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/config.h> 42 #include <linux/module.h> 43 #include <linux/types.h> 44 #include <linux/kernel.h> 45 #include <linux/sched.h> 46 #include <linux/mm.h> 47 #include <linux/interrupt.h> 48 #include <linux/in.h> 49 #include <linux/inet.h> 50 #include <linux/slab.h> 51 #include <linux/netdevice.h> 52 #ifdef CONFIG_NET_CLS_ACT 53 #include <net/pkt_sched.h> 54 #endif 55 #include <linux/string.h> 56 #include <linux/skbuff.h> 57 #include <linux/cache.h> 58 #include <linux/rtnetlink.h> 59 #include <linux/init.h> 60 #include <linux/highmem.h> 61 62 #include <net/protocol.h> 63 #include <net/dst.h> 64 #include <net/sock.h> 65 #include <net/checksum.h> 66 #include <net/xfrm.h> 67 68 #include <asm/uaccess.h> 69 #include <asm/system.h> 70 71 static kmem_cache_t *skbuff_head_cache __read_mostly; 72 static kmem_cache_t *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:%p end:%p dev:%s\n", 92 here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end, 93 skb->dev ? skb->dev->name : "<NULL>"); 94 BUG(); 95 } 96 97 /** 98 * skb_under_panic - private function 99 * @skb: buffer 100 * @sz: size 101 * @here: address 102 * 103 * Out of line support code for skb_push(). Not user callable. 104 */ 105 106 void skb_under_panic(struct sk_buff *skb, int sz, void *here) 107 { 108 printk(KERN_EMERG "skb_under_panic: text:%p len:%d put:%d head:%p " 109 "data:%p tail:%p end:%p dev:%s\n", 110 here, skb->len, sz, skb->head, skb->data, skb->tail, skb->end, 111 skb->dev ? skb->dev->name : "<NULL>"); 112 BUG(); 113 } 114 115 /* Allocate a new skbuff. We do this ourselves so we can fill in a few 116 * 'private' fields and also do memory statistics to find all the 117 * [BEEP] leaks. 118 * 119 */ 120 121 /** 122 * __alloc_skb - allocate a network buffer 123 * @size: size to allocate 124 * @gfp_mask: allocation mask 125 * @fclone: allocate from fclone cache instead of head cache 126 * and allocate a cloned (child) skb 127 * 128 * Allocate a new &sk_buff. The returned buffer has no headroom and a 129 * tail room of size bytes. The object has a reference count of one. 130 * The return is the buffer. On a failure the return is %NULL. 131 * 132 * Buffers may only be allocated from interrupts using a @gfp_mask of 133 * %GFP_ATOMIC. 134 */ 135 struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, 136 int fclone) 137 { 138 struct sk_buff *skb; 139 u8 *data; 140 141 /* Get the HEAD */ 142 if (fclone) 143 skb = kmem_cache_alloc(skbuff_fclone_cache, 144 gfp_mask & ~__GFP_DMA); 145 else 146 skb = kmem_cache_alloc(skbuff_head_cache, 147 gfp_mask & ~__GFP_DMA); 148 149 if (!skb) 150 goto out; 151 152 /* Get the DATA. Size must match skb_add_mtu(). */ 153 size = SKB_DATA_ALIGN(size); 154 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask); 155 if (!data) 156 goto nodata; 157 158 memset(skb, 0, offsetof(struct sk_buff, truesize)); 159 skb->truesize = size + sizeof(struct sk_buff); 160 atomic_set(&skb->users, 1); 161 skb->head = data; 162 skb->data = data; 163 skb->tail = data; 164 skb->end = data + size; 165 if (fclone) { 166 struct sk_buff *child = skb + 1; 167 atomic_t *fclone_ref = (atomic_t *) (child + 1); 168 169 skb->fclone = SKB_FCLONE_ORIG; 170 atomic_set(fclone_ref, 1); 171 172 child->fclone = SKB_FCLONE_UNAVAILABLE; 173 } 174 atomic_set(&(skb_shinfo(skb)->dataref), 1); 175 skb_shinfo(skb)->nr_frags = 0; 176 skb_shinfo(skb)->tso_size = 0; 177 skb_shinfo(skb)->tso_segs = 0; 178 skb_shinfo(skb)->frag_list = NULL; 179 skb_shinfo(skb)->ufo_size = 0; 180 skb_shinfo(skb)->ip6_frag_id = 0; 181 out: 182 return skb; 183 nodata: 184 kmem_cache_free(skbuff_head_cache, skb); 185 skb = NULL; 186 goto out; 187 } 188 189 /** 190 * alloc_skb_from_cache - allocate a network buffer 191 * @cp: kmem_cache from which to allocate the data area 192 * (object size must be big enough for @size bytes + skb overheads) 193 * @size: size to allocate 194 * @gfp_mask: allocation mask 195 * 196 * Allocate a new &sk_buff. The returned buffer has no headroom and 197 * tail room of size bytes. The object has a reference count of one. 198 * The return is the buffer. On a failure the return is %NULL. 199 * 200 * Buffers may only be allocated from interrupts using a @gfp_mask of 201 * %GFP_ATOMIC. 202 */ 203 struct sk_buff *alloc_skb_from_cache(kmem_cache_t *cp, 204 unsigned int size, 205 gfp_t gfp_mask) 206 { 207 struct sk_buff *skb; 208 u8 *data; 209 210 /* Get the HEAD */ 211 skb = kmem_cache_alloc(skbuff_head_cache, 212 gfp_mask & ~__GFP_DMA); 213 if (!skb) 214 goto out; 215 216 /* Get the DATA. */ 217 size = SKB_DATA_ALIGN(size); 218 data = kmem_cache_alloc(cp, gfp_mask); 219 if (!data) 220 goto nodata; 221 222 memset(skb, 0, offsetof(struct sk_buff, truesize)); 223 skb->truesize = size + sizeof(struct sk_buff); 224 atomic_set(&skb->users, 1); 225 skb->head = data; 226 skb->data = data; 227 skb->tail = data; 228 skb->end = data + size; 229 230 atomic_set(&(skb_shinfo(skb)->dataref), 1); 231 skb_shinfo(skb)->nr_frags = 0; 232 skb_shinfo(skb)->tso_size = 0; 233 skb_shinfo(skb)->tso_segs = 0; 234 skb_shinfo(skb)->frag_list = NULL; 235 out: 236 return skb; 237 nodata: 238 kmem_cache_free(skbuff_head_cache, skb); 239 skb = NULL; 240 goto out; 241 } 242 243 244 static void skb_drop_fraglist(struct sk_buff *skb) 245 { 246 struct sk_buff *list = skb_shinfo(skb)->frag_list; 247 248 skb_shinfo(skb)->frag_list = NULL; 249 250 do { 251 struct sk_buff *this = list; 252 list = list->next; 253 kfree_skb(this); 254 } while (list); 255 } 256 257 static void skb_clone_fraglist(struct sk_buff *skb) 258 { 259 struct sk_buff *list; 260 261 for (list = skb_shinfo(skb)->frag_list; list; list = list->next) 262 skb_get(list); 263 } 264 265 void skb_release_data(struct sk_buff *skb) 266 { 267 if (!skb->cloned || 268 !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1, 269 &skb_shinfo(skb)->dataref)) { 270 if (skb_shinfo(skb)->nr_frags) { 271 int i; 272 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 273 put_page(skb_shinfo(skb)->frags[i].page); 274 } 275 276 if (skb_shinfo(skb)->frag_list) 277 skb_drop_fraglist(skb); 278 279 kfree(skb->head); 280 } 281 } 282 283 /* 284 * Free an skbuff by memory without cleaning the state. 285 */ 286 void kfree_skbmem(struct sk_buff *skb) 287 { 288 struct sk_buff *other; 289 atomic_t *fclone_ref; 290 291 skb_release_data(skb); 292 switch (skb->fclone) { 293 case SKB_FCLONE_UNAVAILABLE: 294 kmem_cache_free(skbuff_head_cache, skb); 295 break; 296 297 case SKB_FCLONE_ORIG: 298 fclone_ref = (atomic_t *) (skb + 2); 299 if (atomic_dec_and_test(fclone_ref)) 300 kmem_cache_free(skbuff_fclone_cache, skb); 301 break; 302 303 case SKB_FCLONE_CLONE: 304 fclone_ref = (atomic_t *) (skb + 1); 305 other = skb - 1; 306 307 /* The clone portion is available for 308 * fast-cloning again. 309 */ 310 skb->fclone = SKB_FCLONE_UNAVAILABLE; 311 312 if (atomic_dec_and_test(fclone_ref)) 313 kmem_cache_free(skbuff_fclone_cache, other); 314 break; 315 }; 316 } 317 318 /** 319 * __kfree_skb - private function 320 * @skb: buffer 321 * 322 * Free an sk_buff. Release anything attached to the buffer. 323 * Clean the state. This is an internal helper function. Users should 324 * always call kfree_skb 325 */ 326 327 void __kfree_skb(struct sk_buff *skb) 328 { 329 dst_release(skb->dst); 330 #ifdef CONFIG_XFRM 331 secpath_put(skb->sp); 332 #endif 333 if (skb->destructor) { 334 WARN_ON(in_irq()); 335 skb->destructor(skb); 336 } 337 #ifdef CONFIG_NETFILTER 338 nf_conntrack_put(skb->nfct); 339 #ifdef CONFIG_BRIDGE_NETFILTER 340 nf_bridge_put(skb->nf_bridge); 341 #endif 342 #endif 343 /* XXX: IS this still necessary? - JHS */ 344 #ifdef CONFIG_NET_SCHED 345 skb->tc_index = 0; 346 #ifdef CONFIG_NET_CLS_ACT 347 skb->tc_verd = 0; 348 #endif 349 #endif 350 351 kfree_skbmem(skb); 352 } 353 354 /** 355 * skb_clone - duplicate an sk_buff 356 * @skb: buffer to clone 357 * @gfp_mask: allocation priority 358 * 359 * Duplicate an &sk_buff. The new one is not owned by a socket. Both 360 * copies share the same packet data but not structure. The new 361 * buffer has a reference count of 1. If the allocation fails the 362 * function returns %NULL otherwise the new buffer is returned. 363 * 364 * If this function is called from an interrupt gfp_mask() must be 365 * %GFP_ATOMIC. 366 */ 367 368 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 369 { 370 struct sk_buff *n; 371 372 n = skb + 1; 373 if (skb->fclone == SKB_FCLONE_ORIG && 374 n->fclone == SKB_FCLONE_UNAVAILABLE) { 375 atomic_t *fclone_ref = (atomic_t *) (n + 1); 376 n->fclone = SKB_FCLONE_CLONE; 377 atomic_inc(fclone_ref); 378 } else { 379 n = kmem_cache_alloc(skbuff_head_cache, gfp_mask); 380 if (!n) 381 return NULL; 382 n->fclone = SKB_FCLONE_UNAVAILABLE; 383 } 384 385 #define C(x) n->x = skb->x 386 387 n->next = n->prev = NULL; 388 n->sk = NULL; 389 C(tstamp); 390 C(dev); 391 C(h); 392 C(nh); 393 C(mac); 394 C(dst); 395 dst_clone(skb->dst); 396 C(sp); 397 #ifdef CONFIG_INET 398 secpath_get(skb->sp); 399 #endif 400 memcpy(n->cb, skb->cb, sizeof(skb->cb)); 401 C(len); 402 C(data_len); 403 C(csum); 404 C(local_df); 405 n->cloned = 1; 406 n->nohdr = 0; 407 C(pkt_type); 408 C(ip_summed); 409 C(priority); 410 C(protocol); 411 n->destructor = NULL; 412 #ifdef CONFIG_NETFILTER 413 C(nfmark); 414 C(nfct); 415 nf_conntrack_get(skb->nfct); 416 C(nfctinfo); 417 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 418 C(ipvs_property); 419 #endif 420 #ifdef CONFIG_BRIDGE_NETFILTER 421 C(nf_bridge); 422 nf_bridge_get(skb->nf_bridge); 423 #endif 424 #endif /*CONFIG_NETFILTER*/ 425 #ifdef CONFIG_NET_SCHED 426 C(tc_index); 427 #ifdef CONFIG_NET_CLS_ACT 428 n->tc_verd = SET_TC_VERD(skb->tc_verd,0); 429 n->tc_verd = CLR_TC_OK2MUNGE(n->tc_verd); 430 n->tc_verd = CLR_TC_MUNGED(n->tc_verd); 431 C(input_dev); 432 #endif 433 434 #endif 435 C(truesize); 436 atomic_set(&n->users, 1); 437 C(head); 438 C(data); 439 C(tail); 440 C(end); 441 442 atomic_inc(&(skb_shinfo(skb)->dataref)); 443 skb->cloned = 1; 444 445 return n; 446 } 447 448 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old) 449 { 450 /* 451 * Shift between the two data areas in bytes 452 */ 453 unsigned long offset = new->data - old->data; 454 455 new->sk = NULL; 456 new->dev = old->dev; 457 new->priority = old->priority; 458 new->protocol = old->protocol; 459 new->dst = dst_clone(old->dst); 460 #ifdef CONFIG_INET 461 new->sp = secpath_get(old->sp); 462 #endif 463 new->h.raw = old->h.raw + offset; 464 new->nh.raw = old->nh.raw + offset; 465 new->mac.raw = old->mac.raw + offset; 466 memcpy(new->cb, old->cb, sizeof(old->cb)); 467 new->local_df = old->local_df; 468 new->fclone = SKB_FCLONE_UNAVAILABLE; 469 new->pkt_type = old->pkt_type; 470 new->tstamp = old->tstamp; 471 new->destructor = NULL; 472 #ifdef CONFIG_NETFILTER 473 new->nfmark = old->nfmark; 474 new->nfct = old->nfct; 475 nf_conntrack_get(old->nfct); 476 new->nfctinfo = old->nfctinfo; 477 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 478 new->ipvs_property = old->ipvs_property; 479 #endif 480 #ifdef CONFIG_BRIDGE_NETFILTER 481 new->nf_bridge = old->nf_bridge; 482 nf_bridge_get(old->nf_bridge); 483 #endif 484 #endif 485 #ifdef CONFIG_NET_SCHED 486 #ifdef CONFIG_NET_CLS_ACT 487 new->tc_verd = old->tc_verd; 488 #endif 489 new->tc_index = old->tc_index; 490 #endif 491 atomic_set(&new->users, 1); 492 skb_shinfo(new)->tso_size = skb_shinfo(old)->tso_size; 493 skb_shinfo(new)->tso_segs = skb_shinfo(old)->tso_segs; 494 } 495 496 /** 497 * skb_copy - create private copy of an sk_buff 498 * @skb: buffer to copy 499 * @gfp_mask: allocation priority 500 * 501 * Make a copy of both an &sk_buff and its data. This is used when the 502 * caller wishes to modify the data and needs a private copy of the 503 * data to alter. Returns %NULL on failure or the pointer to the buffer 504 * on success. The returned buffer has a reference count of 1. 505 * 506 * As by-product this function converts non-linear &sk_buff to linear 507 * one, so that &sk_buff becomes completely private and caller is allowed 508 * to modify all the data of returned buffer. This means that this 509 * function is not recommended for use in circumstances when only 510 * header is going to be modified. Use pskb_copy() instead. 511 */ 512 513 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask) 514 { 515 int headerlen = skb->data - skb->head; 516 /* 517 * Allocate the copy buffer 518 */ 519 struct sk_buff *n = alloc_skb(skb->end - skb->head + skb->data_len, 520 gfp_mask); 521 if (!n) 522 return NULL; 523 524 /* Set the data pointer */ 525 skb_reserve(n, headerlen); 526 /* Set the tail pointer and length */ 527 skb_put(n, skb->len); 528 n->csum = skb->csum; 529 n->ip_summed = skb->ip_summed; 530 531 if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len)) 532 BUG(); 533 534 copy_skb_header(n, skb); 535 return n; 536 } 537 538 539 /** 540 * pskb_copy - create copy of an sk_buff with private head. 541 * @skb: buffer to copy 542 * @gfp_mask: allocation priority 543 * 544 * Make a copy of both an &sk_buff and part of its data, located 545 * in header. Fragmented data remain shared. This is used when 546 * the caller wishes to modify only header of &sk_buff and needs 547 * private copy of the header to alter. Returns %NULL on failure 548 * or the pointer to the buffer on success. 549 * The returned buffer has a reference count of 1. 550 */ 551 552 struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask) 553 { 554 /* 555 * Allocate the copy buffer 556 */ 557 struct sk_buff *n = alloc_skb(skb->end - skb->head, gfp_mask); 558 559 if (!n) 560 goto out; 561 562 /* Set the data pointer */ 563 skb_reserve(n, skb->data - skb->head); 564 /* Set the tail pointer and length */ 565 skb_put(n, skb_headlen(skb)); 566 /* Copy the bytes */ 567 memcpy(n->data, skb->data, n->len); 568 n->csum = skb->csum; 569 n->ip_summed = skb->ip_summed; 570 571 n->data_len = skb->data_len; 572 n->len = skb->len; 573 574 if (skb_shinfo(skb)->nr_frags) { 575 int i; 576 577 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 578 skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i]; 579 get_page(skb_shinfo(n)->frags[i].page); 580 } 581 skb_shinfo(n)->nr_frags = i; 582 } 583 584 if (skb_shinfo(skb)->frag_list) { 585 skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list; 586 skb_clone_fraglist(n); 587 } 588 589 copy_skb_header(n, skb); 590 out: 591 return n; 592 } 593 594 /** 595 * pskb_expand_head - reallocate header of &sk_buff 596 * @skb: buffer to reallocate 597 * @nhead: room to add at head 598 * @ntail: room to add at tail 599 * @gfp_mask: allocation priority 600 * 601 * Expands (or creates identical copy, if &nhead and &ntail are zero) 602 * header of skb. &sk_buff itself is not changed. &sk_buff MUST have 603 * reference count of 1. Returns zero in the case of success or error, 604 * if expansion failed. In the last case, &sk_buff is not changed. 605 * 606 * All the pointers pointing into skb header may change and must be 607 * reloaded after call to this function. 608 */ 609 610 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, 611 gfp_t gfp_mask) 612 { 613 int i; 614 u8 *data; 615 int size = nhead + (skb->end - skb->head) + ntail; 616 long off; 617 618 if (skb_shared(skb)) 619 BUG(); 620 621 size = SKB_DATA_ALIGN(size); 622 623 data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask); 624 if (!data) 625 goto nodata; 626 627 /* Copy only real data... and, alas, header. This should be 628 * optimized for the cases when header is void. */ 629 memcpy(data + nhead, skb->head, skb->tail - skb->head); 630 memcpy(data + size, skb->end, sizeof(struct skb_shared_info)); 631 632 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 633 get_page(skb_shinfo(skb)->frags[i].page); 634 635 if (skb_shinfo(skb)->frag_list) 636 skb_clone_fraglist(skb); 637 638 skb_release_data(skb); 639 640 off = (data + nhead) - skb->head; 641 642 skb->head = data; 643 skb->end = data + size; 644 skb->data += off; 645 skb->tail += off; 646 skb->mac.raw += off; 647 skb->h.raw += off; 648 skb->nh.raw += off; 649 skb->cloned = 0; 650 skb->nohdr = 0; 651 atomic_set(&skb_shinfo(skb)->dataref, 1); 652 return 0; 653 654 nodata: 655 return -ENOMEM; 656 } 657 658 /* Make private copy of skb with writable head and some headroom */ 659 660 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom) 661 { 662 struct sk_buff *skb2; 663 int delta = headroom - skb_headroom(skb); 664 665 if (delta <= 0) 666 skb2 = pskb_copy(skb, GFP_ATOMIC); 667 else { 668 skb2 = skb_clone(skb, GFP_ATOMIC); 669 if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0, 670 GFP_ATOMIC)) { 671 kfree_skb(skb2); 672 skb2 = NULL; 673 } 674 } 675 return skb2; 676 } 677 678 679 /** 680 * skb_copy_expand - copy and expand sk_buff 681 * @skb: buffer to copy 682 * @newheadroom: new free bytes at head 683 * @newtailroom: new free bytes at tail 684 * @gfp_mask: allocation priority 685 * 686 * Make a copy of both an &sk_buff and its data and while doing so 687 * allocate additional space. 688 * 689 * This is used when the caller wishes to modify the data and needs a 690 * private copy of the data to alter as well as more space for new fields. 691 * Returns %NULL on failure or the pointer to the buffer 692 * on success. The returned buffer has a reference count of 1. 693 * 694 * You must pass %GFP_ATOMIC as the allocation priority if this function 695 * is called from an interrupt. 696 * 697 * BUG ALERT: ip_summed is not copied. Why does this work? Is it used 698 * only by netfilter in the cases when checksum is recalculated? --ANK 699 */ 700 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, 701 int newheadroom, int newtailroom, 702 gfp_t gfp_mask) 703 { 704 /* 705 * Allocate the copy buffer 706 */ 707 struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom, 708 gfp_mask); 709 int head_copy_len, head_copy_off; 710 711 if (!n) 712 return NULL; 713 714 skb_reserve(n, newheadroom); 715 716 /* Set the tail pointer and length */ 717 skb_put(n, skb->len); 718 719 head_copy_len = skb_headroom(skb); 720 head_copy_off = 0; 721 if (newheadroom <= head_copy_len) 722 head_copy_len = newheadroom; 723 else 724 head_copy_off = newheadroom - head_copy_len; 725 726 /* Copy the linear header and data. */ 727 if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off, 728 skb->len + head_copy_len)) 729 BUG(); 730 731 copy_skb_header(n, skb); 732 733 return n; 734 } 735 736 /** 737 * skb_pad - zero pad the tail of an skb 738 * @skb: buffer to pad 739 * @pad: space to pad 740 * 741 * Ensure that a buffer is followed by a padding area that is zero 742 * filled. Used by network drivers which may DMA or transfer data 743 * beyond the buffer end onto the wire. 744 * 745 * May return NULL in out of memory cases. 746 */ 747 748 struct sk_buff *skb_pad(struct sk_buff *skb, int pad) 749 { 750 struct sk_buff *nskb; 751 752 /* If the skbuff is non linear tailroom is always zero.. */ 753 if (skb_tailroom(skb) >= pad) { 754 memset(skb->data+skb->len, 0, pad); 755 return skb; 756 } 757 758 nskb = skb_copy_expand(skb, skb_headroom(skb), skb_tailroom(skb) + pad, GFP_ATOMIC); 759 kfree_skb(skb); 760 if (nskb) 761 memset(nskb->data+nskb->len, 0, pad); 762 return nskb; 763 } 764 765 /* Trims skb to length len. It can change skb pointers, if "realloc" is 1. 766 * If realloc==0 and trimming is impossible without change of data, 767 * it is BUG(). 768 */ 769 770 int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc) 771 { 772 int offset = skb_headlen(skb); 773 int nfrags = skb_shinfo(skb)->nr_frags; 774 int i; 775 776 for (i = 0; i < nfrags; i++) { 777 int end = offset + skb_shinfo(skb)->frags[i].size; 778 if (end > len) { 779 if (skb_cloned(skb)) { 780 if (!realloc) 781 BUG(); 782 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 783 return -ENOMEM; 784 } 785 if (len <= offset) { 786 put_page(skb_shinfo(skb)->frags[i].page); 787 skb_shinfo(skb)->nr_frags--; 788 } else { 789 skb_shinfo(skb)->frags[i].size = len - offset; 790 } 791 } 792 offset = end; 793 } 794 795 if (offset < len) { 796 skb->data_len -= skb->len - len; 797 skb->len = len; 798 } else { 799 if (len <= skb_headlen(skb)) { 800 skb->len = len; 801 skb->data_len = 0; 802 skb->tail = skb->data + len; 803 if (skb_shinfo(skb)->frag_list && !skb_cloned(skb)) 804 skb_drop_fraglist(skb); 805 } else { 806 skb->data_len -= skb->len - len; 807 skb->len = len; 808 } 809 } 810 811 return 0; 812 } 813 814 /** 815 * __pskb_pull_tail - advance tail of skb header 816 * @skb: buffer to reallocate 817 * @delta: number of bytes to advance tail 818 * 819 * The function makes a sense only on a fragmented &sk_buff, 820 * it expands header moving its tail forward and copying necessary 821 * data from fragmented part. 822 * 823 * &sk_buff MUST have reference count of 1. 824 * 825 * Returns %NULL (and &sk_buff does not change) if pull failed 826 * or value of new tail of skb in the case of success. 827 * 828 * All the pointers pointing into skb header may change and must be 829 * reloaded after call to this function. 830 */ 831 832 /* Moves tail of skb head forward, copying data from fragmented part, 833 * when it is necessary. 834 * 1. It may fail due to malloc failure. 835 * 2. It may change skb pointers. 836 * 837 * It is pretty complicated. Luckily, it is called only in exceptional cases. 838 */ 839 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta) 840 { 841 /* If skb has not enough free space at tail, get new one 842 * plus 128 bytes for future expansions. If we have enough 843 * room at tail, reallocate without expansion only if skb is cloned. 844 */ 845 int i, k, eat = (skb->tail + delta) - skb->end; 846 847 if (eat > 0 || skb_cloned(skb)) { 848 if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0, 849 GFP_ATOMIC)) 850 return NULL; 851 } 852 853 if (skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta)) 854 BUG(); 855 856 /* Optimization: no fragments, no reasons to preestimate 857 * size of pulled pages. Superb. 858 */ 859 if (!skb_shinfo(skb)->frag_list) 860 goto pull_pages; 861 862 /* Estimate size of pulled pages. */ 863 eat = delta; 864 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 865 if (skb_shinfo(skb)->frags[i].size >= eat) 866 goto pull_pages; 867 eat -= skb_shinfo(skb)->frags[i].size; 868 } 869 870 /* If we need update frag list, we are in troubles. 871 * Certainly, it possible to add an offset to skb data, 872 * but taking into account that pulling is expected to 873 * be very rare operation, it is worth to fight against 874 * further bloating skb head and crucify ourselves here instead. 875 * Pure masohism, indeed. 8)8) 876 */ 877 if (eat) { 878 struct sk_buff *list = skb_shinfo(skb)->frag_list; 879 struct sk_buff *clone = NULL; 880 struct sk_buff *insp = NULL; 881 882 do { 883 if (!list) 884 BUG(); 885 886 if (list->len <= eat) { 887 /* Eaten as whole. */ 888 eat -= list->len; 889 list = list->next; 890 insp = list; 891 } else { 892 /* Eaten partially. */ 893 894 if (skb_shared(list)) { 895 /* Sucks! We need to fork list. :-( */ 896 clone = skb_clone(list, GFP_ATOMIC); 897 if (!clone) 898 return NULL; 899 insp = list->next; 900 list = clone; 901 } else { 902 /* This may be pulled without 903 * problems. */ 904 insp = list; 905 } 906 if (!pskb_pull(list, eat)) { 907 if (clone) 908 kfree_skb(clone); 909 return NULL; 910 } 911 break; 912 } 913 } while (eat); 914 915 /* Free pulled out fragments. */ 916 while ((list = skb_shinfo(skb)->frag_list) != insp) { 917 skb_shinfo(skb)->frag_list = list->next; 918 kfree_skb(list); 919 } 920 /* And insert new clone at head. */ 921 if (clone) { 922 clone->next = list; 923 skb_shinfo(skb)->frag_list = clone; 924 } 925 } 926 /* Success! Now we may commit changes to skb data. */ 927 928 pull_pages: 929 eat = delta; 930 k = 0; 931 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 932 if (skb_shinfo(skb)->frags[i].size <= eat) { 933 put_page(skb_shinfo(skb)->frags[i].page); 934 eat -= skb_shinfo(skb)->frags[i].size; 935 } else { 936 skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; 937 if (eat) { 938 skb_shinfo(skb)->frags[k].page_offset += eat; 939 skb_shinfo(skb)->frags[k].size -= eat; 940 eat = 0; 941 } 942 k++; 943 } 944 } 945 skb_shinfo(skb)->nr_frags = k; 946 947 skb->tail += delta; 948 skb->data_len -= delta; 949 950 return skb->tail; 951 } 952 953 /* Copy some data bits from skb to kernel buffer. */ 954 955 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) 956 { 957 int i, copy; 958 int start = skb_headlen(skb); 959 960 if (offset > (int)skb->len - len) 961 goto fault; 962 963 /* Copy header. */ 964 if ((copy = start - offset) > 0) { 965 if (copy > len) 966 copy = len; 967 memcpy(to, skb->data + offset, copy); 968 if ((len -= copy) == 0) 969 return 0; 970 offset += copy; 971 to += copy; 972 } 973 974 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 975 int end; 976 977 BUG_TRAP(start <= offset + len); 978 979 end = start + skb_shinfo(skb)->frags[i].size; 980 if ((copy = end - offset) > 0) { 981 u8 *vaddr; 982 983 if (copy > len) 984 copy = len; 985 986 vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]); 987 memcpy(to, 988 vaddr + skb_shinfo(skb)->frags[i].page_offset+ 989 offset - start, copy); 990 kunmap_skb_frag(vaddr); 991 992 if ((len -= copy) == 0) 993 return 0; 994 offset += copy; 995 to += copy; 996 } 997 start = end; 998 } 999 1000 if (skb_shinfo(skb)->frag_list) { 1001 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1002 1003 for (; list; list = list->next) { 1004 int end; 1005 1006 BUG_TRAP(start <= offset + len); 1007 1008 end = start + list->len; 1009 if ((copy = end - offset) > 0) { 1010 if (copy > len) 1011 copy = len; 1012 if (skb_copy_bits(list, offset - start, 1013 to, copy)) 1014 goto fault; 1015 if ((len -= copy) == 0) 1016 return 0; 1017 offset += copy; 1018 to += copy; 1019 } 1020 start = end; 1021 } 1022 } 1023 if (!len) 1024 return 0; 1025 1026 fault: 1027 return -EFAULT; 1028 } 1029 1030 /** 1031 * skb_store_bits - store bits from kernel buffer to skb 1032 * @skb: destination buffer 1033 * @offset: offset in destination 1034 * @from: source buffer 1035 * @len: number of bytes to copy 1036 * 1037 * Copy the specified number of bytes from the source buffer to the 1038 * destination skb. This function handles all the messy bits of 1039 * traversing fragment lists and such. 1040 */ 1041 1042 int skb_store_bits(const struct sk_buff *skb, int offset, void *from, int len) 1043 { 1044 int i, copy; 1045 int start = skb_headlen(skb); 1046 1047 if (offset > (int)skb->len - len) 1048 goto fault; 1049 1050 if ((copy = start - offset) > 0) { 1051 if (copy > len) 1052 copy = len; 1053 memcpy(skb->data + offset, from, copy); 1054 if ((len -= copy) == 0) 1055 return 0; 1056 offset += copy; 1057 from += copy; 1058 } 1059 1060 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1061 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 1062 int end; 1063 1064 BUG_TRAP(start <= offset + len); 1065 1066 end = start + frag->size; 1067 if ((copy = end - offset) > 0) { 1068 u8 *vaddr; 1069 1070 if (copy > len) 1071 copy = len; 1072 1073 vaddr = kmap_skb_frag(frag); 1074 memcpy(vaddr + frag->page_offset + offset - start, 1075 from, copy); 1076 kunmap_skb_frag(vaddr); 1077 1078 if ((len -= copy) == 0) 1079 return 0; 1080 offset += copy; 1081 from += copy; 1082 } 1083 start = end; 1084 } 1085 1086 if (skb_shinfo(skb)->frag_list) { 1087 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1088 1089 for (; list; list = list->next) { 1090 int end; 1091 1092 BUG_TRAP(start <= offset + len); 1093 1094 end = start + list->len; 1095 if ((copy = end - offset) > 0) { 1096 if (copy > len) 1097 copy = len; 1098 if (skb_store_bits(list, offset - start, 1099 from, copy)) 1100 goto fault; 1101 if ((len -= copy) == 0) 1102 return 0; 1103 offset += copy; 1104 from += copy; 1105 } 1106 start = end; 1107 } 1108 } 1109 if (!len) 1110 return 0; 1111 1112 fault: 1113 return -EFAULT; 1114 } 1115 1116 EXPORT_SYMBOL(skb_store_bits); 1117 1118 /* Checksum skb data. */ 1119 1120 unsigned int skb_checksum(const struct sk_buff *skb, int offset, 1121 int len, unsigned int csum) 1122 { 1123 int start = skb_headlen(skb); 1124 int i, copy = start - offset; 1125 int pos = 0; 1126 1127 /* Checksum header. */ 1128 if (copy > 0) { 1129 if (copy > len) 1130 copy = len; 1131 csum = csum_partial(skb->data + offset, copy, csum); 1132 if ((len -= copy) == 0) 1133 return csum; 1134 offset += copy; 1135 pos = copy; 1136 } 1137 1138 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1139 int end; 1140 1141 BUG_TRAP(start <= offset + len); 1142 1143 end = start + skb_shinfo(skb)->frags[i].size; 1144 if ((copy = end - offset) > 0) { 1145 unsigned int csum2; 1146 u8 *vaddr; 1147 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 1148 1149 if (copy > len) 1150 copy = len; 1151 vaddr = kmap_skb_frag(frag); 1152 csum2 = csum_partial(vaddr + frag->page_offset + 1153 offset - start, copy, 0); 1154 kunmap_skb_frag(vaddr); 1155 csum = csum_block_add(csum, csum2, pos); 1156 if (!(len -= copy)) 1157 return csum; 1158 offset += copy; 1159 pos += copy; 1160 } 1161 start = end; 1162 } 1163 1164 if (skb_shinfo(skb)->frag_list) { 1165 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1166 1167 for (; list; list = list->next) { 1168 int end; 1169 1170 BUG_TRAP(start <= offset + len); 1171 1172 end = start + list->len; 1173 if ((copy = end - offset) > 0) { 1174 unsigned int csum2; 1175 if (copy > len) 1176 copy = len; 1177 csum2 = skb_checksum(list, offset - start, 1178 copy, 0); 1179 csum = csum_block_add(csum, csum2, pos); 1180 if ((len -= copy) == 0) 1181 return csum; 1182 offset += copy; 1183 pos += copy; 1184 } 1185 start = end; 1186 } 1187 } 1188 if (len) 1189 BUG(); 1190 1191 return csum; 1192 } 1193 1194 /* Both of above in one bottle. */ 1195 1196 unsigned int skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, 1197 u8 *to, int len, unsigned int csum) 1198 { 1199 int start = skb_headlen(skb); 1200 int i, copy = start - offset; 1201 int pos = 0; 1202 1203 /* Copy header. */ 1204 if (copy > 0) { 1205 if (copy > len) 1206 copy = len; 1207 csum = csum_partial_copy_nocheck(skb->data + offset, to, 1208 copy, csum); 1209 if ((len -= copy) == 0) 1210 return csum; 1211 offset += copy; 1212 to += copy; 1213 pos = copy; 1214 } 1215 1216 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 1217 int end; 1218 1219 BUG_TRAP(start <= offset + len); 1220 1221 end = start + skb_shinfo(skb)->frags[i].size; 1222 if ((copy = end - offset) > 0) { 1223 unsigned int csum2; 1224 u8 *vaddr; 1225 skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; 1226 1227 if (copy > len) 1228 copy = len; 1229 vaddr = kmap_skb_frag(frag); 1230 csum2 = csum_partial_copy_nocheck(vaddr + 1231 frag->page_offset + 1232 offset - start, to, 1233 copy, 0); 1234 kunmap_skb_frag(vaddr); 1235 csum = csum_block_add(csum, csum2, pos); 1236 if (!(len -= copy)) 1237 return csum; 1238 offset += copy; 1239 to += copy; 1240 pos += copy; 1241 } 1242 start = end; 1243 } 1244 1245 if (skb_shinfo(skb)->frag_list) { 1246 struct sk_buff *list = skb_shinfo(skb)->frag_list; 1247 1248 for (; list; list = list->next) { 1249 unsigned int csum2; 1250 int end; 1251 1252 BUG_TRAP(start <= offset + len); 1253 1254 end = start + list->len; 1255 if ((copy = end - offset) > 0) { 1256 if (copy > len) 1257 copy = len; 1258 csum2 = skb_copy_and_csum_bits(list, 1259 offset - start, 1260 to, copy, 0); 1261 csum = csum_block_add(csum, csum2, pos); 1262 if ((len -= copy) == 0) 1263 return csum; 1264 offset += copy; 1265 to += copy; 1266 pos += copy; 1267 } 1268 start = end; 1269 } 1270 } 1271 if (len) 1272 BUG(); 1273 return csum; 1274 } 1275 1276 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to) 1277 { 1278 unsigned int csum; 1279 long csstart; 1280 1281 if (skb->ip_summed == CHECKSUM_HW) 1282 csstart = skb->h.raw - skb->data; 1283 else 1284 csstart = skb_headlen(skb); 1285 1286 if (csstart > skb_headlen(skb)) 1287 BUG(); 1288 1289 memcpy(to, skb->data, csstart); 1290 1291 csum = 0; 1292 if (csstart != skb->len) 1293 csum = skb_copy_and_csum_bits(skb, csstart, to + csstart, 1294 skb->len - csstart, 0); 1295 1296 if (skb->ip_summed == CHECKSUM_HW) { 1297 long csstuff = csstart + skb->csum; 1298 1299 *((unsigned short *)(to + csstuff)) = csum_fold(csum); 1300 } 1301 } 1302 1303 /** 1304 * skb_dequeue - remove from the head of the queue 1305 * @list: list to dequeue from 1306 * 1307 * Remove the head of the list. The list lock is taken so the function 1308 * may be used safely with other locking list functions. The head item is 1309 * returned or %NULL if the list is empty. 1310 */ 1311 1312 struct sk_buff *skb_dequeue(struct sk_buff_head *list) 1313 { 1314 unsigned long flags; 1315 struct sk_buff *result; 1316 1317 spin_lock_irqsave(&list->lock, flags); 1318 result = __skb_dequeue(list); 1319 spin_unlock_irqrestore(&list->lock, flags); 1320 return result; 1321 } 1322 1323 /** 1324 * skb_dequeue_tail - remove from the tail of the queue 1325 * @list: list to dequeue from 1326 * 1327 * Remove the tail of the list. The list lock is taken so the function 1328 * may be used safely with other locking list functions. The tail item is 1329 * returned or %NULL if the list is empty. 1330 */ 1331 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list) 1332 { 1333 unsigned long flags; 1334 struct sk_buff *result; 1335 1336 spin_lock_irqsave(&list->lock, flags); 1337 result = __skb_dequeue_tail(list); 1338 spin_unlock_irqrestore(&list->lock, flags); 1339 return result; 1340 } 1341 1342 /** 1343 * skb_queue_purge - empty a list 1344 * @list: list to empty 1345 * 1346 * Delete all buffers on an &sk_buff list. Each buffer is removed from 1347 * the list and one reference dropped. This function takes the list 1348 * lock and is atomic with respect to other list locking functions. 1349 */ 1350 void skb_queue_purge(struct sk_buff_head *list) 1351 { 1352 struct sk_buff *skb; 1353 while ((skb = skb_dequeue(list)) != NULL) 1354 kfree_skb(skb); 1355 } 1356 1357 /** 1358 * skb_queue_head - queue a buffer at the list head 1359 * @list: list to use 1360 * @newsk: buffer to queue 1361 * 1362 * Queue a buffer at the start of the list. This function takes the 1363 * list lock and can be used safely with other locking &sk_buff functions 1364 * safely. 1365 * 1366 * A buffer cannot be placed on two lists at the same time. 1367 */ 1368 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk) 1369 { 1370 unsigned long flags; 1371 1372 spin_lock_irqsave(&list->lock, flags); 1373 __skb_queue_head(list, newsk); 1374 spin_unlock_irqrestore(&list->lock, flags); 1375 } 1376 1377 /** 1378 * skb_queue_tail - queue a buffer at the list tail 1379 * @list: list to use 1380 * @newsk: buffer to queue 1381 * 1382 * Queue a buffer at the tail of the list. This function takes the 1383 * list lock and can be used safely with other locking &sk_buff functions 1384 * safely. 1385 * 1386 * A buffer cannot be placed on two lists at the same time. 1387 */ 1388 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk) 1389 { 1390 unsigned long flags; 1391 1392 spin_lock_irqsave(&list->lock, flags); 1393 __skb_queue_tail(list, newsk); 1394 spin_unlock_irqrestore(&list->lock, flags); 1395 } 1396 1397 /** 1398 * skb_unlink - remove a buffer from a list 1399 * @skb: buffer to remove 1400 * @list: list to use 1401 * 1402 * Remove a packet from a list. The list locks are taken and this 1403 * function is atomic with respect to other list locked calls 1404 * 1405 * You must know what list the SKB is on. 1406 */ 1407 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list) 1408 { 1409 unsigned long flags; 1410 1411 spin_lock_irqsave(&list->lock, flags); 1412 __skb_unlink(skb, list); 1413 spin_unlock_irqrestore(&list->lock, flags); 1414 } 1415 1416 /** 1417 * skb_append - append a buffer 1418 * @old: buffer to insert after 1419 * @newsk: buffer to insert 1420 * @list: list to use 1421 * 1422 * Place a packet after a given packet in a list. The list locks are taken 1423 * and this function is atomic with respect to other list locked calls. 1424 * A buffer cannot be placed on two lists at the same time. 1425 */ 1426 void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list) 1427 { 1428 unsigned long flags; 1429 1430 spin_lock_irqsave(&list->lock, flags); 1431 __skb_append(old, newsk, list); 1432 spin_unlock_irqrestore(&list->lock, flags); 1433 } 1434 1435 1436 /** 1437 * skb_insert - insert a buffer 1438 * @old: buffer to insert before 1439 * @newsk: buffer to insert 1440 * @list: list to use 1441 * 1442 * Place a packet before a given packet in a list. The list locks are 1443 * taken and this function is atomic with respect to other list locked 1444 * calls. 1445 * 1446 * A buffer cannot be placed on two lists at the same time. 1447 */ 1448 void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list) 1449 { 1450 unsigned long flags; 1451 1452 spin_lock_irqsave(&list->lock, flags); 1453 __skb_insert(newsk, old->prev, old, list); 1454 spin_unlock_irqrestore(&list->lock, flags); 1455 } 1456 1457 #if 0 1458 /* 1459 * Tune the memory allocator for a new MTU size. 1460 */ 1461 void skb_add_mtu(int mtu) 1462 { 1463 /* Must match allocation in alloc_skb */ 1464 mtu = SKB_DATA_ALIGN(mtu) + sizeof(struct skb_shared_info); 1465 1466 kmem_add_cache_size(mtu); 1467 } 1468 #endif 1469 1470 static inline void skb_split_inside_header(struct sk_buff *skb, 1471 struct sk_buff* skb1, 1472 const u32 len, const int pos) 1473 { 1474 int i; 1475 1476 memcpy(skb_put(skb1, pos - len), skb->data + len, pos - len); 1477 1478 /* And move data appendix as is. */ 1479 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) 1480 skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i]; 1481 1482 skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags; 1483 skb_shinfo(skb)->nr_frags = 0; 1484 skb1->data_len = skb->data_len; 1485 skb1->len += skb1->data_len; 1486 skb->data_len = 0; 1487 skb->len = len; 1488 skb->tail = skb->data + len; 1489 } 1490 1491 static inline void skb_split_no_header(struct sk_buff *skb, 1492 struct sk_buff* skb1, 1493 const u32 len, int pos) 1494 { 1495 int i, k = 0; 1496 const int nfrags = skb_shinfo(skb)->nr_frags; 1497 1498 skb_shinfo(skb)->nr_frags = 0; 1499 skb1->len = skb1->data_len = skb->len - len; 1500 skb->len = len; 1501 skb->data_len = len - pos; 1502 1503 for (i = 0; i < nfrags; i++) { 1504 int size = skb_shinfo(skb)->frags[i].size; 1505 1506 if (pos + size > len) { 1507 skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i]; 1508 1509 if (pos < len) { 1510 /* Split frag. 1511 * We have two variants in this case: 1512 * 1. Move all the frag to the second 1513 * part, if it is possible. F.e. 1514 * this approach is mandatory for TUX, 1515 * where splitting is expensive. 1516 * 2. Split is accurately. We make this. 1517 */ 1518 get_page(skb_shinfo(skb)->frags[i].page); 1519 skb_shinfo(skb1)->frags[0].page_offset += len - pos; 1520 skb_shinfo(skb1)->frags[0].size -= len - pos; 1521 skb_shinfo(skb)->frags[i].size = len - pos; 1522 skb_shinfo(skb)->nr_frags++; 1523 } 1524 k++; 1525 } else 1526 skb_shinfo(skb)->nr_frags++; 1527 pos += size; 1528 } 1529 skb_shinfo(skb1)->nr_frags = k; 1530 } 1531 1532 /** 1533 * skb_split - Split fragmented skb to two parts at length len. 1534 * @skb: the buffer to split 1535 * @skb1: the buffer to receive the second part 1536 * @len: new length for skb 1537 */ 1538 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len) 1539 { 1540 int pos = skb_headlen(skb); 1541 1542 if (len < pos) /* Split line is inside header. */ 1543 skb_split_inside_header(skb, skb1, len, pos); 1544 else /* Second chunk has no header, nothing to copy. */ 1545 skb_split_no_header(skb, skb1, len, pos); 1546 } 1547 1548 /** 1549 * skb_prepare_seq_read - Prepare a sequential read of skb data 1550 * @skb: the buffer to read 1551 * @from: lower offset of data to be read 1552 * @to: upper offset of data to be read 1553 * @st: state variable 1554 * 1555 * Initializes the specified state variable. Must be called before 1556 * invoking skb_seq_read() for the first time. 1557 */ 1558 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from, 1559 unsigned int to, struct skb_seq_state *st) 1560 { 1561 st->lower_offset = from; 1562 st->upper_offset = to; 1563 st->root_skb = st->cur_skb = skb; 1564 st->frag_idx = st->stepped_offset = 0; 1565 st->frag_data = NULL; 1566 } 1567 1568 /** 1569 * skb_seq_read - Sequentially read skb data 1570 * @consumed: number of bytes consumed by the caller so far 1571 * @data: destination pointer for data to be returned 1572 * @st: state variable 1573 * 1574 * Reads a block of skb data at &consumed relative to the 1575 * lower offset specified to skb_prepare_seq_read(). Assigns 1576 * the head of the data block to &data and returns the length 1577 * of the block or 0 if the end of the skb data or the upper 1578 * offset has been reached. 1579 * 1580 * The caller is not required to consume all of the data 1581 * returned, i.e. &consumed is typically set to the number 1582 * of bytes already consumed and the next call to 1583 * skb_seq_read() will return the remaining part of the block. 1584 * 1585 * Note: The size of each block of data returned can be arbitary, 1586 * this limitation is the cost for zerocopy seqeuental 1587 * reads of potentially non linear data. 1588 * 1589 * Note: Fragment lists within fragments are not implemented 1590 * at the moment, state->root_skb could be replaced with 1591 * a stack for this purpose. 1592 */ 1593 unsigned int skb_seq_read(unsigned int consumed, const u8 **data, 1594 struct skb_seq_state *st) 1595 { 1596 unsigned int block_limit, abs_offset = consumed + st->lower_offset; 1597 skb_frag_t *frag; 1598 1599 if (unlikely(abs_offset >= st->upper_offset)) 1600 return 0; 1601 1602 next_skb: 1603 block_limit = skb_headlen(st->cur_skb); 1604 1605 if (abs_offset < block_limit) { 1606 *data = st->cur_skb->data + abs_offset; 1607 return block_limit - abs_offset; 1608 } 1609 1610 if (st->frag_idx == 0 && !st->frag_data) 1611 st->stepped_offset += skb_headlen(st->cur_skb); 1612 1613 while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) { 1614 frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx]; 1615 block_limit = frag->size + st->stepped_offset; 1616 1617 if (abs_offset < block_limit) { 1618 if (!st->frag_data) 1619 st->frag_data = kmap_skb_frag(frag); 1620 1621 *data = (u8 *) st->frag_data + frag->page_offset + 1622 (abs_offset - st->stepped_offset); 1623 1624 return block_limit - abs_offset; 1625 } 1626 1627 if (st->frag_data) { 1628 kunmap_skb_frag(st->frag_data); 1629 st->frag_data = NULL; 1630 } 1631 1632 st->frag_idx++; 1633 st->stepped_offset += frag->size; 1634 } 1635 1636 if (st->cur_skb->next) { 1637 st->cur_skb = st->cur_skb->next; 1638 st->frag_idx = 0; 1639 goto next_skb; 1640 } else if (st->root_skb == st->cur_skb && 1641 skb_shinfo(st->root_skb)->frag_list) { 1642 st->cur_skb = skb_shinfo(st->root_skb)->frag_list; 1643 goto next_skb; 1644 } 1645 1646 return 0; 1647 } 1648 1649 /** 1650 * skb_abort_seq_read - Abort a sequential read of skb data 1651 * @st: state variable 1652 * 1653 * Must be called if skb_seq_read() was not called until it 1654 * returned 0. 1655 */ 1656 void skb_abort_seq_read(struct skb_seq_state *st) 1657 { 1658 if (st->frag_data) 1659 kunmap_skb_frag(st->frag_data); 1660 } 1661 1662 #define TS_SKB_CB(state) ((struct skb_seq_state *) &((state)->cb)) 1663 1664 static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text, 1665 struct ts_config *conf, 1666 struct ts_state *state) 1667 { 1668 return skb_seq_read(offset, text, TS_SKB_CB(state)); 1669 } 1670 1671 static void skb_ts_finish(struct ts_config *conf, struct ts_state *state) 1672 { 1673 skb_abort_seq_read(TS_SKB_CB(state)); 1674 } 1675 1676 /** 1677 * skb_find_text - Find a text pattern in skb data 1678 * @skb: the buffer to look in 1679 * @from: search offset 1680 * @to: search limit 1681 * @config: textsearch configuration 1682 * @state: uninitialized textsearch state variable 1683 * 1684 * Finds a pattern in the skb data according to the specified 1685 * textsearch configuration. Use textsearch_next() to retrieve 1686 * subsequent occurrences of the pattern. Returns the offset 1687 * to the first occurrence or UINT_MAX if no match was found. 1688 */ 1689 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from, 1690 unsigned int to, struct ts_config *config, 1691 struct ts_state *state) 1692 { 1693 config->get_next_block = skb_ts_get_next_block; 1694 config->finish = skb_ts_finish; 1695 1696 skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state)); 1697 1698 return textsearch_find(config, state); 1699 } 1700 1701 /** 1702 * skb_append_datato_frags: - append the user data to a skb 1703 * @sk: sock structure 1704 * @skb: skb structure to be appened with user data. 1705 * @getfrag: call back function to be used for getting the user data 1706 * @from: pointer to user message iov 1707 * @length: length of the iov message 1708 * 1709 * Description: This procedure append the user data in the fragment part 1710 * of the skb if any page alloc fails user this procedure returns -ENOMEM 1711 */ 1712 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb, 1713 int getfrag(void *from, char *to, int offset, 1714 int len, int odd, struct sk_buff *skb), 1715 void *from, int length) 1716 { 1717 int frg_cnt = 0; 1718 skb_frag_t *frag = NULL; 1719 struct page *page = NULL; 1720 int copy, left; 1721 int offset = 0; 1722 int ret; 1723 1724 do { 1725 /* Return error if we don't have space for new frag */ 1726 frg_cnt = skb_shinfo(skb)->nr_frags; 1727 if (frg_cnt >= MAX_SKB_FRAGS) 1728 return -EFAULT; 1729 1730 /* allocate a new page for next frag */ 1731 page = alloc_pages(sk->sk_allocation, 0); 1732 1733 /* If alloc_page fails just return failure and caller will 1734 * free previous allocated pages by doing kfree_skb() 1735 */ 1736 if (page == NULL) 1737 return -ENOMEM; 1738 1739 /* initialize the next frag */ 1740 sk->sk_sndmsg_page = page; 1741 sk->sk_sndmsg_off = 0; 1742 skb_fill_page_desc(skb, frg_cnt, page, 0, 0); 1743 skb->truesize += PAGE_SIZE; 1744 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc); 1745 1746 /* get the new initialized frag */ 1747 frg_cnt = skb_shinfo(skb)->nr_frags; 1748 frag = &skb_shinfo(skb)->frags[frg_cnt - 1]; 1749 1750 /* copy the user data to page */ 1751 left = PAGE_SIZE - frag->page_offset; 1752 copy = (length > left)? left : length; 1753 1754 ret = getfrag(from, (page_address(frag->page) + 1755 frag->page_offset + frag->size), 1756 offset, copy, 0, skb); 1757 if (ret < 0) 1758 return -EFAULT; 1759 1760 /* copy was successful so update the size parameters */ 1761 sk->sk_sndmsg_off += copy; 1762 frag->size += copy; 1763 skb->len += copy; 1764 skb->data_len += copy; 1765 offset += copy; 1766 length -= copy; 1767 1768 } while (length > 0); 1769 1770 return 0; 1771 } 1772 1773 void __init skb_init(void) 1774 { 1775 skbuff_head_cache = kmem_cache_create("skbuff_head_cache", 1776 sizeof(struct sk_buff), 1777 0, 1778 SLAB_HWCACHE_ALIGN, 1779 NULL, NULL); 1780 if (!skbuff_head_cache) 1781 panic("cannot create skbuff cache"); 1782 1783 skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache", 1784 (2*sizeof(struct sk_buff)) + 1785 sizeof(atomic_t), 1786 0, 1787 SLAB_HWCACHE_ALIGN, 1788 NULL, NULL); 1789 if (!skbuff_fclone_cache) 1790 panic("cannot create skbuff cache"); 1791 } 1792 1793 EXPORT_SYMBOL(___pskb_trim); 1794 EXPORT_SYMBOL(__kfree_skb); 1795 EXPORT_SYMBOL(__pskb_pull_tail); 1796 EXPORT_SYMBOL(__alloc_skb); 1797 EXPORT_SYMBOL(pskb_copy); 1798 EXPORT_SYMBOL(pskb_expand_head); 1799 EXPORT_SYMBOL(skb_checksum); 1800 EXPORT_SYMBOL(skb_clone); 1801 EXPORT_SYMBOL(skb_clone_fraglist); 1802 EXPORT_SYMBOL(skb_copy); 1803 EXPORT_SYMBOL(skb_copy_and_csum_bits); 1804 EXPORT_SYMBOL(skb_copy_and_csum_dev); 1805 EXPORT_SYMBOL(skb_copy_bits); 1806 EXPORT_SYMBOL(skb_copy_expand); 1807 EXPORT_SYMBOL(skb_over_panic); 1808 EXPORT_SYMBOL(skb_pad); 1809 EXPORT_SYMBOL(skb_realloc_headroom); 1810 EXPORT_SYMBOL(skb_under_panic); 1811 EXPORT_SYMBOL(skb_dequeue); 1812 EXPORT_SYMBOL(skb_dequeue_tail); 1813 EXPORT_SYMBOL(skb_insert); 1814 EXPORT_SYMBOL(skb_queue_purge); 1815 EXPORT_SYMBOL(skb_queue_head); 1816 EXPORT_SYMBOL(skb_queue_tail); 1817 EXPORT_SYMBOL(skb_unlink); 1818 EXPORT_SYMBOL(skb_append); 1819 EXPORT_SYMBOL(skb_split); 1820 EXPORT_SYMBOL(skb_prepare_seq_read); 1821 EXPORT_SYMBOL(skb_seq_read); 1822 EXPORT_SYMBOL(skb_abort_seq_read); 1823 EXPORT_SYMBOL(skb_find_text); 1824 EXPORT_SYMBOL(skb_append_datato_frags); 1825