diff --git a/ChangeLog.d/tls13-hrr-selected-group.txt b/ChangeLog.d/tls13-hrr-selected-group.txt new file mode 100644 index 0000000000..20d7a18fbd --- /dev/null +++ b/ChangeLog.d/tls13-hrr-selected-group.txt @@ -0,0 +1,5 @@ +Security + * Fix TLS 1.3 clients to reject a HelloRetryRequest whose selected group was + not advertised in the original ClientHello. Reported by + Din Asotić / Xiangdong Li, Beijing University of Posts and + Telecommunications (BUPT) diff --git a/library/ssl_client.c b/library/ssl_client.c index 0bd00cd91a..fb5fe57181 100644 --- a/library/ssl_client.c +++ b/library/ssl_client.c @@ -210,6 +210,10 @@ static int ssl_write_alpn_ext(mbedtls_ssl_context *ssl, * generalization of the TLS 1.2 supported elliptic curves extension. They both * share the same extension identifier. * + * If the TLS 1.3 logic for selecting proposed groups changes, the TLS 1.3 + * group filtering in the function `ssl_tls13_parse_hrr_key_share_ext()` must + * be updated accordingly. + * */ #define SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_2_FLAG 1 #define SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_3_FLAG 2 @@ -253,8 +257,8 @@ static int ssl_write_supported_groups_ext(mbedtls_ssl_context *ssl, if (flags & SSL_WRITE_SUPPORTED_GROUPS_EXT_TLS1_3_FLAG) { #if defined(PSA_WANT_ALG_ECDH) if (mbedtls_ssl_tls13_named_group_is_ecdhe(*group_list) && - (mbedtls_ssl_get_ecp_group_id_from_tls_id(*group_list) != - MBEDTLS_ECP_DP_NONE)) { + mbedtls_ssl_get_psa_curve_info_from_tls_id( + *group_list, NULL, NULL) == PSA_SUCCESS) { propose_group = 1; } #endif diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c index 752bc033fe..0d20db2023 100644 --- a/library/ssl_tls13_client.c +++ b/library/ssl_tls13_client.c @@ -405,14 +405,18 @@ static int ssl_tls13_parse_hrr_key_share_ext(mbedtls_ssl_context *ssl, * then the client MUST abort the handshake with an "illegal_parameter" alert. */ for (; *group_list != 0; group_list++) { + if (*group_list != selected_group) { + continue; + } #if defined(PSA_WANT_ALG_ECDH) if (mbedtls_ssl_tls13_named_group_is_ecdhe(*group_list)) { - if ((mbedtls_ssl_get_psa_curve_info_from_tls_id( - *group_list, NULL, NULL) == PSA_ERROR_NOT_SUPPORTED) || - *group_list != selected_group) { - found = 1; - break; + if (mbedtls_ssl_get_psa_curve_info_from_tls_id( + *group_list, NULL, NULL) == PSA_ERROR_NOT_SUPPORTED) { + continue; } + /* Found only if psa_curve is supported and group_list == selected_group */ + found = 1; + break; } #endif /* PSA_WANT_ALG_ECDH */ #if defined(PSA_WANT_ALG_FFDH) diff --git a/tests/suites/test_suite_ssl.data b/tests/suites/test_suite_ssl.data index 06e8b62303..ca8984c90a 100644 --- a/tests/suites/test_suite_ssl.data +++ b/tests/suites/test_suite_ssl.data @@ -3347,6 +3347,9 @@ cookie_parsing:"16fefd0000000000000000002F010000de000000000000011efefd7b72727272 TLS 1.3 srv Certificate msg - wrong vector lengths tls13_server_certificate_msg_invalid_vector_len +TLS 1.3 cli rejects HRR selecting an un-offered group +reject_hrr_selecting_unoffered_group + EC-JPAKE set password depends_on:MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED ssl_ecjpake_set_password:0 diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function index ae7ab55366..5d8340853c 100644 --- a/tests/suites/test_suite_ssl.function +++ b/tests/suites/test_suite_ssl.function @@ -3968,6 +3968,118 @@ exit: } /* END_CASE */ +/* BEGIN_CASE depends_on:MBEDTLS_SSL_PROTO_TLS1_3:MBEDTLS_SSL_CLI_C:MBEDTLS_SSL_SRV_C:MBEDTLS_TEST_AT_LEAST_ONE_TLS1_3_CIPHERSUITE:MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED:PSA_WANT_ALG_SHA_256:PSA_WANT_ALG_ECDH:MBEDTLS_PK_CAN_ECDSA_SIGN:PSA_WANT_ECC_SECP_R1_256:PSA_WANT_ECC_SECP_R1_384 */ +void reject_hrr_selecting_unoffered_group(void) +{ + int ret = -1; + + mbedtls_test_ssl_endpoint client_ep, server_ep; + mbedtls_test_handshake_test_options client_options, server_options; +#if defined(MBEDTLS_DEBUG_C) + mbedtls_test_ssl_log_pattern cli_pattern = { .pattern = "Invalid key share in HRR" }; +#endif /* MBEDTLS_DEBUG_C */ + + /* Group order is intentional: client offers secp256r1 first, while server only + * accepts secp384r1. This prevents immediate group agreement and forces HRR. */ + uint16_t client_group_list[] = { + MBEDTLS_SSL_IANA_TLS_GROUP_SECP256R1, + MBEDTLS_SSL_IANA_TLS_GROUP_SECP384R1, + MBEDTLS_SSL_IANA_TLS_GROUP_NONE + }; + uint16_t server_group_list[] = { MBEDTLS_SSL_IANA_TLS_GROUP_SECP384R1, + MBEDTLS_SSL_IANA_TLS_GROUP_NONE }; + + memset(&client_ep, 0, sizeof(client_ep)); + memset(&server_ep, 0, sizeof(server_ep)); + + mbedtls_test_init_handshake_options(&client_options); + mbedtls_test_init_handshake_options(&server_options); + MD_OR_USE_PSA_INIT(); + + client_options.pk_alg = MBEDTLS_PK_ECDSA; + client_options.client_min_version = MBEDTLS_SSL_VERSION_TLS1_3; + client_options.client_max_version = MBEDTLS_SSL_VERSION_TLS1_3; + client_options.group_list = client_group_list; +#if defined(MBEDTLS_DEBUG_C) + client_options.cli_log_obj = &cli_pattern; + client_options.cli_log_fun = mbedtls_test_ssl_log_analyzer; + mbedtls_debug_set_threshold(1); +#endif /* MBEDTLS_DEBUG_C */ + + server_options.pk_alg = MBEDTLS_PK_ECDSA; + server_options.server_min_version = MBEDTLS_SSL_VERSION_TLS1_3; + server_options.server_max_version = MBEDTLS_SSL_VERSION_TLS1_3; + server_options.group_list = server_group_list; + + for (int round = 0; round < 2; round++) { + int select_unoffered_group = (round != 0); + TEST_EQUAL(mbedtls_test_ssl_endpoint_init(&client_ep, + MBEDTLS_SSL_IS_CLIENT, + &client_options, NULL, NULL, + NULL), 0); + + TEST_EQUAL(mbedtls_test_ssl_endpoint_init(&server_ep, + MBEDTLS_SSL_IS_SERVER, + &server_options, NULL, NULL, + NULL), 0); + + TEST_EQUAL(mbedtls_test_mock_socket_connect(&(client_ep.socket), + &(server_ep.socket), 4096), 0); + + ret = mbedtls_test_move_handshake_to_state( + &(server_ep.ssl), &(client_ep.ssl), + MBEDTLS_SSL_HELLO_RETRY_REQUEST); + TEST_EQUAL(ret, 0); + TEST_EQUAL(client_ep.ssl.handshake->offered_group_id, + MBEDTLS_SSL_IANA_TLS_GROUP_SECP256R1); + + if (!select_unoffered_group) { + TEST_EQUAL(server_ep.ssl.handshake->hrr_selected_group, + MBEDTLS_SSL_IANA_TLS_GROUP_SECP384R1); + } else { + server_ep.ssl.handshake->hrr_selected_group = MBEDTLS_SSL_IANA_TLS_GROUP_X25519; + } + + /* Write and send the HRR */ + TEST_EQUAL(mbedtls_ssl_handshake_step(&(server_ep.ssl)), 0); + TEST_EQUAL(mbedtls_ssl_flush_output(&(server_ep.ssl)), 0); + + if (!select_unoffered_group) { + /* Valid HRR, the client accepts the group MBEDTLS_SSL_IANA_TLS_GROUP_SECP384R1 + * and goes ahead with the handshake. + */ + TEST_EQUAL(mbedtls_ssl_handshake_step(&(client_ep.ssl)), 0); + TEST_ASSERT(client_ep.ssl.state != MBEDTLS_SSL_SERVER_HELLO); +#if defined(MBEDTLS_DEBUG_C) + TEST_EQUAL(cli_pattern.counter, 0); +#endif /* MBEDTLS_DEBUG_C */ + } else { + /* Invalid HRR selecting MBEDTLS_SSL_IANA_TLS_GROUP_X25519 group. + * The client rejects it and aborts the handshake. + */ + TEST_EQUAL(mbedtls_ssl_handshake_step(&(client_ep.ssl)), + MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); + TEST_EQUAL(client_ep.ssl.state, MBEDTLS_SSL_SERVER_HELLO); +#if defined(MBEDTLS_DEBUG_C) + TEST_EQUAL(cli_pattern.counter, 1); +#endif /* MBEDTLS_DEBUG_C */ + } + mbedtls_test_ssl_endpoint_free(&client_ep, NULL); + mbedtls_test_ssl_endpoint_free(&server_ep, NULL); + } + +exit: + mbedtls_test_ssl_endpoint_free(&client_ep, NULL); + mbedtls_test_ssl_endpoint_free(&server_ep, NULL); + mbedtls_test_free_handshake_options(&client_options); + mbedtls_test_free_handshake_options(&server_options); +#if defined(MBEDTLS_DEBUG_C) + mbedtls_debug_set_threshold(0); +#endif /* MBEDTLS_DEBUG_C */ + MD_OR_USE_PSA_DONE(); +} +/* END_CASE */ + /* BEGIN_CASE depends_on:MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */ void ssl_ecjpake_set_password(int use_opaque_arg) {