1 /* $OpenBSD: ocsp_vfy.c,v 1.15 2017/01/29 17:49:23 beck 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 OCSPerror(OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND); 90 goto end; 91 } 92 if ((ret == 2) && (flags & OCSP_TRUSTOTHER)) 93 flags |= OCSP_NOVERIFY; 94 if (!(flags & OCSP_NOSIGS)) { 95 EVP_PKEY *skey; 96 97 skey = X509_get_pubkey(signer); 98 if (skey) { 99 ret = OCSP_BASICRESP_verify(bs, skey, 0); 100 EVP_PKEY_free(skey); 101 } 102 if (!skey || ret <= 0) { 103 OCSPerror(OCSP_R_SIGNATURE_FAILURE); 104 goto end; 105 } 106 } 107 if (!(flags & OCSP_NOVERIFY)) { 108 int init_res; 109 110 if (flags & OCSP_NOCHAIN) { 111 untrusted = NULL; 112 } else if (bs->certs && certs) { 113 untrusted = sk_X509_dup(bs->certs); 114 for (i = 0; i < sk_X509_num(certs); i++) { 115 if (!sk_X509_push(untrusted, 116 sk_X509_value(certs, i))) { 117 OCSPerror(ERR_R_MALLOC_FAILURE); 118 goto end; 119 } 120 } 121 } else 122 untrusted = bs->certs; 123 init_res = X509_STORE_CTX_init(&ctx, st, signer, untrusted); 124 if (!init_res) { 125 ret = -1; 126 OCSPerror(ERR_R_X509_LIB); 127 goto end; 128 } 129 130 if (X509_STORE_CTX_set_purpose(&ctx, 131 X509_PURPOSE_OCSP_HELPER) == 0) { 132 X509_STORE_CTX_cleanup(&ctx); 133 ret = -1; 134 goto end; 135 } 136 ret = X509_verify_cert(&ctx); 137 chain = X509_STORE_CTX_get1_chain(&ctx); 138 X509_STORE_CTX_cleanup(&ctx); 139 if (ret <= 0) { 140 i = X509_STORE_CTX_get_error(&ctx); 141 OCSPerror(OCSP_R_CERTIFICATE_VERIFY_ERROR); 142 ERR_asprintf_error_data("Verify error:%s", 143 X509_verify_cert_error_string(i)); 144 goto end; 145 } 146 if (flags & OCSP_NOCHECKS) { 147 ret = 1; 148 goto end; 149 } 150 /* At this point we have a valid certificate chain 151 * need to verify it against the OCSP issuer criteria. 152 */ 153 ret = ocsp_check_issuer(bs, chain, flags); 154 155 /* If fatal error or valid match then finish */ 156 if (ret != 0) 157 goto end; 158 159 /* Easy case: explicitly trusted. Get root CA and 160 * check for explicit trust 161 */ 162 if (flags & OCSP_NOEXPLICIT) 163 goto end; 164 165 x = sk_X509_value(chain, sk_X509_num(chain) - 1); 166 if (X509_check_trust(x, NID_OCSP_sign, 0) != 167 X509_TRUST_TRUSTED) { 168 OCSPerror(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 OCSPerror(OCSP_R_NO_CERTIFICATES_IN_CHAIN); 244 return -1; 245 } 246 247 /* See if the issuer IDs match. */ 248 i = ocsp_check_ids(sresp, &caid); 249 250 /* If ID mismatch or other error then return */ 251 if (i <= 0) 252 return i; 253 254 signer = sk_X509_value(chain, 0); 255 /* Check to see if OCSP responder CA matches request CA */ 256 if (sk_X509_num(chain) > 1) { 257 sca = sk_X509_value(chain, 1); 258 i = ocsp_match_issuerid(sca, caid, sresp); 259 if (i < 0) 260 return i; 261 if (i) { 262 /* We have a match, if extensions OK then success */ 263 if (ocsp_check_delegated(signer, flags)) 264 return 1; 265 return 0; 266 } 267 } 268 269 /* Otherwise check if OCSP request signed directly by request CA */ 270 return ocsp_match_issuerid(signer, caid, sresp); 271 } 272 273 /* Check the issuer certificate IDs for equality. If there is a mismatch with the same 274 * algorithm then there's no point trying to match any certificates against the issuer. 275 * If the issuer IDs all match then we just need to check equality against one of them. 276 */ 277 static int 278 ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret) 279 { 280 OCSP_CERTID *tmpid, *cid; 281 int i, idcount; 282 283 idcount = sk_OCSP_SINGLERESP_num(sresp); 284 if (idcount <= 0) { 285 OCSPerror(OCSP_R_RESPONSE_CONTAINS_NO_REVOCATION_DATA); 286 return -1; 287 } 288 289 cid = sk_OCSP_SINGLERESP_value(sresp, 0)->certId; 290 291 *ret = NULL; 292 293 for (i = 1; i < idcount; i++) { 294 tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId; 295 /* Check to see if IDs match */ 296 if (OCSP_id_issuer_cmp(cid, tmpid)) { 297 return 0; 298 } 299 } 300 301 /* All IDs match: only need to check one ID */ 302 *ret = cid; 303 return 1; 304 } 305 306 static int 307 ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid, 308 STACK_OF(OCSP_SINGLERESP) *sresp) 309 { 310 /* If only one ID to match then do it */ 311 if (cid) { 312 const EVP_MD *dgst; 313 X509_NAME *iname; 314 int mdlen; 315 unsigned char md[EVP_MAX_MD_SIZE]; 316 317 if (!(dgst = 318 EVP_get_digestbyobj(cid->hashAlgorithm->algorithm))) { 319 OCSPerror(OCSP_R_UNKNOWN_MESSAGE_DIGEST); 320 return -1; 321 } 322 323 mdlen = EVP_MD_size(dgst); 324 if (mdlen < 0) 325 return -1; 326 if (cid->issuerNameHash->length != mdlen || 327 cid->issuerKeyHash->length != mdlen) 328 return 0; 329 iname = X509_get_subject_name(cert); 330 if (!X509_NAME_digest(iname, dgst, md, NULL)) 331 return -1; 332 if (memcmp(md, cid->issuerNameHash->data, mdlen)) 333 return 0; 334 X509_pubkey_digest(cert, dgst, md, NULL); 335 if (memcmp(md, cid->issuerKeyHash->data, mdlen)) 336 return 0; 337 338 return 1; 339 } else { 340 /* We have to match the whole lot */ 341 int i, ret; 342 OCSP_CERTID *tmpid; 343 344 for (i = 0; i < sk_OCSP_SINGLERESP_num(sresp); i++) { 345 tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId; 346 ret = ocsp_match_issuerid(cert, tmpid, NULL); 347 if (ret <= 0) 348 return ret; 349 } 350 return 1; 351 } 352 } 353 354 static int 355 ocsp_check_delegated(X509 *x, int flags) 356 { 357 X509_check_purpose(x, -1, 0); 358 if ((x->ex_flags & EXFLAG_XKUSAGE) && (x->ex_xkusage & XKU_OCSP_SIGN)) 359 return 1; 360 OCSPerror(OCSP_R_MISSING_OCSPSIGNING_USAGE); 361 return 0; 362 } 363 364 /* Verify an OCSP request. This is fortunately much easier than OCSP 365 * response verify. Just find the signers certificate and verify it 366 * against a given trust value. 367 */ 368 int 369 OCSP_request_verify(OCSP_REQUEST *req, STACK_OF(X509) *certs, X509_STORE *store, 370 unsigned long flags) 371 { 372 X509 *signer; 373 X509_NAME *nm; 374 GENERAL_NAME *gen; 375 int ret; 376 X509_STORE_CTX ctx; 377 378 if (!req->optionalSignature) { 379 OCSPerror(OCSP_R_REQUEST_NOT_SIGNED); 380 return 0; 381 } 382 gen = req->tbsRequest->requestorName; 383 if (!gen || gen->type != GEN_DIRNAME) { 384 OCSPerror(OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE); 385 return 0; 386 } 387 nm = gen->d.directoryName; 388 ret = ocsp_req_find_signer(&signer, req, nm, certs, store, flags); 389 if (ret <= 0) { 390 OCSPerror(OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND); 391 return 0; 392 } 393 if ((ret == 2) && (flags & OCSP_TRUSTOTHER)) 394 flags |= OCSP_NOVERIFY; 395 if (!(flags & OCSP_NOSIGS)) { 396 EVP_PKEY *skey; 397 398 skey = X509_get_pubkey(signer); 399 ret = OCSP_REQUEST_verify(req, skey); 400 EVP_PKEY_free(skey); 401 if (ret <= 0) { 402 OCSPerror(OCSP_R_SIGNATURE_FAILURE); 403 return 0; 404 } 405 } 406 if (!(flags & OCSP_NOVERIFY)) { 407 int init_res; 408 409 if (flags & OCSP_NOCHAIN) 410 init_res = X509_STORE_CTX_init(&ctx, store, signer, 411 NULL); 412 else 413 init_res = X509_STORE_CTX_init(&ctx, store, signer, 414 req->optionalSignature->certs); 415 if (!init_res) { 416 OCSPerror(ERR_R_X509_LIB); 417 return 0; 418 } 419 420 if (X509_STORE_CTX_set_purpose(&ctx, 421 X509_PURPOSE_OCSP_HELPER) == 0 || 422 X509_STORE_CTX_set_trust(&ctx, 423 X509_TRUST_OCSP_REQUEST) == 0) { 424 X509_STORE_CTX_cleanup(&ctx); 425 return 0; 426 } 427 ret = X509_verify_cert(&ctx); 428 X509_STORE_CTX_cleanup(&ctx); 429 if (ret <= 0) { 430 ret = X509_STORE_CTX_get_error(&ctx); 431 OCSPerror(OCSP_R_CERTIFICATE_VERIFY_ERROR); 432 ERR_asprintf_error_data("Verify error:%s", 433 X509_verify_cert_error_string(ret)); 434 return 0; 435 } 436 } 437 return 1; 438 } 439 440 static int 441 ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req, X509_NAME *nm, 442 STACK_OF(X509) *certs, X509_STORE *st, unsigned long flags) 443 { 444 X509 *signer; 445 446 if (!(flags & OCSP_NOINTERN)) { 447 signer = X509_find_by_subject(req->optionalSignature->certs, nm); 448 if (signer) { 449 *psigner = signer; 450 return 1; 451 } 452 } 453 454 signer = X509_find_by_subject(certs, nm); 455 if (signer) { 456 *psigner = signer; 457 return 2; 458 } 459 return 0; 460 } 461