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 1.24 2002-04-07 02:16:03 guy 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_OPENSSL_RC5_H
  46 #include <openssl/rc5.h>
  47 #endif
  48 #ifdef HAVE_OPENSSL_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 #ifdef HAVE_LIBCRYPTO
 199         u_char *p;
 200 #endif
 201
 202         esp = (struct esp *)bp;
 203         spi = (u_int32_t)ntohl(esp->esp_spi);
 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 - sizeof(struct esp)) {
 215                 fputs("[|ESP]", stdout);
 216                 goto fail;
 217         }
 218         printf("ESP(spi=0x%08x", spi);
 219         printf(",seq=0x%x", (u_int32_t)ntohl(*(u_int32_t *)(esp + 1)));
 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->algo == NONE) {
 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                 des_key_schedule schedule;
 273
 274                 switch (ivlen) {
 275                 case 4:
 276                         memcpy(iv, ivoff, 4);
 277                         memcpy(&iv[4], ivoff, 4);
 278                         p = &iv[4];
 279                         *p++ ^= 0xff;
 280                         *p++ ^= 0xff;
 281                         *p++ ^= 0xff;
 282                         *p++ ^= 0xff;
 283                         break;
 284                 case 8:
 285                         memcpy(iv, ivoff, 8);
 286                         break;
 287                 default:
 288                         goto fail;
 289                 }
 290
 291                 des_check_key = 0;
 292                 des_set_key((void *)secret, schedule);
 293
 294                 p = ivoff + ivlen;
 295                 des_cbc_encrypt((void *)p, (void *)p,
 296                         (long)(ep - p), schedule, (void *)iv,
 297                         DES_DECRYPT);
 298                 advance = ivoff - (u_char *)esp + ivlen;
 299                 break;
 300             }
 301 #else
 302                 goto fail;
 303 #endif /*HAVE_LIBCRYPTO*/
 304
 305         case BLOWFISH:
 306 #ifdef HAVE_LIBCRYPTO
 307             {
 308                 BF_KEY schedule;
 309
 310                 BF_set_key(&schedule, strlen(secret), secret);
 311
 312                 p = ivoff + ivlen;
 313                 BF_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 314                         BF_DECRYPT);
 315                 advance = ivoff - (u_char *)esp + ivlen;
 316                 break;
 317             }
 318 #else
 319                 goto fail;
 320 #endif /*HAVE_LIBCRYPTO*/
 321
 322         case RC5:
 323 #if defined(HAVE_LIBCRYPTO) && defined(HAVE_RC5_H)
 324             {
 325                 RC5_32_KEY schedule;
 326
 327                 RC5_32_set_key(&schedule, strlen(secret), secret,
 328                         RC5_16_ROUNDS);
 329
 330                 p = ivoff + ivlen;
 331                 RC5_32_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 332                         RC5_DECRYPT);
 333                 advance = ivoff - (u_char *)esp + ivlen;
 334                 break;
 335             }
 336 #else
 337                 goto fail;
 338 #endif /*HAVE_LIBCRYPTO*/
 339
 340         case CAST128:
 341 #if defined(HAVE_LIBCRYPTO) && defined(HAVE_CAST_H) && !defined(HAVE_BUGGY_CAST128)
 342             {
 343                 CAST_KEY schedule;
 344
 345                 CAST_set_key(&schedule, strlen(secret), secret);
 346
 347                 p = ivoff + ivlen;
 348                 CAST_cbc_encrypt(p, p, (long)(ep - p), &schedule, ivoff,
 349                         CAST_DECRYPT);
 350                 advance = ivoff - (u_char *)esp + ivlen;
 351                 break;
 352             }
 353 #else
 354                 goto fail;
 355 #endif /*HAVE_LIBCRYPTO*/
 356
 357         case DES3CBC:
 358 #if defined(HAVE_LIBCRYPTO)
 359             {
 360                 des_key_schedule s1, s2, s3;
 361
 362                 des_check_key = 1;
 363                 des_set_odd_parity((void *)secret);
 364                 des_set_odd_parity((void *)(secret + 8));
 365                 des_set_odd_parity((void *)(secret + 16));
 366                 if(des_set_key((void *)secret, s1) != 0) {
 367                   printf("failed to schedule key 1\n");
 368                 }
 369                 if(des_set_key((void *)(secret + 8), s2)!=0) {
 370                   printf("failed to schedule key 2\n");
 371                 }
 372                 if(des_set_key((void *)(secret + 16), s3)!=0) {
 373                   printf("failed to schedule key 3\n");
 374                 }
 375
 376                 p = ivoff + ivlen;
 377                 des_ede3_cbc_encrypt((void *)p, (void *)p,
 378                                      (long)(ep - p),
 379                                      s1, s2, s3,
 380                                      (void *)ivoff, DES_DECRYPT);
 381                 advance = ivoff - (u_char *)esp + ivlen;
 382                 break;
 383             }
 384 #else
 385                 goto fail;
 386 #endif /*HAVE_LIBCRYPTO*/
 387
 388         case NONE:
 389         default:
 390                 advance = sizeof(struct esp) + espsecret_xform->replaysize;
 391                 break;
 392         }
 393
 394         ep = ep - espsecret_xform->authlen;
 395         /* sanity check for pad length */
 396         if (ep - bp < *(ep - 2))
 397                 goto fail;
 398
 399         if (padlen)
 400                 *padlen = *(ep - 2) + 2;
 401
 402         if (nhdr)
 403                 *nhdr = *(ep - 1);
 404
 405         printf(": ");
 406         return advance;
 407
 408 fail:
 409         if (nhdr)
 410                 *nhdr = -1;
 411         return 65536;
 412 }