/* * TLS 1.3 server-side functions * * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "common.h" #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3) #include "mbedtls/debug.h" #include "mbedtls/error.h" #include "mbedtls/platform.h" #include "mbedtls/constant_time.h" #include "ssl_misc.h" #include "ssl_tls13_keys.h" #include "ssl_debug_helpers.h" #if defined(MBEDTLS_ECP_C) #include "mbedtls/ecp.h" #endif /* MBEDTLS_ECP_C */ #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include #define mbedtls_calloc calloc #define mbedtls_free free #endif /* MBEDTLS_PLATFORM_C */ #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 ); } #if defined(MBEDTLS_KEY_EXCHANGE_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 ); } #define SSL_TLS1_3_OFFERED_PSK_NOT_MATCH 1 #define SSL_TLS1_3_OFFERED_PSK_MATCH 0 #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_time_t now; uint64_t age_in_s; int64_t age_diff_in_ms; #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( 0 ); /* 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 ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "buffer too small" ) ); return ( MBEDTLS_ERR_SSL_ALLOC_FAILED ); } memcpy( ticket_buffer, identity, identity_len ); if( ( ret = ssl->conf->f_ticket_parse( ssl->conf->p_ticket, session, ticket_buffer, identity_len ) ) != 0 ) { if( ret == MBEDTLS_ERR_SSL_INVALID_MAC ) MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket is not authentic" ) ); else if( ret == MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED ) MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket is expired" ) ); else MBEDTLS_SSL_DEBUG_RET( 1, "ticket_parse", ret ); } /* We delete the temporary buffer */ mbedtls_free( ticket_buffer ); if( ret != 0 ) goto exit; ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED; #if defined(MBEDTLS_HAVE_TIME) now = mbedtls_time( NULL ); if( now < session->start ) { MBEDTLS_SSL_DEBUG_MSG( 3, ( "Ticket expired: now=%" MBEDTLS_PRINTF_LONGLONG ", start=%" MBEDTLS_PRINTF_LONGLONG, (long long)now, (long long)session->start ) ); goto exit; } age_in_s = (uint64_t)( now - session->start ); /* 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. * * For time being, the age MUST be less than 604800 seconds (7 days). */ if( age_in_s > 604800 ) { MBEDTLS_SSL_DEBUG_MSG( 3, ( "Ticket expired: Ticket age exceed limitation ticket_age=%lu", (long unsigned int)age_in_s ) ); 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: When `now == session->start`, `age_diff_in_ms` may be negative * as the age units are different on the server (s) and in the * client (ms) side. Add a -1000 ms tolerance window to take this * into account. */ age_diff_in_ms = age_in_s * 1000; age_diff_in_ms -= ( obfuscated_ticket_age - session->ticket_age_add ); if( age_diff_in_ms <= -1000 || age_diff_in_ms > MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE ) { MBEDTLS_SSL_DEBUG_MSG( 3, ( "Ticket expired: Ticket age outside tolerance window " "( diff=%d )", (int)age_diff_in_ms ) ); goto exit; } ret = 0; #endif /* MBEDTLS_HAVE_TIME */ exit: if( ret != 0 ) 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 ) { ((void) session); ((void) obfuscated_ticket_age); *psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL; MBEDTLS_SSL_DEBUG_BUF( 4, "identity", identity, identity_len ); ssl->handshake->resume = 0; #if defined(MBEDTLS_SSL_SESSION_TICKETS) if( ssl_tls13_offered_psks_check_identity_match_ticket( ssl, identity, identity_len, obfuscated_ticket_age, session ) == SSL_TLS1_3_OFFERED_PSK_MATCH ) { ssl->handshake->resume = 1; *psk_type = MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION; mbedtls_ssl_set_hs_psk( ssl, session->resumption_key, session->resumption_key_len ); 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_OFFERED_PSK_MATCH ); } #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_OFFERED_PSK_MATCH ); } return( SSL_TLS1_3_OFFERED_PSK_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 ) { mbedtls_ssl_set_hs_psk( ssl, ssl->conf->psk, ssl->conf->psk_len ); return( SSL_TLS1_3_OFFERED_PSK_MATCH ); } return( SSL_TLS1_3_OFFERED_PSK_NOT_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]; /* Get current state of handshake transcript. */ ret = mbedtls_ssl_get_handshake_transcript( ssl, mbedtls_hash_info_md_from_psa( 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, binder_len ) == 0 ) { return( SSL_TLS1_3_OFFERED_PSK_MATCH ); } mbedtls_platform_zeroize( server_computed_binder, sizeof( server_computed_binder ) ); return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH ); } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_select_ciphersuite_for_psk( mbedtls_ssl_context *ssl, const unsigned char *cipher_suites, const unsigned char *cipher_suites_end, uint16_t *selected_ciphersuite, const mbedtls_ssl_ciphersuite_t **selected_ciphersuite_info ) { psa_algorithm_t psk_hash_alg = PSA_ALG_SHA_256; *selected_ciphersuite = 0; *selected_ciphersuite_info = NULL; /* RFC 8446, page 55. * * For externally established PSKs, the Hash algorithm MUST be set when the * PSK is established or default to SHA-256 if no such algorithm is defined. * */ /* * Search for a matching ciphersuite */ for ( const unsigned char *p = cipher_suites; p < cipher_suites_end; p += 2 ) { uint16_t cipher_suite; const mbedtls_ssl_ciphersuite_t *ciphersuite_info; cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 ); ciphersuite_info = ssl_tls13_validate_peer_ciphersuite( ssl, cipher_suite ); if( ciphersuite_info == NULL ) continue; /* MAC of selected ciphersuite MUST be same with PSK binder if exist. * Otherwise, client should reject. */ if( psk_hash_alg == mbedtls_psa_translate_md( ciphersuite_info->mac ) ) { *selected_ciphersuite = cipher_suite; *selected_ciphersuite_info = ciphersuite_info; return( 0 ); } } MBEDTLS_SSL_DEBUG_MSG( 2, ( "No matched ciphersuite" ) ); return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } #if defined(MBEDTLS_SSL_SESSION_TICKETS) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_select_ciphersuite_for_resumption( mbedtls_ssl_context *ssl, const unsigned char *cipher_suites, const unsigned char *cipher_suites_end, mbedtls_ssl_session *session, uint16_t *selected_ciphersuite, const mbedtls_ssl_ciphersuite_t **selected_ciphersuite_info ) { *selected_ciphersuite = 0; *selected_ciphersuite_info = NULL; for( const unsigned char *p = cipher_suites; p < cipher_suites_end; p += 2 ) { uint16_t cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 ); const mbedtls_ssl_ciphersuite_t *ciphersuite_info; if( cipher_suite != session->ciphersuite ) continue; ciphersuite_info = ssl_tls13_validate_peer_ciphersuite( ssl, cipher_suite ); if( ciphersuite_info == NULL ) continue; *selected_ciphersuite = cipher_suite; *selected_ciphersuite_info = ciphersuite_info; return( 0 ); } return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } 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 ); return( 0 ); } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ /* 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 ) { 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; ssl->handshake->update_checksum( ssl, pre_shared_key_ext, identities_end - pre_shared_key_ext ); 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 ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int psk_type; uint16_t cipher_suite; const mbedtls_ssl_ciphersuite_t *ciphersuite_info; #if defined(MBEDTLS_SSL_SESSION_TICKETS) mbedtls_ssl_session session; mbedtls_ssl_session_init( &session ); #endif 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_OFFERED_PSK_MATCH ) continue; MBEDTLS_SSL_DEBUG_MSG( 4, ( "found matched identity" ) ); switch( psk_type ) { case MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL: ret = ssl_tls13_select_ciphersuite_for_psk( ssl, ciphersuites, ciphersuites_end, &cipher_suite, &ciphersuite_info ); break; case MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION: #if defined(MBEDTLS_SSL_SESSION_TICKETS) ret = ssl_tls13_select_ciphersuite_for_resumption( ssl, ciphersuites, ciphersuites_end, &session, &cipher_suite, &ciphersuite_info ); if( ret != 0 ) mbedtls_ssl_session_free( &session ); #else ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; #endif break; default: return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); } if( ret != 0 ) { /* See below, no cipher_suite available, abort handshake */ MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); MBEDTLS_SSL_DEBUG_RET( 2, "ssl_tls13_select_ciphersuite", ret ); return( ret ); } ret = ssl_tls13_offered_psks_check_binder_match( ssl, binder, binder_len, psk_type, mbedtls_psa_translate_md( ciphersuite_info->mac ) ); if( ret != SSL_TLS1_3_OFFERED_PSK_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; /* Update handshake parameters */ ssl->handshake->ciphersuite_info = ciphersuite_info; ssl->session_negotiate->ciphersuite = cipher_suite; MBEDTLS_SSL_DEBUG_MSG( 2, ( "overwrite ciphersuite: %04x - %s", cipher_suite, ciphersuite_info->name ) ); #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 extesion 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. */ ssl->handshake->update_checksum( ssl, identities_end, (size_t)( binders_end - identities_end ) ); if( matched_identity == -1 ) { MBEDTLS_SSL_DEBUG_MSG( 3, ( "No matched 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; #if defined(MBEDTLS_USE_PSA_CRYPTO) if( mbedtls_svc_key_id_is_null( ssl->handshake->psk_opaque ) ) #else if( ssl->handshake->psk == NULL ) #endif { /* 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 ) ); return( 0 ); } #endif /* MBEDTLS_KEY_EXCHANGE_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 tls13_supported = 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; /* In this implementation we only support TLS 1.3 and DTLS 1.3. */ if( tls_version == MBEDTLS_SSL_VERSION_TLS1_3 ) { tls13_supported = 1; break; } } if( !tls13_supported ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS 1.3 is not supported by the client" ) ); 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. Supported is [%04x]", (unsigned int)tls_version ) ); return( 0 ); } #if defined(MBEDTLS_ECDH_C) /* * * 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 /* MBEDTLS_ECDH_C */ #define SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH 1 #if defined(MBEDTLS_ECDH_C) /* * 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; } /* * For now, we only support ECDHE groups. */ if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) ) { MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH group: %s (%04x)", mbedtls_ssl_named_group_to_str( group ), group ) ); ret = mbedtls_ssl_tls13_read_public_ecdhe_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_ECDH_C */ #if defined(MBEDTLS_DEBUG_C) static void ssl_tls13_debug_print_client_hello_exts( mbedtls_ssl_context *ssl ) { ((void) ssl); MBEDTLS_SSL_DEBUG_MSG( 3, ( "Supported Extensions:" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "- KEY_SHARE_EXTENSION ( %s )", ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_KEY_SHARE ) > 0 ) ? "TRUE" : "FALSE" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "- PSK_KEY_EXCHANGE_MODES_EXTENSION ( %s )", ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) > 0 ) ? "TRUE" : "FALSE" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "- PRE_SHARED_KEY_EXTENSION ( %s )", ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) > 0 ) ? "TRUE" : "FALSE" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "- SIGNATURE_ALGORITHM_EXTENSION ( %s )", ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_SIG_ALG ) > 0 ) ? "TRUE" : "FALSE" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "- SUPPORTED_GROUPS_EXTENSION ( %s )", ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_SUPPORTED_GROUPS ) >0 ) ? "TRUE" : "FALSE" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "- SUPPORTED_VERSION_EXTENSION ( %s )", ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS ) > 0 ) ? "TRUE" : "FALSE" ) ); #if defined ( MBEDTLS_SSL_SERVER_NAME_INDICATION ) MBEDTLS_SSL_DEBUG_MSG( 3, ( "- SERVERNAME_EXTENSION ( %s )", ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_SERVERNAME ) > 0 ) ? "TRUE" : "FALSE" ) ); #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ #if defined ( MBEDTLS_SSL_ALPN ) MBEDTLS_SSL_DEBUG_MSG( 3, ( "- ALPN_EXTENSION ( %s )", ( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_ALPN ) > 0 ) ? "TRUE" : "FALSE" ) ); #endif /* MBEDTLS_SSL_ALPN */ } #endif /* MBEDTLS_DEBUG_C */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_client_hello_has_exts( mbedtls_ssl_context *ssl, int exts_mask ) { int masked = ssl->handshake->extensions_present & exts_mask; return( masked == exts_mask ); } 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_SUPPORTED_GROUPS | MBEDTLS_SSL_EXT_KEY_SHARE | MBEDTLS_SSL_EXT_SIG_ALG ) ); } #if defined(MBEDTLS_KEY_EXCHANGE_SOME_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_PRE_SHARED_KEY | MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) ); } 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_SUPPORTED_GROUPS | MBEDTLS_SSL_EXT_KEY_SHARE | MBEDTLS_SSL_EXT_PRE_SHARED_KEY | MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) ); } #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_check_ephemeral_key_exchange( mbedtls_ssl_context *ssl ) { return( mbedtls_ssl_conf_tls13_ephemeral_enabled( ssl ) && ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange( ssl ) ); } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_check_psk_key_exchange( mbedtls_ssl_context *ssl ) { #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED) return( mbedtls_ssl_conf_tls13_psk_enabled( ssl ) && mbedtls_ssl_tls13_psk_enabled( 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_check_psk_ephemeral_key_exchange( mbedtls_ssl_context *ssl ) { #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED) return( mbedtls_ssl_conf_tls13_psk_ephemeral_enabled( ssl ) && mbedtls_ssl_tls13_psk_ephemeral_enabled( ssl ) && ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange( ssl ) ); #else ((void) ssl); return( 0 ); #endif } static int ssl_tls13_determine_key_exchange_mode( mbedtls_ssl_context *ssl ) { /* * 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 ) */ ssl->handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE; if( ssl_tls13_check_psk_ephemeral_key_exchange( ssl ) ) { ssl->handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: psk_ephemeral" ) ); } else if( ssl_tls13_check_ephemeral_key_exchange( ssl ) ) { ssl->handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL; MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: ephemeral" ) ); } else if( ssl_tls13_check_psk_key_exchange( ssl ) ) { ssl->handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: psk" ) ); } 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 ); } return( 0 ); } #if defined(MBEDTLS_X509_CRT_PARSE_C) && \ defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_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_KEY_EXCHANGE_WITH_CERT_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 0 #define SSL_CLIENT_HELLO_HRR_REQUIRED 1 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; size_t legacy_session_id_len; size_t cipher_suites_len; const unsigned char *cipher_suites_end; size_t extensions_len; const unsigned char *extensions_end; int hrr_required = 0; #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED) const unsigned char *cipher_suites; const unsigned char *pre_shared_key_ext = NULL; const unsigned char *pre_shared_key_ext_end = NULL; #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE; /* * 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; /* * Only support TLS 1.3 currently, temporarily set the version. */ ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; #if defined(MBEDTLS_SSL_SESSION_TICKETS) /* Store minor version for later use with ticket serialization. */ ssl->session_negotiate->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; ssl->session_negotiate->endpoint = ssl->conf->endpoint; #endif /* ... * Random random; * ... * with Random defined as: * opaque Random[32]; */ MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes", p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN ); memcpy( &ssl->handshake->randbytes[0], p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN ); p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN; /* ... * opaque legacy_session_id<0..32>; * ... */ legacy_session_id_len = p[0]; p++; 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", p, legacy_session_id_len ); /* * 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 ); memcpy( &ssl->session_negotiate->id[0], p, legacy_session_id_len ); p += legacy_session_id_len; cipher_suites_len = MBEDTLS_GET_UINT16_BE( p, 0 ); p += 2; /* 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 2 bytes * extensions_len 2 bytes */ MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, cipher_suites_len + 2 + 2 ); /* ... * CipherSuite cipher_suites<2..2^16-2>; * ... * with CipherSuite defined as: * uint8 CipherSuite[2]; */ #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED) cipher_suites = p; #endif cipher_suites_end = p + cipher_suites_len; MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, ciphersuitelist", p, cipher_suites_len ); /* * Search for a matching ciphersuite */ for ( ; p < cipher_suites_end; p += 2 ) { uint16_t cipher_suite; const mbedtls_ssl_ciphersuite_t* ciphersuite_info; MBEDTLS_SSL_CHK_BUF_READ_PTR( p, cipher_suites_end, 2 ); cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 ); ciphersuite_info = ssl_tls13_validate_peer_ciphersuite( ssl,cipher_suite ); if( ciphersuite_info == NULL ) continue; ssl->session_negotiate->ciphersuite = cipher_suite; ssl->handshake->ciphersuite_info = ciphersuite_info; MBEDTLS_SSL_DEBUG_MSG( 2, ( "selected ciphersuite: %04x - %s", cipher_suite, ciphersuite_info->name ) ); } if( ssl->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 ); } /* ... * 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 ); while( p < extensions_end ) { unsigned int extension_type; size_t extension_data_len; const unsigned char *extension_data_end; /* RFC 8446, page 57 * * 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( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_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_HANDSHAKE_FAILURE ); return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } 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; 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 ); } ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SERVERNAME; break; #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ #if defined(MBEDTLS_ECDH_C) 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, "mbedtls_ssl_parse_supported_groups_ext", ret ); return( ret ); } ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS; break; #endif /* MBEDTLS_ECDH_C */ #if defined(MBEDTLS_ECDH_C) 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, ( "HRR needed " ) ); hrr_required = 1; } if( ret < 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_parse_key_shares_ext", ret ); return( ret ); } ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE; break; #endif /* MBEDTLS_ECDH_C */ case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS: MBEDTLS_SSL_DEBUG_MSG( 3, ( "found supported versions extension" ) ); ret = ssl_tls13_parse_supported_versions_ext( ssl, p, extension_data_end ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_supported_versions_ext" ), ret ); return( ret ); } ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS; break; #if defined(MBEDTLS_KEY_EXCHANGE_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 ); } ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES; break; #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ case MBEDTLS_TLS_EXT_PRE_SHARED_KEY: MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension" ) ); if( ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) == 0 ) { MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); } #if defined(MBEDTLS_KEY_EXCHANGE_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_KEY_EXCHANGE_SOME_PSK_ENABLED */ ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PRE_SHARED_KEY; 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 ); } ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_ALPN; break; #endif /* MBEDTLS_SSL_ALPN */ #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_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_MSG( 1, ( "ssl_parse_supported_signature_algorithms_server_ext ( %d )", ret ) ); return( ret ); } ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SIG_ALG; break; #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */ default: MBEDTLS_SSL_DEBUG_MSG( 3, ( "unknown extension found: %ud ( ignoring )", extension_type ) ); } p += extension_data_len; } #if defined(MBEDTLS_DEBUG_C) /* List all the extensions we have received */ ssl_tls13_debug_print_client_hello_exts( ssl ); #endif /* MBEDTLS_DEBUG_C */ mbedtls_ssl_add_hs_hdr_to_checksum( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, p - buf ); #if defined(MBEDTLS_KEY_EXCHANGE_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. */ /* If we've settled on a PSK-based exchange, parse PSK identity ext */ if( mbedtls_ssl_tls13_some_psk_enabled( ssl ) && mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) && ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) ) { ssl->handshake->update_checksum( ssl, buf, pre_shared_key_ext - buf ); ret = ssl_tls13_parse_pre_shared_key_ext( ssl, pre_shared_key_ext, pre_shared_key_ext_end, cipher_suites, cipher_suites_end ); if( ret == MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY ) { ssl->handshake->extensions_present &= ~MBEDTLS_SSL_EXT_PRE_SHARED_KEY; } else if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_pre_shared_key_ext" ), ret ); return( ret ); } } else #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ { ssl->handshake->update_checksum( ssl, buf, p - buf ); } ret = ssl_tls13_determine_key_exchange_mode( ssl ); if( ret < 0 ) return( ret ); mbedtls_ssl_optimize_checksum( ssl, ssl->handshake->ciphersuite_info ); return( hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK ); } /* Update the handshake state machine */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_postprocess_client_hello( mbedtls_ssl_context* ssl ) { 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 ); } 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 return value of parse_client_hello, * only SSL_CLIENT_HELLO_OK or * SSL_CLIENT_HELLO_HRR_REQUIRED at this * stage as negative error codes are handled * by MBEDTLS_SSL_PROC_CHK_NEG. */ MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_client_hello( ssl ) ); if( parse_client_hello_ret == SSL_CLIENT_HELLO_OK ) 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( ssl->conf->f_rng == NULL ) { MBEDTLS_SSL_DEBUG_MSG( 1, ( "no RNG provided" ) ); return( MBEDTLS_ERR_SSL_NO_RNG ); } 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 = 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; 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_ECDH_C) if( mbedtls_ssl_tls13_named_group_is_ecdhe( named_group ) ) { ret = mbedtls_ssl_tls13_generate_and_write_ecdh_key_exchange( ssl, named_group, buf, end, out_len ); if( ret != 0 ) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_generate_and_write_ecdh_key_exchange", ret ); return( ret ); } } else #endif /* MBEDTLS_ECDH_C */ 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; 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; 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; /* ... * 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_KEY_EXCHANGE_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_KEY_EXCHANGE_SOME_PSK_ENABLED */ 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 ); return( ret ); } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_finalize_write_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_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_write_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_count > 0 ) { 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_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_count++; #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 */ 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 ); 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_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_KEY_EXCHANGE_WITH_CERT_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_KEY_EXCHANGE_WITH_CERT_ENABLED) #define SSL_CERTIFICATE_REQUEST_SEND_REQUEST 0 #define SSL_CERTIFICATE_REQUEST_SKIP 1 /* 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 ) 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; 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_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_KEY_EXCHANGE_WITH_CERT_ENABLED */ /* * 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 ); } MBEDTLS_SSL_DEBUG_MSG( 1, ( "Switch to handshake keys for inbound traffic" ) ); mbedtls_ssl_set_inbound_transform( ssl, ssl->handshake->transform_handshake ); 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 ); } return( 0 ); } /* * 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) mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_NEW_SESSION_TICKET ); #else mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HANDSHAKE_OVER ); #endif return( 0 ); } /* * Handler for MBEDTLS_SSL_NEW_SESSION_TICKET */ #define SSL_NEW_SESSION_TICKET_SKIP 0 #define SSL_NEW_SESSION_TICKET_WRITE 1 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 ); } #if defined(MBEDTLS_SSL_SESSION_TICKETS) 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" ) ); #if defined(MBEDTLS_HAVE_TIME) session->start = mbedtls_time( NULL ); #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_psa_translate_md( 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 (start) * - flags (flags) * - age add (ticket_age_add) * - key (key) * - key length (key_len) * - ciphersuite (ciphersuite) */ 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; *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 */ 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 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). The value of zero indicates that the * ticket should be discarded immediately. Clients MUST NOT cache * tickets for longer than 7 days, regardless of the ticket_lifetime, * and MAY delete tickets earlier based on local policy. A server * MAY treat a ticket as valid for a shorter period of time than what * is stated in the ticket_lifetime. */ ticket_lifetime %= 604800; 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 * * Note: We currently don't have any extensions. * Set length to zero. */ MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 ); MBEDTLS_PUT_UINT16_BE( 0, p, 0 ); p += 2; *out_len = p - buf; MBEDTLS_SSL_DEBUG_BUF( 4, "ticket", buf, *out_len ); MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write new session ticket" ) ); return( 0 ); } /* * Handler for MBEDTLS_SSL_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_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( 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_KEY_EXCHANGE_WITH_CERT_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_KEY_EXCHANGE_WITH_CERT_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 ) 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; 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; 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; #if defined(MBEDTLS_SSL_SESSION_TICKETS) case MBEDTLS_SSL_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_NEW_SESSION_TICKET_FLUSH: /* This state is necessary to do the flush of the New Session * Ticket message written in MBEDTLS_SSL_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_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 */