Version:  2.0.40 2.2.26 2.4.37 3.6 3.7 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

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

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