Version:  2.0.40 2.2.26 2.4.37 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7

Linux/net/core/skbuff.c

  1 /*
  2  *      Routines having to do with the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:        Alan Cox <alan@lxorguk.ukuu.org.uk>
  5  *                      Florian La Roche <rzsfl@rz.uni-sb.de>
  6  *
  7  *      Fixes:
  8  *              Alan Cox        :       Fixed the worst of the load
  9  *                                      balancer bugs.
 10  *              Dave Platt      :       Interrupt stacking fix.
 11  *      Richard Kooijman        :       Timestamp fixes.
 12  *              Alan Cox        :       Changed buffer format.
 13  *              Alan Cox        :       destructor hook for AF_UNIX etc.
 14  *              Linus Torvalds  :       Better skb_clone.
 15  *              Alan Cox        :       Added skb_copy.
 16  *              Alan Cox        :       Added all the changed routines Linus
 17  *                                      only put in the headers
 18  *              Ray VanTassle   :       Fixed --skb->lock in free
 19  *              Alan Cox        :       skb_copy copy arp field
 20  *              Andi Kleen      :       slabified it.
 21  *              Robert Olsson   :       Removed skb_head_pool
 22  *
 23  *      NOTE:
 24  *              The __skb_ routines should be called with interrupts
 25  *      disabled, or you better be *real* sure that the operation is atomic
 26  *      with respect to whatever list is being frobbed (e.g. via lock_sock()
 27  *      or via disabling bottom half handlers, etc).
 28  *
 29  *      This program is free software; you can redistribute it and/or
 30  *      modify it under the terms of the GNU General Public License
 31  *      as published by the Free Software Foundation; either version
 32  *      2 of the License, or (at your option) any later version.
 33  */
 34 
 35 /*
 36  *      The functions in this file will not compile correctly with gcc 2.4.x
 37  */
 38 
 39 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 40 
 41 #include <linux/module.h>
 42 #include <linux/types.h>
 43 #include <linux/kernel.h>
 44 #include <linux/kmemcheck.h>
 45 #include <linux/mm.h>
 46 #include <linux/interrupt.h>
 47 #include <linux/in.h>
 48 #include <linux/inet.h>
 49 #include <linux/slab.h>
 50 #include <linux/tcp.h>
 51 #include <linux/udp.h>
 52 #include <linux/netdevice.h>
 53 #ifdef CONFIG_NET_CLS_ACT
 54 #include <net/pkt_sched.h>
 55 #endif
 56 #include <linux/string.h>
 57 #include <linux/skbuff.h>
 58 #include <linux/splice.h>
 59 #include <linux/cache.h>
 60 #include <linux/rtnetlink.h>
 61 #include <linux/init.h>
 62 #include <linux/scatterlist.h>
 63 #include <linux/errqueue.h>
 64 #include <linux/prefetch.h>
 65 #include <linux/if_vlan.h>
 66 
 67 #include <net/protocol.h>
 68 #include <net/dst.h>
 69 #include <net/sock.h>
 70 #include <net/checksum.h>
 71 #include <net/ip6_checksum.h>
 72 #include <net/xfrm.h>
 73 
 74 #include <asm/uaccess.h>
 75 #include <trace/events/skb.h>
 76 #include <linux/highmem.h>
 77 #include <linux/capability.h>
 78 #include <linux/user_namespace.h>
 79 
 80 struct kmem_cache *skbuff_head_cache __read_mostly;
 81 static struct kmem_cache *skbuff_fclone_cache __read_mostly;
 82 int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
 83 EXPORT_SYMBOL(sysctl_max_skb_frags);
 84 
 85 /**
 86  *      skb_panic - private function for out-of-line support
 87  *      @skb:   buffer
 88  *      @sz:    size
 89  *      @addr:  address
 90  *      @msg:   skb_over_panic or skb_under_panic
 91  *
 92  *      Out-of-line support for skb_put() and skb_push().
 93  *      Called via the wrapper skb_over_panic() or skb_under_panic().
 94  *      Keep out of line to prevent kernel bloat.
 95  *      __builtin_return_address is not used because it is not always reliable.
 96  */
 97 static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
 98                       const char msg[])
 99 {
100         pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n",
101                  msg, addr, skb->len, sz, skb->head, skb->data,
102                  (unsigned long)skb->tail, (unsigned long)skb->end,
103                  skb->dev ? skb->dev->name : "<NULL>");
104         BUG();
105 }
106 
107 static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
108 {
109         skb_panic(skb, sz, addr, __func__);
110 }
111 
112 static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
113 {
114         skb_panic(skb, sz, addr, __func__);
115 }
116 
117 /*
118  * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
119  * the caller if emergency pfmemalloc reserves are being used. If it is and
120  * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
121  * may be used. Otherwise, the packet data may be discarded until enough
122  * memory is free
123  */
124 #define kmalloc_reserve(size, gfp, node, pfmemalloc) \
125          __kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc)
126 
127 static void *__kmalloc_reserve(size_t size, gfp_t flags, int node,
128                                unsigned long ip, bool *pfmemalloc)
129 {
130         void *obj;
131         bool ret_pfmemalloc = false;
132 
133         /*
134          * Try a regular allocation, when that fails and we're not entitled
135          * to the reserves, fail.
136          */
137         obj = kmalloc_node_track_caller(size,
138                                         flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
139                                         node);
140         if (obj || !(gfp_pfmemalloc_allowed(flags)))
141                 goto out;
142 
143         /* Try again but now we are using pfmemalloc reserves */
144         ret_pfmemalloc = true;
145         obj = kmalloc_node_track_caller(size, flags, node);
146 
147 out:
148         if (pfmemalloc)
149                 *pfmemalloc = ret_pfmemalloc;
150 
151         return obj;
152 }
153 
154 /*      Allocate a new skbuff. We do this ourselves so we can fill in a few
155  *      'private' fields and also do memory statistics to find all the
156  *      [BEEP] leaks.
157  *
158  */
159 
160 struct sk_buff *__alloc_skb_head(gfp_t gfp_mask, int node)
161 {
162         struct sk_buff *skb;
163 
164         /* Get the HEAD */
165         skb = kmem_cache_alloc_node(skbuff_head_cache,
166                                     gfp_mask & ~__GFP_DMA, node);
167         if (!skb)
168                 goto out;
169 
170         /*
171          * Only clear those fields we need to clear, not those that we will
172          * actually initialise below. Hence, don't put any more fields after
173          * the tail pointer in struct sk_buff!
174          */
175         memset(skb, 0, offsetof(struct sk_buff, tail));
176         skb->head = NULL;
177         skb->truesize = sizeof(struct sk_buff);
178         atomic_set(&skb->users, 1);
179 
180         skb->mac_header = (typeof(skb->mac_header))~0U;
181 out:
182         return skb;
183 }
184 
185 /**
186  *      __alloc_skb     -       allocate a network buffer
187  *      @size: size to allocate
188  *      @gfp_mask: allocation mask
189  *      @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
190  *              instead of head cache and allocate a cloned (child) skb.
191  *              If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
192  *              allocations in case the data is required for writeback
193  *      @node: numa node to allocate memory on
194  *
195  *      Allocate a new &sk_buff. The returned buffer has no headroom and a
196  *      tail room of at least size bytes. The object has a reference count
197  *      of one. The return is the buffer. On a failure the return is %NULL.
198  *
199  *      Buffers may only be allocated from interrupts using a @gfp_mask of
200  *      %GFP_ATOMIC.
201  */
202 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
203                             int flags, int node)
204 {
205         struct kmem_cache *cache;
206         struct skb_shared_info *shinfo;
207         struct sk_buff *skb;
208         u8 *data;
209         bool pfmemalloc;
210 
211         cache = (flags & SKB_ALLOC_FCLONE)
212                 ? skbuff_fclone_cache : skbuff_head_cache;
213 
214         if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
215                 gfp_mask |= __GFP_MEMALLOC;
216 
217         /* Get the HEAD */
218         skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
219         if (!skb)
220                 goto out;
221         prefetchw(skb);
222 
223         /* We do our best to align skb_shared_info on a separate cache
224          * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
225          * aligned memory blocks, unless SLUB/SLAB debug is enabled.
226          * Both skb->head and skb_shared_info are cache line aligned.
227          */
228         size = SKB_DATA_ALIGN(size);
229         size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
230         data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
231         if (!data)
232                 goto nodata;
233         /* kmalloc(size) might give us more room than requested.
234          * Put skb_shared_info exactly at the end of allocated zone,
235          * to allow max possible filling before reallocation.
236          */
237         size = SKB_WITH_OVERHEAD(ksize(data));
238         prefetchw(data + size);
239 
240         /*
241          * Only clear those fields we need to clear, not those that we will
242          * actually initialise below. Hence, don't put any more fields after
243          * the tail pointer in struct sk_buff!
244          */
245         memset(skb, 0, offsetof(struct sk_buff, tail));
246         /* Account for allocated memory : skb + skb->head */
247         skb->truesize = SKB_TRUESIZE(size);
248         skb->pfmemalloc = pfmemalloc;
249         atomic_set(&skb->users, 1);
250         skb->head = data;
251         skb->data = data;
252         skb_reset_tail_pointer(skb);
253         skb->end = skb->tail + size;
254         skb->mac_header = (typeof(skb->mac_header))~0U;
255         skb->transport_header = (typeof(skb->transport_header))~0U;
256 
257         /* make sure we initialize shinfo sequentially */
258         shinfo = skb_shinfo(skb);
259         memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
260         atomic_set(&shinfo->dataref, 1);
261         kmemcheck_annotate_variable(shinfo->destructor_arg);
262 
263         if (flags & SKB_ALLOC_FCLONE) {
264                 struct sk_buff_fclones *fclones;
265 
266                 fclones = container_of(skb, struct sk_buff_fclones, skb1);
267 
268                 kmemcheck_annotate_bitfield(&fclones->skb2, flags1);
269                 skb->fclone = SKB_FCLONE_ORIG;
270                 atomic_set(&fclones->fclone_ref, 1);
271 
272                 fclones->skb2.fclone = SKB_FCLONE_CLONE;
273                 fclones->skb2.pfmemalloc = pfmemalloc;
274         }
275 out:
276         return skb;
277 nodata:
278         kmem_cache_free(cache, skb);
279         skb = NULL;
280         goto out;
281 }
282 EXPORT_SYMBOL(__alloc_skb);
283 
284 /**
285  * __build_skb - build a network buffer
286  * @data: data buffer provided by caller
287  * @frag_size: size of data, or 0 if head was kmalloced
288  *
289  * Allocate a new &sk_buff. Caller provides space holding head and
290  * skb_shared_info. @data must have been allocated by kmalloc() only if
291  * @frag_size is 0, otherwise data should come from the page allocator
292  *  or vmalloc()
293  * The return is the new skb buffer.
294  * On a failure the return is %NULL, and @data is not freed.
295  * Notes :
296  *  Before IO, driver allocates only data buffer where NIC put incoming frame
297  *  Driver should add room at head (NET_SKB_PAD) and
298  *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
299  *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
300  *  before giving packet to stack.
301  *  RX rings only contains data buffers, not full skbs.
302  */
303 struct sk_buff *__build_skb(void *data, unsigned int frag_size)
304 {
305         struct skb_shared_info *shinfo;
306         struct sk_buff *skb;
307         unsigned int size = frag_size ? : ksize(data);
308 
309         skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
310         if (!skb)
311                 return NULL;
312 
313         size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
314 
315         memset(skb, 0, offsetof(struct sk_buff, tail));
316         skb->truesize = SKB_TRUESIZE(size);
317         atomic_set(&skb->users, 1);
318         skb->head = data;
319         skb->data = data;
320         skb_reset_tail_pointer(skb);
321         skb->end = skb->tail + size;
322         skb->mac_header = (typeof(skb->mac_header))~0U;
323         skb->transport_header = (typeof(skb->transport_header))~0U;
324 
325         /* make sure we initialize shinfo sequentially */
326         shinfo = skb_shinfo(skb);
327         memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
328         atomic_set(&shinfo->dataref, 1);
329         kmemcheck_annotate_variable(shinfo->destructor_arg);
330 
331         return skb;
332 }
333 
334 /* build_skb() is wrapper over __build_skb(), that specifically
335  * takes care of skb->head and skb->pfmemalloc
336  * This means that if @frag_size is not zero, then @data must be backed
337  * by a page fragment, not kmalloc() or vmalloc()
338  */
339 struct sk_buff *build_skb(void *data, unsigned int frag_size)
340 {
341         struct sk_buff *skb = __build_skb(data, frag_size);
342 
343         if (skb && frag_size) {
344                 skb->head_frag = 1;
345                 if (page_is_pfmemalloc(virt_to_head_page(data)))
346                         skb->pfmemalloc = 1;
347         }
348         return skb;
349 }
350 EXPORT_SYMBOL(build_skb);
351 
352 #define NAPI_SKB_CACHE_SIZE     64
353 
354 struct napi_alloc_cache {
355         struct page_frag_cache page;
356         size_t skb_count;
357         void *skb_cache[NAPI_SKB_CACHE_SIZE];
358 };
359 
360 static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
361 static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache);
362 
363 static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
364 {
365         struct page_frag_cache *nc;
366         unsigned long flags;
367         void *data;
368 
369         local_irq_save(flags);
370         nc = this_cpu_ptr(&netdev_alloc_cache);
371         data = __alloc_page_frag(nc, fragsz, gfp_mask);
372         local_irq_restore(flags);
373         return data;
374 }
375 
376 /**
377  * netdev_alloc_frag - allocate a page fragment
378  * @fragsz: fragment size
379  *
380  * Allocates a frag from a page for receive buffer.
381  * Uses GFP_ATOMIC allocations.
382  */
383 void *netdev_alloc_frag(unsigned int fragsz)
384 {
385         return __netdev_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD);
386 }
387 EXPORT_SYMBOL(netdev_alloc_frag);
388 
389 static void *__napi_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
390 {
391         struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
392 
393         return __alloc_page_frag(&nc->page, fragsz, gfp_mask);
394 }
395 
396 void *napi_alloc_frag(unsigned int fragsz)
397 {
398         return __napi_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD);
399 }
400 EXPORT_SYMBOL(napi_alloc_frag);
401 
402 /**
403  *      __netdev_alloc_skb - allocate an skbuff for rx on a specific device
404  *      @dev: network device to receive on
405  *      @len: length to allocate
406  *      @gfp_mask: get_free_pages mask, passed to alloc_skb
407  *
408  *      Allocate a new &sk_buff and assign it a usage count of one. The
409  *      buffer has NET_SKB_PAD headroom built in. Users should allocate
410  *      the headroom they think they need without accounting for the
411  *      built in space. The built in space is used for optimisations.
412  *
413  *      %NULL is returned if there is no free memory.
414  */
415 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
416                                    gfp_t gfp_mask)
417 {
418         struct page_frag_cache *nc;
419         unsigned long flags;
420         struct sk_buff *skb;
421         bool pfmemalloc;
422         void *data;
423 
424         len += NET_SKB_PAD;
425 
426         if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
427             (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
428                 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
429                 if (!skb)
430                         goto skb_fail;
431                 goto skb_success;
432         }
433 
434         len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
435         len = SKB_DATA_ALIGN(len);
436 
437         if (sk_memalloc_socks())
438                 gfp_mask |= __GFP_MEMALLOC;
439 
440         local_irq_save(flags);
441 
442         nc = this_cpu_ptr(&netdev_alloc_cache);
443         data = __alloc_page_frag(nc, len, gfp_mask);
444         pfmemalloc = nc->pfmemalloc;
445 
446         local_irq_restore(flags);
447 
448         if (unlikely(!data))
449                 return NULL;
450 
451         skb = __build_skb(data, len);
452         if (unlikely(!skb)) {
453                 skb_free_frag(data);
454                 return NULL;
455         }
456 
457         /* use OR instead of assignment to avoid clearing of bits in mask */
458         if (pfmemalloc)
459                 skb->pfmemalloc = 1;
460         skb->head_frag = 1;
461 
462 skb_success:
463         skb_reserve(skb, NET_SKB_PAD);
464         skb->dev = dev;
465 
466 skb_fail:
467         return skb;
468 }
469 EXPORT_SYMBOL(__netdev_alloc_skb);
470 
471 /**
472  *      __napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
473  *      @napi: napi instance this buffer was allocated for
474  *      @len: length to allocate
475  *      @gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
476  *
477  *      Allocate a new sk_buff for use in NAPI receive.  This buffer will
478  *      attempt to allocate the head from a special reserved region used
479  *      only for NAPI Rx allocation.  By doing this we can save several
480  *      CPU cycles by avoiding having to disable and re-enable IRQs.
481  *
482  *      %NULL is returned if there is no free memory.
483  */
484 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
485                                  gfp_t gfp_mask)
486 {
487         struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
488         struct sk_buff *skb;
489         void *data;
490 
491         len += NET_SKB_PAD + NET_IP_ALIGN;
492 
493         if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
494             (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
495                 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
496                 if (!skb)
497                         goto skb_fail;
498                 goto skb_success;
499         }
500 
501         len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
502         len = SKB_DATA_ALIGN(len);
503 
504         if (sk_memalloc_socks())
505                 gfp_mask |= __GFP_MEMALLOC;
506 
507         data = __alloc_page_frag(&nc->page, len, gfp_mask);
508         if (unlikely(!data))
509                 return NULL;
510 
511         skb = __build_skb(data, len);
512         if (unlikely(!skb)) {
513                 skb_free_frag(data);
514                 return NULL;
515         }
516 
517         /* use OR instead of assignment to avoid clearing of bits in mask */
518         if (nc->page.pfmemalloc)
519                 skb->pfmemalloc = 1;
520         skb->head_frag = 1;
521 
522 skb_success:
523         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
524         skb->dev = napi->dev;
525 
526 skb_fail:
527         return skb;
528 }
529 EXPORT_SYMBOL(__napi_alloc_skb);
530 
531 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
532                      int size, unsigned int truesize)
533 {
534         skb_fill_page_desc(skb, i, page, off, size);
535         skb->len += size;
536         skb->data_len += size;
537         skb->truesize += truesize;
538 }
539 EXPORT_SYMBOL(skb_add_rx_frag);
540 
541 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
542                           unsigned int truesize)
543 {
544         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
545 
546         skb_frag_size_add(frag, size);
547         skb->len += size;
548         skb->data_len += size;
549         skb->truesize += truesize;
550 }
551 EXPORT_SYMBOL(skb_coalesce_rx_frag);
552 
553 static void skb_drop_list(struct sk_buff **listp)
554 {
555         kfree_skb_list(*listp);
556         *listp = NULL;
557 }
558 
559 static inline void skb_drop_fraglist(struct sk_buff *skb)
560 {
561         skb_drop_list(&skb_shinfo(skb)->frag_list);
562 }
563 
564 static void skb_clone_fraglist(struct sk_buff *skb)
565 {
566         struct sk_buff *list;
567 
568         skb_walk_frags(skb, list)
569                 skb_get(list);
570 }
571 
572 static void skb_free_head(struct sk_buff *skb)
573 {
574         unsigned char *head = skb->head;
575 
576         if (skb->head_frag)
577                 skb_free_frag(head);
578         else
579                 kfree(head);
580 }
581 
582 static void skb_release_data(struct sk_buff *skb)
583 {
584         struct skb_shared_info *shinfo = skb_shinfo(skb);
585         int i;
586 
587         if (skb->cloned &&
588             atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
589                               &shinfo->dataref))
590                 return;
591 
592         for (i = 0; i < shinfo->nr_frags; i++)
593                 __skb_frag_unref(&shinfo->frags[i]);
594 
595         /*
596          * If skb buf is from userspace, we need to notify the caller
597          * the lower device DMA has done;
598          */
599         if (shinfo->tx_flags & SKBTX_DEV_ZEROCOPY) {
600                 struct ubuf_info *uarg;
601 
602                 uarg = shinfo->destructor_arg;
603                 if (uarg->callback)
604                         uarg->callback(uarg, true);
605         }
606 
607         if (shinfo->frag_list)
608                 kfree_skb_list(shinfo->frag_list);
609 
610         skb_free_head(skb);
611 }
612 
613 /*
614  *      Free an skbuff by memory without cleaning the state.
615  */
616 static void kfree_skbmem(struct sk_buff *skb)
617 {
618         struct sk_buff_fclones *fclones;
619 
620         switch (skb->fclone) {
621         case SKB_FCLONE_UNAVAILABLE:
622                 kmem_cache_free(skbuff_head_cache, skb);
623                 return;
624 
625         case SKB_FCLONE_ORIG:
626                 fclones = container_of(skb, struct sk_buff_fclones, skb1);
627 
628                 /* We usually free the clone (TX completion) before original skb
629                  * This test would have no chance to be true for the clone,
630                  * while here, branch prediction will be good.
631                  */
632                 if (atomic_read(&fclones->fclone_ref) == 1)
633                         goto fastpath;
634                 break;
635 
636         default: /* SKB_FCLONE_CLONE */
637                 fclones = container_of(skb, struct sk_buff_fclones, skb2);
638                 break;
639         }
640         if (!atomic_dec_and_test(&fclones->fclone_ref))
641                 return;
642 fastpath:
643         kmem_cache_free(skbuff_fclone_cache, fclones);
644 }
645 
646 static void skb_release_head_state(struct sk_buff *skb)
647 {
648         skb_dst_drop(skb);
649 #ifdef CONFIG_XFRM
650         secpath_put(skb->sp);
651 #endif
652         if (skb->destructor) {
653                 WARN_ON(in_irq());
654                 skb->destructor(skb);
655         }
656 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
657         nf_conntrack_put(skb->nfct);
658 #endif
659 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
660         nf_bridge_put(skb->nf_bridge);
661 #endif
662 }
663 
664 /* Free everything but the sk_buff shell. */
665 static void skb_release_all(struct sk_buff *skb)
666 {
667         skb_release_head_state(skb);
668         if (likely(skb->head))
669                 skb_release_data(skb);
670 }
671 
672 /**
673  *      __kfree_skb - private function
674  *      @skb: buffer
675  *
676  *      Free an sk_buff. Release anything attached to the buffer.
677  *      Clean the state. This is an internal helper function. Users should
678  *      always call kfree_skb
679  */
680 
681 void __kfree_skb(struct sk_buff *skb)
682 {
683         skb_release_all(skb);
684         kfree_skbmem(skb);
685 }
686 EXPORT_SYMBOL(__kfree_skb);
687 
688 /**
689  *      kfree_skb - free an sk_buff
690  *      @skb: buffer to free
691  *
692  *      Drop a reference to the buffer and free it if the usage count has
693  *      hit zero.
694  */
695 void kfree_skb(struct sk_buff *skb)
696 {
697         if (unlikely(!skb))
698                 return;
699         if (likely(atomic_read(&skb->users) == 1))
700                 smp_rmb();
701         else if (likely(!atomic_dec_and_test(&skb->users)))
702                 return;
703         trace_kfree_skb(skb, __builtin_return_address(0));
704         __kfree_skb(skb);
705 }
706 EXPORT_SYMBOL(kfree_skb);
707 
708 void kfree_skb_list(struct sk_buff *segs)
709 {
710         while (segs) {
711                 struct sk_buff *next = segs->next;
712 
713                 kfree_skb(segs);
714                 segs = next;
715         }
716 }
717 EXPORT_SYMBOL(kfree_skb_list);
718 
719 /**
720  *      skb_tx_error - report an sk_buff xmit error
721  *      @skb: buffer that triggered an error
722  *
723  *      Report xmit error if a device callback is tracking this skb.
724  *      skb must be freed afterwards.
725  */
726 void skb_tx_error(struct sk_buff *skb)
727 {
728         if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
729                 struct ubuf_info *uarg;
730 
731                 uarg = skb_shinfo(skb)->destructor_arg;
732                 if (uarg->callback)
733                         uarg->callback(uarg, false);
734                 skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
735         }
736 }
737 EXPORT_SYMBOL(skb_tx_error);
738 
739 /**
740  *      consume_skb - free an skbuff
741  *      @skb: buffer to free
742  *
743  *      Drop a ref to the buffer and free it if the usage count has hit zero
744  *      Functions identically to kfree_skb, but kfree_skb assumes that the frame
745  *      is being dropped after a failure and notes that
746  */
747 void consume_skb(struct sk_buff *skb)
748 {
749         if (unlikely(!skb))
750                 return;
751         if (likely(atomic_read(&skb->users) == 1))
752                 smp_rmb();
753         else if (likely(!atomic_dec_and_test(&skb->users)))
754                 return;
755         trace_consume_skb(skb);
756         __kfree_skb(skb);
757 }
758 EXPORT_SYMBOL(consume_skb);
759 
760 void __kfree_skb_flush(void)
761 {
762         struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
763 
764         /* flush skb_cache if containing objects */
765         if (nc->skb_count) {
766                 kmem_cache_free_bulk(skbuff_head_cache, nc->skb_count,
767                                      nc->skb_cache);
768                 nc->skb_count = 0;
769         }
770 }
771 
772 static inline void _kfree_skb_defer(struct sk_buff *skb)
773 {
774         struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
775 
776         /* drop skb->head and call any destructors for packet */
777         skb_release_all(skb);
778 
779         /* record skb to CPU local list */
780         nc->skb_cache[nc->skb_count++] = skb;
781 
782 #ifdef CONFIG_SLUB
783         /* SLUB writes into objects when freeing */
784         prefetchw(skb);
785 #endif
786 
787         /* flush skb_cache if it is filled */
788         if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
789                 kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_SIZE,
790                                      nc->skb_cache);
791                 nc->skb_count = 0;
792         }
793 }
794 void __kfree_skb_defer(struct sk_buff *skb)
795 {
796         _kfree_skb_defer(skb);
797 }
798 
799 void napi_consume_skb(struct sk_buff *skb, int budget)
800 {
801         if (unlikely(!skb))
802                 return;
803 
804         /* Zero budget indicate non-NAPI context called us, like netpoll */
805         if (unlikely(!budget)) {
806                 dev_consume_skb_any(skb);
807                 return;
808         }
809 
810         if (likely(atomic_read(&skb->users) == 1))
811                 smp_rmb();
812         else if (likely(!atomic_dec_and_test(&skb->users)))
813                 return;
814         /* if reaching here SKB is ready to free */
815         trace_consume_skb(skb);
816 
817         /* if SKB is a clone, don't handle this case */
818         if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
819                 __kfree_skb(skb);
820                 return;
821         }
822 
823         _kfree_skb_defer(skb);
824 }
825 EXPORT_SYMBOL(napi_consume_skb);
826 
827 /* Make sure a field is enclosed inside headers_start/headers_end section */
828 #define CHECK_SKB_FIELD(field) \
829         BUILD_BUG_ON(offsetof(struct sk_buff, field) <          \
830                      offsetof(struct sk_buff, headers_start));  \
831         BUILD_BUG_ON(offsetof(struct sk_buff, field) >          \
832                      offsetof(struct sk_buff, headers_end));    \
833 
834 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
835 {
836         new->tstamp             = old->tstamp;
837         /* We do not copy old->sk */
838         new->dev                = old->dev;
839         memcpy(new->cb, old->cb, sizeof(old->cb));
840         skb_dst_copy(new, old);
841 #ifdef CONFIG_XFRM
842         new->sp                 = secpath_get(old->sp);
843 #endif
844         __nf_copy(new, old, false);
845 
846         /* Note : this field could be in headers_start/headers_end section
847          * It is not yet because we do not want to have a 16 bit hole
848          */
849         new->queue_mapping = old->queue_mapping;
850 
851         memcpy(&new->headers_start, &old->headers_start,
852                offsetof(struct sk_buff, headers_end) -
853                offsetof(struct sk_buff, headers_start));
854         CHECK_SKB_FIELD(protocol);
855         CHECK_SKB_FIELD(csum);
856         CHECK_SKB_FIELD(hash);
857         CHECK_SKB_FIELD(priority);
858         CHECK_SKB_FIELD(skb_iif);
859         CHECK_SKB_FIELD(vlan_proto);
860         CHECK_SKB_FIELD(vlan_tci);
861         CHECK_SKB_FIELD(transport_header);
862         CHECK_SKB_FIELD(network_header);
863         CHECK_SKB_FIELD(mac_header);
864         CHECK_SKB_FIELD(inner_protocol);
865         CHECK_SKB_FIELD(inner_transport_header);
866         CHECK_SKB_FIELD(inner_network_header);
867         CHECK_SKB_FIELD(inner_mac_header);
868         CHECK_SKB_FIELD(mark);
869 #ifdef CONFIG_NETWORK_SECMARK
870         CHECK_SKB_FIELD(secmark);
871 #endif
872 #ifdef CONFIG_NET_RX_BUSY_POLL
873         CHECK_SKB_FIELD(napi_id);
874 #endif
875 #ifdef CONFIG_XPS
876         CHECK_SKB_FIELD(sender_cpu);
877 #endif
878 #ifdef CONFIG_NET_SCHED
879         CHECK_SKB_FIELD(tc_index);
880 #ifdef CONFIG_NET_CLS_ACT
881         CHECK_SKB_FIELD(tc_verd);
882 #endif
883 #endif
884 
885 }
886 
887 /*
888  * You should not add any new code to this function.  Add it to
889  * __copy_skb_header above instead.
890  */
891 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
892 {
893 #define C(x) n->x = skb->x
894 
895         n->next = n->prev = NULL;
896         n->sk = NULL;
897         __copy_skb_header(n, skb);
898 
899         C(len);
900         C(data_len);
901         C(mac_len);
902         n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
903         n->cloned = 1;
904         n->nohdr = 0;
905         n->destructor = NULL;
906         C(tail);
907         C(end);
908         C(head);
909         C(head_frag);
910         C(data);
911         C(truesize);
912         atomic_set(&n->users, 1);
913 
914         atomic_inc(&(skb_shinfo(skb)->dataref));
915         skb->cloned = 1;
916 
917         return n;
918 #undef C
919 }
920 
921 /**
922  *      skb_morph       -       morph one skb into another
923  *      @dst: the skb to receive the contents
924  *      @src: the skb to supply the contents
925  *
926  *      This is identical to skb_clone except that the target skb is
927  *      supplied by the user.
928  *
929  *      The target skb is returned upon exit.
930  */
931 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
932 {
933         skb_release_all(dst);
934         return __skb_clone(dst, src);
935 }
936 EXPORT_SYMBOL_GPL(skb_morph);
937 
938 /**
939  *      skb_copy_ubufs  -       copy userspace skb frags buffers to kernel
940  *      @skb: the skb to modify
941  *      @gfp_mask: allocation priority
942  *
943  *      This must be called on SKBTX_DEV_ZEROCOPY skb.
944  *      It will copy all frags into kernel and drop the reference
945  *      to userspace pages.
946  *
947  *      If this function is called from an interrupt gfp_mask() must be
948  *      %GFP_ATOMIC.
949  *
950  *      Returns 0 on success or a negative error code on failure
951  *      to allocate kernel memory to copy to.
952  */
953 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
954 {
955         int i;
956         int num_frags = skb_shinfo(skb)->nr_frags;
957         struct page *page, *head = NULL;
958         struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;
959 
960         for (i = 0; i < num_frags; i++) {
961                 u8 *vaddr;
962                 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
963 
964                 page = alloc_page(gfp_mask);
965                 if (!page) {
966                         while (head) {
967                                 struct page *next = (struct page *)page_private(head);
968                                 put_page(head);
969                                 head = next;
970                         }
971                         return -ENOMEM;
972                 }
973                 vaddr = kmap_atomic(skb_frag_page(f));
974                 memcpy(page_address(page),
975                        vaddr + f->page_offset, skb_frag_size(f));
976                 kunmap_atomic(vaddr);
977                 set_page_private(page, (unsigned long)head);
978                 head = page;
979         }
980 
981         /* skb frags release userspace buffers */
982         for (i = 0; i < num_frags; i++)
983                 skb_frag_unref(skb, i);
984 
985         uarg->callback(uarg, false);
986 
987         /* skb frags point to kernel buffers */
988         for (i = num_frags - 1; i >= 0; i--) {
989                 __skb_fill_page_desc(skb, i, head, 0,
990                                      skb_shinfo(skb)->frags[i].size);
991                 head = (struct page *)page_private(head);
992         }
993 
994         skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
995         return 0;
996 }
997 EXPORT_SYMBOL_GPL(skb_copy_ubufs);
998 
999 /**
1000  *      skb_clone       -       duplicate an sk_buff
1001  *      @skb: buffer to clone
1002  *      @gfp_mask: allocation priority
1003  *
1004  *      Duplicate an &sk_buff. The new one is not owned by a socket. Both
1005  *      copies share the same packet data but not structure. The new
1006  *      buffer has a reference count of 1. If the allocation fails the
1007  *      function returns %NULL otherwise the new buffer is returned.
1008  *
1009  *      If this function is called from an interrupt gfp_mask() must be
1010  *      %GFP_ATOMIC.
1011  */
1012 
1013 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
1014 {
1015         struct sk_buff_fclones *fclones = container_of(skb,
1016                                                        struct sk_buff_fclones,
1017                                                        skb1);
1018         struct sk_buff *n;
1019 
1020         if (skb_orphan_frags(skb, gfp_mask))
1021                 return NULL;
1022 
1023         if (skb->fclone == SKB_FCLONE_ORIG &&
1024             atomic_read(&fclones->fclone_ref) == 1) {
1025                 n = &fclones->skb2;
1026                 atomic_set(&fclones->fclone_ref, 2);
1027         } else {
1028                 if (skb_pfmemalloc(skb))
1029                         gfp_mask |= __GFP_MEMALLOC;
1030 
1031                 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
1032                 if (!n)
1033                         return NULL;
1034 
1035                 kmemcheck_annotate_bitfield(n, flags1);
1036                 n->fclone = SKB_FCLONE_UNAVAILABLE;
1037         }
1038 
1039         return __skb_clone(n, skb);
1040 }
1041 EXPORT_SYMBOL(skb_clone);
1042 
1043 static void skb_headers_offset_update(struct sk_buff *skb, int off)
1044 {
1045         /* Only adjust this if it actually is csum_start rather than csum */
1046         if (skb->ip_summed == CHECKSUM_PARTIAL)
1047                 skb->csum_start += off;
1048         /* {transport,network,mac}_header and tail are relative to skb->head */
1049         skb->transport_header += off;
1050         skb->network_header   += off;
1051         if (skb_mac_header_was_set(skb))
1052                 skb->mac_header += off;
1053         skb->inner_transport_header += off;
1054         skb->inner_network_header += off;
1055         skb->inner_mac_header += off;
1056 }
1057 
1058 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
1059 {
1060         __copy_skb_header(new, old);
1061 
1062         skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
1063         skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
1064         skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
1065 }
1066 
1067 static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
1068 {
1069         if (skb_pfmemalloc(skb))
1070                 return SKB_ALLOC_RX;
1071         return 0;
1072 }
1073 
1074 /**
1075  *      skb_copy        -       create private copy of an sk_buff
1076  *      @skb: buffer to copy
1077  *      @gfp_mask: allocation priority
1078  *
1079  *      Make a copy of both an &sk_buff and its data. This is used when the
1080  *      caller wishes to modify the data and needs a private copy of the
1081  *      data to alter. Returns %NULL on failure or the pointer to the buffer
1082  *      on success. The returned buffer has a reference count of 1.
1083  *
1084  *      As by-product this function converts non-linear &sk_buff to linear
1085  *      one, so that &sk_buff becomes completely private and caller is allowed
1086  *      to modify all the data of returned buffer. This means that this
1087  *      function is not recommended for use in circumstances when only
1088  *      header is going to be modified. Use pskb_copy() instead.
1089  */
1090 
1091 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
1092 {
1093         int headerlen = skb_headroom(skb);
1094         unsigned int size = skb_end_offset(skb) + skb->data_len;
1095         struct sk_buff *n = __alloc_skb(size, gfp_mask,
1096                                         skb_alloc_rx_flag(skb), NUMA_NO_NODE);
1097 
1098         if (!n)
1099                 return NULL;
1100 
1101         /* Set the data pointer */
1102         skb_reserve(n, headerlen);
1103         /* Set the tail pointer and length */
1104         skb_put(n, skb->len);
1105 
1106         if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
1107                 BUG();
1108 
1109         copy_skb_header(n, skb);
1110         return n;
1111 }
1112 EXPORT_SYMBOL(skb_copy);
1113 
1114 /**
1115  *      __pskb_copy_fclone      -  create copy of an sk_buff with private head.
1116  *      @skb: buffer to copy
1117  *      @headroom: headroom of new skb
1118  *      @gfp_mask: allocation priority
1119  *      @fclone: if true allocate the copy of the skb from the fclone
1120  *      cache instead of the head cache; it is recommended to set this
1121  *      to true for the cases where the copy will likely be cloned
1122  *
1123  *      Make a copy of both an &sk_buff and part of its data, located
1124  *      in header. Fragmented data remain shared. This is used when
1125  *      the caller wishes to modify only header of &sk_buff and needs
1126  *      private copy of the header to alter. Returns %NULL on failure
1127  *      or the pointer to the buffer on success.
1128  *      The returned buffer has a reference count of 1.
1129  */
1130 
1131 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
1132                                    gfp_t gfp_mask, bool fclone)
1133 {
1134         unsigned int size = skb_headlen(skb) + headroom;
1135         int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
1136         struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
1137 
1138         if (!n)
1139                 goto out;
1140 
1141         /* Set the data pointer */
1142         skb_reserve(n, headroom);
1143         /* Set the tail pointer and length */
1144         skb_put(n, skb_headlen(skb));
1145         /* Copy the bytes */
1146         skb_copy_from_linear_data(skb, n->data, n->len);
1147 
1148         n->truesize += skb->data_len;
1149         n->data_len  = skb->data_len;
1150         n->len       = skb->len;
1151 
1152         if (skb_shinfo(skb)->nr_frags) {
1153                 int i;
1154 
1155                 if (skb_orphan_frags(skb, gfp_mask)) {
1156                         kfree_skb(n);
1157                         n = NULL;
1158                         goto out;
1159                 }
1160                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1161                         skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
1162                         skb_frag_ref(skb, i);
1163                 }
1164                 skb_shinfo(n)->nr_frags = i;
1165         }
1166 
1167         if (skb_has_frag_list(skb)) {
1168                 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
1169                 skb_clone_fraglist(n);
1170         }
1171 
1172         copy_skb_header(n, skb);
1173 out:
1174         return n;
1175 }
1176 EXPORT_SYMBOL(__pskb_copy_fclone);
1177 
1178 /**
1179  *      pskb_expand_head - reallocate header of &sk_buff
1180  *      @skb: buffer to reallocate
1181  *      @nhead: room to add at head
1182  *      @ntail: room to add at tail
1183  *      @gfp_mask: allocation priority
1184  *
1185  *      Expands (or creates identical copy, if @nhead and @ntail are zero)
1186  *      header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
1187  *      reference count of 1. Returns zero in the case of success or error,
1188  *      if expansion failed. In the last case, &sk_buff is not changed.
1189  *
1190  *      All the pointers pointing into skb header may change and must be
1191  *      reloaded after call to this function.
1192  */
1193 
1194 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
1195                      gfp_t gfp_mask)
1196 {
1197         int i;
1198         u8 *data;
1199         int size = nhead + skb_end_offset(skb) + ntail;
1200         long off;
1201 
1202         BUG_ON(nhead < 0);
1203 
1204         if (skb_shared(skb))
1205                 BUG();
1206 
1207         size = SKB_DATA_ALIGN(size);
1208 
1209         if (skb_pfmemalloc(skb))
1210                 gfp_mask |= __GFP_MEMALLOC;
1211         data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
1212                                gfp_mask, NUMA_NO_NODE, NULL);
1213         if (!data)
1214                 goto nodata;
1215         size = SKB_WITH_OVERHEAD(ksize(data));
1216 
1217         /* Copy only real data... and, alas, header. This should be
1218          * optimized for the cases when header is void.
1219          */
1220         memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
1221 
1222         memcpy((struct skb_shared_info *)(data + size),
1223                skb_shinfo(skb),
1224                offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
1225 
1226         /*
1227          * if shinfo is shared we must drop the old head gracefully, but if it
1228          * is not we can just drop the old head and let the existing refcount
1229          * be since all we did is relocate the values
1230          */
1231         if (skb_cloned(skb)) {
1232                 /* copy this zero copy skb frags */
1233                 if (skb_orphan_frags(skb, gfp_mask))
1234                         goto nofrags;
1235                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1236                         skb_frag_ref(skb, i);
1237 
1238                 if (skb_has_frag_list(skb))
1239                         skb_clone_fraglist(skb);
1240 
1241                 skb_release_data(skb);
1242         } else {
1243                 skb_free_head(skb);
1244         }
1245         off = (data + nhead) - skb->head;
1246 
1247         skb->head     = data;
1248         skb->head_frag = 0;
1249         skb->data    += off;
1250 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1251         skb->end      = size;
1252         off           = nhead;
1253 #else
1254         skb->end      = skb->head + size;
1255 #endif
1256         skb->tail             += off;
1257         skb_headers_offset_update(skb, nhead);
1258         skb->cloned   = 0;
1259         skb->hdr_len  = 0;
1260         skb->nohdr    = 0;
1261         atomic_set(&skb_shinfo(skb)->dataref, 1);
1262         return 0;
1263 
1264 nofrags:
1265         kfree(data);
1266 nodata:
1267         return -ENOMEM;
1268 }
1269 EXPORT_SYMBOL(pskb_expand_head);
1270 
1271 /* Make private copy of skb with writable head and some headroom */
1272 
1273 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1274 {
1275         struct sk_buff *skb2;
1276         int delta = headroom - skb_headroom(skb);
1277 
1278         if (delta <= 0)
1279                 skb2 = pskb_copy(skb, GFP_ATOMIC);
1280         else {
1281                 skb2 = skb_clone(skb, GFP_ATOMIC);
1282                 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1283                                              GFP_ATOMIC)) {
1284                         kfree_skb(skb2);
1285                         skb2 = NULL;
1286                 }
1287         }
1288         return skb2;
1289 }
1290 EXPORT_SYMBOL(skb_realloc_headroom);
1291 
1292 /**
1293  *      skb_copy_expand -       copy and expand sk_buff
1294  *      @skb: buffer to copy
1295  *      @newheadroom: new free bytes at head
1296  *      @newtailroom: new free bytes at tail
1297  *      @gfp_mask: allocation priority
1298  *
1299  *      Make a copy of both an &sk_buff and its data and while doing so
1300  *      allocate additional space.
1301  *
1302  *      This is used when the caller wishes to modify the data and needs a
1303  *      private copy of the data to alter as well as more space for new fields.
1304  *      Returns %NULL on failure or the pointer to the buffer
1305  *      on success. The returned buffer has a reference count of 1.
1306  *
1307  *      You must pass %GFP_ATOMIC as the allocation priority if this function
1308  *      is called from an interrupt.
1309  */
1310 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
1311                                 int newheadroom, int newtailroom,
1312                                 gfp_t gfp_mask)
1313 {
1314         /*
1315          *      Allocate the copy buffer
1316          */
1317         struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
1318                                         gfp_mask, skb_alloc_rx_flag(skb),
1319                                         NUMA_NO_NODE);
1320         int oldheadroom = skb_headroom(skb);
1321         int head_copy_len, head_copy_off;
1322 
1323         if (!n)
1324                 return NULL;
1325 
1326         skb_reserve(n, newheadroom);
1327 
1328         /* Set the tail pointer and length */
1329         skb_put(n, skb->len);
1330 
1331         head_copy_len = oldheadroom;
1332         head_copy_off = 0;
1333         if (newheadroom <= head_copy_len)
1334                 head_copy_len = newheadroom;
1335         else
1336                 head_copy_off = newheadroom - head_copy_len;
1337 
1338         /* Copy the linear header and data. */
1339         if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1340                           skb->len + head_copy_len))
1341                 BUG();
1342 
1343         copy_skb_header(n, skb);
1344 
1345         skb_headers_offset_update(n, newheadroom - oldheadroom);
1346 
1347         return n;
1348 }
1349 EXPORT_SYMBOL(skb_copy_expand);
1350 
1351 /**
1352  *      skb_pad                 -       zero pad the tail of an skb
1353  *      @skb: buffer to pad
1354  *      @pad: space to pad
1355  *
1356  *      Ensure that a buffer is followed by a padding area that is zero
1357  *      filled. Used by network drivers which may DMA or transfer data
1358  *      beyond the buffer end onto the wire.
1359  *
1360  *      May return error in out of memory cases. The skb is freed on error.
1361  */
1362 
1363 int skb_pad(struct sk_buff *skb, int pad)
1364 {
1365         int err;
1366         int ntail;
1367 
1368         /* If the skbuff is non linear tailroom is always zero.. */
1369         if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1370                 memset(skb->data+skb->len, 0, pad);
1371                 return 0;
1372         }
1373 
1374         ntail = skb->data_len + pad - (skb->end - skb->tail);
1375         if (likely(skb_cloned(skb) || ntail > 0)) {
1376                 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1377                 if (unlikely(err))
1378                         goto free_skb;
1379         }
1380 
1381         /* FIXME: The use of this function with non-linear skb's really needs
1382          * to be audited.
1383          */
1384         err = skb_linearize(skb);
1385         if (unlikely(err))
1386                 goto free_skb;
1387 
1388         memset(skb->data + skb->len, 0, pad);
1389         return 0;
1390 
1391 free_skb:
1392         kfree_skb(skb);
1393         return err;
1394 }
1395 EXPORT_SYMBOL(skb_pad);
1396 
1397 /**
1398  *      pskb_put - add data to the tail of a potentially fragmented buffer
1399  *      @skb: start of the buffer to use
1400  *      @tail: tail fragment of the buffer to use
1401  *      @len: amount of data to add
1402  *
1403  *      This function extends the used data area of the potentially
1404  *      fragmented buffer. @tail must be the last fragment of @skb -- or
1405  *      @skb itself. If this would exceed the total buffer size the kernel
1406  *      will panic. A pointer to the first byte of the extra data is
1407  *      returned.
1408  */
1409 
1410 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
1411 {
1412         if (tail != skb) {
1413                 skb->data_len += len;
1414                 skb->len += len;
1415         }
1416         return skb_put(tail, len);
1417 }
1418 EXPORT_SYMBOL_GPL(pskb_put);
1419 
1420 /**
1421  *      skb_put - add data to a buffer
1422  *      @skb: buffer to use
1423  *      @len: amount of data to add
1424  *
1425  *      This function extends the used data area of the buffer. If this would
1426  *      exceed the total buffer size the kernel will panic. A pointer to the
1427  *      first byte of the extra data is returned.
1428  */
1429 unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
1430 {
1431         unsigned char *tmp = skb_tail_pointer(skb);
1432         SKB_LINEAR_ASSERT(skb);
1433         skb->tail += len;
1434         skb->len  += len;
1435         if (unlikely(skb->tail > skb->end))
1436                 skb_over_panic(skb, len, __builtin_return_address(0));
1437         return tmp;
1438 }
1439 EXPORT_SYMBOL(skb_put);
1440 
1441 /**
1442  *      skb_push - add data to the start of a buffer
1443  *      @skb: buffer to use
1444  *      @len: amount of data to add
1445  *
1446  *      This function extends the used data area of the buffer at the buffer
1447  *      start. If this would exceed the total buffer headroom the kernel will
1448  *      panic. A pointer to the first byte of the extra data is returned.
1449  */
1450 unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1451 {
1452         skb->data -= len;
1453         skb->len  += len;
1454         if (unlikely(skb->data<skb->head))
1455                 skb_under_panic(skb, len, __builtin_return_address(0));
1456         return skb->data;
1457 }
1458 EXPORT_SYMBOL(skb_push);
1459 
1460 /**
1461  *      skb_pull - remove data from the start of a buffer
1462  *      @skb: buffer to use
1463  *      @len: amount of data to remove
1464  *
1465  *      This function removes data from the start of a buffer, returning
1466  *      the memory to the headroom. A pointer to the next data in the buffer
1467  *      is returned. Once the data has been pulled future pushes will overwrite
1468  *      the old data.
1469  */
1470 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1471 {
1472         return skb_pull_inline(skb, len);
1473 }
1474 EXPORT_SYMBOL(skb_pull);
1475 
1476 /**
1477  *      skb_trim - remove end from a buffer
1478  *      @skb: buffer to alter
1479  *      @len: new length
1480  *
1481  *      Cut the length of a buffer down by removing data from the tail. If
1482  *      the buffer is already under the length specified it is not modified.
1483  *      The skb must be linear.
1484  */
1485 void skb_trim(struct sk_buff *skb, unsigned int len)
1486 {
1487         if (skb->len > len)
1488                 __skb_trim(skb, len);
1489 }
1490 EXPORT_SYMBOL(skb_trim);
1491 
1492 /* Trims skb to length len. It can change skb pointers.
1493  */
1494 
1495 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1496 {
1497         struct sk_buff **fragp;
1498         struct sk_buff *frag;
1499         int offset = skb_headlen(skb);
1500         int nfrags = skb_shinfo(skb)->nr_frags;
1501         int i;
1502         int err;
1503 
1504         if (skb_cloned(skb) &&
1505             unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1506                 return err;
1507 
1508         i = 0;
1509         if (offset >= len)
1510                 goto drop_pages;
1511 
1512         for (; i < nfrags; i++) {
1513                 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
1514 
1515                 if (end < len) {
1516                         offset = end;
1517                         continue;
1518                 }
1519 
1520                 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
1521 
1522 drop_pages:
1523                 skb_shinfo(skb)->nr_frags = i;
1524 
1525                 for (; i < nfrags; i++)
1526                         skb_frag_unref(skb, i);
1527 
1528                 if (skb_has_frag_list(skb))
1529                         skb_drop_fraglist(skb);
1530                 goto done;
1531         }
1532 
1533         for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1534              fragp = &frag->next) {
1535                 int end = offset + frag->len;
1536 
1537                 if (skb_shared(frag)) {
1538                         struct sk_buff *nfrag;
1539 
1540                         nfrag = skb_clone(frag, GFP_ATOMIC);
1541                         if (unlikely(!nfrag))
1542                                 return -ENOMEM;
1543 
1544                         nfrag->next = frag->next;
1545                         consume_skb(frag);
1546                         frag = nfrag;
1547                         *fragp = frag;
1548                 }
1549 
1550                 if (end < len) {
1551                         offset = end;
1552                         continue;
1553                 }
1554 
1555                 if (end > len &&
1556                     unlikely((err = pskb_trim(frag, len - offset))))
1557                         return err;
1558 
1559                 if (frag->next)
1560                         skb_drop_list(&frag->next);
1561                 break;
1562         }
1563 
1564 done:
1565         if (len > skb_headlen(skb)) {
1566                 skb->data_len -= skb->len - len;
1567                 skb->len       = len;
1568         } else {
1569                 skb->len       = len;
1570                 skb->data_len  = 0;
1571                 skb_set_tail_pointer(skb, len);
1572         }
1573 
1574         return 0;
1575 }
1576 EXPORT_SYMBOL(___pskb_trim);
1577 
1578 /**
1579  *      __pskb_pull_tail - advance tail of skb header
1580  *      @skb: buffer to reallocate
1581  *      @delta: number of bytes to advance tail
1582  *
1583  *      The function makes a sense only on a fragmented &sk_buff,
1584  *      it expands header moving its tail forward and copying necessary
1585  *      data from fragmented part.
1586  *
1587  *      &sk_buff MUST have reference count of 1.
1588  *
1589  *      Returns %NULL (and &sk_buff does not change) if pull failed
1590  *      or value of new tail of skb in the case of success.
1591  *
1592  *      All the pointers pointing into skb header may change and must be
1593  *      reloaded after call to this function.
1594  */
1595 
1596 /* Moves tail of skb head forward, copying data from fragmented part,
1597  * when it is necessary.
1598  * 1. It may fail due to malloc failure.
1599  * 2. It may change skb pointers.
1600  *
1601  * It is pretty complicated. Luckily, it is called only in exceptional cases.
1602  */
1603 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1604 {
1605         /* If skb has not enough free space at tail, get new one
1606          * plus 128 bytes for future expansions. If we have enough
1607          * room at tail, reallocate without expansion only if skb is cloned.
1608          */
1609         int i, k, eat = (skb->tail + delta) - skb->end;
1610 
1611         if (eat > 0 || skb_cloned(skb)) {
1612                 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1613                                      GFP_ATOMIC))
1614                         return NULL;
1615         }
1616 
1617         if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1618                 BUG();
1619 
1620         /* Optimization: no fragments, no reasons to preestimate
1621          * size of pulled pages. Superb.
1622          */
1623         if (!skb_has_frag_list(skb))
1624                 goto pull_pages;
1625 
1626         /* Estimate size of pulled pages. */
1627         eat = delta;
1628         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1629                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1630 
1631                 if (size >= eat)
1632                         goto pull_pages;
1633                 eat -= size;
1634         }
1635 
1636         /* If we need update frag list, we are in troubles.
1637          * Certainly, it possible to add an offset to skb data,
1638          * but taking into account that pulling is expected to
1639          * be very rare operation, it is worth to fight against
1640          * further bloating skb head and crucify ourselves here instead.
1641          * Pure masohism, indeed. 8)8)
1642          */
1643         if (eat) {
1644                 struct sk_buff *list = skb_shinfo(skb)->frag_list;
1645                 struct sk_buff *clone = NULL;
1646                 struct sk_buff *insp = NULL;
1647 
1648                 do {
1649                         BUG_ON(!list);
1650 
1651                         if (list->len <= eat) {
1652                                 /* Eaten as whole. */
1653                                 eat -= list->len;
1654                                 list = list->next;
1655                                 insp = list;
1656                         } else {
1657                                 /* Eaten partially. */
1658 
1659                                 if (skb_shared(list)) {
1660                                         /* Sucks! We need to fork list. :-( */
1661                                         clone = skb_clone(list, GFP_ATOMIC);
1662                                         if (!clone)
1663                                                 return NULL;
1664                                         insp = list->next;
1665                                         list = clone;
1666                                 } else {
1667                                         /* This may be pulled without
1668                                          * problems. */
1669                                         insp = list;
1670                                 }
1671                                 if (!pskb_pull(list, eat)) {
1672                                         kfree_skb(clone);
1673                                         return NULL;
1674                                 }
1675                                 break;
1676                         }
1677                 } while (eat);
1678 
1679                 /* Free pulled out fragments. */
1680                 while ((list = skb_shinfo(skb)->frag_list) != insp) {
1681                         skb_shinfo(skb)->frag_list = list->next;
1682                         kfree_skb(list);
1683                 }
1684                 /* And insert new clone at head. */
1685                 if (clone) {
1686                         clone->next = list;
1687                         skb_shinfo(skb)->frag_list = clone;
1688                 }
1689         }
1690         /* Success! Now we may commit changes to skb data. */
1691 
1692 pull_pages:
1693         eat = delta;
1694         k = 0;
1695         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1696                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1697 
1698                 if (size <= eat) {
1699                         skb_frag_unref(skb, i);
1700                         eat -= size;
1701                 } else {
1702                         skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1703                         if (eat) {
1704                                 skb_shinfo(skb)->frags[k].page_offset += eat;
1705                                 skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
1706                                 eat = 0;
1707                         }
1708                         k++;
1709                 }
1710         }
1711         skb_shinfo(skb)->nr_frags = k;
1712 
1713         skb->tail     += delta;
1714         skb->data_len -= delta;
1715 
1716         return skb_tail_pointer(skb);
1717 }
1718 EXPORT_SYMBOL(__pskb_pull_tail);
1719 
1720 /**
1721  *      skb_copy_bits - copy bits from skb to kernel buffer
1722  *      @skb: source skb
1723  *      @offset: offset in source
1724  *      @to: destination buffer
1725  *      @len: number of bytes to copy
1726  *
1727  *      Copy the specified number of bytes from the source skb to the
1728  *      destination buffer.
1729  *
1730  *      CAUTION ! :
1731  *              If its prototype is ever changed,
1732  *              check arch/{*}/net/{*}.S files,
1733  *              since it is called from BPF assembly code.
1734  */
1735 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1736 {
1737         int start = skb_headlen(skb);
1738         struct sk_buff *frag_iter;
1739         int i, copy;
1740 
1741         if (offset > (int)skb->len - len)
1742                 goto fault;
1743 
1744         /* Copy header. */
1745         if ((copy = start - offset) > 0) {
1746                 if (copy > len)
1747                         copy = len;
1748                 skb_copy_from_linear_data_offset(skb, offset, to, copy);
1749                 if ((len -= copy) == 0)
1750                         return 0;
1751                 offset += copy;
1752                 to     += copy;
1753         }
1754 
1755         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1756                 int end;
1757                 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1758 
1759                 WARN_ON(start > offset + len);
1760 
1761                 end = start + skb_frag_size(f);
1762                 if ((copy = end - offset) > 0) {
1763                         u8 *vaddr;
1764 
1765                         if (copy > len)
1766                                 copy = len;
1767 
1768                         vaddr = kmap_atomic(skb_frag_page(f));
1769                         memcpy(to,
1770                                vaddr + f->page_offset + offset - start,
1771                                copy);
1772                         kunmap_atomic(vaddr);
1773 
1774                         if ((len -= copy) == 0)
1775                                 return 0;
1776                         offset += copy;
1777                         to     += copy;
1778                 }
1779                 start = end;
1780         }
1781 
1782         skb_walk_frags(skb, frag_iter) {
1783                 int end;
1784 
1785                 WARN_ON(start > offset + len);
1786 
1787                 end = start + frag_iter->len;
1788                 if ((copy = end - offset) > 0) {
1789                         if (copy > len)
1790                                 copy = len;
1791                         if (skb_copy_bits(frag_iter, offset - start, to, copy))
1792                                 goto fault;
1793                         if ((len -= copy) == 0)
1794                                 return 0;
1795                         offset += copy;
1796                         to     += copy;
1797                 }
1798                 start = end;
1799         }
1800 
1801         if (!len)
1802                 return 0;
1803 
1804 fault:
1805         return -EFAULT;
1806 }
1807 EXPORT_SYMBOL(skb_copy_bits);
1808 
1809 /*
1810  * Callback from splice_to_pipe(), if we need to release some pages
1811  * at the end of the spd in case we error'ed out in filling the pipe.
1812  */
1813 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1814 {
1815         put_page(spd->pages[i]);
1816 }
1817 
1818 static struct page *linear_to_page(struct page *page, unsigned int *len,
1819                                    unsigned int *offset,
1820                                    struct sock *sk)
1821 {
1822         struct page_frag *pfrag = sk_page_frag(sk);
1823 
1824         if (!sk_page_frag_refill(sk, pfrag))
1825                 return NULL;
1826 
1827         *len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
1828 
1829         memcpy(page_address(pfrag->page) + pfrag->offset,
1830                page_address(page) + *offset, *len);
1831         *offset = pfrag->offset;
1832         pfrag->offset += *len;
1833 
1834         return pfrag->page;
1835 }
1836 
1837 static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
1838                              struct page *page,
1839                              unsigned int offset)
1840 {
1841         return  spd->nr_pages &&
1842                 spd->pages[spd->nr_pages - 1] == page &&
1843                 (spd->partial[spd->nr_pages - 1].offset +
1844                  spd->partial[spd->nr_pages - 1].len == offset);
1845 }
1846 
1847 /*
1848  * Fill page/offset/length into spd, if it can hold more pages.
1849  */
1850 static bool spd_fill_page(struct splice_pipe_desc *spd,
1851                           struct pipe_inode_info *pipe, struct page *page,
1852                           unsigned int *len, unsigned int offset,
1853                           bool linear,
1854                           struct sock *sk)
1855 {
1856         if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
1857                 return true;
1858 
1859         if (linear) {
1860                 page = linear_to_page(page, len, &offset, sk);
1861                 if (!page)
1862                         return true;
1863         }
1864         if (spd_can_coalesce(spd, page, offset)) {
1865                 spd->partial[spd->nr_pages - 1].len += *len;
1866                 return false;
1867         }
1868         get_page(page);
1869         spd->pages[spd->nr_pages] = page;
1870         spd->partial[spd->nr_pages].len = *len;
1871         spd->partial[spd->nr_pages].offset = offset;
1872         spd->nr_pages++;
1873 
1874         return false;
1875 }
1876 
1877 static bool __splice_segment(struct page *page, unsigned int poff,
1878                              unsigned int plen, unsigned int *off,
1879                              unsigned int *len,
1880                              struct splice_pipe_desc *spd, bool linear,
1881                              struct sock *sk,
1882                              struct pipe_inode_info *pipe)
1883 {
1884         if (!*len)
1885                 return true;
1886 
1887         /* skip this segment if already processed */
1888         if (*off >= plen) {
1889                 *off -= plen;
1890                 return false;
1891         }
1892 
1893         /* ignore any bits we already processed */
1894         poff += *off;
1895         plen -= *off;
1896         *off = 0;
1897 
1898         do {
1899                 unsigned int flen = min(*len, plen);
1900 
1901                 if (spd_fill_page(spd, pipe, page, &flen, poff,
1902                                   linear, sk))
1903                         return true;
1904                 poff += flen;
1905                 plen -= flen;
1906                 *len -= flen;
1907         } while (*len && plen);
1908 
1909         return false;
1910 }
1911 
1912 /*
1913  * Map linear and fragment data from the skb to spd. It reports true if the
1914  * pipe is full or if we already spliced the requested length.
1915  */
1916 static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
1917                               unsigned int *offset, unsigned int *len,
1918                               struct splice_pipe_desc *spd, struct sock *sk)
1919 {
1920         int seg;
1921         struct sk_buff *iter;
1922 
1923         /* map the linear part :
1924          * If skb->head_frag is set, this 'linear' part is backed by a
1925          * fragment, and if the head is not shared with any clones then
1926          * we can avoid a copy since we own the head portion of this page.
1927          */
1928         if (__splice_segment(virt_to_page(skb->data),
1929                              (unsigned long) skb->data & (PAGE_SIZE - 1),
1930                              skb_headlen(skb),
1931                              offset, len, spd,
1932                              skb_head_is_locked(skb),
1933                              sk, pipe))
1934                 return true;
1935 
1936         /*
1937          * then map the fragments
1938          */
1939         for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1940                 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1941 
1942                 if (__splice_segment(skb_frag_page(f),
1943                                      f->page_offset, skb_frag_size(f),
1944                                      offset, len, spd, false, sk, pipe))
1945                         return true;
1946         }
1947 
1948         skb_walk_frags(skb, iter) {
1949                 if (*offset >= iter->len) {
1950                         *offset -= iter->len;
1951                         continue;
1952                 }
1953                 /* __skb_splice_bits() only fails if the output has no room
1954                  * left, so no point in going over the frag_list for the error
1955                  * case.
1956                  */
1957                 if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
1958                         return true;
1959         }
1960 
1961         return false;
1962 }
1963 
1964 ssize_t skb_socket_splice(struct sock *sk,
1965                           struct pipe_inode_info *pipe,
1966                           struct splice_pipe_desc *spd)
1967 {
1968         int ret;
1969 
1970         /* Drop the socket lock, otherwise we have reverse
1971          * locking dependencies between sk_lock and i_mutex
1972          * here as compared to sendfile(). We enter here
1973          * with the socket lock held, and splice_to_pipe() will
1974          * grab the pipe inode lock. For sendfile() emulation,
1975          * we call into ->sendpage() with the i_mutex lock held
1976          * and networking will grab the socket lock.
1977          */
1978         release_sock(sk);
1979         ret = splice_to_pipe(pipe, spd);
1980         lock_sock(sk);
1981 
1982         return ret;
1983 }
1984 
1985 /*
1986  * Map data from the skb to a pipe. Should handle both the linear part,
1987  * the fragments, and the frag list.
1988  */
1989 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
1990                     struct pipe_inode_info *pipe, unsigned int tlen,
1991                     unsigned int flags,
1992                     ssize_t (*splice_cb)(struct sock *,
1993                                          struct pipe_inode_info *,
1994                                          struct splice_pipe_desc *))
1995 {
1996         struct partial_page partial[MAX_SKB_FRAGS];
1997         struct page *pages[MAX_SKB_FRAGS];
1998         struct splice_pipe_desc spd = {
1999                 .pages = pages,
2000                 .partial = partial,
2001                 .nr_pages_max = MAX_SKB_FRAGS,
2002                 .flags = flags,
2003                 .ops = &nosteal_pipe_buf_ops,
2004                 .spd_release = sock_spd_release,
2005         };
2006         int ret = 0;
2007 
2008         __skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
2009 
2010         if (spd.nr_pages)
2011                 ret = splice_cb(sk, pipe, &spd);
2012 
2013         return ret;
2014 }
2015 EXPORT_SYMBOL_GPL(skb_splice_bits);
2016 
2017 /**
2018  *      skb_store_bits - store bits from kernel buffer to skb
2019  *      @skb: destination buffer
2020  *      @offset: offset in destination
2021  *      @from: source buffer
2022  *      @len: number of bytes to copy
2023  *
2024  *      Copy the specified number of bytes from the source buffer to the
2025  *      destination skb.  This function handles all the messy bits of
2026  *      traversing fragment lists and such.
2027  */
2028 
2029 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
2030 {
2031         int start = skb_headlen(skb);
2032         struct sk_buff *frag_iter;
2033         int i, copy;
2034 
2035         if (offset > (int)skb->len - len)
2036                 goto fault;
2037 
2038         if ((copy = start - offset) > 0) {
2039                 if (copy > len)
2040                         copy = len;
2041                 skb_copy_to_linear_data_offset(skb, offset, from, copy);
2042                 if ((len -= copy) == 0)
2043                         return 0;
2044                 offset += copy;
2045                 from += copy;
2046         }
2047 
2048         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2049                 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2050                 int end;
2051 
2052                 WARN_ON(start > offset + len);
2053 
2054                 end = start + skb_frag_size(frag);
2055                 if ((copy = end - offset) > 0) {
2056                         u8 *vaddr;
2057 
2058                         if (copy > len)
2059                                 copy = len;
2060 
2061                         vaddr = kmap_atomic(skb_frag_page(frag));
2062                         memcpy(vaddr + frag->page_offset + offset - start,
2063                                from, copy);
2064                         kunmap_atomic(vaddr);
2065 
2066                         if ((len -= copy) == 0)
2067                                 return 0;
2068                         offset += copy;
2069                         from += copy;
2070                 }
2071                 start = end;
2072         }
2073 
2074         skb_walk_frags(skb, frag_iter) {
2075                 int end;
2076 
2077                 WARN_ON(start > offset + len);
2078 
2079                 end = start + frag_iter->len;
2080                 if ((copy = end - offset) > 0) {
2081                         if (copy > len)
2082                                 copy = len;
2083                         if (skb_store_bits(frag_iter, offset - start,
2084                                            from, copy))
2085                                 goto fault;
2086                         if ((len -= copy) == 0)
2087                                 return 0;
2088                         offset += copy;
2089                         from += copy;
2090                 }
2091                 start = end;
2092         }
2093         if (!len)
2094                 return 0;
2095 
2096 fault:
2097         return -EFAULT;
2098 }
2099 EXPORT_SYMBOL(skb_store_bits);
2100 
2101 /* Checksum skb data. */
2102 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2103                       __wsum csum, const struct skb_checksum_ops *ops)
2104 {
2105         int start = skb_headlen(skb);
2106         int i, copy = start - offset;
2107         struct sk_buff *frag_iter;
2108         int pos = 0;
2109 
2110         /* Checksum header. */
2111         if (copy > 0) {
2112                 if (copy > len)
2113                         copy = len;
2114                 csum = ops->update(skb->data + offset, copy, csum);
2115                 if ((len -= copy) == 0)
2116                         return csum;
2117                 offset += copy;
2118                 pos     = copy;
2119         }
2120 
2121         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2122                 int end;
2123                 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2124 
2125                 WARN_ON(start > offset + len);
2126 
2127                 end = start + skb_frag_size(frag);
2128                 if ((copy = end - offset) > 0) {
2129                         __wsum csum2;
2130                         u8 *vaddr;
2131 
2132                         if (copy > len)
2133                                 copy = len;
2134                         vaddr = kmap_atomic(skb_frag_page(frag));
2135                         csum2 = ops->update(vaddr + frag->page_offset +
2136                                             offset - start, copy, 0);
2137                         kunmap_atomic(vaddr);
2138                         csum = ops->combine(csum, csum2, pos, copy);
2139                         if (!(len -= copy))
2140                                 return csum;
2141                         offset += copy;
2142                         pos    += copy;
2143                 }
2144                 start = end;
2145         }
2146 
2147         skb_walk_frags(skb, frag_iter) {
2148                 int end;
2149 
2150                 WARN_ON(start > offset + len);
2151 
2152                 end = start + frag_iter->len;
2153                 if ((copy = end - offset) > 0) {
2154                         __wsum csum2;
2155                         if (copy > len)
2156                                 copy = len;
2157                         csum2 = __skb_checksum(frag_iter, offset - start,
2158                                                copy, 0, ops);
2159                         csum = ops->combine(csum, csum2, pos, copy);
2160                         if ((len -= copy) == 0)
2161                                 return csum;
2162                         offset += copy;
2163                         pos    += copy;
2164                 }
2165                 start = end;
2166         }
2167         BUG_ON(len);
2168 
2169         return csum;
2170 }
2171 EXPORT_SYMBOL(__skb_checksum);
2172 
2173 __wsum skb_checksum(const struct sk_buff *skb, int offset,
2174                     int len, __wsum csum)
2175 {
2176         const struct skb_checksum_ops ops = {
2177                 .update  = csum_partial_ext,
2178                 .combine = csum_block_add_ext,
2179         };
2180 
2181         return __skb_checksum(skb, offset, len, csum, &ops);
2182 }
2183 EXPORT_SYMBOL(skb_checksum);
2184 
2185 /* Both of above in one bottle. */
2186 
2187 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
2188                                     u8 *to, int len, __wsum csum)
2189 {
2190         int start = skb_headlen(skb);
2191         int i, copy = start - offset;
2192         struct sk_buff *frag_iter;
2193         int pos = 0;
2194 
2195         /* Copy header. */
2196         if (copy > 0) {
2197                 if (copy > len)
2198                         copy = len;
2199                 csum = csum_partial_copy_nocheck(skb->data + offset, to,
2200                                                  copy, csum);
2201                 if ((len -= copy) == 0)
2202                         return csum;
2203                 offset += copy;
2204                 to     += copy;
2205                 pos     = copy;
2206         }
2207 
2208         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2209                 int end;
2210 
2211                 WARN_ON(start > offset + len);
2212 
2213                 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2214                 if ((copy = end - offset) > 0) {
2215                         __wsum csum2;
2216                         u8 *vaddr;
2217                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2218 
2219                         if (copy > len)
2220                                 copy = len;
2221                         vaddr = kmap_atomic(skb_frag_page(frag));
2222                         csum2 = csum_partial_copy_nocheck(vaddr +
2223                                                           frag->page_offset +
2224                                                           offset - start, to,
2225                                                           copy, 0);
2226                         kunmap_atomic(vaddr);
2227                         csum = csum_block_add(csum, csum2, pos);
2228                         if (!(len -= copy))
2229                                 return csum;
2230                         offset += copy;
2231                         to     += copy;
2232                         pos    += copy;
2233                 }
2234                 start = end;
2235         }
2236 
2237         skb_walk_frags(skb, frag_iter) {
2238                 __wsum csum2;
2239                 int end;
2240 
2241                 WARN_ON(start > offset + len);
2242 
2243                 end = start + frag_iter->len;
2244                 if ((copy = end - offset) > 0) {
2245                         if (copy > len)
2246                                 copy = len;
2247                         csum2 = skb_copy_and_csum_bits(frag_iter,
2248                                                        offset - start,
2249                                                        to, copy, 0);
2250                         csum = csum_block_add(csum, csum2, pos);
2251                         if ((len -= copy) == 0)
2252                                 return csum;
2253                         offset += copy;
2254                         to     += copy;
2255                         pos    += copy;
2256                 }
2257                 start = end;
2258         }
2259         BUG_ON(len);
2260         return csum;
2261 }
2262 EXPORT_SYMBOL(skb_copy_and_csum_bits);
2263 
2264  /**
2265  *      skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
2266  *      @from: source buffer
2267  *
2268  *      Calculates the amount of linear headroom needed in the 'to' skb passed
2269  *      into skb_zerocopy().
2270  */
2271 unsigned int
2272 skb_zerocopy_headlen(const struct sk_buff *from)
2273 {
2274         unsigned int hlen = 0;
2275 
2276         if (!from->head_frag ||
2277             skb_headlen(from) < L1_CACHE_BYTES ||
2278             skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
2279                 hlen = skb_headlen(from);
2280 
2281         if (skb_has_frag_list(from))
2282                 hlen = from->len;
2283 
2284         return hlen;
2285 }
2286 EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
2287 
2288 /**
2289  *      skb_zerocopy - Zero copy skb to skb
2290  *      @to: destination buffer
2291  *      @from: source buffer
2292  *      @len: number of bytes to copy from source buffer
2293  *      @hlen: size of linear headroom in destination buffer
2294  *
2295  *      Copies up to `len` bytes from `from` to `to` by creating references
2296  *      to the frags in the source buffer.
2297  *
2298  *      The `hlen` as calculated by skb_zerocopy_headlen() specifies the
2299  *      headroom in the `to` buffer.
2300  *
2301  *      Return value:
2302  *      0: everything is OK
2303  *      -ENOMEM: couldn't orphan frags of @from due to lack of memory
2304  *      -EFAULT: skb_copy_bits() found some problem with skb geometry
2305  */
2306 int
2307 skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
2308 {
2309         int i, j = 0;
2310         int plen = 0; /* length of skb->head fragment */
2311         int ret;
2312         struct page *page;
2313         unsigned int offset;
2314 
2315         BUG_ON(!from->head_frag && !hlen);
2316 
2317         /* dont bother with small payloads */
2318         if (len <= skb_tailroom(to))
2319                 return skb_copy_bits(from, 0, skb_put(to, len), len);
2320 
2321         if (hlen) {
2322                 ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
2323                 if (unlikely(ret))
2324                         return ret;
2325                 len -= hlen;
2326         } else {
2327                 plen = min_t(int, skb_headlen(from), len);
2328                 if (plen) {
2329                         page = virt_to_head_page(from->head);
2330                         offset = from->data - (unsigned char *)page_address(page);
2331                         __skb_fill_page_desc(to, 0, page, offset, plen);
2332                         get_page(page);
2333                         j = 1;
2334                         len -= plen;
2335                 }
2336         }
2337 
2338         to->truesize += len + plen;
2339         to->len += len + plen;
2340         to->data_len += len + plen;
2341 
2342         if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
2343                 skb_tx_error(from);
2344                 return -ENOMEM;
2345         }
2346 
2347         for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
2348                 if (!len)
2349                         break;
2350                 skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
2351                 skb_shinfo(to)->frags[j].size = min_t(int, skb_shinfo(to)->frags[j].size, len);
2352                 len -= skb_shinfo(to)->frags[j].size;
2353                 skb_frag_ref(to, j);
2354                 j++;
2355         }
2356         skb_shinfo(to)->nr_frags = j;
2357 
2358         return 0;
2359 }
2360 EXPORT_SYMBOL_GPL(skb_zerocopy);
2361 
2362 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
2363 {
2364         __wsum csum;
2365         long csstart;
2366 
2367         if (skb->ip_summed == CHECKSUM_PARTIAL)
2368                 csstart = skb_checksum_start_offset(skb);
2369         else
2370                 csstart = skb_headlen(skb);
2371 
2372         BUG_ON(csstart > skb_headlen(skb));
2373 
2374         skb_copy_from_linear_data(skb, to, csstart);
2375 
2376         csum = 0;
2377         if (csstart != skb->len)
2378                 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
2379                                               skb->len - csstart, 0);
2380 
2381         if (skb->ip_summed == CHECKSUM_PARTIAL) {
2382                 long csstuff = csstart + skb->csum_offset;
2383 
2384                 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
2385         }
2386 }
2387 EXPORT_SYMBOL(skb_copy_and_csum_dev);
2388 
2389 /**
2390  *      skb_dequeue - remove from the head of the queue
2391  *      @list: list to dequeue from
2392  *
2393  *      Remove the head of the list. The list lock is taken so the function
2394  *      may be used safely with other locking list functions. The head item is
2395  *      returned or %NULL if the list is empty.
2396  */
2397 
2398 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
2399 {
2400         unsigned long flags;
2401         struct sk_buff *result;
2402 
2403         spin_lock_irqsave(&list->lock, flags);
2404         result = __skb_dequeue(list);
2405         spin_unlock_irqrestore(&list->lock, flags);
2406         return result;
2407 }
2408 EXPORT_SYMBOL(skb_dequeue);
2409 
2410 /**
2411  *      skb_dequeue_tail - remove from the tail of the queue
2412  *      @list: list to dequeue from
2413  *
2414  *      Remove the tail of the list. The list lock is taken so the function
2415  *      may be used safely with other locking list functions. The tail item is
2416  *      returned or %NULL if the list is empty.
2417  */
2418 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
2419 {
2420         unsigned long flags;
2421         struct sk_buff *result;
2422 
2423         spin_lock_irqsave(&list->lock, flags);
2424         result = __skb_dequeue_tail(list);
2425         spin_unlock_irqrestore(&list->lock, flags);
2426         return result;
2427 }
2428 EXPORT_SYMBOL(skb_dequeue_tail);
2429 
2430 /**
2431  *      skb_queue_purge - empty a list
2432  *      @list: list to empty
2433  *
2434  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2435  *      the list and one reference dropped. This function takes the list
2436  *      lock and is atomic with respect to other list locking functions.
2437  */
2438 void skb_queue_purge(struct sk_buff_head *list)
2439 {
2440         struct sk_buff *skb;
2441         while ((skb = skb_dequeue(list)) != NULL)
2442                 kfree_skb(skb);
2443 }
2444 EXPORT_SYMBOL(skb_queue_purge);
2445 
2446 /**
2447  *      skb_queue_head - queue a buffer at the list head
2448  *      @list: list to use
2449  *      @newsk: buffer to queue
2450  *
2451  *      Queue a buffer at the start of the list. This function takes the
2452  *      list lock and can be used safely with other locking &sk_buff functions
2453  *      safely.
2454  *
2455  *      A buffer cannot be placed on two lists at the same time.
2456  */
2457 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
2458 {
2459         unsigned long flags;
2460 
2461         spin_lock_irqsave(&list->lock, flags);
2462         __skb_queue_head(list, newsk);
2463         spin_unlock_irqrestore(&list->lock, flags);
2464 }
2465 EXPORT_SYMBOL(skb_queue_head);
2466 
2467 /**
2468  *      skb_queue_tail - queue a buffer at the list tail
2469  *      @list: list to use
2470  *      @newsk: buffer to queue
2471  *
2472  *      Queue a buffer at the tail of the list. This function takes the
2473  *      list lock and can be used safely with other locking &sk_buff functions
2474  *      safely.
2475  *
2476  *      A buffer cannot be placed on two lists at the same time.
2477  */
2478 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
2479 {
2480         unsigned long flags;
2481 
2482         spin_lock_irqsave(&list->lock, flags);
2483         __skb_queue_tail(list, newsk);
2484         spin_unlock_irqrestore(&list->lock, flags);
2485 }
2486 EXPORT_SYMBOL(skb_queue_tail);
2487 
2488 /**
2489  *      skb_unlink      -       remove a buffer from a list
2490  *      @skb: buffer to remove
2491  *      @list: list to use
2492  *
2493  *      Remove a packet from a list. The list locks are taken and this
2494  *      function is atomic with respect to other list locked calls
2495  *
2496  *      You must know what list the SKB is on.
2497  */
2498 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
2499 {
2500         unsigned long flags;
2501 
2502         spin_lock_irqsave(&list->lock, flags);
2503         __skb_unlink(skb, list);
2504         spin_unlock_irqrestore(&list->lock, flags);
2505 }
2506 EXPORT_SYMBOL(skb_unlink);
2507 
2508 /**
2509  *      skb_append      -       append a buffer
2510  *      @old: buffer to insert after
2511  *      @newsk: buffer to insert
2512  *      @list: list to use
2513  *
2514  *      Place a packet after a given packet in a list. The list locks are taken
2515  *      and this function is atomic with respect to other list locked calls.
2516  *      A buffer cannot be placed on two lists at the same time.
2517  */
2518 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2519 {
2520         unsigned long flags;
2521 
2522         spin_lock_irqsave(&list->lock, flags);
2523         __skb_queue_after(list, old, newsk);
2524         spin_unlock_irqrestore(&list->lock, flags);
2525 }
2526 EXPORT_SYMBOL(skb_append);
2527 
2528 /**
2529  *      skb_insert      -       insert a buffer
2530  *      @old: buffer to insert before
2531  *      @newsk: buffer to insert
2532  *      @list: list to use
2533  *
2534  *      Place a packet before a given packet in a list. The list locks are
2535  *      taken and this function is atomic with respect to other list locked
2536  *      calls.
2537  *
2538  *      A buffer cannot be placed on two lists at the same time.
2539  */
2540 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2541 {
2542         unsigned long flags;
2543 
2544         spin_lock_irqsave(&list->lock, flags);
2545         __skb_insert(newsk, old->prev, old, list);
2546         spin_unlock_irqrestore(&list->lock, flags);
2547 }
2548 EXPORT_SYMBOL(skb_insert);
2549 
2550 static inline void skb_split_inside_header(struct sk_buff *skb,
2551                                            struct sk_buff* skb1,
2552                                            const u32 len, const int pos)
2553 {
2554         int i;
2555 
2556         skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2557                                          pos - len);
2558         /* And move data appendix as is. */
2559         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2560                 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2561 
2562         skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2563         skb_shinfo(skb)->nr_frags  = 0;
2564         skb1->data_len             = skb->data_len;
2565         skb1->len                  += skb1->data_len;
2566         skb->data_len              = 0;
2567         skb->len                   = len;
2568         skb_set_tail_pointer(skb, len);
2569 }
2570 
2571 static inline void skb_split_no_header(struct sk_buff *skb,
2572                                        struct sk_buff* skb1,
2573                                        const u32 len, int pos)
2574 {
2575         int i, k = 0;
2576         const int nfrags = skb_shinfo(skb)->nr_frags;
2577 
2578         skb_shinfo(skb)->nr_frags = 0;
2579         skb1->len                 = skb1->data_len = skb->len - len;
2580         skb->len                  = len;
2581         skb->data_len             = len - pos;
2582 
2583         for (i = 0; i < nfrags; i++) {
2584                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2585 
2586                 if (pos + size > len) {
2587                         skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2588 
2589                         if (pos < len) {
2590                                 /* Split frag.
2591                                  * We have two variants in this case:
2592                                  * 1. Move all the frag to the second
2593                                  *    part, if it is possible. F.e.
2594                                  *    this approach is mandatory for TUX,
2595                                  *    where splitting is expensive.
2596                                  * 2. Split is accurately. We make this.
2597                                  */
2598                                 skb_frag_ref(skb, i);
2599                                 skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2600                                 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
2601                                 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
2602                                 skb_shinfo(skb)->nr_frags++;
2603                         }
2604                         k++;
2605                 } else
2606                         skb_shinfo(skb)->nr_frags++;
2607                 pos += size;
2608         }
2609         skb_shinfo(skb1)->nr_frags = k;
2610 }
2611 
2612 /**
2613  * skb_split - Split fragmented skb to two parts at length len.
2614  * @skb: the buffer to split
2615  * @skb1: the buffer to receive the second part
2616  * @len: new length for skb
2617  */
2618 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2619 {
2620         int pos = skb_headlen(skb);
2621 
2622         skb_shinfo(skb1)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2623         if (len < pos)  /* Split line is inside header. */
2624                 skb_split_inside_header(skb, skb1, len, pos);
2625         else            /* Second chunk has no header, nothing to copy. */
2626                 skb_split_no_header(skb, skb1, len, pos);
2627 }
2628 EXPORT_SYMBOL(skb_split);
2629 
2630 /* Shifting from/to a cloned skb is a no-go.
2631  *
2632  * Caller cannot keep skb_shinfo related pointers past calling here!
2633  */
2634 static int skb_prepare_for_shift(struct sk_buff *skb)
2635 {
2636         return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2637 }
2638 
2639 /**
2640  * skb_shift - Shifts paged data partially from skb to another
2641  * @tgt: buffer into which tail data gets added
2642  * @skb: buffer from which the paged data comes from
2643  * @shiftlen: shift up to this many bytes
2644  *
2645  * Attempts to shift up to shiftlen worth of bytes, which may be less than
2646  * the length of the skb, from skb to tgt. Returns number bytes shifted.
2647  * It's up to caller to free skb if everything was shifted.
2648  *
2649  * If @tgt runs out of frags, the whole operation is aborted.
2650  *
2651  * Skb cannot include anything else but paged data while tgt is allowed
2652  * to have non-paged data as well.
2653  *
2654  * TODO: full sized shift could be optimized but that would need
2655  * specialized skb free'er to handle frags without up-to-date nr_frags.
2656  */
2657 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2658 {
2659         int from, to, merge, todo;
2660         struct skb_frag_struct *fragfrom, *fragto;
2661 
2662         BUG_ON(shiftlen > skb->len);
2663         BUG_ON(skb_headlen(skb));       /* Would corrupt stream */
2664 
2665         todo = shiftlen;
2666         from = 0;
2667         to = skb_shinfo(tgt)->nr_frags;
2668         fragfrom = &skb_shinfo(skb)->frags[from];
2669 
2670         /* Actual merge is delayed until the point when we know we can
2671          * commit all, so that we don't have to undo partial changes
2672          */
2673         if (!to ||
2674             !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
2675                               fragfrom->page_offset)) {
2676                 merge = -1;
2677         } else {
2678                 merge = to - 1;
2679 
2680                 todo -= skb_frag_size(fragfrom);
2681                 if (todo < 0) {
2682                         if (skb_prepare_for_shift(skb) ||
2683                             skb_prepare_for_shift(tgt))
2684                                 return 0;
2685 
2686                         /* All previous frag pointers might be stale! */
2687                         fragfrom = &skb_shinfo(skb)->frags[from];
2688                         fragto = &skb_shinfo(tgt)->frags[merge];
2689 
2690                         skb_frag_size_add(fragto, shiftlen);
2691                         skb_frag_size_sub(fragfrom, shiftlen);
2692                         fragfrom->page_offset += shiftlen;
2693 
2694                         goto onlymerged;
2695                 }
2696 
2697                 from++;
2698         }
2699 
2700         /* Skip full, not-fitting skb to avoid expensive operations */
2701         if ((shiftlen == skb->len) &&
2702             (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2703                 return 0;
2704 
2705         if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2706                 return 0;
2707 
2708         while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2709                 if (to == MAX_SKB_FRAGS)
2710                         return 0;
2711 
2712                 fragfrom = &skb_shinfo(skb)->frags[from];
2713                 fragto = &skb_shinfo(tgt)->frags[to];
2714 
2715                 if (todo >= skb_frag_size(fragfrom)) {
2716                         *fragto = *fragfrom;
2717                         todo -= skb_frag_size(fragfrom);
2718                         from++;
2719                         to++;
2720 
2721                 } else {
2722                         __skb_frag_ref(fragfrom);
2723                         fragto->page = fragfrom->page;
2724                         fragto->page_offset = fragfrom->page_offset;
2725                         skb_frag_size_set(fragto, todo);
2726 
2727                         fragfrom->page_offset += todo;
2728                         skb_frag_size_sub(fragfrom, todo);
2729                         todo = 0;
2730 
2731                         to++;
2732                         break;
2733                 }
2734         }
2735 
2736         /* Ready to "commit" this state change to tgt */
2737         skb_shinfo(tgt)->nr_frags = to;
2738 
2739         if (merge >= 0) {
2740                 fragfrom = &skb_shinfo(skb)->frags[0];
2741                 fragto = &skb_shinfo(tgt)->frags[merge];
2742 
2743                 skb_frag_size_add(fragto, skb_frag_size(fragfrom));
2744                 __skb_frag_unref(fragfrom);
2745         }
2746 
2747         /* Reposition in the original skb */
2748         to = 0;
2749         while (from < skb_shinfo(skb)->nr_frags)
2750                 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2751         skb_shinfo(skb)->nr_frags = to;
2752 
2753         BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2754 
2755 onlymerged:
2756         /* Most likely the tgt won't ever need its checksum anymore, skb on
2757          * the other hand might need it if it needs to be resent
2758          */
2759         tgt->ip_summed = CHECKSUM_PARTIAL;
2760         skb->ip_summed = CHECKSUM_PARTIAL;
2761 
2762         /* Yak, is it really working this way? Some helper please? */
2763         skb->len -= shiftlen;
2764         skb->data_len -= shiftlen;
2765         skb->truesize -= shiftlen;
2766         tgt->len += shiftlen;
2767         tgt->data_len += shiftlen;
2768         tgt->truesize += shiftlen;
2769 
2770         return shiftlen;
2771 }
2772 
2773 /**
2774  * skb_prepare_seq_read - Prepare a sequential read of skb data
2775  * @skb: the buffer to read
2776  * @from: lower offset of data to be read
2777  * @to: upper offset of data to be read
2778  * @st: state variable
2779  *
2780  * Initializes the specified state variable. Must be called before
2781  * invoking skb_seq_read() for the first time.
2782  */
2783 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2784                           unsigned int to, struct skb_seq_state *st)
2785 {
2786         st->lower_offset = from;
2787         st->upper_offset = to;
2788         st->root_skb = st->cur_skb = skb;
2789         st->frag_idx = st->stepped_offset = 0;
2790         st->frag_data = NULL;
2791 }
2792 EXPORT_SYMBOL(skb_prepare_seq_read);
2793 
2794 /**
2795  * skb_seq_read - Sequentially read skb data
2796  * @consumed: number of bytes consumed by the caller so far
2797  * @data: destination pointer for data to be returned
2798  * @st: state variable
2799  *
2800  * Reads a block of skb data at @consumed relative to the
2801  * lower offset specified to skb_prepare_seq_read(). Assigns
2802  * the head of the data block to @data and returns the length
2803  * of the block or 0 if the end of the skb data or the upper
2804  * offset has been reached.
2805  *
2806  * The caller is not required to consume all of the data
2807  * returned, i.e. @consumed is typically set to the number
2808  * of bytes already consumed and the next call to
2809  * skb_seq_read() will return the remaining part of the block.
2810  *
2811  * Note 1: The size of each block of data returned can be arbitrary,
2812  *       this limitation is the cost for zerocopy sequential
2813  *       reads of potentially non linear data.
2814  *
2815  * Note 2: Fragment lists within fragments are not implemented
2816  *       at the moment, state->root_skb could be replaced with
2817  *       a stack for this purpose.
2818  */
2819 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2820                           struct skb_seq_state *st)
2821 {
2822         unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2823         skb_frag_t *frag;
2824 
2825         if (unlikely(abs_offset >= st->upper_offset)) {
2826                 if (st->frag_data) {
2827                         kunmap_atomic(st->frag_data);
2828                         st->frag_data = NULL;
2829                 }
2830                 return 0;
2831         }
2832 
2833 next_skb:
2834         block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2835 
2836         if (abs_offset < block_limit && !st->frag_data) {
2837                 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2838                 return block_limit - abs_offset;
2839         }
2840 
2841         if (st->frag_idx == 0 && !st->frag_data)
2842                 st->stepped_offset += skb_headlen(st->cur_skb);
2843 
2844         while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2845                 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2846                 block_limit = skb_frag_size(frag) + st->stepped_offset;
2847 
2848                 if (abs_offset < block_limit) {
2849                         if (!st->frag_data)
2850                                 st->frag_data = kmap_atomic(skb_frag_page(frag));
2851 
2852                         *data = (u8 *) st->frag_data + frag->page_offset +
2853                                 (abs_offset - st->stepped_offset);
2854 
2855                         return block_limit - abs_offset;
2856                 }
2857 
2858                 if (st->frag_data) {
2859                         kunmap_atomic(st->frag_data);
2860                         st->frag_data = NULL;
2861                 }
2862 
2863                 st->frag_idx++;
2864                 st->stepped_offset += skb_frag_size(frag);
2865         }
2866 
2867         if (st->frag_data) {
2868                 kunmap_atomic(st->frag_data);
2869                 st->frag_data = NULL;
2870         }
2871 
2872         if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
2873                 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2874                 st->frag_idx = 0;
2875                 goto next_skb;
2876         } else if (st->cur_skb->next) {
2877                 st->cur_skb = st->cur_skb->next;
2878                 st->frag_idx = 0;
2879                 goto next_skb;
2880         }
2881 
2882         return 0;
2883 }
2884 EXPORT_SYMBOL(skb_seq_read);
2885 
2886 /**
2887  * skb_abort_seq_read - Abort a sequential read of skb data
2888  * @st: state variable
2889  *
2890  * Must be called if skb_seq_read() was not called until it
2891  * returned 0.
2892  */
2893 void skb_abort_seq_read(struct skb_seq_state *st)
2894 {
2895         if (st->frag_data)
2896                 kunmap_atomic(st->frag_data);
2897 }
2898 EXPORT_SYMBOL(skb_abort_seq_read);
2899 
2900 #define TS_SKB_CB(state)        ((struct skb_seq_state *) &((state)->cb))
2901 
2902 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2903                                           struct ts_config *conf,
2904                                           struct ts_state *state)
2905 {
2906         return skb_seq_read(offset, text, TS_SKB_CB(state));
2907 }
2908 
2909 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2910 {
2911         skb_abort_seq_read(TS_SKB_CB(state));
2912 }
2913 
2914 /**
2915  * skb_find_text - Find a text pattern in skb data
2916  * @skb: the buffer to look in
2917  * @from: search offset
2918  * @to: search limit
2919  * @config: textsearch configuration
2920  *
2921  * Finds a pattern in the skb data according to the specified
2922  * textsearch configuration. Use textsearch_next() to retrieve
2923  * subsequent occurrences of the pattern. Returns the offset
2924  * to the first occurrence or UINT_MAX if no match was found.
2925  */
2926 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2927                            unsigned int to, struct ts_config *config)
2928 {
2929         struct ts_state state;
2930         unsigned int ret;
2931 
2932         config->get_next_block = skb_ts_get_next_block;
2933         config->finish = skb_ts_finish;
2934 
2935         skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
2936 
2937         ret = textsearch_find(config, &state);
2938         return (ret <= to - from ? ret : UINT_MAX);
2939 }
2940 EXPORT_SYMBOL(skb_find_text);
2941 
2942 /**
2943  * skb_append_datato_frags - append the user data to a skb
2944  * @sk: sock  structure
2945  * @skb: skb structure to be appended with user data.
2946  * @getfrag: call back function to be used for getting the user data
2947  * @from: pointer to user message iov
2948  * @length: length of the iov message
2949  *
2950  * Description: This procedure append the user data in the fragment part
2951  * of the skb if any page alloc fails user this procedure returns  -ENOMEM
2952  */
2953 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2954                         int (*getfrag)(void *from, char *to, int offset,
2955                                         int len, int odd, struct sk_buff *skb),
2956                         void *from, int length)
2957 {
2958         int frg_cnt = skb_shinfo(skb)->nr_frags;
2959         int copy;
2960         int offset = 0;
2961         int ret;
2962         struct page_frag *pfrag = &current->task_frag;
2963 
2964         do {
2965                 /* Return error if we don't have space for new frag */
2966                 if (frg_cnt >= MAX_SKB_FRAGS)
2967                         return -EMSGSIZE;
2968 
2969                 if (!sk_page_frag_refill(sk, pfrag))
2970                         return -ENOMEM;
2971 
2972                 /* copy the user data to page */
2973                 copy = min_t(int, length, pfrag->size - pfrag->offset);
2974 
2975                 ret = getfrag(from, page_address(pfrag->page) + pfrag->offset,
2976                               offset, copy, 0, skb);
2977                 if (ret < 0)
2978                         return -EFAULT;
2979 
2980                 /* copy was successful so update the size parameters */
2981                 skb_fill_page_desc(skb, frg_cnt, pfrag->page, pfrag->offset,
2982                                    copy);
2983                 frg_cnt++;
2984                 pfrag->offset += copy;
2985                 get_page(pfrag->page);
2986 
2987                 skb->truesize += copy;
2988                 atomic_add(copy, &sk->sk_wmem_alloc);
2989                 skb->len += copy;
2990                 skb->data_len += copy;
2991                 offset += copy;
2992                 length -= copy;
2993 
2994         } while (length > 0);
2995 
2996         return 0;
2997 }
2998 EXPORT_SYMBOL(skb_append_datato_frags);
2999 
3000 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
3001                          int offset, size_t size)
3002 {
3003         int i = skb_shinfo(skb)->nr_frags;
3004 
3005         if (skb_can_coalesce(skb, i, page, offset)) {
3006                 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
3007         } else if (i < MAX_SKB_FRAGS) {
3008                 get_page(page);
3009                 skb_fill_page_desc(skb, i, page, offset, size);
3010         } else {
3011                 return -EMSGSIZE;
3012         }
3013 
3014         return 0;
3015 }
3016 EXPORT_SYMBOL_GPL(skb_append_pagefrags);
3017 
3018 /**
3019  *      skb_pull_rcsum - pull skb and update receive checksum
3020  *      @skb: buffer to update
3021  *      @len: length of data pulled
3022  *
3023  *      This function performs an skb_pull on the packet and updates
3024  *      the CHECKSUM_COMPLETE checksum.  It should be used on
3025  *      receive path processing instead of skb_pull unless you know
3026  *      that the checksum difference is zero (e.g., a valid IP header)
3027  *      or you are setting ip_summed to CHECKSUM_NONE.
3028  */
3029 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
3030 {
3031         unsigned char *data = skb->data;
3032 
3033         BUG_ON(len > skb->len);
3034         __skb_pull(skb, len);
3035         skb_postpull_rcsum(skb, data, len);
3036         return skb->data;
3037 }
3038 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
3039 
3040 /**
3041  *      skb_segment - Perform protocol segmentation on skb.
3042  *      @head_skb: buffer to segment
3043  *      @features: features for the output path (see dev->features)
3044  *
3045  *      This function performs segmentation on the given skb.  It returns
3046  *      a pointer to the first in a list of new skbs for the segments.
3047  *      In case of error it returns ERR_PTR(err).
3048  */
3049 struct sk_buff *skb_segment(struct sk_buff *head_skb,
3050                             netdev_features_t features)
3051 {
3052         struct sk_buff *segs = NULL;
3053         struct sk_buff *tail = NULL;
3054         struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
3055         skb_frag_t *frag = skb_shinfo(head_skb)->frags;
3056         unsigned int mss = skb_shinfo(head_skb)->gso_size;
3057         unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
3058         struct sk_buff *frag_skb = head_skb;
3059         unsigned int offset = doffset;
3060         unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
3061         unsigned int partial_segs = 0;
3062         unsigned int headroom;
3063         unsigned int len = head_skb->len;
3064         __be16 proto;
3065         bool csum, sg;
3066         int nfrags = skb_shinfo(head_skb)->nr_frags;
3067         int err = -ENOMEM;
3068         int i = 0;
3069         int pos;
3070         int dummy;
3071 
3072         __skb_push(head_skb, doffset);
3073         proto = skb_network_protocol(head_skb, &dummy);
3074         if (unlikely(!proto))
3075                 return ERR_PTR(-EINVAL);
3076 
3077         sg = !!(features & NETIF_F_SG);
3078         csum = !!can_checksum_protocol(features, proto);
3079 
3080         /* GSO partial only requires that we trim off any excess that
3081          * doesn't fit into an MSS sized block, so take care of that
3082          * now.
3083          */
3084         if (sg && csum && (features & NETIF_F_GSO_PARTIAL)) {
3085                 partial_segs = len / mss;
3086                 if (partial_segs > 1)
3087                         mss *= partial_segs;
3088                 else
3089                         partial_segs = 0;
3090         }
3091 
3092         headroom = skb_headroom(head_skb);
3093         pos = skb_headlen(head_skb);
3094 
3095         do {
3096                 struct sk_buff *nskb;
3097                 skb_frag_t *nskb_frag;
3098                 int hsize;
3099                 int size;
3100 
3101                 len = head_skb->len - offset;
3102                 if (len > mss)
3103                         len = mss;
3104 
3105                 hsize = skb_headlen(head_skb) - offset;
3106                 if (hsize < 0)
3107                         hsize = 0;
3108                 if (hsize > len || !sg)
3109                         hsize = len;
3110 
3111                 if (!hsize && i >= nfrags && skb_headlen(list_skb) &&
3112                     (skb_headlen(list_skb) == len || sg)) {
3113                         BUG_ON(skb_headlen(list_skb) > len);
3114 
3115                         i = 0;
3116                         nfrags = skb_shinfo(list_skb)->nr_frags;
3117                         frag = skb_shinfo(list_skb)->frags;
3118                         frag_skb = list_skb;
3119                         pos += skb_headlen(list_skb);
3120 
3121                         while (pos < offset + len) {
3122                                 BUG_ON(i >= nfrags);
3123 
3124                                 size = skb_frag_size(frag);
3125                                 if (pos + size > offset + len)
3126                                         break;
3127 
3128                                 i++;
3129                                 pos += size;
3130                                 frag++;
3131                         }
3132 
3133                         nskb = skb_clone(list_skb, GFP_ATOMIC);
3134                         list_skb = list_skb->next;
3135 
3136                         if (unlikely(!nskb))
3137                                 goto err;
3138 
3139                         if (unlikely(pskb_trim(nskb, len))) {
3140                                 kfree_skb(nskb);
3141                                 goto err;
3142                         }
3143 
3144                         hsize = skb_end_offset(nskb);
3145                         if (skb_cow_head(nskb, doffset + headroom)) {
3146                                 kfree_skb(nskb);
3147                                 goto err;
3148                         }
3149 
3150                         nskb->truesize += skb_end_offset(nskb) - hsize;
3151                         skb_release_head_state(nskb);
3152                         __skb_push(nskb, doffset);
3153                 } else {
3154                         nskb = __alloc_skb(hsize + doffset + headroom,
3155                                            GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
3156                                            NUMA_NO_NODE);
3157 
3158                         if (unlikely(!nskb))
3159                                 goto err;
3160 
3161                         skb_reserve(nskb, headroom);
3162                         __skb_put(nskb, doffset);
3163                 }
3164 
3165                 if (segs)
3166                         tail->next = nskb;
3167                 else
3168                         segs = nskb;
3169                 tail = nskb;
3170 
3171                 __copy_skb_header(nskb, head_skb);
3172 
3173                 skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
3174                 skb_reset_mac_len(nskb);
3175 
3176                 skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
3177                                                  nskb->data - tnl_hlen,
3178                                                  doffset + tnl_hlen);
3179 
3180                 if (nskb->len == len + doffset)
3181                         goto perform_csum_check;
3182 
3183                 if (!sg) {
3184                         if (!nskb->remcsum_offload)
3185                                 nskb->ip_summed = CHECKSUM_NONE;
3186                         SKB_GSO_CB(nskb)->csum =
3187                                 skb_copy_and_csum_bits(head_skb, offset,
3188                                                        skb_put(nskb, len),
3189                                                        len, 0);
3190                         SKB_GSO_CB(nskb)->csum_start =
3191                                 skb_headroom(nskb) + doffset;
3192                         continue;
3193                 }
3194 
3195                 nskb_frag = skb_shinfo(nskb)->frags;
3196 
3197                 skb_copy_from_linear_data_offset(head_skb, offset,
3198                                                  skb_put(nskb, hsize), hsize);
3199 
3200                 skb_shinfo(nskb)->tx_flags = skb_shinfo(head_skb)->tx_flags &
3201                         SKBTX_SHARED_FRAG;
3202 
3203                 while (pos < offset + len) {
3204                         if (i >= nfrags) {
3205                                 BUG_ON(skb_headlen(list_skb));
3206 
3207                                 i = 0;
3208                                 nfrags = skb_shinfo(list_skb)->nr_frags;
3209                                 frag = skb_shinfo(list_skb)->frags;
3210                                 frag_skb = list_skb;
3211 
3212                                 BUG_ON(!nfrags);
3213 
3214                                 list_skb = list_skb->next;
3215                         }
3216 
3217                         if (unlikely(skb_shinfo(nskb)->nr_frags >=
3218                                      MAX_SKB_FRAGS)) {
3219                                 net_warn_ratelimited(
3220                                         "skb_segment: too many frags: %u %u\n",
3221                                         pos, mss);
3222                                 goto err;
3223                         }
3224 
3225                         if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC)))
3226                                 goto err;
3227 
3228                         *nskb_frag = *frag;
3229                         __skb_frag_ref(nskb_frag);
3230                         size = skb_frag_size(nskb_frag);
3231 
3232                         if (pos < offset) {
3233                                 nskb_frag->page_offset += offset - pos;
3234                                 skb_frag_size_sub(nskb_frag, offset - pos);
3235                         }
3236 
3237                         skb_shinfo(nskb)->nr_frags++;
3238 
3239                         if (pos + size <= offset + len) {
3240                                 i++;
3241                                 frag++;
3242                                 pos += size;
3243                         } else {
3244                                 skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
3245                                 goto skip_fraglist;
3246                         }
3247 
3248                         nskb_frag++;
3249                 }
3250 
3251 skip_fraglist:
3252                 nskb->data_len = len - hsize;
3253                 nskb->len += nskb->data_len;
3254                 nskb->truesize += nskb->data_len;
3255 
3256 perform_csum_check:
3257                 if (!csum) {
3258                         if (skb_has_shared_frag(nskb)) {
3259                                 err = __skb_linearize(nskb);
3260                                 if (err)
3261                                         goto err;
3262                         }
3263                         if (!nskb->remcsum_offload)
3264                                 nskb->ip_summed = CHECKSUM_NONE;
3265                         SKB_GSO_CB(nskb)->csum =
3266                                 skb_checksum(nskb, doffset,
3267                                              nskb->len - doffset, 0);
3268                         SKB_GSO_CB(nskb)->csum_start =
3269                                 skb_headroom(nskb) + doffset;
3270                 }
3271         } while ((offset += len) < head_skb->len);
3272 
3273         /* Some callers want to get the end of the list.
3274          * Put it in segs->prev to avoid walking the list.
3275          * (see validate_xmit_skb_list() for example)
3276          */
3277         segs->prev = tail;
3278 
3279         /* Update GSO info on first skb in partial sequence. */
3280         if (partial_segs) {
3281                 int type = skb_shinfo(head_skb)->gso_type;
3282 
3283                 /* Update type to add partial and then remove dodgy if set */
3284                 type |= SKB_GSO_PARTIAL;
3285                 type &= ~SKB_GSO_DODGY;
3286 
3287                 /* Update GSO info and prepare to start updating headers on
3288                  * our way back down the stack of protocols.
3289                  */
3290                 skb_shinfo(segs)->gso_size = skb_shinfo(head_skb)->gso_size;
3291                 skb_shinfo(segs)->gso_segs = partial_segs;
3292                 skb_shinfo(segs)->gso_type = type;
3293                 SKB_GSO_CB(segs)->data_offset = skb_headroom(segs) + doffset;
3294         }
3295 
3296         /* Following permits correct backpressure, for protocols
3297          * using skb_set_owner_w().
3298          * Idea is to tranfert ownership from head_skb to last segment.
3299          */
3300         if (head_skb->destructor == sock_wfree) {
3301                 swap(tail->truesize, head_skb->truesize);
3302                 swap(tail->destructor, head_skb->destructor);
3303                 swap(tail->sk, head_skb->sk);
3304         }
3305         return segs;
3306 
3307 err:
3308         kfree_skb_list(segs);
3309         return ERR_PTR(err);
3310 }
3311 EXPORT_SYMBOL_GPL(skb_segment);
3312 
3313 int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
3314 {
3315         struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
3316         unsigned int offset = skb_gro_offset(skb);
3317         unsigned int headlen = skb_headlen(skb);
3318         unsigned int len = skb_gro_len(skb);
3319         struct sk_buff *lp, *p = *head;
3320         unsigned int delta_truesize;
3321 
3322         if (unlikely(p->len + len >= 65536))
3323                 return -E2BIG;
3324 
3325         lp = NAPI_GRO_CB(p)->last;
3326         pinfo = skb_shinfo(lp);
3327 
3328         if (headlen <= offset) {
3329                 skb_frag_t *frag;
3330                 skb_frag_t *frag2;
3331                 int i = skbinfo->nr_frags;
3332                 int nr_frags = pinfo->nr_frags + i;
3333 
3334                 if (nr_frags > MAX_SKB_FRAGS)
3335                         goto merge;
3336 
3337                 offset -= headlen;
3338                 pinfo->nr_frags = nr_frags;
3339                 skbinfo->nr_frags = 0;
3340 
3341                 frag = pinfo->frags + nr_frags;
3342                 frag2 = skbinfo->frags + i;
3343                 do {
3344                         *--frag = *--frag2;
3345                 } while (--i);
3346 
3347                 frag->page_offset += offset;
3348                 skb_frag_size_sub(frag, offset);
3349 
3350                 /* all fragments truesize : remove (head size + sk_buff) */
3351                 delta_truesize = skb->truesize -
3352                                  SKB_TRUESIZE(skb_end_offset(skb));
3353 
3354                 skb->truesize -= skb->data_len;
3355                 skb->len -= skb->data_len;
3356                 skb->data_len = 0;
3357 
3358                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
3359                 goto done;
3360         } else if (skb->head_frag) {
3361                 int nr_frags = pinfo->nr_frags;
3362                 skb_frag_t *frag = pinfo->frags + nr_frags;
3363                 struct page *page = virt_to_head_page(skb->head);
3364                 unsigned int first_size = headlen - offset;
3365                 unsigned int first_offset;
3366 
3367                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
3368                         goto merge;
3369 
3370                 first_offset = skb->data -
3371                                (unsigned char *)page_address(page) +
3372                                offset;
3373 
3374                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
3375 
3376                 frag->page.p      = page;
3377                 frag->page_offset = first_offset;
3378                 skb_frag_size_set(frag, first_size);
3379 
3380                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
3381                 /* We dont need to clear skbinfo->nr_frags here */
3382 
3383                 delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
3384                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
3385                 goto done;
3386         }
3387 
3388 merge:
3389         delta_truesize = skb->truesize;
3390         if (offset > headlen) {
3391                 unsigned int eat = offset - headlen;
3392 
3393                 skbinfo->frags[0].page_offset += eat;
3394                 skb_frag_size_sub(&skbinfo->frags[0], eat);
3395                 skb->data_len -= eat;
3396                 skb->len -= eat;
3397                 offset = headlen;
3398         }
3399 
3400         __skb_pull(skb, offset);
3401 
3402         if (NAPI_GRO_CB(p)->last == p)
3403                 skb_shinfo(p)->frag_list = skb;
3404         else
3405                 NAPI_GRO_CB(p)->last->next = skb;
3406         NAPI_GRO_CB(p)->last = skb;
3407         __skb_header_release(skb);
3408         lp = p;
3409 
3410 done:
3411         NAPI_GRO_CB(p)->count++;
3412         p->data_len += len;
3413         p->truesize += delta_truesize;
3414         p->len += len;
3415         if (lp != p) {
3416                 lp->data_len += len;
3417                 lp->truesize += delta_truesize;
3418                 lp->len += len;
3419         }
3420         NAPI_GRO_CB(skb)->same_flow = 1;
3421         return 0;
3422 }
3423 
3424 void __init skb_init(void)
3425 {
3426         skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
3427                                               sizeof(struct sk_buff),
3428                                               0,
3429                                               SLAB_HWCACHE_ALIGN|SLAB_PANIC,
3430                                               NULL);
3431         skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
3432                                                 sizeof(struct sk_buff_fclones),
3433                                                 0,
3434                                                 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
3435                                                 NULL);
3436 }
3437 
3438 /**
3439  *      skb_to_sgvec - Fill a scatter-gather list from a socket buffer
3440  *      @skb: Socket buffer containing the buffers to be mapped
3441  *      @sg: The scatter-gather list to map into
3442  *      @offset: The offset into the buffer's contents to start mapping
3443  *      @len: Length of buffer space to be mapped
3444  *
3445  *      Fill the specified scatter-gather list with mappings/pointers into a
3446  *      region of the buffer space attached to a socket buffer.
3447  */
3448 static int
3449 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3450 {
3451         int start = skb_headlen(skb);
3452         int i, copy = start - offset;
3453         struct sk_buff *frag_iter;
3454         int elt = 0;
3455 
3456         if (copy > 0) {
3457                 if (copy > len)
3458                         copy = len;
3459                 sg_set_buf(sg, skb->data + offset, copy);
3460                 elt++;
3461                 if ((len -= copy) == 0)
3462                         return elt;
3463                 offset += copy;
3464         }
3465 
3466         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3467                 int end;
3468 
3469                 WARN_ON(start > offset + len);
3470 
3471                 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3472                 if ((copy = end - offset) > 0) {
3473                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3474 
3475                         if (copy > len)
3476                                 copy = len;
3477                         sg_set_page(&sg[elt], skb_frag_page(frag), copy,
3478                                         frag->page_offset+offset-start);
3479                         elt++;
3480                         if (!(len -= copy))
3481                                 return elt;
3482                         offset += copy;
3483                 }
3484                 start = end;
3485         }
3486 
3487         skb_walk_frags(skb, frag_iter) {
3488                 int end;
3489 
3490                 WARN_ON(start > offset + len);
3491 
3492                 end = start + frag_iter->len;
3493                 if ((copy = end - offset) > 0) {
3494                         if (copy > len)
3495                                 copy = len;
3496                         elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
3497                                               copy);
3498                         if ((len -= copy) == 0)
3499                                 return elt;
3500                         offset += copy;
3501                 }
3502                 start = end;
3503         }
3504         BUG_ON(len);
3505         return elt;
3506 }
3507 
3508 /* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
3509  * sglist without mark the sg which contain last skb data as the end.
3510  * So the caller can mannipulate sg list as will when padding new data after
3511  * the first call without calling sg_unmark_end to expend sg list.
3512  *
3513  * Scenario to use skb_to_sgvec_nomark:
3514  * 1. sg_init_table
3515  * 2. skb_to_sgvec_nomark(payload1)
3516  * 3. skb_to_sgvec_nomark(payload2)
3517  *
3518  * This is equivalent to:
3519  * 1. sg_init_table
3520  * 2. skb_to_sgvec(payload1)
3521  * 3. sg_unmark_end
3522  * 4. skb_to_sgvec(payload2)
3523  *
3524  * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
3525  * is more preferable.
3526  */
3527 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
3528                         int offset, int len)
3529 {
3530         return __skb_to_sgvec(skb, sg, offset, len);
3531 }
3532 EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
3533 
3534 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3535 {
3536         int nsg = __skb_to_sgvec(skb, sg, offset, len);
3537 
3538         sg_mark_end(&sg[nsg - 1]);
3539 
3540         return nsg;
3541 }
3542 EXPORT_SYMBOL_GPL(skb_to_sgvec);
3543 
3544 /**
3545  *      skb_cow_data - Check that a socket buffer's data buffers are writable
3546  *      @skb: The socket buffer to check.
3547  *      @tailbits: Amount of trailing space to be added
3548  *      @trailer: Returned pointer to the skb where the @tailbits space begins
3549  *
3550  *      Make sure that the data buffers attached to a socket buffer are
3551  *      writable. If they are not, private copies are made of the data buffers
3552  *      and the socket buffer is set to use these instead.
3553  *
3554  *      If @tailbits is given, make sure that there is space to write @tailbits
3555  *      bytes of data beyond current end of socket buffer.  @trailer will be
3556  *      set to point to the skb in which this space begins.
3557  *
3558  *      The number of scatterlist elements required to completely map the
3559  *      COW'd and extended socket buffer will be returned.
3560  */
3561 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
3562 {
3563         int copyflag;
3564         int elt;
3565         struct sk_buff *skb1, **skb_p;
3566 
3567         /* If skb is cloned or its head is paged, reallocate
3568          * head pulling out all the pages (pages are considered not writable
3569          * at the moment even if they are anonymous).
3570          */
3571         if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
3572             __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
3573                 return -ENOMEM;
3574 
3575         /* Easy case. Most of packets will go this way. */
3576         if (!skb_has_frag_list(skb)) {
3577                 /* A little of trouble, not enough of space for trailer.
3578                  * This should not happen, when stack is tuned to generate
3579                  * good frames. OK, on miss we reallocate and reserve even more
3580                  * space, 128 bytes is fair. */
3581 
3582                 if (skb_tailroom(skb) < tailbits &&
3583                     pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
3584                         return -ENOMEM;
3585 
3586                 /* Voila! */
3587                 *trailer = skb;
3588                 return 1;
3589         }
3590 
3591         /* Misery. We are in troubles, going to mincer fragments... */
3592 
3593         elt = 1;
3594         skb_p = &skb_shinfo(skb)->frag_list;
3595         copyflag = 0;
3596 
3597         while ((skb1 = *skb_p) != NULL) {
3598                 int ntail = 0;
3599 
3600                 /* The fragment is partially pulled by someone,
3601                  * this can happen on input. Copy it and everything
3602                  * after it. */
3603 
3604                 if (skb_shared(skb1))
3605                         copyflag = 1;
3606 
3607                 /* If the skb is the last, worry about trailer. */
3608 
3609                 if (skb1->next == NULL && tailbits) {
3610                         if (skb_shinfo(skb1)->nr_frags ||
3611                             skb_has_frag_list(skb1) ||
3612                             skb_tailroom(skb1) < tailbits)
3613                                 ntail = tailbits + 128;
3614                 }
3615 
3616                 if (copyflag ||
3617                     skb_cloned(skb1) ||
3618                     ntail ||
3619                     skb_shinfo(skb1)->nr_frags ||
3620                     skb_has_frag_list(skb1)) {
3621                         struct sk_buff *skb2;
3622 
3623                         /* Fuck, we are miserable poor guys... */
3624                         if (ntail == 0)
3625                                 skb2 = skb_copy(skb1, GFP_ATOMIC);
3626                         else
3627                                 skb2 = skb_copy_expand(skb1,
3628                                                        skb_headroom(skb1),
3629                                                        ntail,
3630                                                        GFP_ATOMIC);
3631                         if (unlikely(skb2 == NULL))
3632                                 return -ENOMEM;
3633 
3634                         if (skb1->sk)
3635                                 skb_set_owner_w(skb2, skb1->sk);
3636 
3637                         /* Looking around. Are we still alive?
3638                          * OK, link new skb, drop old one */
3639 
3640                         skb2->next = skb1->next;
3641                         *skb_p = skb2;
3642                         kfree_skb(skb1);
3643                         skb1 = skb2;
3644                 }
3645                 elt++;
3646                 *trailer = skb1;
3647                 skb_p = &skb1->next;
3648         }
3649 
3650         return elt;
3651 }
3652 EXPORT_SYMBOL_GPL(skb_cow_data);
3653 
3654 static void sock_rmem_free(struct sk_buff *skb)
3655 {
3656         struct sock *sk = skb->sk;
3657 
3658         atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
3659 }
3660 
3661 /*
3662  * Note: We dont mem charge error packets (no sk_forward_alloc changes)
3663  */
3664 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
3665 {
3666         if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
3667             (unsigned int)sk->sk_rcvbuf)
3668                 return -ENOMEM;
3669 
3670         skb_orphan(skb);
3671         skb->sk = sk;
3672         skb->destructor = sock_rmem_free;
3673         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
3674 
3675         /* before exiting rcu section, make sure dst is refcounted */
3676         skb_dst_force(skb);
3677 
3678         skb_queue_tail(&sk->sk_error_queue, skb);
3679         if (!sock_flag(sk, SOCK_DEAD))
3680                 sk->sk_data_ready(sk);
3681         return 0;
3682 }
3683 EXPORT_SYMBOL(sock_queue_err_skb);
3684 
3685 struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
3686 {
3687         struct sk_buff_head *q = &sk->sk_error_queue;
3688         struct sk_buff *skb, *skb_next;
3689         unsigned long flags;
3690         int err = 0;
3691 
3692         spin_lock_irqsave(&q->lock, flags);
3693         skb = __skb_dequeue(q);
3694         if (skb && (skb_next = skb_peek(q)))
3695                 err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
3696         spin_unlock_irqrestore(&q->lock, flags);
3697 
3698         sk->sk_err = err;
3699         if (err)
3700                 sk->sk_error_report(sk);
3701 
3702         return skb;
3703 }
3704 EXPORT_SYMBOL(sock_dequeue_err_skb);
3705 
3706 /**
3707  * skb_clone_sk - create clone of skb, and take reference to socket
3708  * @skb: the skb to clone
3709  *
3710  * This function creates a clone of a buffer that holds a reference on
3711  * sk_refcnt.  Buffers created via this function are meant to be
3712  * returned using sock_queue_err_skb, or free via kfree_skb.
3713  *
3714  * When passing buffers allocated with this function to sock_queue_err_skb
3715  * it is necessary to wrap the call with sock_hold/sock_put in order to
3716  * prevent the socket from being released prior to being enqueued on
3717  * the sk_error_queue.
3718  */
3719 struct sk_buff *skb_clone_sk(struct sk_buff *skb)
3720 {
3721         struct sock *sk = skb->sk;
3722         struct sk_buff *clone;
3723 
3724         if (!sk || !atomic_inc_not_zero(&sk->sk_refcnt))
3725                 return NULL;
3726 
3727         clone = skb_clone(skb, GFP_ATOMIC);
3728         if (!clone) {
3729                 sock_put(sk);
3730                 return NULL;
3731         }
3732 
3733         clone->sk = sk;
3734         clone->destructor = sock_efree;
3735 
3736         return clone;
3737 }
3738 EXPORT_SYMBOL(skb_clone_sk);
3739 
3740 static void __skb_complete_tx_timestamp(struct sk_buff *skb,
3741                                         struct sock *sk,
3742                                         int tstype)
3743 {
3744         struct sock_exterr_skb *serr;
3745         int err;
3746 
3747         serr = SKB_EXT_ERR(skb);
3748         memset(serr, 0, sizeof(*serr));
3749         serr->ee.ee_errno = ENOMSG;
3750         serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3751         serr->ee.ee_info = tstype;
3752         if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) {
3753                 serr->ee.ee_data = skb_shinfo(skb)->tskey;
3754                 if (sk->sk_protocol == IPPROTO_TCP &&
3755                     sk->sk_type == SOCK_STREAM)
3756                         serr->ee.ee_data -= sk->sk_tskey;
3757         }
3758 
3759         err = sock_queue_err_skb(sk, skb);
3760 
3761         if (err)
3762                 kfree_skb(skb);
3763 }
3764 
3765 static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
3766 {
3767         bool ret;
3768 
3769         if (likely(sysctl_tstamp_allow_data || tsonly))
3770                 return true;
3771 
3772         read_lock_bh(&sk->sk_callback_lock);
3773         ret = sk->sk_socket && sk->sk_socket->file &&
3774               file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
3775         read_unlock_bh(&sk->sk_callback_lock);
3776         return ret;
3777 }
3778 
3779 void skb_complete_tx_timestamp(struct sk_buff *skb,
3780                                struct skb_shared_hwtstamps *hwtstamps)
3781 {
3782         struct sock *sk = skb->sk;
3783 
3784         if (!skb_may_tx_timestamp(sk, false))
3785                 return;
3786 
3787         /* take a reference to prevent skb_orphan() from freeing the socket */
3788         sock_hold(sk);
3789 
3790         *skb_hwtstamps(skb) = *hwtstamps;
3791         __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
3792 
3793         sock_put(sk);
3794 }
3795 EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
3796 
3797 void __skb_tstamp_tx(struct sk_buff *orig_skb,
3798                      struct skb_shared_hwtstamps *hwtstamps,
3799                      struct sock *sk, int tstype)
3800 {
3801         struct sk_buff *skb;
3802         bool tsonly;
3803 
3804         if (!sk)
3805                 return;
3806 
3807         tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
3808         if (!skb_may_tx_timestamp(sk, tsonly))
3809                 return;
3810 
3811         if (tsonly)
3812                 skb = alloc_skb(0, GFP_ATOMIC);
3813         else
3814                 skb = skb_clone(orig_skb, GFP_ATOMIC);
3815         if (!skb)
3816                 return;
3817 
3818         if (tsonly) {
3819                 skb_shinfo(skb)->tx_flags = skb_shinfo(orig_skb)->tx_flags;
3820                 skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
3821         }
3822 
3823         if (hwtstamps)
3824                 *skb_hwtstamps(skb) = *hwtstamps;
3825         else
3826                 skb->tstamp = ktime_get_real();
3827 
3828         __skb_complete_tx_timestamp(skb, sk, tstype);
3829 }
3830 EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
3831 
3832 void skb_tstamp_tx(struct sk_buff *orig_skb,
3833                    struct skb_shared_hwtstamps *hwtstamps)
3834 {
3835         return __skb_tstamp_tx(orig_skb, hwtstamps, orig_skb->sk,
3836                                SCM_TSTAMP_SND);
3837 }
3838 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3839 
3840 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
3841 {
3842         struct sock *sk = skb->sk;
3843         struct sock_exterr_skb *serr;
3844         int err;
3845 
3846         skb->wifi_acked_valid = 1;
3847         skb->wifi_acked = acked;
3848 
3849         serr = SKB_EXT_ERR(skb);
3850         memset(serr, 0, sizeof(*serr));
3851         serr->ee.ee_errno = ENOMSG;
3852         serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
3853 
3854         /* take a reference to prevent skb_orphan() from freeing the socket */
3855         sock_hold(sk);
3856 
3857         err = sock_queue_err_skb(sk, skb);
3858         if (err)
3859                 kfree_skb(skb);
3860 
3861         sock_put(sk);
3862 }
3863 EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
3864 
3865 /**
3866  * skb_partial_csum_set - set up and verify partial csum values for packet
3867  * @skb: the skb to set
3868  * @start: the number of bytes after skb->data to start checksumming.
3869  * @off: the offset from start to place the checksum.
3870  *
3871  * For untrusted partially-checksummed packets, we need to make sure the values
3872  * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3873  *
3874  * This function checks and sets those values and skb->ip_summed: if this
3875  * returns false you should drop the packet.
3876  */
3877 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3878 {
3879         if (unlikely(start > skb_headlen(skb)) ||
3880             unlikely((int)start + off > skb_headlen(skb) - 2)) {
3881                 net_warn_ratelimited("bad partial csum: csum=%u/%u len=%u\n",
3882                                      start, off, skb_headlen(skb));
3883                 return false;
3884         }
3885         skb->ip_summed = CHECKSUM_PARTIAL;
3886         skb->csum_start = skb_headroom(skb) + start;
3887         skb->csum_offset = off;
3888         skb_set_transport_header(skb, start);
3889         return true;
3890 }
3891 EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3892 
3893 static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
3894                                unsigned int max)
3895 {
3896         if (skb_headlen(skb) >= len)
3897                 return 0;
3898 
3899         /* If we need to pullup then pullup to the max, so we
3900          * won't need to do it again.
3901          */
3902         if (max > skb->len)
3903                 max = skb->len;
3904 
3905         if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
3906                 return -ENOMEM;
3907 
3908         if (skb_headlen(skb) < len)
3909                 return -EPROTO;
3910 
3911         return 0;
3912 }
3913 
3914 #define MAX_TCP_HDR_LEN (15 * 4)
3915 
3916 static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
3917                                       typeof(IPPROTO_IP) proto,
3918                                       unsigned int off)
3919 {
3920         switch (proto) {
3921                 int err;
3922 
3923         case IPPROTO_TCP:
3924                 err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
3925                                           off + MAX_TCP_HDR_LEN);
3926                 if (!err && !skb_partial_csum_set(skb, off,
3927                                                   offsetof(struct tcphdr,
3928                                                            check)))
3929                         err = -EPROTO;
3930                 return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
3931 
3932         case IPPROTO_UDP:
3933                 err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
3934                                           off + sizeof(struct udphdr));
3935                 if (!err && !skb_partial_csum_set(skb, off,
3936                                                   offsetof(struct udphdr,
3937                                                            check)))
3938                         err = -EPROTO;
3939                 return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
3940         }
3941 
3942         return ERR_PTR(-EPROTO);
3943 }
3944 
3945 /* This value should be large enough to cover a tagged ethernet header plus
3946  * maximally sized IP and TCP or UDP headers.
3947  */
3948 #define MAX_IP_HDR_LEN 128
3949 
3950 static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
3951 {
3952         unsigned int off;
3953         bool fragment;
3954         __sum16 *csum;
3955         int err;
3956 
3957         fragment = false;
3958 
3959         err = skb_maybe_pull_tail(skb,
3960                                   sizeof(struct iphdr),
3961                                   MAX_IP_HDR_LEN);
3962         if (err < 0)
3963                 goto out;
3964 
3965         if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
3966                 fragment = true;
3967 
3968         off = ip_hdrlen(skb);
3969 
3970         err = -EPROTO;
3971 
3972         if (fragment)
3973                 goto out;
3974 
3975         csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
3976         if (IS_ERR(csum))
3977                 return PTR_ERR(csum);
3978 
3979         if (recalculate)
3980                 *csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
3981                                            ip_hdr(skb)->daddr,
3982                                            skb->len - off,
3983                                            ip_hdr(skb)->protocol, 0);
3984         err = 0;
3985 
3986 out:
3987         return err;
3988 }
3989 
3990 /* This value should be large enough to cover a tagged ethernet header plus
3991  * an IPv6 header, all options, and a maximal TCP or UDP header.
3992  */
3993 #define MAX_IPV6_HDR_LEN 256
3994 
3995 #define OPT_HDR(type, skb, off) \
3996         (type *)(skb_network_header(skb) + (off))
3997 
3998 static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
3999 {
4000         int err;
4001         u8 nexthdr;
4002         unsigned int off;
4003         unsigned int len;
4004         bool fragment;
4005         bool done;
4006         __sum16 *csum;
4007 
4008         fragment = false;
4009         done = false;
4010 
4011         off = sizeof(struct ipv6hdr);
4012 
4013         err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
4014         if (err < 0)
4015                 goto out;
4016 
4017         nexthdr = ipv6_hdr(skb)->nexthdr;
4018 
4019         len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
4020         while (off <= len && !done) {
4021                 switch (nexthdr) {
4022                 case IPPROTO_DSTOPTS:
4023                 case IPPROTO_HOPOPTS:
4024                 case IPPROTO_ROUTING: {
4025                         struct ipv6_opt_hdr *hp;
4026 
4027                         err = skb_maybe_pull_tail(skb,
4028                                                   off +
4029                                                   sizeof(struct ipv6_opt_hdr),
4030                                                   MAX_IPV6_HDR_LEN);
4031                         if (err < 0)
4032                                 goto out;
4033 
4034                         hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
4035                         nexthdr = hp->nexthdr;
4036                         off += ipv6_optlen(hp);
4037                         break;
4038                 }
4039                 case IPPROTO_AH: {
4040                         struct ip_auth_hdr *hp;
4041 
4042                         err = skb_maybe_pull_tail(skb,
4043                                                   off +
4044                                                   sizeof(struct ip_auth_hdr),
4045                                                   MAX_IPV6_HDR_LEN);
4046                         if (err < 0)
4047                                 goto out;
4048 
4049                         hp = OPT_HDR(struct ip_auth_hdr, skb, off);
4050                         nexthdr = hp->nexthdr;
4051                         off += ipv6_authlen(hp);
4052                         break;
4053                 }
4054                 case IPPROTO_FRAGMENT: {
4055                         struct frag_hdr *hp;
4056 
4057                         err = skb_maybe_pull_tail(skb,
4058                                                   off +
4059                                                   sizeof(struct frag_hdr),
4060                                                   MAX_IPV6_HDR_LEN);
4061                         if (err < 0)
4062                                 goto out;
4063 
4064                         hp = OPT_HDR(struct frag_hdr, skb, off);
4065 
4066                         if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
4067                                 fragment = true;
4068 
4069                         nexthdr = hp->nexthdr;
4070                         off += sizeof(struct frag_hdr);
4071                         break;
4072                 }
4073                 default:
4074                         done = true;
4075                         break;
4076                 }
4077         }
4078 
4079         err = -EPROTO;
4080 
4081         if (!done || fragment)
4082                 goto out;
4083 
4084         csum = skb_checksum_setup_ip(skb, nexthdr, off);
4085         if (IS_ERR(csum))
4086                 return PTR_ERR(csum);
4087 
4088         if (recalculate)
4089                 *csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
4090                                          &ipv6_hdr(skb)->daddr,
4091                                          skb->len - off, nexthdr, 0);
4092         err = 0;
4093 
4094 out:
4095         return err;
4096 }
4097 
4098 /**
4099  * skb_checksum_setup - set up partial checksum offset
4100  * @skb: the skb to set up
4101  * @recalculate: if true the pseudo-header checksum will be recalculated
4102  */
4103 int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
4104 {
4105         int err;
4106 
4107         switch (skb->protocol) {
4108         case htons(ETH_P_IP):
4109                 err = skb_checksum_setup_ipv4(skb, recalculate);
4110                 break;
4111 
4112         case htons(ETH_P_IPV6):
4113                 err = skb_checksum_setup_ipv6(skb, recalculate);
4114                 break;
4115 
4116         default:
4117                 err = -EPROTO;
4118                 break;
4119         }
4120 
4121         return err;
4122 }
4123 EXPORT_SYMBOL(skb_checksum_setup);
4124 
4125 /**
4126  * skb_checksum_maybe_trim - maybe trims the given skb
4127  * @skb: the skb to check
4128  * @transport_len: the data length beyond the network header
4129  *
4130  * Checks whether the given skb has data beyond the given transport length.
4131  * If so, returns a cloned skb trimmed to this transport length.
4132  * Otherwise returns the provided skb. Returns NULL in error cases
4133  * (e.g. transport_len exceeds skb length or out-of-memory).
4134  *
4135  * Caller needs to set the skb transport header and free any returned skb if it
4136  * differs from the provided skb.
4137  */
4138 static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
4139                                                unsigned int transport_len)
4140 {
4141         struct sk_buff *skb_chk;
4142         unsigned int len = skb_transport_offset(skb) + transport_len;
4143         int ret;
4144 
4145         if (skb->len < len)
4146                 return NULL;
4147         else if (skb->len == len)
4148                 return skb;
4149 
4150         skb_chk = skb_clone(skb, GFP_ATOMIC);
4151         if (!skb_chk)
4152                 return NULL;
4153 
4154         ret = pskb_trim_rcsum(skb_chk, len);
4155         if (ret) {
4156                 kfree_skb(skb_chk);
4157                 return NULL;
4158         }
4159 
4160         return skb_chk;
4161 }
4162 
4163 /**
4164  * skb_checksum_trimmed - validate checksum of an skb
4165  * @skb: the skb to check
4166  * @transport_len: the data length beyond the network header
4167  * @skb_chkf: checksum function to use
4168  *
4169  * Applies the given checksum function skb_chkf to the provided skb.
4170  * Returns a checked and maybe trimmed skb. Returns NULL on error.
4171  *
4172  * If the skb has data beyond the given transport length, then a
4173  * trimmed & cloned skb is checked and returned.
4174  *
4175  * Caller needs to set the skb transport header and free any returned skb if it
4176  * differs from the provided skb.
4177  */
4178 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
4179                                      unsigned int transport_len,
4180                                      __sum16(*skb_chkf)(struct sk_buff *skb))
4181 {
4182         struct sk_buff *skb_chk;
4183         unsigned int offset = skb_transport_offset(skb);
4184         __sum16 ret;
4185 
4186         skb_chk = skb_checksum_maybe_trim(skb, transport_len);
4187         if (!skb_chk)
4188                 goto err;
4189 
4190         if (!pskb_may_pull(skb_chk, offset))
4191                 goto err;
4192 
4193         skb_pull_rcsum(skb_chk, offset);
4194         ret = skb_chkf(skb_chk);
4195         skb_push_rcsum(skb_chk, offset);
4196 
4197         if (ret)
4198                 goto err;
4199 
4200         return skb_chk;
4201 
4202 err:
4203         if (skb_chk && skb_chk != skb)
4204                 kfree_skb(skb_chk);
4205 
4206         return NULL;
4207 
4208 }
4209 EXPORT_SYMBOL(skb_checksum_trimmed);
4210 
4211 void __skb_warn_lro_forwarding(const struct sk_buff *skb)
4212 {
4213         net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
4214                              skb->dev->name);
4215 }
4216 EXPORT_SYMBOL(__skb_warn_lro_forwarding);
4217 
4218 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
4219 {
4220         if (head_stolen) {
4221                 skb_release_head_state(skb);
4222                 kmem_cache_free(skbuff_head_cache, skb);
4223         } else {
4224                 __kfree_skb(skb);
4225         }
4226 }
4227 EXPORT_SYMBOL(kfree_skb_partial);
4228 
4229 /**
4230  * skb_try_coalesce - try to merge skb to prior one
4231  * @to: prior buffer
4232  * @from: buffer to add
4233  * @fragstolen: pointer to boolean
4234  * @delta_truesize: how much more was allocated than was requested
4235  */
4236 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
4237                       bool *fragstolen, int *delta_truesize)
4238 {
4239         int i, delta, len = from->len;
4240 
4241         *fragstolen = false;
4242 
4243         if (skb_cloned(to))
4244                 return false;
4245 
4246         if (len <= skb_tailroom(to)) {
4247                 if (len)
4248                         BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
4249                 *delta_truesize = 0;
4250                 return true;
4251         }
4252 
4253         if (skb_has_frag_list(to) || skb_has_frag_list(from))
4254                 return false;
4255 
4256         if (skb_headlen(from) != 0) {
4257                 struct page *page;
4258                 unsigned int offset;
4259 
4260                 if (skb_shinfo(to)->nr_frags +
4261                     skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
4262                         return false;
4263 
4264                 if (skb_head_is_locked(from))
4265                         return false;
4266 
4267                 delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
4268 
4269                 page = virt_to_head_page(from->head);
4270                 offset = from->data - (unsigned char *)page_address(page);
4271 
4272                 skb_fill_page_desc(to, skb_shinfo(to)->nr_frags,
4273                                    page, offset, skb_headlen(from));
4274                 *fragstolen = true;
4275         } else {
4276                 if (skb_shinfo(to)->nr_frags +
4277                     skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS)
4278                         return false;
4279 
4280                 delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
4281         }
4282 
4283         WARN_ON_ONCE(delta < len);
4284 
4285         memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags,
4286                skb_shinfo(from)->frags,
4287                skb_shinfo(from)->nr_frags * sizeof(skb_frag_t));
4288         skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags;
4289 
4290         if (!skb_cloned(from))
4291                 skb_shinfo(from)->nr_frags = 0;
4292 
4293         /* if the skb is not cloned this does nothing
4294          * since we set nr_frags to 0.
4295          */
4296         for (i = 0; i < skb_shinfo(from)->nr_frags; i++)
4297                 skb_frag_ref(from, i);
4298 
4299         to->truesize += delta;
4300         to->len += len;
4301         to->data_len += len;
4302 
4303         *delta_truesize = delta;
4304         return true;
4305 }
4306 EXPORT_SYMBOL(skb_try_coalesce);
4307 
4308 /**
4309  * skb_scrub_packet - scrub an skb
4310  *
4311  * @skb: buffer to clean
4312  * @xnet: packet is crossing netns
4313  *
4314  * skb_scrub_packet can be used after encapsulating or decapsulting a packet
4315  * into/from a tunnel. Some information have to be cleared during these
4316  * operations.
4317  * skb_scrub_packet can also be used to clean a skb before injecting it in
4318  * another namespace (@xnet == true). We have to clear all information in the
4319  * skb that could impact namespace isolation.
4320  */
4321 void skb_scrub_packet(struct sk_buff *skb, bool xnet)
4322 {
4323         skb->tstamp.tv64 = 0;
4324         skb->pkt_type = PACKET_HOST;
4325         skb->skb_iif = 0;
4326         skb->ignore_df = 0;
4327         skb_dst_drop(skb);
4328         secpath_reset(skb);
4329         nf_reset(skb);
4330         nf_reset_trace(skb);
4331 
4332         if (!xnet)
4333                 return;
4334 
4335         skb_orphan(skb);
4336         skb->mark = 0;
4337 }
4338 EXPORT_SYMBOL_GPL(skb_scrub_packet);
4339 
4340 /**
4341  * skb_gso_transport_seglen - Return length of individual segments of a gso packet
4342  *
4343  * @skb: GSO skb
4344  *
4345  * skb_gso_transport_seglen is used to determine the real size of the
4346  * individual segments, including Layer4 headers (TCP/UDP).
4347  *
4348  * The MAC/L2 or network (IP, IPv6) headers are not accounted for.
4349  */
4350 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
4351 {
4352         const struct skb_shared_info *shinfo = skb_shinfo(skb);
4353         unsigned int thlen = 0;
4354 
4355         if (skb->encapsulation) {
4356                 thlen = skb_inner_transport_header(skb) -
4357                         skb_transport_header(skb);
4358 
4359                 if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
4360                         thlen += inner_tcp_hdrlen(skb);
4361         } else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
4362                 thlen = tcp_hdrlen(skb);
4363         }
4364         /* UFO sets gso_size to the size of the fragmentation
4365          * payload, i.e. the size of the L4 (UDP) header is already
4366          * accounted for.
4367          */
4368         return thlen + shinfo->gso_size;
4369 }
4370 EXPORT_SYMBOL_GPL(skb_gso_transport_seglen);
4371 
4372 static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
4373 {
4374         if (skb_cow(skb, skb_headroom(skb)) < 0) {
4375                 kfree_skb(skb);
4376                 return NULL;
4377         }
4378 
4379         memmove(skb->data - ETH_HLEN, skb->data - skb->mac_len - VLAN_HLEN,
4380                 2 * ETH_ALEN);
4381         skb->mac_header += VLAN_HLEN;
4382         return skb;
4383 }
4384 
4385 struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
4386 {
4387         struct vlan_hdr *vhdr;
4388         u16 vlan_tci;
4389 
4390         if (unlikely(skb_vlan_tag_present(skb))) {
4391                 /* vlan_tci is already set-up so leave this for another time */
4392                 return skb;
4393         }
4394 
4395         skb = skb_share_check(skb, GFP_ATOMIC);
4396         if (unlikely(!skb))
4397                 goto err_free;
4398 
4399         if (unlikely(!pskb_may_pull(skb, VLAN_HLEN)))
4400                 goto err_free;
4401 
4402         vhdr = (struct vlan_hdr *)skb->data;
4403         vlan_tci = ntohs(vhdr->h_vlan_TCI);
4404         __vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
4405 
4406         skb_pull_rcsum(skb, VLAN_HLEN);
4407         vlan_set_encap_proto(skb, vhdr);
4408 
4409         skb = skb_reorder_vlan_header(skb);
4410         if (unlikely(!skb))
4411                 goto err_free;
4412 
4413         skb_reset_network_header(skb);
4414         skb_reset_transport_header(skb);
4415         skb_reset_mac_len(skb);
4416 
4417         return skb;
4418 
4419 err_free:
4420         kfree_skb(skb);
4421         return NULL;
4422 }
4423 EXPORT_SYMBOL(skb_vlan_untag);
4424 
4425 int skb_ensure_writable(struct sk_buff *skb, int write_len)
4426 {
4427         if (!pskb_may_pull(skb, write_len))
4428                 return -ENOMEM;
4429 
4430         if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
4431                 return 0;
4432 
4433         return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
4434 }
4435 EXPORT_SYMBOL(skb_ensure_writable);
4436 
4437 /* remove VLAN header from packet and update csum accordingly. */
4438 static int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
4439 {
4440         struct vlan_hdr *vhdr;
4441         unsigned int offset = skb->data - skb_mac_header(skb);
4442         int err;
4443 
4444         __skb_push(skb, offset);
4445         err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
4446         if (unlikely(err))
4447                 goto pull;
4448 
4449         skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
4450 
4451         vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
4452         *vlan_tci = ntohs(vhdr->h_vlan_TCI);
4453 
4454         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
4455         __skb_pull(skb, VLAN_HLEN);
4456 
4457         vlan_set_encap_proto(skb, vhdr);
4458         skb->mac_header += VLAN_HLEN;
4459 
4460         if (skb_network_offset(skb) < ETH_HLEN)
4461                 skb_set_network_header(skb, ETH_HLEN);
4462 
4463         skb_reset_mac_len(skb);
4464 pull:
4465         __skb_pull(skb, offset);
4466 
4467         return err;
4468 }
4469 
4470 int skb_vlan_pop(struct sk_buff *skb)
4471 {
4472         u16 vlan_tci;
4473         __be16 vlan_proto;
4474         int err;
4475 
4476         if (likely(skb_vlan_tag_present(skb))) {
4477                 skb->vlan_tci = 0;
4478         } else {
4479                 if (unlikely((skb->protocol != htons(ETH_P_8021Q) &&
4480                               skb->protocol != htons(ETH_P_8021AD)) ||
4481                              skb->len < VLAN_ETH_HLEN))
4482                         return 0;
4483 
4484                 err = __skb_vlan_pop(skb, &vlan_tci);
4485                 if (err)
4486                         return err;
4487         }
4488         /* move next vlan tag to hw accel tag */
4489         if (likely((skb->protocol != htons(ETH_P_8021Q) &&
4490                     skb->protocol != htons(ETH_P_8021AD)) ||
4491                    skb->len < VLAN_ETH_HLEN))
4492                 return 0;
4493 
4494         vlan_proto = skb->protocol;
4495         err = __skb_vlan_pop(skb, &vlan_tci);
4496         if (unlikely(err))
4497                 return err;
4498 
4499         __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
4500         return 0;
4501 }
4502 EXPORT_SYMBOL(skb_vlan_pop);
4503 
4504 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
4505 {
4506         if (skb_vlan_tag_present(skb)) {
4507                 unsigned int offset = skb->data - skb_mac_header(skb);
4508                 int err;
4509 
4510                 /* __vlan_insert_tag expect skb->data pointing to mac header.
4511                  * So change skb->data before calling it and change back to
4512                  * original position later
4513                  */
4514                 __skb_push(skb, offset);
4515                 err = __vlan_insert_tag(skb, skb->vlan_proto,
4516                                         skb_vlan_tag_get(skb));
4517                 if (err) {
4518                         __skb_pull(skb, offset);
4519                         return err;
4520                 }
4521 
4522                 skb->protocol = skb->vlan_proto;
4523                 skb->mac_len += VLAN_HLEN;
4524 
4525                 skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
4526                 __skb_pull(skb, offset);
4527         }
4528         __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
4529         return 0;
4530 }
4531 EXPORT_SYMBOL(skb_vlan_push);
4532 
4533 /**
4534  * alloc_skb_with_frags - allocate skb with page frags
4535  *
4536  * @header_len: size of linear part
4537  * @data_len: needed length in frags
4538  * @max_page_order: max page order desired.
4539  * @errcode: pointer to error code if any
4540  * @gfp_mask: allocation mask
4541  *
4542  * This can be used to allocate a paged skb, given a maximal order for frags.
4543  */
4544 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
4545                                      unsigned long data_len,
4546                                      int max_page_order,
4547                                      int *errcode,
4548                                      gfp_t gfp_mask)
4549 {
4550         int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
4551         unsigned long chunk;
4552         struct sk_buff *skb;
4553         struct page *page;
4554         gfp_t gfp_head;
4555         int i;
4556 
4557         *errcode = -EMSGSIZE;
4558         /* Note this test could be relaxed, if we succeed to allocate
4559          * high order pages...
4560          */
4561         if (npages > MAX_SKB_FRAGS)
4562                 return NULL;
4563 
4564         gfp_head = gfp_mask;
4565         if (gfp_head & __GFP_DIRECT_RECLAIM)
4566                 gfp_head |= __GFP_REPEAT;
4567 
4568         *errcode = -ENOBUFS;
4569         skb = alloc_skb(header_len, gfp_head);
4570         if (!skb)
4571                 return NULL;
4572 
4573         skb->truesize += npages << PAGE_SHIFT;
4574 
4575         for (i = 0; npages > 0; i++) {
4576                 int order = max_page_order;
4577 
4578                 while (order) {
4579                         if (npages >= 1 << order) {
4580                                 page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
4581                                                    __GFP_COMP |
4582                                                    __GFP_NOWARN |
4583                                                    __GFP_NORETRY,
4584                                                    order);
4585                                 if (page)
4586                                         goto fill_page;
4587                                 /* Do not retry other high order allocations */
4588                                 order = 1;
4589                                 max_page_order = 0;
4590                         }
4591                         order--;
4592                 }
4593                 page = alloc_page(gfp_mask);
4594                 if (!page)
4595                         goto failure;
4596 fill_page:
4597                 chunk = min_t(unsigned long, data_len,
4598                               PAGE_SIZE << order);
4599                 skb_fill_page_desc(skb, i, page, 0, chunk);
4600                 data_len -= chunk;
4601                 npages -= 1 << order;
4602         }
4603         return skb;
4604 
4605 failure:
4606         kfree_skb(skb);
4607         return NULL;
4608 }
4609 EXPORT_SYMBOL(alloc_skb_with_frags);
4610 
4611 /* carve out the first off bytes from skb when off < headlen */
4612 static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
4613                                     const int headlen, gfp_t gfp_mask)
4614 {
4615         int i;
4616         int size = skb_end_offset(skb);
4617         int new_hlen = headlen - off;
4618         u8 *data;
4619 
4620         size = SKB_DATA_ALIGN(size);
4621 
4622         if (skb_pfmemalloc(skb))
4623                 gfp_mask |= __GFP_MEMALLOC;
4624         data = kmalloc_reserve(size +
4625                                SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
4626                                gfp_mask, NUMA_NO_NODE, NULL);
4627         if (!data)
4628                 return -ENOMEM;
4629 
4630         size = SKB_WITH_OVERHEAD(ksize(data));
4631 
4632         /* Copy real data, and all frags */
4633         skb_copy_from_linear_data_offset(skb, off, data, new_hlen);
4634         skb->len -= off;
4635 
4636         memcpy((struct skb_shared_info *)(data + size),
4637                skb_shinfo(skb),
4638                offsetof(struct skb_shared_info,
4639                         frags[skb_shinfo(skb)->nr_frags]));
4640         if (skb_cloned(skb)) {
4641                 /* drop the old head gracefully */
4642                 if (skb_orphan_frags(skb, gfp_mask)) {
4643                         kfree(data);
4644                         return -ENOMEM;
4645                 }
4646                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
4647                         skb_frag_ref(skb, i);
4648                 if (skb_has_frag_list(skb))
4649                         skb_clone_fraglist(skb);
4650                 skb_release_data(skb);
4651         } else {
4652                 /* we can reuse existing recount- all we did was
4653                  * relocate values
4654                  */
4655                 skb_free_head(skb);
4656         }
4657 
4658         skb->head = data;
4659         skb->data = data;
4660         skb->head_frag = 0;
4661 #ifdef NET_SKBUFF_DATA_USES_OFFSET
4662         skb->end = size;
4663 #else
4664         skb->end = skb->head + size;
4665 #endif
4666         skb_set_tail_pointer(skb, skb_headlen(skb));
4667         skb_headers_offset_update(skb, 0);
4668         skb->cloned = 0;
4669         skb->hdr_len = 0;
4670         skb->nohdr = 0;
4671         atomic_set(&skb_shinfo(skb)->dataref, 1);
4672 
4673         return 0;
4674 }
4675 
4676 static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
4677 
4678 /* carve out the first eat bytes from skb's frag_list. May recurse into
4679  * pskb_carve()
4680  */
4681 static int pskb_carve_frag_list(struct sk_buff *skb,
4682                                 struct skb_shared_info *shinfo, int eat,
4683                                 gfp_t gfp_mask)
4684 {
4685         struct sk_buff *list = shinfo->frag_list;
4686         struct sk_buff *clone = NULL;
4687         struct sk_buff *insp = NULL;
4688 
4689         do {
4690                 if (!list) {
4691                         pr_err("Not enough bytes to eat. Want %d\n", eat);
4692                         return -EFAULT;
4693                 }
4694                 if (list->len <= eat) {
4695                         /* Eaten as whole. */
4696                         eat -= list->len;
4697                         list = list->next;
4698                         insp = list;
4699                 } else {
4700                         /* Eaten partially. */
4701                         if (skb_shared(list)) {
4702                                 clone = skb_clone(list, gfp_mask);
4703                                 if (!clone)
4704                                         return -ENOMEM;
4705                                 insp = list->next;
4706                                 list = clone;
4707                         } else {
4708                                 /* This may be pulled without problems. */
4709                                 insp = list;
4710                         }
4711                         if (pskb_carve(list, eat, gfp_mask) < 0) {
4712                                 kfree_skb(clone);
4713                                 return -ENOMEM;
4714                         }
4715                         break;
4716                 }
4717         } while (eat);
4718 
4719         /* Free pulled out fragments. */
4720         while ((list = shinfo->frag_list) != insp) {
4721                 shinfo->frag_list = list->next;
4722                 kfree_skb(list);
4723         }
4724         /* And insert new clone at head. */
4725         if (clone) {
4726                 clone->next = list;
4727                 shinfo->frag_list = clone;
4728         }
4729         return 0;
4730 }
4731 
4732 /* carve off first len bytes from skb. Split line (off) is in the
4733  * non-linear part of skb
4734  */
4735 static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
4736                                        int pos, gfp_t gfp_mask)
4737 {
4738         int i, k = 0;
4739         int size = skb_end_offset(skb);
4740         u8 *data;
4741         const int nfrags = skb_shinfo(skb)->nr_frags;
4742         struct skb_shared_info *shinfo;
4743 
4744         size = SKB_DATA_ALIGN(size);
4745 
4746         if (skb_pfmemalloc(skb))
4747                 gfp_mask |= __GFP_MEMALLOC;
4748         data = kmalloc_reserve(size +
4749                                SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
4750                                gfp_mask, NUMA_NO_NODE, NULL);
4751         if (!data)
4752                 return -ENOMEM;
4753 
4754         size = SKB_WITH_OVERHEAD(ksize(data));
4755 
4756         memcpy((struct skb_shared_info *)(data + size),
4757                skb_shinfo(skb), offsetof(struct skb_shared_info,
4758                                          frags[skb_shinfo(skb)->nr_frags]));
4759         if (skb_orphan_frags(skb, gfp_mask)) {
4760                 kfree(data);
4761                 return -ENOMEM;
4762         }
4763         shinfo = (struct skb_shared_info *)(data + size);
4764         for (i = 0; i < nfrags; i++) {
4765                 int fsize = skb_frag_size(&skb_shinfo(skb)->frags[i]);
4766 
4767                 if (pos + fsize > off) {
4768                         shinfo->frags[k] = skb_shinfo(skb)->frags[i];
4769 
4770                         if (pos < off) {
4771                                 /* Split frag.
4772                                  * We have two variants in this case:
4773                                  * 1. Move all the frag to the second
4774                                  *    part, if it is possible. F.e.
4775                                  *    this approach is mandatory for TUX,
4776                                  *    where splitting is expensive.
4777                                  * 2. Split is accurately. We make this.
4778                                  */
4779                                 shinfo->frags[0].page_offset += off - pos;
4780                                 skb_frag_size_sub(&shinfo->frags[0], off - pos);
4781                         }
4782                         skb_frag_ref(skb, i);
4783                         k++;
4784                 }
4785                 pos += fsize;
4786         }
4787         shinfo->nr_frags = k;
4788         if (skb_has_frag_list(skb))
4789                 skb_clone_fraglist(skb);
4790 
4791         if (k == 0) {
4792                 /* split line is in frag list */
4793                 pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask);
4794         }
4795         skb_release_data(skb);
4796 
4797         skb->head = data;
4798         skb->head_frag = 0;
4799         skb->data = data;
4800 #ifdef NET_SKBUFF_DATA_USES_OFFSET
4801         skb->end = size;
4802 #else
4803         skb->end = skb->head + size;
4804 #endif
4805         skb_reset_tail_pointer(skb);
4806         skb_headers_offset_update(skb, 0);
4807         skb->cloned   = 0;
4808         skb->hdr_len  = 0;
4809         skb->nohdr    = 0;
4810         skb->len -= off;
4811         skb->data_len = skb->len;
4812         atomic_set(&skb_shinfo(skb)->dataref, 1);
4813         return 0;
4814 }
4815 
4816 /* remove len bytes from the beginning of the skb */
4817 static int pskb_carve(struct sk_buff *skb, const u32 len, gfp_t gfp)
4818 {
4819         int headlen = skb_headlen(skb);
4820 
4821         if (len < headlen)
4822                 return pskb_carve_inside_header(skb, len, headlen, gfp);
4823         else
4824                 return pskb_carve_inside_nonlinear(skb, len, headlen, gfp);
4825 }
4826 
4827 /* Extract to_copy bytes starting at off from skb, and return this in
4828  * a new skb
4829  */
4830 struct sk_buff *pskb_extract(struct sk_buff *skb, int off,
4831                              int to_copy, gfp_t gfp)
4832 {
4833         struct sk_buff  *clone = skb_clone(skb, gfp);
4834 
4835         if (!clone)
4836                 return NULL;
4837 
4838         if (pskb_carve(clone, off, gfp) < 0 ||
4839             pskb_trim(clone, to_copy)) {
4840                 kfree_skb(clone);
4841                 return NULL;
4842         }
4843         return clone;
4844 }
4845 EXPORT_SYMBOL(pskb_extract);
4846 

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