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 #ifdef HAVE_CONFIG_H
  25 #include "config.h"
  26 #endif
  27
  28 #include <netdissect-stdinc.h>
  29
  30 #include <string.h>
  31 #include <stdlib.h>
  32
  33 /* Any code in this file that depends on HAVE_LIBCRYPTO depends on
  34  * HAVE_OPENSSL_EVP_H too. Undefining the former when the latter isn't defined
  35  * is the simplest way of handling the dependency.
  36  */
  37 #ifdef HAVE_LIBCRYPTO
  38 #ifdef HAVE_OPENSSL_EVP_H
  39 #include <openssl/evp.h>
  40 #else
  41 #undef HAVE_LIBCRYPTO
  42 #endif
  43 #endif
  44
  45 #include "netdissect.h"
  46 #include "strtoaddr.h"
  47 #include "extract.h"
  48
  49 #include "ascii_strcasecmp.h"
  50
  51 #include "ip.h"
  52 #include "ip6.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         struct in6_addr in6;
 102 };
 103 struct sa_list {
 104         struct sa_list  *next;
 105         u_int           daddr_version;
 106         union inaddr_u  daddr;
 107         uint32_t        spi;          /* if == 0, then IKEv2 */
 108         int             initiator;
 109         u_char          spii[8];      /* for IKEv2 */
 110         u_char          spir[8];
 111         const EVP_CIPHER *evp;
 112         int             ivlen;
 113         int             authlen;
 114         u_char          authsecret[256];
 115         int             authsecret_len;
 116         u_char          secret[256];  /* is that big enough for all secrets? */
 117         int             secretlen;
 118 };
 119
 120 /*
 121  * this will adjust ndo_packetp and ndo_snapend to new buffer!
 122  */
 123 USES_APPLE_DEPRECATED_API
 124 int esp_print_decrypt_buffer_by_ikev2(netdissect_options *ndo,
 125                                       int initiator,
 126                                       u_char spii[8], u_char spir[8],
 127                                       const u_char *buf, const u_char *end)
 128 {
 129         struct sa_list *sa;
 130         const u_char *iv;
 131         int len;
 132         EVP_CIPHER_CTX ctx;
 133
 134         /* initiator arg is any non-zero value */
 135         if(initiator) initiator=1;
 136
 137         /* see if we can find the SA, and if so, decode it */
 138         for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 139                 if (sa->spi == 0
 140                     && initiator == sa->initiator
 141                     && memcmp(spii, sa->spii, 8) == 0
 142                     && memcmp(spir, sa->spir, 8) == 0)
 143                         break;
 144         }
 145
 146         if(sa == NULL) return 0;
 147         if(sa->evp == NULL) return 0;
 148
 149         /*
 150          * remove authenticator, and see if we still have something to
 151          * work with
 152          */
 153         end = end - sa->authlen;
 154         iv  = buf;
 155         buf = buf + sa->ivlen;
 156         len = end-buf;
 157
 158         if(end <= buf) return 0;
 159
 160         memset(&ctx, 0, sizeof(ctx));
 161         if (EVP_CipherInit(&ctx, sa->evp, sa->secret, NULL, 0) < 0)
 162                 (*ndo->ndo_warning)(ndo, "espkey init failed");
 163         EVP_CipherInit(&ctx, NULL, NULL, iv, 0);
 164         EVP_Cipher(&ctx, buf, buf, len);
 165         EVP_CIPHER_CTX_cleanup(&ctx);
 166
 167         ndo->ndo_packetp = buf;
 168         ndo->ndo_snapend = end;
 169
 170         return 1;
 171
 172 }
 173 USES_APPLE_RST
 174
 175 static void esp_print_addsa(netdissect_options *ndo,
 176                             struct sa_list *sa, int sa_def)
 177 {
 178         /* copy the "sa" */
 179
 180         struct sa_list *nsa;
 181
 182         nsa = (struct sa_list *)malloc(sizeof(struct sa_list));
 183         if (nsa == NULL)
 184                 (*ndo->ndo_error)(ndo, "ran out of memory to allocate sa structure");
 185
 186         *nsa = *sa;
 187
 188         if (sa_def)
 189                 ndo->ndo_sa_default = nsa;
 190
 191         nsa->next = ndo->ndo_sa_list_head;
 192         ndo->ndo_sa_list_head = nsa;
 193 }
 194
 195
 196 static u_int hexdigit(netdissect_options *ndo, char hex)
 197 {
 198         if (hex >= '0' && hex <= '9')
 199                 return (hex - '0');
 200         else if (hex >= 'A' && hex <= 'F')
 201                 return (hex - 'A' + 10);
 202         else if (hex >= 'a' && hex <= 'f')
 203                 return (hex - 'a' + 10);
 204         else {
 205                 (*ndo->ndo_error)(ndo, "invalid hex digit %c in espsecret\n", hex);
 206                 return 0;
 207         }
 208 }
 209
 210 static u_int hex2byte(netdissect_options *ndo, char *hexstring)
 211 {
 212         u_int byte;
 213
 214         byte = (hexdigit(ndo, hexstring[0]) << 4) + hexdigit(ndo, hexstring[1]);
 215         return byte;
 216 }
 217
 218 /*
 219  * returns size of binary, 0 on failure.
 220  */
 221 static
 222 int espprint_decode_hex(netdissect_options *ndo,
 223                         u_char *binbuf, unsigned int binbuf_len,
 224                         char *hex)
 225 {
 226         unsigned int len;
 227         int i;
 228
 229         len = strlen(hex) / 2;
 230
 231         if (len > binbuf_len) {
 232                 (*ndo->ndo_warning)(ndo, "secret is too big: %d\n", len);
 233                 return 0;
 234         }
 235
 236         i = 0;
 237         while (hex[0] != '\0' && hex[1]!='\0') {
 238                 binbuf[i] = hex2byte(ndo, hex);
 239                 hex += 2;
 240                 i++;
 241         }
 242
 243         return i;
 244 }
 245
 246 /*
 247  * decode the form:    SPINUM@IP <tab> ALGONAME:0xsecret
 248  */
 249
 250 USES_APPLE_DEPRECATED_API
 251 static int
 252 espprint_decode_encalgo(netdissect_options *ndo,
 253                         char *decode, struct sa_list *sa)
 254 {
 255         size_t i;
 256         const EVP_CIPHER *evp;
 257         int authlen = 0;
 258         char *colon, *p;
 259
 260         colon = strchr(decode, ':');
 261         if (colon == NULL) {
 262                 (*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
 263                 return 0;
 264         }
 265         *colon = '\0';
 266
 267         if (strlen(decode) > strlen("-hmac96") &&
 268             !strcmp(decode + strlen(decode) - strlen("-hmac96"),
 269                     "-hmac96")) {
 270                 p = strstr(decode, "-hmac96");
 271                 *p = '\0';
 272                 authlen = 12;
 273         }
 274         if (strlen(decode) > strlen("-cbc") &&
 275             !strcmp(decode + strlen(decode) - strlen("-cbc"), "-cbc")) {
 276                 p = strstr(decode, "-cbc");
 277                 *p = '\0';
 278         }
 279         evp = EVP_get_cipherbyname(decode);
 280
 281         if (!evp) {
 282                 (*ndo->ndo_warning)(ndo, "failed to find cipher algo %s\n", decode);
 283                 sa->evp = NULL;
 284                 sa->authlen = 0;
 285                 sa->ivlen = 0;
 286                 return 0;
 287         }
 288
 289         sa->evp = evp;
 290         sa->authlen = authlen;
 291         sa->ivlen = EVP_CIPHER_iv_length(evp);
 292
 293         colon++;
 294         if (colon[0] == '0' && colon[1] == 'x') {
 295                 /* decode some hex! */
 296
 297                 colon += 2;
 298                 sa->secretlen = espprint_decode_hex(ndo, sa->secret, sizeof(sa->secret), colon);
 299                 if(sa->secretlen == 0) return 0;
 300         } else {
 301                 i = strlen(colon);
 302
 303                 if (i < sizeof(sa->secret)) {
 304                         memcpy(sa->secret, colon, i);
 305                         sa->secretlen = i;
 306                 } else {
 307                         memcpy(sa->secret, colon, sizeof(sa->secret));
 308                         sa->secretlen = sizeof(sa->secret);
 309                 }
 310         }
 311
 312         return 1;
 313 }
 314 USES_APPLE_RST
 315
 316 /*
 317  * for the moment, ignore the auth algorith, just hard code the authenticator
 318  * length. Need to research how openssl looks up HMAC stuff.
 319  */
 320 static int
 321 espprint_decode_authalgo(netdissect_options *ndo,
 322                          char *decode, struct sa_list *sa)
 323 {
 324         char *colon;
 325
 326         colon = strchr(decode, ':');
 327         if (colon == NULL) {
 328                 (*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
 329                 return 0;
 330         }
 331         *colon = '\0';
 332
 333         if(ascii_strcasecmp(colon,"sha1") == 0 ||
 334            ascii_strcasecmp(colon,"md5") == 0) {
 335                 sa->authlen = 12;
 336         }
 337         return 1;
 338 }
 339
 340 static void esp_print_decode_ikeline(netdissect_options *ndo, char *line,
 341                                      const char *file, int lineno)
 342 {
 343         /* it's an IKEv2 secret, store it instead */
 344         struct sa_list sa1;
 345
 346         char *init;
 347         char *icookie, *rcookie;
 348         int   ilen, rlen;
 349         char *authkey;
 350         char *enckey;
 351
 352         init = strsep(&line, " \t");
 353         icookie = strsep(&line, " \t");
 354         rcookie = strsep(&line, " \t");
 355         authkey = strsep(&line, " \t");
 356         enckey  = strsep(&line, " \t");
 357
 358         /* if any fields are missing */
 359         if(!init || !icookie || !rcookie || !authkey || !enckey) {
 360                 (*ndo->ndo_warning)(ndo, "print_esp: failed to find all fields for ikev2 at %s:%u",
 361                                     file, lineno);
 362
 363                 return;
 364         }
 365
 366         ilen = strlen(icookie);
 367         rlen = strlen(rcookie);
 368
 369         if((init[0]!='I' && init[0]!='R')
 370            || icookie[0]!='0' || icookie[1]!='x'
 371            || rcookie[0]!='0' || rcookie[1]!='x'
 372            || ilen!=18
 373            || rlen!=18) {
 374                 (*ndo->ndo_warning)(ndo, "print_esp: line %s:%u improperly formatted.",
 375                                     file, lineno);
 376
 377                 (*ndo->ndo_warning)(ndo, "init=%s icookie=%s(%u) rcookie=%s(%u)",
 378                                     init, icookie, ilen, rcookie, rlen);
 379
 380                 return;
 381         }
 382
 383         sa1.spi = 0;
 384         sa1.initiator = (init[0] == 'I');
 385         if(espprint_decode_hex(ndo, sa1.spii, sizeof(sa1.spii), icookie+2)!=8)
 386                 return;
 387
 388         if(espprint_decode_hex(ndo, sa1.spir, sizeof(sa1.spir), rcookie+2)!=8)
 389                 return;
 390
 391         if(!espprint_decode_encalgo(ndo, enckey, &sa1)) return;
 392
 393         if(!espprint_decode_authalgo(ndo, authkey, &sa1)) return;
 394
 395         esp_print_addsa(ndo, &sa1, FALSE);
 396 }
 397
 398 /*
 399  *
 400  * special form: file /name
 401  * causes us to go read from this file instead.
 402  *
 403  */
 404 static void esp_print_decode_onesecret(netdissect_options *ndo, char *line,
 405                                        const char *file, int lineno)
 406 {
 407         struct sa_list sa1;
 408         int sa_def;
 409
 410         char *spikey;
 411         char *decode;
 412
 413         spikey = strsep(&line, " \t");
 414         sa_def = 0;
 415         memset(&sa1, 0, sizeof(struct sa_list));
 416
 417         /* if there is only one token, then it is an algo:key token */
 418         if (line == NULL) {
 419                 decode = spikey;
 420                 spikey = NULL;
 421                 /* sa1.daddr.version = 0; */
 422                 /* memset(&sa1.daddr, 0, sizeof(sa1.daddr)); */
 423                 /* sa1.spi = 0; */
 424                 sa_def    = 1;
 425         } else
 426                 decode = line;
 427
 428         if (spikey && ascii_strcasecmp(spikey, "file") == 0) {
 429                 /* open file and read it */
 430                 FILE *secretfile;
 431                 char  fileline[1024];
 432                 int   subfile_lineno=0;
 433                 char  *nl;
 434                 char *filename = line;
 435
 436                 secretfile = fopen(filename, FOPEN_READ_TXT);
 437                 if (secretfile == NULL) {
 438                         perror(filename);
 439                         exit(3);
 440                 }
 441
 442                 while (fgets(fileline, sizeof(fileline)-1, secretfile) != NULL) {
 443                         subfile_lineno++;
 444                         /* remove newline from the line */
 445                         nl = strchr(fileline, '\n');
 446                         if (nl)
 447                                 *nl = '\0';
 448                         if (fileline[0] == '#') continue;
 449                         if (fileline[0] == '\0') continue;
 450
 451                         esp_print_decode_onesecret(ndo, fileline, filename, subfile_lineno);
 452                 }
 453                 fclose(secretfile);
 454
 455                 return;
 456         }
 457
 458         if (spikey && ascii_strcasecmp(spikey, "ikev2") == 0) {
 459                 esp_print_decode_ikeline(ndo, line, file, lineno);
 460                 return;
 461         }
 462
 463         if (spikey) {
 464
 465                 char *spistr, *foo;
 466                 uint32_t spino;
 467
 468                 spistr = strsep(&spikey, "@");
 469
 470                 spino = strtoul(spistr, &foo, 0);
 471                 if (spistr == foo || !spikey) {
 472                         (*ndo->ndo_warning)(ndo, "print_esp: failed to decode spi# %s\n", foo);
 473                         return;
 474                 }
 475
 476                 sa1.spi = spino;
 477
 478                 if (strtoaddr6(spikey, &sa1.daddr.in6) == 1) {
 479                         sa1.daddr_version = 6;
 480                 } else if (strtoaddr(spikey, &sa1.daddr.in4) == 1) {
 481                         sa1.daddr_version = 4;
 482                 } else {
 483                         (*ndo->ndo_warning)(ndo, "print_esp: can not decode IP# %s\n", spikey);
 484                         return;
 485                 }
 486         }
 487
 488         if (decode) {
 489                 /* skip any blank spaces */
 490                 while (isspace((unsigned char)*decode))
 491                         decode++;
 492
 493                 if(!espprint_decode_encalgo(ndo, decode, &sa1)) {
 494                         return;
 495                 }
 496         }
 497
 498         esp_print_addsa(ndo, &sa1, sa_def);
 499 }
 500
 501 USES_APPLE_DEPRECATED_API
 502 static void esp_init(netdissect_options *ndo _U_)
 503 {
 504
 505         OpenSSL_add_all_algorithms();
 506         EVP_add_cipher_alias(SN_des_ede3_cbc, "3des");
 507 }
 508 USES_APPLE_RST
 509
 510 void esp_print_decodesecret(netdissect_options *ndo)
 511 {
 512         char *line;
 513         char *p;
 514         static int initialized = 0;
 515
 516         if (!initialized) {
 517                 esp_init(ndo);
 518                 initialized = 1;
 519         }
 520
 521         p = ndo->ndo_espsecret;
 522
 523         while (p && p[0] != '\0') {
 524                 /* pick out the first line or first thing until a comma */
 525                 if ((line = strsep(&p, "\n,")) == NULL) {
 526                         line = p;
 527                         p = NULL;
 528                 }
 529
 530                 esp_print_decode_onesecret(ndo, line, "cmdline", 0);
 531         }
 532
 533         ndo->ndo_espsecret = NULL;
 534 }
 535
 536 #endif
 537
 538 #ifdef HAVE_LIBCRYPTO
 539 USES_APPLE_DEPRECATED_API
 540 #endif
 541 int
 542 esp_print(netdissect_options *ndo,
 543           const u_char *bp, const int length, const u_char *bp2
 544 #ifndef HAVE_LIBCRYPTO
 545         _U_
 546 #endif
 547         ,
 548         int *nhdr
 549 #ifndef HAVE_LIBCRYPTO
 550         _U_
 551 #endif
 552         ,
 553         int *padlen
 554 #ifndef HAVE_LIBCRYPTO
 555         _U_
 556 #endif
 557         )
 558 {
 559         register const struct newesp *esp;
 560         register const u_char *ep;
 561 #ifdef HAVE_LIBCRYPTO
 562         const struct ip *ip;
 563         struct sa_list *sa = NULL;
 564         const struct ip6_hdr *ip6 = NULL;
 565         int advance;
 566         int len;
 567         u_char *secret;
 568         int ivlen = 0;
 569         const u_char *ivoff;
 570         const u_char *p;
 571         EVP_CIPHER_CTX ctx;
 572 #endif
 573
 574         esp = (const struct newesp *)bp;
 575
 576 #ifdef HAVE_LIBCRYPTO
 577         secret = NULL;
 578         advance = 0;
 579 #endif
 580
 581 #if 0
 582         /* keep secret out of a register */
 583         p = (u_char *)&secret;
 584 #endif
 585
 586         /* 'ep' points to the end of available data. */
 587         ep = ndo->ndo_snapend;
 588
 589         if ((const u_char *)(esp + 1) >= ep) {
 590                 ND_PRINT((ndo, "[|ESP]"));
 591                 goto fail;
 592         }
 593         ND_PRINT((ndo, "ESP(spi=0x%08x", EXTRACT_32BITS(&esp->esp_spi)));
 594         ND_PRINT((ndo, ",seq=0x%x)", EXTRACT_32BITS(&esp->esp_seq)));
 595         ND_PRINT((ndo, ", length %u", length));
 596
 597 #ifndef HAVE_LIBCRYPTO
 598         goto fail;
 599 #else
 600         /* initiailize SAs */
 601         if (ndo->ndo_sa_list_head == NULL) {
 602                 if (!ndo->ndo_espsecret)
 603                         goto fail;
 604
 605                 esp_print_decodesecret(ndo);
 606         }
 607
 608         if (ndo->ndo_sa_list_head == NULL)
 609                 goto fail;
 610
 611         ip = (const struct ip *)bp2;
 612         switch (IP_V(ip)) {
 613         case 6:
 614                 ip6 = (const struct ip6_hdr *)bp2;
 615                 /* we do not attempt to decrypt jumbograms */
 616                 if (!EXTRACT_16BITS(&ip6->ip6_plen))
 617                         goto fail;
 618                 /* if we can't get nexthdr, we do not need to decrypt it */
 619                 len = sizeof(struct ip6_hdr) + EXTRACT_16BITS(&ip6->ip6_plen);
 620
 621                 /* see if we can find the SA, and if so, decode it */
 622                 for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 623                         if (sa->spi == EXTRACT_32BITS(&esp->esp_spi) &&
 624                             sa->daddr_version == 6 &&
 625                             UNALIGNED_MEMCMP(&sa->daddr.in6, &ip6->ip6_dst,
 626                                    sizeof(struct in6_addr)) == 0) {
 627                                 break;
 628                         }
 629                 }
 630                 break;
 631         case 4:
 632                 /* nexthdr & padding are in the last fragment */
 633                 if (EXTRACT_16BITS(&ip->ip_off) & IP_MF)
 634                         goto fail;
 635                 len = EXTRACT_16BITS(&ip->ip_len);
 636
 637                 /* see if we can find the SA, and if so, decode it */
 638                 for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 639                         if (sa->spi == EXTRACT_32BITS(&esp->esp_spi) &&
 640                             sa->daddr_version == 4 &&
 641                             UNALIGNED_MEMCMP(&sa->daddr.in4, &ip->ip_dst,
 642                                    sizeof(struct in_addr)) == 0) {
 643                                 break;
 644                         }
 645                 }
 646                 break;
 647         default:
 648                 goto fail;
 649         }
 650
 651         /* if we didn't find the specific one, then look for
 652          * an unspecified one.
 653          */
 654         if (sa == NULL)
 655                 sa = ndo->ndo_sa_default;
 656
 657         /* if not found fail */
 658         if (sa == NULL)
 659                 goto fail;
 660
 661         /* if we can't get nexthdr, we do not need to decrypt it */
 662         if (ep - bp2 < len)
 663                 goto fail;
 664         if (ep - bp2 > len) {
 665                 /* FCS included at end of frame (NetBSD 1.6 or later) */
 666                 ep = bp2 + len;
 667         }
 668
 669         ivoff = (const u_char *)(esp + 1) + 0;
 670         ivlen = sa->ivlen;
 671         secret = sa->secret;
 672         ep = ep - sa->authlen;
 673
 674         if (sa->evp) {
 675                 memset(&ctx, 0, sizeof(ctx));
 676                 if (EVP_CipherInit(&ctx, sa->evp, secret, NULL, 0) < 0)
 677                         (*ndo->ndo_warning)(ndo, "espkey init failed");
 678
 679                 p = ivoff;
 680                 EVP_CipherInit(&ctx, NULL, NULL, p, 0);
 681                 EVP_Cipher(&ctx, p + ivlen, p + ivlen, ep - (p + ivlen));
 682                 EVP_CIPHER_CTX_cleanup(&ctx);
 683                 advance = ivoff - (const u_char *)esp + ivlen;
 684         } else
 685                 advance = sizeof(struct newesp);
 686
 687         /* sanity check for pad length */
 688         if (ep - bp < *(ep - 2))
 689                 goto fail;
 690
 691         if (padlen)
 692                 *padlen = *(ep - 2) + 2;
 693
 694         if (nhdr)
 695                 *nhdr = *(ep - 1);
 696
 697         ND_PRINT((ndo, ": "));
 698         return advance;
 699 #endif
 700
 701 fail:
 702         return -1;
 703 }
 704 #ifdef HAVE_LIBCRYPTO
 705 USES_APPLE_RST
 706 #endif
 707
 708 /*
 709  * Local Variables:
 710  * c-style: whitesmith
 711  * c-basic-offset: 8
 712  * End:
 713  */