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TOMOYO Linux Cross Reference
Linux/net/core/skbuff.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  *      Routines having to do with the 'struct sk_buff' memory handlers.
  4  *
  5  *      Authors:        Alan Cox <alan@lxorguk.ukuu.org.uk>
  6  *                      Florian La Roche <rzsfl@rz.uni-sb.de>
  7  *
  8  *      Fixes:
  9  *              Alan Cox        :       Fixed the worst of the load
 10  *                                      balancer bugs.
 11  *              Dave Platt      :       Interrupt stacking fix.
 12  *      Richard Kooijman        :       Timestamp fixes.
 13  *              Alan Cox        :       Changed buffer format.
 14  *              Alan Cox        :       destructor hook for AF_UNIX etc.
 15  *              Linus Torvalds  :       Better skb_clone.
 16  *              Alan Cox        :       Added skb_copy.
 17  *              Alan Cox        :       Added all the changed routines Linus
 18  *                                      only put in the headers
 19  *              Ray VanTassle   :       Fixed --skb->lock in free
 20  *              Alan Cox        :       skb_copy copy arp field
 21  *              Andi Kleen      :       slabified it.
 22  *              Robert Olsson   :       Removed skb_head_pool
 23  *
 24  *      NOTE:
 25  *              The __skb_ routines should be called with interrupts
 26  *      disabled, or you better be *real* sure that the operation is atomic
 27  *      with respect to whatever list is being frobbed (e.g. via lock_sock()
 28  *      or via disabling bottom half handlers, etc).
 29  */
 30 
 31 /*
 32  *      The functions in this file will not compile correctly with gcc 2.4.x
 33  */
 34 
 35 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 36 
 37 #include <linux/module.h>
 38 #include <linux/types.h>
 39 #include <linux/kernel.h>
 40 #include <linux/mm.h>
 41 #include <linux/interrupt.h>
 42 #include <linux/in.h>
 43 #include <linux/inet.h>
 44 #include <linux/slab.h>
 45 #include <linux/tcp.h>
 46 #include <linux/udp.h>
 47 #include <linux/sctp.h>
 48 #include <linux/netdevice.h>
 49 #ifdef CONFIG_NET_CLS_ACT
 50 #include <net/pkt_sched.h>
 51 #endif
 52 #include <linux/string.h>
 53 #include <linux/skbuff.h>
 54 #include <linux/splice.h>
 55 #include <linux/cache.h>
 56 #include <linux/rtnetlink.h>
 57 #include <linux/init.h>
 58 #include <linux/scatterlist.h>
 59 #include <linux/errqueue.h>
 60 #include <linux/prefetch.h>
 61 #include <linux/if_vlan.h>
 62 #include <linux/mpls.h>
 63 
 64 #include <net/protocol.h>
 65 #include <net/dst.h>
 66 #include <net/sock.h>
 67 #include <net/checksum.h>
 68 #include <net/ip6_checksum.h>
 69 #include <net/xfrm.h>
 70 #include <net/mpls.h>
 71 
 72 #include <linux/uaccess.h>
 73 #include <trace/events/skb.h>
 74 #include <linux/highmem.h>
 75 #include <linux/capability.h>
 76 #include <linux/user_namespace.h>
 77 #include <linux/indirect_call_wrapper.h>
 78 
 79 #include "datagram.h"
 80 
 81 struct kmem_cache *skbuff_head_cache __ro_after_init;
 82 static struct kmem_cache *skbuff_fclone_cache __ro_after_init;
 83 #ifdef CONFIG_SKB_EXTENSIONS
 84 static struct kmem_cache *skbuff_ext_cache __ro_after_init;
 85 #endif
 86 int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
 87 EXPORT_SYMBOL(sysctl_max_skb_frags);
 88 
 89 /**
 90  *      skb_panic - private function for out-of-line support
 91  *      @skb:   buffer
 92  *      @sz:    size
 93  *      @addr:  address
 94  *      @msg:   skb_over_panic or skb_under_panic
 95  *
 96  *      Out-of-line support for skb_put() and skb_push().
 97  *      Called via the wrapper skb_over_panic() or skb_under_panic().
 98  *      Keep out of line to prevent kernel bloat.
 99  *      __builtin_return_address is not used because it is not always reliable.
100  */
101 static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
102                       const char msg[])
103 {
104         pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n",
105                  msg, addr, skb->len, sz, skb->head, skb->data,
106                  (unsigned long)skb->tail, (unsigned long)skb->end,
107                  skb->dev ? skb->dev->name : "<NULL>");
108         BUG();
109 }
110 
111 static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
112 {
113         skb_panic(skb, sz, addr, __func__);
114 }
115 
116 static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
117 {
118         skb_panic(skb, sz, addr, __func__);
119 }
120 
121 /*
122  * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
123  * the caller if emergency pfmemalloc reserves are being used. If it is and
124  * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
125  * may be used. Otherwise, the packet data may be discarded until enough
126  * memory is free
127  */
128 #define kmalloc_reserve(size, gfp, node, pfmemalloc) \
129          __kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc)
130 
131 static void *__kmalloc_reserve(size_t size, gfp_t flags, int node,
132                                unsigned long ip, bool *pfmemalloc)
133 {
134         void *obj;
135         bool ret_pfmemalloc = false;
136 
137         /*
138          * Try a regular allocation, when that fails and we're not entitled
139          * to the reserves, fail.
140          */
141         obj = kmalloc_node_track_caller(size,
142                                         flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
143                                         node);
144         if (obj || !(gfp_pfmemalloc_allowed(flags)))
145                 goto out;
146 
147         /* Try again but now we are using pfmemalloc reserves */
148         ret_pfmemalloc = true;
149         obj = kmalloc_node_track_caller(size, flags, node);
150 
151 out:
152         if (pfmemalloc)
153                 *pfmemalloc = ret_pfmemalloc;
154 
155         return obj;
156 }
157 
158 /*      Allocate a new skbuff. We do this ourselves so we can fill in a few
159  *      'private' fields and also do memory statistics to find all the
160  *      [BEEP] leaks.
161  *
162  */
163 
164 /**
165  *      __alloc_skb     -       allocate a network buffer
166  *      @size: size to allocate
167  *      @gfp_mask: allocation mask
168  *      @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
169  *              instead of head cache and allocate a cloned (child) skb.
170  *              If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
171  *              allocations in case the data is required for writeback
172  *      @node: numa node to allocate memory on
173  *
174  *      Allocate a new &sk_buff. The returned buffer has no headroom and a
175  *      tail room of at least size bytes. The object has a reference count
176  *      of one. The return is the buffer. On a failure the return is %NULL.
177  *
178  *      Buffers may only be allocated from interrupts using a @gfp_mask of
179  *      %GFP_ATOMIC.
180  */
181 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
182                             int flags, int node)
183 {
184         struct kmem_cache *cache;
185         struct skb_shared_info *shinfo;
186         struct sk_buff *skb;
187         u8 *data;
188         bool pfmemalloc;
189 
190         cache = (flags & SKB_ALLOC_FCLONE)
191                 ? skbuff_fclone_cache : skbuff_head_cache;
192 
193         if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
194                 gfp_mask |= __GFP_MEMALLOC;
195 
196         /* Get the HEAD */
197         skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
198         if (!skb)
199                 goto out;
200         prefetchw(skb);
201 
202         /* We do our best to align skb_shared_info on a separate cache
203          * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
204          * aligned memory blocks, unless SLUB/SLAB debug is enabled.
205          * Both skb->head and skb_shared_info are cache line aligned.
206          */
207         size = SKB_DATA_ALIGN(size);
208         size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
209         data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
210         if (!data)
211                 goto nodata;
212         /* kmalloc(size) might give us more room than requested.
213          * Put skb_shared_info exactly at the end of allocated zone,
214          * to allow max possible filling before reallocation.
215          */
216         size = SKB_WITH_OVERHEAD(ksize(data));
217         prefetchw(data + size);
218 
219         /*
220          * Only clear those fields we need to clear, not those that we will
221          * actually initialise below. Hence, don't put any more fields after
222          * the tail pointer in struct sk_buff!
223          */
224         memset(skb, 0, offsetof(struct sk_buff, tail));
225         /* Account for allocated memory : skb + skb->head */
226         skb->truesize = SKB_TRUESIZE(size);
227         skb->pfmemalloc = pfmemalloc;
228         refcount_set(&skb->users, 1);
229         skb->head = data;
230         skb->data = data;
231         skb_reset_tail_pointer(skb);
232         skb->end = skb->tail + size;
233         skb->mac_header = (typeof(skb->mac_header))~0U;
234         skb->transport_header = (typeof(skb->transport_header))~0U;
235 
236         /* make sure we initialize shinfo sequentially */
237         shinfo = skb_shinfo(skb);
238         memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
239         atomic_set(&shinfo->dataref, 1);
240 
241         if (flags & SKB_ALLOC_FCLONE) {
242                 struct sk_buff_fclones *fclones;
243 
244                 fclones = container_of(skb, struct sk_buff_fclones, skb1);
245 
246                 skb->fclone = SKB_FCLONE_ORIG;
247                 refcount_set(&fclones->fclone_ref, 1);
248 
249                 fclones->skb2.fclone = SKB_FCLONE_CLONE;
250         }
251 out:
252         return skb;
253 nodata:
254         kmem_cache_free(cache, skb);
255         skb = NULL;
256         goto out;
257 }
258 EXPORT_SYMBOL(__alloc_skb);
259 
260 /* Caller must provide SKB that is memset cleared */
261 static struct sk_buff *__build_skb_around(struct sk_buff *skb,
262                                           void *data, unsigned int frag_size)
263 {
264         struct skb_shared_info *shinfo;
265         unsigned int size = frag_size ? : ksize(data);
266 
267         size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
268 
269         /* Assumes caller memset cleared SKB */
270         skb->truesize = SKB_TRUESIZE(size);
271         refcount_set(&skb->users, 1);
272         skb->head = data;
273         skb->data = data;
274         skb_reset_tail_pointer(skb);
275         skb->end = skb->tail + size;
276         skb->mac_header = (typeof(skb->mac_header))~0U;
277         skb->transport_header = (typeof(skb->transport_header))~0U;
278 
279         /* make sure we initialize shinfo sequentially */
280         shinfo = skb_shinfo(skb);
281         memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
282         atomic_set(&shinfo->dataref, 1);
283 
284         return skb;
285 }
286 
287 /**
288  * __build_skb - build a network buffer
289  * @data: data buffer provided by caller
290  * @frag_size: size of data, or 0 if head was kmalloced
291  *
292  * Allocate a new &sk_buff. Caller provides space holding head and
293  * skb_shared_info. @data must have been allocated by kmalloc() only if
294  * @frag_size is 0, otherwise data should come from the page allocator
295  *  or vmalloc()
296  * The return is the new skb buffer.
297  * On a failure the return is %NULL, and @data is not freed.
298  * Notes :
299  *  Before IO, driver allocates only data buffer where NIC put incoming frame
300  *  Driver should add room at head (NET_SKB_PAD) and
301  *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
302  *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
303  *  before giving packet to stack.
304  *  RX rings only contains data buffers, not full skbs.
305  */
306 struct sk_buff *__build_skb(void *data, unsigned int frag_size)
307 {
308         struct sk_buff *skb;
309 
310         skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
311         if (unlikely(!skb))
312                 return NULL;
313 
314         memset(skb, 0, offsetof(struct sk_buff, tail));
315 
316         return __build_skb_around(skb, data, frag_size);
317 }
318 
319 /* build_skb() is wrapper over __build_skb(), that specifically
320  * takes care of skb->head and skb->pfmemalloc
321  * This means that if @frag_size is not zero, then @data must be backed
322  * by a page fragment, not kmalloc() or vmalloc()
323  */
324 struct sk_buff *build_skb(void *data, unsigned int frag_size)
325 {
326         struct sk_buff *skb = __build_skb(data, frag_size);
327 
328         if (skb && frag_size) {
329                 skb->head_frag = 1;
330                 if (page_is_pfmemalloc(virt_to_head_page(data)))
331                         skb->pfmemalloc = 1;
332         }
333         return skb;
334 }
335 EXPORT_SYMBOL(build_skb);
336 
337 /**
338  * build_skb_around - build a network buffer around provided skb
339  * @skb: sk_buff provide by caller, must be memset cleared
340  * @data: data buffer provided by caller
341  * @frag_size: size of data, or 0 if head was kmalloced
342  */
343 struct sk_buff *build_skb_around(struct sk_buff *skb,
344                                  void *data, unsigned int frag_size)
345 {
346         if (unlikely(!skb))
347                 return NULL;
348 
349         skb = __build_skb_around(skb, data, frag_size);
350 
351         if (skb && frag_size) {
352                 skb->head_frag = 1;
353                 if (page_is_pfmemalloc(virt_to_head_page(data)))
354                         skb->pfmemalloc = 1;
355         }
356         return skb;
357 }
358 EXPORT_SYMBOL(build_skb_around);
359 
360 #define NAPI_SKB_CACHE_SIZE     64
361 
362 struct napi_alloc_cache {
363         struct page_frag_cache page;
364         unsigned int skb_count;
365         void *skb_cache[NAPI_SKB_CACHE_SIZE];
366 };
367 
368 static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
369 static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache);
370 
371 static void *__napi_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
372 {
373         struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
374 
375         return page_frag_alloc(&nc->page, fragsz, gfp_mask);
376 }
377 
378 void *napi_alloc_frag(unsigned int fragsz)
379 {
380         fragsz = SKB_DATA_ALIGN(fragsz);
381 
382         return __napi_alloc_frag(fragsz, GFP_ATOMIC);
383 }
384 EXPORT_SYMBOL(napi_alloc_frag);
385 
386 /**
387  * netdev_alloc_frag - allocate a page fragment
388  * @fragsz: fragment size
389  *
390  * Allocates a frag from a page for receive buffer.
391  * Uses GFP_ATOMIC allocations.
392  */
393 void *netdev_alloc_frag(unsigned int fragsz)
394 {
395         struct page_frag_cache *nc;
396         void *data;
397 
398         fragsz = SKB_DATA_ALIGN(fragsz);
399         if (in_irq() || irqs_disabled()) {
400                 nc = this_cpu_ptr(&netdev_alloc_cache);
401                 data = page_frag_alloc(nc, fragsz, GFP_ATOMIC);
402         } else {
403                 local_bh_disable();
404                 data = __napi_alloc_frag(fragsz, GFP_ATOMIC);
405                 local_bh_enable();
406         }
407         return data;
408 }
409 EXPORT_SYMBOL(netdev_alloc_frag);
410 
411 /**
412  *      __netdev_alloc_skb - allocate an skbuff for rx on a specific device
413  *      @dev: network device to receive on
414  *      @len: length to allocate
415  *      @gfp_mask: get_free_pages mask, passed to alloc_skb
416  *
417  *      Allocate a new &sk_buff and assign it a usage count of one. The
418  *      buffer has NET_SKB_PAD headroom built in. Users should allocate
419  *      the headroom they think they need without accounting for the
420  *      built in space. The built in space is used for optimisations.
421  *
422  *      %NULL is returned if there is no free memory.
423  */
424 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
425                                    gfp_t gfp_mask)
426 {
427         struct page_frag_cache *nc;
428         struct sk_buff *skb;
429         bool pfmemalloc;
430         void *data;
431 
432         len += NET_SKB_PAD;
433 
434         if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
435             (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
436                 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
437                 if (!skb)
438                         goto skb_fail;
439                 goto skb_success;
440         }
441 
442         len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
443         len = SKB_DATA_ALIGN(len);
444 
445         if (sk_memalloc_socks())
446                 gfp_mask |= __GFP_MEMALLOC;
447 
448         if (in_irq() || irqs_disabled()) {
449                 nc = this_cpu_ptr(&netdev_alloc_cache);
450                 data = page_frag_alloc(nc, len, gfp_mask);
451                 pfmemalloc = nc->pfmemalloc;
452         } else {
453                 local_bh_disable();
454                 nc = this_cpu_ptr(&napi_alloc_cache.page);
455                 data = page_frag_alloc(nc, len, gfp_mask);
456                 pfmemalloc = nc->pfmemalloc;
457                 local_bh_enable();
458         }
459 
460         if (unlikely(!data))
461                 return NULL;
462 
463         skb = __build_skb(data, len);
464         if (unlikely(!skb)) {
465                 skb_free_frag(data);
466                 return NULL;
467         }
468 
469         /* use OR instead of assignment to avoid clearing of bits in mask */
470         if (pfmemalloc)
471                 skb->pfmemalloc = 1;
472         skb->head_frag = 1;
473 
474 skb_success:
475         skb_reserve(skb, NET_SKB_PAD);
476         skb->dev = dev;
477 
478 skb_fail:
479         return skb;
480 }
481 EXPORT_SYMBOL(__netdev_alloc_skb);
482 
483 /**
484  *      __napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
485  *      @napi: napi instance this buffer was allocated for
486  *      @len: length to allocate
487  *      @gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
488  *
489  *      Allocate a new sk_buff for use in NAPI receive.  This buffer will
490  *      attempt to allocate the head from a special reserved region used
491  *      only for NAPI Rx allocation.  By doing this we can save several
492  *      CPU cycles by avoiding having to disable and re-enable IRQs.
493  *
494  *      %NULL is returned if there is no free memory.
495  */
496 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
497                                  gfp_t gfp_mask)
498 {
499         struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
500         struct sk_buff *skb;
501         void *data;
502 
503         len += NET_SKB_PAD + NET_IP_ALIGN;
504 
505         if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
506             (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
507                 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
508                 if (!skb)
509                         goto skb_fail;
510                 goto skb_success;
511         }
512 
513         len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
514         len = SKB_DATA_ALIGN(len);
515 
516         if (sk_memalloc_socks())
517                 gfp_mask |= __GFP_MEMALLOC;
518 
519         data = page_frag_alloc(&nc->page, len, gfp_mask);
520         if (unlikely(!data))
521                 return NULL;
522 
523         skb = __build_skb(data, len);
524         if (unlikely(!skb)) {
525                 skb_free_frag(data);
526                 return NULL;
527         }
528 
529         /* use OR instead of assignment to avoid clearing of bits in mask */
530         if (nc->page.pfmemalloc)
531                 skb->pfmemalloc = 1;
532         skb->head_frag = 1;
533 
534 skb_success:
535         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
536         skb->dev = napi->dev;
537 
538 skb_fail:
539         return skb;
540 }
541 EXPORT_SYMBOL(__napi_alloc_skb);
542 
543 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
544                      int size, unsigned int truesize)
545 {
546         skb_fill_page_desc(skb, i, page, off, size);
547         skb->len += size;
548         skb->data_len += size;
549         skb->truesize += truesize;
550 }
551 EXPORT_SYMBOL(skb_add_rx_frag);
552 
553 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
554                           unsigned int truesize)
555 {
556         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
557 
558         skb_frag_size_add(frag, size);
559         skb->len += size;
560         skb->data_len += size;
561         skb->truesize += truesize;
562 }
563 EXPORT_SYMBOL(skb_coalesce_rx_frag);
564 
565 static void skb_drop_list(struct sk_buff **listp)
566 {
567         kfree_skb_list(*listp);
568         *listp = NULL;
569 }
570 
571 static inline void skb_drop_fraglist(struct sk_buff *skb)
572 {
573         skb_drop_list(&skb_shinfo(skb)->frag_list);
574 }
575 
576 static void skb_clone_fraglist(struct sk_buff *skb)
577 {
578         struct sk_buff *list;
579 
580         skb_walk_frags(skb, list)
581                 skb_get(list);
582 }
583 
584 static void skb_free_head(struct sk_buff *skb)
585 {
586         unsigned char *head = skb->head;
587 
588         if (skb->head_frag)
589                 skb_free_frag(head);
590         else
591                 kfree(head);
592 }
593 
594 static void skb_release_data(struct sk_buff *skb)
595 {
596         struct skb_shared_info *shinfo = skb_shinfo(skb);
597         int i;
598 
599         if (skb->cloned &&
600             atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
601                               &shinfo->dataref))
602                 return;
603 
604         for (i = 0; i < shinfo->nr_frags; i++)
605                 __skb_frag_unref(&shinfo->frags[i]);
606 
607         if (shinfo->frag_list)
608                 kfree_skb_list(shinfo->frag_list);
609 
610         skb_zcopy_clear(skb, true);
611         skb_free_head(skb);
612 }
613 
614 /*
615  *      Free an skbuff by memory without cleaning the state.
616  */
617 static void kfree_skbmem(struct sk_buff *skb)
618 {
619         struct sk_buff_fclones *fclones;
620 
621         switch (skb->fclone) {
622         case SKB_FCLONE_UNAVAILABLE:
623                 kmem_cache_free(skbuff_head_cache, skb);
624                 return;
625 
626         case SKB_FCLONE_ORIG:
627                 fclones = container_of(skb, struct sk_buff_fclones, skb1);
628 
629                 /* We usually free the clone (TX completion) before original skb
630                  * This test would have no chance to be true for the clone,
631                  * while here, branch prediction will be good.
632                  */
633                 if (refcount_read(&fclones->fclone_ref) == 1)
634                         goto fastpath;
635                 break;
636 
637         default: /* SKB_FCLONE_CLONE */
638                 fclones = container_of(skb, struct sk_buff_fclones, skb2);
639                 break;
640         }
641         if (!refcount_dec_and_test(&fclones->fclone_ref))
642                 return;
643 fastpath:
644         kmem_cache_free(skbuff_fclone_cache, fclones);
645 }
646 
647 void skb_release_head_state(struct sk_buff *skb)
648 {
649         skb_dst_drop(skb);
650         if (skb->destructor) {
651                 WARN_ON(in_irq());
652                 skb->destructor(skb);
653         }
654 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
655         nf_conntrack_put(skb_nfct(skb));
656 #endif
657         skb_ext_put(skb);
658 }
659 
660 /* Free everything but the sk_buff shell. */
661 static void skb_release_all(struct sk_buff *skb)
662 {
663         skb_release_head_state(skb);
664         if (likely(skb->head))
665                 skb_release_data(skb);
666 }
667 
668 /**
669  *      __kfree_skb - private function
670  *      @skb: buffer
671  *
672  *      Free an sk_buff. Release anything attached to the buffer.
673  *      Clean the state. This is an internal helper function. Users should
674  *      always call kfree_skb
675  */
676 
677 void __kfree_skb(struct sk_buff *skb)
678 {
679         skb_release_all(skb);
680         kfree_skbmem(skb);
681 }
682 EXPORT_SYMBOL(__kfree_skb);
683 
684 /**
685  *      kfree_skb - free an sk_buff
686  *      @skb: buffer to free
687  *
688  *      Drop a reference to the buffer and free it if the usage count has
689  *      hit zero.
690  */
691 void kfree_skb(struct sk_buff *skb)
692 {
693         if (!skb_unref(skb))
694                 return;
695 
696         trace_kfree_skb(skb, __builtin_return_address(0));
697         __kfree_skb(skb);
698 }
699 EXPORT_SYMBOL(kfree_skb);
700 
701 void kfree_skb_list(struct sk_buff *segs)
702 {
703         while (segs) {
704                 struct sk_buff *next = segs->next;
705 
706                 kfree_skb(segs);
707                 segs = next;
708         }
709 }
710 EXPORT_SYMBOL(kfree_skb_list);
711 
712 /* Dump skb information and contents.
713  *
714  * Must only be called from net_ratelimit()-ed paths.
715  *
716  * Dumps up to can_dump_full whole packets if full_pkt, headers otherwise.
717  */
718 void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt)
719 {
720         static atomic_t can_dump_full = ATOMIC_INIT(5);
721         struct skb_shared_info *sh = skb_shinfo(skb);
722         struct net_device *dev = skb->dev;
723         struct sock *sk = skb->sk;
724         struct sk_buff *list_skb;
725         bool has_mac, has_trans;
726         int headroom, tailroom;
727         int i, len, seg_len;
728 
729         if (full_pkt)
730                 full_pkt = atomic_dec_if_positive(&can_dump_full) >= 0;
731 
732         if (full_pkt)
733                 len = skb->len;
734         else
735                 len = min_t(int, skb->len, MAX_HEADER + 128);
736 
737         headroom = skb_headroom(skb);
738         tailroom = skb_tailroom(skb);
739 
740         has_mac = skb_mac_header_was_set(skb);
741         has_trans = skb_transport_header_was_set(skb);
742 
743         printk("%sskb len=%u headroom=%u headlen=%u tailroom=%u\n"
744                "mac=(%d,%d) net=(%d,%d) trans=%d\n"
745                "shinfo(txflags=%u nr_frags=%u gso(size=%hu type=%u segs=%hu))\n"
746                "csum(0x%x ip_summed=%u complete_sw=%u valid=%u level=%u)\n"
747                "hash(0x%x sw=%u l4=%u) proto=0x%04x pkttype=%u iif=%d\n",
748                level, skb->len, headroom, skb_headlen(skb), tailroom,
749                has_mac ? skb->mac_header : -1,
750                has_mac ? skb_mac_header_len(skb) : -1,
751                skb->network_header,
752                has_trans ? skb_network_header_len(skb) : -1,
753                has_trans ? skb->transport_header : -1,
754                sh->tx_flags, sh->nr_frags,
755                sh->gso_size, sh->gso_type, sh->gso_segs,
756                skb->csum, skb->ip_summed, skb->csum_complete_sw,
757                skb->csum_valid, skb->csum_level,
758                skb->hash, skb->sw_hash, skb->l4_hash,
759                ntohs(skb->protocol), skb->pkt_type, skb->skb_iif);
760 
761         if (dev)
762                 printk("%sdev name=%s feat=0x%pNF\n",
763                        level, dev->name, &dev->features);
764         if (sk)
765                 printk("%ssk family=%hu type=%u proto=%u\n",
766                        level, sk->sk_family, sk->sk_type, sk->sk_protocol);
767 
768         if (full_pkt && headroom)
769                 print_hex_dump(level, "skb headroom: ", DUMP_PREFIX_OFFSET,
770                                16, 1, skb->head, headroom, false);
771 
772         seg_len = min_t(int, skb_headlen(skb), len);
773         if (seg_len)
774                 print_hex_dump(level, "skb linear:   ", DUMP_PREFIX_OFFSET,
775                                16, 1, skb->data, seg_len, false);
776         len -= seg_len;
777 
778         if (full_pkt && tailroom)
779                 print_hex_dump(level, "skb tailroom: ", DUMP_PREFIX_OFFSET,
780                                16, 1, skb_tail_pointer(skb), tailroom, false);
781 
782         for (i = 0; len && i < skb_shinfo(skb)->nr_frags; i++) {
783                 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
784                 u32 p_off, p_len, copied;
785                 struct page *p;
786                 u8 *vaddr;
787 
788                 skb_frag_foreach_page(frag, skb_frag_off(frag),
789                                       skb_frag_size(frag), p, p_off, p_len,
790                                       copied) {
791                         seg_len = min_t(int, p_len, len);
792                         vaddr = kmap_atomic(p);
793                         print_hex_dump(level, "skb frag:     ",
794                                        DUMP_PREFIX_OFFSET,
795                                        16, 1, vaddr + p_off, seg_len, false);
796                         kunmap_atomic(vaddr);
797                         len -= seg_len;
798                         if (!len)
799                                 break;
800                 }
801         }
802 
803         if (full_pkt && skb_has_frag_list(skb)) {
804                 printk("skb fraglist:\n");
805                 skb_walk_frags(skb, list_skb)
806                         skb_dump(level, list_skb, true);
807         }
808 }
809 EXPORT_SYMBOL(skb_dump);
810 
811 /**
812  *      skb_tx_error - report an sk_buff xmit error
813  *      @skb: buffer that triggered an error
814  *
815  *      Report xmit error if a device callback is tracking this skb.
816  *      skb must be freed afterwards.
817  */
818 void skb_tx_error(struct sk_buff *skb)
819 {
820         skb_zcopy_clear(skb, true);
821 }
822 EXPORT_SYMBOL(skb_tx_error);
823 
824 /**
825  *      consume_skb - free an skbuff
826  *      @skb: buffer to free
827  *
828  *      Drop a ref to the buffer and free it if the usage count has hit zero
829  *      Functions identically to kfree_skb, but kfree_skb assumes that the frame
830  *      is being dropped after a failure and notes that
831  */
832 void consume_skb(struct sk_buff *skb)
833 {
834         if (!skb_unref(skb))
835                 return;
836 
837         trace_consume_skb(skb);
838         __kfree_skb(skb);
839 }
840 EXPORT_SYMBOL(consume_skb);
841 
842 /**
843  *      consume_stateless_skb - free an skbuff, assuming it is stateless
844  *      @skb: buffer to free
845  *
846  *      Alike consume_skb(), but this variant assumes that this is the last
847  *      skb reference and all the head states have been already dropped
848  */
849 void __consume_stateless_skb(struct sk_buff *skb)
850 {
851         trace_consume_skb(skb);
852         skb_release_data(skb);
853         kfree_skbmem(skb);
854 }
855 
856 void __kfree_skb_flush(void)
857 {
858         struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
859 
860         /* flush skb_cache if containing objects */
861         if (nc->skb_count) {
862                 kmem_cache_free_bulk(skbuff_head_cache, nc->skb_count,
863                                      nc->skb_cache);
864                 nc->skb_count = 0;
865         }
866 }
867 
868 static inline void _kfree_skb_defer(struct sk_buff *skb)
869 {
870         struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
871 
872         /* drop skb->head and call any destructors for packet */
873         skb_release_all(skb);
874 
875         /* record skb to CPU local list */
876         nc->skb_cache[nc->skb_count++] = skb;
877 
878 #ifdef CONFIG_SLUB
879         /* SLUB writes into objects when freeing */
880         prefetchw(skb);
881 #endif
882 
883         /* flush skb_cache if it is filled */
884         if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
885                 kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_SIZE,
886                                      nc->skb_cache);
887                 nc->skb_count = 0;
888         }
889 }
890 void __kfree_skb_defer(struct sk_buff *skb)
891 {
892         _kfree_skb_defer(skb);
893 }
894 
895 void napi_consume_skb(struct sk_buff *skb, int budget)
896 {
897         if (unlikely(!skb))
898                 return;
899 
900         /* Zero budget indicate non-NAPI context called us, like netpoll */
901         if (unlikely(!budget)) {
902                 dev_consume_skb_any(skb);
903                 return;
904         }
905 
906         if (!skb_unref(skb))
907                 return;
908 
909         /* if reaching here SKB is ready to free */
910         trace_consume_skb(skb);
911 
912         /* if SKB is a clone, don't handle this case */
913         if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
914                 __kfree_skb(skb);
915                 return;
916         }
917 
918         _kfree_skb_defer(skb);
919 }
920 EXPORT_SYMBOL(napi_consume_skb);
921 
922 /* Make sure a field is enclosed inside headers_start/headers_end section */
923 #define CHECK_SKB_FIELD(field) \
924         BUILD_BUG_ON(offsetof(struct sk_buff, field) <          \
925                      offsetof(struct sk_buff, headers_start));  \
926         BUILD_BUG_ON(offsetof(struct sk_buff, field) >          \
927                      offsetof(struct sk_buff, headers_end));    \
928 
929 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
930 {
931         new->tstamp             = old->tstamp;
932         /* We do not copy old->sk */
933         new->dev                = old->dev;
934         memcpy(new->cb, old->cb, sizeof(old->cb));
935         skb_dst_copy(new, old);
936         __skb_ext_copy(new, old);
937         __nf_copy(new, old, false);
938 
939         /* Note : this field could be in headers_start/headers_end section
940          * It is not yet because we do not want to have a 16 bit hole
941          */
942         new->queue_mapping = old->queue_mapping;
943 
944         memcpy(&new->headers_start, &old->headers_start,
945                offsetof(struct sk_buff, headers_end) -
946                offsetof(struct sk_buff, headers_start));
947         CHECK_SKB_FIELD(protocol);
948         CHECK_SKB_FIELD(csum);
949         CHECK_SKB_FIELD(hash);
950         CHECK_SKB_FIELD(priority);
951         CHECK_SKB_FIELD(skb_iif);
952         CHECK_SKB_FIELD(vlan_proto);
953         CHECK_SKB_FIELD(vlan_tci);
954         CHECK_SKB_FIELD(transport_header);
955         CHECK_SKB_FIELD(network_header);
956         CHECK_SKB_FIELD(mac_header);
957         CHECK_SKB_FIELD(inner_protocol);
958         CHECK_SKB_FIELD(inner_transport_header);
959         CHECK_SKB_FIELD(inner_network_header);
960         CHECK_SKB_FIELD(inner_mac_header);
961         CHECK_SKB_FIELD(mark);
962 #ifdef CONFIG_NETWORK_SECMARK
963         CHECK_SKB_FIELD(secmark);
964 #endif
965 #ifdef CONFIG_NET_RX_BUSY_POLL
966         CHECK_SKB_FIELD(napi_id);
967 #endif
968 #ifdef CONFIG_XPS
969         CHECK_SKB_FIELD(sender_cpu);
970 #endif
971 #ifdef CONFIG_NET_SCHED
972         CHECK_SKB_FIELD(tc_index);
973 #endif
974 
975 }
976 
977 /*
978  * You should not add any new code to this function.  Add it to
979  * __copy_skb_header above instead.
980  */
981 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
982 {
983 #define C(x) n->x = skb->x
984 
985         n->next = n->prev = NULL;
986         n->sk = NULL;
987         __copy_skb_header(n, skb);
988 
989         C(len);
990         C(data_len);
991         C(mac_len);
992         n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
993         n->cloned = 1;
994         n->nohdr = 0;
995         n->peeked = 0;
996         C(pfmemalloc);
997         n->destructor = NULL;
998         C(tail);
999         C(end);
1000         C(head);
1001         C(head_frag);
1002         C(data);
1003         C(truesize);
1004         refcount_set(&n->users, 1);
1005 
1006         atomic_inc(&(skb_shinfo(skb)->dataref));
1007         skb->cloned = 1;
1008 
1009         return n;
1010 #undef C
1011 }
1012 
1013 /**
1014  * alloc_skb_for_msg() - allocate sk_buff to wrap frag list forming a msg
1015  * @first: first sk_buff of the msg
1016  */
1017 struct sk_buff *alloc_skb_for_msg(struct sk_buff *first)
1018 {
1019         struct sk_buff *n;
1020 
1021         n = alloc_skb(0, GFP_ATOMIC);
1022         if (!n)
1023                 return NULL;
1024 
1025         n->len = first->len;
1026         n->data_len = first->len;
1027         n->truesize = first->truesize;
1028 
1029         skb_shinfo(n)->frag_list = first;
1030 
1031         __copy_skb_header(n, first);
1032         n->destructor = NULL;
1033 
1034         return n;
1035 }
1036 EXPORT_SYMBOL_GPL(alloc_skb_for_msg);
1037 
1038 /**
1039  *      skb_morph       -       morph one skb into another
1040  *      @dst: the skb to receive the contents
1041  *      @src: the skb to supply the contents
1042  *
1043  *      This is identical to skb_clone except that the target skb is
1044  *      supplied by the user.
1045  *
1046  *      The target skb is returned upon exit.
1047  */
1048 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
1049 {
1050         skb_release_all(dst);
1051         return __skb_clone(dst, src);
1052 }
1053 EXPORT_SYMBOL_GPL(skb_morph);
1054 
1055 int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
1056 {
1057         unsigned long max_pg, num_pg, new_pg, old_pg;
1058         struct user_struct *user;
1059 
1060         if (capable(CAP_IPC_LOCK) || !size)
1061                 return 0;
1062 
1063         num_pg = (size >> PAGE_SHIFT) + 2;      /* worst case */
1064         max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
1065         user = mmp->user ? : current_user();
1066 
1067         do {
1068                 old_pg = atomic_long_read(&user->locked_vm);
1069                 new_pg = old_pg + num_pg;
1070                 if (new_pg > max_pg)
1071                         return -ENOBUFS;
1072         } while (atomic_long_cmpxchg(&user->locked_vm, old_pg, new_pg) !=
1073                  old_pg);
1074 
1075         if (!mmp->user) {
1076                 mmp->user = get_uid(user);
1077                 mmp->num_pg = num_pg;
1078         } else {
1079                 mmp->num_pg += num_pg;
1080         }
1081 
1082         return 0;
1083 }
1084 EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
1085 
1086 void mm_unaccount_pinned_pages(struct mmpin *mmp)
1087 {
1088         if (mmp->user) {
1089                 atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
1090                 free_uid(mmp->user);
1091         }
1092 }
1093 EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
1094 
1095 struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
1096 {
1097         struct ubuf_info *uarg;
1098         struct sk_buff *skb;
1099 
1100         WARN_ON_ONCE(!in_task());
1101 
1102         skb = sock_omalloc(sk, 0, GFP_KERNEL);
1103         if (!skb)
1104                 return NULL;
1105 
1106         BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
1107         uarg = (void *)skb->cb;
1108         uarg->mmp.user = NULL;
1109 
1110         if (mm_account_pinned_pages(&uarg->mmp, size)) {
1111                 kfree_skb(skb);
1112                 return NULL;
1113         }
1114 
1115         uarg->callback = sock_zerocopy_callback;
1116         uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
1117         uarg->len = 1;
1118         uarg->bytelen = size;
1119         uarg->zerocopy = 1;
1120         refcount_set(&uarg->refcnt, 1);
1121         sock_hold(sk);
1122 
1123         return uarg;
1124 }
1125 EXPORT_SYMBOL_GPL(sock_zerocopy_alloc);
1126 
1127 static inline struct sk_buff *skb_from_uarg(struct ubuf_info *uarg)
1128 {
1129         return container_of((void *)uarg, struct sk_buff, cb);
1130 }
1131 
1132 struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
1133                                         struct ubuf_info *uarg)
1134 {
1135         if (uarg) {
1136                 const u32 byte_limit = 1 << 19;         /* limit to a few TSO */
1137                 u32 bytelen, next;
1138 
1139                 /* realloc only when socket is locked (TCP, UDP cork),
1140                  * so uarg->len and sk_zckey access is serialized
1141                  */
1142                 if (!sock_owned_by_user(sk)) {
1143                         WARN_ON_ONCE(1);
1144                         return NULL;
1145                 }
1146 
1147                 bytelen = uarg->bytelen + size;
1148                 if (uarg->len == USHRT_MAX - 1 || bytelen > byte_limit) {
1149                         /* TCP can create new skb to attach new uarg */
1150                         if (sk->sk_type == SOCK_STREAM)
1151                                 goto new_alloc;
1152                         return NULL;
1153                 }
1154 
1155                 next = (u32)atomic_read(&sk->sk_zckey);
1156                 if ((u32)(uarg->id + uarg->len) == next) {
1157                         if (mm_account_pinned_pages(&uarg->mmp, size))
1158                                 return NULL;
1159                         uarg->len++;
1160                         uarg->bytelen = bytelen;
1161                         atomic_set(&sk->sk_zckey, ++next);
1162 
1163                         /* no extra ref when appending to datagram (MSG_MORE) */
1164                         if (sk->sk_type == SOCK_STREAM)
1165                                 sock_zerocopy_get(uarg);
1166 
1167                         return uarg;
1168                 }
1169         }
1170 
1171 new_alloc:
1172         return sock_zerocopy_alloc(sk, size);
1173 }
1174 EXPORT_SYMBOL_GPL(sock_zerocopy_realloc);
1175 
1176 static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
1177 {
1178         struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
1179         u32 old_lo, old_hi;
1180         u64 sum_len;
1181 
1182         old_lo = serr->ee.ee_info;
1183         old_hi = serr->ee.ee_data;
1184         sum_len = old_hi - old_lo + 1ULL + len;
1185 
1186         if (sum_len >= (1ULL << 32))
1187                 return false;
1188 
1189         if (lo != old_hi + 1)
1190                 return false;
1191 
1192         serr->ee.ee_data += len;
1193         return true;
1194 }
1195 
1196 void sock_zerocopy_callback(struct ubuf_info *uarg, bool success)
1197 {
1198         struct sk_buff *tail, *skb = skb_from_uarg(uarg);
1199         struct sock_exterr_skb *serr;
1200         struct sock *sk = skb->sk;
1201         struct sk_buff_head *q;
1202         unsigned long flags;
1203         u32 lo, hi;
1204         u16 len;
1205 
1206         mm_unaccount_pinned_pages(&uarg->mmp);
1207 
1208         /* if !len, there was only 1 call, and it was aborted
1209          * so do not queue a completion notification
1210          */
1211         if (!uarg->len || sock_flag(sk, SOCK_DEAD))
1212                 goto release;
1213 
1214         len = uarg->len;
1215         lo = uarg->id;
1216         hi = uarg->id + len - 1;
1217 
1218         serr = SKB_EXT_ERR(skb);
1219         memset(serr, 0, sizeof(*serr));
1220         serr->ee.ee_errno = 0;
1221         serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
1222         serr->ee.ee_data = hi;
1223         serr->ee.ee_info = lo;
1224         if (!success)
1225                 serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
1226 
1227         q = &sk->sk_error_queue;
1228         spin_lock_irqsave(&q->lock, flags);
1229         tail = skb_peek_tail(q);
1230         if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
1231             !skb_zerocopy_notify_extend(tail, lo, len)) {
1232                 __skb_queue_tail(q, skb);
1233                 skb = NULL;
1234         }
1235         spin_unlock_irqrestore(&q->lock, flags);
1236 
1237         sk->sk_error_report(sk);
1238 
1239 release:
1240         consume_skb(skb);
1241         sock_put(sk);
1242 }
1243 EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
1244 
1245 void sock_zerocopy_put(struct ubuf_info *uarg)
1246 {
1247         if (uarg && refcount_dec_and_test(&uarg->refcnt)) {
1248                 if (uarg->callback)
1249                         uarg->callback(uarg, uarg->zerocopy);
1250                 else
1251                         consume_skb(skb_from_uarg(uarg));
1252         }
1253 }
1254 EXPORT_SYMBOL_GPL(sock_zerocopy_put);
1255 
1256 void sock_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
1257 {
1258         if (uarg) {
1259                 struct sock *sk = skb_from_uarg(uarg)->sk;
1260 
1261                 atomic_dec(&sk->sk_zckey);
1262                 uarg->len--;
1263 
1264                 if (have_uref)
1265                         sock_zerocopy_put(uarg);
1266         }
1267 }
1268 EXPORT_SYMBOL_GPL(sock_zerocopy_put_abort);
1269 
1270 int skb_zerocopy_iter_dgram(struct sk_buff *skb, struct msghdr *msg, int len)
1271 {
1272         return __zerocopy_sg_from_iter(skb->sk, skb, &msg->msg_iter, len);
1273 }
1274 EXPORT_SYMBOL_GPL(skb_zerocopy_iter_dgram);
1275 
1276 int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
1277                              struct msghdr *msg, int len,
1278                              struct ubuf_info *uarg)
1279 {
1280         struct ubuf_info *orig_uarg = skb_zcopy(skb);
1281         struct iov_iter orig_iter = msg->msg_iter;
1282         int err, orig_len = skb->len;
1283 
1284         /* An skb can only point to one uarg. This edge case happens when
1285          * TCP appends to an skb, but zerocopy_realloc triggered a new alloc.
1286          */
1287         if (orig_uarg && uarg != orig_uarg)
1288                 return -EEXIST;
1289 
1290         err = __zerocopy_sg_from_iter(sk, skb, &msg->msg_iter, len);
1291         if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
1292                 struct sock *save_sk = skb->sk;
1293 
1294                 /* Streams do not free skb on error. Reset to prev state. */
1295                 msg->msg_iter = orig_iter;
1296                 skb->sk = sk;
1297                 ___pskb_trim(skb, orig_len);
1298                 skb->sk = save_sk;
1299                 return err;
1300         }
1301 
1302         skb_zcopy_set(skb, uarg, NULL);
1303         return skb->len - orig_len;
1304 }
1305 EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
1306 
1307 static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
1308                               gfp_t gfp_mask)
1309 {
1310         if (skb_zcopy(orig)) {
1311                 if (skb_zcopy(nskb)) {
1312                         /* !gfp_mask callers are verified to !skb_zcopy(nskb) */
1313                         if (!gfp_mask) {
1314                                 WARN_ON_ONCE(1);
1315                                 return -ENOMEM;
1316                         }
1317                         if (skb_uarg(nskb) == skb_uarg(orig))
1318                                 return 0;
1319                         if (skb_copy_ubufs(nskb, GFP_ATOMIC))
1320                                 return -EIO;
1321                 }
1322                 skb_zcopy_set(nskb, skb_uarg(orig), NULL);
1323         }
1324         return 0;
1325 }
1326 
1327 /**
1328  *      skb_copy_ubufs  -       copy userspace skb frags buffers to kernel
1329  *      @skb: the skb to modify
1330  *      @gfp_mask: allocation priority
1331  *
1332  *      This must be called on SKBTX_DEV_ZEROCOPY skb.
1333  *      It will copy all frags into kernel and drop the reference
1334  *      to userspace pages.
1335  *
1336  *      If this function is called from an interrupt gfp_mask() must be
1337  *      %GFP_ATOMIC.
1338  *
1339  *      Returns 0 on success or a negative error code on failure
1340  *      to allocate kernel memory to copy to.
1341  */
1342 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
1343 {
1344         int num_frags = skb_shinfo(skb)->nr_frags;
1345         struct page *page, *head = NULL;
1346         int i, new_frags;
1347         u32 d_off;
1348 
1349         if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
1350                 return -EINVAL;
1351 
1352         if (!num_frags)
1353                 goto release;
1354 
1355         new_frags = (__skb_pagelen(skb) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1356         for (i = 0; i < new_frags; i++) {
1357                 page = alloc_page(gfp_mask);
1358                 if (!page) {
1359                         while (head) {
1360                                 struct page *next = (struct page *)page_private(head);
1361                                 put_page(head);
1362                                 head = next;
1363                         }
1364                         return -ENOMEM;
1365                 }
1366                 set_page_private(page, (unsigned long)head);
1367                 head = page;
1368         }
1369 
1370         page = head;
1371         d_off = 0;
1372         for (i = 0; i < num_frags; i++) {
1373                 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1374                 u32 p_off, p_len, copied;
1375                 struct page *p;
1376                 u8 *vaddr;
1377 
1378                 skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
1379                                       p, p_off, p_len, copied) {
1380                         u32 copy, done = 0;
1381                         vaddr = kmap_atomic(p);
1382 
1383                         while (done < p_len) {
1384                                 if (d_off == PAGE_SIZE) {
1385                                         d_off = 0;
1386                                         page = (struct page *)page_private(page);
1387                                 }
1388                                 copy = min_t(u32, PAGE_SIZE - d_off, p_len - done);
1389                                 memcpy(page_address(page) + d_off,
1390                                        vaddr + p_off + done, copy);
1391                                 done += copy;
1392                                 d_off += copy;
1393                         }
1394                         kunmap_atomic(vaddr);
1395                 }
1396         }
1397 
1398         /* skb frags release userspace buffers */
1399         for (i = 0; i < num_frags; i++)
1400                 skb_frag_unref(skb, i);
1401 
1402         /* skb frags point to kernel buffers */
1403         for (i = 0; i < new_frags - 1; i++) {
1404                 __skb_fill_page_desc(skb, i, head, 0, PAGE_SIZE);
1405                 head = (struct page *)page_private(head);
1406         }
1407         __skb_fill_page_desc(skb, new_frags - 1, head, 0, d_off);
1408         skb_shinfo(skb)->nr_frags = new_frags;
1409 
1410 release:
1411         skb_zcopy_clear(skb, false);
1412         return 0;
1413 }
1414 EXPORT_SYMBOL_GPL(skb_copy_ubufs);
1415 
1416 /**
1417  *      skb_clone       -       duplicate an sk_buff
1418  *      @skb: buffer to clone
1419  *      @gfp_mask: allocation priority
1420  *
1421  *      Duplicate an &sk_buff. The new one is not owned by a socket. Both
1422  *      copies share the same packet data but not structure. The new
1423  *      buffer has a reference count of 1. If the allocation fails the
1424  *      function returns %NULL otherwise the new buffer is returned.
1425  *
1426  *      If this function is called from an interrupt gfp_mask() must be
1427  *      %GFP_ATOMIC.
1428  */
1429 
1430 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
1431 {
1432         struct sk_buff_fclones *fclones = container_of(skb,
1433                                                        struct sk_buff_fclones,
1434                                                        skb1);
1435         struct sk_buff *n;
1436 
1437         if (skb_orphan_frags(skb, gfp_mask))
1438                 return NULL;
1439 
1440         if (skb->fclone == SKB_FCLONE_ORIG &&
1441             refcount_read(&fclones->fclone_ref) == 1) {
1442                 n = &fclones->skb2;
1443                 refcount_set(&fclones->fclone_ref, 2);
1444         } else {
1445                 if (skb_pfmemalloc(skb))
1446                         gfp_mask |= __GFP_MEMALLOC;
1447 
1448                 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
1449                 if (!n)
1450                         return NULL;
1451 
1452                 n->fclone = SKB_FCLONE_UNAVAILABLE;
1453         }
1454 
1455         return __skb_clone(n, skb);
1456 }
1457 EXPORT_SYMBOL(skb_clone);
1458 
1459 void skb_headers_offset_update(struct sk_buff *skb, int off)
1460 {
1461         /* Only adjust this if it actually is csum_start rather than csum */
1462         if (skb->ip_summed == CHECKSUM_PARTIAL)
1463                 skb->csum_start += off;
1464         /* {transport,network,mac}_header and tail are relative to skb->head */
1465         skb->transport_header += off;
1466         skb->network_header   += off;
1467         if (skb_mac_header_was_set(skb))
1468                 skb->mac_header += off;
1469         skb->inner_transport_header += off;
1470         skb->inner_network_header += off;
1471         skb->inner_mac_header += off;
1472 }
1473 EXPORT_SYMBOL(skb_headers_offset_update);
1474 
1475 void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
1476 {
1477         __copy_skb_header(new, old);
1478 
1479         skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
1480         skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
1481         skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
1482 }
1483 EXPORT_SYMBOL(skb_copy_header);
1484 
1485 static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
1486 {
1487         if (skb_pfmemalloc(skb))
1488                 return SKB_ALLOC_RX;
1489         return 0;
1490 }
1491 
1492 /**
1493  *      skb_copy        -       create private copy of an sk_buff
1494  *      @skb: buffer to copy
1495  *      @gfp_mask: allocation priority
1496  *
1497  *      Make a copy of both an &sk_buff and its data. This is used when the
1498  *      caller wishes to modify the data and needs a private copy of the
1499  *      data to alter. Returns %NULL on failure or the pointer to the buffer
1500  *      on success. The returned buffer has a reference count of 1.
1501  *
1502  *      As by-product this function converts non-linear &sk_buff to linear
1503  *      one, so that &sk_buff becomes completely private and caller is allowed
1504  *      to modify all the data of returned buffer. This means that this
1505  *      function is not recommended for use in circumstances when only
1506  *      header is going to be modified. Use pskb_copy() instead.
1507  */
1508 
1509 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
1510 {
1511         int headerlen = skb_headroom(skb);
1512         unsigned int size = skb_end_offset(skb) + skb->data_len;
1513         struct sk_buff *n = __alloc_skb(size, gfp_mask,
1514                                         skb_alloc_rx_flag(skb), NUMA_NO_NODE);
1515 
1516         if (!n)
1517                 return NULL;
1518 
1519         /* Set the data pointer */
1520         skb_reserve(n, headerlen);
1521         /* Set the tail pointer and length */
1522         skb_put(n, skb->len);
1523 
1524         BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
1525 
1526         skb_copy_header(n, skb);
1527         return n;
1528 }
1529 EXPORT_SYMBOL(skb_copy);
1530 
1531 /**
1532  *      __pskb_copy_fclone      -  create copy of an sk_buff with private head.
1533  *      @skb: buffer to copy
1534  *      @headroom: headroom of new skb
1535  *      @gfp_mask: allocation priority
1536  *      @fclone: if true allocate the copy of the skb from the fclone
1537  *      cache instead of the head cache; it is recommended to set this
1538  *      to true for the cases where the copy will likely be cloned
1539  *
1540  *      Make a copy of both an &sk_buff and part of its data, located
1541  *      in header. Fragmented data remain shared. This is used when
1542  *      the caller wishes to modify only header of &sk_buff and needs
1543  *      private copy of the header to alter. Returns %NULL on failure
1544  *      or the pointer to the buffer on success.
1545  *      The returned buffer has a reference count of 1.
1546  */
1547 
1548 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
1549                                    gfp_t gfp_mask, bool fclone)
1550 {
1551         unsigned int size = skb_headlen(skb) + headroom;
1552         int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
1553         struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
1554 
1555         if (!n)
1556                 goto out;
1557 
1558         /* Set the data pointer */
1559         skb_reserve(n, headroom);
1560         /* Set the tail pointer and length */
1561         skb_put(n, skb_headlen(skb));
1562         /* Copy the bytes */
1563         skb_copy_from_linear_data(skb, n->data, n->len);
1564 
1565         n->truesize += skb->data_len;
1566         n->data_len  = skb->data_len;
1567         n->len       = skb->len;
1568 
1569         if (skb_shinfo(skb)->nr_frags) {
1570                 int i;
1571 
1572                 if (skb_orphan_frags(skb, gfp_mask) ||
1573                     skb_zerocopy_clone(n, skb, gfp_mask)) {
1574                         kfree_skb(n);
1575                         n = NULL;
1576                         goto out;
1577                 }
1578                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1579                         skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
1580                         skb_frag_ref(skb, i);
1581                 }
1582                 skb_shinfo(n)->nr_frags = i;
1583         }
1584 
1585         if (skb_has_frag_list(skb)) {
1586                 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
1587                 skb_clone_fraglist(n);
1588         }
1589 
1590         skb_copy_header(n, skb);
1591 out:
1592         return n;
1593 }
1594 EXPORT_SYMBOL(__pskb_copy_fclone);
1595 
1596 /**
1597  *      pskb_expand_head - reallocate header of &sk_buff
1598  *      @skb: buffer to reallocate
1599  *      @nhead: room to add at head
1600  *      @ntail: room to add at tail
1601  *      @gfp_mask: allocation priority
1602  *
1603  *      Expands (or creates identical copy, if @nhead and @ntail are zero)
1604  *      header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
1605  *      reference count of 1. Returns zero in the case of success or error,
1606  *      if expansion failed. In the last case, &sk_buff is not changed.
1607  *
1608  *      All the pointers pointing into skb header may change and must be
1609  *      reloaded after call to this function.
1610  */
1611 
1612 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
1613                      gfp_t gfp_mask)
1614 {
1615         int i, osize = skb_end_offset(skb);
1616         int size = osize + nhead + ntail;
1617         long off;
1618         u8 *data;
1619 
1620         BUG_ON(nhead < 0);
1621 
1622         BUG_ON(skb_shared(skb));
1623 
1624         size = SKB_DATA_ALIGN(size);
1625 
1626         if (skb_pfmemalloc(skb))
1627                 gfp_mask |= __GFP_MEMALLOC;
1628         data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
1629                                gfp_mask, NUMA_NO_NODE, NULL);
1630         if (!data)
1631                 goto nodata;
1632         size = SKB_WITH_OVERHEAD(ksize(data));
1633 
1634         /* Copy only real data... and, alas, header. This should be
1635          * optimized for the cases when header is void.
1636          */
1637         memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
1638 
1639         memcpy((struct skb_shared_info *)(data + size),
1640                skb_shinfo(skb),
1641                offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
1642 
1643         /*
1644          * if shinfo is shared we must drop the old head gracefully, but if it
1645          * is not we can just drop the old head and let the existing refcount
1646          * be since all we did is relocate the values
1647          */
1648         if (skb_cloned(skb)) {
1649                 if (skb_orphan_frags(skb, gfp_mask))
1650                         goto nofrags;
1651                 if (skb_zcopy(skb))
1652                         refcount_inc(&skb_uarg(skb)->refcnt);
1653                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1654                         skb_frag_ref(skb, i);
1655 
1656                 if (skb_has_frag_list(skb))
1657                         skb_clone_fraglist(skb);
1658 
1659                 skb_release_data(skb);
1660         } else {
1661                 skb_free_head(skb);
1662         }
1663         off = (data + nhead) - skb->head;
1664 
1665         skb->head     = data;
1666         skb->head_frag = 0;
1667         skb->data    += off;
1668 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1669         skb->end      = size;
1670         off           = nhead;
1671 #else
1672         skb->end      = skb->head + size;
1673 #endif
1674         skb->tail             += off;
1675         skb_headers_offset_update(skb, nhead);
1676         skb->cloned   = 0;
1677         skb->hdr_len  = 0;
1678         skb->nohdr    = 0;
1679         atomic_set(&skb_shinfo(skb)->dataref, 1);
1680 
1681         skb_metadata_clear(skb);
1682 
1683         /* It is not generally safe to change skb->truesize.
1684          * For the moment, we really care of rx path, or
1685          * when skb is orphaned (not attached to a socket).
1686          */
1687         if (!skb->sk || skb->destructor == sock_edemux)
1688                 skb->truesize += size - osize;
1689 
1690         return 0;
1691 
1692 nofrags:
1693         kfree(data);
1694 nodata:
1695         return -ENOMEM;
1696 }
1697 EXPORT_SYMBOL(pskb_expand_head);
1698 
1699 /* Make private copy of skb with writable head and some headroom */
1700 
1701 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1702 {
1703         struct sk_buff *skb2;
1704         int delta = headroom - skb_headroom(skb);
1705 
1706         if (delta <= 0)
1707                 skb2 = pskb_copy(skb, GFP_ATOMIC);
1708         else {
1709                 skb2 = skb_clone(skb, GFP_ATOMIC);
1710                 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1711                                              GFP_ATOMIC)) {
1712                         kfree_skb(skb2);
1713                         skb2 = NULL;
1714                 }
1715         }
1716         return skb2;
1717 }
1718 EXPORT_SYMBOL(skb_realloc_headroom);
1719 
1720 /**
1721  *      skb_copy_expand -       copy and expand sk_buff
1722  *      @skb: buffer to copy
1723  *      @newheadroom: new free bytes at head
1724  *      @newtailroom: new free bytes at tail
1725  *      @gfp_mask: allocation priority
1726  *
1727  *      Make a copy of both an &sk_buff and its data and while doing so
1728  *      allocate additional space.
1729  *
1730  *      This is used when the caller wishes to modify the data and needs a
1731  *      private copy of the data to alter as well as more space for new fields.
1732  *      Returns %NULL on failure or the pointer to the buffer
1733  *      on success. The returned buffer has a reference count of 1.
1734  *
1735  *      You must pass %GFP_ATOMIC as the allocation priority if this function
1736  *      is called from an interrupt.
1737  */
1738 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
1739                                 int newheadroom, int newtailroom,
1740                                 gfp_t gfp_mask)
1741 {
1742         /*
1743          *      Allocate the copy buffer
1744          */
1745         struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
1746                                         gfp_mask, skb_alloc_rx_flag(skb),
1747                                         NUMA_NO_NODE);
1748         int oldheadroom = skb_headroom(skb);
1749         int head_copy_len, head_copy_off;
1750 
1751         if (!n)
1752                 return NULL;
1753 
1754         skb_reserve(n, newheadroom);
1755 
1756         /* Set the tail pointer and length */
1757         skb_put(n, skb->len);
1758 
1759         head_copy_len = oldheadroom;
1760         head_copy_off = 0;
1761         if (newheadroom <= head_copy_len)
1762                 head_copy_len = newheadroom;
1763         else
1764                 head_copy_off = newheadroom - head_copy_len;
1765 
1766         /* Copy the linear header and data. */
1767         BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1768                              skb->len + head_copy_len));
1769 
1770         skb_copy_header(n, skb);
1771 
1772         skb_headers_offset_update(n, newheadroom - oldheadroom);
1773 
1774         return n;
1775 }
1776 EXPORT_SYMBOL(skb_copy_expand);
1777 
1778 /**
1779  *      __skb_pad               -       zero pad the tail of an skb
1780  *      @skb: buffer to pad
1781  *      @pad: space to pad
1782  *      @free_on_error: free buffer on error
1783  *
1784  *      Ensure that a buffer is followed by a padding area that is zero
1785  *      filled. Used by network drivers which may DMA or transfer data
1786  *      beyond the buffer end onto the wire.
1787  *
1788  *      May return error in out of memory cases. The skb is freed on error
1789  *      if @free_on_error is true.
1790  */
1791 
1792 int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
1793 {
1794         int err;
1795         int ntail;
1796 
1797         /* If the skbuff is non linear tailroom is always zero.. */
1798         if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1799                 memset(skb->data+skb->len, 0, pad);
1800                 return 0;
1801         }
1802 
1803         ntail = skb->data_len + pad - (skb->end - skb->tail);
1804         if (likely(skb_cloned(skb) || ntail > 0)) {
1805                 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1806                 if (unlikely(err))
1807                         goto free_skb;
1808         }
1809 
1810         /* FIXME: The use of this function with non-linear skb's really needs
1811          * to be audited.
1812          */
1813         err = skb_linearize(skb);
1814         if (unlikely(err))
1815                 goto free_skb;
1816 
1817         memset(skb->data + skb->len, 0, pad);
1818         return 0;
1819 
1820 free_skb:
1821         if (free_on_error)
1822                 kfree_skb(skb);
1823         return err;
1824 }
1825 EXPORT_SYMBOL(__skb_pad);
1826 
1827 /**
1828  *      pskb_put - add data to the tail of a potentially fragmented buffer
1829  *      @skb: start of the buffer to use
1830  *      @tail: tail fragment of the buffer to use
1831  *      @len: amount of data to add
1832  *
1833  *      This function extends the used data area of the potentially
1834  *      fragmented buffer. @tail must be the last fragment of @skb -- or
1835  *      @skb itself. If this would exceed the total buffer size the kernel
1836  *      will panic. A pointer to the first byte of the extra data is
1837  *      returned.
1838  */
1839 
1840 void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
1841 {
1842         if (tail != skb) {
1843                 skb->data_len += len;
1844                 skb->len += len;
1845         }
1846         return skb_put(tail, len);
1847 }
1848 EXPORT_SYMBOL_GPL(pskb_put);
1849 
1850 /**
1851  *      skb_put - add data to a buffer
1852  *      @skb: buffer to use
1853  *      @len: amount of data to add
1854  *
1855  *      This function extends the used data area of the buffer. If this would
1856  *      exceed the total buffer size the kernel will panic. A pointer to the
1857  *      first byte of the extra data is returned.
1858  */
1859 void *skb_put(struct sk_buff *skb, unsigned int len)
1860 {
1861         void *tmp = skb_tail_pointer(skb);
1862         SKB_LINEAR_ASSERT(skb);
1863         skb->tail += len;
1864         skb->len  += len;
1865         if (unlikely(skb->tail > skb->end))
1866                 skb_over_panic(skb, len, __builtin_return_address(0));
1867         return tmp;
1868 }
1869 EXPORT_SYMBOL(skb_put);
1870 
1871 /**
1872  *      skb_push - add data to the start of a buffer
1873  *      @skb: buffer to use
1874  *      @len: amount of data to add
1875  *
1876  *      This function extends the used data area of the buffer at the buffer
1877  *      start. If this would exceed the total buffer headroom the kernel will
1878  *      panic. A pointer to the first byte of the extra data is returned.
1879  */
1880 void *skb_push(struct sk_buff *skb, unsigned int len)
1881 {
1882         skb->data -= len;
1883         skb->len  += len;
1884         if (unlikely(skb->data < skb->head))
1885                 skb_under_panic(skb, len, __builtin_return_address(0));
1886         return skb->data;
1887 }
1888 EXPORT_SYMBOL(skb_push);
1889 
1890 /**
1891  *      skb_pull - remove data from the start of a buffer
1892  *      @skb: buffer to use
1893  *      @len: amount of data to remove
1894  *
1895  *      This function removes data from the start of a buffer, returning
1896  *      the memory to the headroom. A pointer to the next data in the buffer
1897  *      is returned. Once the data has been pulled future pushes will overwrite
1898  *      the old data.
1899  */
1900 void *skb_pull(struct sk_buff *skb, unsigned int len)
1901 {
1902         return skb_pull_inline(skb, len);
1903 }
1904 EXPORT_SYMBOL(skb_pull);
1905 
1906 /**
1907  *      skb_trim - remove end from a buffer
1908  *      @skb: buffer to alter
1909  *      @len: new length
1910  *
1911  *      Cut the length of a buffer down by removing data from the tail. If
1912  *      the buffer is already under the length specified it is not modified.
1913  *      The skb must be linear.
1914  */
1915 void skb_trim(struct sk_buff *skb, unsigned int len)
1916 {
1917         if (skb->len > len)
1918                 __skb_trim(skb, len);
1919 }
1920 EXPORT_SYMBOL(skb_trim);
1921 
1922 /* Trims skb to length len. It can change skb pointers.
1923  */
1924 
1925 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1926 {
1927         struct sk_buff **fragp;
1928         struct sk_buff *frag;
1929         int offset = skb_headlen(skb);
1930         int nfrags = skb_shinfo(skb)->nr_frags;
1931         int i;
1932         int err;
1933 
1934         if (skb_cloned(skb) &&
1935             unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1936                 return err;
1937 
1938         i = 0;
1939         if (offset >= len)
1940                 goto drop_pages;
1941 
1942         for (; i < nfrags; i++) {
1943                 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
1944 
1945                 if (end < len) {
1946                         offset = end;
1947                         continue;
1948                 }
1949 
1950                 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
1951 
1952 drop_pages:
1953                 skb_shinfo(skb)->nr_frags = i;
1954 
1955                 for (; i < nfrags; i++)
1956                         skb_frag_unref(skb, i);
1957 
1958                 if (skb_has_frag_list(skb))
1959                         skb_drop_fraglist(skb);
1960                 goto done;
1961         }
1962 
1963         for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1964              fragp = &frag->next) {
1965                 int end = offset + frag->len;
1966 
1967                 if (skb_shared(frag)) {
1968                         struct sk_buff *nfrag;
1969 
1970                         nfrag = skb_clone(frag, GFP_ATOMIC);
1971                         if (unlikely(!nfrag))
1972                                 return -ENOMEM;
1973 
1974                         nfrag->next = frag->next;
1975                         consume_skb(frag);
1976                         frag = nfrag;
1977                         *fragp = frag;
1978                 }
1979 
1980                 if (end < len) {
1981                         offset = end;
1982                         continue;
1983                 }
1984 
1985                 if (end > len &&
1986                     unlikely((err = pskb_trim(frag, len - offset))))
1987                         return err;
1988 
1989                 if (frag->next)
1990                         skb_drop_list(&frag->next);
1991                 break;
1992         }
1993 
1994 done:
1995         if (len > skb_headlen(skb)) {
1996                 skb->data_len -= skb->len - len;
1997                 skb->len       = len;
1998         } else {
1999                 skb->len       = len;
2000                 skb->data_len  = 0;
2001                 skb_set_tail_pointer(skb, len);
2002         }
2003 
2004         if (!skb->sk || skb->destructor == sock_edemux)
2005                 skb_condense(skb);
2006         return 0;
2007 }
2008 EXPORT_SYMBOL(___pskb_trim);
2009 
2010 /* Note : use pskb_trim_rcsum() instead of calling this directly
2011  */
2012 int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
2013 {
2014         if (skb->ip_summed == CHECKSUM_COMPLETE) {
2015                 int delta = skb->len - len;
2016 
2017                 skb->csum = csum_block_sub(skb->csum,
2018                                            skb_checksum(skb, len, delta, 0),
2019                                            len);
2020         }
2021         return __pskb_trim(skb, len);
2022 }
2023 EXPORT_SYMBOL(pskb_trim_rcsum_slow);
2024 
2025 /**
2026  *      __pskb_pull_tail - advance tail of skb header
2027  *      @skb: buffer to reallocate
2028  *      @delta: number of bytes to advance tail
2029  *
2030  *      The function makes a sense only on a fragmented &sk_buff,
2031  *      it expands header moving its tail forward and copying necessary
2032  *      data from fragmented part.
2033  *
2034  *      &sk_buff MUST have reference count of 1.
2035  *
2036  *      Returns %NULL (and &sk_buff does not change) if pull failed
2037  *      or value of new tail of skb in the case of success.
2038  *
2039  *      All the pointers pointing into skb header may change and must be
2040  *      reloaded after call to this function.
2041  */
2042 
2043 /* Moves tail of skb head forward, copying data from fragmented part,
2044  * when it is necessary.
2045  * 1. It may fail due to malloc failure.
2046  * 2. It may change skb pointers.
2047  *
2048  * It is pretty complicated. Luckily, it is called only in exceptional cases.
2049  */
2050 void *__pskb_pull_tail(struct sk_buff *skb, int delta)
2051 {
2052         /* If skb has not enough free space at tail, get new one
2053          * plus 128 bytes for future expansions. If we have enough
2054          * room at tail, reallocate without expansion only if skb is cloned.
2055          */
2056         int i, k, eat = (skb->tail + delta) - skb->end;
2057 
2058         if (eat > 0 || skb_cloned(skb)) {
2059                 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
2060                                      GFP_ATOMIC))
2061                         return NULL;
2062         }
2063 
2064         BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
2065                              skb_tail_pointer(skb), delta));
2066 
2067         /* Optimization: no fragments, no reasons to preestimate
2068          * size of pulled pages. Superb.
2069          */
2070         if (!skb_has_frag_list(skb))
2071                 goto pull_pages;
2072 
2073         /* Estimate size of pulled pages. */
2074         eat = delta;
2075         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2076                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2077 
2078                 if (size >= eat)
2079                         goto pull_pages;
2080                 eat -= size;
2081         }
2082 
2083         /* If we need update frag list, we are in troubles.
2084          * Certainly, it is possible to add an offset to skb data,
2085          * but taking into account that pulling is expected to
2086          * be very rare operation, it is worth to fight against
2087          * further bloating skb head and crucify ourselves here instead.
2088          * Pure masohism, indeed. 8)8)
2089          */
2090         if (eat) {
2091                 struct sk_buff *list = skb_shinfo(skb)->frag_list;
2092                 struct sk_buff *clone = NULL;
2093                 struct sk_buff *insp = NULL;
2094 
2095                 do {
2096                         if (list->len <= eat) {
2097                                 /* Eaten as whole. */
2098                                 eat -= list->len;
2099                                 list = list->next;
2100                                 insp = list;
2101                         } else {
2102                                 /* Eaten partially. */
2103 
2104                                 if (skb_shared(list)) {
2105                                         /* Sucks! We need to fork list. :-( */
2106                                         clone = skb_clone(list, GFP_ATOMIC);
2107                                         if (!clone)
2108                                                 return NULL;
2109                                         insp = list->next;
2110                                         list = clone;
2111                                 } else {
2112                                         /* This may be pulled without
2113                                          * problems. */
2114                                         insp = list;
2115                                 }
2116                                 if (!pskb_pull(list, eat)) {
2117                                         kfree_skb(clone);
2118                                         return NULL;
2119                                 }
2120                                 break;
2121                         }
2122                 } while (eat);
2123 
2124                 /* Free pulled out fragments. */
2125                 while ((list = skb_shinfo(skb)->frag_list) != insp) {
2126                         skb_shinfo(skb)->frag_list = list->next;
2127                         kfree_skb(list);
2128                 }
2129                 /* And insert new clone at head. */
2130                 if (clone) {
2131                         clone->next = list;
2132                         skb_shinfo(skb)->frag_list = clone;
2133                 }
2134         }
2135         /* Success! Now we may commit changes to skb data. */
2136 
2137 pull_pages:
2138         eat = delta;
2139         k = 0;
2140         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2141                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2142 
2143                 if (size <= eat) {
2144                         skb_frag_unref(skb, i);
2145                         eat -= size;
2146                 } else {
2147                         skb_frag_t *frag = &skb_shinfo(skb)->frags[k];
2148 
2149                         *frag = skb_shinfo(skb)->frags[i];
2150                         if (eat) {
2151                                 skb_frag_off_add(frag, eat);
2152                                 skb_frag_size_sub(frag, eat);
2153                                 if (!i)
2154                                         goto end;
2155                                 eat = 0;
2156                         }
2157                         k++;
2158                 }
2159         }
2160         skb_shinfo(skb)->nr_frags = k;
2161 
2162 end:
2163         skb->tail     += delta;
2164         skb->data_len -= delta;
2165 
2166         if (!skb->data_len)
2167                 skb_zcopy_clear(skb, false);
2168 
2169         return skb_tail_pointer(skb);
2170 }
2171 EXPORT_SYMBOL(__pskb_pull_tail);
2172 
2173 /**
2174  *      skb_copy_bits - copy bits from skb to kernel buffer
2175  *      @skb: source skb
2176  *      @offset: offset in source
2177  *      @to: destination buffer
2178  *      @len: number of bytes to copy
2179  *
2180  *      Copy the specified number of bytes from the source skb to the
2181  *      destination buffer.
2182  *
2183  *      CAUTION ! :
2184  *              If its prototype is ever changed,
2185  *              check arch/{*}/net/{*}.S files,
2186  *              since it is called from BPF assembly code.
2187  */
2188 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
2189 {
2190         int start = skb_headlen(skb);
2191         struct sk_buff *frag_iter;
2192         int i, copy;
2193 
2194         if (offset > (int)skb->len - len)
2195                 goto fault;
2196 
2197         /* Copy header. */
2198         if ((copy = start - offset) > 0) {
2199                 if (copy > len)
2200                         copy = len;
2201                 skb_copy_from_linear_data_offset(skb, offset, to, copy);
2202                 if ((len -= copy) == 0)
2203                         return 0;
2204                 offset += copy;
2205                 to     += copy;
2206         }
2207 
2208         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2209                 int end;
2210                 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
2211 
2212                 WARN_ON(start > offset + len);
2213 
2214                 end = start + skb_frag_size(f);
2215                 if ((copy = end - offset) > 0) {
2216                         u32 p_off, p_len, copied;
2217                         struct page *p;
2218                         u8 *vaddr;
2219 
2220                         if (copy > len)
2221                                 copy = len;
2222 
2223                         skb_frag_foreach_page(f,
2224                                               skb_frag_off(f) + offset - start,
2225                                               copy, p, p_off, p_len, copied) {
2226                                 vaddr = kmap_atomic(p);
2227                                 memcpy(to + copied, vaddr + p_off, p_len);
2228                                 kunmap_atomic(vaddr);
2229                         }
2230 
2231                         if ((len -= copy) == 0)
2232                                 return 0;
2233                         offset += copy;
2234                         to     += copy;
2235                 }
2236                 start = end;
2237         }
2238 
2239         skb_walk_frags(skb, frag_iter) {
2240                 int end;
2241 
2242                 WARN_ON(start > offset + len);
2243 
2244                 end = start + frag_iter->len;
2245                 if ((copy = end - offset) > 0) {
2246                         if (copy > len)
2247                                 copy = len;
2248                         if (skb_copy_bits(frag_iter, offset - start, to, copy))
2249                                 goto fault;
2250                         if ((len -= copy) == 0)
2251                                 return 0;
2252                         offset += copy;
2253                         to     += copy;
2254                 }
2255                 start = end;
2256         }
2257 
2258         if (!len)
2259                 return 0;
2260 
2261 fault:
2262         return -EFAULT;
2263 }
2264 EXPORT_SYMBOL(skb_copy_bits);
2265 
2266 /*
2267  * Callback from splice_to_pipe(), if we need to release some pages
2268  * at the end of the spd in case we error'ed out in filling the pipe.
2269  */
2270 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
2271 {
2272         put_page(spd->pages[i]);
2273 }
2274 
2275 static struct page *linear_to_page(struct page *page, unsigned int *len,
2276                                    unsigned int *offset,
2277                                    struct sock *sk)
2278 {
2279         struct page_frag *pfrag = sk_page_frag(sk);
2280 
2281         if (!sk_page_frag_refill(sk, pfrag))
2282                 return NULL;
2283 
2284         *len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
2285 
2286         memcpy(page_address(pfrag->page) + pfrag->offset,
2287                page_address(page) + *offset, *len);
2288         *offset = pfrag->offset;
2289         pfrag->offset += *len;
2290 
2291         return pfrag->page;
2292 }
2293 
2294 static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
2295                              struct page *page,
2296                              unsigned int offset)
2297 {
2298         return  spd->nr_pages &&
2299                 spd->pages[spd->nr_pages - 1] == page &&
2300                 (spd->partial[spd->nr_pages - 1].offset +
2301                  spd->partial[spd->nr_pages - 1].len == offset);
2302 }
2303 
2304 /*
2305  * Fill page/offset/length into spd, if it can hold more pages.
2306  */
2307 static bool spd_fill_page(struct splice_pipe_desc *spd,
2308                           struct pipe_inode_info *pipe, struct page *page,
2309                           unsigned int *len, unsigned int offset,
2310                           bool linear,
2311                           struct sock *sk)
2312 {
2313         if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
2314                 return true;
2315 
2316         if (linear) {
2317                 page = linear_to_page(page, len, &offset, sk);
2318                 if (!page)
2319                         return true;
2320         }
2321         if (spd_can_coalesce(spd, page, offset)) {
2322                 spd->partial[spd->nr_pages - 1].len += *len;
2323                 return false;
2324         }
2325         get_page(page);
2326         spd->pages[spd->nr_pages] = page;
2327         spd->partial[spd->nr_pages].len = *len;
2328         spd->partial[spd->nr_pages].offset = offset;
2329         spd->nr_pages++;
2330 
2331         return false;
2332 }
2333 
2334 static bool __splice_segment(struct page *page, unsigned int poff,
2335                              unsigned int plen, unsigned int *off,
2336                              unsigned int *len,
2337                              struct splice_pipe_desc *spd, bool linear,
2338                              struct sock *sk,
2339                              struct pipe_inode_info *pipe)
2340 {
2341         if (!*len)
2342                 return true;
2343 
2344         /* skip this segment if already processed */
2345         if (*off >= plen) {
2346                 *off -= plen;
2347                 return false;
2348         }
2349 
2350         /* ignore any bits we already processed */
2351         poff += *off;
2352         plen -= *off;
2353         *off = 0;
2354 
2355         do {
2356                 unsigned int flen = min(*len, plen);
2357 
2358                 if (spd_fill_page(spd, pipe, page, &flen, poff,
2359                                   linear, sk))
2360                         return true;
2361                 poff += flen;
2362                 plen -= flen;
2363                 *len -= flen;
2364         } while (*len && plen);
2365 
2366         return false;
2367 }
2368 
2369 /*
2370  * Map linear and fragment data from the skb to spd. It reports true if the
2371  * pipe is full or if we already spliced the requested length.
2372  */
2373 static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
2374                               unsigned int *offset, unsigned int *len,
2375                               struct splice_pipe_desc *spd, struct sock *sk)
2376 {
2377         int seg;
2378         struct sk_buff *iter;
2379 
2380         /* map the linear part :
2381          * If skb->head_frag is set, this 'linear' part is backed by a
2382          * fragment, and if the head is not shared with any clones then
2383          * we can avoid a copy since we own the head portion of this page.
2384          */
2385         if (__splice_segment(virt_to_page(skb->data),
2386                              (unsigned long) skb->data & (PAGE_SIZE - 1),
2387                              skb_headlen(skb),
2388                              offset, len, spd,
2389                              skb_head_is_locked(skb),
2390                              sk, pipe))
2391                 return true;
2392 
2393         /*
2394          * then map the fragments
2395          */
2396         for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
2397                 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
2398 
2399                 if (__splice_segment(skb_frag_page(f),
2400                                      skb_frag_off(f), skb_frag_size(f),
2401                                      offset, len, spd, false, sk, pipe))
2402                         return true;
2403         }
2404 
2405         skb_walk_frags(skb, iter) {
2406                 if (*offset >= iter->len) {
2407                         *offset -= iter->len;
2408                         continue;
2409                 }
2410                 /* __skb_splice_bits() only fails if the output has no room
2411                  * left, so no point in going over the frag_list for the error
2412                  * case.
2413                  */
2414                 if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
2415                         return true;
2416         }
2417 
2418         return false;
2419 }
2420 
2421 /*
2422  * Map data from the skb to a pipe. Should handle both the linear part,
2423  * the fragments, and the frag list.
2424  */
2425 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
2426                     struct pipe_inode_info *pipe, unsigned int tlen,
2427                     unsigned int flags)
2428 {
2429         struct partial_page partial[MAX_SKB_FRAGS];
2430         struct page *pages[MAX_SKB_FRAGS];
2431         struct splice_pipe_desc spd = {
2432                 .pages = pages,
2433                 .partial = partial,
2434                 .nr_pages_max = MAX_SKB_FRAGS,
2435                 .ops = &nosteal_pipe_buf_ops,
2436                 .spd_release = sock_spd_release,
2437         };
2438         int ret = 0;
2439 
2440         __skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
2441 
2442         if (spd.nr_pages)
2443                 ret = splice_to_pipe(pipe, &spd);
2444 
2445         return ret;
2446 }
2447 EXPORT_SYMBOL_GPL(skb_splice_bits);
2448 
2449 /* Send skb data on a socket. Socket must be locked. */
2450 int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
2451                          int len)
2452 {
2453         unsigned int orig_len = len;
2454         struct sk_buff *head = skb;
2455         unsigned short fragidx;
2456         int slen, ret;
2457 
2458 do_frag_list:
2459 
2460         /* Deal with head data */
2461         while (offset < skb_headlen(skb) && len) {
2462                 struct kvec kv;
2463                 struct msghdr msg;
2464 
2465                 slen = min_t(int, len, skb_headlen(skb) - offset);
2466                 kv.iov_base = skb->data + offset;
2467                 kv.iov_len = slen;
2468                 memset(&msg, 0, sizeof(msg));
2469                 msg.msg_flags = MSG_DONTWAIT;
2470 
2471                 ret = kernel_sendmsg_locked(sk, &msg, &kv, 1, slen);
2472                 if (ret <= 0)
2473                         goto error;
2474 
2475                 offset += ret;
2476                 len -= ret;
2477         }
2478 
2479         /* All the data was skb head? */
2480         if (!len)
2481                 goto out;
2482 
2483         /* Make offset relative to start of frags */
2484         offset -= skb_headlen(skb);
2485 
2486         /* Find where we are in frag list */
2487         for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
2488                 skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
2489 
2490                 if (offset < skb_frag_size(frag))
2491                         break;
2492 
2493                 offset -= skb_frag_size(frag);
2494         }
2495 
2496         for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
2497                 skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
2498 
2499                 slen = min_t(size_t, len, skb_frag_size(frag) - offset);
2500 
2501                 while (slen) {
2502                         ret = kernel_sendpage_locked(sk, skb_frag_page(frag),
2503                                                      skb_frag_off(frag) + offset,
2504                                                      slen, MSG_DONTWAIT);
2505                         if (ret <= 0)
2506                                 goto error;
2507 
2508                         len -= ret;
2509                         offset += ret;
2510                         slen -= ret;
2511                 }
2512 
2513                 offset = 0;
2514         }
2515 
2516         if (len) {
2517                 /* Process any frag lists */
2518 
2519                 if (skb == head) {
2520                         if (skb_has_frag_list(skb)) {
2521                                 skb = skb_shinfo(skb)->frag_list;
2522                                 goto do_frag_list;
2523                         }
2524                 } else if (skb->next) {
2525                         skb = skb->next;
2526                         goto do_frag_list;
2527                 }
2528         }
2529 
2530 out:
2531         return orig_len - len;
2532 
2533 error:
2534         return orig_len == len ? ret : orig_len - len;
2535 }
2536 EXPORT_SYMBOL_GPL(skb_send_sock_locked);
2537 
2538 /**
2539  *      skb_store_bits - store bits from kernel buffer to skb
2540  *      @skb: destination buffer
2541  *      @offset: offset in destination
2542  *      @from: source buffer
2543  *      @len: number of bytes to copy
2544  *
2545  *      Copy the specified number of bytes from the source buffer to the
2546  *      destination skb.  This function handles all the messy bits of
2547  *      traversing fragment lists and such.
2548  */
2549 
2550 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
2551 {
2552         int start = skb_headlen(skb);
2553         struct sk_buff *frag_iter;
2554         int i, copy;
2555 
2556         if (offset > (int)skb->len - len)
2557                 goto fault;
2558 
2559         if ((copy = start - offset) > 0) {
2560                 if (copy > len)
2561                         copy = len;
2562                 skb_copy_to_linear_data_offset(skb, offset, from, copy);
2563                 if ((len -= copy) == 0)
2564                         return 0;
2565                 offset += copy;
2566                 from += copy;
2567         }
2568 
2569         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2570                 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2571                 int end;
2572 
2573                 WARN_ON(start > offset + len);
2574 
2575                 end = start + skb_frag_size(frag);
2576                 if ((copy = end - offset) > 0) {
2577                         u32 p_off, p_len, copied;
2578                         struct page *p;
2579                         u8 *vaddr;
2580 
2581                         if (copy > len)
2582                                 copy = len;
2583 
2584                         skb_frag_foreach_page(frag,
2585                                               skb_frag_off(frag) + offset - start,
2586                                               copy, p, p_off, p_len, copied) {
2587                                 vaddr = kmap_atomic(p);
2588                                 memcpy(vaddr + p_off, from + copied, p_len);
2589                                 kunmap_atomic(vaddr);
2590                         }
2591 
2592                         if ((len -= copy) == 0)
2593                                 return 0;
2594                         offset += copy;
2595                         from += copy;
2596                 }
2597                 start = end;
2598         }
2599 
2600         skb_walk_frags(skb, frag_iter) {
2601                 int end;
2602 
2603                 WARN_ON(start > offset + len);
2604 
2605                 end = start + frag_iter->len;
2606                 if ((copy = end - offset) > 0) {
2607                         if (copy > len)
2608                                 copy = len;
2609                         if (skb_store_bits(frag_iter, offset - start,
2610                                            from, copy))
2611                                 goto fault;
2612                         if ((len -= copy) == 0)
2613                                 return 0;
2614                         offset += copy;
2615                         from += copy;
2616                 }
2617                 start = end;
2618         }
2619         if (!len)
2620                 return 0;
2621 
2622 fault:
2623         return -EFAULT;
2624 }
2625 EXPORT_SYMBOL(skb_store_bits);
2626 
2627 /* Checksum skb data. */
2628 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2629                       __wsum csum, const struct skb_checksum_ops *ops)
2630 {
2631         int start = skb_headlen(skb);
2632         int i, copy = start - offset;
2633         struct sk_buff *frag_iter;
2634         int pos = 0;
2635 
2636         /* Checksum header. */
2637         if (copy > 0) {
2638                 if (copy > len)
2639                         copy = len;
2640                 csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,
2641                                        skb->data + offset, copy, csum);
2642                 if ((len -= copy) == 0)
2643                         return csum;
2644                 offset += copy;
2645                 pos     = copy;
2646         }
2647 
2648         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2649                 int end;
2650                 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2651 
2652                 WARN_ON(start > offset + len);
2653 
2654                 end = start + skb_frag_size(frag);
2655                 if ((copy = end - offset) > 0) {
2656                         u32 p_off, p_len, copied;
2657                         struct page *p;
2658                         __wsum csum2;
2659                         u8 *vaddr;
2660 
2661                         if (copy > len)
2662                                 copy = len;
2663 
2664                         skb_frag_foreach_page(frag,
2665                                               skb_frag_off(frag) + offset - start,
2666                                               copy, p, p_off, p_len, copied) {
2667                                 vaddr = kmap_atomic(p);
2668                                 csum2 = INDIRECT_CALL_1(ops->update,
2669                                                         csum_partial_ext,
2670                                                         vaddr + p_off, p_len, 0);
2671                                 kunmap_atomic(vaddr);
2672                                 csum = INDIRECT_CALL_1(ops->combine,
2673                                                        csum_block_add_ext, csum,
2674                                                        csum2, pos, p_len);
2675                                 pos += p_len;
2676                         }
2677 
2678                         if (!(len -= copy))
2679                                 return csum;
2680                         offset += copy;
2681                 }
2682                 start = end;
2683         }
2684 
2685         skb_walk_frags(skb, frag_iter) {
2686                 int end;
2687 
2688                 WARN_ON(start > offset + len);
2689 
2690                 end = start + frag_iter->len;
2691                 if ((copy = end - offset) > 0) {
2692                         __wsum csum2;
2693                         if (copy > len)
2694                                 copy = len;
2695                         csum2 = __skb_checksum(frag_iter, offset - start,
2696                                                copy, 0, ops);
2697                         csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,
2698                                                csum, csum2, pos, copy);
2699                         if ((len -= copy) == 0)
2700                                 return csum;
2701                         offset += copy;
2702                         pos    += copy;
2703                 }
2704                 start = end;
2705         }
2706         BUG_ON(len);
2707 
2708         return csum;
2709 }
2710 EXPORT_SYMBOL(__skb_checksum);
2711 
2712 __wsum skb_checksum(const struct sk_buff *skb, int offset,
2713                     int len, __wsum csum)
2714 {
2715         const struct skb_checksum_ops ops = {
2716                 .update  = csum_partial_ext,
2717                 .combine = csum_block_add_ext,
2718         };
2719 
2720         return __skb_checksum(skb, offset, len, csum, &ops);
2721 }
2722 EXPORT_SYMBOL(skb_checksum);
2723 
2724 /* Both of above in one bottle. */
2725 
2726 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
2727                                     u8 *to, int len, __wsum csum)
2728 {
2729         int start = skb_headlen(skb);
2730         int i, copy = start - offset;
2731         struct sk_buff *frag_iter;
2732         int pos = 0;
2733 
2734         /* Copy header. */
2735         if (copy > 0) {
2736                 if (copy > len)
2737                         copy = len;
2738                 csum = csum_partial_copy_nocheck(skb->data + offset, to,
2739                                                  copy, csum);
2740                 if ((len -= copy) == 0)
2741                         return csum;
2742                 offset += copy;
2743                 to     += copy;
2744                 pos     = copy;
2745         }
2746 
2747         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2748                 int end;
2749 
2750                 WARN_ON(start > offset + len);
2751 
2752                 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2753                 if ((copy = end - offset) > 0) {
2754                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2755                         u32 p_off, p_len, copied;
2756                         struct page *p;
2757                         __wsum csum2;
2758                         u8 *vaddr;
2759 
2760                         if (copy > len)
2761                                 copy = len;
2762 
2763                         skb_frag_foreach_page(frag,
2764                                               skb_frag_off(frag) + offset - start,
2765                                               copy, p, p_off, p_len, copied) {
2766                                 vaddr = kmap_atomic(p);
2767                                 csum2 = csum_partial_copy_nocheck(vaddr + p_off,
2768                                                                   to + copied,
2769                                                                   p_len, 0);
2770                                 kunmap_atomic(vaddr);
2771                                 csum = csum_block_add(csum, csum2, pos);
2772                                 pos += p_len;
2773                         }
2774 
2775                         if (!(len -= copy))
2776                                 return csum;
2777                         offset += copy;
2778                         to     += copy;
2779                 }
2780                 start = end;
2781         }
2782 
2783         skb_walk_frags(skb, frag_iter) {
2784                 __wsum csum2;
2785                 int end;
2786 
2787                 WARN_ON(start > offset + len);
2788 
2789                 end = start + frag_iter->len;
2790                 if ((copy = end - offset) > 0) {
2791                         if (copy > len)
2792                                 copy = len;
2793                         csum2 = skb_copy_and_csum_bits(frag_iter,
2794                                                        offset - start,
2795                                                        to, copy, 0);
2796                         csum = csum_block_add(csum, csum2, pos);
2797                         if ((len -= copy) == 0)
2798                                 return csum;
2799                         offset += copy;
2800                         to     += copy;
2801                         pos    += copy;
2802                 }
2803                 start = end;
2804         }
2805         BUG_ON(len);
2806         return csum;
2807 }
2808 EXPORT_SYMBOL(skb_copy_and_csum_bits);
2809 
2810 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
2811 {
2812         __sum16 sum;
2813 
2814         sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
2815         /* See comments in __skb_checksum_complete(). */
2816         if (likely(!sum)) {
2817                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
2818                     !skb->csum_complete_sw)
2819                         netdev_rx_csum_fault(skb->dev, skb);
2820         }
2821         if (!skb_shared(skb))
2822                 skb->csum_valid = !sum;
2823         return sum;
2824 }
2825 EXPORT_SYMBOL(__skb_checksum_complete_head);
2826 
2827 /* This function assumes skb->csum already holds pseudo header's checksum,
2828  * which has been changed from the hardware checksum, for example, by
2829  * __skb_checksum_validate_complete(). And, the original skb->csum must
2830  * have been validated unsuccessfully for CHECKSUM_COMPLETE case.
2831  *
2832  * It returns non-zero if the recomputed checksum is still invalid, otherwise
2833  * zero. The new checksum is stored back into skb->csum unless the skb is
2834  * shared.
2835  */
2836 __sum16 __skb_checksum_complete(struct sk_buff *skb)
2837 {
2838         __wsum csum;
2839         __sum16 sum;
2840 
2841         csum = skb_checksum(skb, 0, skb->len, 0);
2842 
2843         sum = csum_fold(csum_add(skb->csum, csum));
2844         /* This check is inverted, because we already knew the hardware
2845          * checksum is invalid before calling this function. So, if the
2846          * re-computed checksum is valid instead, then we have a mismatch
2847          * between the original skb->csum and skb_checksum(). This means either
2848          * the original hardware checksum is incorrect or we screw up skb->csum
2849          * when moving skb->data around.
2850          */
2851         if (likely(!sum)) {
2852                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
2853                     !skb->csum_complete_sw)
2854                         netdev_rx_csum_fault(skb->dev, skb);
2855         }
2856 
2857         if (!skb_shared(skb)) {
2858                 /* Save full packet checksum */
2859                 skb->csum = csum;
2860                 skb->ip_summed = CHECKSUM_COMPLETE;
2861                 skb->csum_complete_sw = 1;
2862                 skb->csum_valid = !sum;
2863         }
2864 
2865         return sum;
2866 }
2867 EXPORT_SYMBOL(__skb_checksum_complete);
2868 
2869 static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
2870 {
2871         net_warn_ratelimited(
2872                 "%s: attempt to compute crc32c without libcrc32c.ko\n",
2873                 __func__);
2874         return 0;
2875 }
2876 
2877 static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
2878                                        int offset, int len)
2879 {
2880         net_warn_ratelimited(
2881                 "%s: attempt to compute crc32c without libcrc32c.ko\n",
2882                 __func__);
2883         return 0;
2884 }
2885 
2886 static const struct skb_checksum_ops default_crc32c_ops = {
2887         .update  = warn_crc32c_csum_update,
2888         .combine = warn_crc32c_csum_combine,
2889 };
2890 
2891 const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
2892         &default_crc32c_ops;
2893 EXPORT_SYMBOL(crc32c_csum_stub);
2894 
2895  /**
2896  *      skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
2897  *      @from: source buffer
2898  *
2899  *      Calculates the amount of linear headroom needed in the 'to' skb passed
2900  *      into skb_zerocopy().
2901  */
2902 unsigned int
2903 skb_zerocopy_headlen(const struct sk_buff *from)
2904 {
2905         unsigned int hlen = 0;
2906 
2907         if (!from->head_frag ||
2908             skb_headlen(from) < L1_CACHE_BYTES ||
2909             skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
2910                 hlen = skb_headlen(from);
2911 
2912         if (skb_has_frag_list(from))
2913                 hlen = from->len;
2914 
2915         return hlen;
2916 }
2917 EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
2918 
2919 /**
2920  *      skb_zerocopy - Zero copy skb to skb
2921  *      @to: destination buffer
2922  *      @from: source buffer
2923  *      @len: number of bytes to copy from source buffer
2924  *      @hlen: size of linear headroom in destination buffer
2925  *
2926  *      Copies up to `len` bytes from `from` to `to` by creating references
2927  *      to the frags in the source buffer.
2928  *
2929  *      The `hlen` as calculated by skb_zerocopy_headlen() specifies the
2930  *      headroom in the `to` buffer.
2931  *
2932  *      Return value:
2933  *      0: everything is OK
2934  *      -ENOMEM: couldn't orphan frags of @from due to lack of memory
2935  *      -EFAULT: skb_copy_bits() found some problem with skb geometry
2936  */
2937 int
2938 skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
2939 {
2940         int i, j = 0;
2941         int plen = 0; /* length of skb->head fragment */
2942         int ret;
2943         struct page *page;
2944         unsigned int offset;
2945 
2946         BUG_ON(!from->head_frag && !hlen);
2947 
2948         /* dont bother with small payloads */
2949         if (len <= skb_tailroom(to))
2950                 return skb_copy_bits(from, 0, skb_put(to, len), len);
2951 
2952         if (hlen) {
2953                 ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
2954                 if (unlikely(ret))
2955                         return ret;
2956                 len -= hlen;
2957         } else {
2958                 plen = min_t(int, skb_headlen(from), len);
2959                 if (plen) {
2960                         page = virt_to_head_page(from->head);
2961                         offset = from->data - (unsigned char *)page_address(page);
2962                         __skb_fill_page_desc(to, 0, page, offset, plen);
2963                         get_page(page);
2964                         j = 1;
2965                         len -= plen;
2966                 }
2967         }
2968 
2969         to->truesize += len + plen;
2970         to->len += len + plen;
2971         to->data_len += len + plen;
2972 
2973         if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
2974                 skb_tx_error(from);
2975                 return -ENOMEM;
2976         }
2977         skb_zerocopy_clone(to, from, GFP_ATOMIC);
2978 
2979         for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
2980                 int size;
2981 
2982                 if (!len)
2983                         break;
2984                 skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
2985                 size = min_t(int, skb_frag_size(&skb_shinfo(to)->frags[j]),
2986                                         len);
2987                 skb_frag_size_set(&skb_shinfo(to)->frags[j], size);
2988                 len -= size;
2989                 skb_frag_ref(to, j);
2990                 j++;
2991         }
2992         skb_shinfo(to)->nr_frags = j;
2993 
2994         return 0;
2995 }
2996 EXPORT_SYMBOL_GPL(skb_zerocopy);
2997 
2998 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
2999 {
3000         __wsum csum;
3001         long csstart;
3002 
3003         if (skb->ip_summed == CHECKSUM_PARTIAL)
3004                 csstart = skb_checksum_start_offset(skb);
3005         else
3006                 csstart = skb_headlen(skb);
3007 
3008         BUG_ON(csstart > skb_headlen(skb));
3009 
3010         skb_copy_from_linear_data(skb, to, csstart);
3011 
3012         csum = 0;
3013         if (csstart != skb->len)
3014                 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
3015                                               skb->len - csstart, 0);
3016 
3017         if (skb->ip_summed == CHECKSUM_PARTIAL) {
3018                 long csstuff = csstart + skb->csum_offset;
3019 
3020                 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
3021         }
3022 }
3023 EXPORT_SYMBOL(skb_copy_and_csum_dev);
3024 
3025 /**
3026  *      skb_dequeue - remove from the head of the queue
3027  *      @list: list to dequeue from
3028  *
3029  *      Remove the head of the list. The list lock is taken so the function
3030  *      may be used safely with other locking list functions. The head item is
3031  *      returned or %NULL if the list is empty.
3032  */
3033 
3034 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
3035 {
3036         unsigned long flags;
3037         struct sk_buff *result;
3038 
3039         spin_lock_irqsave(&list->lock, flags);
3040         result = __skb_dequeue(list);
3041         spin_unlock_irqrestore(&list->lock, flags);
3042         return result;
3043 }
3044 EXPORT_SYMBOL(skb_dequeue);
3045 
3046 /**
3047  *      skb_dequeue_tail - remove from the tail of the queue
3048  *      @list: list to dequeue from
3049  *
3050  *      Remove the tail of the list. The list lock is taken so the function
3051  *      may be used safely with other locking list functions. The tail item is
3052  *      returned or %NULL if the list is empty.
3053  */
3054 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
3055 {
3056         unsigned long flags;
3057         struct sk_buff *result;
3058 
3059         spin_lock_irqsave(&list->lock, flags);
3060         result = __skb_dequeue_tail(list);
3061         spin_unlock_irqrestore(&list->lock, flags);
3062         return result;
3063 }
3064 EXPORT_SYMBOL(skb_dequeue_tail);
3065 
3066 /**
3067  *      skb_queue_purge - empty a list
3068  *      @list: list to empty
3069  *
3070  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
3071  *      the list and one reference dropped. This function takes the list
3072  *      lock and is atomic with respect to other list locking functions.
3073  */
3074 void skb_queue_purge(struct sk_buff_head *list)
3075 {
3076         struct sk_buff *skb;
3077         while ((skb = skb_dequeue(list)) != NULL)
3078                 kfree_skb(skb);
3079 }
3080 EXPORT_SYMBOL(skb_queue_purge);
3081 
3082 /**
3083  *      skb_rbtree_purge - empty a skb rbtree
3084  *      @root: root of the rbtree to empty
3085  *      Return value: the sum of truesizes of all purged skbs.
3086  *
3087  *      Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
3088  *      the list and one reference dropped. This function does not take
3089  *      any lock. Synchronization should be handled by the caller (e.g., TCP
3090  *      out-of-order queue is protected by the socket lock).
3091  */
3092 unsigned int skb_rbtree_purge(struct rb_root *root)
3093 {
3094         struct rb_node *p = rb_first(root);
3095         unsigned int sum = 0;
3096 
3097         while (p) {
3098                 struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
3099 
3100                 p = rb_next(p);
3101                 rb_erase(&skb->rbnode, root);
3102                 sum += skb->truesize;
3103                 kfree_skb(skb);
3104         }
3105         return sum;
3106 }
3107 
3108 /**
3109  *      skb_queue_head - queue a buffer at the list head
3110  *      @list: list to use
3111  *      @newsk: buffer to queue
3112  *
3113  *      Queue a buffer at the start of the list. This function takes the
3114  *      list lock and can be used safely with other locking &sk_buff functions
3115  *      safely.
3116  *
3117  *      A buffer cannot be placed on two lists at the same time.
3118  */
3119 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
3120 {
3121         unsigned long flags;
3122 
3123         spin_lock_irqsave(&list->lock, flags);
3124         __skb_queue_head(list, newsk);
3125         spin_unlock_irqrestore(&list->lock, flags);
3126 }
3127 EXPORT_SYMBOL(skb_queue_head);
3128 
3129 /**
3130  *      skb_queue_tail - queue a buffer at the list tail
3131  *      @list: list to use
3132  *      @newsk: buffer to queue
3133  *
3134  *      Queue a buffer at the tail of the list. This function takes the
3135  *      list lock and can be used safely with other locking &sk_buff functions
3136  *      safely.
3137  *
3138  *      A buffer cannot be placed on two lists at the same time.
3139  */
3140 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
3141 {
3142         unsigned long flags;
3143 
3144         spin_lock_irqsave(&list->lock, flags);
3145         __skb_queue_tail(list, newsk);
3146         spin_unlock_irqrestore(&list->lock, flags);
3147 }
3148 EXPORT_SYMBOL(skb_queue_tail);
3149 
3150 /**
3151  *      skb_unlink      -       remove a buffer from a list
3152  *      @skb: buffer to remove
3153  *      @list: list to use
3154  *
3155  *      Remove a packet from a list. The list locks are taken and this
3156  *      function is atomic with respect to other list locked calls
3157  *
3158  *      You must know what list the SKB is on.
3159  */
3160 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
3161 {
3162         unsigned long flags;
3163 
3164         spin_lock_irqsave(&list->lock, flags);
3165         __skb_unlink(skb, list);
3166         spin_unlock_irqrestore(&list->lock, flags);
3167 }
3168 EXPORT_SYMBOL(skb_unlink);
3169 
3170 /**
3171  *      skb_append      -       append a buffer
3172  *      @old: buffer to insert after
3173  *      @newsk: buffer to insert
3174  *      @list: list to use
3175  *
3176  *      Place a packet after a given packet in a list. The list locks are taken
3177  *      and this function is atomic with respect to other list locked calls.
3178  *      A buffer cannot be placed on two lists at the same time.
3179  */
3180 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
3181 {
3182         unsigned long flags;
3183 
3184         spin_lock_irqsave(&list->lock, flags);
3185         __skb_queue_after(list, old, newsk);
3186         spin_unlock_irqrestore(&list->lock, flags);
3187 }
3188 EXPORT_SYMBOL(skb_append);
3189 
3190 static inline void skb_split_inside_header(struct sk_buff *skb,
3191                                            struct sk_buff* skb1,
3192                                            const u32 len, const int pos)
3193 {
3194         int i;
3195 
3196         skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
3197                                          pos - len);
3198         /* And move data appendix as is. */
3199         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
3200                 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
3201 
3202         skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
3203         skb_shinfo(skb)->nr_frags  = 0;
3204         skb1->data_len             = skb->data_len;
3205         skb1->len                  += skb1->data_len;
3206         skb->data_len              = 0;
3207         skb->len                   = len;
3208         skb_set_tail_pointer(skb, len);
3209 }
3210 
3211 static inline void skb_split_no_header(struct sk_buff *skb,
3212                                        struct sk_buff* skb1,
3213                                        const u32 len, int pos)
3214 {
3215         int i, k = 0;
3216         const int nfrags = skb_shinfo(skb)->nr_frags;
3217 
3218         skb_shinfo(skb)->nr_frags = 0;
3219         skb1->len                 = skb1->data_len = skb->len - len;
3220         skb->len                  = len;
3221         skb->data_len             = len - pos;
3222 
3223         for (i = 0; i < nfrags; i++) {
3224                 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
3225 
3226                 if (pos + size > len) {
3227                         skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
3228 
3229                         if (pos < len) {
3230                                 /* Split frag.
3231                                  * We have two variants in this case:
3232                                  * 1. Move all the frag to the second
3233                                  *    part, if it is possible. F.e.
3234                                  *    this approach is mandatory for TUX,
3235                                  *    where splitting is expensive.
3236                                  * 2. Split is accurately. We make this.
3237                                  */
3238                                 skb_frag_ref(skb, i);
3239                                 skb_frag_off_add(&skb_shinfo(skb1)->frags[0], len - pos);
3240                                 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
3241                                 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
3242                                 skb_shinfo(skb)->nr_frags++;
3243                         }
3244                         k++;
3245                 } else
3246                         skb_shinfo(skb)->nr_frags++;
3247                 pos += size;
3248         }
3249         skb_shinfo(skb1)->nr_frags = k;
3250 }
3251 
3252 /**
3253  * skb_split - Split fragmented skb to two parts at length len.
3254  * @skb: the buffer to split
3255  * @skb1: the buffer to receive the second part
3256  * @len: new length for skb
3257  */
3258 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
3259 {
3260         int pos = skb_headlen(skb);
3261 
3262         skb_shinfo(skb1)->tx_flags |= skb_shinfo(skb)->tx_flags &
3263                                       SKBTX_SHARED_FRAG;
3264         skb_zerocopy_clone(skb1, skb, 0);
3265         if (len < pos)  /* Split line is inside header. */
3266                 skb_split_inside_header(skb, skb1, len, pos);
3267         else            /* Second chunk has no header, nothing to copy. */
3268                 skb_split_no_header(skb, skb1, len, pos);
3269 }
3270 EXPORT_SYMBOL(skb_split);
3271 
3272 /* Shifting from/to a cloned skb is a no-go.
3273  *
3274  * Caller cannot keep skb_shinfo related pointers past calling here!
3275  */
3276 static int skb_prepare_for_shift(struct sk_buff *skb)
3277 {
3278         return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
3279 }
3280 
3281 /**
3282  * skb_shift - Shifts paged data partially from skb to another
3283  * @tgt: buffer into which tail data gets added
3284  * @skb: buffer from which the paged data comes from
3285  * @shiftlen: shift up to this many bytes
3286  *
3287  * Attempts to shift up to shiftlen worth of bytes, which may be less than
3288  * the length of the skb, from skb to tgt. Returns number bytes shifted.
3289  * It's up to caller to free skb if everything was shifted.
3290  *
3291  * If @tgt runs out of frags, the whole operation is aborted.
3292  *
3293  * Skb cannot include anything else but paged data while tgt is allowed
3294  * to have non-paged data as well.
3295  *
3296  * TODO: full sized shift could be optimized but that would need
3297  * specialized skb free'er to handle frags without up-to-date nr_frags.
3298  */
3299 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
3300 {
3301         int from, to, merge, todo;
3302         skb_frag_t *fragfrom, *fragto;
3303 
3304         BUG_ON(shiftlen > skb->len);
3305 
3306         if (skb_headlen(skb))
3307                 return 0;
3308         if (skb_zcopy(tgt) || skb_zcopy(skb))
3309                 return 0;
3310 
3311         todo = shiftlen;
3312         from = 0;
3313         to = skb_shinfo(tgt)->nr_frags;
3314         fragfrom = &skb_shinfo(skb)->frags[from];
3315 
3316         /* Actual merge is delayed until the point when we know we can
3317          * commit all, so that we don't have to undo partial changes
3318          */
3319         if (!to ||
3320             !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
3321                               skb_frag_off(fragfrom))) {
3322                 merge = -1;
3323         } else {
3324                 merge = to - 1;
3325 
3326                 todo -= skb_frag_size(fragfrom);
3327                 if (todo < 0) {
3328                         if (skb_prepare_for_shift(skb) ||
3329                             skb_prepare_for_shift(tgt))
3330                                 return 0;
3331 
3332                         /* All previous frag pointers might be stale! */
3333                         fragfrom = &skb_shinfo(skb)->frags[from];
3334                         fragto = &skb_shinfo(tgt)->frags[merge];
3335 
3336                         skb_frag_size_add(fragto, shiftlen);
3337                         skb_frag_size_sub(fragfrom, shiftlen);
3338                         skb_frag_off_add(fragfrom, shiftlen);
3339 
3340                         goto onlymerged;
3341                 }
3342 
3343                 from++;
3344         }
3345 
3346         /* Skip full, not-fitting skb to avoid expensive operations */
3347         if ((shiftlen == skb->len) &&
3348             (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
3349                 return 0;
3350 
3351         if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
3352                 return 0;
3353 
3354         while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
3355                 if (to == MAX_SKB_FRAGS)
3356                         return 0;
3357 
3358                 fragfrom = &skb_shinfo(skb)->frags[from];
3359                 fragto = &skb_shinfo(tgt)->frags[to];
3360 
3361                 if (todo >= skb_frag_size(fragfrom)) {
3362                         *fragto = *fragfrom;
3363                         todo -= skb_frag_size(fragfrom);
3364                         from++;
3365                         to++;
3366 
3367                 } else {
3368                         __skb_frag_ref(fragfrom);
3369                         skb_frag_page_copy(fragto, fragfrom);
3370                         skb_frag_off_copy(fragto, fragfrom);
3371                         skb_frag_size_set(fragto, todo);
3372 
3373                         skb_frag_off_add(fragfrom, todo);
3374                         skb_frag_size_sub(fragfrom, todo);
3375                         todo = 0;
3376 
3377                         to++;
3378                         break;
3379                 }
3380         }
3381 
3382         /* Ready to "commit" this state change to tgt */
3383         skb_shinfo(tgt)->nr_frags = to;
3384 
3385         if (merge >= 0) {
3386                 fragfrom = &skb_shinfo(skb)->frags[0];
3387                 fragto = &skb_shinfo(tgt)->frags[merge];
3388 
3389                 skb_frag_size_add(fragto, skb_frag_size(fragfrom));
3390                 __skb_frag_unref(fragfrom);
3391         }
3392 
3393         /* Reposition in the original skb */
3394         to = 0;
3395         while (from < skb_shinfo(skb)->nr_frags)
3396                 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
3397         skb_shinfo(skb)->nr_frags = to;
3398 
3399         BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
3400 
3401 onlymerged:
3402         /* Most likely the tgt won't ever need its checksum anymore, skb on
3403          * the other hand might need it if it needs to be resent
3404          */
3405         tgt->ip_summed = CHECKSUM_PARTIAL;
3406         skb->ip_summed = CHECKSUM_PARTIAL;
3407 
3408         /* Yak, is it really working this way? Some helper please? */
3409         skb->len -= shiftlen;
3410         skb->data_len -= shiftlen;
3411         skb->truesize -= shiftlen;
3412         tgt->len += shiftlen;
3413         tgt->data_len += shiftlen;
3414         tgt->truesize += shiftlen;
3415 
3416         return shiftlen;
3417 }
3418 
3419 /**
3420  * skb_prepare_seq_read - Prepare a sequential read of skb data
3421  * @skb: the buffer to read
3422  * @from: lower offset of data to be read
3423  * @to: upper offset of data to be read
3424  * @st: state variable
3425  *
3426  * Initializes the specified state variable. Must be called before
3427  * invoking skb_seq_read() for the first time.
3428  */
3429 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
3430                           unsigned int to, struct skb_seq_state *st)
3431 {
3432         st->lower_offset = from;
3433         st->upper_offset = to;
3434         st->root_skb = st->cur_skb = skb;
3435         st->frag_idx = st->stepped_offset = 0;
3436         st->frag_data = NULL;
3437 }
3438 EXPORT_SYMBOL(skb_prepare_seq_read);
3439 
3440 /**
3441  * skb_seq_read - Sequentially read skb data
3442  * @consumed: number of bytes consumed by the caller so far
3443  * @data: destination pointer for data to be returned
3444  * @st: state variable
3445  *
3446  * Reads a block of skb data at @consumed relative to the
3447  * lower offset specified to skb_prepare_seq_read(). Assigns
3448  * the head of the data block to @data and returns the length
3449  * of the block or 0 if the end of the skb data or the upper
3450  * offset has been reached.
3451  *
3452  * The caller is not required to consume all of the data
3453  * returned, i.e. @consumed is typically set to the number
3454  * of bytes already consumed and the next call to
3455  * skb_seq_read() will return the remaining part of the block.
3456  *
3457  * Note 1: The size of each block of data returned can be arbitrary,
3458  *       this limitation is the cost for zerocopy sequential
3459  *       reads of potentially non linear data.
3460  *
3461  * Note 2: Fragment lists within fragments are not implemented
3462  *       at the moment, state->root_skb could be replaced with
3463  *       a stack for this purpose.
3464  */
3465 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
3466                           struct skb_seq_state *st)
3467 {
3468         unsigned int block_limit, abs_offset = consumed + st->lower_offset;
3469         skb_frag_t *frag;
3470 
3471         if (unlikely(abs_offset >= st->upper_offset)) {
3472                 if (st->frag_data) {
3473                         kunmap_atomic(st->frag_data);
3474                         st->frag_data = NULL;
3475                 }
3476                 return 0;
3477         }
3478 
3479 next_skb:
3480         block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
3481 
3482         if (abs_offset < block_limit && !st->frag_data) {
3483                 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
3484                 return block_limit - abs_offset;
3485         }
3486 
3487         if (st->frag_idx == 0 && !st->frag_data)
3488                 st->stepped_offset += skb_headlen(st->cur_skb);
3489 
3490         while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
3491                 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
3492                 block_limit = skb_frag_size(frag) + st->stepped_offset;
3493 
3494                 if (abs_offset < block_limit) {
3495                         if (!st->frag_data)
3496                                 st->frag_data = kmap_atomic(skb_frag_page(frag));
3497 
3498                         *data = (u8 *) st->frag_data + skb_frag_off(frag) +
3499                                 (abs_offset - st->stepped_offset);
3500 
3501                         return block_limit - abs_offset;
3502                 }
3503 
3504                 if (st->frag_data) {
3505                         kunmap_atomic(st->frag_data);
3506                         st->frag_data = NULL;
3507                 }
3508 
3509                 st->frag_idx++;
3510                 st->stepped_offset += skb_frag_size(frag);
3511         }
3512 
3513         if (st->frag_data) {
3514                 kunmap_atomic(st->frag_data);
3515                 st->frag_data = NULL;
3516         }
3517 
3518         if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
3519                 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
3520                 st->frag_idx = 0;
3521                 goto next_skb;
3522         } else if (st->cur_skb->next) {
3523                 st->cur_skb = st->cur_skb->next;
3524                 st->frag_idx = 0;
3525                 goto next_skb;
3526         }
3527 
3528         return 0;
3529 }
3530 EXPORT_SYMBOL(skb_seq_read);
3531 
3532 /**
3533  * skb_abort_seq_read - Abort a sequential read of skb data
3534  * @st: state variable
3535  *
3536  * Must be called if skb_seq_read() was not called until it
3537  * returned 0.
3538  */
3539 void skb_abort_seq_read(struct skb_seq_state *st)
3540 {
3541         if (st->frag_data)
3542                 kunmap_atomic(st->frag_data);
3543 }
3544 EXPORT_SYMBOL(skb_abort_seq_read);
3545 
3546 #define TS_SKB_CB(state)        ((struct skb_seq_state *) &((state)->cb))
3547 
3548 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
3549                                           struct ts_config *conf,
3550                                           struct ts_state *state)
3551 {
3552         return skb_seq_read(offset, text, TS_SKB_CB(state));
3553 }
3554 
3555 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
3556 {
3557         skb_abort_seq_read(TS_SKB_CB(state));
3558 }
3559 
3560 /**
3561  * skb_find_text - Find a text pattern in skb data
3562  * @skb: the buffer to look in
3563  * @from: search offset
3564  * @to: search limit
3565  * @config: textsearch configuration
3566  *
3567  * Finds a pattern in the skb data according to the specified
3568  * textsearch configuration. Use textsearch_next() to retrieve
3569  * subsequent occurrences of the pattern. Returns the offset
3570  * to the first occurrence or UINT_MAX if no match was found.
3571  */
3572 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
3573                            unsigned int to, struct ts_config *config)
3574 {
3575         struct ts_state state;
3576         unsigned int ret;
3577 
3578         config->get_next_block = skb_ts_get_next_block;
3579         config->finish = skb_ts_finish;
3580 
3581         skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
3582 
3583         ret = textsearch_find(config, &state);
3584         return (ret <= to - from ? ret : UINT_MAX);
3585 }
3586 EXPORT_SYMBOL(skb_find_text);
3587 
3588 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
3589                          int offset, size_t size)
3590 {
3591         int i = skb_shinfo(skb)->nr_frags;
3592 
3593         if (skb_can_coalesce(skb, i, page, offset)) {
3594                 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
3595         } else if (i < MAX_SKB_FRAGS) {
3596                 get_page(page);
3597                 skb_fill_page_desc(skb, i, page, offset, size);
3598         } else {
3599                 return -EMSGSIZE;
3600         }
3601 
3602         return 0;
3603 }
3604 EXPORT_SYMBOL_GPL(skb_append_pagefrags);
3605 
3606 /**
3607  *      skb_pull_rcsum - pull skb and update receive checksum
3608  *      @skb: buffer to update
3609  *      @len: length of data pulled
3610  *
3611  *      This function performs an skb_pull on the packet and updates
3612  *      the CHECKSUM_COMPLETE checksum.  It should be used on
3613  *      receive path processing instead of skb_pull unless you know
3614  *      that the checksum difference is zero (e.g., a valid IP header)
3615  *      or you are setting ip_summed to CHECKSUM_NONE.
3616  */
3617 void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
3618 {
3619         unsigned char *data = skb->data;
3620 
3621         BUG_ON(len > skb->len);
3622         __skb_pull(skb, len);
3623         skb_postpull_rcsum(skb, data, len);
3624         return skb->data;
3625 }
3626 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
3627 
3628 static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
3629 {
3630         skb_frag_t head_frag;
3631         struct page *page;
3632 
3633         page = virt_to_head_page(frag_skb->head);
3634         __skb_frag_set_page(&head_frag, page);
3635         skb_frag_off_set(&head_frag, frag_skb->data -
3636                          (unsigned char *)page_address(page));
3637         skb_frag_size_set(&head_frag, skb_headlen(frag_skb));
3638         return head_frag;
3639 }
3640 
3641 /**
3642  *      skb_segment - Perform protocol segmentation on skb.
3643  *      @head_skb: buffer to segment
3644  *      @features: features for the output path (see dev->features)
3645  *
3646  *      This function performs segmentation on the given skb.  It returns
3647  *      a pointer to the first in a list of new skbs for the segments.
3648  *      In case of error it returns ERR_PTR(err).
3649  */
3650 struct sk_buff *skb_segment(struct sk_buff *head_skb,
3651                             netdev_features_t features)
3652 {
3653         struct sk_buff *segs = NULL;
3654         struct sk_buff *tail = NULL;
3655         struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
3656         skb_frag_t *frag = skb_shinfo(head_skb)->frags;
3657         unsigned int mss = skb_shinfo(head_skb)->gso_size;
3658         unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
3659         struct sk_buff *frag_skb = head_skb;
3660         unsigned int offset = doffset;
3661         unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
3662         unsigned int partial_segs = 0;
3663         unsigned int headroom;
3664         unsigned int len = head_skb->len;
3665         __be16 proto;
3666         bool csum, sg;
3667         int nfrags = skb_shinfo(head_skb)->nr_frags;
3668         int err = -ENOMEM;
3669         int i = 0;
3670         int pos;
3671         int dummy;
3672 
3673         if (list_skb && !list_skb->head_frag && skb_headlen(list_skb) &&
3674             (skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY)) {
3675                 /* gso_size is untrusted, and we have a frag_list with a linear
3676                  * non head_frag head.
3677                  *
3678                  * (we assume checking the first list_skb member suffices;
3679                  * i.e if either of the list_skb members have non head_frag
3680                  * head, then the first one has too).
3681                  *
3682                  * If head_skb's headlen does not fit requested gso_size, it
3683                  * means that the frag_list members do NOT terminate on exact
3684                  * gso_size boundaries. Hence we cannot perform skb_frag_t page
3685                  * sharing. Therefore we must fallback to copying the frag_list
3686                  * skbs; we do so by disabling SG.
3687                  */
3688                 if (mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb))
3689                         features &= ~NETIF_F_SG;
3690         }
3691 
3692         __skb_push(head_skb, doffset);
3693         proto = skb_network_protocol(head_skb, &dummy);
3694         if (unlikely(!proto))
3695                 return ERR_PTR(-EINVAL);
3696 
3697         sg = !!(features & NETIF_F_SG);
3698         csum = !!can_checksum_protocol(features, proto);
3699 
3700         if (sg && csum && (mss != GSO_BY_FRAGS))  {
3701                 if (!(features & NETIF_F_GSO_PARTIAL)) {
3702                         struct sk_buff *iter;
3703                         unsigned int frag_len;
3704 
3705                         if (!list_skb ||
3706                             !net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
3707                                 goto normal;
3708 
3709                         /* If we get here then all the required
3710                          * GSO features except frag_list are supported.
3711                          * Try to split the SKB to multiple GSO SKBs
3712                          * with no frag_list.
3713                          * Currently we can do that only when the buffers don't
3714                          * have a linear part and all the buffers except
3715                          * the last are of the same length.
3716                          */
3717                         frag_len = list_skb->len;
3718                         skb_walk_frags(head_skb, iter) {
3719                                 if (frag_len != iter->len && iter->next)
3720                                         goto normal;
3721                                 if (skb_headlen(iter) && !iter->head_frag)
3722                                         goto normal;
3723 
3724                                 len -= iter->len;
3725                         }
3726 
3727                         if (len != frag_len)
3728                                 goto normal;
3729                 }
3730 
3731                 /* GSO partial only requires that we trim off any excess that
3732                  * doesn't fit into an MSS sized block, so take care of that
3733                  * now.
3734                  */
3735                 partial_segs = len / mss;
3736                 if (partial_segs > 1)
3737                         mss *= partial_segs;
3738                 else
3739                         partial_segs = 0;
3740         }
3741 
3742 normal:
3743         headroom = skb_headroom(head_skb);
3744         pos = skb_headlen(head_skb);
3745 
3746         do {
3747                 struct sk_buff *nskb;
3748                 skb_frag_t *nskb_frag;
3749                 int hsize;
3750                 int size;
3751 
3752                 if (unlikely(mss == GSO_BY_FRAGS)) {
3753                         len = list_skb->len;
3754                 } else {
3755                         len = head_skb->len - offset;
3756                         if (len > mss)
3757                                 len = mss;
3758                 }
3759 
3760                 hsize = skb_headlen(head_skb) - offset;
3761                 if (hsize < 0)
3762                         hsize = 0;
3763                 if (hsize > len || !sg)
3764                         hsize = len;
3765 
3766                 if (!hsize && i >= nfrags && skb_headlen(list_skb) &&
3767                     (skb_headlen(list_skb) == len || sg)) {
3768                         BUG_ON(skb_headlen(list_skb) > len);
3769 
3770                         i = 0;
3771                         nfrags = skb_shinfo(list_skb)->nr_frags;
3772                         frag = skb_shinfo(list_skb)->frags;
3773                         frag_skb = list_skb;
3774                         pos += skb_headlen(list_skb);
3775 
3776                         while (pos < offset + len) {
3777                                 BUG_ON(i >= nfrags);
3778 
3779                                 size = skb_frag_size(frag);
3780                                 if (pos + size > offset + len)
3781                                         break;
3782 
3783                                 i++;
3784                                 pos += size;
3785                                 frag++;
3786                         }
3787 
3788                         nskb = skb_clone(list_skb, GFP_ATOMIC);
3789                         list_skb = list_skb->next;
3790 
3791                         if (unlikely(!nskb))
3792                                 goto err;
3793 
3794                         if (unlikely(pskb_trim(nskb, len))) {
3795                                 kfree_skb(nskb);
3796                                 goto err;
3797                         }
3798 
3799                         hsize = skb_end_offset(nskb);
3800                         if (skb_cow_head(nskb, doffset + headroom)) {
3801                                 kfree_skb(nskb);
3802                                 goto err;
3803                         }
3804 
3805                         nskb->truesize += skb_end_offset(nskb) - hsize;
3806                         skb_release_head_state(nskb);
3807                         __skb_push(nskb, doffset);
3808                 } else {
3809                         nskb = __alloc_skb(hsize + doffset + headroom,
3810                                            GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
3811                                            NUMA_NO_NODE);
3812 
3813                         if (unlikely(!nskb))
3814                                 goto err;
3815 
3816                         skb_reserve(nskb, headroom);
3817                         __skb_put(nskb, doffset);
3818                 }
3819 
3820                 if (segs)
3821                         tail->next = nskb;
3822                 else
3823                         segs = nskb;
3824                 tail = nskb;
3825 
3826                 __copy_skb_header(nskb, head_skb);
3827 
3828                 skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
3829                 skb_reset_mac_len(nskb);
3830 
3831                 skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
3832                                                  nskb->data - tnl_hlen,
3833                                                  doffset + tnl_hlen);
3834 
3835                 if (nskb->len == len + doffset)
3836                         goto perform_csum_check;
3837 
3838                 if (!sg) {
3839                         if (!nskb->remcsum_offload)
3840                                 nskb->ip_summed = CHECKSUM_NONE;
3841                         SKB_GSO_CB(nskb)->csum =
3842                                 skb_copy_and_csum_bits(head_skb, offset,
3843                                                        skb_put(nskb, len),
3844                                                        len, 0);
3845                         SKB_GSO_CB(nskb)->csum_start =
3846                                 skb_headroom(nskb) + doffset;
3847                         continue;
3848                 }
3849 
3850                 nskb_frag = skb_shinfo(nskb)->frags;
3851 
3852                 skb_copy_from_linear_data_offset(head_skb, offset,
3853                                                  skb_put(nskb, hsize), hsize);
3854 
3855                 skb_shinfo(nskb)->tx_flags |= skb_shinfo(head_skb)->tx_flags &
3856                                               SKBTX_SHARED_FRAG;
3857 
3858                 if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
3859                     skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
3860                         goto err;
3861 
3862                 while (pos < offset + len) {
3863                         if (i >= nfrags) {
3864                                 i = 0;
3865                                 nfrags = skb_shinfo(list_skb)->nr_frags;
3866                                 frag = skb_shinfo(list_skb)->frags;
3867                                 frag_skb = list_skb;
3868                                 if (!skb_headlen(list_skb)) {
3869                                         BUG_ON(!nfrags);
3870                                 } else {
3871                                         BUG_ON(!list_skb->head_frag);
3872 
3873                                         /* to make room for head_frag. */
3874                                         i--;
3875                                         frag--;
3876                                 }
3877                                 if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
3878                                     skb_zerocopy_clone(nskb, frag_skb,
3879                                                        GFP_ATOMIC))
3880                                         goto err;
3881 
3882                                 list_skb = list_skb->next;
3883                         }
3884 
3885                         if (unlikely(skb_shinfo(nskb)->nr_frags >=
3886                                      MAX_SKB_FRAGS)) {
3887                                 net_warn_ratelimited(
3888                                         "skb_segment: too many frags: %u %u\n",
3889                                         pos, mss);
3890                                 err = -EINVAL;
3891                                 goto err;
3892                         }
3893 
3894                         *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
3895                         __skb_frag_ref(nskb_frag);
3896                         size = skb_frag_size(nskb_frag);
3897 
3898                         if (pos < offset) {
3899                                 skb_frag_off_add(nskb_frag, offset - pos);
3900                                 skb_frag_size_sub(nskb_frag, offset - pos);
3901                         }
3902 
3903                         skb_shinfo(nskb)->nr_frags++;
3904 
3905                         if (pos + size <= offset + len) {
3906                                 i++;
3907                                 frag++;
3908                                 pos += size;
3909                         } else {
3910                                 skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
3911                                 goto skip_fraglist;
3912                         }
3913 
3914                         nskb_frag++;
3915                 }
3916 
3917 skip_fraglist:
3918                 nskb->data_len = len - hsize;
3919                 nskb->len += nskb->data_len;
3920                 nskb->truesize += nskb->data_len;
3921 
3922 perform_csum_check:
3923                 if (!csum) {
3924                         if (skb_has_shared_frag(nskb) &&
3925                             __skb_linearize(nskb))
3926                                 goto err;
3927 
3928                         if (!nskb->remcsum_offload)
3929                                 nskb->ip_summed = CHECKSUM_NONE;
3930                         SKB_GSO_CB(nskb)->csum =
3931                                 skb_checksum(nskb, doffset,
3932                                              nskb->len - doffset, 0);
3933                         SKB_GSO_CB(nskb)->csum_start =
3934                                 skb_headroom(nskb) + doffset;
3935                 }
3936         } while ((offset += len) < head_skb->len);
3937 
3938         /* Some callers want to get the end of the list.
3939          * Put it in segs->prev to avoid walking the list.
3940          * (see validate_xmit_skb_list() for example)
3941          */
3942         segs->prev = tail;
3943 
3944         if (partial_segs) {
3945                 struct sk_buff *iter;
3946                 int type = skb_shinfo(head_skb)->gso_type;
3947                 unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
3948 
3949                 /* Update type to add partial and then remove dodgy if set */
3950                 type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
3951                 type &= ~SKB_GSO_DODGY;
3952 
3953                 /* Update GSO info and prepare to start updating headers on
3954                  * our way back down the stack of protocols.
3955                  */
3956                 for (iter = segs; iter; iter = iter->next) {
3957                         skb_shinfo(iter)->gso_size = gso_size;
3958                         skb_shinfo(iter)->gso_segs = partial_segs;
3959                         skb_shinfo(iter)->gso_type = type;
3960                         SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
3961                 }
3962 
3963                 if (tail->len - doffset <= gso_size)
3964                         skb_shinfo(tail)->gso_size = 0;
3965                 else if (tail != segs)
3966                         skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
3967         }
3968 
3969         /* Following permits correct backpressure, for protocols
3970          * using skb_set_owner_w().
3971          * Idea is to tranfert ownership from head_skb to last segment.
3972          */
3973         if (head_skb->destructor == sock_wfree) {
3974                 swap(tail->truesize, head_skb->truesize);
3975                 swap(tail->destructor, head_skb->destructor);
3976                 swap(tail->sk, head_skb->sk);
3977         }
3978         return segs;
3979 
3980 err:
3981         kfree_skb_list(segs);
3982         return ERR_PTR(err);
3983 }
3984 EXPORT_SYMBOL_GPL(skb_segment);
3985 
3986 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
3987 {
3988         struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
3989         unsigned int offset = skb_gro_offset(skb);
3990         unsigned int headlen = skb_headlen(skb);
3991         unsigned int len = skb_gro_len(skb);
3992         unsigned int delta_truesize;
3993         struct sk_buff *lp;
3994 
3995         if (unlikely(p->len + len >= 65536 || NAPI_GRO_CB(skb)->flush))
3996                 return -E2BIG;
3997 
3998         lp = NAPI_GRO_CB(p)->last;
3999         pinfo = skb_shinfo(lp);
4000 
4001         if (headlen <= offset) {
4002                 skb_frag_t *frag;
4003                 skb_frag_t *frag2;
4004                 int i = skbinfo->nr_frags;
4005                 int nr_frags = pinfo->nr_frags + i;
4006 
4007                 if (nr_frags > MAX_SKB_FRAGS)
4008                         goto merge;
4009 
4010                 offset -= headlen;
4011                 pinfo->nr_frags = nr_frags;
4012                 skbinfo->nr_frags = 0;
4013 
4014                 frag = pinfo->frags + nr_frags;
4015                 frag2 = skbinfo->frags + i;
4016                 do {
4017                         *--frag = *--frag2;
4018                 } while (--i);
4019 
4020                 skb_frag_off_add(frag, offset);
4021                 skb_frag_size_sub(frag, offset);
4022 
4023                 /* all fragments truesize : remove (head size + sk_buff) */
4024                 delta_truesize = skb->truesize -
4025                                  SKB_TRUESIZE(skb_end_offset(skb));
4026 
4027                 skb->truesize -= skb->data_len;
4028                 skb->len -= skb->data_len;
4029                 skb->data_len = 0;
4030 
4031                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
4032                 goto done;
4033         } else if (skb->head_frag) {
4034                 int nr_frags = pinfo->nr_frags;
4035                 skb_frag_t *frag = pinfo->frags + nr_frags;
4036                 struct page *page = virt_to_head_page(skb->head);
4037                 unsigned int first_size = headlen - offset;
4038                 unsigned int first_offset;
4039 
4040                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
4041                         goto merge;
4042 
4043                 first_offset = skb->data -
4044                                (unsigned char *)page_address(page) +
4045                                offset;
4046 
4047                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
4048 
4049                 __skb_frag_set_page(frag, page);
4050                 skb_frag_off_set(frag, first_offset);
4051                 skb_frag_size_set(frag, first_size);
4052 
4053                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
4054                 /* We dont need to clear skbinfo->nr_frags here */
4055 
4056                 delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
4057                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
4058                 goto done;
4059         }
4060 
4061 merge:
4062         delta_truesize = skb->truesize;
4063         if (offset > headlen) {
4064                 unsigned int eat = offset - headlen;
4065 
4066                 skb_frag_off_add(&skbinfo->frags[0], eat);
4067                 skb_frag_size_sub(&skbinfo->frags[0], eat);
4068                 skb->data_len -= eat;
4069                 skb->len -= eat;
4070                 offset = headlen;
4071         }
4072 
4073         __skb_pull(skb, offset);
4074 
4075         if (NAPI_GRO_CB(p)->last == p)
4076                 skb_shinfo(p)->frag_list = skb;
4077         else
4078                 NAPI_GRO_CB(p)->last->next = skb;
4079         NAPI_GRO_CB(p)->last = skb;
4080         __skb_header_release(skb);
4081         lp = p;
4082 
4083 done:
4084         NAPI_GRO_CB(p)->count++;
4085         p->data_len += len;
4086         p->truesize += delta_truesize;
4087         p->len += len;
4088         if (lp != p) {
4089                 lp->data_len += len;
4090                 lp->truesize += delta_truesize;
4091                 lp->len += len;
4092         }
4093         NAPI_GRO_CB(skb)->same_flow = 1;
4094         return 0;
4095 }
4096 EXPORT_SYMBOL_GPL(skb_gro_receive);
4097 
4098 #ifdef CONFIG_SKB_EXTENSIONS
4099 #define SKB_EXT_ALIGN_VALUE     8
4100 #define SKB_EXT_CHUNKSIZEOF(x)  (ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE)
4101 
4102 static const u8 skb_ext_type_len[] = {
4103 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4104         [SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info),
4105 #endif
4106 #ifdef CONFIG_XFRM
4107         [SKB_EXT_SEC_PATH] = SKB_EXT_CHUNKSIZEOF(struct sec_path),
4108 #endif
4109 #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4110         [TC_SKB_EXT] = SKB_EXT_CHUNKSIZEOF(struct tc_skb_ext),
4111 #endif
4112 };
4113 
4114 static __always_inline unsigned int skb_ext_total_length(void)
4115 {
4116         return SKB_EXT_CHUNKSIZEOF(struct skb_ext) +
4117 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4118                 skb_ext_type_len[SKB_EXT_BRIDGE_NF] +
4119 #endif
4120 #ifdef CONFIG_XFRM
4121                 skb_ext_type_len[SKB_EXT_SEC_PATH] +
4122 #endif
4123 #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4124                 skb_ext_type_len[TC_SKB_EXT] +
4125 #endif
4126                 0;
4127 }
4128 
4129 static void skb_extensions_init(void)
4130 {
4131         BUILD_BUG_ON(SKB_EXT_NUM >= 8);
4132         BUILD_BUG_ON(skb_ext_total_length() > 255);
4133 
4134         skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache",
4135                                              SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),
4136                                              0,
4137                                              SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4138                                              NULL);
4139 }
4140 #else
4141 static void skb_extensions_init(void) {}
4142 #endif
4143 
4144 void __init skb_init(void)
4145 {
4146         skbuff_head_cache = kmem_cache_create_usercopy("skbuff_head_cache",
4147                                               sizeof(struct sk_buff),
4148                                               0,
4149                                               SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4150                                               offsetof(struct sk_buff, cb),
4151                                               sizeof_field(struct sk_buff, cb),
4152                                               NULL);
4153         skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
4154                                                 sizeof(struct sk_buff_fclones),
4155                                                 0,
4156                                                 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4157                                                 NULL);
4158         skb_extensions_init();
4159 }
4160 
4161 static int
4162 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len,
4163                unsigned int recursion_level)
4164 {
4165         int start = skb_headlen(skb);
4166         int i, copy = start - offset;
4167         struct sk_buff *frag_iter;
4168         int elt = 0;
4169 
4170         if (unlikely(recursion_level >= 24))
4171                 return -EMSGSIZE;
4172 
4173         if (copy > 0) {
4174                 if (copy > len)
4175                         copy = len;
4176                 sg_set_buf(sg, skb->data + offset, copy);
4177                 elt++;
4178                 if ((len -= copy) == 0)
4179                         return elt;
4180                 offset += copy;
4181         }
4182 
4183         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
4184                 int end;
4185 
4186                 WARN_ON(start > offset + len);
4187 
4188                 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
4189                 if ((copy = end - offset) > 0) {
4190                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
4191                         if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4192                                 return -EMSGSIZE;
4193 
4194                         if (copy > len)
4195                                 copy = len;
4196                         sg_set_page(&sg[elt], skb_frag_page(frag), copy,
4197                                     skb_frag_off(frag) + offset - start);
4198                         elt++;
4199                         if (!(len -= copy))
4200                                 return elt;
4201                         offset += copy;
4202                 }
4203                 start = end;
4204         }
4205 
4206         skb_walk_frags(skb, frag_iter) {
4207                 int end, ret;
4208 
4209                 WARN_ON(start > offset + len);
4210 
4211                 end = start + frag_iter->len;
4212                 if ((copy = end - offset) > 0) {
4213                         if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4214                                 return -EMSGSIZE;
4215 
4216                         if (copy > len)
4217                                 copy = len;
4218                         ret = __skb_to_sgvec(frag_iter, sg+elt, offset - start,
4219                                               copy, recursion_level + 1);
4220                         if (unlikely(ret < 0))
4221                                 return ret;
4222                         elt += ret;
4223                         if ((len -= copy) == 0)
4224                                 return elt;
4225                         offset += copy;
4226                 }
4227                 start = end;
4228         }
4229         BUG_ON(len);
4230         return elt;
4231 }
4232 
4233 /**
4234  *      skb_to_sgvec - Fill a scatter-gather list from a socket buffer
4235  *      @skb: Socket buffer containing the buffers to be mapped
4236  *      @sg: The scatter-gather list to map into
4237  *      @offset: The offset into the buffer's contents to start mapping
4238  *      @len: Length of buffer space to be mapped
4239  *
4240  *      Fill the specified scatter-gather list with mappings/pointers into a
4241  *      region of the buffer space attached to a socket buffer. Returns either
4242  *      the number of scatterlist items used, or -EMSGSIZE if the contents
4243  *      could not fit.
4244  */
4245 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
4246 {
4247         int nsg = __skb_to_sgvec(skb, sg, offset, len, 0);
4248 
4249         if (nsg <= 0)
4250                 return nsg;
4251 
4252         sg_mark_end(&sg[nsg - 1]);
4253 
4254         return nsg;
4255 }
4256 EXPORT_SYMBOL_GPL(skb_to_sgvec);
4257 
4258 /* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
4259  * sglist without mark the sg which contain last skb data as the end.
4260  * So the caller can mannipulate sg list as will when padding new data after
4261  * the first call without calling sg_unmark_end to expend sg list.
4262  *
4263  * Scenario to use skb_to_sgvec_nomark:
4264  * 1. sg_init_table
4265  * 2. skb_to_sgvec_nomark(payload1)
4266  * 3. skb_to_sgvec_nomark(payload2)
4267  *
4268  * This is equivalent to:
4269  * 1. sg_init_table
4270  * 2. skb_to_sgvec(payload1)
4271  * 3. sg_unmark_end
4272  * 4. skb_to_sgvec(payload2)
4273  *
4274  * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
4275  * is more preferable.
4276  */
4277 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
4278                         int offset, int len)
4279 {
4280         return __skb_to_sgvec(skb, sg, offset, len, 0);
4281 }
4282 EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
4283 
4284 
4285 
4286 /**
4287  *      skb_cow_data - Check that a socket buffer's data buffers are writable
4288  *      @skb: The socket buffer to check.
4289  *      @tailbits: Amount of trailing space to be added
4290  *      @trailer: Returned pointer to the skb where the @tailbits space begins
4291  *
4292  *      Make sure that the data buffers attached to a socket buffer are
4293  *      writable. If they are not, private copies are made of the data buffers
4294  *      and the socket buffer is set to use these instead.
4295  *
4296  *      If @tailbits is given, make sure that there is space to write @tailbits
4297  *      bytes of data beyond current end of socket buffer.  @trailer will be
4298  *      set to point to the skb in which this space begins.
4299  *
4300  *      The number of scatterlist elements required to completely map the
4301  *      COW'd and extended socket buffer will be returned.
4302  */
4303 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
4304 {
4305         int copyflag;
4306         int elt;
4307         struct sk_buff *skb1, **skb_p;
4308 
4309         /* If skb is cloned or its head is paged, reallocate
4310          * head pulling out all the pages (pages are considered not writable
4311          * at the moment even if they are anonymous).
4312          */
4313         if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
4314             __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
4315                 return -ENOMEM;
4316 
4317         /* Easy case. Most of packets will go this way. */
4318         if (!skb_has_frag_list(skb)) {
4319                 /* A little of trouble, not enough of space for trailer.
4320                  * This should not happen, when stack is tuned to generate
4321                  * good frames. OK, on miss we reallocate and reserve even more
4322                  * space, 128 bytes is fair. */
4323 
4324                 if (skb_tailroom(skb) < tailbits &&
4325                     pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
4326                         return -ENOMEM;
4327 
4328                 /* Voila! */
4329                 *trailer = skb;
4330                 return 1;
4331         }
4332 
4333         /* Misery. We are in troubles, going to mincer fragments... */
4334 
4335         elt = 1;
4336         skb_p = &skb_shinfo(skb)->frag_list;
4337         copyflag = 0;
4338 
4339         while ((skb1 = *skb_p) != NULL) {
4340                 int ntail = 0;
4341 
4342                 /* The fragment is partially pulled by someone,
4343                  * this can happen on input. Copy it and everything
4344                  * after it. */
4345 
4346                 if (skb_shared(skb1))
4347                         copyflag = 1;
4348 
4349                 /* If the skb is the last, worry about trailer. */
4350 
4351                 if (skb1->next == NULL && tailbits) {
4352                         if (skb_shinfo(skb1)->nr_frags ||
4353                             skb_has_frag_list(skb1) ||
4354                             skb_tailroom(skb1) < tailbits)
4355                                 ntail = tailbits + 128;
4356                 }
4357 
4358                 if (copyflag ||
4359                     skb_cloned(skb1) ||
4360                     ntail ||
4361                     skb_shinfo(skb1)->nr_frags ||
4362                     skb_has_frag_list(skb1)) {
4363                         struct sk_buff *skb2;
4364 
4365                         /* Fuck, we are miserable poor guys... */
4366                         if (ntail == 0)
4367                                 skb2 = skb_copy(skb1, GFP_ATOMIC);
4368                         else
4369                                 skb2 = skb_copy_expand(skb1,
4370                                                        skb_headroom(skb1),
4371                                                        ntail,
4372                                                        GFP_ATOMIC);
4373                         if (unlikely(skb2 == NULL))
4374                                 return -ENOMEM;
4375 
4376                         if (skb1->sk)
4377                                 skb_set_owner_w(skb2, skb1->sk);
4378 
4379                         /* Looking around. Are we still alive?
4380                          * OK, link new skb, drop old one */
4381 
4382                         skb2->next = skb1->next;
4383                         *skb_p = skb2;
4384                         kfree_skb(skb1);
4385                         skb1 = skb2;
4386                 }
4387                 elt++;
4388                 *trailer = skb1;
4389                 skb_p = &skb1->next;
4390         }
4391 
4392         return elt;
4393 }
4394 EXPORT_SYMBOL_GPL(skb_cow_data);
4395 
4396 static void sock_rmem_free(struct sk_buff *skb)
4397 {
4398         struct sock *sk = skb->sk;
4399 
4400         atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
4401 }
4402 
4403 static void skb_set_err_queue(struct sk_buff *skb)
4404 {
4405         /* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
4406          * So, it is safe to (mis)use it to mark skbs on the error queue.
4407          */
4408         skb->pkt_type = PACKET_OUTGOING;
4409         BUILD_BUG_ON(PACKET_OUTGOING == 0);
4410 }
4411 
4412 /*
4413  * Note: We dont mem charge error packets (no sk_forward_alloc changes)
4414  */
4415 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
4416 {
4417         if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
4418             (unsigned int)READ_ONCE(sk->sk_rcvbuf))
4419                 return -ENOMEM;
4420 
4421         skb_orphan(skb);
4422         skb->sk = sk;
4423         skb->destructor = sock_rmem_free;
4424         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
4425         skb_set_err_queue(skb);
4426 
4427         /* before exiting rcu section, make sure dst is refcounted */
4428         skb_dst_force(skb);
4429 
4430         skb_queue_tail(&sk->sk_error_queue, skb);
4431         if (!sock_flag(sk, SOCK_DEAD))
4432                 sk->sk_error_report(sk);
4433         return 0;
4434 }
4435 EXPORT_SYMBOL(sock_queue_err_skb);
4436 
4437 static bool is_icmp_err_skb(const struct sk_buff *skb)
4438 {
4439         return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
4440                        SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6);
4441 }
4442 
4443 struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
4444 {
4445         struct sk_buff_head *q = &sk->sk_error_queue;
4446         struct sk_buff *skb, *skb_next = NULL;
4447         bool icmp_next = false;
4448         unsigned long flags;
4449 
4450         spin_lock_irqsave(&q->lock, flags);
4451         skb = __skb_dequeue(q);
4452         if (skb && (skb_next = skb_peek(q))) {
4453                 icmp_next = is_icmp_err_skb(skb_next);
4454                 if (icmp_next)
4455                         sk->sk_err = SKB_EXT_ERR(skb_next)->ee.ee_origin;
4456         }
4457         spin_unlock_irqrestore(&q->lock, flags);
4458 
4459         if (is_icmp_err_skb(skb) && !icmp_next)
4460                 sk->sk_err = 0;
4461 
4462         if (skb_next)
4463                 sk->sk_error_report(sk);
4464 
4465         return skb;
4466 }
4467 EXPORT_SYMBOL(sock_dequeue_err_skb);
4468 
4469 /**
4470  * skb_clone_sk - create clone of skb, and take reference to socket
4471  * @skb: the skb to clone
4472  *
4473  * This function creates a clone of a buffer that holds a reference on
4474  * sk_refcnt.  Buffers created via this function are meant to be
4475  * returned using sock_queue_err_skb, or free via kfree_skb.
4476  *
4477  * When passing buffers allocated with this function to sock_queue_err_skb
4478  * it is necessary to wrap the call with sock_hold/sock_put in order to
4479  * prevent the socket from being released prior to being enqueued on
4480  * the sk_error_queue.
4481  */
4482 struct sk_buff *skb_clone_sk(struct sk_buff *skb)
4483 {
4484         struct sock *sk = skb->sk;
4485         struct sk_buff *clone;
4486 
4487         if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
4488                 return NULL;
4489 
4490         clone = skb_clone(skb, GFP_ATOMIC);
4491         if (!clone) {
4492                 sock_put(sk);
4493                 return NULL;
4494         }
4495 
4496         clone->sk = sk;
4497         clone->destructor = sock_efree;
4498 
4499         return clone;
4500 }
4501 EXPORT_SYMBOL(skb_clone_sk);
4502 
4503 static void __skb_complete_tx_timestamp(struct sk_buff *skb,
4504                                         struct sock *sk,
4505                                         int tstype,
4506                                         bool opt_stats)
4507 {
4508         struct sock_exterr_skb *serr;
4509         int err;
4510 
4511         BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));
4512 
4513         serr = SKB_EXT_ERR(skb);
4514         memset(serr, 0, sizeof(*serr));
4515         serr->ee.ee_errno = ENOMSG;
4516         serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
4517         serr->ee.ee_info = tstype;
4518         serr->opt_stats = opt_stats;
4519         serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0;
4520         if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) {
4521                 serr->ee.ee_data = skb_shinfo(skb)->tskey;
4522                 if (sk->sk_protocol == IPPROTO_TCP &&
4523                     sk->sk_type == SOCK_STREAM)
4524                         serr->ee.ee_data -= sk->sk_tskey;
4525         }
4526 
4527         err = sock_queue_err_skb(sk, skb);
4528 
4529         if (err)
4530                 kfree_skb(skb);
4531 }
4532 
4533 static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
4534 {
4535         bool ret;
4536 
4537         if (likely(sysctl_tstamp_allow_data || tsonly))
4538                 return true;
4539 
4540         read_lock_bh(&sk->sk_callback_lock);
4541         ret = sk->sk_socket && sk->sk_socket->file &&
4542               file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
4543         read_unlock_bh(&sk->sk_callback_lock);
4544         return ret;
4545 }
4546 
4547 void skb_complete_tx_timestamp(struct sk_buff *skb,
4548                                struct skb_shared_hwtstamps *hwtstamps)
4549 {
4550         struct sock *sk = skb->sk;
4551 
4552         if (!skb_may_tx_timestamp(sk, false))
4553                 goto err;
4554 
4555         /* Take a reference to prevent skb_orphan() from freeing the socket,
4556          * but only if the socket refcount is not zero.
4557          */
4558         if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
4559                 *skb_hwtstamps(skb) = *hwtstamps;
4560                 __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
4561                 sock_put(sk);
4562                 return;
4563         }
4564 
4565 err:
4566         kfree_skb(skb);
4567 }
4568 EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
4569 
4570 void __skb_tstamp_tx(struct sk_buff *orig_skb,
4571                      struct skb_shared_hwtstamps *hwtstamps,
4572                      struct sock *sk, int tstype)
4573 {
4574         struct sk_buff *skb;
4575         bool tsonly, opt_stats = false;
4576 
4577         if (!sk)
4578                 return;
4579 
4580         if (!hwtstamps && !(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
4581             skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
4582                 return;
4583 
4584         tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
4585         if (!skb_may_tx_timestamp(sk, tsonly))
4586                 return;
4587 
4588         if (tsonly) {
4589 #ifdef CONFIG_INET
4590                 if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
4591                     sk->sk_protocol == IPPROTO_TCP &&
4592                     sk->sk_type == SOCK_STREAM) {
4593                         skb = tcp_get_timestamping_opt_stats(sk);
4594                         opt_stats = true;
4595                 } else
4596 #endif
4597                         skb = alloc_skb(0, GFP_ATOMIC);
4598         } else {
4599                 skb = skb_clone(orig_skb, GFP_ATOMIC);
4600         }
4601         if (!skb)
4602                 return;
4603 
4604         if (tsonly) {
4605                 skb_shinfo(skb)->tx_flags |= skb_shinfo(orig_skb)->tx_flags &
4606                                              SKBTX_ANY_TSTAMP;
4607                 skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
4608         }
4609 
4610         if (hwtstamps)
4611                 *skb_hwtstamps(skb) = *hwtstamps;
4612         else
4613                 skb->tstamp = ktime_get_real();
4614 
4615         __skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
4616 }
4617 EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
4618 
4619 void skb_tstamp_tx(struct sk_buff *orig_skb,
4620                    struct skb_shared_hwtstamps *hwtstamps)
4621 {
4622         return __skb_tstamp_tx(orig_skb, hwtstamps, orig_skb->sk,
4623                                SCM_TSTAMP_SND);
4624 }
4625 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
4626 
4627 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
4628 {
4629         struct sock *sk = skb->sk;
4630         struct sock_exterr_skb *serr;
4631         int err = 1;
4632 
4633         skb->wifi_acked_valid = 1;
4634         skb->wifi_acked = acked;
4635 
4636         serr = SKB_EXT_ERR(skb);
4637         memset(serr, 0, sizeof(*serr));
4638         serr->ee.ee_errno = ENOMSG;
4639         serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
4640 
4641         /* Take a reference to prevent skb_orphan() from freeing the socket,
4642          * but only if the socket refcount is not zero.
4643          */
4644         if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
4645                 err = sock_queue_err_skb(sk, skb);
4646                 sock_put(sk);
4647         }
4648         if (err)
4649                 kfree_skb(skb);
4650 }
4651 EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
4652 
4653 /**
4654  * skb_partial_csum_set - set up and verify partial csum values for packet
4655  * @skb: the skb to set
4656  * @start: the number of bytes after skb->data to start checksumming.
4657  * @off: the offset from start to place the checksum.
4658  *
4659  * For untrusted partially-checksummed packets, we need to make sure the values
4660  * for skb->csum_start and skb->csum_offset are valid so we don't oops.
4661  *
4662  * This function checks and sets those values and skb->ip_summed: if this
4663  * returns false you should drop the packet.
4664  */
4665 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
4666 {
4667         u32 csum_end = (u32)start + (u32)off + sizeof(__sum16);
4668         u32 csum_start = skb_headroom(skb) + (u32)start;
4669 
4670         if (unlikely(csum_start > U16_MAX || csum_end > skb_headlen(skb))) {
4671                 net_warn_ratelimited("bad partial csum: csum=%u/%u headroom=%u headlen=%u\n",
4672                                      start, off, skb_headroom(skb), skb_headlen(skb));
4673                 return false;
4674         }
4675         skb->ip_summed = CHECKSUM_PARTIAL;
4676         skb->csum_start = csum_start;
4677         skb->csum_offset = off;
4678         skb_set_transport_header(skb, start);
4679         return true;
4680 }
4681 EXPORT_SYMBOL_GPL(skb_partial_csum_set);
4682 
4683 static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
4684                                unsigned int max)
4685 {
4686         if (skb_headlen(skb) >= len)
4687                 return 0;
4688 
4689         /* If we need to pullup then pullup to the max, so we
4690          * won't need to do it again.
4691          */
4692         if (max > skb->len)
4693                 max = skb->len;
4694 
4695         if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
4696                 return -ENOMEM;
4697 
4698         if (skb_headlen(skb) < len)
4699                 return -EPROTO;
4700 
4701         return 0;
4702 }
4703 
4704 #define MAX_TCP_HDR_LEN (15 * 4)
4705 
4706 static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
4707                                       typeof(IPPROTO_IP) proto,
4708                                       unsigned int off)
4709 {
4710         switch (proto) {
4711                 int err;
4712 
4713         case IPPROTO_TCP:
4714                 err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
4715                                           off + MAX_TCP_HDR_LEN);
4716                 if (!err && !skb_partial_csum_set(skb, off,
4717                                                   offsetof(struct tcphdr,
4718                                                            check)))
4719                         err = -EPROTO;
4720                 return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
4721 
4722         case IPPROTO_UDP:
4723                 err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
4724                                           off + sizeof(struct udphdr));
4725                 if (!err && !skb_partial_csum_set(skb, off,
4726                                                   offsetof(struct udphdr,
4727                                                            check)))
4728                         err = -EPROTO;
4729                 return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
4730         }
4731 
4732         return ERR_PTR(-EPROTO);
4733 }
4734 
4735 /* This value should be large enough to cover a tagged ethernet header plus
4736  * maximally sized IP and TCP or UDP headers.
4737  */
4738 #define MAX_IP_HDR_LEN 128
4739 
4740 static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
4741 {
4742         unsigned int off;
4743         bool fragment;
4744         __sum16 *csum;
4745         int err;
4746 
4747         fragment = false;
4748 
4749         err = skb_maybe_pull_tail(skb,
4750                                   sizeof(struct iphdr),
4751                                   MAX_IP_HDR_LEN);
4752         if (err < 0)
4753                 goto out;
4754 
4755         if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
4756                 fragment = true;
4757 
4758         off = ip_hdrlen(skb);
4759 
4760         err = -EPROTO;
4761 
4762         if (fragment)
4763                 goto out;
4764 
4765         csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
4766         if (IS_ERR(csum))
4767                 return PTR_ERR(csum);
4768 
4769         if (recalculate)
4770                 *csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
4771                                            ip_hdr(skb)->daddr,
4772                                            skb->len - off,
4773                                            ip_hdr(skb)->protocol, 0);
4774         err = 0;
4775 
4776 out:
4777         return err;
4778 }
4779 
4780 /* This value should be large enough to cover a tagged ethernet header plus
4781  * an IPv6 header, all options, and a maximal TCP or UDP header.
4782  */
4783 #define MAX_IPV6_HDR_LEN 256
4784 
4785 #define OPT_HDR(type, skb, off) \
4786         (type *)(skb_network_header(skb) + (off))
4787 
4788 static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
4789 {
4790         int err;
4791         u8 nexthdr;
4792         unsigned int off;
4793         unsigned int len;
4794         bool fragment;
4795         bool done;
4796         __sum16 *csum;
4797 
4798         fragment = false;
4799         done = false;
4800 
4801         off = sizeof(struct ipv6hdr);
4802 
4803         err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
4804         if (err < 0)
4805                 goto out;
4806 
4807         nexthdr = ipv6_hdr(skb)->nexthdr;
4808 
4809         len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
4810         while (off <= len && !done) {
4811                 switch (nexthdr) {
4812                 case IPPROTO_DSTOPTS:
4813                 case IPPROTO_HOPOPTS:
4814                 case IPPROTO_ROUTING: {
4815                         struct ipv6_opt_hdr *hp;
4816 
4817                         err = skb_maybe_pull_tail(skb,
4818                                                   off +
4819                                                   sizeof(struct ipv6_opt_hdr),
4820                                                   MAX_IPV6_HDR_LEN);
4821                         if (err < 0)
4822                                 goto out;
4823 
4824                         hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
4825                         nexthdr = hp->nexthdr;
4826                         off += ipv6_optlen(hp);
4827                         break;
4828                 }
4829                 case IPPROTO_AH: {
4830                         struct ip_auth_hdr *hp;
4831 
4832                         err = skb_maybe_pull_tail(skb,
4833                                                   off +
4834                                                   sizeof(struct ip_auth_hdr),
4835                                                   MAX_IPV6_HDR_LEN);
4836                         if (err < 0)
4837                                 goto out;
4838 
4839                         hp = OPT_HDR(struct ip_auth_hdr, skb, off);
4840                         nexthdr = hp->nexthdr;
4841                         off += ipv6_authlen(hp);
4842                         break;
4843                 }
4844                 case IPPROTO_FRAGMENT: {
4845                         struct frag_hdr *hp;
4846 
4847                         err = skb_maybe_pull_tail(skb,
4848                                                   off +
4849                                                   sizeof(struct frag_hdr),
4850                                                   MAX_IPV6_HDR_LEN);
4851                         if (err < 0)
4852                                 goto out;
4853 
4854                         hp = OPT_HDR(struct frag_hdr, skb, off);
4855 
4856                         if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
4857                                 fragment = true;
4858 
4859                         nexthdr = hp->nexthdr;
4860                         off += sizeof(struct frag_hdr);
4861                         break;
4862                 }
4863                 default:
4864                         done = true;
4865                         break;
4866                 }
4867         }
4868 
4869         err = -EPROTO;
4870 
4871         if (!done || fragment)
4872                 goto out;
4873 
4874         csum = skb_checksum_setup_ip(skb, nexthdr, off);
4875         if (IS_ERR(csum))
4876                 return PTR_ERR(csum);
4877 
4878         if (recalculate)
4879                 *csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
4880                                          &ipv6_hdr(skb)->daddr,
4881                                          skb->len - off, nexthdr, 0);
4882         err = 0;
4883 
4884 out:
4885         return err;
4886 }
4887 
4888 /**
4889  * skb_checksum_setup - set up partial checksum offset
4890  * @skb: the skb to set up
4891  * @recalculate: if true the pseudo-header checksum will be recalculated
4892  */
4893 int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
4894 {
4895         int err;
4896 
4897         switch (skb->protocol) {
4898         case htons(ETH_P_IP):
4899                 err = skb_checksum_setup_ipv4(skb, recalculate);
4900                 break;
4901 
4902         case htons(ETH_P_IPV6):
4903                 err = skb_checksum_setup_ipv6(skb, recalculate);
4904                 break;
4905 
4906         default:
4907                 err = -EPROTO;
4908                 break;
4909         }
4910 
4911         return err;
4912 }
4913 EXPORT_SYMBOL(skb_checksum_setup);
4914 
4915 /**
4916  * skb_checksum_maybe_trim - maybe trims the given skb
4917  * @skb: the skb to check
4918  * @transport_len: the data length beyond the network header
4919  *
4920  * Checks whether the given skb has data beyond the given transport length.
4921  * If so, returns a cloned skb trimmed to this transport length.
4922  * Otherwise returns the provided skb. Returns NULL in error cases
4923  * (e.g. transport_len exceeds skb length or out-of-memory).
4924  *
4925  * Caller needs to set the skb transport header and free any returned skb if it
4926  * differs from the provided skb.
4927  */
4928 static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
4929                                                unsigned int transport_len)
4930 {
4931         struct sk_buff *skb_chk;
4932         unsigned int len = skb_transport_offset(skb) + transport_len;
4933         int ret;
4934 
4935         if (skb->len < len)
4936                 return NULL;
4937         else if (skb->len == len)
4938                 return skb;
4939 
4940         skb_chk = skb_clone(skb, GFP_ATOMIC);
4941         if (!skb_chk)
4942                 return NULL;
4943 
4944         ret = pskb_trim_rcsum(skb_chk, len);
4945         if (ret) {
4946                 kfree_skb(skb_chk);
4947                 return NULL;
4948         }
4949 
4950         return skb_chk;
4951 }
4952 
4953 /**
4954  * skb_checksum_trimmed - validate checksum of an skb
4955  * @skb: the skb to check
4956  * @transport_len: the data length beyond the network header
4957  * @skb_chkf: checksum function to use
4958  *
4959  * Applies the given checksum function skb_chkf to the provided skb.
4960  * Returns a checked and maybe trimmed skb. Returns NULL on error.
4961  *
4962  * If the skb has data beyond the given transport length, then a
4963  * trimmed & cloned skb is checked and returned.
4964  *
4965  * Caller needs to set the skb transport header and free any returned skb if it
4966  * differs from the provided skb.
4967  */
4968 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
4969                                      unsigned int transport_len,
4970                                      __sum16(*skb_chkf)(struct sk_buff *skb))
4971 {
4972         struct sk_buff *skb_chk;
4973         unsigned int offset = skb_transport_offset(skb);
4974         __sum16 ret;
4975 
4976         skb_chk = skb_checksum_maybe_trim(skb, transport_len);
4977         if (!skb_chk)
4978                 goto err;
4979 
4980         if (!pskb_may_pull(skb_chk, offset))
4981                 goto err;
4982 
4983         skb_pull_rcsum(skb_chk, offset);
4984         ret = skb_chkf(skb_chk);
4985         skb_push_rcsum(skb_chk, offset);
4986 
4987         if (ret)
4988                 goto err;
4989 
4990         return skb_chk;
4991 
4992 err:
4993         if (skb_chk && skb_chk != skb)
4994                 kfree_skb(skb_chk);
4995 
4996         return NULL;
4997 
4998 }
4999 EXPORT_SYMBOL(skb_checksum_trimmed);
5000 
5001 void __skb_warn_lro_forwarding(const struct sk_buff *skb)
5002 {
5003         net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
5004                              skb->dev->name);
5005 }
5006 EXPORT_SYMBOL(__skb_warn_lro_forwarding);
5007 
5008 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
5009 {
5010         if (head_stolen) {
5011                 skb_release_head_state(skb);
5012                 kmem_cache_free(skbuff_head_cache, skb);
5013         } else {
5014                 __kfree_skb(skb);
5015         }
5016 }
5017 EXPORT_SYMBOL(kfree_skb_partial);
5018 
5019 /**
5020  * skb_try_coalesce - try to merge skb to prior one
5021  * @to: prior buffer
5022  * @from: buffer to add
5023  * @fragstolen: pointer to boolean
5024  * @delta_truesize: how much more was allocated than was requested
5025  */
5026 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
5027                       bool *fragstolen, int *delta_truesize)
5028 {
5029         struct skb_shared_info *to_shinfo, *from_shinfo;
5030         int i, delta, len = from->len;
5031 
5032         *fragstolen = false;
5033 
5034         if (skb_cloned(to))
5035                 return false;
5036 
5037         if (len <= skb_tailroom(to)) {
5038                 if (len)
5039                         BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
5040                 *delta_truesize = 0;
5041                 return true;
5042         }
5043 
5044         to_shinfo = skb_shinfo(to);
5045         from_shinfo = skb_shinfo(from);
5046         if (to_shinfo->frag_list || from_shinfo->frag_list)
5047                 return false;
5048         if (skb_zcopy(to) || skb_zcopy(from))
5049                 return false;
5050 
5051         if (skb_headlen(from) != 0) {
5052                 struct page *page;
5053                 unsigned int offset;
5054 
5055                 if (to_shinfo->nr_frags +
5056                     from_shinfo->nr_frags >= MAX_SKB_FRAGS)
5057                         return false;
5058 
5059                 if (skb_head_is_locked(from))
5060                         return false;
5061 
5062                 delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
5063 
5064                 page = virt_to_head_page(from->head);
5065                 offset = from->data - (unsigned char *)page_address(page);
5066 
5067                 skb_fill_page_desc(to, to_shinfo->nr_frags,
5068                                    page, offset, skb_headlen(from));
5069                 *fragstolen = true;
5070         } else {
5071                 if (to_shinfo->nr_frags +
5072                     from_shinfo->nr_frags > MAX_SKB_FRAGS)
5073                         return false;
5074 
5075                 delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
5076         }
5077 
5078         WARN_ON_ONCE(delta < len);
5079 
5080         memcpy(to_shinfo->frags + to_shinfo->nr_frags,
5081                from_shinfo->frags,
5082                from_shinfo->nr_frags * sizeof(skb_frag_t));
5083         to_shinfo->nr_frags += from_shinfo->nr_frags;
5084 
5085         if (!skb_cloned(from))
5086                 from_shinfo->nr_frags = 0;
5087 
5088         /* if the skb is not cloned this does nothing
5089          * since we set nr_frags to 0.
5090          */
5091         for (i = 0; i < from_shinfo->nr_frags; i++)
5092                 __skb_frag_ref(&from_shinfo->frags[i]);
5093 
5094         to->truesize += delta;
5095         to->len += len;
5096         to->data_len += len;
5097 
5098         *delta_truesize = delta;
5099         return true;
5100 }
5101 EXPORT_SYMBOL(skb_try_coalesce);
5102 
5103 /**
5104  * skb_scrub_packet - scrub an skb
5105  *
5106  * @skb: buffer to clean
5107  * @xnet: packet is crossing netns
5108  *
5109  * skb_scrub_packet can be used after encapsulating or decapsulting a packet
5110  * into/from a tunnel. Some information have to be cleared during these
5111  * operations.
5112  * skb_scrub_packet can also be used to clean a skb before injecting it in
5113  * another namespace (@xnet == true). We have to clear all information in the
5114  * skb that could impact namespace isolation.
5115  */
5116 void skb_scrub_packet(struct sk_buff *skb, bool xnet)
5117 {
5118         skb->pkt_type = PACKET_HOST;
5119         skb->skb_iif = 0;
5120         skb->ignore_df = 0;
5121         skb_dst_drop(skb);
5122         skb_ext_reset(skb);
5123         nf_reset_ct(skb);
5124         nf_reset_trace(skb);
5125 
5126 #ifdef CONFIG_NET_SWITCHDEV
5127         skb->offload_fwd_mark = 0;
5128         skb->offload_l3_fwd_mark = 0;
5129 #endif
5130 
5131         if (!xnet)
5132                 return;
5133 
5134         ipvs_reset(skb);
5135         skb->mark = 0;
5136         skb->tstamp = 0;
5137 }
5138 EXPORT_SYMBOL_GPL(skb_scrub_packet);
5139 
5140 /**
5141  * skb_gso_transport_seglen - Return length of individual segments of a gso packet
5142  *
5143  * @skb: GSO skb
5144  *
5145  * skb_gso_transport_seglen is used to determine the real size of the
5146  * individual segments, including Layer4 headers (TCP/UDP).
5147  *
5148  * The MAC/L2 or network (IP, IPv6) headers are not accounted for.
5149  */
5150 static unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
5151 {
5152         const struct skb_shared_info *shinfo = skb_shinfo(skb);
5153         unsigned int thlen = 0;
5154 
5155         if (skb->encapsulation) {
5156                 thlen = skb_inner_transport_header(skb) -
5157                         skb_transport_header(skb);
5158 
5159                 if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
5160                         thlen += inner_tcp_hdrlen(skb);
5161         } else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
5162                 thlen = tcp_hdrlen(skb);
5163         } else if (unlikely(skb_is_gso_sctp(skb))) {
5164                 thlen = sizeof(struct sctphdr);
5165         } else if (shinfo->gso_type & SKB_GSO_UDP_L4) {
5166                 thlen = sizeof(struct udphdr);
5167         }
5168         /* UFO sets gso_size to the size of the fragmentation
5169          * payload, i.e. the size of the L4 (UDP) header is already
5170          * accounted for.
5171          */
5172         return thlen + shinfo->gso_size;
5173 }
5174 
5175 /**
5176  * skb_gso_network_seglen - Return length of individual segments of a gso packet
5177  *
5178  * @skb: GSO skb
5179  *
5180  * skb_gso_network_seglen is used to determine the real size of the
5181  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
5182  *
5183  * The MAC/L2 header is not accounted for.
5184  */
5185 static unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
5186 {
5187         unsigned int hdr_len = skb_transport_header(skb) -
5188                                skb_network_header(skb);
5189 
5190         return hdr_len + skb_gso_transport_seglen(skb);
5191 }
5192 
5193 /**
5194  * skb_gso_mac_seglen - Return length of individual segments of a gso packet
5195  *
5196  * @skb: GSO skb
5197  *
5198  * skb_gso_mac_seglen is used to determine the real size of the
5199  * individual segments, including MAC/L2, Layer3 (IP, IPv6) and L4
5200  * headers (TCP/UDP).
5201  */
5202 static unsigned int skb_gso_mac_seglen(const struct sk_buff *skb)
5203 {
5204         unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
5205 
5206         return hdr_len + skb_gso_transport_seglen(skb);
5207 }
5208 
5209 /**
5210  * skb_gso_size_check - check the skb size, considering GSO_BY_FRAGS
5211  *
5212  * There are a couple of instances where we have a GSO skb, and we
5213  * want to determine what size it would be after it is segmented.
5214  *
5215  * We might want to check:
5216  * -    L3+L4+payload size (e.g. IP forwarding)
5217  * - L2+L3+L4+payload size (e.g. sanity check before passing to driver)
5218  *
5219  * This is a helper to do that correctly considering GSO_BY_FRAGS.
5220  *
5221  * @skb: GSO skb
5222  *
5223  * @seg_len: The segmented length (from skb_gso_*_seglen). In the
5224  *           GSO_BY_FRAGS case this will be [header sizes + GSO_BY_FRAGS].
5225  *
5226  * @max_len: The maximum permissible length.
5227  *
5228  * Returns true if the segmented length <= max length.
5229  */
5230 static inline bool skb_gso_size_check(const struct sk_buff *skb,
5231                                       unsigned int seg_len,
5232                                       unsigned int max_len) {
5233         const struct skb_shared_info *shinfo = skb_shinfo(skb);
5234         const struct sk_buff *iter;
5235 
5236         if (shinfo->gso_size != GSO_BY_FRAGS)
5237                 return seg_len <= max_len;
5238 
5239         /* Undo this so we can re-use header sizes */
5240         seg_len -= GSO_BY_FRAGS;
5241 
5242         skb_walk_frags(skb, iter) {
5243                 if (seg_len + skb_headlen(iter) > max_len)
5244                         return false;
5245         }
5246 
5247         return true;
5248 }
5249 
5250 /**
5251  * skb_gso_validate_network_len - Will a split GSO skb fit into a given MTU?
5252  *
5253  * @skb: GSO skb
5254  * @mtu: MTU to validate against
5255  *
5256  * skb_gso_validate_network_len validates if a given skb will fit a
5257  * wanted MTU once split. It considers L3 headers, L4 headers, and the
5258  * payload.
5259  */
5260 bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu)
5261 {
5262         return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu);
5263 }
5264 EXPORT_SYMBOL_GPL(skb_gso_validate_network_len);
5265 
5266 /**
5267  * skb_gso_validate_mac_len - Will a split GSO skb fit in a given length?
5268  *
5269  * @skb: GSO skb
5270  * @len: length to validate against
5271  *
5272  * skb_gso_validate_mac_len validates if a given skb will fit a wanted
5273  * length once split, including L2, L3 and L4 headers and the payload.
5274  */
5275 bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len)
5276 {
5277         return skb_gso_size_check(skb, skb_gso_mac_seglen(skb), len);
5278 }
5279 EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len);
5280 
5281 static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
5282 {
5283         int mac_len, meta_len;
5284         void *meta;
5285 
5286         if (skb_cow(skb, skb_headroom(skb)) < 0) {
5287                 kfree_skb(skb);
5288                 return NULL;
5289         }
5290 
5291         mac_len = skb->data - skb_mac_header(skb);
5292         if (likely(mac_len > VLAN_HLEN + ETH_TLEN)) {
5293                 memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
5294                         mac_len - VLAN_HLEN - ETH_TLEN);
5295         }
5296 
5297         meta_len = skb_metadata_len(skb);
5298         if (meta_len) {
5299                 meta = skb_metadata_end(skb) - meta_len;
5300                 memmove(meta + VLAN_HLEN, meta, meta_len);
5301         }
5302 
5303         skb->mac_header += VLAN_HLEN;
5304         return skb;
5305 }
5306 
5307 struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
5308 {
5309         struct vlan_hdr *vhdr;
5310         u16 vlan_tci;
5311 
5312         if (unlikely(skb_vlan_tag_present(skb))) {
5313                 /* vlan_tci is already set-up so leave this for another time */
5314                 return skb;
5315         }
5316 
5317         skb = skb_share_check(skb, GFP_ATOMIC);
5318         if (unlikely(!skb))
5319                 goto err_free;
5320 
5321         if (unlikely(!pskb_may_pull(skb, VLAN_HLEN)))
5322                 goto err_free;
5323 
5324         vhdr = (struct vlan_hdr *)skb->data;
5325         vlan_tci = ntohs(vhdr->h_vlan_TCI);
5326         __vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
5327 
5328         skb_pull_rcsum(skb, VLAN_HLEN);
5329         vlan_set_encap_proto(skb, vhdr);
5330 
5331         skb = skb_reorder_vlan_header(skb);
5332         if (unlikely(!skb))
5333                 goto err_free;
5334 
5335         skb_reset_network_header(skb);
5336         skb_reset_transport_header(skb);
5337         skb_reset_mac_len(skb);
5338 
5339         return skb;
5340 
5341 err_free:
5342         kfree_skb(skb);
5343         return NULL;
5344 }
5345 EXPORT_SYMBOL(skb_vlan_untag);
5346 
5347 int skb_ensure_writable(struct sk_buff *skb, int write_len)
5348 {
5349         if (!pskb_may_pull(skb, write_len))
5350                 return -ENOMEM;
5351 
5352         if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
5353                 return 0;
5354 
5355         return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
5356 }
5357 EXPORT_SYMBOL(skb_ensure_writable);
5358 
5359 /* remove VLAN header from packet and update csum accordingly.
5360  * expects a non skb_vlan_tag_present skb with a vlan tag payload
5361  */
5362 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
5363 {
5364         struct vlan_hdr *vhdr;
5365         int offset = skb->data - skb_mac_header(skb);
5366         int err;
5367 
5368         if (WARN_ONCE(offset,
5369                       "__skb_vlan_pop got skb with skb->data not at mac header (offset %d)\n",
5370                       offset)) {
5371                 return -EINVAL;
5372         }
5373 
5374         err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
5375         if (unlikely(err))
5376                 return err;
5377 
5378         skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
5379 
5380         vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
5381         *vlan_tci = ntohs(vhdr->h_vlan_TCI);
5382 
5383         memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
5384         __skb_pull(skb, VLAN_HLEN);
5385 
5386         vlan_set_encap_proto(skb, vhdr);
5387         skb->mac_header += VLAN_HLEN;
5388 
5389         if (skb_network_offset(skb) < ETH_HLEN)
5390                 skb_set_network_header(skb, ETH_HLEN);
5391 
5392         skb_reset_mac_len(skb);
5393 
5394         return err;
5395 }
5396 EXPORT_SYMBOL(__skb_vlan_pop);
5397 
5398 /* Pop a vlan tag either from hwaccel or from payload.
5399  * Expects skb->data at mac header.
5400  */
5401 int skb_vlan_pop(struct sk_buff *skb)
5402 {
5403         u16 vlan_tci;
5404         __be16 vlan_proto;
5405         int err;
5406 
5407         if (likely(skb_vlan_tag_present(skb))) {
5408                 __vlan_hwaccel_clear_tag(skb);
5409         } else {
5410                 if (unlikely(!eth_type_vlan(skb->protocol)))
5411                         return 0;
5412 
5413                 err = __skb_vlan_pop(skb, &vlan_tci);
5414                 if (err)
5415                         return err;
5416         }
5417         /* move next vlan tag to hw accel tag */
5418         if (likely(!eth_type_vlan(skb->protocol)))
5419                 return 0;
5420 
5421         vlan_proto = skb->protocol;
5422         err = __skb_vlan_pop(skb, &vlan_tci);
5423         if (unlikely(err))
5424                 return err;
5425 
5426         __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
5427         return 0;
5428 }
5429 EXPORT_SYMBOL(skb_vlan_pop);
5430 
5431 /* Push a vlan tag either into hwaccel or into payload (if hwaccel tag present).
5432  * Expects skb->data at mac header.
5433  */
5434 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
5435 {
5436         if (skb_vlan_tag_present(skb)) {
5437                 int offset = skb->data - skb_mac_header(skb);
5438                 int err;
5439 
5440                 if (WARN_ONCE(offset,
5441                               "skb_vlan_push got skb with skb->data not at mac header (offset %d)\n",
5442                               offset)) {
5443                         return -EINVAL;
5444                 }
5445 
5446                 err = __vlan_insert_tag(skb, skb->vlan_proto,
5447                                         skb_vlan_tag_get(skb));
5448                 if (err)
5449                         return err;
5450 
5451                 skb->protocol = skb->vlan_proto;
5452                 skb->mac_len += VLAN_HLEN;
5453 
5454                 skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
5455         }
5456         __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
5457         return 0;
5458 }
5459 EXPORT_SYMBOL(skb_vlan_push);
5460 
5461 /* Update the ethertype of hdr and the skb csum value if required. */
5462 static void skb_mod_eth_type(struct sk_buff *skb, struct ethhdr *hdr,
5463                              __be16 ethertype)
5464 {
5465         if (skb->ip_summed == CHECKSUM_COMPLETE) {
5466                 __be16 diff[] = { ~hdr->h_proto, ethertype };
5467 
5468                 skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
5469         }
5470 
5471         hdr->h_proto = ethertype;
5472 }
5473 
5474 /**
5475  * skb_mpls_push() - push a new MPLS header after the mac header
5476  *
5477  * @skb: buffer
5478  * @mpls_lse: MPLS label stack entry to push
5479  * @mpls_proto: ethertype of the new MPLS header (expects 0x8847 or 0x8848)
5480  * @mac_len: length of the MAC header
5481  *
5482  * Expects skb->data at mac header.
5483  *
5484  * Returns 0 on success, -errno otherwise.
5485  */
5486 int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
5487                   int mac_len, bool ethernet)
5488 {
5489         struct mpls_shim_hdr *lse;
5490         int err;
5491 
5492         if (unlikely(!eth_p_mpls(mpls_proto)))
5493                 return -EINVAL;
5494 
5495         /* Networking stack does not allow simultaneous Tunnel and MPLS GSO. */
5496         if (skb->encapsulation)
5497                 return -EINVAL;
5498 
5499         err = skb_cow_head(skb, MPLS_HLEN);
5500         if (unlikely(err))
5501                 return err;
5502 
5503         if (!skb->inner_protocol) {
5504                 skb_set_inner_network_header(skb, mac_len);
5505                 skb_set_inner_protocol(skb, skb->protocol);
5506         }
5507 
5508         skb_push(skb, MPLS_HLEN);
5509         memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
5510                 mac_len);
5511         skb_reset_mac_header(skb);
5512         skb_set_network_header(skb, mac_len);
5513 
5514         lse = mpls_hdr(skb);
5515         lse->label_stack_entry = mpls_lse;
5516         skb_postpush_rcsum(skb, lse, MPLS_HLEN);
5517 
5518         if (ethernet)
5519                 skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
5520         skb->protocol = mpls_proto;
5521 
5522         return 0;
5523 }
5524 EXPORT_SYMBOL_GPL(skb_mpls_push);
5525 
5526 /**
5527  * skb_mpls_pop() - pop the outermost MPLS header
5528  *
5529  * @skb: buffer
5530  * @next_proto: ethertype of header after popped MPLS header
5531  * @mac_len: length of the MAC header
5532  * @ethernet: flag to indicate if ethernet header is present in packet
5533  *
5534  * Expects skb->data at mac header.
5535  *
5536  * Returns 0 on success, -errno otherwise.
5537  */
5538 int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
5539                  bool ethernet)
5540 {
5541         int err;
5542 
5543         if (unlikely(!eth_p_mpls(skb->protocol)))
5544                 return 0;
5545 
5546         err = skb_ensure_writable(skb, mac_len + MPLS_HLEN);
5547         if (unlikely(err))
5548                 return err;
5549 
5550         skb_postpull_rcsum(skb, mpls_hdr(skb), MPLS_HLEN);
5551         memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
5552                 mac_len);
5553 
5554         __skb_pull(skb, MPLS_HLEN);
5555         skb_reset_mac_header(skb);
5556         skb_set_network_header(skb, mac_len);
5557 
5558         if (ethernet) {
5559                 struct ethhdr *hdr;
5560 
5561                 /* use mpls_hdr() to get ethertype to account for VLANs. */
5562                 hdr = (struct ethhdr *)((void *)mpls_hdr(skb) - ETH_HLEN);
5563                 skb_mod_eth_type(skb, hdr, next_proto);
5564         }
5565         skb->protocol = next_proto;
5566 
5567         return 0;
5568 }
5569 EXPORT_SYMBOL_GPL(skb_mpls_pop);
5570 
5571 /**
5572  * skb_mpls_update_lse() - modify outermost MPLS header and update csum
5573  *
5574  * @skb: buffer
5575  * @mpls_lse: new MPLS label stack entry to update to
5576  *
5577  * Expects skb->data at mac header.
5578  *
5579  * Returns 0 on success, -errno otherwise.
5580  */
5581 int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse)
5582 {
5583         int err;
5584 
5585         if (unlikely(!eth_p_mpls(skb->protocol)))
5586                 return -EINVAL;
5587 
5588         err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
5589         if (unlikely(err))
5590                 return err;
5591 
5592         if (skb->ip_summed == CHECKSUM_COMPLETE) {
5593                 __be32 diff[] = { ~mpls_hdr(skb)->label_stack_entry, mpls_lse };
5594 
5595                 skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
5596         }
5597 
5598         mpls_hdr(skb)->label_stack_entry = mpls_lse;
5599 
5600         return 0;
5601 }
5602 EXPORT_SYMBOL_GPL(skb_mpls_update_lse);
5603 
5604 /**
5605  * skb_mpls_dec_ttl() - decrement the TTL of the outermost MPLS header
5606  *
5607  * @skb: buffer
5608  *
5609  * Expects skb->data at mac header.
5610  *
5611  * Returns 0 on success, -errno otherwise.
5612  */
5613 int skb_mpls_dec_ttl(struct sk_buff *skb)
5614 {
5615         u32 lse;
5616         u8 ttl;
5617 
5618         if (unlikely(!eth_p_mpls(skb->protocol)))
5619                 return -EINVAL;
5620 
5621         lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry);
5622         ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
5623         if (!--ttl)
5624                 return -EINVAL;
5625 
5626         lse &= ~MPLS_LS_TTL_MASK;
5627         lse |= ttl << MPLS_LS_TTL_SHIFT;
5628 
5629         return skb_mpls_update_lse(skb, cpu_to_be32(lse));
5630 }
5631 EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl);
5632 
5633 /**
5634  * alloc_skb_with_frags - allocate skb with page frags
5635  *
5636  * @header_len: size of linear part
5637  * @data_len: needed length in frags
5638  * @max_page_order: max page order desired.
5639  * @errcode: pointer to error code if any
5640  * @gfp_mask: allocation mask
5641  *
5642  * This can be used to allocate a paged skb, given a maximal order for frags.
5643  */
5644 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
5645                                      unsigned long data_len,
5646                                      int max_page_order,
5647                                      int *errcode,
5648                                      gfp_t gfp_mask)
5649 {
5650         int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
5651         unsigned long chunk;
5652         struct sk_buff *skb;
5653         struct page *page;
5654         int i;
5655 
5656         *errcode = -EMSGSIZE;
5657         /* Note this test could be relaxed, if we succeed to allocate
5658          * high order pages...
5659          */
5660         if (npages > MAX_SKB_FRAGS)
5661                 return NULL;
5662 
5663         *errcode = -ENOBUFS;
5664         skb = alloc_skb(header_len, gfp_mask);
5665         if (!skb)
5666                 return NULL;
5667 
5668         skb->truesize += npages << PAGE_SHIFT;
5669 
5670         for (i = 0; npages > 0; i++) {
5671                 int order = max_page_order;
5672 
5673                 while (order) {
5674                         if (npages >= 1 << order) {
5675                                 page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
5676                                                    __GFP_COMP |
5677                                                    __GFP_NOWARN,
5678                                                    order);
5679                                 if (page)
5680                                         goto fill_page;
5681                                 /* Do not retry other high order allocations */
5682                                 order = 1;
5683                                 max_page_order = 0;
5684                         }
5685                         order--;
5686                 }
5687                 page = alloc_page(gfp_mask);
5688                 if (!page)
5689                         goto failure;
5690 fill_page:
5691                 chunk = min_t(unsigned long, data_len,
5692                               PAGE_SIZE << order);
5693                 skb_fill_page_desc(skb, i, page, 0, chunk);
5694                 data_len -= chunk;
5695                 npages -= 1 << order;
5696         }
5697         return skb;
5698 
5699 failure:
5700         kfree_skb(skb);
5701         return NULL;
5702 }
5703 EXPORT_SYMBOL(alloc_skb_with_frags);
5704 
5705 /* carve out the first off bytes from skb when off < headlen */
5706 static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
5707                                     const int headlen, gfp_t gfp_mask)
5708 {
5709         int i;
5710         int size = skb_end_offset(skb);
5711         int new_hlen = headlen - off;
5712         u8 *data;
5713 
5714         size = SKB_DATA_ALIGN(size);
5715 
5716         if (skb_pfmemalloc(skb))
5717                 gfp_mask |= __GFP_MEMALLOC;
5718         data = kmalloc_reserve(size +
5719                                SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
5720                                gfp_mask, NUMA_NO_NODE, NULL);
5721         if (!data)
5722                 return -ENOMEM;
5723 
5724         size = SKB_WITH_OVERHEAD(ksize(data));
5725 
5726         /* Copy real data, and all frags */
5727         skb_copy_from_linear_data_offset(skb, off, data, new_hlen);
5728         skb->len -= off;
5729 
5730         memcpy((struct skb_shared_info *)(data + size),
5731                skb_shinfo(skb),
5732                offsetof(struct skb_shared_info,
5733                         frags[skb_shinfo(skb)->nr_frags]));
5734         if (skb_cloned(skb)) {
5735                 /* drop the old head gracefully */
5736                 if (skb_orphan_frags(skb, gfp_mask)) {
5737                         kfree(data);
5738                         return -ENOMEM;
5739                 }
5740                 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
5741                         skb_frag_ref(skb, i);
5742                 if (skb_has_frag_list(skb))
5743                         skb_clone_fraglist(skb);
5744                 skb_release_data(skb);
5745         } else {
5746                 /* we can reuse existing recount- all we did was
5747                  * relocate values
5748                  */
5749                 skb_free_head(skb);
5750         }
5751 
5752         skb->head = data;
5753         skb->data = data;
5754         skb->head_frag = 0;
5755 #ifdef NET_SKBUFF_DATA_USES_OFFSET
5756         skb->end = size;
5757 #else
5758         skb->end = skb->head + size;
5759 #endif
5760         skb_set_tail_pointer(skb, skb_headlen(skb));
5761         skb_headers_offset_update(skb, 0);
5762         skb->cloned = 0;
5763         skb->hdr_len = 0;
5764         skb->nohdr = 0;
5765         atomic_set(&skb_shinfo(skb)->dataref, 1);
5766 
5767         return 0;
5768 }
5769 
5770 static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
5771 
5772 /* carve out the first eat bytes from skb's frag_list. May recurse into
5773  * pskb_carve()
5774  */
5775 static int pskb_carve_frag_list(struct sk_buff *skb,
5776                                 struct skb_shared_info *shinfo, int eat,
5777                                 gfp_t gfp_mask)
5778 {
5779         struct sk_buff *list = shinfo->frag_list;
5780         struct sk_buff *clone = NULL;
5781         struct sk_buff *insp = NULL;
5782 
5783         do {
5784                 if (!list) {
5785                         pr_err("Not enough bytes to eat. Want %d\n", eat);
5786                         return -EFAULT;
5787                 }
5788                 if (list->len <= eat) {
5789                         /* Eaten as whole. */
5790                         eat -= list->len;
5791                         list = list->next;
5792                         insp = list;
5793                 } else {
5794                         /* Eaten partially. */
5795                         if (skb_shared(list)) {
5796                                 clone = skb_clone(list, gfp_mask);
5797                                 if (!clone)
5798                                         return -ENOMEM;
5799                                 insp = list->next;
5800                                 list = clone;
5801                         } else {
5802                                 /* This may be pulled without problems. */
5803                                 insp = list;
5804                         }
5805                         if (pskb_carve(list, eat, gfp_mask) < 0) {
5806                                 kfree_skb(clone);
5807                                 return -ENOMEM;
5808                         }
5809                         break;
5810                 }
5811         } while (eat);
5812 
5813         /* Free pulled out fragments. */
5814         while ((list = shinfo->frag_list) != insp) {
5815                 shinfo->frag_list = list->next;
5816                 kfree_skb(list);
5817         }
5818         /* And insert new clone at head. */
5819         if (clone) {
5820                 clone->next = list;
5821                 shinfo->frag_list = clone;
5822         }
5823         return 0;
5824 }
5825 
5826 /* carve off first len bytes from skb. Split line (off) is in the
5827  * non-linear part of skb
5828  */
5829 static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
5830                                        int pos, gfp_t gfp_mask)
5831 {
5832         int i, k = 0;
5833         int size = skb_end_offset(skb);
5834         u8 *data;
5835         const int nfrags = skb_shinfo(skb)->nr_frags;
5836         struct skb_shared_info *shinfo;
5837 
5838         size = SKB_DATA_ALIGN(size);
5839 
5840         if (skb_pfmemalloc(skb))
5841                 gfp_mask |= __GFP_MEMALLOC;
5842         data = kmalloc_reserve(size +
5843                                SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
5844                                gfp_mask, NUMA_NO_NODE, NULL);
5845         if (!data)
5846                 return -ENOMEM;
5847 
5848         size = SKB_WITH_OVERHEAD(ksize(data));
5849 
5850         memcpy((struct skb_shared_info *)(data + size),
5851                skb_shinfo(skb), offsetof(struct skb_shared_info,
5852                                          frags[skb_shinfo(skb)->nr_frags]));
5853         if (skb_orphan_frags(skb, gfp_mask)) {
5854                 kfree(data);
5855                 return -ENOMEM;
5856         }
5857         shinfo = (struct skb_shared_info *)(data + size);
5858         for (i = 0; i < nfrags; i++) {
5859                 int fsize = skb_frag_size(&skb_shinfo(skb)->frags[i]);
5860 
5861                 if (pos + fsize > off) {
5862                         shinfo->frags[k] = skb_shinfo(skb)->frags[i];
5863 
5864                         if (pos < off) {
5865                                 /* Split frag.
5866                                  * We have two variants in this case:
5867                                  * 1. Move all the frag to the second
5868                                  *    part, if it is possible. F.e.
5869                                  *    this approach is mandatory for TUX,
5870                                  *    where splitting is expensive.
5871                                  * 2. Split is accurately. We make this.
5872                                  */
5873                                 skb_frag_off_add(&shinfo->frags[0], off - pos);
5874                                 skb_frag_size_sub(&shinfo->frags[0], off - pos);
5875                         }
5876                         skb_frag_ref(skb, i);
5877                         k++;
5878                 }
5879                 pos += fsize;
5880         }
5881         shinfo->nr_frags = k;
5882         if (skb_has_frag_list(skb))
5883                 skb_clone_fraglist(skb);
5884 
5885         if (k == 0) {
5886                 /* split line is in frag list */
5887                 pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask);
5888         }
5889         skb_release_data(skb);
5890 
5891         skb->head = data;
5892         skb->head_frag = 0;
5893         skb->data = data;
5894 #ifdef NET_SKBUFF_DATA_USES_OFFSET
5895         skb->end = size;
5896 #else
5897         skb->end = skb->head + size;
5898 #endif
5899         skb_reset_tail_pointer(skb);
5900         skb_headers_offset_update(skb, 0);
5901         skb->cloned   = 0;
5902         skb->hdr_len  = 0;
5903         skb->nohdr    = 0;
5904         skb->len -= off;
5905         skb->data_len = skb->len;
5906         atomic_set(&skb_shinfo(skb)->dataref, 1);
5907         return 0;
5908 }
5909 
5910 /* remove len bytes from the beginning of the skb */
5911 static int pskb_carve(struct sk_buff *skb, const u32 len, gfp_t gfp)
5912 {
5913         int headlen = skb_headlen(skb);
5914 
5915         if (len < headlen)
5916                 return pskb_carve_inside_header(skb, len, headlen, gfp);
5917         else
5918                 return pskb_carve_inside_nonlinear(skb, len, headlen, gfp);
5919 }
5920 
5921 /* Extract to_copy bytes starting at off from skb, and return this in
5922  * a new skb
5923  */
5924 struct sk_buff *pskb_extract(struct sk_buff *skb, int off,
5925                              int to_copy, gfp_t gfp)
5926 {
5927         struct sk_buff  *clone = skb_clone(skb, gfp);
5928 
5929         if (!clone)
5930                 return NULL;
5931 
5932         if (pskb_carve(clone, off, gfp) < 0 ||
5933             pskb_trim(clone, to_copy)) {
5934                 kfree_skb(clone);
5935                 return NULL;
5936         }
5937         return clone;
5938 }
5939 EXPORT_SYMBOL(pskb_extract);
5940 
5941 /**
5942  * skb_condense - try to get rid of fragments/frag_list if possible
5943  * @skb: buffer
5944  *
5945  * Can be used to save memory before skb is added to a busy queue.
5946  * If packet has bytes in frags and enough tail room in skb->head,
5947  * pull all of them, so that we can free the frags right now and adjust
5948  * truesize.
5949  * Notes:
5950  *      We do not reallocate skb->head thus can not fail.
5951  *      Caller must re-evaluate skb->truesize if needed.
5952  */
5953 void skb_condense(struct sk_buff *skb)
5954 {
5955         if (skb->data_len) {
5956                 if (skb->data_len > skb->end - skb->tail ||
5957                     skb_cloned(skb))
5958                         return;
5959 
5960                 /* Nice, we can free page frag(s) right now */
5961                 __pskb_pull_tail(skb, skb->data_len);
5962         }
5963         /* At this point, skb->truesize might be over estimated,
5964          * because skb had a fragment, and fragments do not tell
5965          * their truesize.
5966          * When we pulled its content into skb->head, fragment
5967          * was freed, but __pskb_pull_tail() could not possibly
5968          * adjust skb->truesize, not knowing the frag truesize.
5969          */
5970         skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
5971 }
5972 
5973 #ifdef CONFIG_SKB_EXTENSIONS
5974 static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id)
5975 {
5976         return (void *)ext + (ext->offset[id] * SKB_EXT_ALIGN_VALUE);
5977 }
5978 
5979 static struct skb_ext *skb_ext_alloc(void)
5980 {
5981         struct skb_ext *new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC);
5982 
5983         if (new) {
5984                 memset(new->offset, 0, sizeof(new->offset));
5985                 refcount_set(&new->refcnt, 1);
5986         }
5987 
5988         return new;
5989 }
5990 
5991 static struct skb_ext *skb_ext_maybe_cow(struct skb_ext *old,
5992                                          unsigned int old_active)
5993 {
5994         struct skb_ext *new;
5995 
5996         if (refcount_read(&old->refcnt) == 1)
5997                 return old;
5998 
5999         new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC);
6000         if (!new)
6001                 return NULL;
6002 
6003         memcpy(new, old, old->chunks * SKB_EXT_ALIGN_VALUE);
6004         refcount_set(&new->refcnt, 1);
6005 
6006 #ifdef CONFIG_XFRM
6007         if (old_active & (1 << SKB_EXT_SEC_PATH)) {
6008                 struct sec_path *sp = skb_ext_get_ptr(old, SKB_EXT_SEC_PATH);
6009                 unsigned int i;
6010 
6011                 for (i = 0; i < sp->len; i++)
6012                         xfrm_state_hold(sp->xvec[i]);
6013         }
6014 #endif
6015         __skb_ext_put(old);
6016         return new;
6017 }
6018 
6019 /**
6020  * skb_ext_add - allocate space for given extension, COW if needed
6021  * @skb: buffer
6022  * @id: extension to allocate space for
6023  *
6024  * Allocates enough space for the given extension.
6025  * If the extension is already present, a pointer to that extension
6026  * is returned.
6027  *
6028  * If the skb was cloned, COW applies and the returned memory can be
6029  * modified without changing the extension space of clones buffers.
6030  *
6031  * Returns pointer to the extension or NULL on allocation failure.
6032  */
6033 void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id)
6034 {
6035         struct skb_ext *new, *old = NULL;
6036         unsigned int newlen, newoff;
6037 
6038         if (skb->active_extensions) {
6039                 old = skb->extensions;
6040 
6041                 new = skb_ext_maybe_cow(old, skb->active_extensions);
6042                 if (!new)
6043                         return NULL;