crypto/ts/ts_rsp_verify.c

   1 /*
   2  * Copyright 2006-2019 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (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 <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/objects.h>
  13 #include <openssl/ts.h>
  14 #include <openssl/pkcs7.h>
  15 #include "ts_lcl.h"
  16 #include "crypto/ess.h"
  17
  18 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
  19                           X509 *signer, STACK_OF(X509) **chain);
  20 static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
  21                                   STACK_OF(X509) *chain);
  22 static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert);
  23 static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert);
  24 static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
  25                                     PKCS7 *token, TS_TST_INFO *tst_info);
  26 static int ts_check_status_info(TS_RESP *response);
  27 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text);
  28 static int ts_check_policy(const ASN1_OBJECT *req_oid,
  29                            const TS_TST_INFO *tst_info);
  30 static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
  31                               X509_ALGOR **md_alg,
  32                               unsigned char **imprint, unsigned *imprint_len);
  33 static int ts_check_imprints(X509_ALGOR *algor_a,
  34                              const unsigned char *imprint_a, unsigned len_a,
  35                              TS_TST_INFO *tst_info);
  36 static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info);
  37 static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer);
  38 static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names,
  39                         GENERAL_NAME *name);
  40 static int ts_find_cert_v2(STACK_OF(ESS_CERT_ID_V2) *cert_ids, X509 *cert);
  41
  42 /*
  43  * This must be large enough to hold all values in ts_status_text (with
  44  * comma separator) or all text fields in ts_failure_info (also with comma).
  45  */
  46 #define TS_STATUS_BUF_SIZE      256
  47
  48 /*
  49  * Local mapping between response codes and descriptions.
  50  */
  51 static const char *ts_status_text[] = {
  52     "granted",
  53     "grantedWithMods",
  54     "rejection",
  55     "waiting",
  56     "revocationWarning",
  57     "revocationNotification"
  58 };
  59
  60 #define TS_STATUS_TEXT_SIZE     OSSL_NELEM(ts_status_text)
  61
  62 static struct {
  63     int code;
  64     const char *text;
  65 } ts_failure_info[] = {
  66     {TS_INFO_BAD_ALG, "badAlg"},
  67     {TS_INFO_BAD_REQUEST, "badRequest"},
  68     {TS_INFO_BAD_DATA_FORMAT, "badDataFormat"},
  69     {TS_INFO_TIME_NOT_AVAILABLE, "timeNotAvailable"},
  70     {TS_INFO_UNACCEPTED_POLICY, "unacceptedPolicy"},
  71     {TS_INFO_UNACCEPTED_EXTENSION, "unacceptedExtension"},
  72     {TS_INFO_ADD_INFO_NOT_AVAILABLE, "addInfoNotAvailable"},
  73     {TS_INFO_SYSTEM_FAILURE, "systemFailure"}
  74 };
  75
  76
  77 /*-
  78  * This function carries out the following tasks:
  79  *      - Checks if there is one and only one signer.
  80  *      - Search for the signing certificate in 'certs' and in the response.
  81  *      - Check the extended key usage and key usage fields of the signer
  82  *      certificate (done by the path validation).
  83  *      - Build and validate the certificate path.
  84  *      - Check if the certificate path meets the requirements of the
  85  *      SigningCertificate ESS signed attribute.
  86  *      - Verify the signature value.
  87  *      - Returns the signer certificate in 'signer', if 'signer' is not NULL.
  88  */
  89 int TS_RESP_verify_signature(PKCS7 *token, STACK_OF(X509) *certs,
  90                              X509_STORE *store, X509 **signer_out)
  91 {
  92     STACK_OF(PKCS7_SIGNER_INFO) *sinfos = NULL;
  93     PKCS7_SIGNER_INFO *si;
  94     STACK_OF(X509) *signers = NULL;
  95     X509 *signer;
  96     STACK_OF(X509) *chain = NULL;
  97     char buf[4096];
  98     int i, j = 0, ret = 0;
  99     BIO *p7bio = NULL;
 100
 101     /* Some sanity checks first. */
 102     if (!token) {
 103         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_INVALID_NULL_POINTER);
 104         goto err;
 105     }
 106     if (!PKCS7_type_is_signed(token)) {
 107         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_WRONG_CONTENT_TYPE);
 108         goto err;
 109     }
 110     sinfos = PKCS7_get_signer_info(token);
 111     if (!sinfos || sk_PKCS7_SIGNER_INFO_num(sinfos) != 1) {
 112         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_THERE_MUST_BE_ONE_SIGNER);
 113         goto err;
 114     }
 115     si = sk_PKCS7_SIGNER_INFO_value(sinfos, 0);
 116     if (PKCS7_get_detached(token)) {
 117         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_NO_CONTENT);
 118         goto err;
 119     }
 120
 121     /*
 122      * Get hold of the signer certificate, search only internal certificates
 123      * if it was requested.
 124      */
 125     signers = PKCS7_get0_signers(token, certs, 0);
 126     if (!signers || sk_X509_num(signers) != 1)
 127         goto err;
 128     signer = sk_X509_value(signers, 0);
 129
 130     if (!ts_verify_cert(store, certs, signer, &chain))
 131         goto err;
 132     if (!ts_check_signing_certs(si, chain))
 133         goto err;
 134     p7bio = PKCS7_dataInit(token, NULL);
 135
 136     /* We now have to 'read' from p7bio to calculate digests etc. */
 137     while ((i = BIO_read(p7bio, buf, sizeof(buf))) > 0)
 138         continue;
 139
 140     j = PKCS7_signatureVerify(p7bio, token, si, signer);
 141     if (j <= 0) {
 142         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_SIGNATURE_FAILURE);
 143         goto err;
 144     }
 145
 146     if (signer_out) {
 147         *signer_out = signer;
 148         X509_up_ref(signer);
 149     }
 150     ret = 1;
 151
 152  err:
 153     BIO_free_all(p7bio);
 154     sk_X509_pop_free(chain, X509_free);
 155     sk_X509_free(signers);
 156
 157     return ret;
 158 }
 159
 160 /*
 161  * The certificate chain is returned in chain. Caller is responsible for
 162  * freeing the vector.
 163  */
 164 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
 165                           X509 *signer, STACK_OF(X509) **chain)
 166 {
 167     X509_STORE_CTX *cert_ctx = NULL;
 168     int i;
 169     int ret = 0;
 170
 171     *chain = NULL;
 172     cert_ctx = X509_STORE_CTX_new();
 173     if (cert_ctx == NULL) {
 174         TSerr(TS_F_TS_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
 175         goto err;
 176     }
 177     if (!X509_STORE_CTX_init(cert_ctx, store, signer, untrusted))
 178         goto end;
 179     X509_STORE_CTX_set_purpose(cert_ctx, X509_PURPOSE_TIMESTAMP_SIGN);
 180     i = X509_verify_cert(cert_ctx);
 181     if (i <= 0) {
 182         int j = X509_STORE_CTX_get_error(cert_ctx);
 183         TSerr(TS_F_TS_VERIFY_CERT, TS_R_CERTIFICATE_VERIFY_ERROR);
 184         ERR_add_error_data(2, "Verify error:",
 185                            X509_verify_cert_error_string(j));
 186         goto err;
 187     }
 188     *chain = X509_STORE_CTX_get1_chain(cert_ctx);
 189     ret = 1;
 190     goto end;
 191
 192 err:
 193     ret = 0;
 194
 195 end:
 196     X509_STORE_CTX_free(cert_ctx);
 197     return ret;
 198 }
 199
 200 static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
 201                                   STACK_OF(X509) *chain)
 202 {
 203     ESS_SIGNING_CERT *ss = ESS_SIGNING_CERT_get(si);
 204     STACK_OF(ESS_CERT_ID) *cert_ids = NULL;
 205     ESS_SIGNING_CERT_V2 *ssv2 = ESS_SIGNING_CERT_V2_get(si);
 206     STACK_OF(ESS_CERT_ID_V2) *cert_ids_v2 = NULL;
 207     X509 *cert;
 208     int i = 0;
 209     int ret = 0;
 210
 211     if (ss != NULL) {
 212         cert_ids = ss->cert_ids;
 213         cert = sk_X509_value(chain, 0);
 214         if (ts_find_cert(cert_ids, cert) != 0)
 215             goto err;
 216
 217         /*
 218          * Check the other certificates of the chain if there are more than one
 219          * certificate ids in cert_ids.
 220          */
 221         if (sk_ESS_CERT_ID_num(cert_ids) > 1) {
 222             for (i = 1; i < sk_X509_num(chain); ++i) {
 223                 cert = sk_X509_value(chain, i);
 224                 if (ts_find_cert(cert_ids, cert) < 0)
 225                     goto err;
 226             }
 227         }
 228     } else if (ssv2 != NULL) {
 229         cert_ids_v2 = ssv2->cert_ids;
 230         cert = sk_X509_value(chain, 0);
 231         if (ts_find_cert_v2(cert_ids_v2, cert) != 0)
 232             goto err;
 233
 234         /*
 235          * Check the other certificates of the chain if there are more than one
 236          * certificate ids in cert_ids.
 237          */
 238         if (sk_ESS_CERT_ID_V2_num(cert_ids_v2) > 1) {
 239             for (i = 1; i < sk_X509_num(chain); ++i) {
 240                 cert = sk_X509_value(chain, i);
 241                 if (ts_find_cert_v2(cert_ids_v2, cert) < 0)
 242                     goto err;
 243             }
 244         }
 245     } else {
 246         goto err;
 247     }
 248
 249     ret = 1;
 250  err:
 251     if (!ret)
 252         TSerr(TS_F_TS_CHECK_SIGNING_CERTS,
 253               TS_R_ESS_SIGNING_CERTIFICATE_ERROR);
 254     ESS_SIGNING_CERT_free(ss);
 255     ESS_SIGNING_CERT_V2_free(ssv2);
 256     return ret;
 257 }
 258
 259 /* Returns < 0 if certificate is not found, certificate index otherwise. */
 260 static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert)
 261 {
 262     int i;
 263     unsigned char cert_sha1[SHA_DIGEST_LENGTH];
 264
 265     if (!cert_ids || !cert)
 266         return -1;
 267
 268     X509_digest(cert, EVP_sha1(), cert_sha1, NULL);
 269
 270     /* Recompute SHA1 hash of certificate if necessary (side effect). */
 271     X509_check_purpose(cert, -1, 0);
 272
 273     /* Look for cert in the cert_ids vector. */
 274     for (i = 0; i < sk_ESS_CERT_ID_num(cert_ids); ++i) {
 275         ESS_CERT_ID *cid = sk_ESS_CERT_ID_value(cert_ids, i);
 276
 277         if (cid->hash->length == SHA_DIGEST_LENGTH
 278             && memcmp(cid->hash->data, cert_sha1, SHA_DIGEST_LENGTH) == 0) {
 279             ESS_ISSUER_SERIAL *is = cid->issuer_serial;
 280             if (!is || !ts_issuer_serial_cmp(is, cert))
 281                 return i;
 282         }
 283     }
 284
 285     return -1;
 286 }
 287
 288 /* Returns < 0 if certificate is not found, certificate index otherwise. */
 289 static int ts_find_cert_v2(STACK_OF(ESS_CERT_ID_V2) *cert_ids, X509 *cert)
 290 {
 291     int i;
 292     unsigned char cert_digest[EVP_MAX_MD_SIZE];
 293     unsigned int len;
 294
 295     /* Look for cert in the cert_ids vector. */
 296     for (i = 0; i < sk_ESS_CERT_ID_V2_num(cert_ids); ++i) {
 297         ESS_CERT_ID_V2 *cid = sk_ESS_CERT_ID_V2_value(cert_ids, i);
 298         const EVP_MD *md;
 299
 300         if (cid->hash_alg != NULL)
 301             md = EVP_get_digestbyobj(cid->hash_alg->algorithm);
 302         else
 303             md = EVP_sha256();
 304
 305         X509_digest(cert, md, cert_digest, &len);
 306         if (cid->hash->length != (int)len)
 307             return -1;
 308
 309         if (memcmp(cid->hash->data, cert_digest, cid->hash->length) == 0) {
 310             ESS_ISSUER_SERIAL *is = cid->issuer_serial;
 311
 312             if (is == NULL || !ts_issuer_serial_cmp(is, cert))
 313                 return i;
 314         }
 315     }
 316
 317     return -1;
 318 }
 319
 320 static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert)
 321 {
 322     GENERAL_NAME *issuer;
 323
 324     if (!is || !cert || sk_GENERAL_NAME_num(is->issuer) != 1)
 325         return -1;
 326
 327     issuer = sk_GENERAL_NAME_value(is->issuer, 0);
 328     if (issuer->type != GEN_DIRNAME
 329         || X509_NAME_cmp(issuer->d.dirn, X509_get_issuer_name(cert)))
 330         return -1;
 331
 332     if (ASN1_INTEGER_cmp(is->serial, X509_get_serialNumber(cert)))
 333         return -1;
 334
 335     return 0;
 336 }
 337
 338 /*-
 339  * Verifies whether 'response' contains a valid response with regards
 340  * to the settings of the context:
 341  *      - Gives an error message if the TS_TST_INFO is not present.
 342  *      - Calls _TS_RESP_verify_token to verify the token content.
 343  */
 344 int TS_RESP_verify_response(TS_VERIFY_CTX *ctx, TS_RESP *response)
 345 {
 346     PKCS7 *token = response->token;
 347     TS_TST_INFO *tst_info = response->tst_info;
 348     int ret = 0;
 349
 350     if (!ts_check_status_info(response))
 351         goto err;
 352     if (!int_ts_RESP_verify_token(ctx, token, tst_info))
 353         goto err;
 354     ret = 1;
 355
 356  err:
 357     return ret;
 358 }
 359
 360 /*
 361  * Tries to extract a TS_TST_INFO structure from the PKCS7 token and
 362  * calls the internal int_TS_RESP_verify_token function for verifying it.
 363  */
 364 int TS_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token)
 365 {
 366     TS_TST_INFO *tst_info = PKCS7_to_TS_TST_INFO(token);
 367     int ret = 0;
 368     if (tst_info) {
 369         ret = int_ts_RESP_verify_token(ctx, token, tst_info);
 370         TS_TST_INFO_free(tst_info);
 371     }
 372     return ret;
 373 }
 374
 375 /*-
 376  * Verifies whether the 'token' contains a valid time stamp token
 377  * with regards to the settings of the context. Only those checks are
 378  * carried out that are specified in the context:
 379  *      - Verifies the signature of the TS_TST_INFO.
 380  *      - Checks the version number of the response.
 381  *      - Check if the requested and returned policies math.
 382  *      - Check if the message imprints are the same.
 383  *      - Check if the nonces are the same.
 384  *      - Check if the TSA name matches the signer.
 385  *      - Check if the TSA name is the expected TSA.
 386  */
 387 static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
 388                                     PKCS7 *token, TS_TST_INFO *tst_info)
 389 {
 390     X509 *signer = NULL;
 391     GENERAL_NAME *tsa_name = tst_info->tsa;
 392     X509_ALGOR *md_alg = NULL;
 393     unsigned char *imprint = NULL;
 394     unsigned imprint_len = 0;
 395     int ret = 0;
 396     int flags = ctx->flags;
 397
 398     /* Some options require us to also check the signature */
 399     if (((flags & TS_VFY_SIGNER) && tsa_name != NULL)
 400             || (flags & TS_VFY_TSA_NAME)) {
 401         flags |= TS_VFY_SIGNATURE;
 402     }
 403
 404     if ((flags & TS_VFY_SIGNATURE)
 405         && !TS_RESP_verify_signature(token, ctx->certs, ctx->store, &signer))
 406         goto err;
 407     if ((flags & TS_VFY_VERSION)
 408         && TS_TST_INFO_get_version(tst_info) != 1) {
 409         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_UNSUPPORTED_VERSION);
 410         goto err;
 411     }
 412     if ((flags & TS_VFY_POLICY)
 413         && !ts_check_policy(ctx->policy, tst_info))
 414         goto err;
 415     if ((flags & TS_VFY_IMPRINT)
 416         && !ts_check_imprints(ctx->md_alg, ctx->imprint, ctx->imprint_len,
 417                               tst_info))
 418         goto err;
 419     if ((flags & TS_VFY_DATA)
 420         && (!ts_compute_imprint(ctx->data, tst_info,
 421                                 &md_alg, &imprint, &imprint_len)
 422             || !ts_check_imprints(md_alg, imprint, imprint_len, tst_info)))
 423         goto err;
 424     if ((flags & TS_VFY_NONCE)
 425         && !ts_check_nonces(ctx->nonce, tst_info))
 426         goto err;
 427     if ((flags & TS_VFY_SIGNER)
 428         && tsa_name && !ts_check_signer_name(tsa_name, signer)) {
 429         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_NAME_MISMATCH);
 430         goto err;
 431     }
 432     if ((flags & TS_VFY_TSA_NAME)
 433         && !ts_check_signer_name(ctx->tsa_name, signer)) {
 434         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_UNTRUSTED);
 435         goto err;
 436     }
 437     ret = 1;
 438
 439  err:
 440     X509_free(signer);
 441     X509_ALGOR_free(md_alg);
 442     OPENSSL_free(imprint);
 443     return ret;
 444 }
 445
 446 static int ts_check_status_info(TS_RESP *response)
 447 {
 448     TS_STATUS_INFO *info = response->status_info;
 449     long status = ASN1_INTEGER_get(info->status);
 450     const char *status_text = NULL;
 451     char *embedded_status_text = NULL;
 452     char failure_text[TS_STATUS_BUF_SIZE] = "";
 453
 454     if (status == 0 || status == 1)
 455         return 1;
 456
 457     /* There was an error, get the description in status_text. */
 458     if (0 <= status && status < (long) OSSL_NELEM(ts_status_text))
 459         status_text = ts_status_text[status];
 460     else
 461         status_text = "unknown code";
 462
 463     if (sk_ASN1_UTF8STRING_num(info->text) > 0
 464         && (embedded_status_text = ts_get_status_text(info->text)) == NULL)
 465         return 0;
 466
 467     /* Fill in failure_text with the failure information. */
 468     if (info->failure_info) {
 469         int i;
 470         int first = 1;
 471         for (i = 0; i < (int)OSSL_NELEM(ts_failure_info); ++i) {
 472             if (ASN1_BIT_STRING_get_bit(info->failure_info,
 473                                         ts_failure_info[i].code)) {
 474                 if (!first)
 475                     strcat(failure_text, ",");
 476                 else
 477                     first = 0;
 478                 strcat(failure_text, ts_failure_info[i].text);
 479             }
 480         }
 481     }
 482     if (failure_text[0] == '\0')
 483         strcpy(failure_text, "unspecified");
 484
 485     TSerr(TS_F_TS_CHECK_STATUS_INFO, TS_R_NO_TIME_STAMP_TOKEN);
 486     ERR_add_error_data(6,
 487                        "status code: ", status_text,
 488                        ", status text: ", embedded_status_text ?
 489                        embedded_status_text : "unspecified",
 490                        ", failure codes: ", failure_text);
 491     OPENSSL_free(embedded_status_text);
 492
 493     return 0;
 494 }
 495
 496 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text)
 497 {
 498     int i;
 499     int length = 0;
 500     char *result = NULL;
 501     char *p;
 502
 503     for (i = 0; i < sk_ASN1_UTF8STRING_num(text); ++i) {
 504         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
 505         if (ASN1_STRING_length(current) > TS_MAX_STATUS_LENGTH - length - 1)
 506             return NULL;
 507         length += ASN1_STRING_length(current);
 508         length += 1;            /* separator character */
 509     }
 510     if ((result = OPENSSL_malloc(length)) == NULL) {
 511         TSerr(TS_F_TS_GET_STATUS_TEXT, ERR_R_MALLOC_FAILURE);
 512         return NULL;
 513     }
 514
 515     for (i = 0, p = result; i < sk_ASN1_UTF8STRING_num(text); ++i) {
 516         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
 517         length = ASN1_STRING_length(current);
 518         if (i > 0)
 519             *p++ = '/';
 520         strncpy(p, (const char *)ASN1_STRING_get0_data(current), length);
 521         p += length;
 522     }
 523     *p = '\0';
 524
 525     return result;
 526 }
 527
 528 static int ts_check_policy(const ASN1_OBJECT *req_oid,
 529                            const TS_TST_INFO *tst_info)
 530 {
 531     const ASN1_OBJECT *resp_oid = tst_info->policy_id;
 532
 533     if (OBJ_cmp(req_oid, resp_oid) != 0) {
 534         TSerr(TS_F_TS_CHECK_POLICY, TS_R_POLICY_MISMATCH);
 535         return 0;
 536     }
 537
 538     return 1;
 539 }
 540
 541 static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
 542                               X509_ALGOR **md_alg,
 543                               unsigned char **imprint, unsigned *imprint_len)
 544 {
 545     TS_MSG_IMPRINT *msg_imprint = tst_info->msg_imprint;
 546     X509_ALGOR *md_alg_resp = msg_imprint->hash_algo;
 547     const EVP_MD *md;
 548     EVP_MD_CTX *md_ctx = NULL;
 549     unsigned char buffer[4096];
 550     int length;
 551
 552     *md_alg = NULL;
 553     *imprint = NULL;
 554
 555     if ((*md_alg = X509_ALGOR_dup(md_alg_resp)) == NULL)
 556         goto err;
 557     if ((md = EVP_get_digestbyobj((*md_alg)->algorithm)) == NULL) {
 558         TSerr(TS_F_TS_COMPUTE_IMPRINT, TS_R_UNSUPPORTED_MD_ALGORITHM);
 559         goto err;
 560     }
 561     length = EVP_MD_size(md);
 562     if (length < 0)
 563         goto err;
 564     *imprint_len = length;
 565     if ((*imprint = OPENSSL_malloc(*imprint_len)) == NULL) {
 566         TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
 567         goto err;
 568     }
 569
 570     md_ctx = EVP_MD_CTX_new();
 571     if (md_ctx == NULL) {
 572         TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
 573         goto err;
 574     }
 575     if (!EVP_DigestInit(md_ctx, md))
 576         goto err;
 577     while ((length = BIO_read(data, buffer, sizeof(buffer))) > 0) {
 578         if (!EVP_DigestUpdate(md_ctx, buffer, length))
 579             goto err;
 580     }
 581     if (!EVP_DigestFinal(md_ctx, *imprint, NULL))
 582         goto err;
 583     EVP_MD_CTX_free(md_ctx);
 584
 585     return 1;
 586  err:
 587     EVP_MD_CTX_free(md_ctx);
 588     X509_ALGOR_free(*md_alg);
 589     OPENSSL_free(*imprint);
 590     *imprint_len = 0;
 591     *imprint = 0;
 592     return 0;
 593 }
 594
 595 static int ts_check_imprints(X509_ALGOR *algor_a,
 596                              const unsigned char *imprint_a, unsigned len_a,
 597                              TS_TST_INFO *tst_info)
 598 {
 599     TS_MSG_IMPRINT *b = tst_info->msg_imprint;
 600     X509_ALGOR *algor_b = b->hash_algo;
 601     int ret = 0;
 602
 603     if (algor_a) {
 604         if (OBJ_cmp(algor_a->algorithm, algor_b->algorithm))
 605             goto err;
 606
 607         /* The parameter must be NULL in both. */
 608         if ((algor_a->parameter
 609              && ASN1_TYPE_get(algor_a->parameter) != V_ASN1_NULL)
 610             || (algor_b->parameter
 611                 && ASN1_TYPE_get(algor_b->parameter) != V_ASN1_NULL))
 612             goto err;
 613     }
 614
 615     ret = len_a == (unsigned)ASN1_STRING_length(b->hashed_msg) &&
 616         memcmp(imprint_a, ASN1_STRING_get0_data(b->hashed_msg), len_a) == 0;
 617  err:
 618     if (!ret)
 619         TSerr(TS_F_TS_CHECK_IMPRINTS, TS_R_MESSAGE_IMPRINT_MISMATCH);
 620     return ret;
 621 }
 622
 623 static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info)
 624 {
 625     const ASN1_INTEGER *b = tst_info->nonce;
 626
 627     if (!b) {
 628         TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_NOT_RETURNED);
 629         return 0;
 630     }
 631
 632     /* No error if a nonce is returned without being requested. */
 633     if (ASN1_INTEGER_cmp(a, b) != 0) {
 634         TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_MISMATCH);
 635         return 0;
 636     }
 637
 638     return 1;
 639 }
 640
 641 /*
 642  * Check if the specified TSA name matches either the subject or one of the
 643  * subject alternative names of the TSA certificate.
 644  */
 645 static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer)
 646 {
 647     STACK_OF(GENERAL_NAME) *gen_names = NULL;
 648     int idx = -1;
 649     int found = 0;
 650
 651     if (tsa_name->type == GEN_DIRNAME
 652         && X509_name_cmp(tsa_name->d.dirn, X509_get_subject_name(signer)) == 0)
 653         return 1;
 654     gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
 655     while (gen_names != NULL) {
 656         found = ts_find_name(gen_names, tsa_name) >= 0;
 657         if (found)
 658             break;
 659         /*
 660          * Get the next subject alternative name, although there should be no
 661          * more than one.
 662          */
 663         GENERAL_NAMES_free(gen_names);
 664         gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
 665     }
 666     GENERAL_NAMES_free(gen_names);
 667
 668     return found;
 669 }
 670
 671 /* Returns 1 if name is in gen_names, 0 otherwise. */
 672 static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names, GENERAL_NAME *name)
 673 {
 674     int i, found;
 675     for (i = 0, found = 0; !found && i < sk_GENERAL_NAME_num(gen_names); ++i) {
 676         GENERAL_NAME *current = sk_GENERAL_NAME_value(gen_names, i);
 677         found = GENERAL_NAME_cmp(current, name) == 0;
 678     }
 679     return found ? i - 1 : -1;
 680 }