The Tcpdump Group git mirrors - tcpdump/blob - print-esp.c

   1 /*      $NetBSD: print-ah.c,v 1.4 1996/05/20 00:41:16 fvdl Exp $        */
   2
   3 /*
   4  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that: (1) source code distributions
   9  * retain the above copyright notice and this paragraph in its entirety, (2)
  10  * distributions including binary code include the above copyright notice and
  11  * this paragraph in its entirety in the documentation or other materials
  12  * provided with the distribution, and (3) all advertising materials mentioning
  13  * features or use of this software display the following acknowledgement:
  14  * ``This product includes software developed by the University of California,
  15  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  16  * the University nor the names of its contributors may be used to endorse
  17  * or promote products derived from this software without specific prior
  18  * written permission.
  19  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  20  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  22  */
  23
  24 #define NETDISSECT_REWORKED
  25 #ifdef HAVE_CONFIG_H
  26 #include "config.h"
  27 #endif
  28
  29 #include <tcpdump-stdinc.h>
  30
  31 #include <string.h>
  32 #include <stdlib.h>
  33
  34 /* Any code in this file that depends on HAVE_LIBCRYPTO depends on
  35  * HAVE_OPENSSL_EVP_H too. Undefining the former when the latter isn't defined
  36  * is the simplest way of handling the dependency.
  37  */
  38 #ifdef HAVE_LIBCRYPTO
  39 #ifdef HAVE_OPENSSL_EVP_H
  40 #include <openssl/evp.h>
  41 #else
  42 #undef HAVE_LIBCRYPTO
  43 #endif
  44 #endif
  45
  46 #include "ip.h"
  47 #ifdef INET6
  48 #include "ip6.h"
  49 #endif
  50
  51 #include "interface.h"
  52 #include "extract.h"
  53
  54 /*
  55  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
  56  * All rights reserved.
  57  *
  58  * Redistribution and use in source and binary forms, with or without
  59  * modification, are permitted provided that the following conditions
  60  * are met:
  61  * 1. Redistributions of source code must retain the above copyright
  62  *    notice, this list of conditions and the following disclaimer.
  63  * 2. Redistributions in binary form must reproduce the above copyright
  64  *    notice, this list of conditions and the following disclaimer in the
  65  *    documentation and/or other materials provided with the distribution.
  66  * 3. Neither the name of the project nor the names of its contributors
  67  *    may be used to endorse or promote products derived from this software
  68  *    without specific prior written permission.
  69  *
  70  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  71  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  72  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  73  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  74  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  75  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  76  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  77  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  78  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  79  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  80  * SUCH DAMAGE.
  81  */
  82
  83 /*
  84  * RFC1827/2406 Encapsulated Security Payload.
  85  */
  86
  87 struct newesp {
  88         uint32_t        esp_spi;        /* ESP */
  89         uint32_t        esp_seq;        /* Sequence number */
  90         /*variable size*/               /* (IV and) Payload data */
  91         /*variable size*/               /* padding */
  92         /*8bit*/                        /* pad size */
  93         /*8bit*/                        /* next header */
  94         /*8bit*/                        /* next header */
  95         /*variable size, 32bit bound*/  /* Authentication data */
  96 };
  97
  98 #ifdef HAVE_LIBCRYPTO
  99 union inaddr_u {
 100         struct in_addr in4;
 101 #ifdef INET6
 102         struct in6_addr in6;
 103 #endif
 104 };
 105 struct sa_list {
 106         struct sa_list  *next;
 107         u_int           daddr_version;
 108         union inaddr_u  daddr;
 109         uint32_t        spi;          /* if == 0, then IKEv2 */
 110         int             initiator;
 111         u_char          spii[8];      /* for IKEv2 */
 112         u_char          spir[8];
 113         const EVP_CIPHER *evp;
 114         int             ivlen;
 115         int             authlen;
 116         u_char          authsecret[256];
 117         int             authsecret_len;
 118         u_char          secret[256];  /* is that big enough for all secrets? */
 119         int             secretlen;
 120 };
 121
 122 /*
 123  * this will adjust ndo_packetp and ndo_snapend to new buffer!
 124  */
 125 USES_APPLE_DEPRECATED_API
 126 int esp_print_decrypt_buffer_by_ikev2(netdissect_options *ndo,
 127                                       int initiator,
 128                                       u_char spii[8], u_char spir[8],
 129                                       u_char *buf, u_char *end)
 130 {
 131         struct sa_list *sa;
 132         u_char *iv;
 133         int len;
 134         EVP_CIPHER_CTX ctx;
 135
 136         /* initiator arg is any non-zero value */
 137         if(initiator) initiator=1;
 138
 139         /* see if we can find the SA, and if so, decode it */
 140         for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 141                 if (sa->spi == 0
 142                     && initiator == sa->initiator
 143                     && memcmp(spii, sa->spii, 8) == 0
 144                     && memcmp(spir, sa->spir, 8) == 0)
 145                         break;
 146         }
 147
 148         if(sa == NULL) return 0;
 149         if(sa->evp == NULL) return 0;
 150
 151         /*
 152          * remove authenticator, and see if we still have something to
 153          * work with
 154          */
 155         end = end - sa->authlen;
 156         iv  = buf;
 157         buf = buf + sa->ivlen;
 158         len = end-buf;
 159
 160         if(end <= buf) return 0;
 161
 162         memset(&ctx, 0, sizeof(ctx));
 163         if (EVP_CipherInit(&ctx, sa->evp, sa->secret, NULL, 0) < 0)
 164                 (*ndo->ndo_warning)(ndo, "espkey init failed");
 165         EVP_CipherInit(&ctx, NULL, NULL, iv, 0);
 166         EVP_Cipher(&ctx, buf, buf, len);
 167         EVP_CIPHER_CTX_cleanup(&ctx);
 168
 169         ndo->ndo_packetp = buf;
 170         ndo->ndo_snapend = end;
 171
 172         return 1;
 173
 174 }
 175 USES_APPLE_RST
 176
 177 static void esp_print_addsa(netdissect_options *ndo,
 178                             struct sa_list *sa, int sa_def)
 179 {
 180         /* copy the "sa" */
 181
 182         struct sa_list *nsa;
 183
 184         nsa = (struct sa_list *)malloc(sizeof(struct sa_list));
 185         if (nsa == NULL)
 186                 (*ndo->ndo_error)(ndo, "ran out of memory to allocate sa structure");
 187
 188         *nsa = *sa;
 189
 190         if (sa_def)
 191                 ndo->ndo_sa_default = nsa;
 192
 193         nsa->next = ndo->ndo_sa_list_head;
 194         ndo->ndo_sa_list_head = nsa;
 195 }
 196
 197
 198 static u_int hexdigit(netdissect_options *ndo, char hex)
 199 {
 200         if (hex >= '0' && hex <= '9')
 201                 return (hex - '0');
 202         else if (hex >= 'A' && hex <= 'F')
 203                 return (hex - 'A' + 10);
 204         else if (hex >= 'a' && hex <= 'f')
 205                 return (hex - 'a' + 10);
 206         else {
 207                 (*ndo->ndo_error)(ndo, "invalid hex digit %c in espsecret\n", hex);
 208                 return 0;
 209         }
 210 }
 211
 212 static u_int hex2byte(netdissect_options *ndo, char *hexstring)
 213 {
 214         u_int byte;
 215
 216         byte = (hexdigit(ndo, hexstring[0]) << 4) + hexdigit(ndo, hexstring[1]);
 217         return byte;
 218 }
 219
 220 /*
 221  * returns size of binary, 0 on failure.
 222  */
 223 static
 224 int espprint_decode_hex(netdissect_options *ndo,
 225                         u_char *binbuf, unsigned int binbuf_len,
 226                         char *hex)
 227 {
 228         unsigned int len;
 229         int i;
 230
 231         len = strlen(hex) / 2;
 232
 233         if (len > binbuf_len) {
 234                 (*ndo->ndo_warning)(ndo, "secret is too big: %d\n", len);
 235                 return 0;
 236         }
 237
 238         i = 0;
 239         while (hex[0] != '\0' && hex[1]!='\0') {
 240                 binbuf[i] = hex2byte(ndo, hex);
 241                 hex += 2;
 242                 i++;
 243         }
 244
 245         return i;
 246 }
 247
 248 /*
 249  * decode the form:    SPINUM@IP <tab> ALGONAME:0xsecret
 250  */
 251
 252 USES_APPLE_DEPRECATED_API
 253 static int
 254 espprint_decode_encalgo(netdissect_options *ndo,
 255                         char *decode, struct sa_list *sa)
 256 {
 257         size_t i;
 258         const EVP_CIPHER *evp;
 259         int authlen = 0;
 260         char *colon, *p;
 261
 262         colon = strchr(decode, ':');
 263         if (colon == NULL) {
 264                 (*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
 265                 return 0;
 266         }
 267         *colon = '\0';
 268
 269         if (strlen(decode) > strlen("-hmac96") &&
 270             !strcmp(decode + strlen(decode) - strlen("-hmac96"),
 271                     "-hmac96")) {
 272                 p = strstr(decode, "-hmac96");
 273                 *p = '\0';
 274                 authlen = 12;
 275         }
 276         if (strlen(decode) > strlen("-cbc") &&
 277             !strcmp(decode + strlen(decode) - strlen("-cbc"), "-cbc")) {
 278                 p = strstr(decode, "-cbc");
 279                 *p = '\0';
 280         }
 281         evp = EVP_get_cipherbyname(decode);
 282
 283         if (!evp) {
 284                 (*ndo->ndo_warning)(ndo, "failed to find cipher algo %s\n", decode);
 285                 sa->evp = NULL;
 286                 sa->authlen = 0;
 287                 sa->ivlen = 0;
 288                 return 0;
 289         }
 290
 291         sa->evp = evp;
 292         sa->authlen = authlen;
 293         sa->ivlen = EVP_CIPHER_iv_length(evp);
 294
 295         colon++;
 296         if (colon[0] == '0' && colon[1] == 'x') {
 297                 /* decode some hex! */
 298
 299                 colon += 2;
 300                 sa->secretlen = espprint_decode_hex(ndo, sa->secret, sizeof(sa->secret), colon);
 301                 if(sa->secretlen == 0) return 0;
 302         } else {
 303                 i = strlen(colon);
 304
 305                 if (i < sizeof(sa->secret)) {
 306                         memcpy(sa->secret, colon, i);
 307                         sa->secretlen = i;
 308                 } else {
 309                         memcpy(sa->secret, colon, sizeof(sa->secret));
 310                         sa->secretlen = sizeof(sa->secret);
 311                 }
 312         }
 313
 314         return 1;
 315 }
 316 USES_APPLE_RST
 317
 318 /*
 319  * for the moment, ignore the auth algorith, just hard code the authenticator
 320  * length. Need to research how openssl looks up HMAC stuff.
 321  */
 322 static int
 323 espprint_decode_authalgo(netdissect_options *ndo,
 324                          char *decode, struct sa_list *sa)
 325 {
 326         char *colon;
 327
 328         colon = strchr(decode, ':');
 329         if (colon == NULL) {
 330                 (*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
 331                 return 0;
 332         }
 333         *colon = '\0';
 334
 335         if(strcasecmp(colon,"sha1") == 0 ||
 336            strcasecmp(colon,"md5") == 0) {
 337                 sa->authlen = 12;
 338         }
 339         return 1;
 340 }
 341
 342 static void esp_print_decode_ikeline(netdissect_options *ndo, char *line,
 343                                      const char *file, int lineno)
 344 {
 345         /* it's an IKEv2 secret, store it instead */
 346         struct sa_list sa1;
 347
 348         char *init;
 349         char *icookie, *rcookie;
 350         int   ilen, rlen;
 351         char *authkey;
 352         char *enckey;
 353
 354         init = strsep(&line, " \t");
 355         icookie = strsep(&line, " \t");
 356         rcookie = strsep(&line, " \t");
 357         authkey = strsep(&line, " \t");
 358         enckey  = strsep(&line, " \t");
 359
 360         /* if any fields are missing */
 361         if(!init || !icookie || !rcookie || !authkey || !enckey) {
 362                 (*ndo->ndo_warning)(ndo, "print_esp: failed to find all fields for ikev2 at %s:%u",
 363                                     file, lineno);
 364
 365                 return;
 366         }
 367
 368         ilen = strlen(icookie);
 369         rlen = strlen(rcookie);
 370
 371         if((init[0]!='I' && init[0]!='R')
 372            || icookie[0]!='0' || icookie[1]!='x'
 373            || rcookie[0]!='0' || rcookie[1]!='x'
 374            || ilen!=18
 375            || rlen!=18) {
 376                 (*ndo->ndo_warning)(ndo, "print_esp: line %s:%u improperly formatted.",
 377                                     file, lineno);
 378
 379                 (*ndo->ndo_warning)(ndo, "init=%s icookie=%s(%u) rcookie=%s(%u)",
 380                                     init, icookie, ilen, rcookie, rlen);
 381
 382                 return;
 383         }
 384
 385         sa1.spi = 0;
 386         sa1.initiator = (init[0] == 'I');
 387         if(espprint_decode_hex(ndo, sa1.spii, sizeof(sa1.spii), icookie+2)!=8)
 388                 return;
 389
 390         if(espprint_decode_hex(ndo, sa1.spir, sizeof(sa1.spir), rcookie+2)!=8)
 391                 return;
 392
 393         if(!espprint_decode_encalgo(ndo, enckey, &sa1)) return;
 394
 395         if(!espprint_decode_authalgo(ndo, authkey, &sa1)) return;
 396
 397         esp_print_addsa(ndo, &sa1, FALSE);
 398 }
 399
 400 /*
 401  *
 402  * special form: file /name
 403  * causes us to go read from this file instead.
 404  *
 405  */
 406 static void esp_print_decode_onesecret(netdissect_options *ndo, char *line,
 407                                        const char *file, int lineno)
 408 {
 409         struct sa_list sa1;
 410         int sa_def;
 411
 412         char *spikey;
 413         char *decode;
 414
 415         spikey = strsep(&line, " \t");
 416         sa_def = 0;
 417         memset(&sa1, 0, sizeof(struct sa_list));
 418
 419         /* if there is only one token, then it is an algo:key token */
 420         if (line == NULL) {
 421                 decode = spikey;
 422                 spikey = NULL;
 423                 /* sa1.daddr.version = 0; */
 424                 /* memset(&sa1.daddr, 0, sizeof(sa1.daddr)); */
 425                 /* sa1.spi = 0; */
 426                 sa_def    = 1;
 427         } else
 428                 decode = line;
 429
 430         if (spikey && strcasecmp(spikey, "file") == 0) {
 431                 /* open file and read it */
 432                 FILE *secretfile;
 433                 char  fileline[1024];
 434                 int   lineno=0;
 435                 char  *nl;
 436                 char *filename = line;
 437
 438                 secretfile = fopen(filename, FOPEN_READ_TXT);
 439                 if (secretfile == NULL) {
 440                         perror(filename);
 441                         exit(3);
 442                 }
 443
 444                 while (fgets(fileline, sizeof(fileline)-1, secretfile) != NULL) {
 445                         lineno++;
 446                         /* remove newline from the line */
 447                         nl = strchr(fileline, '\n');
 448                         if (nl)
 449                                 *nl = '\0';
 450                         if (fileline[0] == '#') continue;
 451                         if (fileline[0] == '\0') continue;
 452
 453                         esp_print_decode_onesecret(ndo, fileline, filename, lineno);
 454                 }
 455                 fclose(secretfile);
 456
 457                 return;
 458         }
 459
 460         if (spikey && strcasecmp(spikey, "ikev2") == 0) {
 461                 esp_print_decode_ikeline(ndo, line, file, lineno);
 462                 return;
 463         }
 464
 465         if (spikey) {
 466
 467                 char *spistr, *foo;
 468                 uint32_t spino;
 469
 470                 spistr = strsep(&spikey, "@");
 471
 472                 spino = strtoul(spistr, &foo, 0);
 473                 if (spistr == foo || !spikey) {
 474                         (*ndo->ndo_warning)(ndo, "print_esp: failed to decode spi# %s\n", foo);
 475                         return;
 476                 }
 477
 478                 sa1.spi = spino;
 479
 480 #ifdef INET6
 481                 if (inet_pton(AF_INET6, spikey, &sa1.daddr.in6) == 1) {
 482                         sa1.daddr_version = 6;
 483                 } else
 484 #endif
 485                         if (inet_pton(AF_INET, spikey, &sa1.daddr.in4) == 1) {
 486                                 sa1.daddr_version = 4;
 487                         } else {
 488                                 (*ndo->ndo_warning)(ndo, "print_esp: can not decode IP# %s\n", spikey);
 489                                 return;
 490                         }
 491         }
 492
 493         if (decode) {
 494                 /* skip any blank spaces */
 495                 while (isspace((unsigned char)*decode))
 496                         decode++;
 497
 498                 if(!espprint_decode_encalgo(ndo, decode, &sa1)) {
 499                         return;
 500                 }
 501         }
 502
 503         esp_print_addsa(ndo, &sa1, sa_def);
 504 }
 505
 506 USES_APPLE_DEPRECATED_API
 507 static void esp_init(netdissect_options *ndo _U_)
 508 {
 509
 510         OpenSSL_add_all_algorithms();
 511         EVP_add_cipher_alias(SN_des_ede3_cbc, "3des");
 512 }
 513 USES_APPLE_RST
 514
 515 void esp_print_decodesecret(netdissect_options *ndo)
 516 {
 517         char *line;
 518         char *p;
 519         static int initialized = 0;
 520
 521         if (!initialized) {
 522                 esp_init(ndo);
 523                 initialized = 1;
 524         }
 525
 526         p = ndo->ndo_espsecret;
 527
 528         while (p && p[0] != '\0') {
 529                 /* pick out the first line or first thing until a comma */
 530                 if ((line = strsep(&p, "\n,")) == NULL) {
 531                         line = p;
 532                         p = NULL;
 533                 }
 534
 535                 esp_print_decode_onesecret(ndo, line, "cmdline", 0);
 536         }
 537
 538         ndo->ndo_espsecret = NULL;
 539 }
 540
 541 #endif
 542
 543 #ifdef HAVE_LIBCRYPTO
 544 USES_APPLE_DEPRECATED_API
 545 #endif
 546 int
 547 esp_print(netdissect_options *ndo,
 548           const u_char *bp, const int length, const u_char *bp2
 549 #ifndef HAVE_LIBCRYPTO
 550         _U_
 551 #endif
 552         ,
 553         int *nhdr
 554 #ifndef HAVE_LIBCRYPTO
 555         _U_
 556 #endif
 557         ,
 558         int *padlen
 559 #ifndef HAVE_LIBCRYPTO
 560         _U_
 561 #endif
 562         )
 563 {
 564         register const struct newesp *esp;
 565         register const u_char *ep;
 566 #ifdef HAVE_LIBCRYPTO
 567         struct ip *ip;
 568         struct sa_list *sa = NULL;
 569 #ifdef INET6
 570         struct ip6_hdr *ip6 = NULL;
 571 #endif
 572         int advance;
 573         int len;
 574         u_char *secret;
 575         int ivlen = 0;
 576         u_char *ivoff;
 577         u_char *p;
 578         EVP_CIPHER_CTX ctx;
 579 #endif
 580
 581         esp = (struct newesp *)bp;
 582
 583 #ifdef HAVE_LIBCRYPTO
 584         secret = NULL;
 585         advance = 0;
 586 #endif
 587
 588 #if 0
 589         /* keep secret out of a register */
 590         p = (u_char *)&secret;
 591 #endif
 592
 593         /* 'ep' points to the end of available data. */
 594         ep = ndo->ndo_snapend;
 595
 596         if ((u_char *)(esp + 1) >= ep) {
 597                 ND_PRINT((ndo, "[|ESP]"));
 598                 goto fail;
 599         }
 600         ND_PRINT((ndo, "ESP(spi=0x%08x", EXTRACT_32BITS(&esp->esp_spi)));
 601         ND_PRINT((ndo, ",seq=0x%x)", EXTRACT_32BITS(&esp->esp_seq)));
 602         ND_PRINT((ndo, ", length %u", length));
 603
 604 #ifndef HAVE_LIBCRYPTO
 605         goto fail;
 606 #else
 607         /* initiailize SAs */
 608         if (ndo->ndo_sa_list_head == NULL) {
 609                 if (!ndo->ndo_espsecret)
 610                         goto fail;
 611
 612                 esp_print_decodesecret(ndo);
 613         }
 614
 615         if (ndo->ndo_sa_list_head == NULL)
 616                 goto fail;
 617
 618         ip = (struct ip *)bp2;
 619         switch (IP_V(ip)) {
 620 #ifdef INET6
 621         case 6:
 622                 ip6 = (struct ip6_hdr *)bp2;
 623                 /* we do not attempt to decrypt jumbograms */
 624                 if (!EXTRACT_16BITS(&ip6->ip6_plen))
 625                         goto fail;
 626                 /* if we can't get nexthdr, we do not need to decrypt it */
 627                 len = sizeof(struct ip6_hdr) + EXTRACT_16BITS(&ip6->ip6_plen);
 628
 629                 /* see if we can find the SA, and if so, decode it */
 630                 for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 631                         if (sa->spi == EXTRACT_32BITS(&esp->esp_spi) &&
 632                             sa->daddr_version == 6 &&
 633                             UNALIGNED_MEMCMP(&sa->daddr.in6, &ip6->ip6_dst,
 634                                    sizeof(struct in6_addr)) == 0) {
 635                                 break;
 636                         }
 637                 }
 638                 break;
 639 #endif /*INET6*/
 640         case 4:
 641                 /* nexthdr & padding are in the last fragment */
 642                 if (EXTRACT_16BITS(&ip->ip_off) & IP_MF)
 643                         goto fail;
 644                 len = EXTRACT_16BITS(&ip->ip_len);
 645
 646                 /* see if we can find the SA, and if so, decode it */
 647                 for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 648                         if (sa->spi == EXTRACT_32BITS(&esp->esp_spi) &&
 649                             sa->daddr_version == 4 &&
 650                             UNALIGNED_MEMCMP(&sa->daddr.in4, &ip->ip_dst,
 651                                    sizeof(struct in_addr)) == 0) {
 652                                 break;
 653                         }
 654                 }
 655                 break;
 656         default:
 657                 goto fail;
 658         }
 659
 660         /* if we didn't find the specific one, then look for
 661          * an unspecified one.
 662          */
 663         if (sa == NULL)
 664                 sa = ndo->ndo_sa_default;
 665
 666         /* if not found fail */
 667         if (sa == NULL)
 668                 goto fail;
 669
 670         /* if we can't get nexthdr, we do not need to decrypt it */
 671         if (ep - bp2 < len)
 672                 goto fail;
 673         if (ep - bp2 > len) {
 674                 /* FCS included at end of frame (NetBSD 1.6 or later) */
 675                 ep = bp2 + len;
 676         }
 677
 678         ivoff = (u_char *)(esp + 1) + 0;
 679         ivlen = sa->ivlen;
 680         secret = sa->secret;
 681         ep = ep - sa->authlen;
 682
 683         if (sa->evp) {
 684                 memset(&ctx, 0, sizeof(ctx));
 685                 if (EVP_CipherInit(&ctx, sa->evp, secret, NULL, 0) < 0)
 686                         (*ndo->ndo_warning)(ndo, "espkey init failed");
 687
 688                 p = ivoff;
 689                 EVP_CipherInit(&ctx, NULL, NULL, p, 0);
 690                 EVP_Cipher(&ctx, p + ivlen, p + ivlen, ep - (p + ivlen));
 691                 EVP_CIPHER_CTX_cleanup(&ctx);
 692                 advance = ivoff - (u_char *)esp + ivlen;
 693         } else
 694                 advance = sizeof(struct newesp);
 695
 696         /* sanity check for pad length */
 697         if (ep - bp < *(ep - 2))
 698                 goto fail;
 699
 700         if (padlen)
 701                 *padlen = *(ep - 2) + 2;
 702
 703         if (nhdr)
 704                 *nhdr = *(ep - 1);
 705
 706         ND_PRINT((ndo, ": "));
 707         return advance;
 708 #endif
 709
 710 fail:
 711         return -1;
 712 }
 713 #ifdef HAVE_LIBCRYPTO
 714 USES_APPLE_RST
 715 #endif
 716
 717 /*
 718  * Local Variables:
 719  * c-style: whitesmith
 720  * c-basic-offset: 8
 721  * End:
 722  */