ns_verify.c revision 1.2.10.4
1 /* $NetBSD: ns_verify.c,v 1.2.10.4 2013/07/30 08:17:48 msaitoh Exp $ */ 2 3 /* 4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 5 * Copyright (c) 1999 by Internet Software Consortium, Inc. 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 #ifndef lint 21 static const char rcsid[] = "Id: ns_verify.c,v 1.5 2006/03/09 23:57:56 marka Exp "; 22 #endif 23 24 /* Import. */ 25 26 #include "port_before.h" 27 #include "fd_setsize.h" 28 29 #include <sys/types.h> 30 #include <sys/param.h> 31 32 #include <netinet/in.h> 33 #include <arpa/nameser.h> 34 #include <arpa/inet.h> 35 36 #include <errno.h> 37 #include <netdb.h> 38 #include <resolv.h> 39 #include <stdio.h> 40 #include <stdlib.h> 41 #include <string.h> 42 #include <time.h> 43 #include <unistd.h> 44 45 #include <isc/dst.h> 46 47 #include "port_after.h" 48 49 /* Private. */ 50 51 #define BOUNDS_CHECK(ptr, count) \ 52 do { \ 53 if ((ptr) + (count) > eom) { \ 54 return (NS_TSIG_ERROR_FORMERR); \ 55 } \ 56 } while (/*CONSTCOND*/0) 57 58 /* Public. */ 59 60 u_char * 61 ns_find_tsig(u_char *msg, u_char *eom) { 62 HEADER *hp = (void *)msg; 63 int n, type; 64 u_char *cp = msg, *start; 65 66 if (msg == NULL || eom == NULL || msg > eom) 67 return (NULL); 68 69 if (cp + HFIXEDSZ >= eom) 70 return (NULL); 71 72 if (hp->arcount == 0) 73 return (NULL); 74 75 cp += HFIXEDSZ; 76 77 n = ns_skiprr(cp, eom, ns_s_qd, ntohs(hp->qdcount)); 78 if (n < 0) 79 return (NULL); 80 cp += n; 81 82 n = ns_skiprr(cp, eom, ns_s_an, ntohs(hp->ancount)); 83 if (n < 0) 84 return (NULL); 85 cp += n; 86 87 n = ns_skiprr(cp, eom, ns_s_ns, ntohs(hp->nscount)); 88 if (n < 0) 89 return (NULL); 90 cp += n; 91 92 n = ns_skiprr(cp, eom, ns_s_ar, ntohs(hp->arcount) - 1); 93 if (n < 0) 94 return (NULL); 95 cp += n; 96 97 start = cp; 98 n = dn_skipname(cp, eom); 99 if (n < 0) 100 return (NULL); 101 cp += n; 102 if (cp + INT16SZ >= eom) 103 return (NULL); 104 105 GETSHORT(type, cp); 106 if (type != ns_t_tsig) 107 return (NULL); 108 return (start); 109 } 110 111 /* ns_verify 112 * 113 * Parameters: 114 *\li statp res stuff 115 *\li msg received message 116 *\li msglen length of message 117 *\li key tsig key used for verifying. 118 *\li querysig (response), the signature in the query 119 *\li querysiglen (response), the length of the signature in the query 120 *\li sig (query), a buffer to hold the signature 121 *\li siglen (query), input - length of signature buffer 122 * output - length of signature 123 * 124 * Errors: 125 *\li - bad input (-1) 126 *\li - invalid dns message (NS_TSIG_ERROR_FORMERR) 127 *\li - TSIG is not present (NS_TSIG_ERROR_NO_TSIG) 128 *\li - key doesn't match (-ns_r_badkey) 129 *\li - TSIG verification fails with BADKEY (-ns_r_badkey) 130 *\li - TSIG verification fails with BADSIG (-ns_r_badsig) 131 *\li - TSIG verification fails with BADTIME (-ns_r_badtime) 132 *\li - TSIG verification succeeds, error set to BAKEY (ns_r_badkey) 133 *\li - TSIG verification succeeds, error set to BADSIG (ns_r_badsig) 134 *\li - TSIG verification succeeds, error set to BADTIME (ns_r_badtime) 135 */ 136 int 137 ns_verify(u_char *msg, int *msglen, void *k, 138 const u_char *querysig, int querysiglen, u_char *sig, int *siglen, 139 time_t *timesigned, int nostrip) 140 { 141 HEADER *hp = (void *)msg; 142 DST_KEY *key = (DST_KEY *)k; 143 u_char *cp = msg, *eom; 144 char name[MAXDNAME], alg[MAXDNAME]; 145 u_char *recstart, *rdatastart; 146 u_char *sigstart, *otherstart; 147 int n; 148 int error; 149 u_int16_t type, length; 150 u_int16_t fudge, sigfieldlen, otherfieldlen; 151 152 dst_init(); 153 if (msg == NULL || msglen == NULL || *msglen < 0) 154 return (-1); 155 156 eom = msg + *msglen; 157 158 recstart = ns_find_tsig(msg, eom); 159 if (recstart == NULL) 160 return (NS_TSIG_ERROR_NO_TSIG); 161 162 cp = recstart; 163 164 /* Read the key name. */ 165 n = dn_expand(msg, eom, cp, name, MAXDNAME); 166 if (n < 0) 167 return (NS_TSIG_ERROR_FORMERR); 168 cp += n; 169 170 /* Read the type. */ 171 BOUNDS_CHECK(cp, 2*INT16SZ + INT32SZ + INT16SZ); 172 GETSHORT(type, cp); 173 if (type != ns_t_tsig) 174 return (NS_TSIG_ERROR_NO_TSIG); 175 176 /* Skip the class and TTL, save the length. */ 177 cp += INT16SZ + INT32SZ; 178 GETSHORT(length, cp); 179 if (eom - cp != length) 180 return (NS_TSIG_ERROR_FORMERR); 181 182 /* Read the algorithm name. */ 183 rdatastart = cp; 184 n = dn_expand(msg, eom, cp, alg, MAXDNAME); 185 if (n < 0) 186 return (NS_TSIG_ERROR_FORMERR); 187 if (ns_samename(alg, NS_TSIG_ALG_HMAC_MD5) != 1) 188 return (-ns_r_badkey); 189 cp += n; 190 191 /* Read the time signed and fudge. */ 192 BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ); 193 cp += INT16SZ; 194 GETLONG((*timesigned), cp); 195 GETSHORT(fudge, cp); 196 197 /* Read the signature. */ 198 BOUNDS_CHECK(cp, INT16SZ); 199 GETSHORT(sigfieldlen, cp); 200 BOUNDS_CHECK(cp, sigfieldlen); 201 sigstart = cp; 202 cp += sigfieldlen; 203 204 /* Skip id and read error. */ 205 BOUNDS_CHECK(cp, 2*INT16SZ); 206 cp += INT16SZ; 207 GETSHORT(error, cp); 208 209 /* Parse the other data. */ 210 BOUNDS_CHECK(cp, INT16SZ); 211 GETSHORT(otherfieldlen, cp); 212 BOUNDS_CHECK(cp, otherfieldlen); 213 otherstart = cp; 214 cp += otherfieldlen; 215 216 if (cp != eom) 217 return (NS_TSIG_ERROR_FORMERR); 218 219 /* Verify that the key used is OK. */ 220 if (key != NULL) { 221 if (key->dk_alg != KEY_HMAC_MD5) 222 return (-ns_r_badkey); 223 if (error != ns_r_badsig && error != ns_r_badkey) { 224 if (ns_samename(key->dk_key_name, name) != 1) 225 return (-ns_r_badkey); 226 } 227 } 228 229 hp->arcount = htons(ntohs(hp->arcount) - 1); 230 231 /* 232 * Do the verification. 233 */ 234 235 if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) { 236 void *ctx; 237 u_char buf[MAXDNAME]; 238 u_char buf2[MAXDNAME]; 239 240 /* Digest the query signature, if this is a response. */ 241 dst_verify_data(SIG_MODE_INIT, key, &ctx, NULL, 0, NULL, 0); 242 if (querysiglen > 0 && querysig != NULL) { 243 u_int16_t len_n = htons(querysiglen); 244 dst_verify_data(SIG_MODE_UPDATE, key, &ctx, 245 (void *)&len_n, INT16SZ, NULL, 0); 246 dst_verify_data(SIG_MODE_UPDATE, key, &ctx, 247 querysig, querysiglen, NULL, 0); 248 } 249 250 /* Digest the message. */ 251 dst_verify_data(SIG_MODE_UPDATE, key, &ctx, msg, 252 (int)(recstart - msg), NULL, 0); 253 254 /* Digest the key name. */ 255 n = ns_name_pton(name, buf2, sizeof(buf2)); 256 if (n < 0) 257 return (-1); 258 n = ns_name_ntol(buf2, buf, sizeof(buf)); 259 if (n < 0) 260 return (-1); 261 dst_verify_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0); 262 263 /* Digest the class and TTL. */ 264 dst_verify_data(SIG_MODE_UPDATE, key, &ctx, 265 recstart + dn_skipname(recstart, eom) + INT16SZ, 266 INT16SZ + INT32SZ, NULL, 0); 267 268 /* Digest the algorithm. */ 269 n = ns_name_pton(alg, buf2, sizeof(buf2)); 270 if (n < 0) 271 return (-1); 272 n = ns_name_ntol(buf2, buf, sizeof(buf)); 273 if (n < 0) 274 return (-1); 275 dst_verify_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0); 276 277 /* Digest the time signed and fudge. */ 278 dst_verify_data(SIG_MODE_UPDATE, key, &ctx, 279 rdatastart + dn_skipname(rdatastart, eom), 280 INT16SZ + INT32SZ + INT16SZ, NULL, 0); 281 282 /* Digest the error and other data. */ 283 dst_verify_data(SIG_MODE_UPDATE, key, &ctx, 284 otherstart - INT16SZ - INT16SZ, 285 otherfieldlen + INT16SZ + INT16SZ, NULL, 0); 286 287 n = dst_verify_data(SIG_MODE_FINAL, key, &ctx, NULL, 0, 288 sigstart, sigfieldlen); 289 290 if (n < 0) 291 return (-ns_r_badsig); 292 293 if (sig != NULL && siglen != NULL) { 294 if (*siglen < sigfieldlen) 295 return (NS_TSIG_ERROR_NO_SPACE); 296 memcpy(sig, sigstart, sigfieldlen); 297 *siglen = sigfieldlen; 298 } 299 } else { 300 if (sigfieldlen > 0) 301 return (NS_TSIG_ERROR_FORMERR); 302 if (sig != NULL && siglen != NULL) 303 *siglen = 0; 304 } 305 306 /* Reset the counter, since we still need to check for badtime. */ 307 hp->arcount = htons(ntohs(hp->arcount) + 1); 308 309 /* Verify the time. */ 310 if (abs((int)((*timesigned) - time(NULL))) > fudge) 311 return (-ns_r_badtime); 312 313 if (nostrip == 0) { 314 *msglen = (int)(recstart - msg); 315 hp->arcount = htons(ntohs(hp->arcount) - 1); 316 } 317 318 if (error != NOERROR) 319 return (error); 320 321 return (0); 322 } 323 324 int 325 ns_verify_tcp_init(void *k, const u_char *querysig, int querysiglen, 326 ns_tcp_tsig_state *state) 327 { 328 dst_init(); 329 if (state == NULL || k == NULL || querysig == NULL || querysiglen < 0) 330 return (-1); 331 state->counter = -1; 332 state->key = k; 333 if (state->key->dk_alg != KEY_HMAC_MD5) 334 return (-ns_r_badkey); 335 if (querysiglen > (int)sizeof(state->sig)) 336 return (-1); 337 memcpy(state->sig, querysig, querysiglen); 338 state->siglen = querysiglen; 339 return (0); 340 } 341 342 int 343 ns_verify_tcp(u_char *msg, int *msglen, ns_tcp_tsig_state *state, 344 int required) 345 { 346 HEADER *hp = (void *)msg; 347 u_char *recstart, *sigstart; 348 unsigned int sigfieldlen, otherfieldlen; 349 u_char *cp, *eom, *cp2; 350 char name[MAXDNAME], alg[MAXDNAME]; 351 u_char buf[MAXDNAME]; 352 int n, type, length, fudge, error; 353 time_t timesigned; 354 355 if (msg == NULL || msglen == NULL || state == NULL) 356 return (-1); 357 358 eom = msg + *msglen; 359 360 state->counter++; 361 if (state->counter == 0) 362 return (ns_verify(msg, msglen, state->key, 363 state->sig, state->siglen, 364 state->sig, &state->siglen, ×igned, 0)); 365 366 if (state->siglen > 0) { 367 u_int16_t siglen_n = htons(state->siglen); 368 369 dst_verify_data(SIG_MODE_INIT, state->key, &state->ctx, 370 NULL, 0, NULL, 0); 371 dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx, 372 (void *)&siglen_n, INT16SZ, NULL, 0); 373 dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx, 374 state->sig, state->siglen, NULL, 0); 375 state->siglen = 0; 376 } 377 378 cp = recstart = ns_find_tsig(msg, eom); 379 380 if (recstart == NULL) { 381 if (required) 382 return (NS_TSIG_ERROR_NO_TSIG); 383 dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx, 384 msg, *msglen, NULL, 0); 385 return (0); 386 } 387 388 hp->arcount = htons(ntohs(hp->arcount) - 1); 389 dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx, 390 msg, (int)(recstart - msg), NULL, 0); 391 392 /* Read the key name. */ 393 n = dn_expand(msg, eom, cp, name, MAXDNAME); 394 if (n < 0) 395 return (NS_TSIG_ERROR_FORMERR); 396 cp += n; 397 398 /* Read the type. */ 399 BOUNDS_CHECK(cp, 2*INT16SZ + INT32SZ + INT16SZ); 400 GETSHORT(type, cp); 401 if (type != ns_t_tsig) 402 return (NS_TSIG_ERROR_NO_TSIG); 403 404 /* Skip the class and TTL, save the length. */ 405 cp += INT16SZ + INT32SZ; 406 GETSHORT(length, cp); 407 if (eom - cp != length) 408 return (NS_TSIG_ERROR_FORMERR); 409 410 /* Read the algorithm name. */ 411 n = dn_expand(msg, eom, cp, alg, MAXDNAME); 412 if (n < 0) 413 return (NS_TSIG_ERROR_FORMERR); 414 if (ns_samename(alg, NS_TSIG_ALG_HMAC_MD5) != 1) 415 return (-ns_r_badkey); 416 cp += n; 417 418 /* Verify that the key used is OK. */ 419 if ((ns_samename(state->key->dk_key_name, name) != 1 || 420 state->key->dk_alg != KEY_HMAC_MD5)) 421 return (-ns_r_badkey); 422 423 /* Read the time signed and fudge. */ 424 BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ); 425 cp += INT16SZ; 426 GETLONG(timesigned, cp); 427 GETSHORT(fudge, cp); 428 429 /* Read the signature. */ 430 BOUNDS_CHECK(cp, INT16SZ); 431 GETSHORT(sigfieldlen, cp); 432 BOUNDS_CHECK(cp, sigfieldlen); 433 sigstart = cp; 434 cp += sigfieldlen; 435 436 /* Skip id and read error. */ 437 BOUNDS_CHECK(cp, 2*INT16SZ); 438 cp += INT16SZ; 439 GETSHORT(error, cp); 440 441 /* Parse the other data. */ 442 BOUNDS_CHECK(cp, INT16SZ); 443 GETSHORT(otherfieldlen, cp); 444 BOUNDS_CHECK(cp, otherfieldlen); 445 cp += otherfieldlen; 446 447 if (cp != eom) 448 return (NS_TSIG_ERROR_FORMERR); 449 450 /* 451 * Do the verification. 452 */ 453 454 /* Digest the time signed and fudge. */ 455 cp2 = buf; 456 PUTSHORT(0, cp2); /*%< Top 16 bits of time. */ 457 PUTLONG(timesigned, cp2); 458 PUTSHORT(NS_TSIG_FUDGE, cp2); 459 460 dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx, 461 buf, (int)(cp2 - buf), NULL, 0); 462 463 n = dst_verify_data(SIG_MODE_FINAL, state->key, &state->ctx, NULL, 0, 464 sigstart, (int)sigfieldlen); 465 if (n < 0) 466 return (-ns_r_badsig); 467 468 if (sigfieldlen > sizeof(state->sig)) 469 return (NS_TSIG_ERROR_NO_SPACE); 470 471 memcpy(state->sig, sigstart, sigfieldlen); 472 state->siglen = sigfieldlen; 473 474 /* Verify the time. */ 475 if (abs((int)(timesigned - time(NULL))) > fudge) 476 return (-ns_r_badtime); 477 478 *msglen = (int)(recstart - msg); 479 480 if (error != NOERROR) 481 return (error); 482 483 return (0); 484 } 485 486 /*! \file */ 487
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