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/bitfield.h>
62 #include <linux/if_vlan.h>
63 #include <linux/mpls.h>
64 #include <linux/kcov.h>
65
66 #include <net/protocol.h>
67 #include <net/dst.h>
68 #include <net/sock.h>
69 #include <net/checksum.h>
70 #include <net/gso.h>
71 #include <net/ip6_checksum.h>
72 #include <net/xfrm.h>
73 #include <net/mpls.h>
74 #include <net/mptcp.h>
75 #include <net/mctp.h>
76 #include <net/page_pool/helpers.h>
77 #include <net/dropreason.h>
78
79 #include <linux/uaccess.h>
80 #include <trace/events/skb.h>
81 #include <linux/highmem.h>
82 #include <linux/capability.h>
83 #include <linux/user_namespace.h>
84 #include <linux/indirect_call_wrapper.h>
85 #include <linux/textsearch.h>
86
87 #include "dev.h"
88 #include "sock_destructor.h"
89
90 struct kmem_cache *skbuff_cache __ro_after_init;
91 static struct kmem_cache *skbuff_fclone_cache __ro_after_init;
92 #ifdef CONFIG_SKB_EXTENSIONS
93 static struct kmem_cache *skbuff_ext_cache __ro_after_init;
94 #endif
95
96
97 static struct kmem_cache *skb_small_head_cache __ro_after_init;
98
99 #define SKB_SMALL_HEAD_SIZE SKB_HEAD_ALIGN(MAX_TCP_HEADER)
100
101 /* We want SKB_SMALL_HEAD_CACHE_SIZE to not be a power of two.
102 * This should ensure that SKB_SMALL_HEAD_HEADROOM is a unique
103 * size, and we can differentiate heads from skb_small_head_cache
104 * vs system slabs by looking at their size (skb_end_offset()).
105 */
106 #define SKB_SMALL_HEAD_CACHE_SIZE \
107 (is_power_of_2(SKB_SMALL_HEAD_SIZE) ? \
108 (SKB_SMALL_HEAD_SIZE + L1_CACHE_BYTES) : \
109 SKB_SMALL_HEAD_SIZE)
110
111 #define SKB_SMALL_HEAD_HEADROOM \
112 SKB_WITH_OVERHEAD(SKB_SMALL_HEAD_CACHE_SIZE)
113
114 int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
115 EXPORT_SYMBOL(sysctl_max_skb_frags);
116
117 #undef FN
118 #define FN(reason) [SKB_DROP_REASON_##reason] = #reason,
119 static const char * const drop_reasons[] = {
120 [SKB_CONSUMED] = "CONSUMED",
121 DEFINE_DROP_REASON(FN, FN)
122 };
123
124 static const struct drop_reason_list drop_reasons_core = {
125 .reasons = drop_reasons,
126 .n_reasons = ARRAY_SIZE(drop_reasons),
127 };
128
129 const struct drop_reason_list __rcu *
130 drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM] = {
131 [SKB_DROP_REASON_SUBSYS_CORE] = RCU_INITIALIZER(&drop_reasons_core),
132 };
133 EXPORT_SYMBOL(drop_reasons_by_subsys);
134
135 /**
136 * drop_reasons_register_subsys - register another drop reason subsystem
137 * @subsys: the subsystem to register, must not be the core
138 * @list: the list of drop reasons within the subsystem, must point to
139 * a statically initialized list
140 */
drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,const struct drop_reason_list * list)141 void drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,
142 const struct drop_reason_list *list)
143 {
144 if (WARN(subsys <= SKB_DROP_REASON_SUBSYS_CORE ||
145 subsys >= ARRAY_SIZE(drop_reasons_by_subsys),
146 "invalid subsystem %d\n", subsys))
147 return;
148
149 /* must point to statically allocated memory, so INIT is OK */
150 RCU_INIT_POINTER(drop_reasons_by_subsys[subsys], list);
151 }
152 EXPORT_SYMBOL_GPL(drop_reasons_register_subsys);
153
154 /**
155 * drop_reasons_unregister_subsys - unregister a drop reason subsystem
156 * @subsys: the subsystem to remove, must not be the core
157 *
158 * Note: This will synchronize_rcu() to ensure no users when it returns.
159 */
drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys)160 void drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys)
161 {
162 if (WARN(subsys <= SKB_DROP_REASON_SUBSYS_CORE ||
163 subsys >= ARRAY_SIZE(drop_reasons_by_subsys),
164 "invalid subsystem %d\n", subsys))
165 return;
166
167 RCU_INIT_POINTER(drop_reasons_by_subsys[subsys], NULL);
168
169 synchronize_rcu();
170 }
171 EXPORT_SYMBOL_GPL(drop_reasons_unregister_subsys);
172
173 /**
174 * skb_panic - private function for out-of-line support
175 * @skb: buffer
176 * @sz: size
177 * @addr: address
178 * @msg: skb_over_panic or skb_under_panic
179 *
180 * Out-of-line support for skb_put() and skb_push().
181 * Called via the wrapper skb_over_panic() or skb_under_panic().
182 * Keep out of line to prevent kernel bloat.
183 * __builtin_return_address is not used because it is not always reliable.
184 */
skb_panic(struct sk_buff * skb,unsigned int sz,void * addr,const char msg[])185 static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
186 const char msg[])
187 {
188 pr_emerg("%s: text:%px len:%d put:%d head:%px data:%px tail:%#lx end:%#lx dev:%s\n",
189 msg, addr, skb->len, sz, skb->head, skb->data,
190 (unsigned long)skb->tail, (unsigned long)skb->end,
191 skb->dev ? skb->dev->name : "<NULL>");
192 BUG();
193 }
194
skb_over_panic(struct sk_buff * skb,unsigned int sz,void * addr)195 static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
196 {
197 skb_panic(skb, sz, addr, __func__);
198 }
199
skb_under_panic(struct sk_buff * skb,unsigned int sz,void * addr)200 static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
201 {
202 skb_panic(skb, sz, addr, __func__);
203 }
204
205 #define NAPI_SKB_CACHE_SIZE 64
206 #define NAPI_SKB_CACHE_BULK 16
207 #define NAPI_SKB_CACHE_HALF (NAPI_SKB_CACHE_SIZE / 2)
208
209 #if PAGE_SIZE == SZ_4K
210
211 #define NAPI_HAS_SMALL_PAGE_FRAG 1
212 #define NAPI_SMALL_PAGE_PFMEMALLOC(nc) ((nc).pfmemalloc)
213
214 /* specialized page frag allocator using a single order 0 page
215 * and slicing it into 1K sized fragment. Constrained to systems
216 * with a very limited amount of 1K fragments fitting a single
217 * page - to avoid excessive truesize underestimation
218 */
219
220 struct page_frag_1k {
221 void *va;
222 u16 offset;
223 bool pfmemalloc;
224 };
225
page_frag_alloc_1k(struct page_frag_1k * nc,gfp_t gfp)226 static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp)
227 {
228 struct page *page;
229 int offset;
230
231 offset = nc->offset - SZ_1K;
232 if (likely(offset >= 0))
233 goto use_frag;
234
235 page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
236 if (!page)
237 return NULL;
238
239 nc->va = page_address(page);
240 nc->pfmemalloc = page_is_pfmemalloc(page);
241 offset = PAGE_SIZE - SZ_1K;
242 page_ref_add(page, offset / SZ_1K);
243
244 use_frag:
245 nc->offset = offset;
246 return nc->va + offset;
247 }
248 #else
249
250 /* the small page is actually unused in this build; add dummy helpers
251 * to please the compiler and avoid later preprocessor's conditionals
252 */
253 #define NAPI_HAS_SMALL_PAGE_FRAG 0
254 #define NAPI_SMALL_PAGE_PFMEMALLOC(nc) false
255
256 struct page_frag_1k {
257 };
258
page_frag_alloc_1k(struct page_frag_1k * nc,gfp_t gfp_mask)259 static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp_mask)
260 {
261 return NULL;
262 }
263
264 #endif
265
266 struct napi_alloc_cache {
267 struct page_frag_cache page;
268 struct page_frag_1k page_small;
269 unsigned int skb_count;
270 void *skb_cache[NAPI_SKB_CACHE_SIZE];
271 };
272
273 static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
274 static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache);
275
276 /* Double check that napi_get_frags() allocates skbs with
277 * skb->head being backed by slab, not a page fragment.
278 * This is to make sure bug fixed in 3226b158e67c
279 * ("net: avoid 32 x truesize under-estimation for tiny skbs")
280 * does not accidentally come back.
281 */
napi_get_frags_check(struct napi_struct * napi)282 void napi_get_frags_check(struct napi_struct *napi)
283 {
284 struct sk_buff *skb;
285
286 local_bh_disable();
287 skb = napi_get_frags(napi);
288 WARN_ON_ONCE(!NAPI_HAS_SMALL_PAGE_FRAG && skb && skb->head_frag);
289 napi_free_frags(napi);
290 local_bh_enable();
291 }
292
__napi_alloc_frag_align(unsigned int fragsz,unsigned int align_mask)293 void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
294 {
295 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
296
297 fragsz = SKB_DATA_ALIGN(fragsz);
298
299 return page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC, align_mask);
300 }
301 EXPORT_SYMBOL(__napi_alloc_frag_align);
302
__netdev_alloc_frag_align(unsigned int fragsz,unsigned int align_mask)303 void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
304 {
305 void *data;
306
307 fragsz = SKB_DATA_ALIGN(fragsz);
308 if (in_hardirq() || irqs_disabled()) {
309 struct page_frag_cache *nc = this_cpu_ptr(&netdev_alloc_cache);
310
311 data = page_frag_alloc_align(nc, fragsz, GFP_ATOMIC, align_mask);
312 } else {
313 struct napi_alloc_cache *nc;
314
315 local_bh_disable();
316 nc = this_cpu_ptr(&napi_alloc_cache);
317 data = page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC, align_mask);
318 local_bh_enable();
319 }
320 return data;
321 }
322 EXPORT_SYMBOL(__netdev_alloc_frag_align);
323
napi_skb_cache_get(void)324 static struct sk_buff *napi_skb_cache_get(void)
325 {
326 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
327 struct sk_buff *skb;
328
329 if (unlikely(!nc->skb_count)) {
330 nc->skb_count = kmem_cache_alloc_bulk(skbuff_cache,
331 GFP_ATOMIC,
332 NAPI_SKB_CACHE_BULK,
333 nc->skb_cache);
334 if (unlikely(!nc->skb_count))
335 return NULL;
336 }
337
338 skb = nc->skb_cache[--nc->skb_count];
339 kasan_unpoison_object_data(skbuff_cache, skb);
340
341 return skb;
342 }
343
__finalize_skb_around(struct sk_buff * skb,void * data,unsigned int size)344 static inline void __finalize_skb_around(struct sk_buff *skb, void *data,
345 unsigned int size)
346 {
347 struct skb_shared_info *shinfo;
348
349 size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
350
351 /* Assumes caller memset cleared SKB */
352 skb->truesize = SKB_TRUESIZE(size);
353 refcount_set(&skb->users, 1);
354 skb->head = data;
355 skb->data = data;
356 skb_reset_tail_pointer(skb);
357 skb_set_end_offset(skb, size);
358 skb->mac_header = (typeof(skb->mac_header))~0U;
359 skb->transport_header = (typeof(skb->transport_header))~0U;
360 skb->alloc_cpu = raw_smp_processor_id();
361 /* make sure we initialize shinfo sequentially */
362 shinfo = skb_shinfo(skb);
363 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
364 atomic_set(&shinfo->dataref, 1);
365
366 skb_set_kcov_handle(skb, kcov_common_handle());
367 }
368
__slab_build_skb(struct sk_buff * skb,void * data,unsigned int * size)369 static inline void *__slab_build_skb(struct sk_buff *skb, void *data,
370 unsigned int *size)
371 {
372 void *resized;
373
374 /* Must find the allocation size (and grow it to match). */
375 *size = ksize(data);
376 /* krealloc() will immediately return "data" when
377 * "ksize(data)" is requested: it is the existing upper
378 * bounds. As a result, GFP_ATOMIC will be ignored. Note
379 * that this "new" pointer needs to be passed back to the
380 * caller for use so the __alloc_size hinting will be
381 * tracked correctly.
382 */
383 resized = krealloc(data, *size, GFP_ATOMIC);
384 WARN_ON_ONCE(resized != data);
385 return resized;
386 }
387
388 /* build_skb() variant which can operate on slab buffers.
389 * Note that this should be used sparingly as slab buffers
390 * cannot be combined efficiently by GRO!
391 */
slab_build_skb(void * data)392 struct sk_buff *slab_build_skb(void *data)
393 {
394 struct sk_buff *skb;
395 unsigned int size;
396
397 skb = kmem_cache_alloc(skbuff_cache, GFP_ATOMIC);
398 if (unlikely(!skb))
399 return NULL;
400
401 memset(skb, 0, offsetof(struct sk_buff, tail));
402 data = __slab_build_skb(skb, data, &size);
403 __finalize_skb_around(skb, data, size);
404
405 return skb;
406 }
407 EXPORT_SYMBOL(slab_build_skb);
408
409 /* Caller must provide SKB that is memset cleared */
__build_skb_around(struct sk_buff * skb,void * data,unsigned int frag_size)410 static void __build_skb_around(struct sk_buff *skb, void *data,
411 unsigned int frag_size)
412 {
413 unsigned int size = frag_size;
414
415 /* frag_size == 0 is considered deprecated now. Callers
416 * using slab buffer should use slab_build_skb() instead.
417 */
418 if (WARN_ONCE(size == 0, "Use slab_build_skb() instead"))
419 data = __slab_build_skb(skb, data, &size);
420
421 __finalize_skb_around(skb, data, size);
422 }
423
424 /**
425 * __build_skb - build a network buffer
426 * @data: data buffer provided by caller
427 * @frag_size: size of data (must not be 0)
428 *
429 * Allocate a new &sk_buff. Caller provides space holding head and
430 * skb_shared_info. @data must have been allocated from the page
431 * allocator or vmalloc(). (A @frag_size of 0 to indicate a kmalloc()
432 * allocation is deprecated, and callers should use slab_build_skb()
433 * instead.)
434 * The return is the new skb buffer.
435 * On a failure the return is %NULL, and @data is not freed.
436 * Notes :
437 * Before IO, driver allocates only data buffer where NIC put incoming frame
438 * Driver should add room at head (NET_SKB_PAD) and
439 * MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
440 * After IO, driver calls build_skb(), to allocate sk_buff and populate it
441 * before giving packet to stack.
442 * RX rings only contains data buffers, not full skbs.
443 */
__build_skb(void * data,unsigned int frag_size)444 struct sk_buff *__build_skb(void *data, unsigned int frag_size)
445 {
446 struct sk_buff *skb;
447
448 skb = kmem_cache_alloc(skbuff_cache, GFP_ATOMIC);
449 if (unlikely(!skb))
450 return NULL;
451
452 memset(skb, 0, offsetof(struct sk_buff, tail));
453 __build_skb_around(skb, data, frag_size);
454
455 return skb;
456 }
457
458 /* build_skb() is wrapper over __build_skb(), that specifically
459 * takes care of skb->head and skb->pfmemalloc
460 */
build_skb(void * data,unsigned int frag_size)461 struct sk_buff *build_skb(void *data, unsigned int frag_size)
462 {
463 struct sk_buff *skb = __build_skb(data, frag_size);
464
465 if (likely(skb && frag_size)) {
466 skb->head_frag = 1;
467 skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
468 }
469 return skb;
470 }
471 EXPORT_SYMBOL(build_skb);
472
473 /**
474 * build_skb_around - build a network buffer around provided skb
475 * @skb: sk_buff provide by caller, must be memset cleared
476 * @data: data buffer provided by caller
477 * @frag_size: size of data
478 */
build_skb_around(struct sk_buff * skb,void * data,unsigned int frag_size)479 struct sk_buff *build_skb_around(struct sk_buff *skb,
480 void *data, unsigned int frag_size)
481 {
482 if (unlikely(!skb))
483 return NULL;
484
485 __build_skb_around(skb, data, frag_size);
486
487 if (frag_size) {
488 skb->head_frag = 1;
489 skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
490 }
491 return skb;
492 }
493 EXPORT_SYMBOL(build_skb_around);
494
495 /**
496 * __napi_build_skb - build a network buffer
497 * @data: data buffer provided by caller
498 * @frag_size: size of data
499 *
500 * Version of __build_skb() that uses NAPI percpu caches to obtain
501 * skbuff_head instead of inplace allocation.
502 *
503 * Returns a new &sk_buff on success, %NULL on allocation failure.
504 */
__napi_build_skb(void * data,unsigned int frag_size)505 static struct sk_buff *__napi_build_skb(void *data, unsigned int frag_size)
506 {
507 struct sk_buff *skb;
508
509 skb = napi_skb_cache_get();
510 if (unlikely(!skb))
511 return NULL;
512
513 memset(skb, 0, offsetof(struct sk_buff, tail));
514 __build_skb_around(skb, data, frag_size);
515
516 return skb;
517 }
518
519 /**
520 * napi_build_skb - build a network buffer
521 * @data: data buffer provided by caller
522 * @frag_size: size of data
523 *
524 * Version of __napi_build_skb() that takes care of skb->head_frag
525 * and skb->pfmemalloc when the data is a page or page fragment.
526 *
527 * Returns a new &sk_buff on success, %NULL on allocation failure.
528 */
napi_build_skb(void * data,unsigned int frag_size)529 struct sk_buff *napi_build_skb(void *data, unsigned int frag_size)
530 {
531 struct sk_buff *skb = __napi_build_skb(data, frag_size);
532
533 if (likely(skb) && frag_size) {
534 skb->head_frag = 1;
535 skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
536 }
537
538 return skb;
539 }
540 EXPORT_SYMBOL(napi_build_skb);
541
542 /*
543 * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
544 * the caller if emergency pfmemalloc reserves are being used. If it is and
545 * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
546 * may be used. Otherwise, the packet data may be discarded until enough
547 * memory is free
548 */
kmalloc_reserve(unsigned int * size,gfp_t flags,int node,bool * pfmemalloc)549 static void *kmalloc_reserve(unsigned int *size, gfp_t flags, int node,
550 bool *pfmemalloc)
551 {
552 bool ret_pfmemalloc = false;
553 size_t obj_size;
554 void *obj;
555
556 obj_size = SKB_HEAD_ALIGN(*size);
557 if (obj_size <= SKB_SMALL_HEAD_CACHE_SIZE &&
558 !(flags & KMALLOC_NOT_NORMAL_BITS)) {
559 obj = kmem_cache_alloc_node(skb_small_head_cache,
560 flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
561 node);
562 *size = SKB_SMALL_HEAD_CACHE_SIZE;
563 if (obj || !(gfp_pfmemalloc_allowed(flags)))
564 goto out;
565 /* Try again but now we are using pfmemalloc reserves */
566 ret_pfmemalloc = true;
567 obj = kmem_cache_alloc_node(skb_small_head_cache, flags, node);
568 goto out;
569 }
570
571 obj_size = kmalloc_size_roundup(obj_size);
572 /* The following cast might truncate high-order bits of obj_size, this
573 * is harmless because kmalloc(obj_size >= 2^32) will fail anyway.
574 */
575 *size = (unsigned int)obj_size;
576
577 /*
578 * Try a regular allocation, when that fails and we're not entitled
579 * to the reserves, fail.
580 */
581 obj = kmalloc_node_track_caller(obj_size,
582 flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
583 node);
584 if (obj || !(gfp_pfmemalloc_allowed(flags)))
585 goto out;
586
587 /* Try again but now we are using pfmemalloc reserves */
588 ret_pfmemalloc = true;
589 obj = kmalloc_node_track_caller(obj_size, flags, node);
590
591 out:
592 if (pfmemalloc)
593 *pfmemalloc = ret_pfmemalloc;
594
595 return obj;
596 }
597
598 /* Allocate a new skbuff. We do this ourselves so we can fill in a few
599 * 'private' fields and also do memory statistics to find all the
600 * [BEEP] leaks.
601 *
602 */
603
604 /**
605 * __alloc_skb - allocate a network buffer
606 * @size: size to allocate
607 * @gfp_mask: allocation mask
608 * @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
609 * instead of head cache and allocate a cloned (child) skb.
610 * If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
611 * allocations in case the data is required for writeback
612 * @node: numa node to allocate memory on
613 *
614 * Allocate a new &sk_buff. The returned buffer has no headroom and a
615 * tail room of at least size bytes. The object has a reference count
616 * of one. The return is the buffer. On a failure the return is %NULL.
617 *
618 * Buffers may only be allocated from interrupts using a @gfp_mask of
619 * %GFP_ATOMIC.
620 */
__alloc_skb(unsigned int size,gfp_t gfp_mask,int flags,int node)621 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
622 int flags, int node)
623 {
624 struct kmem_cache *cache;
625 struct sk_buff *skb;
626 bool pfmemalloc;
627 u8 *data;
628
629 cache = (flags & SKB_ALLOC_FCLONE)
630 ? skbuff_fclone_cache : skbuff_cache;
631
632 if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
633 gfp_mask |= __GFP_MEMALLOC;
634
635 /* Get the HEAD */
636 if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI)) == SKB_ALLOC_NAPI &&
637 likely(node == NUMA_NO_NODE || node == numa_mem_id()))
638 skb = napi_skb_cache_get();
639 else
640 skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node);
641 if (unlikely(!skb))
642 return NULL;
643 prefetchw(skb);
644
645 /* We do our best to align skb_shared_info on a separate cache
646 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
647 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
648 * Both skb->head and skb_shared_info are cache line aligned.
649 */
650 data = kmalloc_reserve(&size, gfp_mask, node, &pfmemalloc);
651 if (unlikely(!data))
652 goto nodata;
653 /* kmalloc_size_roundup() might give us more room than requested.
654 * Put skb_shared_info exactly at the end of allocated zone,
655 * to allow max possible filling before reallocation.
656 */
657 prefetchw(data + SKB_WITH_OVERHEAD(size));
658
659 /*
660 * Only clear those fields we need to clear, not those that we will
661 * actually initialise below. Hence, don't put any more fields after
662 * the tail pointer in struct sk_buff!
663 */
664 memset(skb, 0, offsetof(struct sk_buff, tail));
665 __build_skb_around(skb, data, size);
666 skb->pfmemalloc = pfmemalloc;
667
668 if (flags & SKB_ALLOC_FCLONE) {
669 struct sk_buff_fclones *fclones;
670
671 fclones = container_of(skb, struct sk_buff_fclones, skb1);
672
673 skb->fclone = SKB_FCLONE_ORIG;
674 refcount_set(&fclones->fclone_ref, 1);
675 }
676
677 return skb;
678
679 nodata:
680 kmem_cache_free(cache, skb);
681 return NULL;
682 }
683 EXPORT_SYMBOL(__alloc_skb);
684
685 /**
686 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device
687 * @dev: network device to receive on
688 * @len: length to allocate
689 * @gfp_mask: get_free_pages mask, passed to alloc_skb
690 *
691 * Allocate a new &sk_buff and assign it a usage count of one. The
692 * buffer has NET_SKB_PAD headroom built in. Users should allocate
693 * the headroom they think they need without accounting for the
694 * built in space. The built in space is used for optimisations.
695 *
696 * %NULL is returned if there is no free memory.
697 */
__netdev_alloc_skb(struct net_device * dev,unsigned int len,gfp_t gfp_mask)698 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
699 gfp_t gfp_mask)
700 {
701 struct page_frag_cache *nc;
702 struct sk_buff *skb;
703 bool pfmemalloc;
704 void *data;
705
706 len += NET_SKB_PAD;
707
708 /* If requested length is either too small or too big,
709 * we use kmalloc() for skb->head allocation.
710 */
711 if (len <= SKB_WITH_OVERHEAD(1024) ||
712 len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
713 (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
714 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
715 if (!skb)
716 goto skb_fail;
717 goto skb_success;
718 }
719
720 len = SKB_HEAD_ALIGN(len);
721
722 if (sk_memalloc_socks())
723 gfp_mask |= __GFP_MEMALLOC;
724
725 if (in_hardirq() || irqs_disabled()) {
726 nc = this_cpu_ptr(&netdev_alloc_cache);
727 data = page_frag_alloc(nc, len, gfp_mask);
728 pfmemalloc = nc->pfmemalloc;
729 } else {
730 local_bh_disable();
731 nc = this_cpu_ptr(&napi_alloc_cache.page);
732 data = page_frag_alloc(nc, len, gfp_mask);
733 pfmemalloc = nc->pfmemalloc;
734 local_bh_enable();
735 }
736
737 if (unlikely(!data))
738 return NULL;
739
740 skb = __build_skb(data, len);
741 if (unlikely(!skb)) {
742 skb_free_frag(data);
743 return NULL;
744 }
745
746 if (pfmemalloc)
747 skb->pfmemalloc = 1;
748 skb->head_frag = 1;
749
750 skb_success:
751 skb_reserve(skb, NET_SKB_PAD);
752 skb->dev = dev;
753
754 skb_fail:
755 return skb;
756 }
757 EXPORT_SYMBOL(__netdev_alloc_skb);
758
759 /**
760 * __napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
761 * @napi: napi instance this buffer was allocated for
762 * @len: length to allocate
763 * @gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
764 *
765 * Allocate a new sk_buff for use in NAPI receive. This buffer will
766 * attempt to allocate the head from a special reserved region used
767 * only for NAPI Rx allocation. By doing this we can save several
768 * CPU cycles by avoiding having to disable and re-enable IRQs.
769 *
770 * %NULL is returned if there is no free memory.
771 */
__napi_alloc_skb(struct napi_struct * napi,unsigned int len,gfp_t gfp_mask)772 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
773 gfp_t gfp_mask)
774 {
775 struct napi_alloc_cache *nc;
776 struct sk_buff *skb;
777 bool pfmemalloc;
778 void *data;
779
780 DEBUG_NET_WARN_ON_ONCE(!in_softirq());
781 len += NET_SKB_PAD + NET_IP_ALIGN;
782
783 /* If requested length is either too small or too big,
784 * we use kmalloc() for skb->head allocation.
785 * When the small frag allocator is available, prefer it over kmalloc
786 * for small fragments
787 */
788 if ((!NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) ||
789 len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
790 (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
791 skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX | SKB_ALLOC_NAPI,
792 NUMA_NO_NODE);
793 if (!skb)
794 goto skb_fail;
795 goto skb_success;
796 }
797
798 nc = this_cpu_ptr(&napi_alloc_cache);
799
800 if (sk_memalloc_socks())
801 gfp_mask |= __GFP_MEMALLOC;
802
803 if (NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) {
804 /* we are artificially inflating the allocation size, but
805 * that is not as bad as it may look like, as:
806 * - 'len' less than GRO_MAX_HEAD makes little sense
807 * - On most systems, larger 'len' values lead to fragment
808 * size above 512 bytes
809 * - kmalloc would use the kmalloc-1k slab for such values
810 * - Builds with smaller GRO_MAX_HEAD will very likely do
811 * little networking, as that implies no WiFi and no
812 * tunnels support, and 32 bits arches.
813 */
814 len = SZ_1K;
815
816 data = page_frag_alloc_1k(&nc->page_small, gfp_mask);
817 pfmemalloc = NAPI_SMALL_PAGE_PFMEMALLOC(nc->page_small);
818 } else {
819 len = SKB_HEAD_ALIGN(len);
820
821 data = page_frag_alloc(&nc->page, len, gfp_mask);
822 pfmemalloc = nc->page.pfmemalloc;
823 }
824
825 if (unlikely(!data))
826 return NULL;
827
828 skb = __napi_build_skb(data, len);
829 if (unlikely(!skb)) {
830 skb_free_frag(data);
831 return NULL;
832 }
833
834 if (pfmemalloc)
835 skb->pfmemalloc = 1;
836 skb->head_frag = 1;
837
838 skb_success:
839 skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
840 skb->dev = napi->dev;
841
842 skb_fail:
843 return skb;
844 }
845 EXPORT_SYMBOL(__napi_alloc_skb);
846
skb_add_rx_frag(struct sk_buff * skb,int i,struct page * page,int off,int size,unsigned int truesize)847 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
848 int size, unsigned int truesize)
849 {
850 skb_fill_page_desc(skb, i, page, off, size);
851 skb->len += size;
852 skb->data_len += size;
853 skb->truesize += truesize;
854 }
855 EXPORT_SYMBOL(skb_add_rx_frag);
856
skb_coalesce_rx_frag(struct sk_buff * skb,int i,int size,unsigned int truesize)857 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
858 unsigned int truesize)
859 {
860 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
861
862 skb_frag_size_add(frag, size);
863 skb->len += size;
864 skb->data_len += size;
865 skb->truesize += truesize;
866 }
867 EXPORT_SYMBOL(skb_coalesce_rx_frag);
868
skb_drop_list(struct sk_buff ** listp)869 static void skb_drop_list(struct sk_buff **listp)
870 {
871 kfree_skb_list(*listp);
872 *listp = NULL;
873 }
874
skb_drop_fraglist(struct sk_buff * skb)875 static inline void skb_drop_fraglist(struct sk_buff *skb)
876 {
877 skb_drop_list(&skb_shinfo(skb)->frag_list);
878 }
879
skb_clone_fraglist(struct sk_buff * skb)880 static void skb_clone_fraglist(struct sk_buff *skb)
881 {
882 struct sk_buff *list;
883
884 skb_walk_frags(skb, list)
885 skb_get(list);
886 }
887
888 #if IS_ENABLED(CONFIG_PAGE_POOL)
napi_pp_put_page(struct page * page,bool napi_safe)889 bool napi_pp_put_page(struct page *page, bool napi_safe)
890 {
891 bool allow_direct = false;
892 struct page_pool *pp;
893
894 page = compound_head(page);
895
896 /* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
897 * in order to preserve any existing bits, such as bit 0 for the
898 * head page of compound page and bit 1 for pfmemalloc page, so
899 * mask those bits for freeing side when doing below checking,
900 * and page_is_pfmemalloc() is checked in __page_pool_put_page()
901 * to avoid recycling the pfmemalloc page.
902 */
903 if (unlikely((page->pp_magic & ~0x3UL) != PP_SIGNATURE))
904 return false;
905
906 pp = page->pp;
907
908 /* Allow direct recycle if we have reasons to believe that we are
909 * in the same context as the consumer would run, so there's
910 * no possible race.
911 * __page_pool_put_page() makes sure we're not in hardirq context
912 * and interrupts are enabled prior to accessing the cache.
913 */
914 if (napi_safe || in_softirq()) {
915 const struct napi_struct *napi = READ_ONCE(pp->p.napi);
916
917 allow_direct = napi &&
918 READ_ONCE(napi->list_owner) == smp_processor_id();
919 }
920
921 /* Driver set this to memory recycling info. Reset it on recycle.
922 * This will *not* work for NIC using a split-page memory model.
923 * The page will be returned to the pool here regardless of the
924 * 'flipped' fragment being in use or not.
925 */
926 page_pool_put_full_page(pp, page, allow_direct);
927
928 return true;
929 }
930 EXPORT_SYMBOL(napi_pp_put_page);
931 #endif
932
skb_pp_recycle(struct sk_buff * skb,void * data,bool napi_safe)933 static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe)
934 {
935 if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
936 return false;
937 return napi_pp_put_page(virt_to_page(data), napi_safe);
938 }
939
skb_kfree_head(void * head,unsigned int end_offset)940 static void skb_kfree_head(void *head, unsigned int end_offset)
941 {
942 if (end_offset == SKB_SMALL_HEAD_HEADROOM)
943 kmem_cache_free(skb_small_head_cache, head);
944 else
945 kfree(head);
946 }
947
skb_free_head(struct sk_buff * skb,bool napi_safe)948 static void skb_free_head(struct sk_buff *skb, bool napi_safe)
949 {
950 unsigned char *head = skb->head;
951
952 if (skb->head_frag) {
953 if (skb_pp_recycle(skb, head, napi_safe))
954 return;
955 skb_free_frag(head);
956 } else {
957 skb_kfree_head(head, skb_end_offset(skb));
958 }
959 }
960
skb_release_data(struct sk_buff * skb,enum skb_drop_reason reason,bool napi_safe)961 static void skb_release_data(struct sk_buff *skb, enum skb_drop_reason reason,
962 bool napi_safe)
963 {
964 struct skb_shared_info *shinfo = skb_shinfo(skb);
965 int i;
966
967 if (skb->cloned &&
968 atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
969 &shinfo->dataref))
970 goto exit;
971
972 if (skb_zcopy(skb)) {
973 bool skip_unref = shinfo->flags & SKBFL_MANAGED_FRAG_REFS;
974
975 skb_zcopy_clear(skb, true);
976 if (skip_unref)
977 goto free_head;
978 }
979
980 for (i = 0; i < shinfo->nr_frags; i++)
981 napi_frag_unref(&shinfo->frags[i], skb->pp_recycle, napi_safe);
982
983 free_head:
984 if (shinfo->frag_list)
985 kfree_skb_list_reason(shinfo->frag_list, reason);
986
987 skb_free_head(skb, napi_safe);
988 exit:
989 /* When we clone an SKB we copy the reycling bit. The pp_recycle
990 * bit is only set on the head though, so in order to avoid races
991 * while trying to recycle fragments on __skb_frag_unref() we need
992 * to make one SKB responsible for triggering the recycle path.
993 * So disable the recycling bit if an SKB is cloned and we have
994 * additional references to the fragmented part of the SKB.
995 * Eventually the last SKB will have the recycling bit set and it's
996 * dataref set to 0, which will trigger the recycling
997 */
998 skb->pp_recycle = 0;
999 }
1000
1001 /*
1002 * Free an skbuff by memory without cleaning the state.
1003 */
kfree_skbmem(struct sk_buff * skb)1004 static void kfree_skbmem(struct sk_buff *skb)
1005 {
1006 struct sk_buff_fclones *fclones;
1007
1008 switch (skb->fclone) {
1009 case SKB_FCLONE_UNAVAILABLE:
1010 kmem_cache_free(skbuff_cache, skb);
1011 return;
1012
1013 case SKB_FCLONE_ORIG:
1014 fclones = container_of(skb, struct sk_buff_fclones, skb1);
1015
1016 /* We usually free the clone (TX completion) before original skb
1017 * This test would have no chance to be true for the clone,
1018 * while here, branch prediction will be good.
1019 */
1020 if (refcount_read(&fclones->fclone_ref) == 1)
1021 goto fastpath;
1022 break;
1023
1024 default: /* SKB_FCLONE_CLONE */
1025 fclones = container_of(skb, struct sk_buff_fclones, skb2);
1026 break;
1027 }
1028 if (!refcount_dec_and_test(&fclones->fclone_ref))
1029 return;
1030 fastpath:
1031 kmem_cache_free(skbuff_fclone_cache, fclones);
1032 }
1033
skb_release_head_state(struct sk_buff * skb)1034 void skb_release_head_state(struct sk_buff *skb)
1035 {
1036 skb_dst_drop(skb);
1037 if (skb->destructor) {
1038 DEBUG_NET_WARN_ON_ONCE(in_hardirq());
1039 skb->destructor(skb);
1040 }
1041 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
1042 nf_conntrack_put(skb_nfct(skb));
1043 #endif
1044 skb_ext_put(skb);
1045 }
1046
1047 /* Free everything but the sk_buff shell. */
skb_release_all(struct sk_buff * skb,enum skb_drop_reason reason,bool napi_safe)1048 static void skb_release_all(struct sk_buff *skb, enum skb_drop_reason reason,
1049 bool napi_safe)
1050 {
1051 skb_release_head_state(skb);
1052 if (likely(skb->head))
1053 skb_release_data(skb, reason, napi_safe);
1054 }
1055
1056 /**
1057 * __kfree_skb - private function
1058 * @skb: buffer
1059 *
1060 * Free an sk_buff. Release anything attached to the buffer.
1061 * Clean the state. This is an internal helper function. Users should
1062 * always call kfree_skb
1063 */
1064
__kfree_skb(struct sk_buff * skb)1065 void __kfree_skb(struct sk_buff *skb)
1066 {
1067 skb_release_all(skb, SKB_DROP_REASON_NOT_SPECIFIED, false);
1068 kfree_skbmem(skb);
1069 }
1070 EXPORT_SYMBOL(__kfree_skb);
1071
1072 static __always_inline
__kfree_skb_reason(struct sk_buff * skb,enum skb_drop_reason reason)1073 bool __kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
1074 {
1075 if (unlikely(!skb_unref(skb)))
1076 return false;
1077
1078 DEBUG_NET_WARN_ON_ONCE(reason == SKB_NOT_DROPPED_YET ||
1079 u32_get_bits(reason,
1080 SKB_DROP_REASON_SUBSYS_MASK) >=
1081 SKB_DROP_REASON_SUBSYS_NUM);
1082
1083 if (reason == SKB_CONSUMED)
1084 trace_consume_skb(skb, __builtin_return_address(0));
1085 else
1086 trace_kfree_skb(skb, __builtin_return_address(0), reason);
1087 return true;
1088 }
1089
1090 /**
1091 * kfree_skb_reason - free an sk_buff with special reason
1092 * @skb: buffer to free
1093 * @reason: reason why this skb is dropped
1094 *
1095 * Drop a reference to the buffer and free it if the usage count has
1096 * hit zero. Meanwhile, pass the drop reason to 'kfree_skb'
1097 * tracepoint.
1098 */
1099 void __fix_address
kfree_skb_reason(struct sk_buff * skb,enum skb_drop_reason reason)1100 kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
1101 {
1102 if (__kfree_skb_reason(skb, reason))
1103 __kfree_skb(skb);
1104 }
1105 EXPORT_SYMBOL(kfree_skb_reason);
1106
1107 #define KFREE_SKB_BULK_SIZE 16
1108
1109 struct skb_free_array {
1110 unsigned int skb_count;
1111 void *skb_array[KFREE_SKB_BULK_SIZE];
1112 };
1113
kfree_skb_add_bulk(struct sk_buff * skb,struct skb_free_array * sa,enum skb_drop_reason reason)1114 static void kfree_skb_add_bulk(struct sk_buff *skb,
1115 struct skb_free_array *sa,
1116 enum skb_drop_reason reason)
1117 {
1118 /* if SKB is a clone, don't handle this case */
1119 if (unlikely(skb->fclone != SKB_FCLONE_UNAVAILABLE)) {
1120 __kfree_skb(skb);
1121 return;
1122 }
1123
1124 skb_release_all(skb, reason, false);
1125 sa->skb_array[sa->skb_count++] = skb;
1126
1127 if (unlikely(sa->skb_count == KFREE_SKB_BULK_SIZE)) {
1128 kmem_cache_free_bulk(skbuff_cache, KFREE_SKB_BULK_SIZE,
1129 sa->skb_array);
1130 sa->skb_count = 0;
1131 }
1132 }
1133
1134 void __fix_address
kfree_skb_list_reason(struct sk_buff * segs,enum skb_drop_reason reason)1135 kfree_skb_list_reason(struct sk_buff *segs, enum skb_drop_reason reason)
1136 {
1137 struct skb_free_array sa;
1138
1139 sa.skb_count = 0;
1140
1141 while (segs) {
1142 struct sk_buff *next = segs->next;
1143
1144 if (__kfree_skb_reason(segs, reason)) {
1145 skb_poison_list(segs);
1146 kfree_skb_add_bulk(segs, &sa, reason);
1147 }
1148
1149 segs = next;
1150 }
1151
1152 if (sa.skb_count)
1153 kmem_cache_free_bulk(skbuff_cache, sa.skb_count, sa.skb_array);
1154 }
1155 EXPORT_SYMBOL(kfree_skb_list_reason);
1156
1157 /* Dump skb information and contents.
1158 *
1159 * Must only be called from net_ratelimit()-ed paths.
1160 *
1161 * Dumps whole packets if full_pkt, only headers otherwise.
1162 */
skb_dump(const char * level,const struct sk_buff * skb,bool full_pkt)1163 void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt)
1164 {
1165 struct skb_shared_info *sh = skb_shinfo(skb);
1166 struct net_device *dev = skb->dev;
1167 struct sock *sk = skb->sk;
1168 struct sk_buff *list_skb;
1169 bool has_mac, has_trans;
1170 int headroom, tailroom;
1171 int i, len, seg_len;
1172
1173 if (full_pkt)
1174 len = skb->len;
1175 else
1176 len = min_t(int, skb->len, MAX_HEADER + 128);
1177
1178 headroom = skb_headroom(skb);
1179 tailroom = skb_tailroom(skb);
1180
1181 has_mac = skb_mac_header_was_set(skb);
1182 has_trans = skb_transport_header_was_set(skb);
1183
1184 printk("%sskb len=%u headroom=%u headlen=%u tailroom=%u\n"
1185 "mac=(%d,%d) net=(%d,%d) trans=%d\n"
1186 "shinfo(txflags=%u nr_frags=%u gso(size=%hu type=%u segs=%hu))\n"
1187 "csum(0x%x ip_summed=%u complete_sw=%u valid=%u level=%u)\n"
1188 "hash(0x%x sw=%u l4=%u) proto=0x%04x pkttype=%u iif=%d\n",
1189 level, skb->len, headroom, skb_headlen(skb), tailroom,
1190 has_mac ? skb->mac_header : -1,
1191 has_mac ? skb_mac_header_len(skb) : -1,
1192 skb->network_header,
1193 has_trans ? skb_network_header_len(skb) : -1,
1194 has_trans ? skb->transport_header : -1,
1195 sh->tx_flags, sh->nr_frags,
1196 sh->gso_size, sh->gso_type, sh->gso_segs,
1197 skb->csum, skb->ip_summed, skb->csum_complete_sw,
1198 skb->csum_valid, skb->csum_level,
1199 skb->hash, skb->sw_hash, skb->l4_hash,
1200 ntohs(skb->protocol), skb->pkt_type, skb->skb_iif);
1201
1202 if (dev)
1203 printk("%sdev name=%s feat=%pNF\n",
1204 level, dev->name, &dev->features);
1205 if (sk)
1206 printk("%ssk family=%hu type=%u proto=%u\n",
1207 level, sk->sk_family, sk->sk_type, sk->sk_protocol);
1208
1209 if (full_pkt && headroom)
1210 print_hex_dump(level, "skb headroom: ", DUMP_PREFIX_OFFSET,
1211 16, 1, skb->head, headroom, false);
1212
1213 seg_len = min_t(int, skb_headlen(skb), len);
1214 if (seg_len)
1215 print_hex_dump(level, "skb linear: ", DUMP_PREFIX_OFFSET,
1216 16, 1, skb->data, seg_len, false);
1217 len -= seg_len;
1218
1219 if (full_pkt && tailroom)
1220 print_hex_dump(level, "skb tailroom: ", DUMP_PREFIX_OFFSET,
1221 16, 1, skb_tail_pointer(skb), tailroom, false);
1222
1223 for (i = 0; len && i < skb_shinfo(skb)->nr_frags; i++) {
1224 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1225 u32 p_off, p_len, copied;
1226 struct page *p;
1227 u8 *vaddr;
1228
1229 skb_frag_foreach_page(frag, skb_frag_off(frag),
1230 skb_frag_size(frag), p, p_off, p_len,
1231 copied) {
1232 seg_len = min_t(int, p_len, len);
1233 vaddr = kmap_atomic(p);
1234 print_hex_dump(level, "skb frag: ",
1235 DUMP_PREFIX_OFFSET,
1236 16, 1, vaddr + p_off, seg_len, false);
1237 kunmap_atomic(vaddr);
1238 len -= seg_len;
1239 if (!len)
1240 break;
1241 }
1242 }
1243
1244 if (full_pkt && skb_has_frag_list(skb)) {
1245 printk("skb fraglist:\n");
1246 skb_walk_frags(skb, list_skb)
1247 skb_dump(level, list_skb, true);
1248 }
1249 }
1250 EXPORT_SYMBOL(skb_dump);
1251
1252 /**
1253 * skb_tx_error - report an sk_buff xmit error
1254 * @skb: buffer that triggered an error
1255 *
1256 * Report xmit error if a device callback is tracking this skb.
1257 * skb must be freed afterwards.
1258 */
skb_tx_error(struct sk_buff * skb)1259 void skb_tx_error(struct sk_buff *skb)
1260 {
1261 if (skb) {
1262 skb_zcopy_downgrade_managed(skb);
1263 skb_zcopy_clear(skb, true);
1264 }
1265 }
1266 EXPORT_SYMBOL(skb_tx_error);
1267
1268 #ifdef CONFIG_TRACEPOINTS
1269 /**
1270 * consume_skb - free an skbuff
1271 * @skb: buffer to free
1272 *
1273 * Drop a ref to the buffer and free it if the usage count has hit zero
1274 * Functions identically to kfree_skb, but kfree_skb assumes that the frame
1275 * is being dropped after a failure and notes that
1276 */
consume_skb(struct sk_buff * skb)1277 void consume_skb(struct sk_buff *skb)
1278 {
1279 if (!skb_unref(skb))
1280 return;
1281
1282 trace_consume_skb(skb, __builtin_return_address(0));
1283 __kfree_skb(skb);
1284 }
1285 EXPORT_SYMBOL(consume_skb);
1286 #endif
1287
1288 /**
1289 * __consume_stateless_skb - free an skbuff, assuming it is stateless
1290 * @skb: buffer to free
1291 *
1292 * Alike consume_skb(), but this variant assumes that this is the last
1293 * skb reference and all the head states have been already dropped
1294 */
__consume_stateless_skb(struct sk_buff * skb)1295 void __consume_stateless_skb(struct sk_buff *skb)
1296 {
1297 trace_consume_skb(skb, __builtin_return_address(0));
1298 skb_release_data(skb, SKB_CONSUMED, false);
1299 kfree_skbmem(skb);
1300 }
1301
napi_skb_cache_put(struct sk_buff * skb)1302 static void napi_skb_cache_put(struct sk_buff *skb)
1303 {
1304 struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
1305 u32 i;
1306
1307 kasan_poison_object_data(skbuff_cache, skb);
1308 nc->skb_cache[nc->skb_count++] = skb;
1309
1310 if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
1311 for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
1312 kasan_unpoison_object_data(skbuff_cache,
1313 nc->skb_cache[i]);
1314
1315 kmem_cache_free_bulk(skbuff_cache, NAPI_SKB_CACHE_HALF,
1316 nc->skb_cache + NAPI_SKB_CACHE_HALF);
1317 nc->skb_count = NAPI_SKB_CACHE_HALF;
1318 }
1319 }
1320
__napi_kfree_skb(struct sk_buff * skb,enum skb_drop_reason reason)1321 void __napi_kfree_skb(struct sk_buff *skb, enum skb_drop_reason reason)
1322 {
1323 skb_release_all(skb, reason, true);
1324 napi_skb_cache_put(skb);
1325 }
1326
napi_skb_free_stolen_head(struct sk_buff * skb)1327 void napi_skb_free_stolen_head(struct sk_buff *skb)
1328 {
1329 if (unlikely(skb->slow_gro)) {
1330 nf_reset_ct(skb);
1331 skb_dst_drop(skb);
1332 skb_ext_put(skb);
1333 skb_orphan(skb);
1334 skb->slow_gro = 0;
1335 }
1336 napi_skb_cache_put(skb);
1337 }
1338
napi_consume_skb(struct sk_buff * skb,int budget)1339 void napi_consume_skb(struct sk_buff *skb, int budget)
1340 {
1341 /* Zero budget indicate non-NAPI context called us, like netpoll */
1342 if (unlikely(!budget)) {
1343 dev_consume_skb_any(skb);
1344 return;
1345 }
1346
1347 DEBUG_NET_WARN_ON_ONCE(!in_softirq());
1348
1349 if (!skb_unref(skb))
1350 return;
1351
1352 /* if reaching here SKB is ready to free */
1353 trace_consume_skb(skb, __builtin_return_address(0));
1354
1355 /* if SKB is a clone, don't handle this case */
1356 if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
1357 __kfree_skb(skb);
1358 return;
1359 }
1360
1361 skb_release_all(skb, SKB_CONSUMED, !!budget);
1362 napi_skb_cache_put(skb);
1363 }
1364 EXPORT_SYMBOL(napi_consume_skb);
1365
1366 /* Make sure a field is contained by headers group */
1367 #define CHECK_SKB_FIELD(field) \
1368 BUILD_BUG_ON(offsetof(struct sk_buff, field) != \
1369 offsetof(struct sk_buff, headers.field)); \
1370
__copy_skb_header(struct sk_buff * new,const struct sk_buff * old)1371 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
1372 {
1373 new->tstamp = old->tstamp;
1374 /* We do not copy old->sk */
1375 new->dev = old->dev;
1376 memcpy(new->cb, old->cb, sizeof(old->cb));
1377 skb_dst_copy(new, old);
1378 __skb_ext_copy(new, old);
1379 __nf_copy(new, old, false);
1380
1381 /* Note : this field could be in the headers group.
1382 * It is not yet because we do not want to have a 16 bit hole
1383 */
1384 new->queue_mapping = old->queue_mapping;
1385
1386 memcpy(&new->headers, &old->headers, sizeof(new->headers));
1387 CHECK_SKB_FIELD(protocol);
1388 CHECK_SKB_FIELD(csum);
1389 CHECK_SKB_FIELD(hash);
1390 CHECK_SKB_FIELD(priority);
1391 CHECK_SKB_FIELD(skb_iif);
1392 CHECK_SKB_FIELD(vlan_proto);
1393 CHECK_SKB_FIELD(vlan_tci);
1394 CHECK_SKB_FIELD(transport_header);
1395 CHECK_SKB_FIELD(network_header);
1396 CHECK_SKB_FIELD(mac_header);
1397 CHECK_SKB_FIELD(inner_protocol);
1398 CHECK_SKB_FIELD(inner_transport_header);
1399 CHECK_SKB_FIELD(inner_network_header);
1400 CHECK_SKB_FIELD(inner_mac_header);
1401 CHECK_SKB_FIELD(mark);
1402 #ifdef CONFIG_NETWORK_SECMARK
1403 CHECK_SKB_FIELD(secmark);
1404 #endif
1405 #ifdef CONFIG_NET_RX_BUSY_POLL
1406 CHECK_SKB_FIELD(napi_id);
1407 #endif
1408 CHECK_SKB_FIELD(alloc_cpu);
1409 #ifdef CONFIG_XPS
1410 CHECK_SKB_FIELD(sender_cpu);
1411 #endif
1412 #ifdef CONFIG_NET_SCHED
1413 CHECK_SKB_FIELD(tc_index);
1414 #endif
1415
1416 }
1417
1418 /*
1419 * You should not add any new code to this function. Add it to
1420 * __copy_skb_header above instead.
1421 */
__skb_clone(struct sk_buff * n,struct sk_buff * skb)1422 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
1423 {
1424 #define C(x) n->x = skb->x
1425
1426 n->next = n->prev = NULL;
1427 n->sk = NULL;
1428 __copy_skb_header(n, skb);
1429
1430 C(len);
1431 C(data_len);
1432 C(mac_len);
1433 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
1434 n->cloned = 1;
1435 n->nohdr = 0;
1436 n->peeked = 0;
1437 C(pfmemalloc);
1438 C(pp_recycle);
1439 n->destructor = NULL;
1440 C(tail);
1441 C(end);
1442 C(head);
1443 C(head_frag);
1444 C(data);
1445 C(truesize);
1446 refcount_set(&n->users, 1);
1447
1448 atomic_inc(&(skb_shinfo(skb)->dataref));
1449 skb->cloned = 1;
1450
1451 return n;
1452 #undef C
1453 }
1454
1455 /**
1456 * alloc_skb_for_msg() - allocate sk_buff to wrap frag list forming a msg
1457 * @first: first sk_buff of the msg
1458 */
alloc_skb_for_msg(struct sk_buff * first)1459 struct sk_buff *alloc_skb_for_msg(struct sk_buff *first)
1460 {
1461 struct sk_buff *n;
1462
1463 n = alloc_skb(0, GFP_ATOMIC);
1464 if (!n)
1465 return NULL;
1466
1467 n->len = first->len;
1468 n->data_len = first->len;
1469 n->truesize = first->truesize;
1470
1471 skb_shinfo(n)->frag_list = first;
1472
1473 __copy_skb_header(n, first);
1474 n->destructor = NULL;
1475
1476 return n;
1477 }
1478 EXPORT_SYMBOL_GPL(alloc_skb_for_msg);
1479
1480 /**
1481 * skb_morph - morph one skb into another
1482 * @dst: the skb to receive the contents
1483 * @src: the skb to supply the contents
1484 *
1485 * This is identical to skb_clone except that the target skb is
1486 * supplied by the user.
1487 *
1488 * The target skb is returned upon exit.
1489 */
skb_morph(struct sk_buff * dst,struct sk_buff * src)1490 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
1491 {
1492 skb_release_all(dst, SKB_CONSUMED, false);
1493 return __skb_clone(dst, src);
1494 }
1495 EXPORT_SYMBOL_GPL(skb_morph);
1496
mm_account_pinned_pages(struct mmpin * mmp,size_t size)1497 int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
1498 {
1499 unsigned long max_pg, num_pg, new_pg, old_pg, rlim;
1500 struct user_struct *user;
1501
1502 if (capable(CAP_IPC_LOCK) || !size)
1503 return 0;
1504
1505 rlim = rlimit(RLIMIT_MEMLOCK);
1506 if (rlim == RLIM_INFINITY)
1507 return 0;
1508
1509 num_pg = (size >> PAGE_SHIFT) + 2; /* worst case */
1510 max_pg = rlim >> PAGE_SHIFT;
1511 user = mmp->user ? : current_user();
1512
1513 old_pg = atomic_long_read(&user->locked_vm);
1514 do {
1515 new_pg = old_pg + num_pg;
1516 if (new_pg > max_pg)
1517 return -ENOBUFS;
1518 } while (!atomic_long_try_cmpxchg(&user->locked_vm, &old_pg, new_pg));
1519
1520 if (!mmp->user) {
1521 mmp->user = get_uid(user);
1522 mmp->num_pg = num_pg;
1523 } else {
1524 mmp->num_pg += num_pg;
1525 }
1526
1527 return 0;
1528 }
1529 EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
1530
mm_unaccount_pinned_pages(struct mmpin * mmp)1531 void mm_unaccount_pinned_pages(struct mmpin *mmp)
1532 {
1533 if (mmp->user) {
1534 atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
1535 free_uid(mmp->user);
1536 }
1537 }
1538 EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
1539
msg_zerocopy_alloc(struct sock * sk,size_t size)1540 static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
1541 {
1542 struct ubuf_info_msgzc *uarg;
1543 struct sk_buff *skb;
1544
1545 WARN_ON_ONCE(!in_task());
1546
1547 skb = sock_omalloc(sk, 0, GFP_KERNEL);
1548 if (!skb)
1549 return NULL;
1550
1551 BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
1552 uarg = (void *)skb->cb;
1553 uarg->mmp.user = NULL;
1554
1555 if (mm_account_pinned_pages(&uarg->mmp, size)) {
1556 kfree_skb(skb);
1557 return NULL;
1558 }
1559
1560 uarg->ubuf.callback = msg_zerocopy_callback;
1561 uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
1562 uarg->len = 1;
1563 uarg->bytelen = size;
1564 uarg->zerocopy = 1;
1565 uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
1566 refcount_set(&uarg->ubuf.refcnt, 1);
1567 sock_hold(sk);
1568
1569 return &uarg->ubuf;
1570 }
1571
skb_from_uarg(struct ubuf_info_msgzc * uarg)1572 static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
1573 {
1574 return container_of((void *)uarg, struct sk_buff, cb);
1575 }
1576
msg_zerocopy_realloc(struct sock * sk,size_t size,struct ubuf_info * uarg)1577 struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
1578 struct ubuf_info *uarg)
1579 {
1580 if (uarg) {
1581 struct ubuf_info_msgzc *uarg_zc;
1582 const u32 byte_limit = 1 << 19; /* limit to a few TSO */
1583 u32 bytelen, next;
1584
1585 /* there might be non MSG_ZEROCOPY users */
1586 if (uarg->callback != msg_zerocopy_callback)
1587 return NULL;
1588
1589 /* realloc only when socket is locked (TCP, UDP cork),
1590 * so uarg->len and sk_zckey access is serialized
1591 */
1592 if (!sock_owned_by_user(sk)) {
1593 WARN_ON_ONCE(1);
1594 return NULL;
1595 }
1596
1597 uarg_zc = uarg_to_msgzc(uarg);
1598 bytelen = uarg_zc->bytelen + size;
1599 if (uarg_zc->len == USHRT_MAX - 1 || bytelen > byte_limit) {
1600 /* TCP can create new skb to attach new uarg */
1601 if (sk->sk_type == SOCK_STREAM)
1602 goto new_alloc;
1603 return NULL;
1604 }
1605
1606 next = (u32)atomic_read(&sk->sk_zckey);
1607 if ((u32)(uarg_zc->id + uarg_zc->len) == next) {
1608 if (mm_account_pinned_pages(&uarg_zc->mmp, size))
1609 return NULL;
1610 uarg_zc->len++;
1611 uarg_zc->bytelen = bytelen;
1612 atomic_set(&sk->sk_zckey, ++next);
1613
1614 /* no extra ref when appending to datagram (MSG_MORE) */
1615 if (sk->sk_type == SOCK_STREAM)
1616 net_zcopy_get(uarg);
1617
1618 return uarg;
1619 }
1620 }
1621
1622 new_alloc:
1623 return msg_zerocopy_alloc(sk, size);
1624 }
1625 EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
1626
skb_zerocopy_notify_extend(struct sk_buff * skb,u32 lo,u16 len)1627 static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
1628 {
1629 struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
1630 u32 old_lo, old_hi;
1631 u64 sum_len;
1632
1633 old_lo = serr->ee.ee_info;
1634 old_hi = serr->ee.ee_data;
1635 sum_len = old_hi - old_lo + 1ULL + len;
1636
1637 if (sum_len >= (1ULL << 32))
1638 return false;
1639
1640 if (lo != old_hi + 1)
1641 return false;
1642
1643 serr->ee.ee_data += len;
1644 return true;
1645 }
1646
__msg_zerocopy_callback(struct ubuf_info_msgzc * uarg)1647 static void __msg_zerocopy_callback(struct ubuf_info_msgzc *uarg)
1648 {
1649 struct sk_buff *tail, *skb = skb_from_uarg(uarg);
1650 struct sock_exterr_skb *serr;
1651 struct sock *sk = skb->sk;
1652 struct sk_buff_head *q;
1653 unsigned long flags;
1654 bool is_zerocopy;
1655 u32 lo, hi;
1656 u16 len;
1657
1658 mm_unaccount_pinned_pages(&uarg->mmp);
1659
1660 /* if !len, there was only 1 call, and it was aborted
1661 * so do not queue a completion notification
1662 */
1663 if (!uarg->len || sock_flag(sk, SOCK_DEAD))
1664 goto release;
1665
1666 len = uarg->len;
1667 lo = uarg->id;
1668 hi = uarg->id + len - 1;
1669 is_zerocopy = uarg->zerocopy;
1670
1671 serr = SKB_EXT_ERR(skb);
1672 memset(serr, 0, sizeof(*serr));
1673 serr->ee.ee_errno = 0;
1674 serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
1675 serr->ee.ee_data = hi;
1676 serr->ee.ee_info = lo;
1677 if (!is_zerocopy)
1678 serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
1679
1680 q = &sk->sk_error_queue;
1681 spin_lock_irqsave(&q->lock, flags);
1682 tail = skb_peek_tail(q);
1683 if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
1684 !skb_zerocopy_notify_extend(tail, lo, len)) {
1685 __skb_queue_tail(q, skb);
1686 skb = NULL;
1687 }
1688 spin_unlock_irqrestore(&q->lock, flags);
1689
1690 sk_error_report(sk);
1691
1692 release:
1693 consume_skb(skb);
1694 sock_put(sk);
1695 }
1696
msg_zerocopy_callback(struct sk_buff * skb,struct ubuf_info * uarg,bool success)1697 void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
1698 bool success)
1699 {
1700 struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
1701
1702 uarg_zc->zerocopy = uarg_zc->zerocopy & success;
1703
1704 if (refcount_dec_and_test(&uarg->refcnt))
1705 __msg_zerocopy_callback(uarg_zc);
1706 }
1707 EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
1708
msg_zerocopy_put_abort(struct ubuf_info * uarg,bool have_uref)1709 void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
1710 {
1711 struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
1712
1713 atomic_dec(&sk->sk_zckey);
1714 uarg_to_msgzc(uarg)->len--;
1715
1716 if (have_uref)
1717 msg_zerocopy_callback(NULL, uarg, true);
1718 }
1719 EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
1720
skb_zerocopy_iter_stream(struct sock * sk,struct sk_buff * skb,struct msghdr * msg,int len,struct ubuf_info * uarg)1721 int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
1722 struct msghdr *msg, int len,
1723 struct ubuf_info *uarg)
1724 {
1725 struct ubuf_info *orig_uarg = skb_zcopy(skb);
1726 int err, orig_len = skb->len;
1727
1728 /* An skb can only point to one uarg. This edge case happens when
1729 * TCP appends to an skb, but zerocopy_realloc triggered a new alloc.
1730 */
1731 if (orig_uarg && uarg != orig_uarg)
1732 return -EEXIST;
1733
1734 err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len);
1735 if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
1736 struct sock *save_sk = skb->sk;
1737
1738 /* Streams do not free skb on error. Reset to prev state. */
1739 iov_iter_revert(&msg->msg_iter, skb->len - orig_len);
1740 skb->sk = sk;
1741 ___pskb_trim(skb, orig_len);
1742 skb->sk = save_sk;
1743 return err;
1744 }
1745
1746 skb_zcopy_set(skb, uarg, NULL);
1747 return skb->len - orig_len;
1748 }
1749 EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
1750
__skb_zcopy_downgrade_managed(struct sk_buff * skb)1751 void __skb_zcopy_downgrade_managed(struct sk_buff *skb)
1752 {
1753 int i;
1754
1755 skb_shinfo(skb)->flags &= ~SKBFL_MANAGED_FRAG_REFS;
1756 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1757 skb_frag_ref(skb, i);
1758 }
1759 EXPORT_SYMBOL_GPL(__skb_zcopy_downgrade_managed);
1760
skb_zerocopy_clone(struct sk_buff * nskb,struct sk_buff * orig,gfp_t gfp_mask)1761 static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
1762 gfp_t gfp_mask)
1763 {
1764 if (skb_zcopy(orig)) {
1765 if (skb_zcopy(nskb)) {
1766 /* !gfp_mask callers are verified to !skb_zcopy(nskb) */
1767 if (!gfp_mask) {
1768 WARN_ON_ONCE(1);
1769 return -ENOMEM;
1770 }
1771 if (skb_uarg(nskb) == skb_uarg(orig))
1772 return 0;
1773 if (skb_copy_ubufs(nskb, GFP_ATOMIC))
1774 return -EIO;
1775 }
1776 skb_zcopy_set(nskb, skb_uarg(orig), NULL);
1777 }
1778 return 0;
1779 }
1780
1781 /**
1782 * skb_copy_ubufs - copy userspace skb frags buffers to kernel
1783 * @skb: the skb to modify
1784 * @gfp_mask: allocation priority
1785 *
1786 * This must be called on skb with SKBFL_ZEROCOPY_ENABLE.
1787 * It will copy all frags into kernel and drop the reference
1788 * to userspace pages.
1789 *
1790 * If this function is called from an interrupt gfp_mask() must be
1791 * %GFP_ATOMIC.
1792 *
1793 * Returns 0 on success or a negative error code on failure
1794 * to allocate kernel memory to copy to.
1795 */
skb_copy_ubufs(struct sk_buff * skb,gfp_t gfp_mask)1796 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
1797 {
1798 int num_frags = skb_shinfo(skb)->nr_frags;
1799 struct page *page, *head = NULL;
1800 int i, order, psize, new_frags;
1801 u32 d_off;
1802
1803 if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
1804 return -EINVAL;
1805
1806 if (!num_frags)
1807 goto release;
1808
1809 /* We might have to allocate high order pages, so compute what minimum
1810 * page order is needed.
1811 */
1812 order = 0;
1813 while ((PAGE_SIZE << order) * MAX_SKB_FRAGS < __skb_pagelen(skb))
1814 order++;
1815 psize = (PAGE_SIZE << order);
1816
1817 new_frags = (__skb_pagelen(skb) + psize - 1) >> (PAGE_SHIFT + order);
1818 for (i = 0; i < new_frags; i++) {
1819 page = alloc_pages(gfp_mask | __GFP_COMP, order);
1820 if (!page) {
1821 while (head) {
1822 struct page *next = (struct page *)page_private(head);
1823 put_page(head);
1824 head = next;
1825 }
1826 return -ENOMEM;
1827 }
1828 set_page_private(page, (unsigned long)head);
1829 head = page;
1830 }
1831
1832 page = head;
1833 d_off = 0;
1834 for (i = 0; i < num_frags; i++) {
1835 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1836 u32 p_off, p_len, copied;
1837 struct page *p;
1838 u8 *vaddr;
1839
1840 skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
1841 p, p_off, p_len, copied) {
1842 u32 copy, done = 0;
1843 vaddr = kmap_atomic(p);
1844
1845 while (done < p_len) {
1846 if (d_off == psize) {
1847 d_off = 0;
1848 page = (struct page *)page_private(page);
1849 }
1850 copy = min_t(u32, psize - d_off, p_len - done);
1851 memcpy(page_address(page) + d_off,
1852 vaddr + p_off + done, copy);
1853 done += copy;
1854 d_off += copy;
1855 }
1856 kunmap_atomic(vaddr);
1857 }
1858 }
1859
1860 /* skb frags release userspace buffers */
1861 for (i = 0; i < num_frags; i++)
1862 skb_frag_unref(skb, i);
1863
1864 /* skb frags point to kernel buffers */
1865 for (i = 0; i < new_frags - 1; i++) {
1866 __skb_fill_page_desc(skb, i, head, 0, psize);
1867 head = (struct page *)page_private(head);
1868 }
1869 __skb_fill_page_desc(skb, new_frags - 1, head, 0, d_off);
1870 skb_shinfo(skb)->nr_frags = new_frags;
1871
1872 release:
1873 skb_zcopy_clear(skb, false);
1874 return 0;
1875 }
1876 EXPORT_SYMBOL_GPL(skb_copy_ubufs);
1877
1878 /**
1879 * skb_clone - duplicate an sk_buff
1880 * @skb: buffer to clone
1881 * @gfp_mask: allocation priority
1882 *
1883 * Duplicate an &sk_buff. The new one is not owned by a socket. Both
1884 * copies share the same packet data but not structure. The new
1885 * buffer has a reference count of 1. If the allocation fails the
1886 * function returns %NULL otherwise the new buffer is returned.
1887 *
1888 * If this function is called from an interrupt gfp_mask() must be
1889 * %GFP_ATOMIC.
1890 */
1891
skb_clone(struct sk_buff * skb,gfp_t gfp_mask)1892 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
1893 {
1894 struct sk_buff_fclones *fclones = container_of(skb,
1895 struct sk_buff_fclones,
1896 skb1);
1897 struct sk_buff *n;
1898
1899 if (skb_orphan_frags(skb, gfp_mask))
1900 return NULL;
1901
1902 if (skb->fclone == SKB_FCLONE_ORIG &&
1903 refcount_read(&fclones->fclone_ref) == 1) {
1904 n = &fclones->skb2;
1905 refcount_set(&fclones->fclone_ref, 2);
1906 n->fclone = SKB_FCLONE_CLONE;
1907 } else {
1908 if (skb_pfmemalloc(skb))
1909 gfp_mask |= __GFP_MEMALLOC;
1910
1911 n = kmem_cache_alloc(skbuff_cache, gfp_mask);
1912 if (!n)
1913 return NULL;
1914
1915 n->fclone = SKB_FCLONE_UNAVAILABLE;
1916 }
1917
1918 return __skb_clone(n, skb);
1919 }
1920 EXPORT_SYMBOL(skb_clone);
1921
skb_headers_offset_update(struct sk_buff * skb,int off)1922 void skb_headers_offset_update(struct sk_buff *skb, int off)
1923 {
1924 /* Only adjust this if it actually is csum_start rather than csum */
1925 if (skb->ip_summed == CHECKSUM_PARTIAL)
1926 skb->csum_start += off;
1927 /* {transport,network,mac}_header and tail are relative to skb->head */
1928 skb->transport_header += off;
1929 skb->network_header += off;
1930 if (skb_mac_header_was_set(skb))
1931 skb->mac_header += off;
1932 skb->inner_transport_header += off;
1933 skb->inner_network_header += off;
1934 skb->inner_mac_header += off;
1935 }
1936 EXPORT_SYMBOL(skb_headers_offset_update);
1937
skb_copy_header(struct sk_buff * new,const struct sk_buff * old)1938 void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
1939 {
1940 __copy_skb_header(new, old);
1941
1942 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
1943 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
1944 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
1945 }
1946 EXPORT_SYMBOL(skb_copy_header);
1947
skb_alloc_rx_flag(const struct sk_buff * skb)1948 static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
1949 {
1950 if (skb_pfmemalloc(skb))
1951 return SKB_ALLOC_RX;
1952 return 0;
1953 }
1954
1955 /**
1956 * skb_copy - create private copy of an sk_buff
1957 * @skb: buffer to copy
1958 * @gfp_mask: allocation priority
1959 *
1960 * Make a copy of both an &sk_buff and its data. This is used when the
1961 * caller wishes to modify the data and needs a private copy of the
1962 * data to alter. Returns %NULL on failure or the pointer to the buffer
1963 * on success. The returned buffer has a reference count of 1.
1964 *
1965 * As by-product this function converts non-linear &sk_buff to linear
1966 * one, so that &sk_buff becomes completely private and caller is allowed
1967 * to modify all the data of returned buffer. This means that this
1968 * function is not recommended for use in circumstances when only
1969 * header is going to be modified. Use pskb_copy() instead.
1970 */
1971
skb_copy(const struct sk_buff * skb,gfp_t gfp_mask)1972 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
1973 {
1974 int headerlen = skb_headroom(skb);
1975 unsigned int size = skb_end_offset(skb) + skb->data_len;
1976 struct sk_buff *n = __alloc_skb(size, gfp_mask,
1977 skb_alloc_rx_flag(skb), NUMA_NO_NODE);
1978
1979 if (!n)
1980 return NULL;
1981
1982 /* Set the data pointer */
1983 skb_reserve(n, headerlen);
1984 /* Set the tail pointer and length */
1985 skb_put(n, skb->len);
1986
1987 BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
1988
1989 skb_copy_header(n, skb);
1990 return n;
1991 }
1992 EXPORT_SYMBOL(skb_copy);
1993
1994 /**
1995 * __pskb_copy_fclone - create copy of an sk_buff with private head.
1996 * @skb: buffer to copy
1997 * @headroom: headroom of new skb
1998 * @gfp_mask: allocation priority
1999 * @fclone: if true allocate the copy of the skb from the fclone
2000 * cache instead of the head cache; it is recommended to set this
2001 * to true for the cases where the copy will likely be cloned
2002 *
2003 * Make a copy of both an &sk_buff and part of its data, located
2004 * in header. Fragmented data remain shared. This is used when
2005 * the caller wishes to modify only header of &sk_buff and needs
2006 * private copy of the header to alter. Returns %NULL on failure
2007 * or the pointer to the buffer on success.
2008 * The returned buffer has a reference count of 1.
2009 */
2010
__pskb_copy_fclone(struct sk_buff * skb,int headroom,gfp_t gfp_mask,bool fclone)2011 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
2012 gfp_t gfp_mask, bool fclone)
2013 {
2014 unsigned int size = skb_headlen(skb) + headroom;
2015 int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
2016 struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
2017
2018 if (!n)
2019 goto out;
2020
2021 /* Set the data pointer */
2022 skb_reserve(n, headroom);
2023 /* Set the tail pointer and length */
2024 skb_put(n, skb_headlen(skb));
2025 /* Copy the bytes */
2026 skb_copy_from_linear_data(skb, n->data, n->len);
2027
2028 n->truesize += skb->data_len;
2029 n->data_len = skb->data_len;
2030 n->len = skb->len;
2031
2032 if (skb_shinfo(skb)->nr_frags) {
2033 int i;
2034
2035 if (skb_orphan_frags(skb, gfp_mask) ||
2036 skb_zerocopy_clone(n, skb, gfp_mask)) {
2037 kfree_skb(n);
2038 n = NULL;
2039 goto out;
2040 }
2041 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2042 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
2043 skb_frag_ref(skb, i);
2044 }
2045 skb_shinfo(n)->nr_frags = i;
2046 }
2047
2048 if (skb_has_frag_list(skb)) {
2049 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
2050 skb_clone_fraglist(n);
2051 }
2052
2053 skb_copy_header(n, skb);
2054 out:
2055 return n;
2056 }
2057 EXPORT_SYMBOL(__pskb_copy_fclone);
2058
2059 /**
2060 * pskb_expand_head - reallocate header of &sk_buff
2061 * @skb: buffer to reallocate
2062 * @nhead: room to add at head
2063 * @ntail: room to add at tail
2064 * @gfp_mask: allocation priority
2065 *
2066 * Expands (or creates identical copy, if @nhead and @ntail are zero)
2067 * header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
2068 * reference count of 1. Returns zero in the case of success or error,
2069 * if expansion failed. In the last case, &sk_buff is not changed.
2070 *
2071 * All the pointers pointing into skb header may change and must be
2072 * reloaded after call to this function.
2073 */
2074
pskb_expand_head(struct sk_buff * skb,int nhead,int ntail,gfp_t gfp_mask)2075 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
2076 gfp_t gfp_mask)
2077 {
2078 unsigned int osize = skb_end_offset(skb);
2079 unsigned int size = osize + nhead + ntail;
2080 long off;
2081 u8 *data;
2082 int i;
2083
2084 BUG_ON(nhead < 0);
2085
2086 BUG_ON(skb_shared(skb));
2087
2088 skb_zcopy_downgrade_managed(skb);
2089
2090 if (skb_pfmemalloc(skb))
2091 gfp_mask |= __GFP_MEMALLOC;
2092
2093 data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
2094 if (!data)
2095 goto nodata;
2096 size = SKB_WITH_OVERHEAD(size);
2097
2098 /* Copy only real data... and, alas, header. This should be
2099 * optimized for the cases when header is void.
2100 */
2101 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
2102
2103 memcpy((struct skb_shared_info *)(data + size),
2104 skb_shinfo(skb),
2105 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
2106
2107 /*
2108 * if shinfo is shared we must drop the old head gracefully, but if it
2109 * is not we can just drop the old head and let the existing refcount
2110 * be since all we did is relocate the values
2111 */
2112 if (skb_cloned(skb)) {
2113 if (skb_orphan_frags(skb, gfp_mask))
2114 goto nofrags;
2115 if (skb_zcopy(skb))
2116 refcount_inc(&skb_uarg(skb)->refcnt);
2117 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2118 skb_frag_ref(skb, i);
2119
2120 if (skb_has_frag_list(skb))
2121 skb_clone_fraglist(skb);
2122
2123 skb_release_data(skb, SKB_CONSUMED, false);
2124 } else {
2125 skb_free_head(skb, false);
2126 }
2127 off = (data + nhead) - skb->head;
2128
2129 skb->head = data;
2130 skb->head_frag = 0;
2131 skb->data += off;
2132
2133 skb_set_end_offset(skb, size);
2134 #ifdef NET_SKBUFF_DATA_USES_OFFSET
2135 off = nhead;
2136 #endif
2137 skb->tail += off;
2138 skb_headers_offset_update(skb, nhead);
2139 skb->cloned = 0;
2140 skb->hdr_len = 0;
2141 skb->nohdr = 0;
2142 atomic_set(&skb_shinfo(skb)->dataref, 1);
2143
2144 skb_metadata_clear(skb);
2145
2146 /* It is not generally safe to change skb->truesize.
2147 * For the moment, we really care of rx path, or
2148 * when skb is orphaned (not attached to a socket).
2149 */
2150 if (!skb->sk || skb->destructor == sock_edemux)
2151 skb->truesize += size - osize;
2152
2153 return 0;
2154
2155 nofrags:
2156 skb_kfree_head(data, size);
2157 nodata:
2158 return -ENOMEM;
2159 }
2160 EXPORT_SYMBOL(pskb_expand_head);
2161
2162 /* Make private copy of skb with writable head and some headroom */
2163
skb_realloc_headroom(struct sk_buff * skb,unsigned int headroom)2164 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
2165 {
2166 struct sk_buff *skb2;
2167 int delta = headroom - skb_headroom(skb);
2168
2169 if (delta <= 0)
2170 skb2 = pskb_copy(skb, GFP_ATOMIC);
2171 else {
2172 skb2 = skb_clone(skb, GFP_ATOMIC);
2173 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
2174 GFP_ATOMIC)) {
2175 kfree_skb(skb2);
2176 skb2 = NULL;
2177 }
2178 }
2179 return skb2;
2180 }
2181 EXPORT_SYMBOL(skb_realloc_headroom);
2182
2183 /* Note: We plan to rework this in linux-6.4 */
__skb_unclone_keeptruesize(struct sk_buff * skb,gfp_t pri)2184 int __skb_unclone_keeptruesize(struct sk_buff *skb, gfp_t pri)
2185 {
2186 unsigned int saved_end_offset, saved_truesize;
2187 struct skb_shared_info *shinfo;
2188 int res;
2189
2190 saved_end_offset = skb_end_offset(skb);
2191 saved_truesize = skb->truesize;
2192
2193 res = pskb_expand_head(skb, 0, 0, pri);
2194 if (res)
2195 return res;
2196
2197 skb->truesize = saved_truesize;
2198
2199 if (likely(skb_end_offset(skb) == saved_end_offset))
2200 return 0;
2201
2202 /* We can not change skb->end if the original or new value
2203 * is SKB_SMALL_HEAD_HEADROOM, as it might break skb_kfree_head().
2204 */
2205 if (saved_end_offset == SKB_SMALL_HEAD_HEADROOM ||
2206 skb_end_offset(skb) == SKB_SMALL_HEAD_HEADROOM) {
2207 /* We think this path should not be taken.
2208 * Add a temporary trace to warn us just in case.
2209 */
2210 pr_err_once("__skb_unclone_keeptruesize() skb_end_offset() %u -> %u\n",
2211 saved_end_offset, skb_end_offset(skb));
2212 WARN_ON_ONCE(1);
2213 return 0;
2214 }
2215
2216 shinfo = skb_shinfo(skb);
2217
2218 /* We are about to change back skb->end,
2219 * we need to move skb_shinfo() to its new location.
2220 */
2221 memmove(skb->head + saved_end_offset,
2222 shinfo,
2223 offsetof(struct skb_shared_info, frags[shinfo->nr_frags]));
2224
2225 skb_set_end_offset(skb, saved_end_offset);
2226
2227 return 0;
2228 }
2229
2230 /**
2231 * skb_expand_head - reallocate header of &sk_buff
2232 * @skb: buffer to reallocate
2233 * @headroom: needed headroom
2234 *
2235 * Unlike skb_realloc_headroom, this one does not allocate a new skb
2236 * if possible; copies skb->sk to new skb as needed
2237 * and frees original skb in case of failures.
2238 *
2239 * It expect increased headroom and generates warning otherwise.
2240 */
2241
skb_expand_head(struct sk_buff * skb,unsigned int headroom)2242 struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom)
2243 {
2244 int delta = headroom - skb_headroom(skb);
2245 int osize = skb_end_offset(skb);
2246 struct sock *sk = skb->sk;
2247
2248 if (WARN_ONCE(delta <= 0,
2249 "%s is expecting an increase in the headroom", __func__))
2250 return skb;
2251
2252 delta = SKB_DATA_ALIGN(delta);
2253 /* pskb_expand_head() might crash, if skb is shared. */
2254 if (skb_shared(skb) || !is_skb_wmem(skb)) {
2255 struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
2256
2257 if (unlikely(!nskb))
2258 goto fail;
2259
2260 if (sk)
2261 skb_set_owner_w(nskb, sk);
2262 consume_skb(skb);
2263 skb = nskb;
2264 }
2265 if (pskb_expand_head(skb, delta, 0, GFP_ATOMIC))
2266 goto fail;
2267
2268 if (sk && is_skb_wmem(skb)) {
2269 delta = skb_end_offset(skb) - osize;
2270 refcount_add(delta, &sk->sk_wmem_alloc);
2271 skb->truesize += delta;
2272 }
2273 return skb;
2274
2275 fail:
2276 kfree_skb(skb);
2277 return NULL;
2278 }
2279 EXPORT_SYMBOL(skb_expand_head);
2280
2281 /**
2282 * skb_copy_expand - copy and expand sk_buff
2283 * @skb: buffer to copy
2284 * @newheadroom: new free bytes at head
2285 * @newtailroom: new free bytes at tail
2286 * @gfp_mask: allocation priority
2287 *
2288 * Make a copy of both an &sk_buff and its data and while doing so
2289 * allocate additional space.
2290 *
2291 * This is used when the caller wishes to modify the data and needs a
2292 * private copy of the data to alter as well as more space for new fields.
2293 * Returns %NULL on failure or the pointer to the buffer
2294 * on success. The returned buffer has a reference count of 1.
2295 *
2296 * You must pass %GFP_ATOMIC as the allocation priority if this function
2297 * is called from an interrupt.
2298 */
skb_copy_expand(const struct sk_buff * skb,int newheadroom,int newtailroom,gfp_t gfp_mask)2299 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
2300 int newheadroom, int newtailroom,
2301 gfp_t gfp_mask)
2302 {
2303 /*
2304 * Allocate the copy buffer
2305 */
2306 struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
2307 gfp_mask, skb_alloc_rx_flag(skb),
2308 NUMA_NO_NODE);
2309 int oldheadroom = skb_headroom(skb);
2310 int head_copy_len, head_copy_off;
2311
2312 if (!n)
2313 return NULL;
2314
2315 skb_reserve(n, newheadroom);
2316
2317 /* Set the tail pointer and length */
2318 skb_put(n, skb->len);
2319
2320 head_copy_len = oldheadroom;
2321 head_copy_off = 0;
2322 if (newheadroom <= head_copy_len)
2323 head_copy_len = newheadroom;
2324 else
2325 head_copy_off = newheadroom - head_copy_len;
2326
2327 /* Copy the linear header and data. */
2328 BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
2329 skb->len + head_copy_len));
2330
2331 skb_copy_header(n, skb);
2332
2333 skb_headers_offset_update(n, newheadroom - oldheadroom);
2334
2335 return n;
2336 }
2337 EXPORT_SYMBOL(skb_copy_expand);
2338
2339 /**
2340 * __skb_pad - zero pad the tail of an skb
2341 * @skb: buffer to pad
2342 * @pad: space to pad
2343 * @free_on_error: free buffer on error
2344 *
2345 * Ensure that a buffer is followed by a padding area that is zero
2346 * filled. Used by network drivers which may DMA or transfer data
2347 * beyond the buffer end onto the wire.
2348 *
2349 * May return error in out of memory cases. The skb is freed on error
2350 * if @free_on_error is true.
2351 */
2352
__skb_pad(struct sk_buff * skb,int pad,bool free_on_error)2353 int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
2354 {
2355 int err;
2356 int ntail;
2357
2358 /* If the skbuff is non linear tailroom is always zero.. */
2359 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
2360 memset(skb->data+skb->len, 0, pad);
2361 return 0;
2362 }
2363
2364 ntail = skb->data_len + pad - (skb->end - skb->tail);
2365 if (likely(skb_cloned(skb) || ntail > 0)) {
2366 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
2367 if (unlikely(err))
2368 goto free_skb;
2369 }
2370
2371 /* FIXME: The use of this function with non-linear skb's really needs
2372 * to be audited.
2373 */
2374 err = skb_linearize(skb);
2375 if (unlikely(err))
2376 goto free_skb;
2377
2378 memset(skb->data + skb->len, 0, pad);
2379 return 0;
2380
2381 free_skb:
2382 if (free_on_error)
2383 kfree_skb(skb);
2384 return err;
2385 }
2386 EXPORT_SYMBOL(__skb_pad);
2387
2388 /**
2389 * pskb_put - add data to the tail of a potentially fragmented buffer
2390 * @skb: start of the buffer to use
2391 * @tail: tail fragment of the buffer to use
2392 * @len: amount of data to add
2393 *
2394 * This function extends the used data area of the potentially
2395 * fragmented buffer. @tail must be the last fragment of @skb -- or
2396 * @skb itself. If this would exceed the total buffer size the kernel
2397 * will panic. A pointer to the first byte of the extra data is
2398 * returned.
2399 */
2400
pskb_put(struct sk_buff * skb,struct sk_buff * tail,int len)2401 void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
2402 {
2403 if (tail != skb) {
2404 skb->data_len += len;
2405 skb->len += len;
2406 }
2407 return skb_put(tail, len);
2408 }
2409 EXPORT_SYMBOL_GPL(pskb_put);
2410
2411 /**
2412 * skb_put - add data to a buffer
2413 * @skb: buffer to use
2414 * @len: amount of data to add
2415 *
2416 * This function extends the used data area of the buffer. If this would
2417 * exceed the total buffer size the kernel will panic. A pointer to the
2418 * first byte of the extra data is returned.
2419 */
skb_put(struct sk_buff * skb,unsigned int len)2420 void *skb_put(struct sk_buff *skb, unsigned int len)
2421 {
2422 void *tmp = skb_tail_pointer(skb);
2423 SKB_LINEAR_ASSERT(skb);
2424 skb->tail += len;
2425 skb->len += len;
2426 if (unlikely(skb->tail > skb->end))
2427 skb_over_panic(skb, len, __builtin_return_address(0));
2428 return tmp;
2429 }
2430 EXPORT_SYMBOL(skb_put);
2431
2432 /**
2433 * skb_push - add data to the start of a buffer
2434 * @skb: buffer to use
2435 * @len: amount of data to add
2436 *
2437 * This function extends the used data area of the buffer at the buffer
2438 * start. If this would exceed the total buffer headroom the kernel will
2439 * panic. A pointer to the first byte of the extra data is returned.
2440 */
skb_push(struct sk_buff * skb,unsigned int len)2441 void *skb_push(struct sk_buff *skb, unsigned int len)
2442 {
2443 skb->data -= len;
2444 skb->len += len;
2445 if (unlikely(skb->data < skb->head))
2446 skb_under_panic(skb, len, __builtin_return_address(0));
2447 return skb->data;
2448 }
2449 EXPORT_SYMBOL(skb_push);
2450
2451 /**
2452 * skb_pull - remove data from the start of a buffer
2453 * @skb: buffer to use
2454 * @len: amount of data to remove
2455 *
2456 * This function removes data from the start of a buffer, returning
2457 * the memory to the headroom. A pointer to the next data in the buffer
2458 * is returned. Once the data has been pulled future pushes will overwrite
2459 * the old data.
2460 */
skb_pull(struct sk_buff * skb,unsigned int len)2461 void *skb_pull(struct sk_buff *skb, unsigned int len)
2462 {
2463 return skb_pull_inline(skb, len);
2464 }
2465 EXPORT_SYMBOL(skb_pull);
2466
2467 /**
2468 * skb_pull_data - remove data from the start of a buffer returning its
2469 * original position.
2470 * @skb: buffer to use
2471 * @len: amount of data to remove
2472 *
2473 * This function removes data from the start of a buffer, returning
2474 * the memory to the headroom. A pointer to the original data in the buffer
2475 * is returned after checking if there is enough data to pull. Once the
2476 * data has been pulled future pushes will overwrite the old data.
2477 */
skb_pull_data(struct sk_buff * skb,size_t len)2478 void *skb_pull_data(struct sk_buff *skb, size_t len)
2479 {
2480 void *data = skb->data;
2481
2482 if (skb->len < len)
2483 return NULL;
2484
2485 skb_pull(skb, len);
2486
2487 return data;
2488 }
2489 EXPORT_SYMBOL(skb_pull_data);
2490
2491 /**
2492 * skb_trim - remove end from a buffer
2493 * @skb: buffer to alter
2494 * @len: new length
2495 *
2496 * Cut the length of a buffer down by removing data from the tail. If
2497 * the buffer is already under the length specified it is not modified.
2498 * The skb must be linear.
2499 */
skb_trim(struct sk_buff * skb,unsigned int len)2500 void skb_trim(struct sk_buff *skb, unsigned int len)
2501 {
2502 if (skb->len > len)
2503 __skb_trim(skb, len);
2504 }
2505 EXPORT_SYMBOL(skb_trim);
2506
2507 /* Trims skb to length len. It can change skb pointers.
2508 */
2509
___pskb_trim(struct sk_buff * skb,unsigned int len)2510 int ___pskb_trim(struct sk_buff *skb, unsigned int len)
2511 {
2512 struct sk_buff **fragp;
2513 struct sk_buff *frag;
2514 int offset = skb_headlen(skb);
2515 int nfrags = skb_shinfo(skb)->nr_frags;
2516 int i;
2517 int err;
2518
2519 if (skb_cloned(skb) &&
2520 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
2521 return err;
2522
2523 i = 0;
2524 if (offset >= len)
2525 goto drop_pages;
2526
2527 for (; i < nfrags; i++) {
2528 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2529
2530 if (end < len) {
2531 offset = end;
2532 continue;
2533 }
2534
2535 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
2536
2537 drop_pages:
2538 skb_shinfo(skb)->nr_frags = i;
2539
2540 for (; i < nfrags; i++)
2541 skb_frag_unref(skb, i);
2542
2543 if (skb_has_frag_list(skb))
2544 skb_drop_fraglist(skb);
2545 goto done;
2546 }
2547
2548 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
2549 fragp = &frag->next) {
2550 int end = offset + frag->len;
2551
2552 if (skb_shared(frag)) {
2553 struct sk_buff *nfrag;
2554
2555 nfrag = skb_clone(frag, GFP_ATOMIC);
2556 if (unlikely(!nfrag))
2557 return -ENOMEM;
2558
2559 nfrag->next = frag->next;
2560 consume_skb(frag);
2561 frag = nfrag;
2562 *fragp = frag;
2563 }
2564
2565 if (end < len) {
2566 offset = end;
2567 continue;
2568 }
2569
2570 if (end > len &&
2571 unlikely((err = pskb_trim(frag, len - offset))))
2572 return err;
2573
2574 if (frag->next)
2575 skb_drop_list(&frag->next);
2576 break;
2577 }
2578
2579 done:
2580 if (len > skb_headlen(skb)) {
2581 skb->data_len -= skb->len - len;
2582 skb->len = len;
2583 } else {
2584 skb->len = len;
2585 skb->data_len = 0;
2586 skb_set_tail_pointer(skb, len);
2587 }
2588
2589 if (!skb->sk || skb->destructor == sock_edemux)
2590 skb_condense(skb);
2591 return 0;
2592 }
2593 EXPORT_SYMBOL(___pskb_trim);
2594
2595 /* Note : use pskb_trim_rcsum() instead of calling this directly
2596 */
pskb_trim_rcsum_slow(struct sk_buff * skb,unsigned int len)2597 int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
2598 {
2599 if (skb->ip_summed == CHECKSUM_COMPLETE) {
2600 int delta = skb->len - len;
2601
2602 skb->csum = csum_block_sub(skb->csum,
2603 skb_checksum(skb, len, delta, 0),
2604 len);
2605 } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
2606 int hdlen = (len > skb_headlen(skb)) ? skb_headlen(skb) : len;
2607 int offset = skb_checksum_start_offset(skb) + skb->csum_offset;
2608
2609 if (offset + sizeof(__sum16) > hdlen)
2610 return -EINVAL;
2611 }
2612 return __pskb_trim(skb, len);
2613 }
2614 EXPORT_SYMBOL(pskb_trim_rcsum_slow);
2615
2616 /**
2617 * __pskb_pull_tail - advance tail of skb header
2618 * @skb: buffer to reallocate
2619 * @delta: number of bytes to advance tail
2620 *
2621 * The function makes a sense only on a fragmented &sk_buff,
2622 * it expands header moving its tail forward and copying necessary
2623 * data from fragmented part.
2624 *
2625 * &sk_buff MUST have reference count of 1.
2626 *
2627 * Returns %NULL (and &sk_buff does not change) if pull failed
2628 * or value of new tail of skb in the case of success.
2629 *
2630 * All the pointers pointing into skb header may change and must be
2631 * reloaded after call to this function.
2632 */
2633
2634 /* Moves tail of skb head forward, copying data from fragmented part,
2635 * when it is necessary.
2636 * 1. It may fail due to malloc failure.
2637 * 2. It may change skb pointers.
2638 *
2639 * It is pretty complicated. Luckily, it is called only in exceptional cases.
2640 */
__pskb_pull_tail(struct sk_buff * skb,int delta)2641 void *__pskb_pull_tail(struct sk_buff *skb, int delta)
2642 {
2643 /* If skb has not enough free space at tail, get new one
2644 * plus 128 bytes for future expansions. If we have enough
2645 * room at tail, reallocate without expansion only if skb is cloned.
2646 */
2647 int i, k, eat = (skb->tail + delta) - skb->end;
2648
2649 if (eat > 0 || skb_cloned(skb)) {
2650 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
2651 GFP_ATOMIC))
2652 return NULL;
2653 }
2654
2655 BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
2656 skb_tail_pointer(skb), delta));
2657
2658 /* Optimization: no fragments, no reasons to preestimate
2659 * size of pulled pages. Superb.
2660 */
2661 if (!skb_has_frag_list(skb))
2662 goto pull_pages;
2663
2664 /* Estimate size of pulled pages. */
2665 eat = delta;
2666 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2667 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2668
2669 if (size >= eat)
2670 goto pull_pages;
2671 eat -= size;
2672 }
2673
2674 /* If we need update frag list, we are in troubles.
2675 * Certainly, it is possible to add an offset to skb data,
2676 * but taking into account that pulling is expected to
2677 * be very rare operation, it is worth to fight against
2678 * further bloating skb head and crucify ourselves here instead.
2679 * Pure masohism, indeed. 8)8)
2680 */
2681 if (eat) {
2682 struct sk_buff *list = skb_shinfo(skb)->frag_list;
2683 struct sk_buff *clone = NULL;
2684 struct sk_buff *insp = NULL;
2685
2686 do {
2687 if (list->len <= eat) {
2688 /* Eaten as whole. */
2689 eat -= list->len;
2690 list = list->next;
2691 insp = list;
2692 } else {
2693 /* Eaten partially. */
2694 if (skb_is_gso(skb) && !list->head_frag &&
2695 skb_headlen(list))
2696 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
2697
2698 if (skb_shared(list)) {
2699 /* Sucks! We need to fork list. :-( */
2700 clone = skb_clone(list, GFP_ATOMIC);
2701 if (!clone)
2702 return NULL;
2703 insp = list->next;
2704 list = clone;
2705 } else {
2706 /* This may be pulled without
2707 * problems. */
2708 insp = list;
2709 }
2710 if (!pskb_pull(list, eat)) {
2711 kfree_skb(clone);
2712 return NULL;
2713 }
2714 break;
2715 }
2716 } while (eat);
2717
2718 /* Free pulled out fragments. */
2719 while ((list = skb_shinfo(skb)->frag_list) != insp) {
2720 skb_shinfo(skb)->frag_list = list->next;
2721 consume_skb(list);
2722 }
2723 /* And insert new clone at head. */
2724 if (clone) {
2725 clone->next = list;
2726 skb_shinfo(skb)->frag_list = clone;
2727 }
2728 }
2729 /* Success! Now we may commit changes to skb data. */
2730
2731 pull_pages:
2732 eat = delta;
2733 k = 0;
2734 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2735 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2736
2737 if (size <= eat) {
2738 skb_frag_unref(skb, i);
2739 eat -= size;
2740 } else {
2741 skb_frag_t *frag = &skb_shinfo(skb)->frags[k];
2742
2743 *frag = skb_shinfo(skb)->frags[i];
2744 if (eat) {
2745 skb_frag_off_add(frag, eat);
2746 skb_frag_size_sub(frag, eat);
2747 if (!i)
2748 goto end;
2749 eat = 0;
2750 }
2751 k++;
2752 }
2753 }
2754 skb_shinfo(skb)->nr_frags = k;
2755
2756 end:
2757 skb->tail += delta;
2758 skb->data_len -= delta;
2759
2760 if (!skb->data_len)
2761 skb_zcopy_clear(skb, false);
2762
2763 return skb_tail_pointer(skb);
2764 }
2765 EXPORT_SYMBOL(__pskb_pull_tail);
2766
2767 /**
2768 * skb_copy_bits - copy bits from skb to kernel buffer
2769 * @skb: source skb
2770 * @offset: offset in source
2771 * @to: destination buffer
2772 * @len: number of bytes to copy
2773 *
2774 * Copy the specified number of bytes from the source skb to the
2775 * destination buffer.
2776 *
2777 * CAUTION ! :
2778 * If its prototype is ever changed,
2779 * check arch/{*}/net/{*}.S files,
2780 * since it is called from BPF assembly code.
2781 */
skb_copy_bits(const struct sk_buff * skb,int offset,void * to,int len)2782 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
2783 {
2784 int start = skb_headlen(skb);
2785 struct sk_buff *frag_iter;
2786 int i, copy;
2787
2788 if (offset > (int)skb->len - len)
2789 goto fault;
2790
2791 /* Copy header. */
2792 if ((copy = start - offset) > 0) {
2793 if (copy > len)
2794 copy = len;
2795 skb_copy_from_linear_data_offset(skb, offset, to, copy);
2796 if ((len -= copy) == 0)
2797 return 0;
2798 offset += copy;
2799 to += copy;
2800 }
2801
2802 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2803 int end;
2804 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
2805
2806 WARN_ON(start > offset + len);
2807
2808 end = start + skb_frag_size(f);
2809 if ((copy = end - offset) > 0) {
2810 u32 p_off, p_len, copied;
2811 struct page *p;
2812 u8 *vaddr;
2813
2814 if (copy > len)
2815 copy = len;
2816
2817 skb_frag_foreach_page(f,
2818 skb_frag_off(f) + offset - start,
2819 copy, p, p_off, p_len, copied) {
2820 vaddr = kmap_atomic(p);
2821 memcpy(to + copied, vaddr + p_off, p_len);
2822 kunmap_atomic(vaddr);
2823 }
2824
2825 if ((len -= copy) == 0)
2826 return 0;
2827 offset += copy;
2828 to += copy;
2829 }
2830 start = end;
2831 }
2832
2833 skb_walk_frags(skb, frag_iter) {
2834 int end;
2835
2836 WARN_ON(start > offset + len);
2837
2838 end = start + frag_iter->len;
2839 if ((copy = end - offset) > 0) {
2840 if (copy > len)
2841 copy = len;
2842 if (skb_copy_bits(frag_iter, offset - start, to, copy))
2843 goto fault;
2844 if ((len -= copy) == 0)
2845 return 0;
2846 offset += copy;
2847 to += copy;
2848 }
2849 start = end;
2850 }
2851
2852 if (!len)
2853 return 0;
2854
2855 fault:
2856 return -EFAULT;
2857 }
2858 EXPORT_SYMBOL(skb_copy_bits);
2859
2860 /*
2861 * Callback from splice_to_pipe(), if we need to release some pages
2862 * at the end of the spd in case we error'ed out in filling the pipe.
2863 */
sock_spd_release(struct splice_pipe_desc * spd,unsigned int i)2864 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
2865 {
2866 put_page(spd->pages[i]);
2867 }
2868
linear_to_page(struct page * page,unsigned int * len,unsigned int * offset,struct sock * sk)2869 static struct page *linear_to_page(struct page *page, unsigned int *len,
2870 unsigned int *offset,
2871 struct sock *sk)
2872 {
2873 struct page_frag *pfrag = sk_page_frag(sk);
2874
2875 if (!sk_page_frag_refill(sk, pfrag))
2876 return NULL;
2877
2878 *len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
2879
2880 memcpy(page_address(pfrag->page) + pfrag->offset,
2881 page_address(page) + *offset, *len);
2882 *offset = pfrag->offset;
2883 pfrag->offset += *len;
2884
2885 return pfrag->page;
2886 }
2887
spd_can_coalesce(const struct splice_pipe_desc * spd,struct page * page,unsigned int offset)2888 static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
2889 struct page *page,
2890 unsigned int offset)
2891 {
2892 return spd->nr_pages &&
2893 spd->pages[spd->nr_pages - 1] == page &&
2894 (spd->partial[spd->nr_pages - 1].offset +
2895 spd->partial[spd->nr_pages - 1].len == offset);
2896 }
2897
2898 /*
2899 * Fill page/offset/length into spd, if it can hold more pages.
2900 */
spd_fill_page(struct splice_pipe_desc * spd,struct pipe_inode_info * pipe,struct page * page,unsigned int * len,unsigned int offset,bool linear,struct sock * sk)2901 static bool spd_fill_page(struct splice_pipe_desc *spd,
2902 struct pipe_inode_info *pipe, struct page *page,
2903 unsigned int *len, unsigned int offset,
2904 bool linear,
2905 struct sock *sk)
2906 {
2907 if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
2908 return true;
2909
2910 if (linear) {
2911 page = linear_to_page(page, len, &offset, sk);
2912 if (!page)
2913 return true;
2914 }
2915 if (spd_can_coalesce(spd, page, offset)) {
2916 spd->partial[spd->nr_pages - 1].len += *len;
2917 return false;
2918 }
2919 get_page(page);
2920 spd->pages[spd->nr_pages] = page;
2921 spd->partial[spd->nr_pages].len = *len;
2922 spd->partial[spd->nr_pages].offset = offset;
2923 spd->nr_pages++;
2924
2925 return false;
2926 }
2927
__splice_segment(struct page * page,unsigned int poff,unsigned int plen,unsigned int * off,unsigned int * len,struct splice_pipe_desc * spd,bool linear,struct sock * sk,struct pipe_inode_info * pipe)2928 static bool __splice_segment(struct page *page, unsigned int poff,
2929 unsigned int plen, unsigned int *off,
2930 unsigned int *len,
2931 struct splice_pipe_desc *spd, bool linear,
2932 struct sock *sk,
2933 struct pipe_inode_info *pipe)
2934 {
2935 if (!*len)
2936 return true;
2937
2938 /* skip this segment if already processed */
2939 if (*off >= plen) {
2940 *off -= plen;
2941 return false;
2942 }
2943
2944 /* ignore any bits we already processed */
2945 poff += *off;
2946 plen -= *off;
2947 *off = 0;
2948
2949 do {
2950 unsigned int flen = min(*len, plen);
2951
2952 if (spd_fill_page(spd, pipe, page, &flen, poff,
2953 linear, sk))
2954 return true;
2955 poff += flen;
2956 plen -= flen;
2957 *len -= flen;
2958 } while (*len && plen);
2959
2960 return false;
2961 }
2962
2963 /*
2964 * Map linear and fragment data from the skb to spd. It reports true if the
2965 * pipe is full or if we already spliced the requested length.
2966 */
__skb_splice_bits(struct sk_buff * skb,struct pipe_inode_info * pipe,unsigned int * offset,unsigned int * len,struct splice_pipe_desc * spd,struct sock * sk)2967 static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
2968 unsigned int *offset, unsigned int *len,
2969 struct splice_pipe_desc *spd, struct sock *sk)
2970 {
2971 int seg;
2972 struct sk_buff *iter;
2973
2974 /* map the linear part :
2975 * If skb->head_frag is set, this 'linear' part is backed by a
2976 * fragment, and if the head is not shared with any clones then
2977 * we can avoid a copy since we own the head portion of this page.
2978 */
2979 if (__splice_segment(virt_to_page(skb->data),
2980 (unsigned long) skb->data & (PAGE_SIZE - 1),
2981 skb_headlen(skb),
2982 offset, len, spd,
2983 skb_head_is_locked(skb),
2984 sk, pipe))
2985 return true;
2986
2987 /*
2988 * then map the fragments
2989 */
2990 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
2991 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
2992
2993 if (__splice_segment(skb_frag_page(f),
2994 skb_frag_off(f), skb_frag_size(f),
2995 offset, len, spd, false, sk, pipe))
2996 return true;
2997 }
2998
2999 skb_walk_frags(skb, iter) {
3000 if (*offset >= iter->len) {
3001 *offset -= iter->len;
3002 continue;
3003 }
3004 /* __skb_splice_bits() only fails if the output has no room
3005 * left, so no point in going over the frag_list for the error
3006 * case.
3007 */
3008 if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
3009 return true;
3010 }
3011
3012 return false;
3013 }
3014
3015 /*
3016 * Map data from the skb to a pipe. Should handle both the linear part,
3017 * the fragments, and the frag list.
3018 */
skb_splice_bits(struct sk_buff * skb,struct sock * sk,unsigned int offset,struct pipe_inode_info * pipe,unsigned int tlen,unsigned int flags)3019 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
3020 struct pipe_inode_info *pipe, unsigned int tlen,
3021 unsigned int flags)
3022 {
3023 struct partial_page partial[MAX_SKB_FRAGS];
3024 struct page *pages[MAX_SKB_FRAGS];
3025 struct splice_pipe_desc spd = {
3026 .pages = pages,
3027 .partial = partial,
3028 .nr_pages_max = MAX_SKB_FRAGS,
3029 .ops = &nosteal_pipe_buf_ops,
3030 .spd_release = sock_spd_release,
3031 };
3032 int ret = 0;
3033
3034 __skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
3035
3036 if (spd.nr_pages)
3037 ret = splice_to_pipe(pipe, &spd);
3038
3039 return ret;
3040 }
3041 EXPORT_SYMBOL_GPL(skb_splice_bits);
3042
sendmsg_locked(struct sock * sk,struct msghdr * msg)3043 static int sendmsg_locked(struct sock *sk, struct msghdr *msg)
3044 {
3045 struct socket *sock = sk->sk_socket;
3046 size_t size = msg_data_left(msg);
3047
3048 if (!sock)
3049 return -EINVAL;
3050
3051 if (!sock->ops->sendmsg_locked)
3052 return sock_no_sendmsg_locked(sk, msg, size);
3053
3054 return sock->ops->sendmsg_locked(sk, msg, size);
3055 }
3056
sendmsg_unlocked(struct sock * sk,struct msghdr * msg)3057 static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg)
3058 {
3059 struct socket *sock = sk->sk_socket;
3060
3061 if (!sock)
3062 return -EINVAL;
3063 return sock_sendmsg(sock, msg);
3064 }
3065
3066 typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg);
__skb_send_sock(struct sock * sk,struct sk_buff * skb,int offset,int len,sendmsg_func sendmsg)3067 static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
3068 int len, sendmsg_func sendmsg)
3069 {
3070 unsigned int orig_len = len;
3071 struct sk_buff *head = skb;
3072 unsigned short fragidx;
3073 int slen, ret;
3074
3075 do_frag_list:
3076
3077 /* Deal with head data */
3078 while (offset < skb_headlen(skb) && len) {
3079 struct kvec kv;
3080 struct msghdr msg;
3081
3082 slen = min_t(int, len, skb_headlen(skb) - offset);
3083 kv.iov_base = skb->data + offset;
3084 kv.iov_len = slen;
3085 memset(&msg, 0, sizeof(msg));
3086 msg.msg_flags = MSG_DONTWAIT;
3087
3088 iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &kv, 1, slen);
3089 ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
3090 sendmsg_unlocked, sk, &msg);
3091 if (ret <= 0)
3092 goto error;
3093
3094 offset += ret;
3095 len -= ret;
3096 }
3097
3098 /* All the data was skb head? */
3099 if (!len)
3100 goto out;
3101
3102 /* Make offset relative to start of frags */
3103 offset -= skb_headlen(skb);
3104
3105 /* Find where we are in frag list */
3106 for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
3107 skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
3108
3109 if (offset < skb_frag_size(frag))
3110 break;
3111
3112 offset -= skb_frag_size(frag);
3113 }
3114
3115 for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
3116 skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
3117
3118 slen = min_t(size_t, len, skb_frag_size(frag) - offset);
3119
3120 while (slen) {
3121 struct bio_vec bvec;
3122 struct msghdr msg = {
3123 .msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT,
3124 };
3125
3126 bvec_set_page(&bvec, skb_frag_page(frag), slen,
3127 skb_frag_off(frag) + offset);
3128 iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1,
3129 slen);
3130
3131 ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
3132 sendmsg_unlocked, sk, &msg);
3133 if (ret <= 0)
3134 goto error;
3135
3136 len -= ret;
3137 offset += ret;
3138 slen -= ret;
3139 }
3140
3141 offset = 0;
3142 }
3143
3144 if (len) {
3145 /* Process any frag lists */
3146
3147 if (skb == head) {
3148 if (skb_has_frag_list(skb)) {
3149 skb = skb_shinfo(skb)->frag_list;
3150 goto do_frag_list;
3151 }
3152 } else if (skb->next) {
3153 skb = skb->next;
3154 goto do_frag_list;
3155 }
3156 }
3157
3158 out:
3159 return orig_len - len;
3160
3161 error:
3162 return orig_len == len ? ret : orig_len - len;
3163 }
3164
3165 /* Send skb data on a socket. Socket must be locked. */
skb_send_sock_locked(struct sock * sk,struct sk_buff * skb,int offset,int len)3166 int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
3167 int len)
3168 {
3169 return __skb_send_sock(sk, skb, offset, len, sendmsg_locked);
3170 }
3171 EXPORT_SYMBOL_GPL(skb_send_sock_locked);
3172
3173 /* Send skb data on a socket. Socket must be unlocked. */
skb_send_sock(struct sock * sk,struct sk_buff * skb,int offset,int len)3174 int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
3175 {
3176 return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked);
3177 }
3178
3179 /**
3180 * skb_store_bits - store bits from kernel buffer to skb
3181 * @skb: destination buffer
3182 * @offset: offset in destination
3183 * @from: source buffer
3184 * @len: number of bytes to copy
3185 *
3186 * Copy the specified number of bytes from the source buffer to the
3187 * destination skb. This function handles all the messy bits of
3188 * traversing fragment lists and such.
3189 */
3190
skb_store_bits(struct sk_buff * skb,int offset,const void * from,int len)3191 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
3192 {
3193 int start = skb_headlen(skb);
3194 struct sk_buff *frag_iter;
3195 int i, copy;
3196
3197 if (offset > (int)skb->len - len)
3198 goto fault;
3199
3200 if ((copy = start - offset) > 0) {
3201 if (copy > len)
3202 copy = len;
3203 skb_copy_to_linear_data_offset(skb, offset, from, copy);
3204 if ((len -= copy) == 0)
3205 return 0;
3206 offset += copy;
3207 from += copy;
3208 }
3209
3210 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3211 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3212 int end;
3213
3214 WARN_ON(start > offset + len);
3215
3216 end = start + skb_frag_size(frag);
3217 if ((copy = end - offset) > 0) {
3218 u32 p_off, p_len, copied;
3219 struct page *p;
3220 u8 *vaddr;
3221
3222 if (copy > len)
3223 copy = len;
3224
3225 skb_frag_foreach_page(frag,
3226 skb_frag_off(frag) + offset - start,
3227 copy, p, p_off, p_len, copied) {
3228 vaddr = kmap_atomic(p);
3229 memcpy(vaddr + p_off, from + copied, p_len);
3230 kunmap_atomic(vaddr);
3231 }
3232
3233 if ((len -= copy) == 0)
3234 return 0;
3235 offset += copy;
3236 from += copy;
3237 }
3238 start = end;
3239 }
3240
3241 skb_walk_frags(skb, frag_iter) {
3242 int end;
3243
3244 WARN_ON(start > offset + len);
3245
3246 end = start + frag_iter->len;
3247 if ((copy = end - offset) > 0) {
3248 if (copy > len)
3249 copy = len;
3250 if (skb_store_bits(frag_iter, offset - start,
3251 from, copy))
3252 goto fault;
3253 if ((len -= copy) == 0)
3254 return 0;
3255 offset += copy;
3256 from += copy;
3257 }
3258 start = end;
3259 }
3260 if (!len)
3261 return 0;
3262
3263 fault:
3264 return -EFAULT;
3265 }
3266 EXPORT_SYMBOL(skb_store_bits);
3267
3268 /* Checksum skb data. */
__skb_checksum(const struct sk_buff * skb,int offset,int len,__wsum csum,const struct skb_checksum_ops * ops)3269 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3270 __wsum csum, const struct skb_checksum_ops *ops)
3271 {
3272 int start = skb_headlen(skb);
3273 int i, copy = start - offset;
3274 struct sk_buff *frag_iter;
3275 int pos = 0;
3276
3277 /* Checksum header. */
3278 if (copy > 0) {
3279 if (copy > len)
3280 copy = len;
3281 csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,
3282 skb->data + offset, copy, csum);
3283 if ((len -= copy) == 0)
3284 return csum;
3285 offset += copy;
3286 pos = copy;
3287 }
3288
3289 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3290 int end;
3291 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3292
3293 WARN_ON(start > offset + len);
3294
3295 end = start + skb_frag_size(frag);
3296 if ((copy = end - offset) > 0) {
3297 u32 p_off, p_len, copied;
3298 struct page *p;
3299 __wsum csum2;
3300 u8 *vaddr;
3301
3302 if (copy > len)
3303 copy = len;
3304
3305 skb_frag_foreach_page(frag,
3306 skb_frag_off(frag) + offset - start,
3307 copy, p, p_off, p_len, copied) {
3308 vaddr = kmap_atomic(p);
3309 csum2 = INDIRECT_CALL_1(ops->update,
3310 csum_partial_ext,
3311 vaddr + p_off, p_len, 0);
3312 kunmap_atomic(vaddr);
3313 csum = INDIRECT_CALL_1(ops->combine,
3314 csum_block_add_ext, csum,
3315 csum2, pos, p_len);
3316 pos += p_len;
3317 }
3318
3319 if (!(len -= copy))
3320 return csum;
3321 offset += copy;
3322 }
3323 start = end;
3324 }
3325
3326 skb_walk_frags(skb, frag_iter) {
3327 int end;
3328
3329 WARN_ON(start > offset + len);
3330
3331 end = start + frag_iter->len;
3332 if ((copy = end - offset) > 0) {
3333 __wsum csum2;
3334 if (copy > len)
3335 copy = len;
3336 csum2 = __skb_checksum(frag_iter, offset - start,
3337 copy, 0, ops);
3338 csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,
3339 csum, csum2, pos, copy);
3340 if ((len -= copy) == 0)
3341 return csum;
3342 offset += copy;
3343 pos += copy;
3344 }
3345 start = end;
3346 }
3347 BUG_ON(len);
3348
3349 return csum;
3350 }
3351 EXPORT_SYMBOL(__skb_checksum);
3352
skb_checksum(const struct sk_buff * skb,int offset,int len,__wsum csum)3353 __wsum skb_checksum(const struct sk_buff *skb, int offset,
3354 int len, __wsum csum)
3355 {
3356 const struct skb_checksum_ops ops = {
3357 .update = csum_partial_ext,
3358 .combine = csum_block_add_ext,
3359 };
3360
3361 return __skb_checksum(skb, offset, len, csum, &ops);
3362 }
3363 EXPORT_SYMBOL(skb_checksum);
3364
3365 /* Both of above in one bottle. */
3366
skb_copy_and_csum_bits(const struct sk_buff * skb,int offset,u8 * to,int len)3367 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
3368 u8 *to, int len)
3369 {
3370 int start = skb_headlen(skb);
3371 int i, copy = start - offset;
3372 struct sk_buff *frag_iter;
3373 int pos = 0;
3374 __wsum csum = 0;
3375
3376 /* Copy header. */
3377 if (copy > 0) {
3378 if (copy > len)
3379 copy = len;
3380 csum = csum_partial_copy_nocheck(skb->data + offset, to,
3381 copy);
3382 if ((len -= copy) == 0)
3383 return csum;
3384 offset += copy;
3385 to += copy;
3386 pos = copy;
3387 }
3388
3389 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3390 int end;
3391
3392 WARN_ON(start > offset + len);
3393
3394 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3395 if ((copy = end - offset) > 0) {
3396 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3397 u32 p_off, p_len, copied;
3398 struct page *p;
3399 __wsum csum2;
3400 u8 *vaddr;
3401
3402 if (copy > len)
3403 copy = len;
3404
3405 skb_frag_foreach_page(frag,
3406 skb_frag_off(frag) + offset - start,
3407 copy, p, p_off, p_len, copied) {
3408 vaddr = kmap_atomic(p);
3409 csum2 = csum_partial_copy_nocheck(vaddr + p_off,
3410 to + copied,
3411 p_len);
3412 kunmap_atomic(vaddr);
3413 csum = csum_block_add(csum, csum2, pos);
3414 pos += p_len;
3415 }
3416
3417 if (!(len -= copy))
3418 return csum;
3419 offset += copy;
3420 to += copy;
3421 }
3422 start = end;
3423 }
3424
3425 skb_walk_frags(skb, frag_iter) {
3426 __wsum csum2;
3427 int end;
3428
3429 WARN_ON(start > offset + len);
3430
3431 end = start + frag_iter->len;
3432 if ((copy = end - offset) > 0) {
3433 if (copy > len)
3434 copy = len;
3435 csum2 = skb_copy_and_csum_bits(frag_iter,
3436 offset - start,
3437 to, copy);
3438 csum = csum_block_add(csum, csum2, pos);
3439 if ((len -= copy) == 0)
3440 return csum;
3441 offset += copy;
3442 to += copy;
3443 pos += copy;
3444 }
3445 start = end;
3446 }
3447 BUG_ON(len);
3448 return csum;
3449 }
3450 EXPORT_SYMBOL(skb_copy_and_csum_bits);
3451
__skb_checksum_complete_head(struct sk_buff * skb,int len)3452 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
3453 {
3454 __sum16 sum;
3455
3456 sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
3457 /* See comments in __skb_checksum_complete(). */
3458 if (likely(!sum)) {
3459 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
3460 !skb->csum_complete_sw)
3461 netdev_rx_csum_fault(skb->dev, skb);
3462 }
3463 if (!skb_shared(skb))
3464 skb->csum_valid = !sum;
3465 return sum;
3466 }
3467 EXPORT_SYMBOL(__skb_checksum_complete_head);
3468
3469 /* This function assumes skb->csum already holds pseudo header's checksum,
3470 * which has been changed from the hardware checksum, for example, by
3471 * __skb_checksum_validate_complete(). And, the original skb->csum must
3472 * have been validated unsuccessfully for CHECKSUM_COMPLETE case.
3473 *
3474 * It returns non-zero if the recomputed checksum is still invalid, otherwise
3475 * zero. The new checksum is stored back into skb->csum unless the skb is
3476 * shared.
3477 */
__skb_checksum_complete(struct sk_buff * skb)3478 __sum16 __skb_checksum_complete(struct sk_buff *skb)
3479 {
3480 __wsum csum;
3481 __sum16 sum;
3482
3483 csum = skb_checksum(skb, 0, skb->len, 0);
3484
3485 sum = csum_fold(csum_add(skb->csum, csum));
3486 /* This check is inverted, because we already knew the hardware
3487 * checksum is invalid before calling this function. So, if the
3488 * re-computed checksum is valid instead, then we have a mismatch
3489 * between the original skb->csum and skb_checksum(). This means either
3490 * the original hardware checksum is incorrect or we screw up skb->csum
3491 * when moving skb->data around.
3492 */
3493 if (likely(!sum)) {
3494 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
3495 !skb->csum_complete_sw)
3496 netdev_rx_csum_fault(skb->dev, skb);
3497 }
3498
3499 if (!skb_shared(skb)) {
3500 /* Save full packet checksum */
3501 skb->csum = csum;
3502 skb->ip_summed = CHECKSUM_COMPLETE;
3503 skb->csum_complete_sw = 1;
3504 skb->csum_valid = !sum;
3505 }
3506
3507 return sum;
3508 }
3509 EXPORT_SYMBOL(__skb_checksum_complete);
3510
warn_crc32c_csum_update(const void * buff,int len,__wsum sum)3511 static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
3512 {
3513 net_warn_ratelimited(
3514 "%s: attempt to compute crc32c without libcrc32c.ko\n",
3515 __func__);
3516 return 0;
3517 }
3518
warn_crc32c_csum_combine(__wsum csum,__wsum csum2,int offset,int len)3519 static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
3520 int offset, int len)
3521 {
3522 net_warn_ratelimited(
3523 "%s: attempt to compute crc32c without libcrc32c.ko\n",
3524 __func__);
3525 return 0;
3526 }
3527
3528 static const struct skb_checksum_ops default_crc32c_ops = {
3529 .update = warn_crc32c_csum_update,
3530 .combine = warn_crc32c_csum_combine,
3531 };
3532
3533 const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
3534 &default_crc32c_ops;
3535 EXPORT_SYMBOL(crc32c_csum_stub);
3536
3537 /**
3538 * skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
3539 * @from: source buffer
3540 *
3541 * Calculates the amount of linear headroom needed in the 'to' skb passed
3542 * into skb_zerocopy().
3543 */
3544 unsigned int
skb_zerocopy_headlen(const struct sk_buff * from)3545 skb_zerocopy_headlen(const struct sk_buff *from)
3546 {
3547 unsigned int hlen = 0;
3548
3549 if (!from->head_frag ||
3550 skb_headlen(from) < L1_CACHE_BYTES ||
3551 skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) {
3552 hlen = skb_headlen(from);
3553 if (!hlen)
3554 hlen = from->len;
3555 }
3556
3557 if (skb_has_frag_list(from))
3558 hlen = from->len;
3559
3560 return hlen;
3561 }
3562 EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
3563
3564 /**
3565 * skb_zerocopy - Zero copy skb to skb
3566 * @to: destination buffer
3567 * @from: source buffer
3568 * @len: number of bytes to copy from source buffer
3569 * @hlen: size of linear headroom in destination buffer
3570 *
3571 * Copies up to `len` bytes from `from` to `to` by creating references
3572 * to the frags in the source buffer.
3573 *
3574 * The `hlen` as calculated by skb_zerocopy_headlen() specifies the
3575 * headroom in the `to` buffer.
3576 *
3577 * Return value:
3578 * 0: everything is OK
3579 * -ENOMEM: couldn't orphan frags of @from due to lack of memory
3580 * -EFAULT: skb_copy_bits() found some problem with skb geometry
3581 */
3582 int
skb_zerocopy(struct sk_buff * to,struct sk_buff * from,int len,int hlen)3583 skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
3584 {
3585 int i, j = 0;
3586 int plen = 0; /* length of skb->head fragment */
3587 int ret;
3588 struct page *page;
3589 unsigned int offset;
3590
3591 BUG_ON(!from->head_frag && !hlen);
3592
3593 /* dont bother with small payloads */
3594 if (len <= skb_tailroom(to))
3595 return skb_copy_bits(from, 0, skb_put(to, len), len);
3596
3597 if (hlen) {
3598 ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
3599 if (unlikely(ret))
3600 return ret;
3601 len -= hlen;
3602 } else {
3603 plen = min_t(int, skb_headlen(from), len);
3604 if (plen) {
3605 page = virt_to_head_page(from->head);
3606 offset = from->data - (unsigned char *)page_address(page);
3607 __skb_fill_page_desc(to, 0, page, offset, plen);
3608 get_page(page);
3609 j = 1;
3610 len -= plen;
3611 }
3612 }
3613
3614 skb_len_add(to, len + plen);
3615
3616 if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
3617 skb_tx_error(from);
3618 return -ENOMEM;
3619 }
3620 skb_zerocopy_clone(to, from, GFP_ATOMIC);
3621
3622 for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
3623 int size;
3624
3625 if (!len)
3626 break;
3627 skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
3628 size = min_t(int, skb_frag_size(&skb_shinfo(to)->frags[j]),
3629 len);
3630 skb_frag_size_set(&skb_shinfo(to)->frags[j], size);
3631 len -= size;
3632 skb_frag_ref(to, j);
3633 j++;
3634 }
3635 skb_shinfo(to)->nr_frags = j;
3636
3637 return 0;
3638 }
3639 EXPORT_SYMBOL_GPL(skb_zerocopy);
3640
skb_copy_and_csum_dev(const struct sk_buff * skb,u8 * to)3641 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
3642 {
3643 __wsum csum;
3644 long csstart;
3645
3646 if (skb->ip_summed == CHECKSUM_PARTIAL)
3647 csstart = skb_checksum_start_offset(skb);
3648 else
3649 csstart = skb_headlen(skb);
3650
3651 BUG_ON(csstart > skb_headlen(skb));
3652
3653 skb_copy_from_linear_data(skb, to, csstart);
3654
3655 csum = 0;
3656 if (csstart != skb->len)
3657 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
3658 skb->len - csstart);
3659
3660 if (skb->ip_summed == CHECKSUM_PARTIAL) {
3661 long csstuff = csstart + skb->csum_offset;
3662
3663 *((__sum16 *)(to + csstuff)) = csum_fold(csum);
3664 }
3665 }
3666 EXPORT_SYMBOL(skb_copy_and_csum_dev);
3667
3668 /**
3669 * skb_dequeue - remove from the head of the queue
3670 * @list: list to dequeue from
3671 *
3672 * Remove the head of the list. The list lock is taken so the function
3673 * may be used safely with other locking list functions. The head item is
3674 * returned or %NULL if the list is empty.
3675 */
3676
skb_dequeue(struct sk_buff_head * list)3677 struct sk_buff *skb_dequeue(struct sk_buff_head *list)
3678 {
3679 unsigned long flags;
3680 struct sk_buff *result;
3681
3682 spin_lock_irqsave(&list->lock, flags);
3683 result = __skb_dequeue(list);
3684 spin_unlock_irqrestore(&list->lock, flags);
3685 return result;
3686 }
3687 EXPORT_SYMBOL(skb_dequeue);
3688
3689 /**
3690 * skb_dequeue_tail - remove from the tail of the queue
3691 * @list: list to dequeue from
3692 *
3693 * Remove the tail of the list. The list lock is taken so the function
3694 * may be used safely with other locking list functions. The tail item is
3695 * returned or %NULL if the list is empty.
3696 */
skb_dequeue_tail(struct sk_buff_head * list)3697 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
3698 {
3699 unsigned long flags;
3700 struct sk_buff *result;
3701
3702 spin_lock_irqsave(&list->lock, flags);
3703 result = __skb_dequeue_tail(list);
3704 spin_unlock_irqrestore(&list->lock, flags);
3705 return result;
3706 }
3707 EXPORT_SYMBOL(skb_dequeue_tail);
3708
3709 /**
3710 * skb_queue_purge_reason - empty a list
3711 * @list: list to empty
3712 * @reason: drop reason
3713 *
3714 * Delete all buffers on an &sk_buff list. Each buffer is removed from
3715 * the list and one reference dropped. This function takes the list
3716 * lock and is atomic with respect to other list locking functions.
3717 */
skb_queue_purge_reason(struct sk_buff_head * list,enum skb_drop_reason reason)3718 void skb_queue_purge_reason(struct sk_buff_head *list,
3719 enum skb_drop_reason reason)
3720 {
3721 struct sk_buff *skb;
3722
3723 while ((skb = skb_dequeue(list)) != NULL)
3724 kfree_skb_reason(skb, reason);
3725 }
3726 EXPORT_SYMBOL(skb_queue_purge_reason);
3727
3728 /**
3729 * skb_rbtree_purge - empty a skb rbtree
3730 * @root: root of the rbtree to empty
3731 * Return value: the sum of truesizes of all purged skbs.
3732 *
3733 * Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
3734 * the list and one reference dropped. This function does not take
3735 * any lock. Synchronization should be handled by the caller (e.g., TCP
3736 * out-of-order queue is protected by the socket lock).
3737 */
skb_rbtree_purge(struct rb_root * root)3738 unsigned int skb_rbtree_purge(struct rb_root *root)
3739 {
3740 struct rb_node *p = rb_first(root);
3741 unsigned int sum = 0;
3742
3743 while (p) {
3744 struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
3745
3746 p = rb_next(p);
3747 rb_erase(&skb->rbnode, root);
3748 sum += skb->truesize;
3749 kfree_skb(skb);
3750 }
3751 return sum;
3752 }
3753
skb_errqueue_purge(struct sk_buff_head * list)3754 void skb_errqueue_purge(struct sk_buff_head *list)
3755 {
3756 struct sk_buff *skb, *next;
3757 struct sk_buff_head kill;
3758 unsigned long flags;
3759
3760 __skb_queue_head_init(&kill);
3761
3762 spin_lock_irqsave(&list->lock, flags);
3763 skb_queue_walk_safe(list, skb, next) {
3764 if (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ZEROCOPY ||
3765 SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING)
3766 continue;
3767 __skb_unlink(skb, list);
3768 __skb_queue_tail(&kill, skb);
3769 }
3770 spin_unlock_irqrestore(&list->lock, flags);
3771 __skb_queue_purge(&kill);
3772 }
3773 EXPORT_SYMBOL(skb_errqueue_purge);
3774
3775 /**
3776 * skb_queue_head - queue a buffer at the list head
3777 * @list: list to use
3778 * @newsk: buffer to queue
3779 *
3780 * Queue a buffer at the start of the list. This function takes the
3781 * list lock and can be used safely with other locking &sk_buff functions
3782 * safely.
3783 *
3784 * A buffer cannot be placed on two lists at the same time.
3785 */
skb_queue_head(struct sk_buff_head * list,struct sk_buff * newsk)3786 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
3787 {
3788 unsigned long flags;
3789
3790 spin_lock_irqsave(&list->lock, flags);
3791 __skb_queue_head(list, newsk);
3792 spin_unlock_irqrestore(&list->lock, flags);
3793 }
3794 EXPORT_SYMBOL(skb_queue_head);
3795
3796 /**
3797 * skb_queue_tail - queue a buffer at the list tail
3798 * @list: list to use
3799 * @newsk: buffer to queue
3800 *
3801 * Queue a buffer at the tail of the list. This function takes the
3802 * list lock and can be used safely with other locking &sk_buff functions
3803 * safely.
3804 *
3805 * A buffer cannot be placed on two lists at the same time.
3806 */
skb_queue_tail(struct sk_buff_head * list,struct sk_buff * newsk)3807 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
3808 {
3809 unsigned long flags;
3810
3811 spin_lock_irqsave(&list->lock, flags);
3812 __skb_queue_tail(list, newsk);
3813 spin_unlock_irqrestore(&list->lock, flags);
3814 }
3815 EXPORT_SYMBOL(skb_queue_tail);
3816
3817 /**
3818 * skb_unlink - remove a buffer from a list
3819 * @skb: buffer to remove
3820 * @list: list to use
3821 *
3822 * Remove a packet from a list. The list locks are taken and this
3823 * function is atomic with respect to other list locked calls
3824 *
3825 * You must know what list the SKB is on.
3826 */
skb_unlink(struct sk_buff * skb,struct sk_buff_head * list)3827 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
3828 {
3829 unsigned long flags;
3830
3831 spin_lock_irqsave(&list->lock, flags);
3832 __skb_unlink(skb, list);
3833 spin_unlock_irqrestore(&list->lock, flags);
3834 }
3835 EXPORT_SYMBOL(skb_unlink);
3836
3837 /**
3838 * skb_append - append a buffer
3839 * @old: buffer to insert after
3840 * @newsk: buffer to insert
3841 * @list: list to use
3842 *
3843 * Place a packet after a given packet in a list. The list locks are taken
3844 * and this function is atomic with respect to other list locked calls.
3845 * A buffer cannot be placed on two lists at the same time.
3846 */
skb_append(struct sk_buff * old,struct sk_buff * newsk,struct sk_buff_head * list)3847 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
3848 {
3849 unsigned long flags;
3850
3851 spin_lock_irqsave(&list->lock, flags);
3852 __skb_queue_after(list, old, newsk);
3853 spin_unlock_irqrestore(&list->lock, flags);
3854 }
3855 EXPORT_SYMBOL(skb_append);
3856
skb_split_inside_header(struct sk_buff * skb,struct sk_buff * skb1,const u32 len,const int pos)3857 static inline void skb_split_inside_header(struct sk_buff *skb,
3858 struct sk_buff* skb1,
3859 const u32 len, const int pos)
3860 {
3861 int i;
3862
3863 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
3864 pos - len);
3865 /* And move data appendix as is. */
3866 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
3867 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
3868
3869 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
3870 skb_shinfo(skb)->nr_frags = 0;
3871 skb1->data_len = skb->data_len;
3872 skb1->len += skb1->data_len;
3873 skb->data_len = 0;
3874 skb->len = len;
3875 skb_set_tail_pointer(skb, len);
3876 }
3877
skb_split_no_header(struct sk_buff * skb,struct sk_buff * skb1,const u32 len,int pos)3878 static inline void skb_split_no_header(struct sk_buff *skb,
3879 struct sk_buff* skb1,
3880 const u32 len, int pos)
3881 {
3882 int i, k = 0;
3883 const int nfrags = skb_shinfo(skb)->nr_frags;
3884
3885 skb_shinfo(skb)->nr_frags = 0;
3886 skb1->len = skb1->data_len = skb->len - len;
3887 skb->len = len;
3888 skb->data_len = len - pos;
3889
3890 for (i = 0; i < nfrags; i++) {
3891 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
3892
3893 if (pos + size > len) {
3894 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
3895
3896 if (pos < len) {
3897 /* Split frag.
3898 * We have two variants in this case:
3899 * 1. Move all the frag to the second
3900 * part, if it is possible. F.e.
3901 * this approach is mandatory for TUX,
3902 * where splitting is expensive.
3903 * 2. Split is accurately. We make this.
3904 */
3905 skb_frag_ref(skb, i);
3906 skb_frag_off_add(&skb_shinfo(skb1)->frags[0], len - pos);
3907 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
3908 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
3909 skb_shinfo(skb)->nr_frags++;
3910 }
3911 k++;
3912 } else
3913 skb_shinfo(skb)->nr_frags++;
3914 pos += size;
3915 }
3916 skb_shinfo(skb1)->nr_frags = k;
3917 }
3918
3919 /**
3920 * skb_split - Split fragmented skb to two parts at length len.
3921 * @skb: the buffer to split
3922 * @skb1: the buffer to receive the second part
3923 * @len: new length for skb
3924 */
skb_split(struct sk_buff * skb,struct sk_buff * skb1,const u32 len)3925 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
3926 {
3927 int pos = skb_headlen(skb);
3928 const int zc_flags = SKBFL_SHARED_FRAG | SKBFL_PURE_ZEROCOPY;
3929
3930 skb_zcopy_downgrade_managed(skb);
3931
3932 skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & zc_flags;
3933 skb_zerocopy_clone(skb1, skb, 0);
3934 if (len < pos) /* Split line is inside header. */
3935 skb_split_inside_header(skb, skb1, len, pos);
3936 else /* Second chunk has no header, nothing to copy. */
3937 skb_split_no_header(skb, skb1, len, pos);
3938 }
3939 EXPORT_SYMBOL(skb_split);
3940
3941 /* Shifting from/to a cloned skb is a no-go.
3942 *
3943 * Caller cannot keep skb_shinfo related pointers past calling here!
3944 */
skb_prepare_for_shift(struct sk_buff * skb)3945 static int skb_prepare_for_shift(struct sk_buff *skb)
3946 {
3947 return skb_unclone_keeptruesize(skb, GFP_ATOMIC);
3948 }
3949
3950 /**
3951 * skb_shift - Shifts paged data partially from skb to another
3952 * @tgt: buffer into which tail data gets added
3953 * @skb: buffer from which the paged data comes from
3954 * @shiftlen: shift up to this many bytes
3955 *
3956 * Attempts to shift up to shiftlen worth of bytes, which may be less than
3957 * the length of the skb, from skb to tgt. Returns number bytes shifted.
3958 * It's up to caller to free skb if everything was shifted.
3959 *
3960 * If @tgt runs out of frags, the whole operation is aborted.
3961 *
3962 * Skb cannot include anything else but paged data while tgt is allowed
3963 * to have non-paged data as well.
3964 *
3965 * TODO: full sized shift could be optimized but that would need
3966 * specialized skb free'er to handle frags without up-to-date nr_frags.
3967 */
skb_shift(struct sk_buff * tgt,struct sk_buff * skb,int shiftlen)3968 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
3969 {
3970 int from, to, merge, todo;
3971 skb_frag_t *fragfrom, *fragto;
3972
3973 BUG_ON(shiftlen > skb->len);
3974
3975 if (skb_headlen(skb))
3976 return 0;
3977 if (skb_zcopy(tgt) || skb_zcopy(skb))
3978 return 0;
3979
3980 todo = shiftlen;
3981 from = 0;
3982 to = skb_shinfo(tgt)->nr_frags;
3983 fragfrom = &skb_shinfo(skb)->frags[from];
3984
3985 /* Actual merge is delayed until the point when we know we can
3986 * commit all, so that we don't have to undo partial changes
3987 */
3988 if (!to ||
3989 !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
3990 skb_frag_off(fragfrom))) {
3991 merge = -1;
3992 } else {
3993 merge = to - 1;
3994
3995 todo -= skb_frag_size(fragfrom);
3996 if (todo < 0) {
3997 if (skb_prepare_for_shift(skb) ||
3998 skb_prepare_for_shift(tgt))
3999 return 0;
4000
4001 /* All previous frag pointers might be stale! */
4002 fragfrom = &skb_shinfo(skb)->frags[from];
4003 fragto = &skb_shinfo(tgt)->frags[merge];
4004
4005 skb_frag_size_add(fragto, shiftlen);
4006 skb_frag_size_sub(fragfrom, shiftlen);
4007 skb_frag_off_add(fragfrom, shiftlen);
4008
4009 goto onlymerged;
4010 }
4011
4012 from++;
4013 }
4014
4015 /* Skip full, not-fitting skb to avoid expensive operations */
4016 if ((shiftlen == skb->len) &&
4017 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
4018 return 0;
4019
4020 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
4021 return 0;
4022
4023 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
4024 if (to == MAX_SKB_FRAGS)
4025 return 0;
4026
4027 fragfrom = &skb_shinfo(skb)->frags[from];
4028 fragto = &skb_shinfo(tgt)->frags[to];
4029
4030 if (todo >= skb_frag_size(fragfrom)) {
4031 *fragto = *fragfrom;
4032 todo -= skb_frag_size(fragfrom);
4033 from++;
4034 to++;
4035
4036 } else {
4037 __skb_frag_ref(fragfrom);
4038 skb_frag_page_copy(fragto, fragfrom);
4039 skb_frag_off_copy(fragto, fragfrom);
4040 skb_frag_size_set(fragto, todo);
4041
4042 skb_frag_off_add(fragfrom, todo);
4043 skb_frag_size_sub(fragfrom, todo);
4044 todo = 0;
4045
4046 to++;
4047 break;
4048 }
4049 }
4050
4051 /* Ready to "commit" this state change to tgt */
4052 skb_shinfo(tgt)->nr_frags = to;
4053
4054 if (merge >= 0) {
4055 fragfrom = &skb_shinfo(skb)->frags[0];
4056 fragto = &skb_shinfo(tgt)->frags[merge];
4057
4058 skb_frag_size_add(fragto, skb_frag_size(fragfrom));
4059 __skb_frag_unref(fragfrom, skb->pp_recycle);
4060 }
4061
4062 /* Reposition in the original skb */
4063 to = 0;
4064 while (from < skb_shinfo(skb)->nr_frags)
4065 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
4066 skb_shinfo(skb)->nr_frags = to;
4067
4068 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
4069
4070 onlymerged:
4071 /* Most likely the tgt won't ever need its checksum anymore, skb on
4072 * the other hand might need it if it needs to be resent
4073 */
4074 tgt->ip_summed = CHECKSUM_PARTIAL;
4075 skb->ip_summed = CHECKSUM_PARTIAL;
4076
4077 skb_len_add(skb, -shiftlen);
4078 skb_len_add(tgt, shiftlen);
4079
4080 return shiftlen;
4081 }
4082
4083 /**
4084 * skb_prepare_seq_read - Prepare a sequential read of skb data
4085 * @skb: the buffer to read
4086 * @from: lower offset of data to be read
4087 * @to: upper offset of data to be read
4088 * @st: state variable
4089 *
4090 * Initializes the specified state variable. Must be called before
4091 * invoking skb_seq_read() for the first time.
4092 */
skb_prepare_seq_read(struct sk_buff * skb,unsigned int from,unsigned int to,struct skb_seq_state * st)4093 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
4094 unsigned int to, struct skb_seq_state *st)
4095 {
4096 st->lower_offset = from;
4097 st->upper_offset = to;
4098 st->root_skb = st->cur_skb = skb;
4099 st->frag_idx = st->stepped_offset = 0;
4100 st->frag_data = NULL;
4101 st->frag_off = 0;
4102 }
4103 EXPORT_SYMBOL(skb_prepare_seq_read);
4104
4105 /**
4106 * skb_seq_read - Sequentially read skb data
4107 * @consumed: number of bytes consumed by the caller so far
4108 * @data: destination pointer for data to be returned
4109 * @st: state variable
4110 *
4111 * Reads a block of skb data at @consumed relative to the
4112 * lower offset specified to skb_prepare_seq_read(). Assigns
4113 * the head of the data block to @data and returns the length
4114 * of the block or 0 if the end of the skb data or the upper
4115 * offset has been reached.
4116 *
4117 * The caller is not required to consume all of the data
4118 * returned, i.e. @consumed is typically set to the number
4119 * of bytes already consumed and the next call to
4120 * skb_seq_read() will return the remaining part of the block.
4121 *
4122 * Note 1: The size of each block of data returned can be arbitrary,
4123 * this limitation is the cost for zerocopy sequential
4124 * reads of potentially non linear data.
4125 *
4126 * Note 2: Fragment lists within fragments are not implemented
4127 * at the moment, state->root_skb could be replaced with
4128 * a stack for this purpose.
4129 */
skb_seq_read(unsigned int consumed,const u8 ** data,struct skb_seq_state * st)4130 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
4131 struct skb_seq_state *st)
4132 {
4133 unsigned int block_limit, abs_offset = consumed + st->lower_offset;
4134 skb_frag_t *frag;
4135
4136 if (unlikely(abs_offset >= st->upper_offset)) {
4137 if (st->frag_data) {
4138 kunmap_atomic(st->frag_data);
4139 st->frag_data = NULL;
4140 }
4141 return 0;
4142 }
4143
4144 next_skb:
4145 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
4146
4147 if (abs_offset < block_limit && !st->frag_data) {
4148 *data = st->cur_skb->data + (abs_offset - st->stepped_offset);
4149 return block_limit - abs_offset;
4150 }
4151
4152 if (st->frag_idx == 0 && !st->frag_data)
4153 st->stepped_offset += skb_headlen(st->cur_skb);
4154
4155 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
4156 unsigned int pg_idx, pg_off, pg_sz;
4157
4158 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
4159
4160 pg_idx = 0;
4161 pg_off = skb_frag_off(frag);
4162 pg_sz = skb_frag_size(frag);
4163
4164 if (skb_frag_must_loop(skb_frag_page(frag))) {
4165 pg_idx = (pg_off + st->frag_off) >> PAGE_SHIFT;
4166 pg_off = offset_in_page(pg_off + st->frag_off);
4167 pg_sz = min_t(unsigned int, pg_sz - st->frag_off,
4168 PAGE_SIZE - pg_off);
4169 }
4170
4171 block_limit = pg_sz + st->stepped_offset;
4172 if (abs_offset < block_limit) {
4173 if (!st->frag_data)
4174 st->frag_data = kmap_atomic(skb_frag_page(frag) + pg_idx);
4175
4176 *data = (u8 *)st->frag_data + pg_off +
4177 (abs_offset - st->stepped_offset);
4178
4179 return block_limit - abs_offset;
4180 }
4181
4182 if (st->frag_data) {
4183 kunmap_atomic(st->frag_data);
4184 st->frag_data = NULL;
4185 }
4186
4187 st->stepped_offset += pg_sz;
4188 st->frag_off += pg_sz;
4189 if (st->frag_off == skb_frag_size(frag)) {
4190 st->frag_off = 0;
4191 st->frag_idx++;
4192 }
4193 }
4194
4195 if (st->frag_data) {
4196 kunmap_atomic(st->frag_data);
4197 st->frag_data = NULL;
4198 }
4199
4200 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
4201 st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
4202 st->frag_idx = 0;
4203 goto next_skb;
4204 } else if (st->cur_skb->next) {
4205 st->cur_skb = st->cur_skb->next;
4206 st->frag_idx = 0;
4207 goto next_skb;
4208 }
4209
4210 return 0;
4211 }
4212 EXPORT_SYMBOL(skb_seq_read);
4213
4214 /**
4215 * skb_abort_seq_read - Abort a sequential read of skb data
4216 * @st: state variable
4217 *
4218 * Must be called if skb_seq_read() was not called until it
4219 * returned 0.
4220 */
skb_abort_seq_read(struct skb_seq_state * st)4221 void skb_abort_seq_read(struct skb_seq_state *st)
4222 {
4223 if (st->frag_data)
4224 kunmap_atomic(st->frag_data);
4225 }
4226 EXPORT_SYMBOL(skb_abort_seq_read);
4227
4228 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb))
4229
skb_ts_get_next_block(unsigned int offset,const u8 ** text,struct ts_config * conf,struct ts_state * state)4230 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
4231 struct ts_config *conf,
4232 struct ts_state *state)
4233 {
4234 return skb_seq_read(offset, text, TS_SKB_CB(state));
4235 }
4236
skb_ts_finish(struct ts_config * conf,struct ts_state * state)4237 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
4238 {
4239 skb_abort_seq_read(TS_SKB_CB(state));
4240 }
4241
4242 /**
4243 * skb_find_text - Find a text pattern in skb data
4244 * @skb: the buffer to look in
4245 * @from: search offset
4246 * @to: search limit
4247 * @config: textsearch configuration
4248 *
4249 * Finds a pattern in the skb data according to the specified
4250 * textsearch configuration. Use textsearch_next() to retrieve
4251 * subsequent occurrences of the pattern. Returns the offset
4252 * to the first occurrence or UINT_MAX if no match was found.
4253 */
skb_find_text(struct sk_buff * skb,unsigned int from,unsigned int to,struct ts_config * config)4254 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
4255 unsigned int to, struct ts_config *config)
4256 {
4257 unsigned int patlen = config->ops->get_pattern_len(config);
4258 struct ts_state state;
4259 unsigned int ret;
4260
4261 BUILD_BUG_ON(sizeof(struct skb_seq_state) > sizeof(state.cb));
4262
4263 config->get_next_block = skb_ts_get_next_block;
4264 config->finish = skb_ts_finish;
4265
4266 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
4267
4268 ret = textsearch_find(config, &state);
4269 return (ret + patlen <= to - from ? ret : UINT_MAX);
4270 }
4271 EXPORT_SYMBOL(skb_find_text);
4272
skb_append_pagefrags(struct sk_buff * skb,struct page * page,int offset,size_t size,size_t max_frags)4273 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
4274 int offset, size_t size, size_t max_frags)
4275 {
4276 int i = skb_shinfo(skb)->nr_frags;
4277
4278 if (skb_can_coalesce(skb, i, page, offset)) {
4279 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
4280 } else if (i < max_frags) {
4281 skb_zcopy_downgrade_managed(skb);
4282 get_page(page);
4283 skb_fill_page_desc_noacc(skb, i, page, offset, size);
4284 } else {
4285 return -EMSGSIZE;
4286 }
4287
4288 return 0;
4289 }
4290 EXPORT_SYMBOL_GPL(skb_append_pagefrags);
4291
4292 /**
4293 * skb_pull_rcsum - pull skb and update receive checksum
4294 * @skb: buffer to update
4295 * @len: length of data pulled
4296 *
4297 * This function performs an skb_pull on the packet and updates
4298 * the CHECKSUM_COMPLETE checksum. It should be used on
4299 * receive path processing instead of skb_pull unless you know
4300 * that the checksum difference is zero (e.g., a valid IP header)
4301 * or you are setting ip_summed to CHECKSUM_NONE.
4302 */
skb_pull_rcsum(struct sk_buff * skb,unsigned int len)4303 void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
4304 {
4305 unsigned char *data = skb->data;
4306
4307 BUG_ON(len > skb->len);
4308 __skb_pull(skb, len);
4309 skb_postpull_rcsum(skb, data, len);
4310 return skb->data;
4311 }
4312 EXPORT_SYMBOL_GPL(skb_pull_rcsum);
4313
skb_head_frag_to_page_desc(struct sk_buff * frag_skb)4314 static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
4315 {
4316 skb_frag_t head_frag;
4317 struct page *page;
4318
4319 page = virt_to_head_page(frag_skb->head);
4320 skb_frag_fill_page_desc(&head_frag, page, frag_skb->data -
4321 (unsigned char *)page_address(page),
4322 skb_headlen(frag_skb));
4323 return head_frag;
4324 }
4325
skb_segment_list(struct sk_buff * skb,netdev_features_t features,unsigned int offset)4326 struct sk_buff *skb_segment_list(struct sk_buff *skb,
4327 netdev_features_t features,
4328 unsigned int offset)
4329 {
4330 struct sk_buff *list_skb = skb_shinfo(skb)->frag_list;
4331 unsigned int tnl_hlen = skb_tnl_header_len(skb);
4332 unsigned int delta_truesize = 0;
4333 unsigned int delta_len = 0;
4334 struct sk_buff *tail = NULL;
4335 struct sk_buff *nskb, *tmp;
4336 int len_diff, err;
4337
4338 skb_push(skb, -skb_network_offset(skb) + offset);
4339
4340 /* Ensure the head is writeable before touching the shared info */
4341 err = skb_unclone(skb, GFP_ATOMIC);
4342 if (err)
4343 goto err_linearize;
4344
4345 skb_shinfo(skb)->frag_list = NULL;
4346
4347 while (list_skb) {
4348 nskb = list_skb;
4349 list_skb = list_skb->next;
4350
4351 err = 0;
4352 delta_truesize += nskb->truesize;
4353 if (skb_shared(nskb)) {
4354 tmp = skb_clone(nskb, GFP_ATOMIC);
4355 if (tmp) {
4356 consume_skb(nskb);
4357 nskb = tmp;
4358 err = skb_unclone(nskb, GFP_ATOMIC);
4359 } else {
4360 err = -ENOMEM;
4361 }
4362 }
4363
4364 if (!tail)
4365 skb->next = nskb;
4366 else
4367 tail->next = nskb;
4368
4369 if (unlikely(err)) {
4370 nskb->next = list_skb;
4371 goto err_linearize;
4372 }
4373
4374 tail = nskb;
4375
4376 delta_len += nskb->len;
4377
4378 skb_push(nskb, -skb_network_offset(nskb) + offset);
4379
4380 skb_release_head_state(nskb);
4381 len_diff = skb_network_header_len(nskb) - skb_network_header_len(skb);
4382 __copy_skb_header(nskb, skb);
4383
4384 skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
4385 nskb->transport_header += len_diff;
4386 skb_copy_from_linear_data_offset(skb, -tnl_hlen,
4387 nskb->data - tnl_hlen,
4388 offset + tnl_hlen);
4389
4390 if (skb_needs_linearize(nskb, features) &&
4391 __skb_linearize(nskb))
4392 goto err_linearize;
4393 }
4394
4395 skb->truesize = skb->truesize - delta_truesize;
4396 skb->data_len = skb->data_len - delta_len;
4397 skb->len = skb->len - delta_len;
4398
4399 skb_gso_reset(skb);
4400
4401 skb->prev = tail;
4402
4403 if (skb_needs_linearize(skb, features) &&
4404 __skb_linearize(skb))
4405 goto err_linearize;
4406
4407 skb_get(skb);
4408
4409 return skb;
4410
4411 err_linearize:
4412 kfree_skb_list(skb->next);
4413 skb->next = NULL;
4414 return ERR_PTR(-ENOMEM);
4415 }
4416 EXPORT_SYMBOL_GPL(skb_segment_list);
4417
4418 /**
4419 * skb_segment - Perform protocol segmentation on skb.
4420 * @head_skb: buffer to segment
4421 * @features: features for the output path (see dev->features)
4422 *
4423 * This function performs segmentation on the given skb. It returns
4424 * a pointer to the first in a list of new skbs for the segments.
4425 * In case of error it returns ERR_PTR(err).
4426 */
skb_segment(struct sk_buff * head_skb,netdev_features_t features)4427 struct sk_buff *skb_segment(struct sk_buff *head_skb,
4428 netdev_features_t features)
4429 {
4430 struct sk_buff *segs = NULL;
4431 struct sk_buff *tail = NULL;
4432 struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
4433 unsigned int mss = skb_shinfo(head_skb)->gso_size;
4434 unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
4435 unsigned int offset = doffset;
4436 unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
4437 unsigned int partial_segs = 0;
4438 unsigned int headroom;
4439 unsigned int len = head_skb->len;
4440 struct sk_buff *frag_skb;
4441 skb_frag_t *frag;
4442 __be16 proto;
4443 bool csum, sg;
4444 int err = -ENOMEM;
4445 int i = 0;
4446 int nfrags, pos;
4447
4448 if ((skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY) &&
4449 mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb)) {
4450 struct sk_buff *check_skb;
4451
4452 for (check_skb = list_skb; check_skb; check_skb = check_skb->next) {
4453 if (skb_headlen(check_skb) && !check_skb->head_frag) {
4454 /* gso_size is untrusted, and we have a frag_list with
4455 * a linear non head_frag item.
4456 *
4457 * If head_skb's headlen does not fit requested gso_size,
4458 * it means that the frag_list members do NOT terminate
4459 * on exact gso_size boundaries. Hence we cannot perform
4460 * skb_frag_t page sharing. Therefore we must fallback to
4461 * copying the frag_list skbs; we do so by disabling SG.
4462 */
4463 features &= ~NETIF_F_SG;
4464 break;
4465 }
4466 }
4467 }
4468
4469 __skb_push(head_skb, doffset);
4470 proto = skb_network_protocol(head_skb, NULL);
4471 if (unlikely(!proto))
4472 return ERR_PTR(-EINVAL);
4473
4474 sg = !!(features & NETIF_F_SG);
4475 csum = !!can_checksum_protocol(features, proto);
4476
4477 if (sg && csum && (mss != GSO_BY_FRAGS)) {
4478 if (!(features & NETIF_F_GSO_PARTIAL)) {
4479 struct sk_buff *iter;
4480 unsigned int frag_len;
4481
4482 if (!list_skb ||
4483 !net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
4484 goto normal;
4485
4486 /* If we get here then all the required
4487 * GSO features except frag_list are supported.
4488 * Try to split the SKB to multiple GSO SKBs
4489 * with no frag_list.
4490 * Currently we can do that only when the buffers don't
4491 * have a linear part and all the buffers except
4492 * the last are of the same length.
4493 */
4494 frag_len = list_skb->len;
4495 skb_walk_frags(head_skb, iter) {
4496 if (frag_len != iter->len && iter->next)
4497 goto normal;
4498 if (skb_headlen(iter) && !iter->head_frag)
4499 goto normal;
4500
4501 len -= iter->len;
4502 }
4503
4504 if (len != frag_len)
4505 goto normal;
4506 }
4507
4508 /* GSO partial only requires that we trim off any excess that
4509 * doesn't fit into an MSS sized block, so take care of that
4510 * now.
4511 * Cap len to not accidentally hit GSO_BY_FRAGS.
4512 */
4513 partial_segs = min(len, GSO_BY_FRAGS - 1U) / mss;
4514 if (partial_segs > 1)
4515 mss *= partial_segs;
4516 else
4517 partial_segs = 0;
4518 }
4519
4520 normal:
4521 headroom = skb_headroom(head_skb);
4522 pos = skb_headlen(head_skb);
4523
4524 if (skb_orphan_frags(head_skb, GFP_ATOMIC))
4525 return ERR_PTR(-ENOMEM);
4526
4527 nfrags = skb_shinfo(head_skb)->nr_frags;
4528 frag = skb_shinfo(head_skb)->frags;
4529 frag_skb = head_skb;
4530
4531 do {
4532 struct sk_buff *nskb;
4533 skb_frag_t *nskb_frag;
4534 int hsize;
4535 int size;
4536
4537 if (unlikely(mss == GSO_BY_FRAGS)) {
4538 len = list_skb->len;
4539 } else {
4540 len = head_skb->len - offset;
4541 if (len > mss)
4542 len = mss;
4543 }
4544
4545 hsize = skb_headlen(head_skb) - offset;
4546
4547 if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
4548 (skb_headlen(list_skb) == len || sg)) {
4549 BUG_ON(skb_headlen(list_skb) > len);
4550
4551 nskb = skb_clone(list_skb, GFP_ATOMIC);
4552 if (unlikely(!nskb))
4553 goto err;
4554
4555 i = 0;
4556 nfrags = skb_shinfo(list_skb)->nr_frags;
4557 frag = skb_shinfo(list_skb)->frags;
4558 frag_skb = list_skb;
4559 pos += skb_headlen(list_skb);
4560
4561 while (pos < offset + len) {
4562 BUG_ON(i >= nfrags);
4563
4564 size = skb_frag_size(frag);
4565 if (pos + size > offset + len)
4566 break;
4567
4568 i++;
4569 pos += size;
4570 frag++;
4571 }
4572
4573 list_skb = list_skb->next;
4574
4575 if (unlikely(pskb_trim(nskb, len))) {
4576 kfree_skb(nskb);
4577 goto err;
4578 }
4579
4580 hsize = skb_end_offset(nskb);
4581 if (skb_cow_head(nskb, doffset + headroom)) {
4582 kfree_skb(nskb);
4583 goto err;
4584 }
4585
4586 nskb->truesize += skb_end_offset(nskb) - hsize;
4587 skb_release_head_state(nskb);
4588 __skb_push(nskb, doffset);
4589 } else {
4590 if (hsize < 0)
4591 hsize = 0;
4592 if (hsize > len || !sg)
4593 hsize = len;
4594
4595 nskb = __alloc_skb(hsize + doffset + headroom,
4596 GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
4597 NUMA_NO_NODE);
4598
4599 if (unlikely(!nskb))
4600 goto err;
4601
4602 skb_reserve(nskb, headroom);
4603 __skb_put(nskb, doffset);
4604 }
4605
4606 if (segs)
4607 tail->next = nskb;
4608 else
4609 segs = nskb;
4610 tail = nskb;
4611
4612 __copy_skb_header(nskb, head_skb);
4613
4614 skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
4615 skb_reset_mac_len(nskb);
4616
4617 skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
4618 nskb->data - tnl_hlen,
4619 doffset + tnl_hlen);
4620
4621 if (nskb->len == len + doffset)
4622 goto perform_csum_check;
4623
4624 if (!sg) {
4625 if (!csum) {
4626 if (!nskb->remcsum_offload)
4627 nskb->ip_summed = CHECKSUM_NONE;
4628 SKB_GSO_CB(nskb)->csum =
4629 skb_copy_and_csum_bits(head_skb, offset,
4630 skb_put(nskb,
4631 len),
4632 len);
4633 SKB_GSO_CB(nskb)->csum_start =
4634 skb_headroom(nskb) + doffset;
4635 } else {
4636 if (skb_copy_bits(head_skb, offset, skb_put(nskb, len), len))
4637 goto err;
4638 }
4639 continue;
4640 }
4641
4642 nskb_frag = skb_shinfo(nskb)->frags;
4643
4644 skb_copy_from_linear_data_offset(head_skb, offset,
4645 skb_put(nskb, hsize), hsize);
4646
4647 skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
4648 SKBFL_SHARED_FRAG;
4649
4650 if (skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
4651 goto err;
4652
4653 while (pos < offset + len) {
4654 if (i >= nfrags) {
4655 if (skb_orphan_frags(list_skb, GFP_ATOMIC) ||
4656 skb_zerocopy_clone(nskb, list_skb,
4657 GFP_ATOMIC))
4658 goto err;
4659
4660 i = 0;
4661 nfrags = skb_shinfo(list_skb)->nr_frags;
4662 frag = skb_shinfo(list_skb)->frags;
4663 frag_skb = list_skb;
4664 if (!skb_headlen(list_skb)) {
4665 BUG_ON(!nfrags);
4666 } else {
4667 BUG_ON(!list_skb->head_frag);
4668
4669 /* to make room for head_frag. */
4670 i--;
4671 frag--;
4672 }
4673
4674 list_skb = list_skb->next;
4675 }
4676
4677 if (unlikely(skb_shinfo(nskb)->nr_frags >=
4678 MAX_SKB_FRAGS)) {
4679 net_warn_ratelimited(
4680 "skb_segment: too many frags: %u %u\n",
4681 pos, mss);
4682 err = -EINVAL;
4683 goto err;
4684 }
4685
4686 *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
4687 __skb_frag_ref(nskb_frag);
4688 size = skb_frag_size(nskb_frag);
4689
4690 if (pos < offset) {
4691 skb_frag_off_add(nskb_frag, offset - pos);
4692 skb_frag_size_sub(nskb_frag, offset - pos);
4693 }
4694
4695 skb_shinfo(nskb)->nr_frags++;
4696
4697 if (pos + size <= offset + len) {
4698 i++;
4699 frag++;
4700 pos += size;
4701 } else {
4702 skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
4703 goto skip_fraglist;
4704 }
4705
4706 nskb_frag++;
4707 }
4708
4709 skip_fraglist:
4710 nskb->data_len = len - hsize;
4711 nskb->len += nskb->data_len;
4712 nskb->truesize += nskb->data_len;
4713
4714 perform_csum_check:
4715 if (!csum) {
4716 if (skb_has_shared_frag(nskb) &&
4717 __skb_linearize(nskb))
4718 goto err;
4719
4720 if (!nskb->remcsum_offload)
4721 nskb->ip_summed = CHECKSUM_NONE;
4722 SKB_GSO_CB(nskb)->csum =
4723 skb_checksum(nskb, doffset,
4724 nskb->len - doffset, 0);
4725 SKB_GSO_CB(nskb)->csum_start =
4726 skb_headroom(nskb) + doffset;
4727 }
4728 } while ((offset += len) < head_skb->len);
4729
4730 /* Some callers want to get the end of the list.
4731 * Put it in segs->prev to avoid walking the list.
4732 * (see validate_xmit_skb_list() for example)
4733 */
4734 segs->prev = tail;
4735
4736 if (partial_segs) {
4737 struct sk_buff *iter;
4738 int type = skb_shinfo(head_skb)->gso_type;
4739 unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
4740
4741 /* Update type to add partial and then remove dodgy if set */
4742 type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
4743 type &= ~SKB_GSO_DODGY;
4744
4745 /* Update GSO info and prepare to start updating headers on
4746 * our way back down the stack of protocols.
4747 */
4748 for (iter = segs; iter; iter = iter->next) {
4749 skb_shinfo(iter)->gso_size = gso_size;
4750 skb_shinfo(iter)->gso_segs = partial_segs;
4751 skb_shinfo(iter)->gso_type = type;
4752 SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
4753 }
4754
4755 if (tail->len - doffset <= gso_size)
4756 skb_shinfo(tail)->gso_size = 0;
4757 else if (tail != segs)
4758 skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
4759 }
4760
4761 /* Following permits correct backpressure, for protocols
4762 * using skb_set_owner_w().
4763 * Idea is to tranfert ownership from head_skb to last segment.
4764 */
4765 if (head_skb->destructor == sock_wfree) {
4766 swap(tail->truesize, head_skb->truesize);
4767 swap(tail->destructor, head_skb->destructor);
4768 swap(tail->sk, head_skb->sk);
4769 }
4770 return segs;
4771
4772 err:
4773 kfree_skb_list(segs);
4774 return ERR_PTR(err);
4775 }
4776 EXPORT_SYMBOL_GPL(skb_segment);
4777
4778 #ifdef CONFIG_SKB_EXTENSIONS
4779 #define SKB_EXT_ALIGN_VALUE 8
4780 #define SKB_EXT_CHUNKSIZEOF(x) (ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE)
4781
4782 static const u8 skb_ext_type_len[] = {
4783 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4784 [SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info),
4785 #endif
4786 #ifdef CONFIG_XFRM
4787 [SKB_EXT_SEC_PATH] = SKB_EXT_CHUNKSIZEOF(struct sec_path),
4788 #endif
4789 #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4790 [TC_SKB_EXT] = SKB_EXT_CHUNKSIZEOF(struct tc_skb_ext),
4791 #endif
4792 #if IS_ENABLED(CONFIG_MPTCP)
4793 [SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext),
4794 #endif
4795 #if IS_ENABLED(CONFIG_MCTP_FLOWS)
4796 [SKB_EXT_MCTP] = SKB_EXT_CHUNKSIZEOF(struct mctp_flow),
4797 #endif
4798 };
4799
skb_ext_total_length(void)4800 static __always_inline unsigned int skb_ext_total_length(void)
4801 {
4802 unsigned int l = SKB_EXT_CHUNKSIZEOF(struct skb_ext);
4803 int i;
4804
4805 for (i = 0; i < ARRAY_SIZE(skb_ext_type_len); i++)
4806 l += skb_ext_type_len[i];
4807
4808 return l;
4809 }
4810
skb_extensions_init(void)4811 static void skb_extensions_init(void)
4812 {
4813 BUILD_BUG_ON(SKB_EXT_NUM >= 8);
4814 #if !IS_ENABLED(CONFIG_KCOV_INSTRUMENT_ALL)
4815 BUILD_BUG_ON(skb_ext_total_length() > 255);
4816 #endif
4817
4818 skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache",
4819 SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),
4820 0,
4821 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4822 NULL);
4823 }
4824 #else
skb_extensions_init(void)4825 static void skb_extensions_init(void) {}
4826 #endif
4827
4828 /* The SKB kmem_cache slab is critical for network performance. Never
4829 * merge/alias the slab with similar sized objects. This avoids fragmentation
4830 * that hurts performance of kmem_cache_{alloc,free}_bulk APIs.
4831 */
4832 #ifndef CONFIG_SLUB_TINY
4833 #define FLAG_SKB_NO_MERGE SLAB_NO_MERGE
4834 #else /* CONFIG_SLUB_TINY - simple loop in kmem_cache_alloc_bulk */
4835 #define FLAG_SKB_NO_MERGE 0
4836 #endif
4837
skb_init(void)4838 void __init skb_init(void)
4839 {
4840 skbuff_cache = kmem_cache_create_usercopy("skbuff_head_cache",
4841 sizeof(struct sk_buff),
4842 0,
4843 SLAB_HWCACHE_ALIGN|SLAB_PANIC|
4844 FLAG_SKB_NO_MERGE,
4845 offsetof(struct sk_buff, cb),
4846 sizeof_field(struct sk_buff, cb),
4847 NULL);
4848 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
4849 sizeof(struct sk_buff_fclones),
4850 0,
4851 SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4852 NULL);
4853 /* usercopy should only access first SKB_SMALL_HEAD_HEADROOM bytes.
4854 * struct skb_shared_info is located at the end of skb->head,
4855 * and should not be copied to/from user.
4856 */
4857 skb_small_head_cache = kmem_cache_create_usercopy("skbuff_small_head",
4858 SKB_SMALL_HEAD_CACHE_SIZE,
4859 0,
4860 SLAB_HWCACHE_ALIGN | SLAB_PANIC,
4861 0,
4862 SKB_SMALL_HEAD_HEADROOM,
4863 NULL);
4864 skb_extensions_init();
4865 }
4866
4867 static int
__skb_to_sgvec(struct sk_buff * skb,struct scatterlist * sg,int offset,int len,unsigned int recursion_level)4868 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len,
4869 unsigned int recursion_level)
4870 {
4871 int start = skb_headlen(skb);
4872 int i, copy = start - offset;
4873 struct sk_buff *frag_iter;
4874 int elt = 0;
4875
4876 if (unlikely(recursion_level >= 24))
4877 return -EMSGSIZE;
4878
4879 if (copy > 0) {
4880 if (copy > len)
4881 copy = len;
4882 sg_set_buf(sg, skb->data + offset, copy);
4883 elt++;
4884 if ((len -= copy) == 0)
4885 return elt;
4886 offset += copy;
4887 }
4888
4889 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
4890 int end;
4891
4892 WARN_ON(start > offset + len);
4893
4894 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
4895 if ((copy = end - offset) > 0) {
4896 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
4897 if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4898 return -EMSGSIZE;
4899
4900 if (copy > len)
4901 copy = len;
4902 sg_set_page(&sg[elt], skb_frag_page(frag), copy,
4903 skb_frag_off(frag) + offset - start);
4904 elt++;
4905 if (!(len -= copy))
4906 return elt;
4907 offset += copy;
4908 }
4909 start = end;
4910 }
4911
4912 skb_walk_frags(skb, frag_iter) {
4913 int end, ret;
4914
4915 WARN_ON(start > offset + len);
4916
4917 end = start + frag_iter->len;
4918 if ((copy = end - offset) > 0) {
4919 if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4920 return -EMSGSIZE;
4921
4922 if (copy > len)
4923 copy = len;
4924 ret = __skb_to_sgvec(frag_iter, sg+elt, offset - start,
4925 copy, recursion_level + 1);
4926 if (unlikely(ret < 0))
4927 return ret;
4928 elt += ret;
4929 if ((len -= copy) == 0)
4930 return elt;
4931 offset += copy;
4932 }
4933 start = end;
4934 }
4935 BUG_ON(len);
4936 return elt;
4937 }
4938
4939 /**
4940 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
4941 * @skb: Socket buffer containing the buffers to be mapped
4942 * @sg: The scatter-gather list to map into
4943 * @offset: The offset into the buffer's contents to start mapping
4944 * @len: Length of buffer space to be mapped
4945 *
4946 * Fill the specified scatter-gather list with mappings/pointers into a
4947 * region of the buffer space attached to a socket buffer. Returns either
4948 * the number of scatterlist items used, or -EMSGSIZE if the contents
4949 * could not fit.
4950 */
skb_to_sgvec(struct sk_buff * skb,struct scatterlist * sg,int offset,int len)4951 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
4952 {
4953 int nsg = __skb_to_sgvec(skb, sg, offset, len, 0);
4954
4955 if (nsg <= 0)
4956 return nsg;
4957
4958 sg_mark_end(&sg[nsg - 1]);
4959
4960 return nsg;
4961 }
4962 EXPORT_SYMBOL_GPL(skb_to_sgvec);
4963
4964 /* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
4965 * sglist without mark the sg which contain last skb data as the end.
4966 * So the caller can mannipulate sg list as will when padding new data after
4967 * the first call without calling sg_unmark_end to expend sg list.
4968 *
4969 * Scenario to use skb_to_sgvec_nomark:
4970 * 1. sg_init_table
4971 * 2. skb_to_sgvec_nomark(payload1)
4972 * 3. skb_to_sgvec_nomark(payload2)
4973 *
4974 * This is equivalent to:
4975 * 1. sg_init_table
4976 * 2. skb_to_sgvec(payload1)
4977 * 3. sg_unmark_end
4978 * 4. skb_to_sgvec(payload2)
4979 *
4980 * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
4981 * is more preferable.
4982 */
skb_to_sgvec_nomark(struct sk_buff * skb,struct scatterlist * sg,int offset,int len)4983 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
4984 int offset, int len)
4985 {
4986 return __skb_to_sgvec(skb, sg, offset, len, 0);
4987 }
4988 EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
4989
4990
4991
4992 /**
4993 * skb_cow_data - Check that a socket buffer's data buffers are writable
4994 * @skb: The socket buffer to check.
4995 * @tailbits: Amount of trailing space to be added
4996 * @trailer: Returned pointer to the skb where the @tailbits space begins
4997 *
4998 * Make sure that the data buffers attached to a socket buffer are
4999 * writable. If they are not, private copies are made of the data buffers
5000 * and the socket buffer is set to use these instead.
5001 *
5002 * If @tailbits is given, make sure that there is space to write @tailbits
5003 * bytes of data beyond current end of socket buffer. @trailer will be
5004 * set to point to the skb in which this space begins.
5005 *
5006 * The number of scatterlist elements required to completely map the
5007 * COW'd and extended socket buffer will be returned.
5008 */
skb_cow_data(struct sk_buff * skb,int tailbits,struct sk_buff ** trailer)5009 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
5010 {
5011 int copyflag;
5012 int elt;
5013 struct sk_buff *skb1, **skb_p;
5014
5015 /* If skb is cloned or its head is paged, reallocate
5016 * head pulling out all the pages (pages are considered not writable
5017 * at the moment even if they are anonymous).
5018 */
5019 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
5020 !__pskb_pull_tail(skb, __skb_pagelen(skb)))
5021 return -ENOMEM;
5022
5023 /* Easy case. Most of packets will go this way. */
5024 if (!skb_has_frag_list(skb)) {
5025 /* A little of trouble, not enough of space for trailer.
5026 * This should not happen, when stack is tuned to generate
5027 * good frames. OK, on miss we reallocate and reserve even more
5028 * space, 128 bytes is fair. */
5029
5030 if (skb_tailroom(skb) < tailbits &&
5031 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
5032 return -ENOMEM;
5033
5034 /* Voila! */
5035 *trailer = skb;
5036 return 1;
5037 }
5038
5039 /* Misery. We are in troubles, going to mincer fragments... */
5040
5041 elt = 1;
5042 skb_p = &skb_shinfo(skb)->frag_list;
5043 copyflag = 0;
5044
5045 while ((skb1 = *skb_p) != NULL) {
5046 int ntail = 0;
5047
5048 /* The fragment is partially pulled by someone,
5049 * this can happen on input. Copy it and everything
5050 * after it. */
5051
5052 if (skb_shared(skb1))
5053 copyflag = 1;
5054
5055 /* If the skb is the last, worry about trailer. */
5056
5057 if (skb1->next == NULL && tailbits) {
5058 if (skb_shinfo(skb1)->nr_frags ||
5059 skb_has_frag_list(skb1) ||
5060 skb_tailroom(skb1) < tailbits)
5061 ntail = tailbits + 128;
5062 }
5063
5064 if (copyflag ||
5065 skb_cloned(skb1) ||
5066 ntail ||
5067 skb_shinfo(skb1)->nr_frags ||
5068 skb_has_frag_list(skb1)) {
5069 struct sk_buff *skb2;
5070
5071 /* Fuck, we are miserable poor guys... */
5072 if (ntail == 0)
5073 skb2 = skb_copy(skb1, GFP_ATOMIC);
5074 else
5075 skb2 = skb_copy_expand(skb1,
5076 skb_headroom(skb1),
5077 ntail,
5078 GFP_ATOMIC);
5079 if (unlikely(skb2 == NULL))
5080 return -ENOMEM;
5081
5082 if (skb1->sk)
5083 skb_set_owner_w(skb2, skb1->sk);
5084
5085 /* Looking around. Are we still alive?
5086 * OK, link new skb, drop old one */
5087
5088 skb2->next = skb1->next;
5089 *skb_p = skb2;
5090 kfree_skb(skb1);
5091 skb1 = skb2;
5092 }
5093 elt++;
5094 *trailer = skb1;
5095 skb_p = &skb1->next;
5096 }
5097
5098 return elt;
5099 }
5100 EXPORT_SYMBOL_GPL(skb_cow_data);
5101
sock_rmem_free(struct sk_buff * skb)5102 static void sock_rmem_free(struct sk_buff *skb)
5103 {
5104 struct sock *sk = skb->sk;
5105
5106 atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
5107 }
5108
skb_set_err_queue(struct sk_buff * skb)5109 static void skb_set_err_queue(struct sk_buff *skb)
5110 {
5111 /* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
5112 * So, it is safe to (mis)use it to mark skbs on the error queue.
5113 */
5114 skb->pkt_type = PACKET_OUTGOING;
5115 BUILD_BUG_ON(PACKET_OUTGOING == 0);
5116 }
5117
5118 /*
5119 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
5120 */
sock_queue_err_skb(struct sock * sk,struct sk_buff * skb)5121 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
5122 {
5123 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
5124 (unsigned int)READ_ONCE(sk->sk_rcvbuf))
5125 return -ENOMEM;
5126
5127 skb_orphan(skb);
5128 skb->sk = sk;
5129 skb->destructor = sock_rmem_free;
5130 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
5131 skb_set_err_queue(skb);
5132
5133 /* before exiting rcu section, make sure dst is refcounted */
5134 skb_dst_force(skb);
5135
5136 skb_queue_tail(&sk->sk_error_queue, skb);
5137 if (!sock_flag(sk, SOCK_DEAD))
5138 sk_error_report(sk);
5139 return 0;
5140 }
5141 EXPORT_SYMBOL(sock_queue_err_skb);
5142
is_icmp_err_skb(const struct sk_buff * skb)5143 static bool is_icmp_err_skb(const struct sk_buff *skb)
5144 {
5145 return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
5146 SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6);
5147 }
5148
sock_dequeue_err_skb(struct sock * sk)5149 struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
5150 {
5151 struct sk_buff_head *q = &sk->sk_error_queue;
5152 struct sk_buff *skb, *skb_next = NULL;
5153 bool icmp_next = false;
5154 unsigned long flags;
5155
5156 spin_lock_irqsave(&q->lock, flags);
5157 skb = __skb_dequeue(q);
5158 if (skb && (skb_next = skb_peek(q))) {
5159 icmp_next = is_icmp_err_skb(skb_next);
5160 if (icmp_next)
5161 sk->sk_err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
5162 }
5163 spin_unlock_irqrestore(&q->lock, flags);
5164
5165 if (is_icmp_err_skb(skb) && !icmp_next)
5166 sk->sk_err = 0;
5167
5168 if (skb_next)
5169 sk_error_report(sk);
5170
5171 return skb;
5172 }
5173 EXPORT_SYMBOL(sock_dequeue_err_skb);
5174
5175 /**
5176 * skb_clone_sk - create clone of skb, and take reference to socket
5177 * @skb: the skb to clone
5178 *
5179 * This function creates a clone of a buffer that holds a reference on
5180 * sk_refcnt. Buffers created via this function are meant to be
5181 * returned using sock_queue_err_skb, or free via kfree_skb.
5182 *
5183 * When passing buffers allocated with this function to sock_queue_err_skb
5184 * it is necessary to wrap the call with sock_hold/sock_put in order to
5185 * prevent the socket from being released prior to being enqueued on
5186 * the sk_error_queue.
5187 */
skb_clone_sk(struct sk_buff * skb)5188 struct sk_buff *skb_clone_sk(struct sk_buff *skb)
5189 {
5190 struct sock *sk = skb->sk;
5191 struct sk_buff *clone;
5192
5193 if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
5194 return NULL;
5195
5196 clone = skb_clone(skb, GFP_ATOMIC);
5197 if (!clone) {
5198 sock_put(sk);
5199 return NULL;
5200 }
5201
5202 clone->sk = sk;
5203 clone->destructor = sock_efree;
5204
5205 return clone;
5206 }
5207 EXPORT_SYMBOL(skb_clone_sk);
5208
__skb_complete_tx_timestamp(struct sk_buff * skb,struct sock * sk,int tstype,bool opt_stats)5209 static void __skb_complete_tx_timestamp(struct sk_buff *skb,
5210 struct sock *sk,
5211 int tstype,
5212 bool opt_stats)
5213 {
5214 struct sock_exterr_skb *serr;
5215 int err;
5216
5217 BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));
5218
5219 serr = SKB_EXT_ERR(skb);
5220 memset(serr, 0, sizeof(*serr));
5221 serr->ee.ee_errno = ENOMSG;
5222 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
5223 serr->ee.ee_info = tstype;
5224 serr->opt_stats = opt_stats;
5225 serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0;
5226 if (READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) {
5227 serr->ee.ee_data = skb_shinfo(skb)->tskey;
5228 if (sk_is_tcp(sk))
5229 serr->ee.ee_data -= atomic_read(&sk->sk_tskey);
5230 }
5231
5232 err = sock_queue_err_skb(sk, skb);
5233
5234 if (err)
5235 kfree_skb(skb);
5236 }
5237
skb_may_tx_timestamp(struct sock * sk,bool tsonly)5238 static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
5239 {
5240 bool ret;
5241
5242 if (likely(READ_ONCE(sysctl_tstamp_allow_data) || tsonly))
5243 return true;
5244
5245 read_lock_bh(&sk->sk_callback_lock);
5246 ret = sk->sk_socket && sk->sk_socket->file &&
5247 file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
5248 read_unlock_bh(&sk->sk_callback_lock);
5249 return ret;
5250 }
5251
skb_complete_tx_timestamp(struct sk_buff * skb,struct skb_shared_hwtstamps * hwtstamps)5252 void skb_complete_tx_timestamp(struct sk_buff *skb,
5253 struct skb_shared_hwtstamps *hwtstamps)
5254 {
5255 struct sock *sk = skb->sk;
5256
5257 if (!skb_may_tx_timestamp(sk, false))
5258 goto err;
5259
5260 /* Take a reference to prevent skb_orphan() from freeing the socket,
5261 * but only if the socket refcount is not zero.
5262 */
5263 if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
5264 *skb_hwtstamps(skb) = *hwtstamps;
5265 __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
5266 sock_put(sk);
5267 return;
5268 }
5269
5270 err:
5271 kfree_skb(skb);
5272 }
5273 EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
5274
__skb_tstamp_tx(struct sk_buff * orig_skb,const struct sk_buff * ack_skb,struct skb_shared_hwtstamps * hwtstamps,struct sock * sk,int tstype)5275 void __skb_tstamp_tx(struct sk_buff *orig_skb,
5276 const struct sk_buff *ack_skb,
5277 struct skb_shared_hwtstamps *hwtstamps,
5278 struct sock *sk, int tstype)
5279 {
5280 struct sk_buff *skb;
5281 bool tsonly, opt_stats = false;
5282 u32 tsflags;
5283
5284 if (!sk)
5285 return;
5286
5287 tsflags = READ_ONCE(sk->sk_tsflags);
5288 if (!hwtstamps && !(tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
5289 skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
5290 return;
5291
5292 tsonly = tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
5293 if (!skb_may_tx_timestamp(sk, tsonly))
5294 return;
5295
5296 if (tsonly) {
5297 #ifdef CONFIG_INET
5298 if ((tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
5299 sk_is_tcp(sk)) {
5300 skb = tcp_get_timestamping_opt_stats(sk, orig_skb,
5301 ack_skb);
5302 opt_stats = true;
5303 } else
5304 #endif
5305 skb = alloc_skb(0, GFP_ATOMIC);
5306 } else {
5307 skb = skb_clone(orig_skb, GFP_ATOMIC);
5308
5309 if (skb_orphan_frags_rx(skb, GFP_ATOMIC)) {
5310 kfree_skb(skb);
5311 return;
5312 }
5313 }
5314 if (!skb)
5315 return;
5316
5317 if (tsonly) {
5318 skb_shinfo(skb)->tx_flags |= skb_shinfo(orig_skb)->tx_flags &
5319 SKBTX_ANY_TSTAMP;
5320 skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
5321 }
5322
5323 if (hwtstamps)
5324 *skb_hwtstamps(skb) = *hwtstamps;
5325 else
5326 __net_timestamp(skb);
5327
5328 __skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
5329 }
5330 EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
5331
skb_tstamp_tx(struct sk_buff * orig_skb,struct skb_shared_hwtstamps * hwtstamps)5332 void skb_tstamp_tx(struct sk_buff *orig_skb,
5333 struct skb_shared_hwtstamps *hwtstamps)
5334 {
5335 return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,
5336 SCM_TSTAMP_SND);
5337 }
5338 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
5339
5340 #ifdef CONFIG_WIRELESS
skb_complete_wifi_ack(struct sk_buff * skb,bool acked)5341 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
5342 {
5343 struct sock *sk = skb->sk;
5344 struct sock_exterr_skb *serr;
5345 int err = 1;
5346
5347 skb->wifi_acked_valid = 1;
5348 skb->wifi_acked = acked;
5349
5350 serr = SKB_EXT_ERR(skb);
5351 memset(serr, 0, sizeof(*serr));
5352 serr->ee.ee_errno = ENOMSG;
5353 serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
5354
5355 /* Take a reference to prevent skb_orphan() from freeing the socket,
5356 * but only if the socket refcount is not zero.
5357 */
5358 if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
5359 err = sock_queue_err_skb(sk, skb);
5360 sock_put(sk);
5361 }
5362 if (err)
5363 kfree_skb(skb);
5364 }
5365 EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
5366 #endif /* CONFIG_WIRELESS */
5367
5368 /**
5369 * skb_partial_csum_set - set up and verify partial csum values for packet
5370 * @skb: the skb to set
5371 * @start: the number of bytes after skb->data to start checksumming.
5372 * @off: the offset from start to place the checksum.
5373 *
5374 * For untrusted partially-checksummed packets, we need to make sure the values
5375 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
5376 *
5377 * This function checks and sets those values and skb->ip_summed: if this
5378 * returns false you should drop the packet.
5379 */
skb_partial_csum_set(struct sk_buff * skb,u16 start,u16 off)5380 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
5381 {
5382 u32 csum_end = (u32)start + (u32)off + sizeof(__sum16);
5383 u32 csum_start = skb_headroom(skb) + (u32)start;
5384
5385 if (unlikely(csum_start >= U16_MAX || csum_end > skb_headlen(skb))) {
5386 net_warn_ratelimited("bad partial csum: csum=%u/%u headroom=%u headlen=%u\n",
5387 start, off, skb_headroom(skb), skb_headlen(skb));
5388 return false;
5389 }
5390 skb->ip_summed = CHECKSUM_PARTIAL;
5391 skb->csum_start = csum_start;
5392 skb->csum_offset = off;
5393 skb->transport_header = csum_start;
5394 return true;
5395 }
5396 EXPORT_SYMBOL_GPL(skb_partial_csum_set);
5397
skb_maybe_pull_tail(struct sk_buff * skb,unsigned int len,unsigned int max)5398 static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
5399 unsigned int max)
5400 {
5401 if (skb_headlen(skb) >= len)
5402 return 0;
5403
5404 /* If we need to pullup then pullup to the max, so we
5405 * won't need to do it again.
5406 */
5407 if (max > skb->len)
5408 max = skb->len;
5409
5410 if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
5411 return -ENOMEM;
5412
5413 if (skb_headlen(skb) < len)
5414 return -EPROTO;
5415
5416 return 0;
5417 }
5418
5419 #define MAX_TCP_HDR_LEN (15 * 4)
5420
skb_checksum_setup_ip(struct sk_buff * skb,typeof(IPPROTO_IP) proto,unsigned int off)5421 static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
5422 typeof(IPPROTO_IP) proto,
5423 unsigned int off)
5424 {
5425 int err;
5426
5427 switch (proto) {
5428 case IPPROTO_TCP:
5429 err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
5430 off + MAX_TCP_HDR_LEN);
5431 if (!err && !skb_partial_csum_set(skb, off,
5432 offsetof(struct tcphdr,
5433 check)))
5434 err = -EPROTO;
5435 return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
5436
5437 case IPPROTO_UDP:
5438 err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
5439 off + sizeof(struct udphdr));
5440 if (!err && !skb_partial_csum_set(skb, off,
5441 offsetof(struct udphdr,
5442 check)))
5443 err = -EPROTO;
5444 return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
5445 }
5446
5447 return ERR_PTR(-EPROTO);
5448 }
5449
5450 /* This value should be large enough to cover a tagged ethernet header plus
5451 * maximally sized IP and TCP or UDP headers.
5452 */
5453 #define MAX_IP_HDR_LEN 128
5454
skb_checksum_setup_ipv4(struct sk_buff * skb,bool recalculate)5455 static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
5456 {
5457 unsigned int off;
5458 bool fragment;
5459 __sum16 *csum;
5460 int err;
5461
5462 fragment = false;
5463
5464 err = skb_maybe_pull_tail(skb,
5465 sizeof(struct iphdr),
5466 MAX_IP_HDR_LEN);
5467 if (err < 0)
5468 goto out;
5469
5470 if (ip_is_fragment(ip_hdr(skb)))
5471 fragment = true;
5472
5473 off = ip_hdrlen(skb);
5474
5475 err = -EPROTO;
5476
5477 if (fragment)
5478 goto out;
5479
5480 csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
5481 if (IS_ERR(csum))
5482 return PTR_ERR(csum);
5483
5484 if (recalculate)
5485 *csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
5486 ip_hdr(skb)->daddr,
5487 skb->len - off,
5488 ip_hdr(skb)->protocol, 0);
5489 err = 0;
5490
5491 out:
5492 return err;
5493 }
5494
5495 /* This value should be large enough to cover a tagged ethernet header plus
5496 * an IPv6 header, all options, and a maximal TCP or UDP header.
5497 */
5498 #define MAX_IPV6_HDR_LEN 256
5499
5500 #define OPT_HDR(type, skb, off) \
5501 (type *)(skb_network_header(skb) + (off))
5502
skb_checksum_setup_ipv6(struct sk_buff * skb,bool recalculate)5503 static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
5504 {
5505 int err;
5506 u8 nexthdr;
5507 unsigned int off;
5508 unsigned int len;
5509 bool fragment;
5510 bool done;
5511 __sum16 *csum;
5512
5513 fragment = false;
5514 done = false;
5515
5516 off = sizeof(struct ipv6hdr);
5517
5518 err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
5519 if (err < 0)
5520 goto out;
5521
5522 nexthdr = ipv6_hdr(skb)->nexthdr;
5523
5524 len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
5525 while (off <= len && !done) {
5526 switch (nexthdr) {
5527 case IPPROTO_DSTOPTS:
5528 case IPPROTO_HOPOPTS:
5529 case IPPROTO_ROUTING: {
5530 struct ipv6_opt_hdr *hp;
5531
5532 err = skb_maybe_pull_tail(skb,
5533 off +
5534 sizeof(struct ipv6_opt_hdr),
5535 MAX_IPV6_HDR_LEN);
5536 if (err < 0)
5537 goto out;
5538
5539 hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
5540 nexthdr = hp->nexthdr;
5541 off += ipv6_optlen(hp);
5542 break;
5543 }
5544 case IPPROTO_AH: {
5545 struct ip_auth_hdr *hp;
5546
5547 err = skb_maybe_pull_tail(skb,
5548 off +
5549 sizeof(struct ip_auth_hdr),
5550 MAX_IPV6_HDR_LEN);
5551 if (err < 0)
5552 goto out;
5553
5554 hp = OPT_HDR(struct ip_auth_hdr, skb, off);
5555 nexthdr = hp->nexthdr;
5556 off += ipv6_authlen(hp);
5557 break;
5558 }
5559 case IPPROTO_FRAGMENT: {
5560 struct frag_hdr *hp;
5561
5562 err = skb_maybe_pull_tail(skb,
5563 off +
5564 sizeof(struct frag_hdr),
5565 MAX_IPV6_HDR_LEN);
5566 if (err < 0)
5567 goto out;
5568
5569 hp = OPT_HDR(struct frag_hdr, skb, off);
5570
5571 if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
5572 fragment = true;
5573
5574 nexthdr = hp->nexthdr;
5575 off += sizeof(struct frag_hdr);
5576 break;
5577 }
5578 default:
5579 done = true;
5580 break;
5581 }
5582 }
5583
5584 err = -EPROTO;
5585
5586 if (!done || fragment)
5587 goto out;
5588
5589 csum = skb_checksum_setup_ip(skb, nexthdr, off);
5590 if (IS_ERR(csum))
5591 return PTR_ERR(csum);
5592
5593 if (recalculate)
5594 *csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
5595 &ipv6_hdr(skb)->daddr,
5596 skb->len - off, nexthdr, 0);
5597 err = 0;
5598
5599 out:
5600 return err;
5601 }
5602
5603 /**
5604 * skb_checksum_setup - set up partial checksum offset
5605 * @skb: the skb to set up
5606 * @recalculate: if true the pseudo-header checksum will be recalculated
5607 */
skb_checksum_setup(struct sk_buff * skb,bool recalculate)5608 int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
5609 {
5610 int err;
5611
5612 switch (skb->protocol) {
5613 case htons(ETH_P_IP):
5614 err = skb_checksum_setup_ipv4(skb, recalculate);
5615 break;
5616
5617 case htons(ETH_P_IPV6):
5618 err = skb_checksum_setup_ipv6(skb, recalculate);
5619 break;
5620
5621 default:
5622 err = -EPROTO;
5623 break;
5624 }
5625
5626 return err;
5627 }
5628 EXPORT_SYMBOL(skb_checksum_setup);
5629
5630 /**
5631 * skb_checksum_maybe_trim - maybe trims the given skb
5632 * @skb: the skb to check
5633 * @transport_len: the data length beyond the network header
5634 *
5635 * Checks whether the given skb has data beyond the given transport length.
5636 * If so, returns a cloned skb trimmed to this transport length.
5637 * Otherwise returns the provided skb. Returns NULL in error cases
5638 * (e.g. transport_len exceeds skb length or out-of-memory).
5639 *
5640 * Caller needs to set the skb transport header and free any returned skb if it
5641 * differs from the provided skb.
5642 */
skb_checksum_maybe_trim(struct sk_buff * skb,unsigned int transport_len)5643 static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
5644 unsigned int transport_len)
5645 {
5646 struct sk_buff *skb_chk;
5647 unsigned int len = skb_transport_offset(skb) + transport_len;
5648 int ret;
5649
5650 if (skb->len < len)
5651 return NULL;
5652 else if (skb->len == len)
5653 return skb;
5654
5655 skb_chk = skb_clone(skb, GFP_ATOMIC);
5656 if (!skb_chk)
5657 return NULL;
5658
5659 ret = pskb_trim_rcsum(skb_chk, len);
5660 if (ret) {
5661 kfree_skb(skb_chk);
5662 return NULL;
5663 }
5664
5665 return skb_chk;
5666 }
5667
5668 /**
5669 * skb_checksum_trimmed - validate checksum of an skb
5670 * @skb: the skb to check
5671 * @transport_len: the data length beyond the network header
5672 * @skb_chkf: checksum function to use
5673 *
5674 * Applies the given checksum function skb_chkf to the provided skb.
5675 * Returns a checked and maybe trimmed skb. Returns NULL on error.
5676 *
5677 * If the skb has data beyond the given transport length, then a
5678 * trimmed & cloned skb is checked and returned.
5679 *
5680 * Caller needs to set the skb transport header and free any returned skb if it
5681 * differs from the provided skb.
5682 */
skb_checksum_trimmed(struct sk_buff * skb,unsigned int transport_len,__sum16 (* skb_chkf)(struct sk_buff * skb))5683 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
5684 unsigned int transport_len,
5685 __sum16(*skb_chkf)(struct sk_buff *skb))
5686 {
5687 struct sk_buff *skb_chk;
5688 unsigned int offset = skb_transport_offset(skb);
5689 __sum16 ret;
5690
5691 skb_chk = skb_checksum_maybe_trim(skb, transport_len);
5692 if (!skb_chk)
5693 goto err;
5694
5695 if (!pskb_may_pull(skb_chk, offset))
5696 goto err;
5697
5698 skb_pull_rcsum(skb_chk, offset);
5699 ret = skb_chkf(skb_chk);
5700 skb_push_rcsum(skb_chk, offset);
5701
5702 if (ret)
5703 goto err;
5704
5705 return skb_chk;
5706
5707 err:
5708 if (skb_chk && skb_chk != skb)
5709 kfree_skb(skb_chk);
5710
5711 return NULL;
5712
5713 }
5714 EXPORT_SYMBOL(skb_checksum_trimmed);
5715
__skb_warn_lro_forwarding(const struct sk_buff * skb)5716 void __skb_warn_lro_forwarding(const struct sk_buff *skb)
5717 {
5718 net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
5719 skb->dev->name);
5720 }
5721 EXPORT_SYMBOL(__skb_warn_lro_forwarding);
5722
kfree_skb_partial(struct sk_buff * skb,bool head_stolen)5723 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
5724 {
5725 if (head_stolen) {
5726 skb_release_head_state(skb);
5727 kmem_cache_free(skbuff_cache, skb);
5728 } else {
5729 __kfree_skb(skb);
5730 }
5731 }
5732 EXPORT_SYMBOL(kfree_skb_partial);
5733
5734 /**
5735 * skb_try_coalesce - try to merge skb to prior one
5736 * @to: prior buffer
5737 * @from: buffer to add
5738 * @fragstolen: pointer to boolean
5739 * @delta_truesize: how much more was allocated than was requested
5740 */
skb_try_coalesce(struct sk_buff * to,struct sk_buff * from,bool * fragstolen,int * delta_truesize)5741 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
5742 bool *fragstolen, int *delta_truesize)
5743 {
5744 struct skb_shared_info *to_shinfo, *from_shinfo;
5745 int i, delta, len = from->len;
5746
5747 *fragstolen = false;
5748
5749 if (skb_cloned(to))
5750 return false;
5751
5752 /* In general, avoid mixing page_pool and non-page_pool allocated
5753 * pages within the same SKB. Additionally avoid dealing with clones
5754 * with page_pool pages, in case the SKB is using page_pool fragment
5755 * references (PP_FLAG_PAGE_FRAG). Since we only take full page
5756 * references for cloned SKBs at the moment that would result in
5757 * inconsistent reference counts.
5758 * In theory we could take full references if @from is cloned and
5759 * !@to->pp_recycle but its tricky (due to potential race with
5760 * the clone disappearing) and rare, so not worth dealing with.
5761 */
5762 if (to->pp_recycle != from->pp_recycle ||
5763 (from->pp_recycle && skb_cloned(from)))
5764 return false;
5765
5766 if (len <= skb_tailroom(to)) {
5767 if (len)
5768 BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
5769 *delta_truesize = 0;
5770 return true;
5771 }
5772
5773 to_shinfo = skb_shinfo(to);
5774 from_shinfo = skb_shinfo(from);
5775 if (to_shinfo->frag_list || from_shinfo->frag_list)
5776 return false;
5777 if (skb_zcopy(to) || skb_zcopy(from))
5778 return false;
5779
5780 if (skb_headlen(from) != 0) {
5781 struct page *page;
5782 unsigned int offset;
5783
5784 if (to_shinfo->nr_frags +
5785 from_shinfo->nr_frags >= MAX_SKB_FRAGS)
5786 return false;
5787
5788 if (skb_head_is_locked(from))
5789 return false;
5790
5791 delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
5792
5793 page = virt_to_head_page(from->head);
5794 offset = from->data - (unsigned char *)page_address(page);
5795
5796 skb_fill_page_desc(to, to_shinfo->nr_frags,
5797 page, offset, skb_headlen(from));
5798 *fragstolen = true;
5799 } else {
5800 if (to_shinfo->nr_frags +
5801 from_shinfo->nr_frags > MAX_SKB_FRAGS)
5802 return false;
5803
5804 delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
5805 }
5806
5807 WARN_ON_ONCE(delta < len);
5808
5809 memcpy(to_shinfo->frags + to_shinfo->nr_frags,
5810 from_shinfo->frags,
5811 from_shinfo->nr_frags * sizeof(skb_frag_t));
5812 to_shinfo->nr_frags += from_shinfo->nr_frags;
5813
5814 if (!skb_cloned(from))
5815 from_shinfo->nr_frags = 0;
5816
5817 /* if the skb is not cloned this does nothing
5818 * since we set nr_frags to 0.
5819 */
5820 for (i = 0; i < from_shinfo->nr_frags; i++)
5821 __skb_frag_ref(&from_shinfo->frags[i]);
5822
5823 to->truesize += delta;
5824 to->len += len;
5825 to->data_len += len;
5826
5827 *delta_truesize = delta;
5828 return true;
5829 }
5830 EXPORT_SYMBOL(skb_try_coalesce);
5831
5832 /**
5833 * skb_scrub_packet - scrub an skb
5834 *
5835 * @skb: buffer to clean
5836 * @xnet: packet is crossing netns
5837 *
5838 * skb_scrub_packet can be used after encapsulating or decapsulting a packet
5839 * into/from a tunnel. Some information have to be cleared during these
5840 * operations.
5841 * skb_scrub_packet can also be used to clean a skb before injecting it in
5842 * another namespace (@xnet == true). We have to clear all information in the
5843 * skb that could impact namespace isolation.
5844 */
skb_scrub_packet(struct sk_buff * skb,bool xnet)5845 void skb_scrub_packet(struct sk_buff *skb, bool xnet)
5846 {
5847 skb->pkt_type = PACKET_HOST;
5848 skb->skb_iif = 0;
5849 skb->ignore_df = 0;
5850 skb_dst_drop(skb);
5851 skb_ext_reset(skb);
5852 nf_reset_ct(skb);
5853 nf_reset_trace(skb);
5854
5855 #ifdef CONFIG_NET_SWITCHDEV
5856 skb->offload_fwd_mark = 0;
5857 skb->offload_l3_fwd_mark = 0;
5858 #endif
5859
5860 if (!xnet)
5861 return;
5862
5863 ipvs_reset(skb);
5864 skb->mark = 0;
5865 skb_clear_tstamp(skb);
5866 }
5867 EXPORT_SYMBOL_GPL(skb_scrub_packet);
5868
skb_reorder_vlan_header(struct sk_buff * skb)5869 static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
5870 {
5871 int mac_len, meta_len;
5872 void *meta;
5873
5874 if (skb_cow(skb, skb_headroom(skb)) < 0) {
5875 kfree_skb(skb);
5876 return NULL;
5877 }
5878
5879 mac_len = skb->data - skb_mac_header(skb);
5880 if (likely(mac_len > VLAN_HLEN + ETH_TLEN)) {
5881 memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
5882 mac_len - VLAN_HLEN - ETH_TLEN);
5883 }
5884
5885 meta_len = skb_metadata_len(skb);
5886 if (meta_len) {
5887 meta = skb_metadata_end(skb) - meta_len;
5888 memmove(meta + VLAN_HLEN, meta, meta_len);
5889 }
5890
5891 skb->mac_header += VLAN_HLEN;
5892 return skb;
5893 }
5894
skb_vlan_untag(struct sk_buff * skb)5895 struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
5896 {
5897 struct vlan_hdr *vhdr;
5898 u16 vlan_tci;
5899
5900 if (unlikely(skb_vlan_tag_present(skb))) {
5901 /* vlan_tci is already set-up so leave this for another time */
5902 return skb;
5903 }
5904
5905 skb = skb_share_check(skb, GFP_ATOMIC);
5906 if (unlikely(!skb))
5907 goto err_free;
5908 /* We may access the two bytes after vlan_hdr in vlan_set_encap_proto(). */
5909 if (unlikely(!pskb_may_pull(skb, VLAN_HLEN + sizeof(unsigned short))))
5910 goto err_free;
5911
5912 vhdr = (struct vlan_hdr *)skb->data;
5913 vlan_tci = ntohs(vhdr->h_vlan_TCI);
5914 __vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
5915
5916 skb_pull_rcsum(skb, VLAN_HLEN);
5917 vlan_set_encap_proto(skb, vhdr);
5918
5919 skb = skb_reorder_vlan_header(skb);
5920 if (unlikely(!skb))
5921 goto err_free;
5922
5923 skb_reset_network_header(skb);
5924 if (!skb_transport_header_was_set(skb))
5925 skb_reset_transport_header(skb);
5926 skb_reset_mac_len(skb);
5927
5928 return skb;
5929
5930 err_free:
5931 kfree_skb(skb);
5932 return NULL;
5933 }
5934 EXPORT_SYMBOL(skb_vlan_untag);
5935
skb_ensure_writable(struct sk_buff * skb,unsigned int write_len)5936 int skb_ensure_writable(struct sk_buff *skb, unsigned int write_len)
5937 {
5938 if (!pskb_may_pull(skb, write_len))
5939 return -ENOMEM;
5940
5941 if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
5942 return 0;
5943
5944 return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
5945 }
5946 EXPORT_SYMBOL(skb_ensure_writable);
5947
5948 /* remove VLAN header from packet and update csum accordingly.
5949 * expects a non skb_vlan_tag_present skb with a vlan tag payload
5950 */
__skb_vlan_pop(struct sk_buff * skb,u16 * vlan_tci)5951 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
5952 {
5953 int offset = skb->data - skb_mac_header(skb);
5954 int err;
5955
5956 if (WARN_ONCE(offset,
5957 "__skb_vlan_pop got skb with skb->data not at mac header (offset %d)\n",
5958 offset)) {
5959 return -EINVAL;
5960 }
5961
5962 err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
5963 if (unlikely(err))
5964 return err;
5965
5966 skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
5967
5968 vlan_remove_tag(skb, vlan_tci);
5969
5970 skb->mac_header += VLAN_HLEN;
5971
5972 if (skb_network_offset(skb) < ETH_HLEN)
5973 skb_set_network_header(skb, ETH_HLEN);
5974
5975 skb_reset_mac_len(skb);
5976
5977 return err;
5978 }
5979 EXPORT_SYMBOL(__skb_vlan_pop);
5980
5981 /* Pop a vlan tag either from hwaccel or from payload.
5982 * Expects skb->data at mac header.
5983 */
skb_vlan_pop(struct sk_buff * skb)5984 int skb_vlan_pop(struct sk_buff *skb)
5985 {
5986 u16 vlan_tci;
5987 __be16 vlan_proto;
5988 int err;
5989
5990 if (likely(skb_vlan_tag_present(skb))) {
5991 __vlan_hwaccel_clear_tag(skb);
5992 } else {
5993 if (unlikely(!eth_type_vlan(skb->protocol)))
5994 return 0;
5995
5996 err = __skb_vlan_pop(skb, &vlan_tci);
5997 if (err)
5998 return err;
5999 }
6000 /* move next vlan tag to hw accel tag */
6001 if (likely(!eth_type_vlan(skb->protocol)))
6002 return 0;
6003
6004 vlan_proto = skb->protocol;
6005 err = __skb_vlan_pop(skb, &vlan_tci);
6006 if (unlikely(err))
6007 return err;
6008
6009 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
6010 return 0;
6011 }
6012 EXPORT_SYMBOL(skb_vlan_pop);
6013
6014 /* Push a vlan tag either into hwaccel or into payload (if hwaccel tag present).
6015 * Expects skb->data at mac header.
6016 */
skb_vlan_push(struct sk_buff * skb,__be16 vlan_proto,u16 vlan_tci)6017 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
6018 {
6019 if (skb_vlan_tag_present(skb)) {
6020 int offset = skb->data - skb_mac_header(skb);
6021 int err;
6022
6023 if (WARN_ONCE(offset,
6024 "skb_vlan_push got skb with skb->data not at mac header (offset %d)\n",
6025 offset)) {
6026 return -EINVAL;
6027 }
6028
6029 err = __vlan_insert_tag(skb, skb->vlan_proto,
6030 skb_vlan_tag_get(skb));
6031 if (err)
6032 return err;
6033
6034 skb->protocol = skb->vlan_proto;
6035 skb->mac_len += VLAN_HLEN;
6036
6037 skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
6038 }
6039 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
6040 return 0;
6041 }
6042 EXPORT_SYMBOL(skb_vlan_push);
6043
6044 /**
6045 * skb_eth_pop() - Drop the Ethernet header at the head of a packet
6046 *
6047 * @skb: Socket buffer to modify
6048 *
6049 * Drop the Ethernet header of @skb.
6050 *
6051 * Expects that skb->data points to the mac header and that no VLAN tags are
6052 * present.
6053 *
6054 * Returns 0 on success, -errno otherwise.
6055 */
skb_eth_pop(struct sk_buff * skb)6056 int skb_eth_pop(struct sk_buff *skb)
6057 {
6058 if (!pskb_may_pull(skb, ETH_HLEN) || skb_vlan_tagged(skb) ||
6059 skb_network_offset(skb) < ETH_HLEN)
6060 return -EPROTO;
6061
6062 skb_pull_rcsum(skb, ETH_HLEN);
6063 skb_reset_mac_header(skb);
6064 skb_reset_mac_len(skb);
6065
6066 return 0;
6067 }
6068 EXPORT_SYMBOL(skb_eth_pop);
6069
6070 /**
6071 * skb_eth_push() - Add a new Ethernet header at the head of a packet
6072 *
6073 * @skb: Socket buffer to modify
6074 * @dst: Destination MAC address of the new header
6075 * @src: Source MAC address of the new header
6076 *
6077 * Prepend @skb with a new Ethernet header.
6078 *
6079 * Expects that skb->data points to the mac header, which must be empty.
6080 *
6081 * Returns 0 on success, -errno otherwise.
6082 */
skb_eth_push(struct sk_buff * skb,const unsigned char * dst,const unsigned char * src)6083 int skb_eth_push(struct sk_buff *skb, const unsigned char *dst,
6084 const unsigned char *src)
6085 {
6086 struct ethhdr *eth;
6087 int err;
6088
6089 if (skb_network_offset(skb) || skb_vlan_tag_present(skb))
6090 return -EPROTO;
6091
6092 err = skb_cow_head(skb, sizeof(*eth));
6093 if (err < 0)
6094 return err;
6095
6096 skb_push(skb, sizeof(*eth));
6097 skb_reset_mac_header(skb);
6098 skb_reset_mac_len(skb);
6099
6100 eth = eth_hdr(skb);
6101 ether_addr_copy(eth->h_dest, dst);
6102 ether_addr_copy(eth->h_source, src);
6103 eth->h_proto = skb->protocol;
6104
6105 skb_postpush_rcsum(skb, eth, sizeof(*eth));
6106
6107 return 0;
6108 }
6109 EXPORT_SYMBOL(skb_eth_push);
6110
6111 /* Update the ethertype of hdr and the skb csum value if required. */
skb_mod_eth_type(struct sk_buff * skb,struct ethhdr * hdr,__be16 ethertype)6112 static void skb_mod_eth_type(struct sk_buff *skb, struct ethhdr *hdr,
6113 __be16 ethertype)
6114 {
6115 if (skb->ip_summed == CHECKSUM_COMPLETE) {
6116 __be16 diff[] = { ~hdr->h_proto, ethertype };
6117
6118 skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
6119 }
6120
6121 hdr->h_proto = ethertype;
6122 }
6123
6124 /**
6125 * skb_mpls_push() - push a new MPLS header after mac_len bytes from start of
6126 * the packet
6127 *
6128 * @skb: buffer
6129 * @mpls_lse: MPLS label stack entry to push
6130 * @mpls_proto: ethertype of the new MPLS header (expects 0x8847 or 0x8848)
6131 * @mac_len: length of the MAC header
6132 * @ethernet: flag to indicate if the resulting packet after skb_mpls_push is
6133 * ethernet
6134 *
6135 * Expects skb->data at mac header.
6136 *
6137 * Returns 0 on success, -errno otherwise.
6138 */
skb_mpls_push(struct sk_buff * skb,__be32 mpls_lse,__be16 mpls_proto,int mac_len,bool ethernet)6139 int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
6140 int mac_len, bool ethernet)
6141 {
6142 struct mpls_shim_hdr *lse;
6143 int err;
6144
6145 if (unlikely(!eth_p_mpls(mpls_proto)))
6146 return -EINVAL;
6147
6148 /* Networking stack does not allow simultaneous Tunnel and MPLS GSO. */
6149 if (skb->encapsulation)
6150 return -EINVAL;
6151
6152 err = skb_cow_head(skb, MPLS_HLEN);
6153 if (unlikely(err))
6154 return err;
6155
6156 if (!skb->inner_protocol) {
6157 skb_set_inner_network_header(skb, skb_network_offset(skb));
6158 skb_set_inner_protocol(skb, skb->protocol);
6159 }
6160
6161 skb_push(skb, MPLS_HLEN);
6162 memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
6163 mac_len);
6164 skb_reset_mac_header(skb);
6165 skb_set_network_header(skb, mac_len);
6166 skb_reset_mac_len(skb);
6167
6168 lse = mpls_hdr(skb);
6169 lse->label_stack_entry = mpls_lse;
6170 skb_postpush_rcsum(skb, lse, MPLS_HLEN);
6171
6172 if (ethernet && mac_len >= ETH_HLEN)
6173 skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
6174 skb->protocol = mpls_proto;
6175
6176 return 0;
6177 }
6178 EXPORT_SYMBOL_GPL(skb_mpls_push);
6179
6180 /**
6181 * skb_mpls_pop() - pop the outermost MPLS header
6182 *
6183 * @skb: buffer
6184 * @next_proto: ethertype of header after popped MPLS header
6185 * @mac_len: length of the MAC header
6186 * @ethernet: flag to indicate if the packet is ethernet
6187 *
6188 * Expects skb->data at mac header.
6189 *
6190 * Returns 0 on success, -errno otherwise.
6191 */
skb_mpls_pop(struct sk_buff * skb,__be16 next_proto,int mac_len,bool ethernet)6192 int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
6193 bool ethernet)
6194 {
6195 int err;
6196
6197 if (unlikely(!eth_p_mpls(skb->protocol)))
6198 return 0;
6199
6200 err = skb_ensure_writable(skb, mac_len + MPLS_HLEN);
6201 if (unlikely(err))
6202 return err;
6203
6204 skb_postpull_rcsum(skb, mpls_hdr(skb), MPLS_HLEN);
6205 memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
6206 mac_len);
6207
6208 __skb_pull(skb, MPLS_HLEN);
6209 skb_reset_mac_header(skb);
6210 skb_set_network_header(skb, mac_len);
6211
6212 if (ethernet && mac_len >= ETH_HLEN) {
6213 struct ethhdr *hdr;
6214
6215 /* use mpls_hdr() to get ethertype to account for VLANs. */
6216 hdr = (struct ethhdr *)((void *)mpls_hdr(skb) - ETH_HLEN);
6217 skb_mod_eth_type(skb, hdr, next_proto);
6218 }
6219 skb->protocol = next_proto;
6220
6221 return 0;
6222 }
6223 EXPORT_SYMBOL_GPL(skb_mpls_pop);
6224
6225 /**
6226 * skb_mpls_update_lse() - modify outermost MPLS header and update csum
6227 *
6228 * @skb: buffer
6229 * @mpls_lse: new MPLS label stack entry to update to
6230 *
6231 * Expects skb->data at mac header.
6232 *
6233 * Returns 0 on success, -errno otherwise.
6234 */
skb_mpls_update_lse(struct sk_buff * skb,__be32 mpls_lse)6235 int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse)
6236 {
6237 int err;
6238
6239 if (unlikely(!eth_p_mpls(skb->protocol)))
6240 return -EINVAL;
6241
6242 err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
6243 if (unlikely(err))
6244 return err;
6245
6246 if (skb->ip_summed == CHECKSUM_COMPLETE) {
6247 __be32 diff[] = { ~mpls_hdr(skb)->label_stack_entry, mpls_lse };
6248
6249 skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
6250 }
6251
6252 mpls_hdr(skb)->label_stack_entry = mpls_lse;
6253
6254 return 0;
6255 }
6256 EXPORT_SYMBOL_GPL(skb_mpls_update_lse);
6257
6258 /**
6259 * skb_mpls_dec_ttl() - decrement the TTL of the outermost MPLS header
6260 *
6261 * @skb: buffer
6262 *
6263 * Expects skb->data at mac header.
6264 *
6265 * Returns 0 on success, -errno otherwise.
6266 */
skb_mpls_dec_ttl(struct sk_buff * skb)6267 int skb_mpls_dec_ttl(struct sk_buff *skb)
6268 {
6269 u32 lse;
6270 u8 ttl;
6271
6272 if (unlikely(!eth_p_mpls(skb->protocol)))
6273 return -EINVAL;
6274
6275 if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN))
6276 return -ENOMEM;
6277
6278 lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry);
6279 ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
6280 if (!--ttl)
6281 return -EINVAL;
6282
6283 lse &= ~MPLS_LS_TTL_MASK;
6284 lse |= ttl << MPLS_LS_TTL_SHIFT;
6285
6286 return skb_mpls_update_lse(skb, cpu_to_be32(lse));
6287 }
6288 EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl);
6289
6290 /**
6291 * alloc_skb_with_frags - allocate skb with page frags
6292 *
6293 * @header_len: size of linear part
6294 * @data_len: needed length in frags
6295 * @order: max page order desired.
6296 * @errcode: pointer to error code if any
6297 * @gfp_mask: allocation mask
6298 *
6299 * This can be used to allocate a paged skb, given a maximal order for frags.
6300 */
alloc_skb_with_frags(unsigned long header_len,unsigned long data_len,int order,int * errcode,gfp_t gfp_mask)6301 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
6302 unsigned long data_len,
6303 int order,
6304 int *errcode,
6305 gfp_t gfp_mask)
6306 {
6307 unsigned long chunk;
6308 struct sk_buff *skb;
6309 struct page *page;
6310 int nr_frags = 0;
6311
6312 *errcode = -EMSGSIZE;
6313 if (unlikely(data_len > MAX_SKB_FRAGS * (PAGE_SIZE << order)))
6314 return NULL;
6315
6316 *errcode = -ENOBUFS;
6317 skb = alloc_skb(header_len, gfp_mask);
6318 if (!skb)
6319 return NULL;
6320
6321 while (data_len) {
6322 if (nr_frags == MAX_SKB_FRAGS - 1)
6323 goto failure;
6324 while (order && PAGE_ALIGN(data_len) < (PAGE_SIZE << order))
6325 order--;
6326
6327 if (order) {
6328 page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
6329 __GFP_COMP |
6330 __GFP_NOWARN,
6331 order);
6332 if (!page) {
6333 order--;
6334 continue;
6335 }
6336 } else {
6337 page = alloc_page(gfp_mask);
6338 if (!page)
6339 goto failure;
6340 }
6341 chunk = min_t(unsigned long, data_len,
6342 PAGE_SIZE << order);
6343 skb_fill_page_desc(skb, nr_frags, page, 0, chunk);
6344 nr_frags++;
6345 skb->truesize += (PAGE_SIZE << order);
6346 data_len -= chunk;
6347 }
6348 return skb;
6349
6350 failure:
6351 kfree_skb(skb);
6352 return NULL;
6353 }
6354 EXPORT_SYMBOL(alloc_skb_with_frags);
6355
6356 /* carve out the first off bytes from skb when off < headlen */
pskb_carve_inside_header(struct sk_buff * skb,const u32 off,const int headlen,gfp_t gfp_mask)6357 static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
6358 const int headlen, gfp_t gfp_mask)
6359 {
6360 int i;
6361 unsigned int size = skb_end_offset(skb);
6362 int new_hlen = headlen - off;
6363 u8 *data;
6364
6365 if (skb_pfmemalloc(skb))
6366 gfp_mask |= __GFP_MEMALLOC;
6367
6368 data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
6369 if (!data)
6370 return -ENOMEM;
6371 size = SKB_WITH_OVERHEAD(size);
6372
6373 /* Copy real data, and all frags */
6374 skb_copy_from_linear_data_offset(skb, off, data, new_hlen);
6375 skb->len -= off;
6376
6377 memcpy((struct skb_shared_info *)(data + size),
6378 skb_shinfo(skb),
6379 offsetof(struct skb_shared_info,
6380 frags[skb_shinfo(skb)->nr_frags]));
6381 if (skb_cloned(skb)) {
6382 /* drop the old head gracefully */
6383 if (skb_orphan_frags(skb, gfp_mask)) {
6384 skb_kfree_head(data, size);
6385 return -ENOMEM;
6386 }
6387 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
6388 skb_frag_ref(skb, i);
6389 if (skb_has_frag_list(skb))
6390 skb_clone_fraglist(skb);
6391 skb_release_data(skb, SKB_CONSUMED, false);
6392 } else {
6393 /* we can reuse existing recount- all we did was
6394 * relocate values
6395 */
6396 skb_free_head(skb, false);
6397 }
6398
6399 skb->head = data;
6400 skb->data = data;
6401 skb->head_frag = 0;
6402 skb_set_end_offset(skb, size);
6403 skb_set_tail_pointer(skb, skb_headlen(skb));
6404 skb_headers_offset_update(skb, 0);
6405 skb->cloned = 0;
6406 skb->hdr_len = 0;
6407 skb->nohdr = 0;
6408 atomic_set(&skb_shinfo(skb)->dataref, 1);
6409
6410 return 0;
6411 }
6412
6413 static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
6414
6415 /* carve out the first eat bytes from skb's frag_list. May recurse into
6416 * pskb_carve()
6417 */
pskb_carve_frag_list(struct sk_buff * skb,struct skb_shared_info * shinfo,int eat,gfp_t gfp_mask)6418 static int pskb_carve_frag_list(struct sk_buff *skb,
6419 struct skb_shared_info *shinfo, int eat,
6420 gfp_t gfp_mask)
6421 {
6422 struct sk_buff *list = shinfo->frag_list;
6423 struct sk_buff *clone = NULL;
6424 struct sk_buff *insp = NULL;
6425
6426 do {
6427 if (!list) {
6428 pr_err("Not enough bytes to eat. Want %d\n", eat);
6429 return -EFAULT;
6430 }
6431 if (list->len <= eat) {
6432 /* Eaten as whole. */
6433 eat -= list->len;
6434 list = list->next;
6435 insp = list;
6436 } else {
6437 /* Eaten partially. */
6438 if (skb_shared(list)) {
6439 clone = skb_clone(list, gfp_mask);
6440 if (!clone)
6441 return -ENOMEM;
6442 insp = list->next;
6443 list = clone;
6444 } else {
6445 /* This may be pulled without problems. */
6446 insp = list;
6447 }
6448 if (pskb_carve(list, eat, gfp_mask) < 0) {
6449 kfree_skb(clone);
6450 return -ENOMEM;
6451 }
6452 break;
6453 }
6454 } while (eat);
6455
6456 /* Free pulled out fragments. */
6457 while ((list = shinfo->frag_list) != insp) {
6458 shinfo->frag_list = list->next;
6459 consume_skb(list);
6460 }
6461 /* And insert new clone at head. */
6462 if (clone) {
6463 clone->next = list;
6464 shinfo->frag_list = clone;
6465 }
6466 return 0;
6467 }
6468
6469 /* carve off first len bytes from skb. Split line (off) is in the
6470 * non-linear part of skb
6471 */
pskb_carve_inside_nonlinear(struct sk_buff * skb,const u32 off,int pos,gfp_t gfp_mask)6472 static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
6473 int pos, gfp_t gfp_mask)
6474 {
6475 int i, k = 0;
6476 unsigned int size = skb_end_offset(skb);
6477 u8 *data;
6478 const int nfrags = skb_shinfo(skb)->nr_frags;
6479 struct skb_shared_info *shinfo;
6480
6481 if (skb_pfmemalloc(skb))
6482 gfp_mask |= __GFP_MEMALLOC;
6483
6484 data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
6485 if (!data)
6486 return -ENOMEM;
6487 size = SKB_WITH_OVERHEAD(size);
6488
6489 memcpy((struct skb_shared_info *)(data + size),
6490 skb_shinfo(skb), offsetof(struct skb_shared_info, frags[0]));
6491 if (skb_orphan_frags(skb, gfp_mask)) {
6492 skb_kfree_head(data, size);
6493 return -ENOMEM;
6494 }
6495 shinfo = (struct skb_shared_info *)(data + size);
6496 for (i = 0; i < nfrags; i++) {
6497 int fsize = skb_frag_size(&skb_shinfo(skb)->frags[i]);
6498
6499 if (pos + fsize > off) {
6500 shinfo->frags[k] = skb_shinfo(skb)->frags[i];
6501
6502 if (pos < off) {
6503 /* Split frag.
6504 * We have two variants in this case:
6505 * 1. Move all the frag to the second
6506 * part, if it is possible. F.e.
6507 * this approach is mandatory for TUX,
6508 * where splitting is expensive.
6509 * 2. Split is accurately. We make this.
6510 */
6511 skb_frag_off_add(&shinfo->frags[0], off - pos);
6512 skb_frag_size_sub(&shinfo->frags[0], off - pos);
6513 }
6514 skb_frag_ref(skb, i);
6515 k++;
6516 }
6517 pos += fsize;
6518 }
6519 shinfo->nr_frags = k;
6520 if (skb_has_frag_list(skb))
6521 skb_clone_fraglist(skb);
6522
6523 /* split line is in frag list */
6524 if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
6525 /* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
6526 if (skb_has_frag_list(skb))
6527 kfree_skb_list(skb_shinfo(skb)->frag_list);
6528 skb_kfree_head(data, size);
6529 return -ENOMEM;
6530 }
6531 skb_release_data(skb, SKB_CONSUMED, false);
6532
6533 skb->head = data;
6534 skb->head_frag = 0;
6535 skb->data = data;
6536 skb_set_end_offset(skb, size);
6537 skb_reset_tail_pointer(skb);
6538 skb_headers_offset_update(skb, 0);
6539 skb->cloned = 0;
6540 skb->hdr_len = 0;
6541 skb->nohdr = 0;
6542 skb->len -= off;
6543 skb->data_len = skb->len;
6544 atomic_set(&skb_shinfo(skb)->dataref, 1);
6545 return 0;
6546 }
6547
6548 /* remove len bytes from the beginning of the skb */
pskb_carve(struct sk_buff * skb,const u32 len,gfp_t gfp)6549 static int pskb_carve(struct sk_buff *skb, const u32 len, gfp_t gfp)
6550 {
6551 int headlen = skb_headlen(skb);
6552
6553 if (len < headlen)
6554 return pskb_carve_inside_header(skb, len, headlen, gfp);
6555 else
6556 return pskb_carve_inside_nonlinear(skb, len, headlen, gfp);
6557 }
6558
6559 /* Extract to_copy bytes starting at off from skb, and return this in
6560 * a new skb
6561 */
pskb_extract(struct sk_buff * skb,int off,int to_copy,gfp_t gfp)6562 struct sk_buff *pskb_extract(struct sk_buff *skb, int off,
6563 int to_copy, gfp_t gfp)
6564 {
6565 struct sk_buff *clone = skb_clone(skb, gfp);
6566
6567 if (!clone)
6568 return NULL;
6569
6570 if (pskb_carve(clone, off, gfp) < 0 ||
6571 pskb_trim(clone, to_copy)) {
6572 kfree_skb(clone);
6573 return NULL;
6574 }
6575 return clone;
6576 }
6577 EXPORT_SYMBOL(pskb_extract);
6578
6579 /**
6580 * skb_condense - try to get rid of fragments/frag_list if possible
6581 * @skb: buffer
6582 *
6583 * Can be used to save memory before skb is added to a busy queue.
6584 * If packet has bytes in frags and enough tail room in skb->head,
6585 * pull all of them, so that we can free the frags right now and adjust
6586 * truesize.
6587 * Notes:
6588 * We do not reallocate skb->head thus can not fail.
6589 * Caller must re-evaluate skb->truesize if needed.
6590 */
skb_condense(struct sk_buff * skb)6591 void skb_condense(struct sk_buff *skb)
6592 {
6593 if (skb->data_len) {
6594 if (skb->data_len > skb->end - skb->tail ||
6595 skb_cloned(skb))
6596 return;
6597
6598 /* Nice, we can free page frag(s) right now */
6599 __pskb_pull_tail(skb, skb->data_len);
6600 }
6601 /* At this point, skb->truesize might be over estimated,
6602 * because skb had a fragment, and fragments do not tell
6603 * their truesize.
6604 * When we pulled its content into skb->head, fragment
6605 * was freed, but __pskb_pull_tail() could not possibly
6606 * adjust skb->truesize, not knowing the frag truesize.
6607 */
6608 skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
6609 }
6610 EXPORT_SYMBOL(skb_condense);
6611
6612 #ifdef CONFIG_SKB_EXTENSIONS
skb_ext_get_ptr(struct skb_ext * ext,enum skb_ext_id id)6613 static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id)
6614 {
6615 return (void *)ext + (ext->offset[id] * SKB_EXT_ALIGN_VALUE);
6616 }
6617
6618 /**
6619 * __skb_ext_alloc - allocate a new skb extensions storage
6620 *
6621 * @flags: See kmalloc().
6622 *
6623 * Returns the newly allocated pointer. The pointer can later attached to a
6624 * skb via __skb_ext_set().
6625 * Note: caller must handle the skb_ext as an opaque data.
6626 */
__skb_ext_alloc(gfp_t flags)6627 struct skb_ext *__skb_ext_alloc(gfp_t flags)
6628 {
6629 struct skb_ext *new = kmem_cache_alloc(skbuff_ext_cache, flags);
6630
6631 if (new) {
6632 memset(new->offset, 0, sizeof(new->offset));
6633 refcount_set(&new->refcnt, 1);
6634 }
6635
6636 return new;
6637 }
6638
skb_ext_maybe_cow(struct skb_ext * old,unsigned int old_active)6639 static struct skb_ext *skb_ext_maybe_cow(struct skb_ext *old,
6640 unsigned int old_active)
6641 {
6642 struct skb_ext *new;
6643
6644 if (refcount_read(&old->refcnt) == 1)
6645 return old;
6646
6647 new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC);
6648 if (!new)
6649 return NULL;
6650
6651 memcpy(new, old, old->chunks * SKB_EXT_ALIGN_VALUE);
6652 refcount_set(&new->refcnt, 1);
6653
6654 #ifdef CONFIG_XFRM
6655 if (old_active & (1 << SKB_EXT_SEC_PATH)) {
6656 struct sec_path *sp = skb_ext_get_ptr(old, SKB_EXT_SEC_PATH);
6657 unsigned int i;
6658
6659 for (i = 0; i < sp->len; i++)
6660 xfrm_state_hold(sp->xvec[i]);
6661 }
6662 #endif
6663 __skb_ext_put(old);
6664 return new;
6665 }
6666
6667 /**
6668 * __skb_ext_set - attach the specified extension storage to this skb
6669 * @skb: buffer
6670 * @id: extension id
6671 * @ext: extension storage previously allocated via __skb_ext_alloc()
6672 *
6673 * Existing extensions, if any, are cleared.
6674 *
6675 * Returns the pointer to the extension.
6676 */
__skb_ext_set(struct sk_buff * skb,enum skb_ext_id id,struct skb_ext * ext)6677 void *__skb_ext_set(struct sk_buff *skb, enum skb_ext_id id,
6678 struct skb_ext *ext)
6679 {
6680 unsigned int newlen, newoff = SKB_EXT_CHUNKSIZEOF(*ext);
6681
6682 skb_ext_put(skb);
6683 newlen = newoff + skb_ext_type_len[id];
6684 ext->chunks = newlen;
6685 ext->offset[id] = newoff;
6686 skb->extensions = ext;
6687 skb->active_extensions = 1 << id;
6688 return skb_ext_get_ptr(ext, id);
6689 }
6690
6691 /**
6692 * skb_ext_add - allocate space for given extension, COW if needed
6693 * @skb: buffer
6694 * @id: extension to allocate space for
6695 *
6696 * Allocates enough space for the given extension.
6697 * If the extension is already present, a pointer to that extension
6698 * is returned.
6699 *
6700 * If the skb was cloned, COW applies and the returned memory can be
6701 * modified without changing the extension space of clones buffers.
6702 *
6703 * Returns pointer to the extension or NULL on allocation failure.
6704 */
skb_ext_add(struct sk_buff * skb,enum skb_ext_id id)6705 void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id)
6706 {
6707 struct skb_ext *new, *old = NULL;
6708 unsigned int newlen, newoff;
6709
6710 if (skb->active_extensions) {
6711 old = skb->extensions;
6712
6713 new = skb_ext_maybe_cow(old, skb->active_extensions);
6714 if (!new)
6715 return NULL;
6716
6717 if (__skb_ext_exist(new, id))
6718 goto set_active;
6719
6720 newoff = new->chunks;
6721 } else {
6722 newoff = SKB_EXT_CHUNKSIZEOF(*new);
6723
6724 new = __skb_ext_alloc(GFP_ATOMIC);
6725 if (!new)
6726 return NULL;
6727 }
6728
6729 newlen = newoff + skb_ext_type_len[id];
6730 new->chunks = newlen;
6731 new->offset[id] = newoff;
6732 set_active:
6733 skb->slow_gro = 1;
6734 skb->extensions = new;
6735 skb->active_extensions |= 1 << id;
6736 return skb_ext_get_ptr(new, id);
6737 }
6738 EXPORT_SYMBOL(skb_ext_add);
6739
6740 #ifdef CONFIG_XFRM
skb_ext_put_sp(struct sec_path * sp)6741 static void skb_ext_put_sp(struct sec_path *sp)
6742 {
6743 unsigned int i;
6744
6745 for (i = 0; i < sp->len; i++)
6746 xfrm_state_put(sp->xvec[i]);
6747 }
6748 #endif
6749
6750 #ifdef CONFIG_MCTP_FLOWS
skb_ext_put_mctp(struct mctp_flow * flow)6751 static void skb_ext_put_mctp(struct mctp_flow *flow)
6752 {
6753 if (flow->key)
6754 mctp_key_unref(flow->key);
6755 }
6756 #endif
6757
__skb_ext_del(struct sk_buff * skb,enum skb_ext_id id)6758 void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
6759 {
6760 struct skb_ext *ext = skb->extensions;
6761
6762 skb->active_extensions &= ~(1 << id);
6763 if (skb->active_extensions == 0) {
6764 skb->extensions = NULL;
6765 __skb_ext_put(ext);
6766 #ifdef CONFIG_XFRM
6767 } else if (id == SKB_EXT_SEC_PATH &&
6768 refcount_read(&ext->refcnt) == 1) {
6769 struct sec_path *sp = skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH);
6770
6771 skb_ext_put_sp(sp);
6772 sp->len = 0;
6773 #endif
6774 }
6775 }
6776 EXPORT_SYMBOL(__skb_ext_del);
6777
__skb_ext_put(struct skb_ext * ext)6778 void __skb_ext_put(struct skb_ext *ext)
6779 {
6780 /* If this is last clone, nothing can increment
6781 * it after check passes. Avoids one atomic op.
6782 */
6783 if (refcount_read(&ext->refcnt) == 1)
6784 goto free_now;
6785
6786 if (!refcount_dec_and_test(&ext->refcnt))
6787 return;
6788 free_now:
6789 #ifdef CONFIG_XFRM
6790 if (__skb_ext_exist(ext, SKB_EXT_SEC_PATH))
6791 skb_ext_put_sp(skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH));
6792 #endif
6793 #ifdef CONFIG_MCTP_FLOWS
6794 if (__skb_ext_exist(ext, SKB_EXT_MCTP))
6795 skb_ext_put_mctp(skb_ext_get_ptr(ext, SKB_EXT_MCTP));
6796 #endif
6797
6798 kmem_cache_free(skbuff_ext_cache, ext);
6799 }
6800 EXPORT_SYMBOL(__skb_ext_put);
6801 #endif /* CONFIG_SKB_EXTENSIONS */
6802
6803 /**
6804 * skb_attempt_defer_free - queue skb for remote freeing
6805 * @skb: buffer
6806 *
6807 * Put @skb in a per-cpu list, using the cpu which
6808 * allocated the skb/pages to reduce false sharing
6809 * and memory zone spinlock contention.
6810 */
skb_attempt_defer_free(struct sk_buff * skb)6811 void skb_attempt_defer_free(struct sk_buff *skb)
6812 {
6813 int cpu = skb->alloc_cpu;
6814 struct softnet_data *sd;
6815 unsigned int defer_max;
6816 bool kick;
6817
6818 if (WARN_ON_ONCE(cpu >= nr_cpu_ids) ||
6819 !cpu_online(cpu) ||
6820 cpu == raw_smp_processor_id()) {
6821 nodefer: __kfree_skb(skb);
6822 return;
6823 }
6824
6825 DEBUG_NET_WARN_ON_ONCE(skb_dst(skb));
6826 DEBUG_NET_WARN_ON_ONCE(skb->destructor);
6827
6828 sd = &per_cpu(softnet_data, cpu);
6829 defer_max = READ_ONCE(sysctl_skb_defer_max);
6830 if (READ_ONCE(sd->defer_count) >= defer_max)
6831 goto nodefer;
6832
6833 spin_lock_bh(&sd->defer_lock);
6834 /* Send an IPI every time queue reaches half capacity. */
6835 kick = sd->defer_count == (defer_max >> 1);
6836 /* Paired with the READ_ONCE() few lines above */
6837 WRITE_ONCE(sd->defer_count, sd->defer_count + 1);
6838
6839 skb->next = sd->defer_list;
6840 /* Paired with READ_ONCE() in skb_defer_free_flush() */
6841 WRITE_ONCE(sd->defer_list, skb);
6842 spin_unlock_bh(&sd->defer_lock);
6843
6844 /* Make sure to trigger NET_RX_SOFTIRQ on the remote CPU
6845 * if we are unlucky enough (this seems very unlikely).
6846 */
6847 if (unlikely(kick) && !cmpxchg(&sd->defer_ipi_scheduled, 0, 1))
6848 smp_call_function_single_async(cpu, &sd->defer_csd);
6849 }
6850
skb_splice_csum_page(struct sk_buff * skb,struct page * page,size_t offset,size_t len)6851 static void skb_splice_csum_page(struct sk_buff *skb, struct page *page,
6852 size_t offset, size_t len)
6853 {
6854 const char *kaddr;
6855 __wsum csum;
6856
6857 kaddr = kmap_local_page(page);
6858 csum = csum_partial(kaddr + offset, len, 0);
6859 kunmap_local(kaddr);
6860 skb->csum = csum_block_add(skb->csum, csum, skb->len);
6861 }
6862
6863 /**
6864 * skb_splice_from_iter - Splice (or copy) pages to skbuff
6865 * @skb: The buffer to add pages to
6866 * @iter: Iterator representing the pages to be added
6867 * @maxsize: Maximum amount of pages to be added
6868 * @gfp: Allocation flags
6869 *
6870 * This is a common helper function for supporting MSG_SPLICE_PAGES. It
6871 * extracts pages from an iterator and adds them to the socket buffer if
6872 * possible, copying them to fragments if not possible (such as if they're slab
6873 * pages).
6874 *
6875 * Returns the amount of data spliced/copied or -EMSGSIZE if there's
6876 * insufficient space in the buffer to transfer anything.
6877 */
skb_splice_from_iter(struct sk_buff * skb,struct iov_iter * iter,ssize_t maxsize,gfp_t gfp)6878 ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter,
6879 ssize_t maxsize, gfp_t gfp)
6880 {
6881 size_t frag_limit = READ_ONCE(sysctl_max_skb_frags);
6882 struct page *pages[8], **ppages = pages;
6883 ssize_t spliced = 0, ret = 0;
6884 unsigned int i;
6885
6886 while (iter->count > 0) {
6887 ssize_t space, nr, len;
6888 size_t off;
6889
6890 ret = -EMSGSIZE;
6891 space = frag_limit - skb_shinfo(skb)->nr_frags;
6892 if (space < 0)
6893 break;
6894
6895 /* We might be able to coalesce without increasing nr_frags */
6896 nr = clamp_t(size_t, space, 1, ARRAY_SIZE(pages));
6897
6898 len = iov_iter_extract_pages(iter, &ppages, maxsize, nr, 0, &off);
6899 if (len <= 0) {
6900 ret = len ?: -EIO;
6901 break;
6902 }
6903
6904 i = 0;
6905 do {
6906 struct page *page = pages[i++];
6907 size_t part = min_t(size_t, PAGE_SIZE - off, len);
6908
6909 ret = -EIO;
6910 if (WARN_ON_ONCE(!sendpage_ok(page)))
6911 goto out;
6912
6913 ret = skb_append_pagefrags(skb, page, off, part,
6914 frag_limit);
6915 if (ret < 0) {
6916 iov_iter_revert(iter, len);
6917 goto out;
6918 }
6919
6920 if (skb->ip_summed == CHECKSUM_NONE)
6921 skb_splice_csum_page(skb, page, off, part);
6922
6923 off = 0;
6924 spliced += part;
6925 maxsize -= part;
6926 len -= part;
6927 } while (len > 0);
6928
6929 if (maxsize <= 0)
6930 break;
6931 }
6932
6933 out:
6934 skb_len_add(skb, spliced);
6935 return spliced ?: ret;
6936 }
6937 EXPORT_SYMBOL(skb_splice_from_iter);
6938