1 /* 2 * Routines having to do with the 'struct sk_buff' memory handlers. 3 * 4 * Authors: Alan Cox <iiitac@pyr.swan.ac.uk> 5 * Florian La Roche <rzsfl@rz.uni-sb.de> 6 * 7 * Version: $Id: skbuff.c,v 1.90 2001/11/07 05:56:19 davem Exp $ 8 * 9 * Fixes: 10 * Alan Cox : Fixed the worst of the load 11 * balancer bugs. 12 * Dave Platt : Interrupt stacking fix. 13 * Richard Kooijman : Timestamp fixes. 14 * Alan Cox : Changed buffer format. 15 * Alan Cox : destructor hook for AF_UNIX etc. 16 * Linus Torvalds : Better skb_clone. 17 * Alan Cox : Added skb_copy. 18 * Alan Cox : Added all the changed routines Linus 19 * only put in the headers 20 * Ray VanTassle : Fixed --skb->lock in free 21 * Alan Cox : skb_copy copy arp field 22 * Andi Kleen : slabified it. 23 * Robert Olsson : Removed skb_head_pool 24 * 25 * NOTE: 26 * The __skb_ routines should be called with interrupts 27 * disabled, or you better be *real* sure that the operation is atomic 28 * with respect to whatever list is being frobbed (e.g. via lock_sock() 29 * or via disabling bottom half handlers, etc). 30 * 31 * This program is free software; you can redistribute it and/or 32 * modify it under the terms of the GNU General Public License 33 * as published by the Free Software Foundation; either version 34 * 2 of the License, or (at your option) any later version. 35 */ 36 37 /* 38 * The functions in this file will not compile correctly with gcc 2.4.x 39 */ 40 41 #include <linux/module.h> 42 #include <linux/types.h> 43 #include <linux/kernel.h> 44 #include <linux/mm.h> 45 #include <linux/interrupt.h> 46 #include <linux/in.h> 47 #include <linux/inet.h> 48 #include <linux/slab.h> 49 #include <linux/netdevice.h> 50 #ifdef CONFIG_NET_CLS_ACT 51 #include <net/pkt_sched.h> 52 #endif 53 #include <linux/string.h> 54 #include <linux/skbuff.h> 55 #include <linux/cache.h> 56 #include <linux/rtnetlink.h> 57 #include <linux/init.h> 58 #include <linux/scatterlist.h> 59 60 #include <net/protocol.h> 61 #include <net/dst.h> 62 #include <net/sock.h> 63 #include <net/checksum.h> 64 #include <net/xfrm.h> 65 66 #include <asm/uaccess.h> 67 #include <asm/system.h> 68 69 #include "kmap_skb.h" 70 71 static struct kmem_cache *skbuff_head_cache __read_mostly; 72 static struct kmem_cache *skbuff_fclone_cache __read_mostly; 73 74 /* 75 * Keep out-of-line to prevent kernel bloat. 76 * __builtin_return_address is not used because it is not always 77 * reliable. 78 */ 79 80 /** 81 * skb_over_panic - private function 82 * @skb: buffer 83 * @sz: size 84 * @here: address 85 * 86 * Out of line support code for skb_put(). Not user callable. 87 */ 88 void skb_over_panic(struct sk_buff *skb, int sz, void *here) 89 { 90 printk(KERN_EMERG "skb_over_panic: text:%p len:%d put:%d head:%p " 91 "data:%p tail:%#lx end:%#lx dev:%s\n", 92 here, skb->len, sz, skb->head, skb->data, 93 (unsigned long)skb->tail, (unsigned long)skb->end, 94 skb->dev ? skb->dev->name : "<NULL>"); 95 BUG(); 96 } 97 98 /** 99 * skb_under_panic - private function 100 * @skb: buffer 101 * @sz: size 102 * @here: address 103 * 104 * Out of line support code for skb_push(). Not user callable. 105 */ 106 107 void skb_under_panic(struct sk_buff *skb, int sz, void *here) 108 { 109 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p " 110 "data:%p tail:%#lx end:%#lx dev:%s\n", 111 here, skb->len, sz, skb->head, skb->data, 112 (unsigned long)skb->tail, (unsigned long)skb->end, 113 skb->dev ? skb->dev->name : "<NULL>"); 114 BUG(); 115 } 116 117 void skb_truesize_bug(struct sk_buff *skb) 118 { 119 printk(KERN_ERR "SKB BUG: Invalid truesize (%u) " 120 "len=%u, sizeof(sk_buff)=%Zd\n", 121 skb->truesize, skb->len, sizeof(struct sk_buff)); 122 } 123 EXPORT_SYMBOL(skb_truesize_bug); 124 125 /* Allocate a new skbuff. We do this ourselves so we can fill in a few 126 * 'private' fields and also do memory statistics to find all the 127 * [BEEP] leaks. 128 * 129 */ 130 131 /** 132 * __alloc_skb - allocate a network buffer 133 * @size: size to allocate 134 * @gfp_mask: allocation mask 135 * @fclone: allocate from fclone cache instead of head cache 136 * and allocate a cloned (child) skb 137 * @node: numa node to allocate memory on 138 * 139 * Allocate a new &sk_buff. The returned buffer has no headroom and a 140 * tail room of size bytes. The object has a reference count of one. 141 * The return is the buffer. On a failure the return is %NULL. 142 * 143 * Buffers may only be allocated from interrupts using a @gfp_mask of 144 * %GFP_ATOMIC. 145 */ 146 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, 147 int fclone, int node) 148 { 149 struct kmem_cache *cache; 150 struct skb_shared_info *shinfo; 151 struct sk_buff *skb; 152 u8 *data; 153 154 cache = fclone ? skbuff_fclone_cache : skbuff_head_cache; 155 156 /* Get the HEAD */ 157 skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node); 158 if (!skb) 159 goto out; 160 161 size = SKB_DATA_ALIGN(size); 162 data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info), 163 gfp_mask, node); 164 if (!data) 165 goto nodata; 166 167 /* 168 * See comment in sk_buff definition, just before the 'tail' member 169 */ 170 memset(skb, 0, offsetof(struct sk_buff, tail)); 171 skb->truesize = size + sizeof(struct sk_buff); 172 atomic_set(&skb->users, 1); 173 skb->head = data; 174 skb->data = data; 175 skb_reset_tail_pointer(skb); 176 skb->end = skb->tail + size; 177 /* make sure we initialize shinfo sequentially */ 178 shinfo = skb_shinfo(skb); 179 atomic_set(&shinfo->dataref, 1); 180 shinfo->nr_frags = 0; 181 shinfo->gso_size = 0; 182 shinfo->gso_segs = 0; 183 shinfo->gso_type = 0; 184 shinfo->ip6_frag_id = 0; 185 shinfo->frag_list = NULL; 186 187 if (fclone) { 188 struct sk_buff *child = skb + 1; 189 atomic_t *fclone_ref = (atomic_t *) (child + 1); 190 191 skb->fclone = SKB_FCLONE_ORIG; 192 atomic_set(fclone_ref, 1); 193 194 child->fclone = SKB_FCLONE_UNAVAILABLE; 195 } 196 out: 197 return skb; 198 nodata: 199 kmem_cache_free(cache, skb); 200 skb = NULL; 201 goto out; 202 } 203 204 /** 205 * __netdev_alloc_skb - allocate an skbuff for rx on a specific device 206 * @dev: network device to receive on 207 * @length: length to allocate 208 * @gfp_mask: get_free_pages mask, passed to alloc_skb 209 * 210 * Allocate a new &sk_buff and assign it a usage count of one. The 211 * buffer has unspecified headroom built in. Users should allocate 212 * the headroom they think they need without accounting for the 213 * built in space. The built in space is used for optimisations. 214 * 215 * %NULL is returned if there is no free memory. 216 */ 217 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, 218 unsigned int length, gfp_t gfp_mask) 219 { 220 int node = dev->dev.parent ? dev_to_node(dev->dev.parent) : -1; 221 struct sk_buff *skb; 222 223 skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, node); 224 if (likely(skb)) { 225 skb_reserve(skb, NET_SKB_PAD); 226 skb->dev = dev; 227 } 228 return skb; 229 } 230 231 static void skb_drop_list(struct sk_buff **listp) 232 { 233 struct sk_buff *list = *listp; 234 235 *listp = NULL; 236 237 do { 238 struct sk_buff *this = list; 239 list = list->next; 240 kfree_skb(this); 241 } while (list); 242 } 243 244 static inline void skb_drop_fraglist(struct sk_buff *skb) 245 { 246 skb_drop_list(&skb_shinfo(skb)->frag_list); 247 } 248 249 static void skb_clone_fraglist(struct sk_buff *skb) 250 { 251 struct sk_buff *list; 252 253 for (list = skb_shinfo(skb)->frag_list; list; list = list->next) 254 skb_get(list); 255 } 256 257 static void skb_release_data(struct sk_buff *skb) 258 { 259 if (!skb->cloned || 260 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1, 261 &skb_shinfo(skb)->dataref)) { 262 if (skb_shinfo(skb)->nr_frags) { 263 int i; 264 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 265 put_page(skb_shinfo(skb)->frags[i].page); 266 } 267 268 if (skb_shinfo(skb)->frag_list) 269 skb_drop_fraglist(skb); 270 271 kfree(skb->head); 272 } 273 } 274 275 /* 276 * Free an skbuff by memory without cleaning the state. 277 */ 278 void kfree_skbmem(struct sk_buff *skb) 279 { 280 struct sk_buff *other; 281 atomic_t *fclone_ref; 282 283 skb_release_data(skb); 284 switch (skb->fclone) { 285 case SKB_FCLONE_UNAVAILABLE: 286 kmem_cache_free(skbuff_head_cache, skb); 287 break; 288 289 case SKB_FCLONE_ORIG: 290 fclone_ref = (atomic_t *) (skb + 2); 291 if (atomic_dec_and_test(fclone_ref)) 292 kmem_cache_free(skbuff_fclone_cache, skb); 293 break; 294 295 case SKB_FCLONE_CLONE: 296 fclone_ref = (atomic_t *) (skb + 1); 297 other = skb - 1; 298 299 /* The clone portion is available for 300 * fast-cloning again. 301 */ 302 skb->fclone = SKB_FCLONE_UNAVAILABLE; 303 304 if (atomic_dec_and_test(fclone_ref)) 305 kmem_cache_free(skbuff_fclone_cache, other); 306 break; 307 } 308 } 309 310 /** 311 * __kfree_skb - private function 312 * @skb: buffer 313 * 314 * Free an sk_buff. Release anything attached to the buffer. 315 * Clean the state. This is an internal helper function. Users should 316 * always call kfree_skb 317 */ 318 319 void __kfree_skb(struct sk_buff *skb) 320 { 321 dst_release(skb->dst); 322 #ifdef CONFIG_XFRM 323 secpath_put(skb->sp); 324 #endif 325 if (skb->destructor) { 326 WARN_ON(in_irq()); 327 skb->destructor(skb); 328 } 329 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) 330 nf_conntrack_put(skb->nfct); 331 nf_conntrack_put_reasm(skb->nfct_reasm); 332 #endif 333 #ifdef CONFIG_BRIDGE_NETFILTER 334 nf_bridge_put(skb->nf_bridge); 335 #endif 336 /* XXX: IS this still necessary? - JHS */ 337 #ifdef CONFIG_NET_SCHED 338 skb->tc_index = 0; 339 #ifdef CONFIG_NET_CLS_ACT 340 skb->tc_verd = 0; 341 #endif 342 #endif 343 344 kfree_skbmem(skb); 345 } 346 347 /** 348 * kfree_skb - free an sk_buff 349 * @skb: buffer to free 350 * 351 * Drop a reference to the buffer and free it if the usage count has 352 * hit zero. 353 */ 354 void kfree_skb(struct sk_buff *skb) 355 { 356 if (unlikely(!skb)) 357 return; 358 if (likely(atomic_read(&skb->users) == 1)) 359 smp_rmb(); 360 else if (likely(!atomic_dec_and_test(&skb->users))) 361 return; 362 __kfree_skb(skb); 363 } 364 365 /** 366 * skb_clone - duplicate an sk_buff 367 * @skb: buffer to clone 368 * @gfp_mask: allocation priority 369 * 370 * Duplicate an &sk_buff. The new one is not owned by a socket. Both 371 * copies share the same packet data but not structure. The new 372 * buffer has a reference count of 1. If the allocation fails the 373 * function returns %NULL otherwise the new buffer is returned. 374 * 375 * If this function is called from an interrupt gfp_mask() must be 376 * %GFP_ATOMIC. 377 */ 378 379 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 380 { 381 struct sk_buff *n; 382 383 n = skb + 1; 384 if (skb->fclone == SKB_FCLONE_ORIG && 385 n->fclone == SKB_FCLONE_UNAVAILABLE) { 386 atomic_t *fclone_ref = (atomic_t *) (n + 1); 387 n->fclone = SKB_FCLONE_CLONE; 388 atomic_inc(fclone_ref); 389 } else { 390 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask); 391 if (!n) 392 return NULL; 393 n->fclone = SKB_FCLONE_UNAVAILABLE; 394 } 395 396 #define C(x) n->x = skb->x 397 398 n->next = n->prev = NULL; 399 n->sk = NULL; 400 C(tstamp); 401 C(dev); 402 C(transport_header); 403 C(network_header); 404 C(mac_header); 405 C(dst); 406 dst_clone(skb->dst); 407 C(sp); 408 #ifdef CONFIG_INET 409 secpath_get(skb->sp); 410 #endif 411 memcpy(n->cb, skb->cb, sizeof(skb->cb)); 412 C(len); 413 C(data_len); 414 C(mac_len); 415 C(csum); 416 C(local_df); 417 n->cloned = 1; 418 n->nohdr = 0; 419 C(pkt_type); 420 C(ip_summed); 421 C(priority); 422 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 423 C(ipvs_property); 424 #endif 425 C(protocol); 426 n->destructor = NULL; 427 C(mark); 428 __nf_copy(n, skb); 429 #ifdef CONFIG_NET_SCHED 430 C(tc_index); 431 #ifdef CONFIG_NET_CLS_ACT 432 n->tc_verd = SET_TC_VERD(skb->tc_verd,0); 433 n->tc_verd = CLR_TC_OK2MUNGE(n->tc_verd); 434 n->tc_verd = CLR_TC_MUNGED(n->tc_verd); 435 C(iif); 436 #endif 437 skb_copy_secmark(n, skb); 438 #endif 439 C(truesize); 440 atomic_set(&n->users, 1); 441 C(head); 442 C(data); 443 C(tail); 444 C(end); 445 446 atomic_inc(&(skb_shinfo(skb)->dataref)); 447 skb->cloned = 1; 448 449 return n; 450 } 451 452 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old) 453 { 454 #ifndef NET_SKBUFF_DATA_USES_OFFSET 455 /* 456 * Shift between the two data areas in bytes 457 */ 458 unsigned long offset = new->data - old->data; 459 #endif 460 new->sk = NULL; 461 new->dev = old->dev; 462 new->priority = old->priority; 463 new->protocol = old->protocol; 464 new->dst = dst_clone(old->dst); 465 #ifdef CONFIG_INET 466 new->sp = secpath_get(old->sp); 467 #endif 468 new->transport_header = old->transport_header; 469 new->network_header = old->network_header; 470 new->mac_header = old->mac_header; 471 #ifndef NET_SKBUFF_DATA_USES_OFFSET 472 /* {transport,network,mac}_header are relative to skb->head */ 473 new->transport_header += offset; 474 new->network_header += offset; 475 new->mac_header += offset; 476 #endif 477 memcpy(new->cb, old->cb, sizeof(old->cb)); 478 new->local_df = old->local_df; 479 new->fclone = SKB_FCLONE_UNAVAILABLE; 480 new->pkt_type = old->pkt_type; 481 new->tstamp = old->tstamp; 482 new->destructor = NULL; 483 new->mark = old->mark; 484 __nf_copy(new, old); 485 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 486 new->ipvs_property = old->ipvs_property; 487 #endif 488 #ifdef CONFIG_NET_SCHED 489 #ifdef CONFIG_NET_CLS_ACT 490 new->tc_verd = old->tc_verd; 491 #endif 492 new->tc_index = old->tc_index; 493 #endif 494 skb_copy_secmark(new, old); 495 atomic_set(&new->users, 1); 496 skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size; 497 skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs; 498 skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type; 499 } 500 501 /** 502 * skb_copy - create private copy of an sk_buff 503 * @skb: buffer to copy 504 * @gfp_mask: allocation priority 505 * 506 * Make a copy of both an &sk_buff and its data. This is used when the 507 * caller wishes to modify the data and needs a private copy of the 508 * data to alter. Returns %NULL on failure or the pointer to the buffer 509 * on success. The returned buffer has a reference count of 1. 510 * 511 * As by-product this function converts non-linear &sk_buff to linear 512 * one, so that &sk_buff becomes completely private and caller is allowed 513 * to modify all the data of returned buffer. This means that this 514 * function is not recommended for use in circumstances when only 515 * header is going to be modified. Use pskb_copy() instead. 516 */ 517 518 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask) 519 { 520 int headerlen = skb->data - skb->head; 521 /* 522 * Allocate the copy buffer 523 */ 524 struct sk_buff *n; 525 #ifdef NET_SKBUFF_DATA_USES_OFFSET 526 n = alloc_skb(skb->end + skb->data_len, gfp_mask); 527 #else 528 n = alloc_skb(skb->end - skb->head + skb->data_len, gfp_mask); 529 #endif 530 if (!n) 531 return NULL; 532 533 /* Set the data pointer */ 534 skb_reserve(n, headerlen); 535 /* Set the tail pointer and length */ 536 skb_put(n, skb->len); 537 n->csum = skb->csum; 538 n->ip_summed = skb->ip_summed; 539 540 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len)) 541 BUG(); 542 543 copy_skb_header(n, skb); 544 return n; 545 } 546 547 548 /** 549 * pskb_copy - create copy of an sk_buff with private head. 550 * @skb: buffer to copy 551 * @gfp_mask: allocation priority 552 * 553 * Make a copy of both an &sk_buff and part of its data, located 554 * in header. Fragmented data remain shared. This is used when 555 * the caller wishes to modify only header of &sk_buff and needs 556 * private copy of the header to alter. Returns %NULL on failure 557 * or the pointer to the buffer on success. 558 * The returned buffer has a reference count of 1. 559 */ 560 561 struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask) 562 { 563 /* 564 * Allocate the copy buffer 565 */ 566 struct sk_buff *n; 567 #ifdef NET_SKBUFF_DATA_USES_OFFSET 568 n = alloc_skb(skb->end, gfp_mask); 569 #else 570 n = alloc_skb(skb->end - skb->head, gfp_mask); 571 #endif 572 if (!n) 573 goto out; 574 575 /* Set the data pointer */ 576 skb_reserve(n, skb->data - skb->head); 577 /* Set the tail pointer and length */ 578 skb_put(n, skb_headlen(skb)); 579 /* Copy the bytes */ 580 skb_copy_from_linear_data(skb, n->data, n->len); 581 n->csum = skb->csum; 582 n->ip_summed = skb->ip_summed; 583 584 n->truesize += skb->data_len; 585 n->data_len = skb->data_len; 586 n->len = skb->len; 587 588 if (skb_shinfo(skb)->nr_frags) { 589 int i; 590 591 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 592 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i]; 593 get_page(skb_shinfo(n)->frags[i].page); 594 } 595 skb_shinfo(n)->nr_frags = i; 596 } 597 598 if (skb_shinfo(skb)->frag_list) { 599 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list; 600 skb_clone_fraglist(n); 601 } 602 603 copy_skb_header(n, skb); 604 out: 605 return n; 606 } 607 608 /** 609 * pskb_expand_head - reallocate header of &sk_buff 610 * @skb: buffer to reallocate 611 * @nhead: room to add at head 612 * @ntail: room to add at tail 613 * @gfp_mask: allocation priority 614 * 615 * Expands (or creates identical copy, if &nhead and &ntail are zero) 616 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have 617 * reference count of 1. Returns zero in the case of success or error, 618 * if expansion failed. In the last case, &sk_buff is not changed. 619 * 620 * All the pointers pointing into skb header may change and must be 621 * reloaded after call to this function. 622 */ 623 624 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, 625 gfp_t gfp_mask) 626 { 627 int i; 628 u8 *data; 629 #ifdef NET_SKBUFF_DATA_USES_OFFSET 630 int size = nhead + skb->end + ntail; 631 #else 632 int size = nhead + (skb->end - skb->head) + ntail; 633 #endif 634 long off; 635 636 if (skb_shared(skb)) 637 BUG(); 638 639 size = SKB_DATA_ALIGN(size); 640 641 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask); 642 if (!data) 643 goto nodata; 644 645 /* Copy only real data... and, alas, header. This should be 646 * optimized for the cases when header is void. */ 647 memcpy(data + nhead, skb->head, 648 #ifdef NET_SKBUFF_DATA_USES_OFFSET 649 skb->tail); 650 #else 651 skb->tail - skb->head); 652 #endif 653 memcpy(data + size, skb_end_pointer(skb), 654 sizeof(struct skb_shared_info)); 655 656 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 657 get_page(skb_shinfo(skb)->frags[i].page); 658 659 if (skb_shinfo(skb)->frag_list) 660 skb_clone_fraglist(skb); 661 662 skb_release_data(skb); 663 664 off = (data + nhead) - skb->head; 665 666 skb->head = data; 667 skb->data += off; 668 #ifdef NET_SKBUFF_DATA_USES_OFFSET 669 skb->end = size; 670 off = nhead; 671 #else 672 skb->end = skb->head + size; 673 #endif 674 /* {transport,network,mac}_header and tail are relative to skb->head */ 675 skb->tail += off; 676 skb->transport_header += off; 677 skb->network_header += off; 678 skb->mac_header += off; 679 skb->cloned = 0; 680 skb->nohdr = 0; 681 atomic_set(&skb_shinfo(skb)->dataref, 1); 682 return 0; 683 684 nodata: 685 return -ENOMEM; 686 } 687 688 /* Make private copy of skb with writable head and some headroom */ 689 690 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom) 691 { 692 struct sk_buff *skb2; 693 int delta = headroom - skb_headroom(skb); 694 695 if (delta <= 0) 696 skb2 = pskb_copy(skb, GFP_ATOMIC); 697 else { 698 skb2 = skb_clone(skb, GFP_ATOMIC); 699 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0, 700 GFP_ATOMIC)) { 701 kfree_skb(skb2); 702 skb2 = NULL; 703 } 704 } 705 return skb2; 706 } 707 708 709 /** 710 * skb_copy_expand - copy and expand sk_buff 711 * @skb: buffer to copy 712 * @newheadroom: new free bytes at head 713 * @newtailroom: new free bytes at tail 714 * @gfp_mask: allocation priority 715 * 716 * Make a copy of both an &sk_buff and its data and while doing so 717 * allocate additional space. 718 * 719 * This is used when the caller wishes to modify the data and needs a 720 * private copy of the data to alter as well as more space for new fields. 721 * Returns %NULL on failure or the pointer to the buffer 722 * on success. The returned buffer has a reference count of 1. 723 * 724 * You must pass %GFP_ATOMIC as the allocation priority if this function 725 * is called from an interrupt. 726 * 727 * BUG ALERT: ip_summed is not copied. Why does this work? Is it used 728 * only by netfilter in the cases when checksum is recalculated? --ANK 729 */ 730 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, 731 int newheadroom, int newtailroom, 732 gfp_t gfp_mask) 733 { 734 /* 735 * Allocate the copy buffer 736 */ 737 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom, 738 gfp_mask); 739 int oldheadroom = skb_headroom(skb); 740 int head_copy_len, head_copy_off; 741 int off = 0; 742 743 if (!n) 744 return NULL; 745 746 skb_reserve(n, newheadroom); 747 748 /* Set the tail pointer and length */ 749 skb_put(n, skb->len); 750 751 head_copy_len = oldheadroom; 752 head_copy_off = 0; 753 if (newheadroom <= head_copy_len) 754 head_copy_len = newheadroom; 755 else 756 head_copy_off = newheadroom - head_copy_len; 757 758 /* Copy the linear header and data. */ 759 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off, 760 skb->len + head_copy_len)) 761 BUG(); 762 763 copy_skb_header(n, skb); 764 765 #ifdef NET_SKBUFF_DATA_USES_OFFSET 766 off = newheadroom - oldheadroom; 767 #endif 768 n->transport_header += off; 769 n->network_header += off; 770 n->mac_header += off; 771 772 return n; 773 } 774 775 /** 776 * skb_pad - zero pad the tail of an skb 777 * @skb: buffer to pad 778 * @pad: space to pad 779 * 780 * Ensure that a buffer is followed by a padding area that is zero 781 * filled. Used by network drivers which may DMA or transfer data 782 * beyond the buffer end onto the wire. 783 * 784 * May return error in out of memory cases. The skb is freed on error. 785 */ 786 787 int skb_pad(struct sk_buff *skb, int pad) 788 { 789 int err; 790 int ntail; 791 792 /* If the skbuff is non linear tailroom is always zero.. */ 793 if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) { 794 memset(skb->data+skb->len, 0, pad); 795 return 0; 796 } 797 798 ntail = skb->data_len + pad - (skb->end - skb->tail); 799 if (likely(skb_cloned(skb) || ntail > 0)) { 800 err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC); 801 if (unlikely(err)) 802 goto free_skb; 803 } 804 805 /* FIXME: The use of this function with non-linear skb's really needs 806 * to be audited. 807 */ 808 err = skb_linearize(skb); 809 if (unlikely(err)) 810 goto free_skb; 811 812 memset(skb->data + skb->len, 0, pad); 813 return 0; 814 815 free_skb: 816 kfree_skb(skb); 817 return err; 818 } 819 820 /* Trims skb to length len. It can change skb pointers. 821 */ 822 823 int ___pskb_trim(struct sk_buff *skb, unsigned int len) 824 { 825 struct sk_buff **fragp; 826 struct sk_buff *frag; 827 int offset = skb_headlen(skb); 828 int nfrags = skb_shinfo(skb)->nr_frags; 829 int i; 830 int err; 831 832 if (skb_cloned(skb) && 833 unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))) 834 return err; 835 836 i = 0; 837 if (offset >= len) 838 goto drop_pages; 839 840 for (; i < nfrags; i++) { 841 int end = offset + skb_shinfo(skb)->frags[i].size; 842 843 if (end < len) { 844 offset = end; 845 continue; 846 } 847 848 skb_shinfo(skb)->frags[i++].size = len - offset; 849 850 drop_pages: 851 skb_shinfo(skb)->nr_frags = i; 852 853 for (; i < nfrags; i++) 854 put_page(skb_shinfo(skb)->frags[i].page); 855 856 if (skb_shinfo(skb)->frag_list) 857 skb_drop_fraglist(skb); 858 goto done; 859 } 860 861 for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp); 862 fragp = &frag->next) { 863 int end = offset + frag->len; 864 865 if (skb_shared(frag)) { 866 struct sk_buff *nfrag; 867 868 nfrag = skb_clone(frag, GFP_ATOMIC); 869 if (unlikely(!nfrag)) 870 return -ENOMEM; 871 872 nfrag->next = frag->next; 873 kfree_skb(frag); 874 frag = nfrag; 875 *fragp = frag; 876 } 877 878 if (end < len) { 879 offset = end; 880 continue; 881 } 882 883 if (end > len && 884 unlikely((err = pskb_trim(frag, len - offset)))) 885 return err; 886 887 if (frag->next) 888 skb_drop_list(&frag->next); 889 break; 890 } 891 892 done: 893 if (len > skb_headlen(skb)) { 894 skb->data_len -= skb->len - len; 895 skb->len = len; 896 } else { 897 skb->len = len; 898 skb->data_len = 0; 899 skb_set_tail_pointer(skb, len); 900 } 901 902 return 0; 903 } 904 905 /** 906 * __pskb_pull_tail - advance tail of skb header 907 * @skb: buffer to reallocate 908 * @delta: number of bytes to advance tail 909 * 910 * The function makes a sense only on a fragmented &sk_buff, 911 * it expands header moving its tail forward and copying necessary 912 * data from fragmented part. 913 * 914 * &sk_buff MUST have reference count of 1. 915 * 916 * Returns %NULL (and &sk_buff does not change) if pull failed 917 * or value of new tail of skb in the case of success. 918 * 919 * All the pointers pointing into skb header may change and must be 920 * reloaded after call to this function. 921 */ 922 923 /* Moves tail of skb head forward, copying data from fragmented part, 924 * when it is necessary. 925 * 1. It may fail due to malloc failure. 926 * 2. It may change skb pointers. 927 * 928 * It is pretty complicated. Luckily, it is called only in exceptional cases. 929 */ 930 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta) 931 { 932 /* If skb has not enough free space at tail, get new one 933 * plus 128 bytes for future expansions. If we have enough 934 * room at tail, reallocate without expansion only if skb is cloned. 935 */ 936 int i, k, eat = (skb->tail + delta) - skb->end; 937 938 if (eat > 0 || skb_cloned(skb)) { 939 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0, 940 GFP_ATOMIC)) 941 return NULL; 942 } 943 944 if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta)) 945 BUG(); 946 947 /* Optimization: no fragments, no reasons to preestimate 948 * size of pulled pages. Superb. 949 */ 950 if (!skb_shinfo(skb)->frag_list) 951 goto pull_pages; 952 953 /* Estimate size of pulled pages. */ 954 eat = delta; 955 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 956 if (skb_shinfo(skb)->frags[i].size >= eat) 957 goto pull_pages; 958 eat -= skb_shinfo(skb)->frags[i].size; 959 } 960 961 /* If we need update frag list, we are in troubles. 962 * Certainly, it possible to add an offset to skb data, 963 * but taking into account that pulling is expected to 964 * be very rare operation, it is worth to fight against 965 * further bloating skb head and crucify ourselves here instead. 966 * Pure masohism, indeed. 8)8) 967 */ 968 if (eat) { 969 struct sk_buff *list = skb_shinfo(skb)->frag_list; 970 struct sk_buff *clone = NULL; 971 struct sk_buff *insp = NULL; 972 973 do { 974 BUG_ON(!list); 975 976 if (list->len <= eat) { 977 /* Eaten as whole. */ 978 eat -= list->len; 979 list = list->next; 980 insp = list; 981 } else { 982 /* Eaten partially. */ 983 984 if (skb_shared(list)) { 985 /* Sucks! We need to fork list. :-( */ 986 clone = skb_clone(list, GFP_ATOMIC); 987 if (!clone) 988 return NULL; 989 insp = list->next; 990 list = clone; 991 } else { 992 /* This may be pulled without 993 * problems. */ 994 insp = list; 995 } 996 if (!pskb_pull(list, eat)) { 997 if (clone) 998 kfree_skb(clone); 999 return NULL; 1000 } 1001 break; 1002 } 1003 } while (eat); 1004 1005 /* Free pulled out fragments. */ 1006 while ((list = skb_shinfo(skb)->frag_list) != insp) { 1007 skb_shinfo(skb)->frag_list = list->next; 1008 kfree_skb(list); 1009 } 1010 /* And insert new clone at head. */ 1011 if (clone) { 1012 clone->next = list; 1013 skb_shinfo(skb)->frag_list = clone; 1014 } 1015 } 1016 /* Success! Now we may commit changes to skb data. */ 1017 1018 pull_pages: 1019 eat = delta; 1020 k = 0; 1021 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1022 if (skb_shinfo(skb)->frags[i].size <= eat) { 1023 put_page(skb_shinfo(skb)->frags[i].page); 1024 eat -= skb_shinfo(skb)->frags[i].size; 1025 } else { 1026 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; 1027 if (eat) { 1028 skb_shinfo(skb)->frags[k].page_offset += eat; 1029 skb_shinfo(skb)->frags[k].size -= eat; 1030 eat = 0; 1031 } 1032 k++; 1033 } 1034 } 1035 skb_shinfo(skb)->nr_frags = k; 1036 1037 skb->tail += delta; 1038 skb->data_len -= delta; 1039 1040 return skb_tail_pointer(skb); 1041 } 1042 1043 /* Copy some data bits from skb to kernel buffer. */ 1044 1045 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) 1046 { 1047 int i, copy; 1048 int start = skb_headlen(skb); 1049 1050 if (offset > (int)skb->len - len) 1051 goto fault; 1052 1053 /* Copy header. */ 1054 if ((copy = start - offset) > 0) { 1055 if (copy > len) 1056 copy = len; 1057 skb_copy_from_linear_data_offset(skb, offset, to, copy); 1058 if ((len -= copy) == 0) 1059 return 0; 1060 offset += copy; 1061 to += copy; 1062 } 1063 1064 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1065 int end; 1066 1067 BUG_TRAP(start <= offset + len); 1068 1069 end = start + skb_shinfo(skb)->frags[i].size; 1070 if ((copy = end - offset) > 0) { 1071 u8 *vaddr; 1072 1073 if (copy > len) 1074 copy = len; 1075 1076 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]); 1077 memcpy(to, 1078 vaddr + skb_shinfo(skb)->frags[i].page_offset+ 1079 offset - start, copy); 1080 kunmap_skb_frag(vaddr); 1081 1082 if ((len -= copy) == 0) 1083 return 0; 1084 offset += copy; 1085 to += copy; 1086 } 1087 start = end; 1088 } 1089 1090 if (skb_shinfo(skb)->frag_list) { 1091 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1092 1093 for (; list; list = list->next) { 1094 int end; 1095 1096 BUG_TRAP(start <= offset + len); 1097 1098 end = start + list->len; 1099 if ((copy = end - offset) > 0) { 1100 if (copy > len) 1101 copy = len; 1102 if (skb_copy_bits(list, offset - start, 1103 to, copy)) 1104 goto fault; 1105 if ((len -= copy) == 0) 1106 return 0; 1107 offset += copy; 1108 to += copy; 1109 } 1110 start = end; 1111 } 1112 } 1113 if (!len) 1114 return 0; 1115 1116 fault: 1117 return -EFAULT; 1118 } 1119 1120 /** 1121 * skb_store_bits - store bits from kernel buffer to skb 1122 * @skb: destination buffer 1123 * @offset: offset in destination 1124 * @from: source buffer 1125 * @len: number of bytes to copy 1126 * 1127 * Copy the specified number of bytes from the source buffer to the 1128 * destination skb. This function handles all the messy bits of 1129 * traversing fragment lists and such. 1130 */ 1131 1132 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len) 1133 { 1134 int i, copy; 1135 int start = skb_headlen(skb); 1136 1137 if (offset > (int)skb->len - len) 1138 goto fault; 1139 1140 if ((copy = start - offset) > 0) { 1141 if (copy > len) 1142 copy = len; 1143 skb_copy_to_linear_data_offset(skb, offset, from, copy); 1144 if ((len -= copy) == 0) 1145 return 0; 1146 offset += copy; 1147 from += copy; 1148 } 1149 1150 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1151 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 1152 int end; 1153 1154 BUG_TRAP(start <= offset + len); 1155 1156 end = start + frag->size; 1157 if ((copy = end - offset) > 0) { 1158 u8 *vaddr; 1159 1160 if (copy > len) 1161 copy = len; 1162 1163 vaddr = kmap_skb_frag(frag); 1164 memcpy(vaddr + frag->page_offset + offset - start, 1165 from, copy); 1166 kunmap_skb_frag(vaddr); 1167 1168 if ((len -= copy) == 0) 1169 return 0; 1170 offset += copy; 1171 from += copy; 1172 } 1173 start = end; 1174 } 1175 1176 if (skb_shinfo(skb)->frag_list) { 1177 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1178 1179 for (; list; list = list->next) { 1180 int end; 1181 1182 BUG_TRAP(start <= offset + len); 1183 1184 end = start + list->len; 1185 if ((copy = end - offset) > 0) { 1186 if (copy > len) 1187 copy = len; 1188 if (skb_store_bits(list, offset - start, 1189 from, copy)) 1190 goto fault; 1191 if ((len -= copy) == 0) 1192 return 0; 1193 offset += copy; 1194 from += copy; 1195 } 1196 start = end; 1197 } 1198 } 1199 if (!len) 1200 return 0; 1201 1202 fault: 1203 return -EFAULT; 1204 } 1205 1206 EXPORT_SYMBOL(skb_store_bits); 1207 1208 /* Checksum skb data. */ 1209 1210 __wsum skb_checksum(const struct sk_buff *skb, int offset, 1211 int len, __wsum csum) 1212 { 1213 int start = skb_headlen(skb); 1214 int i, copy = start - offset; 1215 int pos = 0; 1216 1217 /* Checksum header. */ 1218 if (copy > 0) { 1219 if (copy > len) 1220 copy = len; 1221 csum = csum_partial(skb->data + offset, copy, csum); 1222 if ((len -= copy) == 0) 1223 return csum; 1224 offset += copy; 1225 pos = copy; 1226 } 1227 1228 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1229 int end; 1230 1231 BUG_TRAP(start <= offset + len); 1232 1233 end = start + skb_shinfo(skb)->frags[i].size; 1234 if ((copy = end - offset) > 0) { 1235 __wsum csum2; 1236 u8 *vaddr; 1237 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 1238 1239 if (copy > len) 1240 copy = len; 1241 vaddr = kmap_skb_frag(frag); 1242 csum2 = csum_partial(vaddr + frag->page_offset + 1243 offset - start, copy, 0); 1244 kunmap_skb_frag(vaddr); 1245 csum = csum_block_add(csum, csum2, pos); 1246 if (!(len -= copy)) 1247 return csum; 1248 offset += copy; 1249 pos += copy; 1250 } 1251 start = end; 1252 } 1253 1254 if (skb_shinfo(skb)->frag_list) { 1255 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1256 1257 for (; list; list = list->next) { 1258 int end; 1259 1260 BUG_TRAP(start <= offset + len); 1261 1262 end = start + list->len; 1263 if ((copy = end - offset) > 0) { 1264 __wsum csum2; 1265 if (copy > len) 1266 copy = len; 1267 csum2 = skb_checksum(list, offset - start, 1268 copy, 0); 1269 csum = csum_block_add(csum, csum2, pos); 1270 if ((len -= copy) == 0) 1271 return csum; 1272 offset += copy; 1273 pos += copy; 1274 } 1275 start = end; 1276 } 1277 } 1278 BUG_ON(len); 1279 1280 return csum; 1281 } 1282 1283 /* Both of above in one bottle. */ 1284 1285 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, 1286 u8 *to, int len, __wsum csum) 1287 { 1288 int start = skb_headlen(skb); 1289 int i, copy = start - offset; 1290 int pos = 0; 1291 1292 /* Copy header. */ 1293 if (copy > 0) { 1294 if (copy > len) 1295 copy = len; 1296 csum = csum_partial_copy_nocheck(skb->data + offset, to, 1297 copy, csum); 1298 if ((len -= copy) == 0) 1299 return csum; 1300 offset += copy; 1301 to += copy; 1302 pos = copy; 1303 } 1304 1305 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1306 int end; 1307 1308 BUG_TRAP(start <= offset + len); 1309 1310 end = start + skb_shinfo(skb)->frags[i].size; 1311 if ((copy = end - offset) > 0) { 1312 __wsum csum2; 1313 u8 *vaddr; 1314 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 1315 1316 if (copy > len) 1317 copy = len; 1318 vaddr = kmap_skb_frag(frag); 1319 csum2 = csum_partial_copy_nocheck(vaddr + 1320 frag->page_offset + 1321 offset - start, to, 1322 copy, 0); 1323 kunmap_skb_frag(vaddr); 1324 csum = csum_block_add(csum, csum2, pos); 1325 if (!(len -= copy)) 1326 return csum; 1327 offset += copy; 1328 to += copy; 1329 pos += copy; 1330 } 1331 start = end; 1332 } 1333 1334 if (skb_shinfo(skb)->frag_list) { 1335 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1336 1337 for (; list; list = list->next) { 1338 __wsum csum2; 1339 int end; 1340 1341 BUG_TRAP(start <= offset + len); 1342 1343 end = start + list->len; 1344 if ((copy = end - offset) > 0) { 1345 if (copy > len) 1346 copy = len; 1347 csum2 = skb_copy_and_csum_bits(list, 1348 offset - start, 1349 to, copy, 0); 1350 csum = csum_block_add(csum, csum2, pos); 1351 if ((len -= copy) == 0) 1352 return csum; 1353 offset += copy; 1354 to += copy; 1355 pos += copy; 1356 } 1357 start = end; 1358 } 1359 } 1360 BUG_ON(len); 1361 return csum; 1362 } 1363 1364 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to) 1365 { 1366 __wsum csum; 1367 long csstart; 1368 1369 if (skb->ip_summed == CHECKSUM_PARTIAL) 1370 csstart = skb->csum_start - skb_headroom(skb); 1371 else 1372 csstart = skb_headlen(skb); 1373 1374 BUG_ON(csstart > skb_headlen(skb)); 1375 1376 skb_copy_from_linear_data(skb, to, csstart); 1377 1378 csum = 0; 1379 if (csstart != skb->len) 1380 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart, 1381 skb->len - csstart, 0); 1382 1383 if (skb->ip_summed == CHECKSUM_PARTIAL) { 1384 long csstuff = csstart + skb->csum_offset; 1385 1386 *((__sum16 *)(to + csstuff)) = csum_fold(csum); 1387 } 1388 } 1389 1390 /** 1391 * skb_dequeue - remove from the head of the queue 1392 * @list: list to dequeue from 1393 * 1394 * Remove the head of the list. The list lock is taken so the function 1395 * may be used safely with other locking list functions. The head item is 1396 * returned or %NULL if the list is empty. 1397 */ 1398 1399 struct sk_buff *skb_dequeue(struct sk_buff_head *list) 1400 { 1401 unsigned long flags; 1402 struct sk_buff *result; 1403 1404 spin_lock_irqsave(&list->lock, flags); 1405 result = __skb_dequeue(list); 1406 spin_unlock_irqrestore(&list->lock, flags); 1407 return result; 1408 } 1409 1410 /** 1411 * skb_dequeue_tail - remove from the tail of the queue 1412 * @list: list to dequeue from 1413 * 1414 * Remove the tail of the list. The list lock is taken so the function 1415 * may be used safely with other locking list functions. The tail item is 1416 * returned or %NULL if the list is empty. 1417 */ 1418 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list) 1419 { 1420 unsigned long flags; 1421 struct sk_buff *result; 1422 1423 spin_lock_irqsave(&list->lock, flags); 1424 result = __skb_dequeue_tail(list); 1425 spin_unlock_irqrestore(&list->lock, flags); 1426 return result; 1427 } 1428 1429 /** 1430 * skb_queue_purge - empty a list 1431 * @list: list to empty 1432 * 1433 * Delete all buffers on an &sk_buff list. Each buffer is removed from 1434 * the list and one reference dropped. This function takes the list 1435 * lock and is atomic with respect to other list locking functions. 1436 */ 1437 void skb_queue_purge(struct sk_buff_head *list) 1438 { 1439 struct sk_buff *skb; 1440 while ((skb = skb_dequeue(list)) != NULL) 1441 kfree_skb(skb); 1442 } 1443 1444 /** 1445 * skb_queue_head - queue a buffer at the list head 1446 * @list: list to use 1447 * @newsk: buffer to queue 1448 * 1449 * Queue a buffer at the start of the list. This function takes the 1450 * list lock and can be used safely with other locking &sk_buff functions 1451 * safely. 1452 * 1453 * A buffer cannot be placed on two lists at the same time. 1454 */ 1455 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk) 1456 { 1457 unsigned long flags; 1458 1459 spin_lock_irqsave(&list->lock, flags); 1460 __skb_queue_head(list, newsk); 1461 spin_unlock_irqrestore(&list->lock, flags); 1462 } 1463 1464 /** 1465 * skb_queue_tail - queue a buffer at the list tail 1466 * @list: list to use 1467 * @newsk: buffer to queue 1468 * 1469 * Queue a buffer at the tail of the list. This function takes the 1470 * list lock and can be used safely with other locking &sk_buff functions 1471 * safely. 1472 * 1473 * A buffer cannot be placed on two lists at the same time. 1474 */ 1475 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk) 1476 { 1477 unsigned long flags; 1478 1479 spin_lock_irqsave(&list->lock, flags); 1480 __skb_queue_tail(list, newsk); 1481 spin_unlock_irqrestore(&list->lock, flags); 1482 } 1483 1484 /** 1485 * skb_unlink - remove a buffer from a list 1486 * @skb: buffer to remove 1487 * @list: list to use 1488 * 1489 * Remove a packet from a list. The list locks are taken and this 1490 * function is atomic with respect to other list locked calls 1491 * 1492 * You must know what list the SKB is on. 1493 */ 1494 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list) 1495 { 1496 unsigned long flags; 1497 1498 spin_lock_irqsave(&list->lock, flags); 1499 __skb_unlink(skb, list); 1500 spin_unlock_irqrestore(&list->lock, flags); 1501 } 1502 1503 /** 1504 * skb_append - append a buffer 1505 * @old: buffer to insert after 1506 * @newsk: buffer to insert 1507 * @list: list to use 1508 * 1509 * Place a packet after a given packet in a list. The list locks are taken 1510 * and this function is atomic with respect to other list locked calls. 1511 * A buffer cannot be placed on two lists at the same time. 1512 */ 1513 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list) 1514 { 1515 unsigned long flags; 1516 1517 spin_lock_irqsave(&list->lock, flags); 1518 __skb_append(old, newsk, list); 1519 spin_unlock_irqrestore(&list->lock, flags); 1520 } 1521 1522 1523 /** 1524 * skb_insert - insert a buffer 1525 * @old: buffer to insert before 1526 * @newsk: buffer to insert 1527 * @list: list to use 1528 * 1529 * Place a packet before a given packet in a list. The list locks are 1530 * taken and this function is atomic with respect to other list locked 1531 * calls. 1532 * 1533 * A buffer cannot be placed on two lists at the same time. 1534 */ 1535 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list) 1536 { 1537 unsigned long flags; 1538 1539 spin_lock_irqsave(&list->lock, flags); 1540 __skb_insert(newsk, old->prev, old, list); 1541 spin_unlock_irqrestore(&list->lock, flags); 1542 } 1543 1544 static inline void skb_split_inside_header(struct sk_buff *skb, 1545 struct sk_buff* skb1, 1546 const u32 len, const int pos) 1547 { 1548 int i; 1549 1550 skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len), 1551 pos - len); 1552 /* And move data appendix as is. */ 1553 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 1554 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i]; 1555 1556 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags; 1557 skb_shinfo(skb)->nr_frags = 0; 1558 skb1->data_len = skb->data_len; 1559 skb1->len += skb1->data_len; 1560 skb->data_len = 0; 1561 skb->len = len; 1562 skb_set_tail_pointer(skb, len); 1563 } 1564 1565 static inline void skb_split_no_header(struct sk_buff *skb, 1566 struct sk_buff* skb1, 1567 const u32 len, int pos) 1568 { 1569 int i, k = 0; 1570 const int nfrags = skb_shinfo(skb)->nr_frags; 1571 1572 skb_shinfo(skb)->nr_frags = 0; 1573 skb1->len = skb1->data_len = skb->len - len; 1574 skb->len = len; 1575 skb->data_len = len - pos; 1576 1577 for (i = 0; i < nfrags; i++) { 1578 int size = skb_shinfo(skb)->frags[i].size; 1579 1580 if (pos + size > len) { 1581 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i]; 1582 1583 if (pos < len) { 1584 /* Split frag. 1585 * We have two variants in this case: 1586 * 1. Move all the frag to the second 1587 * part, if it is possible. F.e. 1588 * this approach is mandatory for TUX, 1589 * where splitting is expensive. 1590 * 2. Split is accurately. We make this. 1591 */ 1592 get_page(skb_shinfo(skb)->frags[i].page); 1593 skb_shinfo(skb1)->frags[0].page_offset += len - pos; 1594 skb_shinfo(skb1)->frags[0].size -= len - pos; 1595 skb_shinfo(skb)->frags[i].size = len - pos; 1596 skb_shinfo(skb)->nr_frags++; 1597 } 1598 k++; 1599 } else 1600 skb_shinfo(skb)->nr_frags++; 1601 pos += size; 1602 } 1603 skb_shinfo(skb1)->nr_frags = k; 1604 } 1605 1606 /** 1607 * skb_split - Split fragmented skb to two parts at length len. 1608 * @skb: the buffer to split 1609 * @skb1: the buffer to receive the second part 1610 * @len: new length for skb 1611 */ 1612 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len) 1613 { 1614 int pos = skb_headlen(skb); 1615 1616 if (len < pos) /* Split line is inside header. */ 1617 skb_split_inside_header(skb, skb1, len, pos); 1618 else /* Second chunk has no header, nothing to copy. */ 1619 skb_split_no_header(skb, skb1, len, pos); 1620 } 1621 1622 /** 1623 * skb_prepare_seq_read - Prepare a sequential read of skb data 1624 * @skb: the buffer to read 1625 * @from: lower offset of data to be read 1626 * @to: upper offset of data to be read 1627 * @st: state variable 1628 * 1629 * Initializes the specified state variable. Must be called before 1630 * invoking skb_seq_read() for the first time. 1631 */ 1632 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from, 1633 unsigned int to, struct skb_seq_state *st) 1634 { 1635 st->lower_offset = from; 1636 st->upper_offset = to; 1637 st->root_skb = st->cur_skb = skb; 1638 st->frag_idx = st->stepped_offset = 0; 1639 st->frag_data = NULL; 1640 } 1641 1642 /** 1643 * skb_seq_read - Sequentially read skb data 1644 * @consumed: number of bytes consumed by the caller so far 1645 * @data: destination pointer for data to be returned 1646 * @st: state variable 1647 * 1648 * Reads a block of skb data at &consumed relative to the 1649 * lower offset specified to skb_prepare_seq_read(). Assigns 1650 * the head of the data block to &data and returns the length 1651 * of the block or 0 if the end of the skb data or the upper 1652 * offset has been reached. 1653 * 1654 * The caller is not required to consume all of the data 1655 * returned, i.e. &consumed is typically set to the number 1656 * of bytes already consumed and the next call to 1657 * skb_seq_read() will return the remaining part of the block. 1658 * 1659 * Note: The size of each block of data returned can be arbitary, 1660 * this limitation is the cost for zerocopy seqeuental 1661 * reads of potentially non linear data. 1662 * 1663 * Note: Fragment lists within fragments are not implemented 1664 * at the moment, state->root_skb could be replaced with 1665 * a stack for this purpose. 1666 */ 1667 unsigned int skb_seq_read(unsigned int consumed, const u8 **data, 1668 struct skb_seq_state *st) 1669 { 1670 unsigned int block_limit, abs_offset = consumed + st->lower_offset; 1671 skb_frag_t *frag; 1672 1673 if (unlikely(abs_offset >= st->upper_offset)) 1674 return 0; 1675 1676 next_skb: 1677 block_limit = skb_headlen(st->cur_skb); 1678 1679 if (abs_offset < block_limit) { 1680 *data = st->cur_skb->data + abs_offset; 1681 return block_limit - abs_offset; 1682 } 1683 1684 if (st->frag_idx == 0 && !st->frag_data) 1685 st->stepped_offset += skb_headlen(st->cur_skb); 1686 1687 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) { 1688 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx]; 1689 block_limit = frag->size + st->stepped_offset; 1690 1691 if (abs_offset < block_limit) { 1692 if (!st->frag_data) 1693 st->frag_data = kmap_skb_frag(frag); 1694 1695 *data = (u8 *) st->frag_data + frag->page_offset + 1696 (abs_offset - st->stepped_offset); 1697 1698 return block_limit - abs_offset; 1699 } 1700 1701 if (st->frag_data) { 1702 kunmap_skb_frag(st->frag_data); 1703 st->frag_data = NULL; 1704 } 1705 1706 st->frag_idx++; 1707 st->stepped_offset += frag->size; 1708 } 1709 1710 if (st->cur_skb->next) { 1711 st->cur_skb = st->cur_skb->next; 1712 st->frag_idx = 0; 1713 goto next_skb; 1714 } else if (st->root_skb == st->cur_skb && 1715 skb_shinfo(st->root_skb)->frag_list) { 1716 st->cur_skb = skb_shinfo(st->root_skb)->frag_list; 1717 goto next_skb; 1718 } 1719 1720 return 0; 1721 } 1722 1723 /** 1724 * skb_abort_seq_read - Abort a sequential read of skb data 1725 * @st: state variable 1726 * 1727 * Must be called if skb_seq_read() was not called until it 1728 * returned 0. 1729 */ 1730 void skb_abort_seq_read(struct skb_seq_state *st) 1731 { 1732 if (st->frag_data) 1733 kunmap_skb_frag(st->frag_data); 1734 } 1735 1736 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb)) 1737 1738 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text, 1739 struct ts_config *conf, 1740 struct ts_state *state) 1741 { 1742 return skb_seq_read(offset, text, TS_SKB_CB(state)); 1743 } 1744 1745 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state) 1746 { 1747 skb_abort_seq_read(TS_SKB_CB(state)); 1748 } 1749 1750 /** 1751 * skb_find_text - Find a text pattern in skb data 1752 * @skb: the buffer to look in 1753 * @from: search offset 1754 * @to: search limit 1755 * @config: textsearch configuration 1756 * @state: uninitialized textsearch state variable 1757 * 1758 * Finds a pattern in the skb data according to the specified 1759 * textsearch configuration. Use textsearch_next() to retrieve 1760 * subsequent occurrences of the pattern. Returns the offset 1761 * to the first occurrence or UINT_MAX if no match was found. 1762 */ 1763 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from, 1764 unsigned int to, struct ts_config *config, 1765 struct ts_state *state) 1766 { 1767 unsigned int ret; 1768 1769 config->get_next_block = skb_ts_get_next_block; 1770 config->finish = skb_ts_finish; 1771 1772 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state)); 1773 1774 ret = textsearch_find(config, state); 1775 return (ret <= to - from ? ret : UINT_MAX); 1776 } 1777 1778 /** 1779 * skb_append_datato_frags: - append the user data to a skb 1780 * @sk: sock structure 1781 * @skb: skb structure to be appened with user data. 1782 * @getfrag: call back function to be used for getting the user data 1783 * @from: pointer to user message iov 1784 * @length: length of the iov message 1785 * 1786 * Description: This procedure append the user data in the fragment part 1787 * of the skb if any page alloc fails user this procedure returns -ENOMEM 1788 */ 1789 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb, 1790 int (*getfrag)(void *from, char *to, int offset, 1791 int len, int odd, struct sk_buff *skb), 1792 void *from, int length) 1793 { 1794 int frg_cnt = 0; 1795 skb_frag_t *frag = NULL; 1796 struct page *page = NULL; 1797 int copy, left; 1798 int offset = 0; 1799 int ret; 1800 1801 do { 1802 /* Return error if we don't have space for new frag */ 1803 frg_cnt = skb_shinfo(skb)->nr_frags; 1804 if (frg_cnt >= MAX_SKB_FRAGS) 1805 return -EFAULT; 1806 1807 /* allocate a new page for next frag */ 1808 page = alloc_pages(sk->sk_allocation, 0); 1809 1810 /* If alloc_page fails just return failure and caller will 1811 * free previous allocated pages by doing kfree_skb() 1812 */ 1813 if (page == NULL) 1814 return -ENOMEM; 1815 1816 /* initialize the next frag */ 1817 sk->sk_sndmsg_page = page; 1818 sk->sk_sndmsg_off = 0; 1819 skb_fill_page_desc(skb, frg_cnt, page, 0, 0); 1820 skb->truesize += PAGE_SIZE; 1821 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc); 1822 1823 /* get the new initialized frag */ 1824 frg_cnt = skb_shinfo(skb)->nr_frags; 1825 frag = &skb_shinfo(skb)->frags[frg_cnt - 1]; 1826 1827 /* copy the user data to page */ 1828 left = PAGE_SIZE - frag->page_offset; 1829 copy = (length > left)? left : length; 1830 1831 ret = getfrag(from, (page_address(frag->page) + 1832 frag->page_offset + frag->size), 1833 offset, copy, 0, skb); 1834 if (ret < 0) 1835 return -EFAULT; 1836 1837 /* copy was successful so update the size parameters */ 1838 sk->sk_sndmsg_off += copy; 1839 frag->size += copy; 1840 skb->len += copy; 1841 skb->data_len += copy; 1842 offset += copy; 1843 length -= copy; 1844 1845 } while (length > 0); 1846 1847 return 0; 1848 } 1849 1850 /** 1851 * skb_pull_rcsum - pull skb and update receive checksum 1852 * @skb: buffer to update 1853 * @start: start of data before pull 1854 * @len: length of data pulled 1855 * 1856 * This function performs an skb_pull on the packet and updates 1857 * update the CHECKSUM_COMPLETE checksum. It should be used on 1858 * receive path processing instead of skb_pull unless you know 1859 * that the checksum difference is zero (e.g., a valid IP header) 1860 * or you are setting ip_summed to CHECKSUM_NONE. 1861 */ 1862 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len) 1863 { 1864 BUG_ON(len > skb->len); 1865 skb->len -= len; 1866 BUG_ON(skb->len < skb->data_len); 1867 skb_postpull_rcsum(skb, skb->data, len); 1868 return skb->data += len; 1869 } 1870 1871 EXPORT_SYMBOL_GPL(skb_pull_rcsum); 1872 1873 /** 1874 * skb_segment - Perform protocol segmentation on skb. 1875 * @skb: buffer to segment 1876 * @features: features for the output path (see dev->features) 1877 * 1878 * This function performs segmentation on the given skb. It returns 1879 * the segment at the given position. It returns NULL if there are 1880 * no more segments to generate, or when an error is encountered. 1881 */ 1882 struct sk_buff *skb_segment(struct sk_buff *skb, int features) 1883 { 1884 struct sk_buff *segs = NULL; 1885 struct sk_buff *tail = NULL; 1886 unsigned int mss = skb_shinfo(skb)->gso_size; 1887 unsigned int doffset = skb->data - skb_mac_header(skb); 1888 unsigned int offset = doffset; 1889 unsigned int headroom; 1890 unsigned int len; 1891 int sg = features & NETIF_F_SG; 1892 int nfrags = skb_shinfo(skb)->nr_frags; 1893 int err = -ENOMEM; 1894 int i = 0; 1895 int pos; 1896 1897 __skb_push(skb, doffset); 1898 headroom = skb_headroom(skb); 1899 pos = skb_headlen(skb); 1900 1901 do { 1902 struct sk_buff *nskb; 1903 skb_frag_t *frag; 1904 int hsize; 1905 int k; 1906 int size; 1907 1908 len = skb->len - offset; 1909 if (len > mss) 1910 len = mss; 1911 1912 hsize = skb_headlen(skb) - offset; 1913 if (hsize < 0) 1914 hsize = 0; 1915 if (hsize > len || !sg) 1916 hsize = len; 1917 1918 nskb = alloc_skb(hsize + doffset + headroom, GFP_ATOMIC); 1919 if (unlikely(!nskb)) 1920 goto err; 1921 1922 if (segs) 1923 tail->next = nskb; 1924 else 1925 segs = nskb; 1926 tail = nskb; 1927 1928 nskb->dev = skb->dev; 1929 nskb->priority = skb->priority; 1930 nskb->protocol = skb->protocol; 1931 nskb->dst = dst_clone(skb->dst); 1932 memcpy(nskb->cb, skb->cb, sizeof(skb->cb)); 1933 nskb->pkt_type = skb->pkt_type; 1934 nskb->mac_len = skb->mac_len; 1935 1936 skb_reserve(nskb, headroom); 1937 skb_reset_mac_header(nskb); 1938 skb_set_network_header(nskb, skb->mac_len); 1939 nskb->transport_header = (nskb->network_header + 1940 skb_network_header_len(skb)); 1941 skb_copy_from_linear_data(skb, skb_put(nskb, doffset), 1942 doffset); 1943 if (!sg) { 1944 nskb->csum = skb_copy_and_csum_bits(skb, offset, 1945 skb_put(nskb, len), 1946 len, 0); 1947 continue; 1948 } 1949 1950 frag = skb_shinfo(nskb)->frags; 1951 k = 0; 1952 1953 nskb->ip_summed = CHECKSUM_PARTIAL; 1954 nskb->csum = skb->csum; 1955 skb_copy_from_linear_data_offset(skb, offset, 1956 skb_put(nskb, hsize), hsize); 1957 1958 while (pos < offset + len) { 1959 BUG_ON(i >= nfrags); 1960 1961 *frag = skb_shinfo(skb)->frags[i]; 1962 get_page(frag->page); 1963 size = frag->size; 1964 1965 if (pos < offset) { 1966 frag->page_offset += offset - pos; 1967 frag->size -= offset - pos; 1968 } 1969 1970 k++; 1971 1972 if (pos + size <= offset + len) { 1973 i++; 1974 pos += size; 1975 } else { 1976 frag->size -= pos + size - (offset + len); 1977 break; 1978 } 1979 1980 frag++; 1981 } 1982 1983 skb_shinfo(nskb)->nr_frags = k; 1984 nskb->data_len = len - hsize; 1985 nskb->len += nskb->data_len; 1986 nskb->truesize += nskb->data_len; 1987 } while ((offset += len) < skb->len); 1988 1989 return segs; 1990 1991 err: 1992 while ((skb = segs)) { 1993 segs = skb->next; 1994 kfree_skb(skb); 1995 } 1996 return ERR_PTR(err); 1997 } 1998 1999 EXPORT_SYMBOL_GPL(skb_segment); 2000 2001 void __init skb_init(void) 2002 { 2003 skbuff_head_cache = kmem_cache_create("skbuff_head_cache", 2004 sizeof(struct sk_buff), 2005 0, 2006 SLAB_HWCACHE_ALIGN|SLAB_PANIC, 2007 NULL, NULL); 2008 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache", 2009 (2*sizeof(struct sk_buff)) + 2010 sizeof(atomic_t), 2011 0, 2012 SLAB_HWCACHE_ALIGN|SLAB_PANIC, 2013 NULL, NULL); 2014 } 2015 2016 /** 2017 * skb_to_sgvec - Fill a scatter-gather list from a socket buffer 2018 * @skb: Socket buffer containing the buffers to be mapped 2019 * @sg: The scatter-gather list to map into 2020 * @offset: The offset into the buffer's contents to start mapping 2021 * @len: Length of buffer space to be mapped 2022 * 2023 * Fill the specified scatter-gather list with mappings/pointers into a 2024 * region of the buffer space attached to a socket buffer. 2025 */ 2026 int 2027 skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) 2028 { 2029 int start = skb_headlen(skb); 2030 int i, copy = start - offset; 2031 int elt = 0; 2032 2033 if (copy > 0) { 2034 if (copy > len) 2035 copy = len; 2036 sg[elt].page = virt_to_page(skb->data + offset); 2037 sg[elt].offset = (unsigned long)(skb->data + offset) % PAGE_SIZE; 2038 sg[elt].length = copy; 2039 elt++; 2040 if ((len -= copy) == 0) 2041 return elt; 2042 offset += copy; 2043 } 2044 2045 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 2046 int end; 2047 2048 BUG_TRAP(start <= offset + len); 2049 2050 end = start + skb_shinfo(skb)->frags[i].size; 2051 if ((copy = end - offset) > 0) { 2052 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 2053 2054 if (copy > len) 2055 copy = len; 2056 sg[elt].page = frag->page; 2057 sg[elt].offset = frag->page_offset+offset-start; 2058 sg[elt].length = copy; 2059 elt++; 2060 if (!(len -= copy)) 2061 return elt; 2062 offset += copy; 2063 } 2064 start = end; 2065 } 2066 2067 if (skb_shinfo(skb)->frag_list) { 2068 struct sk_buff *list = skb_shinfo(skb)->frag_list; 2069 2070 for (; list; list = list->next) { 2071 int end; 2072 2073 BUG_TRAP(start <= offset + len); 2074 2075 end = start + list->len; 2076 if ((copy = end - offset) > 0) { 2077 if (copy > len) 2078 copy = len; 2079 elt += skb_to_sgvec(list, sg+elt, offset - start, copy); 2080 if ((len -= copy) == 0) 2081 return elt; 2082 offset += copy; 2083 } 2084 start = end; 2085 } 2086 } 2087 BUG_ON(len); 2088 return elt; 2089 } 2090 2091 /** 2092 * skb_cow_data - Check that a socket buffer's data buffers are writable 2093 * @skb: The socket buffer to check. 2094 * @tailbits: Amount of trailing space to be added 2095 * @trailer: Returned pointer to the skb where the @tailbits space begins 2096 * 2097 * Make sure that the data buffers attached to a socket buffer are 2098 * writable. If they are not, private copies are made of the data buffers 2099 * and the socket buffer is set to use these instead. 2100 * 2101 * If @tailbits is given, make sure that there is space to write @tailbits 2102 * bytes of data beyond current end of socket buffer. @trailer will be 2103 * set to point to the skb in which this space begins. 2104 * 2105 * The number of scatterlist elements required to completely map the 2106 * COW'd and extended socket buffer will be returned. 2107 */ 2108 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer) 2109 { 2110 int copyflag; 2111 int elt; 2112 struct sk_buff *skb1, **skb_p; 2113 2114 /* If skb is cloned or its head is paged, reallocate 2115 * head pulling out all the pages (pages are considered not writable 2116 * at the moment even if they are anonymous). 2117 */ 2118 if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) && 2119 __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL) 2120 return -ENOMEM; 2121 2122 /* Easy case. Most of packets will go this way. */ 2123 if (!skb_shinfo(skb)->frag_list) { 2124 /* A little of trouble, not enough of space for trailer. 2125 * This should not happen, when stack is tuned to generate 2126 * good frames. OK, on miss we reallocate and reserve even more 2127 * space, 128 bytes is fair. */ 2128 2129 if (skb_tailroom(skb) < tailbits && 2130 pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC)) 2131 return -ENOMEM; 2132 2133 /* Voila! */ 2134 *trailer = skb; 2135 return 1; 2136 } 2137 2138 /* Misery. We are in troubles, going to mincer fragments... */ 2139 2140 elt = 1; 2141 skb_p = &skb_shinfo(skb)->frag_list; 2142 copyflag = 0; 2143 2144 while ((skb1 = *skb_p) != NULL) { 2145 int ntail = 0; 2146 2147 /* The fragment is partially pulled by someone, 2148 * this can happen on input. Copy it and everything 2149 * after it. */ 2150 2151 if (skb_shared(skb1)) 2152 copyflag = 1; 2153 2154 /* If the skb is the last, worry about trailer. */ 2155 2156 if (skb1->next == NULL && tailbits) { 2157 if (skb_shinfo(skb1)->nr_frags || 2158 skb_shinfo(skb1)->frag_list || 2159 skb_tailroom(skb1) < tailbits) 2160 ntail = tailbits + 128; 2161 } 2162 2163 if (copyflag || 2164 skb_cloned(skb1) || 2165 ntail || 2166 skb_shinfo(skb1)->nr_frags || 2167 skb_shinfo(skb1)->frag_list) { 2168 struct sk_buff *skb2; 2169 2170 /* Fuck, we are miserable poor guys... */ 2171 if (ntail == 0) 2172 skb2 = skb_copy(skb1, GFP_ATOMIC); 2173 else 2174 skb2 = skb_copy_expand(skb1, 2175 skb_headroom(skb1), 2176 ntail, 2177 GFP_ATOMIC); 2178 if (unlikely(skb2 == NULL)) 2179 return -ENOMEM; 2180 2181 if (skb1->sk) 2182 skb_set_owner_w(skb2, skb1->sk); 2183 2184 /* Looking around. Are we still alive? 2185 * OK, link new skb, drop old one */ 2186 2187 skb2->next = skb1->next; 2188 *skb_p = skb2; 2189 kfree_skb(skb1); 2190 skb1 = skb2; 2191 } 2192 elt++; 2193 *trailer = skb1; 2194 skb_p = &skb1->next; 2195 } 2196 2197 return elt; 2198 } 2199 2200 EXPORT_SYMBOL(___pskb_trim); 2201 EXPORT_SYMBOL(__kfree_skb); 2202 EXPORT_SYMBOL(kfree_skb); 2203 EXPORT_SYMBOL(__pskb_pull_tail); 2204 EXPORT_SYMBOL(__alloc_skb); 2205 EXPORT_SYMBOL(__netdev_alloc_skb); 2206 EXPORT_SYMBOL(pskb_copy); 2207 EXPORT_SYMBOL(pskb_expand_head); 2208 EXPORT_SYMBOL(skb_checksum); 2209 EXPORT_SYMBOL(skb_clone); 2210 EXPORT_SYMBOL(skb_clone_fraglist); 2211 EXPORT_SYMBOL(skb_copy); 2212 EXPORT_SYMBOL(skb_copy_and_csum_bits); 2213 EXPORT_SYMBOL(skb_copy_and_csum_dev); 2214 EXPORT_SYMBOL(skb_copy_bits); 2215 EXPORT_SYMBOL(skb_copy_expand); 2216 EXPORT_SYMBOL(skb_over_panic); 2217 EXPORT_SYMBOL(skb_pad); 2218 EXPORT_SYMBOL(skb_realloc_headroom); 2219 EXPORT_SYMBOL(skb_under_panic); 2220 EXPORT_SYMBOL(skb_dequeue); 2221 EXPORT_SYMBOL(skb_dequeue_tail); 2222 EXPORT_SYMBOL(skb_insert); 2223 EXPORT_SYMBOL(skb_queue_purge); 2224 EXPORT_SYMBOL(skb_queue_head); 2225 EXPORT_SYMBOL(skb_queue_tail); 2226 EXPORT_SYMBOL(skb_unlink); 2227 EXPORT_SYMBOL(skb_append); 2228 EXPORT_SYMBOL(skb_split); 2229 EXPORT_SYMBOL(skb_prepare_seq_read); 2230 EXPORT_SYMBOL(skb_seq_read); 2231 EXPORT_SYMBOL(skb_abort_seq_read); 2232 EXPORT_SYMBOL(skb_find_text); 2233 EXPORT_SYMBOL(skb_append_datato_frags); 2234 2235 EXPORT_SYMBOL_GPL(skb_to_sgvec); 2236 EXPORT_SYMBOL_GPL(skb_cow_data); 2237