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 #ifndef lint
  25 static const char rcsid[] _U_ =
  26     "@(#) $Header: /tcpdump/master/tcpdump/print-esp.c,v 1.50 2004-04-05 00:15:51 mcr Exp $ (LBL)";
  27 #endif
  28
  29 #ifdef HAVE_CONFIG_H
  30 #include "config.h"
  31 #endif
  32
  33 #include <string.h>
  34
  35 #include <tcpdump-stdinc.h>
  36
  37 #include <stdlib.h>
  38
  39 #ifdef HAVE_LIBCRYPTO
  40 #ifdef HAVE_OPENSSL_EVP_H
  41 #include <openssl/evp.h>
  42 #endif
  43 #endif
  44
  45 #include <stdio.h>
  46
  47 #include "ip.h"
  48 #include "esp.h"
  49 #ifdef INET6
  50 #include "ip6.h"
  51 #endif
  52
  53 #if defined(__MINGW32__) || defined(__WATCOMC__)
  54 extern char *strsep(char **stringp, const char *delim); /* Missing/strsep.c */
  55 #endif
  56
  57 #include "netdissect.h"
  58 #include "addrtoname.h"
  59 #include "extract.h"
  60
  61 #ifndef HAVE_SOCKADDR_STORAGE
  62 #ifdef INET6
  63 struct sockaddr_storage {
  64         union {
  65                 struct sockaddr_in sin;
  66                 struct sockaddr_in6 sin6;
  67         } un;
  68 };
  69 #else
  70 #define sockaddr_storage sockaddr
  71 #endif
  72 #endif /* HAVE_SOCKADDR_STORAGE */
  73
  74 #ifdef HAVE_LIBCRYPTO
  75 struct sa_list {
  76         struct sa_list  *next;
  77         struct sockaddr_storage daddr;
  78         u_int32_t       spi;
  79         const EVP_CIPHER *evp;
  80         int             ivlen;
  81         int             authlen;
  82         char            secret[256];  /* is that big enough for all secrets? */
  83         int             secretlen;
  84 };
  85
  86 static void esp_print_addsa(netdissect_options *ndo,
  87                             struct sa_list *sa, int sa_def)
  88 {
  89         /* copy the "sa" */
  90
  91         struct sa_list *nsa;
  92
  93         nsa = (struct sa_list *)malloc(sizeof(struct sa_list));
  94         if (nsa == NULL)
  95                 (*ndo->ndo_error)(ndo, "ran out of memory to allocate sa structure");
  96
  97         *nsa = *sa;
  98
  99         if (sa_def)
 100                 ndo->ndo_sa_default = nsa;
 101
 102         nsa->next = ndo->ndo_sa_list_head;
 103         ndo->ndo_sa_list_head = nsa;
 104 }
 105
 106
 107 static int hexdigit(netdissect_options *ndo, char hex)
 108 {
 109         if (hex >= '0' && hex <= '9')
 110                 return (hex - '0');
 111         else if (hex >= 'A' && hex <= 'F')
 112                 return (hex - 'A' + 10);
 113         else if (hex >= 'a' && hex <= 'f')
 114                 return (hex - 'a' + 10);
 115         else {
 116                 (*ndo->ndo_error)(ndo, "invalid hex digit %c in espsecret\n", hex);
 117                 return 0;
 118         }
 119 }
 120
 121 static int hex2byte(netdissect_options *ndo, char *hexstring)
 122 {
 123         int byte;
 124
 125         byte = (hexdigit(ndo, hexstring[0]) << 4) + hexdigit(ndo, hexstring[1]);
 126         return byte;
 127 }
 128
 129 /*
 130  * decode the form:    SPINUM@IP <tab> ALGONAME:0xsecret
 131  *
 132  * special form: file /name
 133  * causes us to go read from this file instead.
 134  *
 135  */
 136 static void esp_print_decode_onesecret(netdissect_options *ndo, char *line)
 137 {
 138         struct sa_list sa1;
 139         int sa_def;
 140
 141         char *spikey;
 142         char *decode;
 143
 144         spikey = strsep(&line, " \t");
 145         sa_def = 0;
 146         memset(&sa1, 0, sizeof(struct sa_list));
 147
 148         /* if there is only one token, then it is an algo:key token */
 149         if (line == NULL) {
 150                 decode = spikey;
 151                 spikey = NULL;
 152                 /* memset(&sa1.daddr, 0, sizeof(sa1.daddr)); */
 153                 /* sa1.spi = 0; */
 154                 sa_def    = 1;
 155         } else
 156                 decode = line;
 157
 158         if (spikey && strcasecmp(spikey, "file") == 0) {
 159                 /* open file and read it */
 160                 FILE *secretfile;
 161                 char  fileline[1024];
 162                 char  *nl;
 163
 164                 secretfile = fopen(line, FOPEN_READ_TXT);
 165                 if (secretfile == NULL) {
 166                         perror(line);
 167                         exit(3);
 168                 }
 169
 170                 while (fgets(fileline, sizeof(fileline)-1, secretfile) != NULL) {
 171                         /* remove newline from the line */
 172                         nl = strchr(fileline, '\n');
 173                         if (nl)
 174                                 *nl = '\0';
 175                         if (fileline[0] == '#') continue;
 176                         if (fileline[0] == '\0') continue;
 177
 178                         esp_print_decode_onesecret(ndo, fileline);
 179                 }
 180                 fclose(secretfile);
 181
 182                 return;
 183         }
 184
 185         if (spikey) {
 186                 char *spistr, *foo;
 187                 u_int32_t spino;
 188                 struct sockaddr_in *sin;
 189 #ifdef INET6
 190                 struct sockaddr_in6 *sin6;
 191 #endif
 192
 193                 spistr = strsep(&spikey, "@");
 194
 195                 spino = strtoul(spistr, &foo, 0);
 196                 if (spistr == foo || !spikey) {
 197                         (*ndo->ndo_warning)(ndo, "print_esp: failed to decode spi# %s\n", foo);
 198                         return;
 199                 }
 200
 201                 sa1.spi = spino;
 202
 203                 sin = (struct sockaddr_in *)&sa1.daddr;
 204 #ifdef INET6
 205                 sin6 = (struct sockaddr_in6 *)&sa1.daddr;
 206                 if (inet_pton(AF_INET6, spikey, &sin6->sin6_addr) == 1) {
 207 #ifdef HAVE_SOCKADDR_SA_LEN
 208                         sin6->sin6_len = sizeof(struct sockaddr_in6);
 209 #endif
 210                         sin6->sin6_family = AF_INET6;
 211                 } else
 212 #endif
 213                 if (inet_pton(AF_INET, spikey, &sin->sin_addr) == 1) {
 214 #ifdef HAVE_SOCKADDR_SA_LEN
 215                         sin->sin_len = sizeof(struct sockaddr_in);
 216 #endif
 217                         sin->sin_family = AF_INET;
 218                 } else {
 219                         (*ndo->ndo_warning)(ndo, "print_esp: can not decode IP# %s\n", spikey);
 220                         return;
 221                 }
 222         }
 223
 224         if (decode) {
 225                 char *colon, *p;
 226                 char  espsecret_key[256];
 227                 int len;
 228                 size_t i;
 229                 const EVP_CIPHER *evp;
 230                 int authlen = 0;
 231
 232                 /* skip any blank spaces */
 233                 while (isspace((unsigned char)*decode))
 234                         decode++;
 235
 236                 colon = strchr(decode, ':');
 237                 if (colon == NULL) {
 238                         (*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
 239                         return;
 240                 }
 241                 *colon = '\0';
 242
 243                 len = colon - decode;
 244                 if (strlen(decode) > strlen("-hmac96") &&
 245                     !strcmp(decode + strlen(decode) - strlen("-hmac96"),
 246                     "-hmac96")) {
 247                         p = strstr(decode, "-hmac96");
 248                         *p = '\0';
 249                         authlen = 12;
 250                 }
 251                 if (strlen(decode) > strlen("-cbc") &&
 252                     !strcmp(decode + strlen(decode) - strlen("-cbc"), "-cbc")) {
 253                         p = strstr(decode, "-cbc");
 254                         *p = '\0';
 255                 }
 256                 evp = EVP_get_cipherbyname(decode);
 257                 if (!evp) {
 258                         (*ndo->ndo_warning)(ndo, "failed to find cipher algo %s\n", decode);
 259                         sa1.evp = NULL;
 260                         sa1.authlen = 0;
 261                         sa1.ivlen = 0;
 262                         return;
 263                 }
 264
 265                 sa1.evp = evp;
 266                 sa1.authlen = authlen;
 267                 sa1.ivlen = EVP_CIPHER_iv_length(evp);
 268
 269                 colon++;
 270                 if (colon[0] == '0' && colon[1] == 'x') {
 271                         /* decode some hex! */
 272                         colon += 2;
 273                         len = strlen(colon) / 2;
 274
 275                         if (len > 256) {
 276                                 (*ndo->ndo_warning)(ndo, "secret is too big: %d\n", len);
 277                                 return;
 278                         }
 279
 280                         i = 0;
 281                         while (colon[0] != '\0' && colon[1]!='\0') {
 282                                 espsecret_key[i] = hex2byte(ndo, colon);
 283                                 colon += 2;
 284                                 i++;
 285                         }
 286
 287                         memcpy(sa1.secret, espsecret_key, i);
 288                         sa1.secretlen = i;
 289                 } else {
 290                         i = strlen(colon);
 291
 292                         if (i < sizeof(sa1.secret)) {
 293                                 memcpy(sa1.secret, colon, i);
 294                                 sa1.secretlen = i;
 295                         } else {
 296                                 memcpy(sa1.secret, colon, sizeof(sa1.secret));
 297                                 sa1.secretlen = sizeof(sa1.secret);
 298                         }
 299                 }
 300         }
 301
 302         esp_print_addsa(ndo, &sa1, sa_def);
 303 }
 304
 305 static void esp_print_decodesecret(netdissect_options *ndo)
 306 {
 307         char *line;
 308         char *p;
 309
 310         p = ndo->ndo_espsecret;
 311
 312         while (ndo->ndo_espsecret && ndo->ndo_espsecret[0] != '\0') {
 313                 /* pick out the first line or first thing until a comma */
 314                 if ((line = strsep(&ndo->ndo_espsecret, "\n,")) == NULL) {
 315                         line = ndo->ndo_espsecret;
 316                         ndo->ndo_espsecret = NULL;
 317                 }
 318
 319                 esp_print_decode_onesecret(ndo, line);
 320         }
 321 }
 322
 323 static void esp_init(netdissect_options *ndo _U_)
 324 {
 325
 326         OpenSSL_add_all_algorithms();
 327         EVP_add_cipher_alias(SN_des_ede3_cbc, "3des");
 328 }
 329 #endif
 330
 331 int
 332 esp_print(netdissect_options *ndo,
 333           const u_char *bp, const u_char *bp2
 334 #ifndef HAVE_LIBCRYPTO
 335         _U_
 336 #endif
 337         ,
 338         int *nhdr
 339 #ifndef HAVE_LIBCRYPTO
 340         _U_
 341 #endif
 342         ,
 343         int *padlen
 344 #ifndef HAVE_LIBCRYPTO
 345         _U_
 346 #endif
 347         )
 348 {
 349         register const struct newesp *esp;
 350         register const u_char *ep;
 351 #ifdef HAVE_LIBCRYPTO
 352         struct ip *ip;
 353         struct sa_list *sa = NULL;
 354         int espsecret_keylen;
 355 #ifdef INET6
 356         struct ip6_hdr *ip6 = NULL;
 357 #endif
 358         int advance;
 359         int len;
 360         char *secret;
 361         int ivlen = 0;
 362         u_char *ivoff;
 363         u_char *p;
 364         EVP_CIPHER_CTX ctx;
 365         int blocksz;
 366         static int initialized = 0;
 367 #endif
 368
 369         esp = (struct newesp *)bp;
 370
 371 #ifdef HAVE_LIBCRYPTO
 372         secret = NULL;
 373         advance = 0;
 374
 375         if (!initialized) {
 376                 esp_init(ndo);
 377                 initialized = 1;
 378         }
 379 #endif
 380
 381 #if 0
 382         /* keep secret out of a register */
 383         p = (u_char *)&secret;
 384 #endif
 385
 386         /* 'ep' points to the end of available data. */
 387         ep = ndo->ndo_snapend;
 388
 389         if ((u_char *)(esp + 1) >= ep) {
 390                 fputs("[|ESP]", stdout);
 391                 goto fail;
 392         }
 393         (*ndo->ndo_printf)(ndo, "ESP(spi=0x%08x", EXTRACT_32BITS(&esp->esp_spi));
 394         (*ndo->ndo_printf)(ndo, ",seq=0x%x)", EXTRACT_32BITS(&esp->esp_seq));
 395
 396 #ifndef HAVE_LIBCRYPTO
 397         goto fail;
 398 #else
 399         /* initiailize SAs */
 400         if (ndo->ndo_sa_list_head == NULL) {
 401                 if (!ndo->ndo_espsecret)
 402                         goto fail;
 403
 404                 esp_print_decodesecret(ndo);
 405         }
 406
 407         if (ndo->ndo_sa_list_head == NULL)
 408                 goto fail;
 409
 410         ip = (struct ip *)bp2;
 411         switch (IP_V(ip)) {
 412 #ifdef INET6
 413         case 6:
 414                 ip6 = (struct ip6_hdr *)bp2;
 415                 /* we do not attempt to decrypt jumbograms */
 416                 if (!EXTRACT_16BITS(&ip6->ip6_plen))
 417                         goto fail;
 418                 /* if we can't get nexthdr, we do not need to decrypt it */
 419                 len = sizeof(struct ip6_hdr) + EXTRACT_16BITS(&ip6->ip6_plen);
 420
 421                 /* see if we can find the SA, and if so, decode it */
 422                 for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 423                         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&sa->daddr;
 424                         if (sa->spi == ntohl(esp->esp_spi) &&
 425                             sin6->sin6_family == AF_INET6 &&
 426                             memcmp(&sin6->sin6_addr, &ip6->ip6_dst,
 427                                    sizeof(struct in6_addr)) == 0) {
 428                                 break;
 429                         }
 430                 }
 431                 break;
 432 #endif /*INET6*/
 433         case 4:
 434                 /* nexthdr & padding are in the last fragment */
 435                 if (EXTRACT_16BITS(&ip->ip_off) & IP_MF)
 436                         goto fail;
 437                 len = EXTRACT_16BITS(&ip->ip_len);
 438
 439                 /* see if we can find the SA, and if so, decode it */
 440                 for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
 441                         struct sockaddr_in *sin = (struct sockaddr_in *)&sa->daddr;
 442                         if (sa->spi == ntohl(esp->esp_spi) &&
 443                             sin->sin_family == AF_INET &&
 444                             sin->sin_addr.s_addr == ip->ip_dst.s_addr) {
 445                                 break;
 446                         }
 447                 }
 448                 break;
 449         default:
 450                 goto fail;
 451         }
 452
 453         /* if we didn't find the specific one, then look for
 454          * an unspecified one.
 455          */
 456         if (sa == NULL)
 457                 sa = ndo->ndo_sa_default;
 458
 459         /* if not found fail */
 460         if (sa == NULL)
 461                 goto fail;
 462
 463         /* if we can't get nexthdr, we do not need to decrypt it */
 464         if (ep - bp2 < len)
 465                 goto fail;
 466         if (ep - bp2 > len) {
 467                 /* FCS included at end of frame (NetBSD 1.6 or later) */
 468                 ep = bp2 + len;
 469         }
 470
 471         ivoff = (u_char *)(esp + 1) + 0;
 472         ivlen = sa->ivlen;
 473         secret = sa->secret;
 474         espsecret_keylen = sa->secretlen;
 475
 476         if (sa->evp) {
 477                 memset(&ctx, 0, sizeof(ctx));
 478                 if (EVP_CipherInit(&ctx, sa->evp, secret, NULL, 0) < 0)
 479                         (*ndo->ndo_warning)(ndo, "espkey init failed");
 480
 481                 blocksz = EVP_CIPHER_CTX_block_size(&ctx);
 482
 483                 p = ivoff;
 484                 EVP_CipherInit(&ctx, NULL, NULL, p, 0);
 485                 EVP_Cipher(&ctx, p + ivlen, p + ivlen, ep - (p + ivlen));
 486                 advance = ivoff - (u_char *)esp + ivlen;
 487         } else
 488                 advance = sizeof(struct newesp);
 489
 490         ep = ep - sa->authlen;
 491         /* sanity check for pad length */
 492         if (ep - bp < *(ep - 2))
 493                 goto fail;
 494
 495         if (padlen)
 496                 *padlen = *(ep - 2) + 2;
 497
 498         if (nhdr)
 499                 *nhdr = *(ep - 1);
 500
 501         (ndo->ndo_printf)(ndo, ": ");
 502         return advance;
 503 #endif
 504
 505 fail:
 506         return -1;
 507 }
 508
 509 /*
 510  * Local Variables:
 511  * c-style: whitesmith
 512  * c-basic-offset: 8
 513  * End:
 514  */