1 /* $OpenBSD: tls13_server.c,v 1.88 2021/10/31 16:37:25 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_sigalgs.h" 23 #include "ssl_tlsext.h" 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_tls_version_range(s, &ctx->hs->our_min_tls_version, 33 &ctx->hs->our_max_tls_version)) { 34 SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE); 35 return 0; 36 } 37 s->version = ctx->hs->our_max_tls_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 *s = 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(s, TLSEXT_TYPE_pre_shared_key)) { 115 if (!tlsext_extension_seen(s, TLSEXT_TYPE_signature_algorithms)) 116 return 0; 117 if (!tlsext_extension_seen(s, 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(s, TLSEXT_TYPE_supported_groups) != 126 tlsext_extension_seen(s, 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 ctx->hs->negotiated_tls_version = TLS1_3_VERSION; 167 ctx->hs->peer_legacy_version = legacy_version; 168 169 /* Ensure we send subsequent alerts with the correct record version. */ 170 tls13_record_layer_set_legacy_version(ctx->rl, TLS1_2_VERSION); 171 172 /* Add decoded values to the current ClientHello hash */ 173 if (!tls13_clienthello_hash_init(ctx)) { 174 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 175 goto err; 176 } 177 if (!tls13_clienthello_hash_update_bytes(ctx, (void *)&legacy_version, 178 sizeof(legacy_version))) { 179 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 180 goto err; 181 } 182 if (!tls13_clienthello_hash_update(ctx, &client_random)) { 183 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 184 goto err; 185 } 186 if (!tls13_clienthello_hash_update(ctx, &session_id)) { 187 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 188 goto err; 189 } 190 if (!tls13_clienthello_hash_update(ctx, &cipher_suites)) { 191 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 192 goto err; 193 } 194 if (!tls13_clienthello_hash_update(ctx, &compression_methods)) { 195 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 196 goto err; 197 } 198 199 if (!tlsext_server_parse(s, SSL_TLSEXT_MSG_CH, cbs, &alert_desc)) { 200 ctx->alert = alert_desc; 201 goto err; 202 } 203 204 /* Finalize first ClientHello hash, or validate against it */ 205 if (!ctx->hs->tls13.hrr) { 206 if (!tls13_clienthello_hash_finalize(ctx)) { 207 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 208 goto err; 209 } 210 } else { 211 if (!tls13_clienthello_hash_validate(ctx)) { 212 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 213 goto err; 214 } 215 tls13_clienthello_hash_clear(&ctx->hs->tls13); 216 } 217 218 if (!tls13_client_hello_required_extensions(ctx)) { 219 ctx->alert = TLS13_ALERT_MISSING_EXTENSION; 220 goto err; 221 } 222 223 /* 224 * If we got this far we have a supported versions extension that offers 225 * TLS 1.3 or later. This requires the legacy version be set to 0x0303. 226 */ 227 if (legacy_version != TLS1_2_VERSION) { 228 ctx->alert = TLS13_ALERT_PROTOCOL_VERSION; 229 goto err; 230 } 231 232 /* Store legacy session identifier so we can echo it. */ 233 if (CBS_len(&session_id) > sizeof(ctx->hs->tls13.legacy_session_id)) { 234 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 235 goto err; 236 } 237 if (!CBS_write_bytes(&session_id, ctx->hs->tls13.legacy_session_id, 238 sizeof(ctx->hs->tls13.legacy_session_id), 239 &ctx->hs->tls13.legacy_session_id_len)) { 240 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 241 goto err; 242 } 243 244 /* Parse cipher suites list and select preferred cipher. */ 245 if ((ciphers = ssl_bytes_to_cipher_list(s, &cipher_suites)) == NULL) { 246 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 247 goto err; 248 } 249 cipher = ssl3_choose_cipher(s, ciphers, SSL_get_ciphers(s)); 250 if (cipher == NULL) { 251 tls13_set_errorx(ctx, TLS13_ERR_NO_SHARED_CIPHER, 0, 252 "no shared cipher found", NULL); 253 ctx->alert = TLS13_ALERT_HANDSHAKE_FAILURE; 254 goto err; 255 } 256 ctx->hs->cipher = cipher; 257 258 sk_SSL_CIPHER_free(s->session->ciphers); 259 s->session->ciphers = ciphers; 260 ciphers = NULL; 261 262 /* Ensure only the NULL compression method is advertised. */ 263 if (!CBS_mem_equal(&compression_methods, tls13_compression_null_only, 264 sizeof(tls13_compression_null_only))) { 265 ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; 266 goto err; 267 } 268 269 ret = 1; 270 271 err: 272 sk_SSL_CIPHER_free(ciphers); 273 274 return ret; 275 } 276 277 int 278 tls13_client_hello_recv(struct tls13_ctx *ctx, CBS *cbs) 279 { 280 SSL *s = ctx->ssl; 281 282 if (!tls13_client_hello_process(ctx, cbs)) 283 goto err; 284 285 /* See if we switched back to the legacy client method. */ 286 if (s->method->version < TLS1_3_VERSION) 287 return 1; 288 289 /* 290 * If a matching key share was provided, we do not need to send a 291 * HelloRetryRequest. 292 */ 293 /* 294 * XXX - ideally NEGOTIATED would only be added after record protection 295 * has been enabled. This would probably mean using either an 296 * INITIAL | WITHOUT_HRR state, or another intermediate state. 297 */ 298 if (ctx->hs->tls13.key_share != NULL) 299 ctx->handshake_stage.hs_type |= NEGOTIATED | WITHOUT_HRR; 300 301 /* XXX - check this is the correct point */ 302 tls13_record_layer_allow_ccs(ctx->rl, 1); 303 304 return 1; 305 306 err: 307 return 0; 308 } 309 310 static int 311 tls13_server_hello_build(struct tls13_ctx *ctx, CBB *cbb, int hrr) 312 { 313 uint16_t tlsext_msg_type = SSL_TLSEXT_MSG_SH; 314 const uint8_t *server_random; 315 CBB session_id; 316 SSL *s = ctx->ssl; 317 uint16_t cipher; 318 319 cipher = SSL_CIPHER_get_value(ctx->hs->cipher); 320 server_random = s->s3->server_random; 321 322 if (hrr) { 323 server_random = tls13_hello_retry_request_hash; 324 tlsext_msg_type = SSL_TLSEXT_MSG_HRR; 325 } 326 327 if (!CBB_add_u16(cbb, TLS1_2_VERSION)) 328 goto err; 329 if (!CBB_add_bytes(cbb, server_random, SSL3_RANDOM_SIZE)) 330 goto err; 331 if (!CBB_add_u8_length_prefixed(cbb, &session_id)) 332 goto err; 333 if (!CBB_add_bytes(&session_id, ctx->hs->tls13.legacy_session_id, 334 ctx->hs->tls13.legacy_session_id_len)) 335 goto err; 336 if (!CBB_add_u16(cbb, cipher)) 337 goto err; 338 if (!CBB_add_u8(cbb, 0)) 339 goto err; 340 if (!tlsext_server_build(s, tlsext_msg_type, cbb)) 341 goto err; 342 343 if (!CBB_flush(cbb)) 344 goto err; 345 346 return 1; 347 err: 348 return 0; 349 } 350 351 static int 352 tls13_server_engage_record_protection(struct tls13_ctx *ctx) 353 { 354 struct tls13_secrets *secrets; 355 struct tls13_secret context; 356 unsigned char buf[EVP_MAX_MD_SIZE]; 357 uint8_t *shared_key = NULL; 358 size_t shared_key_len = 0; 359 size_t hash_len; 360 SSL *s = ctx->ssl; 361 int ret = 0; 362 363 if (!tls13_key_share_derive(ctx->hs->tls13.key_share, 364 &shared_key, &shared_key_len)) 365 goto err; 366 367 s->session->cipher = ctx->hs->cipher; 368 369 if ((ctx->aead = tls13_cipher_aead(ctx->hs->cipher)) == NULL) 370 goto err; 371 if ((ctx->hash = tls13_cipher_hash(ctx->hs->cipher)) == NULL) 372 goto err; 373 374 if ((secrets = tls13_secrets_create(ctx->hash, 0)) == NULL) 375 goto err; 376 ctx->hs->tls13.secrets = secrets; 377 378 /* XXX - pass in hash. */ 379 if (!tls1_transcript_hash_init(s)) 380 goto err; 381 tls1_transcript_free(s); 382 if (!tls1_transcript_hash_value(s, buf, sizeof(buf), &hash_len)) 383 goto err; 384 context.data = buf; 385 context.len = hash_len; 386 387 /* Early secrets. */ 388 if (!tls13_derive_early_secrets(secrets, secrets->zeros.data, 389 secrets->zeros.len, &context)) 390 goto err; 391 392 /* Handshake secrets. */ 393 if (!tls13_derive_handshake_secrets(ctx->hs->tls13.secrets, shared_key, 394 shared_key_len, &context)) 395 goto err; 396 397 tls13_record_layer_set_aead(ctx->rl, ctx->aead); 398 tls13_record_layer_set_hash(ctx->rl, ctx->hash); 399 400 if (!tls13_record_layer_set_read_traffic_key(ctx->rl, 401 &secrets->client_handshake_traffic)) 402 goto err; 403 if (!tls13_record_layer_set_write_traffic_key(ctx->rl, 404 &secrets->server_handshake_traffic)) 405 goto err; 406 407 ctx->handshake_stage.hs_type |= NEGOTIATED; 408 if (!(SSL_get_verify_mode(s) & SSL_VERIFY_PEER)) 409 ctx->handshake_stage.hs_type |= WITHOUT_CR; 410 411 ret = 1; 412 413 err: 414 freezero(shared_key, shared_key_len); 415 return ret; 416 } 417 418 int 419 tls13_server_hello_retry_request_send(struct tls13_ctx *ctx, CBB *cbb) 420 { 421 int nid; 422 423 ctx->hs->tls13.hrr = 1; 424 425 if (!tls13_synthetic_handshake_message(ctx)) 426 return 0; 427 428 if (ctx->hs->tls13.key_share != NULL) 429 return 0; 430 if ((nid = tls1_get_shared_curve(ctx->ssl)) == NID_undef) 431 return 0; 432 if ((ctx->hs->tls13.server_group = tls1_ec_nid2curve_id(nid)) == 0) 433 return 0; 434 435 if (!tls13_server_hello_build(ctx, cbb, 1)) 436 return 0; 437 438 return 1; 439 } 440 441 int 442 tls13_server_hello_retry_request_sent(struct tls13_ctx *ctx) 443 { 444 /* 445 * If the client has requested middlebox compatibility mode, 446 * we MUST send a dummy CCS following our first handshake message. 447 * See RFC 8446 Appendix D.4. 448 */ 449 if (ctx->hs->tls13.legacy_session_id_len > 0) 450 ctx->send_dummy_ccs_after = 1; 451 452 return 1; 453 } 454 455 int 456 tls13_client_hello_retry_recv(struct tls13_ctx *ctx, CBS *cbs) 457 { 458 SSL *s = ctx->ssl; 459 460 if (!tls13_client_hello_process(ctx, cbs)) 461 return 0; 462 463 /* XXX - need further checks. */ 464 if (s->method->version < TLS1_3_VERSION) 465 return 0; 466 467 ctx->hs->tls13.hrr = 0; 468 469 return 1; 470 } 471 472 static int 473 tls13_servername_process(struct tls13_ctx *ctx) 474 { 475 uint8_t alert = TLS13_ALERT_INTERNAL_ERROR; 476 477 if (!tls13_legacy_servername_process(ctx, &alert)) { 478 ctx->alert = alert; 479 return 0; 480 } 481 482 return 1; 483 } 484 485 int 486 tls13_server_hello_send(struct tls13_ctx *ctx, CBB *cbb) 487 { 488 if (ctx->hs->tls13.key_share == NULL) 489 return 0; 490 if (!tls13_key_share_generate(ctx->hs->tls13.key_share)) 491 return 0; 492 if (!tls13_servername_process(ctx)) 493 return 0; 494 495 ctx->hs->tls13.server_group = 0; 496 497 if (!tls13_server_hello_build(ctx, cbb, 0)) 498 return 0; 499 500 return 1; 501 } 502 503 int 504 tls13_server_hello_sent(struct tls13_ctx *ctx) 505 { 506 /* 507 * If the client has requested middlebox compatibility mode, 508 * we MUST send a dummy CCS following our first handshake message. 509 * See RFC 8446 Appendix D.4. 510 */ 511 if ((ctx->handshake_stage.hs_type & WITHOUT_HRR) && 512 ctx->hs->tls13.legacy_session_id_len > 0) 513 ctx->send_dummy_ccs_after = 1; 514 515 return tls13_server_engage_record_protection(ctx); 516 } 517 518 int 519 tls13_server_encrypted_extensions_send(struct tls13_ctx *ctx, CBB *cbb) 520 { 521 if (!tlsext_server_build(ctx->ssl, SSL_TLSEXT_MSG_EE, cbb)) 522 goto err; 523 524 return 1; 525 err: 526 return 0; 527 } 528 529 int 530 tls13_server_certificate_request_send(struct tls13_ctx *ctx, CBB *cbb) 531 { 532 CBB certificate_request_context; 533 534 if (!CBB_add_u8_length_prefixed(cbb, &certificate_request_context)) 535 goto err; 536 if (!tlsext_server_build(ctx->ssl, SSL_TLSEXT_MSG_CR, cbb)) 537 goto err; 538 539 if (!CBB_flush(cbb)) 540 goto err; 541 542 return 1; 543 err: 544 return 0; 545 } 546 547 static int 548 tls13_server_check_certificate(struct tls13_ctx *ctx, CERT_PKEY *cpk, 549 int *ok, const struct ssl_sigalg **out_sigalg) 550 { 551 const struct ssl_sigalg *sigalg; 552 SSL *s = ctx->ssl; 553 554 *ok = 0; 555 *out_sigalg = NULL; 556 557 if (cpk->x509 == NULL || cpk->privatekey == NULL) 558 goto done; 559 560 /* 561 * The digitalSignature bit MUST be set if the Key Usage extension is 562 * present as per RFC 8446 section 4.4.2.2. 563 */ 564 if (!(X509_get_key_usage(cpk->x509) & X509v3_KU_DIGITAL_SIGNATURE)) 565 goto done; 566 567 if ((sigalg = ssl_sigalg_select(s, cpk->privatekey)) == NULL) 568 goto done; 569 570 *ok = 1; 571 *out_sigalg = sigalg; 572 573 done: 574 return 1; 575 } 576 577 static int 578 tls13_server_select_certificate(struct tls13_ctx *ctx, CERT_PKEY **out_cpk, 579 const struct ssl_sigalg **out_sigalg) 580 { 581 SSL *s = ctx->ssl; 582 const struct ssl_sigalg *sigalg; 583 CERT_PKEY *cpk; 584 int cert_ok; 585 586 *out_cpk = NULL; 587 *out_sigalg = NULL; 588 589 cpk = &s->cert->pkeys[SSL_PKEY_ECC]; 590 if (!tls13_server_check_certificate(ctx, cpk, &cert_ok, &sigalg)) 591 return 0; 592 if (cert_ok) 593 goto done; 594 595 cpk = &s->cert->pkeys[SSL_PKEY_RSA]; 596 if (!tls13_server_check_certificate(ctx, cpk, &cert_ok, &sigalg)) 597 return 0; 598 if (cert_ok) 599 goto done; 600 601 cpk = NULL; 602 sigalg = NULL; 603 604 done: 605 *out_cpk = cpk; 606 *out_sigalg = sigalg; 607 608 return 1; 609 } 610 611 int 612 tls13_server_certificate_send(struct tls13_ctx *ctx, CBB *cbb) 613 { 614 SSL *s = ctx->ssl; 615 CBB cert_request_context, cert_list; 616 const struct ssl_sigalg *sigalg; 617 X509_STORE_CTX *xsc = NULL; 618 STACK_OF(X509) *chain; 619 CERT_PKEY *cpk; 620 X509 *cert; 621 int i, ret = 0; 622 623 if (!tls13_server_select_certificate(ctx, &cpk, &sigalg)) 624 goto err; 625 626 if (cpk == NULL) { 627 /* A server must always provide a certificate. */ 628 ctx->alert = TLS13_ALERT_HANDSHAKE_FAILURE; 629 tls13_set_errorx(ctx, TLS13_ERR_NO_CERTIFICATE, 0, 630 "no server certificate", NULL); 631 goto err; 632 } 633 634 ctx->hs->tls13.cpk = cpk; 635 ctx->hs->our_sigalg = sigalg; 636 637 if ((chain = cpk->chain) == NULL) 638 chain = s->ctx->extra_certs; 639 640 if (chain == NULL && !(s->internal->mode & SSL_MODE_NO_AUTO_CHAIN)) { 641 if ((xsc = X509_STORE_CTX_new()) == NULL) 642 goto err; 643 if (!X509_STORE_CTX_init(xsc, s->ctx->cert_store, cpk->x509, NULL)) 644 goto err; 645 X509_VERIFY_PARAM_set_flags(X509_STORE_CTX_get0_param(xsc), 646 X509_V_FLAG_LEGACY_VERIFY); 647 X509_verify_cert(xsc); 648 ERR_clear_error(); 649 chain = X509_STORE_CTX_get0_chain(xsc); 650 } 651 652 if (!CBB_add_u8_length_prefixed(cbb, &cert_request_context)) 653 goto err; 654 if (!CBB_add_u24_length_prefixed(cbb, &cert_list)) 655 goto err; 656 657 if (!tls13_cert_add(ctx, &cert_list, cpk->x509, tlsext_server_build)) 658 goto err; 659 660 for (i = 0; i < sk_X509_num(chain); i++) { 661 cert = sk_X509_value(chain, i); 662 663 /* 664 * In the case of auto chain, the leaf certificate will be at 665 * the top of the chain - skip over it as we've already added 666 * it earlier. 667 */ 668 if (i == 0 && cert == cpk->x509) 669 continue; 670 671 /* 672 * XXX we don't send extensions with chain certs to avoid sending 673 * a leaf ocsp staple with the chain certs. This needs to get 674 * fixed. 675 */ 676 if (!tls13_cert_add(ctx, &cert_list, cert, NULL)) 677 goto err; 678 } 679 680 if (!CBB_flush(cbb)) 681 goto err; 682 683 ret = 1; 684 685 err: 686 X509_STORE_CTX_free(xsc); 687 688 return ret; 689 } 690 691 int 692 tls13_server_certificate_verify_send(struct tls13_ctx *ctx, CBB *cbb) 693 { 694 const struct ssl_sigalg *sigalg; 695 uint8_t *sig = NULL, *sig_content = NULL; 696 size_t sig_len, sig_content_len; 697 EVP_MD_CTX *mdctx = NULL; 698 EVP_PKEY_CTX *pctx; 699 EVP_PKEY *pkey; 700 const CERT_PKEY *cpk; 701 CBB sig_cbb; 702 int ret = 0; 703 704 memset(&sig_cbb, 0, sizeof(sig_cbb)); 705 706 if ((cpk = ctx->hs->tls13.cpk) == NULL) 707 goto err; 708 if ((sigalg = ctx->hs->our_sigalg) == NULL) 709 goto err; 710 pkey = cpk->privatekey; 711 712 if (!CBB_init(&sig_cbb, 0)) 713 goto err; 714 if (!CBB_add_bytes(&sig_cbb, tls13_cert_verify_pad, 715 sizeof(tls13_cert_verify_pad))) 716 goto err; 717 if (!CBB_add_bytes(&sig_cbb, tls13_cert_server_verify_context, 718 strlen(tls13_cert_server_verify_context))) 719 goto err; 720 if (!CBB_add_u8(&sig_cbb, 0)) 721 goto err; 722 if (!CBB_add_bytes(&sig_cbb, ctx->hs->tls13.transcript_hash, 723 ctx->hs->tls13.transcript_hash_len)) 724 goto err; 725 if (!CBB_finish(&sig_cbb, &sig_content, &sig_content_len)) 726 goto err; 727 728 if ((mdctx = EVP_MD_CTX_new()) == NULL) 729 goto err; 730 if (!EVP_DigestSignInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) 731 goto err; 732 if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { 733 if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) 734 goto err; 735 if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) 736 goto err; 737 } 738 if (!EVP_DigestSignUpdate(mdctx, sig_content, sig_content_len)) 739 goto err; 740 if (EVP_DigestSignFinal(mdctx, NULL, &sig_len) <= 0) 741 goto err; 742 if ((sig = calloc(1, sig_len)) == NULL) 743 goto err; 744 if (EVP_DigestSignFinal(mdctx, sig, &sig_len) <= 0) 745 goto err; 746 747 if (!CBB_add_u16(cbb, sigalg->value)) 748 goto err; 749 if (!CBB_add_u16_length_prefixed(cbb, &sig_cbb)) 750 goto err; 751 if (!CBB_add_bytes(&sig_cbb, sig, sig_len)) 752 goto err; 753 754 if (!CBB_flush(cbb)) 755 goto err; 756 757 ret = 1; 758 759 err: 760 if (!ret && ctx->alert == 0) 761 ctx->alert = TLS13_ALERT_INTERNAL_ERROR; 762 763 CBB_cleanup(&sig_cbb); 764 EVP_MD_CTX_free(mdctx); 765 free(sig_content); 766 free(sig); 767 768 return ret; 769 } 770 771 int 772 tls13_server_finished_send(struct tls13_ctx *ctx, CBB *cbb) 773 { 774 struct tls13_secrets *secrets = ctx->hs->tls13.secrets; 775 struct tls13_secret context = { .data = "", .len = 0 }; 776 struct tls13_secret finished_key = { .data = NULL, .len = 0 } ; 777 uint8_t transcript_hash[EVP_MAX_MD_SIZE]; 778 size_t transcript_hash_len; 779 uint8_t *verify_data; 780 size_t verify_data_len; 781 unsigned int hlen; 782 HMAC_CTX *hmac_ctx = NULL; 783 CBS cbs; 784 int ret = 0; 785 786 if (!tls13_secret_init(&finished_key, EVP_MD_size(ctx->hash))) 787 goto err; 788 789 if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, 790 &secrets->server_handshake_traffic, "finished", 791 &context)) 792 goto err; 793 794 if (!tls1_transcript_hash_value(ctx->ssl, transcript_hash, 795 sizeof(transcript_hash), &transcript_hash_len)) 796 goto err; 797 798 if ((hmac_ctx = HMAC_CTX_new()) == NULL) 799 goto err; 800 if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, 801 ctx->hash, NULL)) 802 goto err; 803 if (!HMAC_Update(hmac_ctx, transcript_hash, transcript_hash_len)) 804 goto err; 805 806 verify_data_len = HMAC_size(hmac_ctx); 807 if (!CBB_add_space(cbb, &verify_data, verify_data_len)) 808 goto err; 809 if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) 810 goto err; 811 if (hlen != verify_data_len) 812 goto err; 813 814 CBS_init(&cbs, verify_data, verify_data_len); 815 if (!CBS_write_bytes(&cbs, ctx->hs->finished, 816 sizeof(ctx->hs->finished), &ctx->hs->finished_len)) 817 goto err; 818 819 ret = 1; 820 821 err: 822 tls13_secret_cleanup(&finished_key); 823 HMAC_CTX_free(hmac_ctx); 824 825 return ret; 826 } 827 828 int 829 tls13_server_finished_sent(struct tls13_ctx *ctx) 830 { 831 struct tls13_secrets *secrets = ctx->hs->tls13.secrets; 832 struct tls13_secret context = { .data = "", .len = 0 }; 833 834 /* 835 * Derive application traffic keys. 836 */ 837 context.data = ctx->hs->tls13.transcript_hash; 838 context.len = ctx->hs->tls13.transcript_hash_len; 839 840 if (!tls13_derive_application_secrets(secrets, &context)) 841 return 0; 842 843 /* 844 * Any records following the server finished message must be encrypted 845 * using the server application traffic keys. 846 */ 847 return tls13_record_layer_set_write_traffic_key(ctx->rl, 848 &secrets->server_application_traffic); 849 } 850 851 int 852 tls13_client_certificate_recv(struct tls13_ctx *ctx, CBS *cbs) 853 { 854 CBS cert_request_context, cert_list, cert_data, cert_exts; 855 struct stack_st_X509 *certs = NULL; 856 SSL *s = ctx->ssl; 857 X509 *cert = NULL; 858 EVP_PKEY *pkey; 859 const uint8_t *p; 860 int cert_idx; 861 int ret = 0; 862 863 if (!CBS_get_u8_length_prefixed(cbs, &cert_request_context)) 864 goto err; 865 if (CBS_len(&cert_request_context) != 0) 866 goto err; 867 if (!CBS_get_u24_length_prefixed(cbs, &cert_list)) 868 goto err; 869 if (CBS_len(&cert_list) == 0) { 870 if (!(s->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT)) 871 return 1; 872 ctx->alert = TLS13_ALERT_CERTIFICATE_REQUIRED; 873 tls13_set_errorx(ctx, TLS13_ERR_NO_PEER_CERTIFICATE, 0, 874 "peer did not provide a certificate", NULL); 875 goto err; 876 } 877 878 if ((certs = sk_X509_new_null()) == NULL) 879 goto err; 880 while (CBS_len(&cert_list) > 0) { 881 if (!CBS_get_u24_length_prefixed(&cert_list, &cert_data)) 882 goto err; 883 if (!CBS_get_u16_length_prefixed(&cert_list, &cert_exts)) 884 goto err; 885 886 p = CBS_data(&cert_data); 887 if ((cert = d2i_X509(NULL, &p, CBS_len(&cert_data))) == NULL) 888 goto err; 889 if (p != CBS_data(&cert_data) + CBS_len(&cert_data)) 890 goto err; 891 892 if (!sk_X509_push(certs, cert)) 893 goto err; 894 895 cert = NULL; 896 } 897 898 /* 899 * At this stage we still have no proof of possession. As such, it would 900 * be preferable to keep the chain and verify once we have successfully 901 * processed the CertificateVerify message. 902 */ 903 if (ssl_verify_cert_chain(s, certs) <= 0) { 904 ctx->alert = ssl_verify_alarm_type(s->verify_result); 905 tls13_set_errorx(ctx, TLS13_ERR_VERIFY_FAILED, 0, 906 "failed to verify peer certificate", NULL); 907 goto err; 908 } 909 ERR_clear_error(); 910 911 cert = sk_X509_value(certs, 0); 912 X509_up_ref(cert); 913 914 if ((pkey = X509_get0_pubkey(cert)) == NULL) 915 goto err; 916 if (EVP_PKEY_missing_parameters(pkey)) 917 goto err; 918 if ((cert_idx = ssl_cert_type(cert, pkey)) < 0) 919 goto err; 920 921 ssl_sess_cert_free(s->session->sess_cert); 922 if ((s->session->sess_cert = ssl_sess_cert_new()) == NULL) 923 goto err; 924 925 s->session->sess_cert->cert_chain = certs; 926 certs = NULL; 927 928 X509_up_ref(cert); 929 s->session->sess_cert->peer_pkeys[cert_idx].x509 = cert; 930 s->session->sess_cert->peer_key = &(s->session->sess_cert->peer_pkeys[cert_idx]); 931 932 X509_free(s->session->peer); 933 934 X509_up_ref(cert); 935 s->session->peer = cert; 936 s->session->verify_result = s->verify_result; 937 938 ctx->handshake_stage.hs_type |= WITH_CCV; 939 ret = 1; 940 941 err: 942 sk_X509_pop_free(certs, X509_free); 943 X509_free(cert); 944 945 return ret; 946 } 947 948 int 949 tls13_client_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs) 950 { 951 const struct ssl_sigalg *sigalg; 952 uint16_t signature_scheme; 953 uint8_t *sig_content = NULL; 954 size_t sig_content_len; 955 EVP_MD_CTX *mdctx = NULL; 956 EVP_PKEY_CTX *pctx; 957 EVP_PKEY *pkey; 958 X509 *cert; 959 CBS signature; 960 CBB cbb; 961 int ret = 0; 962 963 memset(&cbb, 0, sizeof(cbb)); 964 965 if (!CBS_get_u16(cbs, &signature_scheme)) 966 goto err; 967 if (!CBS_get_u16_length_prefixed(cbs, &signature)) 968 goto err; 969 970 if (!CBB_init(&cbb, 0)) 971 goto err; 972 if (!CBB_add_bytes(&cbb, tls13_cert_verify_pad, 973 sizeof(tls13_cert_verify_pad))) 974 goto err; 975 if (!CBB_add_bytes(&cbb, tls13_cert_client_verify_context, 976 strlen(tls13_cert_client_verify_context))) 977 goto err; 978 if (!CBB_add_u8(&cbb, 0)) 979 goto err; 980 if (!CBB_add_bytes(&cbb, ctx->hs->tls13.transcript_hash, 981 ctx->hs->tls13.transcript_hash_len)) 982 goto err; 983 if (!CBB_finish(&cbb, &sig_content, &sig_content_len)) 984 goto err; 985 986 if ((cert = ctx->ssl->session->peer) == NULL) 987 goto err; 988 if ((pkey = X509_get0_pubkey(cert)) == NULL) 989 goto err; 990 if ((sigalg = ssl_sigalg_for_peer(ctx->ssl, pkey, 991 signature_scheme)) == NULL) 992 goto err; 993 ctx->hs->peer_sigalg = sigalg; 994 995 if (CBS_len(&signature) > EVP_PKEY_size(pkey)) 996 goto err; 997 998 if ((mdctx = EVP_MD_CTX_new()) == NULL) 999 goto err; 1000 if (!EVP_DigestVerifyInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) 1001 goto err; 1002 if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { 1003 if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) 1004 goto err; 1005 if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) 1006 goto err; 1007 } 1008 if (!EVP_DigestVerifyUpdate(mdctx, sig_content, sig_content_len)) { 1009 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 1010 goto err; 1011 } 1012 if (EVP_DigestVerifyFinal(mdctx, CBS_data(&signature), 1013 CBS_len(&signature)) <= 0) { 1014 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 1015 goto err; 1016 } 1017 1018 ret = 1; 1019 1020 err: 1021 if (!ret && ctx->alert == 0) 1022 ctx->alert = TLS13_ALERT_DECODE_ERROR; 1023 1024 CBB_cleanup(&cbb); 1025 EVP_MD_CTX_free(mdctx); 1026 free(sig_content); 1027 1028 return ret; 1029 } 1030 1031 int 1032 tls13_client_end_of_early_data_recv(struct tls13_ctx *ctx, CBS *cbs) 1033 { 1034 return 0; 1035 } 1036 1037 int 1038 tls13_client_finished_recv(struct tls13_ctx *ctx, CBS *cbs) 1039 { 1040 struct tls13_secrets *secrets = ctx->hs->tls13.secrets; 1041 struct tls13_secret context = { .data = "", .len = 0 }; 1042 struct tls13_secret finished_key; 1043 uint8_t *verify_data = NULL; 1044 size_t verify_data_len; 1045 uint8_t key[EVP_MAX_MD_SIZE]; 1046 HMAC_CTX *hmac_ctx = NULL; 1047 unsigned int hlen; 1048 int ret = 0; 1049 1050 /* 1051 * Verify client finished. 1052 */ 1053 finished_key.data = key; 1054 finished_key.len = EVP_MD_size(ctx->hash); 1055 1056 if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, 1057 &secrets->client_handshake_traffic, "finished", 1058 &context)) 1059 goto err; 1060 1061 if ((hmac_ctx = HMAC_CTX_new()) == NULL) 1062 goto err; 1063 if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, 1064 ctx->hash, NULL)) 1065 goto err; 1066 if (!HMAC_Update(hmac_ctx, ctx->hs->tls13.transcript_hash, 1067 ctx->hs->tls13.transcript_hash_len)) 1068 goto err; 1069 verify_data_len = HMAC_size(hmac_ctx); 1070 if ((verify_data = calloc(1, verify_data_len)) == NULL) 1071 goto err; 1072 if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) 1073 goto err; 1074 if (hlen != verify_data_len) 1075 goto err; 1076 1077 if (!CBS_mem_equal(cbs, verify_data, verify_data_len)) { 1078 ctx->alert = TLS13_ALERT_DECRYPT_ERROR; 1079 goto err; 1080 } 1081 1082 if (!CBS_write_bytes(cbs, ctx->hs->peer_finished, 1083 sizeof(ctx->hs->peer_finished), 1084 &ctx->hs->peer_finished_len)) 1085 goto err; 1086 1087 if (!CBS_skip(cbs, verify_data_len)) 1088 goto err; 1089 1090 /* 1091 * Any records following the client finished message must be encrypted 1092 * using the client application traffic keys. 1093 */ 1094 if (!tls13_record_layer_set_read_traffic_key(ctx->rl, 1095 &secrets->client_application_traffic)) 1096 goto err; 1097 1098 tls13_record_layer_allow_ccs(ctx->rl, 0); 1099 1100 ret = 1; 1101 1102 err: 1103 HMAC_CTX_free(hmac_ctx); 1104 free(verify_data); 1105 1106 return ret; 1107 } 1108