git.oblomov.eu Git - linux-2.6/blob - net/xfrm/xfrm_algo.c

   1 /*
   2  * xfrm algorithm interface
   3  *
   4  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/pfkeyv2.h>
  15 #include <linux/crypto.h>
  16 #include <net/xfrm.h>
  17 #if defined(CONFIG_INET_AH) || defined(CONFIG_INET_AH_MODULE) || defined(CONFIG_INET6_AH) || defined(CONFIG_INET6_AH_MODULE)
  18 #include <net/ah.h>
  19 #endif
  20 #if defined(CONFIG_INET_ESP) || defined(CONFIG_INET_ESP_MODULE) || defined(CONFIG_INET6_ESP) || defined(CONFIG_INET6_ESP_MODULE)
  21 #include <net/esp.h>
  22 #endif
  23 #include <asm/scatterlist.h>
  24
  25 /*
  26  * Algorithms supported by IPsec.  These entries contain properties which
  27  * are used in key negotiation and xfrm processing, and are used to verify
  28  * that instantiated crypto transforms have correct parameters for IPsec
  29  * purposes.
  30  */
  31 static struct xfrm_algo_desc aalg_list[] = {
  32 {
  33         .name = "hmac(digest_null)",
  34         .compat = "digest_null",
  35
  36         .uinfo = {
  37                 .auth = {
  38                         .icv_truncbits = 0,
  39                         .icv_fullbits = 0,
  40                 }
  41         },
  42
  43         .desc = {
  44                 .sadb_alg_id = SADB_X_AALG_NULL,
  45                 .sadb_alg_ivlen = 0,
  46                 .sadb_alg_minbits = 0,
  47                 .sadb_alg_maxbits = 0
  48         }
  49 },
  50 {
  51         .name = "hmac(md5)",
  52         .compat = "md5",
  53
  54         .uinfo = {
  55                 .auth = {
  56                         .icv_truncbits = 96,
  57                         .icv_fullbits = 128,
  58                 }
  59         },
  60
  61         .desc = {
  62                 .sadb_alg_id = SADB_AALG_MD5HMAC,
  63                 .sadb_alg_ivlen = 0,
  64                 .sadb_alg_minbits = 128,
  65                 .sadb_alg_maxbits = 128
  66         }
  67 },
  68 {
  69         .name = "hmac(sha1)",
  70         .compat = "sha1",
  71
  72         .uinfo = {
  73                 .auth = {
  74                         .icv_truncbits = 96,
  75                         .icv_fullbits = 160,
  76                 }
  77         },
  78
  79         .desc = {
  80                 .sadb_alg_id = SADB_AALG_SHA1HMAC,
  81                 .sadb_alg_ivlen = 0,
  82                 .sadb_alg_minbits = 160,
  83                 .sadb_alg_maxbits = 160
  84         }
  85 },
  86 {
  87         .name = "hmac(sha256)",
  88         .compat = "sha256",
  89
  90         .uinfo = {
  91                 .auth = {
  92                         .icv_truncbits = 96,
  93                         .icv_fullbits = 256,
  94                 }
  95         },
  96
  97         .desc = {
  98                 .sadb_alg_id = SADB_X_AALG_SHA2_256HMAC,
  99                 .sadb_alg_ivlen = 0,
 100                 .sadb_alg_minbits = 256,
 101                 .sadb_alg_maxbits = 256
 102         }
 103 },
 104 {
 105         .name = "hmac(ripemd160)",
 106         .compat = "ripemd160",
 107
 108         .uinfo = {
 109                 .auth = {
 110                         .icv_truncbits = 96,
 111                         .icv_fullbits = 160,
 112                 }
 113         },
 114
 115         .desc = {
 116                 .sadb_alg_id = SADB_X_AALG_RIPEMD160HMAC,
 117                 .sadb_alg_ivlen = 0,
 118                 .sadb_alg_minbits = 160,
 119                 .sadb_alg_maxbits = 160
 120         }
 121 },
 122 {
 123         .name = "xcbc(aes)",
 124
 125         .uinfo = {
 126                 .auth = {
 127                         .icv_truncbits = 96,
 128                         .icv_fullbits = 128,
 129                 }
 130         },
 131
 132         .desc = {
 133                 .sadb_alg_id = SADB_X_AALG_AES_XCBC_MAC,
 134                 .sadb_alg_ivlen = 0,
 135                 .sadb_alg_minbits = 128,
 136                 .sadb_alg_maxbits = 128
 137         }
 138 },
 139 };
 140
 141 static struct xfrm_algo_desc ealg_list[] = {
 142 {
 143         .name = "ecb(cipher_null)",
 144         .compat = "cipher_null",
 145
 146         .uinfo = {
 147                 .encr = {
 148                         .blockbits = 8,
 149                         .defkeybits = 0,
 150                 }
 151         },
 152
 153         .desc = {
 154                 .sadb_alg_id =  SADB_EALG_NULL,
 155                 .sadb_alg_ivlen = 0,
 156                 .sadb_alg_minbits = 0,
 157                 .sadb_alg_maxbits = 0
 158         }
 159 },
 160 {
 161         .name = "cbc(des)",
 162         .compat = "des",
 163
 164         .uinfo = {
 165                 .encr = {
 166                         .blockbits = 64,
 167                         .defkeybits = 64,
 168                 }
 169         },
 170
 171         .desc = {
 172                 .sadb_alg_id = SADB_EALG_DESCBC,
 173                 .sadb_alg_ivlen = 8,
 174                 .sadb_alg_minbits = 64,
 175                 .sadb_alg_maxbits = 64
 176         }
 177 },
 178 {
 179         .name = "cbc(des3_ede)",
 180         .compat = "des3_ede",
 181
 182         .uinfo = {
 183                 .encr = {
 184                         .blockbits = 64,
 185                         .defkeybits = 192,
 186                 }
 187         },
 188
 189         .desc = {
 190                 .sadb_alg_id = SADB_EALG_3DESCBC,
 191                 .sadb_alg_ivlen = 8,
 192                 .sadb_alg_minbits = 192,
 193                 .sadb_alg_maxbits = 192
 194         }
 195 },
 196 {
 197         .name = "cbc(cast128)",
 198         .compat = "cast128",
 199
 200         .uinfo = {
 201                 .encr = {
 202                         .blockbits = 64,
 203                         .defkeybits = 128,
 204                 }
 205         },
 206
 207         .desc = {
 208                 .sadb_alg_id = SADB_X_EALG_CASTCBC,
 209                 .sadb_alg_ivlen = 8,
 210                 .sadb_alg_minbits = 40,
 211                 .sadb_alg_maxbits = 128
 212         }
 213 },
 214 {
 215         .name = "cbc(blowfish)",
 216         .compat = "blowfish",
 217
 218         .uinfo = {
 219                 .encr = {
 220                         .blockbits = 64,
 221                         .defkeybits = 128,
 222                 }
 223         },
 224
 225         .desc = {
 226                 .sadb_alg_id = SADB_X_EALG_BLOWFISHCBC,
 227                 .sadb_alg_ivlen = 8,
 228                 .sadb_alg_minbits = 40,
 229                 .sadb_alg_maxbits = 448
 230         }
 231 },
 232 {
 233         .name = "cbc(aes)",
 234         .compat = "aes",
 235
 236         .uinfo = {
 237                 .encr = {
 238                         .blockbits = 128,
 239                         .defkeybits = 128,
 240                 }
 241         },
 242
 243         .desc = {
 244                 .sadb_alg_id = SADB_X_EALG_AESCBC,
 245                 .sadb_alg_ivlen = 8,
 246                 .sadb_alg_minbits = 128,
 247                 .sadb_alg_maxbits = 256
 248         }
 249 },
 250 {
 251         .name = "cbc(serpent)",
 252         .compat = "serpent",
 253
 254         .uinfo = {
 255                 .encr = {
 256                         .blockbits = 128,
 257                         .defkeybits = 128,
 258                 }
 259         },
 260
 261         .desc = {
 262                 .sadb_alg_id = SADB_X_EALG_SERPENTCBC,
 263                 .sadb_alg_ivlen = 8,
 264                 .sadb_alg_minbits = 128,
 265                 .sadb_alg_maxbits = 256,
 266         }
 267 },
 268 {
 269         .name = "cbc(camellia)",
 270
 271         .uinfo = {
 272                 .encr = {
 273                         .blockbits = 128,
 274                         .defkeybits = 128,
 275                 }
 276         },
 277
 278         .desc = {
 279                 .sadb_alg_id = SADB_X_EALG_CAMELLIACBC,
 280                 .sadb_alg_ivlen = 8,
 281                 .sadb_alg_minbits = 128,
 282                 .sadb_alg_maxbits = 256
 283         }
 284 },
 285 {
 286         .name = "cbc(twofish)",
 287         .compat = "twofish",
 288
 289         .uinfo = {
 290                 .encr = {
 291                         .blockbits = 128,
 292                         .defkeybits = 128,
 293                 }
 294         },
 295
 296         .desc = {
 297                 .sadb_alg_id = SADB_X_EALG_TWOFISHCBC,
 298                 .sadb_alg_ivlen = 8,
 299                 .sadb_alg_minbits = 128,
 300                 .sadb_alg_maxbits = 256
 301         }
 302 },
 303 };
 304
 305 static struct xfrm_algo_desc calg_list[] = {
 306 {
 307         .name = "deflate",
 308         .uinfo = {
 309                 .comp = {
 310                         .threshold = 90,
 311                 }
 312         },
 313         .desc = { .sadb_alg_id = SADB_X_CALG_DEFLATE }
 314 },
 315 {
 316         .name = "lzs",
 317         .uinfo = {
 318                 .comp = {
 319                         .threshold = 90,
 320                 }
 321         },
 322         .desc = { .sadb_alg_id = SADB_X_CALG_LZS }
 323 },
 324 {
 325         .name = "lzjh",
 326         .uinfo = {
 327                 .comp = {
 328                         .threshold = 50,
 329                 }
 330         },
 331         .desc = { .sadb_alg_id = SADB_X_CALG_LZJH }
 332 },
 333 };
 334
 335 static inline int aalg_entries(void)
 336 {
 337         return ARRAY_SIZE(aalg_list);
 338 }
 339
 340 static inline int ealg_entries(void)
 341 {
 342         return ARRAY_SIZE(ealg_list);
 343 }
 344
 345 static inline int calg_entries(void)
 346 {
 347         return ARRAY_SIZE(calg_list);
 348 }
 349
 350 /* Todo: generic iterators */
 351 struct xfrm_algo_desc *xfrm_aalg_get_byid(int alg_id)
 352 {
 353         int i;
 354
 355         for (i = 0; i < aalg_entries(); i++) {
 356                 if (aalg_list[i].desc.sadb_alg_id == alg_id) {
 357                         if (aalg_list[i].available)
 358                                 return &aalg_list[i];
 359                         else
 360                                 break;
 361                 }
 362         }
 363         return NULL;
 364 }
 365 EXPORT_SYMBOL_GPL(xfrm_aalg_get_byid);
 366
 367 struct xfrm_algo_desc *xfrm_ealg_get_byid(int alg_id)
 368 {
 369         int i;
 370
 371         for (i = 0; i < ealg_entries(); i++) {
 372                 if (ealg_list[i].desc.sadb_alg_id == alg_id) {
 373                         if (ealg_list[i].available)
 374                                 return &ealg_list[i];
 375                         else
 376                                 break;
 377                 }
 378         }
 379         return NULL;
 380 }
 381 EXPORT_SYMBOL_GPL(xfrm_ealg_get_byid);
 382
 383 struct xfrm_algo_desc *xfrm_calg_get_byid(int alg_id)
 384 {
 385         int i;
 386
 387         for (i = 0; i < calg_entries(); i++) {
 388                 if (calg_list[i].desc.sadb_alg_id == alg_id) {
 389                         if (calg_list[i].available)
 390                                 return &calg_list[i];
 391                         else
 392                                 break;
 393                 }
 394         }
 395         return NULL;
 396 }
 397 EXPORT_SYMBOL_GPL(xfrm_calg_get_byid);
 398
 399 static struct xfrm_algo_desc *xfrm_get_byname(struct xfrm_algo_desc *list,
 400                                               int entries, u32 type, u32 mask,
 401                                               char *name, int probe)
 402 {
 403         int i, status;
 404
 405         if (!name)
 406                 return NULL;
 407
 408         for (i = 0; i < entries; i++) {
 409                 if (strcmp(name, list[i].name) &&
 410                     (!list[i].compat || strcmp(name, list[i].compat)))
 411                         continue;
 412
 413                 if (list[i].available)
 414                         return &list[i];
 415
 416                 if (!probe)
 417                         break;
 418
 419                 status = crypto_has_alg(list[i].name, type,
 420                                         mask | CRYPTO_ALG_ASYNC);
 421                 if (!status)
 422                         break;
 423
 424                 list[i].available = status;
 425                 return &list[i];
 426         }
 427         return NULL;
 428 }
 429
 430 struct xfrm_algo_desc *xfrm_aalg_get_byname(char *name, int probe)
 431 {
 432         return xfrm_get_byname(aalg_list, aalg_entries(),
 433                                CRYPTO_ALG_TYPE_HASH, CRYPTO_ALG_TYPE_HASH_MASK,
 434                                name, probe);
 435 }
 436 EXPORT_SYMBOL_GPL(xfrm_aalg_get_byname);
 437
 438 struct xfrm_algo_desc *xfrm_ealg_get_byname(char *name, int probe)
 439 {
 440         return xfrm_get_byname(ealg_list, ealg_entries(),
 441                                CRYPTO_ALG_TYPE_BLKCIPHER, CRYPTO_ALG_TYPE_MASK,
 442                                name, probe);
 443 }
 444 EXPORT_SYMBOL_GPL(xfrm_ealg_get_byname);
 445
 446 struct xfrm_algo_desc *xfrm_calg_get_byname(char *name, int probe)
 447 {
 448         return xfrm_get_byname(calg_list, calg_entries(),
 449                                CRYPTO_ALG_TYPE_COMPRESS, CRYPTO_ALG_TYPE_MASK,
 450                                name, probe);
 451 }
 452 EXPORT_SYMBOL_GPL(xfrm_calg_get_byname);
 453
 454 struct xfrm_algo_desc *xfrm_aalg_get_byidx(unsigned int idx)
 455 {
 456         if (idx >= aalg_entries())
 457                 return NULL;
 458
 459         return &aalg_list[idx];
 460 }
 461 EXPORT_SYMBOL_GPL(xfrm_aalg_get_byidx);
 462
 463 struct xfrm_algo_desc *xfrm_ealg_get_byidx(unsigned int idx)
 464 {
 465         if (idx >= ealg_entries())
 466                 return NULL;
 467
 468         return &ealg_list[idx];
 469 }
 470 EXPORT_SYMBOL_GPL(xfrm_ealg_get_byidx);
 471
 472 /*
 473  * Probe for the availability of crypto algorithms, and set the available
 474  * flag for any algorithms found on the system.  This is typically called by
 475  * pfkey during userspace SA add, update or register.
 476  */
 477 void xfrm_probe_algs(void)
 478 {
 479 #ifdef CONFIG_CRYPTO
 480         int i, status;
 481
 482         BUG_ON(in_softirq());
 483
 484         for (i = 0; i < aalg_entries(); i++) {
 485                 status = crypto_has_hash(aalg_list[i].name, 0,
 486                                          CRYPTO_ALG_ASYNC);
 487                 if (aalg_list[i].available != status)
 488                         aalg_list[i].available = status;
 489         }
 490
 491         for (i = 0; i < ealg_entries(); i++) {
 492                 status = crypto_has_blkcipher(ealg_list[i].name, 0,
 493                                               CRYPTO_ALG_ASYNC);
 494                 if (ealg_list[i].available != status)
 495                         ealg_list[i].available = status;
 496         }
 497
 498         for (i = 0; i < calg_entries(); i++) {
 499                 status = crypto_has_comp(calg_list[i].name, 0,
 500                                          CRYPTO_ALG_ASYNC);
 501                 if (calg_list[i].available != status)
 502                         calg_list[i].available = status;
 503         }
 504 #endif
 505 }
 506 EXPORT_SYMBOL_GPL(xfrm_probe_algs);
 507
 508 int xfrm_count_auth_supported(void)
 509 {
 510         int i, n;
 511
 512         for (i = 0, n = 0; i < aalg_entries(); i++)
 513                 if (aalg_list[i].available)
 514                         n++;
 515         return n;
 516 }
 517 EXPORT_SYMBOL_GPL(xfrm_count_auth_supported);
 518
 519 int xfrm_count_enc_supported(void)
 520 {
 521         int i, n;
 522
 523         for (i = 0, n = 0; i < ealg_entries(); i++)
 524                 if (ealg_list[i].available)
 525                         n++;
 526         return n;
 527 }
 528 EXPORT_SYMBOL_GPL(xfrm_count_enc_supported);
 529
 530 /* Move to common area: it is shared with AH. */
 531
 532 int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *desc,
 533                  int offset, int len, icv_update_fn_t icv_update)
 534 {
 535         int start = skb_headlen(skb);
 536         int i, copy = start - offset;
 537         int err;
 538         struct scatterlist sg;
 539
 540         /* Checksum header. */
 541         if (copy > 0) {
 542                 if (copy > len)
 543                         copy = len;
 544
 545                 sg.page = virt_to_page(skb->data + offset);
 546                 sg.offset = (unsigned long)(skb->data + offset) % PAGE_SIZE;
 547                 sg.length = copy;
 548
 549                 err = icv_update(desc, &sg, copy);
 550                 if (unlikely(err))
 551                         return err;
 552
 553                 if ((len -= copy) == 0)
 554                         return 0;
 555                 offset += copy;
 556         }
 557
 558         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 559                 int end;
 560
 561                 BUG_TRAP(start <= offset + len);
 562
 563                 end = start + skb_shinfo(skb)->frags[i].size;
 564                 if ((copy = end - offset) > 0) {
 565                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 566
 567                         if (copy > len)
 568                                 copy = len;
 569
 570                         sg.page = frag->page;
 571                         sg.offset = frag->page_offset + offset-start;
 572                         sg.length = copy;
 573
 574                         err = icv_update(desc, &sg, copy);
 575                         if (unlikely(err))
 576                                 return err;
 577
 578                         if (!(len -= copy))
 579                                 return 0;
 580                         offset += copy;
 581                 }
 582                 start = end;
 583         }
 584
 585         if (skb_shinfo(skb)->frag_list) {
 586                 struct sk_buff *list = skb_shinfo(skb)->frag_list;
 587
 588                 for (; list; list = list->next) {
 589                         int end;
 590
 591                         BUG_TRAP(start <= offset + len);
 592
 593                         end = start + list->len;
 594                         if ((copy = end - offset) > 0) {
 595                                 if (copy > len)
 596                                         copy = len;
 597                                 err = skb_icv_walk(list, desc, offset-start,
 598                                                    copy, icv_update);
 599                                 if (unlikely(err))
 600                                         return err;
 601                                 if ((len -= copy) == 0)
 602                                         return 0;
 603                                 offset += copy;
 604                         }
 605                         start = end;
 606                 }
 607         }
 608         BUG_ON(len);
 609         return 0;
 610 }
 611 EXPORT_SYMBOL_GPL(skb_icv_walk);
 612
 613 #if defined(CONFIG_INET_ESP) || defined(CONFIG_INET_ESP_MODULE) || defined(CONFIG_INET6_ESP) || defined(CONFIG_INET6_ESP_MODULE)
 614
 615 /* Looking generic it is not used in another places. */
 616
 617 int
 618 skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
 619 {
 620         int start = skb_headlen(skb);
 621         int i, copy = start - offset;
 622         int elt = 0;
 623
 624         if (copy > 0) {
 625                 if (copy > len)
 626                         copy = len;
 627                 sg[elt].page = virt_to_page(skb->data + offset);
 628                 sg[elt].offset = (unsigned long)(skb->data + offset) % PAGE_SIZE;
 629                 sg[elt].length = copy;
 630                 elt++;
 631                 if ((len -= copy) == 0)
 632                         return elt;
 633                 offset += copy;
 634         }
 635
 636         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 637                 int end;
 638
 639                 BUG_TRAP(start <= offset + len);
 640
 641                 end = start + skb_shinfo(skb)->frags[i].size;
 642                 if ((copy = end - offset) > 0) {
 643                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 644
 645                         if (copy > len)
 646                                 copy = len;
 647                         sg[elt].page = frag->page;
 648                         sg[elt].offset = frag->page_offset+offset-start;
 649                         sg[elt].length = copy;
 650                         elt++;
 651                         if (!(len -= copy))
 652                                 return elt;
 653                         offset += copy;
 654                 }
 655                 start = end;
 656         }
 657
 658         if (skb_shinfo(skb)->frag_list) {
 659                 struct sk_buff *list = skb_shinfo(skb)->frag_list;
 660
 661                 for (; list; list = list->next) {
 662                         int end;
 663
 664                         BUG_TRAP(start <= offset + len);
 665
 666                         end = start + list->len;
 667                         if ((copy = end - offset) > 0) {
 668                                 if (copy > len)
 669                                         copy = len;
 670                                 elt += skb_to_sgvec(list, sg+elt, offset - start, copy);
 671                                 if ((len -= copy) == 0)
 672                                         return elt;
 673                                 offset += copy;
 674                         }
 675                         start = end;
 676                 }
 677         }
 678         BUG_ON(len);
 679         return elt;
 680 }
 681 EXPORT_SYMBOL_GPL(skb_to_sgvec);
 682
 683 /* Check that skb data bits are writable. If they are not, copy data
 684  * to newly created private area. If "tailbits" is given, make sure that
 685  * tailbits bytes beyond current end of skb are writable.
 686  *
 687  * Returns amount of elements of scatterlist to load for subsequent
 688  * transformations and pointer to writable trailer skb.
 689  */
 690
 691 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
 692 {
 693         int copyflag;
 694         int elt;
 695         struct sk_buff *skb1, **skb_p;
 696
 697         /* If skb is cloned or its head is paged, reallocate
 698          * head pulling out all the pages (pages are considered not writable
 699          * at the moment even if they are anonymous).
 700          */
 701         if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
 702             __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
 703                 return -ENOMEM;
 704
 705         /* Easy case. Most of packets will go this way. */
 706         if (!skb_shinfo(skb)->frag_list) {
 707                 /* A little of trouble, not enough of space for trailer.
 708                  * This should not happen, when stack is tuned to generate
 709                  * good frames. OK, on miss we reallocate and reserve even more
 710                  * space, 128 bytes is fair. */
 711
 712                 if (skb_tailroom(skb) < tailbits &&
 713                     pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
 714                         return -ENOMEM;
 715
 716                 /* Voila! */
 717                 *trailer = skb;
 718                 return 1;
 719         }
 720
 721         /* Misery. We are in troubles, going to mincer fragments... */
 722
 723         elt = 1;
 724         skb_p = &skb_shinfo(skb)->frag_list;
 725         copyflag = 0;
 726
 727         while ((skb1 = *skb_p) != NULL) {
 728                 int ntail = 0;
 729
 730                 /* The fragment is partially pulled by someone,
 731                  * this can happen on input. Copy it and everything
 732                  * after it. */
 733
 734                 if (skb_shared(skb1))
 735                         copyflag = 1;
 736
 737                 /* If the skb is the last, worry about trailer. */
 738
 739                 if (skb1->next == NULL && tailbits) {
 740                         if (skb_shinfo(skb1)->nr_frags ||
 741                             skb_shinfo(skb1)->frag_list ||
 742                             skb_tailroom(skb1) < tailbits)
 743                                 ntail = tailbits + 128;
 744                 }
 745
 746                 if (copyflag ||
 747                     skb_cloned(skb1) ||
 748                     ntail ||
 749                     skb_shinfo(skb1)->nr_frags ||
 750                     skb_shinfo(skb1)->frag_list) {
 751                         struct sk_buff *skb2;
 752
 753                         /* Fuck, we are miserable poor guys... */
 754                         if (ntail == 0)
 755                                 skb2 = skb_copy(skb1, GFP_ATOMIC);
 756                         else
 757                                 skb2 = skb_copy_expand(skb1,
 758                                                        skb_headroom(skb1),
 759                                                        ntail,
 760                                                        GFP_ATOMIC);
 761                         if (unlikely(skb2 == NULL))
 762                                 return -ENOMEM;
 763
 764                         if (skb1->sk)
 765                                 skb_set_owner_w(skb2, skb1->sk);
 766
 767                         /* Looking around. Are we still alive?
 768                          * OK, link new skb, drop old one */
 769
 770                         skb2->next = skb1->next;
 771                         *skb_p = skb2;
 772                         kfree_skb(skb1);
 773                         skb1 = skb2;
 774                 }
 775                 elt++;
 776                 *trailer = skb1;
 777                 skb_p = &skb1->next;
 778         }
 779
 780         return elt;
 781 }
 782 EXPORT_SYMBOL_GPL(skb_cow_data);
 783
 784 void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
 785 {
 786         if (tail != skb) {
 787                 skb->data_len += len;
 788                 skb->len += len;
 789         }
 790         return skb_put(tail, len);
 791 }
 792 EXPORT_SYMBOL_GPL(pskb_put);
 793 #endif