1 /* 2 * Routines having to do with the 'struct sk_buff' memory handlers. 3 * 4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk> 5 * Florian La Roche <rzsfl@rz.uni-sb.de> 6 * 7 * Fixes: 8 * Alan Cox : Fixed the worst of the load 9 * balancer bugs. 10 * Dave Platt : Interrupt stacking fix. 11 * Richard Kooijman : Timestamp fixes. 12 * Alan Cox : Changed buffer format. 13 * Alan Cox : destructor hook for AF_UNIX etc. 14 * Linus Torvalds : Better skb_clone. 15 * Alan Cox : Added skb_copy. 16 * Alan Cox : Added all the changed routines Linus 17 * only put in the headers 18 * Ray VanTassle : Fixed --skb->lock in free 19 * Alan Cox : skb_copy copy arp field 20 * Andi Kleen : slabified it. 21 * Robert Olsson : Removed skb_head_pool 22 * 23 * NOTE: 24 * The __skb_ routines should be called with interrupts 25 * disabled, or you better be *real* sure that the operation is atomic 26 * with respect to whatever list is being frobbed (e.g. via lock_sock() 27 * or via disabling bottom half handlers, etc). 28 * 29 * This program is free software; you can redistribute it and/or 30 * modify it under the terms of the GNU General Public License 31 * as published by the Free Software Foundation; either version 32 * 2 of the License, or (at your option) any later version. 33 */ 34 35 /* 36 * The functions in this file will not compile correctly with gcc 2.4.x 37 */ 38 39 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 40 41 #include <linux/module.h> 42 #include <linux/types.h> 43 #include <linux/kernel.h> 44 #include <linux/kmemcheck.h> 45 #include <linux/mm.h> 46 #include <linux/interrupt.h> 47 #include <linux/in.h> 48 #include <linux/inet.h> 49 #include <linux/slab.h> 50 #include <linux/netdevice.h> 51 #ifdef CONFIG_NET_CLS_ACT 52 #include <net/pkt_sched.h> 53 #endif 54 #include <linux/string.h> 55 #include <linux/skbuff.h> 56 #include <linux/splice.h> 57 #include <linux/cache.h> 58 #include <linux/rtnetlink.h> 59 #include <linux/init.h> 60 #include <linux/scatterlist.h> 61 #include <linux/errqueue.h> 62 #include <linux/prefetch.h> 63 64 #include <net/protocol.h> 65 #include <net/dst.h> 66 #include <net/sock.h> 67 #include <net/checksum.h> 68 #include <net/xfrm.h> 69 70 #include <asm/uaccess.h> 71 #include <trace/events/skb.h> 72 #include <linux/highmem.h> 73 74 struct kmem_cache *skbuff_head_cache __read_mostly; 75 static struct kmem_cache *skbuff_fclone_cache __read_mostly; 76 77 static void sock_pipe_buf_release(struct pipe_inode_info *pipe, 78 struct pipe_buffer *buf) 79 { 80 put_page(buf->page); 81 } 82 83 static void sock_pipe_buf_get(struct pipe_inode_info *pipe, 84 struct pipe_buffer *buf) 85 { 86 get_page(buf->page); 87 } 88 89 static int sock_pipe_buf_steal(struct pipe_inode_info *pipe, 90 struct pipe_buffer *buf) 91 { 92 return 1; 93 } 94 95 96 /* Pipe buffer operations for a socket. */ 97 static const struct pipe_buf_operations sock_pipe_buf_ops = { 98 .can_merge = 0, 99 .map = generic_pipe_buf_map, 100 .unmap = generic_pipe_buf_unmap, 101 .confirm = generic_pipe_buf_confirm, 102 .release = sock_pipe_buf_release, 103 .steal = sock_pipe_buf_steal, 104 .get = sock_pipe_buf_get, 105 }; 106 107 /* 108 * Keep out-of-line to prevent kernel bloat. 109 * __builtin_return_address is not used because it is not always 110 * reliable. 111 */ 112 113 /** 114 * skb_over_panic - private function 115 * @skb: buffer 116 * @sz: size 117 * @here: address 118 * 119 * Out of line support code for skb_put(). Not user callable. 120 */ 121 static void skb_over_panic(struct sk_buff *skb, int sz, void *here) 122 { 123 pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n", 124 __func__, here, skb->len, sz, skb->head, skb->data, 125 (unsigned long)skb->tail, (unsigned long)skb->end, 126 skb->dev ? skb->dev->name : "<NULL>"); 127 BUG(); 128 } 129 130 /** 131 * skb_under_panic - private function 132 * @skb: buffer 133 * @sz: size 134 * @here: address 135 * 136 * Out of line support code for skb_push(). Not user callable. 137 */ 138 139 static void skb_under_panic(struct sk_buff *skb, int sz, void *here) 140 { 141 pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n", 142 __func__, here, skb->len, sz, skb->head, skb->data, 143 (unsigned long)skb->tail, (unsigned long)skb->end, 144 skb->dev ? skb->dev->name : "<NULL>"); 145 BUG(); 146 } 147 148 149 /* 150 * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells 151 * the caller if emergency pfmemalloc reserves are being used. If it is and 152 * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves 153 * may be used. Otherwise, the packet data may be discarded until enough 154 * memory is free 155 */ 156 #define kmalloc_reserve(size, gfp, node, pfmemalloc) \ 157 __kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc) 158 void *__kmalloc_reserve(size_t size, gfp_t flags, int node, unsigned long ip, 159 bool *pfmemalloc) 160 { 161 void *obj; 162 bool ret_pfmemalloc = false; 163 164 /* 165 * Try a regular allocation, when that fails and we're not entitled 166 * to the reserves, fail. 167 */ 168 obj = kmalloc_node_track_caller(size, 169 flags | __GFP_NOMEMALLOC | __GFP_NOWARN, 170 node); 171 if (obj || !(gfp_pfmemalloc_allowed(flags))) 172 goto out; 173 174 /* Try again but now we are using pfmemalloc reserves */ 175 ret_pfmemalloc = true; 176 obj = kmalloc_node_track_caller(size, flags, node); 177 178 out: 179 if (pfmemalloc) 180 *pfmemalloc = ret_pfmemalloc; 181 182 return obj; 183 } 184 185 /* Allocate a new skbuff. We do this ourselves so we can fill in a few 186 * 'private' fields and also do memory statistics to find all the 187 * [BEEP] leaks. 188 * 189 */ 190 191 /** 192 * __alloc_skb - allocate a network buffer 193 * @size: size to allocate 194 * @gfp_mask: allocation mask 195 * @flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache 196 * instead of head cache and allocate a cloned (child) skb. 197 * If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for 198 * allocations in case the data is required for writeback 199 * @node: numa node to allocate memory on 200 * 201 * Allocate a new &sk_buff. The returned buffer has no headroom and a 202 * tail room of at least size bytes. The object has a reference count 203 * of one. The return is the buffer. On a failure the return is %NULL. 204 * 205 * Buffers may only be allocated from interrupts using a @gfp_mask of 206 * %GFP_ATOMIC. 207 */ 208 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, 209 int flags, int node) 210 { 211 struct kmem_cache *cache; 212 struct skb_shared_info *shinfo; 213 struct sk_buff *skb; 214 u8 *data; 215 bool pfmemalloc; 216 217 cache = (flags & SKB_ALLOC_FCLONE) 218 ? skbuff_fclone_cache : skbuff_head_cache; 219 220 if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX)) 221 gfp_mask |= __GFP_MEMALLOC; 222 223 /* Get the HEAD */ 224 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node); 225 if (!skb) 226 goto out; 227 prefetchw(skb); 228 229 /* We do our best to align skb_shared_info on a separate cache 230 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives 231 * aligned memory blocks, unless SLUB/SLAB debug is enabled. 232 * Both skb->head and skb_shared_info are cache line aligned. 233 */ 234 size = SKB_DATA_ALIGN(size); 235 size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); 236 data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc); 237 if (!data) 238 goto nodata; 239 /* kmalloc(size) might give us more room than requested. 240 * Put skb_shared_info exactly at the end of allocated zone, 241 * to allow max possible filling before reallocation. 242 */ 243 size = SKB_WITH_OVERHEAD(ksize(data)); 244 prefetchw(data + size); 245 246 /* 247 * Only clear those fields we need to clear, not those that we will 248 * actually initialise below. Hence, don't put any more fields after 249 * the tail pointer in struct sk_buff! 250 */ 251 memset(skb, 0, offsetof(struct sk_buff, tail)); 252 /* Account for allocated memory : skb + skb->head */ 253 skb->truesize = SKB_TRUESIZE(size); 254 skb->pfmemalloc = pfmemalloc; 255 atomic_set(&skb->users, 1); 256 skb->head = data; 257 skb->data = data; 258 skb_reset_tail_pointer(skb); 259 skb->end = skb->tail + size; 260 #ifdef NET_SKBUFF_DATA_USES_OFFSET 261 skb->mac_header = ~0U; 262 #endif 263 264 /* make sure we initialize shinfo sequentially */ 265 shinfo = skb_shinfo(skb); 266 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref)); 267 atomic_set(&shinfo->dataref, 1); 268 kmemcheck_annotate_variable(shinfo->destructor_arg); 269 270 if (flags & SKB_ALLOC_FCLONE) { 271 struct sk_buff *child = skb + 1; 272 atomic_t *fclone_ref = (atomic_t *) (child + 1); 273 274 kmemcheck_annotate_bitfield(child, flags1); 275 kmemcheck_annotate_bitfield(child, flags2); 276 skb->fclone = SKB_FCLONE_ORIG; 277 atomic_set(fclone_ref, 1); 278 279 child->fclone = SKB_FCLONE_UNAVAILABLE; 280 child->pfmemalloc = pfmemalloc; 281 } 282 out: 283 return skb; 284 nodata: 285 kmem_cache_free(cache, skb); 286 skb = NULL; 287 goto out; 288 } 289 EXPORT_SYMBOL(__alloc_skb); 290 291 /** 292 * build_skb - build a network buffer 293 * @data: data buffer provided by caller 294 * @frag_size: size of fragment, or 0 if head was kmalloced 295 * 296 * Allocate a new &sk_buff. Caller provides space holding head and 297 * skb_shared_info. @data must have been allocated by kmalloc() 298 * The return is the new skb buffer. 299 * On a failure the return is %NULL, and @data is not freed. 300 * Notes : 301 * Before IO, driver allocates only data buffer where NIC put incoming frame 302 * Driver should add room at head (NET_SKB_PAD) and 303 * MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info)) 304 * After IO, driver calls build_skb(), to allocate sk_buff and populate it 305 * before giving packet to stack. 306 * RX rings only contains data buffers, not full skbs. 307 */ 308 struct sk_buff *build_skb(void *data, unsigned int frag_size) 309 { 310 struct skb_shared_info *shinfo; 311 struct sk_buff *skb; 312 unsigned int size = frag_size ? : ksize(data); 313 314 skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC); 315 if (!skb) 316 return NULL; 317 318 size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); 319 320 memset(skb, 0, offsetof(struct sk_buff, tail)); 321 skb->truesize = SKB_TRUESIZE(size); 322 skb->head_frag = frag_size != 0; 323 atomic_set(&skb->users, 1); 324 skb->head = data; 325 skb->data = data; 326 skb_reset_tail_pointer(skb); 327 skb->end = skb->tail + size; 328 #ifdef NET_SKBUFF_DATA_USES_OFFSET 329 skb->mac_header = ~0U; 330 #endif 331 332 /* make sure we initialize shinfo sequentially */ 333 shinfo = skb_shinfo(skb); 334 memset(shinfo, 0, offsetof(struct skb_shared_info, dataref)); 335 atomic_set(&shinfo->dataref, 1); 336 kmemcheck_annotate_variable(shinfo->destructor_arg); 337 338 return skb; 339 } 340 EXPORT_SYMBOL(build_skb); 341 342 struct netdev_alloc_cache { 343 struct page_frag frag; 344 /* we maintain a pagecount bias, so that we dont dirty cache line 345 * containing page->_count every time we allocate a fragment. 346 */ 347 unsigned int pagecnt_bias; 348 }; 349 static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache); 350 351 #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768) 352 #define NETDEV_FRAG_PAGE_MAX_SIZE (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER) 353 #define NETDEV_PAGECNT_MAX_BIAS NETDEV_FRAG_PAGE_MAX_SIZE 354 355 static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask) 356 { 357 struct netdev_alloc_cache *nc; 358 void *data = NULL; 359 int order; 360 unsigned long flags; 361 362 local_irq_save(flags); 363 nc = &__get_cpu_var(netdev_alloc_cache); 364 if (unlikely(!nc->frag.page)) { 365 refill: 366 for (order = NETDEV_FRAG_PAGE_MAX_ORDER; ;) { 367 gfp_t gfp = gfp_mask; 368 369 if (order) 370 gfp |= __GFP_COMP | __GFP_NOWARN; 371 nc->frag.page = alloc_pages(gfp, order); 372 if (likely(nc->frag.page)) 373 break; 374 if (--order < 0) 375 goto end; 376 } 377 nc->frag.size = PAGE_SIZE << order; 378 recycle: 379 atomic_set(&nc->frag.page->_count, NETDEV_PAGECNT_MAX_BIAS); 380 nc->pagecnt_bias = NETDEV_PAGECNT_MAX_BIAS; 381 nc->frag.offset = 0; 382 } 383 384 if (nc->frag.offset + fragsz > nc->frag.size) { 385 /* avoid unnecessary locked operations if possible */ 386 if ((atomic_read(&nc->frag.page->_count) == nc->pagecnt_bias) || 387 atomic_sub_and_test(nc->pagecnt_bias, &nc->frag.page->_count)) 388 goto recycle; 389 goto refill; 390 } 391 392 data = page_address(nc->frag.page) + nc->frag.offset; 393 nc->frag.offset += fragsz; 394 nc->pagecnt_bias--; 395 end: 396 local_irq_restore(flags); 397 return data; 398 } 399 400 /** 401 * netdev_alloc_frag - allocate a page fragment 402 * @fragsz: fragment size 403 * 404 * Allocates a frag from a page for receive buffer. 405 * Uses GFP_ATOMIC allocations. 406 */ 407 void *netdev_alloc_frag(unsigned int fragsz) 408 { 409 return __netdev_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD); 410 } 411 EXPORT_SYMBOL(netdev_alloc_frag); 412 413 /** 414 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device 415 * @dev: network device to receive on 416 * @length: length to allocate 417 * @gfp_mask: get_free_pages mask, passed to alloc_skb 418 * 419 * Allocate a new &sk_buff and assign it a usage count of one. The 420 * buffer has unspecified headroom built in. Users should allocate 421 * the headroom they think they need without accounting for the 422 * built in space. The built in space is used for optimisations. 423 * 424 * %NULL is returned if there is no free memory. 425 */ 426 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, 427 unsigned int length, gfp_t gfp_mask) 428 { 429 struct sk_buff *skb = NULL; 430 unsigned int fragsz = SKB_DATA_ALIGN(length + NET_SKB_PAD) + 431 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); 432 433 if (fragsz <= PAGE_SIZE && !(gfp_mask & (__GFP_WAIT | GFP_DMA))) { 434 void *data; 435 436 if (sk_memalloc_socks()) 437 gfp_mask |= __GFP_MEMALLOC; 438 439 data = __netdev_alloc_frag(fragsz, gfp_mask); 440 441 if (likely(data)) { 442 skb = build_skb(data, fragsz); 443 if (unlikely(!skb)) 444 put_page(virt_to_head_page(data)); 445 } 446 } else { 447 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 448 SKB_ALLOC_RX, NUMA_NO_NODE); 449 } 450 if (likely(skb)) { 451 skb_reserve(skb, NET_SKB_PAD); 452 skb->dev = dev; 453 } 454 return skb; 455 } 456 EXPORT_SYMBOL(__netdev_alloc_skb); 457 458 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off, 459 int size, unsigned int truesize) 460 { 461 skb_fill_page_desc(skb, i, page, off, size); 462 skb->len += size; 463 skb->data_len += size; 464 skb->truesize += truesize; 465 } 466 EXPORT_SYMBOL(skb_add_rx_frag); 467 468 static void skb_drop_list(struct sk_buff **listp) 469 { 470 struct sk_buff *list = *listp; 471 472 *listp = NULL; 473 474 do { 475 struct sk_buff *this = list; 476 list = list->next; 477 kfree_skb(this); 478 } while (list); 479 } 480 481 static inline void skb_drop_fraglist(struct sk_buff *skb) 482 { 483 skb_drop_list(&skb_shinfo(skb)->frag_list); 484 } 485 486 static void skb_clone_fraglist(struct sk_buff *skb) 487 { 488 struct sk_buff *list; 489 490 skb_walk_frags(skb, list) 491 skb_get(list); 492 } 493 494 static void skb_free_head(struct sk_buff *skb) 495 { 496 if (skb->head_frag) 497 put_page(virt_to_head_page(skb->head)); 498 else 499 kfree(skb->head); 500 } 501 502 static void skb_release_data(struct sk_buff *skb) 503 { 504 if (!skb->cloned || 505 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1, 506 &skb_shinfo(skb)->dataref)) { 507 if (skb_shinfo(skb)->nr_frags) { 508 int i; 509 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 510 skb_frag_unref(skb, i); 511 } 512 513 /* 514 * If skb buf is from userspace, we need to notify the caller 515 * the lower device DMA has done; 516 */ 517 if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) { 518 struct ubuf_info *uarg; 519 520 uarg = skb_shinfo(skb)->destructor_arg; 521 if (uarg->callback) 522 uarg->callback(uarg); 523 } 524 525 if (skb_has_frag_list(skb)) 526 skb_drop_fraglist(skb); 527 528 skb_free_head(skb); 529 } 530 } 531 532 /* 533 * Free an skbuff by memory without cleaning the state. 534 */ 535 static void kfree_skbmem(struct sk_buff *skb) 536 { 537 struct sk_buff *other; 538 atomic_t *fclone_ref; 539 540 switch (skb->fclone) { 541 case SKB_FCLONE_UNAVAILABLE: 542 kmem_cache_free(skbuff_head_cache, skb); 543 break; 544 545 case SKB_FCLONE_ORIG: 546 fclone_ref = (atomic_t *) (skb + 2); 547 if (atomic_dec_and_test(fclone_ref)) 548 kmem_cache_free(skbuff_fclone_cache, skb); 549 break; 550 551 case SKB_FCLONE_CLONE: 552 fclone_ref = (atomic_t *) (skb + 1); 553 other = skb - 1; 554 555 /* The clone portion is available for 556 * fast-cloning again. 557 */ 558 skb->fclone = SKB_FCLONE_UNAVAILABLE; 559 560 if (atomic_dec_and_test(fclone_ref)) 561 kmem_cache_free(skbuff_fclone_cache, other); 562 break; 563 } 564 } 565 566 static void skb_release_head_state(struct sk_buff *skb) 567 { 568 skb_dst_drop(skb); 569 #ifdef CONFIG_XFRM 570 secpath_put(skb->sp); 571 #endif 572 if (skb->destructor) { 573 WARN_ON(in_irq()); 574 skb->destructor(skb); 575 } 576 #if IS_ENABLED(CONFIG_NF_CONNTRACK) 577 nf_conntrack_put(skb->nfct); 578 #endif 579 #ifdef NET_SKBUFF_NF_DEFRAG_NEEDED 580 nf_conntrack_put_reasm(skb->nfct_reasm); 581 #endif 582 #ifdef CONFIG_BRIDGE_NETFILTER 583 nf_bridge_put(skb->nf_bridge); 584 #endif 585 /* XXX: IS this still necessary? - JHS */ 586 #ifdef CONFIG_NET_SCHED 587 skb->tc_index = 0; 588 #ifdef CONFIG_NET_CLS_ACT 589 skb->tc_verd = 0; 590 #endif 591 #endif 592 } 593 594 /* Free everything but the sk_buff shell. */ 595 static void skb_release_all(struct sk_buff *skb) 596 { 597 skb_release_head_state(skb); 598 skb_release_data(skb); 599 } 600 601 /** 602 * __kfree_skb - private function 603 * @skb: buffer 604 * 605 * Free an sk_buff. Release anything attached to the buffer. 606 * Clean the state. This is an internal helper function. Users should 607 * always call kfree_skb 608 */ 609 610 void __kfree_skb(struct sk_buff *skb) 611 { 612 skb_release_all(skb); 613 kfree_skbmem(skb); 614 } 615 EXPORT_SYMBOL(__kfree_skb); 616 617 /** 618 * kfree_skb - free an sk_buff 619 * @skb: buffer to free 620 * 621 * Drop a reference to the buffer and free it if the usage count has 622 * hit zero. 623 */ 624 void kfree_skb(struct sk_buff *skb) 625 { 626 if (unlikely(!skb)) 627 return; 628 if (likely(atomic_read(&skb->users) == 1)) 629 smp_rmb(); 630 else if (likely(!atomic_dec_and_test(&skb->users))) 631 return; 632 trace_kfree_skb(skb, __builtin_return_address(0)); 633 __kfree_skb(skb); 634 } 635 EXPORT_SYMBOL(kfree_skb); 636 637 /** 638 * consume_skb - free an skbuff 639 * @skb: buffer to free 640 * 641 * Drop a ref to the buffer and free it if the usage count has hit zero 642 * Functions identically to kfree_skb, but kfree_skb assumes that the frame 643 * is being dropped after a failure and notes that 644 */ 645 void consume_skb(struct sk_buff *skb) 646 { 647 if (unlikely(!skb)) 648 return; 649 if (likely(atomic_read(&skb->users) == 1)) 650 smp_rmb(); 651 else if (likely(!atomic_dec_and_test(&skb->users))) 652 return; 653 trace_consume_skb(skb); 654 __kfree_skb(skb); 655 } 656 EXPORT_SYMBOL(consume_skb); 657 658 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old) 659 { 660 new->tstamp = old->tstamp; 661 new->dev = old->dev; 662 new->transport_header = old->transport_header; 663 new->network_header = old->network_header; 664 new->mac_header = old->mac_header; 665 skb_dst_copy(new, old); 666 new->rxhash = old->rxhash; 667 new->ooo_okay = old->ooo_okay; 668 new->l4_rxhash = old->l4_rxhash; 669 new->no_fcs = old->no_fcs; 670 #ifdef CONFIG_XFRM 671 new->sp = secpath_get(old->sp); 672 #endif 673 memcpy(new->cb, old->cb, sizeof(old->cb)); 674 new->csum = old->csum; 675 new->local_df = old->local_df; 676 new->pkt_type = old->pkt_type; 677 new->ip_summed = old->ip_summed; 678 skb_copy_queue_mapping(new, old); 679 new->priority = old->priority; 680 #if IS_ENABLED(CONFIG_IP_VS) 681 new->ipvs_property = old->ipvs_property; 682 #endif 683 new->pfmemalloc = old->pfmemalloc; 684 new->protocol = old->protocol; 685 new->mark = old->mark; 686 new->skb_iif = old->skb_iif; 687 __nf_copy(new, old); 688 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) 689 new->nf_trace = old->nf_trace; 690 #endif 691 #ifdef CONFIG_NET_SCHED 692 new->tc_index = old->tc_index; 693 #ifdef CONFIG_NET_CLS_ACT 694 new->tc_verd = old->tc_verd; 695 #endif 696 #endif 697 new->vlan_tci = old->vlan_tci; 698 699 skb_copy_secmark(new, old); 700 } 701 702 /* 703 * You should not add any new code to this function. Add it to 704 * __copy_skb_header above instead. 705 */ 706 static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb) 707 { 708 #define C(x) n->x = skb->x 709 710 n->next = n->prev = NULL; 711 n->sk = NULL; 712 __copy_skb_header(n, skb); 713 714 C(len); 715 C(data_len); 716 C(mac_len); 717 n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len; 718 n->cloned = 1; 719 n->nohdr = 0; 720 n->destructor = NULL; 721 C(tail); 722 C(end); 723 C(head); 724 C(head_frag); 725 C(data); 726 C(truesize); 727 atomic_set(&n->users, 1); 728 729 atomic_inc(&(skb_shinfo(skb)->dataref)); 730 skb->cloned = 1; 731 732 return n; 733 #undef C 734 } 735 736 /** 737 * skb_morph - morph one skb into another 738 * @dst: the skb to receive the contents 739 * @src: the skb to supply the contents 740 * 741 * This is identical to skb_clone except that the target skb is 742 * supplied by the user. 743 * 744 * The target skb is returned upon exit. 745 */ 746 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src) 747 { 748 skb_release_all(dst); 749 return __skb_clone(dst, src); 750 } 751 EXPORT_SYMBOL_GPL(skb_morph); 752 753 /** 754 * skb_copy_ubufs - copy userspace skb frags buffers to kernel 755 * @skb: the skb to modify 756 * @gfp_mask: allocation priority 757 * 758 * This must be called on SKBTX_DEV_ZEROCOPY skb. 759 * It will copy all frags into kernel and drop the reference 760 * to userspace pages. 761 * 762 * If this function is called from an interrupt gfp_mask() must be 763 * %GFP_ATOMIC. 764 * 765 * Returns 0 on success or a negative error code on failure 766 * to allocate kernel memory to copy to. 767 */ 768 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask) 769 { 770 int i; 771 int num_frags = skb_shinfo(skb)->nr_frags; 772 struct page *page, *head = NULL; 773 struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg; 774 775 for (i = 0; i < num_frags; i++) { 776 u8 *vaddr; 777 skb_frag_t *f = &skb_shinfo(skb)->frags[i]; 778 779 page = alloc_page(gfp_mask); 780 if (!page) { 781 while (head) { 782 struct page *next = (struct page *)head->private; 783 put_page(head); 784 head = next; 785 } 786 return -ENOMEM; 787 } 788 vaddr = kmap_atomic(skb_frag_page(f)); 789 memcpy(page_address(page), 790 vaddr + f->page_offset, skb_frag_size(f)); 791 kunmap_atomic(vaddr); 792 page->private = (unsigned long)head; 793 head = page; 794 } 795 796 /* skb frags release userspace buffers */ 797 for (i = 0; i < num_frags; i++) 798 skb_frag_unref(skb, i); 799 800 uarg->callback(uarg); 801 802 /* skb frags point to kernel buffers */ 803 for (i = num_frags - 1; i >= 0; i--) { 804 __skb_fill_page_desc(skb, i, head, 0, 805 skb_shinfo(skb)->frags[i].size); 806 head = (struct page *)head->private; 807 } 808 809 skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY; 810 return 0; 811 } 812 EXPORT_SYMBOL_GPL(skb_copy_ubufs); 813 814 /** 815 * skb_clone - duplicate an sk_buff 816 * @skb: buffer to clone 817 * @gfp_mask: allocation priority 818 * 819 * Duplicate an &sk_buff. The new one is not owned by a socket. Both 820 * copies share the same packet data but not structure. The new 821 * buffer has a reference count of 1. If the allocation fails the 822 * function returns %NULL otherwise the new buffer is returned. 823 * 824 * If this function is called from an interrupt gfp_mask() must be 825 * %GFP_ATOMIC. 826 */ 827 828 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 829 { 830 struct sk_buff *n; 831 832 if (skb_orphan_frags(skb, gfp_mask)) 833 return NULL; 834 835 n = skb + 1; 836 if (skb->fclone == SKB_FCLONE_ORIG && 837 n->fclone == SKB_FCLONE_UNAVAILABLE) { 838 atomic_t *fclone_ref = (atomic_t *) (n + 1); 839 n->fclone = SKB_FCLONE_CLONE; 840 atomic_inc(fclone_ref); 841 } else { 842 if (skb_pfmemalloc(skb)) 843 gfp_mask |= __GFP_MEMALLOC; 844 845 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask); 846 if (!n) 847 return NULL; 848 849 kmemcheck_annotate_bitfield(n, flags1); 850 kmemcheck_annotate_bitfield(n, flags2); 851 n->fclone = SKB_FCLONE_UNAVAILABLE; 852 } 853 854 return __skb_clone(n, skb); 855 } 856 EXPORT_SYMBOL(skb_clone); 857 858 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old) 859 { 860 #ifndef NET_SKBUFF_DATA_USES_OFFSET 861 /* 862 * Shift between the two data areas in bytes 863 */ 864 unsigned long offset = new->data - old->data; 865 #endif 866 867 __copy_skb_header(new, old); 868 869 #ifndef NET_SKBUFF_DATA_USES_OFFSET 870 /* {transport,network,mac}_header are relative to skb->head */ 871 new->transport_header += offset; 872 new->network_header += offset; 873 if (skb_mac_header_was_set(new)) 874 new->mac_header += offset; 875 #endif 876 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size; 877 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs; 878 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type; 879 } 880 881 static inline int skb_alloc_rx_flag(const struct sk_buff *skb) 882 { 883 if (skb_pfmemalloc(skb)) 884 return SKB_ALLOC_RX; 885 return 0; 886 } 887 888 /** 889 * skb_copy - create private copy of an sk_buff 890 * @skb: buffer to copy 891 * @gfp_mask: allocation priority 892 * 893 * Make a copy of both an &sk_buff and its data. This is used when the 894 * caller wishes to modify the data and needs a private copy of the 895 * data to alter. Returns %NULL on failure or the pointer to the buffer 896 * on success. The returned buffer has a reference count of 1. 897 * 898 * As by-product this function converts non-linear &sk_buff to linear 899 * one, so that &sk_buff becomes completely private and caller is allowed 900 * to modify all the data of returned buffer. This means that this 901 * function is not recommended for use in circumstances when only 902 * header is going to be modified. Use pskb_copy() instead. 903 */ 904 905 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask) 906 { 907 int headerlen = skb_headroom(skb); 908 unsigned int size = skb_end_offset(skb) + skb->data_len; 909 struct sk_buff *n = __alloc_skb(size, gfp_mask, 910 skb_alloc_rx_flag(skb), NUMA_NO_NODE); 911 912 if (!n) 913 return NULL; 914 915 /* Set the data pointer */ 916 skb_reserve(n, headerlen); 917 /* Set the tail pointer and length */ 918 skb_put(n, skb->len); 919 920 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len)) 921 BUG(); 922 923 copy_skb_header(n, skb); 924 return n; 925 } 926 EXPORT_SYMBOL(skb_copy); 927 928 /** 929 * __pskb_copy - create copy of an sk_buff with private head. 930 * @skb: buffer to copy 931 * @headroom: headroom of new skb 932 * @gfp_mask: allocation priority 933 * 934 * Make a copy of both an &sk_buff and part of its data, located 935 * in header. Fragmented data remain shared. This is used when 936 * the caller wishes to modify only header of &sk_buff and needs 937 * private copy of the header to alter. Returns %NULL on failure 938 * or the pointer to the buffer on success. 939 * The returned buffer has a reference count of 1. 940 */ 941 942 struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom, gfp_t gfp_mask) 943 { 944 unsigned int size = skb_headlen(skb) + headroom; 945 struct sk_buff *n = __alloc_skb(size, gfp_mask, 946 skb_alloc_rx_flag(skb), NUMA_NO_NODE); 947 948 if (!n) 949 goto out; 950 951 /* Set the data pointer */ 952 skb_reserve(n, headroom); 953 /* Set the tail pointer and length */ 954 skb_put(n, skb_headlen(skb)); 955 /* Copy the bytes */ 956 skb_copy_from_linear_data(skb, n->data, n->len); 957 958 n->truesize += skb->data_len; 959 n->data_len = skb->data_len; 960 n->len = skb->len; 961 962 if (skb_shinfo(skb)->nr_frags) { 963 int i; 964 965 if (skb_orphan_frags(skb, gfp_mask)) { 966 kfree_skb(n); 967 n = NULL; 968 goto out; 969 } 970 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 971 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i]; 972 skb_frag_ref(skb, i); 973 } 974 skb_shinfo(n)->nr_frags = i; 975 } 976 977 if (skb_has_frag_list(skb)) { 978 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list; 979 skb_clone_fraglist(n); 980 } 981 982 copy_skb_header(n, skb); 983 out: 984 return n; 985 } 986 EXPORT_SYMBOL(__pskb_copy); 987 988 /** 989 * pskb_expand_head - reallocate header of &sk_buff 990 * @skb: buffer to reallocate 991 * @nhead: room to add at head 992 * @ntail: room to add at tail 993 * @gfp_mask: allocation priority 994 * 995 * Expands (or creates identical copy, if &nhead and &ntail are zero) 996 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have 997 * reference count of 1. Returns zero in the case of success or error, 998 * if expansion failed. In the last case, &sk_buff is not changed. 999 * 1000 * All the pointers pointing into skb header may change and must be 1001 * reloaded after call to this function. 1002 */ 1003 1004 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, 1005 gfp_t gfp_mask) 1006 { 1007 int i; 1008 u8 *data; 1009 int size = nhead + skb_end_offset(skb) + ntail; 1010 long off; 1011 1012 BUG_ON(nhead < 0); 1013 1014 if (skb_shared(skb)) 1015 BUG(); 1016 1017 size = SKB_DATA_ALIGN(size); 1018 1019 if (skb_pfmemalloc(skb)) 1020 gfp_mask |= __GFP_MEMALLOC; 1021 data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)), 1022 gfp_mask, NUMA_NO_NODE, NULL); 1023 if (!data) 1024 goto nodata; 1025 size = SKB_WITH_OVERHEAD(ksize(data)); 1026 1027 /* Copy only real data... and, alas, header. This should be 1028 * optimized for the cases when header is void. 1029 */ 1030 memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head); 1031 1032 memcpy((struct skb_shared_info *)(data + size), 1033 skb_shinfo(skb), 1034 offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags])); 1035 1036 /* 1037 * if shinfo is shared we must drop the old head gracefully, but if it 1038 * is not we can just drop the old head and let the existing refcount 1039 * be since all we did is relocate the values 1040 */ 1041 if (skb_cloned(skb)) { 1042 /* copy this zero copy skb frags */ 1043 if (skb_orphan_frags(skb, gfp_mask)) 1044 goto nofrags; 1045 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 1046 skb_frag_ref(skb, i); 1047 1048 if (skb_has_frag_list(skb)) 1049 skb_clone_fraglist(skb); 1050 1051 skb_release_data(skb); 1052 } else { 1053 skb_free_head(skb); 1054 } 1055 off = (data + nhead) - skb->head; 1056 1057 skb->head = data; 1058 skb->head_frag = 0; 1059 skb->data += off; 1060 #ifdef NET_SKBUFF_DATA_USES_OFFSET 1061 skb->end = size; 1062 off = nhead; 1063 #else 1064 skb->end = skb->head + size; 1065 #endif 1066 /* {transport,network,mac}_header and tail are relative to skb->head */ 1067 skb->tail += off; 1068 skb->transport_header += off; 1069 skb->network_header += off; 1070 if (skb_mac_header_was_set(skb)) 1071 skb->mac_header += off; 1072 /* Only adjust this if it actually is csum_start rather than csum */ 1073 if (skb->ip_summed == CHECKSUM_PARTIAL) 1074 skb->csum_start += nhead; 1075 skb->cloned = 0; 1076 skb->hdr_len = 0; 1077 skb->nohdr = 0; 1078 atomic_set(&skb_shinfo(skb)->dataref, 1); 1079 return 0; 1080 1081 nofrags: 1082 kfree(data); 1083 nodata: 1084 return -ENOMEM; 1085 } 1086 EXPORT_SYMBOL(pskb_expand_head); 1087 1088 /* Make private copy of skb with writable head and some headroom */ 1089 1090 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom) 1091 { 1092 struct sk_buff *skb2; 1093 int delta = headroom - skb_headroom(skb); 1094 1095 if (delta <= 0) 1096 skb2 = pskb_copy(skb, GFP_ATOMIC); 1097 else { 1098 skb2 = skb_clone(skb, GFP_ATOMIC); 1099 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0, 1100 GFP_ATOMIC)) { 1101 kfree_skb(skb2); 1102 skb2 = NULL; 1103 } 1104 } 1105 return skb2; 1106 } 1107 EXPORT_SYMBOL(skb_realloc_headroom); 1108 1109 /** 1110 * skb_copy_expand - copy and expand sk_buff 1111 * @skb: buffer to copy 1112 * @newheadroom: new free bytes at head 1113 * @newtailroom: new free bytes at tail 1114 * @gfp_mask: allocation priority 1115 * 1116 * Make a copy of both an &sk_buff and its data and while doing so 1117 * allocate additional space. 1118 * 1119 * This is used when the caller wishes to modify the data and needs a 1120 * private copy of the data to alter as well as more space for new fields. 1121 * Returns %NULL on failure or the pointer to the buffer 1122 * on success. The returned buffer has a reference count of 1. 1123 * 1124 * You must pass %GFP_ATOMIC as the allocation priority if this function 1125 * is called from an interrupt. 1126 */ 1127 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, 1128 int newheadroom, int newtailroom, 1129 gfp_t gfp_mask) 1130 { 1131 /* 1132 * Allocate the copy buffer 1133 */ 1134 struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom, 1135 gfp_mask, skb_alloc_rx_flag(skb), 1136 NUMA_NO_NODE); 1137 int oldheadroom = skb_headroom(skb); 1138 int head_copy_len, head_copy_off; 1139 int off; 1140 1141 if (!n) 1142 return NULL; 1143 1144 skb_reserve(n, newheadroom); 1145 1146 /* Set the tail pointer and length */ 1147 skb_put(n, skb->len); 1148 1149 head_copy_len = oldheadroom; 1150 head_copy_off = 0; 1151 if (newheadroom <= head_copy_len) 1152 head_copy_len = newheadroom; 1153 else 1154 head_copy_off = newheadroom - head_copy_len; 1155 1156 /* Copy the linear header and data. */ 1157 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off, 1158 skb->len + head_copy_len)) 1159 BUG(); 1160 1161 copy_skb_header(n, skb); 1162 1163 off = newheadroom - oldheadroom; 1164 if (n->ip_summed == CHECKSUM_PARTIAL) 1165 n->csum_start += off; 1166 #ifdef NET_SKBUFF_DATA_USES_OFFSET 1167 n->transport_header += off; 1168 n->network_header += off; 1169 if (skb_mac_header_was_set(skb)) 1170 n->mac_header += off; 1171 #endif 1172 1173 return n; 1174 } 1175 EXPORT_SYMBOL(skb_copy_expand); 1176 1177 /** 1178 * skb_pad - zero pad the tail of an skb 1179 * @skb: buffer to pad 1180 * @pad: space to pad 1181 * 1182 * Ensure that a buffer is followed by a padding area that is zero 1183 * filled. Used by network drivers which may DMA or transfer data 1184 * beyond the buffer end onto the wire. 1185 * 1186 * May return error in out of memory cases. The skb is freed on error. 1187 */ 1188 1189 int skb_pad(struct sk_buff *skb, int pad) 1190 { 1191 int err; 1192 int ntail; 1193 1194 /* If the skbuff is non linear tailroom is always zero.. */ 1195 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) { 1196 memset(skb->data+skb->len, 0, pad); 1197 return 0; 1198 } 1199 1200 ntail = skb->data_len + pad - (skb->end - skb->tail); 1201 if (likely(skb_cloned(skb) || ntail > 0)) { 1202 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC); 1203 if (unlikely(err)) 1204 goto free_skb; 1205 } 1206 1207 /* FIXME: The use of this function with non-linear skb's really needs 1208 * to be audited. 1209 */ 1210 err = skb_linearize(skb); 1211 if (unlikely(err)) 1212 goto free_skb; 1213 1214 memset(skb->data + skb->len, 0, pad); 1215 return 0; 1216 1217 free_skb: 1218 kfree_skb(skb); 1219 return err; 1220 } 1221 EXPORT_SYMBOL(skb_pad); 1222 1223 /** 1224 * skb_put - add data to a buffer 1225 * @skb: buffer to use 1226 * @len: amount of data to add 1227 * 1228 * This function extends the used data area of the buffer. If this would 1229 * exceed the total buffer size the kernel will panic. A pointer to the 1230 * first byte of the extra data is returned. 1231 */ 1232 unsigned char *skb_put(struct sk_buff *skb, unsigned int len) 1233 { 1234 unsigned char *tmp = skb_tail_pointer(skb); 1235 SKB_LINEAR_ASSERT(skb); 1236 skb->tail += len; 1237 skb->len += len; 1238 if (unlikely(skb->tail > skb->end)) 1239 skb_over_panic(skb, len, __builtin_return_address(0)); 1240 return tmp; 1241 } 1242 EXPORT_SYMBOL(skb_put); 1243 1244 /** 1245 * skb_push - add data to the start of a buffer 1246 * @skb: buffer to use 1247 * @len: amount of data to add 1248 * 1249 * This function extends the used data area of the buffer at the buffer 1250 * start. If this would exceed the total buffer headroom the kernel will 1251 * panic. A pointer to the first byte of the extra data is returned. 1252 */ 1253 unsigned char *skb_push(struct sk_buff *skb, unsigned int len) 1254 { 1255 skb->data -= len; 1256 skb->len += len; 1257 if (unlikely(skb->data<skb->head)) 1258 skb_under_panic(skb, len, __builtin_return_address(0)); 1259 return skb->data; 1260 } 1261 EXPORT_SYMBOL(skb_push); 1262 1263 /** 1264 * skb_pull - remove data from the start of a buffer 1265 * @skb: buffer to use 1266 * @len: amount of data to remove 1267 * 1268 * This function removes data from the start of a buffer, returning 1269 * the memory to the headroom. A pointer to the next data in the buffer 1270 * is returned. Once the data has been pulled future pushes will overwrite 1271 * the old data. 1272 */ 1273 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len) 1274 { 1275 return skb_pull_inline(skb, len); 1276 } 1277 EXPORT_SYMBOL(skb_pull); 1278 1279 /** 1280 * skb_trim - remove end from a buffer 1281 * @skb: buffer to alter 1282 * @len: new length 1283 * 1284 * Cut the length of a buffer down by removing data from the tail. If 1285 * the buffer is already under the length specified it is not modified. 1286 * The skb must be linear. 1287 */ 1288 void skb_trim(struct sk_buff *skb, unsigned int len) 1289 { 1290 if (skb->len > len) 1291 __skb_trim(skb, len); 1292 } 1293 EXPORT_SYMBOL(skb_trim); 1294 1295 /* Trims skb to length len. It can change skb pointers. 1296 */ 1297 1298 int ___pskb_trim(struct sk_buff *skb, unsigned int len) 1299 { 1300 struct sk_buff **fragp; 1301 struct sk_buff *frag; 1302 int offset = skb_headlen(skb); 1303 int nfrags = skb_shinfo(skb)->nr_frags; 1304 int i; 1305 int err; 1306 1307 if (skb_cloned(skb) && 1308 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))) 1309 return err; 1310 1311 i = 0; 1312 if (offset >= len) 1313 goto drop_pages; 1314 1315 for (; i < nfrags; i++) { 1316 int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]); 1317 1318 if (end < len) { 1319 offset = end; 1320 continue; 1321 } 1322 1323 skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset); 1324 1325 drop_pages: 1326 skb_shinfo(skb)->nr_frags = i; 1327 1328 for (; i < nfrags; i++) 1329 skb_frag_unref(skb, i); 1330 1331 if (skb_has_frag_list(skb)) 1332 skb_drop_fraglist(skb); 1333 goto done; 1334 } 1335 1336 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp); 1337 fragp = &frag->next) { 1338 int end = offset + frag->len; 1339 1340 if (skb_shared(frag)) { 1341 struct sk_buff *nfrag; 1342 1343 nfrag = skb_clone(frag, GFP_ATOMIC); 1344 if (unlikely(!nfrag)) 1345 return -ENOMEM; 1346 1347 nfrag->next = frag->next; 1348 consume_skb(frag); 1349 frag = nfrag; 1350 *fragp = frag; 1351 } 1352 1353 if (end < len) { 1354 offset = end; 1355 continue; 1356 } 1357 1358 if (end > len && 1359 unlikely((err = pskb_trim(frag, len - offset)))) 1360 return err; 1361 1362 if (frag->next) 1363 skb_drop_list(&frag->next); 1364 break; 1365 } 1366 1367 done: 1368 if (len > skb_headlen(skb)) { 1369 skb->data_len -= skb->len - len; 1370 skb->len = len; 1371 } else { 1372 skb->len = len; 1373 skb->data_len = 0; 1374 skb_set_tail_pointer(skb, len); 1375 } 1376 1377 return 0; 1378 } 1379 EXPORT_SYMBOL(___pskb_trim); 1380 1381 /** 1382 * __pskb_pull_tail - advance tail of skb header 1383 * @skb: buffer to reallocate 1384 * @delta: number of bytes to advance tail 1385 * 1386 * The function makes a sense only on a fragmented &sk_buff, 1387 * it expands header moving its tail forward and copying necessary 1388 * data from fragmented part. 1389 * 1390 * &sk_buff MUST have reference count of 1. 1391 * 1392 * Returns %NULL (and &sk_buff does not change) if pull failed 1393 * or value of new tail of skb in the case of success. 1394 * 1395 * All the pointers pointing into skb header may change and must be 1396 * reloaded after call to this function. 1397 */ 1398 1399 /* Moves tail of skb head forward, copying data from fragmented part, 1400 * when it is necessary. 1401 * 1. It may fail due to malloc failure. 1402 * 2. It may change skb pointers. 1403 * 1404 * It is pretty complicated. Luckily, it is called only in exceptional cases. 1405 */ 1406 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta) 1407 { 1408 /* If skb has not enough free space at tail, get new one 1409 * plus 128 bytes for future expansions. If we have enough 1410 * room at tail, reallocate without expansion only if skb is cloned. 1411 */ 1412 int i, k, eat = (skb->tail + delta) - skb->end; 1413 1414 if (eat > 0 || skb_cloned(skb)) { 1415 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0, 1416 GFP_ATOMIC)) 1417 return NULL; 1418 } 1419 1420 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta)) 1421 BUG(); 1422 1423 /* Optimization: no fragments, no reasons to preestimate 1424 * size of pulled pages. Superb. 1425 */ 1426 if (!skb_has_frag_list(skb)) 1427 goto pull_pages; 1428 1429 /* Estimate size of pulled pages. */ 1430 eat = delta; 1431 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1432 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]); 1433 1434 if (size >= eat) 1435 goto pull_pages; 1436 eat -= size; 1437 } 1438 1439 /* If we need update frag list, we are in troubles. 1440 * Certainly, it possible to add an offset to skb data, 1441 * but taking into account that pulling is expected to 1442 * be very rare operation, it is worth to fight against 1443 * further bloating skb head and crucify ourselves here instead. 1444 * Pure masohism, indeed. 8)8) 1445 */ 1446 if (eat) { 1447 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1448 struct sk_buff *clone = NULL; 1449 struct sk_buff *insp = NULL; 1450 1451 do { 1452 BUG_ON(!list); 1453 1454 if (list->len <= eat) { 1455 /* Eaten as whole. */ 1456 eat -= list->len; 1457 list = list->next; 1458 insp = list; 1459 } else { 1460 /* Eaten partially. */ 1461 1462 if (skb_shared(list)) { 1463 /* Sucks! We need to fork list. :-( */ 1464 clone = skb_clone(list, GFP_ATOMIC); 1465 if (!clone) 1466 return NULL; 1467 insp = list->next; 1468 list = clone; 1469 } else { 1470 /* This may be pulled without 1471 * problems. */ 1472 insp = list; 1473 } 1474 if (!pskb_pull(list, eat)) { 1475 kfree_skb(clone); 1476 return NULL; 1477 } 1478 break; 1479 } 1480 } while (eat); 1481 1482 /* Free pulled out fragments. */ 1483 while ((list = skb_shinfo(skb)->frag_list) != insp) { 1484 skb_shinfo(skb)->frag_list = list->next; 1485 kfree_skb(list); 1486 } 1487 /* And insert new clone at head. */ 1488 if (clone) { 1489 clone->next = list; 1490 skb_shinfo(skb)->frag_list = clone; 1491 } 1492 } 1493 /* Success! Now we may commit changes to skb data. */ 1494 1495 pull_pages: 1496 eat = delta; 1497 k = 0; 1498 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1499 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]); 1500 1501 if (size <= eat) { 1502 skb_frag_unref(skb, i); 1503 eat -= size; 1504 } else { 1505 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; 1506 if (eat) { 1507 skb_shinfo(skb)->frags[k].page_offset += eat; 1508 skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat); 1509 eat = 0; 1510 } 1511 k++; 1512 } 1513 } 1514 skb_shinfo(skb)->nr_frags = k; 1515 1516 skb->tail += delta; 1517 skb->data_len -= delta; 1518 1519 return skb_tail_pointer(skb); 1520 } 1521 EXPORT_SYMBOL(__pskb_pull_tail); 1522 1523 /** 1524 * skb_copy_bits - copy bits from skb to kernel buffer 1525 * @skb: source skb 1526 * @offset: offset in source 1527 * @to: destination buffer 1528 * @len: number of bytes to copy 1529 * 1530 * Copy the specified number of bytes from the source skb to the 1531 * destination buffer. 1532 * 1533 * CAUTION ! : 1534 * If its prototype is ever changed, 1535 * check arch/{*}/net/{*}.S files, 1536 * since it is called from BPF assembly code. 1537 */ 1538 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) 1539 { 1540 int start = skb_headlen(skb); 1541 struct sk_buff *frag_iter; 1542 int i, copy; 1543 1544 if (offset > (int)skb->len - len) 1545 goto fault; 1546 1547 /* Copy header. */ 1548 if ((copy = start - offset) > 0) { 1549 if (copy > len) 1550 copy = len; 1551 skb_copy_from_linear_data_offset(skb, offset, to, copy); 1552 if ((len -= copy) == 0) 1553 return 0; 1554 offset += copy; 1555 to += copy; 1556 } 1557 1558 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1559 int end; 1560 skb_frag_t *f = &skb_shinfo(skb)->frags[i]; 1561 1562 WARN_ON(start > offset + len); 1563 1564 end = start + skb_frag_size(f); 1565 if ((copy = end - offset) > 0) { 1566 u8 *vaddr; 1567 1568 if (copy > len) 1569 copy = len; 1570 1571 vaddr = kmap_atomic(skb_frag_page(f)); 1572 memcpy(to, 1573 vaddr + f->page_offset + offset - start, 1574 copy); 1575 kunmap_atomic(vaddr); 1576 1577 if ((len -= copy) == 0) 1578 return 0; 1579 offset += copy; 1580 to += copy; 1581 } 1582 start = end; 1583 } 1584 1585 skb_walk_frags(skb, frag_iter) { 1586 int end; 1587 1588 WARN_ON(start > offset + len); 1589 1590 end = start + frag_iter->len; 1591 if ((copy = end - offset) > 0) { 1592 if (copy > len) 1593 copy = len; 1594 if (skb_copy_bits(frag_iter, offset - start, to, copy)) 1595 goto fault; 1596 if ((len -= copy) == 0) 1597 return 0; 1598 offset += copy; 1599 to += copy; 1600 } 1601 start = end; 1602 } 1603 1604 if (!len) 1605 return 0; 1606 1607 fault: 1608 return -EFAULT; 1609 } 1610 EXPORT_SYMBOL(skb_copy_bits); 1611 1612 /* 1613 * Callback from splice_to_pipe(), if we need to release some pages 1614 * at the end of the spd in case we error'ed out in filling the pipe. 1615 */ 1616 static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i) 1617 { 1618 put_page(spd->pages[i]); 1619 } 1620 1621 static struct page *linear_to_page(struct page *page, unsigned int *len, 1622 unsigned int *offset, 1623 struct sk_buff *skb, struct sock *sk) 1624 { 1625 struct page_frag *pfrag = sk_page_frag(sk); 1626 1627 if (!sk_page_frag_refill(sk, pfrag)) 1628 return NULL; 1629 1630 *len = min_t(unsigned int, *len, pfrag->size - pfrag->offset); 1631 1632 memcpy(page_address(pfrag->page) + pfrag->offset, 1633 page_address(page) + *offset, *len); 1634 *offset = pfrag->offset; 1635 pfrag->offset += *len; 1636 1637 return pfrag->page; 1638 } 1639 1640 static bool spd_can_coalesce(const struct splice_pipe_desc *spd, 1641 struct page *page, 1642 unsigned int offset) 1643 { 1644 return spd->nr_pages && 1645 spd->pages[spd->nr_pages - 1] == page && 1646 (spd->partial[spd->nr_pages - 1].offset + 1647 spd->partial[spd->nr_pages - 1].len == offset); 1648 } 1649 1650 /* 1651 * Fill page/offset/length into spd, if it can hold more pages. 1652 */ 1653 static bool spd_fill_page(struct splice_pipe_desc *spd, 1654 struct pipe_inode_info *pipe, struct page *page, 1655 unsigned int *len, unsigned int offset, 1656 struct sk_buff *skb, bool linear, 1657 struct sock *sk) 1658 { 1659 if (unlikely(spd->nr_pages == MAX_SKB_FRAGS)) 1660 return true; 1661 1662 if (linear) { 1663 page = linear_to_page(page, len, &offset, skb, sk); 1664 if (!page) 1665 return true; 1666 } 1667 if (spd_can_coalesce(spd, page, offset)) { 1668 spd->partial[spd->nr_pages - 1].len += *len; 1669 return false; 1670 } 1671 get_page(page); 1672 spd->pages[spd->nr_pages] = page; 1673 spd->partial[spd->nr_pages].len = *len; 1674 spd->partial[spd->nr_pages].offset = offset; 1675 spd->nr_pages++; 1676 1677 return false; 1678 } 1679 1680 static inline void __segment_seek(struct page **page, unsigned int *poff, 1681 unsigned int *plen, unsigned int off) 1682 { 1683 unsigned long n; 1684 1685 *poff += off; 1686 n = *poff / PAGE_SIZE; 1687 if (n) 1688 *page = nth_page(*page, n); 1689 1690 *poff = *poff % PAGE_SIZE; 1691 *plen -= off; 1692 } 1693 1694 static bool __splice_segment(struct page *page, unsigned int poff, 1695 unsigned int plen, unsigned int *off, 1696 unsigned int *len, struct sk_buff *skb, 1697 struct splice_pipe_desc *spd, bool linear, 1698 struct sock *sk, 1699 struct pipe_inode_info *pipe) 1700 { 1701 if (!*len) 1702 return true; 1703 1704 /* skip this segment if already processed */ 1705 if (*off >= plen) { 1706 *off -= plen; 1707 return false; 1708 } 1709 1710 /* ignore any bits we already processed */ 1711 if (*off) { 1712 __segment_seek(&page, &poff, &plen, *off); 1713 *off = 0; 1714 } 1715 1716 do { 1717 unsigned int flen = min(*len, plen); 1718 1719 /* the linear region may spread across several pages */ 1720 flen = min_t(unsigned int, flen, PAGE_SIZE - poff); 1721 1722 if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk)) 1723 return true; 1724 1725 __segment_seek(&page, &poff, &plen, flen); 1726 *len -= flen; 1727 1728 } while (*len && plen); 1729 1730 return false; 1731 } 1732 1733 /* 1734 * Map linear and fragment data from the skb to spd. It reports true if the 1735 * pipe is full or if we already spliced the requested length. 1736 */ 1737 static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe, 1738 unsigned int *offset, unsigned int *len, 1739 struct splice_pipe_desc *spd, struct sock *sk) 1740 { 1741 int seg; 1742 1743 /* map the linear part : 1744 * If skb->head_frag is set, this 'linear' part is backed by a 1745 * fragment, and if the head is not shared with any clones then 1746 * we can avoid a copy since we own the head portion of this page. 1747 */ 1748 if (__splice_segment(virt_to_page(skb->data), 1749 (unsigned long) skb->data & (PAGE_SIZE - 1), 1750 skb_headlen(skb), 1751 offset, len, skb, spd, 1752 skb_head_is_locked(skb), 1753 sk, pipe)) 1754 return true; 1755 1756 /* 1757 * then map the fragments 1758 */ 1759 for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) { 1760 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg]; 1761 1762 if (__splice_segment(skb_frag_page(f), 1763 f->page_offset, skb_frag_size(f), 1764 offset, len, skb, spd, false, sk, pipe)) 1765 return true; 1766 } 1767 1768 return false; 1769 } 1770 1771 /* 1772 * Map data from the skb to a pipe. Should handle both the linear part, 1773 * the fragments, and the frag list. It does NOT handle frag lists within 1774 * the frag list, if such a thing exists. We'd probably need to recurse to 1775 * handle that cleanly. 1776 */ 1777 int skb_splice_bits(struct sk_buff *skb, unsigned int offset, 1778 struct pipe_inode_info *pipe, unsigned int tlen, 1779 unsigned int flags) 1780 { 1781 struct partial_page partial[MAX_SKB_FRAGS]; 1782 struct page *pages[MAX_SKB_FRAGS]; 1783 struct splice_pipe_desc spd = { 1784 .pages = pages, 1785 .partial = partial, 1786 .nr_pages_max = MAX_SKB_FRAGS, 1787 .flags = flags, 1788 .ops = &sock_pipe_buf_ops, 1789 .spd_release = sock_spd_release, 1790 }; 1791 struct sk_buff *frag_iter; 1792 struct sock *sk = skb->sk; 1793 int ret = 0; 1794 1795 /* 1796 * __skb_splice_bits() only fails if the output has no room left, 1797 * so no point in going over the frag_list for the error case. 1798 */ 1799 if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk)) 1800 goto done; 1801 else if (!tlen) 1802 goto done; 1803 1804 /* 1805 * now see if we have a frag_list to map 1806 */ 1807 skb_walk_frags(skb, frag_iter) { 1808 if (!tlen) 1809 break; 1810 if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk)) 1811 break; 1812 } 1813 1814 done: 1815 if (spd.nr_pages) { 1816 /* 1817 * Drop the socket lock, otherwise we have reverse 1818 * locking dependencies between sk_lock and i_mutex 1819 * here as compared to sendfile(). We enter here 1820 * with the socket lock held, and splice_to_pipe() will 1821 * grab the pipe inode lock. For sendfile() emulation, 1822 * we call into ->sendpage() with the i_mutex lock held 1823 * and networking will grab the socket lock. 1824 */ 1825 release_sock(sk); 1826 ret = splice_to_pipe(pipe, &spd); 1827 lock_sock(sk); 1828 } 1829 1830 return ret; 1831 } 1832 1833 /** 1834 * skb_store_bits - store bits from kernel buffer to skb 1835 * @skb: destination buffer 1836 * @offset: offset in destination 1837 * @from: source buffer 1838 * @len: number of bytes to copy 1839 * 1840 * Copy the specified number of bytes from the source buffer to the 1841 * destination skb. This function handles all the messy bits of 1842 * traversing fragment lists and such. 1843 */ 1844 1845 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len) 1846 { 1847 int start = skb_headlen(skb); 1848 struct sk_buff *frag_iter; 1849 int i, copy; 1850 1851 if (offset > (int)skb->len - len) 1852 goto fault; 1853 1854 if ((copy = start - offset) > 0) { 1855 if (copy > len) 1856 copy = len; 1857 skb_copy_to_linear_data_offset(skb, offset, from, copy); 1858 if ((len -= copy) == 0) 1859 return 0; 1860 offset += copy; 1861 from += copy; 1862 } 1863 1864 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1865 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 1866 int end; 1867 1868 WARN_ON(start > offset + len); 1869 1870 end = start + skb_frag_size(frag); 1871 if ((copy = end - offset) > 0) { 1872 u8 *vaddr; 1873 1874 if (copy > len) 1875 copy = len; 1876 1877 vaddr = kmap_atomic(skb_frag_page(frag)); 1878 memcpy(vaddr + frag->page_offset + offset - start, 1879 from, copy); 1880 kunmap_atomic(vaddr); 1881 1882 if ((len -= copy) == 0) 1883 return 0; 1884 offset += copy; 1885 from += copy; 1886 } 1887 start = end; 1888 } 1889 1890 skb_walk_frags(skb, frag_iter) { 1891 int end; 1892 1893 WARN_ON(start > offset + len); 1894 1895 end = start + frag_iter->len; 1896 if ((copy = end - offset) > 0) { 1897 if (copy > len) 1898 copy = len; 1899 if (skb_store_bits(frag_iter, offset - start, 1900 from, copy)) 1901 goto fault; 1902 if ((len -= copy) == 0) 1903 return 0; 1904 offset += copy; 1905 from += copy; 1906 } 1907 start = end; 1908 } 1909 if (!len) 1910 return 0; 1911 1912 fault: 1913 return -EFAULT; 1914 } 1915 EXPORT_SYMBOL(skb_store_bits); 1916 1917 /* Checksum skb data. */ 1918 1919 __wsum skb_checksum(const struct sk_buff *skb, int offset, 1920 int len, __wsum csum) 1921 { 1922 int start = skb_headlen(skb); 1923 int i, copy = start - offset; 1924 struct sk_buff *frag_iter; 1925 int pos = 0; 1926 1927 /* Checksum header. */ 1928 if (copy > 0) { 1929 if (copy > len) 1930 copy = len; 1931 csum = csum_partial(skb->data + offset, copy, csum); 1932 if ((len -= copy) == 0) 1933 return csum; 1934 offset += copy; 1935 pos = copy; 1936 } 1937 1938 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1939 int end; 1940 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 1941 1942 WARN_ON(start > offset + len); 1943 1944 end = start + skb_frag_size(frag); 1945 if ((copy = end - offset) > 0) { 1946 __wsum csum2; 1947 u8 *vaddr; 1948 1949 if (copy > len) 1950 copy = len; 1951 vaddr = kmap_atomic(skb_frag_page(frag)); 1952 csum2 = csum_partial(vaddr + frag->page_offset + 1953 offset - start, copy, 0); 1954 kunmap_atomic(vaddr); 1955 csum = csum_block_add(csum, csum2, pos); 1956 if (!(len -= copy)) 1957 return csum; 1958 offset += copy; 1959 pos += copy; 1960 } 1961 start = end; 1962 } 1963 1964 skb_walk_frags(skb, frag_iter) { 1965 int end; 1966 1967 WARN_ON(start > offset + len); 1968 1969 end = start + frag_iter->len; 1970 if ((copy = end - offset) > 0) { 1971 __wsum csum2; 1972 if (copy > len) 1973 copy = len; 1974 csum2 = skb_checksum(frag_iter, offset - start, 1975 copy, 0); 1976 csum = csum_block_add(csum, csum2, pos); 1977 if ((len -= copy) == 0) 1978 return csum; 1979 offset += copy; 1980 pos += copy; 1981 } 1982 start = end; 1983 } 1984 BUG_ON(len); 1985 1986 return csum; 1987 } 1988 EXPORT_SYMBOL(skb_checksum); 1989 1990 /* Both of above in one bottle. */ 1991 1992 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, 1993 u8 *to, int len, __wsum csum) 1994 { 1995 int start = skb_headlen(skb); 1996 int i, copy = start - offset; 1997 struct sk_buff *frag_iter; 1998 int pos = 0; 1999 2000 /* Copy header. */ 2001 if (copy > 0) { 2002 if (copy > len) 2003 copy = len; 2004 csum = csum_partial_copy_nocheck(skb->data + offset, to, 2005 copy, csum); 2006 if ((len -= copy) == 0) 2007 return csum; 2008 offset += copy; 2009 to += copy; 2010 pos = copy; 2011 } 2012 2013 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 2014 int end; 2015 2016 WARN_ON(start > offset + len); 2017 2018 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]); 2019 if ((copy = end - offset) > 0) { 2020 __wsum csum2; 2021 u8 *vaddr; 2022 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 2023 2024 if (copy > len) 2025 copy = len; 2026 vaddr = kmap_atomic(skb_frag_page(frag)); 2027 csum2 = csum_partial_copy_nocheck(vaddr + 2028 frag->page_offset + 2029 offset - start, to, 2030 copy, 0); 2031 kunmap_atomic(vaddr); 2032 csum = csum_block_add(csum, csum2, pos); 2033 if (!(len -= copy)) 2034 return csum; 2035 offset += copy; 2036 to += copy; 2037 pos += copy; 2038 } 2039 start = end; 2040 } 2041 2042 skb_walk_frags(skb, frag_iter) { 2043 __wsum csum2; 2044 int end; 2045 2046 WARN_ON(start > offset + len); 2047 2048 end = start + frag_iter->len; 2049 if ((copy = end - offset) > 0) { 2050 if (copy > len) 2051 copy = len; 2052 csum2 = skb_copy_and_csum_bits(frag_iter, 2053 offset - start, 2054 to, copy, 0); 2055 csum = csum_block_add(csum, csum2, pos); 2056 if ((len -= copy) == 0) 2057 return csum; 2058 offset += copy; 2059 to += copy; 2060 pos += copy; 2061 } 2062 start = end; 2063 } 2064 BUG_ON(len); 2065 return csum; 2066 } 2067 EXPORT_SYMBOL(skb_copy_and_csum_bits); 2068 2069 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to) 2070 { 2071 __wsum csum; 2072 long csstart; 2073 2074 if (skb->ip_summed == CHECKSUM_PARTIAL) 2075 csstart = skb_checksum_start_offset(skb); 2076 else 2077 csstart = skb_headlen(skb); 2078 2079 BUG_ON(csstart > skb_headlen(skb)); 2080 2081 skb_copy_from_linear_data(skb, to, csstart); 2082 2083 csum = 0; 2084 if (csstart != skb->len) 2085 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart, 2086 skb->len - csstart, 0); 2087 2088 if (skb->ip_summed == CHECKSUM_PARTIAL) { 2089 long csstuff = csstart + skb->csum_offset; 2090 2091 *((__sum16 *)(to + csstuff)) = csum_fold(csum); 2092 } 2093 } 2094 EXPORT_SYMBOL(skb_copy_and_csum_dev); 2095 2096 /** 2097 * skb_dequeue - remove from the head of the queue 2098 * @list: list to dequeue from 2099 * 2100 * Remove the head of the list. The list lock is taken so the function 2101 * may be used safely with other locking list functions. The head item is 2102 * returned or %NULL if the list is empty. 2103 */ 2104 2105 struct sk_buff *skb_dequeue(struct sk_buff_head *list) 2106 { 2107 unsigned long flags; 2108 struct sk_buff *result; 2109 2110 spin_lock_irqsave(&list->lock, flags); 2111 result = __skb_dequeue(list); 2112 spin_unlock_irqrestore(&list->lock, flags); 2113 return result; 2114 } 2115 EXPORT_SYMBOL(skb_dequeue); 2116 2117 /** 2118 * skb_dequeue_tail - remove from the tail of the queue 2119 * @list: list to dequeue from 2120 * 2121 * Remove the tail of the list. The list lock is taken so the function 2122 * may be used safely with other locking list functions. The tail item is 2123 * returned or %NULL if the list is empty. 2124 */ 2125 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list) 2126 { 2127 unsigned long flags; 2128 struct sk_buff *result; 2129 2130 spin_lock_irqsave(&list->lock, flags); 2131 result = __skb_dequeue_tail(list); 2132 spin_unlock_irqrestore(&list->lock, flags); 2133 return result; 2134 } 2135 EXPORT_SYMBOL(skb_dequeue_tail); 2136 2137 /** 2138 * skb_queue_purge - empty a list 2139 * @list: list to empty 2140 * 2141 * Delete all buffers on an &sk_buff list. Each buffer is removed from 2142 * the list and one reference dropped. This function takes the list 2143 * lock and is atomic with respect to other list locking functions. 2144 */ 2145 void skb_queue_purge(struct sk_buff_head *list) 2146 { 2147 struct sk_buff *skb; 2148 while ((skb = skb_dequeue(list)) != NULL) 2149 kfree_skb(skb); 2150 } 2151 EXPORT_SYMBOL(skb_queue_purge); 2152 2153 /** 2154 * skb_queue_head - queue a buffer at the list head 2155 * @list: list to use 2156 * @newsk: buffer to queue 2157 * 2158 * Queue a buffer at the start of the list. This function takes the 2159 * list lock and can be used safely with other locking &sk_buff functions 2160 * safely. 2161 * 2162 * A buffer cannot be placed on two lists at the same time. 2163 */ 2164 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk) 2165 { 2166 unsigned long flags; 2167 2168 spin_lock_irqsave(&list->lock, flags); 2169 __skb_queue_head(list, newsk); 2170 spin_unlock_irqrestore(&list->lock, flags); 2171 } 2172 EXPORT_SYMBOL(skb_queue_head); 2173 2174 /** 2175 * skb_queue_tail - queue a buffer at the list tail 2176 * @list: list to use 2177 * @newsk: buffer to queue 2178 * 2179 * Queue a buffer at the tail of the list. This function takes the 2180 * list lock and can be used safely with other locking &sk_buff functions 2181 * safely. 2182 * 2183 * A buffer cannot be placed on two lists at the same time. 2184 */ 2185 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk) 2186 { 2187 unsigned long flags; 2188 2189 spin_lock_irqsave(&list->lock, flags); 2190 __skb_queue_tail(list, newsk); 2191 spin_unlock_irqrestore(&list->lock, flags); 2192 } 2193 EXPORT_SYMBOL(skb_queue_tail); 2194 2195 /** 2196 * skb_unlink - remove a buffer from a list 2197 * @skb: buffer to remove 2198 * @list: list to use 2199 * 2200 * Remove a packet from a list. The list locks are taken and this 2201 * function is atomic with respect to other list locked calls 2202 * 2203 * You must know what list the SKB is on. 2204 */ 2205 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list) 2206 { 2207 unsigned long flags; 2208 2209 spin_lock_irqsave(&list->lock, flags); 2210 __skb_unlink(skb, list); 2211 spin_unlock_irqrestore(&list->lock, flags); 2212 } 2213 EXPORT_SYMBOL(skb_unlink); 2214 2215 /** 2216 * skb_append - append a buffer 2217 * @old: buffer to insert after 2218 * @newsk: buffer to insert 2219 * @list: list to use 2220 * 2221 * Place a packet after a given packet in a list. The list locks are taken 2222 * and this function is atomic with respect to other list locked calls. 2223 * A buffer cannot be placed on two lists at the same time. 2224 */ 2225 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list) 2226 { 2227 unsigned long flags; 2228 2229 spin_lock_irqsave(&list->lock, flags); 2230 __skb_queue_after(list, old, newsk); 2231 spin_unlock_irqrestore(&list->lock, flags); 2232 } 2233 EXPORT_SYMBOL(skb_append); 2234 2235 /** 2236 * skb_insert - insert a buffer 2237 * @old: buffer to insert before 2238 * @newsk: buffer to insert 2239 * @list: list to use 2240 * 2241 * Place a packet before a given packet in a list. The list locks are 2242 * taken and this function is atomic with respect to other list locked 2243 * calls. 2244 * 2245 * A buffer cannot be placed on two lists at the same time. 2246 */ 2247 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list) 2248 { 2249 unsigned long flags; 2250 2251 spin_lock_irqsave(&list->lock, flags); 2252 __skb_insert(newsk, old->prev, old, list); 2253 spin_unlock_irqrestore(&list->lock, flags); 2254 } 2255 EXPORT_SYMBOL(skb_insert); 2256 2257 static inline void skb_split_inside_header(struct sk_buff *skb, 2258 struct sk_buff* skb1, 2259 const u32 len, const int pos) 2260 { 2261 int i; 2262 2263 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len), 2264 pos - len); 2265 /* And move data appendix as is. */ 2266 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 2267 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i]; 2268 2269 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags; 2270 skb_shinfo(skb)->nr_frags = 0; 2271 skb1->data_len = skb->data_len; 2272 skb1->len += skb1->data_len; 2273 skb->data_len = 0; 2274 skb->len = len; 2275 skb_set_tail_pointer(skb, len); 2276 } 2277 2278 static inline void skb_split_no_header(struct sk_buff *skb, 2279 struct sk_buff* skb1, 2280 const u32 len, int pos) 2281 { 2282 int i, k = 0; 2283 const int nfrags = skb_shinfo(skb)->nr_frags; 2284 2285 skb_shinfo(skb)->nr_frags = 0; 2286 skb1->len = skb1->data_len = skb->len - len; 2287 skb->len = len; 2288 skb->data_len = len - pos; 2289 2290 for (i = 0; i < nfrags; i++) { 2291 int size = skb_frag_size(&skb_shinfo(skb)->frags[i]); 2292 2293 if (pos + size > len) { 2294 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i]; 2295 2296 if (pos < len) { 2297 /* Split frag. 2298 * We have two variants in this case: 2299 * 1. Move all the frag to the second 2300 * part, if it is possible. F.e. 2301 * this approach is mandatory for TUX, 2302 * where splitting is expensive. 2303 * 2. Split is accurately. We make this. 2304 */ 2305 skb_frag_ref(skb, i); 2306 skb_shinfo(skb1)->frags[0].page_offset += len - pos; 2307 skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos); 2308 skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos); 2309 skb_shinfo(skb)->nr_frags++; 2310 } 2311 k++; 2312 } else 2313 skb_shinfo(skb)->nr_frags++; 2314 pos += size; 2315 } 2316 skb_shinfo(skb1)->nr_frags = k; 2317 } 2318 2319 /** 2320 * skb_split - Split fragmented skb to two parts at length len. 2321 * @skb: the buffer to split 2322 * @skb1: the buffer to receive the second part 2323 * @len: new length for skb 2324 */ 2325 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len) 2326 { 2327 int pos = skb_headlen(skb); 2328 2329 if (len < pos) /* Split line is inside header. */ 2330 skb_split_inside_header(skb, skb1, len, pos); 2331 else /* Second chunk has no header, nothing to copy. */ 2332 skb_split_no_header(skb, skb1, len, pos); 2333 } 2334 EXPORT_SYMBOL(skb_split); 2335 2336 /* Shifting from/to a cloned skb is a no-go. 2337 * 2338 * Caller cannot keep skb_shinfo related pointers past calling here! 2339 */ 2340 static int skb_prepare_for_shift(struct sk_buff *skb) 2341 { 2342 return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC); 2343 } 2344 2345 /** 2346 * skb_shift - Shifts paged data partially from skb to another 2347 * @tgt: buffer into which tail data gets added 2348 * @skb: buffer from which the paged data comes from 2349 * @shiftlen: shift up to this many bytes 2350 * 2351 * Attempts to shift up to shiftlen worth of bytes, which may be less than 2352 * the length of the skb, from skb to tgt. Returns number bytes shifted. 2353 * It's up to caller to free skb if everything was shifted. 2354 * 2355 * If @tgt runs out of frags, the whole operation is aborted. 2356 * 2357 * Skb cannot include anything else but paged data while tgt is allowed 2358 * to have non-paged data as well. 2359 * 2360 * TODO: full sized shift could be optimized but that would need 2361 * specialized skb free'er to handle frags without up-to-date nr_frags. 2362 */ 2363 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen) 2364 { 2365 int from, to, merge, todo; 2366 struct skb_frag_struct *fragfrom, *fragto; 2367 2368 BUG_ON(shiftlen > skb->len); 2369 BUG_ON(skb_headlen(skb)); /* Would corrupt stream */ 2370 2371 todo = shiftlen; 2372 from = 0; 2373 to = skb_shinfo(tgt)->nr_frags; 2374 fragfrom = &skb_shinfo(skb)->frags[from]; 2375 2376 /* Actual merge is delayed until the point when we know we can 2377 * commit all, so that we don't have to undo partial changes 2378 */ 2379 if (!to || 2380 !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom), 2381 fragfrom->page_offset)) { 2382 merge = -1; 2383 } else { 2384 merge = to - 1; 2385 2386 todo -= skb_frag_size(fragfrom); 2387 if (todo < 0) { 2388 if (skb_prepare_for_shift(skb) || 2389 skb_prepare_for_shift(tgt)) 2390 return 0; 2391 2392 /* All previous frag pointers might be stale! */ 2393 fragfrom = &skb_shinfo(skb)->frags[from]; 2394 fragto = &skb_shinfo(tgt)->frags[merge]; 2395 2396 skb_frag_size_add(fragto, shiftlen); 2397 skb_frag_size_sub(fragfrom, shiftlen); 2398 fragfrom->page_offset += shiftlen; 2399 2400 goto onlymerged; 2401 } 2402 2403 from++; 2404 } 2405 2406 /* Skip full, not-fitting skb to avoid expensive operations */ 2407 if ((shiftlen == skb->len) && 2408 (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to)) 2409 return 0; 2410 2411 if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt)) 2412 return 0; 2413 2414 while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) { 2415 if (to == MAX_SKB_FRAGS) 2416 return 0; 2417 2418 fragfrom = &skb_shinfo(skb)->frags[from]; 2419 fragto = &skb_shinfo(tgt)->frags[to]; 2420 2421 if (todo >= skb_frag_size(fragfrom)) { 2422 *fragto = *fragfrom; 2423 todo -= skb_frag_size(fragfrom); 2424 from++; 2425 to++; 2426 2427 } else { 2428 __skb_frag_ref(fragfrom); 2429 fragto->page = fragfrom->page; 2430 fragto->page_offset = fragfrom->page_offset; 2431 skb_frag_size_set(fragto, todo); 2432 2433 fragfrom->page_offset += todo; 2434 skb_frag_size_sub(fragfrom, todo); 2435 todo = 0; 2436 2437 to++; 2438 break; 2439 } 2440 } 2441 2442 /* Ready to "commit" this state change to tgt */ 2443 skb_shinfo(tgt)->nr_frags = to; 2444 2445 if (merge >= 0) { 2446 fragfrom = &skb_shinfo(skb)->frags[0]; 2447 fragto = &skb_shinfo(tgt)->frags[merge]; 2448 2449 skb_frag_size_add(fragto, skb_frag_size(fragfrom)); 2450 __skb_frag_unref(fragfrom); 2451 } 2452 2453 /* Reposition in the original skb */ 2454 to = 0; 2455 while (from < skb_shinfo(skb)->nr_frags) 2456 skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++]; 2457 skb_shinfo(skb)->nr_frags = to; 2458 2459 BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags); 2460 2461 onlymerged: 2462 /* Most likely the tgt won't ever need its checksum anymore, skb on 2463 * the other hand might need it if it needs to be resent 2464 */ 2465 tgt->ip_summed = CHECKSUM_PARTIAL; 2466 skb->ip_summed = CHECKSUM_PARTIAL; 2467 2468 /* Yak, is it really working this way? Some helper please? */ 2469 skb->len -= shiftlen; 2470 skb->data_len -= shiftlen; 2471 skb->truesize -= shiftlen; 2472 tgt->len += shiftlen; 2473 tgt->data_len += shiftlen; 2474 tgt->truesize += shiftlen; 2475 2476 return shiftlen; 2477 } 2478 2479 /** 2480 * skb_prepare_seq_read - Prepare a sequential read of skb data 2481 * @skb: the buffer to read 2482 * @from: lower offset of data to be read 2483 * @to: upper offset of data to be read 2484 * @st: state variable 2485 * 2486 * Initializes the specified state variable. Must be called before 2487 * invoking skb_seq_read() for the first time. 2488 */ 2489 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from, 2490 unsigned int to, struct skb_seq_state *st) 2491 { 2492 st->lower_offset = from; 2493 st->upper_offset = to; 2494 st->root_skb = st->cur_skb = skb; 2495 st->frag_idx = st->stepped_offset = 0; 2496 st->frag_data = NULL; 2497 } 2498 EXPORT_SYMBOL(skb_prepare_seq_read); 2499 2500 /** 2501 * skb_seq_read - Sequentially read skb data 2502 * @consumed: number of bytes consumed by the caller so far 2503 * @data: destination pointer for data to be returned 2504 * @st: state variable 2505 * 2506 * Reads a block of skb data at &consumed relative to the 2507 * lower offset specified to skb_prepare_seq_read(). Assigns 2508 * the head of the data block to &data and returns the length 2509 * of the block or 0 if the end of the skb data or the upper 2510 * offset has been reached. 2511 * 2512 * The caller is not required to consume all of the data 2513 * returned, i.e. &consumed is typically set to the number 2514 * of bytes already consumed and the next call to 2515 * skb_seq_read() will return the remaining part of the block. 2516 * 2517 * Note 1: The size of each block of data returned can be arbitrary, 2518 * this limitation is the cost for zerocopy seqeuental 2519 * reads of potentially non linear data. 2520 * 2521 * Note 2: Fragment lists within fragments are not implemented 2522 * at the moment, state->root_skb could be replaced with 2523 * a stack for this purpose. 2524 */ 2525 unsigned int skb_seq_read(unsigned int consumed, const u8 **data, 2526 struct skb_seq_state *st) 2527 { 2528 unsigned int block_limit, abs_offset = consumed + st->lower_offset; 2529 skb_frag_t *frag; 2530 2531 if (unlikely(abs_offset >= st->upper_offset)) 2532 return 0; 2533 2534 next_skb: 2535 block_limit = skb_headlen(st->cur_skb) + st->stepped_offset; 2536 2537 if (abs_offset < block_limit && !st->frag_data) { 2538 *data = st->cur_skb->data + (abs_offset - st->stepped_offset); 2539 return block_limit - abs_offset; 2540 } 2541 2542 if (st->frag_idx == 0 && !st->frag_data) 2543 st->stepped_offset += skb_headlen(st->cur_skb); 2544 2545 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) { 2546 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx]; 2547 block_limit = skb_frag_size(frag) + st->stepped_offset; 2548 2549 if (abs_offset < block_limit) { 2550 if (!st->frag_data) 2551 st->frag_data = kmap_atomic(skb_frag_page(frag)); 2552 2553 *data = (u8 *) st->frag_data + frag->page_offset + 2554 (abs_offset - st->stepped_offset); 2555 2556 return block_limit - abs_offset; 2557 } 2558 2559 if (st->frag_data) { 2560 kunmap_atomic(st->frag_data); 2561 st->frag_data = NULL; 2562 } 2563 2564 st->frag_idx++; 2565 st->stepped_offset += skb_frag_size(frag); 2566 } 2567 2568 if (st->frag_data) { 2569 kunmap_atomic(st->frag_data); 2570 st->frag_data = NULL; 2571 } 2572 2573 if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) { 2574 st->cur_skb = skb_shinfo(st->root_skb)->frag_list; 2575 st->frag_idx = 0; 2576 goto next_skb; 2577 } else if (st->cur_skb->next) { 2578 st->cur_skb = st->cur_skb->next; 2579 st->frag_idx = 0; 2580 goto next_skb; 2581 } 2582 2583 return 0; 2584 } 2585 EXPORT_SYMBOL(skb_seq_read); 2586 2587 /** 2588 * skb_abort_seq_read - Abort a sequential read of skb data 2589 * @st: state variable 2590 * 2591 * Must be called if skb_seq_read() was not called until it 2592 * returned 0. 2593 */ 2594 void skb_abort_seq_read(struct skb_seq_state *st) 2595 { 2596 if (st->frag_data) 2597 kunmap_atomic(st->frag_data); 2598 } 2599 EXPORT_SYMBOL(skb_abort_seq_read); 2600 2601 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb)) 2602 2603 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text, 2604 struct ts_config *conf, 2605 struct ts_state *state) 2606 { 2607 return skb_seq_read(offset, text, TS_SKB_CB(state)); 2608 } 2609 2610 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state) 2611 { 2612 skb_abort_seq_read(TS_SKB_CB(state)); 2613 } 2614 2615 /** 2616 * skb_find_text - Find a text pattern in skb data 2617 * @skb: the buffer to look in 2618 * @from: search offset 2619 * @to: search limit 2620 * @config: textsearch configuration 2621 * @state: uninitialized textsearch state variable 2622 * 2623 * Finds a pattern in the skb data according to the specified 2624 * textsearch configuration. Use textsearch_next() to retrieve 2625 * subsequent occurrences of the pattern. Returns the offset 2626 * to the first occurrence or UINT_MAX if no match was found. 2627 */ 2628 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from, 2629 unsigned int to, struct ts_config *config, 2630 struct ts_state *state) 2631 { 2632 unsigned int ret; 2633 2634 config->get_next_block = skb_ts_get_next_block; 2635 config->finish = skb_ts_finish; 2636 2637 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state)); 2638 2639 ret = textsearch_find(config, state); 2640 return (ret <= to - from ? ret : UINT_MAX); 2641 } 2642 EXPORT_SYMBOL(skb_find_text); 2643 2644 /** 2645 * skb_append_datato_frags - append the user data to a skb 2646 * @sk: sock structure 2647 * @skb: skb structure to be appened with user data. 2648 * @getfrag: call back function to be used for getting the user data 2649 * @from: pointer to user message iov 2650 * @length: length of the iov message 2651 * 2652 * Description: This procedure append the user data in the fragment part 2653 * of the skb if any page alloc fails user this procedure returns -ENOMEM 2654 */ 2655 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb, 2656 int (*getfrag)(void *from, char *to, int offset, 2657 int len, int odd, struct sk_buff *skb), 2658 void *from, int length) 2659 { 2660 int frg_cnt = 0; 2661 skb_frag_t *frag = NULL; 2662 struct page *page = NULL; 2663 int copy, left; 2664 int offset = 0; 2665 int ret; 2666 2667 do { 2668 /* Return error if we don't have space for new frag */ 2669 frg_cnt = skb_shinfo(skb)->nr_frags; 2670 if (frg_cnt >= MAX_SKB_FRAGS) 2671 return -EFAULT; 2672 2673 /* allocate a new page for next frag */ 2674 page = alloc_pages(sk->sk_allocation, 0); 2675 2676 /* If alloc_page fails just return failure and caller will 2677 * free previous allocated pages by doing kfree_skb() 2678 */ 2679 if (page == NULL) 2680 return -ENOMEM; 2681 2682 /* initialize the next frag */ 2683 skb_fill_page_desc(skb, frg_cnt, page, 0, 0); 2684 skb->truesize += PAGE_SIZE; 2685 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc); 2686 2687 /* get the new initialized frag */ 2688 frg_cnt = skb_shinfo(skb)->nr_frags; 2689 frag = &skb_shinfo(skb)->frags[frg_cnt - 1]; 2690 2691 /* copy the user data to page */ 2692 left = PAGE_SIZE - frag->page_offset; 2693 copy = (length > left)? left : length; 2694 2695 ret = getfrag(from, skb_frag_address(frag) + skb_frag_size(frag), 2696 offset, copy, 0, skb); 2697 if (ret < 0) 2698 return -EFAULT; 2699 2700 /* copy was successful so update the size parameters */ 2701 skb_frag_size_add(frag, copy); 2702 skb->len += copy; 2703 skb->data_len += copy; 2704 offset += copy; 2705 length -= copy; 2706 2707 } while (length > 0); 2708 2709 return 0; 2710 } 2711 EXPORT_SYMBOL(skb_append_datato_frags); 2712 2713 /** 2714 * skb_pull_rcsum - pull skb and update receive checksum 2715 * @skb: buffer to update 2716 * @len: length of data pulled 2717 * 2718 * This function performs an skb_pull on the packet and updates 2719 * the CHECKSUM_COMPLETE checksum. It should be used on 2720 * receive path processing instead of skb_pull unless you know 2721 * that the checksum difference is zero (e.g., a valid IP header) 2722 * or you are setting ip_summed to CHECKSUM_NONE. 2723 */ 2724 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len) 2725 { 2726 BUG_ON(len > skb->len); 2727 skb->len -= len; 2728 BUG_ON(skb->len < skb->data_len); 2729 skb_postpull_rcsum(skb, skb->data, len); 2730 return skb->data += len; 2731 } 2732 EXPORT_SYMBOL_GPL(skb_pull_rcsum); 2733 2734 /** 2735 * skb_segment - Perform protocol segmentation on skb. 2736 * @skb: buffer to segment 2737 * @features: features for the output path (see dev->features) 2738 * 2739 * This function performs segmentation on the given skb. It returns 2740 * a pointer to the first in a list of new skbs for the segments. 2741 * In case of error it returns ERR_PTR(err). 2742 */ 2743 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) 2744 { 2745 struct sk_buff *segs = NULL; 2746 struct sk_buff *tail = NULL; 2747 struct sk_buff *fskb = skb_shinfo(skb)->frag_list; 2748 unsigned int mss = skb_shinfo(skb)->gso_size; 2749 unsigned int doffset = skb->data - skb_mac_header(skb); 2750 unsigned int offset = doffset; 2751 unsigned int headroom; 2752 unsigned int len; 2753 int sg = !!(features & NETIF_F_SG); 2754 int nfrags = skb_shinfo(skb)->nr_frags; 2755 int err = -ENOMEM; 2756 int i = 0; 2757 int pos; 2758 2759 __skb_push(skb, doffset); 2760 headroom = skb_headroom(skb); 2761 pos = skb_headlen(skb); 2762 2763 do { 2764 struct sk_buff *nskb; 2765 skb_frag_t *frag; 2766 int hsize; 2767 int size; 2768 2769 len = skb->len - offset; 2770 if (len > mss) 2771 len = mss; 2772 2773 hsize = skb_headlen(skb) - offset; 2774 if (hsize < 0) 2775 hsize = 0; 2776 if (hsize > len || !sg) 2777 hsize = len; 2778 2779 if (!hsize && i >= nfrags) { 2780 BUG_ON(fskb->len != len); 2781 2782 pos += len; 2783 nskb = skb_clone(fskb, GFP_ATOMIC); 2784 fskb = fskb->next; 2785 2786 if (unlikely(!nskb)) 2787 goto err; 2788 2789 hsize = skb_end_offset(nskb); 2790 if (skb_cow_head(nskb, doffset + headroom)) { 2791 kfree_skb(nskb); 2792 goto err; 2793 } 2794 2795 nskb->truesize += skb_end_offset(nskb) - hsize; 2796 skb_release_head_state(nskb); 2797 __skb_push(nskb, doffset); 2798 } else { 2799 nskb = __alloc_skb(hsize + doffset + headroom, 2800 GFP_ATOMIC, skb_alloc_rx_flag(skb), 2801 NUMA_NO_NODE); 2802 2803 if (unlikely(!nskb)) 2804 goto err; 2805 2806 skb_reserve(nskb, headroom); 2807 __skb_put(nskb, doffset); 2808 } 2809 2810 if (segs) 2811 tail->next = nskb; 2812 else 2813 segs = nskb; 2814 tail = nskb; 2815 2816 __copy_skb_header(nskb, skb); 2817 nskb->mac_len = skb->mac_len; 2818 2819 /* nskb and skb might have different headroom */ 2820 if (nskb->ip_summed == CHECKSUM_PARTIAL) 2821 nskb->csum_start += skb_headroom(nskb) - headroom; 2822 2823 skb_reset_mac_header(nskb); 2824 skb_set_network_header(nskb, skb->mac_len); 2825 nskb->transport_header = (nskb->network_header + 2826 skb_network_header_len(skb)); 2827 skb_copy_from_linear_data(skb, nskb->data, doffset); 2828 2829 if (fskb != skb_shinfo(skb)->frag_list) 2830 continue; 2831 2832 if (!sg) { 2833 nskb->ip_summed = CHECKSUM_NONE; 2834 nskb->csum = skb_copy_and_csum_bits(skb, offset, 2835 skb_put(nskb, len), 2836 len, 0); 2837 continue; 2838 } 2839 2840 frag = skb_shinfo(nskb)->frags; 2841 2842 skb_copy_from_linear_data_offset(skb, offset, 2843 skb_put(nskb, hsize), hsize); 2844 2845 while (pos < offset + len && i < nfrags) { 2846 *frag = skb_shinfo(skb)->frags[i]; 2847 __skb_frag_ref(frag); 2848 size = skb_frag_size(frag); 2849 2850 if (pos < offset) { 2851 frag->page_offset += offset - pos; 2852 skb_frag_size_sub(frag, offset - pos); 2853 } 2854 2855 skb_shinfo(nskb)->nr_frags++; 2856 2857 if (pos + size <= offset + len) { 2858 i++; 2859 pos += size; 2860 } else { 2861 skb_frag_size_sub(frag, pos + size - (offset + len)); 2862 goto skip_fraglist; 2863 } 2864 2865 frag++; 2866 } 2867 2868 if (pos < offset + len) { 2869 struct sk_buff *fskb2 = fskb; 2870 2871 BUG_ON(pos + fskb->len != offset + len); 2872 2873 pos += fskb->len; 2874 fskb = fskb->next; 2875 2876 if (fskb2->next) { 2877 fskb2 = skb_clone(fskb2, GFP_ATOMIC); 2878 if (!fskb2) 2879 goto err; 2880 } else 2881 skb_get(fskb2); 2882 2883 SKB_FRAG_ASSERT(nskb); 2884 skb_shinfo(nskb)->frag_list = fskb2; 2885 } 2886 2887 skip_fraglist: 2888 nskb->data_len = len - hsize; 2889 nskb->len += nskb->data_len; 2890 nskb->truesize += nskb->data_len; 2891 } while ((offset += len) < skb->len); 2892 2893 return segs; 2894 2895 err: 2896 while ((skb = segs)) { 2897 segs = skb->next; 2898 kfree_skb(skb); 2899 } 2900 return ERR_PTR(err); 2901 } 2902 EXPORT_SYMBOL_GPL(skb_segment); 2903 2904 int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) 2905 { 2906 struct sk_buff *p = *head; 2907 struct sk_buff *nskb; 2908 struct skb_shared_info *skbinfo = skb_shinfo(skb); 2909 struct skb_shared_info *pinfo = skb_shinfo(p); 2910 unsigned int headroom; 2911 unsigned int len = skb_gro_len(skb); 2912 unsigned int offset = skb_gro_offset(skb); 2913 unsigned int headlen = skb_headlen(skb); 2914 unsigned int delta_truesize; 2915 2916 if (p->len + len >= 65536) 2917 return -E2BIG; 2918 2919 if (pinfo->frag_list) 2920 goto merge; 2921 else if (headlen <= offset) { 2922 skb_frag_t *frag; 2923 skb_frag_t *frag2; 2924 int i = skbinfo->nr_frags; 2925 int nr_frags = pinfo->nr_frags + i; 2926 2927 offset -= headlen; 2928 2929 if (nr_frags > MAX_SKB_FRAGS) 2930 return -E2BIG; 2931 2932 pinfo->nr_frags = nr_frags; 2933 skbinfo->nr_frags = 0; 2934 2935 frag = pinfo->frags + nr_frags; 2936 frag2 = skbinfo->frags + i; 2937 do { 2938 *--frag = *--frag2; 2939 } while (--i); 2940 2941 frag->page_offset += offset; 2942 skb_frag_size_sub(frag, offset); 2943 2944 /* all fragments truesize : remove (head size + sk_buff) */ 2945 delta_truesize = skb->truesize - 2946 SKB_TRUESIZE(skb_end_offset(skb)); 2947 2948 skb->truesize -= skb->data_len; 2949 skb->len -= skb->data_len; 2950 skb->data_len = 0; 2951 2952 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE; 2953 goto done; 2954 } else if (skb->head_frag) { 2955 int nr_frags = pinfo->nr_frags; 2956 skb_frag_t *frag = pinfo->frags + nr_frags; 2957 struct page *page = virt_to_head_page(skb->head); 2958 unsigned int first_size = headlen - offset; 2959 unsigned int first_offset; 2960 2961 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS) 2962 return -E2BIG; 2963 2964 first_offset = skb->data - 2965 (unsigned char *)page_address(page) + 2966 offset; 2967 2968 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags; 2969 2970 frag->page.p = page; 2971 frag->page_offset = first_offset; 2972 skb_frag_size_set(frag, first_size); 2973 2974 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags); 2975 /* We dont need to clear skbinfo->nr_frags here */ 2976 2977 delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff)); 2978 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD; 2979 goto done; 2980 } else if (skb_gro_len(p) != pinfo->gso_size) 2981 return -E2BIG; 2982 2983 headroom = skb_headroom(p); 2984 nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC); 2985 if (unlikely(!nskb)) 2986 return -ENOMEM; 2987 2988 __copy_skb_header(nskb, p); 2989 nskb->mac_len = p->mac_len; 2990 2991 skb_reserve(nskb, headroom); 2992 __skb_put(nskb, skb_gro_offset(p)); 2993 2994 skb_set_mac_header(nskb, skb_mac_header(p) - p->data); 2995 skb_set_network_header(nskb, skb_network_offset(p)); 2996 skb_set_transport_header(nskb, skb_transport_offset(p)); 2997 2998 __skb_pull(p, skb_gro_offset(p)); 2999 memcpy(skb_mac_header(nskb), skb_mac_header(p), 3000 p->data - skb_mac_header(p)); 3001 3002 *NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p); 3003 skb_shinfo(nskb)->frag_list = p; 3004 skb_shinfo(nskb)->gso_size = pinfo->gso_size; 3005 pinfo->gso_size = 0; 3006 skb_header_release(p); 3007 nskb->prev = p; 3008 3009 nskb->data_len += p->len; 3010 nskb->truesize += p->truesize; 3011 nskb->len += p->len; 3012 3013 *head = nskb; 3014 nskb->next = p->next; 3015 p->next = NULL; 3016 3017 p = nskb; 3018 3019 merge: 3020 delta_truesize = skb->truesize; 3021 if (offset > headlen) { 3022 unsigned int eat = offset - headlen; 3023 3024 skbinfo->frags[0].page_offset += eat; 3025 skb_frag_size_sub(&skbinfo->frags[0], eat); 3026 skb->data_len -= eat; 3027 skb->len -= eat; 3028 offset = headlen; 3029 } 3030 3031 __skb_pull(skb, offset); 3032 3033 p->prev->next = skb; 3034 p->prev = skb; 3035 skb_header_release(skb); 3036 3037 done: 3038 NAPI_GRO_CB(p)->count++; 3039 p->data_len += len; 3040 p->truesize += delta_truesize; 3041 p->len += len; 3042 3043 NAPI_GRO_CB(skb)->same_flow = 1; 3044 return 0; 3045 } 3046 EXPORT_SYMBOL_GPL(skb_gro_receive); 3047 3048 void __init skb_init(void) 3049 { 3050 skbuff_head_cache = kmem_cache_create("skbuff_head_cache", 3051 sizeof(struct sk_buff), 3052 0, 3053 SLAB_HWCACHE_ALIGN|SLAB_PANIC, 3054 NULL); 3055 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache", 3056 (2*sizeof(struct sk_buff)) + 3057 sizeof(atomic_t), 3058 0, 3059 SLAB_HWCACHE_ALIGN|SLAB_PANIC, 3060 NULL); 3061 } 3062 3063 /** 3064 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer 3065 * @skb: Socket buffer containing the buffers to be mapped 3066 * @sg: The scatter-gather list to map into 3067 * @offset: The offset into the buffer's contents to start mapping 3068 * @len: Length of buffer space to be mapped 3069 * 3070 * Fill the specified scatter-gather list with mappings/pointers into a 3071 * region of the buffer space attached to a socket buffer. 3072 */ 3073 static int 3074 __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) 3075 { 3076 int start = skb_headlen(skb); 3077 int i, copy = start - offset; 3078 struct sk_buff *frag_iter; 3079 int elt = 0; 3080 3081 if (copy > 0) { 3082 if (copy > len) 3083 copy = len; 3084 sg_set_buf(sg, skb->data + offset, copy); 3085 elt++; 3086 if ((len -= copy) == 0) 3087 return elt; 3088 offset += copy; 3089 } 3090 3091 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 3092 int end; 3093 3094 WARN_ON(start > offset + len); 3095 3096 end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]); 3097 if ((copy = end - offset) > 0) { 3098 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 3099 3100 if (copy > len) 3101 copy = len; 3102 sg_set_page(&sg[elt], skb_frag_page(frag), copy, 3103 frag->page_offset+offset-start); 3104 elt++; 3105 if (!(len -= copy)) 3106 return elt; 3107 offset += copy; 3108 } 3109 start = end; 3110 } 3111 3112 skb_walk_frags(skb, frag_iter) { 3113 int end; 3114 3115 WARN_ON(start > offset + len); 3116 3117 end = start + frag_iter->len; 3118 if ((copy = end - offset) > 0) { 3119 if (copy > len) 3120 copy = len; 3121 elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start, 3122 copy); 3123 if ((len -= copy) == 0) 3124 return elt; 3125 offset += copy; 3126 } 3127 start = end; 3128 } 3129 BUG_ON(len); 3130 return elt; 3131 } 3132 3133 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) 3134 { 3135 int nsg = __skb_to_sgvec(skb, sg, offset, len); 3136 3137 sg_mark_end(&sg[nsg - 1]); 3138 3139 return nsg; 3140 } 3141 EXPORT_SYMBOL_GPL(skb_to_sgvec); 3142 3143 /** 3144 * skb_cow_data - Check that a socket buffer's data buffers are writable 3145 * @skb: The socket buffer to check. 3146 * @tailbits: Amount of trailing space to be added 3147 * @trailer: Returned pointer to the skb where the @tailbits space begins 3148 * 3149 * Make sure that the data buffers attached to a socket buffer are 3150 * writable. If they are not, private copies are made of the data buffers 3151 * and the socket buffer is set to use these instead. 3152 * 3153 * If @tailbits is given, make sure that there is space to write @tailbits 3154 * bytes of data beyond current end of socket buffer. @trailer will be 3155 * set to point to the skb in which this space begins. 3156 * 3157 * The number of scatterlist elements required to completely map the 3158 * COW'd and extended socket buffer will be returned. 3159 */ 3160 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer) 3161 { 3162 int copyflag; 3163 int elt; 3164 struct sk_buff *skb1, **skb_p; 3165 3166 /* If skb is cloned or its head is paged, reallocate 3167 * head pulling out all the pages (pages are considered not writable 3168 * at the moment even if they are anonymous). 3169 */ 3170 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) && 3171 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL) 3172 return -ENOMEM; 3173 3174 /* Easy case. Most of packets will go this way. */ 3175 if (!skb_has_frag_list(skb)) { 3176 /* A little of trouble, not enough of space for trailer. 3177 * This should not happen, when stack is tuned to generate 3178 * good frames. OK, on miss we reallocate and reserve even more 3179 * space, 128 bytes is fair. */ 3180 3181 if (skb_tailroom(skb) < tailbits && 3182 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC)) 3183 return -ENOMEM; 3184 3185 /* Voila! */ 3186 *trailer = skb; 3187 return 1; 3188 } 3189 3190 /* Misery. We are in troubles, going to mincer fragments... */ 3191 3192 elt = 1; 3193 skb_p = &skb_shinfo(skb)->frag_list; 3194 copyflag = 0; 3195 3196 while ((skb1 = *skb_p) != NULL) { 3197 int ntail = 0; 3198 3199 /* The fragment is partially pulled by someone, 3200 * this can happen on input. Copy it and everything 3201 * after it. */ 3202 3203 if (skb_shared(skb1)) 3204 copyflag = 1; 3205 3206 /* If the skb is the last, worry about trailer. */ 3207 3208 if (skb1->next == NULL && tailbits) { 3209 if (skb_shinfo(skb1)->nr_frags || 3210 skb_has_frag_list(skb1) || 3211 skb_tailroom(skb1) < tailbits) 3212 ntail = tailbits + 128; 3213 } 3214 3215 if (copyflag || 3216 skb_cloned(skb1) || 3217 ntail || 3218 skb_shinfo(skb1)->nr_frags || 3219 skb_has_frag_list(skb1)) { 3220 struct sk_buff *skb2; 3221 3222 /* Fuck, we are miserable poor guys... */ 3223 if (ntail == 0) 3224 skb2 = skb_copy(skb1, GFP_ATOMIC); 3225 else 3226 skb2 = skb_copy_expand(skb1, 3227 skb_headroom(skb1), 3228 ntail, 3229 GFP_ATOMIC); 3230 if (unlikely(skb2 == NULL)) 3231 return -ENOMEM; 3232 3233 if (skb1->sk) 3234 skb_set_owner_w(skb2, skb1->sk); 3235 3236 /* Looking around. Are we still alive? 3237 * OK, link new skb, drop old one */ 3238 3239 skb2->next = skb1->next; 3240 *skb_p = skb2; 3241 kfree_skb(skb1); 3242 skb1 = skb2; 3243 } 3244 elt++; 3245 *trailer = skb1; 3246 skb_p = &skb1->next; 3247 } 3248 3249 return elt; 3250 } 3251 EXPORT_SYMBOL_GPL(skb_cow_data); 3252 3253 static void sock_rmem_free(struct sk_buff *skb) 3254 { 3255 struct sock *sk = skb->sk; 3256 3257 atomic_sub(skb->truesize, &sk->sk_rmem_alloc); 3258 } 3259 3260 /* 3261 * Note: We dont mem charge error packets (no sk_forward_alloc changes) 3262 */ 3263 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb) 3264 { 3265 int len = skb->len; 3266 3267 if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >= 3268 (unsigned int)sk->sk_rcvbuf) 3269 return -ENOMEM; 3270 3271 skb_orphan(skb); 3272 skb->sk = sk; 3273 skb->destructor = sock_rmem_free; 3274 atomic_add(skb->truesize, &sk->sk_rmem_alloc); 3275 3276 /* before exiting rcu section, make sure dst is refcounted */ 3277 skb_dst_force(skb); 3278 3279 skb_queue_tail(&sk->sk_error_queue, skb); 3280 if (!sock_flag(sk, SOCK_DEAD)) 3281 sk->sk_data_ready(sk, len); 3282 return 0; 3283 } 3284 EXPORT_SYMBOL(sock_queue_err_skb); 3285 3286 void skb_tstamp_tx(struct sk_buff *orig_skb, 3287 struct skb_shared_hwtstamps *hwtstamps) 3288 { 3289 struct sock *sk = orig_skb->sk; 3290 struct sock_exterr_skb *serr; 3291 struct sk_buff *skb; 3292 int err; 3293 3294 if (!sk) 3295 return; 3296 3297 skb = skb_clone(orig_skb, GFP_ATOMIC); 3298 if (!skb) 3299 return; 3300 3301 if (hwtstamps) { 3302 *skb_hwtstamps(skb) = 3303 *hwtstamps; 3304 } else { 3305 /* 3306 * no hardware time stamps available, 3307 * so keep the shared tx_flags and only 3308 * store software time stamp 3309 */ 3310 skb->tstamp = ktime_get_real(); 3311 } 3312 3313 serr = SKB_EXT_ERR(skb); 3314 memset(serr, 0, sizeof(*serr)); 3315 serr->ee.ee_errno = ENOMSG; 3316 serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING; 3317 3318 err = sock_queue_err_skb(sk, skb); 3319 3320 if (err) 3321 kfree_skb(skb); 3322 } 3323 EXPORT_SYMBOL_GPL(skb_tstamp_tx); 3324 3325 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked) 3326 { 3327 struct sock *sk = skb->sk; 3328 struct sock_exterr_skb *serr; 3329 int err; 3330 3331 skb->wifi_acked_valid = 1; 3332 skb->wifi_acked = acked; 3333 3334 serr = SKB_EXT_ERR(skb); 3335 memset(serr, 0, sizeof(*serr)); 3336 serr->ee.ee_errno = ENOMSG; 3337 serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS; 3338 3339 err = sock_queue_err_skb(sk, skb); 3340 if (err) 3341 kfree_skb(skb); 3342 } 3343 EXPORT_SYMBOL_GPL(skb_complete_wifi_ack); 3344 3345 3346 /** 3347 * skb_partial_csum_set - set up and verify partial csum values for packet 3348 * @skb: the skb to set 3349 * @start: the number of bytes after skb->data to start checksumming. 3350 * @off: the offset from start to place the checksum. 3351 * 3352 * For untrusted partially-checksummed packets, we need to make sure the values 3353 * for skb->csum_start and skb->csum_offset are valid so we don't oops. 3354 * 3355 * This function checks and sets those values and skb->ip_summed: if this 3356 * returns false you should drop the packet. 3357 */ 3358 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off) 3359 { 3360 if (unlikely(start > skb_headlen(skb)) || 3361 unlikely((int)start + off > skb_headlen(skb) - 2)) { 3362 net_warn_ratelimited("bad partial csum: csum=%u/%u len=%u\n", 3363 start, off, skb_headlen(skb)); 3364 return false; 3365 } 3366 skb->ip_summed = CHECKSUM_PARTIAL; 3367 skb->csum_start = skb_headroom(skb) + start; 3368 skb->csum_offset = off; 3369 return true; 3370 } 3371 EXPORT_SYMBOL_GPL(skb_partial_csum_set); 3372 3373 void __skb_warn_lro_forwarding(const struct sk_buff *skb) 3374 { 3375 net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n", 3376 skb->dev->name); 3377 } 3378 EXPORT_SYMBOL(__skb_warn_lro_forwarding); 3379 3380 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen) 3381 { 3382 if (head_stolen) { 3383 skb_release_head_state(skb); 3384 kmem_cache_free(skbuff_head_cache, skb); 3385 } else { 3386 __kfree_skb(skb); 3387 } 3388 } 3389 EXPORT_SYMBOL(kfree_skb_partial); 3390 3391 /** 3392 * skb_try_coalesce - try to merge skb to prior one 3393 * @to: prior buffer 3394 * @from: buffer to add 3395 * @fragstolen: pointer to boolean 3396 * @delta_truesize: how much more was allocated than was requested 3397 */ 3398 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, 3399 bool *fragstolen, int *delta_truesize) 3400 { 3401 int i, delta, len = from->len; 3402 3403 *fragstolen = false; 3404 3405 if (skb_cloned(to)) 3406 return false; 3407 3408 if (len <= skb_tailroom(to)) { 3409 BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len)); 3410 *delta_truesize = 0; 3411 return true; 3412 } 3413 3414 if (skb_has_frag_list(to) || skb_has_frag_list(from)) 3415 return false; 3416 3417 if (skb_headlen(from) != 0) { 3418 struct page *page; 3419 unsigned int offset; 3420 3421 if (skb_shinfo(to)->nr_frags + 3422 skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) 3423 return false; 3424 3425 if (skb_head_is_locked(from)) 3426 return false; 3427 3428 delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff)); 3429 3430 page = virt_to_head_page(from->head); 3431 offset = from->data - (unsigned char *)page_address(page); 3432 3433 skb_fill_page_desc(to, skb_shinfo(to)->nr_frags, 3434 page, offset, skb_headlen(from)); 3435 *fragstolen = true; 3436 } else { 3437 if (skb_shinfo(to)->nr_frags + 3438 skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS) 3439 return false; 3440 3441 delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from)); 3442 } 3443 3444 WARN_ON_ONCE(delta < len); 3445 3446 memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags, 3447 skb_shinfo(from)->frags, 3448 skb_shinfo(from)->nr_frags * sizeof(skb_frag_t)); 3449 skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags; 3450 3451 if (!skb_cloned(from)) 3452 skb_shinfo(from)->nr_frags = 0; 3453 3454 /* if the skb is not cloned this does nothing 3455 * since we set nr_frags to 0. 3456 */ 3457 for (i = 0; i < skb_shinfo(from)->nr_frags; i++) 3458 skb_frag_ref(from, i); 3459 3460 to->truesize += delta; 3461 to->len += len; 3462 to->data_len += len; 3463 3464 *delta_truesize = delta; 3465 return true; 3466 } 3467 EXPORT_SYMBOL(skb_try_coalesce); 3468