1 /* $OpenBSD: ocsp_vfy.c,v 1.12 2014/07/09 19:08:10 tedu Exp $ */ 2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL 3 * project 2000. 4 */ 5 /* ==================================================================== 6 * Copyright (c) 2000-2004 The OpenSSL Project. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 20 * 3. All advertising materials mentioning features or use of this 21 * software must display the following acknowledgment: 22 * "This product includes software developed by the OpenSSL Project 23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 24 * 25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26 * endorse or promote products derived from this software without 27 * prior written permission. For written permission, please contact 28 * licensing@OpenSSL.org. 29 * 30 * 5. Products derived from this software may not be called "OpenSSL" 31 * nor may "OpenSSL" appear in their names without prior written 32 * permission of the OpenSSL Project. 33 * 34 * 6. Redistributions of any form whatsoever must retain the following 35 * acknowledgment: 36 * "This product includes software developed by the OpenSSL Project 37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" 38 * 39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50 * OF THE POSSIBILITY OF SUCH DAMAGE. 51 * ==================================================================== 52 * 53 * This product includes cryptographic software written by Eric Young 54 * (eay@cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh@cryptsoft.com). 56 * 57 */ 58 59 #include <openssl/ocsp.h> 60 #include <openssl/err.h> 61 #include <string.h> 62 63 static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs, 64 STACK_OF(X509) *certs, X509_STORE *st, unsigned long flags); 65 static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id); 66 static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain, 67 unsigned long flags); 68 static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret); 69 static int ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid, 70 STACK_OF(OCSP_SINGLERESP) *sresp); 71 static int ocsp_check_delegated(X509 *x, int flags); 72 static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req, 73 X509_NAME *nm, STACK_OF(X509) *certs, X509_STORE *st, 74 unsigned long flags); 75 76 /* Verify a basic response message */ 77 int 78 OCSP_basic_verify(OCSP_BASICRESP *bs, STACK_OF(X509) *certs, X509_STORE *st, 79 unsigned long flags) 80 { 81 X509 *signer, *x; 82 STACK_OF(X509) *chain = NULL; 83 STACK_OF(X509) *untrusted = NULL; 84 X509_STORE_CTX ctx; 85 int i, ret = 0; 86 87 ret = ocsp_find_signer(&signer, bs, certs, st, flags); 88 if (!ret) { 89 OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, 90 OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND); 91 goto end; 92 } 93 if ((ret == 2) && (flags & OCSP_TRUSTOTHER)) 94 flags |= OCSP_NOVERIFY; 95 if (!(flags & OCSP_NOSIGS)) { 96 EVP_PKEY *skey; 97 98 skey = X509_get_pubkey(signer); 99 if (skey) { 100 ret = OCSP_BASICRESP_verify(bs, skey, 0); 101 EVP_PKEY_free(skey); 102 } 103 if (!skey || ret <= 0) { 104 OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, 105 OCSP_R_SIGNATURE_FAILURE); 106 goto end; 107 } 108 } 109 if (!(flags & OCSP_NOVERIFY)) { 110 int init_res; 111 112 if (flags & OCSP_NOCHAIN) { 113 untrusted = NULL; 114 } else if (bs->certs && certs) { 115 untrusted = sk_X509_dup(bs->certs); 116 for (i = 0; i < sk_X509_num(certs); i++) { 117 if (!sk_X509_push(untrusted, 118 sk_X509_value(certs, i))) { 119 OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, 120 ERR_R_MALLOC_FAILURE); 121 goto end; 122 } 123 } 124 } else 125 untrusted = bs->certs; 126 init_res = X509_STORE_CTX_init(&ctx, st, signer, untrusted); 127 if (!init_res) { 128 ret = -1; 129 OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_X509_LIB); 130 goto end; 131 } 132 133 X509_STORE_CTX_set_purpose(&ctx, X509_PURPOSE_OCSP_HELPER); 134 ret = X509_verify_cert(&ctx); 135 chain = X509_STORE_CTX_get1_chain(&ctx); 136 X509_STORE_CTX_cleanup(&ctx); 137 if (ret <= 0) { 138 i = X509_STORE_CTX_get_error(&ctx); 139 OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, 140 OCSP_R_CERTIFICATE_VERIFY_ERROR); 141 ERR_asprintf_error_data("Verify error:%s", 142 X509_verify_cert_error_string(i)); 143 goto end; 144 } 145 if (flags & OCSP_NOCHECKS) { 146 ret = 1; 147 goto end; 148 } 149 /* At this point we have a valid certificate chain 150 * need to verify it against the OCSP issuer criteria. 151 */ 152 ret = ocsp_check_issuer(bs, chain, flags); 153 154 /* If fatal error or valid match then finish */ 155 if (ret != 0) 156 goto end; 157 158 /* Easy case: explicitly trusted. Get root CA and 159 * check for explicit trust 160 */ 161 if (flags & OCSP_NOEXPLICIT) 162 goto end; 163 164 x = sk_X509_value(chain, sk_X509_num(chain) - 1); 165 if (X509_check_trust(x, NID_OCSP_sign, 0) != 166 X509_TRUST_TRUSTED) { 167 OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, 168 OCSP_R_ROOT_CA_NOT_TRUSTED); 169 goto end; 170 } 171 ret = 1; 172 } 173 174 end: 175 if (chain) 176 sk_X509_pop_free(chain, X509_free); 177 if (bs->certs && certs) 178 sk_X509_free(untrusted); 179 return ret; 180 } 181 182 static int 183 ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs, STACK_OF(X509) *certs, 184 X509_STORE *st, unsigned long flags) 185 { 186 X509 *signer; 187 OCSP_RESPID *rid = bs->tbsResponseData->responderId; 188 189 if ((signer = ocsp_find_signer_sk(certs, rid))) { 190 *psigner = signer; 191 return 2; 192 } 193 if (!(flags & OCSP_NOINTERN) && 194 (signer = ocsp_find_signer_sk(bs->certs, rid))) { 195 *psigner = signer; 196 return 1; 197 } 198 /* Maybe lookup from store if by subject name */ 199 200 *psigner = NULL; 201 return 0; 202 } 203 204 static X509 * 205 ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id) 206 { 207 int i; 208 unsigned char tmphash[SHA_DIGEST_LENGTH], *keyhash; 209 X509 *x; 210 211 /* Easy if lookup by name */ 212 if (id->type == V_OCSP_RESPID_NAME) 213 return X509_find_by_subject(certs, id->value.byName); 214 215 /* Lookup by key hash */ 216 217 /* If key hash isn't SHA1 length then forget it */ 218 if (id->value.byKey->length != SHA_DIGEST_LENGTH) 219 return NULL; 220 keyhash = id->value.byKey->data; 221 /* Calculate hash of each key and compare */ 222 for (i = 0; i < sk_X509_num(certs); i++) { 223 x = sk_X509_value(certs, i); 224 X509_pubkey_digest(x, EVP_sha1(), tmphash, NULL); 225 if (!memcmp(keyhash, tmphash, SHA_DIGEST_LENGTH)) 226 return x; 227 } 228 return NULL; 229 } 230 231 static int 232 ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain, 233 unsigned long flags) 234 { 235 STACK_OF(OCSP_SINGLERESP) *sresp; 236 X509 *signer, *sca; 237 OCSP_CERTID *caid = NULL; 238 int i; 239 240 sresp = bs->tbsResponseData->responses; 241 242 if (sk_X509_num(chain) <= 0) { 243 OCSPerr(OCSP_F_OCSP_CHECK_ISSUER, 244 OCSP_R_NO_CERTIFICATES_IN_CHAIN); 245 return -1; 246 } 247 248 /* See if the issuer IDs match. */ 249 i = ocsp_check_ids(sresp, &caid); 250 251 /* If ID mismatch or other error then return */ 252 if (i <= 0) 253 return i; 254 255 signer = sk_X509_value(chain, 0); 256 /* Check to see if OCSP responder CA matches request CA */ 257 if (sk_X509_num(chain) > 1) { 258 sca = sk_X509_value(chain, 1); 259 i = ocsp_match_issuerid(sca, caid, sresp); 260 if (i < 0) 261 return i; 262 if (i) { 263 /* We have a match, if extensions OK then success */ 264 if (ocsp_check_delegated(signer, flags)) 265 return 1; 266 return 0; 267 } 268 } 269 270 /* Otherwise check if OCSP request signed directly by request CA */ 271 return ocsp_match_issuerid(signer, caid, sresp); 272 } 273 274 /* Check the issuer certificate IDs for equality. If there is a mismatch with the same 275 * algorithm then there's no point trying to match any certificates against the issuer. 276 * If the issuer IDs all match then we just need to check equality against one of them. 277 */ 278 static int 279 ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret) 280 { 281 OCSP_CERTID *tmpid, *cid; 282 int i, idcount; 283 284 idcount = sk_OCSP_SINGLERESP_num(sresp); 285 if (idcount <= 0) { 286 OCSPerr(OCSP_F_OCSP_CHECK_IDS, 287 OCSP_R_RESPONSE_CONTAINS_NO_REVOCATION_DATA); 288 return -1; 289 } 290 291 cid = sk_OCSP_SINGLERESP_value(sresp, 0)->certId; 292 293 *ret = NULL; 294 295 for (i = 1; i < idcount; i++) { 296 tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId; 297 /* Check to see if IDs match */ 298 if (OCSP_id_issuer_cmp(cid, tmpid)) { 299 return 0; 300 } 301 } 302 303 /* All IDs match: only need to check one ID */ 304 *ret = cid; 305 return 1; 306 } 307 308 static int 309 ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid, 310 STACK_OF(OCSP_SINGLERESP) *sresp) 311 { 312 /* If only one ID to match then do it */ 313 if (cid) { 314 const EVP_MD *dgst; 315 X509_NAME *iname; 316 int mdlen; 317 unsigned char md[EVP_MAX_MD_SIZE]; 318 319 if (!(dgst = 320 EVP_get_digestbyobj(cid->hashAlgorithm->algorithm))) { 321 OCSPerr(OCSP_F_OCSP_MATCH_ISSUERID, 322 OCSP_R_UNKNOWN_MESSAGE_DIGEST); 323 return -1; 324 } 325 326 mdlen = EVP_MD_size(dgst); 327 if (mdlen < 0) 328 return -1; 329 if (cid->issuerNameHash->length != mdlen || 330 cid->issuerKeyHash->length != mdlen) 331 return 0; 332 iname = X509_get_subject_name(cert); 333 if (!X509_NAME_digest(iname, dgst, md, NULL)) 334 return -1; 335 if (memcmp(md, cid->issuerNameHash->data, mdlen)) 336 return 0; 337 X509_pubkey_digest(cert, dgst, md, NULL); 338 if (memcmp(md, cid->issuerKeyHash->data, mdlen)) 339 return 0; 340 341 return 1; 342 } else { 343 /* We have to match the whole lot */ 344 int i, ret; 345 OCSP_CERTID *tmpid; 346 347 for (i = 0; i < sk_OCSP_SINGLERESP_num(sresp); i++) { 348 tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId; 349 ret = ocsp_match_issuerid(cert, tmpid, NULL); 350 if (ret <= 0) 351 return ret; 352 } 353 return 1; 354 } 355 } 356 357 static int 358 ocsp_check_delegated(X509 *x, int flags) 359 { 360 X509_check_purpose(x, -1, 0); 361 if ((x->ex_flags & EXFLAG_XKUSAGE) && (x->ex_xkusage & XKU_OCSP_SIGN)) 362 return 1; 363 OCSPerr(OCSP_F_OCSP_CHECK_DELEGATED, OCSP_R_MISSING_OCSPSIGNING_USAGE); 364 return 0; 365 } 366 367 /* Verify an OCSP request. This is fortunately much easier than OCSP 368 * response verify. Just find the signers certificate and verify it 369 * against a given trust value. 370 */ 371 int 372 OCSP_request_verify(OCSP_REQUEST *req, STACK_OF(X509) *certs, X509_STORE *store, 373 unsigned long flags) 374 { 375 X509 *signer; 376 X509_NAME *nm; 377 GENERAL_NAME *gen; 378 int ret; 379 X509_STORE_CTX ctx; 380 381 if (!req->optionalSignature) { 382 OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_REQUEST_NOT_SIGNED); 383 return 0; 384 } 385 gen = req->tbsRequest->requestorName; 386 if (!gen || gen->type != GEN_DIRNAME) { 387 OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, 388 OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE); 389 return 0; 390 } 391 nm = gen->d.directoryName; 392 ret = ocsp_req_find_signer(&signer, req, nm, certs, store, flags); 393 if (ret <= 0) { 394 OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, 395 OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND); 396 return 0; 397 } 398 if ((ret == 2) && (flags & OCSP_TRUSTOTHER)) 399 flags |= OCSP_NOVERIFY; 400 if (!(flags & OCSP_NOSIGS)) { 401 EVP_PKEY *skey; 402 403 skey = X509_get_pubkey(signer); 404 ret = OCSP_REQUEST_verify(req, skey); 405 EVP_PKEY_free(skey); 406 if (ret <= 0) { 407 OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, 408 OCSP_R_SIGNATURE_FAILURE); 409 return 0; 410 } 411 } 412 if (!(flags & OCSP_NOVERIFY)) { 413 int init_res; 414 415 if (flags & OCSP_NOCHAIN) 416 init_res = X509_STORE_CTX_init(&ctx, store, signer, 417 NULL); 418 else 419 init_res = X509_STORE_CTX_init(&ctx, store, signer, 420 req->optionalSignature->certs); 421 if (!init_res) { 422 OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, ERR_R_X509_LIB); 423 return 0; 424 } 425 426 X509_STORE_CTX_set_purpose(&ctx, X509_PURPOSE_OCSP_HELPER); 427 X509_STORE_CTX_set_trust(&ctx, X509_TRUST_OCSP_REQUEST); 428 ret = X509_verify_cert(&ctx); 429 X509_STORE_CTX_cleanup(&ctx); 430 if (ret <= 0) { 431 ret = X509_STORE_CTX_get_error(&ctx); 432 OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, 433 OCSP_R_CERTIFICATE_VERIFY_ERROR); 434 ERR_asprintf_error_data("Verify error:%s", 435 X509_verify_cert_error_string(ret)); 436 return 0; 437 } 438 } 439 return 1; 440 } 441 442 static int 443 ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req, X509_NAME *nm, 444 STACK_OF(X509) *certs, X509_STORE *st, unsigned long flags) 445 { 446 X509 *signer; 447 448 if (!(flags & OCSP_NOINTERN)) { 449 signer = X509_find_by_subject(req->optionalSignature->certs, nm); 450 if (signer) { 451 *psigner = signer; 452 return 1; 453 } 454 } 455 456 signer = X509_find_by_subject(certs, nm); 457 if (signer) { 458 *psigner = signer; 459 return 2; 460 } 461 return 0; 462 } 463