/* * TLS 1.3 client-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_CLI_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3) #include <string.h> #include "debug_internal.h" #include "mbedtls/error.h" #include "mbedtls/platform.h" #include "ssl_misc.h" #include "ssl_client.h" #include "ssl_tls13_keys.h" #include "ssl_debug_helpers.h" #include "mbedtls/psa_util.h" #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) /* Define a local translating function to save code size by not using too many * arguments in each translating place. */ static int local_err_translation(psa_status_t status) { return psa_status_to_mbedtls(status, psa_to_ssl_errors, ARRAY_LENGTH(psa_to_ssl_errors), psa_generic_status_to_mbedtls); } #define PSA_TO_MBEDTLS_ERR … #endif /* Write extensions */ /* * ssl_tls13_write_supported_versions_ext(): * * struct { * ProtocolVersion versions<2..254>; * } SupportedVersions; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_supported_versions_ext(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len) { unsigned char *p = buf; unsigned char versions_len = (ssl->handshake->min_tls_version <= MBEDTLS_SSL_VERSION_TLS1_2) ? 4 : 2; *out_len = 0; MBEDTLS_SSL_DEBUG_MSG(3, ("client hello, adding supported versions extension")); /* Check if we have space to write the extension: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - versions_length (1 byte ) * - versions (2 or 4 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 5 + versions_len); MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, p, 0); MBEDTLS_PUT_UINT16_BE(versions_len + 1, p, 2); p += 4; /* Length of versions */ *p++ = versions_len; /* Write values of supported versions. * They are defined by the configuration. * Currently, we advertise only TLS 1.3 or both TLS 1.3 and TLS 1.2. */ mbedtls_ssl_write_version(p, MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_VERSION_TLS1_3); MBEDTLS_SSL_DEBUG_MSG(3, ("supported version: [3:4]")); if (ssl->handshake->min_tls_version <= MBEDTLS_SSL_VERSION_TLS1_2) { mbedtls_ssl_write_version(p + 2, MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_VERSION_TLS1_2); MBEDTLS_SSL_DEBUG_MSG(3, ("supported version: [3:3]")); } *out_len = 5 + versions_len; mbedtls_ssl_tls13_set_hs_sent_ext_mask( ssl, MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS); return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_supported_versions_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { ((void) ssl); MBEDTLS_SSL_CHK_BUF_READ_PTR(buf, end, 2); if (mbedtls_ssl_read_version(buf, ssl->conf->transport) != MBEDTLS_SSL_VERSION_TLS1_3) { MBEDTLS_SSL_DEBUG_MSG(1, ("unexpected version")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } if (&buf[2] != end) { MBEDTLS_SSL_DEBUG_MSG( 1, ("supported_versions ext data length incorrect")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR); return MBEDTLS_ERR_SSL_DECODE_ERROR; } return 0; } #if defined(MBEDTLS_SSL_ALPN) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_alpn_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len) { const unsigned char *p = buf; const unsigned char *end = buf + len; size_t protocol_name_list_len, protocol_name_len; const unsigned char *protocol_name_list_end; /* If we didn't send it, the server shouldn't send it */ if (ssl->conf->alpn_list == NULL) { return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } /* * opaque ProtocolName<1..2^8-1>; * * struct { * ProtocolName protocol_name_list<2..2^16-1> * } ProtocolNameList; * * the "ProtocolNameList" MUST contain exactly one "ProtocolName" */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); protocol_name_list_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, protocol_name_list_len); protocol_name_list_end = p + protocol_name_list_len; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, protocol_name_list_end, 1); protocol_name_len = *p++; /* Check that the server chosen protocol was in our list and save it */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, protocol_name_list_end, protocol_name_len); for (const char **alpn = ssl->conf->alpn_list; *alpn != NULL; alpn++) { if (protocol_name_len == strlen(*alpn) && memcmp(p, *alpn, protocol_name_len) == 0) { ssl->alpn_chosen = *alpn; return 0; } } return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } #endif /* MBEDTLS_SSL_ALPN */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_reset_key_share(mbedtls_ssl_context *ssl) { uint16_t group_id = ssl->handshake->offered_group_id; if (group_id == 0) { return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) if (mbedtls_ssl_tls13_named_group_is_ecdhe(group_id) || mbedtls_ssl_tls13_named_group_is_ffdh(group_id)) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; /* Destroy generated private key. */ status = psa_destroy_key(ssl->handshake->xxdh_psa_privkey); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_destroy_key", ret); return ret; } ssl->handshake->xxdh_psa_privkey = MBEDTLS_SVC_KEY_ID_INIT; return 0; } else #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ if (0 /* other KEMs? */) { /* Do something */ } return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* * Functions for writing key_share extension. */ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_get_default_group_id(mbedtls_ssl_context *ssl, uint16_t *group_id) { int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; #if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) const uint16_t *group_list = mbedtls_ssl_get_groups(ssl); /* Pick first available ECDHE group compatible with TLS 1.3 */ if (group_list == NULL) { return MBEDTLS_ERR_SSL_BAD_CONFIG; } for (; *group_list != 0; group_list++) { #if defined(PSA_WANT_ALG_ECDH) if ((mbedtls_ssl_get_psa_curve_info_from_tls_id( *group_list, NULL, NULL) == PSA_SUCCESS) && mbedtls_ssl_tls13_named_group_is_ecdhe(*group_list)) { *group_id = *group_list; return 0; } #endif #if defined(PSA_WANT_ALG_FFDH) if (mbedtls_ssl_tls13_named_group_is_ffdh(*group_list)) { *group_id = *group_list; return 0; } #endif } #else ((void) ssl); ((void) group_id); #endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */ return ret; } /* * ssl_tls13_write_key_share_ext * * Structure of key_share extension in ClientHello: * * struct { * NamedGroup group; * opaque key_exchange<1..2^16-1>; * } KeyShareEntry; * struct { * KeyShareEntry client_shares<0..2^16-1>; * } KeyShareClientHello; */ 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) { unsigned char *p = buf; unsigned char *client_shares; /* Start of client_shares */ size_t client_shares_len; /* Length of client_shares */ uint16_t group_id; int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; *out_len = 0; /* Check if we have space for header and length fields: * - extension_type (2 bytes) * - extension_data_length (2 bytes) * - client_shares_length (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 6); p += 6; MBEDTLS_SSL_DEBUG_MSG(3, ("client hello: adding key share extension")); /* HRR could already have requested something else. */ group_id = ssl->handshake->offered_group_id; if (!mbedtls_ssl_tls13_named_group_is_ecdhe(group_id) && !mbedtls_ssl_tls13_named_group_is_ffdh(group_id)) { MBEDTLS_SSL_PROC_CHK(ssl_tls13_get_default_group_id(ssl, &group_id)); } /* * Dispatch to type-specific key generation function. * * So far, we're only supporting ECDHE. With the introduction * of PQC KEMs, we'll want to have multiple branches, one per * type of KEM, and dispatch to the corresponding crypto. And * only one key share entry is allowed. */ client_shares = p; #if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) if (mbedtls_ssl_tls13_named_group_is_ecdhe(group_id) || mbedtls_ssl_tls13_named_group_is_ffdh(group_id)) { /* Pointer to group */ unsigned char *group = p; /* Length of key_exchange */ size_t key_exchange_len = 0; /* Check there is space for header of KeyShareEntry * - group (2 bytes) * - key_exchange_length (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 4); p += 4; ret = mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange( ssl, group_id, p, end, &key_exchange_len); p += key_exchange_len; if (ret != 0) { return ret; } /* Write group */ MBEDTLS_PUT_UINT16_BE(group_id, group, 0); /* Write key_exchange_length */ MBEDTLS_PUT_UINT16_BE(key_exchange_len, group, 2); } else #endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */ if (0 /* other KEMs? */) { /* Do something */ } else { return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* Length of client_shares */ client_shares_len = p - client_shares; if (client_shares_len == 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("No key share defined.")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* Write extension_type */ MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, buf, 0); /* Write extension_data_length */ MBEDTLS_PUT_UINT16_BE(client_shares_len + 2, buf, 2); /* Write client_shares_length */ MBEDTLS_PUT_UINT16_BE(client_shares_len, buf, 4); /* Update offered_group_id field */ ssl->handshake->offered_group_id = group_id; /* Output the total length of key_share extension. */ *out_len = p - buf; MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, key_share extension", buf, *out_len); mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); cleanup: return ret; } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ /* * ssl_tls13_parse_hrr_key_share_ext() * Parse key_share extension in Hello Retry Request * * struct { * NamedGroup selected_group; * } KeyShareHelloRetryRequest; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_hrr_key_share_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { #if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) const unsigned char *p = buf; int selected_group; int found = 0; const uint16_t *group_list = mbedtls_ssl_get_groups(ssl); if (group_list == NULL) { return MBEDTLS_ERR_SSL_BAD_CONFIG; } MBEDTLS_SSL_DEBUG_BUF(3, "key_share extension", p, end - buf); /* Read selected_group */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); selected_group = MBEDTLS_GET_UINT16_BE(p, 0); MBEDTLS_SSL_DEBUG_MSG(3, ("selected_group ( %d )", selected_group)); /* Upon receipt of this extension in a HelloRetryRequest, the client * MUST first verify that the selected_group field corresponds to a * group which was provided in the "supported_groups" extension in the * original ClientHello. * The supported_group was based on the info in ssl->conf->group_list. * * If the server provided a key share that was not sent in the ClientHello * then the client MUST abort the handshake with an "illegal_parameter" alert. */ for (; *group_list != 0; group_list++) { #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; } } #endif /* PSA_WANT_ALG_ECDH */ #if defined(PSA_WANT_ALG_FFDH) if (mbedtls_ssl_tls13_named_group_is_ffdh(*group_list)) { found = 1; break; } #endif /* PSA_WANT_ALG_FFDH */ } /* Client MUST verify that the selected_group field does not * correspond to a group which was provided in the "key_share" * extension in the original ClientHello. If the server sent an * HRR message with a key share already provided in the * ClientHello then the client MUST abort the handshake with * an "illegal_parameter" alert. */ if (found == 0 || selected_group == ssl->handshake->offered_group_id) { MBEDTLS_SSL_DEBUG_MSG(1, ("Invalid key share in HRR")); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } /* Remember server's preference for next ClientHello */ ssl->handshake->offered_group_id = selected_group; return 0; #else /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */ (void) ssl; (void) buf; (void) end; return MBEDTLS_ERR_SSL_BAD_CONFIG; #endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */ } /* * ssl_tls13_parse_key_share_ext() * Parse key_share extension in Server Hello * * struct { * KeyShareEntry server_share; * } KeyShareServerHello; * struct { * NamedGroup group; * opaque key_exchange<1..2^16-1>; * } KeyShareEntry; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_key_share_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const unsigned char *p = buf; uint16_t group, offered_group; /* ... * NamedGroup group; (2 bytes) * ... */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); group = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; /* Check that the chosen group matches the one we offered. */ offered_group = ssl->handshake->offered_group_id; if (offered_group != group) { MBEDTLS_SSL_DEBUG_MSG( 1, ("Invalid server key share, our group %u, their group %u", (unsigned) offered_group, (unsigned) group)); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) if (mbedtls_ssl_tls13_named_group_is_ecdhe(group) || mbedtls_ssl_tls13_named_group_is_ffdh(group)) { MBEDTLS_SSL_DEBUG_MSG(2, ("DHE group name: %s", mbedtls_ssl_named_group_to_str(group))); ret = mbedtls_ssl_tls13_read_public_xxdhe_share(ssl, p, end - p); if (ret != 0) { return ret; } } else #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ if (0 /* other KEMs? */) { /* Do something */ } else { return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } return ret; } /* * ssl_tls13_parse_cookie_ext() * Parse cookie extension in Hello Retry Request * * struct { * opaque cookie<1..2^16-1>; * } Cookie; * * When sending a HelloRetryRequest, the server MAY provide a "cookie" * extension to the client (this is an exception to the usual rule that * the only extensions that may be sent are those that appear in the * ClientHello). When sending the new ClientHello, the client MUST copy * the contents of the extension received in the HelloRetryRequest into * a "cookie" extension in the new ClientHello. Clients MUST NOT use * cookies in their initial ClientHello in subsequent connections. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_cookie_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { uint16_t cookie_len; const unsigned char *p = buf; mbedtls_ssl_handshake_params *handshake = ssl->handshake; /* Retrieve length field of cookie */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); cookie_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, cookie_len); MBEDTLS_SSL_DEBUG_BUF(3, "cookie extension", p, cookie_len); mbedtls_free(handshake->cookie); handshake->cookie_len = 0; handshake->cookie = mbedtls_calloc(1, cookie_len); if (handshake->cookie == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("alloc failed ( %ud bytes )", cookie_len)); return MBEDTLS_ERR_SSL_ALLOC_FAILED; } memcpy(handshake->cookie, p, cookie_len); handshake->cookie_len = cookie_len; return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_cookie_ext(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len) { unsigned char *p = buf; *out_len = 0; mbedtls_ssl_handshake_params *handshake = ssl->handshake; if (handshake->cookie == NULL) { MBEDTLS_SSL_DEBUG_MSG(3, ("no cookie to send; skip extension")); return 0; } MBEDTLS_SSL_DEBUG_BUF(3, "client hello, cookie", handshake->cookie, handshake->cookie_len); MBEDTLS_SSL_CHK_BUF_PTR(p, end, handshake->cookie_len + 6); MBEDTLS_SSL_DEBUG_MSG(3, ("client hello, adding cookie extension")); MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_COOKIE, p, 0); MBEDTLS_PUT_UINT16_BE(handshake->cookie_len + 2, p, 2); MBEDTLS_PUT_UINT16_BE(handshake->cookie_len, p, 4); p += 6; /* Cookie */ memcpy(p, handshake->cookie, handshake->cookie_len); *out_len = handshake->cookie_len + 6; mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_COOKIE); return 0; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) /* * ssl_tls13_write_psk_key_exchange_modes_ext() structure: * * 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_write_psk_key_exchange_modes_ext(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len) { unsigned char *p = buf; int ke_modes_len = 0; ((void) ke_modes_len); *out_len = 0; /* Skip writing extension if no PSK key exchange mode * is enabled in the config. */ if (!mbedtls_ssl_conf_tls13_is_some_psk_enabled(ssl)) { MBEDTLS_SSL_DEBUG_MSG(3, ("skip psk_key_exchange_modes extension")); return 0; } /* Require 7 bytes of data, otherwise fail, * even if extension might be shorter. */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 7); MBEDTLS_SSL_DEBUG_MSG( 3, ("client hello, adding psk_key_exchange_modes extension")); MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES, p, 0); /* Skip extension length (2 bytes) and * ke_modes length (1 byte) for now. */ p += 5; if (mbedtls_ssl_conf_tls13_is_psk_ephemeral_enabled(ssl)) { *p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE; ke_modes_len++; MBEDTLS_SSL_DEBUG_MSG(4, ("Adding PSK-ECDHE key exchange mode")); } if (mbedtls_ssl_conf_tls13_is_psk_enabled(ssl)) { *p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE; ke_modes_len++; MBEDTLS_SSL_DEBUG_MSG(4, ("Adding pure PSK key exchange mode")); } /* Now write the extension and ke_modes length */ MBEDTLS_PUT_UINT16_BE(ke_modes_len + 1, buf, 2); buf[4] = ke_modes_len; *out_len = p - buf; mbedtls_ssl_tls13_set_hs_sent_ext_mask( ssl, MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES); return 0; } #if defined(MBEDTLS_SSL_SESSION_TICKETS) static psa_algorithm_t ssl_tls13_get_ciphersuite_hash_alg(int ciphersuite) { const mbedtls_ssl_ciphersuite_t *ciphersuite_info = NULL; ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(ciphersuite); if (ciphersuite_info != NULL) { return mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) ciphersuite_info->mac); } return PSA_ALG_NONE; } static int ssl_tls13_has_configured_ticket(mbedtls_ssl_context *ssl) { mbedtls_ssl_session *session = ssl->session_negotiate; return ssl->handshake->resume && session != NULL && session->ticket != NULL && mbedtls_ssl_conf_tls13_is_kex_mode_enabled( ssl, mbedtls_ssl_tls13_session_get_ticket_flags( session, MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL)); } #if defined(MBEDTLS_SSL_EARLY_DATA) static int ssl_tls13_early_data_has_valid_ticket(mbedtls_ssl_context *ssl) { mbedtls_ssl_session *session = ssl->session_negotiate; return ssl->handshake->resume && session->tls_version == MBEDTLS_SSL_VERSION_TLS1_3 && mbedtls_ssl_tls13_session_ticket_allow_early_data(session) && mbedtls_ssl_tls13_cipher_suite_is_offered(ssl, session->ciphersuite); } #endif MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_ticket_get_identity(mbedtls_ssl_context *ssl, psa_algorithm_t *hash_alg, const unsigned char **identity, size_t *identity_len) { mbedtls_ssl_session *session = ssl->session_negotiate; if (!ssl_tls13_has_configured_ticket(ssl)) { return -1; } *hash_alg = ssl_tls13_get_ciphersuite_hash_alg(session->ciphersuite); *identity = session->ticket; *identity_len = session->ticket_len; return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_ticket_get_psk(mbedtls_ssl_context *ssl, psa_algorithm_t *hash_alg, const unsigned char **psk, size_t *psk_len) { mbedtls_ssl_session *session = ssl->session_negotiate; if (!ssl_tls13_has_configured_ticket(ssl)) { return -1; } *hash_alg = ssl_tls13_get_ciphersuite_hash_alg(session->ciphersuite); *psk = session->resumption_key; *psk_len = session->resumption_key_len; return 0; } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_psk_get_identity(mbedtls_ssl_context *ssl, psa_algorithm_t *hash_alg, const unsigned char **identity, size_t *identity_len) { if (!mbedtls_ssl_conf_has_static_psk(ssl->conf)) { return -1; } *hash_alg = PSA_ALG_SHA_256; *identity = ssl->conf->psk_identity; *identity_len = ssl->conf->psk_identity_len; return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_psk_get_psk(mbedtls_ssl_context *ssl, psa_algorithm_t *hash_alg, const unsigned char **psk, size_t *psk_len) { if (!mbedtls_ssl_conf_has_static_psk(ssl->conf)) { return -1; } *hash_alg = PSA_ALG_SHA_256; *psk = ssl->conf->psk; *psk_len = ssl->conf->psk_len; return 0; } static int ssl_tls13_get_configured_psk_count(mbedtls_ssl_context *ssl) { int configured_psk_count = 0; #if defined(MBEDTLS_SSL_SESSION_TICKETS) if (ssl_tls13_has_configured_ticket(ssl)) { MBEDTLS_SSL_DEBUG_MSG(3, ("Ticket is configured")); configured_psk_count++; } #endif if (mbedtls_ssl_conf_has_static_psk(ssl->conf)) { MBEDTLS_SSL_DEBUG_MSG(3, ("PSK is configured")); configured_psk_count++; } return configured_psk_count; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_identity(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, const unsigned char *identity, size_t identity_len, uint32_t obfuscated_ticket_age, size_t *out_len) { ((void) ssl); *out_len = 0; /* * - identity_len (2 bytes) * - identity (psk_identity_len bytes) * - obfuscated_ticket_age (4 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6 + identity_len); MBEDTLS_PUT_UINT16_BE(identity_len, buf, 0); memcpy(buf + 2, identity, identity_len); MBEDTLS_PUT_UINT32_BE(obfuscated_ticket_age, buf, 2 + identity_len); MBEDTLS_SSL_DEBUG_BUF(4, "write identity", buf, 6 + identity_len); *out_len = 6 + identity_len; return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_binder(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, int psk_type, psa_algorithm_t hash_alg, const unsigned char *psk, size_t psk_len, size_t *out_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char binder_len; unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE]; size_t transcript_len = 0; *out_len = 0; binder_len = PSA_HASH_LENGTH(hash_alg); /* * - binder_len (1 bytes) * - binder (binder_len bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 1 + binder_len); buf[0] = binder_len; /* Get current state of handshake transcript. */ ret = mbedtls_ssl_get_handshake_transcript( ssl, mbedtls_md_type_from_psa_alg(hash_alg), transcript, sizeof(transcript), &transcript_len); if (ret != 0) { return ret; } ret = mbedtls_ssl_tls13_create_psk_binder(ssl, hash_alg, psk, psk_len, psk_type, transcript, buf + 1); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_tls13_create_psk_binder", ret); return ret; } MBEDTLS_SSL_DEBUG_BUF(4, "write binder", buf, 1 + binder_len); *out_len = 1 + binder_len; return 0; } /* * mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext() structure: * * 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; * */ int mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, size_t *out_len, size_t *binders_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int configured_psk_count = 0; unsigned char *p = buf; psa_algorithm_t hash_alg = PSA_ALG_NONE; const unsigned char *identity; size_t identity_len; size_t l_binders_len = 0; size_t output_len; *out_len = 0; *binders_len = 0; /* Check if we have any PSKs to offer. If no, skip pre_shared_key */ configured_psk_count = ssl_tls13_get_configured_psk_count(ssl); if (configured_psk_count == 0) { MBEDTLS_SSL_DEBUG_MSG(3, ("skip pre_shared_key extensions")); return 0; } MBEDTLS_SSL_DEBUG_MSG(4, ("Pre-configured PSK number = %d", configured_psk_count)); /* Check if we have space to write the extension, binders included. * - extension_type (2 bytes) * - extension_data_len (2 bytes) * - identities_len (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 6); p += 6; #if defined(MBEDTLS_SSL_SESSION_TICKETS) if (ssl_tls13_ticket_get_identity( ssl, &hash_alg, &identity, &identity_len) == 0) { #if defined(MBEDTLS_HAVE_TIME) mbedtls_ms_time_t now = mbedtls_ms_time(); mbedtls_ssl_session *session = ssl->session_negotiate; /* The ticket age has been checked to be smaller than the * `ticket_lifetime` in ssl_prepare_client_hello() which is smaller than * 7 days (enforced in ssl_tls13_parse_new_session_ticket()) . Thus the * cast to `uint32_t` of the ticket age is safe. */ uint32_t obfuscated_ticket_age = (uint32_t) (now - session->ticket_reception_time); obfuscated_ticket_age += session->ticket_age_add; ret = ssl_tls13_write_identity(ssl, p, end, identity, identity_len, obfuscated_ticket_age, &output_len); #else ret = ssl_tls13_write_identity(ssl, p, end, identity, identity_len, 0, &output_len); #endif /* MBEDTLS_HAVE_TIME */ if (ret != 0) { return ret; } p += output_len; l_binders_len += 1 + PSA_HASH_LENGTH(hash_alg); } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ if (ssl_tls13_psk_get_identity( ssl, &hash_alg, &identity, &identity_len) == 0) { ret = ssl_tls13_write_identity(ssl, p, end, identity, identity_len, 0, &output_len); if (ret != 0) { return ret; } p += output_len; l_binders_len += 1 + PSA_HASH_LENGTH(hash_alg); } MBEDTLS_SSL_DEBUG_MSG(3, ("client hello, adding pre_shared_key extension, " "omitting PSK binder list")); /* Take into account the two bytes for the length of the binders. */ l_binders_len += 2; /* Check if there is enough space for binders */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, l_binders_len); /* * - extension_type (2 bytes) * - extension_data_len (2 bytes) * - identities_len (2 bytes) */ MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_PRE_SHARED_KEY, buf, 0); MBEDTLS_PUT_UINT16_BE(p - buf - 4 + l_binders_len, buf, 2); MBEDTLS_PUT_UINT16_BE(p - buf - 6, buf, 4); *out_len = (p - buf) + l_binders_len; *binders_len = l_binders_len; MBEDTLS_SSL_DEBUG_BUF(3, "pre_shared_key identities", buf, p - buf); return 0; } int mbedtls_ssl_tls13_write_binders_of_pre_shared_key_ext( mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *p = buf; psa_algorithm_t hash_alg = PSA_ALG_NONE; const unsigned char *psk; size_t psk_len; size_t output_len; /* Check if we have space to write binders_len. * - binders_len (2 bytes) */ MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); p += 2; #if defined(MBEDTLS_SSL_SESSION_TICKETS) if (ssl_tls13_ticket_get_psk(ssl, &hash_alg, &psk, &psk_len) == 0) { ret = ssl_tls13_write_binder(ssl, p, end, MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION, hash_alg, psk, psk_len, &output_len); if (ret != 0) { return ret; } p += output_len; } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ if (ssl_tls13_psk_get_psk(ssl, &hash_alg, &psk, &psk_len) == 0) { ret = ssl_tls13_write_binder(ssl, p, end, MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL, hash_alg, psk, psk_len, &output_len); if (ret != 0) { return ret; } p += output_len; } MBEDTLS_SSL_DEBUG_MSG(3, ("client hello, adding PSK binder list.")); /* * - binders_len (2 bytes) */ MBEDTLS_PUT_UINT16_BE(p - buf - 2, buf, 0); MBEDTLS_SSL_DEBUG_BUF(3, "pre_shared_key binders", buf, p - buf); mbedtls_ssl_tls13_set_hs_sent_ext_mask( ssl, MBEDTLS_TLS_EXT_PRE_SHARED_KEY); return 0; } /* * struct { * opaque identity<1..2^16-1>; * uint32 obfuscated_ticket_age; * } PskIdentity; * * opaque PskBinderEntry<32..255>; * * struct { * * select (Handshake.msg_type) { * ... * case server_hello: uint16 selected_identity; * }; * * } PreSharedKeyExtension; * */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_server_pre_shared_key_ext(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int selected_identity; const unsigned char *psk; size_t psk_len; psa_algorithm_t hash_alg; MBEDTLS_SSL_CHK_BUF_READ_PTR(buf, end, 2); selected_identity = MBEDTLS_GET_UINT16_BE(buf, 0); ssl->handshake->selected_identity = (uint16_t) selected_identity; MBEDTLS_SSL_DEBUG_MSG(3, ("selected_identity = %d", selected_identity)); if (selected_identity >= ssl_tls13_get_configured_psk_count(ssl)) { MBEDTLS_SSL_DEBUG_MSG(1, ("Invalid PSK identity.")); 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_SESSION_TICKETS) if (selected_identity == 0 && ssl_tls13_has_configured_ticket(ssl)) { ret = ssl_tls13_ticket_get_psk(ssl, &hash_alg, &psk, &psk_len); } else #endif if (mbedtls_ssl_conf_has_static_psk(ssl->conf)) { ret = ssl_tls13_psk_get_psk(ssl, &hash_alg, &psk, &psk_len); } else { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } if (ret != 0) { return ret; } if (mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) ssl->handshake->ciphersuite_info->mac) != hash_alg) { MBEDTLS_SSL_DEBUG_MSG( 1, ("Invalid ciphersuite for external psk.")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } ret = mbedtls_ssl_set_hs_psk(ssl, psk, psk_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret); return ret; } return 0; } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ int mbedtls_ssl_tls13_write_client_hello_exts(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 ext_len; *out_len = 0; ret = mbedtls_ssl_tls13_crypto_init(ssl); if (ret != 0) { return ret; } /* Write supported_versions extension * * Supported Versions Extension is mandatory with TLS 1.3. */ ret = ssl_tls13_write_supported_versions_ext(ssl, p, end, &ext_len); if (ret != 0) { return ret; } p += ext_len; /* Echo the cookie if the server provided one in its preceding * HelloRetryRequest message. */ ret = ssl_tls13_write_cookie_ext(ssl, p, end, &ext_len); if (ret != 0) { return ret; } p += ext_len; #if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) ret = mbedtls_ssl_tls13_write_record_size_limit_ext( ssl, p, end, &ext_len); if (ret != 0) { return ret; } p += ext_len; #endif #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) if (mbedtls_ssl_conf_tls13_is_some_ephemeral_enabled(ssl)) { ret = ssl_tls13_write_key_share_ext(ssl, p, end, &ext_len); if (ret != 0) { return ret; } p += ext_len; } #endif #if defined(MBEDTLS_SSL_EARLY_DATA) /* In the first ClientHello, write the early data indication extension if * necessary and update the early data state. * If an HRR has been received and thus we are currently writing the * second ClientHello, the second ClientHello must not contain an early * data extension and the early data state must stay as it is: * MBEDTLS_SSL_EARLY_DATA_STATE_NO_IND_SENT or * MBEDTLS_SSL_EARLY_DATA_STATE_REJECTED. */ if (!ssl->handshake->hello_retry_request_flag) { if (mbedtls_ssl_conf_tls13_is_some_psk_enabled(ssl) && ssl_tls13_early_data_has_valid_ticket(ssl) && ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_ENABLED) { ret = mbedtls_ssl_tls13_write_early_data_ext( ssl, 0, p, end, &ext_len); if (ret != 0) { return ret; } p += ext_len; ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT; } else { ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_NO_IND_SENT; } } #endif /* MBEDTLS_SSL_EARLY_DATA */ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) /* For PSK-based key exchange we need the pre_shared_key extension * and the psk_key_exchange_modes extension. * * The pre_shared_key extension MUST be the last extension in the * ClientHello. Servers MUST check that it is the last extension and * otherwise fail the handshake with an "illegal_parameter" alert. * * Add the psk_key_exchange_modes extension. */ ret = ssl_tls13_write_psk_key_exchange_modes_ext(ssl, p, end, &ext_len); if (ret != 0) { return ret; } p += ext_len; #endif *out_len = p - buf; return 0; } int mbedtls_ssl_tls13_finalize_client_hello(mbedtls_ssl_context *ssl) { ((void) ssl); #if defined(MBEDTLS_SSL_EARLY_DATA) int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; psa_algorithm_t hash_alg = PSA_ALG_NONE; const unsigned char *psk; size_t psk_len; const mbedtls_ssl_ciphersuite_t *ciphersuite_info; if (ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT) { MBEDTLS_SSL_DEBUG_MSG( 1, ("Set hs psk for early data when writing the first psk")); ret = ssl_tls13_ticket_get_psk(ssl, &hash_alg, &psk, &psk_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_ticket_get_psk", ret); return ret; } ret = mbedtls_ssl_set_hs_psk(ssl, psk, psk_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret); return ret; } /* * Early data are going to be encrypted using the ciphersuite * associated with the pre-shared key used for the handshake. * Note that if the server rejects early data, the handshake * based on the pre-shared key may complete successfully * with a selected ciphersuite different from the ciphersuite * associated with the pre-shared key. Only the hashes of the * two ciphersuites have to be the same. In that case, the * encrypted handshake data and application data are * encrypted using a different ciphersuite than the one used for * the rejected early data. */ ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( ssl->session_negotiate->ciphersuite); ssl->handshake->ciphersuite_info = ciphersuite_info; /* Enable psk and psk_ephemeral to make stage early happy */ ssl->handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL; /* Start the TLS 1.3 key schedule: * Set the PSK and derive early secret. */ ret = mbedtls_ssl_tls13_key_schedule_stage_early(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_key_schedule_stage_early", ret); return ret; } /* Derive early data key material */ 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; } #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_CCS_AFTER_CLIENT_HELLO); #else MBEDTLS_SSL_DEBUG_MSG( 1, ("Switch to early data keys for outbound traffic")); mbedtls_ssl_set_outbound_transform( ssl, ssl->handshake->transform_earlydata); ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_CAN_WRITE; #endif } #endif /* MBEDTLS_SSL_EARLY_DATA */ return 0; } /* * Functions for parsing and processing Server Hello */ /** * \brief Detect if the ServerHello contains a supported_versions extension * or not. * * \param[in] ssl SSL context * \param[in] buf Buffer containing the ServerHello message * \param[in] end End of the buffer containing the ServerHello message * * \return 0 if the ServerHello does not contain a supported_versions extension * \return 1 if the ServerHello contains a supported_versions extension * \return A negative value if an error occurred while parsing the ServerHello. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_is_supported_versions_ext_present( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { const unsigned char *p = buf; size_t legacy_session_id_echo_len; const unsigned char *supported_versions_data; const unsigned char *supported_versions_data_end; /* * Check there is enough data to access the legacy_session_id_echo vector * length: * - legacy_version 2 bytes * - random MBEDTLS_SERVER_HELLO_RANDOM_LEN bytes * - legacy_session_id_echo length 1 byte */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN + 3); p += MBEDTLS_SERVER_HELLO_RANDOM_LEN + 2; legacy_session_id_echo_len = *p; /* * Jump to the extensions, jumping over: * - legacy_session_id_echo (legacy_session_id_echo_len + 1) bytes * - cipher_suite 2 bytes * - legacy_compression_method 1 byte */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, legacy_session_id_echo_len + 4); p += legacy_session_id_echo_len + 4; return mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts( ssl, p, end, &supported_versions_data, &supported_versions_data_end); } /* Returns a negative value on failure, and otherwise * - 1 if the last eight bytes of the ServerHello random bytes indicate that * the server is TLS 1.3 capable but negotiating TLS 1.2 or below. * - 0 otherwise */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_is_downgrade_negotiation(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { /* First seven bytes of the magic downgrade strings, see RFC 8446 4.1.3 */ static const unsigned char magic_downgrade_string[] = { 0x44, 0x4F, 0x57, 0x4E, 0x47, 0x52, 0x44 }; const unsigned char *last_eight_bytes_of_random; unsigned char last_byte_of_random; MBEDTLS_SSL_CHK_BUF_READ_PTR(buf, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN + 2); last_eight_bytes_of_random = buf + 2 + MBEDTLS_SERVER_HELLO_RANDOM_LEN - 8; if (memcmp(last_eight_bytes_of_random, magic_downgrade_string, sizeof(magic_downgrade_string)) == 0) { last_byte_of_random = last_eight_bytes_of_random[7]; return last_byte_of_random == 0 || last_byte_of_random == 1; } return 0; } /* Returns a negative value on failure, and otherwise * - SSL_SERVER_HELLO or * - SSL_SERVER_HELLO_HRR * to indicate which message is expected and to be parsed next. */ #define SSL_SERVER_HELLO … #define SSL_SERVER_HELLO_HRR … MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_server_hello_is_hrr(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { /* Check whether this message is a HelloRetryRequest ( HRR ) message. * * Server Hello and HRR are only distinguished by Random set to the * special value of the SHA-256 of "HelloRetryRequest". * * struct { * ProtocolVersion legacy_version = 0x0303; * 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_SSL_CHK_BUF_READ_PTR( buf, end, 2 + sizeof(mbedtls_ssl_tls13_hello_retry_request_magic)); if (memcmp(buf + 2, mbedtls_ssl_tls13_hello_retry_request_magic, sizeof(mbedtls_ssl_tls13_hello_retry_request_magic)) == 0) { return SSL_SERVER_HELLO_HRR; } return SSL_SERVER_HELLO; } /* * Returns a negative value on failure, and otherwise * - SSL_SERVER_HELLO or * - SSL_SERVER_HELLO_HRR or * - SSL_SERVER_HELLO_TLS1_2 */ #define SSL_SERVER_HELLO_TLS1_2 … MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_preprocess_server_hello(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_handshake_params *handshake = ssl->handshake; MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_is_supported_versions_ext_present( ssl, buf, end)); if (ret == 0) { MBEDTLS_SSL_PROC_CHK_NEG( ssl_tls13_is_downgrade_negotiation(ssl, buf, end)); /* If the server is negotiating TLS 1.2 or below and: * . we did not propose TLS 1.2 or * . the server responded it is TLS 1.3 capable but negotiating a lower * version of the protocol and thus we are under downgrade attack * abort the handshake with an "illegal parameter" alert. */ if (handshake->min_tls_version > MBEDTLS_SSL_VERSION_TLS1_2 || ret) { MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } /* * Version 1.2 of the protocol has been negotiated, set the * ssl->keep_current_message flag for the ServerHello to be kept and * parsed as a TLS 1.2 ServerHello. 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. */ ssl->keep_current_message = 1; ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_2; MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, (size_t) (end - buf))); if (mbedtls_ssl_conf_tls13_is_some_ephemeral_enabled(ssl)) { ret = ssl_tls13_reset_key_share(ssl); if (ret != 0) { return ret; } } return SSL_SERVER_HELLO_TLS1_2; } ssl->session_negotiate->tls_version = ssl->tls_version; ssl->session_negotiate->endpoint = ssl->conf->endpoint; handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE; ret = ssl_server_hello_is_hrr(ssl, buf, end); switch (ret) { case SSL_SERVER_HELLO: MBEDTLS_SSL_DEBUG_MSG(2, ("received ServerHello message")); break; case SSL_SERVER_HELLO_HRR: MBEDTLS_SSL_DEBUG_MSG(2, ("received HelloRetryRequest message")); /* If a client receives a second HelloRetryRequest in the same * connection (i.e., where the ClientHello was itself in response * to a HelloRetryRequest), it MUST abort the handshake with an * "unexpected_message" alert. */ if (handshake->hello_retry_request_flag) { MBEDTLS_SSL_DEBUG_MSG(1, ("Multiple HRRs received")); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE, MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE); return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; } /* * Clients must abort the handshake with an "illegal_parameter" * alert if the HelloRetryRequest would not result in any change * in the ClientHello. * In a PSK only key exchange that what we expect. */ if (!mbedtls_ssl_conf_tls13_is_some_ephemeral_enabled(ssl)) { MBEDTLS_SSL_DEBUG_MSG(1, ("Unexpected HRR in pure PSK key exchange.")); MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } handshake->hello_retry_request_flag = 1; break; } cleanup: return ret; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_check_server_hello_session_id_echo(mbedtls_ssl_context *ssl, const unsigned char **buf, const unsigned char *end) { const unsigned char *p = *buf; size_t legacy_session_id_echo_len; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); legacy_session_id_echo_len = *p++; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, legacy_session_id_echo_len); /* legacy_session_id_echo */ if (ssl->session_negotiate->id_len != legacy_session_id_echo_len || memcmp(ssl->session_negotiate->id, p, legacy_session_id_echo_len) != 0) { MBEDTLS_SSL_DEBUG_BUF(3, "Expected Session ID", ssl->session_negotiate->id, ssl->session_negotiate->id_len); MBEDTLS_SSL_DEBUG_BUF(3, "Received Session ID", p, legacy_session_id_echo_len); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } p += legacy_session_id_echo_len; *buf = p; MBEDTLS_SSL_DEBUG_BUF(3, "Session ID", ssl->session_negotiate->id, ssl->session_negotiate->id_len); return 0; } /* Parse ServerHello message and configure context * * struct { * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 * 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_parse_server_hello(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end, int is_hrr) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const unsigned char *p = buf; mbedtls_ssl_handshake_params *handshake = ssl->handshake; size_t extensions_len; const unsigned char *extensions_end; uint16_t cipher_suite; const mbedtls_ssl_ciphersuite_t *ciphersuite_info; int fatal_alert = 0; uint32_t allowed_extensions_mask; int hs_msg_type = is_hrr ? MBEDTLS_SSL_TLS1_3_HS_HELLO_RETRY_REQUEST : MBEDTLS_SSL_HS_SERVER_HELLO; /* * Check there is space for minimal fields * * - legacy_version ( 2 bytes) * - random (MBEDTLS_SERVER_HELLO_RANDOM_LEN bytes) * - legacy_session_id_echo ( 1 byte ), minimum size * - cipher_suite ( 2 bytes) * - legacy_compression_method ( 1 byte ) */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN + 6); MBEDTLS_SSL_DEBUG_BUF(4, "server hello", p, end - p); MBEDTLS_SSL_DEBUG_BUF(3, "server hello, version", p, 2); /* ... * 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); ret = MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; goto cleanup; } p += 2; /* ... * Random random; * ... * with Random defined as: * opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN]; */ if (!is_hrr) { memcpy(&handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN], p, 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>; * ... */ if (ssl_tls13_check_server_hello_session_id_echo(ssl, &p, end) != 0) { fatal_alert = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER; goto cleanup; } /* ... * CipherSuite cipher_suite; * ... * with CipherSuite defined as: * uint8 CipherSuite[2]; */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); cipher_suite = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(cipher_suite); /* * Check whether this ciphersuite is valid and offered. */ if ((mbedtls_ssl_validate_ciphersuite(ssl, ciphersuite_info, ssl->tls_version, ssl->tls_version) != 0) || !mbedtls_ssl_tls13_cipher_suite_is_offered(ssl, cipher_suite)) { fatal_alert = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER; } /* * If we received an HRR before and that the proposed selected * ciphersuite in this server hello is not the same as the one * proposed in the HRR, we abort the handshake and send an * "illegal_parameter" alert. */ else if ((!is_hrr) && handshake->hello_retry_request_flag && (cipher_suite != ssl->session_negotiate->ciphersuite)) { fatal_alert = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER; } if (fatal_alert == MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER) { MBEDTLS_SSL_DEBUG_MSG(1, ("invalid ciphersuite(%04x) parameter", cipher_suite)); goto cleanup; } /* Configure ciphersuites */ mbedtls_ssl_optimize_checksum(ssl, ciphersuite_info); handshake->ciphersuite_info = ciphersuite_info; MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, chosen ciphersuite: ( %04x ) - %s", cipher_suite, ciphersuite_info->name)); #if defined(MBEDTLS_HAVE_TIME) ssl->session_negotiate->start = mbedtls_time(NULL); #endif /* MBEDTLS_HAVE_TIME */ /* ... * uint8 legacy_compression_method = 0; * ... */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); if (p[0] != MBEDTLS_SSL_COMPRESS_NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad legacy compression method")); fatal_alert = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER; goto cleanup; } p++; /* ... * Extension extensions<6..2^16-1>; * ... * struct { * ExtensionType extension_type; (2 bytes) * opaque extension_data<0..2^16-1>; * } Extension; */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); extensions_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; /* Check extensions do not go beyond the buffer of data. */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extensions_len); extensions_end = p + extensions_len; MBEDTLS_SSL_DEBUG_BUF(3, "server hello extensions", p, extensions_len); handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE; allowed_extensions_mask = is_hrr ? MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_HRR : MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_SH; while (p < extensions_end) { unsigned int extension_type; size_t extension_data_len; const unsigned char *extension_data_end; 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, hs_msg_type, extension_type, allowed_extensions_mask); if (ret != 0) { return ret; } switch (extension_type) { case MBEDTLS_TLS_EXT_COOKIE: ret = ssl_tls13_parse_cookie_ext(ssl, p, extension_data_end); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_parse_cookie_ext", ret); goto cleanup; } break; case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS: ret = ssl_tls13_parse_supported_versions_ext(ssl, p, extension_data_end); if (ret != 0) { goto cleanup; } break; #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) case MBEDTLS_TLS_EXT_PRE_SHARED_KEY: MBEDTLS_SSL_DEBUG_MSG(3, ("found pre_shared_key extension")); if ((ret = ssl_tls13_parse_server_pre_shared_key_ext( ssl, p, extension_data_end)) != 0) { MBEDTLS_SSL_DEBUG_RET( 1, ("ssl_tls13_parse_server_pre_shared_key_ext"), ret); return ret; } break; #endif case MBEDTLS_TLS_EXT_KEY_SHARE: MBEDTLS_SSL_DEBUG_MSG(3, ("found key_shares extension")); if (!mbedtls_ssl_conf_tls13_is_some_ephemeral_enabled(ssl)) { fatal_alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT; goto cleanup; } if (is_hrr) { ret = ssl_tls13_parse_hrr_key_share_ext(ssl, p, extension_data_end); } else { ret = ssl_tls13_parse_key_share_ext(ssl, p, extension_data_end); } if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_parse_key_share_ext", ret); goto cleanup; } break; default: ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; goto cleanup; } p += extension_data_len; } MBEDTLS_SSL_PRINT_EXTS(3, hs_msg_type, handshake->received_extensions); cleanup: if (fatal_alert == MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT) { MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT, MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION); ret = MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION; } else if (fatal_alert == MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER) { MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); ret = MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } return ret; } #if defined(MBEDTLS_DEBUG_C) static const char *ssl_tls13_get_kex_mode_str(int mode) { switch (mode) { case MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK: return "psk"; case MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL: return "ephemeral"; case MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL: return "psk_ephemeral"; default: return "unknown mode"; } } #endif /* MBEDTLS_DEBUG_C */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_postprocess_server_hello(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_handshake_params *handshake = ssl->handshake; /* Determine the key exchange mode: * 1) If both the pre_shared_key and key_share extensions were received * then the key exchange mode is PSK with EPHEMERAL. * 2) If only the pre_shared_key extension was received then the key * exchange mode is PSK-only. * 3) If only the key_share extension was received then the key * exchange mode is EPHEMERAL-only. */ switch (handshake->received_extensions & (MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) | MBEDTLS_SSL_EXT_MASK(KEY_SHARE))) { /* Only the pre_shared_key extension was received */ case MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY): handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; break; /* Only the key_share extension was received */ case MBEDTLS_SSL_EXT_MASK(KEY_SHARE): handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL; break; /* Both the pre_shared_key and key_share extensions were received */ case (MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) | MBEDTLS_SSL_EXT_MASK(KEY_SHARE)): handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; break; /* Neither pre_shared_key nor key_share extension was received */ default: MBEDTLS_SSL_DEBUG_MSG(1, ("Unknown key exchange.")); ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; goto cleanup; } if (!mbedtls_ssl_conf_tls13_is_kex_mode_enabled( ssl, handshake->key_exchange_mode)) { ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; MBEDTLS_SSL_DEBUG_MSG( 2, ("Key exchange mode(%s) is not supported.", ssl_tls13_get_kex_mode_str(handshake->key_exchange_mode))); goto cleanup; } MBEDTLS_SSL_DEBUG_MSG( 3, ("Selected key exchange mode: %s", ssl_tls13_get_kex_mode_str(handshake->key_exchange_mode))); /* Start the TLS 1.3 key scheduling if not already done. * * If we proposed early data then we have already derived an * early secret using the selected PSK and its associated hash. * It means that if the negotiated key exchange mode is psk or * psk_ephemeral, we have already correctly computed the * early secret and thus we do not do it again. In all other * cases we compute it here. */ #if defined(MBEDTLS_SSL_EARLY_DATA) if (ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_NO_IND_SENT || handshake->key_exchange_mode == MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL) #endif { ret = mbedtls_ssl_tls13_key_schedule_stage_early(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_key_schedule_stage_early", ret); goto cleanup; } } ret = mbedtls_ssl_tls13_compute_handshake_transform(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_tls13_compute_handshake_transform", ret); goto cleanup; } mbedtls_ssl_set_inbound_transform(ssl, handshake->transform_handshake); MBEDTLS_SSL_DEBUG_MSG(1, ("Switch to handshake keys for inbound traffic")); ssl->session_in = ssl->session_negotiate; cleanup: if (ret != 0) { MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); } return ret; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_postprocess_hrr(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_session_reset_msg_layer(ssl, 0); /* * We are going to re-generate a shared secret corresponding to the group * selected by the server, which is different from the group for which we * generated a shared secret in the first client hello. * Thus, reset the shared secret. */ ret = ssl_tls13_reset_key_share(ssl); if (ret != 0) { return ret; } ssl->session_negotiate->ciphersuite = ssl->handshake->ciphersuite_info->id; #if defined(MBEDTLS_SSL_EARLY_DATA) if (ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_NO_IND_SENT) { ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_REJECTED; } #endif return 0; } /* * Wait and parse ServerHello handshake message. * Handler for MBEDTLS_SSL_SERVER_HELLO */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_server_hello(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf = NULL; size_t buf_len = 0; int is_hrr = 0; MBEDTLS_SSL_DEBUG_MSG(2, ("=> %s", __func__)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len)); ret = ssl_tls13_preprocess_server_hello(ssl, buf, buf + buf_len); if (ret < 0) { goto cleanup; } else { is_hrr = (ret == SSL_SERVER_HELLO_HRR); } if (ret == SSL_SERVER_HELLO_TLS1_2) { ret = 0; goto cleanup; } MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_server_hello(ssl, buf, buf + buf_len, is_hrr)); if (is_hrr) { MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_reset_transcript_for_hrr(ssl)); } MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, buf_len)); if (is_hrr) { MBEDTLS_SSL_PROC_CHK(ssl_tls13_postprocess_hrr(ssl)); #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) /* If not offering early data, the client sends a dummy CCS record * immediately before its second flight. This may either be before * its second ClientHello or before its encrypted handshake flight. */ mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_CCS_BEFORE_2ND_CLIENT_HELLO); #else mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ } else { MBEDTLS_SSL_PROC_CHK(ssl_tls13_postprocess_server_hello(ssl)); mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); } cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= %s ( %s )", __func__, is_hrr ? "HelloRetryRequest" : "ServerHello")); return ret; } /* * * Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS * * The EncryptedExtensions message contains any extensions which * should be protected, i.e., any which are not needed to establish * the cryptographic context. */ /* Parse EncryptedExtensions message * struct { * Extension extensions<0..2^16-1>; * } EncryptedExtensions; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_encrypted_extensions(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { int ret = 0; size_t extensions_len; const unsigned char *p = buf; const unsigned char *extensions_end; mbedtls_ssl_handshake_params *handshake = ssl->handshake; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); 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, "encrypted 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; /* * struct { * ExtensionType extension_type; (2 bytes) * opaque extension_data<0..2^16-1>; * } Extension; */ 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); ret = mbedtls_ssl_tls13_check_received_extension( ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, extension_type, MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_EE); if (ret != 0) { return ret; } switch (extension_type) { #if defined(MBEDTLS_SSL_ALPN) case MBEDTLS_TLS_EXT_ALPN: MBEDTLS_SSL_DEBUG_MSG(3, ("found alpn extension")); if ((ret = ssl_tls13_parse_alpn_ext( ssl, p, (size_t) extension_data_len)) != 0) { return ret; } break; #endif /* MBEDTLS_SSL_ALPN */ #if defined(MBEDTLS_SSL_EARLY_DATA) case MBEDTLS_TLS_EXT_EARLY_DATA: if (extension_data_len != 0) { /* The message must be empty. */ MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR); return MBEDTLS_ERR_SSL_DECODE_ERROR; } break; #endif /* MBEDTLS_SSL_EARLY_DATA */ #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, p + extension_data_len); 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_ENCRYPTED_EXTENSIONS, extension_type, "( ignored )"); break; } p += extension_data_len; } if ((handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(RECORD_SIZE_LIMIT)) && (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(MAX_FRAGMENT_LENGTH))) { MBEDTLS_SSL_DEBUG_MSG(3, ( "Record size limit extension cannot be used with max fragment length 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_PRINT_EXTS(3, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, handshake->received_extensions); /* Check that we consumed all the message. */ if (p != end) { MBEDTLS_SSL_DEBUG_MSG(1, ("EncryptedExtension lengths misaligned")); MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR); return MBEDTLS_ERR_SSL_DECODE_ERROR; } return ret; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_encrypted_extensions(mbedtls_ssl_context *ssl) { int ret; unsigned char *buf; size_t buf_len; mbedtls_ssl_handshake_params *handshake = ssl->handshake; MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse encrypted extensions")); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, &buf, &buf_len)); /* Process the message contents */ MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_encrypted_extensions(ssl, buf, buf + buf_len)); #if defined(MBEDTLS_SSL_EARLY_DATA) if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(EARLY_DATA)) { /* RFC8446 4.2.11 * If the server supplies an "early_data" extension, the * client MUST verify that the server's selected_identity * is 0. If any other value is returned, the client MUST * abort the handshake with an "illegal_parameter" alert. * * 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 * * The server has sent an early data extension in its Encrypted * Extension message thus accepted to receive early data. We * check here that the additional constraints on the handshake * parameters, when early data are exchanged, are met, * namely: * - a PSK has been selected for the handshake * - the selected PSK for the handshake was the first one proposed * by the client. * - the selected ciphersuite for the handshake is the ciphersuite * associated with the selected PSK. */ if ((!mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) || handshake->selected_identity != 0 || handshake->ciphersuite_info->id != ssl->session_negotiate->ciphersuite) { MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_ACCEPTED; } else if (ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_NO_IND_SENT) { ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_REJECTED; } #endif /* * In case the client has proposed a PSK associated with a ticket, * `ssl->session_negotiate->ciphersuite` still contains at this point the * identifier of the ciphersuite associated with the ticket. This is that * way because, if an exchange of early data is agreed upon, we need * it to check that the ciphersuite selected for the handshake is the * ticket ciphersuite (see above). This information is not needed * anymore thus we can now set it to the identifier of the ciphersuite * used in this session under negotiation. */ ssl->session_negotiate->ciphersuite = handshake->ciphersuite_info->id; MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, buf_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 ((void) ssl); mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); #endif cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse encrypted extensions")); return ret; } #if defined(MBEDTLS_SSL_EARLY_DATA) /* * Handler for MBEDTLS_SSL_END_OF_EARLY_DATA * * RFC 8446 section 4.5 * * struct {} EndOfEarlyData; * * If the server sent an "early_data" extension in EncryptedExtensions, the * client MUST send an EndOfEarlyData message after receiving the server * Finished. Otherwise, the client MUST NOT send an EndOfEarlyData message. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_end_of_early_data(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf = NULL; size_t buf_len; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write EndOfEarlyData")); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, &buf, &buf_len)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_hdr_to_checksum( ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, 0)); MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg(ssl, buf_len, 0)); mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE); cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= write EndOfEarlyData")); return ret; } int mbedtls_ssl_get_early_data_status(mbedtls_ssl_context *ssl) { if ((ssl->conf->endpoint != MBEDTLS_SSL_IS_CLIENT) || (!mbedtls_ssl_is_handshake_over(ssl))) { return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } switch (ssl->early_data_state) { case MBEDTLS_SSL_EARLY_DATA_STATE_NO_IND_SENT: return MBEDTLS_SSL_EARLY_DATA_STATUS_NOT_INDICATED; break; case MBEDTLS_SSL_EARLY_DATA_STATE_REJECTED: return MBEDTLS_SSL_EARLY_DATA_STATUS_REJECTED; break; case MBEDTLS_SSL_EARLY_DATA_STATE_SERVER_FINISHED_RECEIVED: return MBEDTLS_SSL_EARLY_DATA_STATUS_ACCEPTED; break; default: return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } } #endif /* MBEDTLS_SSL_EARLY_DATA */ #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) /* * STATE HANDLING: CertificateRequest * */ #define SSL_CERTIFICATE_REQUEST_EXPECT_REQUEST … #define SSL_CERTIFICATE_REQUEST_SKIP … /* Coordination: * Deals with the ambiguity of not knowing if a CertificateRequest * will be sent. Returns a negative code on failure, or * - SSL_CERTIFICATE_REQUEST_EXPECT_REQUEST * - SSL_CERTIFICATE_REQUEST_SKIP * indicating if a Certificate Request is expected or not. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_certificate_request_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_CERTIFICATE_REQUEST)) { MBEDTLS_SSL_DEBUG_MSG(3, ("got a certificate request")); return SSL_CERTIFICATE_REQUEST_EXPECT_REQUEST; } MBEDTLS_SSL_DEBUG_MSG(3, ("got no certificate request")); return SSL_CERTIFICATE_REQUEST_SKIP; } /* * ssl_tls13_parse_certificate_request() * Parse certificate 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_parse_certificate_request(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 certificate_request_context_len = 0; size_t extensions_len = 0; const unsigned char *extensions_end; mbedtls_ssl_handshake_params *handshake = ssl->handshake; /* ... * opaque certificate_request_context<0..2^8-1> * ... */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); certificate_request_context_len = (size_t) p[0]; p += 1; if (certificate_request_context_len > 0) { MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, certificate_request_context_len); MBEDTLS_SSL_DEBUG_BUF(3, "Certificate Request Context", p, certificate_request_context_len); handshake->certificate_request_context = mbedtls_calloc(1, certificate_request_context_len); if (handshake->certificate_request_context == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("buffer too small")); return MBEDTLS_ERR_SSL_ALLOC_FAILED; } memcpy(handshake->certificate_request_context, p, certificate_request_context_len); p += certificate_request_context_len; } /* ... * Extension extensions<2..2^16-1>; * ... */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); 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; handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE; while (p < extensions_end) { unsigned int extension_type; size_t extension_data_len; 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); ret = mbedtls_ssl_tls13_check_received_extension( ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, extension_type, MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CR); if (ret != 0) { return ret; } switch (extension_type) { case MBEDTLS_TLS_EXT_SIG_ALG: MBEDTLS_SSL_DEBUG_MSG(3, ("found signature algorithms extension")); ret = mbedtls_ssl_parse_sig_alg_ext(ssl, p, p + extension_data_len); if (ret != 0) { return ret; } break; default: MBEDTLS_SSL_PRINT_EXT( 3, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, extension_type, "( ignored )"); break; } p += extension_data_len; } MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, handshake->received_extensions); /* Check that we consumed all the message. */ if (p != end) { MBEDTLS_SSL_DEBUG_MSG(1, ("CertificateRequest misaligned")); goto decode_error; } /* RFC 8446 section 4.3.2 * * The "signature_algorithms" extension MUST be specified */ if ((handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(SIG_ALG)) == 0) { MBEDTLS_SSL_DEBUG_MSG(3, ("no signature algorithms extension found")); goto decode_error; } ssl->handshake->client_auth = 1; return 0; decode_error: MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, MBEDTLS_ERR_SSL_DECODE_ERROR); return MBEDTLS_ERR_SSL_DECODE_ERROR; } /* * Handler for MBEDTLS_SSL_CERTIFICATE_REQUEST */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_certificate_request(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse certificate request")); MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_certificate_request_coordinate(ssl)); if (ret == SSL_CERTIFICATE_REQUEST_EXPECT_REQUEST) { unsigned char *buf; size_t buf_len; MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, &buf, &buf_len)); MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_certificate_request( ssl, buf, buf + buf_len)); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, buf, buf_len)); } else if (ret == SSL_CERTIFICATE_REQUEST_SKIP) { 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, ("<= parse certificate request")); return ret; } /* * Handler for MBEDTLS_SSL_SERVER_CERTIFICATE */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_server_certificate(mbedtls_ssl_context *ssl) { int ret; ret = mbedtls_ssl_tls13_process_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_process_certificate_verify(mbedtls_ssl_context *ssl) { int ret; ret = mbedtls_ssl_tls13_process_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 */ /* * Handler for MBEDTLS_SSL_SERVER_FINISHED */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_server_finished(mbedtls_ssl_context *ssl) { int ret; ret = mbedtls_ssl_tls13_process_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->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_ACCEPTED) { ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_SERVER_FINISHED_RECEIVED; mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_END_OF_EARLY_DATA); } else #endif /* MBEDTLS_SSL_EARLY_DATA */ { #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_CCS_AFTER_SERVER_FINISHED); #else mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE); #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ } return 0; } /* * Handler for MBEDTLS_SSL_CLIENT_CERTIFICATE */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_client_certificate(mbedtls_ssl_context *ssl) { int non_empty_certificate_msg = 0; MBEDTLS_SSL_DEBUG_MSG(1, ("Switch to handshake traffic keys for outbound traffic")); mbedtls_ssl_set_outbound_transform(ssl, ssl->handshake->transform_handshake); #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) if (ssl->handshake->client_auth) { int ret = mbedtls_ssl_tls13_write_certificate(ssl); if (ret != 0) { return ret; } if (mbedtls_ssl_own_cert(ssl) != NULL) { non_empty_certificate_msg = 1; } } else { MBEDTLS_SSL_DEBUG_MSG(2, ("skip write certificate")); } #endif if (non_empty_certificate_msg) { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY); } else { MBEDTLS_SSL_DEBUG_MSG(2, ("skip write certificate verify")); mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_FINISHED); } return 0; } #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) /* * Handler for MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_client_certificate_verify(mbedtls_ssl_context *ssl) { int ret = mbedtls_ssl_tls13_write_certificate_verify(ssl); if (ret == 0) { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_FINISHED); } return ret; } #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ /* * Handler for MBEDTLS_SSL_CLIENT_FINISHED */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_write_client_finished(mbedtls_ssl_context *ssl) { int ret; ret = mbedtls_ssl_tls13_write_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); return ret; } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_FLUSH_BUFFERS); return 0; } /* * Handler for MBEDTLS_SSL_FLUSH_BUFFERS */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_flush_buffers(mbedtls_ssl_context *ssl) { MBEDTLS_SSL_DEBUG_MSG(2, ("handshake: done")); 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_tls13_handshake_wrapup(ssl); mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); return 0; } #if defined(MBEDTLS_SSL_SESSION_TICKETS) #if defined(MBEDTLS_SSL_EARLY_DATA) /* From RFC 8446 section 4.2.10 * * struct { * select (Handshake.msg_type) { * case new_session_ticket: uint32 max_early_data_size; * ... * }; * } EarlyDataIndication; */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_new_session_ticket_early_data_ext( mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { mbedtls_ssl_session *session = ssl->session; MBEDTLS_SSL_CHK_BUF_READ_PTR(buf, end, 4); session->max_early_data_size = MBEDTLS_GET_UINT32_BE(buf, 0); mbedtls_ssl_tls13_session_set_ticket_flags( session, MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA); MBEDTLS_SSL_DEBUG_MSG( 3, ("received max_early_data_size: %u", (unsigned int) session->max_early_data_size)); return 0; } #endif /* MBEDTLS_SSL_EARLY_DATA */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_new_session_ticket_exts(mbedtls_ssl_context *ssl, const unsigned char *buf, const unsigned char *end) { mbedtls_ssl_handshake_params *handshake = ssl->handshake; const unsigned char *p = buf; handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE; while (p < end) { unsigned int extension_type; size_t extension_data_len; int ret; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, 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, end, extension_data_len); ret = mbedtls_ssl_tls13_check_received_extension( ssl, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, extension_type, MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_NST); if (ret != 0) { return ret; } switch (extension_type) { #if defined(MBEDTLS_SSL_EARLY_DATA) case MBEDTLS_TLS_EXT_EARLY_DATA: ret = ssl_tls13_parse_new_session_ticket_early_data_ext( ssl, p, p + extension_data_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_parse_new_session_ticket_early_data_ext", ret); } break; #endif /* MBEDTLS_SSL_EARLY_DATA */ default: MBEDTLS_SSL_PRINT_EXT( 3, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, extension_type, "( ignored )"); break; } p += extension_data_len; } MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, handshake->received_extensions); return 0; } /* * From RFC8446, page 74 * * 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; * */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_parse_new_session_ticket(mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end, unsigned char **ticket_nonce, size_t *ticket_nonce_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *p = buf; mbedtls_ssl_session *session = ssl->session; size_t ticket_len; unsigned char *ticket; size_t extensions_len; *ticket_nonce = NULL; *ticket_nonce_len = 0; /* * ticket_lifetime 4 bytes * ticket_age_add 4 bytes * ticket_nonce_len 1 byte */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 9); session->ticket_lifetime = MBEDTLS_GET_UINT32_BE(p, 0); MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_lifetime: %u", (unsigned int) session->ticket_lifetime)); if (session->ticket_lifetime > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME) { MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_lifetime exceeds 7 days.")); return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; } session->ticket_age_add = MBEDTLS_GET_UINT32_BE(p, 4); MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", (unsigned int) session->ticket_age_add)); *ticket_nonce_len = p[8]; p += 9; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, *ticket_nonce_len); *ticket_nonce = p; MBEDTLS_SSL_DEBUG_BUF(3, "ticket_nonce:", *ticket_nonce, *ticket_nonce_len); p += *ticket_nonce_len; /* Ticket */ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); ticket_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, ticket_len); MBEDTLS_SSL_DEBUG_BUF(3, "received ticket", p, ticket_len); /* Check if we previously received a ticket already. */ if (session->ticket != NULL || session->ticket_len > 0) { mbedtls_free(session->ticket); session->ticket = NULL; session->ticket_len = 0; } if ((ticket = mbedtls_calloc(1, ticket_len)) == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("ticket alloc failed")); return MBEDTLS_ERR_SSL_ALLOC_FAILED; } memcpy(ticket, p, ticket_len); p += ticket_len; session->ticket = ticket; session->ticket_len = ticket_len; /* Clear all flags in ticket_flags */ mbedtls_ssl_tls13_session_clear_ticket_flags( session, MBEDTLS_SSL_TLS1_3_TICKET_FLAGS_MASK); MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); extensions_len = MBEDTLS_GET_UINT16_BE(p, 0); p += 2; MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extensions_len); MBEDTLS_SSL_DEBUG_BUF(3, "ticket extension", p, extensions_len); ret = ssl_tls13_parse_new_session_ticket_exts(ssl, p, p + extensions_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_parse_new_session_ticket_exts", ret); return ret; } return 0; } /* Non negative return values for ssl_tls13_postprocess_new_session_ticket(). * - POSTPROCESS_NEW_SESSION_TICKET_SIGNAL, all good, we have to signal the * application that a valid ticket has been received. * - POSTPROCESS_NEW_SESSION_TICKET_DISCARD, no fatal error, we keep the * connection alive but we do not signal the ticket to the application. */ #define POSTPROCESS_NEW_SESSION_TICKET_SIGNAL … #define POSTPROCESS_NEW_SESSION_TICKET_DISCARD … MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_postprocess_new_session_ticket(mbedtls_ssl_context *ssl, unsigned char *ticket_nonce, size_t ticket_nonce_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_session *session = ssl->session; const mbedtls_ssl_ciphersuite_t *ciphersuite_info; psa_algorithm_t psa_hash_alg; int hash_length; if (session->ticket_lifetime == 0) { return POSTPROCESS_NEW_SESSION_TICKET_DISCARD; } #if defined(MBEDTLS_HAVE_TIME) /* Store ticket creation time */ session->ticket_reception_time = mbedtls_ms_time(); #endif ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(session->ciphersuite); if (ciphersuite_info == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } 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; } MBEDTLS_SSL_DEBUG_BUF(3, "resumption_master_secret", session->app_secrets.resumption_master_secret, hash_length); /* 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_len, session->resumption_key, hash_length); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(2, "Creating the ticket-resumed PSK failed", ret); return ret; } session->resumption_key_len = hash_length; MBEDTLS_SSL_DEBUG_BUF(3, "Ticket-resumed PSK", session->resumption_key, session->resumption_key_len); /* Set ticket_flags depends on the selected key exchange modes */ mbedtls_ssl_tls13_session_set_ticket_flags( session, ssl->conf->tls13_kex_modes); MBEDTLS_SSL_PRINT_TICKET_FLAGS(4, session->ticket_flags); return POSTPROCESS_NEW_SESSION_TICKET_SIGNAL; } /* * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_process_new_session_ticket(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf; size_t buf_len; unsigned char *ticket_nonce; size_t ticket_nonce_len; MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse new session ticket")); MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( ssl, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, &buf, &buf_len)); /* * We are about to update (maybe only partially) ticket data thus block * any session export for the time being. */ ssl->session->exported = 1; MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_new_session_ticket( ssl, buf, buf + buf_len, &ticket_nonce, &ticket_nonce_len)); MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_postprocess_new_session_ticket( ssl, ticket_nonce, ticket_nonce_len)); switch (ret) { case POSTPROCESS_NEW_SESSION_TICKET_SIGNAL: /* * All good, we have received a new valid ticket, session data can * be exported now and we signal the ticket to the application. */ ssl->session->exported = 0; ret = MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET; break; case POSTPROCESS_NEW_SESSION_TICKET_DISCARD: ret = 0; MBEDTLS_SSL_DEBUG_MSG(2, ("Discard new session ticket")); break; default: ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); cleanup: MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse new session ticket")); return ret; } #endif /* MBEDTLS_SSL_SESSION_TICKETS */ int mbedtls_ssl_tls13_handshake_client_step(mbedtls_ssl_context *ssl) { int ret = 0; switch (ssl->state) { case MBEDTLS_SSL_HELLO_REQUEST: mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); break; case MBEDTLS_SSL_CLIENT_HELLO: ret = mbedtls_ssl_write_client_hello(ssl); break; case MBEDTLS_SSL_SERVER_HELLO: ret = ssl_tls13_process_server_hello(ssl); break; case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS: ret = ssl_tls13_process_encrypted_extensions(ssl); break; #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) case MBEDTLS_SSL_CERTIFICATE_REQUEST: ret = ssl_tls13_process_certificate_request(ssl); break; case MBEDTLS_SSL_SERVER_CERTIFICATE: ret = ssl_tls13_process_server_certificate(ssl); break; case MBEDTLS_SSL_CERTIFICATE_VERIFY: ret = ssl_tls13_process_certificate_verify(ssl); break; #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ case MBEDTLS_SSL_SERVER_FINISHED: ret = ssl_tls13_process_server_finished(ssl); break; #if defined(MBEDTLS_SSL_EARLY_DATA) case MBEDTLS_SSL_END_OF_EARLY_DATA: ret = ssl_tls13_write_end_of_early_data(ssl); break; #endif case MBEDTLS_SSL_CLIENT_CERTIFICATE: ret = ssl_tls13_write_client_certificate(ssl); break; #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) case MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY: ret = ssl_tls13_write_client_certificate_verify(ssl); break; #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ case MBEDTLS_SSL_CLIENT_FINISHED: ret = ssl_tls13_write_client_finished(ssl); break; case MBEDTLS_SSL_FLUSH_BUFFERS: ret = ssl_tls13_flush_buffers(ssl); break; case MBEDTLS_SSL_HANDSHAKE_WRAPUP: ret = ssl_tls13_handshake_wrapup(ssl); break; /* * Injection of dummy-CCS's for middlebox compatibility */ #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) case MBEDTLS_SSL_CLIENT_CCS_BEFORE_2ND_CLIENT_HELLO: ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); if (ret != 0) { break; } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); break; case MBEDTLS_SSL_CLIENT_CCS_AFTER_SERVER_FINISHED: ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); if (ret != 0) { break; } mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE); break; #if defined(MBEDTLS_SSL_EARLY_DATA) case MBEDTLS_SSL_CLIENT_CCS_AFTER_CLIENT_HELLO: ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); if (ret == 0) { mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_HELLO); MBEDTLS_SSL_DEBUG_MSG( 1, ("Switch to early data keys for outbound traffic")); mbedtls_ssl_set_outbound_transform( ssl, ssl->handshake->transform_earlydata); ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_CAN_WRITE; } break; #endif /* MBEDTLS_SSL_EARLY_DATA */ #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ #if defined(MBEDTLS_SSL_SESSION_TICKETS) case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET: ret = ssl_tls13_process_new_session_ticket(ssl); break; #endif /* MBEDTLS_SSL_SESSION_TICKETS */ default: MBEDTLS_SSL_DEBUG_MSG(1, ("invalid state %d", ssl->state)); return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } return ret; } #endif /* MBEDTLS_SSL_CLI_C && MBEDTLS_SSL_PROTO_TLS1_3 */
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