1 /* $OpenBSD: tls13_server.c,v 1.61.4.1 2021/02/03 07:06:14 tb Exp $ */ 2 /* 3 * Copyright (c) 2019, 2020 Joel Sing <jsing@openbsd.org> 4 * Copyright (c) 2020 Bob Beck <beck@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <openssl/x509v3.h> 20 21 #include "ssl_locl.h" 22 #include "ssl_tlsext.h" 23 24 #include "tls13_handshake.h" 25 #include "tls13_internal.h" 26 27 int 28 tls13_server_init(struct tls13_ctx *ctx) 29 { 30 SSL *s = ctx->ssl; 31 32 if (!ssl_supported_version_range(s, &ctx->hs->min_version, 33 &ctx->hs->max_version)) { 34 SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE); 35 return 0; 36 } 37 s->version = ctx->hs->max_version; 38 39 tls13_record_layer_set_retry_after_phh(ctx->rl, 40 (s->internal->mode & SSL_MODE_AUTO_RETRY) != 0); 41 42 if (!ssl_get_new_session(s, 0)) /* XXX */ 43 return 0; 44 45 tls13_record_layer_set_legacy_version(ctx->rl, TLS1_VERSION); 46 47 if (!tls1_transcript_init(s)) 48 return 0; 49 50 arc4random_buf(s->s3->server_random, SSL3_RANDOM_SIZE); 51 52 return 1; 53 } 54 55 int 56 tls13_server_accept(struct tls13_ctx *ctx) 57 { 58 if (ctx->mode != TLS13_HS_SERVER) 59 return TLS13_IO_FAILURE; 60 61 return tls13_handshake_perform(ctx); 62 } 63 64 static int 65 tls13_client_hello_is_legacy(CBS *cbs) 66 { 67 CBS extensions_block, extensions, extension_data, versions; 68 uint16_t version, max_version = 0; 69 uint16_t type; 70 71 CBS_dup(cbs, &extensions_block); 72 73 if (!CBS_get_u16_length_prefixed(&extensions_block, &extensions)) 74 return 1; 75 76 while (CBS_len(&extensions) > 0) { 77 if (!CBS_get_u16(&extensions, &type)) 78 return 1; 79 if (!CBS_get_u16_length_prefixed(&extensions, &extension_data)) 80 return 1; 81 82 if (type != TLSEXT_TYPE_supported_versions) 83 continue; 84 if (!CBS_get_u8_length_prefixed(&extension_data, &versions)) 85 return 1; 86 while (CBS_len(&versions) > 0) { 87 if (!CBS_get_u16(&versions, &version)) 88 return 1; 89 if (version >= max_version) 90 max_version = version; 91 } 92 if (CBS_len(&extension_data) != 0) 93 return 1; 94 } 95 96 return (max_version < TLS1_3_VERSION); 97 } 98 99 int 100 tls13_client_hello_required_extensions(struct tls13_ctx *ctx) 101 { 102 SSL *ssl = ctx->ssl; 103 104 /* 105 * RFC 8446, section 9.2. If the ClientHello has supported_versions 106 * containing TLSv1.3, presence or absence of some extensions requires 107 * presence or absence of others. 108 */ 109 110 /* 111 * If we got no pre_shared_key, then signature_algorithms and 112 * supported_groups must both be present. 113 */ 114 if (!tlsext_extension_seen(ssl, TLSEXT_TYPE_pre_shared_key)) { 115 if (!tlsext_extension_seen(ssl, TLSEXT_TYPE_signature_algorithms)) 116 return 0; 117 if (!tlsext_extension_seen(ssl, TLSEXT_TYPE_supported_groups)) 118 return 0; 119 } 120 121 /* 122 * supported_groups and key_share must either both be present or 123 * both be absent. 124 */ 125 if (tlsext_extension_seen(ssl, TLSEXT_TYPE_supported_groups) != 126 tlsext_extension_seen(ssl, TLSEXT_TYPE_key_share)) 127 return 0; 128 129 /* 130 * XXX - Require server_name from client? If so, we SHOULD enforce 131 * this here - RFC 8446, 9.2. 132 */ 133 134 return 1; 135 } 136 137 static const uint8_t tls13_compression_null_only[] = { 0 }; 138 139 static int 140 tls13_client_hello_process(struct tls13_ctx *ctx, CBS *cbs) 141 { 142 CBS cipher_suites, client_random, compression_methods, session_id; 143 STACK_OF(SSL_CIPHER) *ciphers = NULL; 144 const SSL_CIPHER *cipher; 145 uint16_t legacy_version; 146 int alert_desc; 147 SSL *s = ctx->ssl; 148 int ret = 0; 149 150 if (!CBS_get_u16(cbs, &legacy_version)) 151 goto err; 152 if (!CBS_get_bytes(cbs, &client_random, SSL3_RANDOM_SIZE)) 153 goto err; 154 if (!CBS_get_u8_length_prefixed(cbs, &session_id)) 155 goto err; 156 if (!CBS_get_u16_length_prefixed(cbs, &cipher_suites)) 157 goto err; 158 if (!CBS_get_u8_length_prefixed(cbs, &compression_methods)) 159 goto err; 160 161 if (tls13_client_hello_is_legacy(cbs) || s->version < TLS1_3_VERSION) { 162 if (!CBS_skip(cbs, CBS_len(cbs))) 163 goto err; 164 return tls13_use_legacy_server(ctx); 165 } 166 167 /* Add decoded values to the current ClientHello hash */ 168 if (!tls13_clienthello_hash_init(ctx)) { 169 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 170 goto err; 171 } 172 if (!tls13_clienthello_hash_update_bytes(ctx, (void *)&legacy_version, 173 sizeof(legacy_version))) { 174 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 175 goto err; 176 } 177 if (!tls13_clienthello_hash_update(ctx, &client_random)) { 178 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 179 goto err; 180 } 181 if (!tls13_clienthello_hash_update(ctx, &session_id)) { 182 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 183 goto err; 184 } 185 if (!tls13_clienthello_hash_update(ctx, &cipher_suites)) { 186 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 187 goto err; 188 } 189 if (!tls13_clienthello_hash_update(ctx, &compression_methods)) { 190 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 191 goto err; 192 } 193 194 if (!tlsext_server_parse(s, SSL_TLSEXT_MSG_CH, cbs, &alert_desc)) { 195 ctx->alert = alert_desc; 196 goto err; 197 } 198 199 /* Finalize first ClientHello hash, or validate against it */ 200 if (!ctx->hs->hrr) { 201 if (!tls13_clienthello_hash_finalize(ctx)) { 202 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 203 goto err; 204 } 205 } else { 206 if (!tls13_clienthello_hash_validate(ctx)) { 207 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 208 goto err; 209 } 210 tls13_clienthello_hash_clear(ctx->hs); 211 } 212 213 if (!tls13_client_hello_required_extensions(ctx)) { 214 ctx->alert = TLS13_ALERT_MISSING_EXTENSION; 215 goto err; 216 } 217 218 /* 219 * If we got this far we have a supported versions extension that offers 220 * TLS 1.3 or later. This requires the legacy version be set to 0x0303. 221 */ 222 if (legacy_version != TLS1_2_VERSION) { 223 ctx->alert = TLS13_ALERT_PROTOCOL_VERSION; 224 goto err; 225 } 226 227 /* Store legacy session identifier so we can echo it. */ 228 if (CBS_len(&session_id) > sizeof(ctx->hs->legacy_session_id)) { 229 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 230 goto err; 231 } 232 if (!CBS_write_bytes(&session_id, ctx->hs->legacy_session_id, 233 sizeof(ctx->hs->legacy_session_id), 234 &ctx->hs->legacy_session_id_len)) { 235 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 236 goto err; 237 } 238 239 /* Parse cipher suites list and select preferred cipher. */ 240 if ((ciphers = ssl_bytes_to_cipher_list(s, &cipher_suites)) == NULL) { 241 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 242 goto err; 243 } 244 cipher = ssl3_choose_cipher(s, ciphers, SSL_get_ciphers(s)); 245 if (cipher == NULL) { 246 tls13_set_errorx(ctx, TLS13_ERR_NO_SHARED_CIPHER, 0, 247 "no shared cipher found", NULL); 248 ctx->alert = TLS13_ALERT_HANDSHAKE_FAILURE; 249 goto err; 250 } 251 S3I(s)->hs.new_cipher = cipher; 252 253 /* Ensure only the NULL compression method is advertised. */ 254 if (!CBS_mem_equal(&compression_methods, tls13_compression_null_only, 255 sizeof(tls13_compression_null_only))) { 256 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 257 goto err; 258 } 259 260 ret = 1; 261 262 err: 263 sk_SSL_CIPHER_free(ciphers); 264 265 return ret; 266 } 267 268 int 269 tls13_client_hello_recv(struct tls13_ctx *ctx, CBS *cbs) 270 { 271 SSL *s = ctx->ssl; 272 273 if (!tls13_client_hello_process(ctx, cbs)) 274 goto err; 275 276 /* See if we switched back to the legacy client method. */ 277 if (s->method->internal->version < TLS1_3_VERSION) 278 return 1; 279 280 tls13_record_layer_set_legacy_version(ctx->rl, TLS1_2_VERSION); 281 282 /* 283 * If a matching key share was provided, we do not need to send a 284 * HelloRetryRequest. 285 */ 286 /* 287 * XXX - ideally NEGOTIATED would only be added after record protection 288 * has been enabled. This would probably mean using either an 289 * INITIAL | WITHOUT_HRR state, or another intermediate state. 290 */ 291 if (ctx->hs->key_share != NULL) 292 ctx->handshake_stage.hs_type |= NEGOTIATED | WITHOUT_HRR; 293 294 /* XXX - check this is the correct point */ 295 tls13_record_layer_allow_ccs(ctx->rl, 1); 296 297 return 1; 298 299 err: 300 return 0; 301 } 302 303 static int 304 tls13_server_hello_build(struct tls13_ctx *ctx, CBB *cbb, int hrr) 305 { 306 uint16_t tlsext_msg_type = SSL_TLSEXT_MSG_SH; 307 const uint8_t *server_random; 308 CBB session_id; 309 SSL *s = ctx->ssl; 310 uint16_t cipher; 311 312 cipher = SSL_CIPHER_get_value(S3I(s)->hs.new_cipher); 313 server_random = s->s3->server_random; 314 315 if (hrr) { 316 server_random = tls13_hello_retry_request_hash; 317 tlsext_msg_type = SSL_TLSEXT_MSG_HRR; 318 } 319 320 if (!CBB_add_u16(cbb, TLS1_2_VERSION)) 321 goto err; 322 if (!CBB_add_bytes(cbb, server_random, SSL3_RANDOM_SIZE)) 323 goto err; 324 if (!CBB_add_u8_length_prefixed(cbb, &session_id)) 325 goto err; 326 if (!CBB_add_bytes(&session_id, ctx->hs->legacy_session_id, 327 ctx->hs->legacy_session_id_len)) 328 goto err; 329 if (!CBB_add_u16(cbb, cipher)) 330 goto err; 331 if (!CBB_add_u8(cbb, 0)) 332 goto err; 333 if (!tlsext_server_build(s, tlsext_msg_type, cbb)) 334 goto err; 335 336 if (!CBB_flush(cbb)) 337 goto err; 338 339 return 1; 340 err: 341 return 0; 342 } 343 344 static int 345 tls13_server_engage_record_protection(struct tls13_ctx *ctx) 346 { 347 struct tls13_secrets *secrets; 348 struct tls13_secret context; 349 unsigned char buf[EVP_MAX_MD_SIZE]; 350 uint8_t *shared_key = NULL; 351 size_t shared_key_len = 0; 352 size_t hash_len; 353 SSL *s = ctx->ssl; 354 int ret = 0; 355 356 if (!tls13_key_share_derive(ctx->hs->key_share, 357 &shared_key, &shared_key_len)) 358 goto err; 359 360 s->session->cipher = S3I(s)->hs.new_cipher; 361 362 if ((ctx->aead = tls13_cipher_aead(S3I(s)->hs.new_cipher)) == NULL) 363 goto err; 364 if ((ctx->hash = tls13_cipher_hash(S3I(s)->hs.new_cipher)) == NULL) 365 goto err; 366 367 if ((secrets = tls13_secrets_create(ctx->hash, 0)) == NULL) 368 goto err; 369 ctx->hs->secrets = secrets; 370 371 /* XXX - pass in hash. */ 372 if (!tls1_transcript_hash_init(s)) 373 goto err; 374 tls1_transcript_free(s); 375 if (!tls1_transcript_hash_value(s, buf, sizeof(buf), &hash_len)) 376 goto err; 377 context.data = buf; 378 context.len = hash_len; 379 380 /* Early secrets. */ 381 if (!tls13_derive_early_secrets(secrets, secrets->zeros.data, 382 secrets->zeros.len, &context)) 383 goto err; 384 385 /* Handshake secrets. */ 386 if (!tls13_derive_handshake_secrets(ctx->hs->secrets, shared_key, 387 shared_key_len, &context)) 388 goto err; 389 390 tls13_record_layer_set_aead(ctx->rl, ctx->aead); 391 tls13_record_layer_set_hash(ctx->rl, ctx->hash); 392 393 if (!tls13_record_layer_set_read_traffic_key(ctx->rl, 394 &secrets->client_handshake_traffic)) 395 goto err; 396 if (!tls13_record_layer_set_write_traffic_key(ctx->rl, 397 &secrets->server_handshake_traffic)) 398 goto err; 399 400 ctx->handshake_stage.hs_type |= NEGOTIATED; 401 if (!(SSL_get_verify_mode(s) & SSL_VERIFY_PEER)) 402 ctx->handshake_stage.hs_type |= WITHOUT_CR; 403 404 ret = 1; 405 406 err: 407 freezero(shared_key, shared_key_len); 408 return ret; 409 } 410 411 int 412 tls13_server_hello_retry_request_send(struct tls13_ctx *ctx, CBB *cbb) 413 { 414 int nid; 415 416 ctx->hs->hrr = 1; 417 418 if (!tls13_synthetic_handshake_message(ctx)) 419 return 0; 420 421 if (ctx->hs->key_share != NULL) 422 return 0; 423 if ((nid = tls1_get_shared_curve(ctx->ssl)) == NID_undef) 424 return 0; 425 if ((ctx->hs->server_group = tls1_ec_nid2curve_id(nid)) == 0) 426 return 0; 427 428 if (!tls13_server_hello_build(ctx, cbb, 1)) 429 return 0; 430 431 return 1; 432 } 433 434 int 435 tls13_server_hello_retry_request_sent(struct tls13_ctx *ctx) 436 { 437 /* 438 * If the client has requested middlebox compatibility mode, 439 * we MUST send a dummy CCS following our first handshake message. 440 * See RFC 8446 Appendix D.4. 441 */ 442 if (ctx->hs->legacy_session_id_len > 0) 443 ctx->send_dummy_ccs_after = 1; 444 445 return 1; 446 } 447 448 int 449 tls13_client_hello_retry_recv(struct tls13_ctx *ctx, CBS *cbs) 450 { 451 SSL *s = ctx->ssl; 452 453 if (!tls13_client_hello_process(ctx, cbs)) 454 return 0; 455 456 /* XXX - need further checks. */ 457 if (s->method->internal->version < TLS1_3_VERSION) 458 return 0; 459 460 ctx->hs->hrr = 0; 461 462 return 1; 463 } 464 465 static int 466 tls13_servername_process(struct tls13_ctx *ctx) 467 { 468 uint8_t alert = TLS13_ALERT_INTERNAL_ERROR; 469 470 if (!tls13_legacy_servername_process(ctx, &alert)) { 471 ctx->alert = alert; 472 return 0; 473 } 474 475 return 1; 476 } 477 478 int 479 tls13_server_hello_send(struct tls13_ctx *ctx, CBB *cbb) 480 { 481 if (ctx->hs->key_share == NULL) 482 return 0; 483 if (!tls13_key_share_generate(ctx->hs->key_share)) 484 return 0; 485 if (!tls13_servername_process(ctx)) 486 return 0; 487 488 ctx->hs->server_group = 0; 489 490 if (!tls13_server_hello_build(ctx, cbb, 0)) 491 return 0; 492 493 return 1; 494 } 495 496 int 497 tls13_server_hello_sent(struct tls13_ctx *ctx) 498 { 499 /* 500 * If the client has requested middlebox compatibility mode, 501 * we MUST send a dummy CCS following our first handshake message. 502 * See RFC 8446 Appendix D.4. 503 */ 504 if ((ctx->handshake_stage.hs_type & WITHOUT_HRR) && 505 ctx->hs->legacy_session_id_len > 0) 506 ctx->send_dummy_ccs_after = 1; 507 508 return tls13_server_engage_record_protection(ctx); 509 } 510 511 int 512 tls13_server_encrypted_extensions_send(struct tls13_ctx *ctx, CBB *cbb) 513 { 514 if (!tlsext_server_build(ctx->ssl, SSL_TLSEXT_MSG_EE, cbb)) 515 goto err; 516 517 return 1; 518 err: 519 return 0; 520 } 521 522 int 523 tls13_server_certificate_request_send(struct tls13_ctx *ctx, CBB *cbb) 524 { 525 CBB certificate_request_context; 526 527 if (!CBB_add_u8_length_prefixed(cbb, &certificate_request_context)) 528 goto err; 529 if (!tlsext_server_build(ctx->ssl, SSL_TLSEXT_MSG_CR, cbb)) 530 goto err; 531 532 if (!CBB_flush(cbb)) 533 goto err; 534 535 return 1; 536 err: 537 return 0; 538 } 539 540 static int 541 tls13_server_check_certificate(struct tls13_ctx *ctx, CERT_PKEY *cpk, 542 int *ok, const struct ssl_sigalg **out_sigalg) 543 { 544 const struct ssl_sigalg *sigalg; 545 SSL *s = ctx->ssl; 546 547 *ok = 0; 548 *out_sigalg = NULL; 549 550 if (cpk->x509 == NULL || cpk->privatekey == NULL) 551 goto done; 552 553 if (!X509_check_purpose(cpk->x509, -1, 0)) 554 return 0; 555 556 /* 557 * The digitalSignature bit MUST be set if the Key Usage extension is 558 * present as per RFC 8446 section 4.4.2.2. 559 */ 560 if ((cpk->x509->ex_flags & EXFLAG_KUSAGE) && 561 !(cpk->x509->ex_kusage & X509v3_KU_DIGITAL_SIGNATURE)) 562 goto done; 563 564 if ((sigalg = ssl_sigalg_select(s, cpk->privatekey)) == NULL) 565 goto done; 566 567 *ok = 1; 568 *out_sigalg = sigalg; 569 570 done: 571 return 1; 572 } 573 574 static int 575 tls13_server_select_certificate(struct tls13_ctx *ctx, CERT_PKEY **out_cpk, 576 const struct ssl_sigalg **out_sigalg) 577 { 578 SSL *s = ctx->ssl; 579 const struct ssl_sigalg *sigalg; 580 CERT_PKEY *cpk; 581 int cert_ok; 582 583 *out_cpk = NULL; 584 *out_sigalg = NULL; 585 586 cpk = &s->cert->pkeys[SSL_PKEY_ECC]; 587 if (!tls13_server_check_certificate(ctx, cpk, &cert_ok, &sigalg)) 588 return 0; 589 if (cert_ok) 590 goto done; 591 592 cpk = &s->cert->pkeys[SSL_PKEY_RSA]; 593 if (!tls13_server_check_certificate(ctx, cpk, &cert_ok, &sigalg)) 594 return 0; 595 if (cert_ok) 596 goto done; 597 598 cpk = NULL; 599 sigalg = NULL; 600 601 done: 602 *out_cpk = cpk; 603 *out_sigalg = sigalg; 604 605 return 1; 606 } 607 608 int 609 tls13_server_certificate_send(struct tls13_ctx *ctx, CBB *cbb) 610 { 611 SSL *s = ctx->ssl; 612 CBB cert_request_context, cert_list; 613 const struct ssl_sigalg *sigalg; 614 X509_STORE_CTX *xsc = NULL; 615 STACK_OF(X509) *chain; 616 CERT_PKEY *cpk; 617 X509 *cert; 618 int i, ret = 0; 619 620 if (!tls13_server_select_certificate(ctx, &cpk, &sigalg)) 621 goto err; 622 623 if (cpk == NULL) { 624 /* A server must always provide a certificate. */ 625 ctx->alert = TLS13_ALERT_HANDSHAKE_FAILURE; 626 tls13_set_errorx(ctx, TLS13_ERR_NO_CERTIFICATE, 0, 627 "no server certificate", NULL); 628 goto err; 629 } 630 631 ctx->hs->cpk = cpk; 632 ctx->hs->sigalg = sigalg; 633 634 if ((chain = cpk->chain) == NULL) 635 chain = s->ctx->extra_certs; 636 637 if (chain == NULL && !(s->internal->mode & SSL_MODE_NO_AUTO_CHAIN)) { 638 if ((xsc = X509_STORE_CTX_new()) == NULL) 639 goto err; 640 if (!X509_STORE_CTX_init(xsc, s->ctx->cert_store, cpk->x509, NULL)) 641 goto err; 642 X509_VERIFY_PARAM_set_flags(X509_STORE_CTX_get0_param(xsc), 643 X509_V_FLAG_LEGACY_VERIFY); 644 X509_verify_cert(xsc); 645 ERR_clear_error(); 646 chain = xsc->chain; 647 } 648 649 if (!CBB_add_u8_length_prefixed(cbb, &cert_request_context)) 650 goto err; 651 if (!CBB_add_u24_length_prefixed(cbb, &cert_list)) 652 goto err; 653 654 if (!tls13_cert_add(ctx, &cert_list, cpk->x509, tlsext_server_build)) 655 goto err; 656 657 for (i = 0; i < sk_X509_num(chain); i++) { 658 cert = sk_X509_value(chain, i); 659 660 /* 661 * In the case of auto chain, the leaf certificate will be at 662 * the top of the chain - skip over it as we've already added 663 * it earlier. 664 */ 665 if (i == 0 && cert == cpk->x509) 666 continue; 667 668 /* 669 * XXX we don't send extensions with chain certs to avoid sending 670 * a leaf ocsp stape with the chain certs. This needs to get 671 * fixed 672 */ 673 if (!tls13_cert_add(ctx, &cert_list, cert, NULL)) 674 goto err; 675 } 676 677 if (!CBB_flush(cbb)) 678 goto err; 679 680 ret = 1; 681 682 err: 683 X509_STORE_CTX_free(xsc); 684 685 return ret; 686 } 687 688 int 689 tls13_server_certificate_verify_send(struct tls13_ctx *ctx, CBB *cbb) 690 { 691 const struct ssl_sigalg *sigalg; 692 uint8_t *sig = NULL, *sig_content = NULL; 693 size_t sig_len, sig_content_len; 694 EVP_MD_CTX *mdctx = NULL; 695 EVP_PKEY_CTX *pctx; 696 EVP_PKEY *pkey; 697 const CERT_PKEY *cpk; 698 CBB sig_cbb; 699 int ret = 0; 700 701 memset(&sig_cbb, 0, sizeof(sig_cbb)); 702 703 if ((cpk = ctx->hs->cpk) == NULL) 704 goto err; 705 if ((sigalg = ctx->hs->sigalg) == NULL) 706 goto err; 707 pkey = cpk->privatekey; 708 709 if (!CBB_init(&sig_cbb, 0)) 710 goto err; 711 if (!CBB_add_bytes(&sig_cbb, tls13_cert_verify_pad, 712 sizeof(tls13_cert_verify_pad))) 713 goto err; 714 if (!CBB_add_bytes(&sig_cbb, tls13_cert_server_verify_context, 715 strlen(tls13_cert_server_verify_context))) 716 goto err; 717 if (!CBB_add_u8(&sig_cbb, 0)) 718 goto err; 719 if (!CBB_add_bytes(&sig_cbb, ctx->hs->transcript_hash, 720 ctx->hs->transcript_hash_len)) 721 goto err; 722 if (!CBB_finish(&sig_cbb, &sig_content, &sig_content_len)) 723 goto err; 724 725 if ((mdctx = EVP_MD_CTX_new()) == NULL) 726 goto err; 727 if (!EVP_DigestSignInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) 728 goto err; 729 if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { 730 if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) 731 goto err; 732 if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) 733 goto err; 734 } 735 if (!EVP_DigestSignUpdate(mdctx, sig_content, sig_content_len)) 736 goto err; 737 if (EVP_DigestSignFinal(mdctx, NULL, &sig_len) <= 0) 738 goto err; 739 if ((sig = calloc(1, sig_len)) == NULL) 740 goto err; 741 if (EVP_DigestSignFinal(mdctx, sig, &sig_len) <= 0) 742 goto err; 743 744 if (!CBB_add_u16(cbb, sigalg->value)) 745 goto err; 746 if (!CBB_add_u16_length_prefixed(cbb, &sig_cbb)) 747 goto err; 748 if (!CBB_add_bytes(&sig_cbb, sig, sig_len)) 749 goto err; 750 751 if (!CBB_flush(cbb)) 752 goto err; 753 754 ret = 1; 755 756 err: 757 if (!ret && ctx->alert == 0) 758 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 759 760 CBB_cleanup(&sig_cbb); 761 EVP_MD_CTX_free(mdctx); 762 free(sig_content); 763 free(sig); 764 765 return ret; 766 } 767 768 int 769 tls13_server_finished_send(struct tls13_ctx *ctx, CBB *cbb) 770 { 771 struct tls13_secrets *secrets = ctx->hs->secrets; 772 struct tls13_secret context = { .data = "", .len = 0 }; 773 struct tls13_secret finished_key; 774 uint8_t transcript_hash[EVP_MAX_MD_SIZE]; 775 size_t transcript_hash_len; 776 uint8_t key[EVP_MAX_MD_SIZE]; 777 uint8_t *verify_data; 778 size_t hmac_len; 779 unsigned int hlen; 780 HMAC_CTX *hmac_ctx = NULL; 781 int ret = 0; 782 783 finished_key.data = key; 784 finished_key.len = EVP_MD_size(ctx->hash); 785 786 if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, 787 &secrets->server_handshake_traffic, "finished", 788 &context)) 789 goto err; 790 791 if (!tls1_transcript_hash_value(ctx->ssl, transcript_hash, 792 sizeof(transcript_hash), &transcript_hash_len)) 793 goto err; 794 795 if ((hmac_ctx = HMAC_CTX_new()) == NULL) 796 goto err; 797 if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, 798 ctx->hash, NULL)) 799 goto err; 800 if (!HMAC_Update(hmac_ctx, transcript_hash, transcript_hash_len)) 801 goto err; 802 803 hmac_len = HMAC_size(hmac_ctx); 804 if (!CBB_add_space(cbb, &verify_data, hmac_len)) 805 goto err; 806 if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) 807 goto err; 808 if (hlen != hmac_len) 809 goto err; 810 811 ret = 1; 812 813 err: 814 HMAC_CTX_free(hmac_ctx); 815 816 return ret; 817 } 818 819 int 820 tls13_server_finished_sent(struct tls13_ctx *ctx) 821 { 822 struct tls13_secrets *secrets = ctx->hs->secrets; 823 struct tls13_secret context = { .data = "", .len = 0 }; 824 825 /* 826 * Derive application traffic keys. 827 */ 828 context.data = ctx->hs->transcript_hash; 829 context.len = ctx->hs->transcript_hash_len; 830 831 if (!tls13_derive_application_secrets(secrets, &context)) 832 return 0; 833 834 /* 835 * Any records following the server finished message must be encrypted 836 * using the server application traffic keys. 837 */ 838 return tls13_record_layer_set_write_traffic_key(ctx->rl, 839 &secrets->server_application_traffic); 840 } 841 842 int 843 tls13_client_certificate_recv(struct tls13_ctx *ctx, CBS *cbs) 844 { 845 CBS cert_request_context, cert_list, cert_data, cert_exts; 846 struct stack_st_X509 *certs = NULL; 847 SSL *s = ctx->ssl; 848 X509 *cert = NULL; 849 EVP_PKEY *pkey; 850 const uint8_t *p; 851 int cert_idx; 852 int ret = 0; 853 854 if (!CBS_get_u8_length_prefixed(cbs, &cert_request_context)) 855 goto err; 856 if (CBS_len(&cert_request_context) != 0) 857 goto err; 858 if (!CBS_get_u24_length_prefixed(cbs, &cert_list)) 859 goto err; 860 if (CBS_len(&cert_list) == 0) { 861 if (!(s->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT)) 862 return 1; 863 ctx->alert = TLS13_ALERT_CERTIFICATE_REQUIRED; 864 tls13_set_errorx(ctx, TLS13_ERR_NO_PEER_CERTIFICATE, 0, 865 "peer did not provide a certificate", NULL); 866 goto err; 867 } 868 869 if ((certs = sk_X509_new_null()) == NULL) 870 goto err; 871 while (CBS_len(&cert_list) > 0) { 872 if (!CBS_get_u24_length_prefixed(&cert_list, &cert_data)) 873 goto err; 874 if (!CBS_get_u16_length_prefixed(&cert_list, &cert_exts)) 875 goto err; 876 877 p = CBS_data(&cert_data); 878 if ((cert = d2i_X509(NULL, &p, CBS_len(&cert_data))) == NULL) 879 goto err; 880 if (p != CBS_data(&cert_data) + CBS_len(&cert_data)) 881 goto err; 882 883 if (!sk_X509_push(certs, cert)) 884 goto err; 885 886 cert = NULL; 887 } 888 889 /* 890 * At this stage we still have no proof of possession. As such, it would 891 * be preferable to keep the chain and verify once we have successfully 892 * processed the CertificateVerify message. 893 */ 894 if (ssl_verify_cert_chain(s, certs) <= 0) { 895 ctx->alert = ssl_verify_alarm_type(s->verify_result); 896 tls13_set_errorx(ctx, TLS13_ERR_VERIFY_FAILED, 0, 897 "failed to verify peer certificate", NULL); 898 goto err; 899 } 900 ERR_clear_error(); 901 902 cert = sk_X509_value(certs, 0); 903 X509_up_ref(cert); 904 905 if ((pkey = X509_get0_pubkey(cert)) == NULL) 906 goto err; 907 if (EVP_PKEY_missing_parameters(pkey)) 908 goto err; 909 if ((cert_idx = ssl_cert_type(cert, pkey)) < 0) 910 goto err; 911 912 ssl_sess_cert_free(SSI(s)->sess_cert); 913 if ((SSI(s)->sess_cert = ssl_sess_cert_new()) == NULL) 914 goto err; 915 916 SSI(s)->sess_cert->cert_chain = certs; 917 certs = NULL; 918 919 X509_up_ref(cert); 920 SSI(s)->sess_cert->peer_pkeys[cert_idx].x509 = cert; 921 SSI(s)->sess_cert->peer_key = &(SSI(s)->sess_cert->peer_pkeys[cert_idx]); 922 923 X509_free(s->session->peer); 924 925 X509_up_ref(cert); 926 s->session->peer = cert; 927 s->session->verify_result = s->verify_result; 928 929 ctx->handshake_stage.hs_type |= WITH_CCV; 930 ret = 1; 931 932 err: 933 sk_X509_pop_free(certs, X509_free); 934 X509_free(cert); 935 936 return ret; 937 } 938 939 int 940 tls13_client_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs) 941 { 942 const struct ssl_sigalg *sigalg; 943 uint16_t signature_scheme; 944 uint8_t *sig_content = NULL; 945 size_t sig_content_len; 946 EVP_MD_CTX *mdctx = NULL; 947 EVP_PKEY_CTX *pctx; 948 EVP_PKEY *pkey; 949 X509 *cert; 950 CBS signature; 951 CBB cbb; 952 int ret = 0; 953 954 memset(&cbb, 0, sizeof(cbb)); 955 956 if (!CBS_get_u16(cbs, &signature_scheme)) 957 goto err; 958 if (!CBS_get_u16_length_prefixed(cbs, &signature)) 959 goto err; 960 961 if ((sigalg = ssl_sigalg(signature_scheme, tls13_sigalgs, 962 tls13_sigalgs_len)) == NULL) 963 goto err; 964 965 if (!CBB_init(&cbb, 0)) 966 goto err; 967 if (!CBB_add_bytes(&cbb, tls13_cert_verify_pad, 968 sizeof(tls13_cert_verify_pad))) 969 goto err; 970 if (!CBB_add_bytes(&cbb, tls13_cert_client_verify_context, 971 strlen(tls13_cert_client_verify_context))) 972 goto err; 973 if (!CBB_add_u8(&cbb, 0)) 974 goto err; 975 if (!CBB_add_bytes(&cbb, ctx->hs->transcript_hash, 976 ctx->hs->transcript_hash_len)) 977 goto err; 978 if (!CBB_finish(&cbb, &sig_content, &sig_content_len)) 979 goto err; 980 981 if ((cert = ctx->ssl->session->peer) == NULL) 982 goto err; 983 if ((pkey = X509_get0_pubkey(cert)) == NULL) 984 goto err; 985 if (!ssl_sigalg_pkey_ok(sigalg, pkey, 1)) 986 goto err; 987 988 if (CBS_len(&signature) > EVP_PKEY_size(pkey)) 989 goto err; 990 991 if ((mdctx = EVP_MD_CTX_new()) == NULL) 992 goto err; 993 if (!EVP_DigestVerifyInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) 994 goto err; 995 if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { 996 if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) 997 goto err; 998 if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) 999 goto err; 1000 } 1001 if (!EVP_DigestVerifyUpdate(mdctx, sig_content, sig_content_len)) { 1002 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 1003 goto err; 1004 } 1005 if (EVP_DigestVerifyFinal(mdctx, CBS_data(&signature), 1006 CBS_len(&signature)) <= 0) { 1007 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 1008 goto err; 1009 } 1010 1011 ret = 1; 1012 1013 err: 1014 if (!ret && ctx->alert == 0) 1015 ctx->alert = TLS13_ALERT_DECODE_ERROR; 1016 1017 CBB_cleanup(&cbb); 1018 EVP_MD_CTX_free(mdctx); 1019 free(sig_content); 1020 1021 return ret; 1022 } 1023 1024 int 1025 tls13_client_end_of_early_data_recv(struct tls13_ctx *ctx, CBS *cbs) 1026 { 1027 return 0; 1028 } 1029 1030 int 1031 tls13_client_finished_recv(struct tls13_ctx *ctx, CBS *cbs) 1032 { 1033 struct tls13_secrets *secrets = ctx->hs->secrets; 1034 struct tls13_secret context = { .data = "", .len = 0 }; 1035 struct tls13_secret finished_key; 1036 uint8_t *verify_data = NULL; 1037 size_t verify_data_len; 1038 uint8_t key[EVP_MAX_MD_SIZE]; 1039 HMAC_CTX *hmac_ctx = NULL; 1040 unsigned int hlen; 1041 int ret = 0; 1042 1043 /* 1044 * Verify client finished. 1045 */ 1046 finished_key.data = key; 1047 finished_key.len = EVP_MD_size(ctx->hash); 1048 1049 if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, 1050 &secrets->client_handshake_traffic, "finished", 1051 &context)) 1052 goto err; 1053 1054 if ((hmac_ctx = HMAC_CTX_new()) == NULL) 1055 goto err; 1056 if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, 1057 ctx->hash, NULL)) 1058 goto err; 1059 if (!HMAC_Update(hmac_ctx, ctx->hs->transcript_hash, 1060 ctx->hs->transcript_hash_len)) 1061 goto err; 1062 verify_data_len = HMAC_size(hmac_ctx); 1063 if ((verify_data = calloc(1, verify_data_len)) == NULL) 1064 goto err; 1065 if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) 1066 goto err; 1067 if (hlen != verify_data_len) 1068 goto err; 1069 1070 if (!CBS_mem_equal(cbs, verify_data, verify_data_len)) { 1071 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 1072 goto err; 1073 } 1074 1075 if (!CBS_skip(cbs, verify_data_len)) 1076 goto err; 1077 1078 /* 1079 * Any records following the client finished message must be encrypted 1080 * using the client application traffic keys. 1081 */ 1082 if (!tls13_record_layer_set_read_traffic_key(ctx->rl, 1083 &secrets->client_application_traffic)) 1084 goto err; 1085 1086 tls13_record_layer_allow_ccs(ctx->rl, 0); 1087 1088 ret = 1; 1089 1090 err: 1091 HMAC_CTX_free(hmac_ctx); 1092 free(verify_data); 1093 1094 return ret; 1095 } 1096