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/*
* 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 <http://www.gnu.org/licenses/>
*
*/
/* This file contains the code for the RFC7627 (ext master secret) TLS extension.
*/
#include "gnutls_int.h"
#include "errors.h"
#include "num.h"
#include <hello_ext.h>
#include <ext/ext_master_secret.h>
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,
.parse_type = 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;
}
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