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(2, ("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 return SSL_CLIENT_HELLO_TLS1_2; 1384 } 1385 1386 if (ret == 1) { 1387 ret = ssl_tls13_parse_supported_versions_ext(ssl, 1388 supported_versions_data, 1389 supported_versions_data_end); 1390 if (ret < 0) { 1391 MBEDTLS_SSL_DEBUG_RET(1, 1392 ("ssl_tls13_parse_supported_versions_ext"), ret); 1393 return ret; 1394 } 1395 1396 /* 1397 * The supported versions extension was parsed successfully as the 1398 * value returned by ssl_tls13_parse_supported_versions_ext() is 1399 * positive. The return value is then equal to 1400 * MBEDTLS_SSL_VERSION_TLS1_2 or MBEDTLS_SSL_VERSION_TLS1_3, defining 1401 * the TLS version to negotiate. 1402 */ 1403 if (MBEDTLS_SSL_VERSION_TLS1_2 == ret) { 1404 return SSL_CLIENT_HELLO_TLS1_2; 1405 } 1406 } 1407 1408 /* 1409 * We negotiate TLS 1.3. 1410 */ 1411 ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; 1412 ssl->session_negotiate->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; 1413 ssl->session_negotiate->endpoint = ssl->conf->endpoint; 1414 1415 /* Before doing any crypto, make sure we can. */ 1416 ret = mbedtls_ssl_tls13_crypto_init(ssl); 1417 if (ret != 0) { 1418 return ret; 1419 } 1420 1421 /* 1422 * We are negotiating the version 1.3 of the protocol. Do what we have 1423 * postponed: copy of the client random bytes, copy of the legacy session 1424 * identifier and selection of the TLS 1.3 cipher suite. 1425 */ 1426 MBEDTLS_SSL_DEBUG_BUF(3, "client hello, random bytes", 1427 random, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); 1428 memcpy(&handshake->randbytes[0], random, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); 1429 1430 if (legacy_session_id_len > sizeof(ssl->session_negotiate->id)) { 1431 MBEDTLS_SSL_DEBUG_MSG(1, ("bad client hello message")); 1432 return MBEDTLS_ERR_SSL_DECODE_ERROR; 1433 } 1434 ssl->session_negotiate->id_len = legacy_session_id_len; 1435 MBEDTLS_SSL_DEBUG_BUF(3, "client hello, session id", 1436 legacy_session_id, legacy_session_id_len); 1437 memcpy(&ssl->session_negotiate->id[0], 1438 legacy_session_id, legacy_session_id_len); 1439 1440 /* 1441 * Search for a matching ciphersuite 1442 */ 1443 MBEDTLS_SSL_DEBUG_BUF(3, "client hello, list of cipher suites", 1444 cipher_suites, cipher_suites_len); 1445 1446 ssl_tls13_select_ciphersuite(ssl, cipher_suites, cipher_suites_end, 1447 0, PSA_ALG_NONE, &handshake->ciphersuite_info); 1448 1449 if (handshake->ciphersuite_info == NULL) { 1450 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, 1451 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 1452 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 1453 } 1454 ssl->session_negotiate->ciphersuite = handshake->ciphersuite_info->id; 1455 1456 MBEDTLS_SSL_DEBUG_MSG(2, ("selected ciphersuite: %04x - %s", 1457 ((unsigned) handshake->ciphersuite_info->id), 1458 handshake->ciphersuite_info->name)); 1459 1460 /* ... 1461 * opaque legacy_compression_methods<1..2^8-1>; 1462 * ... 1463 */ 1464 if (p[0] != 1 || p[1] != MBEDTLS_SSL_COMPRESS_NULL) { 1465 MBEDTLS_SSL_DEBUG_MSG(1, ("bad legacy compression method")); 1466 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, 1467 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 1468 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 1469 } 1470 p += 2; 1471 1472 /* ... 1473 * Extension extensions<8..2^16-1>; 1474 * ... 1475 * with Extension defined as: 1476 * struct { 1477 * ExtensionType extension_type; 1478 * opaque extension_data<0..2^16-1>; 1479 * } Extension; 1480 */ 1481 extensions_len = MBEDTLS_GET_UINT16_BE(p, 0); 1482 p += 2; 1483 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extensions_len); 1484 extensions_end = p + extensions_len; 1485 1486 MBEDTLS_SSL_DEBUG_BUF(3, "client hello extensions", p, extensions_len); 1487 handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE; 1488 1489 while (p < extensions_end) { 1490 unsigned int extension_type; 1491 size_t extension_data_len; 1492 const unsigned char *extension_data_end; 1493 uint32_t allowed_exts = MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CH; 1494 1495 if (ssl->handshake->hello_retry_request_flag) { 1496 /* Do not accept early data extension in 2nd ClientHello */ 1497 allowed_exts &= ~MBEDTLS_SSL_EXT_MASK(EARLY_DATA); 1498 } 1499 1500 /* RFC 8446, section 4.2.11 1501 * 1502 * The "pre_shared_key" extension MUST be the last extension in the 1503 * ClientHello (this facilitates implementation as described below). 1504 * Servers MUST check that it is the last extension and otherwise fail 1505 * the handshake with an "illegal_parameter" alert. 1506 */ 1507 if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY)) { 1508 MBEDTLS_SSL_DEBUG_MSG( 1509 3, ("pre_shared_key is not last extension.")); 1510 MBEDTLS_SSL_PEND_FATAL_ALERT( 1511 MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, 1512 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 1513 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 1514 } 1515 1516 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, 4); 1517 extension_type = MBEDTLS_GET_UINT16_BE(p, 0); 1518 extension_data_len = MBEDTLS_GET_UINT16_BE(p, 2); 1519 p += 4; 1520 1521 MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, extension_data_len); 1522 extension_data_end = p + extension_data_len; 1523 1524 ret = mbedtls_ssl_tls13_check_received_extension( 1525 ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, extension_type, 1526 allowed_exts); 1527 if (ret != 0) { 1528 return ret; 1529 } 1530 1531 switch (extension_type) { 1532 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) 1533 case MBEDTLS_TLS_EXT_SERVERNAME: 1534 MBEDTLS_SSL_DEBUG_MSG(3, ("found ServerName extension")); 1535 ret = mbedtls_ssl_parse_server_name_ext(ssl, p, 1536 extension_data_end); 1537 if (ret != 0) { 1538 MBEDTLS_SSL_DEBUG_RET( 1539 1, "mbedtls_ssl_parse_servername_ext", ret); 1540 return ret; 1541 } 1542 break; 1543 #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ 1544 1545 #if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) 1546 case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS: 1547 MBEDTLS_SSL_DEBUG_MSG(3, ("found supported group extension")); 1548 1549 /* Supported Groups Extension 1550 * 1551 * When sent by the client, the "supported_groups" extension 1552 * indicates the named groups which the client supports, 1553 * ordered from most preferred to least preferred. 1554 */ 1555 ret = ssl_tls13_parse_supported_groups_ext( 1556 ssl, p, extension_data_end); 1557 if (ret != 0) { 1558 MBEDTLS_SSL_DEBUG_RET( 1559 1, "ssl_tls13_parse_supported_groups_ext", ret); 1560 return ret; 1561 } 1562 1563 break; 1564 #endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH*/ 1565 1566 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) 1567 case MBEDTLS_TLS_EXT_KEY_SHARE: 1568 MBEDTLS_SSL_DEBUG_MSG(3, ("found key share extension")); 1569 1570 /* 1571 * Key Share Extension 1572 * 1573 * When sent by the client, the "key_share" extension 1574 * contains the endpoint's cryptographic parameters for 1575 * ECDHE/DHE key establishment methods. 1576 */ 1577 ret = ssl_tls13_parse_key_shares_ext( 1578 ssl, p, extension_data_end); 1579 if (ret == SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH) { 1580 MBEDTLS_SSL_DEBUG_MSG(2, ("No usable share for key agreement.")); 1581 no_usable_share_for_key_agreement = 1; 1582 } 1583 1584 if (ret < 0) { 1585 MBEDTLS_SSL_DEBUG_RET( 1586 1, "ssl_tls13_parse_key_shares_ext", ret); 1587 return ret; 1588 } 1589 1590 break; 1591 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ 1592 1593 case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS: 1594 /* Already parsed */ 1595 break; 1596 1597 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1598 case MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES: 1599 MBEDTLS_SSL_DEBUG_MSG( 1600 3, ("found psk key exchange modes extension")); 1601 1602 ret = ssl_tls13_parse_key_exchange_modes_ext( 1603 ssl, p, extension_data_end); 1604 if (ret != 0) { 1605 MBEDTLS_SSL_DEBUG_RET( 1606 1, "ssl_tls13_parse_key_exchange_modes_ext", ret); 1607 return ret; 1608 } 1609 1610 break; 1611 #endif 1612 1613 case MBEDTLS_TLS_EXT_PRE_SHARED_KEY: 1614 MBEDTLS_SSL_DEBUG_MSG(3, ("found pre_shared_key extension")); 1615 if ((handshake->received_extensions & 1616 MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)) == 0) { 1617 MBEDTLS_SSL_PEND_FATAL_ALERT( 1618 MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, 1619 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 1620 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 1621 } 1622 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1623 /* Delay processing of the PSK identity once we have 1624 * found out which algorithms to use. We keep a pointer 1625 * to the buffer and the size for later processing. 1626 */ 1627 pre_shared_key_ext = p; 1628 pre_shared_key_ext_end = extension_data_end; 1629 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ 1630 break; 1631 1632 #if defined(MBEDTLS_SSL_ALPN) 1633 case MBEDTLS_TLS_EXT_ALPN: 1634 MBEDTLS_SSL_DEBUG_MSG(3, ("found alpn extension")); 1635 1636 ret = mbedtls_ssl_parse_alpn_ext(ssl, p, extension_data_end); 1637 if (ret != 0) { 1638 MBEDTLS_SSL_DEBUG_RET( 1639 1, ("mbedtls_ssl_parse_alpn_ext"), ret); 1640 return ret; 1641 } 1642 break; 1643 #endif /* MBEDTLS_SSL_ALPN */ 1644 1645 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 1646 case MBEDTLS_TLS_EXT_SIG_ALG: 1647 MBEDTLS_SSL_DEBUG_MSG(3, ("found signature_algorithms extension")); 1648 1649 ret = mbedtls_ssl_parse_sig_alg_ext( 1650 ssl, p, extension_data_end); 1651 if (ret != 0) { 1652 MBEDTLS_SSL_DEBUG_RET( 1653 1, "mbedtls_ssl_parse_sig_alg_ext", ret); 1654 return ret; 1655 } 1656 break; 1657 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 1658 1659 #if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) 1660 case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT: 1661 MBEDTLS_SSL_DEBUG_MSG(3, ("found record_size_limit extension")); 1662 1663 ret = mbedtls_ssl_tls13_parse_record_size_limit_ext( 1664 ssl, p, extension_data_end); 1665 if (ret != 0) { 1666 MBEDTLS_SSL_DEBUG_RET( 1667 1, ("mbedtls_ssl_tls13_parse_record_size_limit_ext"), ret); 1668 return ret; 1669 } 1670 break; 1671 #endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */ 1672 1673 default: 1674 MBEDTLS_SSL_PRINT_EXT( 1675 3, MBEDTLS_SSL_HS_CLIENT_HELLO, 1676 extension_type, "( ignored )"); 1677 break; 1678 } 1679 1680 p += extension_data_len; 1681 } 1682 1683 MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_CLIENT_HELLO, 1684 handshake->received_extensions); 1685 1686 ret = mbedtls_ssl_add_hs_hdr_to_checksum(ssl, 1687 MBEDTLS_SSL_HS_CLIENT_HELLO, 1688 p - buf); 1689 if (0 != ret) { 1690 MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_add_hs_hdr_to_checksum"), ret); 1691 return ret; 1692 } 1693 1694 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1695 /* Update checksum with either 1696 * - The entire content of the CH message, if no PSK extension is present 1697 * - The content up to but excluding the PSK extension, if present. 1698 * Always parse the pre-shared-key extension when present in the 1699 * ClientHello even if some pre-requisites for PSK key exchange modes are 1700 * not met. That way we always validate the syntax of the extension. 1701 */ 1702 if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY)) { 1703 ret = handshake->update_checksum(ssl, buf, 1704 pre_shared_key_ext - buf); 1705 if (0 != ret) { 1706 MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); 1707 return ret; 1708 } 1709 ret = ssl_tls13_parse_pre_shared_key_ext(ssl, 1710 pre_shared_key_ext, 1711 pre_shared_key_ext_end, 1712 cipher_suites, 1713 cipher_suites_end, 1714 &psk); 1715 if (ret == 0) { 1716 got_psk = 1; 1717 } else if (ret != MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY) { 1718 MBEDTLS_SSL_DEBUG_RET( 1719 1, "ssl_tls13_parse_pre_shared_key_ext", ret); 1720 return ret; 1721 } 1722 } else 1723 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ 1724 { 1725 ret = handshake->update_checksum(ssl, buf, p - buf); 1726 if (0 != ret) { 1727 MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); 1728 return ret; 1729 } 1730 } 1731 1732 /* 1733 * Determine the key exchange algorithm to use. 1734 * There are three types of key exchanges supported in TLS 1.3: 1735 * - (EC)DH with ECDSA, 1736 * - (EC)DH with PSK, 1737 * - plain PSK. 1738 * 1739 * The PSK-based key exchanges may additionally be used with 0-RTT. 1740 * 1741 * Our built-in order of preference is 1742 * 1 ) (EC)DHE-PSK Mode ( psk_ephemeral ) 1743 * 2 ) Certificate Mode ( ephemeral ) 1744 * 3 ) Plain PSK Mode ( psk ) 1745 */ 1746 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1747 if (got_psk && (psk.key_exchange_mode == 1748 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL)) { 1749 handshake->key_exchange_mode = 1750 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; 1751 MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: psk_ephemeral")); 1752 1753 } else 1754 #endif 1755 if (ssl_tls13_key_exchange_is_ephemeral_available(ssl)) { 1756 handshake->key_exchange_mode = 1757 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL; 1758 MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: ephemeral")); 1759 1760 } 1761 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1762 else if (got_psk && (psk.key_exchange_mode == 1763 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK)) { 1764 handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; 1765 MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: psk")); 1766 } 1767 #endif 1768 else { 1769 MBEDTLS_SSL_DEBUG_MSG( 1770 1, 1771 ("ClientHello message misses mandatory extensions.")); 1772 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION, 1773 MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); 1774 return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; 1775 } 1776 1777 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 1778 if (handshake->key_exchange_mode & 1779 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL) { 1780 handshake->ciphersuite_info = psk.ciphersuite_info; 1781 ssl->session_negotiate->ciphersuite = psk.ciphersuite_info->id; 1782 1783 MBEDTLS_SSL_DEBUG_MSG(2, ("Select PSK ciphersuite: %04x - %s", 1784 ((unsigned) psk.ciphersuite_info->id), 1785 psk.ciphersuite_info->name)); 1786 1787 if (psk.type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION) { 1788 handshake->resume = 1; 1789 } 1790 } 1791 #endif 1792 1793 if (handshake->key_exchange_mode != 1794 MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK) { 1795 hrr_required = (no_usable_share_for_key_agreement != 0); 1796 } 1797 1798 mbedtls_ssl_optimize_checksum(ssl, handshake->ciphersuite_info); 1799 1800 return hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK; 1801 } 1802 1803 #if defined(MBEDTLS_SSL_EARLY_DATA) 1804 static int ssl_tls13_check_early_data_requirements(mbedtls_ssl_context *ssl) 1805 { 1806 mbedtls_ssl_handshake_params *handshake = ssl->handshake; 1807 1808 if (ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_DISABLED) { 1809 MBEDTLS_SSL_DEBUG_MSG( 1810 1, 1811 ("EarlyData: rejected, feature disabled in server configuration.")); 1812 return -1; 1813 } 1814 1815 if (!handshake->resume) { 1816 /* We currently support early data only in the case of PSKs established 1817 via a NewSessionTicket message thus in the case of a session 1818 resumption. */ 1819 MBEDTLS_SSL_DEBUG_MSG( 1820 1, ("EarlyData: rejected, not a session resumption.")); 1821 return -1; 1822 } 1823 1824 /* RFC 8446 4.2.10 1825 * 1826 * In order to accept early data, the server MUST have accepted a PSK cipher 1827 * suite and selected the first key offered in the client's "pre_shared_key" 1828 * extension. In addition, it MUST verify that the following values are the 1829 * same as those associated with the selected PSK: 1830 * - The TLS version number 1831 * - The selected cipher suite 1832 * - The selected ALPN [RFC7301] protocol, if any 1833 * 1834 * NOTE: 1835 * - The TLS version number is checked in 1836 * ssl_tls13_offered_psks_check_identity_match_ticket(). 1837 */ 1838 1839 if (handshake->selected_identity != 0) { 1840 MBEDTLS_SSL_DEBUG_MSG( 1841 1, ("EarlyData: rejected, the selected key in " 1842 "`pre_shared_key` is not the first one.")); 1843 return -1; 1844 } 1845 1846 if (handshake->ciphersuite_info->id != 1847 ssl->session_negotiate->ciphersuite) { 1848 MBEDTLS_SSL_DEBUG_MSG( 1849 1, ("EarlyData: rejected, the selected ciphersuite is not the one " 1850 "of the selected pre-shared key.")); 1851 return -1; 1852 1853 } 1854 1855 if (!mbedtls_ssl_tls13_session_ticket_allow_early_data(ssl->session_negotiate)) { 1856 MBEDTLS_SSL_DEBUG_MSG( 1857 1, 1858 ("EarlyData: rejected, early_data not allowed in ticket " 1859 "permission bits.")); 1860 return -1; 1861 } 1862 1863 #if defined(MBEDTLS_SSL_ALPN) 1864 const char *alpn = mbedtls_ssl_get_alpn_protocol(ssl); 1865 size_t alpn_len; 1866 1867 if (alpn == NULL && ssl->session_negotiate->ticket_alpn == NULL) { 1868 return 0; 1869 } 1870 1871 if (alpn != NULL) { 1872 alpn_len = strlen(alpn); 1873 } 1874 1875 if (alpn == NULL || 1876 ssl->session_negotiate->ticket_alpn == NULL || 1877 alpn_len != strlen(ssl->session_negotiate->ticket_alpn) || 1878 (memcmp(alpn, ssl->session_negotiate->ticket_alpn, alpn_len) != 0)) { 1879 MBEDTLS_SSL_DEBUG_MSG(1, ("EarlyData: rejected, the selected ALPN is different " 1880 "from the one associated with the pre-shared key.")); 1881 return -1; 1882 } 1883 #endif 1884 1885 return 0; 1886 } 1887 #endif /* MBEDTLS_SSL_EARLY_DATA */ 1888 1889 /* Update the handshake state machine */ 1890 1891 MBEDTLS_CHECK_RETURN_CRITICAL 1892 static int ssl_tls13_postprocess_client_hello(mbedtls_ssl_context *ssl, 1893 int hrr_required) 1894 { 1895 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 1896 1897 /* 1898 * Server certificate selection 1899 */ 1900 if (ssl->conf->f_cert_cb && (ret = ssl->conf->f_cert_cb(ssl)) != 0) { 1901 MBEDTLS_SSL_DEBUG_RET(1, "f_cert_cb", ret); 1902 return ret; 1903 } 1904 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) 1905 ssl->handshake->sni_name = NULL; 1906 ssl->handshake->sni_name_len = 0; 1907 #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ 1908 1909 ret = mbedtls_ssl_tls13_key_schedule_stage_early(ssl); 1910 if (ret != 0) { 1911 MBEDTLS_SSL_DEBUG_RET(1, 1912 "mbedtls_ssl_tls1_3_key_schedule_stage_early", ret); 1913 return ret; 1914 } 1915 1916 #if defined(MBEDTLS_SSL_EARLY_DATA) 1917 if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(EARLY_DATA)) { 1918 ssl->handshake->early_data_accepted = 1919 (!hrr_required) && (ssl_tls13_check_early_data_requirements(ssl) == 0); 1920 1921 if (ssl->handshake->early_data_accepted) { 1922 ret = mbedtls_ssl_tls13_compute_early_transform(ssl); 1923 if (ret != 0) { 1924 MBEDTLS_SSL_DEBUG_RET( 1925 1, "mbedtls_ssl_tls13_compute_early_transform", ret); 1926 return ret; 1927 } 1928 } else { 1929 ssl->discard_early_data_record = 1930 hrr_required ? 1931 MBEDTLS_SSL_EARLY_DATA_DISCARD : 1932 MBEDTLS_SSL_EARLY_DATA_TRY_TO_DEPROTECT_AND_DISCARD; 1933 } 1934 } 1935 #else 1936 ((void) hrr_required); 1937 #endif /* MBEDTLS_SSL_EARLY_DATA */ 1938 1939 return 0; 1940 } 1941 1942 /* 1943 * Main entry point from the state machine; orchestrates the otherfunctions. 1944 */ 1945 1946 MBEDTLS_CHECK_RETURN_CRITICAL 1947 static int ssl_tls13_process_client_hello(mbedtls_ssl_context *ssl) 1948 { 1949 1950 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 1951 unsigned char *buf = NULL; 1952 size_t buflen = 0; 1953 int parse_client_hello_ret; 1954 1955 MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse client hello")); 1956 1957 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( 1958 ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, 1959 &buf, &buflen)); 1960 1961 MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_parse_client_hello(ssl, buf, 1962 buf + buflen)); 1963 parse_client_hello_ret = ret; /* Store positive return value of 1964 * parse_client_hello, 1965 * as negative error codes are handled 1966 * by MBEDTLS_SSL_PROC_CHK_NEG. */ 1967 1968 /* 1969 * Version 1.2 of the protocol has to be used for the handshake. 1970 * If TLS 1.2 is not supported, abort the handshake. Otherwise, set the 1971 * ssl->keep_current_message flag for the ClientHello to be kept and parsed 1972 * as a TLS 1.2 ClientHello. We also change ssl->tls_version to 1973 * MBEDTLS_SSL_VERSION_TLS1_2 thus from now on mbedtls_ssl_handshake_step() 1974 * will dispatch to the TLS 1.2 state machine. 1975 */ 1976 if (SSL_CLIENT_HELLO_TLS1_2 == parse_client_hello_ret) { 1977 /* Check if server supports TLS 1.2 */ 1978 if (!mbedtls_ssl_conf_is_tls12_enabled(ssl->conf)) { 1979 MBEDTLS_SSL_DEBUG_MSG( 1980 1, ("TLS 1.2 not supported.")); 1981 MBEDTLS_SSL_PEND_FATAL_ALERT( 1982 MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, 1983 MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); 1984 return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; 1985 } 1986 ssl->keep_current_message = 1; 1987 ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_2; 1988 return 0; 1989 } 1990 1991 MBEDTLS_SSL_PROC_CHK( 1992 ssl_tls13_postprocess_client_hello(ssl, parse_client_hello_ret == 1993 SSL_CLIENT_HELLO_HRR_REQUIRED)); 1994 1995 if (SSL_CLIENT_HELLO_OK == parse_client_hello_ret) { 1996 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_HELLO); 1997 } else { 1998 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HELLO_RETRY_REQUEST); 1999 } 2000 2001 cleanup: 2002 2003 MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse client hello")); 2004 return ret; 2005 } 2006 2007 /* 2008 * Handler for MBEDTLS_SSL_SERVER_HELLO 2009 */ 2010 MBEDTLS_CHECK_RETURN_CRITICAL 2011 static int ssl_tls13_prepare_server_hello(mbedtls_ssl_context *ssl) 2012 { 2013 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2014 unsigned char *server_randbytes = 2015 ssl->handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN; 2016 2017 if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, server_randbytes, 2018 MBEDTLS_SERVER_HELLO_RANDOM_LEN)) != 0) { 2019 MBEDTLS_SSL_DEBUG_RET(1, "f_rng", ret); 2020 return ret; 2021 } 2022 2023 MBEDTLS_SSL_DEBUG_BUF(3, "server hello, random bytes", server_randbytes, 2024 MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2025 2026 #if defined(MBEDTLS_HAVE_TIME) 2027 ssl->session_negotiate->start = mbedtls_time(NULL); 2028 #endif /* MBEDTLS_HAVE_TIME */ 2029 2030 return ret; 2031 } 2032 2033 /* 2034 * ssl_tls13_write_server_hello_supported_versions_ext (): 2035 * 2036 * struct { 2037 * ProtocolVersion selected_version; 2038 * } SupportedVersions; 2039 */ 2040 MBEDTLS_CHECK_RETURN_CRITICAL 2041 static int ssl_tls13_write_server_hello_supported_versions_ext( 2042 mbedtls_ssl_context *ssl, 2043 unsigned char *buf, 2044 unsigned char *end, 2045 size_t *out_len) 2046 { 2047 *out_len = 0; 2048 2049 MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, write selected version")); 2050 2051 /* Check if we have space to write the extension: 2052 * - extension_type (2 bytes) 2053 * - extension_data_length (2 bytes) 2054 * - selected_version (2 bytes) 2055 */ 2056 MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6); 2057 2058 MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, buf, 0); 2059 2060 MBEDTLS_PUT_UINT16_BE(2, buf, 2); 2061 2062 mbedtls_ssl_write_version(buf + 4, 2063 ssl->conf->transport, 2064 ssl->tls_version); 2065 2066 MBEDTLS_SSL_DEBUG_MSG(3, ("supported version: [%04x]", 2067 ssl->tls_version)); 2068 2069 *out_len = 6; 2070 2071 mbedtls_ssl_tls13_set_hs_sent_ext_mask( 2072 ssl, MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS); 2073 2074 return 0; 2075 } 2076 2077 2078 2079 /* Generate and export a single key share. For hybrid KEMs, this can 2080 * be called multiple times with the different components of the hybrid. */ 2081 MBEDTLS_CHECK_RETURN_CRITICAL 2082 static int ssl_tls13_generate_and_write_key_share(mbedtls_ssl_context *ssl, 2083 uint16_t named_group, 2084 unsigned char *buf, 2085 unsigned char *end, 2086 size_t *out_len) 2087 { 2088 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2089 2090 *out_len = 0; 2091 2092 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) 2093 if (mbedtls_ssl_tls13_named_group_is_ecdhe(named_group) || 2094 mbedtls_ssl_tls13_named_group_is_ffdh(named_group)) { 2095 ret = mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange( 2096 ssl, named_group, buf, end, out_len); 2097 if (ret != 0) { 2098 MBEDTLS_SSL_DEBUG_RET( 2099 1, "mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange", 2100 ret); 2101 return ret; 2102 } 2103 } else 2104 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ 2105 if (0 /* Other kinds of KEMs */) { 2106 } else { 2107 ((void) ssl); 2108 ((void) named_group); 2109 ((void) buf); 2110 ((void) end); 2111 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; 2112 } 2113 2114 return ret; 2115 } 2116 2117 /* 2118 * ssl_tls13_write_key_share_ext 2119 * 2120 * Structure of key_share extension in ServerHello: 2121 * 2122 * struct { 2123 * NamedGroup group; 2124 * opaque key_exchange<1..2^16-1>; 2125 * } KeyShareEntry; 2126 * struct { 2127 * KeyShareEntry server_share; 2128 * } KeyShareServerHello; 2129 */ 2130 MBEDTLS_CHECK_RETURN_CRITICAL 2131 static int ssl_tls13_write_key_share_ext(mbedtls_ssl_context *ssl, 2132 unsigned char *buf, 2133 unsigned char *end, 2134 size_t *out_len) 2135 { 2136 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2137 unsigned char *p = buf; 2138 uint16_t group = ssl->handshake->offered_group_id; 2139 unsigned char *server_share = buf + 4; 2140 size_t key_exchange_length; 2141 2142 *out_len = 0; 2143 2144 MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, adding key share extension")); 2145 2146 MBEDTLS_SSL_DEBUG_MSG(2, ("server hello, write selected_group: %s (%04x)", 2147 mbedtls_ssl_named_group_to_str(group), 2148 group)); 2149 2150 /* Check if we have space for header and length fields: 2151 * - extension_type (2 bytes) 2152 * - extension_data_length (2 bytes) 2153 * - group (2 bytes) 2154 * - key_exchange_length (2 bytes) 2155 */ 2156 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 8); 2157 MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, p, 0); 2158 MBEDTLS_PUT_UINT16_BE(group, server_share, 0); 2159 p += 8; 2160 2161 /* When we introduce PQC-ECDHE hybrids, we'll want to call this 2162 * function multiple times. */ 2163 ret = ssl_tls13_generate_and_write_key_share( 2164 ssl, group, server_share + 4, end, &key_exchange_length); 2165 if (ret != 0) { 2166 return ret; 2167 } 2168 p += key_exchange_length; 2169 2170 MBEDTLS_PUT_UINT16_BE(key_exchange_length, server_share + 2, 0); 2171 2172 MBEDTLS_PUT_UINT16_BE(p - server_share, buf, 2); 2173 2174 *out_len = p - buf; 2175 2176 mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); 2177 2178 return 0; 2179 } 2180 2181 MBEDTLS_CHECK_RETURN_CRITICAL 2182 static int ssl_tls13_write_hrr_key_share_ext(mbedtls_ssl_context *ssl, 2183 unsigned char *buf, 2184 unsigned char *end, 2185 size_t *out_len) 2186 { 2187 uint16_t selected_group = ssl->handshake->hrr_selected_group; 2188 /* key_share Extension 2189 * 2190 * struct { 2191 * select (Handshake.msg_type) { 2192 * ... 2193 * case hello_retry_request: 2194 * NamedGroup selected_group; 2195 * ... 2196 * }; 2197 * } KeyShare; 2198 */ 2199 2200 *out_len = 0; 2201 2202 /* 2203 * For a pure PSK key exchange, there is no group to agree upon. The purpose 2204 * of the HRR is then to transmit a cookie to force the client to demonstrate 2205 * reachability at their apparent network address (primarily useful for DTLS). 2206 */ 2207 if (!mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) { 2208 return 0; 2209 } 2210 2211 /* We should only send the key_share extension if the client's initial 2212 * key share was not acceptable. */ 2213 if (ssl->handshake->offered_group_id != 0) { 2214 MBEDTLS_SSL_DEBUG_MSG(4, ("Skip key_share extension in HRR")); 2215 return 0; 2216 } 2217 2218 if (selected_group == 0) { 2219 MBEDTLS_SSL_DEBUG_MSG(1, ("no matching named group found")); 2220 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 2221 } 2222 2223 /* Check if we have enough space: 2224 * - extension_type (2 bytes) 2225 * - extension_data_length (2 bytes) 2226 * - selected_group (2 bytes) 2227 */ 2228 MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6); 2229 2230 MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, buf, 0); 2231 MBEDTLS_PUT_UINT16_BE(2, buf, 2); 2232 MBEDTLS_PUT_UINT16_BE(selected_group, buf, 4); 2233 2234 MBEDTLS_SSL_DEBUG_MSG(3, 2235 ("HRR selected_group: %s (%x)", 2236 mbedtls_ssl_named_group_to_str(selected_group), 2237 selected_group)); 2238 2239 *out_len = 6; 2240 2241 mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); 2242 2243 return 0; 2244 } 2245 2246 /* 2247 * Structure of ServerHello message: 2248 * 2249 * struct { 2250 * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 2251 * Random random; 2252 * opaque legacy_session_id_echo<0..32>; 2253 * CipherSuite cipher_suite; 2254 * uint8 legacy_compression_method = 0; 2255 * Extension extensions<6..2^16-1>; 2256 * } ServerHello; 2257 */ 2258 MBEDTLS_CHECK_RETURN_CRITICAL 2259 static int ssl_tls13_write_server_hello_body(mbedtls_ssl_context *ssl, 2260 unsigned char *buf, 2261 unsigned char *end, 2262 size_t *out_len, 2263 int is_hrr) 2264 { 2265 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2266 unsigned char *p = buf; 2267 unsigned char *p_extensions_len; 2268 size_t output_len; 2269 2270 *out_len = 0; 2271 ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; 2272 2273 /* ... 2274 * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 2275 * ... 2276 * with ProtocolVersion defined as: 2277 * uint16 ProtocolVersion; 2278 */ 2279 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 2280 MBEDTLS_PUT_UINT16_BE(0x0303, p, 0); 2281 p += 2; 2282 2283 /* ... 2284 * Random random; 2285 * ... 2286 * with Random defined as: 2287 * opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN]; 2288 */ 2289 MBEDTLS_SSL_CHK_BUF_PTR(p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2290 if (is_hrr) { 2291 memcpy(p, mbedtls_ssl_tls13_hello_retry_request_magic, 2292 MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2293 } else { 2294 memcpy(p, &ssl->handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN], 2295 MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2296 } 2297 MBEDTLS_SSL_DEBUG_BUF(3, "server hello, random bytes", 2298 p, MBEDTLS_SERVER_HELLO_RANDOM_LEN); 2299 p += MBEDTLS_SERVER_HELLO_RANDOM_LEN; 2300 2301 /* ... 2302 * opaque legacy_session_id_echo<0..32>; 2303 * ... 2304 */ 2305 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1 + ssl->session_negotiate->id_len); 2306 *p++ = (unsigned char) ssl->session_negotiate->id_len; 2307 if (ssl->session_negotiate->id_len > 0) { 2308 memcpy(p, &ssl->session_negotiate->id[0], 2309 ssl->session_negotiate->id_len); 2310 p += ssl->session_negotiate->id_len; 2311 2312 MBEDTLS_SSL_DEBUG_BUF(3, "session id", ssl->session_negotiate->id, 2313 ssl->session_negotiate->id_len); 2314 } 2315 2316 /* ... 2317 * CipherSuite cipher_suite; 2318 * ... 2319 * with CipherSuite defined as: 2320 * uint8 CipherSuite[2]; 2321 */ 2322 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 2323 MBEDTLS_PUT_UINT16_BE(ssl->session_negotiate->ciphersuite, p, 0); 2324 p += 2; 2325 MBEDTLS_SSL_DEBUG_MSG(3, 2326 ("server hello, chosen ciphersuite: %s ( id=%d )", 2327 mbedtls_ssl_get_ciphersuite_name( 2328 ssl->session_negotiate->ciphersuite), 2329 ssl->session_negotiate->ciphersuite)); 2330 2331 /* ... 2332 * uint8 legacy_compression_method = 0; 2333 * ... 2334 */ 2335 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1); 2336 *p++ = MBEDTLS_SSL_COMPRESS_NULL; 2337 2338 /* ... 2339 * Extension extensions<6..2^16-1>; 2340 * ... 2341 * struct { 2342 * ExtensionType extension_type; (2 bytes) 2343 * opaque extension_data<0..2^16-1>; 2344 * } Extension; 2345 */ 2346 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 2347 p_extensions_len = p; 2348 p += 2; 2349 2350 if ((ret = ssl_tls13_write_server_hello_supported_versions_ext( 2351 ssl, p, end, &output_len)) != 0) { 2352 MBEDTLS_SSL_DEBUG_RET( 2353 1, "ssl_tls13_write_server_hello_supported_versions_ext", ret); 2354 return ret; 2355 } 2356 p += output_len; 2357 2358 if (mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) { 2359 if (is_hrr) { 2360 ret = ssl_tls13_write_hrr_key_share_ext(ssl, p, end, &output_len); 2361 } else { 2362 ret = ssl_tls13_write_key_share_ext(ssl, p, end, &output_len); 2363 } 2364 if (ret != 0) { 2365 return ret; 2366 } 2367 p += output_len; 2368 } 2369 2370 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 2371 if (!is_hrr && mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) { 2372 ret = ssl_tls13_write_server_pre_shared_key_ext(ssl, p, end, &output_len); 2373 if (ret != 0) { 2374 MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_server_pre_shared_key_ext", 2375 ret); 2376 return ret; 2377 } 2378 p += output_len; 2379 } 2380 #endif 2381 2382 MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); 2383 2384 MBEDTLS_SSL_DEBUG_BUF(4, "server hello extensions", 2385 p_extensions_len, p - p_extensions_len); 2386 2387 *out_len = p - buf; 2388 2389 MBEDTLS_SSL_DEBUG_BUF(3, "server hello", buf, *out_len); 2390 2391 MBEDTLS_SSL_PRINT_EXTS( 2392 3, is_hrr ? MBEDTLS_SSL_TLS1_3_HS_HELLO_RETRY_REQUEST : 2393 MBEDTLS_SSL_HS_SERVER_HELLO, 2394 ssl->handshake->sent_extensions); 2395 2396 return ret; 2397 } 2398 2399 MBEDTLS_CHECK_RETURN_CRITICAL 2400 static int ssl_tls13_finalize_server_hello(mbedtls_ssl_context *ssl) 2401 { 2402 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2403 ret = mbedtls_ssl_tls13_compute_handshake_transform(ssl); 2404 if (ret != 0) { 2405 MBEDTLS_SSL_DEBUG_RET(1, 2406 "mbedtls_ssl_tls13_compute_handshake_transform", 2407 ret); 2408 return ret; 2409 } 2410 2411 return ret; 2412 } 2413 2414 MBEDTLS_CHECK_RETURN_CRITICAL 2415 static int ssl_tls13_write_server_hello(mbedtls_ssl_context *ssl) 2416 { 2417 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2418 unsigned char *buf; 2419 size_t buf_len, msg_len; 2420 2421 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write server hello")); 2422 2423 MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_server_hello(ssl)); 2424 2425 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 2426 ssl, MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len)); 2427 2428 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_server_hello_body(ssl, buf, 2429 buf + buf_len, 2430 &msg_len, 2431 0)); 2432 2433 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 2434 ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len)); 2435 2436 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( 2437 ssl, buf_len, msg_len)); 2438 2439 MBEDTLS_SSL_PROC_CHK(ssl_tls13_finalize_server_hello(ssl)); 2440 2441 #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) 2442 /* The server sends a dummy change_cipher_spec record immediately 2443 * after its first handshake message. This may either be after 2444 * a ServerHello or a HelloRetryRequest. 2445 */ 2446 mbedtls_ssl_handshake_set_state( 2447 ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO); 2448 #else 2449 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); 2450 #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ 2451 2452 cleanup: 2453 2454 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write server hello")); 2455 return ret; 2456 } 2457 2458 2459 /* 2460 * Handler for MBEDTLS_SSL_HELLO_RETRY_REQUEST 2461 */ 2462 MBEDTLS_CHECK_RETURN_CRITICAL 2463 static int ssl_tls13_prepare_hello_retry_request(mbedtls_ssl_context *ssl) 2464 { 2465 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2466 if (ssl->handshake->hello_retry_request_flag) { 2467 MBEDTLS_SSL_DEBUG_MSG(1, ("Too many HRRs")); 2468 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, 2469 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 2470 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 2471 } 2472 2473 /* 2474 * Create stateless transcript hash for HRR 2475 */ 2476 MBEDTLS_SSL_DEBUG_MSG(4, ("Reset transcript for HRR")); 2477 ret = mbedtls_ssl_reset_transcript_for_hrr(ssl); 2478 if (ret != 0) { 2479 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_reset_transcript_for_hrr", ret); 2480 return ret; 2481 } 2482 mbedtls_ssl_session_reset_msg_layer(ssl, 0); 2483 2484 return 0; 2485 } 2486 2487 MBEDTLS_CHECK_RETURN_CRITICAL 2488 static int ssl_tls13_write_hello_retry_request(mbedtls_ssl_context *ssl) 2489 { 2490 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2491 unsigned char *buf; 2492 size_t buf_len, msg_len; 2493 2494 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write hello retry request")); 2495 2496 MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_hello_retry_request(ssl)); 2497 2498 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 2499 ssl, MBEDTLS_SSL_HS_SERVER_HELLO, 2500 &buf, &buf_len)); 2501 2502 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_server_hello_body(ssl, buf, 2503 buf + buf_len, 2504 &msg_len, 2505 1)); 2506 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 2507 ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len)); 2508 2509 2510 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(ssl, buf_len, 2511 msg_len)); 2512 2513 ssl->handshake->hello_retry_request_flag = 1; 2514 2515 #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) 2516 /* The server sends a dummy change_cipher_spec record immediately 2517 * after its first handshake message. This may either be after 2518 * a ServerHello or a HelloRetryRequest. 2519 */ 2520 mbedtls_ssl_handshake_set_state( 2521 ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST); 2522 #else 2523 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); 2524 #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ 2525 2526 cleanup: 2527 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write hello retry request")); 2528 return ret; 2529 } 2530 2531 /* 2532 * Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS 2533 */ 2534 2535 /* 2536 * struct { 2537 * Extension extensions<0..2 ^ 16 - 1>; 2538 * } EncryptedExtensions; 2539 * 2540 */ 2541 MBEDTLS_CHECK_RETURN_CRITICAL 2542 static int ssl_tls13_write_encrypted_extensions_body(mbedtls_ssl_context *ssl, 2543 unsigned char *buf, 2544 unsigned char *end, 2545 size_t *out_len) 2546 { 2547 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2548 unsigned char *p = buf; 2549 size_t extensions_len = 0; 2550 unsigned char *p_extensions_len; 2551 size_t output_len; 2552 2553 *out_len = 0; 2554 2555 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 2556 p_extensions_len = p; 2557 p += 2; 2558 2559 ((void) ssl); 2560 ((void) ret); 2561 ((void) output_len); 2562 2563 #if defined(MBEDTLS_SSL_ALPN) 2564 ret = mbedtls_ssl_write_alpn_ext(ssl, p, end, &output_len); 2565 if (ret != 0) { 2566 return ret; 2567 } 2568 p += output_len; 2569 #endif /* MBEDTLS_SSL_ALPN */ 2570 2571 #if defined(MBEDTLS_SSL_EARLY_DATA) 2572 if (ssl->handshake->early_data_accepted) { 2573 ret = mbedtls_ssl_tls13_write_early_data_ext( 2574 ssl, 0, p, end, &output_len); 2575 if (ret != 0) { 2576 return ret; 2577 } 2578 p += output_len; 2579 } 2580 #endif /* MBEDTLS_SSL_EARLY_DATA */ 2581 2582 #if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) 2583 if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(RECORD_SIZE_LIMIT)) { 2584 ret = mbedtls_ssl_tls13_write_record_size_limit_ext( 2585 ssl, p, end, &output_len); 2586 if (ret != 0) { 2587 return ret; 2588 } 2589 p += output_len; 2590 } 2591 #endif 2592 2593 extensions_len = (p - p_extensions_len) - 2; 2594 MBEDTLS_PUT_UINT16_BE(extensions_len, p_extensions_len, 0); 2595 2596 *out_len = p - buf; 2597 2598 MBEDTLS_SSL_DEBUG_BUF(4, "encrypted extensions", buf, *out_len); 2599 2600 MBEDTLS_SSL_PRINT_EXTS( 2601 3, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, ssl->handshake->sent_extensions); 2602 2603 return 0; 2604 } 2605 2606 MBEDTLS_CHECK_RETURN_CRITICAL 2607 static int ssl_tls13_write_encrypted_extensions(mbedtls_ssl_context *ssl) 2608 { 2609 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2610 unsigned char *buf; 2611 size_t buf_len, msg_len; 2612 2613 mbedtls_ssl_set_outbound_transform(ssl, 2614 ssl->handshake->transform_handshake); 2615 MBEDTLS_SSL_DEBUG_MSG( 2616 3, ("switching to handshake transform for outbound data")); 2617 2618 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write encrypted extensions")); 2619 2620 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 2621 ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, 2622 &buf, &buf_len)); 2623 2624 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_encrypted_extensions_body( 2625 ssl, buf, buf + buf_len, &msg_len)); 2626 2627 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 2628 ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, 2629 buf, msg_len)); 2630 2631 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( 2632 ssl, buf_len, msg_len)); 2633 2634 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 2635 if (mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) { 2636 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); 2637 } else { 2638 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CERTIFICATE_REQUEST); 2639 } 2640 #else 2641 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); 2642 #endif 2643 2644 cleanup: 2645 2646 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write encrypted extensions")); 2647 return ret; 2648 } 2649 2650 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 2651 #define SSL_CERTIFICATE_REQUEST_SEND_REQUEST 0 2652 #define SSL_CERTIFICATE_REQUEST_SKIP 1 2653 /* Coordination: 2654 * Check whether a CertificateRequest message should be written. 2655 * Returns a negative code on failure, or 2656 * - SSL_CERTIFICATE_REQUEST_SEND_REQUEST 2657 * - SSL_CERTIFICATE_REQUEST_SKIP 2658 * indicating if the writing of the CertificateRequest 2659 * should be skipped or not. 2660 */ 2661 MBEDTLS_CHECK_RETURN_CRITICAL 2662 static int ssl_tls13_certificate_request_coordinate(mbedtls_ssl_context *ssl) 2663 { 2664 int authmode; 2665 2666 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) 2667 if (ssl->handshake->sni_authmode != MBEDTLS_SSL_VERIFY_UNSET) { 2668 authmode = ssl->handshake->sni_authmode; 2669 } else 2670 #endif 2671 authmode = ssl->conf->authmode; 2672 2673 if (authmode == MBEDTLS_SSL_VERIFY_NONE) { 2674 ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_SKIP_VERIFY; 2675 return SSL_CERTIFICATE_REQUEST_SKIP; 2676 } 2677 2678 ssl->handshake->certificate_request_sent = 1; 2679 2680 return SSL_CERTIFICATE_REQUEST_SEND_REQUEST; 2681 } 2682 2683 /* 2684 * struct { 2685 * opaque certificate_request_context<0..2^8-1>; 2686 * Extension extensions<2..2^16-1>; 2687 * } CertificateRequest; 2688 * 2689 */ 2690 MBEDTLS_CHECK_RETURN_CRITICAL 2691 static int ssl_tls13_write_certificate_request_body(mbedtls_ssl_context *ssl, 2692 unsigned char *buf, 2693 const unsigned char *end, 2694 size_t *out_len) 2695 { 2696 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2697 unsigned char *p = buf; 2698 size_t output_len = 0; 2699 unsigned char *p_extensions_len; 2700 2701 *out_len = 0; 2702 2703 /* Check if we have enough space: 2704 * - certificate_request_context (1 byte) 2705 * - extensions length (2 bytes) 2706 */ 2707 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 3); 2708 2709 /* 2710 * Write certificate_request_context 2711 */ 2712 /* 2713 * We use a zero length context for the normal handshake 2714 * messages. For post-authentication handshake messages 2715 * this request context would be set to a non-zero value. 2716 */ 2717 *p++ = 0x0; 2718 2719 /* 2720 * Write extensions 2721 */ 2722 /* The extensions must contain the signature_algorithms. */ 2723 p_extensions_len = p; 2724 p += 2; 2725 ret = mbedtls_ssl_write_sig_alg_ext(ssl, p, end, &output_len); 2726 if (ret != 0) { 2727 return ret; 2728 } 2729 2730 p += output_len; 2731 MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); 2732 2733 *out_len = p - buf; 2734 2735 MBEDTLS_SSL_PRINT_EXTS( 2736 3, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, ssl->handshake->sent_extensions); 2737 2738 return 0; 2739 } 2740 2741 MBEDTLS_CHECK_RETURN_CRITICAL 2742 static int ssl_tls13_write_certificate_request(mbedtls_ssl_context *ssl) 2743 { 2744 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2745 2746 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write certificate request")); 2747 2748 MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_certificate_request_coordinate(ssl)); 2749 2750 if (ret == SSL_CERTIFICATE_REQUEST_SEND_REQUEST) { 2751 unsigned char *buf; 2752 size_t buf_len, msg_len; 2753 2754 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 2755 ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, 2756 &buf, &buf_len)); 2757 2758 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_certificate_request_body( 2759 ssl, buf, buf + buf_len, &msg_len)); 2760 2761 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 2762 ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, 2763 buf, msg_len)); 2764 2765 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( 2766 ssl, buf_len, msg_len)); 2767 } else if (ret == SSL_CERTIFICATE_REQUEST_SKIP) { 2768 MBEDTLS_SSL_DEBUG_MSG(2, ("<= skip write certificate request")); 2769 ret = 0; 2770 } else { 2771 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); 2772 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; 2773 goto cleanup; 2774 } 2775 2776 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_CERTIFICATE); 2777 cleanup: 2778 2779 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write certificate request")); 2780 return ret; 2781 } 2782 2783 /* 2784 * Handler for MBEDTLS_SSL_SERVER_CERTIFICATE 2785 */ 2786 MBEDTLS_CHECK_RETURN_CRITICAL 2787 static int ssl_tls13_write_server_certificate(mbedtls_ssl_context *ssl) 2788 { 2789 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2790 2791 #if defined(MBEDTLS_X509_CRT_PARSE_C) 2792 if ((ssl_tls13_pick_key_cert(ssl) != 0) || 2793 mbedtls_ssl_own_cert(ssl) == NULL) { 2794 MBEDTLS_SSL_DEBUG_MSG(2, ("No certificate available.")); 2795 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, 2796 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 2797 return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; 2798 } 2799 #endif /* MBEDTLS_X509_CRT_PARSE_C */ 2800 2801 ret = mbedtls_ssl_tls13_write_certificate(ssl); 2802 if (ret != 0) { 2803 return ret; 2804 } 2805 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CERTIFICATE_VERIFY); 2806 return 0; 2807 } 2808 2809 /* 2810 * Handler for MBEDTLS_SSL_CERTIFICATE_VERIFY 2811 */ 2812 MBEDTLS_CHECK_RETURN_CRITICAL 2813 static int ssl_tls13_write_certificate_verify(mbedtls_ssl_context *ssl) 2814 { 2815 int ret = mbedtls_ssl_tls13_write_certificate_verify(ssl); 2816 if (ret != 0) { 2817 return ret; 2818 } 2819 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); 2820 return 0; 2821 } 2822 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 2823 2824 /* 2825 * RFC 8446 section A.2 2826 * 2827 * | Send ServerHello 2828 * | K_send = handshake 2829 * | Send EncryptedExtensions 2830 * | [Send CertificateRequest] 2831 * Can send | [Send Certificate + CertificateVerify] 2832 * app data | Send Finished 2833 * after --> | K_send = application 2834 * here +--------+--------+ 2835 * No 0-RTT | | 0-RTT 2836 * | | 2837 * K_recv = handshake | | K_recv = early data 2838 * [Skip decrypt errors] | +------> WAIT_EOED -+ 2839 * | | Recv | | Recv EndOfEarlyData 2840 * | | early data | | K_recv = handshake 2841 * | +------------+ | 2842 * | | 2843 * +> WAIT_FLIGHT2 <--------+ 2844 * | 2845 * +--------+--------+ 2846 * No auth | | Client auth 2847 * | | 2848 * | v 2849 * | WAIT_CERT 2850 * | Recv | | Recv Certificate 2851 * | empty | v 2852 * | Certificate | WAIT_CV 2853 * | | | Recv 2854 * | v | CertificateVerify 2855 * +-> WAIT_FINISHED <---+ 2856 * | Recv Finished 2857 * 2858 * 2859 * The following function handles the state changes after WAIT_FLIGHT2 in the 2860 * above diagram. We are not going to receive early data related messages 2861 * anymore, prepare to receive the first handshake message of the client 2862 * second flight. 2863 */ 2864 static void ssl_tls13_prepare_for_handshake_second_flight( 2865 mbedtls_ssl_context *ssl) 2866 { 2867 if (ssl->handshake->certificate_request_sent) { 2868 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE); 2869 } else { 2870 MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate")); 2871 MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate verify")); 2872 2873 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_FINISHED); 2874 } 2875 } 2876 2877 /* 2878 * Handler for MBEDTLS_SSL_SERVER_FINISHED 2879 */ 2880 MBEDTLS_CHECK_RETURN_CRITICAL 2881 static int ssl_tls13_write_server_finished(mbedtls_ssl_context *ssl) 2882 { 2883 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2884 2885 ret = mbedtls_ssl_tls13_write_finished_message(ssl); 2886 if (ret != 0) { 2887 return ret; 2888 } 2889 2890 ret = mbedtls_ssl_tls13_compute_application_transform(ssl); 2891 if (ret != 0) { 2892 MBEDTLS_SSL_PEND_FATAL_ALERT( 2893 MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, 2894 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); 2895 return ret; 2896 } 2897 2898 #if defined(MBEDTLS_SSL_EARLY_DATA) 2899 if (ssl->handshake->early_data_accepted) { 2900 /* See RFC 8446 section A.2 for more information */ 2901 MBEDTLS_SSL_DEBUG_MSG( 2902 1, ("Switch to early keys for inbound traffic. " 2903 "( K_recv = early data )")); 2904 mbedtls_ssl_set_inbound_transform( 2905 ssl, ssl->handshake->transform_earlydata); 2906 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_END_OF_EARLY_DATA); 2907 return 0; 2908 } 2909 #endif /* MBEDTLS_SSL_EARLY_DATA */ 2910 MBEDTLS_SSL_DEBUG_MSG( 2911 1, ("Switch to handshake keys for inbound traffic " 2912 "( K_recv = handshake )")); 2913 mbedtls_ssl_set_inbound_transform(ssl, ssl->handshake->transform_handshake); 2914 2915 ssl_tls13_prepare_for_handshake_second_flight(ssl); 2916 2917 return 0; 2918 } 2919 2920 #if defined(MBEDTLS_SSL_EARLY_DATA) 2921 /* 2922 * Handler for MBEDTLS_SSL_END_OF_EARLY_DATA 2923 */ 2924 #define SSL_GOT_END_OF_EARLY_DATA 0 2925 #define SSL_GOT_EARLY_DATA 1 2926 /* Coordination: 2927 * Deals with the ambiguity of not knowing if the next message is an 2928 * EndOfEarlyData message or an application message containing early data. 2929 * Returns a negative code on failure, or 2930 * - SSL_GOT_END_OF_EARLY_DATA 2931 * - SSL_GOT_EARLY_DATA 2932 * indicating which message is received. 2933 */ 2934 MBEDTLS_CHECK_RETURN_CRITICAL 2935 static int ssl_tls13_end_of_early_data_coordinate(mbedtls_ssl_context *ssl) 2936 { 2937 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 2938 2939 if ((ret = mbedtls_ssl_read_record(ssl, 0)) != 0) { 2940 MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); 2941 return ret; 2942 } 2943 ssl->keep_current_message = 1; 2944 2945 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && 2946 ssl->in_msg[0] == MBEDTLS_SSL_HS_END_OF_EARLY_DATA) { 2947 MBEDTLS_SSL_DEBUG_MSG(3, ("Received an end_of_early_data message.")); 2948 return SSL_GOT_END_OF_EARLY_DATA; 2949 } 2950 2951 if (ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA) { 2952 if (ssl->in_offt == NULL) { 2953 MBEDTLS_SSL_DEBUG_MSG(3, ("Received early data")); 2954 /* Set the reading pointer */ 2955 ssl->in_offt = ssl->in_msg; 2956 ret = mbedtls_ssl_tls13_check_early_data_len(ssl, ssl->in_msglen); 2957 if (ret != 0) { 2958 return ret; 2959 } 2960 } 2961 return SSL_GOT_EARLY_DATA; 2962 } 2963 2964 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE, 2965 MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE); 2966 return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; 2967 } 2968 2969 MBEDTLS_CHECK_RETURN_CRITICAL 2970 static int ssl_tls13_parse_end_of_early_data(mbedtls_ssl_context *ssl, 2971 const unsigned char *buf, 2972 const unsigned char *end) 2973 { 2974 /* RFC 8446 section 4.5 2975 * 2976 * struct {} EndOfEarlyData; 2977 */ 2978 if (buf != end) { 2979 MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, 2980 MBEDTLS_ERR_SSL_DECODE_ERROR); 2981 return MBEDTLS_ERR_SSL_DECODE_ERROR; 2982 } 2983 return 0; 2984 } 2985 2986 /* 2987 * RFC 8446 section A.2 2988 * 2989 * | Send ServerHello 2990 * | K_send = handshake 2991 * | Send EncryptedExtensions 2992 * | [Send CertificateRequest] 2993 * Can send | [Send Certificate + CertificateVerify] 2994 * app data | Send Finished 2995 * after --> | K_send = application 2996 * here +--------+--------+ 2997 * No 0-RTT | | 0-RTT 2998 * | | 2999 * K_recv = handshake | | K_recv = early data 3000 * [Skip decrypt errors] | +------> WAIT_EOED -+ 3001 * | | Recv | | Recv EndOfEarlyData 3002 * | | early data | | K_recv = handshake 3003 * | +------------+ | 3004 * | | 3005 * +> WAIT_FLIGHT2 <--------+ 3006 * | 3007 * +--------+--------+ 3008 * No auth | | Client auth 3009 * | | 3010 * | v 3011 * | WAIT_CERT 3012 * | Recv | | Recv Certificate 3013 * | empty | v 3014 * | Certificate | WAIT_CV 3015 * | | | Recv 3016 * | v | CertificateVerify 3017 * +-> WAIT_FINISHED <---+ 3018 * | Recv Finished 3019 * 3020 * The function handles actions and state changes from 0-RTT to WAIT_FLIGHT2 in 3021 * the above diagram. 3022 */ 3023 MBEDTLS_CHECK_RETURN_CRITICAL 3024 static int ssl_tls13_process_end_of_early_data(mbedtls_ssl_context *ssl) 3025 { 3026 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3027 3028 MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_tls13_process_end_of_early_data")); 3029 3030 MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_end_of_early_data_coordinate(ssl)); 3031 3032 if (ret == SSL_GOT_END_OF_EARLY_DATA) { 3033 unsigned char *buf; 3034 size_t buf_len; 3035 3036 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( 3037 ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, 3038 &buf, &buf_len)); 3039 3040 MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_end_of_early_data( 3041 ssl, buf, buf + buf_len)); 3042 3043 MBEDTLS_SSL_DEBUG_MSG( 3044 1, ("Switch to handshake keys for inbound traffic" 3045 "( K_recv = handshake )")); 3046 mbedtls_ssl_set_inbound_transform( 3047 ssl, ssl->handshake->transform_handshake); 3048 3049 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( 3050 ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, 3051 buf, buf_len)); 3052 3053 ssl_tls13_prepare_for_handshake_second_flight(ssl); 3054 3055 } else if (ret == SSL_GOT_EARLY_DATA) { 3056 ret = MBEDTLS_ERR_SSL_RECEIVED_EARLY_DATA; 3057 goto cleanup; 3058 } else { 3059 MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); 3060 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; 3061 goto cleanup; 3062 } 3063 3064 cleanup: 3065 MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_tls13_process_end_of_early_data")); 3066 return ret; 3067 } 3068 #endif /* MBEDTLS_SSL_EARLY_DATA */ 3069 3070 /* 3071 * Handler for MBEDTLS_SSL_CLIENT_FINISHED 3072 */ 3073 MBEDTLS_CHECK_RETURN_CRITICAL 3074 static int ssl_tls13_process_client_finished(mbedtls_ssl_context *ssl) 3075 { 3076 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3077 3078 ret = mbedtls_ssl_tls13_process_finished_message(ssl); 3079 if (ret != 0) { 3080 return ret; 3081 } 3082 3083 ret = mbedtls_ssl_tls13_compute_resumption_master_secret(ssl); 3084 if (ret != 0) { 3085 MBEDTLS_SSL_DEBUG_RET( 3086 1, "mbedtls_ssl_tls13_compute_resumption_master_secret", ret); 3087 } 3088 3089 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_WRAPUP); 3090 return 0; 3091 } 3092 3093 /* 3094 * Handler for MBEDTLS_SSL_HANDSHAKE_WRAPUP 3095 */ 3096 MBEDTLS_CHECK_RETURN_CRITICAL 3097 static int ssl_tls13_handshake_wrapup(mbedtls_ssl_context *ssl) 3098 { 3099 MBEDTLS_SSL_DEBUG_MSG(2, ("handshake: done")); 3100 3101 mbedtls_ssl_tls13_handshake_wrapup(ssl); 3102 3103 #if defined(MBEDTLS_SSL_SESSION_TICKETS) && \ 3104 defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 3105 /* TODO: Remove the check of SOME_PSK_ENABLED since SESSION_TICKETS requires 3106 * SOME_PSK_ENABLED to be enabled. Here is just to make CI happy. It is 3107 * expected to be resolved with issue#6395. 3108 */ 3109 /* Sent NewSessionTicket message only when client supports PSK */ 3110 if (mbedtls_ssl_tls13_is_some_psk_supported(ssl)) { 3111 mbedtls_ssl_handshake_set_state( 3112 ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); 3113 } else 3114 #endif 3115 { 3116 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); 3117 } 3118 return 0; 3119 } 3120 3121 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 3122 /* 3123 * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET 3124 */ 3125 #define SSL_NEW_SESSION_TICKET_SKIP 0 3126 #define SSL_NEW_SESSION_TICKET_WRITE 1 3127 MBEDTLS_CHECK_RETURN_CRITICAL 3128 static int ssl_tls13_write_new_session_ticket_coordinate(mbedtls_ssl_context *ssl) 3129 { 3130 /* Check whether the use of session tickets is enabled */ 3131 if (ssl->conf->f_ticket_write == NULL) { 3132 MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: disabled," 3133 " callback is not set")); 3134 return SSL_NEW_SESSION_TICKET_SKIP; 3135 } 3136 if (ssl->conf->new_session_tickets_count == 0) { 3137 MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: disabled," 3138 " configured count is zero")); 3139 return SSL_NEW_SESSION_TICKET_SKIP; 3140 } 3141 3142 if (ssl->handshake->new_session_tickets_count == 0) { 3143 MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: all tickets have " 3144 "been sent.")); 3145 return SSL_NEW_SESSION_TICKET_SKIP; 3146 } 3147 3148 return SSL_NEW_SESSION_TICKET_WRITE; 3149 } 3150 3151 MBEDTLS_CHECK_RETURN_CRITICAL 3152 static int ssl_tls13_prepare_new_session_ticket(mbedtls_ssl_context *ssl, 3153 unsigned char *ticket_nonce, 3154 size_t ticket_nonce_size) 3155 { 3156 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3157 mbedtls_ssl_session *session = ssl->session; 3158 mbedtls_ssl_ciphersuite_t *ciphersuite_info; 3159 psa_algorithm_t psa_hash_alg; 3160 int hash_length; 3161 3162 MBEDTLS_SSL_DEBUG_MSG(2, ("=> prepare NewSessionTicket msg")); 3163 3164 /* Set ticket_flags depends on the advertised psk key exchange mode */ 3165 mbedtls_ssl_tls13_session_clear_ticket_flags( 3166 session, MBEDTLS_SSL_TLS1_3_TICKET_FLAGS_MASK); 3167 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) 3168 mbedtls_ssl_tls13_session_set_ticket_flags( 3169 session, ssl->handshake->tls13_kex_modes); 3170 #endif 3171 3172 #if defined(MBEDTLS_SSL_EARLY_DATA) 3173 if (ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_ENABLED && 3174 ssl->conf->max_early_data_size > 0) { 3175 mbedtls_ssl_tls13_session_set_ticket_flags( 3176 session, MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA); 3177 session->max_early_data_size = ssl->conf->max_early_data_size; 3178 } 3179 #endif /* MBEDTLS_SSL_EARLY_DATA */ 3180 3181 MBEDTLS_SSL_PRINT_TICKET_FLAGS(4, session->ticket_flags); 3182 3183 #if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN) 3184 if (session->ticket_alpn == NULL) { 3185 ret = mbedtls_ssl_session_set_ticket_alpn(session, ssl->alpn_chosen); 3186 if (ret != 0) { 3187 return ret; 3188 } 3189 } 3190 #endif 3191 3192 /* Generate ticket_age_add */ 3193 if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, 3194 (unsigned char *) &session->ticket_age_add, 3195 sizeof(session->ticket_age_add)) != 0)) { 3196 MBEDTLS_SSL_DEBUG_RET(1, "generate_ticket_age_add", ret); 3197 return ret; 3198 } 3199 MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", 3200 (unsigned int) session->ticket_age_add)); 3201 3202 /* Generate ticket_nonce */ 3203 ret = ssl->conf->f_rng(ssl->conf->p_rng, ticket_nonce, ticket_nonce_size); 3204 if (ret != 0) { 3205 MBEDTLS_SSL_DEBUG_RET(1, "generate_ticket_nonce", ret); 3206 return ret; 3207 } 3208 MBEDTLS_SSL_DEBUG_BUF(3, "ticket_nonce:", 3209 ticket_nonce, ticket_nonce_size); 3210 3211 ciphersuite_info = 3212 (mbedtls_ssl_ciphersuite_t *) ssl->handshake->ciphersuite_info; 3213 psa_hash_alg = mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) ciphersuite_info->mac); 3214 hash_length = PSA_HASH_LENGTH(psa_hash_alg); 3215 if (hash_length == -1 || 3216 (size_t) hash_length > sizeof(session->resumption_key)) { 3217 return MBEDTLS_ERR_SSL_INTERNAL_ERROR; 3218 } 3219 3220 /* In this code the psk key length equals the length of the hash */ 3221 session->resumption_key_len = hash_length; 3222 session->ciphersuite = ciphersuite_info->id; 3223 3224 /* Compute resumption key 3225 * 3226 * HKDF-Expand-Label( resumption_master_secret, 3227 * "resumption", ticket_nonce, Hash.length ) 3228 */ 3229 ret = mbedtls_ssl_tls13_hkdf_expand_label( 3230 psa_hash_alg, 3231 session->app_secrets.resumption_master_secret, 3232 hash_length, 3233 MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN(resumption), 3234 ticket_nonce, 3235 ticket_nonce_size, 3236 session->resumption_key, 3237 hash_length); 3238 3239 if (ret != 0) { 3240 MBEDTLS_SSL_DEBUG_RET(2, 3241 "Creating the ticket-resumed PSK failed", 3242 ret); 3243 return ret; 3244 } 3245 MBEDTLS_SSL_DEBUG_BUF(3, "Ticket-resumed PSK", 3246 session->resumption_key, 3247 session->resumption_key_len); 3248 3249 MBEDTLS_SSL_DEBUG_BUF(3, "resumption_master_secret", 3250 session->app_secrets.resumption_master_secret, 3251 hash_length); 3252 3253 return 0; 3254 } 3255 3256 /* This function creates a NewSessionTicket message in the following format: 3257 * 3258 * struct { 3259 * uint32 ticket_lifetime; 3260 * uint32 ticket_age_add; 3261 * opaque ticket_nonce<0..255>; 3262 * opaque ticket<1..2^16-1>; 3263 * Extension extensions<0..2^16-2>; 3264 * } NewSessionTicket; 3265 * 3266 * The ticket inside the NewSessionTicket message is an encrypted container 3267 * carrying the necessary information so that the server is later able to 3268 * re-start the communication. 3269 * 3270 * The following fields are placed inside the ticket by the 3271 * f_ticket_write() function: 3272 * 3273 * - creation time (ticket_creation_time) 3274 * - flags (ticket_flags) 3275 * - age add (ticket_age_add) 3276 * - key (resumption_key) 3277 * - key length (resumption_key_len) 3278 * - ciphersuite (ciphersuite) 3279 * - max_early_data_size (max_early_data_size) 3280 */ 3281 MBEDTLS_CHECK_RETURN_CRITICAL 3282 static int ssl_tls13_write_new_session_ticket_body(mbedtls_ssl_context *ssl, 3283 unsigned char *buf, 3284 unsigned char *end, 3285 size_t *out_len, 3286 unsigned char *ticket_nonce, 3287 size_t ticket_nonce_size) 3288 { 3289 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3290 unsigned char *p = buf; 3291 mbedtls_ssl_session *session = ssl->session; 3292 size_t ticket_len; 3293 uint32_t ticket_lifetime; 3294 unsigned char *p_extensions_len; 3295 3296 *out_len = 0; 3297 MBEDTLS_SSL_DEBUG_MSG(2, ("=> write NewSessionTicket msg")); 3298 3299 /* 3300 * ticket_lifetime 4 bytes 3301 * ticket_age_add 4 bytes 3302 * ticket_nonce 1 + ticket_nonce_size bytes 3303 * ticket >=2 bytes 3304 */ 3305 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 4 + 4 + 1 + ticket_nonce_size + 2); 3306 3307 /* Generate ticket and ticket_lifetime */ 3308 #if defined(MBEDTLS_HAVE_TIME) 3309 session->ticket_creation_time = mbedtls_ms_time(); 3310 #endif 3311 ret = ssl->conf->f_ticket_write(ssl->conf->p_ticket, 3312 session, 3313 p + 9 + ticket_nonce_size + 2, 3314 end, 3315 &ticket_len, 3316 &ticket_lifetime); 3317 if (ret != 0) { 3318 MBEDTLS_SSL_DEBUG_RET(1, "write_ticket", ret); 3319 return ret; 3320 } 3321 3322 /* RFC 8446 section 4.6.1 3323 * 3324 * ticket_lifetime: Indicates the lifetime in seconds as a 32-bit 3325 * unsigned integer in network byte order from the time of ticket 3326 * issuance. Servers MUST NOT use any value greater than 3327 * 604800 seconds (7 days) ... 3328 */ 3329 if (ticket_lifetime > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME) { 3330 MBEDTLS_SSL_DEBUG_MSG( 3331 1, ("Ticket lifetime (%u) is greater than 7 days.", 3332 (unsigned int) ticket_lifetime)); 3333 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; 3334 } 3335 3336 MBEDTLS_PUT_UINT32_BE(ticket_lifetime, p, 0); 3337 MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_lifetime: %u", 3338 (unsigned int) ticket_lifetime)); 3339 3340 /* Write ticket_age_add */ 3341 MBEDTLS_PUT_UINT32_BE(session->ticket_age_add, p, 4); 3342 MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", 3343 (unsigned int) session->ticket_age_add)); 3344 3345 /* Write ticket_nonce */ 3346 p[8] = (unsigned char) ticket_nonce_size; 3347 if (ticket_nonce_size > 0) { 3348 memcpy(p + 9, ticket_nonce, ticket_nonce_size); 3349 } 3350 p += 9 + ticket_nonce_size; 3351 3352 /* Write ticket */ 3353 MBEDTLS_PUT_UINT16_BE(ticket_len, p, 0); 3354 p += 2; 3355 MBEDTLS_SSL_DEBUG_BUF(4, "ticket", p, ticket_len); 3356 p += ticket_len; 3357 3358 /* Ticket Extensions 3359 * 3360 * Extension extensions<0..2^16-2>; 3361 */ 3362 ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; 3363 3364 MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); 3365 p_extensions_len = p; 3366 p += 2; 3367 3368 #if defined(MBEDTLS_SSL_EARLY_DATA) 3369 if (mbedtls_ssl_tls13_session_ticket_allow_early_data(session)) { 3370 size_t output_len; 3371 3372 if ((ret = mbedtls_ssl_tls13_write_early_data_ext( 3373 ssl, 1, p, end, &output_len)) != 0) { 3374 MBEDTLS_SSL_DEBUG_RET( 3375 1, "mbedtls_ssl_tls13_write_early_data_ext", ret); 3376 return ret; 3377 } 3378 p += output_len; 3379 } else { 3380 MBEDTLS_SSL_DEBUG_MSG( 3381 4, ("early_data not allowed, " 3382 "skip early_data extension in NewSessionTicket")); 3383 } 3384 3385 #endif /* MBEDTLS_SSL_EARLY_DATA */ 3386 3387 MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); 3388 3389 *out_len = p - buf; 3390 MBEDTLS_SSL_DEBUG_BUF(4, "ticket", buf, *out_len); 3391 MBEDTLS_SSL_DEBUG_MSG(2, ("<= write new session ticket")); 3392 3393 MBEDTLS_SSL_PRINT_EXTS( 3394 3, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, ssl->handshake->sent_extensions); 3395 3396 return 0; 3397 } 3398 3399 /* 3400 * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET 3401 */ 3402 static int ssl_tls13_write_new_session_ticket(mbedtls_ssl_context *ssl) 3403 { 3404 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3405 3406 MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_write_new_session_ticket_coordinate(ssl)); 3407 3408 if (ret == SSL_NEW_SESSION_TICKET_WRITE) { 3409 unsigned char ticket_nonce[MBEDTLS_SSL_TLS1_3_TICKET_NONCE_LENGTH]; 3410 unsigned char *buf; 3411 size_t buf_len, msg_len; 3412 3413 MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_new_session_ticket( 3414 ssl, ticket_nonce, sizeof(ticket_nonce))); 3415 3416 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( 3417 ssl, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, 3418 &buf, &buf_len)); 3419 3420 MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_new_session_ticket_body( 3421 ssl, buf, buf + buf_len, &msg_len, 3422 ticket_nonce, sizeof(ticket_nonce))); 3423 3424 MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( 3425 ssl, buf_len, msg_len)); 3426 3427 /* Limit session tickets count to one when resumption connection. 3428 * 3429 * See document of mbedtls_ssl_conf_new_session_tickets. 3430 */ 3431 if (ssl->handshake->resume == 1) { 3432 ssl->handshake->new_session_tickets_count = 0; 3433 } else { 3434 ssl->handshake->new_session_tickets_count--; 3435 } 3436 3437 mbedtls_ssl_handshake_set_state( 3438 ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET_FLUSH); 3439 } else { 3440 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); 3441 } 3442 3443 cleanup: 3444 3445 return ret; 3446 } 3447 #endif /* MBEDTLS_SSL_SESSION_TICKETS */ 3448 3449 /* 3450 * TLS 1.3 State Machine -- server side 3451 */ 3452 int mbedtls_ssl_tls13_handshake_server_step(mbedtls_ssl_context *ssl) 3453 { 3454 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 3455 3456 if (ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL) { 3457 return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; 3458 } 3459 3460 MBEDTLS_SSL_DEBUG_MSG(2, ("tls13 server state: %s(%d)", 3461 mbedtls_ssl_states_str((mbedtls_ssl_states) ssl->state), 3462 ssl->state)); 3463 3464 switch (ssl->state) { 3465 /* start state */ 3466 case MBEDTLS_SSL_HELLO_REQUEST: 3467 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); 3468 ret = 0; 3469 break; 3470 3471 case MBEDTLS_SSL_CLIENT_HELLO: 3472 ret = ssl_tls13_process_client_hello(ssl); 3473 if (ret != 0) { 3474 MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_process_client_hello", ret); 3475 } 3476 break; 3477 3478 case MBEDTLS_SSL_HELLO_RETRY_REQUEST: 3479 ret = ssl_tls13_write_hello_retry_request(ssl); 3480 if (ret != 0) { 3481 MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_hello_retry_request", ret); 3482 return ret; 3483 } 3484 break; 3485 3486 case MBEDTLS_SSL_SERVER_HELLO: 3487 ret = ssl_tls13_write_server_hello(ssl); 3488 break; 3489 3490 case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS: 3491 ret = ssl_tls13_write_encrypted_extensions(ssl); 3492 if (ret != 0) { 3493 MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_encrypted_extensions", ret); 3494 return ret; 3495 } 3496 break; 3497 3498 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 3499 case MBEDTLS_SSL_CERTIFICATE_REQUEST: 3500 ret = ssl_tls13_write_certificate_request(ssl); 3501 break; 3502 3503 case MBEDTLS_SSL_SERVER_CERTIFICATE: 3504 ret = ssl_tls13_write_server_certificate(ssl); 3505 break; 3506 3507 case MBEDTLS_SSL_CERTIFICATE_VERIFY: 3508 ret = ssl_tls13_write_certificate_verify(ssl); 3509 break; 3510 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 3511 3512 /* 3513 * Injection of dummy-CCS's for middlebox compatibility 3514 */ 3515 #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) 3516 case MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST: 3517 ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); 3518 if (ret == 0) { 3519 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); 3520 } 3521 break; 3522 3523 case MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO: 3524 ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); 3525 if (ret != 0) { 3526 break; 3527 } 3528 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); 3529 break; 3530 #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ 3531 3532 case MBEDTLS_SSL_SERVER_FINISHED: 3533 ret = ssl_tls13_write_server_finished(ssl); 3534 break; 3535 3536 #if defined(MBEDTLS_SSL_EARLY_DATA) 3537 case MBEDTLS_SSL_END_OF_EARLY_DATA: 3538 ret = ssl_tls13_process_end_of_early_data(ssl); 3539 break; 3540 #endif /* MBEDTLS_SSL_EARLY_DATA */ 3541 3542 case MBEDTLS_SSL_CLIENT_FINISHED: 3543 ret = ssl_tls13_process_client_finished(ssl); 3544 break; 3545 3546 case MBEDTLS_SSL_HANDSHAKE_WRAPUP: 3547 ret = ssl_tls13_handshake_wrapup(ssl); 3548 break; 3549 3550 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) 3551 case MBEDTLS_SSL_CLIENT_CERTIFICATE: 3552 ret = mbedtls_ssl_tls13_process_certificate(ssl); 3553 if (ret == 0) { 3554 if (ssl->session_negotiate->peer_cert != NULL) { 3555 mbedtls_ssl_handshake_set_state( 3556 ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY); 3557 } else { 3558 MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate verify")); 3559 mbedtls_ssl_handshake_set_state( 3560 ssl, MBEDTLS_SSL_CLIENT_FINISHED); 3561 } 3562 } 3563 break; 3564 3565 case MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY: 3566 ret = mbedtls_ssl_tls13_process_certificate_verify(ssl); 3567 if (ret == 0) { 3568 mbedtls_ssl_handshake_set_state( 3569 ssl, MBEDTLS_SSL_CLIENT_FINISHED); 3570 } 3571 break; 3572 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ 3573 3574 #if defined(MBEDTLS_SSL_SESSION_TICKETS) 3575 case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET: 3576 ret = ssl_tls13_write_new_session_ticket(ssl); 3577 if (ret != 0) { 3578 MBEDTLS_SSL_DEBUG_RET(1, 3579 "ssl_tls13_write_new_session_ticket ", 3580 ret); 3581 } 3582 break; 3583 case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET_FLUSH: 3584 /* This state is necessary to do the flush of the New Session 3585 * Ticket message written in MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET 3586 * as part of ssl_prepare_handshake_step. 3587 */ 3588 ret = 0; 3589 3590 if (ssl->handshake->new_session_tickets_count == 0) { 3591 mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); 3592 } else { 3593 mbedtls_ssl_handshake_set_state( 3594 ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); 3595 } 3596 break; 3597 3598 #endif /* MBEDTLS_SSL_SESSION_TICKETS */ 3599 3600 default: 3601 MBEDTLS_SSL_DEBUG_MSG(1, ("invalid state %d", ssl->state)); 3602 return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; 3603 } 3604 3605 return ret; 3606 } 3607 3608 #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_TLS1_3 */ 3609