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 1.21 2002-01-23 05:23:16 itojun Exp $ (LBL)";
  27 #endif
  28
  29 #ifdef HAVE_CONFIG_H
  30 #include "config.h"
  31 #endif
  32
  33 #include <string.h>
  34 #include <sys/param.h>
  35 #include <sys/time.h>
  36 #include <sys/types.h>
  37 #include <sys/socket.h>
  38 #include <stdlib.h>
  39
  40 #include <netinet/in.h>
  41
  42 #ifdef HAVE_LIBCRYPTO
  43 #include <openssl/des.h>
  44 #include <openssl/blowfish.h>
  45 #ifdef HAVE_RC5_H
  46 #include <openssl/rc5.h>
  47 #endif
  48 #ifdef HAVE_CAST_H
  49 #include <openssl/cast.h>
  50 #endif
  51 #endif
  52
  53 #include <stdio.h>
  54
  55 #include "ip.h"
  56 #include "esp.h"
  57 #ifdef INET6
  58 #include "ip6.h"
  59 #endif
  60
  61 #define AVOID_CHURN 1
  62 #include "interface.h"
  63 #include "addrtoname.h"
  64
  65 static struct esp_algorithm *espsecret_xform=NULL;  /* cache of decoded alg. */
  66 static char                 *espsecret_key=NULL;
  67
  68
  69 enum cipher { NONE,
  70               DESCBC,
  71               BLOWFISH,
  72               RC5,
  73               CAST128,
  74               DES3CBC};
  75
  76
  77
  78 struct esp_algorithm {
  79         char        *name;
  80         enum  cipher algo;
  81         int          ivlen;
  82         int          authlen;
  83         int          replaysize;
  84 };
  85
  86 struct esp_algorithm esp_xforms[]={
  87         {"none",                  NONE,    0,  0, 0},
  88         {"des-cbc",               DESCBC,  8,  0, 0},
  89         {"des-cbc-hmac96",        DESCBC,  8, 12, 4},
  90         {"blowfish-cbc",          BLOWFISH,8,  0, 0},
  91         {"blowfish-cbc-hmac96",   BLOWFISH,8, 12, 4},
  92         {"rc5-cbc",               RC5,     8,  0, 0},
  93         {"rc5-cbc-hmac96",        RC5,     8, 12, 4},
  94         {"cast128-cbc",           CAST128, 8,  0, 0},
  95         {"cast128-cbc-hmac96",    CAST128, 8, 12, 4},
  96         {"3des-cbc-hmac96",       DES3CBC, 8, 12, 4},
  97 };
  98
  99 static int hexdigit(char hex)
 100 {
 101         if(hex >= '0' && hex <= '9') {
 102                 return (hex - '0');
 103         } else if(hex >= 'A' && hex <= 'F') {
 104                 return (hex - 'A' + 10);
 105         } else if(hex >= 'a' && hex <= 'f') {
 106                 return (hex - 'a' + 10);
 107         } else {
 108                 printf("invalid hex digit %c in espsecret\n", hex);
 109                 return 0;
 110         }
 111 }
 112
 113 static int hex2byte(char *hexstring)
 114 {
 115         int byte;
 116
 117         byte = (hexdigit(hexstring[0]) << 4) +
 118                 hexdigit(hexstring[1]);
 119         return byte;
 120 }
 121
 122
 123 static void esp_print_decodesecret(void)
 124 {
 125         char *colon;
 126         int   len, i;
 127         struct esp_algorithm *xf;
 128
 129         if(espsecret == NULL) {
 130                 /* set to NONE transform */
 131                 espsecret_xform = esp_xforms;
 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 NONE transform */
 144                 espsecret_xform = esp_xforms;
 145         }
 146
 147         len   = colon - espsecret;
 148         xf = esp_xforms;
 149         while(xf->name && strncasecmp(espsecret, xf->name, len)!=0) {
 150                 xf++;
 151         }
 152         if(xf->name == NULL) {
 153                 printf("failed to find cipher algo %s\n",
 154                        espsecret);
 155                 espsecret_xform = esp_xforms;
 156                 return;
 157         }
 158         espsecret_xform = xf;
 159
 160         colon++;
 161         if(colon[0]=='0' && colon[1]=='x') {
 162                 /* decode some hex! */
 163                 colon+=2;
 164                 len = strlen(colon) / 2;
 165                 espsecret_key = (char *)malloc(len);
 166                 if(espsecret_key == NULL) {
 167                   fprintf(stderr, "%s: ran out of memory (%d) to allocate secret key\n",
 168                           program_name, len);
 169                   exit(2);
 170                 }
 171                 i = 0;
 172                 while(colon[0] != '\0' && colon[1]!='\0') {
 173                         espsecret_key[i]=hex2byte(colon);
 174                         colon+=2;
 175                         i++;
 176                 }
 177         } else {
 178                 espsecret_key = colon;
 179         }
 180 }
 181
 182 int
 183 esp_print(register const u_char *bp, register const u_char *bp2,
 184           int *nhdr, int *padlen)
 185 {
 186         register const struct esp *esp;
 187         register const u_char *ep;
 188         u_int32_t spi;
 189         struct ip *ip = NULL;
 190 #ifdef INET6
 191         struct ip6_hdr *ip6 = NULL;
 192 #endif
 193         int advance;
 194         int len;
 195         char *secret;
 196         int ivlen = 0;
 197         u_char *ivoff;
 198         u_char *p;
 199
 200         esp = (struct esp *)bp;
 201         spi = (u_int32_t)ntohl(esp->esp_spi);
 202         secret = NULL;
 203
 204 #if 0
 205         /* keep secret out of a register */
 206         p = (u_char *)&secret;
 207 #endif
 208
 209         /* 'ep' points to the end of available data. */
 210         ep = snapend;
 211
 212         if ((u_char *)(esp + 1) >= ep - sizeof(struct esp)) {
 213                 fputs("[|ESP]", stdout);
 214                 goto fail;
 215         }
 216         printf("ESP(spi=0x%08x", spi);
 217         printf(",seq=0x%x", (u_int32_t)ntohl(*(u_int32_t *)(esp + 1)));
 218         printf(")");
 219
 220         /* if we don't have decryption key, we can't decrypt this packet. */
 221         if (!espsecret)
 222                 goto fail;
 223
 224         if(!espsecret_xform) {
 225                 esp_print_decodesecret();
 226         }
 227         if(espsecret_xform->algo == NONE) {
 228                 goto fail;
 229         }
 230
 231         ip = (struct ip *)bp2;
 232         switch (IP_V(ip)) {
 233 #ifdef INET6
 234         case 6:
 235                 ip6 = (struct ip6_hdr *)bp2;
 236                 ip = NULL;
 237                 /* we do not attempt to decrypt jumbograms */
 238                 if (!ntohs(ip6->ip6_plen))
 239                         goto fail;
 240                 /* if we can't get nexthdr, we do not need to decrypt it */
 241                 len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
 242                 break;
 243 #endif /*INET6*/
 244         case 4:
 245                 /* nexthdr & padding are in the last fragment */
 246                 if (ntohs(ip->ip_off) & IP_MF)
 247                         goto fail;
 248 #ifdef INET6
 249                 ip6 = NULL;
 250 #endif
 251                 len = ntohs(ip->ip_len);
 252                 break;
 253         default:
 254                 goto fail;
 255         }
 256
 257         /* if we can't get nexthdr, we do not need to decrypt it */
 258         if (ep - bp2 < len)
 259                 goto fail;
 260
 261         ivoff = (u_char *)(esp + 1) + espsecret_xform->replaysize;
 262         ivlen = espsecret_xform->ivlen;
 263         secret = espsecret_key;
 264
 265         switch (espsecret_xform->algo) {
 266         case DESCBC:
 267 #ifdef HAVE_LIBCRYPTO
 268             {
 269                 u_char iv[8];
 270                 des_key_schedule schedule;
 271
 272                 switch (ivlen) {
 273                 case 4:
 274                         memcpy(iv, ivoff, 4);
 275                         memcpy(&iv[4], ivoff, 4);
 276                         p = &iv[4];
 277                         *p++ ^= 0xff;
 278                         *p++ ^= 0xff;
 279                         *p++ ^= 0xff;
 280                         *p++ ^= 0xff;
 281                         break;
 282                 case 8:
 283                         memcpy(iv, ivoff, 8);
 284                         break;
 285                 default:
 286                         goto fail;
 287                 }
 288
 289                 des_check_key = 0;
 290                 des_set_key((void *)secret, schedule);
 291
 292                 p = ivoff + ivlen;
 293                 des_cbc_encrypt((void *)p, (void *)p,
 294                         (long)(ep - p), schedule, (void *)iv,
 295                         DES_DECRYPT);
 296                 advance = ivoff - (u_char *)esp + ivlen;
 297                 break;
 298             }
 299 #else
 300                 goto fail;
 301 #endif /*HAVE_LIBCRYPTO*/
 302
 303         case BLOWFISH:
 304 #ifdef HAVE_LIBCRYPTO
 305             {
 306                 BF_KEY schedule;
 307
 308                 BF_set_key(&schedule, strlen(secret), secret);
 309
 310                 p = ivoff + ivlen;
 311                 BF_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 312                         BF_DECRYPT);
 313                 advance = ivoff - (u_char *)esp + ivlen;
 314                 break;
 315             }
 316 #else
 317                 goto fail;
 318 #endif /*HAVE_LIBCRYPTO*/
 319
 320         case RC5:
 321 #if defined(HAVE_LIBCRYPTO) && defined(HAVE_RC5_H)
 322             {
 323                 RC5_32_KEY schedule;
 324
 325                 RC5_32_set_key(&schedule, strlen(secret), secret,
 326                         RC5_16_ROUNDS);
 327
 328                 p = ivoff + ivlen;
 329                 RC5_32_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 330                         RC5_DECRYPT);
 331                 advance = ivoff - (u_char *)esp + ivlen;
 332                 break;
 333             }
 334 #else
 335                 goto fail;
 336 #endif /*HAVE_LIBCRYPTO*/
 337
 338         case CAST128:
 339 #if defined(HAVE_LIBCRYPTO) && defined(HAVE_CAST_H) && !defined(HAVE_BUGGY_CAST128)
 340             {
 341                 CAST_KEY schedule;
 342
 343                 CAST_set_key(&schedule, strlen(secret), secret);
 344
 345                 p = ivoff + ivlen;
 346                 CAST_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 347                         CAST_DECRYPT);
 348                 advance = ivoff - (u_char *)esp + ivlen;
 349                 break;
 350             }
 351 #else
 352                 goto fail;
 353 #endif /*HAVE_LIBCRYPTO*/
 354
 355         case DES3CBC:
 356 #if defined(HAVE_LIBCRYPTO)
 357             {
 358                 des_key_schedule s1, s2, s3;
 359
 360                 des_check_key = 1;
 361                 des_set_odd_parity((void *)secret);
 362                 des_set_odd_parity((void *)secret+8);
 363                 des_set_odd_parity((void *)secret+16);
 364                 if(des_set_key((void *)secret, s1) != 0) {
 365                   printf("failed to schedule key 1\n");
 366                 }
 367                 if(des_set_key((void *)(secret + 8), s2)!=0) {
 368                   printf("failed to schedule key 2\n");
 369                 }
 370                 if(des_set_key((void *)(secret + 16), s3)!=0) {
 371                   printf("failed to schedule key 3\n");
 372                 }
 373
 374                 p = ivoff + ivlen;
 375                 des_ede3_cbc_encrypt((void *)p, (void *)p,
 376                                      (long)(ep - p),
 377                                      s1, s2, s3,
 378                                      (void *)ivoff, DES_DECRYPT);
 379                 advance = ivoff - (u_char *)esp + ivlen;
 380                 break;
 381             }
 382 #else
 383                 goto fail;
 384 #endif /*HAVE_LIBCRYPTO*/
 385
 386         case NONE:
 387         default:
 388                 advance = sizeof(struct esp) + espsecret_xform->replaysize;
 389                 break;
 390         }
 391
 392         ep = ep - espsecret_xform->authlen;
 393         /* sanity check for pad length */
 394         if (ep - bp < *(ep - 2))
 395                 goto fail;
 396
 397         if (padlen)
 398                 *padlen = *(ep - 2) + 2;
 399
 400         if (nhdr)
 401                 *nhdr = *(ep - 1);
 402
 403         printf(": ");
 404         return advance;
 405
 406 fail:
 407         if (nhdr)
 408                 *nhdr = -1;
 409         return 65536;
 410 }