/* * TLS 1.3 server-side functions * * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */ #include "common.h" #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3) #include "debug_internal.h" #include "mbedtls/error.h" #include "mbedtls/platform.h" #include "mbedtls/constant_time.h" #include "mbedtls/oid.h" #include "mbedtls/psa_util.h" #include "ssl_misc.h" #include "ssl_tls13_keys.h" #include "ssl_debug_helpers.h" static const mbedtls_ssl_ciphersuite_t *ssl_tls13_validate_peer_ciphersuite( mbedtls_ssl_context *ssl, unsigned int cipher_suite) { const mbedtls_ssl_ciphersuite_t *ciphersuite_info; if (!mbedtls_ssl_tls13_cipher_suite_is_offered(ssl, cipher_suite)) { return NULL; } ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(cipher_suite); if ((mbedtls_ssl_validate_ciphersuite(ssl, ciphersuite_info, ssl->tls_version, ssl->tls_version) != 0)) { return NULL; } return ciphersuite_info; } static void ssl_tls13_select_ciphersuite( mbedtls_ssl_context *ssl, const unsigned char *cipher_suites, const unsigned char *cipher_suites_end, int psk_ciphersuite_id, psa_algorithm_t psk_hash_alg, const mbedtls_ssl_ciphersuite_t **selected_ciphersuite_info) { *selected_ciphersuite_info = NULL; /* * In a compliant ClientHello the byte-length of the list of ciphersuites * is even and this function relies on this fact. This should have been * checked in the main ClientHello parsing function. Double check here. */ if ((cipher_suites_end - cipher_suites) & 1) { return; } for (const unsigned char *p = cipher_suites; p < cipher_suites_end; p += 2) { /* * "cipher_suites_end - p is even" is an invariant of the loop. As * cipher_suites_end - p > 0, we have cipher_suites_end - p >= 2 and it * is thus safe to read two bytes. */ uint16_t id = MBEDTLS_GET_UINT16_BE(p, 0); const mbedtls_ssl_ciphersuite_t *info = ssl_tls13_validate_peer_ciphersuite(ssl, id); if (info == NULL) { continue; } /* * If a valid PSK ciphersuite identifier has been passed in, we want * an exact match. */ if (psk_ciphersuite_id != 0) { if (id != psk_ciphersuite_id) { continue; } } else if (psk_hash_alg != PSA_ALG_NONE) { if (mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) info->mac) != psk_hash_alg) { continue; } } *selected_ciphersuite_info = info; return; } MBEDTLS_SSL_DEBUG_MSG(2, ("No matched ciphersuite, psk_ciphersuite_id=%x, psk_hash_alg=%lx", (unsigned) psk_ciphersuite_id, (unsigned long) psk_hash_alg)); } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) /* From RFC 8446: * * enum { psk_ke(0), psk_dhe_ke(1), (255) } PskKeyExchangeMode; * struct { * PskKeyExchangeMode ke_modes<1..255>; * } PskKeyExchangeModes; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_key_exchange_modes_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { const unsigned char *p = buf; size_t ke_modes_len; int ke_modes = 0; /* Read ke_modes length (1 Byte) */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); ke_modes_len = *p++; /* Currently, there are only two PSK modes, so even without looking * at the content, something's wrong if the list has more than 2 items. */ if (ke_modes_len > 2) { MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, ke_modes_len); while (ke_modes_len-- != 0) { switch (*p++) { case MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE: ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; MBEDTLS_SSL_DEBUG_MSG(3, ("Found PSK KEX MODE")); break; case MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE: ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; MBEDTLS_SSL_DEBUG_MSG(3, ("Found PSK_EPHEMERAL KEX MODE")); break; default: MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } } ssl->handshake->tls13_kex_modes = ke_modes; return 0; } /* * Non-error return values of * ssl_tls13_offered_psks_check_identity_match_ticket() and * ssl_tls13_offered_psks_check_identity_match(). They are positive to * not collide with error codes that are negative. Zero * (SSL_TLS1_3_PSK_IDENTITY_MATCH) in case of success as it may be propagated * up by the callers of this function as a generic success condition. * * The return value SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE means * that the pre-shared-key identity matches that of a ticket or an externally- * provisioned pre-shared-key. We have thus been able to retrieve the * attributes of the pre-shared-key but at least one of them does not meet * some criteria and the pre-shared-key cannot be used. For example, a ticket * is expired or its version is not TLS 1.3. Note eventually that the return * value SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE does not have * anything to do with binder check. A binder check is done only when a * suitable pre-shared-key has been selected and only for that selected * pre-shared-key: if the binder check fails, we fail the handshake and we do * not try to find another pre-shared-key for which the binder check would * succeed as recommended by the specification. */ #define SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH … #define SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE … #define SSL_TLS1_3_PSK_IDENTITY_MATCH … MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_key_exchange_is_psk_available(mbedtls_ssl_context *ssl); MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_key_exchange_is_psk_ephemeral_available(mbedtls_ssl_context *ssl); #if defined(MBEDTLS_SSL_SESSION_TICKETS) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_offered_psks_check_identity_match_ticket( mbedtls_ssl_context *ssl, const unsigned char *identity, size_t identity_len, uint32_t obfuscated_ticket_age, mbedtls_ssl_session *session) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *ticket_buffer; #if defined(MBEDTLS_HAVE_TIME) mbedtls_ms_time_t now; mbedtls_ms_time_t server_age; uint32_t client_age; mbedtls_ms_time_t age_diff; #endif ((void) obfuscated_ticket_age); MBEDTLS_SSL_DEBUG_MSG(2, ("=> check_identity_match_ticket")); /* Ticket parser is not configured, Skip */ if (ssl->conf->f_ticket_parse == NULL || identity_len == 0) { return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; } /* We create a copy of the encrypted ticket since the ticket parsing * function is allowed to use its input buffer as an output buffer * (in-place decryption). We do, however, need the original buffer for * computing the PSK binder value. */ ticket_buffer = mbedtls_calloc(1, identity_len); if (ticket_buffer == NULL) { return MBEDTLS_ERR_SSL_ALLOC_FAILED; } memcpy(ticket_buffer, identity, identity_len); ret = ssl->conf->f_ticket_parse(ssl->conf->p_ticket, session, ticket_buffer, identity_len); switch (ret) { case 0: ret = SSL_TLS1_3_PSK_IDENTITY_MATCH; break; case MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED: MBEDTLS_SSL_DEBUG_MSG(3, ("ticket is expired")); ret = SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; break; case MBEDTLS_ERR_SSL_INVALID_MAC: MBEDTLS_SSL_DEBUG_MSG(3, ("ticket is not authentic")); ret = SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; break; default: MBEDTLS_SSL_DEBUG_RET(1, "ticket_parse", ret); ret = SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; } /* We delete the temporary buffer */ mbedtls_free(ticket_buffer); if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { goto exit; } /* * The identity matches that of a ticket. Now check that it has suitable * attributes and bet it will not be the case. */ ret = SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; if (session->tls_version != MBEDTLS_SSL_VERSION_TLS1_3) { MBEDTLS_SSL_DEBUG_MSG(3, ("Ticket TLS version is not 1.3.")); goto exit; } #if defined(MBEDTLS_HAVE_TIME) now = mbedtls_ms_time(); if (now < session->ticket_creation_time) { MBEDTLS_SSL_DEBUG_MSG( 3, ("Invalid ticket creation time ( now = %" MBEDTLS_PRINTF_MS_TIME ", creation_time = %" MBEDTLS_PRINTF_MS_TIME " )", now, session->ticket_creation_time)); goto exit; } server_age = now - session->ticket_creation_time; /* RFC 8446 section 4.6.1 * * Servers MUST NOT use any value greater than 604800 seconds (7 days). * * RFC 8446 section 4.2.11.1 * * Clients MUST NOT attempt to use tickets which have ages greater than * the "ticket_lifetime" value which was provided with the ticket. * */ if (server_age > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME * 1000) { MBEDTLS_SSL_DEBUG_MSG( 3, ("Ticket age exceeds limitation ticket_age = %" MBEDTLS_PRINTF_MS_TIME, server_age)); goto exit; } /* RFC 8446 section 4.2.10 * * For PSKs provisioned via NewSessionTicket, a server MUST validate that * the ticket age for the selected PSK identity (computed by subtracting * ticket_age_add from PskIdentity.obfuscated_ticket_age modulo 2^32) is * within a small tolerance of the time since the ticket was issued. * * NOTE: The typical accuracy of an RTC crystal is ±100 to ±20 parts per * million (360 to 72 milliseconds per hour). Default tolerance * window is 6s, thus in the worst case clients and servers must * sync up their system time every 6000/360/2~=8 hours. */ client_age = obfuscated_ticket_age - session->ticket_age_add; age_diff = server_age - (mbedtls_ms_time_t) client_age; if (age_diff < -MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE || age_diff > MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE) { MBEDTLS_SSL_DEBUG_MSG( 3, ("Ticket age outside tolerance window ( diff = %" MBEDTLS_PRINTF_MS_TIME ")", age_diff)); goto exit; } #endif /* MBEDTLS_HAVE_TIME */ /* * All good, we have found a suitable ticket. */ ret = SSL_TLS1_3_PSK_IDENTITY_MATCH; exit: if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { mbedtls_ssl_session_free(session); } MBEDTLS_SSL_DEBUG_MSG(2, ("<= check_identity_match_ticket")); return ret; } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_offered_psks_check_identity_match( mbedtls_ssl_context *ssl, const unsigned char *identity, size_t identity_len, uint32_t obfuscated_ticket_age, int *psk_type, mbedtls_ssl_session *session) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ((void) session); ((void) obfuscated_ticket_age); *psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL; MBEDTLS_SSL_DEBUG_BUF(4, "identity", identity, identity_len); #if defined(MBEDTLS_SSL_SESSION_TICKETS) ret = ssl_tls13_offered_psks_check_identity_match_ticket( ssl, identity, identity_len, obfuscated_ticket_age, session); if (ret == SSL_TLS1_3_PSK_IDENTITY_MATCH) { *psk_type = MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION; ret = mbedtls_ssl_set_hs_psk(ssl, session->resumption_key, session->resumption_key_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret); return ret; } MBEDTLS_SSL_DEBUG_BUF(4, "Ticket-resumed PSK:", session->resumption_key, session->resumption_key_len); MBEDTLS_SSL_DEBUG_MSG(4, ("ticket: obfuscated_ticket_age: %u", (unsigned) obfuscated_ticket_age)); return SSL_TLS1_3_PSK_IDENTITY_MATCH; } else if (ret == SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE) { return SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ /* Check identity with external configured function */ if (ssl->conf->f_psk != NULL) { if (ssl->conf->f_psk( ssl->conf->p_psk, ssl, identity, identity_len) == 0) { return SSL_TLS1_3_PSK_IDENTITY_MATCH; } return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; } MBEDTLS_SSL_DEBUG_BUF(5, "identity", identity, identity_len); /* Check identity with pre-configured psk */ if (ssl->conf->psk_identity != NULL && identity_len == ssl->conf->psk_identity_len && mbedtls_ct_memcmp(ssl->conf->psk_identity, identity, identity_len) == 0) { ret = mbedtls_ssl_set_hs_psk(ssl, ssl->conf->psk, ssl->conf->psk_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret); return ret; } return SSL_TLS1_3_PSK_IDENTITY_MATCH; } return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; } /* * Non-error return values of ssl_tls13_offered_psks_check_binder_match(). * They are positive to not collide with error codes that are negative. Zero * (SSL_TLS1_3_BINDER_MATCH) in case of success as it may be propagated up * by the callers of this function as a generic success condition. */ #define SSL_TLS1_3_BINDER_DOES_NOT_MATCH … #define SSL_TLS1_3_BINDER_MATCH … MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_offered_psks_check_binder_match( mbedtls_ssl_context *ssl, const unsigned char *binder, size_t binder_len, int psk_type, psa_algorithm_t psk_hash_alg) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char transcript[PSA_HASH_MAX_SIZE]; size_t transcript_len; unsigned char *psk; size_t psk_len; unsigned char server_computed_binder[PSA_HASH_MAX_SIZE]; if (binder_len != PSA_HASH_LENGTH(psk_hash_alg)) { return SSL_TLS1_3_BINDER_DOES_NOT_MATCH; } /* Get current state of handshake transcript. */ ret = mbedtls_ssl_get_handshake_transcript( ssl, mbedtls_md_type_from_psa_alg(psk_hash_alg), transcript, sizeof(transcript), &transcript_len); if (ret != 0) { return ret; } ret = mbedtls_ssl_tls13_export_handshake_psk(ssl, &psk, &psk_len); if (ret != 0) { return ret; } ret = mbedtls_ssl_tls13_create_psk_binder(ssl, psk_hash_alg, psk, psk_len, psk_type, transcript, server_computed_binder); #if defined(MBEDTLS_USE_PSA_CRYPTO) mbedtls_free((void *) psk); #endif if (ret != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("PSK binder calculation failed.")); return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } MBEDTLS_SSL_DEBUG_BUF(3, "psk binder ( computed ): ", server_computed_binder, transcript_len); MBEDTLS_SSL_DEBUG_BUF(3, "psk binder ( received ): ", binder, binder_len); if (mbedtls_ct_memcmp(server_computed_binder, binder, PSA_HASH_LENGTH(psk_hash_alg)) == 0) { return SSL_TLS1_3_BINDER_MATCH; } mbedtls_platform_zeroize(server_computed_binder, sizeof(server_computed_binder)); return SSL_TLS1_3_BINDER_DOES_NOT_MATCH; } #if defined(MBEDTLS_SSL_SESSION_TICKETS) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_session_copy_ticket(mbedtls_ssl_session *dst, const mbedtls_ssl_session *src) { dst->ticket_age_add = src->ticket_age_add; dst->ticket_flags = src->ticket_flags; dst->resumption_key_len = src->resumption_key_len; if (src->resumption_key_len == 0) { return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } memcpy(dst->resumption_key, src->resumption_key, src->resumption_key_len); #if defined(MBEDTLS_SSL_EARLY_DATA) dst->max_early_data_size = src->max_early_data_size; #if defined(MBEDTLS_SSL_ALPN) int ret = mbedtls_ssl_session_set_ticket_alpn(dst, src->ticket_alpn); if (ret != 0) { return ret; } #endif /* MBEDTLS_SSL_ALPN */ #endif /* MBEDTLS_SSL_EARLY_DATA*/ return 0; } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ struct psk_attributes { int type; int key_exchange_mode; const mbedtls_ssl_ciphersuite_t *ciphersuite_info; }; #define PSK_ATTRIBUTES_INIT … /* Parser for pre_shared_key extension in client hello * struct { * opaque identity<1..2^16-1>; * uint32 obfuscated_ticket_age; * } PskIdentity; * * opaque PskBinderEntry<32..255>; * * struct { * PskIdentity identities<7..2^16-1>; * PskBinderEntry binders<33..2^16-1>; * } OfferedPsks; * * struct { * select (Handshake.msg_type) { * case client_hello: OfferedPsks; * .... * }; * } PreSharedKeyExtension; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl, const unsigned char *pre_shared_key_ext, const unsigned char *pre_shared_key_ext_end, const unsigned char *ciphersuites, const unsigned char *ciphersuites_end, struct psk_attributes *psk) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const unsigned char *identities = pre_shared_key_ext; const unsigned char *p_identity_len; size_t identities_len; const unsigned char *identities_end; const unsigned char *binders; const unsigned char *p_binder_len; size_t binders_len; const unsigned char *binders_end; int matched_identity = -1; int identity_id = -1; MBEDTLS_SSL_DEBUG_BUF(3, "pre_shared_key extension", pre_shared_key_ext, pre_shared_key_ext_end - pre_shared_key_ext); /* identities_len 2 bytes * identities_data >= 7 bytes */ MBEDTLS_SSL_CHK_BUF_READ_PTR(identities, pre_shared_key_ext_end, 7 + 2); identities_len = MBEDTLS_GET_UINT16_BE(identities, 0); p_identity_len = identities + 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p_identity_len, pre_shared_key_ext_end, identities_len); identities_end = p_identity_len + identities_len; /* binders_len 2 bytes * binders >= 33 bytes */ binders = identities_end; MBEDTLS_SSL_CHK_BUF_READ_PTR(binders, pre_shared_key_ext_end, 33 + 2); binders_len = MBEDTLS_GET_UINT16_BE(binders, 0); p_binder_len = binders + 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p_binder_len, pre_shared_key_ext_end, binders_len); binders_end = p_binder_len + binders_len; ret = ssl->handshake->update_checksum(ssl, pre_shared_key_ext, identities_end - pre_shared_key_ext); if (0 != ret) { MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); return ret; } while (p_identity_len < identities_end && p_binder_len < binders_end) { const unsigned char *identity; size_t identity_len; uint32_t obfuscated_ticket_age; const unsigned char *binder; size_t binder_len; int psk_ciphersuite_id; psa_algorithm_t psk_hash_alg; int allowed_key_exchange_modes; mbedtls_ssl_session session; mbedtls_ssl_session_init(&session); MBEDTLS_SSL_CHK_BUF_READ_PTR(p_identity_len, identities_end, 2 + 1 + 4); identity_len = MBEDTLS_GET_UINT16_BE(p_identity_len, 0); identity = p_identity_len + 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(identity, identities_end, identity_len + 4); obfuscated_ticket_age = MBEDTLS_GET_UINT32_BE(identity, identity_len); p_identity_len += identity_len + 6; MBEDTLS_SSL_CHK_BUF_READ_PTR(p_binder_len, binders_end, 1 + 32); binder_len = *p_binder_len; binder = p_binder_len + 1; MBEDTLS_SSL_CHK_BUF_READ_PTR(binder, binders_end, binder_len); p_binder_len += binder_len + 1; identity_id++; if (matched_identity != -1) { continue; } ret = ssl_tls13_offered_psks_check_identity_match( ssl, identity, identity_len, obfuscated_ticket_age, &psk->type, &session); if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { continue; } MBEDTLS_SSL_DEBUG_MSG(4, ("found matched identity")); switch (psk->type) { case MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL: psk_ciphersuite_id = 0; psk_hash_alg = PSA_ALG_SHA_256; allowed_key_exchange_modes = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL; break; #if defined(MBEDTLS_SSL_SESSION_TICKETS) case MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION: psk_ciphersuite_id = session.ciphersuite; psk_hash_alg = PSA_ALG_NONE; ssl->session_negotiate->ticket_flags = session.ticket_flags; allowed_key_exchange_modes = session.ticket_flags & MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL; break; #endif default: return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE; if ((allowed_key_exchange_modes & MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL) && ssl_tls13_key_exchange_is_psk_ephemeral_available(ssl)) { psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; } else if ((allowed_key_exchange_modes & MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK) && ssl_tls13_key_exchange_is_psk_available(ssl)) { psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; } if (psk->key_exchange_mode == MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE) { MBEDTLS_SSL_DEBUG_MSG(3, ("No suitable PSK key exchange mode")); continue; } ssl_tls13_select_ciphersuite(ssl, ciphersuites, ciphersuites_end, psk_ciphersuite_id, psk_hash_alg, &psk->ciphersuite_info); if (psk->ciphersuite_info == NULL) { #if defined(MBEDTLS_SSL_SESSION_TICKETS) mbedtls_ssl_session_free(&session); #endif /* * We consider finding a ciphersuite suitable for the PSK as part * of the validation of its binder. Thus if we do not find one, we * abort the handshake with a decrypt_error alert. */ MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } ret = ssl_tls13_offered_psks_check_binder_match( ssl, binder, binder_len, psk->type, mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) psk->ciphersuite_info->mac)); if (ret != SSL_TLS1_3_BINDER_MATCH) { /* For security reasons, the handshake should be aborted when we * fail to validate a binder value. See RFC 8446 section 4.2.11.2 * and appendix E.6. */ #if defined(MBEDTLS_SSL_SESSION_TICKETS) mbedtls_ssl_session_free(&session); #endif MBEDTLS_SSL_DEBUG_MSG(3, ("Invalid binder.")); MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_offered_psks_check_binder_match", ret); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); return ret; } matched_identity = identity_id; #if defined(MBEDTLS_SSL_SESSION_TICKETS) if (psk->type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION) { ret = ssl_tls13_session_copy_ticket(ssl->session_negotiate, &session); mbedtls_ssl_session_free(&session); if (ret != 0) { return ret; } } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ } if (p_identity_len != identities_end || p_binder_len != binders_end) { MBEDTLS_SSL_DEBUG_MSG(3, ("pre_shared_key extension decode error")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR); return MBEDTLS_ERR_SSL_DECODE_ERROR; } /* Update the handshake transcript with the binder list. */ ret = ssl->handshake->update_checksum( ssl, identities_end, (size_t) (binders_end - identities_end)); if (0 != ret) { MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); return ret; } if (matched_identity == -1) { MBEDTLS_SSL_DEBUG_MSG(3, ("No usable PSK or ticket.")); return MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY; } ssl->handshake->selected_identity = (uint16_t) matched_identity; MBEDTLS_SSL_DEBUG_MSG(3, ("Pre shared key found")); return 0; } /* * struct { * select ( Handshake.msg_type ) { * .... * case server_hello: * uint16 selected_identity; * } * } PreSharedKeyExtension; */ static int ssl_tls13_write_server_pre_shared_key_ext(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *olen) { unsigned char *p = (unsigned char *) buf; *olen = 0; int not_using_psk = 0; #if defined(MBEDTLS_USE_PSA_CRYPTO) not_using_psk = (mbedtls_svc_key_id_is_null(ssl->handshake->psk_opaque)); #else not_using_psk = (ssl->handshake->psk == NULL); #endif if (not_using_psk) { /* We shouldn't have called this extension writer unless we've * chosen to use a PSK. */ return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, adding pre_shared_key extension")); MBEDTLS_SSL_CHK_BUF_PTR(p, end, 6); MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_PRE_SHARED_KEY, p, 0); MBEDTLS_PUT_UINT16_BE(2, p, 2); MBEDTLS_PUT_UINT16_BE(ssl->handshake->selected_identity, p, 4); *olen = 6; MBEDTLS_SSL_DEBUG_MSG(4, ("sent selected_identity: %u", ssl->handshake->selected_identity)); mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_PRE_SHARED_KEY); return 0; } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ /* From RFC 8446: * struct { * ProtocolVersion versions<2..254>; * } SupportedVersions; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_supported_versions_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { const unsigned char *p = buf; size_t versions_len; const unsigned char *versions_end; uint16_t tls_version; int found_supported_version = 0; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); versions_len = p[0]; p += 1; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, versions_len); versions_end = p + versions_len; while (p < versions_end) { MBEDTLS_SSL_CHK_BUF_READ_PTR(p, versions_end, 2); tls_version = mbedtls_ssl_read_version(p, ssl->conf->transport); p += 2; if (MBEDTLS_SSL_VERSION_TLS1_3 == tls_version) { found_supported_version = 1; break; } if ((MBEDTLS_SSL_VERSION_TLS1_2 == tls_version) && mbedtls_ssl_conf_is_tls12_enabled(ssl->conf)) { found_supported_version = 1; break; } } if (!found_supported_version) { MBEDTLS_SSL_DEBUG_MSG(1, ("No supported version found.")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; } MBEDTLS_SSL_DEBUG_MSG(1, ("Negotiated version: [%04x]", (unsigned int) tls_version)); return (int) tls_version; } #if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) /* * * From RFC 8446: * enum { * ... (0xFFFF) * } NamedGroup; * struct { * NamedGroup named_group_list<2..2^16-1>; * } NamedGroupList; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_supported_groups_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { const unsigned char *p = buf; size_t named_group_list_len; const unsigned char *named_group_list_end; MBEDTLS_SSL_DEBUG_BUF(3, "supported_groups extension", p, end - buf); MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); named_group_list_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, named_group_list_len); named_group_list_end = p + named_group_list_len; ssl->handshake->hrr_selected_group = 0; while (p < named_group_list_end) { uint16_t named_group; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, named_group_list_end, 2); named_group = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; MBEDTLS_SSL_DEBUG_MSG(2, ("got named group: %s(%04x)", mbedtls_ssl_named_group_to_str(named_group), named_group)); if (!mbedtls_ssl_named_group_is_offered(ssl, named_group) || !mbedtls_ssl_named_group_is_supported(named_group) || ssl->handshake->hrr_selected_group != 0) { continue; } MBEDTLS_SSL_DEBUG_MSG(2, ("add named group %s(%04x) into received list.", mbedtls_ssl_named_group_to_str(named_group), named_group)); ssl->handshake->hrr_selected_group = named_group; } return 0; } #endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */ #define SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH … #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) /* * ssl_tls13_parse_key_shares_ext() verifies whether the information in the * extension is correct and stores the first acceptable key share and its * associated group. * * Possible return values are: * - 0: Successful processing of the client provided key share extension. * - SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH: The key shares provided by * the client does not match a group supported by the server. A * HelloRetryRequest will be needed. * - A negative value for fatal errors. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_key_shares_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char const *p = buf; unsigned char const *client_shares_end; size_t client_shares_len; /* From RFC 8446: * * struct { * KeyShareEntry client_shares<0..2^16-1>; * } KeyShareClientHello; * */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); client_shares_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, client_shares_len); ssl->handshake->offered_group_id = 0; client_shares_end = p + client_shares_len; /* We try to find a suitable key share entry and copy it to the * handshake context. Later, we have to find out whether we can do * something with the provided key share or whether we have to * dismiss it and send a HelloRetryRequest message. */ while (p < client_shares_end) { uint16_t group; size_t key_exchange_len; const unsigned char *key_exchange; /* * struct { * NamedGroup group; * opaque key_exchange<1..2^16-1>; * } KeyShareEntry; */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, client_shares_end, 4); group = MBEDTLS_GET_UINT16_BE(p, 0); key_exchange_len = MBEDTLS_GET_UINT16_BE(p, 2); p += 4; key_exchange = p; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, client_shares_end, key_exchange_len); p += key_exchange_len; /* Continue parsing even if we have already found a match, * for input validation purposes. */ if (!mbedtls_ssl_named_group_is_offered(ssl, group) || !mbedtls_ssl_named_group_is_supported(group) || ssl->handshake->offered_group_id != 0) { continue; } /* * ECDHE and FFDHE groups are supported */ if (mbedtls_ssl_tls13_named_group_is_ecdhe(group) || mbedtls_ssl_tls13_named_group_is_ffdh(group)) { MBEDTLS_SSL_DEBUG_MSG(2, ("ECDH/FFDH group: %s (%04x)", mbedtls_ssl_named_group_to_str(group), group)); ret = mbedtls_ssl_tls13_read_public_xxdhe_share( ssl, key_exchange - 2, key_exchange_len + 2); if (ret != 0) { return ret; } } else { MBEDTLS_SSL_DEBUG_MSG(4, ("Unrecognized NamedGroup %u", (unsigned) group)); continue; } ssl->handshake->offered_group_id = group; } if (ssl->handshake->offered_group_id == 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("no matching key share")); return SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH; } return 0; } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_client_hello_has_exts(mbedtls_ssl_context *ssl, int exts_mask) { int masked = ssl->handshake->received_extensions & exts_mask; return masked == exts_mask; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange( mbedtls_ssl_context *ssl) { return ssl_tls13_client_hello_has_exts( ssl, MBEDTLS_SSL_EXT_MASK(SUPPORTED_GROUPS) | MBEDTLS_SSL_EXT_MASK(KEY_SHARE) | MBEDTLS_SSL_EXT_MASK(SIG_ALG)); } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_client_hello_has_exts_for_psk_key_exchange( mbedtls_ssl_context *ssl) { return ssl_tls13_client_hello_has_exts( ssl, MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) | MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)); } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED */ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange( mbedtls_ssl_context *ssl) { return ssl_tls13_client_hello_has_exts( ssl, MBEDTLS_SSL_EXT_MASK(SUPPORTED_GROUPS) | MBEDTLS_SSL_EXT_MASK(KEY_SHARE) | MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) | MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)); } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED */ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_key_exchange_is_psk_available(mbedtls_ssl_context *ssl) { #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED) return mbedtls_ssl_conf_tls13_is_psk_enabled(ssl) && mbedtls_ssl_tls13_is_psk_supported(ssl) && ssl_tls13_client_hello_has_exts_for_psk_key_exchange(ssl); #else ((void) ssl); return 0; #endif } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_key_exchange_is_psk_ephemeral_available(mbedtls_ssl_context *ssl) { #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED) return mbedtls_ssl_conf_tls13_is_psk_ephemeral_enabled(ssl) && mbedtls_ssl_tls13_is_psk_ephemeral_supported(ssl) && ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange(ssl); #else ((void) ssl); return 0; #endif } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_key_exchange_is_ephemeral_available(mbedtls_ssl_context *ssl) { #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) return mbedtls_ssl_conf_tls13_is_ephemeral_enabled(ssl) && ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange(ssl); #else ((void) ssl); return 0; #endif } #if defined(MBEDTLS_X509_CRT_PARSE_C) && \ defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) #if defined(MBEDTLS_USE_PSA_CRYPTO) static psa_algorithm_t ssl_tls13_iana_sig_alg_to_psa_alg(uint16_t sig_alg) { switch (sig_alg) { case MBEDTLS_TLS1_3_SIG_ECDSA_SECP256R1_SHA256: return PSA_ALG_ECDSA(PSA_ALG_SHA_256); case MBEDTLS_TLS1_3_SIG_ECDSA_SECP384R1_SHA384: return PSA_ALG_ECDSA(PSA_ALG_SHA_384); case MBEDTLS_TLS1_3_SIG_ECDSA_SECP521R1_SHA512: return PSA_ALG_ECDSA(PSA_ALG_SHA_512); case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA256: return PSA_ALG_RSA_PSS(PSA_ALG_SHA_256); case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA384: return PSA_ALG_RSA_PSS(PSA_ALG_SHA_384); case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA512: return PSA_ALG_RSA_PSS(PSA_ALG_SHA_512); case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA256: return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_256); case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA384: return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_384); case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA512: return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_512); default: return PSA_ALG_NONE; } } #endif /* MBEDTLS_USE_PSA_CRYPTO */ /* * Pick best ( private key, certificate chain ) pair based on the signature * algorithms supported by the client. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_pick_key_cert(mbedtls_ssl_context *ssl) { mbedtls_ssl_key_cert *key_cert, *key_cert_list; const uint16_t *sig_alg = ssl->handshake->received_sig_algs; #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) if (ssl->handshake->sni_key_cert != NULL) { key_cert_list = ssl->handshake->sni_key_cert; } else #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ key_cert_list = ssl->conf->key_cert; if (key_cert_list == NULL) { MBEDTLS_SSL_DEBUG_MSG(3, ("server has no certificate")); return -1; } for (; *sig_alg != MBEDTLS_TLS1_3_SIG_NONE; sig_alg++) { if (!mbedtls_ssl_sig_alg_is_offered(ssl, *sig_alg)) { continue; } if (!mbedtls_ssl_tls13_sig_alg_for_cert_verify_is_supported(*sig_alg)) { continue; } for (key_cert = key_cert_list; key_cert != NULL; key_cert = key_cert->next) { #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_algorithm_t psa_alg = PSA_ALG_NONE; #endif /* MBEDTLS_USE_PSA_CRYPTO */ MBEDTLS_SSL_DEBUG_CRT(3, "certificate (chain) candidate", key_cert->cert); /* * This avoids sending the client a cert it'll reject based on * keyUsage or other extensions. */ if (mbedtls_x509_crt_check_key_usage( key_cert->cert, MBEDTLS_X509_KU_DIGITAL_SIGNATURE) != 0 || mbedtls_x509_crt_check_extended_key_usage( key_cert->cert, MBEDTLS_OID_SERVER_AUTH, MBEDTLS_OID_SIZE(MBEDTLS_OID_SERVER_AUTH)) != 0) { MBEDTLS_SSL_DEBUG_MSG(3, ("certificate mismatch: " "(extended) key usage extension")); continue; } MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_tls13_pick_key_cert:" "check signature algorithm %s [%04x]", mbedtls_ssl_sig_alg_to_str(*sig_alg), *sig_alg)); #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_alg = ssl_tls13_iana_sig_alg_to_psa_alg(*sig_alg); #endif /* MBEDTLS_USE_PSA_CRYPTO */ if (mbedtls_ssl_tls13_check_sig_alg_cert_key_match( *sig_alg, &key_cert->cert->pk) #if defined(MBEDTLS_USE_PSA_CRYPTO) && psa_alg != PSA_ALG_NONE && mbedtls_pk_can_do_ext(&key_cert->cert->pk, psa_alg, PSA_KEY_USAGE_SIGN_HASH) == 1 #endif /* MBEDTLS_USE_PSA_CRYPTO */ ) { ssl->handshake->key_cert = key_cert; MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_tls13_pick_key_cert:" "selected signature algorithm" " %s [%04x]", mbedtls_ssl_sig_alg_to_str(*sig_alg), *sig_alg)); MBEDTLS_SSL_DEBUG_CRT( 3, "selected certificate (chain)", ssl->handshake->key_cert->cert); return 0; } } } MBEDTLS_SSL_DEBUG_MSG(2, ("ssl_tls13_pick_key_cert:" "no suitable certificate found")); return -1; } #endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ /* * * STATE HANDLING: ClientHello * * There are three possible classes of outcomes when parsing the ClientHello: * * 1) The ClientHello was well-formed and matched the server's configuration. * * In this case, the server progresses to sending its ServerHello. * * 2) The ClientHello was well-formed but didn't match the server's * configuration. * * For example, the client might not have offered a key share which * the server supports, or the server might require a cookie. * * In this case, the server sends a HelloRetryRequest. * * 3) The ClientHello was ill-formed * * In this case, we abort the handshake. * */ /* * Structure of this message: * * uint16 ProtocolVersion; * opaque Random[32]; * uint8 CipherSuite[2]; // Cryptographic suite selector * * struct { * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 * Random random; * opaque legacy_session_id<0..32>; * CipherSuite cipher_suites<2..2^16-2>; * opaque legacy_compression_methods<1..2^8-1>; * Extension extensions<8..2^16-1>; * } ClientHello; */ #define SSL_CLIENT_HELLO_OK … #define SSL_CLIENT_HELLO_HRR_REQUIRED … #define SSL_CLIENT_HELLO_TLS1_2 … MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_client_hello(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const unsigned char *p = buf; const unsigned char *random; size_t legacy_session_id_len; const unsigned char *legacy_session_id; size_t cipher_suites_len; const unsigned char *cipher_suites; const unsigned char *cipher_suites_end; size_t extensions_len; const unsigned char *extensions_end; const unsigned char *supported_versions_data; const unsigned char *supported_versions_data_end; mbedtls_ssl_handshake_params *handshake = ssl->handshake; int hrr_required = 0; int no_usable_share_for_key_agreement = 0; #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) int got_psk = 0; struct psk_attributes psk = PSK_ATTRIBUTES_INIT; const unsigned char *pre_shared_key_ext = NULL; const unsigned char *pre_shared_key_ext_end = NULL; #endif /* * ClientHello layout: * 0 . 1 protocol version * 2 . 33 random bytes * 34 . 34 session id length ( 1 byte ) * 35 . 34+x session id * .. . .. ciphersuite list length ( 2 bytes ) * .. . .. ciphersuite list * .. . .. compression alg. list length ( 1 byte ) * .. . .. compression alg. list * .. . .. extensions length ( 2 bytes, optional ) * .. . .. extensions ( optional ) */ /* * Minimal length ( with everything empty and extensions omitted ) is * 2 + 32 + 1 + 2 + 1 = 38 bytes. Check that first, so that we can * read at least up to session id length without worrying. */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 38); /* ... * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 * ... * with ProtocolVersion defined as: * uint16 ProtocolVersion; */ if (mbedtls_ssl_read_version(p, ssl->conf->transport) != MBEDTLS_SSL_VERSION_TLS1_2) { MBEDTLS_SSL_DEBUG_MSG(1, ("Unsupported version of TLS.")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; } p += 2; /* ... * Random random; * ... * with Random defined as: * opaque Random[32]; */ random = p; p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN; /* ... * opaque legacy_session_id<0..32>; * ... */ legacy_session_id_len = *(p++); legacy_session_id = p; /* * Check we have enough data for the legacy session identifier * and the ciphersuite list length. */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, legacy_session_id_len + 2); p += legacy_session_id_len; /* ... * CipherSuite cipher_suites<2..2^16-2>; * ... * with CipherSuite defined as: * uint8 CipherSuite[2]; */ cipher_suites_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; cipher_suites = p; /* * The length of the ciphersuite list has to be even. */ if (cipher_suites_len & 1) { MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR); return MBEDTLS_ERR_SSL_DECODE_ERROR; } /* Check we have enough data for the ciphersuite list, the legacy * compression methods and the length of the extensions. * * cipher_suites cipher_suites_len bytes * legacy_compression_methods length 1 byte */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, cipher_suites_len + 1); p += cipher_suites_len; cipher_suites_end = p; /* Check if we have enough data for legacy_compression_methods * and the length of the extensions (2 bytes). */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p + 1, end, p[0] + 2); /* * Search for the supported versions extension and parse it to determine * if the client supports TLS 1.3. */ ret = mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts( ssl, p + 1 + p[0], end, &supported_versions_data, &supported_versions_data_end); if (ret < 0) { MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts"), ret); return ret; } if (ret == 0) { return SSL_CLIENT_HELLO_TLS1_2; } if (ret == 1) { ret = ssl_tls13_parse_supported_versions_ext(ssl, supported_versions_data, supported_versions_data_end); if (ret < 0) { MBEDTLS_SSL_DEBUG_RET(1, ("ssl_tls13_parse_supported_versions_ext"), ret); return ret; } /* * The supported versions extension was parsed successfully as the * value returned by ssl_tls13_parse_supported_versions_ext() is * positive. The return value is then equal to * MBEDTLS_SSL_VERSION_TLS1_2 or MBEDTLS_SSL_VERSION_TLS1_3, defining * the TLS version to negotiate. */ if (MBEDTLS_SSL_VERSION_TLS1_2 == ret) { return SSL_CLIENT_HELLO_TLS1_2; } } /* * We negotiate TLS 1.3. */ ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; ssl->session_negotiate->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; ssl->session_negotiate->endpoint = ssl->conf->endpoint; /* Before doing any crypto, make sure we can. */ ret = mbedtls_ssl_tls13_crypto_init(ssl); if (ret != 0) { return ret; } /* * We are negotiating the version 1.3 of the protocol. Do what we have * postponed: copy of the client random bytes, copy of the legacy session * identifier and selection of the TLS 1.3 cipher suite. */ MBEDTLS_SSL_DEBUG_BUF(3, "client hello, random bytes", random, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); memcpy(&handshake->randbytes[0], random, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); if (legacy_session_id_len > sizeof(ssl->session_negotiate->id)) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad client hello message")); return MBEDTLS_ERR_SSL_DECODE_ERROR; } ssl->session_negotiate->id_len = legacy_session_id_len; MBEDTLS_SSL_DEBUG_BUF(3, "client hello, session id", legacy_session_id, legacy_session_id_len); memcpy(&ssl->session_negotiate->id[0], legacy_session_id, legacy_session_id_len); /* * Search for a matching ciphersuite */ MBEDTLS_SSL_DEBUG_BUF(3, "client hello, list of cipher suites", cipher_suites, cipher_suites_len); ssl_tls13_select_ciphersuite(ssl, cipher_suites, cipher_suites_end, 0, PSA_ALG_NONE, &handshake->ciphersuite_info); if (handshake->ciphersuite_info == NULL) { MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } ssl->session_negotiate->ciphersuite = handshake->ciphersuite_info->id; MBEDTLS_SSL_DEBUG_MSG(2, ("selected ciphersuite: %04x - %s", ((unsigned) handshake->ciphersuite_info->id), handshake->ciphersuite_info->name)); /* ... * opaque legacy_compression_methods<1..2^8-1>; * ... */ if (p[0] != 1 || p[1] != MBEDTLS_SSL_COMPRESS_NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad legacy compression method")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } p += 2; /* ... * Extension extensions<8..2^16-1>; * ... * with Extension defined as: * struct { * ExtensionType extension_type; * opaque extension_data<0..2^16-1>; * } Extension; */ extensions_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extensions_len); extensions_end = p + extensions_len; MBEDTLS_SSL_DEBUG_BUF(3, "client hello extensions", p, extensions_len); handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE; while (p < extensions_end) { unsigned int extension_type; size_t extension_data_len; const unsigned char *extension_data_end; uint32_t allowed_exts = MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CH; if (ssl->handshake->hello_retry_request_flag) { /* Do not accept early data extension in 2nd ClientHello */ allowed_exts &= ~MBEDTLS_SSL_EXT_MASK(EARLY_DATA); } /* RFC 8446, section 4.2.11 * * The "pre_shared_key" extension MUST be the last extension in the * ClientHello (this facilitates implementation as described below). * Servers MUST check that it is the last extension and otherwise fail * the handshake with an "illegal_parameter" alert. */ if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY)) { MBEDTLS_SSL_DEBUG_MSG( 3, ("pre_shared_key is not last extension.")); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, 4); extension_type = MBEDTLS_GET_UINT16_BE(p, 0); extension_data_len = MBEDTLS_GET_UINT16_BE(p, 2); p += 4; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, extension_data_len); extension_data_end = p + extension_data_len; ret = mbedtls_ssl_tls13_check_received_extension( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, extension_type, allowed_exts); if (ret != 0) { return ret; } switch (extension_type) { #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) case MBEDTLS_TLS_EXT_SERVERNAME: MBEDTLS_SSL_DEBUG_MSG(3, ("found ServerName extension")); ret = mbedtls_ssl_parse_server_name_ext(ssl, p, extension_data_end); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_parse_servername_ext", ret); return ret; } break; #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ #if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS: MBEDTLS_SSL_DEBUG_MSG(3, ("found supported group extension")); /* Supported Groups Extension * * When sent by the client, the "supported_groups" extension * indicates the named groups which the client supports, * ordered from most preferred to least preferred. */ ret = ssl_tls13_parse_supported_groups_ext( ssl, p, extension_data_end); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_parse_supported_groups_ext", ret); return ret; } break; #endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH*/ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) case MBEDTLS_TLS_EXT_KEY_SHARE: MBEDTLS_SSL_DEBUG_MSG(3, ("found key share extension")); /* * Key Share Extension * * When sent by the client, the "key_share" extension * contains the endpoint's cryptographic parameters for * ECDHE/DHE key establishment methods. */ ret = ssl_tls13_parse_key_shares_ext( ssl, p, extension_data_end); if (ret == SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH) { MBEDTLS_SSL_DEBUG_MSG(2, ("No usable share for key agreement.")); no_usable_share_for_key_agreement = 1; } if (ret < 0) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_parse_key_shares_ext", ret); return ret; } break; #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS: /* Already parsed */ break; #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) case MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES: MBEDTLS_SSL_DEBUG_MSG( 3, ("found psk key exchange modes extension")); ret = ssl_tls13_parse_key_exchange_modes_ext( ssl, p, extension_data_end); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_parse_key_exchange_modes_ext", ret); return ret; } break; #endif case MBEDTLS_TLS_EXT_PRE_SHARED_KEY: MBEDTLS_SSL_DEBUG_MSG(3, ("found pre_shared_key extension")); if ((handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)) == 0) { MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) /* Delay processing of the PSK identity once we have * found out which algorithms to use. We keep a pointer * to the buffer and the size for later processing. */ pre_shared_key_ext = p; pre_shared_key_ext_end = extension_data_end; #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ break; #if defined(MBEDTLS_SSL_ALPN) case MBEDTLS_TLS_EXT_ALPN: MBEDTLS_SSL_DEBUG_MSG(3, ("found alpn extension")); ret = mbedtls_ssl_parse_alpn_ext(ssl, p, extension_data_end); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, ("mbedtls_ssl_parse_alpn_ext"), ret); return ret; } break; #endif /* MBEDTLS_SSL_ALPN */ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) case MBEDTLS_TLS_EXT_SIG_ALG: MBEDTLS_SSL_DEBUG_MSG(3, ("found signature_algorithms extension")); ret = mbedtls_ssl_parse_sig_alg_ext( ssl, p, extension_data_end); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_parse_sig_alg_ext", ret); return ret; } break; #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ #if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT: MBEDTLS_SSL_DEBUG_MSG(3, ("found record_size_limit extension")); ret = mbedtls_ssl_tls13_parse_record_size_limit_ext( ssl, p, extension_data_end); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, ("mbedtls_ssl_tls13_parse_record_size_limit_ext"), ret); return ret; } break; #endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */ default: MBEDTLS_SSL_PRINT_EXT( 3, MBEDTLS_SSL_HS_CLIENT_HELLO, extension_type, "( ignored )"); break; } p += extension_data_len; } MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_CLIENT_HELLO, handshake->received_extensions); ret = mbedtls_ssl_add_hs_hdr_to_checksum(ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, p - buf); if (0 != ret) { MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_add_hs_hdr_to_checksum"), ret); return ret; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) /* Update checksum with either * - The entire content of the CH message, if no PSK extension is present * - The content up to but excluding the PSK extension, if present. * Always parse the pre-shared-key extension when present in the * ClientHello even if some pre-requisites for PSK key exchange modes are * not met. That way we always validate the syntax of the extension. */ if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY)) { ret = handshake->update_checksum(ssl, buf, pre_shared_key_ext - buf); if (0 != ret) { MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); return ret; } ret = ssl_tls13_parse_pre_shared_key_ext(ssl, pre_shared_key_ext, pre_shared_key_ext_end, cipher_suites, cipher_suites_end, &psk); if (ret == 0) { got_psk = 1; } else if (ret != MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_parse_pre_shared_key_ext", ret); return ret; } } else #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ { ret = handshake->update_checksum(ssl, buf, p - buf); if (0 != ret) { MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); return ret; } } /* * Determine the key exchange algorithm to use. * There are three types of key exchanges supported in TLS 1.3: * - (EC)DH with ECDSA, * - (EC)DH with PSK, * - plain PSK. * * The PSK-based key exchanges may additionally be used with 0-RTT. * * Our built-in order of preference is * 1 ) (EC)DHE-PSK Mode ( psk_ephemeral ) * 2 ) Certificate Mode ( ephemeral ) * 3 ) Plain PSK Mode ( psk ) */ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) if (got_psk && (psk.key_exchange_mode == MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL)) { handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: psk_ephemeral")); } else #endif if (ssl_tls13_key_exchange_is_ephemeral_available(ssl)) { handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL; MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: ephemeral")); } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) else if (got_psk && (psk.key_exchange_mode == MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK)) { handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: psk")); } #endif else { MBEDTLS_SSL_DEBUG_MSG( 1, ("ClientHello message misses mandatory extensions.")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) if (handshake->key_exchange_mode & MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL) { handshake->ciphersuite_info = psk.ciphersuite_info; ssl->session_negotiate->ciphersuite = psk.ciphersuite_info->id; MBEDTLS_SSL_DEBUG_MSG(2, ("Select PSK ciphersuite: %04x - %s", ((unsigned) psk.ciphersuite_info->id), psk.ciphersuite_info->name)); if (psk.type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION) { handshake->resume = 1; } } #endif if (handshake->key_exchange_mode != MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK) { hrr_required = (no_usable_share_for_key_agreement != 0); } mbedtls_ssl_optimize_checksum(ssl, handshake->ciphersuite_info); return hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK; } #if defined(MBEDTLS_SSL_EARLY_DATA) static int ssl_tls13_check_early_data_requirements(mbedtls_ssl_context *ssl) { mbedtls_ssl_handshake_params *handshake = ssl->handshake; if (ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_DISABLED) { MBEDTLS_SSL_DEBUG_MSG( 1, ("EarlyData: rejected, feature disabled in server configuration.")); return -1; } if (!handshake->resume) { /* We currently support early data only in the case of PSKs established via a NewSessionTicket message thus in the case of a session resumption. */ MBEDTLS_SSL_DEBUG_MSG( 1, ("EarlyData: rejected, not a session resumption.")); return -1; } /* RFC 8446 4.2.10 * * In order to accept early data, the server MUST have accepted a PSK cipher * suite and selected the first key offered in the client's "pre_shared_key" * extension. In addition, it MUST verify that the following values are the * same as those associated with the selected PSK: * - The TLS version number * - The selected cipher suite * - The selected ALPN [RFC7301] protocol, if any * * NOTE: * - The TLS version number is checked in * ssl_tls13_offered_psks_check_identity_match_ticket(). */ if (handshake->selected_identity != 0) { MBEDTLS_SSL_DEBUG_MSG( 1, ("EarlyData: rejected, the selected key in " "`pre_shared_key` is not the first one.")); return -1; } if (handshake->ciphersuite_info->id != ssl->session_negotiate->ciphersuite) { MBEDTLS_SSL_DEBUG_MSG( 1, ("EarlyData: rejected, the selected ciphersuite is not the one " "of the selected pre-shared key.")); return -1; } if (!mbedtls_ssl_tls13_session_ticket_allow_early_data(ssl->session_negotiate)) { MBEDTLS_SSL_DEBUG_MSG( 1, ("EarlyData: rejected, early_data not allowed in ticket " "permission bits.")); return -1; } #if defined(MBEDTLS_SSL_ALPN) const char *alpn = mbedtls_ssl_get_alpn_protocol(ssl); size_t alpn_len; if (alpn == NULL && ssl->session_negotiate->ticket_alpn == NULL) { return 0; } if (alpn != NULL) { alpn_len = strlen(alpn); } if (alpn == NULL || ssl->session_negotiate->ticket_alpn == NULL || alpn_len != strlen(ssl->session_negotiate->ticket_alpn) || (memcmp(alpn, ssl->session_negotiate->ticket_alpn, alpn_len) != 0)) { MBEDTLS_SSL_DEBUG_MSG(1, ("EarlyData: rejected, the selected ALPN is different " "from the one associated with the pre-shared key.")); return -1; } #endif return 0; } #endif /* MBEDTLS_SSL_EARLY_DATA */ /* Update the handshake state machine */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_postprocess_client_hello(mbedtls_ssl_context *ssl, int hrr_required) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; /* * Server certificate selection */ if (ssl->conf->f_cert_cb && (ret = ssl->conf->f_cert_cb(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "f_cert_cb", ret); return ret; } #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) ssl->handshake->sni_name = NULL; ssl->handshake->sni_name_len = 0; #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ ret = mbedtls_ssl_tls13_key_schedule_stage_early(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_tls1_3_key_schedule_stage_early", ret); return ret; } #if defined(MBEDTLS_SSL_EARLY_DATA) if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(EARLY_DATA)) { ssl->handshake->early_data_accepted = (!hrr_required) && (ssl_tls13_check_early_data_requirements(ssl) == 0); if (ssl->handshake->early_data_accepted) { ret = mbedtls_ssl_tls13_compute_early_transform(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_compute_early_transform", ret); return ret; } } else { ssl->discard_early_data_record = hrr_required ? MBEDTLS_SSL_EARLY_DATA_DISCARD : MBEDTLS_SSL_EARLY_DATA_TRY_TO_DEPROTECT_AND_DISCARD; } } #else ((void) hrr_required); #endif /* MBEDTLS_SSL_EARLY_DATA */ return 0; } /* * Main entry point from the state machine; orchestrates the otherfunctions. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_client_hello(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf = NULL; size_t buflen = 0; int parse_client_hello_ret; MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse client hello")); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, &buf, &buflen)); MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_parse_client_hello(ssl, buf, buf + buflen)); parse_client_hello_ret = ret; /* Store positive return value of * parse_client_hello, * as negative error codes are handled * by MBEDTLS_SSL_PROC_CHK_NEG. */ /* * Version 1.2 of the protocol has to be used for the handshake. * If TLS 1.2 is not supported, abort the handshake. Otherwise, set the * ssl->keep_current_message flag for the ClientHello to be kept and parsed * as a TLS 1.2 ClientHello. We also change ssl->tls_version to * MBEDTLS_SSL_VERSION_TLS1_2 thus from now on mbedtls_ssl_handshake_step() * will dispatch to the TLS 1.2 state machine. */ if (SSL_CLIENT_HELLO_TLS1_2 == parse_client_hello_ret) { /* Check if server supports TLS 1.2 */ if (!mbedtls_ssl_conf_is_tls12_enabled(ssl->conf)) { MBEDTLS_SSL_DEBUG_MSG( 1, ("TLS 1.2 not supported.")); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; } ssl->keep_current_message = 1; ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_2; return 0; } MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_client_hello(ssl, parse_client_hello_ret == SSL_CLIENT_HELLO_HRR_REQUIRED)); if (SSL_CLIENT_HELLO_OK == parse_client_hello_ret) { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_HELLO); } else { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HELLO_RETRY_REQUEST); } cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse client hello")); return ret; } /* * Handler for MBEDTLS_SSL_SERVER_HELLO */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_prepare_server_hello(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *server_randbytes = ssl->handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN; if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, server_randbytes, MBEDTLS_SERVER_HELLO_RANDOM_LEN)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "f_rng", ret); return ret; } MBEDTLS_SSL_DEBUG_BUF(3, "server hello, random bytes", server_randbytes, MBEDTLS_SERVER_HELLO_RANDOM_LEN); #if defined(MBEDTLS_HAVE_TIME) ssl->session_negotiate->start = mbedtls_time(NULL); #endif /* MBEDTLS_HAVE_TIME */ return ret; } /* * ssl_tls13_write_server_hello_supported_versions_ext (): * * struct { * ProtocolVersion selected_version; * } SupportedVersions; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_server_hello_supported_versions_ext( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len) { *out_len = 0; MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, write selected version")); /* Check if we have space to write the extension: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - selected_version (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6); MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, buf, 0); MBEDTLS_PUT_UINT16_BE(2, buf, 2); mbedtls_ssl_write_version(buf + 4, ssl->conf->transport, ssl->tls_version); MBEDTLS_SSL_DEBUG_MSG(3, ("supported version: [%04x]", ssl->tls_version)); *out_len = 6; mbedtls_ssl_tls13_set_hs_sent_ext_mask( ssl, MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS); return 0; } /* Generate and export a single key share. For hybrid KEMs, this can * be called multiple times with the different components of the hybrid. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_generate_and_write_key_share(mbedtls_ssl_context *ssl, uint16_t named_group, unsigned char *buf, unsigned char *end, size_t *out_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; *out_len = 0; #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) if (mbedtls_ssl_tls13_named_group_is_ecdhe(named_group) || mbedtls_ssl_tls13_named_group_is_ffdh(named_group)) { ret = mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange( ssl, named_group, buf, end, out_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange", ret); return ret; } } else #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ if (0 /* Other kinds of KEMs */) { } else { ((void) ssl); ((void) named_group); ((void) buf); ((void) end); ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; } return ret; } /* * ssl_tls13_write_key_share_ext * * Structure of key_share extension in ServerHello: * * struct { * NamedGroup group; * opaque key_exchange<1..2^16-1>; * } KeyShareEntry; * struct { * KeyShareEntry server_share; * } KeyShareServerHello; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_key_share_ext(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *p = buf; uint16_t group = ssl->handshake->offered_group_id; unsigned char *server_share = buf + 4; size_t key_exchange_length; *out_len = 0; MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, adding key share extension")); MBEDTLS_SSL_DEBUG_MSG(2, ("server hello, write selected_group: %s (%04x)", mbedtls_ssl_named_group_to_str(group), group)); /* Check if we have space for header and length fields: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - group (2 bytes) * - key_exchange_length (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 8); MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, p, 0); MBEDTLS_PUT_UINT16_BE(group, server_share, 0); p += 8; /* When we introduce PQC-ECDHE hybrids, we'll want to call this * function multiple times. */ ret = ssl_tls13_generate_and_write_key_share( ssl, group, server_share + 4, end, &key_exchange_length); if (ret != 0) { return ret; } p += key_exchange_length; MBEDTLS_PUT_UINT16_BE(key_exchange_length, server_share + 2, 0); MBEDTLS_PUT_UINT16_BE(p - server_share, buf, 2); *out_len = p - buf; mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_hrr_key_share_ext(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len) { uint16_t selected_group = ssl->handshake->hrr_selected_group; /* key_share Extension * * struct { * select (Handshake.msg_type) { * ... * case hello_retry_request: * NamedGroup selected_group; * ... * }; * } KeyShare; */ *out_len = 0; /* * For a pure PSK key exchange, there is no group to agree upon. The purpose * of the HRR is then to transmit a cookie to force the client to demonstrate * reachability at their apparent network address (primarily useful for DTLS). */ if (!mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) { return 0; } /* We should only send the key_share extension if the client's initial * key share was not acceptable. */ if (ssl->handshake->offered_group_id != 0) { MBEDTLS_SSL_DEBUG_MSG(4, ("Skip key_share extension in HRR")); return 0; } if (selected_group == 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("no matching named group found")); return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } /* Check if we have enough space: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - selected_group (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6); MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, buf, 0); MBEDTLS_PUT_UINT16_BE(2, buf, 2); MBEDTLS_PUT_UINT16_BE(selected_group, buf, 4); MBEDTLS_SSL_DEBUG_MSG(3, ("HRR selected_group: %s (%x)", mbedtls_ssl_named_group_to_str(selected_group), selected_group)); *out_len = 6; mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); return 0; } /* * Structure of ServerHello message: * * struct { * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 * Random random; * opaque legacy_session_id_echo<0..32>; * CipherSuite cipher_suite; * uint8 legacy_compression_method = 0; * Extension extensions<6..2^16-1>; * } ServerHello; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_server_hello_body(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len, int is_hrr) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *p = buf; unsigned char *p_extensions_len; size_t output_len; *out_len = 0; ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; /* ... * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 * ... * with ProtocolVersion defined as: * uint16 ProtocolVersion; */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); MBEDTLS_PUT_UINT16_BE(0x0303, p, 0); p += 2; /* ... * Random random; * ... * with Random defined as: * opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN]; */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN); if (is_hrr) { memcpy(p, mbedtls_ssl_tls13_hello_retry_request_magic, MBEDTLS_SERVER_HELLO_RANDOM_LEN); } else { memcpy(p, &ssl->handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN], MBEDTLS_SERVER_HELLO_RANDOM_LEN); } MBEDTLS_SSL_DEBUG_BUF(3, "server hello, random bytes", p, MBEDTLS_SERVER_HELLO_RANDOM_LEN); p += MBEDTLS_SERVER_HELLO_RANDOM_LEN; /* ... * opaque legacy_session_id_echo<0..32>; * ... */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1 + ssl->session_negotiate->id_len); *p++ = (unsigned char) ssl->session_negotiate->id_len; if (ssl->session_negotiate->id_len > 0) { memcpy(p, &ssl->session_negotiate->id[0], ssl->session_negotiate->id_len); p += ssl->session_negotiate->id_len; MBEDTLS_SSL_DEBUG_BUF(3, "session id", ssl->session_negotiate->id, ssl->session_negotiate->id_len); } /* ... * CipherSuite cipher_suite; * ... * with CipherSuite defined as: * uint8 CipherSuite[2]; */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); MBEDTLS_PUT_UINT16_BE(ssl->session_negotiate->ciphersuite, p, 0); p += 2; MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, chosen ciphersuite: %s ( id=%d )", mbedtls_ssl_get_ciphersuite_name( ssl->session_negotiate->ciphersuite), ssl->session_negotiate->ciphersuite)); /* ... * uint8 legacy_compression_method = 0; * ... */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1); *p++ = MBEDTLS_SSL_COMPRESS_NULL; /* ... * Extension extensions<6..2^16-1>; * ... * struct { * ExtensionType extension_type; (2 bytes) * opaque extension_data<0..2^16-1>; * } Extension; */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); p_extensions_len = p; p += 2; if ((ret = ssl_tls13_write_server_hello_supported_versions_ext( ssl, p, end, &output_len)) != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_server_hello_supported_versions_ext", ret); return ret; } p += output_len; if (mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) { if (is_hrr) { ret = ssl_tls13_write_hrr_key_share_ext(ssl, p, end, &output_len); } else { ret = ssl_tls13_write_key_share_ext(ssl, p, end, &output_len); } if (ret != 0) { return ret; } p += output_len; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) if (!is_hrr && mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) { ret = ssl_tls13_write_server_pre_shared_key_ext(ssl, p, end, &output_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_server_pre_shared_key_ext", ret); return ret; } p += output_len; } #endif MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); MBEDTLS_SSL_DEBUG_BUF(4, "server hello extensions", p_extensions_len, p - p_extensions_len); *out_len = p - buf; MBEDTLS_SSL_DEBUG_BUF(3, "server hello", buf, *out_len); MBEDTLS_SSL_PRINT_EXTS( 3, is_hrr ? MBEDTLS_SSL_TLS1_3_HS_HELLO_RETRY_REQUEST : MBEDTLS_SSL_HS_SERVER_HELLO, ssl->handshake->sent_extensions); return ret; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_finalize_server_hello(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ret = mbedtls_ssl_tls13_compute_handshake_transform(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_tls13_compute_handshake_transform", ret); return ret; } return ret; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_server_hello(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf; size_t buf_len, msg_len; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write server hello")); MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_server_hello(ssl)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len)); MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_server_hello_body(ssl, buf, buf + buf_len, &msg_len, 0)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( ssl, buf_len, msg_len)); MBEDTLS_SSL_PROC_CHK(ssl_tls13_finalize_server_hello(ssl)); #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) /* The server sends a dummy change_cipher_spec record immediately * after its first handshake message. This may either be after * a ServerHello or a HelloRetryRequest. */ mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO); #else mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= write server hello")); return ret; } /* * Handler for MBEDTLS_SSL_HELLO_RETRY_REQUEST */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_prepare_hello_retry_request(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; if (ssl->handshake->hello_retry_request_flag) { MBEDTLS_SSL_DEBUG_MSG(1, ("Too many HRRs")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } /* * Create stateless transcript hash for HRR */ MBEDTLS_SSL_DEBUG_MSG(4, ("Reset transcript for HRR")); ret = mbedtls_ssl_reset_transcript_for_hrr(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_reset_transcript_for_hrr", ret); return ret; } mbedtls_ssl_session_reset_msg_layer(ssl, 0); return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_hello_retry_request(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf; size_t buf_len, msg_len; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write hello retry request")); MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_hello_retry_request(ssl)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len)); MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_server_hello_body(ssl, buf, buf + buf_len, &msg_len, 1)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(ssl, buf_len, msg_len)); ssl->handshake->hello_retry_request_flag = 1; #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) /* The server sends a dummy change_cipher_spec record immediately * after its first handshake message. This may either be after * a ServerHello or a HelloRetryRequest. */ mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST); #else mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= write hello retry request")); return ret; } /* * Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS */ /* * struct { * Extension extensions<0..2 ^ 16 - 1>; * } EncryptedExtensions; * */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_encrypted_extensions_body(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *p = buf; size_t extensions_len = 0; unsigned char *p_extensions_len; size_t output_len; *out_len = 0; MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); p_extensions_len = p; p += 2; ((void) ssl); ((void) ret); ((void) output_len); #if defined(MBEDTLS_SSL_ALPN) ret = mbedtls_ssl_write_alpn_ext(ssl, p, end, &output_len); if (ret != 0) { return ret; } p += output_len; #endif /* MBEDTLS_SSL_ALPN */ #if defined(MBEDTLS_SSL_EARLY_DATA) if (ssl->handshake->early_data_accepted) { ret = mbedtls_ssl_tls13_write_early_data_ext( ssl, 0, p, end, &output_len); if (ret != 0) { return ret; } p += output_len; } #endif /* MBEDTLS_SSL_EARLY_DATA */ #if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(RECORD_SIZE_LIMIT)) { ret = mbedtls_ssl_tls13_write_record_size_limit_ext( ssl, p, end, &output_len); if (ret != 0) { return ret; } p += output_len; } #endif extensions_len = (p - p_extensions_len) - 2; MBEDTLS_PUT_UINT16_BE(extensions_len, p_extensions_len, 0); *out_len = p - buf; MBEDTLS_SSL_DEBUG_BUF(4, "encrypted extensions", buf, *out_len); MBEDTLS_SSL_PRINT_EXTS( 3, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, ssl->handshake->sent_extensions); return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_encrypted_extensions(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf; size_t buf_len, msg_len; mbedtls_ssl_set_outbound_transform(ssl, ssl->handshake->transform_handshake); MBEDTLS_SSL_DEBUG_MSG( 3, ("switching to handshake transform for outbound data")); MBEDTLS_SSL_DEBUG_MSG(2, ("=> write encrypted extensions")); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, &buf, &buf_len)); MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_encrypted_extensions_body( ssl, buf, buf + buf_len, &msg_len)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, msg_len)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( ssl, buf_len, msg_len)); #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) if (mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); } else { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CERTIFICATE_REQUEST); } #else mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); #endif cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= write encrypted extensions")); return ret; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) #define SSL_CERTIFICATE_REQUEST_SEND_REQUEST … #define SSL_CERTIFICATE_REQUEST_SKIP … /* Coordination: * Check whether a CertificateRequest message should be written. * Returns a negative code on failure, or * - SSL_CERTIFICATE_REQUEST_SEND_REQUEST * - SSL_CERTIFICATE_REQUEST_SKIP * indicating if the writing of the CertificateRequest * should be skipped or not. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_certificate_request_coordinate(mbedtls_ssl_context *ssl) { int authmode; #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) if (ssl->handshake->sni_authmode != MBEDTLS_SSL_VERIFY_UNSET) { authmode = ssl->handshake->sni_authmode; } else #endif authmode = ssl->conf->authmode; if (authmode == MBEDTLS_SSL_VERIFY_NONE) { ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_SKIP_VERIFY; return SSL_CERTIFICATE_REQUEST_SKIP; } ssl->handshake->certificate_request_sent = 1; return SSL_CERTIFICATE_REQUEST_SEND_REQUEST; } /* * struct { * opaque certificate_request_context<0..2^8-1>; * Extension extensions<2..2^16-1>; * } CertificateRequest; * */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_certificate_request_body(mbedtls_ssl_context *ssl, unsigned char *buf, const unsigned char *end, size_t *out_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *p = buf; size_t output_len = 0; unsigned char *p_extensions_len; *out_len = 0; /* Check if we have enough space: * - certificate_request_context (1 byte) * - extensions length (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 3); /* * Write certificate_request_context */ /* * We use a zero length context for the normal handshake * messages. For post-authentication handshake messages * this request context would be set to a non-zero value. */ *p++ = 0x0; /* * Write extensions */ /* The extensions must contain the signature_algorithms. */ p_extensions_len = p; p += 2; ret = mbedtls_ssl_write_sig_alg_ext(ssl, p, end, &output_len); if (ret != 0) { return ret; } p += output_len; MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); *out_len = p - buf; MBEDTLS_SSL_PRINT_EXTS( 3, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, ssl->handshake->sent_extensions); return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_certificate_request(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write certificate request")); MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_certificate_request_coordinate(ssl)); if (ret == SSL_CERTIFICATE_REQUEST_SEND_REQUEST) { unsigned char *buf; size_t buf_len, msg_len; MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, &buf, &buf_len)); MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_certificate_request_body( ssl, buf, buf + buf_len, &msg_len)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, buf, msg_len)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( ssl, buf_len, msg_len)); } else if (ret == SSL_CERTIFICATE_REQUEST_SKIP) { MBEDTLS_SSL_DEBUG_MSG(2, ("<= skip write certificate request")); ret = 0; } else { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; goto cleanup; } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_CERTIFICATE); cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= write certificate request")); return ret; } /* * Handler for MBEDTLS_SSL_SERVER_CERTIFICATE */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_server_certificate(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; #if defined(MBEDTLS_X509_CRT_PARSE_C) if ((ssl_tls13_pick_key_cert(ssl) != 0) || mbedtls_ssl_own_cert(ssl) == NULL) { MBEDTLS_SSL_DEBUG_MSG(2, ("No certificate available.")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } #endif /* MBEDTLS_X509_CRT_PARSE_C */ ret = mbedtls_ssl_tls13_write_certificate(ssl); if (ret != 0) { return ret; } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CERTIFICATE_VERIFY); return 0; } /* * Handler for MBEDTLS_SSL_CERTIFICATE_VERIFY */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_certificate_verify(mbedtls_ssl_context *ssl) { int ret = mbedtls_ssl_tls13_write_certificate_verify(ssl); if (ret != 0) { return ret; } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); return 0; } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ /* * RFC 8446 section A.2 * * | Send ServerHello * | K_send = handshake * | Send EncryptedExtensions * | [Send CertificateRequest] * Can send | [Send Certificate + CertificateVerify] * app data | Send Finished * after --> | K_send = application * here +--------+--------+ * No 0-RTT | | 0-RTT * | | * K_recv = handshake | | K_recv = early data * [Skip decrypt errors] | +------> WAIT_EOED -+ * | | Recv | | Recv EndOfEarlyData * | | early data | | K_recv = handshake * | +------------+ | * | | * +> WAIT_FLIGHT2 <--------+ * | * +--------+--------+ * No auth | | Client auth * | | * | v * | WAIT_CERT * | Recv | | Recv Certificate * | empty | v * | Certificate | WAIT_CV * | | | Recv * | v | CertificateVerify * +-> WAIT_FINISHED <---+ * | Recv Finished * * * The following function handles the state changes after WAIT_FLIGHT2 in the * above diagram. We are not going to receive early data related messages * anymore, prepare to receive the first handshake message of the client * second flight. */ static void ssl_tls13_prepare_for_handshake_second_flight( mbedtls_ssl_context *ssl) { if (ssl->handshake->certificate_request_sent) { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE); } else { MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate")); MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate verify")); mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_FINISHED); } } /* * Handler for MBEDTLS_SSL_SERVER_FINISHED */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_server_finished(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ret = mbedtls_ssl_tls13_write_finished_message(ssl); if (ret != 0) { return ret; } ret = mbedtls_ssl_tls13_compute_application_transform(ssl); if (ret != 0) { MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); return ret; } #if defined(MBEDTLS_SSL_EARLY_DATA) if (ssl->handshake->early_data_accepted) { /* See RFC 8446 section A.2 for more information */ MBEDTLS_SSL_DEBUG_MSG( 1, ("Switch to early keys for inbound traffic. " "( K_recv = early data )")); mbedtls_ssl_set_inbound_transform( ssl, ssl->handshake->transform_earlydata); mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_END_OF_EARLY_DATA); return 0; } #endif /* MBEDTLS_SSL_EARLY_DATA */ MBEDTLS_SSL_DEBUG_MSG( 1, ("Switch to handshake keys for inbound traffic " "( K_recv = handshake )")); mbedtls_ssl_set_inbound_transform(ssl, ssl->handshake->transform_handshake); ssl_tls13_prepare_for_handshake_second_flight(ssl); return 0; } #if defined(MBEDTLS_SSL_EARLY_DATA) /* * Handler for MBEDTLS_SSL_END_OF_EARLY_DATA */ #define SSL_GOT_END_OF_EARLY_DATA … #define SSL_GOT_EARLY_DATA … /* Coordination: * Deals with the ambiguity of not knowing if the next message is an * EndOfEarlyData message or an application message containing early data. * Returns a negative code on failure, or * - SSL_GOT_END_OF_EARLY_DATA * - SSL_GOT_EARLY_DATA * indicating which message is received. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_end_of_early_data_coordinate(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; if ((ret = mbedtls_ssl_read_record(ssl, 0)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); return ret; } ssl->keep_current_message = 1; if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && ssl->in_msg[0] == MBEDTLS_SSL_HS_END_OF_EARLY_DATA) { MBEDTLS_SSL_DEBUG_MSG(3, ("Received an end_of_early_data message.")); return SSL_GOT_END_OF_EARLY_DATA; } if (ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA) { if (ssl->in_offt == NULL) { MBEDTLS_SSL_DEBUG_MSG(3, ("Received early data")); /* Set the reading pointer */ ssl->in_offt = ssl->in_msg; ret = mbedtls_ssl_tls13_check_early_data_len(ssl, ssl->in_msglen); if (ret != 0) { return ret; } } return SSL_GOT_EARLY_DATA; } MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE, MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE); return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_end_of_early_data(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { /* RFC 8446 section 4.5 * * struct {} EndOfEarlyData; */ if (buf != end) { MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR); return MBEDTLS_ERR_SSL_DECODE_ERROR; } return 0; } /* * RFC 8446 section A.2 * * | Send ServerHello * | K_send = handshake * | Send EncryptedExtensions * | [Send CertificateRequest] * Can send | [Send Certificate + CertificateVerify] * app data | Send Finished * after --> | K_send = application * here +--------+--------+ * No 0-RTT | | 0-RTT * | | * K_recv = handshake | | K_recv = early data * [Skip decrypt errors] | +------> WAIT_EOED -+ * | | Recv | | Recv EndOfEarlyData * | | early data | | K_recv = handshake * | +------------+ | * | | * +> WAIT_FLIGHT2 <--------+ * | * +--------+--------+ * No auth | | Client auth * | | * | v * | WAIT_CERT * | Recv | | Recv Certificate * | empty | v * | Certificate | WAIT_CV * | | | Recv * | v | CertificateVerify * +-> WAIT_FINISHED <---+ * | Recv Finished * * The function handles actions and state changes from 0-RTT to WAIT_FLIGHT2 in * the above diagram. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_end_of_early_data(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_tls13_process_end_of_early_data")); MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_end_of_early_data_coordinate(ssl)); if (ret == SSL_GOT_END_OF_EARLY_DATA) { unsigned char *buf; size_t buf_len; MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, &buf, &buf_len)); MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_end_of_early_data( ssl, buf, buf + buf_len)); MBEDTLS_SSL_DEBUG_MSG( 1, ("Switch to handshake keys for inbound traffic" "( K_recv = handshake )")); mbedtls_ssl_set_inbound_transform( ssl, ssl->handshake->transform_handshake); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, buf, buf_len)); ssl_tls13_prepare_for_handshake_second_flight(ssl); } else if (ret == SSL_GOT_EARLY_DATA) { ret = MBEDTLS_ERR_SSL_RECEIVED_EARLY_DATA; goto cleanup; } else { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; goto cleanup; } cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_tls13_process_end_of_early_data")); return ret; } #endif /* MBEDTLS_SSL_EARLY_DATA */ /* * Handler for MBEDTLS_SSL_CLIENT_FINISHED */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_client_finished(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; ret = mbedtls_ssl_tls13_process_finished_message(ssl); if (ret != 0) { return ret; } ret = mbedtls_ssl_tls13_compute_resumption_master_secret(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_compute_resumption_master_secret", ret); } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_WRAPUP); return 0; } /* * Handler for MBEDTLS_SSL_HANDSHAKE_WRAPUP */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_handshake_wrapup(mbedtls_ssl_context *ssl) { MBEDTLS_SSL_DEBUG_MSG(2, ("handshake: done")); mbedtls_ssl_tls13_handshake_wrapup(ssl); #if defined(MBEDTLS_SSL_SESSION_TICKETS) && \ defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) /* TODO: Remove the check of SOME_PSK_ENABLED since SESSION_TICKETS requires * SOME_PSK_ENABLED to be enabled. Here is just to make CI happy. It is * expected to be resolved with issue#6395. */ /* Sent NewSessionTicket message only when client supports PSK */ if (mbedtls_ssl_tls13_is_some_psk_supported(ssl)) { mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); } else #endif { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); } return 0; } #if defined(MBEDTLS_SSL_SESSION_TICKETS) /* * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET */ #define SSL_NEW_SESSION_TICKET_SKIP … #define SSL_NEW_SESSION_TICKET_WRITE … MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_new_session_ticket_coordinate(mbedtls_ssl_context *ssl) { /* Check whether the use of session tickets is enabled */ if (ssl->conf->f_ticket_write == NULL) { MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: disabled," " callback is not set")); return SSL_NEW_SESSION_TICKET_SKIP; } if (ssl->conf->new_session_tickets_count == 0) { MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: disabled," " configured count is zero")); return SSL_NEW_SESSION_TICKET_SKIP; } if (ssl->handshake->new_session_tickets_count == 0) { MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: all tickets have " "been sent.")); return SSL_NEW_SESSION_TICKET_SKIP; } return SSL_NEW_SESSION_TICKET_WRITE; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_prepare_new_session_ticket(mbedtls_ssl_context *ssl, unsigned char *ticket_nonce, size_t ticket_nonce_size) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_session *session = ssl->session; mbedtls_ssl_ciphersuite_t *ciphersuite_info; psa_algorithm_t psa_hash_alg; int hash_length; MBEDTLS_SSL_DEBUG_MSG(2, ("=> prepare NewSessionTicket msg")); /* Set ticket_flags depends on the advertised psk key exchange mode */ mbedtls_ssl_tls13_session_clear_ticket_flags( session, MBEDTLS_SSL_TLS1_3_TICKET_FLAGS_MASK); #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) mbedtls_ssl_tls13_session_set_ticket_flags( session, ssl->handshake->tls13_kex_modes); #endif #if defined(MBEDTLS_SSL_EARLY_DATA) if (ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_ENABLED && ssl->conf->max_early_data_size > 0) { mbedtls_ssl_tls13_session_set_ticket_flags( session, MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA); session->max_early_data_size = ssl->conf->max_early_data_size; } #endif /* MBEDTLS_SSL_EARLY_DATA */ MBEDTLS_SSL_PRINT_TICKET_FLAGS(4, session->ticket_flags); #if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN) if (session->ticket_alpn == NULL) { ret = mbedtls_ssl_session_set_ticket_alpn(session, ssl->alpn_chosen); if (ret != 0) { return ret; } } #endif /* Generate ticket_age_add */ if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, (unsigned char *) &session->ticket_age_add, sizeof(session->ticket_age_add)) != 0)) { MBEDTLS_SSL_DEBUG_RET(1, "generate_ticket_age_add", ret); return ret; } MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", (unsigned int) session->ticket_age_add)); /* Generate ticket_nonce */ ret = ssl->conf->f_rng(ssl->conf->p_rng, ticket_nonce, ticket_nonce_size); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "generate_ticket_nonce", ret); return ret; } MBEDTLS_SSL_DEBUG_BUF(3, "ticket_nonce:", ticket_nonce, ticket_nonce_size); ciphersuite_info = (mbedtls_ssl_ciphersuite_t *) ssl->handshake->ciphersuite_info; psa_hash_alg = mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) ciphersuite_info->mac); hash_length = PSA_HASH_LENGTH(psa_hash_alg); if (hash_length == -1 || (size_t) hash_length > sizeof(session->resumption_key)) { return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* In this code the psk key length equals the length of the hash */ session->resumption_key_len = hash_length; session->ciphersuite = ciphersuite_info->id; /* Compute resumption key * * HKDF-Expand-Label( resumption_master_secret, * "resumption", ticket_nonce, Hash.length ) */ ret = mbedtls_ssl_tls13_hkdf_expand_label( psa_hash_alg, session->app_secrets.resumption_master_secret, hash_length, MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN(resumption), ticket_nonce, ticket_nonce_size, session->resumption_key, hash_length); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(2, "Creating the ticket-resumed PSK failed", ret); return ret; } MBEDTLS_SSL_DEBUG_BUF(3, "Ticket-resumed PSK", session->resumption_key, session->resumption_key_len); MBEDTLS_SSL_DEBUG_BUF(3, "resumption_master_secret", session->app_secrets.resumption_master_secret, hash_length); return 0; } /* This function creates a NewSessionTicket message in the following format: * * struct { * uint32 ticket_lifetime; * uint32 ticket_age_add; * opaque ticket_nonce<0..255>; * opaque ticket<1..2^16-1>; * Extension extensions<0..2^16-2>; * } NewSessionTicket; * * The ticket inside the NewSessionTicket message is an encrypted container * carrying the necessary information so that the server is later able to * re-start the communication. * * The following fields are placed inside the ticket by the * f_ticket_write() function: * * - creation time (ticket_creation_time) * - flags (ticket_flags) * - age add (ticket_age_add) * - key (resumption_key) * - key length (resumption_key_len) * - ciphersuite (ciphersuite) * - max_early_data_size (max_early_data_size) */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_new_session_ticket_body(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len, unsigned char *ticket_nonce, size_t ticket_nonce_size) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *p = buf; mbedtls_ssl_session *session = ssl->session; size_t ticket_len; uint32_t ticket_lifetime; unsigned char *p_extensions_len; *out_len = 0; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write NewSessionTicket msg")); /* * ticket_lifetime 4 bytes * ticket_age_add 4 bytes * ticket_nonce 1 + ticket_nonce_size bytes * ticket >=2 bytes */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 4 + 4 + 1 + ticket_nonce_size + 2); /* Generate ticket and ticket_lifetime */ #if defined(MBEDTLS_HAVE_TIME) session->ticket_creation_time = mbedtls_ms_time(); #endif ret = ssl->conf->f_ticket_write(ssl->conf->p_ticket, session, p + 9 + ticket_nonce_size + 2, end, &ticket_len, &ticket_lifetime); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "write_ticket", ret); return ret; } /* RFC 8446 section 4.6.1 * * ticket_lifetime: Indicates the lifetime in seconds as a 32-bit * unsigned integer in network byte order from the time of ticket * issuance. Servers MUST NOT use any value greater than * 604800 seconds (7 days) ... */ if (ticket_lifetime > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME) { MBEDTLS_SSL_DEBUG_MSG( 1, ("Ticket lifetime (%u) is greater than 7 days.", (unsigned int) ticket_lifetime)); return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } MBEDTLS_PUT_UINT32_BE(ticket_lifetime, p, 0); MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_lifetime: %u", (unsigned int) ticket_lifetime)); /* Write ticket_age_add */ MBEDTLS_PUT_UINT32_BE(session->ticket_age_add, p, 4); MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", (unsigned int) session->ticket_age_add)); /* Write ticket_nonce */ p[8] = (unsigned char) ticket_nonce_size; if (ticket_nonce_size > 0) { memcpy(p + 9, ticket_nonce, ticket_nonce_size); } p += 9 + ticket_nonce_size; /* Write ticket */ MBEDTLS_PUT_UINT16_BE(ticket_len, p, 0); p += 2; MBEDTLS_SSL_DEBUG_BUF(4, "ticket", p, ticket_len); p += ticket_len; /* Ticket Extensions * * Extension extensions<0..2^16-2>; */ ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); p_extensions_len = p; p += 2; #if defined(MBEDTLS_SSL_EARLY_DATA) if (mbedtls_ssl_tls13_session_ticket_allow_early_data(session)) { size_t output_len; if ((ret = mbedtls_ssl_tls13_write_early_data_ext( ssl, 1, p, end, &output_len)) != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_write_early_data_ext", ret); return ret; } p += output_len; } else { MBEDTLS_SSL_DEBUG_MSG( 4, ("early_data not allowed, " "skip early_data extension in NewSessionTicket")); } #endif /* MBEDTLS_SSL_EARLY_DATA */ MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); *out_len = p - buf; MBEDTLS_SSL_DEBUG_BUF(4, "ticket", buf, *out_len); MBEDTLS_SSL_DEBUG_MSG(2, ("<= write new session ticket")); MBEDTLS_SSL_PRINT_EXTS( 3, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, ssl->handshake->sent_extensions); return 0; } /* * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET */ static int ssl_tls13_write_new_session_ticket(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_write_new_session_ticket_coordinate(ssl)); if (ret == SSL_NEW_SESSION_TICKET_WRITE) { unsigned char ticket_nonce[MBEDTLS_SSL_TLS1_3_TICKET_NONCE_LENGTH]; unsigned char *buf; size_t buf_len, msg_len; MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_new_session_ticket( ssl, ticket_nonce, sizeof(ticket_nonce))); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( ssl, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, &buf, &buf_len)); MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_new_session_ticket_body( ssl, buf, buf + buf_len, &msg_len, ticket_nonce, sizeof(ticket_nonce))); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( ssl, buf_len, msg_len)); /* Limit session tickets count to one when resumption connection. * * See document of mbedtls_ssl_conf_new_session_tickets. */ if (ssl->handshake->resume == 1) { ssl->handshake->new_session_tickets_count = 0; } else { ssl->handshake->new_session_tickets_count--; } mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET_FLUSH); } else { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); } cleanup: return ret; } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ /* * TLS 1.3 State Machine -- server side */ int mbedtls_ssl_tls13_handshake_server_step(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; if (ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL) { return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } MBEDTLS_SSL_DEBUG_MSG(2, ("tls13 server state: %s(%d)", mbedtls_ssl_states_str((mbedtls_ssl_states) ssl->state), ssl->state)); switch (ssl->state) { /* start state */ case MBEDTLS_SSL_HELLO_REQUEST: mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); ret = 0; break; case MBEDTLS_SSL_CLIENT_HELLO: ret = ssl_tls13_process_client_hello(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_process_client_hello", ret); } break; case MBEDTLS_SSL_HELLO_RETRY_REQUEST: ret = ssl_tls13_write_hello_retry_request(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_hello_retry_request", ret); return ret; } break; case MBEDTLS_SSL_SERVER_HELLO: ret = ssl_tls13_write_server_hello(ssl); break; case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS: ret = ssl_tls13_write_encrypted_extensions(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_encrypted_extensions", ret); return ret; } break; #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) case MBEDTLS_SSL_CERTIFICATE_REQUEST: ret = ssl_tls13_write_certificate_request(ssl); break; case MBEDTLS_SSL_SERVER_CERTIFICATE: ret = ssl_tls13_write_server_certificate(ssl); break; case MBEDTLS_SSL_CERTIFICATE_VERIFY: ret = ssl_tls13_write_certificate_verify(ssl); break; #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ /* * Injection of dummy-CCS's for middlebox compatibility */ #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) case MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST: ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); if (ret == 0) { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); } break; case MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO: ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); if (ret != 0) { break; } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); break; #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ case MBEDTLS_SSL_SERVER_FINISHED: ret = ssl_tls13_write_server_finished(ssl); break; #if defined(MBEDTLS_SSL_EARLY_DATA) case MBEDTLS_SSL_END_OF_EARLY_DATA: ret = ssl_tls13_process_end_of_early_data(ssl); break; #endif /* MBEDTLS_SSL_EARLY_DATA */ case MBEDTLS_SSL_CLIENT_FINISHED: ret = ssl_tls13_process_client_finished(ssl); break; case MBEDTLS_SSL_HANDSHAKE_WRAPUP: ret = ssl_tls13_handshake_wrapup(ssl); break; #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) case MBEDTLS_SSL_CLIENT_CERTIFICATE: ret = mbedtls_ssl_tls13_process_certificate(ssl); if (ret == 0) { if (ssl->session_negotiate->peer_cert != NULL) { mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY); } else { MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate verify")); mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_FINISHED); } } break; case MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY: ret = mbedtls_ssl_tls13_process_certificate_verify(ssl); if (ret == 0) { mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_FINISHED); } break; #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ #if defined(MBEDTLS_SSL_SESSION_TICKETS) case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET: ret = ssl_tls13_write_new_session_ticket(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_new_session_ticket ", ret); } break; case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET_FLUSH: /* This state is necessary to do the flush of the New Session * Ticket message written in MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET * as part of ssl_prepare_handshake_step. */ ret = 0; if (ssl->handshake->new_session_tickets_count == 0) { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); } else { mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); } break; #endif /* MBEDTLS_SSL_SESSION_TICKETS */ default: MBEDTLS_SSL_DEBUG_MSG(1, ("invalid state %d", ssl->state)); return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; } return ret; } #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_TLS1_3 */
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