SKB_CB(state)        ((struct skb_seq_state *) &((state)->cb))
2833 
2834 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2835                                           struct ts_config *conf,
2836                                           struct ts_state *state)
2837 {
2838         return skb_seq_read(offset, text, TS_SKB_CB(state));
2839 }
2840 
2841 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2842 {
2843         skb_abort_seq_read(TS_SKB_CB(state));
2844 }
2845 
2846 /**
2847  * skb_find_text - Find a text pattern in skb data
2848  * @skb: the buffer to look in
2849  * @from: search offset
2850  * @to: search limit
2851  * @config: textsearch configuration
2852  *
2853  * Finds a pattern in the skb data according to the specified
2854  * textsearch configuration. Use textsearch_next() to retrieve
2855  * subsequent occurrences of the pattern. Returns the offset
2856  * to the first occurrence or UINT_MAX if no match was found.
2857  */
2858 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2859                            unsigned int to, struct ts_config *config)
2860 {
2861         struct ts_state state;
2862         unsigned int ret;
2863 
2864         config->get_next_block = skb_ts_get_next_block;
2865         config->finish = skb_ts_finish;
2866 
2867         skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
2868 
2869         ret = textsearch_find(config, &state);
2870         return (ret <= to - from ? ret : UINT_MAX);
2871 }
2872 EXPORT_SYMBOL(skb_find_text);
2873 
2874 /**
2875  * skb_append_datato_frags - append the user data to a skb
2876  * @sk: sock  structure
2877  * @skb: skb structure to be appended with user data.
2878  * @getfrag: call back function to be used for getting the user data
2879  * @from: pointer to user message iov
2880  * @length: length of the iov message
2881  *
2882  * Description: This procedure append the user data in the fragment part
2883  * of the skb if any page alloc fails user this procedure returns  -ENOMEM
2884  */
2885 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2886                         int (*getfrag)(void *from, char *to, int offset,
2887                                         int len, int odd, struct sk_buff *skb),
2888                         void *from, int length)
2889 {
2890         int frg_cnt = skb_shinfo(skb)->nr_frags;
2891         int copy;
2892         int offset = 0;
2893         int ret;
2894         struct page_frag *pfrag = &current->task_frag;
2895 
2896         do {
2897                 /* Return error if we don't have space for new frag */
2898                 if (frg_cnt >= MAX_SKB_FRAGS)
2899                         return -EMSGSIZE;
2900 
2901                 if (!sk_page_frag_refill(sk, pfrag))
2902                         return -ENOMEM;
2903 
2904                 /* copy the user data to page */
2905                 copy = min_t(int, length, pfrag->size - pfrag->offset);
2906 
2907                 ret = getfrag(from, page_address(pfrag->page) + pfrag->offset,
2908                               offset, copy, 0, skb);
2909                 if (ret < 0)
2910                         return -EFAULT;
2911 
2912                 /* copy was successful so update the size parameters */
2913                 skb_fill_page_desc(skb, frg_cnt, pfrag->page, pfrag->offset,
2914                                    copy);
2915                 frg_cnt++;
2916                 pfrag->offset += copy;
2917                 get_page(pfrag->page);
2918 
2919                 skb->truesize += copy;
2920                 atomic_add(copy, &sk->sk_wmem_alloc);
2921                 skb->len += copy;
2922                 skb->data_len += copy;
2923                 offset += copy;
2924                 length -= copy;
2925 
2926         } while (length > 0);
2927 
2928         return 0;
2929 }
2930 EXPORT_SYMBOL(skb_append_datato_frags);
2931 
2932 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
2933                          int offset, size_t size)
2934 {
2935         int i = skb_shinfo(skb)->nr_frags;
2936 
2937         if (skb_can_coalesce(skb, i, page, offset)) {
2938                 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
2939         } else if (i < MAX_SKB_FRAGS) {
2940                 get_page(page);
2941                 skb_fill_page_desc(skb, i, page, offset, size);
2942         } else {
2943                 return -EMSGSIZE;
2944         }
2945 
2946         return 0;
2947 }
2948 EXPORT_SYMBOL_GPL(skb_append_pagefrags);
2949 
2950 /**
2951  *      skb_push_rcsum - push skb and update receive checksum
2952  *      @skb: buffer to update
2953  *      @len: length of data pulled
2954  *
2955  *      This function performs an skb_push on the packet and updates
2956  *      the CHECKSUM_COMPLETE checksum.  It should be used on
2957  *      receive path processing instead of skb_push unless you know
2958  *      that the checksum difference is zero (e.g., a valid IP header)
2959  *      or you are setting ip_summed to CHECKSUM_NONE.
2960  */
2961 static unsigned char *skb_push_rcsum(struct sk_buff *skb, unsigned len)
2962 {
2963         skb_push(skb, len);
2964         skb_postpush_rcsum(skb, skb->data, len);
2965         return skb->data;
2966 }
2967 
2968 /**
2969  *      skb_pull_rcsum - pull skb and update receive checksum
2970  *      @skb: buffer to update
2971  *      @len: length of data pulled
2972  *
2973  *      This function performs an skb_pull on the packet and updates
2974  *      the CHECKSUM_COMPLETE checksum.  It should be used on
2975  *      receive path processing instead of skb_pull unless you know
2976  *      that the checksum difference is zero (e.g., a valid IP header)
2977  *      or you are setting ip_summed to CHECKSUM_NONE.
2978  */
2979 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
2980 {
2981         unsigned char *data = skb->data;
2982 
2983         BUG_ON(len > skb->len);
2984         __skb_pull(skb, len);
2985         skb_postpull_rcsum(skb, data, len);
2986         return skb->data;
2987 }
2988 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
2989 
2990 /**
2991  *      skb_segment - Perform protocol segmentation on skb.
2992  *      @head_skb: buffer to segment
2993  *      @features: features for the output path (see dev->features)
2994  *
2995  *      This function performs segmentation on the given skb.  It returns
2996  *      a pointer to the first in a list of new skbs for the segments.
2997  *      In case of error it returns ERR_PTR(err).
2998  */
2999 struct sk_buff *skb_segment(struct sk_buff *head_skb,
3000                             netdev_features_t features)
3001 {
3002         struct sk_buff *segs = NULL;
3003         struct sk_buff *tail = NULL;
3004         struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
3005         skb_frag_t *frag = skb_shinfo(head_skb)->frags;
3006         unsigned int mss = skb_shinfo(head_skb)->gso_size;
3007         unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
3008         struct sk_buff *frag_skb = head_skb;
3009         unsigned int offset = doffset;
3010         unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
3011         unsigned int headroom;
3012         unsigned int len;
3013         __be16 proto;
3014         bool csum;
3015         int sg = !!(features & NETIF_F_SG);
3016         int nfrags = skb_shinfo(head_skb)->nr_frags;
3017         int err = -ENOMEM;
3018         int i = 0;
3019         int pos;
3020         int dummy;
3021 
3022         __skb_push(head_skb, doffset);
3023         proto = skb_network_protocol(head_skb, &dummy);
3024         if (unlikely(!proto))
3025                 return ERR_PTR(-EINVAL);
3026 
3027         csum = !head_skb->encap_hdr_csum &&
3028             !!can_checksum_protocol(features, proto);
3029 
3030         headroom = skb_headroom(head_skb);
3031         pos = skb_headlen(head_skb);
3032 
3033         do {
3034                 struct sk_buff *nskb;
3035                 skb_frag_t *nskb_frag;
3036                 int hsize;
3037                 int size;
3038 
3039                 len = head_skb->len - offset;
3040                 if (len > mss)
3041                         len = mss;
3042 
3043                 hsize = skb_headlen(head_skb) - offset;
3044                 if (hsize < 0)
3045                         hsize = 0;
3046                 if (hsize > len || !sg)
3047                         hsize = len;
3048 
3049                 if (!hsize && i >= nfrags && skb_headlen(list_skb) &&
3050                     (skb_headlen(list_skb) == len || sg)) {
3051                         BUG_ON(skb_headlen(list_skb) > len);
3052 
3053                         i = 0;
3054                         nfrags = skb_shinfo(list_skb)->nr_frags;
3055                         frag = skb_shinfo(list_skb)->frags;
3056                         frag_skb = list_skb;
3057                         pos += skb_headlen(list_skb);
3058 
3059                         while (pos < offset + len) {
3060                                 BUG_ON(i >= nfrags);
3061 
3062                                 size = skb_frag_size(frag);
3063                                 if (pos + size > offset + len)
3064                                         break;
3065 
3066                                 i++;
3067                                 pos += size;
3068                                 frag++;
3069                         }
3070 
3071                         nskb = skb_clone(list_skb, GFP_ATOMIC);
3072                         list_skb = list_skb->next;
3073 
3074                         if (unlikely(!nskb))
3075                                 goto err;
3076 
3077                         if (unlikely(pskb_trim(nskb, len))) {
3078                                 kfree_skb(nskb);
3079                                 goto err;
3080                         }
3081 
3082                         hsize = skb_end_offset(nskb);
3083                         if (skb_cow_head(nskb, doffset + headroom)) {
3084                                 kfree_skb(nskb);
3085                                 goto err;
3086                         }
3087 
3088                         nskb->truesize += skb_end_offset(nskb) - hsize;
3089                         skb_release_head_state(nskb);
3090                         __skb_push(nskb, doffset);
3091                 } else {
3092                         nskb = __alloc_skb(hsize + doffset + headroom,
3093                                            GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
3094                                            NUMA_NO_NODE);
3095 
3096                         if (unlikely(!nskb))
3097                                 goto err;
3098 
3099                         skb_reserve(nskb, headroom);
3100                         __skb_put(nskb, doffset);
3101                 }
3102 
3103                 if (segs)
3104                         tail->next = nskb;
3105                 else
3106                         segs = nskb;
3107                 tail = nskb;
3108 
3109                 __copy_skb_header(nskb, head_skb);
3110 
3111                 skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
3112                 skb_reset_mac_len(nskb);
3113 
3114                 skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
3115                                                  nskb->data - tnl_hlen,
3116                                                  doffset + tnl_hlen);
3117 
3118                 if (nskb->len == len + doffset)
3119                         goto perform_csum_check;
3120 
3121                 if (!sg && !nskb->remcsum_offload) {
3122                         nskb->ip_summed = CHECKSUM_NONE;
3123                         nskb->csum = skb_copy_and_csum_bits(head_skb, offset,
3124                                                             skb_put(nskb, len),
3125                                                             len, 0);
3126                         SKB_GSO_CB(nskb)->csum_start =
3127                             skb_headroom(nskb) + doffset;
3128                         continue;
3129                 }
3130 
3131                 nskb_frag = skb_shinfo(nskb)->frags;
3132 
3133                 skb_copy_from_linear_data_offset(head_skb, offset,
3134                                                  skb_put(nskb, hsize), hsize);
3135 
3136                 skb_shinfo(nskb)->tx_flags = skb_shinfo(head_skb)->tx_flags &
3137                         SKBTX_SHARED_FRAG;
3138 
3139                 while (pos < offset + len) {
3140                         if (i >= nfrags) {
3141                                 BUG_ON(skb_headlen(list_skb));
3142 
3143                                 i = 0;
3144                                 nfrags = skb_shinfo(list_skb)->nr_frags;
3145                                 frag = skb_shinfo(list_skb)->frags;
3146                                 frag_skb = list_skb;
3147 
3148                                 BUG_ON(!nfrags);
3149 
3150                                 list_skb = list_skb->next;
3151                         }
3152 
3153                         if (unlikely(skb_shinfo(nskb)->nr_frags >=
3154                                      MAX_SKB_FRAGS)) {
3155                                 net_warn_ratelimited(
3156                                         "skb_segment: too many frags: %u %u\n",
3157                                         pos, mss);
3158                                 goto err;
3159                         }
3160 
3161                         if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC)))
3162                                 goto err;
3163 
3164                         *nskb_frag = *frag;
3165                         __skb_frag_ref(nskb_frag);
3166                         size = skb_frag_size(nskb_frag);
3167 
3168                         if (pos < offset) {
3169                                 nskb_frag->page_offset += offset - pos;
3170                                 skb_frag_size_sub(nskb_frag, offset - pos);
3171                         }
3172 
3173                         skb_shinfo(nskb)->nr_frags++;
3174 
3175                         if (pos + size <= offset + len) {
3176                                 i++;
3177                                 frag++;
3178                                 pos += size;
3179                         } else {
3180                                 skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
3181                                 goto skip_fraglist;
3182                         }
3183 
3184                         nskb_frag++;
3185                 }
3186 
3187 skip_fraglist:
3188                 nskb->data_len = len - hsize;
3189                 nskb->len += nskb->data_len;
3190                 nskb->truesize += nskb->data_len;
3191 
3192 perform_csum_check:
3193                 if (!csum && !nskb->remcsum_offload) {
3194                         nskb->csum = skb_checksum(nskb, doffset,
3195                                                   nskb->len - doffset, 0);
3196                         nskb->ip_summed = CHECKSUM_NONE;
3197                         SKB_GSO_CB(nskb)->csum_start =
3198                             skb_headroom(nskb) + doffset;
3199                 }
3200         } while ((offset += len) < head_skb->len);
3201 
3202         /* Some callers want to get the end of the list.
3203          * Put it in segs->prev to avoid walking the list.
3204          * (see validate_xmit_skb_list() for example)
3205          */
3206         segs->prev = tail;
3207 
3208         /* Following permits correct backpressure, for protocols
3209          * using skb_set_owner_w().
3210          * Idea is to tranfert ownership from head_skb to last segment.
3211          */
3212         if (head_skb->destructor == sock_wfree) {
3213                 swap(tail->truesize, head_skb->truesize);
3214                 swap(tail->destructor, head_skb->destructor);
3215                 swap(tail->sk, head_skb->sk);
3216         }
3217         return segs;
3218 
3219 err:
3220         kfree_skb_list(segs);
3221         return ERR_PTR(err);
3222 }
3223 EXPORT_SYMBOL_GPL(skb_segment);
3224 
3225 int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
3226 {
3227         struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
3228         unsigned int offset = skb_gro_offset(skb);
3229         unsigned int headlen = skb_headlen(skb);
3230         unsigned int len = skb_gro_len(skb);
3231         struct sk_buff *lp, *p = *head;
3232         unsigned int delta_truesize;
3233 
3234         if (unlikely(p->len + len >= 65536))
3235                 return -E2BIG;
3236 
3237         lp = NAPI_GRO_CB(p)->last;
3238         pinfo = skb_shinfo(lp);
3239 
3240         if (headlen <= offset) {
3241                 skb_frag_t *frag;
3242                 skb_frag_t *frag2;
3243                 int i = skbinfo->nr_frags;
3244                 int nr_frags = pinfo->nr_frags + i;
3245 
3246                 if (nr_frags > MAX_SKB_FRAGS)
3247                         goto merge;
3248 
3249                 offset -= headlen;
3250                 pinfo->nr_frags = nr_frags;
3251                 skbinfo->nr_frags = 0;
3252 
3253                 frag = pinfo->frags + nr_frags;
3254                 frag2 = skbinfo->frags + i;
3255                 do {
3256                         *--frag = *--frag2;
3257                 } while (--i);
3258 
3259                 frag->page_offset += offset;
3260                 skb_frag_size_sub(frag, offset);
3261 
3262                 /* all fragments truesize : remove (head size + sk_buff) */
3263                 delta_truesize = skb->truesize -
3264                                  SKB_TRUESIZE(skb_end_offset(skb));
3265 
3266                 skb->truesize -= skb->data_len;
3267                 skb->len -= skb->data_len;
3268                 skb->data_len = 0;
3269 
3270                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
3271                 goto done;
3272         } else if (skb->head_frag) {
3273                 int nr_frags = pinfo->nr_frags;
3274                 skb_frag_t *frag = pinfo->frags + nr_frags;
3275                 struct page *page = virt_to_head_page(skb->head);
3276                 unsigned int first_size = headlen - offset;
3277                 unsigned int first_offset;
3278 
3279                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
3280                         goto merge;
3281 
3282                 first_offset = skb->data -
3283                                (unsigned char *)page_address(page) +
3284                                offset;
3285 
3286                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
3287 
3288                 frag->page.p      = page;
3289                 frag->page_offset = first_offset;
3290                 skb_frag_size_set(frag, first_size);
3291 
3292                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
3293                 /* We dont need to clear skbinfo->nr_frags here */
3294 
3295                 delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
3296                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
3297                 goto done;
3298         }
3299 
3300 merge:
3301         delta_truesize = skb->truesize;
3302         if (offset > headlen) {
3303                 unsigned int eat = offset - headlen;
3304 
3305                 skbinfo->frags[0].page_offset += eat;
3306                 skb_frag_size_sub(&skbinfo->frags[0], eat);
3307                 skb->data_len -= eat;
3308                 skb->len -= eat;
3309                 offset = headlen;
3310         }
3311 
3312         __skb_pull(skb, offset);
3313 
3314         if (NAPI_GRO_CB(p)->last == p)
3315                 skb_shinfo(p)->frag_list = skb;
3316         else
3317                 NAPI_GRO_CB(p)->last->next = skb;
3318         NAPI_GRO_CB(p)->last = skb;
3319         __skb_header_release(skb);
3320         lp = p;
3321 
3322 done:
3323         NAPI_GRO_CB(p)->count++;
3324         p->data_len += len;
3325         p->truesize += delta_truesize;
3326         p->len += len;
3327         if (lp != p) {
3328                 lp->data_len += len;
3329                 lp->truesize += delta_truesize;
3330                 lp->len += len;
3331         }
3332         NAPI_GRO_CB(skb)->same_flow = 1;
3333         return 0;
3334 }
3335 
3336 void __init skb_init(void)
3337 {
3338         skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
3339                                               sizeof(struct sk_buff),
3340                                               0,
3341                                               SLAB_HWCACHE_ALIGN|SLAB_PANIC,
3342                                               NULL);
3343         skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
3344                                                 sizeof(struct sk_buff_fclones),
3345                                                 0,
3346                                                 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
3347                                                 NULL);
3348 }
3349 
3350 /**
3351  *      skb_to_sgvec - Fill a scatter-gather list from a socket buffer
3352  *      @skb: Socket buffer containing the buffers to be mapped
3353  *      @sg: The scatter-gather list to map into
3354  *      @offset: The offset into the buffer's contents to start mapping
3355  *      @len: Length of buffer space to be mapped
3356  *
3357  *      Fill the specified scatter-gather list with mappings/pointers into a
3358  *      region of the buffer space attached to a socket buffer.
3359  */
3360 static int
3361 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3362 {
3363         int start = skb_headlen(skb);
3364         int i, copy = start - offset;
3365         struct sk_buff *frag_iter;
3366         int elt = 0;
3367 
3368         if (copy > 0) {
3369                 if (copy > len)
3370                         copy = len;
3371                 sg_set_buf(sg, skb->data + offset, copy);
3372                 elt++;
3373                 if ((len -= copy) == 0)
3374                         return elt;
3375                 offset += copy;
3376         }
3377 
3378         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3379                 int end;
3380 
3381                 WARN_ON(start > offset + len);
3382 
3383                 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3384                 if ((copy = end - offset) > 0) {
3385                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3386 
3387                         if (copy > len)
3388                                 copy = len;
3389                         sg_set_page(&sg[elt], skb_frag_page(frag), copy,
3390                                         frag->page_offset+offset-start);
3391                         elt++;
3392                         if (!(len -= copy))
3393                                 return elt;
3394                         offset += copy;
3395                 }
3396                 start = end;
3397         }
3398 
3399         skb_walk_frags(skb, frag_iter) {
3400                 int end;
3401 
3402                 WARN_ON(start > offset + len);
3403 
3404                 end = start + frag_iter->len;
3405                 if ((copy = end - offset) > 0) {
3406                         if (copy > len)
3407                                 copy = len;
3408                         elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
3409                                               copy);
3410                         if ((len -= copy) == 0)
3411                                 return elt;
3412                         offset += copy;
3413                 }
3414                 start = end;
3415         }
3416         BUG_ON(len);
3417         return elt;
3418 }
3419 
3420 /* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
3421  * sglist without mark the sg which contain last skb data as the end.
3422  * So the caller can mannipulate sg list as will when padding new data after
3423  * the first call without calling sg_unmark_end to expend sg list.
3424  *
3425  * Scenario to use skb_to_sgvec_nomark:
3426  * 1. sg_init_table
3427  * 2. skb_to_sgvec_nomark(payload1)
3428  * 3. skb_to_sgvec_nomark(payload2)
3429  *
3430  * This is equivalent to:
3431  * 1. sg_init_table
3432  * 2. skb_to_sgvec(payload1)
3433  * 3. sg_unmark_end
3434  * 4. skb_to_sgvec(payload2)
3435  *
3436  * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
3437  * is more preferable.
3438  */
3439 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
3440                         int offset, int len)
3441 {
3442         return __skb_to_sgvec(skb, sg, offset, len);
3443 }
3444 EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
3445 
3446 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3447 {
3448         int nsg = __skb_to_sgvec(skb, sg, offset, len);
3449 
3450         sg_mark_end(&sg[nsg - 1]);
3451 
3452         return nsg;
3453 }
3454 EXPORT_SYMBOL_GPL(skb_to_sgvec);
3455 
3456 /**
3457  *      skb_cow_data - Check that a socket buffer's data buffers are writable
3458  *      @skb: The socket buffer to check.
3459  *      @tailbits: Amount of trailing space to be added
3460  *      @trailer: Returned pointer to the skb where the @tailbits space begins
3461  *
3462  *      Make sure that the data buffers attached to a socket buffer are
3463  *      writable. If they are not, private copies are made of the data buffers
3464  *      and the socket buffer is set to use these instead.
3465  *
3466  *      If @tailbits is given, make sure that there is space to write @tailbits
3467  *      bytes of data beyond current end of socket buffer.  @trailer will be
3468  *      set to point to the skb in which this space begins.
3469  *
3470  *      The number of scatterlist elements required to completely map the
3471  *      COW'd and extended socket buffer will be returned.
3472  */
3473 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
3474 {
3475         int copyflag;
3476         int elt;
3477         struct sk_buff *skb1, **skb_p;
3478 
3479         /* If skb is cloned or its head is paged, reallocate
3480          * head pulling out all the pages (pages are considered not writable
3481          * at the moment even if they are anonymous).
3482          */
3483         if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
3484             __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
3485                 return -ENOMEM;
3486 
3487         /* Easy case. Most of packets will go this way. */
3488         if (!skb_has_frag_list(skb)) {
3489                 /* A little of trouble, not enough of space for trailer.
3490                  * This should not happen, when stack is tuned to generate
3491                  * good frames. OK, on miss we reallocate and reserve even more
3492                  * space, 128 bytes is fair. */
3493 
3494                 if (skb_tailroom(skb) < tailbits &&
3495                     pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
3496                         return -ENOMEM;
3497 
3498                 /* Voila! */
3499                 *trailer = skb;
3500                 return 1;
3501         }
3502 
3503         /* Misery. We are in troubles, going to mincer fragments... */
3504 
3505         elt = 1;
3506         skb_p = &skb_shinfo(skb)->frag_list;
3507         copyflag = 0;
3508 
3509         while ((skb1 = *skb_p) != NULL) {
3510                 int ntail = 0;
3511 
3512                 /* The fragment is partially pulled by someone,
3513                  * this can happen on input. Copy it and everything
3514                  * after it. */
3515 
3516                 if (skb_shared(skb1))
3517                         copyflag = 1;
3518 
3519                 /* If the skb is the last, worry about trailer. */
3520 
3521                 if (skb1->next == NULL && tailbits) {
3522                         if (skb_shinfo(skb1)->nr_frags ||
3523                             skb_has_frag_list(skb1) ||
3524                             skb_tailroom(skb1) < tailbits)
3525                                 ntail = tailbits + 128;
3526                 }
3527 
3528                 if (copyflag ||
3529                     skb_cloned(skb1) ||
3530                     ntail ||
3531                     skb_shinfo(skb1)->nr_frags ||
3532                     skb_has_frag_list(skb1)) {
3533                         struct sk_buff *skb2;
3534 
3535                         /* Fuck, we are miserable poor guys... */
3536                         if (ntail == 0)
3537                                 skb2 = skb_copy(skb1, GFP_ATOMIC);
3538                         else
3539                                 skb2 = skb_copy_expand(skb1,
3540                                                        skb_headroom(skb1),
3541                                                        ntail,
3542                                                        GFP_ATOMIC);
3543                         if (unlikely(skb2 == NULL))
3544                                 return -ENOMEM;
3545 
3546                         if (skb1->sk)
3547                                 skb_set_owner_w(skb2, skb1->sk);
3548 
3549                         /* Looking around. Are we still alive?
3550                          * OK, link new skb, drop old one */
3551 
3552                         skb2->next = skb1->next;
3553                         *skb_p = skb2;
3554                         kfree_skb(skb1);
3555                         skb1 = skb2;
3556                 }
3557                 elt++;
3558                 *trailer = skb1;
3559                 skb_p = &skb1->next;
3560         }
3561 
3562         return elt;
3563 }
3564 EXPORT_SYMBOL_GPL(skb_cow_data);
3565 
3566 static void sock_rmem_free(struct sk_buff *skb)
3567 {
3568         struct sock *sk = skb->sk;
3569 
3570         atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
3571 }
3572 
3573 /*
3574  * Note: We dont mem charge error packets (no sk_forward_alloc changes)
3575  */
3576 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
3577 {
3578         if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
3579             (unsigned int)sk->sk_rcvbuf)
3580                 return -ENOMEM;
3581 
3582         skb_orphan(skb);
3583         skb->sk = sk;
3584         skb->destructor = sock_rmem_free;
3585         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
3586 
3587         /* before exiting rcu section, make sure dst is refcounted */
3588         skb_dst_force(skb);
3589 
3590         skb_queue_tail(&sk->sk_error_queue, skb);
3591         if (!sock_flag(sk, SOCK_DEAD))
3592                 sk->sk_data_ready(sk);
3593         return 0;
3594 }
3595 EXPORT_SYMBOL(sock_queue_err_skb);
3596 
3597 struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
3598 {
3599         struct sk_buff_head *q = &sk->sk_error_queue;
3600         struct sk_buff *skb, *skb_next;
3601         unsigned long flags;
3602         int err = 0;
3603 
3604         spin_lock_irqsave(&q->lock, flags);
3605         skb = __skb_dequeue(q);
3606         if (skb && (skb_next = skb_peek(q)))
3607                 err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
3608         spin_unlock_irqrestore(&q->lock, flags);
3609 
3610         sk->sk_err = err;
3611         if (err)
3612                 sk->sk_error_report(sk);
3613 
3614         return skb;
3615 }
3616 EXPORT_SYMBOL(sock_dequeue_err_skb);
3617 
3618 /**
3619  * skb_clone_sk - create clone of skb, and take reference to socket
3620  * @skb: the skb to clone
3621  *
3622  * This function creates a clone of a buffer that holds a reference on
3623  * sk_refcnt.  Buffers created via this function are meant to be
3624  * returned using sock_queue_err_skb, or free via kfree_skb.
3625  *
3626  * When passing buffers allocated with this function to sock_queue_err_skb
3627  * it is necessary to wrap the call with sock_hold/sock_put in order to
3628  * prevent the socket from being released prior to being enqueued on
3629  * the sk_error_queue.
3630  */
3631 struct sk_buff *skb_clone_sk(struct sk_buff *skb)
3632 {
3633         struct sock *sk = skb->sk;
3634         struct sk_buff *clone;
3635 
3636         if (!sk || !atomic_inc_not_zero(&sk->sk_refcnt))
3637                 return NULL;
3638 
3639         clone = skb_clone(skb, GFP_ATOMIC);
3640         if (!clone) {
3641                 sock_put(sk);
3642                 return NULL;
3643         }
3644 
3645         clone->sk = sk;
3646         clone->destructor = sock_efree;
3647 
3648         return clone;
3649 }
3650 EXPORT_SYMBOL(skb_clone_sk);
3651 
3652 static void __skb_complete_tx_timestamp(struct sk_buff *skb,
3653                                         struct sock *sk,
3654                                         int tstype)
3655 {
3656         struct sock_exterr_skb *serr;
3657         int err;
3658 
3659         serr = SKB_EXT_ERR(skb);
3660         memset(serr, 0, sizeof(*serr));
3661         serr->ee.ee_errno = ENOMSG;
3662         serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3663         serr->ee.ee_info = tstype;
3664         if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) {
3665                 serr->ee.ee_data = skb_shinfo(skb)->tskey;
3666                 if (sk->sk_protocol == IPPROTO_TCP &&
3667                     sk->sk_type == SOCK_STREAM)
3668                         serr->ee.ee_data -= sk->sk_tskey;
3669         }
3670 
3671         err = sock_queue_err_skb(sk, skb);
3672 
3673         if (err)
3674                 kfree_skb(skb);
3675 }
3676 
3677 static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
3678 {
3679         bool ret;
3680 
3681         if (likely(sysctl_tstamp_allow_data || tsonly))
3682                 return true;
3683 
3684         read_lock_bh(&sk->sk_callback_lock);
3685         ret = sk->sk_socket && sk->sk_socket->file &&
3686               file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
3687         read_unlock_bh(&sk->sk_callback_lock);
3688         return ret;
3689 }
3690 
3691 void skb_complete_tx_timestamp(struct sk_buff *skb,
3692                                struct skb_shared_hwtstamps *hwtstamps)
3693 {
3694         struct sock *sk = skb->sk;
3695 
3696         if (!skb_may_tx_timestamp(sk, false))
3697                 return;
3698 
3699         /* take a reference to prevent skb_orphan() from freeing the socket */
3700         sock_hold(sk);
3701 
3702         *skb_hwtstamps(skb) = *hwtstamps;
3703         __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
3704 
3705         sock_put(sk);
3706 }
3707 EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
3708 
3709 void __skb_tstamp_tx(struct sk_buff *orig_skb,
3710                      struct skb_shared_hwtstamps *hwtstamps,
3711                      struct sock *sk, int tstype)
3712 {
3713         struct sk_buff *skb;
3714         bool tsonly;
3715 
3716         if (!sk)
3717                 return;
3718 
3719         tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
3720         if (!skb_may_tx_timestamp(sk, tsonly))
3721                 return;
3722 
3723         if (tsonly)
3724                 skb = alloc_skb(0, GFP_ATOMIC);
3725         else
3726                 skb = skb_clone(orig_skb, GFP_ATOMIC);
3727         if (!skb)
3728                 return;
3729 
3730         if (tsonly) {
3731                 skb_shinfo(skb)->tx_flags = skb_shinfo(orig_skb)->tx_flags;
3732                 skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
3733         }
3734 
3735         if (hwtstamps)
3736                 *skb_hwtstamps(skb) = *hwtstamps;
3737         else
3738                 skb->tstamp = ktime_get_real();
3739 
3740         __skb_complete_tx_timestamp(skb, sk, tstype);
3741 }
3742 EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
3743 
3744 void skb_tstamp_tx(struct sk_buff *orig_skb,
3745                    struct skb_shared_hwtstamps *hwtstamps)
3746 {
3747         return __skb_tstamp_tx(orig_skb, hwtstamps, orig_skb->sk,
3748                                SCM_TSTAMP_SND);
3749 }
3750 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3751 
3752 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
3753 {
3754         struct sock *sk = skb->sk;
3755         struct sock_exterr_skb *serr;
3756         int err;
3757 
3758         skb->wifi_acked_valid = 1;
3759         skb->wifi_acked = acked;
3760 
3761         serr = SKB_EXT_ERR(skb);
3762         memset(serr, 0, sizeof(*serr));
3763         serr->ee.ee_errno = ENOMSG;
3764         serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
3765 
3766         /* take a reference to prevent skb_orphan() from freeing the socket */
3767         sock_hold(sk);
3768 
3769         err = sock_queue_err_skb(sk, skb);
3770         if (err)
3771                 kfree_skb(skb);
3772 
3773         sock_put(sk);
3774 }
3775 EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
3776 
3777 /**
3778  * skb_partial_csum_set - set up and verify partial csum values for packet
3779  * @skb: the skb to set
3780  * @start: the number of bytes after skb->data to start checksumming.
3781  * @off: the offset from start to place the checksum.
3782  *
3783  * For untrusted partially-checksummed packets, we need to make sure the values
3784  * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3785  *
3786  * This function checks and sets those values and skb->ip_summed: if this
3787  * returns false you should drop the packet.
3788  */
3789 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3790 {
3791         if (unlikely(start > skb_headlen(skb)) ||
3792             unlikely((int)start + off > skb_headlen(skb) - 2)) {
3793                 net_warn_ratelimited("bad partial csum: csum=%u/%u len=%u\n",
3794                                      start, off, skb_headlen(skb));
3795                 return false;
3796         }
3797         skb->ip_summed = CHECKSUM_PARTIAL;
3798         skb->csum_start = skb_headroom(skb) + start;
3799         skb->csum_offset = off;
3800         skb_set_transport_header(skb, start);
3801         return true;
3802 }
3803 EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3804 
3805 static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
3806                                unsigned int max)
3807 {
3808         if (skb_headlen(skb) >= len)
3809                 return 0;
3810 
3811         /* If we need to pullup then pullup to the max, so we
3812          * won't need to do it again.
3813          */
3814         if (max > skb->len)
3815                 max = skb->len;
3816 
3817         if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
3818                 return -ENOMEM;
3819 
3820         if (skb_headlen(skb) < len)
3821                 return -EPROTO;
3822 
3823         return 0;
3824 }
3825 
3826 #define MAX_TCP_HDR_LEN (15 * 4)
3827 
3828 static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
3829                                       typeof(IPPROTO_IP) proto,
3830                                       unsigned int off)
3831 {
3832         switch (proto) {
3833                 int err;
3834 
3835         case IPPROTO_TCP:
3836                 err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
3837                                           off + MAX_TCP_HDR_LEN);
3838                 if (!err && !skb_partial_csum_set(skb, off,
3839                                                   offsetof(struct tcphdr,
3840                                                            check)))
3841                         err = -EPROTO;
3842                 return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
3843 
3844         case IPPROTO_UDP:
3845                 err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
3846                                           off + sizeof(struct udphdr));
3847                 if (!err && !skb_partial_csum_set(skb, off,
3848                                                   offsetof(struct udphdr,
3849                                                            check)))
3850                         err = -EPROTO;
3851                 return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
3852         }
3853 
3854         return ERR_PTR(-EPROTO);
3855 }
3856 
3857 /* This value should be large enough to cover a tagged ethernet header plus
3858  * maximally sized IP and TCP or UDP headers.
3859  */
3860 #define MAX_IP_HDR_LEN 128
3861 
3862 static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
3863 {
3864         unsigned int off;
3865         bool fragment;
3866         __sum16 *csum;
3867         int err;
3868 
3869         fragment = false;
3870 
3871         err = skb_maybe_pull_tail(skb,
3872                                   sizeof(struct iphdr),
3873                                   MAX_IP_HDR_LEN);
3874         if (err < 0)
3875                 goto out;
3876 
3877         if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
3878                 fragment = true;
3879 
3880         off = ip_hdrlen(skb);
3881 
3882         err = -EPROTO;
3883 
3884         if (fragment)
3885                 goto out;
3886 
3887         csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
3888         if (IS_ERR(csum))
3889                 return PTR_ERR(csum);
3890 
3891         if (recalculate)
3892                 *csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
3893                                            ip_hdr(skb)->daddr,
3894                                            skb->len - off,
3895                                            ip_hdr(skb)->protocol, 0);
3896         err = 0;
3897 
3898 out:
3899         return err;
3900 }
3901 
3902 /* This value should be large enough to cover a tagged ethernet header plus
3903  * an IPv6 header, all options, and a maximal TCP or UDP header.
3904  */
3905 #define MAX_IPV6_HDR_LEN 256
3906 
3907 #define OPT_HDR(type, skb, off) \
3908         (type *)(skb_network_header(skb) + (off))
3909 
3910 static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
3911 {
3912         int err;
3913         u8 nexthdr;
3914         unsigned int off;
3915         unsigned int len;
3916         bool fragment;
3917         bool done;
3918         __sum16 *csum;
3919 
3920         fragment = false;
3921         done = false;
3922 
3923         off = sizeof(struct ipv6hdr);
3924 
3925         err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
3926         if (err < 0)
3927                 goto out;
3928 
3929         nexthdr = ipv6_hdr(skb)->nexthdr;
3930 
3931         len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
3932         while (off <= len && !done) {
3933                 switch (nexthdr) {
3934                 case IPPROTO_DSTOPTS:
3935                 case IPPROTO_HOPOPTS:
3936                 case IPPROTO_ROUTING: {
3937                         struct ipv6_opt_hdr *hp;
3938 
3939                         err = skb_maybe_pull_tail(skb,
3940                                                   off +
3941                                                   sizeof(struct ipv6_opt_hdr),
3942                                                   MAX_IPV6_HDR_LEN);
3943                         if (err < 0)
3944                                 goto out;
3945 
3946                         hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
3947                         nexthdr = hp->nexthdr;
3948                         off += ipv6_optlen(hp);
3949                         break;
3950                 }
3951                 case IPPROTO_AH: {
3952                         struct ip_auth_hdr *hp;
3953 
3954                         err = skb_maybe_pull_tail(skb,
3955                                                   off +
3956                                                   sizeof(struct ip_auth_hdr),
3957                                                   MAX_IPV6_HDR_LEN);
3958                         if (err < 0)
3959                                 goto out;
3960 
3961                         hp = OPT_HDR(struct ip_auth_hdr, skb, off);
3962                         nexthdr = hp->nexthdr;
3963                         off += ipv6_authlen(hp);
3964                         break;
3965                 }
3966                 case IPPROTO_FRAGMENT: {
3967                         struct frag_hdr *hp;
3968 
3969                         err = skb_maybe_pull_tail(skb,
3970                                                   off +
3971                                                   sizeof(struct frag_hdr),
3972                                                   MAX_IPV6_HDR_LEN);
3973                         if (err < 0)
3974                                 goto out;
3975 
3976                         hp = OPT_HDR(struct frag_hdr, skb, off);
3977 
3978                         if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
3979                                 fragment = true;
3980 
3981                         nexthdr = hp->nexthdr;
3982                         off += sizeof(struct frag_hdr);
3983                         break;
3984                 }
3985                 default:
3986                         done = true;
3987                         break;
3988                 }
3989         }
3990 
3991         err = -EPROTO;
3992 
3993         if (!done || fragment)
3994                 goto out;
3995 
3996         csum = skb_checksum_setup_ip(skb, nexthdr, off);
3997         if (IS_ERR(csum))
3998                 return PTR_ERR(csum);
3999 
4000         if (recalculate)
4001                 *csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
4002                                          &ipv6_hdr(skb)->daddr,
4003                                          skb->len - off, nexthdr, 0);
4004         err = 0;
4005 
4006 out:
4007         return err;
4008 }
4009 
4010 /**
4011  * skb_checksum_setup - set up partial checksum offset
4012  * @skb: the skb to set up
4013  * @recalculate: if true the pseudo-header checksum will be recalculated
4014  */
4015 int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
4016 {
4017         int err;
4018 
4019         switch (skb->protocol) {
4020         case htons(ETH_P_IP):
4021                 err = skb_checksum_setup_ipv4(skb, recalculate);
4022                 break;
4023 
4024         case htons(ETH_P_IPV6):
4025                 err = skb_checksum_setup_ipv6(skb, recalculate);
4026                 break;
4027 
4028         default:
4029                 err = -EPROTO;
4030                 break;
4031         }
4032 
4033         return err;
4034 }
4035 EXPORT_SYMBOL(skb_checksum_setup);
4036 
4037 /**
4038  * skb_checksum_maybe_trim - maybe trims the given skb
4039  * @skb: the skb to check
4040  * @transport_len: the data length beyond the network header
4041  *
4042  * Checks whether the given skb has data beyond the given transport length.
4043  * If so, returns a cloned skb trimmed to this transport length.
4044  * Otherwise returns the provided skb. Returns NULL in error cases
4045  * (e.g. transport_len exceeds skb length or out-of-memory).
4046  *
4047  * Caller needs to set the skb transport header and free any returned skb if it
4048  * differs from the provided skb.
4049  */
4050 static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
4051                                                unsigned int transport_len)
4052 {
4053         struct sk_buff *skb_chk;
4054         unsigned int len = skb_transport_offset(skb) + transport_len;
4055         int ret;
4056 
4057         if (skb->len < len)
4058                 return NULL;
4059         else if (skb->len == len)
4060                 return skb;
4061 
4062         skb_chk = skb_clone(skb, GFP_ATOMIC);
4063         if (!skb_chk)
4064                 return NULL;
4065 
4066         ret = pskb_trim_rcsum(skb_chk, len);
4067         if (ret) {
4068                 kfree_skb(skb_chk);
4069                 return NULL;
4070         }
4071 
4072         return skb_chk;
4073 }
4074 
4075 /**
4076  * skb_checksum_trimmed - validate checksum of an skb
4077  * @skb: the skb to check
4078  * @transport_len: the data length beyond the network header
4079  * @skb_chkf: checksum function to use
4080  *
4081  * Applies the given checksum function skb_chkf to the provided skb.
4082  * Returns a checked and maybe trimmed skb. Returns NULL on error.
4083  *
4084  * If the skb has data beyond the given transport length, then a
4085  * trimmed & cloned skb is checked and returned.
4086  *
4087  * Caller needs to set the skb transport header and free any returned skb if it
4088  * differs from the provided skb.
4089  */
4090 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
4091                                      unsigned int transport_len,
4092                                      __sum16(*skb_chkf)(struct sk_buff *skb))
4093 {
4094         struct sk_buff *skb_chk;
4095         unsigned int offset = skb_transport_offset(skb);
4096         __sum16 ret;
4097 
4098         skb_chk = skb_checksum_maybe_trim(skb, transport_len);
4099         if (!skb_chk)
4100                 goto err;
4101 
4102         if (!pskb_may_pull(skb_chk, offset))
4103                 goto err;
4104 
4105         skb_pull_rcsum(skb_chk, offset);
4106         ret = skb_chkf(skb_chk);
4107         skb_push_rcsum(skb_chk, offset);
4108 
4109         if (ret)
4110                 goto err;
4111 
4112         return skb_chk;
4113 
4114 err:
4115         if (skb_chk && skb_chk != skb)
4116                 kfree_skb(skb_chk);
4117 
4118         return NULL;
4119 
4120 }
4121 EXPORT_SYMBOL(skb_checksum_trimmed);
4122 
4123 void __skb_warn_lro_forwarding(const struct sk_buff *skb)
4124 {
4125         net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
4126                              skb->dev->name);
4127 }
4128 EXPORT_SYMBOL(__skb_warn_lro_forwarding);
4129 
4130 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
4131 {
4132         if (head_stolen) {
4133                 skb_release_head_state(skb);
4134                 kmem_cache_free(skbuff_head_cache, skb);
4135         } else {
4136                 __kfree_skb(skb);
4137         }
4138 }
4139 EXPORT_SYMBOL(kfree_skb_partial);
4140 
4141 /**
4142  * skb_try_coalesce - try to merge skb to prior one
4143  * @to: prior buffer
4144  * @from: buffer to add
4145  * @fragstolen: pointer to boolean
4146  * @delta_truesize: how much more was allocated than was requested
4147  */
4148 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
4149                       bool *fragstolen, int *delta_truesize)
4150 {
4151         int i, delta, len = from->len;
4152 
4153         *fragstolen = false;
4154 
4155         if (skb_cloned(to))
4156                 return false;
4157 
4158         if (len <= skb_tailroom(to)) {
4159                 if (len)
4160                         BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
4161                 *delta_truesize = 0;
4162                 return true;
4163         }
4164 
4165         if (skb_has_frag_list(to) || skb_has_frag_list(from))
4166                 return false;
4167 
4168         if (skb_headlen(from) != 0) {
4169                 struct page *page;
4170                 unsigned int offset;
4171 
4172                 if (skb_shinfo(to)->nr_frags +
4173                     skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
4174                         return false;
4175 
4176                 if (skb_head_is_locked(from))
4177                         return false;
4178 
4179                 delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
4180 
4181                 page = virt_to_head_page(from->head);
4182                 offset = from->data - (unsigned char *)page_address(page);
4183 
4184                 skb_fill_page_desc(to, skb_shinfo(to)->nr_frags,
4185                                    page, offset, skb_headlen(from));
4186                 *fragstolen = true;
4187         } else {
4188                 if (skb_shinfo(to)->nr_frags +
4189                     skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS)
4190                         return false;
4191 
4192                 delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
4193         }
4194 
4195         WARN_ON_ONCE(delta < len);
4196 
4197         memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags,
4198                skb_shinfo(from)->frags,
4199                skb_shinfo(from)->nr_frags * sizeof(skb_frag_t));
4200         skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags;
4201 
4202         if (!skb_cloned(from))
4203                 skb_shinfo(from)->nr_frags = 0;
4204 
4205         /* if the skb is not cloned this does nothing
4206          * since we set nr_frags to 0.
4207          */
4208         for (i = 0; i < skb_shinfo(from)->nr_frags; i++)
4209                 skb_frag_ref(from, i);
4210 
4211         to->truesize += delta;
4212         to->len += len;
4213         to->data_len += len;
4214 
4215         *delta_truesize = delta;
4216         return true;
4217 }
4218 EXPORT_SYMBOL(skb_try_coalesce);
4219 
4220 /**
4221  * skb_scrub_packet - scrub an skb
4222  *
4223  * @skb: buffer to clean
4224  * @xnet: packet is crossing netns
4225  *
4226  * skb_scrub_packet can be used after encapsulating or decapsulting a packet
4227  * into/from a tunnel. Some information have to be cleared during these
4228  * operations.
4229  * skb_scrub_packet can also be used to clean a skb before injecting it in
4230  * another namespace (@xnet == true). We have to clear all information in the
4231  * skb that could impact namespace isolation.
4232  */
4233 void skb_scrub_packet(struct sk_buff *skb, bool xnet)
4234 {
4235         skb->tstamp.tv64 = 0;
4236         skb->pkt_type = PACKET_HOST;
4237         skb->skb_iif = 0;
4238         skb->ignore_df = 0;
4239         skb_dst_drop(skb);
4240         skb_sender_cpu_clear(skb);
4241         secpath_reset(skb);
4242         nf_reset(skb);
4243         nf_reset_trace(skb);
4244 
4245         if (!xnet)
4246                 return;
4247 
4248         skb_orphan(skb);
4249         skb->mark = 0;
4250 }
4251 EXPORT_SYMBOL_GPL(skb_scrub_packet);
4252 
4253 /**
4254  * skb_gso_transport_seglen - Return length of individual segments of a gso packet
4255  *
4256  * @skb: GSO skb
4257  *
4258  * skb_gso_transport_seglen is used to determine the real size of the
4259  * individual segments, including Layer4 headers (TCP/UDP).
4260  *
4261  * The MAC/L2 or network (IP, IPv6) headers are not accounted for.
4262  */
4263 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
4264 {
4265         const struct skb_shared_info *shinfo = skb_shinfo(skb);
4266         unsigned int thlen = 0;
4267 
4268         if (skb->encapsulation) {
4269                 thlen = skb_inner_transport_header(skb) -
4270                         skb_transport_header(skb);
4271 
4272                 if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
4273                         thlen += inner_tcp_hdrlen(skb);
4274         } else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
4275                 thlen = tcp_hdrlen(skb);
4276         }
4277         /* UFO sets gso_size to the size of the fragmentation
4278          * payload, i.e. the size of the L4 (UDP) header is already
4279          * accounted for.
4280          */
4281         return thlen + shinfo->gso_size;
4282 }
4283 EXPORT_SYMBOL_GPL(skb_gso_transport_seglen);
4284 
4285 static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
4286 {
4287         if (skb_cow(skb, skb_headroom(skb)) < 0) {
4288                 kfree_skb(skb);
4289                 return NULL;
4290         }
4291 
4292         memmove(skb->data - ETH_HLEN, skb->data - skb->mac_len - VLAN_HLEN,
4293                 2 * ETH_ALEN);
4294         skb->mac_header += VLAN_HLEN;
4295         return skb;
4296 }
4297 
4298 struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
4299 {
4300         struct vlan_hdr *vhdr;
4301         u16 vlan_tci;
4302 
4303         if (unlikely(skb_vlan_tag_present(skb))) {
4304                 /* vlan_tci is already set-up so leave this for another time */
4305                 return skb;
4306         }
4307 
4308         skb = skb_share_check(skb, GFP_ATOMIC);
4309         if (unlikely(!skb))
4310                 goto err_free;
4311 
4312         if (unlikely(!pskb_may_pull(skb, VLAN_HLEN)))
4313                 goto err_free;
4314 
4315         vhdr = (struct vlan_hdr *)skb->data;
4316         vlan_tci = ntohs(vhdr->h_vlan_TCI);
4317         __vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
4318 
4319         skb_pull_rcsum(skb, VLAN_HLEN);
4320         vlan_set_encap_proto(skb, vhdr);
4321 
4322         skb = skb_reorder_vlan_header(skb);
4323         if (unlikely(!skb))
4324                 goto err_free;
4325 
4326         skb_reset_network_header(skb);
4327         skb_reset_transport_header(skb);
4328         skb_reset_mac_len(skb);
4329 
4330         return skb;
4331 
4332 err_free:
4333         kfree_skb(skb);
4334         return NULL;
4335 }
4336 EXPORT_SYMBOL(skb_vlan_untag);
4337 
4338 int skb_ensure_writable(struct sk_buff *skb, int write_len)
4339 {
4340         if (!pskb_may_pull(skb, write_len))
4341                 return -ENOMEM;
4342 
4343         if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
4344                 return 0;
4345 
4346         return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
4347 }
4348 EXPORT_SYMBOL(skb_ensure_writable);
4349 
4350 /* remove VLAN header from packet and update csum accordingly. */
4351 static int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
4352 {
4353         struct vlan_hdr *vhdr;
4354         unsigned int offset = skb->data - skb_mac_header(skb);
4355         int err;
4356 
4357         __skb_push(skb, offset);
4358         err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
4359         if (unlikely(err))
4360                 goto pull;
4361 
4362         skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
4363 
4364         vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
4365         *vlan_tci = ntohs(vhdr->h_vlan_TCI);
4366 
4367         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
4368         __skb_pull(skb, VLAN_HLEN);
4369 
4370         vlan_set_encap_proto(skb, vhdr);
4371         skb->mac_header += VLAN_HLEN;
4372 
4373         if (skb_network_offset(skb) < ETH_HLEN)
4374                 skb_set_network_header(skb, ETH_HLEN);
4375 
4376         skb_reset_mac_len(skb);
4377 pull:
4378         __skb_pull(skb, offset);
4379 
4380         return err;
4381 }
4382 
4383 int skb_vlan_pop(struct sk_buff *skb)
4384 {
4385         u16 vlan_tci;
4386         __be16 vlan_proto;
4387         int err;
4388 
4389         if (likely(skb_vlan_tag_present(skb))) {
4390                 skb->vlan_tci = 0;
4391         } else {
4392                 if (unlikely((skb->protocol != htons(ETH_P_8021Q) &&
4393                               skb->protocol != htons(ETH_P_8021AD)) ||
4394                              skb->len < VLAN_ETH_HLEN))
4395                         return 0;
4396 
4397                 err = __skb_vlan_pop(skb, &vlan_tci);
4398                 if (err)
4399                         return err;
4400         }
4401         /* move next vlan tag to hw accel tag */
4402         if (likely((skb->protocol != htons(ETH_P_8021Q) &&
4403                     skb->protocol != htons(ETH_P_8021AD)) ||
4404                    skb->len < VLAN_ETH_HLEN))
4405                 return 0;
4406 
4407         vlan_proto = skb->protocol;
4408         err = __skb_vlan_pop(skb, &vlan_tci);
4409         if (unlikely(err))
4410                 return err;
4411 
4412         __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
4413         return 0;
4414 }
4415 EXPORT_SYMBOL(skb_vlan_pop);
4416 
4417 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
4418 {
4419         if (skb_vlan_tag_present(skb)) {
4420                 unsigned int offset = skb->data - skb_mac_header(skb);
4421                 int err;
4422 
4423                 /* __vlan_insert_tag expect skb->data pointing to mac header.
4424                  * So change skb->data before calling it and change back to
4425                  * original position later
4426                  */
4427                 __skb_push(skb, offset);
4428                 err = __vlan_insert_tag(skb, skb->vlan_proto,
4429                                         skb_vlan_tag_get(skb));
4430                 if (err)
4431                         return err;
4432                 skb->protocol = skb->vlan_proto;
4433                 skb->mac_len += VLAN_HLEN;
4434                 __skb_pull(skb, offset);
4435 
4436                 if (skb->ip_summed == CHECKSUM_COMPLETE)
4437                         skb->csum = csum_add(skb->csum, csum_partial(skb->data
4438                                         + (2 * ETH_ALEN), VLAN_HLEN, 0));
4439         }
4440         __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
4441         return 0;
4442 }
4443 EXPORT_SYMBOL(skb_vlan_push);
4444 
4445 /**
4446  * alloc_skb_with_frags - allocate skb with page frags
4447  *
4448  * @header_len: size of linear part
4449  * @data_len: needed length in frags
4450  * @max_page_order: max page order desired.
4451  * @errcode: pointer to error code if any
4452  * @gfp_mask: allocation mask
4453  *
4454  * This can be used to allocate a paged skb, given a maximal order for frags.
4455  */
4456 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
4457                                      unsigned long data_len,
4458                                      int max_page_order,
4459                                      int *errcode,
4460                                      gfp_t gfp_mask)
4461 {
4462         int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
4463         unsigned long chunk;
4464         struct sk_buff *skb;
4465         struct page *page;
4466         gfp_t gfp_head;
4467         int i;
4468 
4469         *errcode = -EMSGSIZE;
4470         /* Note this test could be relaxed, if we succeed to allocate
4471          * high order pages...
4472          */
4473         if (npages > MAX_SKB_FRAGS)
4474                 return NULL;
4475 
4476         gfp_head = gfp_mask;
4477         if (gfp_head & __GFP_DIRECT_RECLAIM)
4478                 gfp_head |= __GFP_REPEAT;
4479 
4480         *errcode = -ENOBUFS;
4481         skb = alloc_skb(header_len, gfp_head);
4482         if (!skb)
4483                 return NULL;
4484 
4485         skb->truesize += npages << PAGE_SHIFT;
4486 
4487         for (i = 0; npages > 0; i++) {
4488                 int order = max_page_order;
4489 
4490                 while (order) {
4491                         if (npages >= 1 << order) {
4492                                 page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
4493                                                    __GFP_COMP |
4494                                                    __GFP_NOWARN |
4495                                                    __GFP_NORETRY,
4496                                                    order);
4497                                 if (page)
4498                                         goto fill_page;
4499                                 /* Do not retry other high order allocations */
4500                                 order = 1;
4501                                 max_page_order = 0;
4502                         }
4503                         order--;
4504                 }
4505                 page = alloc_page(gfp_mask);
4506                 if (!page)
4507                         goto failure;
4508 fill_page:
4509                 chunk = min_t(unsigned long, data_len,
4510                               PAGE_SIZE << order);
4511                 skb_fill_page_desc(skb, i, page, 0, chunk);
4512                 data_len -= chunk;
4513                 npages -= 1 << order;
4514         }
4515         return skb;
4516 
4517 failure:
4518         kfree_skb(skb);
4519         return NULL;
4520 }
4521 EXPORT_SYMBOL(alloc_skb_with_frags);
4522 

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