err.no 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 <linux/scatterlist.h>
  17 #include <net/xfrm.h>
  18 #if defined(CONFIG_INET_AH) || defined(CONFIG_INET_AH_MODULE) || defined(CONFIG_INET6_AH) || defined(CONFIG_INET6_AH_MODULE)
  19 #include <net/ah.h>
  20 #endif
  21 #if defined(CONFIG_INET_ESP) || defined(CONFIG_INET_ESP_MODULE) || defined(CONFIG_INET6_ESP) || defined(CONFIG_INET6_ESP_MODULE)
  22 #include <net/esp.h>
  23 #endif
  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 aead_list[] = {
  32 {
  33         .name = "rfc4106(gcm(aes))",
  34
  35         .uinfo = {
  36                 .aead = {
  37                         .icv_truncbits = 64,
  38                 }
  39         },
  40
  41         .desc = {
  42                 .sadb_alg_id = SADB_X_EALG_AES_GCM_ICV8,
  43                 .sadb_alg_ivlen = 8,
  44                 .sadb_alg_minbits = 128,
  45                 .sadb_alg_maxbits = 256
  46         }
  47 },
  48 {
  49         .name = "rfc4106(gcm(aes))",
  50
  51         .uinfo = {
  52                 .aead = {
  53                         .icv_truncbits = 96,
  54                 }
  55         },
  56
  57         .desc = {
  58                 .sadb_alg_id = SADB_X_EALG_AES_GCM_ICV12,
  59                 .sadb_alg_ivlen = 8,
  60                 .sadb_alg_minbits = 128,
  61                 .sadb_alg_maxbits = 256
  62         }
  63 },
  64 {
  65         .name = "rfc4106(gcm(aes))",
  66
  67         .uinfo = {
  68                 .aead = {
  69                         .icv_truncbits = 128,
  70                 }
  71         },
  72
  73         .desc = {
  74                 .sadb_alg_id = SADB_X_EALG_AES_GCM_ICV16,
  75                 .sadb_alg_ivlen = 8,
  76                 .sadb_alg_minbits = 128,
  77                 .sadb_alg_maxbits = 256
  78         }
  79 },
  80 {
  81         .name = "rfc4309(ccm(aes))",
  82
  83         .uinfo = {
  84                 .aead = {
  85                         .icv_truncbits = 64,
  86                 }
  87         },
  88
  89         .desc = {
  90                 .sadb_alg_id = SADB_X_EALG_AES_CCM_ICV8,
  91                 .sadb_alg_ivlen = 8,
  92                 .sadb_alg_minbits = 128,
  93                 .sadb_alg_maxbits = 256
  94         }
  95 },
  96 {
  97         .name = "rfc4309(ccm(aes))",
  98
  99         .uinfo = {
 100                 .aead = {
 101                         .icv_truncbits = 96,
 102                 }
 103         },
 104
 105         .desc = {
 106                 .sadb_alg_id = SADB_X_EALG_AES_CCM_ICV12,
 107                 .sadb_alg_ivlen = 8,
 108                 .sadb_alg_minbits = 128,
 109                 .sadb_alg_maxbits = 256
 110         }
 111 },
 112 {
 113         .name = "rfc4309(ccm(aes))",
 114
 115         .uinfo = {
 116                 .aead = {
 117                         .icv_truncbits = 128,
 118                 }
 119         },
 120
 121         .desc = {
 122                 .sadb_alg_id = SADB_X_EALG_AES_CCM_ICV16,
 123                 .sadb_alg_ivlen = 8,
 124                 .sadb_alg_minbits = 128,
 125                 .sadb_alg_maxbits = 256
 126         }
 127 },
 128 };
 129
 130 static struct xfrm_algo_desc aalg_list[] = {
 131 {
 132         .name = "digest_null",
 133
 134         .uinfo = {
 135                 .auth = {
 136                         .icv_truncbits = 0,
 137                         .icv_fullbits = 0,
 138                 }
 139         },
 140
 141         .desc = {
 142                 .sadb_alg_id = SADB_X_AALG_NULL,
 143                 .sadb_alg_ivlen = 0,
 144                 .sadb_alg_minbits = 0,
 145                 .sadb_alg_maxbits = 0
 146         }
 147 },
 148 {
 149         .name = "hmac(md5)",
 150         .compat = "md5",
 151
 152         .uinfo = {
 153                 .auth = {
 154                         .icv_truncbits = 96,
 155                         .icv_fullbits = 128,
 156                 }
 157         },
 158
 159         .desc = {
 160                 .sadb_alg_id = SADB_AALG_MD5HMAC,
 161                 .sadb_alg_ivlen = 0,
 162                 .sadb_alg_minbits = 128,
 163                 .sadb_alg_maxbits = 128
 164         }
 165 },
 166 {
 167         .name = "hmac(sha1)",
 168         .compat = "sha1",
 169
 170         .uinfo = {
 171                 .auth = {
 172                         .icv_truncbits = 96,
 173                         .icv_fullbits = 160,
 174                 }
 175         },
 176
 177         .desc = {
 178                 .sadb_alg_id = SADB_AALG_SHA1HMAC,
 179                 .sadb_alg_ivlen = 0,
 180                 .sadb_alg_minbits = 160,
 181                 .sadb_alg_maxbits = 160
 182         }
 183 },
 184 {
 185         .name = "hmac(sha256)",
 186         .compat = "sha256",
 187
 188         .uinfo = {
 189                 .auth = {
 190                         .icv_truncbits = 96,
 191                         .icv_fullbits = 256,
 192                 }
 193         },
 194
 195         .desc = {
 196                 .sadb_alg_id = SADB_X_AALG_SHA2_256HMAC,
 197                 .sadb_alg_ivlen = 0,
 198                 .sadb_alg_minbits = 256,
 199                 .sadb_alg_maxbits = 256
 200         }
 201 },
 202 {
 203         .name = "hmac(rmd160)",
 204         .compat = "rmd160",
 205
 206         .uinfo = {
 207                 .auth = {
 208                         .icv_truncbits = 96,
 209                         .icv_fullbits = 160,
 210                 }
 211         },
 212
 213         .desc = {
 214                 .sadb_alg_id = SADB_X_AALG_RIPEMD160HMAC,
 215                 .sadb_alg_ivlen = 0,
 216                 .sadb_alg_minbits = 160,
 217                 .sadb_alg_maxbits = 160
 218         }
 219 },
 220 {
 221         .name = "xcbc(aes)",
 222
 223         .uinfo = {
 224                 .auth = {
 225                         .icv_truncbits = 96,
 226                         .icv_fullbits = 128,
 227                 }
 228         },
 229
 230         .desc = {
 231                 .sadb_alg_id = SADB_X_AALG_AES_XCBC_MAC,
 232                 .sadb_alg_ivlen = 0,
 233                 .sadb_alg_minbits = 128,
 234                 .sadb_alg_maxbits = 128
 235         }
 236 },
 237 };
 238
 239 static struct xfrm_algo_desc ealg_list[] = {
 240 {
 241         .name = "ecb(cipher_null)",
 242         .compat = "cipher_null",
 243
 244         .uinfo = {
 245                 .encr = {
 246                         .blockbits = 8,
 247                         .defkeybits = 0,
 248                 }
 249         },
 250
 251         .desc = {
 252                 .sadb_alg_id =  SADB_EALG_NULL,
 253                 .sadb_alg_ivlen = 0,
 254                 .sadb_alg_minbits = 0,
 255                 .sadb_alg_maxbits = 0
 256         }
 257 },
 258 {
 259         .name = "cbc(des)",
 260         .compat = "des",
 261
 262         .uinfo = {
 263                 .encr = {
 264                         .blockbits = 64,
 265                         .defkeybits = 64,
 266                 }
 267         },
 268
 269         .desc = {
 270                 .sadb_alg_id = SADB_EALG_DESCBC,
 271                 .sadb_alg_ivlen = 8,
 272                 .sadb_alg_minbits = 64,
 273                 .sadb_alg_maxbits = 64
 274         }
 275 },
 276 {
 277         .name = "cbc(des3_ede)",
 278         .compat = "des3_ede",
 279
 280         .uinfo = {
 281                 .encr = {
 282                         .blockbits = 64,
 283                         .defkeybits = 192,
 284                 }
 285         },
 286
 287         .desc = {
 288                 .sadb_alg_id = SADB_EALG_3DESCBC,
 289                 .sadb_alg_ivlen = 8,
 290                 .sadb_alg_minbits = 192,
 291                 .sadb_alg_maxbits = 192
 292         }
 293 },
 294 {
 295         .name = "cbc(cast128)",
 296         .compat = "cast128",
 297
 298         .uinfo = {
 299                 .encr = {
 300                         .blockbits = 64,
 301                         .defkeybits = 128,
 302                 }
 303         },
 304
 305         .desc = {
 306                 .sadb_alg_id = SADB_X_EALG_CASTCBC,
 307                 .sadb_alg_ivlen = 8,
 308                 .sadb_alg_minbits = 40,
 309                 .sadb_alg_maxbits = 128
 310         }
 311 },
 312 {
 313         .name = "cbc(blowfish)",
 314         .compat = "blowfish",
 315
 316         .uinfo = {
 317                 .encr = {
 318                         .blockbits = 64,
 319                         .defkeybits = 128,
 320                 }
 321         },
 322
 323         .desc = {
 324                 .sadb_alg_id = SADB_X_EALG_BLOWFISHCBC,
 325                 .sadb_alg_ivlen = 8,
 326                 .sadb_alg_minbits = 40,
 327                 .sadb_alg_maxbits = 448
 328         }
 329 },
 330 {
 331         .name = "cbc(aes)",
 332         .compat = "aes",
 333
 334         .uinfo = {
 335                 .encr = {
 336                         .blockbits = 128,
 337                         .defkeybits = 128,
 338                 }
 339         },
 340
 341         .desc = {
 342                 .sadb_alg_id = SADB_X_EALG_AESCBC,
 343                 .sadb_alg_ivlen = 8,
 344                 .sadb_alg_minbits = 128,
 345                 .sadb_alg_maxbits = 256
 346         }
 347 },
 348 {
 349         .name = "cbc(serpent)",
 350         .compat = "serpent",
 351
 352         .uinfo = {
 353                 .encr = {
 354                         .blockbits = 128,
 355                         .defkeybits = 128,
 356                 }
 357         },
 358
 359         .desc = {
 360                 .sadb_alg_id = SADB_X_EALG_SERPENTCBC,
 361                 .sadb_alg_ivlen = 8,
 362                 .sadb_alg_minbits = 128,
 363                 .sadb_alg_maxbits = 256,
 364         }
 365 },
 366 {
 367         .name = "cbc(camellia)",
 368
 369         .uinfo = {
 370                 .encr = {
 371                         .blockbits = 128,
 372                         .defkeybits = 128,
 373                 }
 374         },
 375
 376         .desc = {
 377                 .sadb_alg_id = SADB_X_EALG_CAMELLIACBC,
 378                 .sadb_alg_ivlen = 8,
 379                 .sadb_alg_minbits = 128,
 380                 .sadb_alg_maxbits = 256
 381         }
 382 },
 383 {
 384         .name = "cbc(twofish)",
 385         .compat = "twofish",
 386
 387         .uinfo = {
 388                 .encr = {
 389                         .blockbits = 128,
 390                         .defkeybits = 128,
 391                 }
 392         },
 393
 394         .desc = {
 395                 .sadb_alg_id = SADB_X_EALG_TWOFISHCBC,
 396                 .sadb_alg_ivlen = 8,
 397                 .sadb_alg_minbits = 128,
 398                 .sadb_alg_maxbits = 256
 399         }
 400 },
 401 {
 402         .name = "rfc3686(ctr(aes))",
 403
 404         .uinfo = {
 405                 .encr = {
 406                         .blockbits = 128,
 407                         .defkeybits = 160, /* 128-bit key + 32-bit nonce */
 408                 }
 409         },
 410
 411         .desc = {
 412                 .sadb_alg_id = SADB_X_EALG_AESCTR,
 413                 .sadb_alg_ivlen = 8,
 414                 .sadb_alg_minbits = 128,
 415                 .sadb_alg_maxbits = 256
 416         }
 417 },
 418 };
 419
 420 static struct xfrm_algo_desc calg_list[] = {
 421 {
 422         .name = "deflate",
 423         .uinfo = {
 424                 .comp = {
 425                         .threshold = 90,
 426                 }
 427         },
 428         .desc = { .sadb_alg_id = SADB_X_CALG_DEFLATE }
 429 },
 430 {
 431         .name = "lzs",
 432         .uinfo = {
 433                 .comp = {
 434                         .threshold = 90,
 435                 }
 436         },
 437         .desc = { .sadb_alg_id = SADB_X_CALG_LZS }
 438 },
 439 {
 440         .name = "lzjh",
 441         .uinfo = {
 442                 .comp = {
 443                         .threshold = 50,
 444                 }
 445         },
 446         .desc = { .sadb_alg_id = SADB_X_CALG_LZJH }
 447 },
 448 };
 449
 450 static inline int aead_entries(void)
 451 {
 452         return ARRAY_SIZE(aead_list);
 453 }
 454
 455 static inline int aalg_entries(void)
 456 {
 457         return ARRAY_SIZE(aalg_list);
 458 }
 459
 460 static inline int ealg_entries(void)
 461 {
 462         return ARRAY_SIZE(ealg_list);
 463 }
 464
 465 static inline int calg_entries(void)
 466 {
 467         return ARRAY_SIZE(calg_list);
 468 }
 469
 470 struct xfrm_algo_list {
 471         struct xfrm_algo_desc *algs;
 472         int entries;
 473         u32 type;
 474         u32 mask;
 475 };
 476
 477 static const struct xfrm_algo_list xfrm_aead_list = {
 478         .algs = aead_list,
 479         .entries = ARRAY_SIZE(aead_list),
 480         .type = CRYPTO_ALG_TYPE_AEAD,
 481         .mask = CRYPTO_ALG_TYPE_MASK,
 482 };
 483
 484 static const struct xfrm_algo_list xfrm_aalg_list = {
 485         .algs = aalg_list,
 486         .entries = ARRAY_SIZE(aalg_list),
 487         .type = CRYPTO_ALG_TYPE_HASH,
 488         .mask = CRYPTO_ALG_TYPE_HASH_MASK,
 489 };
 490
 491 static const struct xfrm_algo_list xfrm_ealg_list = {
 492         .algs = ealg_list,
 493         .entries = ARRAY_SIZE(ealg_list),
 494         .type = CRYPTO_ALG_TYPE_BLKCIPHER,
 495         .mask = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
 496 };
 497
 498 static const struct xfrm_algo_list xfrm_calg_list = {
 499         .algs = calg_list,
 500         .entries = ARRAY_SIZE(calg_list),
 501         .type = CRYPTO_ALG_TYPE_COMPRESS,
 502         .mask = CRYPTO_ALG_TYPE_MASK,
 503 };
 504
 505 static struct xfrm_algo_desc *xfrm_find_algo(
 506         const struct xfrm_algo_list *algo_list,
 507         int match(const struct xfrm_algo_desc *entry, const void *data),
 508         const void *data, int probe)
 509 {
 510         struct xfrm_algo_desc *list = algo_list->algs;
 511         int i, status;
 512
 513         for (i = 0; i < algo_list->entries; i++) {
 514                 if (!match(list + i, data))
 515                         continue;
 516
 517                 if (list[i].available)
 518                         return &list[i];
 519
 520                 if (!probe)
 521                         break;
 522
 523                 status = crypto_has_alg(list[i].name, algo_list->type,
 524                                         algo_list->mask);
 525                 if (!status)
 526                         break;
 527
 528                 list[i].available = status;
 529                 return &list[i];
 530         }
 531         return NULL;
 532 }
 533
 534 static int xfrm_alg_id_match(const struct xfrm_algo_desc *entry,
 535                              const void *data)
 536 {
 537         return entry->desc.sadb_alg_id == (unsigned long)data;
 538 }
 539
 540 struct xfrm_algo_desc *xfrm_aalg_get_byid(int alg_id)
 541 {
 542         return xfrm_find_algo(&xfrm_aalg_list, xfrm_alg_id_match,
 543                               (void *)(unsigned long)alg_id, 1);
 544 }
 545 EXPORT_SYMBOL_GPL(xfrm_aalg_get_byid);
 546
 547 struct xfrm_algo_desc *xfrm_ealg_get_byid(int alg_id)
 548 {
 549         return xfrm_find_algo(&xfrm_ealg_list, xfrm_alg_id_match,
 550                               (void *)(unsigned long)alg_id, 1);
 551 }
 552 EXPORT_SYMBOL_GPL(xfrm_ealg_get_byid);
 553
 554 struct xfrm_algo_desc *xfrm_calg_get_byid(int alg_id)
 555 {
 556         return xfrm_find_algo(&xfrm_calg_list, xfrm_alg_id_match,
 557                               (void *)(unsigned long)alg_id, 1);
 558 }
 559 EXPORT_SYMBOL_GPL(xfrm_calg_get_byid);
 560
 561 static int xfrm_alg_name_match(const struct xfrm_algo_desc *entry,
 562                                const void *data)
 563 {
 564         const char *name = data;
 565
 566         return name && (!strcmp(name, entry->name) ||
 567                         (entry->compat && !strcmp(name, entry->compat)));
 568 }
 569
 570 struct xfrm_algo_desc *xfrm_aalg_get_byname(char *name, int probe)
 571 {
 572         return xfrm_find_algo(&xfrm_aalg_list, xfrm_alg_name_match, name,
 573                               probe);
 574 }
 575 EXPORT_SYMBOL_GPL(xfrm_aalg_get_byname);
 576
 577 struct xfrm_algo_desc *xfrm_ealg_get_byname(char *name, int probe)
 578 {
 579         return xfrm_find_algo(&xfrm_ealg_list, xfrm_alg_name_match, name,
 580                               probe);
 581 }
 582 EXPORT_SYMBOL_GPL(xfrm_ealg_get_byname);
 583
 584 struct xfrm_algo_desc *xfrm_calg_get_byname(char *name, int probe)
 585 {
 586         return xfrm_find_algo(&xfrm_calg_list, xfrm_alg_name_match, name,
 587                               probe);
 588 }
 589 EXPORT_SYMBOL_GPL(xfrm_calg_get_byname);
 590
 591 struct xfrm_aead_name {
 592         const char *name;
 593         int icvbits;
 594 };
 595
 596 static int xfrm_aead_name_match(const struct xfrm_algo_desc *entry,
 597                                 const void *data)
 598 {
 599         const struct xfrm_aead_name *aead = data;
 600         const char *name = aead->name;
 601
 602         return aead->icvbits == entry->uinfo.aead.icv_truncbits && name &&
 603                !strcmp(name, entry->name);
 604 }
 605
 606 struct xfrm_algo_desc *xfrm_aead_get_byname(char *name, int icv_len, int probe)
 607 {
 608         struct xfrm_aead_name data = {
 609                 .name = name,
 610                 .icvbits = icv_len,
 611         };
 612
 613         return xfrm_find_algo(&xfrm_aead_list, xfrm_aead_name_match, &data,
 614                               probe);
 615 }
 616 EXPORT_SYMBOL_GPL(xfrm_aead_get_byname);
 617
 618 struct xfrm_algo_desc *xfrm_aalg_get_byidx(unsigned int idx)
 619 {
 620         if (idx >= aalg_entries())
 621                 return NULL;
 622
 623         return &aalg_list[idx];
 624 }
 625 EXPORT_SYMBOL_GPL(xfrm_aalg_get_byidx);
 626
 627 struct xfrm_algo_desc *xfrm_ealg_get_byidx(unsigned int idx)
 628 {
 629         if (idx >= ealg_entries())
 630                 return NULL;
 631
 632         return &ealg_list[idx];
 633 }
 634 EXPORT_SYMBOL_GPL(xfrm_ealg_get_byidx);
 635
 636 /*
 637  * Probe for the availability of crypto algorithms, and set the available
 638  * flag for any algorithms found on the system.  This is typically called by
 639  * pfkey during userspace SA add, update or register.
 640  */
 641 void xfrm_probe_algs(void)
 642 {
 643         int i, status;
 644
 645         BUG_ON(in_softirq());
 646
 647         for (i = 0; i < aalg_entries(); i++) {
 648                 status = crypto_has_hash(aalg_list[i].name, 0,
 649                                          CRYPTO_ALG_ASYNC);
 650                 if (aalg_list[i].available != status)
 651                         aalg_list[i].available = status;
 652         }
 653
 654         for (i = 0; i < ealg_entries(); i++) {
 655                 status = crypto_has_blkcipher(ealg_list[i].name, 0,
 656                                               CRYPTO_ALG_ASYNC);
 657                 if (ealg_list[i].available != status)
 658                         ealg_list[i].available = status;
 659         }
 660
 661         for (i = 0; i < calg_entries(); i++) {
 662                 status = crypto_has_comp(calg_list[i].name, 0,
 663                                          CRYPTO_ALG_ASYNC);
 664                 if (calg_list[i].available != status)
 665                         calg_list[i].available = status;
 666         }
 667 }
 668 EXPORT_SYMBOL_GPL(xfrm_probe_algs);
 669
 670 int xfrm_count_auth_supported(void)
 671 {
 672         int i, n;
 673
 674         for (i = 0, n = 0; i < aalg_entries(); i++)
 675                 if (aalg_list[i].available)
 676                         n++;
 677         return n;
 678 }
 679 EXPORT_SYMBOL_GPL(xfrm_count_auth_supported);
 680
 681 int xfrm_count_enc_supported(void)
 682 {
 683         int i, n;
 684
 685         for (i = 0, n = 0; i < ealg_entries(); i++)
 686                 if (ealg_list[i].available)
 687                         n++;
 688         return n;
 689 }
 690 EXPORT_SYMBOL_GPL(xfrm_count_enc_supported);
 691
 692 /* Move to common area: it is shared with AH. */
 693
 694 int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *desc,
 695                  int offset, int len, icv_update_fn_t icv_update)
 696 {
 697         int start = skb_headlen(skb);
 698         int i, copy = start - offset;
 699         int err;
 700         struct scatterlist sg;
 701
 702         /* Checksum header. */
 703         if (copy > 0) {
 704                 if (copy > len)
 705                         copy = len;
 706
 707                 sg_init_one(&sg, skb->data + offset, copy);
 708
 709                 err = icv_update(desc, &sg, copy);
 710                 if (unlikely(err))
 711                         return err;
 712
 713                 if ((len -= copy) == 0)
 714                         return 0;
 715                 offset += copy;
 716         }
 717
 718         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 719                 int end;
 720
 721                 WARN_ON(start > offset + len);
 722
 723                 end = start + skb_shinfo(skb)->frags[i].size;
 724                 if ((copy = end - offset) > 0) {
 725                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 726
 727                         if (copy > len)
 728                                 copy = len;
 729
 730                         sg_init_table(&sg, 1);
 731                         sg_set_page(&sg, frag->page, copy,
 732                                     frag->page_offset + offset-start);
 733
 734                         err = icv_update(desc, &sg, copy);
 735                         if (unlikely(err))
 736                                 return err;
 737
 738                         if (!(len -= copy))
 739                                 return 0;
 740                         offset += copy;
 741                 }
 742                 start = end;
 743         }
 744
 745         if (skb_shinfo(skb)->frag_list) {
 746                 struct sk_buff *list = skb_shinfo(skb)->frag_list;
 747
 748                 for (; list; list = list->next) {
 749                         int end;
 750
 751                         WARN_ON(start > offset + len);
 752
 753                         end = start + list->len;
 754                         if ((copy = end - offset) > 0) {
 755                                 if (copy > len)
 756                                         copy = len;
 757                                 err = skb_icv_walk(list, desc, offset-start,
 758                                                    copy, icv_update);
 759                                 if (unlikely(err))
 760                                         return err;
 761                                 if ((len -= copy) == 0)
 762                                         return 0;
 763                                 offset += copy;
 764                         }
 765                         start = end;
 766                 }
 767         }
 768         BUG_ON(len);
 769         return 0;
 770 }
 771 EXPORT_SYMBOL_GPL(skb_icv_walk);
 772
 773 #if defined(CONFIG_INET_ESP) || defined(CONFIG_INET_ESP_MODULE) || defined(CONFIG_INET6_ESP) || defined(CONFIG_INET6_ESP_MODULE)
 774
 775 void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
 776 {
 777         if (tail != skb) {
 778                 skb->data_len += len;
 779                 skb->len += len;
 780         }
 781         return skb_put(tail, len);
 782 }
 783 EXPORT_SYMBOL_GPL(pskb_put);
 784 #endif