1/* $OpenBSD: tls13_client.c,v 1.102 2023/06/10 15:34:36 tb 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 <openssl/ssl3.h> 19 20#include "bytestring.h" 21#include "ssl_local.h" 22#include "ssl_sigalgs.h" 23#include "ssl_tlsext.h" 24#include "tls13_handshake.h" 25#include "tls13_internal.h" 26 27int 28tls13_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_tls_version_range(s, &ctx->hs->our_min_tls_version, 35 &ctx->hs->our_max_tls_version)) { 36 SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE); 37 return 0; 38 } 39 s->version = ctx->hs->our_max_tls_version; 40 41 tls13_record_layer_set_retry_after_phh(ctx->rl, 42 (s->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 = tls_key_share_new(groups[0])) == NULL) 55 return 0; 56 if (!tls_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 && 68 ctx->hs->our_max_tls_version >= TLS1_3_VERSION) { 69 arc4random_buf(ctx->hs->tls13.legacy_session_id, 70 sizeof(ctx->hs->tls13.legacy_session_id)); 71 ctx->hs->tls13.legacy_session_id_len = 72 sizeof(ctx->hs->tls13.legacy_session_id); 73 } 74 75 return 1; 76} 77 78int 79tls13_client_connect(struct tls13_ctx *ctx) 80{ 81 if (ctx->mode != TLS13_HS_CLIENT) 82 return TLS13_IO_FAILURE; 83 84 return tls13_handshake_perform(ctx); 85} 86 87static int 88tls13_client_hello_build(struct tls13_ctx *ctx, CBB *cbb) 89{ 90 CBB cipher_suites, compression_methods, session_id; 91 uint16_t client_version; 92 SSL *s = ctx->ssl; 93 94 /* Legacy client version is capped at TLS 1.2. */ 95 if (!ssl_max_legacy_version(s, &client_version)) 96 goto err; 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->tls13.legacy_session_id, 106 ctx->hs->tls13.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 133int 134tls13_client_hello_send(struct tls13_ctx *ctx, CBB *cbb) 135{ 136 if (ctx->hs->our_min_tls_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 148int 149tls13_client_hello_sent(struct tls13_ctx *ctx) 150{ 151 tls1_transcript_freeze(ctx->ssl); 152 153 if (ctx->middlebox_compat) { 154 tls13_record_layer_allow_ccs(ctx->rl, 1); 155 ctx->send_dummy_ccs = 1; 156 } 157 158 return 1; 159} 160 161static int 162tls13_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 190static int 191tls13_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 208static int 209tls13_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->our_max_tls_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->tls13.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->tls13.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 * The supported versions extension indicated 0x0304 or greater. 275 * Ensure that it was 0x0304 and that legacy version is set to 0x0303 276 * (RFC 8446 section 4.2.1). 277 */ 278 if (ctx->hs->tls13.server_version != TLS1_3_VERSION || 279 legacy_version != TLS1_2_VERSION) { 280 ctx->alert = TLS13_ALERT_PROTOCOL_VERSION; 281 goto err; 282 } 283 ctx->hs->negotiated_tls_version = ctx->hs->tls13.server_version; 284 ctx->hs->peer_legacy_version = legacy_version; 285 286 /* The session_id must match. */ 287 if (!CBS_mem_equal(&session_id, ctx->hs->tls13.legacy_session_id, 288 ctx->hs->tls13.legacy_session_id_len)) { 289 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 290 goto err; 291 } 292 293 /* 294 * Ensure that the cipher suite is one that we offered in the client 295 * hello and that it is a TLSv1.3 cipher suite. 296 */ 297 cipher = ssl3_get_cipher_by_value(cipher_suite); 298 if (cipher == NULL || !ssl_cipher_in_list(SSL_get_ciphers(s), cipher)) { 299 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 300 goto err; 301 } 302 if (cipher->algorithm_ssl != SSL_TLSV1_3) { 303 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 304 goto err; 305 } 306 if (!(ctx->handshake_stage.hs_type & WITHOUT_HRR) && !ctx->hs->tls13.hrr) { 307 /* 308 * A ServerHello following a HelloRetryRequest MUST use the same 309 * cipher suite (RFC 8446 section 4.1.4). 310 */ 311 if (ctx->hs->cipher != cipher) { 312 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 313 goto err; 314 } 315 } 316 ctx->hs->cipher = cipher; 317 318 if (compression_method != 0) { 319 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 320 goto err; 321 } 322 323 return 1; 324 325 err: 326 if (ctx->alert == 0) 327 ctx->alert = TLS13_ALERT_DECODE_ERROR; 328 329 return 0; 330} 331 332static int 333tls13_client_engage_record_protection(struct tls13_ctx *ctx) 334{ 335 struct tls13_secrets *secrets; 336 struct tls13_secret context; 337 unsigned char buf[EVP_MAX_MD_SIZE]; 338 uint8_t *shared_key = NULL; 339 size_t shared_key_len = 0; 340 size_t hash_len; 341 SSL *s = ctx->ssl; 342 int ret = 0; 343 344 /* Derive the shared key and engage record protection. */ 345 346 if (!tls_key_share_derive(ctx->hs->key_share, &shared_key, 347 &shared_key_len)) 348 goto err; 349 350 s->session->cipher = ctx->hs->cipher; 351 s->session->ssl_version = ctx->hs->tls13.server_version; 352 353 if ((ctx->aead = tls13_cipher_aead(ctx->hs->cipher)) == NULL) 354 goto err; 355 if ((ctx->hash = tls13_cipher_hash(ctx->hs->cipher)) == NULL) 356 goto err; 357 358 if ((secrets = tls13_secrets_create(ctx->hash, 0)) == NULL) 359 goto err; 360 ctx->hs->tls13.secrets = secrets; 361 362 /* XXX - pass in hash. */ 363 if (!tls1_transcript_hash_init(s)) 364 goto err; 365 tls1_transcript_free(s); 366 if (!tls1_transcript_hash_value(s, buf, sizeof(buf), &hash_len)) 367 goto err; 368 context.data = buf; 369 context.len = hash_len; 370 371 /* Early secrets. */ 372 if (!tls13_derive_early_secrets(secrets, secrets->zeros.data, 373 secrets->zeros.len, &context)) 374 goto err; 375 376 /* Handshake secrets. */ 377 if (!tls13_derive_handshake_secrets(ctx->hs->tls13.secrets, shared_key, 378 shared_key_len, &context)) 379 goto err; 380 381 tls13_record_layer_set_aead(ctx->rl, ctx->aead); 382 tls13_record_layer_set_hash(ctx->rl, ctx->hash); 383 384 if (!tls13_record_layer_set_read_traffic_key(ctx->rl, 385 &secrets->server_handshake_traffic, ssl_encryption_handshake)) 386 goto err; 387 if (!tls13_record_layer_set_write_traffic_key(ctx->rl, 388 &secrets->client_handshake_traffic, ssl_encryption_handshake)) 389 goto err; 390 391 ret = 1; 392 393 err: 394 freezero(shared_key, shared_key_len); 395 396 return ret; 397} 398 399int 400tls13_server_hello_retry_request_recv(struct tls13_ctx *ctx, CBS *cbs) 401{ 402 /* 403 * The state machine has no way of knowing if we're going to receive a 404 * HelloRetryRequest or a ServerHello. As such, we have to handle 405 * this case here and hand off to the appropriate function. 406 */ 407 if (!tls13_server_hello_is_retry(cbs)) { 408 ctx->handshake_stage.hs_type |= WITHOUT_HRR; 409 return tls13_server_hello_recv(ctx, cbs); 410 } 411 412 if (!tls13_server_hello_process(ctx, cbs)) 413 return 0; 414 415 /* 416 * This may have been a TLSv1.2 or earlier ServerHello that just 417 * happened to have matching server random... 418 */ 419 if (ctx->hs->tls13.use_legacy) 420 return tls13_use_legacy_client(ctx); 421 422 if (!ctx->hs->tls13.hrr) 423 return 0; 424 425 if (!tls13_synthetic_handshake_message(ctx)) 426 return 0; 427 if (!tls13_handshake_msg_record(ctx)) 428 return 0; 429 430 ctx->hs->tls13.hrr = 0; 431 432 return 1; 433} 434 435int 436tls13_client_hello_retry_send(struct tls13_ctx *ctx, CBB *cbb) 437{ 438 /* 439 * Ensure that the server supported group is one that we listed in our 440 * supported groups and is not the same as the key share we previously 441 * offered. 442 */ 443 if (!tls1_check_group(ctx->ssl, ctx->hs->tls13.server_group)) 444 return 0; /* XXX alert */ 445 if (ctx->hs->tls13.server_group == tls_key_share_group(ctx->hs->key_share)) 446 return 0; /* XXX alert */ 447 448 /* Switch to new key share. */ 449 tls_key_share_free(ctx->hs->key_share); 450 if ((ctx->hs->key_share = 451 tls_key_share_new(ctx->hs->tls13.server_group)) == NULL) 452 return 0; 453 if (!tls_key_share_generate(ctx->hs->key_share)) 454 return 0; 455 456 if (!tls13_client_hello_build(ctx, cbb)) 457 return 0; 458 459 return 1; 460} 461 462int 463tls13_server_hello_recv(struct tls13_ctx *ctx, CBS *cbs) 464{ 465 SSL *s = ctx->ssl; 466 467 /* 468 * We may have received a legacy (pre-TLSv1.3) ServerHello or a TLSv1.3 469 * ServerHello. HelloRetryRequests have already been handled. 470 */ 471 if (!tls13_server_hello_process(ctx, cbs)) 472 return 0; 473 474 if (ctx->handshake_stage.hs_type & WITHOUT_HRR) { 475 tls1_transcript_unfreeze(s); 476 if (!tls13_handshake_msg_record(ctx)) 477 return 0; 478 } 479 480 if (ctx->hs->tls13.use_legacy) { 481 if (!(ctx->handshake_stage.hs_type & WITHOUT_HRR)) 482 return 0; 483 return tls13_use_legacy_client(ctx); 484 } 485 486 if (ctx->hs->tls13.hrr) { 487 /* The server has sent two HelloRetryRequests. */ 488 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 489 return 0; 490 } 491 492 if (!tls13_client_engage_record_protection(ctx)) 493 return 0; 494 495 ctx->handshake_stage.hs_type |= NEGOTIATED; 496 497 return 1; 498} 499 500int 501tls13_server_encrypted_extensions_recv(struct tls13_ctx *ctx, CBS *cbs) 502{ 503 int alert_desc; 504 505 if (!tlsext_client_parse(ctx->ssl, SSL_TLSEXT_MSG_EE, cbs, &alert_desc)) { 506 ctx->alert = alert_desc; 507 return 0; 508 } 509 510 return 1; 511} 512 513int 514tls13_server_certificate_request_recv(struct tls13_ctx *ctx, CBS *cbs) 515{ 516 CBS cert_request_context; 517 int alert_desc; 518 519 /* 520 * Thanks to poor state design in the RFC, this function can be called 521 * when we actually have a certificate message instead of a certificate 522 * request... in that case we call the certificate handler after 523 * switching state, to avoid advancing state. 524 */ 525 if (tls13_handshake_msg_type(ctx->hs_msg) == TLS13_MT_CERTIFICATE) { 526 ctx->handshake_stage.hs_type |= WITHOUT_CR; 527 return tls13_server_certificate_recv(ctx, cbs); 528 } 529 530 if (!CBS_get_u8_length_prefixed(cbs, &cert_request_context)) 531 goto err; 532 if (CBS_len(&cert_request_context) != 0) 533 goto err; 534 535 if (!tlsext_client_parse(ctx->ssl, SSL_TLSEXT_MSG_CR, cbs, &alert_desc)) { 536 ctx->alert = alert_desc; 537 goto err; 538 } 539 540 return 1; 541 542 err: 543 if (ctx->alert == 0) 544 ctx->alert = TLS13_ALERT_DECODE_ERROR; 545 546 return 0; 547} 548 549int 550tls13_server_certificate_recv(struct tls13_ctx *ctx, CBS *cbs) 551{ 552 CBS cert_request_context, cert_list, cert_data; 553 struct stack_st_X509 *certs = NULL; 554 SSL *s = ctx->ssl; 555 X509 *cert = NULL; 556 const uint8_t *p; 557 int alert_desc; 558 int ret = 0; 559 560 if ((certs = sk_X509_new_null()) == NULL) 561 goto err; 562 563 if (!CBS_get_u8_length_prefixed(cbs, &cert_request_context)) 564 goto err; 565 if (CBS_len(&cert_request_context) != 0) 566 goto err; 567 if (!CBS_get_u24_length_prefixed(cbs, &cert_list)) 568 goto err; 569 570 while (CBS_len(&cert_list) > 0) { 571 if (!CBS_get_u24_length_prefixed(&cert_list, &cert_data)) 572 goto err; 573 574 if (!tlsext_client_parse(ctx->ssl, SSL_TLSEXT_MSG_CT, 575 &cert_list, &alert_desc)) { 576 ctx->alert = alert_desc; 577 goto err; 578 } 579 580 p = CBS_data(&cert_data); 581 if ((cert = d2i_X509(NULL, &p, CBS_len(&cert_data))) == NULL) 582 goto err; 583 if (p != CBS_data(&cert_data) + CBS_len(&cert_data)) 584 goto err; 585 586 if (!sk_X509_push(certs, cert)) 587 goto err; 588 589 cert = NULL; 590 } 591 592 /* A server must always provide a non-empty certificate list. */ 593 if (sk_X509_num(certs) < 1) { 594 ctx->alert = TLS13_ALERT_DECODE_ERROR; 595 tls13_set_errorx(ctx, TLS13_ERR_NO_PEER_CERTIFICATE, 0, 596 "peer failed to provide a certificate", NULL); 597 goto err; 598 } 599 600 /* 601 * At this stage we still have no proof of possession. As such, it would 602 * be preferable to keep the chain and verify once we have successfully 603 * processed the CertificateVerify message. 604 */ 605 if (ssl_verify_cert_chain(s, certs) <= 0 && 606 s->verify_mode != SSL_VERIFY_NONE) { 607 ctx->alert = ssl_verify_alarm_type(s->verify_result); 608 tls13_set_errorx(ctx, TLS13_ERR_VERIFY_FAILED, 0, 609 "failed to verify peer certificate", NULL); 610 goto err; 611 } 612 s->session->verify_result = s->verify_result; 613 ERR_clear_error(); 614 615 if (!tls_process_peer_certs(s, certs)) 616 goto err; 617 618 if (ctx->ocsp_status_recv_cb != NULL && 619 !ctx->ocsp_status_recv_cb(ctx)) 620 goto err; 621 622 ret = 1; 623 624 err: 625 sk_X509_pop_free(certs, X509_free); 626 X509_free(cert); 627 628 return ret; 629} 630 631int 632tls13_server_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs) 633{ 634 const struct ssl_sigalg *sigalg; 635 uint16_t signature_scheme; 636 uint8_t *sig_content = NULL; 637 size_t sig_content_len; 638 EVP_MD_CTX *mdctx = NULL; 639 EVP_PKEY_CTX *pctx; 640 EVP_PKEY *pkey; 641 X509 *cert; 642 CBS signature; 643 CBB cbb; 644 int ret = 0; 645 646 memset(&cbb, 0, sizeof(cbb)); 647 648 if (!CBS_get_u16(cbs, &signature_scheme)) 649 goto err; 650 if (!CBS_get_u16_length_prefixed(cbs, &signature)) 651 goto err; 652 653 if (!CBB_init(&cbb, 0)) 654 goto err; 655 if (!CBB_add_bytes(&cbb, tls13_cert_verify_pad, 656 sizeof(tls13_cert_verify_pad))) 657 goto err; 658 if (!CBB_add_bytes(&cbb, tls13_cert_server_verify_context, 659 strlen(tls13_cert_server_verify_context))) 660 goto err; 661 if (!CBB_add_u8(&cbb, 0)) 662 goto err; 663 if (!CBB_add_bytes(&cbb, ctx->hs->tls13.transcript_hash, 664 ctx->hs->tls13.transcript_hash_len)) 665 goto err; 666 if (!CBB_finish(&cbb, &sig_content, &sig_content_len)) 667 goto err; 668 669 if ((cert = ctx->ssl->session->peer_cert) == NULL) 670 goto err; 671 if ((pkey = X509_get0_pubkey(cert)) == NULL) 672 goto err; 673 if ((sigalg = ssl_sigalg_for_peer(ctx->ssl, pkey, 674 signature_scheme)) == NULL) 675 goto err; 676 ctx->hs->peer_sigalg = sigalg; 677 678 if (CBS_len(&signature) > EVP_PKEY_size(pkey)) 679 goto err; 680 681 if ((mdctx = EVP_MD_CTX_new()) == NULL) 682 goto err; 683 if (!EVP_DigestVerifyInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) 684 goto err; 685 if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { 686 if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) 687 goto err; 688 if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) 689 goto err; 690 } 691 if (EVP_DigestVerify(mdctx, CBS_data(&signature), CBS_len(&signature), 692 sig_content, sig_content_len) <= 0) { 693 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 694 goto err; 695 } 696 697 ret = 1; 698 699 err: 700 if (!ret && ctx->alert == 0) 701 ctx->alert = TLS13_ALERT_DECODE_ERROR; 702 CBB_cleanup(&cbb); 703 EVP_MD_CTX_free(mdctx); 704 free(sig_content); 705 706 return ret; 707} 708 709int 710tls13_server_finished_recv(struct tls13_ctx *ctx, CBS *cbs) 711{ 712 struct tls13_secrets *secrets = ctx->hs->tls13.secrets; 713 struct tls13_secret context = { .data = "", .len = 0 }; 714 struct tls13_secret finished_key; 715 uint8_t transcript_hash[EVP_MAX_MD_SIZE]; 716 size_t transcript_hash_len; 717 uint8_t *verify_data = NULL; 718 size_t verify_data_len; 719 uint8_t key[EVP_MAX_MD_SIZE]; 720 HMAC_CTX *hmac_ctx = NULL; 721 unsigned int hlen; 722 int ret = 0; 723 724 /* 725 * Verify server finished. 726 */ 727 finished_key.data = key; 728 finished_key.len = EVP_MD_size(ctx->hash); 729 730 if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, 731 &secrets->server_handshake_traffic, "finished", 732 &context)) 733 goto err; 734 735 if ((hmac_ctx = HMAC_CTX_new()) == NULL) 736 goto err; 737 if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, 738 ctx->hash, NULL)) 739 goto err; 740 if (!HMAC_Update(hmac_ctx, ctx->hs->tls13.transcript_hash, 741 ctx->hs->tls13.transcript_hash_len)) 742 goto err; 743 verify_data_len = HMAC_size(hmac_ctx); 744 if ((verify_data = calloc(1, verify_data_len)) == NULL) 745 goto err; 746 if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) 747 goto err; 748 if (hlen != verify_data_len) 749 goto err; 750 751 if (!CBS_mem_equal(cbs, verify_data, verify_data_len)) { 752 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 753 goto err; 754 } 755 756 if (!CBS_write_bytes(cbs, ctx->hs->peer_finished, 757 sizeof(ctx->hs->peer_finished), 758 &ctx->hs->peer_finished_len)) 759 goto err; 760 761 if (!CBS_skip(cbs, verify_data_len)) 762 goto err; 763 764 /* 765 * Derive application traffic keys. 766 */ 767 if (!tls1_transcript_hash_value(ctx->ssl, transcript_hash, 768 sizeof(transcript_hash), &transcript_hash_len)) 769 goto err; 770 771 context.data = transcript_hash; 772 context.len = transcript_hash_len; 773 774 if (!tls13_derive_application_secrets(secrets, &context)) 775 goto err; 776 777 /* 778 * Any records following the server finished message must be encrypted 779 * using the server application traffic keys. 780 */ 781 if (!tls13_record_layer_set_read_traffic_key(ctx->rl, 782 &secrets->server_application_traffic, ssl_encryption_application)) 783 goto err; 784 785 tls13_record_layer_allow_ccs(ctx->rl, 0); 786 787 ret = 1; 788 789 err: 790 HMAC_CTX_free(hmac_ctx); 791 free(verify_data); 792 793 return ret; 794} 795 796static int 797tls13_client_check_certificate(struct tls13_ctx *ctx, SSL_CERT_PKEY *cpk, 798 int *ok, const struct ssl_sigalg **out_sigalg) 799{ 800 const struct ssl_sigalg *sigalg; 801 SSL *s = ctx->ssl; 802 803 *ok = 0; 804 *out_sigalg = NULL; 805 806 if (cpk->x509 == NULL || cpk->privatekey == NULL) 807 goto done; 808 809 if ((sigalg = ssl_sigalg_select(s, cpk->privatekey)) == NULL) 810 goto done; 811 812 *ok = 1; 813 *out_sigalg = sigalg; 814 815 done: 816 return 1; 817} 818 819static int 820tls13_client_select_certificate(struct tls13_ctx *ctx, SSL_CERT_PKEY **out_cpk, 821 const struct ssl_sigalg **out_sigalg) 822{ 823 SSL *s = ctx->ssl; 824 const struct ssl_sigalg *sigalg; 825 SSL_CERT_PKEY *cpk; 826 int cert_ok; 827 828 *out_cpk = NULL; 829 *out_sigalg = NULL; 830 831 /* 832 * XXX - RFC 8446, 4.4.2.3: the server can communicate preferences 833 * with the certificate_authorities (4.2.4) and oid_filters (4.2.5) 834 * extensions. We should honor the former and must apply the latter. 835 */ 836 837 cpk = &s->cert->pkeys[SSL_PKEY_ECC]; 838 if (!tls13_client_check_certificate(ctx, cpk, &cert_ok, &sigalg)) 839 return 0; 840 if (cert_ok) 841 goto done; 842 843 cpk = &s->cert->pkeys[SSL_PKEY_RSA]; 844 if (!tls13_client_check_certificate(ctx, cpk, &cert_ok, &sigalg)) 845 return 0; 846 if (cert_ok) 847 goto done; 848 849 cpk = NULL; 850 sigalg = NULL; 851 852 done: 853 *out_cpk = cpk; 854 *out_sigalg = sigalg; 855 856 return 1; 857} 858 859int 860tls13_client_certificate_send(struct tls13_ctx *ctx, CBB *cbb) 861{ 862 SSL *s = ctx->ssl; 863 CBB cert_request_context, cert_list; 864 const struct ssl_sigalg *sigalg; 865 STACK_OF(X509) *chain; 866 SSL_CERT_PKEY *cpk; 867 X509 *cert; 868 int i, ret = 0; 869 870 if (!tls13_client_select_certificate(ctx, &cpk, &sigalg)) 871 goto err; 872 873 ctx->hs->tls13.cpk = cpk; 874 ctx->hs->our_sigalg = sigalg; 875 876 if (!CBB_add_u8_length_prefixed(cbb, &cert_request_context)) 877 goto err; 878 if (!CBB_add_u24_length_prefixed(cbb, &cert_list)) 879 goto err; 880 881 /* No certificate selected. */ 882 if (cpk == NULL) 883 goto done; 884 885 if ((chain = cpk->chain) == NULL) 886 chain = s->ctx->extra_certs; 887 888 if (!tls13_cert_add(ctx, &cert_list, cpk->x509, tlsext_client_build)) 889 goto err; 890 891 for (i = 0; i < sk_X509_num(chain); i++) { 892 cert = sk_X509_value(chain, i); 893 if (!tls13_cert_add(ctx, &cert_list, cert, tlsext_client_build)) 894 goto err; 895 } 896 897 ctx->handshake_stage.hs_type |= WITH_CCV; 898 done: 899 if (!CBB_flush(cbb)) 900 goto err; 901 902 ret = 1; 903 904 err: 905 return ret; 906} 907 908int 909tls13_client_certificate_verify_send(struct tls13_ctx *ctx, CBB *cbb) 910{ 911 const struct ssl_sigalg *sigalg; 912 uint8_t *sig = NULL, *sig_content = NULL; 913 size_t sig_len, sig_content_len; 914 EVP_MD_CTX *mdctx = NULL; 915 EVP_PKEY_CTX *pctx; 916 EVP_PKEY *pkey; 917 const SSL_CERT_PKEY *cpk; 918 CBB sig_cbb; 919 int ret = 0; 920 921 memset(&sig_cbb, 0, sizeof(sig_cbb)); 922 923 if ((cpk = ctx->hs->tls13.cpk) == NULL) 924 goto err; 925 if ((sigalg = ctx->hs->our_sigalg) == NULL) 926 goto err; 927 pkey = cpk->privatekey; 928 929 if (!CBB_init(&sig_cbb, 0)) 930 goto err; 931 if (!CBB_add_bytes(&sig_cbb, tls13_cert_verify_pad, 932 sizeof(tls13_cert_verify_pad))) 933 goto err; 934 if (!CBB_add_bytes(&sig_cbb, tls13_cert_client_verify_context, 935 strlen(tls13_cert_client_verify_context))) 936 goto err; 937 if (!CBB_add_u8(&sig_cbb, 0)) 938 goto err; 939 if (!CBB_add_bytes(&sig_cbb, ctx->hs->tls13.transcript_hash, 940 ctx->hs->tls13.transcript_hash_len)) 941 goto err; 942 if (!CBB_finish(&sig_cbb, &sig_content, &sig_content_len)) 943 goto err; 944 945 if ((mdctx = EVP_MD_CTX_new()) == NULL) 946 goto err; 947 if (!EVP_DigestSignInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) 948 goto err; 949 if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { 950 if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) 951 goto err; 952 if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) 953 goto err; 954 } 955 if (!EVP_DigestSign(mdctx, NULL, &sig_len, sig_content, sig_content_len)) 956 goto err; 957 if ((sig = calloc(1, sig_len)) == NULL) 958 goto err; 959 if (!EVP_DigestSign(mdctx, sig, &sig_len, sig_content, sig_content_len)) 960 goto err; 961 962 if (!CBB_add_u16(cbb, sigalg->value)) 963 goto err; 964 if (!CBB_add_u16_length_prefixed(cbb, &sig_cbb)) 965 goto err; 966 if (!CBB_add_bytes(&sig_cbb, sig, sig_len)) 967 goto err; 968 969 if (!CBB_flush(cbb)) 970 goto err; 971 972 ret = 1; 973 974 err: 975 if (!ret && ctx->alert == 0) 976 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 977 978 CBB_cleanup(&sig_cbb); 979 EVP_MD_CTX_free(mdctx); 980 free(sig_content); 981 free(sig); 982 983 return ret; 984} 985 986int 987tls13_client_end_of_early_data_send(struct tls13_ctx *ctx, CBB *cbb) 988{ 989 return 0; 990} 991 992int 993tls13_client_finished_send(struct tls13_ctx *ctx, CBB *cbb) 994{ 995 struct tls13_secrets *secrets = ctx->hs->tls13.secrets; 996 struct tls13_secret context = { .data = "", .len = 0 }; 997 struct tls13_secret finished_key = { .data = NULL, .len = 0 }; 998 uint8_t transcript_hash[EVP_MAX_MD_SIZE]; 999 size_t transcript_hash_len; 1000 uint8_t *verify_data; 1001 size_t verify_data_len; 1002 unsigned int hlen; 1003 HMAC_CTX *hmac_ctx = NULL; 1004 CBS cbs; 1005 int ret = 0; 1006 1007 if (!tls13_secret_init(&finished_key, EVP_MD_size(ctx->hash))) 1008 goto err; 1009 1010 if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, 1011 &secrets->client_handshake_traffic, "finished", 1012 &context)) 1013 goto err; 1014 1015 if (!tls1_transcript_hash_value(ctx->ssl, transcript_hash, 1016 sizeof(transcript_hash), &transcript_hash_len)) 1017 goto err; 1018 1019 if ((hmac_ctx = HMAC_CTX_new()) == NULL) 1020 goto err; 1021 if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, 1022 ctx->hash, NULL)) 1023 goto err; 1024 if (!HMAC_Update(hmac_ctx, transcript_hash, transcript_hash_len)) 1025 goto err; 1026 1027 verify_data_len = HMAC_size(hmac_ctx); 1028 if (!CBB_add_space(cbb, &verify_data, verify_data_len)) 1029 goto err; 1030 if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) 1031 goto err; 1032 if (hlen != verify_data_len) 1033 goto err; 1034 1035 CBS_init(&cbs, verify_data, verify_data_len); 1036 if (!CBS_write_bytes(&cbs, ctx->hs->finished, 1037 sizeof(ctx->hs->finished), &ctx->hs->finished_len)) 1038 goto err; 1039 1040 ret = 1; 1041 1042 err: 1043 tls13_secret_cleanup(&finished_key); 1044 HMAC_CTX_free(hmac_ctx); 1045 1046 return ret; 1047} 1048 1049int 1050tls13_client_finished_sent(struct tls13_ctx *ctx) 1051{ 1052 struct tls13_secrets *secrets = ctx->hs->tls13.secrets; 1053 1054 /* 1055 * Any records following the client finished message must be encrypted 1056 * using the client application traffic keys. 1057 */ 1058 return tls13_record_layer_set_write_traffic_key(ctx->rl, 1059 &secrets->client_application_traffic, ssl_encryption_application); 1060} 1061