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 1.28 2002-08-01 08:53:05 risso 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 #include <openssl/des.h>
  41 #include <openssl/blowfish.h>
  42 #ifdef HAVE_OPENSSL_RC5_H
  43 #include <openssl/rc5.h>
  44 #endif
  45 #ifdef HAVE_OPENSSL_CAST_H
  46 #include <openssl/cast.h>
  47 #endif
  48 #endif
  49
  50 #include <stdio.h>
  51
  52 #include "ip.h"
  53 #include "esp.h"
  54 #ifdef INET6
  55 #include "ip6.h"
  56 #endif
  57
  58 #define AVOID_CHURN 1
  59 #include "interface.h"
  60 #include "addrtoname.h"
  61
  62 static struct esp_algorithm *espsecret_xform=NULL;  /* cache of decoded alg. */
  63 static char                 *espsecret_key=NULL;
  64
  65
  66 enum cipher { NONE,
  67               DESCBC,
  68               BLOWFISH,
  69               RC5,
  70               CAST128,
  71               DES3CBC};
  72
  73
  74
  75 struct esp_algorithm {
  76         char        *name;
  77         enum  cipher algo;
  78         int          ivlen;
  79         int          authlen;
  80         int          replaysize;
  81 };
  82
  83 struct esp_algorithm esp_xforms[]={
  84         {"none",                  NONE,    0,  0, 0},
  85         {"des-cbc",               DESCBC,  8,  0, 0},
  86         {"des-cbc-hmac96",        DESCBC,  8, 12, 4},
  87         {"blowfish-cbc",          BLOWFISH,8,  0, 0},
  88         {"blowfish-cbc-hmac96",   BLOWFISH,8, 12, 4},
  89         {"rc5-cbc",               RC5,     8,  0, 0},
  90         {"rc5-cbc-hmac96",        RC5,     8, 12, 4},
  91         {"cast128-cbc",           CAST128, 8,  0, 0},
  92         {"cast128-cbc-hmac96",    CAST128, 8, 12, 4},
  93         {"3des-cbc-hmac96",       DES3CBC, 8, 12, 4},
  94         {NULL,                    NONE,    0,  0, 0}
  95 };
  96
  97 static int hexdigit(char hex)
  98 {
  99         if(hex >= '0' && hex <= '9') {
 100                 return (hex - '0');
 101         } else if(hex >= 'A' && hex <= 'F') {
 102                 return (hex - 'A' + 10);
 103         } else if(hex >= 'a' && hex <= 'f') {
 104                 return (hex - 'a' + 10);
 105         } else {
 106                 printf("invalid hex digit %c in espsecret\n", hex);
 107                 return 0;
 108         }
 109 }
 110
 111 static int hex2byte(char *hexstring)
 112 {
 113         int byte;
 114
 115         byte = (hexdigit(hexstring[0]) << 4) +
 116                 hexdigit(hexstring[1]);
 117         return byte;
 118 }
 119
 120
 121 static void esp_print_decodesecret(void)
 122 {
 123         char *colon;
 124         int   len, i;
 125         struct esp_algorithm *xf;
 126         struct esp_algorithm *null_xf =
 127                 &esp_xforms[sizeof(esp_xforms)/sizeof(esp_xforms[0]) - 1];
 128
 129         if(espsecret == NULL) {
 130                 /* set to NULL transform */
 131                 espsecret_xform = null_xf;
 132                 return;
 133         }
 134
 135         if(espsecret_key != NULL) {
 136                 return;
 137         }
 138
 139         colon = strchr(espsecret, ':');
 140         if(colon == NULL) {
 141                 printf("failed to decode espsecret: %s\n",
 142                        espsecret);
 143                 /* set to NULL transform */
 144                 espsecret_xform = null_xf;
 145                 return;
 146         }
 147
 148         len = colon - espsecret;
 149         xf = esp_xforms;
 150         while(xf->name && strncasecmp(espsecret, xf->name, len)!=0) {
 151                 xf++;
 152         }
 153         if(xf->name == NULL) {
 154                 printf("failed to find cipher algo %s\n",
 155                        espsecret);
 156                 /* set to NULL transform */
 157                 espsecret_xform = null_xf;
 158                 return;
 159         }
 160         espsecret_xform = xf;
 161
 162         colon++;
 163         if(colon[0]=='0' && colon[1]=='x') {
 164                 /* decode some hex! */
 165                 colon+=2;
 166                 len = strlen(colon) / 2;
 167                 espsecret_key = (char *)malloc(len);
 168                 if(espsecret_key == NULL) {
 169                   fprintf(stderr, "%s: ran out of memory (%d) to allocate secret key\n",
 170                           program_name, len);
 171                   exit(2);
 172                 }
 173                 i = 0;
 174                 while(colon[0] != '\0' && colon[1]!='\0') {
 175                         espsecret_key[i]=hex2byte(colon);
 176                         colon+=2;
 177                         i++;
 178                 }
 179         } else {
 180                 espsecret_key = colon;
 181         }
 182 }
 183
 184 int
 185 esp_print(register const u_char *bp, register const u_char *bp2,
 186           int *nhdr, int *padlen)
 187 {
 188         register const struct newesp *esp;
 189         register const u_char *ep;
 190         struct ip *ip = NULL;
 191 #ifdef INET6
 192         struct ip6_hdr *ip6 = NULL;
 193 #endif
 194         int advance;
 195         int len;
 196         char *secret;
 197         int ivlen = 0;
 198         u_char *ivoff;
 199 #ifdef HAVE_LIBCRYPTO
 200         u_char *p;
 201 #endif
 202
 203         esp = (struct newesp *)bp;
 204         secret = NULL;
 205
 206 #if 0
 207         /* keep secret out of a register */
 208         p = (u_char *)&secret;
 209 #endif
 210
 211         /* 'ep' points to the end of available data. */
 212         ep = snapend;
 213
 214         if ((u_char *)(esp + 1) >= ep) {
 215                 fputs("[|ESP]", stdout);
 216                 goto fail;
 217         }
 218         printf("ESP(spi=0x%08x", (u_int32_t)ntohl(esp->esp_spi));
 219         printf(",seq=0x%x", (u_int32_t)ntohl(esp->esp_seq));
 220         printf(")");
 221
 222         /* if we don't have decryption key, we can't decrypt this packet. */
 223         if (!espsecret)
 224                 goto fail;
 225
 226         if(!espsecret_xform) {
 227                 esp_print_decodesecret();
 228         }
 229         if(espsecret_xform->name == NULL) {
 230                 goto fail;
 231         }
 232
 233         ip = (struct ip *)bp2;
 234         switch (IP_V(ip)) {
 235 #ifdef INET6
 236         case 6:
 237                 ip6 = (struct ip6_hdr *)bp2;
 238                 ip = NULL;
 239                 /* we do not attempt to decrypt jumbograms */
 240                 if (!ntohs(ip6->ip6_plen))
 241                         goto fail;
 242                 /* if we can't get nexthdr, we do not need to decrypt it */
 243                 len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
 244                 break;
 245 #endif /*INET6*/
 246         case 4:
 247                 /* nexthdr & padding are in the last fragment */
 248                 if (ntohs(ip->ip_off) & IP_MF)
 249                         goto fail;
 250 #ifdef INET6
 251                 ip6 = NULL;
 252 #endif
 253                 len = ntohs(ip->ip_len);
 254                 break;
 255         default:
 256                 goto fail;
 257         }
 258
 259         /* if we can't get nexthdr, we do not need to decrypt it */
 260         if (ep - bp2 < len)
 261                 goto fail;
 262
 263         ivoff = (u_char *)(esp + 1) + espsecret_xform->replaysize;
 264         ivlen = espsecret_xform->ivlen;
 265         secret = espsecret_key;
 266
 267         switch (espsecret_xform->algo) {
 268         case DESCBC:
 269 #ifdef HAVE_LIBCRYPTO
 270             {
 271                 u_char iv[8];
 272 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
 273                 DES_key_schedule schedule;
 274 #else
 275                 des_key_schedule schedule;
 276 #endif
 277
 278                 switch (ivlen) {
 279                 case 4:
 280                         memcpy(iv, ivoff, 4);
 281                         memcpy(&iv[4], ivoff, 4);
 282                         p = &iv[4];
 283                         *p++ ^= 0xff;
 284                         *p++ ^= 0xff;
 285                         *p++ ^= 0xff;
 286                         *p++ ^= 0xff;
 287                         break;
 288                 case 8:
 289                         memcpy(iv, ivoff, 8);
 290                         break;
 291                 default:
 292                         goto fail;
 293                 }
 294                 p = ivoff + ivlen;
 295
 296 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
 297                 DES_set_key_unchecked((DES_cblock *)secret, schedule);
 298
 299                 DES_cbc_encrypt((const unsigned char *)p, p,
 300                         (long)(ep - p), schedule, (DES_cblock *)iv,
 301                         DES_DECRYPT);
 302 #else
 303                 des_check_key = 0;
 304                 des_set_key((void *)secret, schedule);
 305
 306                 des_cbc_encrypt((void *)p, (void *)p,
 307                         (long)(ep - p), schedule, (void *)iv,
 308                         DES_DECRYPT);
 309 #endif
 310                 advance = ivoff - (u_char *)esp + ivlen;
 311                 break;
 312             }
 313 #else
 314                 goto fail;
 315 #endif /*HAVE_LIBCRYPTO*/
 316
 317         case BLOWFISH:
 318 #ifdef HAVE_LIBCRYPTO
 319             {
 320                 BF_KEY schedule;
 321
 322                 BF_set_key(&schedule, strlen(secret), secret);
 323
 324                 p = ivoff + ivlen;
 325                 BF_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 326                         BF_DECRYPT);
 327                 advance = ivoff - (u_char *)esp + ivlen;
 328                 break;
 329             }
 330 #else
 331                 goto fail;
 332 #endif /*HAVE_LIBCRYPTO*/
 333
 334         case RC5:
 335 #if defined(HAVE_LIBCRYPTO) && defined(HAVE_RC5_H)
 336             {
 337                 RC5_32_KEY schedule;
 338
 339                 RC5_32_set_key(&schedule, strlen(secret), secret,
 340                         RC5_16_ROUNDS);
 341
 342                 p = ivoff + ivlen;
 343                 RC5_32_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 344                         RC5_DECRYPT);
 345                 advance = ivoff - (u_char *)esp + ivlen;
 346                 break;
 347             }
 348 #else
 349                 goto fail;
 350 #endif /*HAVE_LIBCRYPTO*/
 351
 352         case CAST128:
 353 #if defined(HAVE_LIBCRYPTO) && defined(HAVE_CAST_H) && !defined(HAVE_BUGGY_CAST128)
 354             {
 355                 CAST_KEY schedule;
 356
 357                 CAST_set_key(&schedule, strlen(secret), secret);
 358
 359                 p = ivoff + ivlen;
 360                 CAST_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 361                         CAST_DECRYPT);
 362                 advance = ivoff - (u_char *)esp + ivlen;
 363                 break;
 364             }
 365 #else
 366                 goto fail;
 367 #endif /*HAVE_LIBCRYPTO*/
 368
 369         case DES3CBC:
 370 #if defined(HAVE_LIBCRYPTO)
 371             {
 372 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
 373                 DES_key_schedule s1, s2, s3;
 374
 375                 DES_set_odd_parity((DES_cblock *)secret);
 376                 DES_set_odd_parity((DES_cblock *)(secret + 8));
 377                 DES_set_odd_parity((DES_cblock *)(secret + 16));
 378                 if(DES_set_key_checked((DES_cblock *)secret, s1) != 0) {
 379                   printf("failed to schedule key 1\n");
 380                 }
 381                 if(DES_set_key_checked((DES_cblock *)(secret + 8), s2)!=0) {
 382                   printf("failed to schedule key 2\n");
 383                 }
 384                 if(DES_set_key_checked((DES_cblock *)(secret + 16), s3)!=0) {
 385                   printf("failed to schedule key 3\n");
 386                 }
 387
 388                 p = ivoff + ivlen;
 389                 DES_ede3_cbc_encrypt((const unsigned char *)p, p,
 390                                      (long)(ep - p),
 391                                      &s1, &s2, &s3,
 392                                      (DES_cblock *)ivoff, DES_DECRYPT);
 393 #else
 394                 des_key_schedule s1, s2, s3;
 395
 396                 des_check_key = 1;
 397                 des_set_odd_parity((void *)secret);
 398                 des_set_odd_parity((void *)(secret + 8));
 399                 des_set_odd_parity((void *)(secret + 16));
 400                 if(des_set_key((void *)secret, s1) != 0) {
 401                   printf("failed to schedule key 1\n");
 402                 }
 403                 if(des_set_key((void *)(secret + 8), s2)!=0) {
 404                   printf("failed to schedule key 2\n");
 405                 }
 406                 if(des_set_key((void *)(secret + 16), s3)!=0) {
 407                   printf("failed to schedule key 3\n");
 408                 }
 409
 410                 p = ivoff + ivlen;
 411                 des_ede3_cbc_encrypt((void *)p, (void *)p,
 412                                      (long)(ep - p),
 413                                      s1, s2, s3,
 414                                      (void *)ivoff, DES_DECRYPT);
 415 #endif
 416                 advance = ivoff - (u_char *)esp + ivlen;
 417                 break;
 418             }
 419 #else
 420                 goto fail;
 421 #endif /*HAVE_LIBCRYPTO*/
 422
 423         case NONE:
 424         default:
 425                 advance = sizeof(struct newesp) + espsecret_xform->replaysize;
 426                 break;
 427         }
 428
 429         ep = ep - espsecret_xform->authlen;
 430         /* sanity check for pad length */
 431         if (ep - bp < *(ep - 2))
 432                 goto fail;
 433
 434         if (padlen)
 435                 *padlen = *(ep - 2) + 2;
 436
 437         if (nhdr)
 438                 *nhdr = *(ep - 1);
 439
 440         printf(": ");
 441         return advance;
 442
 443 fail:
 444         if (nhdr)
 445                 *nhdr = -1;
 446         return 65536;
 447 }