crypto/ocsp/ocsp_vfy.c

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