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[] =
  26     "@(#) $Header: /tcpdump/master/tcpdump/print-esp.c,v 1.41 2003-07-17 13:31:02 itojun 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 "interface.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 struct sa_list {
  75         struct sa_list  *next;
  76         struct sockaddr_storage daddr;
  77         u_int32_t       spi;
  78         const EVP_CIPHER *evp;
  79         int             ivlen;
  80         int             authlen;
  81         char            secret[256];  /* is that big enough for all secrets? */
  82         int             secretlen;
  83 };
  84
  85 static struct sa_list *sa_list_head = NULL;
  86 static struct sa_list *sa_default = NULL;
  87
  88 static void esp_print_addsa(struct sa_list *sa, int sa_def)
  89 {
  90         /* copy the "sa" */
  91
  92         struct sa_list *nsa;
  93
  94         nsa = (struct sa_list *)malloc(sizeof(struct sa_list));
  95         if (nsa == NULL)
  96                 error("ran out of memory to allocate sa structure");
  97
  98         *nsa = *sa;
  99
 100         if (sa_def)
 101                 sa_default = nsa;
 102
 103         nsa->next = sa_list_head;
 104         sa_list_head = nsa;
 105 }
 106
 107
 108 static int hexdigit(char hex)
 109 {
 110         if (hex >= '0' && hex <= '9')
 111                 return (hex - '0');
 112         else if (hex >= 'A' && hex <= 'F')
 113                 return (hex - 'A' + 10);
 114         else if (hex >= 'a' && hex <= 'f')
 115                 return (hex - 'a' + 10);
 116         else {
 117                 printf("invalid hex digit %c in espsecret\n", hex);
 118                 return 0;
 119         }
 120 }
 121
 122 static int hex2byte(char *hexstring)
 123 {
 124         int byte;
 125
 126         byte = (hexdigit(hexstring[0]) << 4) + hexdigit(hexstring[1]);
 127         return byte;
 128 }
 129
 130 /*
 131  * decode the form:    SPINUM@IP <tab> ALGONAME:0xsecret
 132  *
 133  * special form: file /name
 134  * causes us to go read from this file instead.
 135  *
 136  */
 137 static void esp_print_decode_onesecret(char *line)
 138 {
 139         struct sa_list sa1;
 140         int sa_def;
 141
 142         char *spikey;
 143         char *decode;
 144
 145         spikey = strsep(&line, " \t");
 146         sa_def = 0;
 147         memset(&sa1, 0, sizeof(struct sa_list));
 148
 149         /* if there is only one token, then it is an algo:key token */
 150         if (line == NULL) {
 151                 decode = spikey;
 152                 spikey = NULL;
 153                 /* memset(&sa1.daddr, 0, sizeof(sa1.daddr)); */
 154                 /* sa1.spi = 0; */
 155                 sa_def    = 1;
 156         } else
 157                 decode = line;
 158
 159         if (spikey && strcasecmp(spikey, "file") == 0) {
 160                 /* open file and read it */
 161                 FILE *secretfile;
 162                 char  fileline[1024];
 163                 char  *nl;
 164
 165                 secretfile = fopen(line, FOPEN_READ_TXT);
 166                 if (secretfile == NULL) {
 167                         perror(line);
 168                         exit(3);
 169                 }
 170
 171                 while (fgets(fileline, sizeof(fileline)-1, secretfile) != NULL) {
 172                         /* remove newline from the line */
 173                         nl = strchr(fileline, '\n');
 174                         if (nl)
 175                                 *nl = '\0';
 176                         if (fileline[0] == '#') continue;
 177                         if (fileline[0] == '\0') continue;
 178
 179                         esp_print_decode_onesecret(fileline);
 180                 }
 181                 fclose(secretfile);
 182
 183                 return;
 184         }
 185
 186         if (spikey) {
 187                 char *spistr, *foo;
 188                 u_int32_t spino;
 189                 struct sockaddr_in *sin;
 190 #ifdef INET6
 191                 struct sockaddr_in6 *sin6;
 192 #endif
 193
 194                 spistr = strsep(&spikey, "@");
 195
 196                 spino = strtoul(spistr, &foo, 0);
 197                 if (spistr == foo || !spikey) {
 198                         printf("print_esp: failed to decode spi# %s\n", foo);
 199                         return;
 200                 }
 201
 202                 sa1.spi = spino;
 203
 204                 sin = (struct sockaddr_in *)&sa1.daddr;
 205 #ifdef INET6
 206                 sin6 = (struct sockaddr_in6 *)&sa1.daddr;
 207                 if (inet_pton(AF_INET6, spikey, &sin6->sin6_addr) == 1) {
 208 #ifdef HAVE_SOCKADDR_SA_LEN
 209                         sin6->sin6_len = sizeof(struct sockaddr_in6);
 210 #endif
 211                         sin6->sin6_family = AF_INET6;
 212                 } else
 213 #endif
 214                 if (inet_pton(AF_INET, spikey, &sin->sin_addr) == 1) {
 215 #ifdef HAVE_SOCKADDR_SA_LEN
 216                         sin->sin_len = sizeof(struct sockaddr_in);
 217 #endif
 218                         sin->sin_family = AF_INET;
 219                 } else {
 220                         printf("print_esp: can not decode IP# %s\n", spikey);
 221                         return;
 222                 }
 223         }
 224
 225         if (decode) {
 226                 char *colon, *p;
 227                 char  espsecret_key[256];
 228                 int len, i;
 229                 const EVP_CIPHER *evp;
 230                 int ivlen = 8;
 231                 int authlen = 0;
 232
 233                 /* skip any blank spaces */
 234                 while (isspace((unsigned char)*decode))
 235                         decode++;
 236
 237                 colon = strchr(decode, ':');
 238                 if (colon == NULL) {
 239                         printf("failed to decode espsecret: %s\n", decode);
 240                         return;
 241                 }
 242                 *colon = '\0';
 243
 244                 len = colon - decode;
 245                 if (strlen(decode) > strlen("-hmac96") &&
 246                     !strcmp(decode + strlen(decode) - strlen("-hmac96"),
 247                     "-hmac96")) {
 248                         p = strstr(decode, "-hmac96");
 249                         *p = '\0';
 250                         authlen = 12;
 251                 }
 252                 if (strlen(decode) > strlen("-cbc") &&
 253                     !strcmp(decode + strlen(decode) - strlen("-cbc"), "-cbc")) {
 254                         p = strstr(decode, "-cbc");
 255                         *p = '\0';
 256                 }
 257                 evp = EVP_get_cipherbyname(decode);
 258                 if (!evp) {
 259                         printf("failed to find cipher algo %s\n", decode);
 260                         sa1.evp = NULL;
 261                         sa1.authlen = 0;
 262                         sa1.ivlen = 0;
 263                         return;
 264                 }
 265
 266                 sa1.evp = evp;
 267                 sa1.authlen = authlen;
 268                 sa1.ivlen = ivlen;
 269
 270                 colon++;
 271                 if (colon[0] == '0' && colon[1] == 'x') {
 272                         /* decode some hex! */
 273                         colon += 2;
 274                         len = strlen(colon) / 2;
 275
 276                         if (len > 256) {
 277                                 printf("secret is too big: %d\n", len);
 278                                 return;
 279                         }
 280
 281                         i = 0;
 282                         while (colon[0] != '\0' && colon[1]!='\0') {
 283                                 espsecret_key[i] = hex2byte(colon);
 284                                 colon += 2;
 285                                 i++;
 286                         }
 287
 288                         memcpy(sa1.secret, espsecret_key, i);
 289                         sa1.secretlen = i;
 290                 } else {
 291                         i = strlen(colon);
 292
 293                         if (i < sizeof(sa1.secret)) {
 294                                 memcpy(sa1.secret, colon, i);
 295                                 sa1.secretlen = i;
 296                         } else {
 297                                 memcpy(sa1.secret, colon, sizeof(sa1.secret));
 298                                 sa1.secretlen = sizeof(sa1.secret);
 299                         }
 300                 }
 301         }
 302
 303         esp_print_addsa(&sa1, sa_def);
 304 }
 305
 306 static void esp_print_decodesecret(void)
 307 {
 308         char *line;
 309         char *p;
 310
 311         p = espsecret;
 312
 313         while (espsecret && espsecret[0] != '\0') {
 314                 /* pick out the first line or first thing until a comma */
 315                 if ((line = strsep(&espsecret, "\n,")) == NULL) {
 316                         line = espsecret;
 317                         espsecret = NULL;
 318                 }
 319
 320                 esp_print_decode_onesecret(line);
 321         }
 322 }
 323
 324 static void esp_init(void)
 325 {
 326
 327         OpenSSL_add_all_algorithms();
 328         EVP_add_cipher_alias(SN_des_ede3_cbc, "3des");
 329 }
 330
 331 int
 332 esp_print(const u_char *bp, const u_char *bp2, int *nhdr, int *padlen)
 333 {
 334         register const struct newesp *esp;
 335         register const u_char *ep;
 336         struct ip *ip;
 337         struct sa_list *sa = NULL;
 338         int espsecret_keylen;
 339 #ifdef INET6
 340         struct ip6_hdr *ip6 = NULL;
 341 #endif
 342         int advance;
 343         int len;
 344         char *secret;
 345         int ivlen = 0;
 346         u_char *ivoff;
 347 #ifdef HAVE_LIBCRYPTO
 348         const u_char *p;
 349         EVP_CIPHER_CTX ctx;
 350         int blocksz;
 351         static int initialized = 0;
 352 #endif
 353
 354         esp = (struct newesp *)bp;
 355         secret = NULL;
 356         advance = 0;
 357
 358 #ifdef HAVE_LIBCRYPTO
 359         if (!initialized) {
 360                 esp_init();
 361                 initialized = 1;
 362         }
 363 #endif
 364
 365 #if 0
 366         /* keep secret out of a register */
 367         p = (u_char *)&secret;
 368 #endif
 369
 370         /* 'ep' points to the end of available data. */
 371         ep = snapend;
 372
 373         if ((u_char *)(esp + 1) >= ep) {
 374                 fputs("[|ESP]", stdout);
 375                 goto fail;
 376         }
 377         printf("ESP(spi=0x%08x", EXTRACT_32BITS(&esp->esp_spi));
 378         printf(",seq=0x%x", EXTRACT_32BITS(&esp->esp_seq));
 379         printf(")");
 380
 381         /* initiailize SAs */
 382         if (sa_list_head == NULL) {
 383                 if (!espsecret)
 384                         goto fail;
 385
 386                 esp_print_decodesecret();
 387         }
 388
 389         if (sa_list_head == NULL)
 390                 goto fail;
 391
 392         ip = (struct ip *)bp2;
 393         switch (IP_V(ip)) {
 394 #ifdef INET6
 395         case 6:
 396                 ip6 = (struct ip6_hdr *)bp2;
 397                 /* we do not attempt to decrypt jumbograms */
 398                 if (!EXTRACT_16BITS(&ip6->ip6_plen))
 399                         goto fail;
 400                 /* if we can't get nexthdr, we do not need to decrypt it */
 401                 len = sizeof(struct ip6_hdr) + EXTRACT_16BITS(&ip6->ip6_plen);
 402
 403                 /* see if we can find the SA, and if so, decode it */
 404                 for (sa = sa_list_head; sa != NULL; sa = sa->next) {
 405                         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&sa->daddr;
 406                         if (sa->spi == ntohl(esp->esp_spi) &&
 407                             sin6->sin6_family == AF_INET6 &&
 408                             memcmp(&sin6->sin6_addr, &ip6->ip6_dst,
 409                                    sizeof(struct in6_addr)) == 0) {
 410                                 break;
 411                         }
 412                 }
 413                 break;
 414 #endif /*INET6*/
 415         case 4:
 416                 /* nexthdr & padding are in the last fragment */
 417                 if (EXTRACT_16BITS(&ip->ip_off) & IP_MF)
 418                         goto fail;
 419                 len = EXTRACT_16BITS(&ip->ip_len);
 420
 421                 /* see if we can find the SA, and if so, decode it */
 422                 for (sa = sa_list_head; sa != NULL; sa = sa->next) {
 423                         struct sockaddr_in *sin = (struct sockaddr_in *)&sa->daddr;
 424                         if (sa->spi == ntohl(esp->esp_spi) &&
 425                             sin->sin_family == AF_INET &&
 426                             sin->sin_addr.s_addr == ip->ip_dst.s_addr) {
 427                                 break;
 428                         }
 429                 }
 430                 break;
 431         default:
 432                 goto fail;
 433         }
 434
 435         /* if we didn't find the specific one, then look for
 436          * an unspecified one.
 437          */
 438         if (sa == NULL)
 439                 sa = sa_default;
 440
 441         /* if not found fail */
 442         if (sa == NULL)
 443                 goto fail;
 444
 445         /* if we can't get nexthdr, we do not need to decrypt it */
 446         if (ep - bp2 < len)
 447                 goto fail;
 448         if (ep - bp2 > len) {
 449                 /* FCS included at end of frame (NetBSD 1.6 or later) */
 450                 ep = bp2 + len;
 451         }
 452
 453         ivoff = (u_char *)(esp + 1) + 0;
 454         ivlen = sa->ivlen;
 455         secret = sa->secret;
 456         espsecret_keylen = sa->secretlen;
 457
 458         if (sa->evp) {
 459                 memset(&ctx, 0, sizeof(ctx));
 460                 if (EVP_CipherInit(&ctx, sa->evp, secret, NULL, 0) < 0)
 461                         printf("espkey init failed");
 462
 463                 blocksz = EVP_CIPHER_CTX_block_size(&ctx);
 464
 465                 p = ivoff;
 466                 EVP_CipherInit(&ctx, NULL, NULL, p, 0);
 467                 EVP_Cipher(&ctx, p + ivlen, p + ivlen, ep - (p + ivlen));
 468                 advance = ivoff - (u_char *)esp + ivlen;
 469         } else
 470                 advance = sizeof(struct newesp);
 471
 472         ep = ep - sa->authlen;
 473         /* sanity check for pad length */
 474         if (ep - bp < *(ep - 2))
 475                 goto fail;
 476
 477         if (padlen)
 478                 *padlen = *(ep - 2) + 2;
 479
 480         if (nhdr)
 481                 *nhdr = *(ep - 1);
 482
 483         printf(": ");
 484         return advance;
 485
 486 fail:
 487         if (nhdr)
 488                 *nhdr = -1;
 489         return 65536;
 490 }