/* * Copyright (C) 2014-2017 Red Hat, Inc. * * Author: Nikos Mavrogiannopoulos * * This file is part of GnuTLS. * * The GnuTLS is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program. If not, see * */ /* This file contains the code for the RFC7627 (ext master secret) TLS extension. */ #include "gnutls_int.h" #include "errors.h" #include "num.h" #include #include static int _gnutls_ext_master_secret_recv_params(gnutls_session_t session, const uint8_t * data, size_t data_size); static int _gnutls_ext_master_secret_send_params(gnutls_session_t session, gnutls_buffer_st * extdata); const hello_ext_entry_st ext_mod_ext_master_secret = { .name = "Extended Master Secret", .tls_id = 23, .gid = GNUTLS_EXTENSION_EXT_MASTER_SECRET, .client_parse_point = GNUTLS_EXT_MANDATORY, .server_parse_point = GNUTLS_EXT_MANDATORY, .validity = GNUTLS_EXT_FLAG_TLS | GNUTLS_EXT_FLAG_DTLS | GNUTLS_EXT_FLAG_CLIENT_HELLO | GNUTLS_EXT_FLAG_TLS12_SERVER_HELLO, .recv_func = _gnutls_ext_master_secret_recv_params, .send_func = _gnutls_ext_master_secret_send_params, .pack_func = NULL, .unpack_func = NULL, .deinit_func = NULL, .cannot_be_overriden = 1 }; #ifdef ENABLE_SSL3 static inline unsigned have_only_ssl3_enabled(gnutls_session_t session) { if (session->internals.priorities->protocol.num_priorities == 1 && session->internals.priorities->protocol.priorities[0] == GNUTLS_SSL3) return 1; return 0; } #endif /* * In case of a server: if an EXT_MASTER_SECRET extension type is received then it * sets a flag into the session security parameters. * */ static int _gnutls_ext_master_secret_recv_params(gnutls_session_t session, const uint8_t * data, size_t _data_size) { ssize_t data_size = _data_size; if ((session->internals.flags & GNUTLS_NO_EXTENSIONS) || session->internals.priorities->no_extensions || session->internals.no_ext_master_secret != 0) { return 0; } if (data_size != 0) { return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH); } #ifdef ENABLE_SSL3 if (session->security_parameters.entity == GNUTLS_CLIENT) { const version_entry_st *ver = get_version(session); if (unlikely(ver == NULL)) return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR); if (ver->id != GNUTLS_SSL3) session->security_parameters.ext_master_secret = 1; /* do not enable ext master secret if SSL 3.0 is the only protocol supported by server */ } else if (!have_only_ssl3_enabled(session)) #endif session->security_parameters.ext_master_secret = 1; return 0; } /* returns data_size or a negative number on failure */ static int _gnutls_ext_master_secret_send_params(gnutls_session_t session, gnutls_buffer_st * extdata) { if ((session->internals.flags & GNUTLS_NO_EXTENSIONS) || session->internals.priorities->no_extensions != 0 || session->internals.no_ext_master_secret != 0) { session->security_parameters.ext_master_secret = 0; return 0; } /* this function sends the client extension data */ #ifdef ENABLE_SSL3 if (session->security_parameters.entity == GNUTLS_CLIENT) { if (have_only_ssl3_enabled(session)) return 0; /* this extension isn't available for SSL 3.0 */ return GNUTLS_E_INT_RET_0; } else { /* server side */ const version_entry_st *ver = get_version(session); if (unlikely(ver == NULL)) return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR); if (ver->id != GNUTLS_SSL3 && session->security_parameters.ext_master_secret != 0) return GNUTLS_E_INT_RET_0; } return 0; #else if (session->security_parameters.entity == GNUTLS_CLIENT || session->security_parameters.ext_master_secret != 0) return GNUTLS_E_INT_RET_0; return 0; #endif } /** * gnutls_session_ext_master_secret_status: * @session: is a #gnutls_session_t type. * * Get the status of the extended master secret extension negotiation. * This is in accordance to RFC7627. That information is also * available to the more generic gnutls_session_get_flags(). * * Returns: Non-zero if the negotiation was successful or zero otherwise. **/ unsigned gnutls_session_ext_master_secret_status(gnutls_session_t session) { return session->security_parameters.ext_master_secret; }