1 /* $OpenBSD: tls13_client.c,v 1.67 2020/09/11 17:36:27 jsing Exp $ */ 2 /* 3 * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include "ssl_locl.h" 19 20 #include <openssl/ssl3.h> 21 22 #include "bytestring.h" 23 #include "ssl_tlsext.h" 24 #include "tls13_handshake.h" 25 #include "tls13_internal.h" 26 27 int 28 tls13_client_init(struct tls13_ctx *ctx) 29 { 30 const uint16_t *groups; 31 size_t groups_len; 32 SSL *s = ctx->ssl; 33 34 if (!ssl_supported_version_range(s, &ctx->hs->min_version, 35 &ctx->hs->max_version)) { 36 SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE); 37 return 0; 38 } 39 s->client_version = s->version = ctx->hs->max_version; 40 41 tls13_record_layer_set_retry_after_phh(ctx->rl, 42 (s->internal->mode & SSL_MODE_AUTO_RETRY) != 0); 43 44 if (!ssl_get_new_session(s, 0)) /* XXX */ 45 return 0; 46 47 if (!tls1_transcript_init(s)) 48 return 0; 49 50 /* Generate a key share using our preferred group. */ 51 tls1_get_group_list(s, 0, &groups, &groups_len); 52 if (groups_len < 1) 53 return 0; 54 if ((ctx->hs->key_share = tls13_key_share_new(groups[0])) == NULL) 55 return 0; 56 if (!tls13_key_share_generate(ctx->hs->key_share)) 57 return 0; 58 59 arc4random_buf(s->s3->client_random, SSL3_RANDOM_SIZE); 60 61 /* 62 * The legacy session identifier should either be set to an 63 * unpredictable 32-byte value or zero length... a non-zero length 64 * legacy session identifier triggers compatibility mode (see RFC 8446 65 * Appendix D.4). In the pre-TLSv1.3 case a zero length value is used. 66 */ 67 if (ctx->middlebox_compat && ctx->hs->max_version >= TLS1_3_VERSION) { 68 arc4random_buf(ctx->hs->legacy_session_id, 69 sizeof(ctx->hs->legacy_session_id)); 70 ctx->hs->legacy_session_id_len = 71 sizeof(ctx->hs->legacy_session_id); 72 } 73 74 return 1; 75 } 76 77 int 78 tls13_client_connect(struct tls13_ctx *ctx) 79 { 80 if (ctx->mode != TLS13_HS_CLIENT) 81 return TLS13_IO_FAILURE; 82 83 return tls13_handshake_perform(ctx); 84 } 85 86 static int 87 tls13_client_hello_build(struct tls13_ctx *ctx, CBB *cbb) 88 { 89 CBB cipher_suites, compression_methods, session_id; 90 uint16_t client_version; 91 SSL *s = ctx->ssl; 92 93 /* Legacy client version is capped at TLS 1.2. */ 94 client_version = ctx->hs->max_version; 95 if (client_version > TLS1_2_VERSION) 96 client_version = TLS1_2_VERSION; 97 98 if (!CBB_add_u16(cbb, client_version)) 99 goto err; 100 if (!CBB_add_bytes(cbb, s->s3->client_random, SSL3_RANDOM_SIZE)) 101 goto err; 102 103 if (!CBB_add_u8_length_prefixed(cbb, &session_id)) 104 goto err; 105 if (!CBB_add_bytes(&session_id, ctx->hs->legacy_session_id, 106 ctx->hs->legacy_session_id_len)) 107 goto err; 108 109 if (!CBB_add_u16_length_prefixed(cbb, &cipher_suites)) 110 goto err; 111 if (!ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s), &cipher_suites)) { 112 SSLerror(s, SSL_R_NO_CIPHERS_AVAILABLE); 113 goto err; 114 } 115 116 if (!CBB_add_u8_length_prefixed(cbb, &compression_methods)) 117 goto err; 118 if (!CBB_add_u8(&compression_methods, 0)) 119 goto err; 120 121 if (!tlsext_client_build(s, SSL_TLSEXT_MSG_CH, cbb)) 122 goto err; 123 124 if (!CBB_flush(cbb)) 125 goto err; 126 127 return 1; 128 129 err: 130 return 0; 131 } 132 133 int 134 tls13_client_hello_send(struct tls13_ctx *ctx, CBB *cbb) 135 { 136 if (ctx->hs->min_version < TLS1_2_VERSION) 137 tls13_record_layer_set_legacy_version(ctx->rl, TLS1_VERSION); 138 139 /* We may receive a pre-TLSv1.3 alert in response to the client hello. */ 140 tls13_record_layer_allow_legacy_alerts(ctx->rl, 1); 141 142 if (!tls13_client_hello_build(ctx, cbb)) 143 return 0; 144 145 return 1; 146 } 147 148 int 149 tls13_client_hello_sent(struct tls13_ctx *ctx) 150 { 151 tls13_record_layer_allow_ccs(ctx->rl, 1); 152 153 tls1_transcript_freeze(ctx->ssl); 154 155 if (ctx->middlebox_compat) 156 ctx->send_dummy_ccs = 1; 157 158 return 1; 159 } 160 161 static int 162 tls13_server_hello_is_legacy(CBS *cbs) 163 { 164 CBS extensions_block, extensions, extension_data; 165 uint16_t selected_version = 0; 166 uint16_t type; 167 168 CBS_dup(cbs, &extensions_block); 169 170 if (!CBS_get_u16_length_prefixed(&extensions_block, &extensions)) 171 return 1; 172 173 while (CBS_len(&extensions) > 0) { 174 if (!CBS_get_u16(&extensions, &type)) 175 return 1; 176 if (!CBS_get_u16_length_prefixed(&extensions, &extension_data)) 177 return 1; 178 179 if (type != TLSEXT_TYPE_supported_versions) 180 continue; 181 if (!CBS_get_u16(&extension_data, &selected_version)) 182 return 1; 183 if (CBS_len(&extension_data) != 0) 184 return 1; 185 } 186 187 return (selected_version < TLS1_3_VERSION); 188 } 189 190 static int 191 tls13_server_hello_is_retry(CBS *cbs) 192 { 193 CBS server_hello, server_random; 194 uint16_t legacy_version; 195 196 CBS_dup(cbs, &server_hello); 197 198 if (!CBS_get_u16(&server_hello, &legacy_version)) 199 return 0; 200 if (!CBS_get_bytes(&server_hello, &server_random, SSL3_RANDOM_SIZE)) 201 return 0; 202 203 /* See if this is a HelloRetryRequest. */ 204 return CBS_mem_equal(&server_random, tls13_hello_retry_request_hash, 205 sizeof(tls13_hello_retry_request_hash)); 206 } 207 208 static int 209 tls13_server_hello_process(struct tls13_ctx *ctx, CBS *cbs) 210 { 211 CBS server_random, session_id; 212 uint16_t tlsext_msg_type = SSL_TLSEXT_MSG_SH; 213 uint16_t cipher_suite, legacy_version; 214 uint8_t compression_method; 215 const SSL_CIPHER *cipher; 216 int alert_desc; 217 SSL *s = ctx->ssl; 218 219 if (!CBS_get_u16(cbs, &legacy_version)) 220 goto err; 221 if (!CBS_get_bytes(cbs, &server_random, SSL3_RANDOM_SIZE)) 222 goto err; 223 if (!CBS_get_u8_length_prefixed(cbs, &session_id)) 224 goto err; 225 if (!CBS_get_u16(cbs, &cipher_suite)) 226 goto err; 227 if (!CBS_get_u8(cbs, &compression_method)) 228 goto err; 229 230 if (tls13_server_hello_is_legacy(cbs)) { 231 if (ctx->hs->max_version >= TLS1_3_VERSION) { 232 /* 233 * RFC 8446 section 4.1.3, We must not downgrade if 234 * the server random value contains the TLS 1.2 or 1.1 235 * magical value. 236 */ 237 if (!CBS_skip(&server_random, CBS_len(&server_random) - 238 sizeof(tls13_downgrade_12))) 239 goto err; 240 if (CBS_mem_equal(&server_random, tls13_downgrade_12, 241 sizeof(tls13_downgrade_12)) || 242 CBS_mem_equal(&server_random, tls13_downgrade_11, 243 sizeof(tls13_downgrade_11))) { 244 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 245 goto err; 246 } 247 } 248 249 if (!CBS_skip(cbs, CBS_len(cbs))) 250 goto err; 251 252 ctx->hs->use_legacy = 1; 253 return 1; 254 } 255 256 /* From here on in we know we are doing TLSv1.3. */ 257 tls13_record_layer_set_legacy_version(ctx->rl, TLS1_2_VERSION); 258 tls13_record_layer_allow_legacy_alerts(ctx->rl, 0); 259 260 /* See if this is a HelloRetryRequest. */ 261 /* XXX - see if we can avoid doing this twice. */ 262 if (CBS_mem_equal(&server_random, tls13_hello_retry_request_hash, 263 sizeof(tls13_hello_retry_request_hash))) { 264 tlsext_msg_type = SSL_TLSEXT_MSG_HRR; 265 ctx->hs->hrr = 1; 266 } 267 268 if (!tlsext_client_parse(s, tlsext_msg_type, cbs, &alert_desc)) { 269 ctx->alert = alert_desc; 270 goto err; 271 } 272 273 /* 274 * See if a supported versions extension was returned. If it was then 275 * the legacy version must be set to 0x0303 (RFC 8446 section 4.1.3). 276 * Otherwise, fallback to the legacy version, ensuring that it is both 277 * within range and not TLS 1.3 or greater (which must use the 278 * supported version extension. 279 */ 280 if (ctx->hs->server_version != 0) { 281 if (legacy_version != TLS1_2_VERSION) { 282 ctx->alert = TLS13_ALERT_PROTOCOL_VERSION; 283 goto err; 284 } 285 } else { 286 if (legacy_version < ctx->hs->min_version || 287 legacy_version > ctx->hs->max_version || 288 legacy_version > TLS1_2_VERSION) { 289 ctx->alert = TLS13_ALERT_PROTOCOL_VERSION; 290 goto err; 291 } 292 ctx->hs->server_version = legacy_version; 293 } 294 295 /* The session_id must match. */ 296 if (!CBS_mem_equal(&session_id, ctx->hs->legacy_session_id, 297 ctx->hs->legacy_session_id_len)) { 298 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 299 goto err; 300 } 301 302 /* 303 * Ensure that the cipher suite is one that we offered in the client 304 * hello and that it matches the TLS version selected. 305 */ 306 cipher = ssl3_get_cipher_by_value(cipher_suite); 307 if (cipher == NULL || !ssl_cipher_in_list(SSL_get_ciphers(s), cipher)) { 308 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 309 goto err; 310 } 311 if (ctx->hs->server_version == TLS1_3_VERSION && 312 cipher->algorithm_ssl != SSL_TLSV1_3) { 313 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 314 goto err; 315 } 316 /* XXX - move this to hs_tls13? */ 317 S3I(s)->hs.new_cipher = cipher; 318 319 if (compression_method != 0) { 320 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 321 goto err; 322 } 323 324 return 1; 325 326 err: 327 if (ctx->alert == 0) 328 ctx->alert = TLS13_ALERT_DECODE_ERROR; 329 330 return 0; 331 } 332 333 static int 334 tls13_client_engage_record_protection(struct tls13_ctx *ctx) 335 { 336 struct tls13_secrets *secrets; 337 struct tls13_secret context; 338 unsigned char buf[EVP_MAX_MD_SIZE]; 339 uint8_t *shared_key = NULL; 340 size_t shared_key_len = 0; 341 size_t hash_len; 342 SSL *s = ctx->ssl; 343 int ret = 0; 344 345 /* Derive the shared key and engage record protection. */ 346 347 if (!tls13_key_share_derive(ctx->hs->key_share, &shared_key, 348 &shared_key_len)) 349 goto err; 350 351 s->session->cipher = S3I(s)->hs.new_cipher; 352 s->session->ssl_version = ctx->hs->server_version; 353 354 if ((ctx->aead = tls13_cipher_aead(S3I(s)->hs.new_cipher)) == NULL) 355 goto err; 356 if ((ctx->hash = tls13_cipher_hash(S3I(s)->hs.new_cipher)) == NULL) 357 goto err; 358 359 if ((secrets = tls13_secrets_create(ctx->hash, 0)) == NULL) 360 goto err; 361 ctx->hs->secrets = secrets; 362 363 /* XXX - pass in hash. */ 364 if (!tls1_transcript_hash_init(s)) 365 goto err; 366 tls1_transcript_free(s); 367 if (!tls1_transcript_hash_value(s, buf, sizeof(buf), &hash_len)) 368 goto err; 369 context.data = buf; 370 context.len = hash_len; 371 372 /* Early secrets. */ 373 if (!tls13_derive_early_secrets(secrets, secrets->zeros.data, 374 secrets->zeros.len, &context)) 375 goto err; 376 377 /* Handshake secrets. */ 378 if (!tls13_derive_handshake_secrets(ctx->hs->secrets, shared_key, 379 shared_key_len, &context)) 380 goto err; 381 382 tls13_record_layer_set_aead(ctx->rl, ctx->aead); 383 tls13_record_layer_set_hash(ctx->rl, ctx->hash); 384 385 if (!tls13_record_layer_set_read_traffic_key(ctx->rl, 386 &secrets->server_handshake_traffic)) 387 goto err; 388 if (!tls13_record_layer_set_write_traffic_key(ctx->rl, 389 &secrets->client_handshake_traffic)) 390 goto err; 391 392 ret = 1; 393 394 err: 395 freezero(shared_key, shared_key_len); 396 397 return ret; 398 } 399 400 int 401 tls13_server_hello_retry_request_recv(struct tls13_ctx *ctx, CBS *cbs) 402 { 403 /* 404 * The state machine has no way of knowing if we're going to receive a 405 * HelloRetryRequest or a ServerHello. As such, we have to handle 406 * this case here and hand off to the appropriate function. 407 */ 408 if (!tls13_server_hello_is_retry(cbs)) { 409 ctx->handshake_stage.hs_type |= WITHOUT_HRR; 410 return tls13_server_hello_recv(ctx, cbs); 411 } 412 413 if (!tls13_server_hello_process(ctx, cbs)) 414 return 0; 415 416 /* 417 * This may have been a TLSv1.2 or earlier ServerHello that just happened 418 * to have matching server random... 419 */ 420 if (ctx->hs->use_legacy) 421 return tls13_use_legacy_client(ctx); 422 423 if (!ctx->hs->hrr) 424 return 0; 425 426 if (!tls13_synthetic_handshake_message(ctx)) 427 return 0; 428 if (!tls13_handshake_msg_record(ctx)) 429 return 0; 430 431 ctx->hs->hrr = 0; 432 433 return 1; 434 } 435 436 int 437 tls13_client_hello_retry_send(struct tls13_ctx *ctx, CBB *cbb) 438 { 439 /* 440 * Ensure that the server supported group is one that we listed in our 441 * supported groups and is not the same as the key share we previously 442 * offered. 443 */ 444 if (!tls1_check_curve(ctx->ssl, ctx->hs->server_group)) 445 return 0; /* XXX alert */ 446 if (ctx->hs->server_group == tls13_key_share_group(ctx->hs->key_share)) 447 return 0; /* XXX alert */ 448 449 /* Switch to new key share. */ 450 tls13_key_share_free(ctx->hs->key_share); 451 if ((ctx->hs->key_share = 452 tls13_key_share_new(ctx->hs->server_group)) == NULL) 453 return 0; 454 if (!tls13_key_share_generate(ctx->hs->key_share)) 455 return 0; 456 457 if (!tls13_client_hello_build(ctx, cbb)) 458 return 0; 459 460 return 1; 461 } 462 463 int 464 tls13_server_hello_recv(struct tls13_ctx *ctx, CBS *cbs) 465 { 466 SSL *s = ctx->ssl; 467 468 /* 469 * We may have received a legacy (pre-TLSv1.3) ServerHello or a TLSv1.3 470 * ServerHello. HelloRetryRequests have already been handled. 471 */ 472 if (!tls13_server_hello_process(ctx, cbs)) 473 return 0; 474 475 if (ctx->handshake_stage.hs_type & WITHOUT_HRR) { 476 tls1_transcript_unfreeze(s); 477 if (!tls13_handshake_msg_record(ctx)) 478 return 0; 479 } 480 481 if (ctx->hs->use_legacy) { 482 if (!(ctx->handshake_stage.hs_type & WITHOUT_HRR)) 483 return 0; 484 return tls13_use_legacy_client(ctx); 485 } 486 487 if (ctx->hs->hrr) { 488 /* The server has sent two HelloRetryRequests. */ 489 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 490 return 0; 491 } 492 493 if (!tls13_client_engage_record_protection(ctx)) 494 return 0; 495 496 ctx->handshake_stage.hs_type |= NEGOTIATED; 497 498 return 1; 499 } 500 501 int 502 tls13_server_encrypted_extensions_recv(struct tls13_ctx *ctx, CBS *cbs) 503 { 504 int alert_desc; 505 506 if (!tlsext_client_parse(ctx->ssl, SSL_TLSEXT_MSG_EE, cbs, &alert_desc)) { 507 ctx->alert = alert_desc; 508 goto err; 509 } 510 511 return 1; 512 513 err: 514 if (ctx->alert == 0) 515 ctx->alert = TLS13_ALERT_DECODE_ERROR; 516 517 return 0; 518 } 519 520 int 521 tls13_server_certificate_request_recv(struct tls13_ctx *ctx, CBS *cbs) 522 { 523 CBS cert_request_context; 524 int alert_desc; 525 526 /* 527 * Thanks to poor state design in the RFC, this function can be called 528 * when we actually have a certificate message instead of a certificate 529 * request... in that case we call the certificate handler after 530 * switching state, to avoid advancing state. 531 */ 532 if (tls13_handshake_msg_type(ctx->hs_msg) == TLS13_MT_CERTIFICATE) { 533 ctx->handshake_stage.hs_type |= WITHOUT_CR; 534 return tls13_server_certificate_recv(ctx, cbs); 535 } 536 537 if (!CBS_get_u8_length_prefixed(cbs, &cert_request_context)) 538 goto err; 539 if (CBS_len(&cert_request_context) != 0) 540 goto err; 541 542 if (!tlsext_client_parse(ctx->ssl, SSL_TLSEXT_MSG_CR, cbs, &alert_desc)) { 543 ctx->alert = alert_desc; 544 goto err; 545 } 546 547 return 1; 548 549 err: 550 if (ctx->alert == 0) 551 ctx->alert = TLS13_ALERT_DECODE_ERROR; 552 553 return 0; 554 } 555 556 int 557 tls13_server_certificate_recv(struct tls13_ctx *ctx, CBS *cbs) 558 { 559 CBS cert_request_context, cert_list, cert_data; 560 struct stack_st_X509 *certs = NULL; 561 SSL *s = ctx->ssl; 562 X509 *cert = NULL; 563 EVP_PKEY *pkey; 564 const uint8_t *p; 565 int cert_idx, alert_desc; 566 int ret = 0; 567 568 if ((certs = sk_X509_new_null()) == NULL) 569 goto err; 570 571 if (!CBS_get_u8_length_prefixed(cbs, &cert_request_context)) 572 goto err; 573 if (CBS_len(&cert_request_context) != 0) 574 goto err; 575 if (!CBS_get_u24_length_prefixed(cbs, &cert_list)) 576 goto err; 577 578 while (CBS_len(&cert_list) > 0) { 579 if (!CBS_get_u24_length_prefixed(&cert_list, &cert_data)) 580 goto err; 581 582 if (!tlsext_client_parse(ctx->ssl, SSL_TLSEXT_MSG_CT, 583 &cert_list, &alert_desc)) { 584 ctx->alert = alert_desc; 585 goto err; 586 } 587 588 p = CBS_data(&cert_data); 589 if ((cert = d2i_X509(NULL, &p, CBS_len(&cert_data))) == NULL) 590 goto err; 591 if (p != CBS_data(&cert_data) + CBS_len(&cert_data)) 592 goto err; 593 594 if (!sk_X509_push(certs, cert)) 595 goto err; 596 597 cert = NULL; 598 } 599 600 /* A server must always provide a non-empty certificate list. */ 601 if (sk_X509_num(certs) < 1) { 602 ctx->alert = TLS13_ALERT_DECODE_ERROR; 603 tls13_set_errorx(ctx, TLS13_ERR_NO_PEER_CERTIFICATE, 0, 604 "peer failed to provide a certificate", NULL); 605 goto err; 606 } 607 608 /* 609 * At this stage we still have no proof of possession. As such, it would 610 * be preferable to keep the chain and verify once we have successfully 611 * processed the CertificateVerify message. 612 */ 613 if (ssl_verify_cert_chain(s, certs) <= 0 && 614 s->verify_mode != SSL_VERIFY_NONE) { 615 ctx->alert = ssl_verify_alarm_type(s->verify_result); 616 tls13_set_errorx(ctx, TLS13_ERR_VERIFY_FAILED, 0, 617 "failed to verify peer certificate", NULL); 618 goto err; 619 } 620 ERR_clear_error(); 621 622 cert = sk_X509_value(certs, 0); 623 X509_up_ref(cert); 624 625 if ((pkey = X509_get0_pubkey(cert)) == NULL) 626 goto err; 627 if (EVP_PKEY_missing_parameters(pkey)) 628 goto err; 629 if ((cert_idx = ssl_cert_type(cert, pkey)) < 0) 630 goto err; 631 632 ssl_sess_cert_free(SSI(s)->sess_cert); 633 if ((SSI(s)->sess_cert = ssl_sess_cert_new()) == NULL) 634 goto err; 635 636 SSI(s)->sess_cert->cert_chain = certs; 637 certs = NULL; 638 639 X509_up_ref(cert); 640 SSI(s)->sess_cert->peer_pkeys[cert_idx].x509 = cert; 641 SSI(s)->sess_cert->peer_key = &(SSI(s)->sess_cert->peer_pkeys[cert_idx]); 642 643 X509_free(s->session->peer); 644 645 X509_up_ref(cert); 646 s->session->peer = cert; 647 s->session->verify_result = s->verify_result; 648 649 if (ctx->ocsp_status_recv_cb != NULL && 650 !ctx->ocsp_status_recv_cb(ctx)) 651 goto err; 652 653 ret = 1; 654 655 err: 656 sk_X509_pop_free(certs, X509_free); 657 X509_free(cert); 658 659 return ret; 660 } 661 662 int 663 tls13_server_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs) 664 { 665 const struct ssl_sigalg *sigalg; 666 uint16_t signature_scheme; 667 uint8_t *sig_content = NULL; 668 size_t sig_content_len; 669 EVP_MD_CTX *mdctx = NULL; 670 EVP_PKEY_CTX *pctx; 671 EVP_PKEY *pkey; 672 X509 *cert; 673 CBS signature; 674 CBB cbb; 675 int ret = 0; 676 677 memset(&cbb, 0, sizeof(cbb)); 678 679 if (!CBS_get_u16(cbs, &signature_scheme)) 680 goto err; 681 if (!CBS_get_u16_length_prefixed(cbs, &signature)) 682 goto err; 683 684 if ((sigalg = ssl_sigalg(signature_scheme, tls13_sigalgs, 685 tls13_sigalgs_len)) == NULL) 686 goto err; 687 688 if (!CBB_init(&cbb, 0)) 689 goto err; 690 if (!CBB_add_bytes(&cbb, tls13_cert_verify_pad, 691 sizeof(tls13_cert_verify_pad))) 692 goto err; 693 if (!CBB_add_bytes(&cbb, tls13_cert_server_verify_context, 694 strlen(tls13_cert_server_verify_context))) 695 goto err; 696 if (!CBB_add_u8(&cbb, 0)) 697 goto err; 698 if (!CBB_add_bytes(&cbb, ctx->hs->transcript_hash, 699 ctx->hs->transcript_hash_len)) 700 goto err; 701 if (!CBB_finish(&cbb, &sig_content, &sig_content_len)) 702 goto err; 703 704 if ((cert = ctx->ssl->session->peer) == NULL) 705 goto err; 706 if ((pkey = X509_get0_pubkey(cert)) == NULL) 707 goto err; 708 if (!ssl_sigalg_pkey_ok(sigalg, pkey, 1)) 709 goto err; 710 711 if (CBS_len(&signature) > EVP_PKEY_size(pkey)) 712 goto err; 713 714 if ((mdctx = EVP_MD_CTX_new()) == NULL) 715 goto err; 716 if (!EVP_DigestVerifyInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) 717 goto err; 718 if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { 719 if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) 720 goto err; 721 if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) 722 goto err; 723 } 724 if (!EVP_DigestVerifyUpdate(mdctx, sig_content, sig_content_len)) { 725 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 726 goto err; 727 } 728 if (EVP_DigestVerifyFinal(mdctx, CBS_data(&signature), 729 CBS_len(&signature)) <= 0) { 730 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 731 goto err; 732 } 733 734 ret = 1; 735 736 err: 737 if (!ret && ctx->alert == 0) 738 ctx->alert = TLS13_ALERT_DECODE_ERROR; 739 CBB_cleanup(&cbb); 740 EVP_MD_CTX_free(mdctx); 741 free(sig_content); 742 743 return ret; 744 } 745 746 int 747 tls13_server_finished_recv(struct tls13_ctx *ctx, CBS *cbs) 748 { 749 struct tls13_secrets *secrets = ctx->hs->secrets; 750 struct tls13_secret context = { .data = "", .len = 0 }; 751 struct tls13_secret finished_key; 752 uint8_t transcript_hash[EVP_MAX_MD_SIZE]; 753 size_t transcript_hash_len; 754 uint8_t *verify_data = NULL; 755 size_t verify_data_len; 756 uint8_t key[EVP_MAX_MD_SIZE]; 757 HMAC_CTX *hmac_ctx = NULL; 758 unsigned int hlen; 759 int ret = 0; 760 761 /* 762 * Verify server finished. 763 */ 764 finished_key.data = key; 765 finished_key.len = EVP_MD_size(ctx->hash); 766 767 if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, 768 &secrets->server_handshake_traffic, "finished", 769 &context)) 770 goto err; 771 772 if ((hmac_ctx = HMAC_CTX_new()) == NULL) 773 goto err; 774 if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, 775 ctx->hash, NULL)) 776 goto err; 777 if (!HMAC_Update(hmac_ctx, ctx->hs->transcript_hash, 778 ctx->hs->transcript_hash_len)) 779 goto err; 780 verify_data_len = HMAC_size(hmac_ctx); 781 if ((verify_data = calloc(1, verify_data_len)) == NULL) 782 goto err; 783 if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) 784 goto err; 785 if (hlen != verify_data_len) 786 goto err; 787 788 if (!CBS_mem_equal(cbs, verify_data, verify_data_len)) { 789 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 790 goto err; 791 } 792 793 if (!CBS_skip(cbs, verify_data_len)) 794 goto err; 795 796 /* 797 * Derive application traffic keys. 798 */ 799 if (!tls1_transcript_hash_value(ctx->ssl, transcript_hash, 800 sizeof(transcript_hash), &transcript_hash_len)) 801 goto err; 802 803 context.data = transcript_hash; 804 context.len = transcript_hash_len; 805 806 if (!tls13_derive_application_secrets(secrets, &context)) 807 goto err; 808 809 /* 810 * Any records following the server finished message must be encrypted 811 * using the server application traffic keys. 812 */ 813 if (!tls13_record_layer_set_read_traffic_key(ctx->rl, 814 &secrets->server_application_traffic)) 815 goto err; 816 817 tls13_record_layer_allow_ccs(ctx->rl, 0); 818 819 ret = 1; 820 821 err: 822 HMAC_CTX_free(hmac_ctx); 823 free(verify_data); 824 825 return ret; 826 } 827 828 static int 829 tls13_client_check_certificate(struct tls13_ctx *ctx, CERT_PKEY *cpk, 830 int *ok, const struct ssl_sigalg **out_sigalg) 831 { 832 const struct ssl_sigalg *sigalg; 833 SSL *s = ctx->ssl; 834 835 *ok = 0; 836 *out_sigalg = NULL; 837 838 if (cpk->x509 == NULL || cpk->privatekey == NULL) 839 goto done; 840 841 if ((sigalg = ssl_sigalg_select(s, cpk->privatekey)) == NULL) 842 goto done; 843 844 *ok = 1; 845 *out_sigalg = sigalg; 846 847 done: 848 return 1; 849 } 850 851 static int 852 tls13_client_select_certificate(struct tls13_ctx *ctx, CERT_PKEY **out_cpk, 853 const struct ssl_sigalg **out_sigalg) 854 { 855 SSL *s = ctx->ssl; 856 const struct ssl_sigalg *sigalg; 857 CERT_PKEY *cpk; 858 int cert_ok; 859 860 *out_cpk = NULL; 861 *out_sigalg = NULL; 862 863 /* 864 * XXX - RFC 8446, 4.4.2.3: the server can communicate preferences 865 * with the certificate_authorities (4.2.4) and oid_filters (4.2.5) 866 * extensions. We should honor the former and must apply the latter. 867 */ 868 869 cpk = &s->cert->pkeys[SSL_PKEY_ECC]; 870 if (!tls13_client_check_certificate(ctx, cpk, &cert_ok, &sigalg)) 871 return 0; 872 if (cert_ok) 873 goto done; 874 875 cpk = &s->cert->pkeys[SSL_PKEY_RSA]; 876 if (!tls13_client_check_certificate(ctx, cpk, &cert_ok, &sigalg)) 877 return 0; 878 if (cert_ok) 879 goto done; 880 881 cpk = NULL; 882 sigalg = NULL; 883 884 done: 885 *out_cpk = cpk; 886 *out_sigalg = sigalg; 887 888 return 1; 889 } 890 891 int 892 tls13_client_certificate_send(struct tls13_ctx *ctx, CBB *cbb) 893 { 894 SSL *s = ctx->ssl; 895 CBB cert_request_context, cert_list; 896 const struct ssl_sigalg *sigalg; 897 STACK_OF(X509) *chain; 898 CERT_PKEY *cpk; 899 X509 *cert; 900 int i, ret = 0; 901 902 if (!tls13_client_select_certificate(ctx, &cpk, &sigalg)) 903 goto err; 904 905 ctx->hs->cpk = cpk; 906 ctx->hs->sigalg = sigalg; 907 908 if (!CBB_add_u8_length_prefixed(cbb, &cert_request_context)) 909 goto err; 910 if (!CBB_add_u24_length_prefixed(cbb, &cert_list)) 911 goto err; 912 913 /* No certificate selected. */ 914 if (cpk == NULL) 915 goto done; 916 917 if ((chain = cpk->chain) == NULL) 918 chain = s->ctx->extra_certs; 919 920 if (!tls13_cert_add(ctx, &cert_list, cpk->x509, tlsext_client_build)) 921 goto err; 922 923 for (i = 0; i < sk_X509_num(chain); i++) { 924 cert = sk_X509_value(chain, i); 925 if (!tls13_cert_add(ctx, &cert_list, cert, tlsext_client_build)) 926 goto err; 927 } 928 929 ctx->handshake_stage.hs_type |= WITH_CCV; 930 done: 931 if (!CBB_flush(cbb)) 932 goto err; 933 934 ret = 1; 935 936 err: 937 return ret; 938 } 939 940 int 941 tls13_client_certificate_verify_send(struct tls13_ctx *ctx, CBB *cbb) 942 { 943 const struct ssl_sigalg *sigalg; 944 uint8_t *sig = NULL, *sig_content = NULL; 945 size_t sig_len, sig_content_len; 946 EVP_MD_CTX *mdctx = NULL; 947 EVP_PKEY_CTX *pctx; 948 EVP_PKEY *pkey; 949 const CERT_PKEY *cpk; 950 CBB sig_cbb; 951 int ret = 0; 952 953 memset(&sig_cbb, 0, sizeof(sig_cbb)); 954 955 if ((cpk = ctx->hs->cpk) == NULL) 956 goto err; 957 if ((sigalg = ctx->hs->sigalg) == NULL) 958 goto err; 959 pkey = cpk->privatekey; 960 961 if (!CBB_init(&sig_cbb, 0)) 962 goto err; 963 if (!CBB_add_bytes(&sig_cbb, tls13_cert_verify_pad, 964 sizeof(tls13_cert_verify_pad))) 965 goto err; 966 if (!CBB_add_bytes(&sig_cbb, tls13_cert_client_verify_context, 967 strlen(tls13_cert_client_verify_context))) 968 goto err; 969 if (!CBB_add_u8(&sig_cbb, 0)) 970 goto err; 971 if (!CBB_add_bytes(&sig_cbb, ctx->hs->transcript_hash, 972 ctx->hs->transcript_hash_len)) 973 goto err; 974 if (!CBB_finish(&sig_cbb, &sig_content, &sig_content_len)) 975 goto err; 976 977 if ((mdctx = EVP_MD_CTX_new()) == NULL) 978 goto err; 979 if (!EVP_DigestSignInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) 980 goto err; 981 if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { 982 if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) 983 goto err; 984 if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) 985 goto err; 986 } 987 if (!EVP_DigestSignUpdate(mdctx, sig_content, sig_content_len)) 988 goto err; 989 if (EVP_DigestSignFinal(mdctx, NULL, &sig_len) <= 0) 990 goto err; 991 if ((sig = calloc(1, sig_len)) == NULL) 992 goto err; 993 if (EVP_DigestSignFinal(mdctx, sig, &sig_len) <= 0) 994 goto err; 995 996 if (!CBB_add_u16(cbb, sigalg->value)) 997 goto err; 998 if (!CBB_add_u16_length_prefixed(cbb, &sig_cbb)) 999 goto err; 1000 if (!CBB_add_bytes(&sig_cbb, sig, sig_len)) 1001 goto err; 1002 1003 if (!CBB_flush(cbb)) 1004 goto err; 1005 1006 ret = 1; 1007 1008 err: 1009 if (!ret && ctx->alert == 0) 1010 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 1011 1012 CBB_cleanup(&sig_cbb); 1013 EVP_MD_CTX_free(mdctx); 1014 free(sig_content); 1015 free(sig); 1016 1017 return ret; 1018 } 1019 1020 int 1021 tls13_client_end_of_early_data_send(struct tls13_ctx *ctx, CBB *cbb) 1022 { 1023 return 0; 1024 } 1025 1026 int 1027 tls13_client_finished_send(struct tls13_ctx *ctx, CBB *cbb) 1028 { 1029 struct tls13_secrets *secrets = ctx->hs->secrets; 1030 struct tls13_secret context = { .data = "", .len = 0 }; 1031 struct tls13_secret finished_key; 1032 uint8_t transcript_hash[EVP_MAX_MD_SIZE]; 1033 size_t transcript_hash_len; 1034 uint8_t key[EVP_MAX_MD_SIZE]; 1035 uint8_t *verify_data; 1036 size_t hmac_len; 1037 unsigned int hlen; 1038 HMAC_CTX *hmac_ctx = NULL; 1039 int ret = 0; 1040 1041 finished_key.data = key; 1042 finished_key.len = EVP_MD_size(ctx->hash); 1043 1044 if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, 1045 &secrets->client_handshake_traffic, "finished", 1046 &context)) 1047 goto err; 1048 1049 if (!tls1_transcript_hash_value(ctx->ssl, transcript_hash, 1050 sizeof(transcript_hash), &transcript_hash_len)) 1051 goto err; 1052 1053 if ((hmac_ctx = HMAC_CTX_new()) == NULL) 1054 goto err; 1055 if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, 1056 ctx->hash, NULL)) 1057 goto err; 1058 if (!HMAC_Update(hmac_ctx, transcript_hash, transcript_hash_len)) 1059 goto err; 1060 1061 hmac_len = HMAC_size(hmac_ctx); 1062 if (!CBB_add_space(cbb, &verify_data, hmac_len)) 1063 goto err; 1064 if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) 1065 goto err; 1066 if (hlen != hmac_len) 1067 goto err; 1068 1069 ret = 1; 1070 1071 err: 1072 HMAC_CTX_free(hmac_ctx); 1073 1074 return ret; 1075 } 1076 1077 int 1078 tls13_client_finished_sent(struct tls13_ctx *ctx) 1079 { 1080 struct tls13_secrets *secrets = ctx->hs->secrets; 1081 1082 /* 1083 * Any records following the client finished message must be encrypted 1084 * using the client application traffic keys. 1085 */ 1086 return tls13_record_layer_set_write_traffic_key(ctx->rl, 1087 &secrets->client_application_traffic); 1088 } 1089