crypto/ocsp/ocsp_vfy.c

   1 /*
   2  * Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/ocsp.h>
  11 #include "ocsp_lcl.h"
  12 #include <openssl/err.h>
  13 #include <string.h>
  14
  15 static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs,
  16                             STACK_OF(X509) *certs, unsigned long flags);
  17 static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id);
  18 static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain);
  19 static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp,
  20                           OCSP_CERTID **ret);
  21 static int ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid,
  22                                STACK_OF(OCSP_SINGLERESP) *sresp);
  23 static int ocsp_check_delegated(X509 *x);
  24 static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req,
  25                                 X509_NAME *nm, STACK_OF(X509) *certs,
  26                                 unsigned long flags);
  27
  28 /* Verify a basic response message */
  29
  30 int OCSP_basic_verify(OCSP_BASICRESP *bs, STACK_OF(X509) *certs,
  31                       X509_STORE *st, unsigned long flags)
  32 {
  33     X509 *signer, *x;
  34     STACK_OF(X509) *chain = NULL;
  35     STACK_OF(X509) *untrusted = NULL;
  36     X509_STORE_CTX *ctx = NULL;
  37     int i, ret = ocsp_find_signer(&signer, bs, certs, flags);
  38
  39     if (!ret) {
  40         OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,
  41                 OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
  42         goto end;
  43     }
  44     ctx = X509_STORE_CTX_new();
  45     if (ctx == NULL) {
  46         OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_MALLOC_FAILURE);
  47         goto f_err;
  48     }
  49     if ((ret == 2) && (flags & OCSP_TRUSTOTHER))
  50         flags |= OCSP_NOVERIFY;
  51     if (!(flags & OCSP_NOSIGS)) {
  52         EVP_PKEY *skey;
  53         skey = X509_get0_pubkey(signer);
  54         if (skey == NULL) {
  55             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_NO_SIGNER_KEY);
  56             goto err;
  57         }
  58         ret = OCSP_BASICRESP_verify(bs, skey, 0);
  59         if (ret <= 0) {
  60             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_SIGNATURE_FAILURE);
  61             goto end;
  62         }
  63     }
  64     if (!(flags & OCSP_NOVERIFY)) {
  65         int init_res;
  66         if (flags & OCSP_NOCHAIN) {
  67             untrusted = NULL;
  68         } else if (bs->certs && certs) {
  69             untrusted = sk_X509_dup(bs->certs);
  70             for (i = 0; i < sk_X509_num(certs); i++) {
  71                 if (!sk_X509_push(untrusted, sk_X509_value(certs, i))) {
  72                     OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_MALLOC_FAILURE);
  73                     goto f_err;
  74                 }
  75             }
  76         } else if (certs != NULL) {
  77             untrusted = certs;
  78         } else {
  79             untrusted = bs->certs;
  80         }
  81         init_res = X509_STORE_CTX_init(ctx, st, signer, untrusted);
  82         if (!init_res) {
  83             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_X509_LIB);
  84             goto f_err;
  85         }
  86
  87         X509_STORE_CTX_set_purpose(ctx, X509_PURPOSE_OCSP_HELPER);
  88         ret = X509_verify_cert(ctx);
  89         chain = X509_STORE_CTX_get1_chain(ctx);
  90         if (ret <= 0) {
  91             i = X509_STORE_CTX_get_error(ctx);
  92             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,
  93                     OCSP_R_CERTIFICATE_VERIFY_ERROR);
  94             ERR_add_error_data(2, "Verify error:",
  95                                X509_verify_cert_error_string(i));
  96             goto end;
  97         }
  98         if (flags & OCSP_NOCHECKS) {
  99             ret = 1;
 100             goto end;
 101         }
 102         /*
 103          * At this point we have a valid certificate chain need to verify it
 104          * against the OCSP issuer criteria.
 105          */
 106         ret = ocsp_check_issuer(bs, chain);
 107
 108         /* If fatal error or valid match then finish */
 109         if (ret != 0)
 110             goto end;
 111
 112         /*
 113          * Easy case: explicitly trusted. Get root CA and check for explicit
 114          * trust
 115          */
 116         if (flags & OCSP_NOEXPLICIT)
 117             goto end;
 118
 119         x = sk_X509_value(chain, sk_X509_num(chain) - 1);
 120         if (X509_check_trust(x, NID_OCSP_sign, 0) != X509_TRUST_TRUSTED) {
 121             OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_ROOT_CA_NOT_TRUSTED);
 122             goto err;
 123         }
 124         ret = 1;
 125     }
 126  end:
 127     X509_STORE_CTX_free(ctx);
 128     sk_X509_pop_free(chain, X509_free);
 129     if (bs->certs && certs)
 130         sk_X509_free(untrusted);
 131     return ret;
 132
 133  err:
 134     ret = 0;
 135     goto end;
 136  f_err:
 137     ret = -1;
 138     goto end;
 139 }
 140
 141 int OCSP_resp_get0_signer(OCSP_BASICRESP *bs, X509 **signer,
 142                           STACK_OF(X509) *extra_certs)
 143 {
 144     int ret;
 145
 146     ret = ocsp_find_signer(signer, bs, extra_certs, 0);
 147     return (ret > 0) ? 1 : 0;
 148 }
 149
 150 static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs,
 151                             STACK_OF(X509) *certs, unsigned long flags)
 152 {
 153     X509 *signer;
 154     OCSP_RESPID *rid = &bs->tbsResponseData.responderId;
 155     if ((signer = ocsp_find_signer_sk(certs, rid))) {
 156         *psigner = signer;
 157         return 2;
 158     }
 159     if (!(flags & OCSP_NOINTERN) &&
 160         (signer = ocsp_find_signer_sk(bs->certs, rid))) {
 161         *psigner = signer;
 162         return 1;
 163     }
 164     /* Maybe lookup from store if by subject name */
 165
 166     *psigner = NULL;
 167     return 0;
 168 }
 169
 170 static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id)
 171 {
 172     int i;
 173     unsigned char tmphash[SHA_DIGEST_LENGTH], *keyhash;
 174     X509 *x;
 175
 176     /* Easy if lookup by name */
 177     if (id->type == V_OCSP_RESPID_NAME)
 178         return X509_find_by_subject(certs, id->value.byName);
 179
 180     /* Lookup by key hash */
 181
 182     /* If key hash isn't SHA1 length then forget it */
 183     if (id->value.byKey->length != SHA_DIGEST_LENGTH)
 184         return NULL;
 185     keyhash = id->value.byKey->data;
 186     /* Calculate hash of each key and compare */
 187     for (i = 0; i < sk_X509_num(certs); i++) {
 188         x = sk_X509_value(certs, i);
 189         X509_pubkey_digest(x, EVP_sha1(), tmphash, NULL);
 190         if (!memcmp(keyhash, tmphash, SHA_DIGEST_LENGTH))
 191             return x;
 192     }
 193     return NULL;
 194 }
 195
 196 static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain)
 197 {
 198     STACK_OF(OCSP_SINGLERESP) *sresp;
 199     X509 *signer, *sca;
 200     OCSP_CERTID *caid = NULL;
 201     int i;
 202     sresp = bs->tbsResponseData.responses;
 203
 204     if (sk_X509_num(chain) <= 0) {
 205         OCSPerr(OCSP_F_OCSP_CHECK_ISSUER, OCSP_R_NO_CERTIFICATES_IN_CHAIN);
 206         return -1;
 207     }
 208
 209     /* See if the issuer IDs match. */
 210     i = ocsp_check_ids(sresp, &caid);
 211
 212     /* If ID mismatch or other error then return */
 213     if (i <= 0)
 214         return i;
 215
 216     signer = sk_X509_value(chain, 0);
 217     /* Check to see if OCSP responder CA matches request CA */
 218     if (sk_X509_num(chain) > 1) {
 219         sca = sk_X509_value(chain, 1);
 220         i = ocsp_match_issuerid(sca, caid, sresp);
 221         if (i < 0)
 222             return i;
 223         if (i) {
 224             /* We have a match, if extensions OK then success */
 225             if (ocsp_check_delegated(signer))
 226                 return 1;
 227             return 0;
 228         }
 229     }
 230
 231     /* Otherwise check if OCSP request signed directly by request CA */
 232     return ocsp_match_issuerid(signer, caid, sresp);
 233 }
 234
 235 /*
 236  * Check the issuer certificate IDs for equality. If there is a mismatch with
 237  * the same algorithm then there's no point trying to match any certificates
 238  * against the issuer. If the issuer IDs all match then we just need to check
 239  * equality against one of them.
 240  */
 241
 242 static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret)
 243 {
 244     OCSP_CERTID *tmpid, *cid;
 245     int i, idcount;
 246
 247     idcount = sk_OCSP_SINGLERESP_num(sresp);
 248     if (idcount <= 0) {
 249         OCSPerr(OCSP_F_OCSP_CHECK_IDS,
 250                 OCSP_R_RESPONSE_CONTAINS_NO_REVOCATION_DATA);
 251         return -1;
 252     }
 253
 254     cid = sk_OCSP_SINGLERESP_value(sresp, 0)->certId;
 255
 256     *ret = NULL;
 257
 258     for (i = 1; i < idcount; i++) {
 259         tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;
 260         /* Check to see if IDs match */
 261         if (OCSP_id_issuer_cmp(cid, tmpid)) {
 262             /* If algorithm mismatch let caller deal with it */
 263             if (OBJ_cmp(tmpid->hashAlgorithm.algorithm,
 264                         cid->hashAlgorithm.algorithm))
 265                 return 2;
 266             /* Else mismatch */
 267             return 0;
 268         }
 269     }
 270
 271     /* All IDs match: only need to check one ID */
 272     *ret = cid;
 273     return 1;
 274 }
 275
 276 static int ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid,
 277                                STACK_OF(OCSP_SINGLERESP) *sresp)
 278 {
 279     /* If only one ID to match then do it */
 280     if (cid) {
 281         const EVP_MD *dgst;
 282         X509_NAME *iname;
 283         int mdlen;
 284         unsigned char md[EVP_MAX_MD_SIZE];
 285         if ((dgst = EVP_get_digestbyobj(cid->hashAlgorithm.algorithm))
 286                 == NULL) {
 287             OCSPerr(OCSP_F_OCSP_MATCH_ISSUERID,
 288                     OCSP_R_UNKNOWN_MESSAGE_DIGEST);
 289             return -1;
 290         }
 291
 292         mdlen = EVP_MD_size(dgst);
 293         if (mdlen < 0)
 294             return -1;
 295         if ((cid->issuerNameHash.length != mdlen) ||
 296             (cid->issuerKeyHash.length != mdlen))
 297             return 0;
 298         iname = X509_get_subject_name(cert);
 299         if (!X509_NAME_digest(iname, dgst, md, NULL))
 300             return -1;
 301         if (memcmp(md, cid->issuerNameHash.data, mdlen))
 302             return 0;
 303         X509_pubkey_digest(cert, dgst, md, NULL);
 304         if (memcmp(md, cid->issuerKeyHash.data, mdlen))
 305             return 0;
 306
 307         return 1;
 308
 309     } else {
 310         /* We have to match the whole lot */
 311         int i, ret;
 312         OCSP_CERTID *tmpid;
 313         for (i = 0; i < sk_OCSP_SINGLERESP_num(sresp); i++) {
 314             tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;
 315             ret = ocsp_match_issuerid(cert, tmpid, NULL);
 316             if (ret <= 0)
 317                 return ret;
 318         }
 319         return 1;
 320     }
 321
 322 }
 323
 324 static int ocsp_check_delegated(X509 *x)
 325 {
 326     if ((X509_get_extension_flags(x) & EXFLAG_XKUSAGE)
 327         && (X509_get_extended_key_usage(x) & XKU_OCSP_SIGN))
 328         return 1;
 329     OCSPerr(OCSP_F_OCSP_CHECK_DELEGATED, OCSP_R_MISSING_OCSPSIGNING_USAGE);
 330     return 0;
 331 }
 332
 333 /*
 334  * Verify an OCSP request. This is fortunately much easier than OCSP response
 335  * verify. Just find the signers certificate and verify it against a given
 336  * trust value.
 337  */
 338
 339 int OCSP_request_verify(OCSP_REQUEST *req, STACK_OF(X509) *certs,
 340                         X509_STORE *store, unsigned long flags)
 341 {
 342     X509 *signer;
 343     X509_NAME *nm;
 344     GENERAL_NAME *gen;
 345     int ret = 0;
 346     X509_STORE_CTX *ctx = X509_STORE_CTX_new();
 347
 348     if (ctx == NULL) {
 349         OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, ERR_R_MALLOC_FAILURE);
 350         goto err;
 351     }
 352
 353     if (!req->optionalSignature) {
 354         OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_REQUEST_NOT_SIGNED);
 355         goto err;
 356     }
 357     gen = req->tbsRequest.requestorName;
 358     if (!gen || gen->type != GEN_DIRNAME) {
 359         OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,
 360                 OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE);
 361         goto err;
 362     }
 363     nm = gen->d.directoryName;
 364     ret = ocsp_req_find_signer(&signer, req, nm, certs, flags);
 365     if (ret <= 0) {
 366         OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,
 367                 OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
 368         goto err;
 369     }
 370     if ((ret == 2) && (flags & OCSP_TRUSTOTHER))
 371         flags |= OCSP_NOVERIFY;
 372     if (!(flags & OCSP_NOSIGS)) {
 373         EVP_PKEY *skey;
 374         skey = X509_get0_pubkey(signer);
 375         ret = OCSP_REQUEST_verify(req, skey);
 376         if (ret <= 0) {
 377             OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_SIGNATURE_FAILURE);
 378             goto err;
 379         }
 380     }
 381     if (!(flags & OCSP_NOVERIFY)) {
 382         int init_res;
 383         if (flags & OCSP_NOCHAIN)
 384             init_res = X509_STORE_CTX_init(ctx, store, signer, NULL);
 385         else
 386             init_res = X509_STORE_CTX_init(ctx, store, signer,
 387                                            req->optionalSignature->certs);
 388         if (!init_res) {
 389             OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, ERR_R_X509_LIB);
 390             goto err;
 391         }
 392
 393         X509_STORE_CTX_set_purpose(ctx, X509_PURPOSE_OCSP_HELPER);
 394         X509_STORE_CTX_set_trust(ctx, X509_TRUST_OCSP_REQUEST);
 395         ret = X509_verify_cert(ctx);
 396         if (ret <= 0) {
 397             ret = X509_STORE_CTX_get_error(ctx);
 398             OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,
 399                     OCSP_R_CERTIFICATE_VERIFY_ERROR);
 400             ERR_add_error_data(2, "Verify error:",
 401                                X509_verify_cert_error_string(ret));
 402             goto err;
 403         }
 404     }
 405     ret = 1;
 406     goto end;
 407
 408 err:
 409     ret = 0;
 410 end:
 411     X509_STORE_CTX_free(ctx);
 412     return ret;
 413
 414 }
 415
 416 static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req,
 417                                 X509_NAME *nm, STACK_OF(X509) *certs,
 418                                 unsigned long flags)
 419 {
 420     X509 *signer;
 421     if (!(flags & OCSP_NOINTERN)) {
 422         signer = X509_find_by_subject(req->optionalSignature->certs, nm);
 423         if (signer) {
 424             *psigner = signer;
 425             return 1;
 426         }
 427     }
 428
 429     signer = X509_find_by_subject(certs, nm);
 430     if (signer) {
 431         *psigner = signer;
 432         return 2;
 433     }
 434     return 0;
 435 }