ssl_tls13_server.c (127338B)
1 /* 2 * TLS 1.3 server-side functions 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 6 */ 7 8 #include "common.h" 9 10 #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3) 11 12 #include "debug_internal.h" 13 #include "mbedtls/error.h" 14 #include "mbedtls/platform.h" 15 #include "mbedtls/constant_time.h" 16 #include "mbedtls/oid.h" 17 #include "mbedtls/psa_util.h" 18 19 #include "ssl_misc.h" 20 #include "ssl_tls13_keys.h" 21 #include "ssl_debug_helpers.h" 22 23 24 static const mbedtls_ssl_ciphersuite_t *ssl_tls13_validate_peer_ciphersuite( 25 mbedtls_ssl_context *ssl, 26 unsigned int cipher_suite) 27 { 28 const mbedtls_ssl_ciphersuite_t *ciphersuite_info; 29 if (!mbedtls_ssl_tls13_cipher_suite_is_offered(ssl, cipher_suite)) { 30 return NULL; 31 } 32 33 ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(cipher_suite); 34 if ((mbedtls_ssl_validate_ciphersuite(ssl, ciphersuite_info, 35 ssl->tls_version, 36 ssl->tls_version) != 0)) { 37 return NULL; 38 } 39 return ciphersuite_info; 40 } 41 42 static void ssl_tls13_select_ciphersuite( 43 mbedtls_ssl_context *ssl, 44 const unsigned char *cipher_suites, 45 const unsigned char *cipher_suites_end, 46 int psk_ciphersuite_id, 47 psa_algorithm_t psk_hash_alg, 48 const mbedtls_ssl_ciphersuite_t **selected_ciphersuite_info) 49 { 50 *selected_ciphersuite_info = NULL; 51 52 /* 53 * In a compliant ClientHello the byte-length of the list of ciphersuites 54 * is even and this function relies on this fact. This should have been 55 * checked in the main ClientHello parsing function. Double check here. 56 */ 57 if ((cipher_suites_end - cipher_suites) & 1) { 58 return; 59 } 60 61 for (const unsigned char *p = cipher_suites; 62 p < cipher_suites_end; p += 2) { 63 /* 64 * "cipher_suites_end - p is even" is an invariant of the loop. As 65 * cipher_suites_end - p > 0, we have cipher_suites_end - p >= 2 and it 66 * is thus safe to read two bytes. 67 */ 68 uint16_t id = MBEDTLS_GET_UINT16_BE(p, 0); 69 70 const mbedtls_ssl_ciphersuite_t *info = 71 ssl_tls13_validate_peer_ciphersuite(ssl, id); 72 if (info == NULL) { 73 continue; 74 } 75 76 /* 77 * If a valid PSK ciphersuite identifier has been passed in, we want 78 * an exact match. 79 */ 80 if (psk_ciphersuite_id != 0) { 81 if (id != psk_ciphersuite_id) { 82 continue; 83 } 84 } else if (psk_hash_alg != PSA_ALG_NONE) { 85 if (mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) info->mac) != 86 psk_hash_alg) { 87 continue; 88 } 89 } 90 91 *selected_ciphersuite_info = info; 92 return; 93 } 94 95 MBEDTLS_SSL_DEBUG_MSG(1, ("No matched ciphersuite, psk_ciphersuite_id=%x, psk_hash_alg=%lx", 96 (unsigned) psk_ciphersuite_id, 97 (unsigned long) psk_hash_alg)); 98 } 99 100 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 101 /* From RFC 8446: 102 * 103 * enum { psk_ke(0), psk_dhe_ke(1), (255) } PskKeyExchangeMode; 104 * struct { 105 * PskKeyExchangeMode ke_modes<1..255>; 106 * } PskKeyExchangeModes; 107 */ 108 MBEDTLS_CHECK_RETURN_CRITICAL 109 static int ssl_tls13_parse_key_exchange_modes_ext(mbedtls_ssl_context *ssl, 110 const unsigned char *buf, 111 const unsigned char *end) 112 { 113 const unsigned char *p = buf; 114 size_t ke_modes_len; 115 int ke_modes = 0; 116 117 /* Read ke_modes length (1 Byte) */ 118 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); 119 ke_modes_len = *p++; 120 /* Currently, there are only two PSK modes, so even without looking 121 * at the content, something's wrong if the list has more than 2 items. */ 122 if (ke_modes_len > 2) { 123 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, 124 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 125 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 126 } 127 128 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, ke_modes_len); 129 130 while (ke_modes_len-- != 0) { 131 switch (*p++) { 132 case MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE: 133 ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; 134 MBEDTLS_SSL_DEBUG_MSG(3, ("Found PSK KEX MODE")); 135 break; 136 case MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE: 137 ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; 138 MBEDTLS_SSL_DEBUG_MSG(3, ("Found PSK_EPHEMERAL KEX MODE")); 139 break; 140 default: 141 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, 142 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 143 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 144 } 145 } 146 147 ssl->handshake->tls13_kex_modes = ke_modes; 148 return 0; 149 } 150 151 /* 152 * Non-error return values of 153 * ssl_tls13_offered_psks_check_identity_match_ticket() and 154 * ssl_tls13_offered_psks_check_identity_match(). They are positive to 155 * not collide with error codes that are negative. Zero 156 * (SSL_TLS1_3_PSK_IDENTITY_MATCH) in case of success as it may be propagated 157 * up by the callers of this function as a generic success condition. 158 * 159 * The return value SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE means 160 * that the pre-shared-key identity matches that of a ticket or an externally- 161 * provisioned pre-shared-key. We have thus been able to retrieve the 162 * attributes of the pre-shared-key but at least one of them does not meet 163 * some criteria and the pre-shared-key cannot be used. For example, a ticket 164 * is expired or its version is not TLS 1.3. Note eventually that the return 165 * value SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE does not have 166 * anything to do with binder check. A binder check is done only when a 167 * suitable pre-shared-key has been selected and only for that selected 168 * pre-shared-key: if the binder check fails, we fail the handshake and we do 169 * not try to find another pre-shared-key for which the binder check would 170 * succeed as recommended by the specification. 171 */ 172 #define SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH 2 173 #define SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE 1 174 #define SSL_TLS1_3_PSK_IDENTITY_MATCH 0 175 176 MBEDTLS_CHECK_RETURN_CRITICAL 177 static int ssl_tls13_key_exchange_is_psk_available(mbedtls_ssl_context *ssl); 178 MBEDTLS_CHECK_RETURN_CRITICAL 179 static int ssl_tls13_key_exchange_is_psk_ephemeral_available(mbedtls_ssl_context *ssl); 180 181 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 182 MBEDTLS_CHECK_RETURN_CRITICAL 183 static int ssl_tls13_offered_psks_check_identity_match_ticket( 184 mbedtls_ssl_context *ssl, 185 const unsigned char *identity, 186 size_t identity_len, 187 uint32_t obfuscated_ticket_age, 188 mbedtls_ssl_session *session) 189 { 190 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 191 unsigned char *ticket_buffer; 192 #if defined(MBEDTLS_HAVE_TIME) 193 mbedtls_ms_time_t now; 194 mbedtls_ms_time_t server_age; 195 uint32_t client_age; 196 mbedtls_ms_time_t age_diff; 197 #endif 198 199 ((void) obfuscated_ticket_age); 200 201 MBEDTLS_SSL_DEBUG_MSG(2, ("=> check_identity_match_ticket")); 202 203 /* Ticket parser is not configured, Skip */ 204 if (ssl->conf->f_ticket_parse == NULL || identity_len == 0) { 205 return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; 206 } 207 208 /* We create a copy of the encrypted ticket since the ticket parsing 209 * function is allowed to use its input buffer as an output buffer 210 * (in-place decryption). We do, however, need the original buffer for 211 * computing the PSK binder value. 212 */ 213 ticket_buffer = mbedtls_calloc(1, identity_len); 214 if (ticket_buffer == NULL) { 215 return MBEDTLS_ERR_SSL_ALLOC_FAILED; 216 } 217 memcpy(ticket_buffer, identity, identity_len); 218 219 ret = ssl->conf->f_ticket_parse(ssl->conf->p_ticket, 220 session, 221 ticket_buffer, identity_len); 222 switch (ret) { 223 case 0: 224 ret = SSL_TLS1_3_PSK_IDENTITY_MATCH; 225 break; 226 227 case MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED: 228 MBEDTLS_SSL_DEBUG_MSG(3, ("ticket is expired")); 229 ret = SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; 230 break; 231 232 case MBEDTLS_ERR_SSL_INVALID_MAC: 233 MBEDTLS_SSL_DEBUG_MSG(3, ("ticket is not authentic")); 234 ret = SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; 235 break; 236 237 default: 238 MBEDTLS_SSL_DEBUG_RET(1, "ticket_parse", ret); 239 ret = SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; 240 } 241 242 /* We delete the temporary buffer */ 243 mbedtls_free(ticket_buffer); 244 245 if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { 246 goto exit; 247 } 248 249 /* 250 * The identity matches that of a ticket. Now check that it has suitable 251 * attributes and bet it will not be the case. 252 */ 253 ret = SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; 254 255 if (session->tls_version != MBEDTLS_SSL_VERSION_TLS1_3) { 256 MBEDTLS_SSL_DEBUG_MSG(3, ("Ticket TLS version is not 1.3.")); 257 goto exit; 258 } 259 260 #if defined(MBEDTLS_HAVE_TIME) 261 now = mbedtls_ms_time(); 262 263 if (now < session->ticket_creation_time) { 264 MBEDTLS_SSL_DEBUG_MSG( 265 3, ("Invalid ticket creation time ( now = %" MBEDTLS_PRINTF_MS_TIME 266 ", creation_time = %" MBEDTLS_PRINTF_MS_TIME " )", 267 now, session->ticket_creation_time)); 268 goto exit; 269 } 270 271 server_age = now - session->ticket_creation_time; 272 273 /* RFC 8446 section 4.6.1 274 * 275 * Servers MUST NOT use any value greater than 604800 seconds (7 days). 276 * 277 * RFC 8446 section 4.2.11.1 278 * 279 * Clients MUST NOT attempt to use tickets which have ages greater than 280 * the "ticket_lifetime" value which was provided with the ticket. 281 * 282 */ 283 if (server_age > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME * 1000) { 284 MBEDTLS_SSL_DEBUG_MSG( 285 3, ("Ticket age exceeds limitation ticket_age = %" MBEDTLS_PRINTF_MS_TIME, 286 server_age)); 287 goto exit; 288 } 289 290 /* RFC 8446 section 4.2.10 291 * 292 * For PSKs provisioned via NewSessionTicket, a server MUST validate that 293 * the ticket age for the selected PSK identity (computed by subtracting 294 * ticket_age_add from PskIdentity.obfuscated_ticket_age modulo 2^32) is 295 * within a small tolerance of the time since the ticket was issued. 296 * 297 * NOTE: The typical accuracy of an RTC crystal is ±100 to ±20 parts per 298 * million (360 to 72 milliseconds per hour). Default tolerance 299 * window is 6s, thus in the worst case clients and servers must 300 * sync up their system time every 6000/360/2~=8 hours. 301 */ 302 client_age = obfuscated_ticket_age - session->ticket_age_add; 303 age_diff = server_age - (mbedtls_ms_time_t) client_age; 304 if (age_diff < -MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE || 305 age_diff > MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE) { 306 MBEDTLS_SSL_DEBUG_MSG( 307 3, ("Ticket age outside tolerance window ( diff = %" 308 MBEDTLS_PRINTF_MS_TIME ")", 309 age_diff)); 310 goto exit; 311 } 312 #endif /* MBEDTLS_HAVE_TIME */ 313 314 /* 315 * All good, we have found a suitable ticket. 316 */ 317 ret = SSL_TLS1_3_PSK_IDENTITY_MATCH; 318 319 exit: 320 if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { 321 mbedtls_ssl_session_free(session); 322 } 323 324 MBEDTLS_SSL_DEBUG_MSG(2, ("<= check_identity_match_ticket")); 325 return ret; 326 } 327 #endif /* MBEDTLS_SSL_SESSION_TICKETS */ 328 329 MBEDTLS_CHECK_RETURN_CRITICAL 330 static int ssl_tls13_offered_psks_check_identity_match( 331 mbedtls_ssl_context *ssl, 332 const unsigned char *identity, 333 size_t identity_len, 334 uint32_t obfuscated_ticket_age, 335 int *psk_type, 336 mbedtls_ssl_session *session) 337 { 338 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 339 340 ((void) session); 341 ((void) obfuscated_ticket_age); 342 *psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL; 343 344 MBEDTLS_SSL_DEBUG_BUF(4, "identity", identity, identity_len); 345 346 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 347 ret = ssl_tls13_offered_psks_check_identity_match_ticket( 348 ssl, identity, identity_len, obfuscated_ticket_age, session); 349 if (ret == SSL_TLS1_3_PSK_IDENTITY_MATCH) { 350 *psk_type = MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION; 351 ret = mbedtls_ssl_set_hs_psk(ssl, 352 session->resumption_key, 353 session->resumption_key_len); 354 if (ret != 0) { 355 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret); 356 return ret; 357 } 358 359 MBEDTLS_SSL_DEBUG_BUF(4, "Ticket-resumed PSK:", 360 session->resumption_key, 361 session->resumption_key_len); 362 MBEDTLS_SSL_DEBUG_MSG(4, ("ticket: obfuscated_ticket_age: %u", 363 (unsigned) obfuscated_ticket_age)); 364 return SSL_TLS1_3_PSK_IDENTITY_MATCH; 365 } else if (ret == SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE) { 366 return SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; 367 } 368 #endif /* MBEDTLS_SSL_SESSION_TICKETS */ 369 370 /* Check identity with external configured function */ 371 if (ssl->conf->f_psk != NULL) { 372 if (ssl->conf->f_psk( 373 ssl->conf->p_psk, ssl, identity, identity_len) == 0) { 374 return SSL_TLS1_3_PSK_IDENTITY_MATCH; 375 } 376 return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; 377 } 378 379 MBEDTLS_SSL_DEBUG_BUF(5, "identity", identity, identity_len); 380 /* Check identity with pre-configured psk */ 381 if (ssl->conf->psk_identity != NULL && 382 identity_len == ssl->conf->psk_identity_len && 383 mbedtls_ct_memcmp(ssl->conf->psk_identity, 384 identity, identity_len) == 0) { 385 ret = mbedtls_ssl_set_hs_psk(ssl, ssl->conf->psk, ssl->conf->psk_len); 386 if (ret != 0) { 387 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret); 388 return ret; 389 } 390 return SSL_TLS1_3_PSK_IDENTITY_MATCH; 391 } 392 393 return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; 394 } 395 396 /* 397 * Non-error return values of ssl_tls13_offered_psks_check_binder_match(). 398 * They are positive to not collide with error codes that are negative. Zero 399 * (SSL_TLS1_3_BINDER_MATCH) in case of success as it may be propagated up 400 * by the callers of this function as a generic success condition. 401 */ 402 #define SSL_TLS1_3_BINDER_DOES_NOT_MATCH 1 403 #define SSL_TLS1_3_BINDER_MATCH 0 404 MBEDTLS_CHECK_RETURN_CRITICAL 405 static int ssl_tls13_offered_psks_check_binder_match( 406 mbedtls_ssl_context *ssl, 407 const unsigned char *binder, size_t binder_len, 408 int psk_type, psa_algorithm_t psk_hash_alg) 409 { 410 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 411 412 unsigned char transcript[PSA_HASH_MAX_SIZE]; 413 size_t transcript_len; 414 unsigned char *psk; 415 size_t psk_len; 416 unsigned char server_computed_binder[PSA_HASH_MAX_SIZE]; 417 418 if (binder_len != PSA_HASH_LENGTH(psk_hash_alg)) { 419 return SSL_TLS1_3_BINDER_DOES_NOT_MATCH; 420 } 421 422 /* Get current state of handshake transcript. */ 423 ret = mbedtls_ssl_get_handshake_transcript( 424 ssl, mbedtls_md_type_from_psa_alg(psk_hash_alg), 425 transcript, sizeof(transcript), &transcript_len); 426 if (ret != 0) { 427 return ret; 428 } 429 430 ret = mbedtls_ssl_tls13_export_handshake_psk(ssl, &psk, &psk_len); 431 if (ret != 0) { 432 return ret; 433 } 434 435 ret = mbedtls_ssl_tls13_create_psk_binder(ssl, psk_hash_alg, 436 psk, psk_len, psk_type, 437 transcript, 438 server_computed_binder); 439 #if defined(MBEDTLS_USE_PSA_CRYPTO) 440 mbedtls_free((void *) psk); 441 #endif 442 if (ret != 0) { 443 MBEDTLS_SSL_DEBUG_MSG(1, ("PSK binder calculation failed.")); 444 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 445 } 446 447 MBEDTLS_SSL_DEBUG_BUF(3, "psk binder ( computed ): ", 448 server_computed_binder, transcript_len); 449 MBEDTLS_SSL_DEBUG_BUF(3, "psk binder ( received ): ", binder, binder_len); 450 451 if (mbedtls_ct_memcmp(server_computed_binder, 452 binder, 453 PSA_HASH_LENGTH(psk_hash_alg)) == 0) { 454 return SSL_TLS1_3_BINDER_MATCH; 455 } 456 457 mbedtls_platform_zeroize(server_computed_binder, 458 sizeof(server_computed_binder)); 459 return SSL_TLS1_3_BINDER_DOES_NOT_MATCH; 460 } 461 462 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 463 MBEDTLS_CHECK_RETURN_CRITICAL 464 static int ssl_tls13_session_copy_ticket(mbedtls_ssl_session *dst, 465 const mbedtls_ssl_session *src) 466 { 467 dst->ticket_age_add = src->ticket_age_add; 468 dst->ticket_flags = src->ticket_flags; 469 dst->resumption_key_len = src->resumption_key_len; 470 if (src->resumption_key_len == 0) { 471 return MBEDTLS_ERR_SSL_INTERNAL_ERROR; 472 } 473 memcpy(dst->resumption_key, src->resumption_key, src->resumption_key_len); 474 475 #if defined(MBEDTLS_SSL_EARLY_DATA) 476 dst->max_early_data_size = src->max_early_data_size; 477 478 #if defined(MBEDTLS_SSL_ALPN) 479 int ret = mbedtls_ssl_session_set_ticket_alpn(dst, src->ticket_alpn); 480 if (ret != 0) { 481 return ret; 482 } 483 #endif /* MBEDTLS_SSL_ALPN */ 484 #endif /* MBEDTLS_SSL_EARLY_DATA*/ 485 486 return 0; 487 } 488 #endif /* MBEDTLS_SSL_SESSION_TICKETS */ 489 490 struct psk_attributes { 491 int type; 492 int key_exchange_mode; 493 const mbedtls_ssl_ciphersuite_t *ciphersuite_info; 494 }; 495 #define PSK_ATTRIBUTES_INIT { 0, 0, NULL } 496 497 /* Parser for pre_shared_key extension in client hello 498 * struct { 499 * opaque identity<1..2^16-1>; 500 * uint32 obfuscated_ticket_age; 501 * } PskIdentity; 502 * 503 * opaque PskBinderEntry<32..255>; 504 * 505 * struct { 506 * PskIdentity identities<7..2^16-1>; 507 * PskBinderEntry binders<33..2^16-1>; 508 * } OfferedPsks; 509 * 510 * struct { 511 * select (Handshake.msg_type) { 512 * case client_hello: OfferedPsks; 513 * .... 514 * }; 515 * } PreSharedKeyExtension; 516 */ 517 MBEDTLS_CHECK_RETURN_CRITICAL 518 static int ssl_tls13_parse_pre_shared_key_ext( 519 mbedtls_ssl_context *ssl, 520 const unsigned char *pre_shared_key_ext, 521 const unsigned char *pre_shared_key_ext_end, 522 const unsigned char *ciphersuites, 523 const unsigned char *ciphersuites_end, 524 struct psk_attributes *psk) 525 { 526 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 527 const unsigned char *identities = pre_shared_key_ext; 528 const unsigned char *p_identity_len; 529 size_t identities_len; 530 const unsigned char *identities_end; 531 const unsigned char *binders; 532 const unsigned char *p_binder_len; 533 size_t binders_len; 534 const unsigned char *binders_end; 535 int matched_identity = -1; 536 int identity_id = -1; 537 538 MBEDTLS_SSL_DEBUG_BUF(3, "pre_shared_key extension", 539 pre_shared_key_ext, 540 pre_shared_key_ext_end - pre_shared_key_ext); 541 542 /* identities_len 2 bytes 543 * identities_data >= 7 bytes 544 */ 545 MBEDTLS_SSL_CHK_BUF_READ_PTR(identities, pre_shared_key_ext_end, 7 + 2); 546 identities_len = MBEDTLS_GET_UINT16_BE(identities, 0); 547 p_identity_len = identities + 2; 548 MBEDTLS_SSL_CHK_BUF_READ_PTR(p_identity_len, pre_shared_key_ext_end, 549 identities_len); 550 identities_end = p_identity_len + identities_len; 551 552 /* binders_len 2 bytes 553 * binders >= 33 bytes 554 */ 555 binders = identities_end; 556 MBEDTLS_SSL_CHK_BUF_READ_PTR(binders, pre_shared_key_ext_end, 33 + 2); 557 binders_len = MBEDTLS_GET_UINT16_BE(binders, 0); 558 p_binder_len = binders + 2; 559 MBEDTLS_SSL_CHK_BUF_READ_PTR(p_binder_len, pre_shared_key_ext_end, binders_len); 560 binders_end = p_binder_len + binders_len; 561 562 ret = ssl->handshake->update_checksum(ssl, pre_shared_key_ext, 563 identities_end - pre_shared_key_ext); 564 if (0 != ret) { 565 MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); 566 return ret; 567 } 568 569 while (p_identity_len < identities_end && p_binder_len < binders_end) { 570 const unsigned char *identity; 571 size_t identity_len; 572 uint32_t obfuscated_ticket_age; 573 const unsigned char *binder; 574 size_t binder_len; 575 int psk_ciphersuite_id; 576 psa_algorithm_t psk_hash_alg; 577 int allowed_key_exchange_modes; 578 579 mbedtls_ssl_session session; 580 mbedtls_ssl_session_init(&session); 581 582 MBEDTLS_SSL_CHK_BUF_READ_PTR(p_identity_len, identities_end, 2 + 1 + 4); 583 identity_len = MBEDTLS_GET_UINT16_BE(p_identity_len, 0); 584 identity = p_identity_len + 2; 585 MBEDTLS_SSL_CHK_BUF_READ_PTR(identity, identities_end, identity_len + 4); 586 obfuscated_ticket_age = MBEDTLS_GET_UINT32_BE(identity, identity_len); 587 p_identity_len += identity_len + 6; 588 589 MBEDTLS_SSL_CHK_BUF_READ_PTR(p_binder_len, binders_end, 1 + 32); 590 binder_len = *p_binder_len; 591 binder = p_binder_len + 1; 592 MBEDTLS_SSL_CHK_BUF_READ_PTR(binder, binders_end, binder_len); 593 p_binder_len += binder_len + 1; 594 595 identity_id++; 596 if (matched_identity != -1) { 597 continue; 598 } 599 600 ret = ssl_tls13_offered_psks_check_identity_match( 601 ssl, identity, identity_len, obfuscated_ticket_age, 602 &psk->type, &session); 603 if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { 604 continue; 605 } 606 607 MBEDTLS_SSL_DEBUG_MSG(4, ("found matched identity")); 608 609 switch (psk->type) { 610 case MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL: 611 psk_ciphersuite_id = 0; 612 psk_hash_alg = PSA_ALG_SHA_256; 613 allowed_key_exchange_modes = 614 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL; 615 break; 616 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 617 case MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION: 618 psk_ciphersuite_id = session.ciphersuite; 619 psk_hash_alg = PSA_ALG_NONE; 620 ssl->session_negotiate->ticket_flags = session.ticket_flags; 621 allowed_key_exchange_modes = 622 session.ticket_flags & 623 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL; 624 break; 625 #endif 626 default: 627 return MBEDTLS_ERR_SSL_INTERNAL_ERROR; 628 } 629 630 psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE; 631 632 if ((allowed_key_exchange_modes & 633 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL) && 634 ssl_tls13_key_exchange_is_psk_ephemeral_available(ssl)) { 635 psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; 636 } else if ((allowed_key_exchange_modes & 637 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK) && 638 ssl_tls13_key_exchange_is_psk_available(ssl)) { 639 psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; 640 } 641 642 if (psk->key_exchange_mode == MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE) { 643 MBEDTLS_SSL_DEBUG_MSG(3, ("No suitable PSK key exchange mode")); 644 continue; 645 } 646 647 ssl_tls13_select_ciphersuite(ssl, ciphersuites, ciphersuites_end, 648 psk_ciphersuite_id, psk_hash_alg, 649 &psk->ciphersuite_info); 650 651 if (psk->ciphersuite_info == NULL) { 652 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 653 mbedtls_ssl_session_free(&session); 654 #endif 655 /* 656 * We consider finding a ciphersuite suitable for the PSK as part 657 * of the validation of its binder. Thus if we do not find one, we 658 * abort the handshake with a decrypt_error alert. 659 */ 660 MBEDTLS_SSL_PEND_FATAL_ALERT( 661 MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, 662 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 663 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 664 } 665 666 ret = ssl_tls13_offered_psks_check_binder_match( 667 ssl, binder, binder_len, psk->type, 668 mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) psk->ciphersuite_info->mac)); 669 if (ret != SSL_TLS1_3_BINDER_MATCH) { 670 /* For security reasons, the handshake should be aborted when we 671 * fail to validate a binder value. See RFC 8446 section 4.2.11.2 672 * and appendix E.6. */ 673 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 674 mbedtls_ssl_session_free(&session); 675 #endif 676 MBEDTLS_SSL_DEBUG_MSG(3, ("Invalid binder.")); 677 MBEDTLS_SSL_DEBUG_RET( 678 1, "ssl_tls13_offered_psks_check_binder_match", ret); 679 MBEDTLS_SSL_PEND_FATAL_ALERT( 680 MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, 681 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 682 return ret; 683 } 684 685 matched_identity = identity_id; 686 687 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 688 if (psk->type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION) { 689 ret = ssl_tls13_session_copy_ticket(ssl->session_negotiate, 690 &session); 691 mbedtls_ssl_session_free(&session); 692 if (ret != 0) { 693 return ret; 694 } 695 } 696 #endif /* MBEDTLS_SSL_SESSION_TICKETS */ 697 } 698 699 if (p_identity_len != identities_end || p_binder_len != binders_end) { 700 MBEDTLS_SSL_DEBUG_MSG(3, ("pre_shared_key extension decode error")); 701 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, 702 MBEDTLS_ERR_SSL_DECODE_ERROR); 703 return MBEDTLS_ERR_SSL_DECODE_ERROR; 704 } 705 706 /* Update the handshake transcript with the binder list. */ 707 ret = ssl->handshake->update_checksum( 708 ssl, identities_end, (size_t) (binders_end - identities_end)); 709 if (0 != ret) { 710 MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); 711 return ret; 712 } 713 if (matched_identity == -1) { 714 MBEDTLS_SSL_DEBUG_MSG(3, ("No usable PSK or ticket.")); 715 return MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY; 716 } 717 718 ssl->handshake->selected_identity = (uint16_t) matched_identity; 719 MBEDTLS_SSL_DEBUG_MSG(3, ("Pre shared key found")); 720 721 return 0; 722 } 723 724 /* 725 * struct { 726 * select ( Handshake.msg_type ) { 727 * .... 728 * case server_hello: 729 * uint16 selected_identity; 730 * } 731 * } PreSharedKeyExtension; 732 */ 733 static int ssl_tls13_write_server_pre_shared_key_ext(mbedtls_ssl_context *ssl, 734 unsigned char *buf, 735 unsigned char *end, 736 size_t *olen) 737 { 738 unsigned char *p = (unsigned char *) buf; 739 740 *olen = 0; 741 742 int not_using_psk = 0; 743 #if defined(MBEDTLS_USE_PSA_CRYPTO) 744 not_using_psk = (mbedtls_svc_key_id_is_null(ssl->handshake->psk_opaque)); 745 #else 746 not_using_psk = (ssl->handshake->psk == NULL); 747 #endif 748 if (not_using_psk) { 749 /* We shouldn't have called this extension writer unless we've 750 * chosen to use a PSK. */ 751 return MBEDTLS_ERR_SSL_INTERNAL_ERROR; 752 } 753 754 MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, adding pre_shared_key extension")); 755 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 6); 756 757 MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_PRE_SHARED_KEY, p, 0); 758 MBEDTLS_PUT_UINT16_BE(2, p, 2); 759 760 MBEDTLS_PUT_UINT16_BE(ssl->handshake->selected_identity, p, 4); 761 762 *olen = 6; 763 764 MBEDTLS_SSL_DEBUG_MSG(4, ("sent selected_identity: %u", 765 ssl->handshake->selected_identity)); 766 767 mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_PRE_SHARED_KEY); 768 769 return 0; 770 } 771 772 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ 773 774 /* From RFC 8446: 775 * struct { 776 * ProtocolVersion versions<2..254>; 777 * } SupportedVersions; 778 */ 779 MBEDTLS_CHECK_RETURN_CRITICAL 780 static int ssl_tls13_parse_supported_versions_ext(mbedtls_ssl_context *ssl, 781 const unsigned char *buf, 782 const unsigned char *end) 783 { 784 const unsigned char *p = buf; 785 size_t versions_len; 786 const unsigned char *versions_end; 787 uint16_t tls_version; 788 int found_supported_version = 0; 789 790 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); 791 versions_len = p[0]; 792 p += 1; 793 794 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, versions_len); 795 versions_end = p + versions_len; 796 while (p < versions_end) { 797 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, versions_end, 2); 798 tls_version = mbedtls_ssl_read_version(p, ssl->conf->transport); 799 p += 2; 800 801 if (MBEDTLS_SSL_VERSION_TLS1_3 == tls_version) { 802 found_supported_version = 1; 803 break; 804 } 805 806 if ((MBEDTLS_SSL_VERSION_TLS1_2 == tls_version) && 807 mbedtls_ssl_conf_is_tls12_enabled(ssl->conf)) { 808 found_supported_version = 1; 809 break; 810 } 811 } 812 813 if (!found_supported_version) { 814 MBEDTLS_SSL_DEBUG_MSG(1, ("No supported version found.")); 815 816 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, 817 MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); 818 return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; 819 } 820 821 MBEDTLS_SSL_DEBUG_MSG(1, ("Negotiated version: [%04x]", 822 (unsigned int) tls_version)); 823 824 return (int) tls_version; 825 } 826 827 #if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) 828 /* 829 * 830 * From RFC 8446: 831 * enum { 832 * ... (0xFFFF) 833 * } NamedGroup; 834 * struct { 835 * NamedGroup named_group_list<2..2^16-1>; 836 * } NamedGroupList; 837 */ 838 MBEDTLS_CHECK_RETURN_CRITICAL 839 static int ssl_tls13_parse_supported_groups_ext(mbedtls_ssl_context *ssl, 840 const unsigned char *buf, 841 const unsigned char *end) 842 { 843 const unsigned char *p = buf; 844 size_t named_group_list_len; 845 const unsigned char *named_group_list_end; 846 847 MBEDTLS_SSL_DEBUG_BUF(3, "supported_groups extension", p, end - buf); 848 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); 849 named_group_list_len = MBEDTLS_GET_UINT16_BE(p, 0); 850 p += 2; 851 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, named_group_list_len); 852 named_group_list_end = p + named_group_list_len; 853 ssl->handshake->hrr_selected_group = 0; 854 855 while (p < named_group_list_end) { 856 uint16_t named_group; 857 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, named_group_list_end, 2); 858 named_group = MBEDTLS_GET_UINT16_BE(p, 0); 859 p += 2; 860 861 MBEDTLS_SSL_DEBUG_MSG(2, 862 ("got named group: %s(%04x)", 863 mbedtls_ssl_named_group_to_str(named_group), 864 named_group)); 865 866 if (!mbedtls_ssl_named_group_is_offered(ssl, named_group) || 867 !mbedtls_ssl_named_group_is_supported(named_group) || 868 ssl->handshake->hrr_selected_group != 0) { 869 continue; 870 } 871 872 MBEDTLS_SSL_DEBUG_MSG(2, 873 ("add named group %s(%04x) into received list.", 874 mbedtls_ssl_named_group_to_str(named_group), 875 named_group)); 876 877 ssl->handshake->hrr_selected_group = named_group; 878 } 879 880 return 0; 881 882 } 883 #endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */ 884 885 #define SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH 1 886 887 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) 888 /* 889 * ssl_tls13_parse_key_shares_ext() verifies whether the information in the 890 * extension is correct and stores the first acceptable key share and its 891 * associated group. 892 * 893 * Possible return values are: 894 * - 0: Successful processing of the client provided key share extension. 895 * - SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH: The key shares provided by 896 * the client does not match a group supported by the server. A 897 * HelloRetryRequest will be needed. 898 * - A negative value for fatal errors. 899 */ 900 MBEDTLS_CHECK_RETURN_CRITICAL 901 static int ssl_tls13_parse_key_shares_ext(mbedtls_ssl_context *ssl, 902 const unsigned char *buf, 903 const unsigned char *end) 904 { 905 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 906 unsigned char const *p = buf; 907 unsigned char const *client_shares_end; 908 size_t client_shares_len; 909 910 /* From RFC 8446: 911 * 912 * struct { 913 * KeyShareEntry client_shares<0..2^16-1>; 914 * } KeyShareClientHello; 915 * 916 */ 917 918 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); 919 client_shares_len = MBEDTLS_GET_UINT16_BE(p, 0); 920 p += 2; 921 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, client_shares_len); 922 923 ssl->handshake->offered_group_id = 0; 924 client_shares_end = p + client_shares_len; 925 926 /* We try to find a suitable key share entry and copy it to the 927 * handshake context. Later, we have to find out whether we can do 928 * something with the provided key share or whether we have to 929 * dismiss it and send a HelloRetryRequest message. 930 */ 931 932 while (p < client_shares_end) { 933 uint16_t group; 934 size_t key_exchange_len; 935 const unsigned char *key_exchange; 936 937 /* 938 * struct { 939 * NamedGroup group; 940 * opaque key_exchange<1..2^16-1>; 941 * } KeyShareEntry; 942 */ 943 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, client_shares_end, 4); 944 group = MBEDTLS_GET_UINT16_BE(p, 0); 945 key_exchange_len = MBEDTLS_GET_UINT16_BE(p, 2); 946 p += 4; 947 key_exchange = p; 948 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, client_shares_end, key_exchange_len); 949 p += key_exchange_len; 950 951 /* Continue parsing even if we have already found a match, 952 * for input validation purposes. 953 */ 954 if (!mbedtls_ssl_named_group_is_offered(ssl, group) || 955 !mbedtls_ssl_named_group_is_supported(group) || 956 ssl->handshake->offered_group_id != 0) { 957 continue; 958 } 959 960 /* 961 * ECDHE and FFDHE groups are supported 962 */ 963 if (mbedtls_ssl_tls13_named_group_is_ecdhe(group) || 964 mbedtls_ssl_tls13_named_group_is_ffdh(group)) { 965 MBEDTLS_SSL_DEBUG_MSG(2, ("ECDH/FFDH group: %s (%04x)", 966 mbedtls_ssl_named_group_to_str(group), 967 group)); 968 ret = mbedtls_ssl_tls13_read_public_xxdhe_share( 969 ssl, key_exchange - 2, key_exchange_len + 2); 970 if (ret != 0) { 971 return ret; 972 } 973 974 } else { 975 MBEDTLS_SSL_DEBUG_MSG(4, ("Unrecognized NamedGroup %u", 976 (unsigned) group)); 977 continue; 978 } 979 980 ssl->handshake->offered_group_id = group; 981 } 982 983 984 if (ssl->handshake->offered_group_id == 0) { 985 MBEDTLS_SSL_DEBUG_MSG(1, ("no matching key share")); 986 return SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH; 987 } 988 return 0; 989 } 990 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ 991 992 MBEDTLS_CHECK_RETURN_CRITICAL 993 static int ssl_tls13_client_hello_has_exts(mbedtls_ssl_context *ssl, 994 int exts_mask) 995 { 996 int masked = ssl->handshake->received_extensions & exts_mask; 997 return masked == exts_mask; 998 } 999 1000 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 1001 MBEDTLS_CHECK_RETURN_CRITICAL 1002 static int ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange( 1003 mbedtls_ssl_context *ssl) 1004 { 1005 return ssl_tls13_client_hello_has_exts( 1006 ssl, 1007 MBEDTLS_SSL_EXT_MASK(SUPPORTED_GROUPS) | 1008 MBEDTLS_SSL_EXT_MASK(KEY_SHARE) | 1009 MBEDTLS_SSL_EXT_MASK(SIG_ALG)); 1010 } 1011 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 1012 1013 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED) 1014 MBEDTLS_CHECK_RETURN_CRITICAL 1015 static int ssl_tls13_client_hello_has_exts_for_psk_key_exchange( 1016 mbedtls_ssl_context *ssl) 1017 { 1018 return ssl_tls13_client_hello_has_exts( 1019 ssl, 1020 MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) | 1021 MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)); 1022 } 1023 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED */ 1024 1025 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED) 1026 MBEDTLS_CHECK_RETURN_CRITICAL 1027 static int ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange( 1028 mbedtls_ssl_context *ssl) 1029 { 1030 return ssl_tls13_client_hello_has_exts( 1031 ssl, 1032 MBEDTLS_SSL_EXT_MASK(SUPPORTED_GROUPS) | 1033 MBEDTLS_SSL_EXT_MASK(KEY_SHARE) | 1034 MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) | 1035 MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)); 1036 } 1037 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED */ 1038 1039 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1040 MBEDTLS_CHECK_RETURN_CRITICAL 1041 static int ssl_tls13_key_exchange_is_psk_available(mbedtls_ssl_context *ssl) 1042 { 1043 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED) 1044 return mbedtls_ssl_conf_tls13_is_psk_enabled(ssl) && 1045 mbedtls_ssl_tls13_is_psk_supported(ssl) && 1046 ssl_tls13_client_hello_has_exts_for_psk_key_exchange(ssl); 1047 #else 1048 ((void) ssl); 1049 return 0; 1050 #endif 1051 } 1052 1053 MBEDTLS_CHECK_RETURN_CRITICAL 1054 static int ssl_tls13_key_exchange_is_psk_ephemeral_available(mbedtls_ssl_context *ssl) 1055 { 1056 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED) 1057 return mbedtls_ssl_conf_tls13_is_psk_ephemeral_enabled(ssl) && 1058 mbedtls_ssl_tls13_is_psk_ephemeral_supported(ssl) && 1059 ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange(ssl); 1060 #else 1061 ((void) ssl); 1062 return 0; 1063 #endif 1064 } 1065 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ 1066 1067 MBEDTLS_CHECK_RETURN_CRITICAL 1068 static int ssl_tls13_key_exchange_is_ephemeral_available(mbedtls_ssl_context *ssl) 1069 { 1070 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 1071 return mbedtls_ssl_conf_tls13_is_ephemeral_enabled(ssl) && 1072 ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange(ssl); 1073 #else 1074 ((void) ssl); 1075 return 0; 1076 #endif 1077 } 1078 1079 #if defined(MBEDTLS_X509_CRT_PARSE_C) && \ 1080 defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 1081 1082 #if defined(MBEDTLS_USE_PSA_CRYPTO) 1083 static psa_algorithm_t ssl_tls13_iana_sig_alg_to_psa_alg(uint16_t sig_alg) 1084 { 1085 switch (sig_alg) { 1086 case MBEDTLS_TLS1_3_SIG_ECDSA_SECP256R1_SHA256: 1087 return PSA_ALG_ECDSA(PSA_ALG_SHA_256); 1088 case MBEDTLS_TLS1_3_SIG_ECDSA_SECP384R1_SHA384: 1089 return PSA_ALG_ECDSA(PSA_ALG_SHA_384); 1090 case MBEDTLS_TLS1_3_SIG_ECDSA_SECP521R1_SHA512: 1091 return PSA_ALG_ECDSA(PSA_ALG_SHA_512); 1092 case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA256: 1093 return PSA_ALG_RSA_PSS(PSA_ALG_SHA_256); 1094 case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA384: 1095 return PSA_ALG_RSA_PSS(PSA_ALG_SHA_384); 1096 case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA512: 1097 return PSA_ALG_RSA_PSS(PSA_ALG_SHA_512); 1098 case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA256: 1099 return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_256); 1100 case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA384: 1101 return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_384); 1102 case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA512: 1103 return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_512); 1104 default: 1105 return PSA_ALG_NONE; 1106 } 1107 } 1108 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 1109 1110 /* 1111 * Pick best ( private key, certificate chain ) pair based on the signature 1112 * algorithms supported by the client. 1113 */ 1114 MBEDTLS_CHECK_RETURN_CRITICAL 1115 static int ssl_tls13_pick_key_cert(mbedtls_ssl_context *ssl) 1116 { 1117 mbedtls_ssl_key_cert *key_cert, *key_cert_list; 1118 const uint16_t *sig_alg = ssl->handshake->received_sig_algs; 1119 1120 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) 1121 if (ssl->handshake->sni_key_cert != NULL) { 1122 key_cert_list = ssl->handshake->sni_key_cert; 1123 } else 1124 #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ 1125 key_cert_list = ssl->conf->key_cert; 1126 1127 if (key_cert_list == NULL) { 1128 MBEDTLS_SSL_DEBUG_MSG(3, ("server has no certificate")); 1129 return -1; 1130 } 1131 1132 for (; *sig_alg != MBEDTLS_TLS1_3_SIG_NONE; sig_alg++) { 1133 if (!mbedtls_ssl_sig_alg_is_offered(ssl, *sig_alg)) { 1134 continue; 1135 } 1136 1137 if (!mbedtls_ssl_tls13_sig_alg_for_cert_verify_is_supported(*sig_alg)) { 1138 continue; 1139 } 1140 1141 for (key_cert = key_cert_list; key_cert != NULL; 1142 key_cert = key_cert->next) { 1143 #if defined(MBEDTLS_USE_PSA_CRYPTO) 1144 psa_algorithm_t psa_alg = PSA_ALG_NONE; 1145 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 1146 1147 MBEDTLS_SSL_DEBUG_CRT(3, "certificate (chain) candidate", 1148 key_cert->cert); 1149 1150 /* 1151 * This avoids sending the client a cert it'll reject based on 1152 * keyUsage or other extensions. 1153 */ 1154 if (mbedtls_x509_crt_check_key_usage( 1155 key_cert->cert, MBEDTLS_X509_KU_DIGITAL_SIGNATURE) != 0 || 1156 mbedtls_x509_crt_check_extended_key_usage( 1157 key_cert->cert, MBEDTLS_OID_SERVER_AUTH, 1158 MBEDTLS_OID_SIZE(MBEDTLS_OID_SERVER_AUTH)) != 0) { 1159 MBEDTLS_SSL_DEBUG_MSG(3, ("certificate mismatch: " 1160 "(extended) key usage extension")); 1161 continue; 1162 } 1163 1164 MBEDTLS_SSL_DEBUG_MSG(3, 1165 ("ssl_tls13_pick_key_cert:" 1166 "check signature algorithm %s [%04x]", 1167 mbedtls_ssl_sig_alg_to_str(*sig_alg), 1168 *sig_alg)); 1169 #if defined(MBEDTLS_USE_PSA_CRYPTO) 1170 psa_alg = ssl_tls13_iana_sig_alg_to_psa_alg(*sig_alg); 1171 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 1172 1173 if (mbedtls_ssl_tls13_check_sig_alg_cert_key_match( 1174 *sig_alg, &key_cert->cert->pk) 1175 #if defined(MBEDTLS_USE_PSA_CRYPTO) 1176 && psa_alg != PSA_ALG_NONE && 1177 mbedtls_pk_can_do_ext(&key_cert->cert->pk, psa_alg, 1178 PSA_KEY_USAGE_SIGN_HASH) == 1 1179 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 1180 ) { 1181 ssl->handshake->key_cert = key_cert; 1182 MBEDTLS_SSL_DEBUG_MSG(3, 1183 ("ssl_tls13_pick_key_cert:" 1184 "selected signature algorithm" 1185 " %s [%04x]", 1186 mbedtls_ssl_sig_alg_to_str(*sig_alg), 1187 *sig_alg)); 1188 MBEDTLS_SSL_DEBUG_CRT( 1189 3, "selected certificate (chain)", 1190 ssl->handshake->key_cert->cert); 1191 return 0; 1192 } 1193 } 1194 } 1195 1196 MBEDTLS_SSL_DEBUG_MSG(2, ("ssl_tls13_pick_key_cert:" 1197 "no suitable certificate found")); 1198 return -1; 1199 } 1200 #endif /* MBEDTLS_X509_CRT_PARSE_C && 1201 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 1202 1203 /* 1204 * 1205 * STATE HANDLING: ClientHello 1206 * 1207 * There are three possible classes of outcomes when parsing the ClientHello: 1208 * 1209 * 1) The ClientHello was well-formed and matched the server's configuration. 1210 * 1211 * In this case, the server progresses to sending its ServerHello. 1212 * 1213 * 2) The ClientHello was well-formed but didn't match the server's 1214 * configuration. 1215 * 1216 * For example, the client might not have offered a key share which 1217 * the server supports, or the server might require a cookie. 1218 * 1219 * In this case, the server sends a HelloRetryRequest. 1220 * 1221 * 3) The ClientHello was ill-formed 1222 * 1223 * In this case, we abort the handshake. 1224 * 1225 */ 1226 1227 /* 1228 * Structure of this message: 1229 * 1230 * uint16 ProtocolVersion; 1231 * opaque Random[32]; 1232 * uint8 CipherSuite[2]; // Cryptographic suite selector 1233 * 1234 * struct { 1235 * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 1236 * Random random; 1237 * opaque legacy_session_id<0..32>; 1238 * CipherSuite cipher_suites<2..2^16-2>; 1239 * opaque legacy_compression_methods<1..2^8-1>; 1240 * Extension extensions<8..2^16-1>; 1241 * } ClientHello; 1242 */ 1243 1244 #define SSL_CLIENT_HELLO_OK 0 1245 #define SSL_CLIENT_HELLO_HRR_REQUIRED 1 1246 #define SSL_CLIENT_HELLO_TLS1_2 2 1247 1248 MBEDTLS_CHECK_RETURN_CRITICAL 1249 static int ssl_tls13_parse_client_hello(mbedtls_ssl_context *ssl, 1250 const unsigned char *buf, 1251 const unsigned char *end) 1252 { 1253 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 1254 const unsigned char *p = buf; 1255 const unsigned char *random; 1256 size_t legacy_session_id_len; 1257 const unsigned char *legacy_session_id; 1258 size_t cipher_suites_len; 1259 const unsigned char *cipher_suites; 1260 const unsigned char *cipher_suites_end; 1261 size_t extensions_len; 1262 const unsigned char *extensions_end; 1263 const unsigned char *supported_versions_data; 1264 const unsigned char *supported_versions_data_end; 1265 mbedtls_ssl_handshake_params *handshake = ssl->handshake; 1266 int hrr_required = 0; 1267 int no_usable_share_for_key_agreement = 0; 1268 1269 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1270 int got_psk = 0; 1271 struct psk_attributes psk = PSK_ATTRIBUTES_INIT; 1272 const unsigned char *pre_shared_key_ext = NULL; 1273 const unsigned char *pre_shared_key_ext_end = NULL; 1274 #endif 1275 1276 /* 1277 * ClientHello layout: 1278 * 0 . 1 protocol version 1279 * 2 . 33 random bytes 1280 * 34 . 34 session id length ( 1 byte ) 1281 * 35 . 34+x session id 1282 * .. . .. ciphersuite list length ( 2 bytes ) 1283 * .. . .. ciphersuite list 1284 * .. . .. compression alg. list length ( 1 byte ) 1285 * .. . .. compression alg. list 1286 * .. . .. extensions length ( 2 bytes, optional ) 1287 * .. . .. extensions ( optional ) 1288 */ 1289 1290 /* 1291 * Minimal length ( with everything empty and extensions omitted ) is 1292 * 2 + 32 + 1 + 2 + 1 = 38 bytes. Check that first, so that we can 1293 * read at least up to session id length without worrying. 1294 */ 1295 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 38); 1296 1297 /* ... 1298 * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 1299 * ... 1300 * with ProtocolVersion defined as: 1301 * uint16 ProtocolVersion; 1302 */ 1303 if (mbedtls_ssl_read_version(p, ssl->conf->transport) != 1304 MBEDTLS_SSL_VERSION_TLS1_2) { 1305 MBEDTLS_SSL_DEBUG_MSG(1, ("Unsupported version of TLS.")); 1306 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, 1307 MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); 1308 return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; 1309 } 1310 p += 2; 1311 1312 /* ... 1313 * Random random; 1314 * ... 1315 * with Random defined as: 1316 * opaque Random[32]; 1317 */ 1318 random = p; 1319 p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN; 1320 1321 /* ... 1322 * opaque legacy_session_id<0..32>; 1323 * ... 1324 */ 1325 legacy_session_id_len = *(p++); 1326 legacy_session_id = p; 1327 1328 /* 1329 * Check we have enough data for the legacy session identifier 1330 * and the ciphersuite list length. 1331 */ 1332 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, legacy_session_id_len + 2); 1333 p += legacy_session_id_len; 1334 1335 /* ... 1336 * CipherSuite cipher_suites<2..2^16-2>; 1337 * ... 1338 * with CipherSuite defined as: 1339 * uint8 CipherSuite[2]; 1340 */ 1341 cipher_suites_len = MBEDTLS_GET_UINT16_BE(p, 0); 1342 p += 2; 1343 cipher_suites = p; 1344 1345 /* 1346 * The length of the ciphersuite list has to be even. 1347 */ 1348 if (cipher_suites_len & 1) { 1349 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, 1350 MBEDTLS_ERR_SSL_DECODE_ERROR); 1351 return MBEDTLS_ERR_SSL_DECODE_ERROR; 1352 } 1353 1354 /* Check we have enough data for the ciphersuite list, the legacy 1355 * compression methods and the length of the extensions. 1356 * 1357 * cipher_suites cipher_suites_len bytes 1358 * legacy_compression_methods length 1 byte 1359 */ 1360 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, cipher_suites_len + 1); 1361 p += cipher_suites_len; 1362 cipher_suites_end = p; 1363 1364 /* Check if we have enough data for legacy_compression_methods 1365 * and the length of the extensions (2 bytes). 1366 */ 1367 MBEDTLS_SSL_CHK_BUF_READ_PTR(p + 1, end, p[0] + 2); 1368 1369 /* 1370 * Search for the supported versions extension and parse it to determine 1371 * if the client supports TLS 1.3. 1372 */ 1373 ret = mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts( 1374 ssl, p + 1 + p[0], end, 1375 &supported_versions_data, &supported_versions_data_end); 1376 if (ret < 0) { 1377 MBEDTLS_SSL_DEBUG_RET(1, 1378 ("mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts"), ret); 1379 return ret; 1380 } 1381 1382 if (ret == 0) { 1383 MBEDTLS_SSL_DEBUG_MSG(2, ("no supported_versions extension")); 1384 return SSL_CLIENT_HELLO_TLS1_2; 1385 } 1386 1387 if (ret == 1) { 1388 ret = ssl_tls13_parse_supported_versions_ext(ssl, 1389 supported_versions_data, 1390 supported_versions_data_end); 1391 if (ret < 0) { 1392 MBEDTLS_SSL_DEBUG_RET(1, 1393 ("ssl_tls13_parse_supported_versions_ext"), ret); 1394 return ret; 1395 } 1396 1397 /* 1398 * The supported versions extension was parsed successfully as the 1399 * value returned by ssl_tls13_parse_supported_versions_ext() is 1400 * positive. The return value is then equal to 1401 * MBEDTLS_SSL_VERSION_TLS1_2 or MBEDTLS_SSL_VERSION_TLS1_3, defining 1402 * the TLS version to negotiate. 1403 */ 1404 if (MBEDTLS_SSL_VERSION_TLS1_2 == ret) { 1405 MBEDTLS_SSL_DEBUG_MSG(2, ("supported_versions without 1.3")); 1406 return SSL_CLIENT_HELLO_TLS1_2; 1407 } 1408 } 1409 1410 /* 1411 * We negotiate TLS 1.3. 1412 */ 1413 ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; 1414 ssl->session_negotiate->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; 1415 ssl->session_negotiate->endpoint = ssl->conf->endpoint; 1416 1417 /* Before doing any crypto, make sure we can. */ 1418 ret = mbedtls_ssl_tls13_crypto_init(ssl); 1419 if (ret != 0) { 1420 return ret; 1421 } 1422 1423 /* 1424 * We are negotiating the version 1.3 of the protocol. Do what we have 1425 * postponed: copy of the client random bytes, copy of the legacy session 1426 * identifier and selection of the TLS 1.3 cipher suite. 1427 */ 1428 MBEDTLS_SSL_DEBUG_BUF(3, "client hello, random bytes", 1429 random, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); 1430 memcpy(&handshake->randbytes[0], random, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); 1431 1432 if (legacy_session_id_len > sizeof(ssl->session_negotiate->id)) { 1433 MBEDTLS_SSL_DEBUG_MSG(1, ("bad client hello message")); 1434 return MBEDTLS_ERR_SSL_DECODE_ERROR; 1435 } 1436 ssl->session_negotiate->id_len = legacy_session_id_len; 1437 MBEDTLS_SSL_DEBUG_BUF(3, "client hello, session id", 1438 legacy_session_id, legacy_session_id_len); 1439 memcpy(&ssl->session_negotiate->id[0], 1440 legacy_session_id, legacy_session_id_len); 1441 1442 /* 1443 * Search for a matching ciphersuite 1444 */ 1445 MBEDTLS_SSL_DEBUG_BUF(3, "client hello, list of cipher suites", 1446 cipher_suites, cipher_suites_len); 1447 1448 ssl_tls13_select_ciphersuite(ssl, cipher_suites, cipher_suites_end, 1449 0, PSA_ALG_NONE, &handshake->ciphersuite_info); 1450 1451 if (handshake->ciphersuite_info == NULL) { 1452 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, 1453 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 1454 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 1455 } 1456 ssl->session_negotiate->ciphersuite = handshake->ciphersuite_info->id; 1457 1458 MBEDTLS_SSL_DEBUG_MSG(2, ("selected ciphersuite: %04x - %s", 1459 ((unsigned) handshake->ciphersuite_info->id), 1460 handshake->ciphersuite_info->name)); 1461 1462 /* ... 1463 * opaque legacy_compression_methods<1..2^8-1>; 1464 * ... 1465 */ 1466 if (p[0] != 1 || p[1] != MBEDTLS_SSL_COMPRESS_NULL) { 1467 MBEDTLS_SSL_DEBUG_MSG(1, ("bad legacy compression method")); 1468 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, 1469 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 1470 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 1471 } 1472 p += 2; 1473 1474 /* ... 1475 * Extension extensions<8..2^16-1>; 1476 * ... 1477 * with Extension defined as: 1478 * struct { 1479 * ExtensionType extension_type; 1480 * opaque extension_data<0..2^16-1>; 1481 * } Extension; 1482 */ 1483 extensions_len = MBEDTLS_GET_UINT16_BE(p, 0); 1484 p += 2; 1485 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extensions_len); 1486 extensions_end = p + extensions_len; 1487 1488 MBEDTLS_SSL_DEBUG_BUF(3, "client hello extensions", p, extensions_len); 1489 handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE; 1490 1491 while (p < extensions_end) { 1492 unsigned int extension_type; 1493 size_t extension_data_len; 1494 const unsigned char *extension_data_end; 1495 uint32_t allowed_exts = MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CH; 1496 1497 if (ssl->handshake->hello_retry_request_flag) { 1498 /* Do not accept early data extension in 2nd ClientHello */ 1499 allowed_exts &= ~MBEDTLS_SSL_EXT_MASK(EARLY_DATA); 1500 } 1501 1502 /* RFC 8446, section 4.2.11 1503 * 1504 * The "pre_shared_key" extension MUST be the last extension in the 1505 * ClientHello (this facilitates implementation as described below). 1506 * Servers MUST check that it is the last extension and otherwise fail 1507 * the handshake with an "illegal_parameter" alert. 1508 */ 1509 if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY)) { 1510 MBEDTLS_SSL_DEBUG_MSG( 1511 3, ("pre_shared_key is not last extension.")); 1512 MBEDTLS_SSL_PEND_FATAL_ALERT( 1513 MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, 1514 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 1515 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 1516 } 1517 1518 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, 4); 1519 extension_type = MBEDTLS_GET_UINT16_BE(p, 0); 1520 extension_data_len = MBEDTLS_GET_UINT16_BE(p, 2); 1521 p += 4; 1522 1523 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, extension_data_len); 1524 extension_data_end = p + extension_data_len; 1525 1526 ret = mbedtls_ssl_tls13_check_received_extension( 1527 ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, extension_type, 1528 allowed_exts); 1529 if (ret != 0) { 1530 return ret; 1531 } 1532 1533 switch (extension_type) { 1534 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) 1535 case MBEDTLS_TLS_EXT_SERVERNAME: 1536 MBEDTLS_SSL_DEBUG_MSG(3, ("found ServerName extension")); 1537 ret = mbedtls_ssl_parse_server_name_ext(ssl, p, 1538 extension_data_end); 1539 if (ret != 0) { 1540 MBEDTLS_SSL_DEBUG_RET( 1541 1, "mbedtls_ssl_parse_servername_ext", ret); 1542 return ret; 1543 } 1544 break; 1545 #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ 1546 1547 #if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) 1548 case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS: 1549 MBEDTLS_SSL_DEBUG_MSG(3, ("found supported group extension")); 1550 1551 /* Supported Groups Extension 1552 * 1553 * When sent by the client, the "supported_groups" extension 1554 * indicates the named groups which the client supports, 1555 * ordered from most preferred to least preferred. 1556 */ 1557 ret = ssl_tls13_parse_supported_groups_ext( 1558 ssl, p, extension_data_end); 1559 if (ret != 0) { 1560 MBEDTLS_SSL_DEBUG_RET( 1561 1, "ssl_tls13_parse_supported_groups_ext", ret); 1562 return ret; 1563 } 1564 1565 break; 1566 #endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH*/ 1567 1568 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) 1569 case MBEDTLS_TLS_EXT_KEY_SHARE: 1570 MBEDTLS_SSL_DEBUG_MSG(3, ("found key share extension")); 1571 1572 /* 1573 * Key Share Extension 1574 * 1575 * When sent by the client, the "key_share" extension 1576 * contains the endpoint's cryptographic parameters for 1577 * ECDHE/DHE key establishment methods. 1578 */ 1579 ret = ssl_tls13_parse_key_shares_ext( 1580 ssl, p, extension_data_end); 1581 if (ret == SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH) { 1582 MBEDTLS_SSL_DEBUG_MSG(2, ("No usable share for key agreement.")); 1583 no_usable_share_for_key_agreement = 1; 1584 } 1585 1586 if (ret < 0) { 1587 MBEDTLS_SSL_DEBUG_RET( 1588 1, "ssl_tls13_parse_key_shares_ext", ret); 1589 return ret; 1590 } 1591 1592 break; 1593 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ 1594 1595 case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS: 1596 /* Already parsed */ 1597 break; 1598 1599 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1600 case MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES: 1601 MBEDTLS_SSL_DEBUG_MSG( 1602 3, ("found psk key exchange modes extension")); 1603 1604 ret = ssl_tls13_parse_key_exchange_modes_ext( 1605 ssl, p, extension_data_end); 1606 if (ret != 0) { 1607 MBEDTLS_SSL_DEBUG_RET( 1608 1, "ssl_tls13_parse_key_exchange_modes_ext", ret); 1609 return ret; 1610 } 1611 1612 break; 1613 #endif 1614 1615 case MBEDTLS_TLS_EXT_PRE_SHARED_KEY: 1616 MBEDTLS_SSL_DEBUG_MSG(3, ("found pre_shared_key extension")); 1617 if ((handshake->received_extensions & 1618 MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)) == 0) { 1619 MBEDTLS_SSL_PEND_FATAL_ALERT( 1620 MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, 1621 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 1622 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 1623 } 1624 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1625 /* Delay processing of the PSK identity once we have 1626 * found out which algorithms to use. We keep a pointer 1627 * to the buffer and the size for later processing. 1628 */ 1629 pre_shared_key_ext = p; 1630 pre_shared_key_ext_end = extension_data_end; 1631 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ 1632 break; 1633 1634 #if defined(MBEDTLS_SSL_ALPN) 1635 case MBEDTLS_TLS_EXT_ALPN: 1636 MBEDTLS_SSL_DEBUG_MSG(3, ("found alpn extension")); 1637 1638 ret = mbedtls_ssl_parse_alpn_ext(ssl, p, extension_data_end); 1639 if (ret != 0) { 1640 MBEDTLS_SSL_DEBUG_RET( 1641 1, ("mbedtls_ssl_parse_alpn_ext"), ret); 1642 return ret; 1643 } 1644 break; 1645 #endif /* MBEDTLS_SSL_ALPN */ 1646 1647 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 1648 case MBEDTLS_TLS_EXT_SIG_ALG: 1649 MBEDTLS_SSL_DEBUG_MSG(3, ("found signature_algorithms extension")); 1650 1651 ret = mbedtls_ssl_parse_sig_alg_ext( 1652 ssl, p, extension_data_end); 1653 if (ret != 0) { 1654 MBEDTLS_SSL_DEBUG_RET( 1655 1, "mbedtls_ssl_parse_sig_alg_ext", ret); 1656 return ret; 1657 } 1658 break; 1659 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 1660 1661 #if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) 1662 case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT: 1663 MBEDTLS_SSL_DEBUG_MSG(3, ("found record_size_limit extension")); 1664 1665 ret = mbedtls_ssl_tls13_parse_record_size_limit_ext( 1666 ssl, p, extension_data_end); 1667 if (ret != 0) { 1668 MBEDTLS_SSL_DEBUG_RET( 1669 1, ("mbedtls_ssl_tls13_parse_record_size_limit_ext"), ret); 1670 return ret; 1671 } 1672 break; 1673 #endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */ 1674 1675 default: 1676 MBEDTLS_SSL_PRINT_EXT( 1677 3, MBEDTLS_SSL_HS_CLIENT_HELLO, 1678 extension_type, "( ignored )"); 1679 break; 1680 } 1681 1682 p += extension_data_len; 1683 } 1684 1685 MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_CLIENT_HELLO, 1686 handshake->received_extensions); 1687 1688 ret = mbedtls_ssl_add_hs_hdr_to_checksum(ssl, 1689 MBEDTLS_SSL_HS_CLIENT_HELLO, 1690 p - buf); 1691 if (0 != ret) { 1692 MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_add_hs_hdr_to_checksum"), ret); 1693 return ret; 1694 } 1695 1696 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1697 /* Update checksum with either 1698 * - The entire content of the CH message, if no PSK extension is present 1699 * - The content up to but excluding the PSK extension, if present. 1700 * Always parse the pre-shared-key extension when present in the 1701 * ClientHello even if some pre-requisites for PSK key exchange modes are 1702 * not met. That way we always validate the syntax of the extension. 1703 */ 1704 if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY)) { 1705 ret = handshake->update_checksum(ssl, buf, 1706 pre_shared_key_ext - buf); 1707 if (0 != ret) { 1708 MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); 1709 return ret; 1710 } 1711 ret = ssl_tls13_parse_pre_shared_key_ext(ssl, 1712 pre_shared_key_ext, 1713 pre_shared_key_ext_end, 1714 cipher_suites, 1715 cipher_suites_end, 1716 &psk); 1717 if (ret == 0) { 1718 got_psk = 1; 1719 } else if (ret != MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY) { 1720 MBEDTLS_SSL_DEBUG_RET( 1721 1, "ssl_tls13_parse_pre_shared_key_ext", ret); 1722 return ret; 1723 } 1724 } else 1725 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ 1726 { 1727 ret = handshake->update_checksum(ssl, buf, p - buf); 1728 if (0 != ret) { 1729 MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); 1730 return ret; 1731 } 1732 } 1733 1734 /* 1735 * Determine the key exchange algorithm to use. 1736 * There are three types of key exchanges supported in TLS 1.3: 1737 * - (EC)DH with ECDSA, 1738 * - (EC)DH with PSK, 1739 * - plain PSK. 1740 * 1741 * The PSK-based key exchanges may additionally be used with 0-RTT. 1742 * 1743 * Our built-in order of preference is 1744 * 1 ) (EC)DHE-PSK Mode ( psk_ephemeral ) 1745 * 2 ) Certificate Mode ( ephemeral ) 1746 * 3 ) Plain PSK Mode ( psk ) 1747 */ 1748 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1749 if (got_psk && (psk.key_exchange_mode == 1750 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL)) { 1751 handshake->key_exchange_mode = 1752 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; 1753 MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: psk_ephemeral")); 1754 1755 } else 1756 #endif 1757 if (ssl_tls13_key_exchange_is_ephemeral_available(ssl)) { 1758 handshake->key_exchange_mode = 1759 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL; 1760 MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: ephemeral")); 1761 1762 } 1763 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1764 else if (got_psk && (psk.key_exchange_mode == 1765 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK)) { 1766 handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; 1767 MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: psk")); 1768 } 1769 #endif 1770 else { 1771 MBEDTLS_SSL_DEBUG_MSG( 1772 1, 1773 ("ClientHello message misses mandatory extensions.")); 1774 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION, 1775 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 1776 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 1777 } 1778 1779 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1780 if (handshake->key_exchange_mode & 1781 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL) { 1782 handshake->ciphersuite_info = psk.ciphersuite_info; 1783 ssl->session_negotiate->ciphersuite = psk.ciphersuite_info->id; 1784 1785 MBEDTLS_SSL_DEBUG_MSG(2, ("Select PSK ciphersuite: %04x - %s", 1786 ((unsigned) psk.ciphersuite_info->id), 1787 psk.ciphersuite_info->name)); 1788 1789 if (psk.type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION) { 1790 handshake->resume = 1; 1791 } 1792 } 1793 #endif 1794 1795 if (handshake->key_exchange_mode != 1796 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK) { 1797 hrr_required = (no_usable_share_for_key_agreement != 0); 1798 } 1799 1800 mbedtls_ssl_optimize_checksum(ssl, handshake->ciphersuite_info); 1801 1802 return hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK; 1803 } 1804 1805 #if defined(MBEDTLS_SSL_EARLY_DATA) 1806 static int ssl_tls13_check_early_data_requirements(mbedtls_ssl_context *ssl) 1807 { 1808 mbedtls_ssl_handshake_params *handshake = ssl->handshake; 1809 1810 if (ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_DISABLED) { 1811 MBEDTLS_SSL_DEBUG_MSG( 1812 1, 1813 ("EarlyData: rejected, feature disabled in server configuration.")); 1814 return -1; 1815 } 1816 1817 if (!handshake->resume) { 1818 /* We currently support early data only in the case of PSKs established 1819 via a NewSessionTicket message thus in the case of a session 1820 resumption. */ 1821 MBEDTLS_SSL_DEBUG_MSG( 1822 1, ("EarlyData: rejected, not a session resumption.")); 1823 return -1; 1824 } 1825 1826 /* RFC 8446 4.2.10 1827 * 1828 * In order to accept early data, the server MUST have accepted a PSK cipher 1829 * suite and selected the first key offered in the client's "pre_shared_key" 1830 * extension. In addition, it MUST verify that the following values are the 1831 * same as those associated with the selected PSK: 1832 * - The TLS version number 1833 * - The selected cipher suite 1834 * - The selected ALPN [RFC7301] protocol, if any 1835 * 1836 * NOTE: 1837 * - The TLS version number is checked in 1838 * ssl_tls13_offered_psks_check_identity_match_ticket(). 1839 */ 1840 1841 if (handshake->selected_identity != 0) { 1842 MBEDTLS_SSL_DEBUG_MSG( 1843 1, ("EarlyData: rejected, the selected key in " 1844 "`pre_shared_key` is not the first one.")); 1845 return -1; 1846 } 1847 1848 if (handshake->ciphersuite_info->id != 1849 ssl->session_negotiate->ciphersuite) { 1850 MBEDTLS_SSL_DEBUG_MSG( 1851 1, ("EarlyData: rejected, the selected ciphersuite is not the one " 1852 "of the selected pre-shared key.")); 1853 return -1; 1854 1855 } 1856 1857 if (!mbedtls_ssl_tls13_session_ticket_allow_early_data(ssl->session_negotiate)) { 1858 MBEDTLS_SSL_DEBUG_MSG( 1859 1, 1860 ("EarlyData: rejected, early_data not allowed in ticket " 1861 "permission bits.")); 1862 return -1; 1863 } 1864 1865 #if defined(MBEDTLS_SSL_ALPN) 1866 const char *alpn = mbedtls_ssl_get_alpn_protocol(ssl); 1867 size_t alpn_len; 1868 1869 if (alpn == NULL && ssl->session_negotiate->ticket_alpn == NULL) { 1870 return 0; 1871 } 1872 1873 if (alpn != NULL) { 1874 alpn_len = strlen(alpn); 1875 } 1876 1877 if (alpn == NULL || 1878 ssl->session_negotiate->ticket_alpn == NULL || 1879 alpn_len != strlen(ssl->session_negotiate->ticket_alpn) || 1880 (memcmp(alpn, ssl->session_negotiate->ticket_alpn, alpn_len) != 0)) { 1881 MBEDTLS_SSL_DEBUG_MSG(1, ("EarlyData: rejected, the selected ALPN is different " 1882 "from the one associated with the pre-shared key.")); 1883 return -1; 1884 } 1885 #endif 1886 1887 return 0; 1888 } 1889 #endif /* MBEDTLS_SSL_EARLY_DATA */ 1890 1891 /* Update the handshake state machine */ 1892 1893 MBEDTLS_CHECK_RETURN_CRITICAL 1894 static int ssl_tls13_postprocess_client_hello(mbedtls_ssl_context *ssl, 1895 int hrr_required) 1896 { 1897 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 1898 1899 /* 1900 * Server certificate selection 1901 */ 1902 if (ssl->conf->f_cert_cb && (ret = ssl->conf->f_cert_cb(ssl)) != 0) { 1903 MBEDTLS_SSL_DEBUG_RET(1, "f_cert_cb", ret); 1904 return ret; 1905 } 1906 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) 1907 ssl->handshake->sni_name = NULL; 1908 ssl->handshake->sni_name_len = 0; 1909 #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ 1910 1911 ret = mbedtls_ssl_tls13_key_schedule_stage_early(ssl); 1912 if (ret != 0) { 1913 MBEDTLS_SSL_DEBUG_RET(1, 1914 "mbedtls_ssl_tls1_3_key_schedule_stage_early", ret); 1915 return ret; 1916 } 1917 1918 #if defined(MBEDTLS_SSL_EARLY_DATA) 1919 if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(EARLY_DATA)) { 1920 ssl->handshake->early_data_accepted = 1921 (!hrr_required) && (ssl_tls13_check_early_data_requirements(ssl) == 0); 1922 1923 if (ssl->handshake->early_data_accepted) { 1924 ret = mbedtls_ssl_tls13_compute_early_transform(ssl); 1925 if (ret != 0) { 1926 MBEDTLS_SSL_DEBUG_RET( 1927 1, "mbedtls_ssl_tls13_compute_early_transform", ret); 1928 return ret; 1929 } 1930 } else { 1931 ssl->discard_early_data_record = 1932 hrr_required ? 1933 MBEDTLS_SSL_EARLY_DATA_DISCARD : 1934 MBEDTLS_SSL_EARLY_DATA_TRY_TO_DEPROTECT_AND_DISCARD; 1935 } 1936 } 1937 #else 1938 ((void) hrr_required); 1939 #endif /* MBEDTLS_SSL_EARLY_DATA */ 1940 1941 return 0; 1942 } 1943 1944 /* 1945 * Main entry point from the state machine; orchestrates the otherfunctions. 1946 */ 1947 1948 MBEDTLS_CHECK_RETURN_CRITICAL 1949 static int ssl_tls13_process_client_hello(mbedtls_ssl_context *ssl) 1950 { 1951 1952 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 1953 unsigned char *buf = NULL; 1954 size_t buflen = 0; 1955 int parse_client_hello_ret; 1956 1957 MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse client hello")); 1958 1959 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( 1960 ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, 1961 &buf, &buflen)); 1962 1963 MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_parse_client_hello(ssl, buf, 1964 buf + buflen)); 1965 parse_client_hello_ret = ret; /* Store positive return value of 1966 * parse_client_hello, 1967 * as negative error codes are handled 1968 * by MBEDTLS_SSL_PROC_CHK_NEG. */ 1969 1970 /* 1971 * Version 1.2 of the protocol has to be used for the handshake. 1972 * If TLS 1.2 is not supported, abort the handshake. Otherwise, set the 1973 * ssl->keep_current_message flag for the ClientHello to be kept and parsed 1974 * as a TLS 1.2 ClientHello. We also change ssl->tls_version to 1975 * MBEDTLS_SSL_VERSION_TLS1_2 thus from now on mbedtls_ssl_handshake_step() 1976 * will dispatch to the TLS 1.2 state machine. 1977 */ 1978 if (SSL_CLIENT_HELLO_TLS1_2 == parse_client_hello_ret) { 1979 /* Check if server supports TLS 1.2 */ 1980 if (!mbedtls_ssl_conf_is_tls12_enabled(ssl->conf)) { 1981 MBEDTLS_SSL_DEBUG_MSG( 1982 1, ("TLS 1.2 not supported.")); 1983 MBEDTLS_SSL_PEND_FATAL_ALERT( 1984 MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, 1985 MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); 1986 return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; 1987 } 1988 ssl->keep_current_message = 1; 1989 ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_2; 1990 MBEDTLS_SSL_DEBUG_MSG(1, ("non-1.3 ClientHello left for later processing")); 1991 return 0; 1992 } 1993 1994 MBEDTLS_SSL_PROC_CHK( 1995 ssl_tls13_postprocess_client_hello(ssl, parse_client_hello_ret == 1996 SSL_CLIENT_HELLO_HRR_REQUIRED)); 1997 1998 if (SSL_CLIENT_HELLO_OK == parse_client_hello_ret) { 1999 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_HELLO); 2000 } else { 2001 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HELLO_RETRY_REQUEST); 2002 } 2003 2004 cleanup: 2005 2006 MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse client hello")); 2007 return ret; 2008 } 2009 2010 /* 2011 * Handler for MBEDTLS_SSL_SERVER_HELLO 2012 */ 2013 MBEDTLS_CHECK_RETURN_CRITICAL 2014 static int ssl_tls13_prepare_server_hello(mbedtls_ssl_context *ssl) 2015 { 2016 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2017 unsigned char *server_randbytes = 2018 ssl->handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN; 2019 2020 if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, server_randbytes, 2021 MBEDTLS_SERVER_HELLO_RANDOM_LEN)) != 0) { 2022 MBEDTLS_SSL_DEBUG_RET(1, "f_rng", ret); 2023 return ret; 2024 } 2025 2026 MBEDTLS_SSL_DEBUG_BUF(3, "server hello, random bytes", server_randbytes, 2027 MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2028 2029 #if defined(MBEDTLS_HAVE_TIME) 2030 ssl->session_negotiate->start = mbedtls_time(NULL); 2031 #endif /* MBEDTLS_HAVE_TIME */ 2032 2033 return ret; 2034 } 2035 2036 /* 2037 * ssl_tls13_write_server_hello_supported_versions_ext (): 2038 * 2039 * struct { 2040 * ProtocolVersion selected_version; 2041 * } SupportedVersions; 2042 */ 2043 MBEDTLS_CHECK_RETURN_CRITICAL 2044 static int ssl_tls13_write_server_hello_supported_versions_ext( 2045 mbedtls_ssl_context *ssl, 2046 unsigned char *buf, 2047 unsigned char *end, 2048 size_t *out_len) 2049 { 2050 *out_len = 0; 2051 2052 MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, write selected version")); 2053 2054 /* Check if we have space to write the extension: 2055 * - extension_type (2 bytes) 2056 * - extension_data_length (2 bytes) 2057 * - selected_version (2 bytes) 2058 */ 2059 MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6); 2060 2061 MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, buf, 0); 2062 2063 MBEDTLS_PUT_UINT16_BE(2, buf, 2); 2064 2065 mbedtls_ssl_write_version(buf + 4, 2066 ssl->conf->transport, 2067 ssl->tls_version); 2068 2069 MBEDTLS_SSL_DEBUG_MSG(3, ("supported version: [%04x]", 2070 ssl->tls_version)); 2071 2072 *out_len = 6; 2073 2074 mbedtls_ssl_tls13_set_hs_sent_ext_mask( 2075 ssl, MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS); 2076 2077 return 0; 2078 } 2079 2080 2081 2082 /* Generate and export a single key share. For hybrid KEMs, this can 2083 * be called multiple times with the different components of the hybrid. */ 2084 MBEDTLS_CHECK_RETURN_CRITICAL 2085 static int ssl_tls13_generate_and_write_key_share(mbedtls_ssl_context *ssl, 2086 uint16_t named_group, 2087 unsigned char *buf, 2088 unsigned char *end, 2089 size_t *out_len) 2090 { 2091 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2092 2093 *out_len = 0; 2094 2095 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) 2096 if (mbedtls_ssl_tls13_named_group_is_ecdhe(named_group) || 2097 mbedtls_ssl_tls13_named_group_is_ffdh(named_group)) { 2098 ret = mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange( 2099 ssl, named_group, buf, end, out_len); 2100 if (ret != 0) { 2101 MBEDTLS_SSL_DEBUG_RET( 2102 1, "mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange", 2103 ret); 2104 return ret; 2105 } 2106 } else 2107 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ 2108 if (0 /* Other kinds of KEMs */) { 2109 } else { 2110 ((void) ssl); 2111 ((void) named_group); 2112 ((void) buf); 2113 ((void) end); 2114 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; 2115 } 2116 2117 return ret; 2118 } 2119 2120 /* 2121 * ssl_tls13_write_key_share_ext 2122 * 2123 * Structure of key_share extension in ServerHello: 2124 * 2125 * struct { 2126 * NamedGroup group; 2127 * opaque key_exchange<1..2^16-1>; 2128 * } KeyShareEntry; 2129 * struct { 2130 * KeyShareEntry server_share; 2131 * } KeyShareServerHello; 2132 */ 2133 MBEDTLS_CHECK_RETURN_CRITICAL 2134 static int ssl_tls13_write_key_share_ext(mbedtls_ssl_context *ssl, 2135 unsigned char *buf, 2136 unsigned char *end, 2137 size_t *out_len) 2138 { 2139 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2140 unsigned char *p = buf; 2141 uint16_t group = ssl->handshake->offered_group_id; 2142 unsigned char *server_share = buf + 4; 2143 size_t key_exchange_length; 2144 2145 *out_len = 0; 2146 2147 MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, adding key share extension")); 2148 2149 MBEDTLS_SSL_DEBUG_MSG(2, ("server hello, write selected_group: %s (%04x)", 2150 mbedtls_ssl_named_group_to_str(group), 2151 group)); 2152 2153 /* Check if we have space for header and length fields: 2154 * - extension_type (2 bytes) 2155 * - extension_data_length (2 bytes) 2156 * - group (2 bytes) 2157 * - key_exchange_length (2 bytes) 2158 */ 2159 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 8); 2160 MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, p, 0); 2161 MBEDTLS_PUT_UINT16_BE(group, server_share, 0); 2162 p += 8; 2163 2164 /* When we introduce PQC-ECDHE hybrids, we'll want to call this 2165 * function multiple times. */ 2166 ret = ssl_tls13_generate_and_write_key_share( 2167 ssl, group, server_share + 4, end, &key_exchange_length); 2168 if (ret != 0) { 2169 return ret; 2170 } 2171 p += key_exchange_length; 2172 2173 MBEDTLS_PUT_UINT16_BE(key_exchange_length, server_share + 2, 0); 2174 2175 MBEDTLS_PUT_UINT16_BE(p - server_share, buf, 2); 2176 2177 *out_len = p - buf; 2178 2179 mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); 2180 2181 return 0; 2182 } 2183 2184 MBEDTLS_CHECK_RETURN_CRITICAL 2185 static int ssl_tls13_write_hrr_key_share_ext(mbedtls_ssl_context *ssl, 2186 unsigned char *buf, 2187 unsigned char *end, 2188 size_t *out_len) 2189 { 2190 uint16_t selected_group = ssl->handshake->hrr_selected_group; 2191 /* key_share Extension 2192 * 2193 * struct { 2194 * select (Handshake.msg_type) { 2195 * ... 2196 * case hello_retry_request: 2197 * NamedGroup selected_group; 2198 * ... 2199 * }; 2200 * } KeyShare; 2201 */ 2202 2203 *out_len = 0; 2204 2205 /* 2206 * For a pure PSK key exchange, there is no group to agree upon. The purpose 2207 * of the HRR is then to transmit a cookie to force the client to demonstrate 2208 * reachability at their apparent network address (primarily useful for DTLS). 2209 */ 2210 if (!mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) { 2211 return 0; 2212 } 2213 2214 /* We should only send the key_share extension if the client's initial 2215 * key share was not acceptable. */ 2216 if (ssl->handshake->offered_group_id != 0) { 2217 MBEDTLS_SSL_DEBUG_MSG(4, ("Skip key_share extension in HRR")); 2218 return 0; 2219 } 2220 2221 if (selected_group == 0) { 2222 MBEDTLS_SSL_DEBUG_MSG(1, ("no matching named group found")); 2223 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 2224 } 2225 2226 /* Check if we have enough space: 2227 * - extension_type (2 bytes) 2228 * - extension_data_length (2 bytes) 2229 * - selected_group (2 bytes) 2230 */ 2231 MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6); 2232 2233 MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, buf, 0); 2234 MBEDTLS_PUT_UINT16_BE(2, buf, 2); 2235 MBEDTLS_PUT_UINT16_BE(selected_group, buf, 4); 2236 2237 MBEDTLS_SSL_DEBUG_MSG(3, 2238 ("HRR selected_group: %s (%x)", 2239 mbedtls_ssl_named_group_to_str(selected_group), 2240 selected_group)); 2241 2242 *out_len = 6; 2243 2244 mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); 2245 2246 return 0; 2247 } 2248 2249 /* 2250 * Structure of ServerHello message: 2251 * 2252 * struct { 2253 * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 2254 * Random random; 2255 * opaque legacy_session_id_echo<0..32>; 2256 * CipherSuite cipher_suite; 2257 * uint8 legacy_compression_method = 0; 2258 * Extension extensions<6..2^16-1>; 2259 * } ServerHello; 2260 */ 2261 MBEDTLS_CHECK_RETURN_CRITICAL 2262 static int ssl_tls13_write_server_hello_body(mbedtls_ssl_context *ssl, 2263 unsigned char *buf, 2264 unsigned char *end, 2265 size_t *out_len, 2266 int is_hrr) 2267 { 2268 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2269 unsigned char *p = buf; 2270 unsigned char *p_extensions_len; 2271 size_t output_len; 2272 2273 *out_len = 0; 2274 ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; 2275 2276 /* ... 2277 * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 2278 * ... 2279 * with ProtocolVersion defined as: 2280 * uint16 ProtocolVersion; 2281 */ 2282 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 2283 MBEDTLS_PUT_UINT16_BE(0x0303, p, 0); 2284 p += 2; 2285 2286 /* ... 2287 * Random random; 2288 * ... 2289 * with Random defined as: 2290 * opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN]; 2291 */ 2292 MBEDTLS_SSL_CHK_BUF_PTR(p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2293 if (is_hrr) { 2294 memcpy(p, mbedtls_ssl_tls13_hello_retry_request_magic, 2295 MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2296 } else { 2297 memcpy(p, &ssl->handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN], 2298 MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2299 } 2300 MBEDTLS_SSL_DEBUG_BUF(3, "server hello, random bytes", 2301 p, MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2302 p += MBEDTLS_SERVER_HELLO_RANDOM_LEN; 2303 2304 /* ... 2305 * opaque legacy_session_id_echo<0..32>; 2306 * ... 2307 */ 2308 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1 + ssl->session_negotiate->id_len); 2309 *p++ = (unsigned char) ssl->session_negotiate->id_len; 2310 if (ssl->session_negotiate->id_len > 0) { 2311 memcpy(p, &ssl->session_negotiate->id[0], 2312 ssl->session_negotiate->id_len); 2313 p += ssl->session_negotiate->id_len; 2314 2315 MBEDTLS_SSL_DEBUG_BUF(3, "session id", ssl->session_negotiate->id, 2316 ssl->session_negotiate->id_len); 2317 } 2318 2319 /* ... 2320 * CipherSuite cipher_suite; 2321 * ... 2322 * with CipherSuite defined as: 2323 * uint8 CipherSuite[2]; 2324 */ 2325 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 2326 MBEDTLS_PUT_UINT16_BE(ssl->session_negotiate->ciphersuite, p, 0); 2327 p += 2; 2328 MBEDTLS_SSL_DEBUG_MSG(3, 2329 ("server hello, chosen ciphersuite: %s ( id=%d )", 2330 mbedtls_ssl_get_ciphersuite_name( 2331 ssl->session_negotiate->ciphersuite), 2332 ssl->session_negotiate->ciphersuite)); 2333 2334 /* ... 2335 * uint8 legacy_compression_method = 0; 2336 * ... 2337 */ 2338 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1); 2339 *p++ = MBEDTLS_SSL_COMPRESS_NULL; 2340 2341 /* ... 2342 * Extension extensions<6..2^16-1>; 2343 * ... 2344 * struct { 2345 * ExtensionType extension_type; (2 bytes) 2346 * opaque extension_data<0..2^16-1>; 2347 * } Extension; 2348 */ 2349 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 2350 p_extensions_len = p; 2351 p += 2; 2352 2353 if ((ret = ssl_tls13_write_server_hello_supported_versions_ext( 2354 ssl, p, end, &output_len)) != 0) { 2355 MBEDTLS_SSL_DEBUG_RET( 2356 1, "ssl_tls13_write_server_hello_supported_versions_ext", ret); 2357 return ret; 2358 } 2359 p += output_len; 2360 2361 if (mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) { 2362 if (is_hrr) { 2363 ret = ssl_tls13_write_hrr_key_share_ext(ssl, p, end, &output_len); 2364 } else { 2365 ret = ssl_tls13_write_key_share_ext(ssl, p, end, &output_len); 2366 } 2367 if (ret != 0) { 2368 return ret; 2369 } 2370 p += output_len; 2371 } 2372 2373 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 2374 if (!is_hrr && mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) { 2375 ret = ssl_tls13_write_server_pre_shared_key_ext(ssl, p, end, &output_len); 2376 if (ret != 0) { 2377 MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_server_pre_shared_key_ext", 2378 ret); 2379 return ret; 2380 } 2381 p += output_len; 2382 } 2383 #endif 2384 2385 MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); 2386 2387 MBEDTLS_SSL_DEBUG_BUF(4, "server hello extensions", 2388 p_extensions_len, p - p_extensions_len); 2389 2390 *out_len = p - buf; 2391 2392 MBEDTLS_SSL_DEBUG_BUF(3, "server hello", buf, *out_len); 2393 2394 MBEDTLS_SSL_PRINT_EXTS( 2395 3, is_hrr ? MBEDTLS_SSL_TLS1_3_HS_HELLO_RETRY_REQUEST : 2396 MBEDTLS_SSL_HS_SERVER_HELLO, 2397 ssl->handshake->sent_extensions); 2398 2399 return ret; 2400 } 2401 2402 MBEDTLS_CHECK_RETURN_CRITICAL 2403 static int ssl_tls13_finalize_server_hello(mbedtls_ssl_context *ssl) 2404 { 2405 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2406 ret = mbedtls_ssl_tls13_compute_handshake_transform(ssl); 2407 if (ret != 0) { 2408 MBEDTLS_SSL_DEBUG_RET(1, 2409 "mbedtls_ssl_tls13_compute_handshake_transform", 2410 ret); 2411 return ret; 2412 } 2413 2414 return ret; 2415 } 2416 2417 MBEDTLS_CHECK_RETURN_CRITICAL 2418 static int ssl_tls13_write_server_hello(mbedtls_ssl_context *ssl) 2419 { 2420 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2421 unsigned char *buf; 2422 size_t buf_len, msg_len; 2423 2424 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write server hello")); 2425 2426 MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_server_hello(ssl)); 2427 2428 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 2429 ssl, MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len)); 2430 2431 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_server_hello_body(ssl, buf, 2432 buf + buf_len, 2433 &msg_len, 2434 0)); 2435 2436 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 2437 ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len)); 2438 2439 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( 2440 ssl, buf_len, msg_len)); 2441 2442 MBEDTLS_SSL_PROC_CHK(ssl_tls13_finalize_server_hello(ssl)); 2443 2444 #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) 2445 /* The server sends a dummy change_cipher_spec record immediately 2446 * after its first handshake message. This may either be after 2447 * a ServerHello or a HelloRetryRequest. 2448 */ 2449 mbedtls_ssl_handshake_set_state( 2450 ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO); 2451 #else 2452 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); 2453 #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ 2454 2455 cleanup: 2456 2457 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write server hello")); 2458 return ret; 2459 } 2460 2461 2462 /* 2463 * Handler for MBEDTLS_SSL_HELLO_RETRY_REQUEST 2464 */ 2465 MBEDTLS_CHECK_RETURN_CRITICAL 2466 static int ssl_tls13_prepare_hello_retry_request(mbedtls_ssl_context *ssl) 2467 { 2468 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2469 if (ssl->handshake->hello_retry_request_flag) { 2470 MBEDTLS_SSL_DEBUG_MSG(1, ("Too many HRRs")); 2471 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, 2472 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 2473 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 2474 } 2475 2476 /* 2477 * Create stateless transcript hash for HRR 2478 */ 2479 MBEDTLS_SSL_DEBUG_MSG(4, ("Reset transcript for HRR")); 2480 ret = mbedtls_ssl_reset_transcript_for_hrr(ssl); 2481 if (ret != 0) { 2482 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_reset_transcript_for_hrr", ret); 2483 return ret; 2484 } 2485 mbedtls_ssl_session_reset_msg_layer(ssl, 0); 2486 2487 return 0; 2488 } 2489 2490 MBEDTLS_CHECK_RETURN_CRITICAL 2491 static int ssl_tls13_write_hello_retry_request(mbedtls_ssl_context *ssl) 2492 { 2493 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2494 unsigned char *buf; 2495 size_t buf_len, msg_len; 2496 2497 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write hello retry request")); 2498 2499 MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_hello_retry_request(ssl)); 2500 2501 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 2502 ssl, MBEDTLS_SSL_HS_SERVER_HELLO, 2503 &buf, &buf_len)); 2504 2505 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_server_hello_body(ssl, buf, 2506 buf + buf_len, 2507 &msg_len, 2508 1)); 2509 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 2510 ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len)); 2511 2512 2513 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(ssl, buf_len, 2514 msg_len)); 2515 2516 ssl->handshake->hello_retry_request_flag = 1; 2517 2518 #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) 2519 /* The server sends a dummy change_cipher_spec record immediately 2520 * after its first handshake message. This may either be after 2521 * a ServerHello or a HelloRetryRequest. 2522 */ 2523 mbedtls_ssl_handshake_set_state( 2524 ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST); 2525 #else 2526 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); 2527 #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ 2528 2529 cleanup: 2530 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write hello retry request")); 2531 return ret; 2532 } 2533 2534 /* 2535 * Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS 2536 */ 2537 2538 /* 2539 * struct { 2540 * Extension extensions<0..2 ^ 16 - 1>; 2541 * } EncryptedExtensions; 2542 * 2543 */ 2544 MBEDTLS_CHECK_RETURN_CRITICAL 2545 static int ssl_tls13_write_encrypted_extensions_body(mbedtls_ssl_context *ssl, 2546 unsigned char *buf, 2547 unsigned char *end, 2548 size_t *out_len) 2549 { 2550 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2551 unsigned char *p = buf; 2552 size_t extensions_len = 0; 2553 unsigned char *p_extensions_len; 2554 size_t output_len; 2555 2556 *out_len = 0; 2557 2558 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 2559 p_extensions_len = p; 2560 p += 2; 2561 2562 ((void) ssl); 2563 ((void) ret); 2564 ((void) output_len); 2565 2566 #if defined(MBEDTLS_SSL_ALPN) 2567 ret = mbedtls_ssl_write_alpn_ext(ssl, p, end, &output_len); 2568 if (ret != 0) { 2569 return ret; 2570 } 2571 p += output_len; 2572 #endif /* MBEDTLS_SSL_ALPN */ 2573 2574 #if defined(MBEDTLS_SSL_EARLY_DATA) 2575 if (ssl->handshake->early_data_accepted) { 2576 ret = mbedtls_ssl_tls13_write_early_data_ext( 2577 ssl, 0, p, end, &output_len); 2578 if (ret != 0) { 2579 return ret; 2580 } 2581 p += output_len; 2582 } 2583 #endif /* MBEDTLS_SSL_EARLY_DATA */ 2584 2585 #if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) 2586 if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(RECORD_SIZE_LIMIT)) { 2587 ret = mbedtls_ssl_tls13_write_record_size_limit_ext( 2588 ssl, p, end, &output_len); 2589 if (ret != 0) { 2590 return ret; 2591 } 2592 p += output_len; 2593 } 2594 #endif 2595 2596 extensions_len = (p - p_extensions_len) - 2; 2597 MBEDTLS_PUT_UINT16_BE(extensions_len, p_extensions_len, 0); 2598 2599 *out_len = p - buf; 2600 2601 MBEDTLS_SSL_DEBUG_BUF(4, "encrypted extensions", buf, *out_len); 2602 2603 MBEDTLS_SSL_PRINT_EXTS( 2604 3, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, ssl->handshake->sent_extensions); 2605 2606 return 0; 2607 } 2608 2609 MBEDTLS_CHECK_RETURN_CRITICAL 2610 static int ssl_tls13_write_encrypted_extensions(mbedtls_ssl_context *ssl) 2611 { 2612 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2613 unsigned char *buf; 2614 size_t buf_len, msg_len; 2615 2616 mbedtls_ssl_set_outbound_transform(ssl, 2617 ssl->handshake->transform_handshake); 2618 MBEDTLS_SSL_DEBUG_MSG( 2619 3, ("switching to handshake transform for outbound data")); 2620 2621 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write encrypted extensions")); 2622 2623 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 2624 ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, 2625 &buf, &buf_len)); 2626 2627 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_encrypted_extensions_body( 2628 ssl, buf, buf + buf_len, &msg_len)); 2629 2630 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 2631 ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, 2632 buf, msg_len)); 2633 2634 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( 2635 ssl, buf_len, msg_len)); 2636 2637 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 2638 if (mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) { 2639 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); 2640 } else { 2641 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CERTIFICATE_REQUEST); 2642 } 2643 #else 2644 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); 2645 #endif 2646 2647 cleanup: 2648 2649 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write encrypted extensions")); 2650 return ret; 2651 } 2652 2653 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 2654 #define SSL_CERTIFICATE_REQUEST_SEND_REQUEST 0 2655 #define SSL_CERTIFICATE_REQUEST_SKIP 1 2656 /* Coordination: 2657 * Check whether a CertificateRequest message should be written. 2658 * Returns a negative code on failure, or 2659 * - SSL_CERTIFICATE_REQUEST_SEND_REQUEST 2660 * - SSL_CERTIFICATE_REQUEST_SKIP 2661 * indicating if the writing of the CertificateRequest 2662 * should be skipped or not. 2663 */ 2664 MBEDTLS_CHECK_RETURN_CRITICAL 2665 static int ssl_tls13_certificate_request_coordinate(mbedtls_ssl_context *ssl) 2666 { 2667 int authmode; 2668 2669 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) 2670 if (ssl->handshake->sni_authmode != MBEDTLS_SSL_VERIFY_UNSET) { 2671 authmode = ssl->handshake->sni_authmode; 2672 } else 2673 #endif 2674 authmode = ssl->conf->authmode; 2675 2676 if (authmode == MBEDTLS_SSL_VERIFY_NONE) { 2677 ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_SKIP_VERIFY; 2678 return SSL_CERTIFICATE_REQUEST_SKIP; 2679 } 2680 2681 ssl->handshake->certificate_request_sent = 1; 2682 2683 return SSL_CERTIFICATE_REQUEST_SEND_REQUEST; 2684 } 2685 2686 /* 2687 * struct { 2688 * opaque certificate_request_context<0..2^8-1>; 2689 * Extension extensions<2..2^16-1>; 2690 * } CertificateRequest; 2691 * 2692 */ 2693 MBEDTLS_CHECK_RETURN_CRITICAL 2694 static int ssl_tls13_write_certificate_request_body(mbedtls_ssl_context *ssl, 2695 unsigned char *buf, 2696 const unsigned char *end, 2697 size_t *out_len) 2698 { 2699 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2700 unsigned char *p = buf; 2701 size_t output_len = 0; 2702 unsigned char *p_extensions_len; 2703 2704 *out_len = 0; 2705 2706 /* Check if we have enough space: 2707 * - certificate_request_context (1 byte) 2708 * - extensions length (2 bytes) 2709 */ 2710 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 3); 2711 2712 /* 2713 * Write certificate_request_context 2714 */ 2715 /* 2716 * We use a zero length context for the normal handshake 2717 * messages. For post-authentication handshake messages 2718 * this request context would be set to a non-zero value. 2719 */ 2720 *p++ = 0x0; 2721 2722 /* 2723 * Write extensions 2724 */ 2725 /* The extensions must contain the signature_algorithms. */ 2726 p_extensions_len = p; 2727 p += 2; 2728 ret = mbedtls_ssl_write_sig_alg_ext(ssl, p, end, &output_len); 2729 if (ret != 0) { 2730 return ret; 2731 } 2732 2733 p += output_len; 2734 MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); 2735 2736 *out_len = p - buf; 2737 2738 MBEDTLS_SSL_PRINT_EXTS( 2739 3, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, ssl->handshake->sent_extensions); 2740 2741 return 0; 2742 } 2743 2744 MBEDTLS_CHECK_RETURN_CRITICAL 2745 static int ssl_tls13_write_certificate_request(mbedtls_ssl_context *ssl) 2746 { 2747 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2748 2749 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write certificate request")); 2750 2751 MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_certificate_request_coordinate(ssl)); 2752 2753 if (ret == SSL_CERTIFICATE_REQUEST_SEND_REQUEST) { 2754 unsigned char *buf; 2755 size_t buf_len, msg_len; 2756 2757 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 2758 ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, 2759 &buf, &buf_len)); 2760 2761 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_certificate_request_body( 2762 ssl, buf, buf + buf_len, &msg_len)); 2763 2764 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 2765 ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, 2766 buf, msg_len)); 2767 2768 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( 2769 ssl, buf_len, msg_len)); 2770 } else if (ret == SSL_CERTIFICATE_REQUEST_SKIP) { 2771 MBEDTLS_SSL_DEBUG_MSG(2, ("<= skip write certificate request")); 2772 ret = 0; 2773 } else { 2774 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); 2775 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; 2776 goto cleanup; 2777 } 2778 2779 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_CERTIFICATE); 2780 cleanup: 2781 2782 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write certificate request")); 2783 return ret; 2784 } 2785 2786 /* 2787 * Handler for MBEDTLS_SSL_SERVER_CERTIFICATE 2788 */ 2789 MBEDTLS_CHECK_RETURN_CRITICAL 2790 static int ssl_tls13_write_server_certificate(mbedtls_ssl_context *ssl) 2791 { 2792 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2793 2794 #if defined(MBEDTLS_X509_CRT_PARSE_C) 2795 if ((ssl_tls13_pick_key_cert(ssl) != 0) || 2796 mbedtls_ssl_own_cert(ssl) == NULL) { 2797 MBEDTLS_SSL_DEBUG_MSG(2, ("No certificate available.")); 2798 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, 2799 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 2800 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 2801 } 2802 #endif /* MBEDTLS_X509_CRT_PARSE_C */ 2803 2804 ret = mbedtls_ssl_tls13_write_certificate(ssl); 2805 if (ret != 0) { 2806 return ret; 2807 } 2808 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CERTIFICATE_VERIFY); 2809 return 0; 2810 } 2811 2812 /* 2813 * Handler for MBEDTLS_SSL_CERTIFICATE_VERIFY 2814 */ 2815 MBEDTLS_CHECK_RETURN_CRITICAL 2816 static int ssl_tls13_write_certificate_verify(mbedtls_ssl_context *ssl) 2817 { 2818 int ret = mbedtls_ssl_tls13_write_certificate_verify(ssl); 2819 if (ret != 0) { 2820 return ret; 2821 } 2822 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); 2823 return 0; 2824 } 2825 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 2826 2827 /* 2828 * RFC 8446 section A.2 2829 * 2830 * | Send ServerHello 2831 * | K_send = handshake 2832 * | Send EncryptedExtensions 2833 * | [Send CertificateRequest] 2834 * Can send | [Send Certificate + CertificateVerify] 2835 * app data | Send Finished 2836 * after --> | K_send = application 2837 * here +--------+--------+ 2838 * No 0-RTT | | 0-RTT 2839 * | | 2840 * K_recv = handshake | | K_recv = early data 2841 * [Skip decrypt errors] | +------> WAIT_EOED -+ 2842 * | | Recv | | Recv EndOfEarlyData 2843 * | | early data | | K_recv = handshake 2844 * | +------------+ | 2845 * | | 2846 * +> WAIT_FLIGHT2 <--------+ 2847 * | 2848 * +--------+--------+ 2849 * No auth | | Client auth 2850 * | | 2851 * | v 2852 * | WAIT_CERT 2853 * | Recv | | Recv Certificate 2854 * | empty | v 2855 * | Certificate | WAIT_CV 2856 * | | | Recv 2857 * | v | CertificateVerify 2858 * +-> WAIT_FINISHED <---+ 2859 * | Recv Finished 2860 * 2861 * 2862 * The following function handles the state changes after WAIT_FLIGHT2 in the 2863 * above diagram. We are not going to receive early data related messages 2864 * anymore, prepare to receive the first handshake message of the client 2865 * second flight. 2866 */ 2867 static void ssl_tls13_prepare_for_handshake_second_flight( 2868 mbedtls_ssl_context *ssl) 2869 { 2870 if (ssl->handshake->certificate_request_sent) { 2871 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE); 2872 } else { 2873 MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate")); 2874 MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate verify")); 2875 2876 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_FINISHED); 2877 } 2878 } 2879 2880 /* 2881 * Handler for MBEDTLS_SSL_SERVER_FINISHED 2882 */ 2883 MBEDTLS_CHECK_RETURN_CRITICAL 2884 static int ssl_tls13_write_server_finished(mbedtls_ssl_context *ssl) 2885 { 2886 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2887 2888 ret = mbedtls_ssl_tls13_write_finished_message(ssl); 2889 if (ret != 0) { 2890 return ret; 2891 } 2892 2893 ret = mbedtls_ssl_tls13_compute_application_transform(ssl); 2894 if (ret != 0) { 2895 MBEDTLS_SSL_PEND_FATAL_ALERT( 2896 MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, 2897 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 2898 return ret; 2899 } 2900 2901 #if defined(MBEDTLS_SSL_EARLY_DATA) 2902 if (ssl->handshake->early_data_accepted) { 2903 /* See RFC 8446 section A.2 for more information */ 2904 MBEDTLS_SSL_DEBUG_MSG( 2905 1, ("Switch to early keys for inbound traffic. " 2906 "( K_recv = early data )")); 2907 mbedtls_ssl_set_inbound_transform( 2908 ssl, ssl->handshake->transform_earlydata); 2909 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_END_OF_EARLY_DATA); 2910 return 0; 2911 } 2912 #endif /* MBEDTLS_SSL_EARLY_DATA */ 2913 MBEDTLS_SSL_DEBUG_MSG( 2914 1, ("Switch to handshake keys for inbound traffic " 2915 "( K_recv = handshake )")); 2916 mbedtls_ssl_set_inbound_transform(ssl, ssl->handshake->transform_handshake); 2917 2918 ssl_tls13_prepare_for_handshake_second_flight(ssl); 2919 2920 return 0; 2921 } 2922 2923 #if defined(MBEDTLS_SSL_EARLY_DATA) 2924 /* 2925 * Handler for MBEDTLS_SSL_END_OF_EARLY_DATA 2926 */ 2927 #define SSL_GOT_END_OF_EARLY_DATA 0 2928 #define SSL_GOT_EARLY_DATA 1 2929 /* Coordination: 2930 * Deals with the ambiguity of not knowing if the next message is an 2931 * EndOfEarlyData message or an application message containing early data. 2932 * Returns a negative code on failure, or 2933 * - SSL_GOT_END_OF_EARLY_DATA 2934 * - SSL_GOT_EARLY_DATA 2935 * indicating which message is received. 2936 */ 2937 MBEDTLS_CHECK_RETURN_CRITICAL 2938 static int ssl_tls13_end_of_early_data_coordinate(mbedtls_ssl_context *ssl) 2939 { 2940 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2941 2942 if ((ret = mbedtls_ssl_read_record(ssl, 0)) != 0) { 2943 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); 2944 return ret; 2945 } 2946 ssl->keep_current_message = 1; 2947 2948 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && 2949 ssl->in_msg[0] == MBEDTLS_SSL_HS_END_OF_EARLY_DATA) { 2950 MBEDTLS_SSL_DEBUG_MSG(3, ("Received an end_of_early_data message.")); 2951 return SSL_GOT_END_OF_EARLY_DATA; 2952 } 2953 2954 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA) { 2955 if (ssl->in_offt == NULL) { 2956 MBEDTLS_SSL_DEBUG_MSG(3, ("Received early data")); 2957 /* Set the reading pointer */ 2958 ssl->in_offt = ssl->in_msg; 2959 ret = mbedtls_ssl_tls13_check_early_data_len(ssl, ssl->in_msglen); 2960 if (ret != 0) { 2961 return ret; 2962 } 2963 } 2964 return SSL_GOT_EARLY_DATA; 2965 } 2966 2967 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE, 2968 MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE); 2969 return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; 2970 } 2971 2972 MBEDTLS_CHECK_RETURN_CRITICAL 2973 static int ssl_tls13_parse_end_of_early_data(mbedtls_ssl_context *ssl, 2974 const unsigned char *buf, 2975 const unsigned char *end) 2976 { 2977 /* RFC 8446 section 4.5 2978 * 2979 * struct {} EndOfEarlyData; 2980 */ 2981 if (buf != end) { 2982 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, 2983 MBEDTLS_ERR_SSL_DECODE_ERROR); 2984 return MBEDTLS_ERR_SSL_DECODE_ERROR; 2985 } 2986 return 0; 2987 } 2988 2989 /* 2990 * RFC 8446 section A.2 2991 * 2992 * | Send ServerHello 2993 * | K_send = handshake 2994 * | Send EncryptedExtensions 2995 * | [Send CertificateRequest] 2996 * Can send | [Send Certificate + CertificateVerify] 2997 * app data | Send Finished 2998 * after --> | K_send = application 2999 * here +--------+--------+ 3000 * No 0-RTT | | 0-RTT 3001 * | | 3002 * K_recv = handshake | | K_recv = early data 3003 * [Skip decrypt errors] | +------> WAIT_EOED -+ 3004 * | | Recv | | Recv EndOfEarlyData 3005 * | | early data | | K_recv = handshake 3006 * | +------------+ | 3007 * | | 3008 * +> WAIT_FLIGHT2 <--------+ 3009 * | 3010 * +--------+--------+ 3011 * No auth | | Client auth 3012 * | | 3013 * | v 3014 * | WAIT_CERT 3015 * | Recv | | Recv Certificate 3016 * | empty | v 3017 * | Certificate | WAIT_CV 3018 * | | | Recv 3019 * | v | CertificateVerify 3020 * +-> WAIT_FINISHED <---+ 3021 * | Recv Finished 3022 * 3023 * The function handles actions and state changes from 0-RTT to WAIT_FLIGHT2 in 3024 * the above diagram. 3025 */ 3026 MBEDTLS_CHECK_RETURN_CRITICAL 3027 static int ssl_tls13_process_end_of_early_data(mbedtls_ssl_context *ssl) 3028 { 3029 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3030 3031 MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_tls13_process_end_of_early_data")); 3032 3033 MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_end_of_early_data_coordinate(ssl)); 3034 3035 if (ret == SSL_GOT_END_OF_EARLY_DATA) { 3036 unsigned char *buf; 3037 size_t buf_len; 3038 3039 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( 3040 ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, 3041 &buf, &buf_len)); 3042 3043 MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_end_of_early_data( 3044 ssl, buf, buf + buf_len)); 3045 3046 MBEDTLS_SSL_DEBUG_MSG( 3047 1, ("Switch to handshake keys for inbound traffic" 3048 "( K_recv = handshake )")); 3049 mbedtls_ssl_set_inbound_transform( 3050 ssl, ssl->handshake->transform_handshake); 3051 3052 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 3053 ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, 3054 buf, buf_len)); 3055 3056 ssl_tls13_prepare_for_handshake_second_flight(ssl); 3057 3058 } else if (ret == SSL_GOT_EARLY_DATA) { 3059 ret = MBEDTLS_ERR_SSL_RECEIVED_EARLY_DATA; 3060 goto cleanup; 3061 } else { 3062 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); 3063 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; 3064 goto cleanup; 3065 } 3066 3067 cleanup: 3068 MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_tls13_process_end_of_early_data")); 3069 return ret; 3070 } 3071 #endif /* MBEDTLS_SSL_EARLY_DATA */ 3072 3073 /* 3074 * Handler for MBEDTLS_SSL_CLIENT_FINISHED 3075 */ 3076 MBEDTLS_CHECK_RETURN_CRITICAL 3077 static int ssl_tls13_process_client_finished(mbedtls_ssl_context *ssl) 3078 { 3079 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3080 3081 ret = mbedtls_ssl_tls13_process_finished_message(ssl); 3082 if (ret != 0) { 3083 return ret; 3084 } 3085 3086 ret = mbedtls_ssl_tls13_compute_resumption_master_secret(ssl); 3087 if (ret != 0) { 3088 MBEDTLS_SSL_DEBUG_RET( 3089 1, "mbedtls_ssl_tls13_compute_resumption_master_secret", ret); 3090 } 3091 3092 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_WRAPUP); 3093 return 0; 3094 } 3095 3096 /* 3097 * Handler for MBEDTLS_SSL_HANDSHAKE_WRAPUP 3098 */ 3099 MBEDTLS_CHECK_RETURN_CRITICAL 3100 static int ssl_tls13_handshake_wrapup(mbedtls_ssl_context *ssl) 3101 { 3102 MBEDTLS_SSL_DEBUG_MSG(2, ("handshake: done")); 3103 3104 mbedtls_ssl_tls13_handshake_wrapup(ssl); 3105 3106 #if defined(MBEDTLS_SSL_SESSION_TICKETS) && \ 3107 defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 3108 /* TODO: Remove the check of SOME_PSK_ENABLED since SESSION_TICKETS requires 3109 * SOME_PSK_ENABLED to be enabled. Here is just to make CI happy. It is 3110 * expected to be resolved with issue#6395. 3111 */ 3112 /* Sent NewSessionTicket message only when client supports PSK */ 3113 if (mbedtls_ssl_tls13_is_some_psk_supported(ssl)) { 3114 mbedtls_ssl_handshake_set_state( 3115 ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); 3116 } else 3117 #endif 3118 { 3119 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); 3120 } 3121 return 0; 3122 } 3123 3124 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 3125 /* 3126 * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET 3127 */ 3128 #define SSL_NEW_SESSION_TICKET_SKIP 0 3129 #define SSL_NEW_SESSION_TICKET_WRITE 1 3130 MBEDTLS_CHECK_RETURN_CRITICAL 3131 static int ssl_tls13_write_new_session_ticket_coordinate(mbedtls_ssl_context *ssl) 3132 { 3133 /* Check whether the use of session tickets is enabled */ 3134 if (ssl->conf->f_ticket_write == NULL) { 3135 MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: disabled," 3136 " callback is not set")); 3137 return SSL_NEW_SESSION_TICKET_SKIP; 3138 } 3139 if (ssl->conf->new_session_tickets_count == 0) { 3140 MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: disabled," 3141 " configured count is zero")); 3142 return SSL_NEW_SESSION_TICKET_SKIP; 3143 } 3144 3145 if (ssl->handshake->new_session_tickets_count == 0) { 3146 MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: all tickets have " 3147 "been sent.")); 3148 return SSL_NEW_SESSION_TICKET_SKIP; 3149 } 3150 3151 return SSL_NEW_SESSION_TICKET_WRITE; 3152 } 3153 3154 MBEDTLS_CHECK_RETURN_CRITICAL 3155 static int ssl_tls13_prepare_new_session_ticket(mbedtls_ssl_context *ssl, 3156 unsigned char *ticket_nonce, 3157 size_t ticket_nonce_size) 3158 { 3159 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3160 mbedtls_ssl_session *session = ssl->session; 3161 mbedtls_ssl_ciphersuite_t *ciphersuite_info; 3162 psa_algorithm_t psa_hash_alg; 3163 int hash_length; 3164 3165 MBEDTLS_SSL_DEBUG_MSG(2, ("=> prepare NewSessionTicket msg")); 3166 3167 /* Set ticket_flags depends on the advertised psk key exchange mode */ 3168 mbedtls_ssl_tls13_session_clear_ticket_flags( 3169 session, MBEDTLS_SSL_TLS1_3_TICKET_FLAGS_MASK); 3170 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 3171 mbedtls_ssl_tls13_session_set_ticket_flags( 3172 session, ssl->handshake->tls13_kex_modes); 3173 #endif 3174 3175 #if defined(MBEDTLS_SSL_EARLY_DATA) 3176 if (ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_ENABLED && 3177 ssl->conf->max_early_data_size > 0) { 3178 mbedtls_ssl_tls13_session_set_ticket_flags( 3179 session, MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA); 3180 session->max_early_data_size = ssl->conf->max_early_data_size; 3181 } 3182 #endif /* MBEDTLS_SSL_EARLY_DATA */ 3183 3184 MBEDTLS_SSL_PRINT_TICKET_FLAGS(4, session->ticket_flags); 3185 3186 #if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN) 3187 if (session->ticket_alpn == NULL) { 3188 ret = mbedtls_ssl_session_set_ticket_alpn(session, ssl->alpn_chosen); 3189 if (ret != 0) { 3190 return ret; 3191 } 3192 } 3193 #endif 3194 3195 /* Generate ticket_age_add */ 3196 if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, 3197 (unsigned char *) &session->ticket_age_add, 3198 sizeof(session->ticket_age_add)) != 0)) { 3199 MBEDTLS_SSL_DEBUG_RET(1, "generate_ticket_age_add", ret); 3200 return ret; 3201 } 3202 MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", 3203 (unsigned int) session->ticket_age_add)); 3204 3205 /* Generate ticket_nonce */ 3206 ret = ssl->conf->f_rng(ssl->conf->p_rng, ticket_nonce, ticket_nonce_size); 3207 if (ret != 0) { 3208 MBEDTLS_SSL_DEBUG_RET(1, "generate_ticket_nonce", ret); 3209 return ret; 3210 } 3211 MBEDTLS_SSL_DEBUG_BUF(3, "ticket_nonce:", 3212 ticket_nonce, ticket_nonce_size); 3213 3214 ciphersuite_info = 3215 (mbedtls_ssl_ciphersuite_t *) ssl->handshake->ciphersuite_info; 3216 psa_hash_alg = mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) ciphersuite_info->mac); 3217 hash_length = PSA_HASH_LENGTH(psa_hash_alg); 3218 if (hash_length == -1 || 3219 (size_t) hash_length > sizeof(session->resumption_key)) { 3220 return MBEDTLS_ERR_SSL_INTERNAL_ERROR; 3221 } 3222 3223 /* In this code the psk key length equals the length of the hash */ 3224 session->resumption_key_len = hash_length; 3225 session->ciphersuite = ciphersuite_info->id; 3226 3227 /* Compute resumption key 3228 * 3229 * HKDF-Expand-Label( resumption_master_secret, 3230 * "resumption", ticket_nonce, Hash.length ) 3231 */ 3232 ret = mbedtls_ssl_tls13_hkdf_expand_label( 3233 psa_hash_alg, 3234 session->app_secrets.resumption_master_secret, 3235 hash_length, 3236 MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN(resumption), 3237 ticket_nonce, 3238 ticket_nonce_size, 3239 session->resumption_key, 3240 hash_length); 3241 3242 if (ret != 0) { 3243 MBEDTLS_SSL_DEBUG_RET(2, 3244 "Creating the ticket-resumed PSK failed", 3245 ret); 3246 return ret; 3247 } 3248 MBEDTLS_SSL_DEBUG_BUF(3, "Ticket-resumed PSK", 3249 session->resumption_key, 3250 session->resumption_key_len); 3251 3252 MBEDTLS_SSL_DEBUG_BUF(3, "resumption_master_secret", 3253 session->app_secrets.resumption_master_secret, 3254 hash_length); 3255 3256 return 0; 3257 } 3258 3259 /* This function creates a NewSessionTicket message in the following format: 3260 * 3261 * struct { 3262 * uint32 ticket_lifetime; 3263 * uint32 ticket_age_add; 3264 * opaque ticket_nonce<0..255>; 3265 * opaque ticket<1..2^16-1>; 3266 * Extension extensions<0..2^16-2>; 3267 * } NewSessionTicket; 3268 * 3269 * The ticket inside the NewSessionTicket message is an encrypted container 3270 * carrying the necessary information so that the server is later able to 3271 * re-start the communication. 3272 * 3273 * The following fields are placed inside the ticket by the 3274 * f_ticket_write() function: 3275 * 3276 * - creation time (ticket_creation_time) 3277 * - flags (ticket_flags) 3278 * - age add (ticket_age_add) 3279 * - key (resumption_key) 3280 * - key length (resumption_key_len) 3281 * - ciphersuite (ciphersuite) 3282 * - max_early_data_size (max_early_data_size) 3283 */ 3284 MBEDTLS_CHECK_RETURN_CRITICAL 3285 static int ssl_tls13_write_new_session_ticket_body(mbedtls_ssl_context *ssl, 3286 unsigned char *buf, 3287 unsigned char *end, 3288 size_t *out_len, 3289 unsigned char *ticket_nonce, 3290 size_t ticket_nonce_size) 3291 { 3292 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3293 unsigned char *p = buf; 3294 mbedtls_ssl_session *session = ssl->session; 3295 size_t ticket_len; 3296 uint32_t ticket_lifetime; 3297 unsigned char *p_extensions_len; 3298 3299 *out_len = 0; 3300 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write NewSessionTicket msg")); 3301 3302 /* 3303 * ticket_lifetime 4 bytes 3304 * ticket_age_add 4 bytes 3305 * ticket_nonce 1 + ticket_nonce_size bytes 3306 * ticket >=2 bytes 3307 */ 3308 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 4 + 4 + 1 + ticket_nonce_size + 2); 3309 3310 /* Generate ticket and ticket_lifetime */ 3311 #if defined(MBEDTLS_HAVE_TIME) 3312 session->ticket_creation_time = mbedtls_ms_time(); 3313 #endif 3314 ret = ssl->conf->f_ticket_write(ssl->conf->p_ticket, 3315 session, 3316 p + 9 + ticket_nonce_size + 2, 3317 end, 3318 &ticket_len, 3319 &ticket_lifetime); 3320 if (ret != 0) { 3321 MBEDTLS_SSL_DEBUG_RET(1, "write_ticket", ret); 3322 return ret; 3323 } 3324 3325 /* RFC 8446 section 4.6.1 3326 * 3327 * ticket_lifetime: Indicates the lifetime in seconds as a 32-bit 3328 * unsigned integer in network byte order from the time of ticket 3329 * issuance. Servers MUST NOT use any value greater than 3330 * 604800 seconds (7 days) ... 3331 */ 3332 if (ticket_lifetime > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME) { 3333 MBEDTLS_SSL_DEBUG_MSG( 3334 1, ("Ticket lifetime (%u) is greater than 7 days.", 3335 (unsigned int) ticket_lifetime)); 3336 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; 3337 } 3338 3339 MBEDTLS_PUT_UINT32_BE(ticket_lifetime, p, 0); 3340 MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_lifetime: %u", 3341 (unsigned int) ticket_lifetime)); 3342 3343 /* Write ticket_age_add */ 3344 MBEDTLS_PUT_UINT32_BE(session->ticket_age_add, p, 4); 3345 MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", 3346 (unsigned int) session->ticket_age_add)); 3347 3348 /* Write ticket_nonce */ 3349 p[8] = (unsigned char) ticket_nonce_size; 3350 if (ticket_nonce_size > 0) { 3351 memcpy(p + 9, ticket_nonce, ticket_nonce_size); 3352 } 3353 p += 9 + ticket_nonce_size; 3354 3355 /* Write ticket */ 3356 MBEDTLS_PUT_UINT16_BE(ticket_len, p, 0); 3357 p += 2; 3358 MBEDTLS_SSL_DEBUG_BUF(4, "ticket", p, ticket_len); 3359 p += ticket_len; 3360 3361 /* Ticket Extensions 3362 * 3363 * Extension extensions<0..2^16-2>; 3364 */ 3365 ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; 3366 3367 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 3368 p_extensions_len = p; 3369 p += 2; 3370 3371 #if defined(MBEDTLS_SSL_EARLY_DATA) 3372 if (mbedtls_ssl_tls13_session_ticket_allow_early_data(session)) { 3373 size_t output_len; 3374 3375 if ((ret = mbedtls_ssl_tls13_write_early_data_ext( 3376 ssl, 1, p, end, &output_len)) != 0) { 3377 MBEDTLS_SSL_DEBUG_RET( 3378 1, "mbedtls_ssl_tls13_write_early_data_ext", ret); 3379 return ret; 3380 } 3381 p += output_len; 3382 } else { 3383 MBEDTLS_SSL_DEBUG_MSG( 3384 4, ("early_data not allowed, " 3385 "skip early_data extension in NewSessionTicket")); 3386 } 3387 3388 #endif /* MBEDTLS_SSL_EARLY_DATA */ 3389 3390 MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); 3391 3392 *out_len = p - buf; 3393 MBEDTLS_SSL_DEBUG_BUF(4, "ticket", buf, *out_len); 3394 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write new session ticket")); 3395 3396 MBEDTLS_SSL_PRINT_EXTS( 3397 3, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, ssl->handshake->sent_extensions); 3398 3399 return 0; 3400 } 3401 3402 /* 3403 * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET 3404 */ 3405 static int ssl_tls13_write_new_session_ticket(mbedtls_ssl_context *ssl) 3406 { 3407 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3408 3409 MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_write_new_session_ticket_coordinate(ssl)); 3410 3411 if (ret == SSL_NEW_SESSION_TICKET_WRITE) { 3412 unsigned char ticket_nonce[MBEDTLS_SSL_TLS1_3_TICKET_NONCE_LENGTH]; 3413 unsigned char *buf; 3414 size_t buf_len, msg_len; 3415 3416 MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_new_session_ticket( 3417 ssl, ticket_nonce, sizeof(ticket_nonce))); 3418 3419 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 3420 ssl, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, 3421 &buf, &buf_len)); 3422 3423 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_new_session_ticket_body( 3424 ssl, buf, buf + buf_len, &msg_len, 3425 ticket_nonce, sizeof(ticket_nonce))); 3426 3427 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( 3428 ssl, buf_len, msg_len)); 3429 3430 /* Limit session tickets count to one when resumption connection. 3431 * 3432 * See document of mbedtls_ssl_conf_new_session_tickets. 3433 */ 3434 if (ssl->handshake->resume == 1) { 3435 ssl->handshake->new_session_tickets_count = 0; 3436 } else { 3437 ssl->handshake->new_session_tickets_count--; 3438 } 3439 3440 mbedtls_ssl_handshake_set_state( 3441 ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET_FLUSH); 3442 } else { 3443 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); 3444 } 3445 3446 cleanup: 3447 3448 return ret; 3449 } 3450 #endif /* MBEDTLS_SSL_SESSION_TICKETS */ 3451 3452 /* 3453 * TLS 1.3 State Machine -- server side 3454 */ 3455 int mbedtls_ssl_tls13_handshake_server_step(mbedtls_ssl_context *ssl) 3456 { 3457 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3458 3459 if (ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL) { 3460 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; 3461 } 3462 3463 MBEDTLS_SSL_DEBUG_MSG(2, ("tls13 server state: %s(%d)", 3464 mbedtls_ssl_states_str((mbedtls_ssl_states) ssl->state), 3465 ssl->state)); 3466 3467 switch (ssl->state) { 3468 /* start state */ 3469 case MBEDTLS_SSL_HELLO_REQUEST: 3470 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); 3471 ret = 0; 3472 break; 3473 3474 case MBEDTLS_SSL_CLIENT_HELLO: 3475 ret = ssl_tls13_process_client_hello(ssl); 3476 if (ret != 0) { 3477 MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_process_client_hello", ret); 3478 } 3479 break; 3480 3481 case MBEDTLS_SSL_HELLO_RETRY_REQUEST: 3482 ret = ssl_tls13_write_hello_retry_request(ssl); 3483 if (ret != 0) { 3484 MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_hello_retry_request", ret); 3485 return ret; 3486 } 3487 break; 3488 3489 case MBEDTLS_SSL_SERVER_HELLO: 3490 ret = ssl_tls13_write_server_hello(ssl); 3491 break; 3492 3493 case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS: 3494 ret = ssl_tls13_write_encrypted_extensions(ssl); 3495 if (ret != 0) { 3496 MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_encrypted_extensions", ret); 3497 return ret; 3498 } 3499 break; 3500 3501 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 3502 case MBEDTLS_SSL_CERTIFICATE_REQUEST: 3503 ret = ssl_tls13_write_certificate_request(ssl); 3504 break; 3505 3506 case MBEDTLS_SSL_SERVER_CERTIFICATE: 3507 ret = ssl_tls13_write_server_certificate(ssl); 3508 break; 3509 3510 case MBEDTLS_SSL_CERTIFICATE_VERIFY: 3511 ret = ssl_tls13_write_certificate_verify(ssl); 3512 break; 3513 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 3514 3515 /* 3516 * Injection of dummy-CCS's for middlebox compatibility 3517 */ 3518 #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) 3519 case MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST: 3520 ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); 3521 if (ret == 0) { 3522 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); 3523 } 3524 break; 3525 3526 case MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO: 3527 ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); 3528 if (ret != 0) { 3529 break; 3530 } 3531 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); 3532 break; 3533 #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ 3534 3535 case MBEDTLS_SSL_SERVER_FINISHED: 3536 ret = ssl_tls13_write_server_finished(ssl); 3537 break; 3538 3539 #if defined(MBEDTLS_SSL_EARLY_DATA) 3540 case MBEDTLS_SSL_END_OF_EARLY_DATA: 3541 ret = ssl_tls13_process_end_of_early_data(ssl); 3542 break; 3543 #endif /* MBEDTLS_SSL_EARLY_DATA */ 3544 3545 case MBEDTLS_SSL_CLIENT_FINISHED: 3546 ret = ssl_tls13_process_client_finished(ssl); 3547 break; 3548 3549 case MBEDTLS_SSL_HANDSHAKE_WRAPUP: 3550 ret = ssl_tls13_handshake_wrapup(ssl); 3551 break; 3552 3553 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 3554 case MBEDTLS_SSL_CLIENT_CERTIFICATE: 3555 ret = mbedtls_ssl_tls13_process_certificate(ssl); 3556 if (ret == 0) { 3557 if (ssl->session_negotiate->peer_cert != NULL) { 3558 mbedtls_ssl_handshake_set_state( 3559 ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY); 3560 } else { 3561 MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate verify")); 3562 mbedtls_ssl_handshake_set_state( 3563 ssl, MBEDTLS_SSL_CLIENT_FINISHED); 3564 } 3565 } 3566 break; 3567 3568 case MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY: 3569 ret = mbedtls_ssl_tls13_process_certificate_verify(ssl); 3570 if (ret == 0) { 3571 mbedtls_ssl_handshake_set_state( 3572 ssl, MBEDTLS_SSL_CLIENT_FINISHED); 3573 } 3574 break; 3575 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 3576 3577 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 3578 case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET: 3579 ret = ssl_tls13_write_new_session_ticket(ssl); 3580 if (ret != 0) { 3581 MBEDTLS_SSL_DEBUG_RET(1, 3582 "ssl_tls13_write_new_session_ticket ", 3583 ret); 3584 } 3585 break; 3586 case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET_FLUSH: 3587 /* This state is necessary to do the flush of the New Session 3588 * Ticket message written in MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET 3589 * as part of ssl_prepare_handshake_step. 3590 */ 3591 ret = 0; 3592 3593 if (ssl->handshake->new_session_tickets_count == 0) { 3594 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); 3595 } else { 3596 mbedtls_ssl_handshake_set_state( 3597 ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); 3598 } 3599 break; 3600 3601 #endif /* MBEDTLS_SSL_SESSION_TICKETS */ 3602 3603 default: 3604 MBEDTLS_SSL_DEBUG_MSG(1, ("invalid state %d", ssl->state)); 3605 return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; 3606 } 3607 3608 return ret; 3609 } 3610 3611 #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_TLS1_3 */