contrib/tcpdump/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 /* \summary: IPSEC Encapsulating Security Payload (ESP) printer */
  25
  26 #ifdef HAVE_CONFIG_H
  27 #include "config.h"
  28 #endif
  29
  30 #include <netdissect-stdinc.h>
  31
  32 #include <string.h>
  33 #include <stdlib.h>
  34
  35 /* Any code in this file that depends on HAVE_LIBCRYPTO depends on
  36  * HAVE_OPENSSL_EVP_H too. Undefining the former when the latter isn't defined
  37  * is the simplest way of handling the dependency.
  38  */
  39 #ifdef HAVE_LIBCRYPTO
  40 #ifdef HAVE_OPENSSL_EVP_H
  41 #include <openssl/evp.h>
  42 #else
  43 #undef HAVE_LIBCRYPTO
  44 #endif
  45 #endif
  46
  47 #include "netdissect.h"
  48 #include "strtoaddr.h"
  49 #include "extract.h"
  50
  51 #include "ascii_strcasecmp.h"
  52
  53 #include "ip.h"
  54 #include "ip6.h"
  55
  56 /*
  57  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
  58  * All rights reserved.
  59  *
  60  * Redistribution and use in source and binary forms, with or without
  61  * modification, are permitted provided that the following conditions
  62  * are met:
  63  * 1. Redistributions of source code must retain the above copyright
  64  *    notice, this list of conditions and the following disclaimer.
  65  * 2. Redistributions in binary form must reproduce the above copyright
  66  *    notice, this list of conditions and the following disclaimer in the
  67  *    documentation and/or other materials provided with the distribution.
  68  * 3. Neither the name of the project nor the names of its contributors
  69  *    may be used to endorse or promote products derived from this software
  70  *    without specific prior written permission.
  71  *
  72  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  73  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  74  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  75  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  76  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  77  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  78  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  79  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  80  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  81  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  82  * SUCH DAMAGE.
  83  */
  84
  85 /*
  86  * RFC1827/2406 Encapsulated Security Payload.
  87  */
  88
  89 struct newesp {
  90         uint32_t        esp_spi;        /* ESP */
  91         uint32_t        esp_seq;        /* Sequence number */
  92         /*variable size*/               /* (IV and) Payload data */
  93         /*variable size*/               /* padding */
  94         /*8bit*/                        /* pad size */
  95         /*8bit*/                        /* next header */
  96         /*8bit*/                        /* next header */
  97         /*variable size, 32bit bound*/  /* Authentication data */
  98 };
  99
 100 #ifdef HAVE_LIBCRYPTO
 101 union inaddr_u {
 102         struct in_addr in4;
 103         struct in6_addr in6;
 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 #ifndef HAVE_EVP_CIPHER_CTX_NEW
 123 /*
 124  * Allocate an EVP_CIPHER_CTX.
 125  * Used if we have an older version of OpenSSL that doesn't provide
 126  * routines to allocate and free them.
 127  */
 128 static EVP_CIPHER_CTX *
 129 EVP_CIPHER_CTX_new(void)
 130 {
 131         EVP_CIPHER_CTX *ctx;
 132
 133         ctx = malloc(sizeof(*ctx));
 134         if (ctx == NULL)
 135                 return (NULL);
 136         memset(ctx, 0, sizeof(*ctx));
 137         return (ctx);
 138 }
 139
 140 static void
 141 EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx)
 142 {
 143         EVP_CIPHER_CTX_cleanup(ctx);
 144         free(ctx);
 145 }
 146 #endif
 147
 148 #ifdef HAVE_EVP_CIPHERINIT_EX
 149 /*
 150  * Initialize the cipher by calling EVP_CipherInit_ex(), because
 151  * calling EVP_CipherInit() will reset the cipher context, clearing
 152  * the cipher, so calling it twice, with the second call having a
 153  * null cipher, will clear the already-set cipher.  EVP_CipherInit_ex(),
 154  * however, won't reset the cipher context, so you can use it to specify
 155  * the IV oin a second call after a first call to EVP_CipherInit_ex()
 156  * to set the cipher and the key.
 157  *
 158  * XXX - is there some reason why we need to make two calls?
 159  */
 160 static int
 161 set_cipher_parameters(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
 162                       const unsigned char *key,
 163                       const unsigned char *iv, int enc)
 164 {
 165         return EVP_CipherInit_ex(ctx, cipher, NULL, key, iv, enc);
 166 }
 167 #else
 168 /*
 169  * Initialize the cipher by calling EVP_CipherInit(), because we don't
 170  * have EVP_CipherInit_ex(); we rely on it not trashing the context.
 171  */
 172 static int
 173 set_cipher_parameters(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
 174                       const unsigned char *key,
 175                       const unsigned char *iv, int enc)
 176 {
 177         return EVP_CipherInit(ctx, cipher, key, iv, enc);
 178 }
 179 #endif
 180
 181 /*
 182  * this will adjust ndo_packetp and ndo_snapend to new buffer!
 183  */
 184 USES_APPLE_DEPRECATED_API
 185 int esp_print_decrypt_buffer_by_ikev2(netdissect_options *ndo,
 186                                       int initiator,
 187                                       u_char spii[8], u_char spir[8],
 188                                       const u_char *buf, const u_char *end)
 189 {
 190         struct sa_list *sa;
 191         const u_char *iv;
 192         unsigned int len;
 193         EVP_CIPHER_CTX *ctx;
 194         unsigned int block_size, output_buffer_size;
 195         u_char *output_buffer;
 196
 197         /* initiator arg is any non-zero value */
 198         if(initiator) initiator=1;
 199
 200         /* see if we can find the SA, and if so, decode it */
 201         for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 202                 if (sa->spi == 0
 203                     && initiator == sa->initiator
 204                     && memcmp(spii, sa->spii, 8) == 0
 205                     && memcmp(spir, sa->spir, 8) == 0)
 206                         break;
 207         }
 208
 209         if(sa == NULL) return 0;
 210         if(sa->evp == NULL) return 0;
 211
 212         /*
 213          * remove authenticator, and see if we still have something to
 214          * work with
 215          */
 216         end = end - sa->authlen;
 217         iv  = buf;
 218         buf = buf + sa->ivlen;
 219         len = end-buf;
 220
 221         if(end <= buf) return 0;
 222
 223         ctx = EVP_CIPHER_CTX_new();
 224         if (ctx == NULL)
 225                 return 0;
 226         if (set_cipher_parameters(ctx, sa->evp, sa->secret, NULL, 0) < 0)
 227                 (*ndo->ndo_warning)(ndo, "espkey init failed");
 228         set_cipher_parameters(ctx, NULL, NULL, iv, 0);
 229         /*
 230          * Allocate a buffer for the decrypted data.
 231          * The output buffer must be separate from the input buffer, and
 232          * its size must be a multiple of the cipher block size.
 233          */
 234         block_size = (unsigned int)EVP_CIPHER_CTX_block_size(ctx);
 235         output_buffer_size = len + (block_size - len % block_size);
 236         output_buffer = (u_char *)malloc(output_buffer_size);
 237         if (output_buffer == NULL) {
 238                 (*ndo->ndo_warning)(ndo, "can't allocate memory for decryption buffer");
 239                 EVP_CIPHER_CTX_free(ctx);
 240                 return 0;
 241         }
 242         EVP_Cipher(ctx, output_buffer, buf, len);
 243         EVP_CIPHER_CTX_free(ctx);
 244
 245         /*
 246          * XXX - of course this is wrong, because buf is a const buffer,
 247          * but changing this would require a more complicated fix.
 248          */
 249         memcpy(buf, output_buffer, len);
 250         free(output_buffer);
 251
 252         ndo->ndo_packetp = buf;
 253         ndo->ndo_snapend = end;
 254
 255         return 1;
 256 }
 257 USES_APPLE_RST
 258
 259 static void esp_print_addsa(netdissect_options *ndo,
 260                             struct sa_list *sa, int sa_def)
 261 {
 262         /* copy the "sa" */
 263
 264         struct sa_list *nsa;
 265
 266         nsa = (struct sa_list *)malloc(sizeof(struct sa_list));
 267         if (nsa == NULL)
 268                 (*ndo->ndo_error)(ndo, "ran out of memory to allocate sa structure");
 269
 270         *nsa = *sa;
 271
 272         if (sa_def)
 273                 ndo->ndo_sa_default = nsa;
 274
 275         nsa->next = ndo->ndo_sa_list_head;
 276         ndo->ndo_sa_list_head = nsa;
 277 }
 278
 279
 280 static u_int hexdigit(netdissect_options *ndo, char hex)
 281 {
 282         if (hex >= '0' && hex <= '9')
 283                 return (hex - '0');
 284         else if (hex >= 'A' && hex <= 'F')
 285                 return (hex - 'A' + 10);
 286         else if (hex >= 'a' && hex <= 'f')
 287                 return (hex - 'a' + 10);
 288         else {
 289                 (*ndo->ndo_error)(ndo, "invalid hex digit %c in espsecret\n", hex);
 290                 return 0;
 291         }
 292 }
 293
 294 static u_int hex2byte(netdissect_options *ndo, char *hexstring)
 295 {
 296         u_int byte;
 297
 298         byte = (hexdigit(ndo, hexstring[0]) << 4) + hexdigit(ndo, hexstring[1]);
 299         return byte;
 300 }
 301
 302 /*
 303  * returns size of binary, 0 on failure.
 304  */
 305 static
 306 int espprint_decode_hex(netdissect_options *ndo,
 307                         u_char *binbuf, unsigned int binbuf_len,
 308                         char *hex)
 309 {
 310         unsigned int len;
 311         int i;
 312
 313         len = strlen(hex) / 2;
 314
 315         if (len > binbuf_len) {
 316                 (*ndo->ndo_warning)(ndo, "secret is too big: %d\n", len);
 317                 return 0;
 318         }
 319
 320         i = 0;
 321         while (hex[0] != '\0' && hex[1]!='\0') {
 322                 binbuf[i] = hex2byte(ndo, hex);
 323                 hex += 2;
 324                 i++;
 325         }
 326
 327         return i;
 328 }
 329
 330 /*
 331  * decode the form:    SPINUM@IP <tab> ALGONAME:0xsecret
 332  */
 333
 334 USES_APPLE_DEPRECATED_API
 335 static int
 336 espprint_decode_encalgo(netdissect_options *ndo,
 337                         char *decode, struct sa_list *sa)
 338 {
 339         size_t i;
 340         const EVP_CIPHER *evp;
 341         int authlen = 0;
 342         char *colon, *p;
 343
 344         colon = strchr(decode, ':');
 345         if (colon == NULL) {
 346                 (*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
 347                 return 0;
 348         }
 349         *colon = '\0';
 350
 351         if (strlen(decode) > strlen("-hmac96") &&
 352             !strcmp(decode + strlen(decode) - strlen("-hmac96"),
 353                     "-hmac96")) {
 354                 p = strstr(decode, "-hmac96");
 355                 *p = '\0';
 356                 authlen = 12;
 357         }
 358         if (strlen(decode) > strlen("-cbc") &&
 359             !strcmp(decode + strlen(decode) - strlen("-cbc"), "-cbc")) {
 360                 p = strstr(decode, "-cbc");
 361                 *p = '\0';
 362         }
 363         evp = EVP_get_cipherbyname(decode);
 364
 365         if (!evp) {
 366                 (*ndo->ndo_warning)(ndo, "failed to find cipher algo %s\n", decode);
 367                 sa->evp = NULL;
 368                 sa->authlen = 0;
 369                 sa->ivlen = 0;
 370                 return 0;
 371         }
 372
 373         sa->evp = evp;
 374         sa->authlen = authlen;
 375         sa->ivlen = EVP_CIPHER_iv_length(evp);
 376
 377         colon++;
 378         if (colon[0] == '0' && colon[1] == 'x') {
 379                 /* decode some hex! */
 380
 381                 colon += 2;
 382                 sa->secretlen = espprint_decode_hex(ndo, sa->secret, sizeof(sa->secret), colon);
 383                 if(sa->secretlen == 0) return 0;
 384         } else {
 385                 i = strlen(colon);
 386
 387                 if (i < sizeof(sa->secret)) {
 388                         memcpy(sa->secret, colon, i);
 389                         sa->secretlen = i;
 390                 } else {
 391                         memcpy(sa->secret, colon, sizeof(sa->secret));
 392                         sa->secretlen = sizeof(sa->secret);
 393                 }
 394         }
 395
 396         return 1;
 397 }
 398 USES_APPLE_RST
 399
 400 /*
 401  * for the moment, ignore the auth algorith, just hard code the authenticator
 402  * length. Need to research how openssl looks up HMAC stuff.
 403  */
 404 static int
 405 espprint_decode_authalgo(netdissect_options *ndo,
 406                          char *decode, struct sa_list *sa)
 407 {
 408         char *colon;
 409
 410         colon = strchr(decode, ':');
 411         if (colon == NULL) {
 412                 (*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
 413                 return 0;
 414         }
 415         *colon = '\0';
 416
 417         if(ascii_strcasecmp(colon,"sha1") == 0 ||
 418            ascii_strcasecmp(colon,"md5") == 0) {
 419                 sa->authlen = 12;
 420         }
 421         return 1;
 422 }
 423
 424 static void esp_print_decode_ikeline(netdissect_options *ndo, char *line,
 425                                      const char *file, int lineno)
 426 {
 427         /* it's an IKEv2 secret, store it instead */
 428         struct sa_list sa1;
 429
 430         char *init;
 431         char *icookie, *rcookie;
 432         int   ilen, rlen;
 433         char *authkey;
 434         char *enckey;
 435
 436         init = strsep(&line, " \t");
 437         icookie = strsep(&line, " \t");
 438         rcookie = strsep(&line, " \t");
 439         authkey = strsep(&line, " \t");
 440         enckey  = strsep(&line, " \t");
 441
 442         /* if any fields are missing */
 443         if(!init || !icookie || !rcookie || !authkey || !enckey) {
 444                 (*ndo->ndo_warning)(ndo, "print_esp: failed to find all fields for ikev2 at %s:%u",
 445                                     file, lineno);
 446
 447                 return;
 448         }
 449
 450         ilen = strlen(icookie);
 451         rlen = strlen(rcookie);
 452
 453         if((init[0]!='I' && init[0]!='R')
 454            || icookie[0]!='0' || icookie[1]!='x'
 455            || rcookie[0]!='0' || rcookie[1]!='x'
 456            || ilen!=18
 457            || rlen!=18) {
 458                 (*ndo->ndo_warning)(ndo, "print_esp: line %s:%u improperly formatted.",
 459                                     file, lineno);
 460
 461                 (*ndo->ndo_warning)(ndo, "init=%s icookie=%s(%u) rcookie=%s(%u)",
 462                                     init, icookie, ilen, rcookie, rlen);
 463
 464                 return;
 465         }
 466
 467         sa1.spi = 0;
 468         sa1.initiator = (init[0] == 'I');
 469         if(espprint_decode_hex(ndo, sa1.spii, sizeof(sa1.spii), icookie+2)!=8)
 470                 return;
 471
 472         if(espprint_decode_hex(ndo, sa1.spir, sizeof(sa1.spir), rcookie+2)!=8)
 473                 return;
 474
 475         if(!espprint_decode_encalgo(ndo, enckey, &sa1)) return;
 476
 477         if(!espprint_decode_authalgo(ndo, authkey, &sa1)) return;
 478
 479         esp_print_addsa(ndo, &sa1, FALSE);
 480 }
 481
 482 /*
 483  *
 484  * special form: file /name
 485  * causes us to go read from this file instead.
 486  *
 487  */
 488 static void esp_print_decode_onesecret(netdissect_options *ndo, char *line,
 489                                        const char *file, int lineno)
 490 {
 491         struct sa_list sa1;
 492         int sa_def;
 493
 494         char *spikey;
 495         char *decode;
 496
 497         spikey = strsep(&line, " \t");
 498         sa_def = 0;
 499         memset(&sa1, 0, sizeof(struct sa_list));
 500
 501         /* if there is only one token, then it is an algo:key token */
 502         if (line == NULL) {
 503                 decode = spikey;
 504                 spikey = NULL;
 505                 /* sa1.daddr.version = 0; */
 506                 /* memset(&sa1.daddr, 0, sizeof(sa1.daddr)); */
 507                 /* sa1.spi = 0; */
 508                 sa_def    = 1;
 509         } else
 510                 decode = line;
 511
 512         if (spikey && ascii_strcasecmp(spikey, "file") == 0) {
 513                 /* open file and read it */
 514                 FILE *secretfile;
 515                 char  fileline[1024];
 516                 int   subfile_lineno=0;
 517                 char  *nl;
 518                 char *filename = line;
 519
 520                 secretfile = fopen(filename, FOPEN_READ_TXT);
 521                 if (secretfile == NULL) {
 522                         (*ndo->ndo_error)(ndo, "print_esp: can't open %s: %s\n",
 523                             filename, strerror(errno));
 524                         return;
 525                 }
 526
 527                 while (fgets(fileline, sizeof(fileline)-1, secretfile) != NULL) {
 528                         subfile_lineno++;
 529                         /* remove newline from the line */
 530                         nl = strchr(fileline, '\n');
 531                         if (nl)
 532                                 *nl = '\0';
 533                         if (fileline[0] == '#') continue;
 534                         if (fileline[0] == '\0') continue;
 535
 536                         esp_print_decode_onesecret(ndo, fileline, filename, subfile_lineno);
 537                 }
 538                 fclose(secretfile);
 539
 540                 return;
 541         }
 542
 543         if (spikey && ascii_strcasecmp(spikey, "ikev2") == 0) {
 544                 esp_print_decode_ikeline(ndo, line, file, lineno);
 545                 return;
 546         }
 547
 548         if (spikey) {
 549
 550                 char *spistr, *foo;
 551                 uint32_t spino;
 552
 553                 spistr = strsep(&spikey, "@");
 554
 555                 spino = strtoul(spistr, &foo, 0);
 556                 if (spistr == foo || !spikey) {
 557                         (*ndo->ndo_warning)(ndo, "print_esp: failed to decode spi# %s\n", foo);
 558                         return;
 559                 }
 560
 561                 sa1.spi = spino;
 562
 563                 if (strtoaddr6(spikey, &sa1.daddr.in6) == 1) {
 564                         sa1.daddr_version = 6;
 565                 } else if (strtoaddr(spikey, &sa1.daddr.in4) == 1) {
 566                         sa1.daddr_version = 4;
 567                 } else {
 568                         (*ndo->ndo_warning)(ndo, "print_esp: can not decode IP# %s\n", spikey);
 569                         return;
 570                 }
 571         }
 572
 573         if (decode) {
 574                 /* skip any blank spaces */
 575                 while (isspace((unsigned char)*decode))
 576                         decode++;
 577
 578                 if(!espprint_decode_encalgo(ndo, decode, &sa1)) {
 579                         return;
 580                 }
 581         }
 582
 583         esp_print_addsa(ndo, &sa1, sa_def);
 584 }
 585
 586 USES_APPLE_DEPRECATED_API
 587 static void esp_init(netdissect_options *ndo _U_)
 588 {
 589         /*
 590          * 0.9.6 doesn't appear to define OPENSSL_API_COMPAT, so
 591          * we check whether it's undefined or it's less than the
 592          * value for 1.1.0.
 593          */
 594 #if !defined(OPENSSL_API_COMPAT) || OPENSSL_API_COMPAT < 0x10100000L
 595         OpenSSL_add_all_algorithms();
 596 #endif
 597         EVP_add_cipher_alias(SN_des_ede3_cbc, "3des");
 598 }
 599 USES_APPLE_RST
 600
 601 void esp_print_decodesecret(netdissect_options *ndo)
 602 {
 603         char *line;
 604         char *p;
 605         static int initialized = 0;
 606
 607         if (!initialized) {
 608                 esp_init(ndo);
 609                 initialized = 1;
 610         }
 611
 612         p = ndo->ndo_espsecret;
 613
 614         while (p && p[0] != '\0') {
 615                 /* pick out the first line or first thing until a comma */
 616                 if ((line = strsep(&p, "\n,")) == NULL) {
 617                         line = p;
 618                         p = NULL;
 619                 }
 620
 621                 esp_print_decode_onesecret(ndo, line, "cmdline", 0);
 622         }
 623
 624         ndo->ndo_espsecret = NULL;
 625 }
 626
 627 #endif
 628
 629 #ifdef HAVE_LIBCRYPTO
 630 USES_APPLE_DEPRECATED_API
 631 #endif
 632 int
 633 esp_print(netdissect_options *ndo,
 634           const u_char *bp, const int length, const u_char *bp2
 635 #ifndef HAVE_LIBCRYPTO
 636         _U_
 637 #endif
 638         ,
 639         int *nhdr
 640 #ifndef HAVE_LIBCRYPTO
 641         _U_
 642 #endif
 643         ,
 644         int *padlen
 645 #ifndef HAVE_LIBCRYPTO
 646         _U_
 647 #endif
 648         )
 649 {
 650         register const struct newesp *esp;
 651         register const u_char *ep;
 652 #ifdef HAVE_LIBCRYPTO
 653         const struct ip *ip;
 654         struct sa_list *sa = NULL;
 655         const struct ip6_hdr *ip6 = NULL;
 656         int advance;
 657         int len;
 658         u_char *secret;
 659         int ivlen = 0;
 660         const u_char *ivoff;
 661         const u_char *p;
 662         EVP_CIPHER_CTX *ctx;
 663         unsigned int block_size, output_buffer_size;
 664         u_char *output_buffer;
 665 #endif
 666
 667         esp = (const struct newesp *)bp;
 668
 669 #ifdef HAVE_LIBCRYPTO
 670         secret = NULL;
 671         advance = 0;
 672 #endif
 673
 674 #if 0
 675         /* keep secret out of a register */
 676         p = (u_char *)&secret;
 677 #endif
 678
 679         /* 'ep' points to the end of available data. */
 680         ep = ndo->ndo_snapend;
 681
 682         if ((const u_char *)(esp + 1) >= ep) {
 683                 ND_PRINT((ndo, "[|ESP]"));
 684                 goto fail;
 685         }
 686         ND_PRINT((ndo, "ESP(spi=0x%08x", EXTRACT_32BITS(&esp->esp_spi)));
 687         ND_PRINT((ndo, ",seq=0x%x)", EXTRACT_32BITS(&esp->esp_seq)));
 688         ND_PRINT((ndo, ", length %u", length));
 689
 690 #ifndef HAVE_LIBCRYPTO
 691         goto fail;
 692 #else
 693         /* initiailize SAs */
 694         if (ndo->ndo_sa_list_head == NULL) {
 695                 if (!ndo->ndo_espsecret)
 696                         goto fail;
 697
 698                 esp_print_decodesecret(ndo);
 699         }
 700
 701         if (ndo->ndo_sa_list_head == NULL)
 702                 goto fail;
 703
 704         ip = (const struct ip *)bp2;
 705         switch (IP_V(ip)) {
 706         case 6:
 707                 ip6 = (const struct ip6_hdr *)bp2;
 708                 /* we do not attempt to decrypt jumbograms */
 709                 if (!EXTRACT_16BITS(&ip6->ip6_plen))
 710                         goto fail;
 711                 /* if we can't get nexthdr, we do not need to decrypt it */
 712                 len = sizeof(struct ip6_hdr) + EXTRACT_16BITS(&ip6->ip6_plen);
 713
 714                 /* see if we can find the SA, and if so, decode it */
 715                 for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 716                         if (sa->spi == EXTRACT_32BITS(&esp->esp_spi) &&
 717                             sa->daddr_version == 6 &&
 718                             UNALIGNED_MEMCMP(&sa->daddr.in6, &ip6->ip6_dst,
 719                                    sizeof(struct in6_addr)) == 0) {
 720                                 break;
 721                         }
 722                 }
 723                 break;
 724         case 4:
 725                 /* nexthdr & padding are in the last fragment */
 726                 if (EXTRACT_16BITS(&ip->ip_off) & IP_MF)
 727                         goto fail;
 728                 len = EXTRACT_16BITS(&ip->ip_len);
 729
 730                 /* see if we can find the SA, and if so, decode it */
 731                 for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 732                         if (sa->spi == EXTRACT_32BITS(&esp->esp_spi) &&
 733                             sa->daddr_version == 4 &&
 734                             UNALIGNED_MEMCMP(&sa->daddr.in4, &ip->ip_dst,
 735                                    sizeof(struct in_addr)) == 0) {
 736                                 break;
 737                         }
 738                 }
 739                 break;
 740         default:
 741                 goto fail;
 742         }
 743
 744         /* if we didn't find the specific one, then look for
 745          * an unspecified one.
 746          */
 747         if (sa == NULL)
 748                 sa = ndo->ndo_sa_default;
 749
 750         /* if not found fail */
 751         if (sa == NULL)
 752                 goto fail;
 753
 754         /* if we can't get nexthdr, we do not need to decrypt it */
 755         if (ep - bp2 < len)
 756                 goto fail;
 757         if (ep - bp2 > len) {
 758                 /* FCS included at end of frame (NetBSD 1.6 or later) */
 759                 ep = bp2 + len;
 760         }
 761
 762         /* pointer to the IV, if there is one */
 763         ivoff = (const u_char *)(esp + 1) + 0;
 764         /* length of the IV, if there is one; 0, if there isn't */
 765         ivlen = sa->ivlen;
 766         secret = sa->secret;
 767         ep = ep - sa->authlen;
 768
 769         if (sa->evp) {
 770                 ctx = EVP_CIPHER_CTX_new();
 771                 if (ctx != NULL) {
 772                         if (set_cipher_parameters(ctx, sa->evp, secret, NULL, 0) < 0)
 773                                 (*ndo->ndo_warning)(ndo, "espkey init failed");
 774
 775                         p = ivoff;
 776                         set_cipher_parameters(ctx, NULL, NULL, p, 0);
 777                         len = ep - (p + ivlen);
 778
 779                         /*
 780                          * Allocate a buffer for the decrypted data.
 781                          * The output buffer must be separate from the
 782                          * input buffer, and its size must be a multiple
 783                          * of the cipher block size.
 784                          */
 785                         block_size = (unsigned int)EVP_CIPHER_CTX_block_size(ctx);
 786                         output_buffer_size = len + (block_size - len % block_size);
 787                         output_buffer = (u_char *)malloc(output_buffer_size);
 788                         if (output_buffer == NULL) {
 789                                 (*ndo->ndo_warning)(ndo, "can't allocate memory for decryption buffer");
 790                                 EVP_CIPHER_CTX_free(ctx);
 791                                 return -1;
 792                         }
 793
 794                         EVP_Cipher(ctx, output_buffer, p + ivlen, len);
 795                         EVP_CIPHER_CTX_free(ctx);
 796                         /*
 797                          * XXX - of course this is wrong, because buf is a
 798                          * const buffer, but changing this would require a
 799                          * more complicated fix.
 800                          */
 801                         memcpy(p + ivlen, output_buffer, len);
 802                         free(output_buffer);
 803                         advance = ivoff - (const u_char *)esp + ivlen;
 804                 } else
 805                         advance = sizeof(struct newesp);
 806         } else
 807                 advance = sizeof(struct newesp);
 808
 809         /* sanity check for pad length */
 810         if (ep - bp < *(ep - 2))
 811                 goto fail;
 812
 813         if (padlen)
 814                 *padlen = *(ep - 2) + 2;
 815
 816         if (nhdr)
 817                 *nhdr = *(ep - 1);
 818
 819         ND_PRINT((ndo, ": "));
 820         return advance;
 821 #endif
 822
 823 fail:
 824         return -1;
 825 }
 826 #ifdef HAVE_LIBCRYPTO
 827 USES_APPLE_RST
 828 #endif
 829
 830 /*
 831  * Local Variables:
 832  * c-style: whitesmith
 833  * c-basic-offset: 8
 834  * End:
 835  */