crypto/ts/ts_rsp_verify.c

   1 /*
   2  * Copyright 2006-2020 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 <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_local.h"
  16
  17 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
  18                           X509 *signer, STACK_OF(X509) **chain);
  19 static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
  20                                   STACK_OF(X509) *chain);
  21 static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si);
  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 static ESS_SIGNING_CERT_V2 *ess_get_signing_cert_v2(PKCS7_SIGNER_INFO *si);
  42
  43 /*
  44  * This must be large enough to hold all values in ts_status_text (with
  45  * comma separator) or all text fields in ts_failure_info (also with comma).
  46  */
  47 #define TS_STATUS_BUF_SIZE      256
  48
  49 /*
  50  * Local mapping between response codes and descriptions.
  51  */
  52 static const char *ts_status_text[] = {
  53     "granted",
  54     "grantedWithMods",
  55     "rejection",
  56     "waiting",
  57     "revocationWarning",
  58     "revocationNotification"
  59 };
  60
  61 #define TS_STATUS_TEXT_SIZE     OSSL_NELEM(ts_status_text)
  62
  63 static struct {
  64     int code;
  65     const char *text;
  66 } ts_failure_info[] = {
  67     {TS_INFO_BAD_ALG, "badAlg"},
  68     {TS_INFO_BAD_REQUEST, "badRequest"},
  69     {TS_INFO_BAD_DATA_FORMAT, "badDataFormat"},
  70     {TS_INFO_TIME_NOT_AVAILABLE, "timeNotAvailable"},
  71     {TS_INFO_UNACCEPTED_POLICY, "unacceptedPolicy"},
  72     {TS_INFO_UNACCEPTED_EXTENSION, "unacceptedExtension"},
  73     {TS_INFO_ADD_INFO_NOT_AVAILABLE, "addInfoNotAvailable"},
  74     {TS_INFO_SYSTEM_FAILURE, "systemFailure"}
  75 };
  76
  77
  78 /*-
  79  * This function carries out the following tasks:
  80  *      - Checks if there is one and only one signer.
  81  *      - Search for the signing certificate in 'certs' and in the response.
  82  *      - Check the extended key usage and key usage fields of the signer
  83  *      certificate (done by the path validation).
  84  *      - Build and validate the certificate path.
  85  *      - Check if the certificate path meets the requirements of the
  86  *      SigningCertificate ESS signed attribute.
  87  *      - Verify the signature value.
  88  *      - Returns the signer certificate in 'signer', if 'signer' is not NULL.
  89  */
  90 int TS_RESP_verify_signature(PKCS7 *token, STACK_OF(X509) *certs,
  91                              X509_STORE *store, X509 **signer_out)
  92 {
  93     STACK_OF(PKCS7_SIGNER_INFO) *sinfos = NULL;
  94     PKCS7_SIGNER_INFO *si;
  95     STACK_OF(X509) *signers = NULL;
  96     X509 *signer;
  97     STACK_OF(X509) *chain = NULL;
  98     char buf[4096];
  99     int i, j = 0, ret = 0;
 100     BIO *p7bio = NULL;
 101
 102     /* Some sanity checks first. */
 103     if (!token) {
 104         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_INVALID_NULL_POINTER);
 105         goto err;
 106     }
 107     if (!PKCS7_type_is_signed(token)) {
 108         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_WRONG_CONTENT_TYPE);
 109         goto err;
 110     }
 111     sinfos = PKCS7_get_signer_info(token);
 112     if (!sinfos || sk_PKCS7_SIGNER_INFO_num(sinfos) != 1) {
 113         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_THERE_MUST_BE_ONE_SIGNER);
 114         goto err;
 115     }
 116     si = sk_PKCS7_SIGNER_INFO_value(sinfos, 0);
 117     if (PKCS7_get_detached(token)) {
 118         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_NO_CONTENT);
 119         goto err;
 120     }
 121
 122     /*
 123      * Get hold of the signer certificate, search only internal certificates
 124      * if it was requested.
 125      */
 126     signers = PKCS7_get0_signers(token, certs, 0);
 127     if (!signers || sk_X509_num(signers) != 1)
 128         goto err;
 129     signer = sk_X509_value(signers, 0);
 130
 131     if (!ts_verify_cert(store, certs, signer, &chain))
 132         goto err;
 133     if (!ts_check_signing_certs(si, chain))
 134         goto err;
 135     p7bio = PKCS7_dataInit(token, NULL);
 136
 137     /* We now have to 'read' from p7bio to calculate digests etc. */
 138     while ((i = BIO_read(p7bio, buf, sizeof(buf))) > 0)
 139         continue;
 140
 141     j = PKCS7_signatureVerify(p7bio, token, si, signer);
 142     if (j <= 0) {
 143         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_SIGNATURE_FAILURE);
 144         goto err;
 145     }
 146
 147     if (signer_out) {
 148         *signer_out = signer;
 149         X509_up_ref(signer);
 150     }
 151     ret = 1;
 152
 153  err:
 154     BIO_free_all(p7bio);
 155     sk_X509_pop_free(chain, X509_free);
 156     sk_X509_free(signers);
 157
 158     return ret;
 159 }
 160
 161 /*
 162  * The certificate chain is returned in chain. Caller is responsible for
 163  * freeing the vector.
 164  */
 165 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
 166                           X509 *signer, STACK_OF(X509) **chain)
 167 {
 168     X509_STORE_CTX *cert_ctx = NULL;
 169     int i;
 170     int ret = 0;
 171
 172     *chain = NULL;
 173     cert_ctx = X509_STORE_CTX_new();
 174     if (cert_ctx == NULL) {
 175         TSerr(TS_F_TS_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
 176         goto err;
 177     }
 178     if (!X509_STORE_CTX_init(cert_ctx, store, signer, untrusted))
 179         goto end;
 180     X509_STORE_CTX_set_purpose(cert_ctx, X509_PURPOSE_TIMESTAMP_SIGN);
 181     i = X509_verify_cert(cert_ctx);
 182     if (i <= 0) {
 183         int j = X509_STORE_CTX_get_error(cert_ctx);
 184         TSerr(TS_F_TS_VERIFY_CERT, TS_R_CERTIFICATE_VERIFY_ERROR);
 185         ERR_add_error_data(2, "Verify error:",
 186                            X509_verify_cert_error_string(j));
 187         goto err;
 188     }
 189     *chain = X509_STORE_CTX_get1_chain(cert_ctx);
 190     ret = 1;
 191     goto end;
 192
 193 err:
 194     ret = 0;
 195
 196 end:
 197     X509_STORE_CTX_free(cert_ctx);
 198     return ret;
 199 }
 200
 201 static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
 202                                   STACK_OF(X509) *chain)
 203 {
 204     ESS_SIGNING_CERT *ss = ess_get_signing_cert(si);
 205     STACK_OF(ESS_CERT_ID) *cert_ids = NULL;
 206     ESS_SIGNING_CERT_V2 *ssv2 = ess_get_signing_cert_v2(si);
 207     STACK_OF(ESS_CERT_ID_V2) *cert_ids_v2 = NULL;
 208     X509 *cert;
 209     int i = 0;
 210     int ret = 0;
 211
 212     if (ss != NULL) {
 213         cert_ids = ss->cert_ids;
 214         cert = sk_X509_value(chain, 0);
 215         if (ts_find_cert(cert_ids, cert) != 0)
 216             goto err;
 217
 218         /*
 219          * Check the other certificates of the chain if there are more than one
 220          * certificate ids in cert_ids.
 221          */
 222         if (sk_ESS_CERT_ID_num(cert_ids) > 1) {
 223             for (i = 1; i < sk_X509_num(chain); ++i) {
 224                 cert = sk_X509_value(chain, i);
 225                 if (ts_find_cert(cert_ids, cert) < 0)
 226                     goto err;
 227             }
 228         }
 229     } else if (ssv2 != NULL) {
 230         cert_ids_v2 = ssv2->cert_ids;
 231         cert = sk_X509_value(chain, 0);
 232         if (ts_find_cert_v2(cert_ids_v2, cert) != 0)
 233             goto err;
 234
 235         /*
 236          * Check the other certificates of the chain if there are more than one
 237          * certificate ids in cert_ids.
 238          */
 239         if (sk_ESS_CERT_ID_V2_num(cert_ids_v2) > 1) {
 240             for (i = 1; i < sk_X509_num(chain); ++i) {
 241                 cert = sk_X509_value(chain, i);
 242                 if (ts_find_cert_v2(cert_ids_v2, cert) < 0)
 243                     goto err;
 244             }
 245         }
 246     } else {
 247         goto err;
 248     }
 249
 250     ret = 1;
 251  err:
 252     if (!ret)
 253         TSerr(TS_F_TS_CHECK_SIGNING_CERTS,
 254               TS_R_ESS_SIGNING_CERTIFICATE_ERROR);
 255     ESS_SIGNING_CERT_free(ss);
 256     ESS_SIGNING_CERT_V2_free(ssv2);
 257     return ret;
 258 }
 259
 260 static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si)
 261 {
 262     ASN1_TYPE *attr;
 263     const unsigned char *p;
 264     attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificate);
 265     if (!attr)
 266         return NULL;
 267     p = attr->value.sequence->data;
 268     return d2i_ESS_SIGNING_CERT(NULL, &p, attr->value.sequence->length);
 269 }
 270
 271 static ESS_SIGNING_CERT_V2 *ess_get_signing_cert_v2(PKCS7_SIGNER_INFO *si)
 272 {
 273     ASN1_TYPE *attr;
 274     const unsigned char *p;
 275
 276     attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificateV2);
 277     if (attr == NULL)
 278         return NULL;
 279     p = attr->value.sequence->data;
 280     return d2i_ESS_SIGNING_CERT_V2(NULL, &p, attr->value.sequence->length);
 281 }
 282
 283 /* Returns < 0 if certificate is not found, certificate index otherwise. */
 284 static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert)
 285 {
 286     int i;
 287     unsigned char cert_sha1[SHA_DIGEST_LENGTH];
 288
 289     if (!cert_ids || !cert)
 290         return -1;
 291
 292     /* Recompute SHA1 hash of certificate if necessary (side effect). */
 293     X509_check_purpose(cert, -1, 0);
 294
 295     if (!X509_digest(cert, EVP_sha1(), cert_sha1, NULL))
 296         return -1;
 297
 298     /* Look for cert in the cert_ids vector. */
 299     for (i = 0; i < sk_ESS_CERT_ID_num(cert_ids); ++i) {
 300         ESS_CERT_ID *cid = sk_ESS_CERT_ID_value(cert_ids, i);
 301
 302         if (cid->hash->length == SHA_DIGEST_LENGTH
 303             && memcmp(cid->hash->data, cert_sha1, SHA_DIGEST_LENGTH) == 0) {
 304             ESS_ISSUER_SERIAL *is = cid->issuer_serial;
 305             if (!is || !ts_issuer_serial_cmp(is, cert))
 306                 return i;
 307         }
 308     }
 309
 310     return -1;
 311 }
 312
 313 /* Returns < 0 if certificate is not found, certificate index otherwise. */
 314 static int ts_find_cert_v2(STACK_OF(ESS_CERT_ID_V2) *cert_ids, X509 *cert)
 315 {
 316     int i;
 317     unsigned char cert_digest[EVP_MAX_MD_SIZE];
 318     unsigned int len;
 319
 320     /* Look for cert in the cert_ids vector. */
 321     for (i = 0; i < sk_ESS_CERT_ID_V2_num(cert_ids); ++i) {
 322         ESS_CERT_ID_V2 *cid = sk_ESS_CERT_ID_V2_value(cert_ids, i);
 323         const EVP_MD *md;
 324
 325         if (cid->hash_alg != NULL)
 326             md = EVP_get_digestbyobj(cid->hash_alg->algorithm);
 327         else
 328             md = EVP_sha256();
 329
 330         if (!X509_digest(cert, md, cert_digest, &len))
 331             return -1;
 332         if (cid->hash->length != (int)len)
 333             return -1;
 334
 335         if (memcmp(cid->hash->data, cert_digest, cid->hash->length) == 0) {
 336             ESS_ISSUER_SERIAL *is = cid->issuer_serial;
 337
 338             if (is == NULL || !ts_issuer_serial_cmp(is, cert))
 339                 return i;
 340         }
 341     }
 342
 343     return -1;
 344 }
 345
 346 static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert)
 347 {
 348     GENERAL_NAME *issuer;
 349
 350     if (!is || !cert || sk_GENERAL_NAME_num(is->issuer) != 1)
 351         return -1;
 352
 353     issuer = sk_GENERAL_NAME_value(is->issuer, 0);
 354     if (issuer->type != GEN_DIRNAME
 355         || X509_NAME_cmp(issuer->d.dirn, X509_get_issuer_name(cert)))
 356         return -1;
 357
 358     if (ASN1_INTEGER_cmp(is->serial, X509_get_serialNumber(cert)))
 359         return -1;
 360
 361     return 0;
 362 }
 363
 364 /*-
 365  * Verifies whether 'response' contains a valid response with regards
 366  * to the settings of the context:
 367  *      - Gives an error message if the TS_TST_INFO is not present.
 368  *      - Calls _TS_RESP_verify_token to verify the token content.
 369  */
 370 int TS_RESP_verify_response(TS_VERIFY_CTX *ctx, TS_RESP *response)
 371 {
 372     PKCS7 *token = response->token;
 373     TS_TST_INFO *tst_info = response->tst_info;
 374     int ret = 0;
 375
 376     if (!ts_check_status_info(response))
 377         goto err;
 378     if (!int_ts_RESP_verify_token(ctx, token, tst_info))
 379         goto err;
 380     ret = 1;
 381
 382  err:
 383     return ret;
 384 }
 385
 386 /*
 387  * Tries to extract a TS_TST_INFO structure from the PKCS7 token and
 388  * calls the internal int_TS_RESP_verify_token function for verifying it.
 389  */
 390 int TS_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token)
 391 {
 392     TS_TST_INFO *tst_info = PKCS7_to_TS_TST_INFO(token);
 393     int ret = 0;
 394     if (tst_info) {
 395         ret = int_ts_RESP_verify_token(ctx, token, tst_info);
 396         TS_TST_INFO_free(tst_info);
 397     }
 398     return ret;
 399 }
 400
 401 /*-
 402  * Verifies whether the 'token' contains a valid time stamp token
 403  * with regards to the settings of the context. Only those checks are
 404  * carried out that are specified in the context:
 405  *      - Verifies the signature of the TS_TST_INFO.
 406  *      - Checks the version number of the response.
 407  *      - Check if the requested and returned policies math.
 408  *      - Check if the message imprints are the same.
 409  *      - Check if the nonces are the same.
 410  *      - Check if the TSA name matches the signer.
 411  *      - Check if the TSA name is the expected TSA.
 412  */
 413 static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
 414                                     PKCS7 *token, TS_TST_INFO *tst_info)
 415 {
 416     X509 *signer = NULL;
 417     GENERAL_NAME *tsa_name = tst_info->tsa;
 418     X509_ALGOR *md_alg = NULL;
 419     unsigned char *imprint = NULL;
 420     unsigned imprint_len = 0;
 421     int ret = 0;
 422     int flags = ctx->flags;
 423
 424     /* Some options require us to also check the signature */
 425     if (((flags & TS_VFY_SIGNER) && tsa_name != NULL)
 426             || (flags & TS_VFY_TSA_NAME)) {
 427         flags |= TS_VFY_SIGNATURE;
 428     }
 429
 430     if ((flags & TS_VFY_SIGNATURE)
 431         && !TS_RESP_verify_signature(token, ctx->certs, ctx->store, &signer))
 432         goto err;
 433     if ((flags & TS_VFY_VERSION)
 434         && TS_TST_INFO_get_version(tst_info) != 1) {
 435         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_UNSUPPORTED_VERSION);
 436         goto err;
 437     }
 438     if ((flags & TS_VFY_POLICY)
 439         && !ts_check_policy(ctx->policy, tst_info))
 440         goto err;
 441     if ((flags & TS_VFY_IMPRINT)
 442         && !ts_check_imprints(ctx->md_alg, ctx->imprint, ctx->imprint_len,
 443                               tst_info))
 444         goto err;
 445     if ((flags & TS_VFY_DATA)
 446         && (!ts_compute_imprint(ctx->data, tst_info,
 447                                 &md_alg, &imprint, &imprint_len)
 448             || !ts_check_imprints(md_alg, imprint, imprint_len, tst_info)))
 449         goto err;
 450     if ((flags & TS_VFY_NONCE)
 451         && !ts_check_nonces(ctx->nonce, tst_info))
 452         goto err;
 453     if ((flags & TS_VFY_SIGNER)
 454         && tsa_name && !ts_check_signer_name(tsa_name, signer)) {
 455         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_NAME_MISMATCH);
 456         goto err;
 457     }
 458     if ((flags & TS_VFY_TSA_NAME)
 459         && !ts_check_signer_name(ctx->tsa_name, signer)) {
 460         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_UNTRUSTED);
 461         goto err;
 462     }
 463     ret = 1;
 464
 465  err:
 466     X509_free(signer);
 467     X509_ALGOR_free(md_alg);
 468     OPENSSL_free(imprint);
 469     return ret;
 470 }
 471
 472 static int ts_check_status_info(TS_RESP *response)
 473 {
 474     TS_STATUS_INFO *info = response->status_info;
 475     long status = ASN1_INTEGER_get(info->status);
 476     const char *status_text = NULL;
 477     char *embedded_status_text = NULL;
 478     char failure_text[TS_STATUS_BUF_SIZE] = "";
 479
 480     if (status == 0 || status == 1)
 481         return 1;
 482
 483     /* There was an error, get the description in status_text. */
 484     if (0 <= status && status < (long) OSSL_NELEM(ts_status_text))
 485         status_text = ts_status_text[status];
 486     else
 487         status_text = "unknown code";
 488
 489     if (sk_ASN1_UTF8STRING_num(info->text) > 0
 490         && (embedded_status_text = ts_get_status_text(info->text)) == NULL)
 491         return 0;
 492
 493     /* Fill in failure_text with the failure information. */
 494     if (info->failure_info) {
 495         int i;
 496         int first = 1;
 497         for (i = 0; i < (int)OSSL_NELEM(ts_failure_info); ++i) {
 498             if (ASN1_BIT_STRING_get_bit(info->failure_info,
 499                                         ts_failure_info[i].code)) {
 500                 if (!first)
 501                     strcat(failure_text, ",");
 502                 else
 503                     first = 0;
 504                 strcat(failure_text, ts_failure_info[i].text);
 505             }
 506         }
 507     }
 508     if (failure_text[0] == '\0')
 509         strcpy(failure_text, "unspecified");
 510
 511     TSerr(TS_F_TS_CHECK_STATUS_INFO, TS_R_NO_TIME_STAMP_TOKEN);
 512     ERR_add_error_data(6,
 513                        "status code: ", status_text,
 514                        ", status text: ", embedded_status_text ?
 515                        embedded_status_text : "unspecified",
 516                        ", failure codes: ", failure_text);
 517     OPENSSL_free(embedded_status_text);
 518
 519     return 0;
 520 }
 521
 522 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text)
 523 {
 524     int i;
 525     int length = 0;
 526     char *result = NULL;
 527     char *p;
 528
 529     for (i = 0; i < sk_ASN1_UTF8STRING_num(text); ++i) {
 530         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
 531         if (ASN1_STRING_length(current) > TS_MAX_STATUS_LENGTH - length - 1)
 532             return NULL;
 533         length += ASN1_STRING_length(current);
 534         length += 1;            /* separator character */
 535     }
 536     if ((result = OPENSSL_malloc(length)) == NULL) {
 537         TSerr(TS_F_TS_GET_STATUS_TEXT, ERR_R_MALLOC_FAILURE);
 538         return NULL;
 539     }
 540
 541     for (i = 0, p = result; i < sk_ASN1_UTF8STRING_num(text); ++i) {
 542         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
 543         length = ASN1_STRING_length(current);
 544         if (i > 0)
 545             *p++ = '/';
 546         strncpy(p, (const char *)ASN1_STRING_get0_data(current), length);
 547         p += length;
 548     }
 549     *p = '\0';
 550
 551     return result;
 552 }
 553
 554 static int ts_check_policy(const ASN1_OBJECT *req_oid,
 555                            const TS_TST_INFO *tst_info)
 556 {
 557     const ASN1_OBJECT *resp_oid = tst_info->policy_id;
 558
 559     if (OBJ_cmp(req_oid, resp_oid) != 0) {
 560         TSerr(TS_F_TS_CHECK_POLICY, TS_R_POLICY_MISMATCH);
 561         return 0;
 562     }
 563
 564     return 1;
 565 }
 566
 567 static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
 568                               X509_ALGOR **md_alg,
 569                               unsigned char **imprint, unsigned *imprint_len)
 570 {
 571     TS_MSG_IMPRINT *msg_imprint = tst_info->msg_imprint;
 572     X509_ALGOR *md_alg_resp = msg_imprint->hash_algo;
 573     const EVP_MD *md;
 574     EVP_MD_CTX *md_ctx = NULL;
 575     unsigned char buffer[4096];
 576     int length;
 577
 578     *md_alg = NULL;
 579     *imprint = NULL;
 580
 581     if ((*md_alg = X509_ALGOR_dup(md_alg_resp)) == NULL)
 582         goto err;
 583     if ((md = EVP_get_digestbyobj((*md_alg)->algorithm)) == NULL) {
 584         TSerr(TS_F_TS_COMPUTE_IMPRINT, TS_R_UNSUPPORTED_MD_ALGORITHM);
 585         goto err;
 586     }
 587     length = EVP_MD_size(md);
 588     if (length < 0)
 589         goto err;
 590     *imprint_len = length;
 591     if ((*imprint = OPENSSL_malloc(*imprint_len)) == NULL) {
 592         TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
 593         goto err;
 594     }
 595
 596     md_ctx = EVP_MD_CTX_new();
 597     if (md_ctx == NULL) {
 598         TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
 599         goto err;
 600     }
 601     if (!EVP_DigestInit(md_ctx, md))
 602         goto err;
 603     while ((length = BIO_read(data, buffer, sizeof(buffer))) > 0) {
 604         if (!EVP_DigestUpdate(md_ctx, buffer, length))
 605             goto err;
 606     }
 607     if (!EVP_DigestFinal(md_ctx, *imprint, NULL))
 608         goto err;
 609     EVP_MD_CTX_free(md_ctx);
 610
 611     return 1;
 612  err:
 613     EVP_MD_CTX_free(md_ctx);
 614     X509_ALGOR_free(*md_alg);
 615     OPENSSL_free(*imprint);
 616     *imprint_len = 0;
 617     *imprint = 0;
 618     return 0;
 619 }
 620
 621 static int ts_check_imprints(X509_ALGOR *algor_a,
 622                              const unsigned char *imprint_a, unsigned len_a,
 623                              TS_TST_INFO *tst_info)
 624 {
 625     TS_MSG_IMPRINT *b = tst_info->msg_imprint;
 626     X509_ALGOR *algor_b = b->hash_algo;
 627     int ret = 0;
 628
 629     if (algor_a) {
 630         if (OBJ_cmp(algor_a->algorithm, algor_b->algorithm))
 631             goto err;
 632
 633         /* The parameter must be NULL in both. */
 634         if ((algor_a->parameter
 635              && ASN1_TYPE_get(algor_a->parameter) != V_ASN1_NULL)
 636             || (algor_b->parameter
 637                 && ASN1_TYPE_get(algor_b->parameter) != V_ASN1_NULL))
 638             goto err;
 639     }
 640
 641     ret = len_a == (unsigned)ASN1_STRING_length(b->hashed_msg) &&
 642         memcmp(imprint_a, ASN1_STRING_get0_data(b->hashed_msg), len_a) == 0;
 643  err:
 644     if (!ret)
 645         TSerr(TS_F_TS_CHECK_IMPRINTS, TS_R_MESSAGE_IMPRINT_MISMATCH);
 646     return ret;
 647 }
 648
 649 static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info)
 650 {
 651     const ASN1_INTEGER *b = tst_info->nonce;
 652
 653     if (!b) {
 654         TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_NOT_RETURNED);
 655         return 0;
 656     }
 657
 658     /* No error if a nonce is returned without being requested. */
 659     if (ASN1_INTEGER_cmp(a, b) != 0) {
 660         TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_MISMATCH);
 661         return 0;
 662     }
 663
 664     return 1;
 665 }
 666
 667 /*
 668  * Check if the specified TSA name matches either the subject or one of the
 669  * subject alternative names of the TSA certificate.
 670  */
 671 static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer)
 672 {
 673     STACK_OF(GENERAL_NAME) *gen_names = NULL;
 674     int idx = -1;
 675     int found = 0;
 676
 677     if (tsa_name->type == GEN_DIRNAME
 678         && X509_name_cmp(tsa_name->d.dirn, X509_get_subject_name(signer)) == 0)
 679         return 1;
 680     gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
 681     while (gen_names != NULL) {
 682         found = ts_find_name(gen_names, tsa_name) >= 0;
 683         if (found)
 684             break;
 685         /*
 686          * Get the next subject alternative name, although there should be no
 687          * more than one.
 688          */
 689         GENERAL_NAMES_free(gen_names);
 690         gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
 691     }
 692     GENERAL_NAMES_free(gen_names);
 693
 694     return found;
 695 }
 696
 697 /* Returns 1 if name is in gen_names, 0 otherwise. */
 698 static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names, GENERAL_NAME *name)
 699 {
 700     int i, found;
 701     for (i = 0, found = 0; !found && i < sk_GENERAL_NAME_num(gen_names); ++i) {
 702         GENERAL_NAME *current = sk_GENERAL_NAME_value(gen_names, i);
 703         found = GENERAL_NAME_cmp(current, name) == 0;
 704     }
 705     return found ? i - 1 : -1;
 706 }