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     STACK_OF(X509) *untrusted = NULL;
  88     X509_STORE_CTX ctx;
  89     int i, ret = 0;
  90     ret = ocsp_find_signer(&signer, bs, certs, st, flags);
  91     if (!ret) {
  92         OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,
  93                 OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
  94         goto end;
  95     }
  96     if ((ret == 2) && (flags & OCSP_TRUSTOTHER))
  97         flags |= OCSP_NOVERIFY;
  98     if (!(flags & OCSP_NOSIGS)) {
  99         EVP_PKEY *skey;
 100         skey = X509_get_pubkey(signer);
 101         if (skey) {
 102             ret = OCSP_BASICRESP_verify(bs, skey, 0);
 103             EVP_PKEY_free(skey);
 104         }
 105         if (!skey || ret <= 0) {
 106             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_SIGNATURE_FAILURE);
 107             goto end;
 108         }
 109     }
 110     if (!(flags & OCSP_NOVERIFY)) {
 111         int init_res;
 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, sk_X509_value(certs, i))) {
 118                     OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_MALLOC_FAILURE);
 119                     goto end;
 120                 }
 121             }
 122         } else {
 123             untrusted = bs->certs;
 124         }
 125         init_res = X509_STORE_CTX_init(&ctx, st, signer, untrusted);
 126         if (!init_res) {
 127             ret = -1;
 128             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_X509_LIB);
 129             goto end;
 130         }
 131
 132         X509_STORE_CTX_set_purpose(&ctx, X509_PURPOSE_OCSP_HELPER);
 133         ret = X509_verify_cert(&ctx);
 134         chain = X509_STORE_CTX_get1_chain(&ctx);
 135         X509_STORE_CTX_cleanup(&ctx);
 136         if (ret <= 0) {
 137             i = X509_STORE_CTX_get_error(&ctx);
 138             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,
 139                     OCSP_R_CERTIFICATE_VERIFY_ERROR);
 140             ERR_add_error_data(2, "Verify error:",
 141                                X509_verify_cert_error_string(i));
 142             goto end;
 143         }
 144         if (flags & OCSP_NOCHECKS) {
 145             ret = 1;
 146             goto end;
 147         }
 148         /*
 149          * At this point we have a valid certificate chain need to verify it
 150          * 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         /*
 159          * Easy case: explicitly trusted. Get root CA and check for explicit
 160          * 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) != X509_TRUST_TRUSTED) {
 167             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_ROOT_CA_NOT_TRUSTED);
 168             goto end;
 169         }
 170         ret = 1;
 171     }
 172
 173  end:
 174     sk_X509_pop_free(chain, X509_free);
 175     if (bs->certs && certs)
 176         sk_X509_free(untrusted);
 177     return ret;
 178 }
 179
 180 static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs,
 181                             STACK_OF(X509) *certs, X509_STORE *st,
 182                             unsigned long flags)
 183 {
 184     X509 *signer;
 185     OCSP_RESPID *rid = bs->tbsResponseData->responderId;
 186     if ((signer = ocsp_find_signer_sk(certs, rid))) {
 187         *psigner = signer;
 188         return 2;
 189     }
 190     if (!(flags & OCSP_NOINTERN) &&
 191         (signer = ocsp_find_signer_sk(bs->certs, rid))) {
 192         *psigner = signer;
 193         return 1;
 194     }
 195     /* Maybe lookup from store if by subject name */
 196
 197     *psigner = NULL;
 198     return 0;
 199 }
 200
 201 static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id)
 202 {
 203     int i;
 204     unsigned char tmphash[SHA_DIGEST_LENGTH], *keyhash;
 205     X509 *x;
 206
 207     /* Easy if lookup by name */
 208     if (id->type == V_OCSP_RESPID_NAME)
 209         return X509_find_by_subject(certs, id->value.byName);
 210
 211     /* Lookup by key hash */
 212
 213     /* If key hash isn't SHA1 length then forget it */
 214     if (id->value.byKey->length != SHA_DIGEST_LENGTH)
 215         return NULL;
 216     keyhash = id->value.byKey->data;
 217     /* Calculate hash of each key and compare */
 218     for (i = 0; i < sk_X509_num(certs); i++) {
 219         x = sk_X509_value(certs, i);
 220         X509_pubkey_digest(x, EVP_sha1(), tmphash, NULL);
 221         if (!memcmp(keyhash, tmphash, SHA_DIGEST_LENGTH))
 222             return x;
 223     }
 224     return NULL;
 225 }
 226
 227 static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain,
 228                              unsigned long flags)
 229 {
 230     STACK_OF(OCSP_SINGLERESP) *sresp;
 231     X509 *signer, *sca;
 232     OCSP_CERTID *caid = NULL;
 233     int i;
 234     sresp = bs->tbsResponseData->responses;
 235
 236     if (sk_X509_num(chain) <= 0) {
 237         OCSPerr(OCSP_F_OCSP_CHECK_ISSUER, OCSP_R_NO_CERTIFICATES_IN_CHAIN);
 238         return -1;
 239     }
 240
 241     /* See if the issuer IDs match. */
 242     i = ocsp_check_ids(sresp, &caid);
 243
 244     /* If ID mismatch or other error then return */
 245     if (i <= 0)
 246         return i;
 247
 248     signer = sk_X509_value(chain, 0);
 249     /* Check to see if OCSP responder CA matches request CA */
 250     if (sk_X509_num(chain) > 1) {
 251         sca = sk_X509_value(chain, 1);
 252         i = ocsp_match_issuerid(sca, caid, sresp);
 253         if (i < 0)
 254             return i;
 255         if (i) {
 256             /* We have a match, if extensions OK then success */
 257             if (ocsp_check_delegated(signer, flags))
 258                 return 1;
 259             return 0;
 260         }
 261     }
 262
 263     /* Otherwise check if OCSP request signed directly by request CA */
 264     return ocsp_match_issuerid(signer, caid, sresp);
 265 }
 266
 267 /*
 268  * Check the issuer certificate IDs for equality. If there is a mismatch with
 269  * the same algorithm then there's no point trying to match any certificates
 270  * against the issuer. If the issuer IDs all match then we just need to check
 271  * equality against one of them.
 272  */
 273
 274 static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret)
 275 {
 276     OCSP_CERTID *tmpid, *cid;
 277     int i, idcount;
 278
 279     idcount = sk_OCSP_SINGLERESP_num(sresp);
 280     if (idcount <= 0) {
 281         OCSPerr(OCSP_F_OCSP_CHECK_IDS,
 282                 OCSP_R_RESPONSE_CONTAINS_NO_REVOCATION_DATA);
 283         return -1;
 284     }
 285
 286     cid = sk_OCSP_SINGLERESP_value(sresp, 0)->certId;
 287
 288     *ret = NULL;
 289
 290     for (i = 1; i < idcount; i++) {
 291         tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;
 292         /* Check to see if IDs match */
 293         if (OCSP_id_issuer_cmp(cid, tmpid)) {
 294             /* If algoritm mismatch let caller deal with it */
 295             if (OBJ_cmp(tmpid->hashAlgorithm->algorithm,
 296                         cid->hashAlgorithm->algorithm))
 297                 return 2;
 298             /* Else mismatch */
 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 ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid,
 309                                STACK_OF(OCSP_SINGLERESP) *sresp)
 310 {
 311     /* If only one ID to match then do it */
 312     if (cid) {
 313         const EVP_MD *dgst;
 314         X509_NAME *iname;
 315         int mdlen;
 316         unsigned char md[EVP_MAX_MD_SIZE];
 317         if ((dgst = EVP_get_digestbyobj(cid->hashAlgorithm->algorithm))
 318                 == NULL) {
 319             OCSPerr(OCSP_F_OCSP_MATCH_ISSUERID,
 320                     OCSP_R_UNKNOWN_MESSAGE_DIGEST);
 321             return -1;
 322         }
 323
 324         mdlen = EVP_MD_size(dgst);
 325         if (mdlen < 0)
 326             return -1;
 327         if ((cid->issuerNameHash->length != mdlen) ||
 328             (cid->issuerKeyHash->length != mdlen))
 329             return 0;
 330         iname = X509_get_subject_name(cert);
 331         if (!X509_NAME_digest(iname, dgst, md, NULL))
 332             return -1;
 333         if (memcmp(md, cid->issuerNameHash->data, mdlen))
 334             return 0;
 335         X509_pubkey_digest(cert, dgst, md, NULL);
 336         if (memcmp(md, cid->issuerKeyHash->data, mdlen))
 337             return 0;
 338
 339         return 1;
 340
 341     } else {
 342         /* We have to match the whole lot */
 343         int i, ret;
 344         OCSP_CERTID *tmpid;
 345         for (i = 0; i < sk_OCSP_SINGLERESP_num(sresp); i++) {
 346             tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;
 347             ret = ocsp_match_issuerid(cert, tmpid, NULL);
 348             if (ret <= 0)
 349                 return ret;
 350         }
 351         return 1;
 352     }
 353
 354 }
 355
 356 static int ocsp_check_delegated(X509 *x, int flags)
 357 {
 358     X509_check_purpose(x, -1, 0);
 359     if ((x->ex_flags & EXFLAG_XKUSAGE) && (x->ex_xkusage & XKU_OCSP_SIGN))
 360         return 1;
 361     OCSPerr(OCSP_F_OCSP_CHECK_DELEGATED, OCSP_R_MISSING_OCSPSIGNING_USAGE);
 362     return 0;
 363 }
 364
 365 /*
 366  * Verify an OCSP request. This is fortunately much easier than OCSP response
 367  * verify. Just find the signers certificate and verify it against a given
 368  * trust value.
 369  */
 370
 371 int OCSP_request_verify(OCSP_REQUEST *req, STACK_OF(X509) *certs,
 372                         X509_STORE *store, unsigned long flags)
 373 {
 374     X509 *signer;
 375     X509_NAME *nm;
 376     GENERAL_NAME *gen;
 377     int ret;
 378     X509_STORE_CTX ctx;
 379     if (!req->optionalSignature) {
 380         OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_REQUEST_NOT_SIGNED);
 381         return 0;
 382     }
 383     gen = req->tbsRequest->requestorName;
 384     if (!gen || gen->type != GEN_DIRNAME) {
 385         OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,
 386                 OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE);
 387         return 0;
 388     }
 389     nm = gen->d.directoryName;
 390     ret = ocsp_req_find_signer(&signer, req, nm, certs, store, flags);
 391     if (ret <= 0) {
 392         OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,
 393                 OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
 394         return 0;
 395     }
 396     if ((ret == 2) && (flags & OCSP_TRUSTOTHER))
 397         flags |= OCSP_NOVERIFY;
 398     if (!(flags & OCSP_NOSIGS)) {
 399         EVP_PKEY *skey;
 400         skey = X509_get_pubkey(signer);
 401         ret = OCSP_REQUEST_verify(req, skey);
 402         EVP_PKEY_free(skey);
 403         if (ret <= 0) {
 404             OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_SIGNATURE_FAILURE);
 405             return 0;
 406         }
 407     }
 408     if (!(flags & OCSP_NOVERIFY)) {
 409         int init_res;
 410         if (flags & OCSP_NOCHAIN)
 411             init_res = X509_STORE_CTX_init(&ctx, store, signer, NULL);
 412         else
 413             init_res = X509_STORE_CTX_init(&ctx, store, signer,
 414                                            req->optionalSignature->certs);
 415         if (!init_res) {
 416             OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, ERR_R_X509_LIB);
 417             return 0;
 418         }
 419
 420         X509_STORE_CTX_set_purpose(&ctx, X509_PURPOSE_OCSP_HELPER);
 421         X509_STORE_CTX_set_trust(&ctx, X509_TRUST_OCSP_REQUEST);
 422         ret = X509_verify_cert(&ctx);
 423         X509_STORE_CTX_cleanup(&ctx);
 424         if (ret <= 0) {
 425             ret = X509_STORE_CTX_get_error(&ctx);
 426             OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,
 427                     OCSP_R_CERTIFICATE_VERIFY_ERROR);
 428             ERR_add_error_data(2, "Verify error:",
 429                                X509_verify_cert_error_string(ret));
 430             return 0;
 431         }
 432     }
 433     return 1;
 434 }
 435
 436 static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req,
 437                                 X509_NAME *nm, STACK_OF(X509) *certs,
 438                                 X509_STORE *st, unsigned long flags)
 439 {
 440     X509 *signer;
 441     if (!(flags & OCSP_NOINTERN)) {
 442         signer = X509_find_by_subject(req->optionalSignature->certs, nm);
 443         if (signer) {
 444             *psigner = signer;
 445             return 1;
 446         }
 447     }
 448
 449     signer = X509_find_by_subject(certs, nm);
 450     if (signer) {
 451         *psigner = signer;
 452         return 2;
 453     }
 454     return 0;
 455 }