1 /* 2 * Copyright 2006-2021 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 <openssl/objects.h> 12 #include <openssl/ts.h> 13 #include <openssl/pkcs7.h> 14 #include "internal/cryptlib.h" 15 #include "internal/sizes.h" 16 #include "crypto/ess.h" 17 #include "ts_local.h" 18 19 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted, 20 X509 *signer, STACK_OF(X509) **chain); 21 static int ts_check_signing_certs(const PKCS7_SIGNER_INFO *si, 22 const STACK_OF(X509) *chain); 23 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 41 /* 42 * This must be large enough to hold all values in ts_status_text (with 43 * comma separator) or all text fields in ts_failure_info (also with comma). 44 */ 45 #define TS_STATUS_BUF_SIZE 256 46 47 /* 48 * Local mapping between response codes and descriptions. 49 */ 50 static const char *ts_status_text[] = { 51 "granted", 52 "grantedWithMods", 53 "rejection", 54 "waiting", 55 "revocationWarning", 56 "revocationNotification" 57 }; 58 59 #define TS_STATUS_TEXT_SIZE OSSL_NELEM(ts_status_text) 60 61 static struct { 62 int code; 63 const char *text; 64 } ts_failure_info[] = { 65 {TS_INFO_BAD_ALG, "badAlg"}, 66 {TS_INFO_BAD_REQUEST, "badRequest"}, 67 {TS_INFO_BAD_DATA_FORMAT, "badDataFormat"}, 68 {TS_INFO_TIME_NOT_AVAILABLE, "timeNotAvailable"}, 69 {TS_INFO_UNACCEPTED_POLICY, "unacceptedPolicy"}, 70 {TS_INFO_UNACCEPTED_EXTENSION, "unacceptedExtension"}, 71 {TS_INFO_ADD_INFO_NOT_AVAILABLE, "addInfoNotAvailable"}, 72 {TS_INFO_SYSTEM_FAILURE, "systemFailure"} 73 }; 74 75 76 /*- 77 * This function carries out the following tasks: 78 * - Checks if there is one and only one signer. 79 * - Search for the signing certificate in 'certs' and in the response. 80 * - Check the extended key usage and key usage fields of the signer 81 * certificate (done by the path validation). 82 * - Build and validate the certificate path. 83 * - Check if the certificate path meets the requirements of the 84 * SigningCertificate ESS signed attribute. 85 * - Verify the signature value. 86 * - Returns the signer certificate in 'signer', if 'signer' is not NULL. 87 */ 88 int TS_RESP_verify_signature(PKCS7 *token, STACK_OF(X509) *certs, 89 X509_STORE *store, X509 **signer_out) 90 { 91 STACK_OF(PKCS7_SIGNER_INFO) *sinfos = NULL; 92 PKCS7_SIGNER_INFO *si; 93 STACK_OF(X509) *untrusted = NULL; 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 ERR_raise(ERR_LIB_TS, TS_R_INVALID_NULL_POINTER); 104 goto err; 105 } 106 if (!PKCS7_type_is_signed(token)) { 107 ERR_raise(ERR_LIB_TS, 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 ERR_raise(ERR_LIB_TS, 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 ERR_raise(ERR_LIB_TS, 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 untrusted = sk_X509_new_reserve(NULL, sk_X509_num(certs) 131 + sk_X509_num(token->d.sign->cert)); 132 if (untrusted == NULL 133 || !X509_add_certs(untrusted, certs, 0) 134 || !X509_add_certs(untrusted, token->d.sign->cert, 0)) 135 goto err; 136 if (!ts_verify_cert(store, untrusted, signer, &chain)) 137 goto err; 138 if (!ts_check_signing_certs(si, chain)) 139 goto err; 140 p7bio = PKCS7_dataInit(token, NULL); 141 142 /* We now have to 'read' from p7bio to calculate digests etc. */ 143 while ((i = BIO_read(p7bio, buf, sizeof(buf))) > 0) 144 continue; 145 146 j = PKCS7_signatureVerify(p7bio, token, si, signer); 147 if (j <= 0) { 148 ERR_raise(ERR_LIB_TS, TS_R_SIGNATURE_FAILURE); 149 goto err; 150 } 151 152 if (signer_out) { 153 *signer_out = signer; 154 X509_up_ref(signer); 155 } 156 ret = 1; 157 158 err: 159 BIO_free_all(p7bio); 160 sk_X509_free(untrusted); 161 sk_X509_pop_free(chain, X509_free); 162 sk_X509_free(signers); 163 164 return ret; 165 } 166 167 /* 168 * The certificate chain is returned in chain. Caller is responsible for 169 * freeing the vector. 170 */ 171 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted, 172 X509 *signer, STACK_OF(X509) **chain) 173 { 174 X509_STORE_CTX *cert_ctx = NULL; 175 int i; 176 int ret = 0; 177 178 *chain = NULL; 179 cert_ctx = X509_STORE_CTX_new(); 180 if (cert_ctx == NULL) { 181 ERR_raise(ERR_LIB_TS, ERR_R_MALLOC_FAILURE); 182 goto err; 183 } 184 if (!X509_STORE_CTX_init(cert_ctx, store, signer, untrusted)) 185 goto end; 186 X509_STORE_CTX_set_purpose(cert_ctx, X509_PURPOSE_TIMESTAMP_SIGN); 187 i = X509_verify_cert(cert_ctx); 188 if (i <= 0) { 189 int j = X509_STORE_CTX_get_error(cert_ctx); 190 ERR_raise_data(ERR_LIB_TS, TS_R_CERTIFICATE_VERIFY_ERROR, 191 "Verify error:%s", X509_verify_cert_error_string(j)); 192 goto err; 193 } 194 *chain = X509_STORE_CTX_get1_chain(cert_ctx); 195 ret = 1; 196 goto end; 197 198 err: 199 ret = 0; 200 201 end: 202 X509_STORE_CTX_free(cert_ctx); 203 return ret; 204 } 205 206 static ESS_SIGNING_CERT *ossl_ess_get_signing_cert(const PKCS7_SIGNER_INFO *si) 207 { 208 ASN1_TYPE *attr; 209 const unsigned char *p; 210 211 attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificate); 212 if (attr == NULL) 213 return NULL; 214 p = attr->value.sequence->data; 215 return d2i_ESS_SIGNING_CERT(NULL, &p, attr->value.sequence->length); 216 } 217 218 static 219 ESS_SIGNING_CERT_V2 *ossl_ess_get_signing_cert_v2(const PKCS7_SIGNER_INFO *si) 220 { 221 ASN1_TYPE *attr; 222 const unsigned char *p; 223 224 attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificateV2); 225 if (attr == NULL) 226 return NULL; 227 p = attr->value.sequence->data; 228 return d2i_ESS_SIGNING_CERT_V2(NULL, &p, attr->value.sequence->length); 229 } 230 231 static int ts_check_signing_certs(const PKCS7_SIGNER_INFO *si, 232 const STACK_OF(X509) *chain) 233 { 234 ESS_SIGNING_CERT *ss = ossl_ess_get_signing_cert(si); 235 ESS_SIGNING_CERT_V2 *ssv2 = ossl_ess_get_signing_cert_v2(si); 236 int ret = OSSL_ESS_check_signing_certs(ss, ssv2, chain, 1) > 0; 237 238 ESS_SIGNING_CERT_free(ss); 239 ESS_SIGNING_CERT_V2_free(ssv2); 240 return ret; 241 } 242 243 /*- 244 * Verifies whether 'response' contains a valid response with regards 245 * to the settings of the context: 246 * - Gives an error message if the TS_TST_INFO is not present. 247 * - Calls _TS_RESP_verify_token to verify the token content. 248 */ 249 int TS_RESP_verify_response(TS_VERIFY_CTX *ctx, TS_RESP *response) 250 { 251 PKCS7 *token = response->token; 252 TS_TST_INFO *tst_info = response->tst_info; 253 int ret = 0; 254 255 if (!ts_check_status_info(response)) 256 goto err; 257 if (!int_ts_RESP_verify_token(ctx, token, tst_info)) 258 goto err; 259 ret = 1; 260 261 err: 262 return ret; 263 } 264 265 /* 266 * Tries to extract a TS_TST_INFO structure from the PKCS7 token and 267 * calls the internal int_TS_RESP_verify_token function for verifying it. 268 */ 269 int TS_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token) 270 { 271 TS_TST_INFO *tst_info = PKCS7_to_TS_TST_INFO(token); 272 int ret = 0; 273 if (tst_info) { 274 ret = int_ts_RESP_verify_token(ctx, token, tst_info); 275 TS_TST_INFO_free(tst_info); 276 } 277 return ret; 278 } 279 280 /*- 281 * Verifies whether the 'token' contains a valid time stamp token 282 * with regards to the settings of the context. Only those checks are 283 * carried out that are specified in the context: 284 * - Verifies the signature of the TS_TST_INFO. 285 * - Checks the version number of the response. 286 * - Check if the requested and returned policies math. 287 * - Check if the message imprints are the same. 288 * - Check if the nonces are the same. 289 * - Check if the TSA name matches the signer. 290 * - Check if the TSA name is the expected TSA. 291 */ 292 static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx, 293 PKCS7 *token, TS_TST_INFO *tst_info) 294 { 295 X509 *signer = NULL; 296 GENERAL_NAME *tsa_name = tst_info->tsa; 297 X509_ALGOR *md_alg = NULL; 298 unsigned char *imprint = NULL; 299 unsigned imprint_len = 0; 300 int ret = 0; 301 int flags = ctx->flags; 302 303 /* Some options require us to also check the signature */ 304 if (((flags & TS_VFY_SIGNER) && tsa_name != NULL) 305 || (flags & TS_VFY_TSA_NAME)) { 306 flags |= TS_VFY_SIGNATURE; 307 } 308 309 if ((flags & TS_VFY_SIGNATURE) 310 && !TS_RESP_verify_signature(token, ctx->certs, ctx->store, &signer)) 311 goto err; 312 if ((flags & TS_VFY_VERSION) 313 && TS_TST_INFO_get_version(tst_info) != 1) { 314 ERR_raise(ERR_LIB_TS, TS_R_UNSUPPORTED_VERSION); 315 goto err; 316 } 317 if ((flags & TS_VFY_POLICY) 318 && !ts_check_policy(ctx->policy, tst_info)) 319 goto err; 320 if ((flags & TS_VFY_IMPRINT) 321 && !ts_check_imprints(ctx->md_alg, ctx->imprint, ctx->imprint_len, 322 tst_info)) 323 goto err; 324 if ((flags & TS_VFY_DATA) 325 && (!ts_compute_imprint(ctx->data, tst_info, 326 &md_alg, &imprint, &imprint_len) 327 || !ts_check_imprints(md_alg, imprint, imprint_len, tst_info))) 328 goto err; 329 if ((flags & TS_VFY_NONCE) 330 && !ts_check_nonces(ctx->nonce, tst_info)) 331 goto err; 332 if ((flags & TS_VFY_SIGNER) 333 && tsa_name && !ts_check_signer_name(tsa_name, signer)) { 334 ERR_raise(ERR_LIB_TS, TS_R_TSA_NAME_MISMATCH); 335 goto err; 336 } 337 if ((flags & TS_VFY_TSA_NAME) 338 && !ts_check_signer_name(ctx->tsa_name, signer)) { 339 ERR_raise(ERR_LIB_TS, TS_R_TSA_UNTRUSTED); 340 goto err; 341 } 342 ret = 1; 343 344 err: 345 X509_free(signer); 346 X509_ALGOR_free(md_alg); 347 OPENSSL_free(imprint); 348 return ret; 349 } 350 351 static int ts_check_status_info(TS_RESP *response) 352 { 353 TS_STATUS_INFO *info = response->status_info; 354 long status = ASN1_INTEGER_get(info->status); 355 const char *status_text = NULL; 356 char *embedded_status_text = NULL; 357 char failure_text[TS_STATUS_BUF_SIZE] = ""; 358 359 if (status == 0 || status == 1) 360 return 1; 361 362 /* There was an error, get the description in status_text. */ 363 if (0 <= status && status < (long) OSSL_NELEM(ts_status_text)) 364 status_text = ts_status_text[status]; 365 else 366 status_text = "unknown code"; 367 368 if (sk_ASN1_UTF8STRING_num(info->text) > 0 369 && (embedded_status_text = ts_get_status_text(info->text)) == NULL) 370 return 0; 371 372 /* Fill in failure_text with the failure information. */ 373 if (info->failure_info) { 374 int i; 375 int first = 1; 376 for (i = 0; i < (int)OSSL_NELEM(ts_failure_info); ++i) { 377 if (ASN1_BIT_STRING_get_bit(info->failure_info, 378 ts_failure_info[i].code)) { 379 if (!first) 380 strcat(failure_text, ","); 381 else 382 first = 0; 383 strcat(failure_text, ts_failure_info[i].text); 384 } 385 } 386 } 387 if (failure_text[0] == '\0') 388 strcpy(failure_text, "unspecified"); 389 390 ERR_raise_data(ERR_LIB_TS, TS_R_NO_TIME_STAMP_TOKEN, 391 "status code: %s, status text: %s, failure codes: %s", 392 status_text, 393 embedded_status_text ? embedded_status_text : "unspecified", 394 failure_text); 395 OPENSSL_free(embedded_status_text); 396 397 return 0; 398 } 399 400 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text) 401 { 402 return ossl_sk_ASN1_UTF8STRING2text(text, "/", TS_MAX_STATUS_LENGTH); 403 } 404 405 static int ts_check_policy(const ASN1_OBJECT *req_oid, 406 const TS_TST_INFO *tst_info) 407 { 408 const ASN1_OBJECT *resp_oid = tst_info->policy_id; 409 410 if (OBJ_cmp(req_oid, resp_oid) != 0) { 411 ERR_raise(ERR_LIB_TS, TS_R_POLICY_MISMATCH); 412 return 0; 413 } 414 415 return 1; 416 } 417 418 static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info, 419 X509_ALGOR **md_alg, 420 unsigned char **imprint, unsigned *imprint_len) 421 { 422 TS_MSG_IMPRINT *msg_imprint = tst_info->msg_imprint; 423 X509_ALGOR *md_alg_resp = msg_imprint->hash_algo; 424 EVP_MD *md = NULL; 425 EVP_MD_CTX *md_ctx = NULL; 426 unsigned char buffer[4096]; 427 char name[OSSL_MAX_NAME_SIZE]; 428 int length; 429 430 *md_alg = NULL; 431 *imprint = NULL; 432 433 if ((*md_alg = X509_ALGOR_dup(md_alg_resp)) == NULL) 434 goto err; 435 436 OBJ_obj2txt(name, sizeof(name), md_alg_resp->algorithm, 0); 437 438 (void)ERR_set_mark(); 439 md = EVP_MD_fetch(NULL, name, NULL); 440 441 if (md == NULL) 442 md = (EVP_MD *)EVP_get_digestbyname(name); 443 444 if (md == NULL) { 445 (void)ERR_clear_last_mark(); 446 goto err; 447 } 448 (void)ERR_pop_to_mark(); 449 450 length = EVP_MD_get_size(md); 451 if (length < 0) 452 goto err; 453 *imprint_len = length; 454 if ((*imprint = OPENSSL_malloc(*imprint_len)) == NULL) { 455 ERR_raise(ERR_LIB_TS, ERR_R_MALLOC_FAILURE); 456 goto err; 457 } 458 459 md_ctx = EVP_MD_CTX_new(); 460 if (md_ctx == NULL) { 461 ERR_raise(ERR_LIB_TS, ERR_R_MALLOC_FAILURE); 462 goto err; 463 } 464 if (!EVP_DigestInit(md_ctx, md)) 465 goto err; 466 EVP_MD_free(md); 467 md = NULL; 468 while ((length = BIO_read(data, buffer, sizeof(buffer))) > 0) { 469 if (!EVP_DigestUpdate(md_ctx, buffer, length)) 470 goto err; 471 } 472 if (!EVP_DigestFinal(md_ctx, *imprint, NULL)) 473 goto err; 474 EVP_MD_CTX_free(md_ctx); 475 476 return 1; 477 err: 478 EVP_MD_CTX_free(md_ctx); 479 EVP_MD_free(md); 480 X509_ALGOR_free(*md_alg); 481 *md_alg = NULL; 482 OPENSSL_free(*imprint); 483 *imprint_len = 0; 484 *imprint = 0; 485 return 0; 486 } 487 488 static int ts_check_imprints(X509_ALGOR *algor_a, 489 const unsigned char *imprint_a, unsigned len_a, 490 TS_TST_INFO *tst_info) 491 { 492 TS_MSG_IMPRINT *b = tst_info->msg_imprint; 493 X509_ALGOR *algor_b = b->hash_algo; 494 int ret = 0; 495 496 if (algor_a) { 497 if (OBJ_cmp(algor_a->algorithm, algor_b->algorithm)) 498 goto err; 499 500 /* The parameter must be NULL in both. */ 501 if ((algor_a->parameter 502 && ASN1_TYPE_get(algor_a->parameter) != V_ASN1_NULL) 503 || (algor_b->parameter 504 && ASN1_TYPE_get(algor_b->parameter) != V_ASN1_NULL)) 505 goto err; 506 } 507 508 ret = len_a == (unsigned)ASN1_STRING_length(b->hashed_msg) && 509 memcmp(imprint_a, ASN1_STRING_get0_data(b->hashed_msg), len_a) == 0; 510 err: 511 if (!ret) 512 ERR_raise(ERR_LIB_TS, TS_R_MESSAGE_IMPRINT_MISMATCH); 513 return ret; 514 } 515 516 static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info) 517 { 518 const ASN1_INTEGER *b = tst_info->nonce; 519 520 if (!b) { 521 ERR_raise(ERR_LIB_TS, TS_R_NONCE_NOT_RETURNED); 522 return 0; 523 } 524 525 /* No error if a nonce is returned without being requested. */ 526 if (ASN1_INTEGER_cmp(a, b) != 0) { 527 ERR_raise(ERR_LIB_TS, TS_R_NONCE_MISMATCH); 528 return 0; 529 } 530 531 return 1; 532 } 533 534 /* 535 * Check if the specified TSA name matches either the subject or one of the 536 * subject alternative names of the TSA certificate. 537 */ 538 static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer) 539 { 540 STACK_OF(GENERAL_NAME) *gen_names = NULL; 541 int idx = -1; 542 int found = 0; 543 544 if (tsa_name->type == GEN_DIRNAME 545 && X509_name_cmp(tsa_name->d.dirn, X509_get_subject_name(signer)) == 0) 546 return 1; 547 gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx); 548 while (gen_names != NULL) { 549 found = ts_find_name(gen_names, tsa_name) >= 0; 550 if (found) 551 break; 552 /* 553 * Get the next subject alternative name, although there should be no 554 * more than one. 555 */ 556 GENERAL_NAMES_free(gen_names); 557 gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx); 558 } 559 GENERAL_NAMES_free(gen_names); 560 561 return found; 562 } 563 564 /* Returns 1 if name is in gen_names, 0 otherwise. */ 565 static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names, GENERAL_NAME *name) 566 { 567 int i, found; 568 for (i = 0, found = 0; !found && i < sk_GENERAL_NAME_num(gen_names); ++i) { 569 GENERAL_NAME *current = sk_GENERAL_NAME_value(gen_names, i); 570 found = GENERAL_NAME_cmp(current, name) == 0; 571 } 572 return found ? i - 1 : -1; 573 } 574