/*
* TLS 1.3 server-side functions
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "common.h"
#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3)
#include "mbedtls/debug.h"
#include "mbedtls/error.h"
#include "mbedtls/platform.h"
#include "ssl_misc.h"
#include "ssl_tls13_keys.h"
#include "ssl_debug_helpers.h"
#if defined(MBEDTLS_ECP_C)
#include "mbedtls/ecp.h"
#endif /* MBEDTLS_ECP_C */
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif /* MBEDTLS_PLATFORM_C */
#include "ssl_misc.h"
#include "ssl_tls13_keys.h"
#include "ssl_debug_helpers.h"
/* From RFC 8446:
* struct {
* ProtocolVersion versions<2..254>;
* } SupportedVersions;
*/
static int ssl_tls13_parse_supported_versions_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
const unsigned char *p = buf;
size_t versions_len;
const unsigned char *versions_end;
uint16_t tls_version;
int tls13_supported = 0;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
versions_len = p[0];
p += 1;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, versions_len );
versions_end = p + versions_len;
while( p < versions_end )
{
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, versions_end, 2 );
tls_version = mbedtls_ssl_read_version( p, ssl->conf->transport );
p += 2;
/* In this implementation we only support TLS 1.3 and DTLS 1.3. */
if( tls_version == MBEDTLS_SSL_VERSION_TLS1_3 )
{
tls13_supported = 1;
break;
}
}
if( !tls13_supported )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS 1.3 is not supported by the client" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION,
MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
return( MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
}
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Negotiated version. Supported is [%04x]",
(unsigned int)tls_version ) );
return( 0 );
}
#if defined(MBEDTLS_ECDH_C)
/*
*
* From RFC 8446:
* enum {
* ... (0xFFFF)
* } NamedGroup;
* struct {
* NamedGroup named_group_list<2..2^16-1>;
* } NamedGroupList;
*/
static int ssl_tls13_parse_supported_groups_ext(
mbedtls_ssl_context *ssl,
const unsigned char *buf, const unsigned char *end )
{
const unsigned char *p = buf;
size_t named_group_list_len;
const unsigned char *named_group_list_end;
MBEDTLS_SSL_DEBUG_BUF( 3, "supported_groups extension", p, end - buf );
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
named_group_list_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, named_group_list_len );
named_group_list_end = p + named_group_list_len;
ssl->handshake->hrr_selected_group = 0;
while( p < named_group_list_end )
{
uint16_t named_group;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, named_group_list_end, 2 );
named_group = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "got named group: %d", named_group ) );
if( ! mbedtls_ssl_named_group_is_offered( ssl, named_group ) ||
! mbedtls_ssl_named_group_is_supported( named_group ) ||
ssl->handshake->hrr_selected_group != 0 )
{
continue;
}
MBEDTLS_SSL_DEBUG_MSG(
2, ( "add named group (%04x) into received list.",
named_group ) );
ssl->handshake->hrr_selected_group = named_group;
}
return( 0 );
}
#endif /* MBEDTLS_ECDH_C */
#define SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH 1
#if defined(MBEDTLS_ECDH_C)
/*
* ssl_tls13_parse_key_shares_ext() verifies whether the information in the
* extension is correct and stores the first acceptable key share and its associated group.
*
* Possible return values are:
* - 0: Successful processing of the client provided key share extension.
* - SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH: The key shares provided by the client
* does not match a group supported by the server. A HelloRetryRequest will
* be needed.
* - A negative value for fatal errors.
*/
static int ssl_tls13_parse_key_shares_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char const *p = buf;
unsigned char const *client_shares_end;
size_t client_shares_len, key_exchange_len;
int match_found = 0;
/* From RFC 8446:
*
* struct {
* KeyShareEntry client_shares<0..2^16-1>;
* } KeyShareClientHello;
*
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
client_shares_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, client_shares_len );
ssl->handshake->offered_group_id = 0;
client_shares_end = p + client_shares_len;
/* We try to find a suitable key share entry and copy it to the
* handshake context. Later, we have to find out whether we can do
* something with the provided key share or whether we have to
* dismiss it and send a HelloRetryRequest message.
*/
for( ; p < client_shares_end; p += key_exchange_len )
{
uint16_t group;
/*
* struct {
* NamedGroup group;
* opaque key_exchange<1..2^16-1>;
* } KeyShareEntry;
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, client_shares_end, 4 );
group = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
key_exchange_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, client_shares_end, key_exchange_len );
/* Continue parsing even if we have already found a match,
* for input validation purposes.
*/
if( match_found == 1 )
continue;
if( ! mbedtls_ssl_named_group_is_offered( ssl, group ) ||
! mbedtls_ssl_named_group_is_supported( group ) )
{
continue;
}
/*
* For now, we only support ECDHE groups.
*/
if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) )
{
const mbedtls_ecp_curve_info *curve_info =
mbedtls_ecp_curve_info_from_tls_id( group );
((void) curve_info);
MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) );
ret = mbedtls_ssl_tls13_read_public_ecdhe_share(
ssl, p - 2, key_exchange_len + 2 );
if( ret != 0 )
return( ret );
match_found = 1;
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Unrecognized NamedGroup %u",
(unsigned) group ) );
continue;
}
ssl->handshake->offered_group_id = group;
}
if( match_found == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "no matching key share" ) );
return( SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH );
}
return( 0 );
}
#endif /* MBEDTLS_ECDH_C */
#if defined(MBEDTLS_DEBUG_C)
static void ssl_tls13_debug_print_client_hello_exts( mbedtls_ssl_context *ssl )
{
((void) ssl);
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Supported Extensions:" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- KEY_SHARE_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_KEY_SHARE ) > 0 ) ? "TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- PSK_KEY_EXCHANGE_MODES_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) > 0 ) ?
"TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- PRE_SHARED_KEY_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) > 0 ) ? "TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- SIGNATURE_ALGORITHM_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_SIG_ALG ) > 0 ) ? "TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- SUPPORTED_GROUPS_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_SUPPORTED_GROUPS ) >0 ) ?
"TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- SUPPORTED_VERSION_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS ) > 0 ) ?
"TRUE" : "FALSE" ) );
#if defined ( MBEDTLS_SSL_SERVER_NAME_INDICATION )
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- SERVERNAME_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_SERVERNAME ) > 0 ) ?
"TRUE" : "FALSE" ) );
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
}
#endif /* MBEDTLS_DEBUG_C */
static int ssl_tls13_client_hello_has_exts( mbedtls_ssl_context *ssl,
int exts_mask )
{
int masked = ssl->handshake->extensions_present & exts_mask;
return( masked == exts_mask );
}
static int ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange(
mbedtls_ssl_context *ssl )
{
return( ssl_tls13_client_hello_has_exts( ssl,
MBEDTLS_SSL_EXT_SUPPORTED_GROUPS |
MBEDTLS_SSL_EXT_KEY_SHARE |
MBEDTLS_SSL_EXT_SIG_ALG ) );
}
static int ssl_tls13_check_ephemeral_key_exchange( mbedtls_ssl_context *ssl )
{
if( !mbedtls_ssl_conf_tls13_ephemeral_enabled( ssl ) )
return( 0 );
if( !ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange( ssl ) )
return( 0 );
ssl->handshake->tls13_kex_modes =
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL;
return( 1 );
}
/*
*
* STATE HANDLING: ClientHello
*
* There are three possible classes of outcomes when parsing the ClientHello:
*
* 1) The ClientHello was well-formed and matched the server's configuration.
*
* In this case, the server progresses to sending its ServerHello.
*
* 2) The ClientHello was well-formed but didn't match the server's
* configuration.
*
* For example, the client might not have offered a key share which
* the server supports, or the server might require a cookie.
*
* In this case, the server sends a HelloRetryRequest.
*
* 3) The ClientHello was ill-formed
*
* In this case, we abort the handshake.
*
*/
/*
* Structure of this message:
*
* uint16 ProtocolVersion;
* opaque Random[32];
* uint8 CipherSuite[2]; // Cryptographic suite selector
*
* struct {
* ProtocolVersion legacy_version = 0x0303; // TLS v1.2
* Random random;
* opaque legacy_session_id<0..32>;
* CipherSuite cipher_suites<2..2^16-2>;
* opaque legacy_compression_methods<1..2^8-1>;
* Extension extensions<8..2^16-1>;
* } ClientHello;
*/
#define SSL_CLIENT_HELLO_OK 0
#define SSL_CLIENT_HELLO_HRR_REQUIRED 1
static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const unsigned char *p = buf;
size_t legacy_session_id_len;
const unsigned char *cipher_suites;
size_t cipher_suites_len;
const unsigned char *cipher_suites_end;
size_t extensions_len;
const unsigned char *extensions_end;
const mbedtls_ssl_ciphersuite_t* ciphersuite_info;
ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
/*
* ClientHello layout:
* 0 . 1 protocol version
* 2 . 33 random bytes
* 34 . 34 session id length ( 1 byte )
* 35 . 34+x session id
* .. . .. ciphersuite list length ( 2 bytes )
* .. . .. ciphersuite list
* .. . .. compression alg. list length ( 1 byte )
* .. . .. compression alg. list
* .. . .. extensions length ( 2 bytes, optional )
* .. . .. extensions ( optional )
*/
/*
* Minimal length ( with everything empty and extensions ommitted ) is
* 2 + 32 + 1 + 2 + 1 = 38 bytes. Check that first, so that we can
* read at least up to session id length without worrying.
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 38 );
/* ...
* ProtocolVersion legacy_version = 0x0303; // TLS 1.2
* ...
* with ProtocolVersion defined as:
* uint16 ProtocolVersion;
*/
if( mbedtls_ssl_read_version( p, ssl->conf->transport ) !=
MBEDTLS_SSL_VERSION_TLS1_2 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Unsupported version of TLS." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION,
MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
return ( MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
}
p += 2;
/*
* Only support TLS 1.3 currently, temporarily set the version.
*/
ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_3;
/* ---
* Random random;
* ---
* with Random defined as:
* opaque Random[32];
*/
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes",
p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
memcpy( &ssl->handshake->randbytes[0], p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN;
/* ---
* opaque legacy_session_id<0..32>;
* ---
*/
legacy_session_id_len = p[0];
p++;
if( legacy_session_id_len > sizeof( ssl->session_negotiate->id ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
ssl->session_negotiate->id_len = legacy_session_id_len;
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, session id",
p, legacy_session_id_len );
/*
* Check we have enough data for the legacy session identifier
* and the ciphersuite list length.
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, legacy_session_id_len + 2 );
memcpy( &ssl->session_negotiate->id[0], p, legacy_session_id_len );
p += legacy_session_id_len;
cipher_suites_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
/* Check we have enough data for the ciphersuite list, the legacy
* compression methods and the length of the extensions.
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, cipher_suites_len + 2 + 2 );
/* ---
* CipherSuite cipher_suites<2..2^16-2>;
* ---
* with CipherSuite defined as:
* uint8 CipherSuite[2];
*/
cipher_suites = p;
cipher_suites_end = p + cipher_suites_len;
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, ciphersuitelist",
p, cipher_suites_len );
/*
* Search for a matching ciphersuite
*/
int ciphersuite_match = 0;
for ( ; p < cipher_suites_end; p += 2 )
{
uint16_t cipher_suite;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, cipher_suites_end, 2 );
cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 );
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 ) )
continue;
ssl->session_negotiate->ciphersuite = cipher_suite;
ssl->handshake->ciphersuite_info = ciphersuite_info;
ciphersuite_match = 1;
break;
}
if( !ciphersuite_match )
{
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return ( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "selected ciphersuite: %s",
ciphersuite_info->name ) );
p = cipher_suites + cipher_suites_len;
/* ...
* opaque legacy_compression_methods<1..2^8-1>;
* ...
*/
if( p[0] != 1 || p[1] != MBEDTLS_SSL_COMPRESS_NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad legacy compression method" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return ( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
p += 2;
/* ---
* Extension extensions<8..2^16-1>;
* ---
* with Extension defined as:
* struct {
* ExtensionType extension_type;
* opaque extension_data<0..2^16-1>;
* } Extension;
*/
extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, extensions_len );
extensions_end = p + extensions_len;
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello extensions", p, extensions_len );
while( p < extensions_end )
{
unsigned int extension_type;
size_t extension_data_len;
const unsigned char *extension_data_end;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extensions_end, 4 );
extension_type = MBEDTLS_GET_UINT16_BE( p, 0 );
extension_data_len = MBEDTLS_GET_UINT16_BE( p, 2 );
p += 4;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extensions_end, extension_data_len );
extension_data_end = p + extension_data_len;
switch( extension_type )
{
#if defined(MBEDTLS_ECDH_C)
case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found supported group extension" ) );
/* Supported Groups Extension
*
* When sent by the client, the "supported_groups" extension
* indicates the named groups which the client supports,
* ordered from most preferred to least preferred.
*/
ret = ssl_tls13_parse_supported_groups_ext( ssl, p,
extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"mbedtls_ssl_parse_supported_groups_ext", ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS;
break;
#endif /* MBEDTLS_ECDH_C */
#if defined(MBEDTLS_ECDH_C)
case MBEDTLS_TLS_EXT_KEY_SHARE:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found key share extension" ) );
/*
* Key Share Extension
*
* When sent by the client, the "key_share" extension
* contains the endpoint's cryptographic parameters for
* ECDHE/DHE key establishment methods.
*/
ret = ssl_tls13_parse_key_shares_ext( ssl, p, extension_data_end );
if( ret == SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "HRR needed " ) );
ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
}
if( ret != 0 )
return( ret );
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE;
break;
#endif /* MBEDTLS_ECDH_C */
case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found supported versions extension" ) );
ret = ssl_tls13_parse_supported_versions_ext(
ssl, p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
( "ssl_tls13_parse_supported_versions_ext" ), ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS;
break;
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
case MBEDTLS_TLS_EXT_SIG_ALG:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found signature_algorithms extension" ) );
ret = mbedtls_ssl_tls13_parse_sig_alg_ext( ssl, p,
extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
( "ssl_parse_supported_signature_algorithms_server_ext ( %d )",
ret ) );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SIG_ALG;
break;
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
default:
MBEDTLS_SSL_DEBUG_MSG( 3,
( "unknown extension found: %ud ( ignoring )",
extension_type ) );
}
p += extension_data_len;
}
/* Update checksum with either
* - The entire content of the CH message, if no PSK extension is present
* - The content up to but excluding the PSK extension, if present.
*/
mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO,
buf, p - buf );
/* List all the extensions we have received */
#if defined(MBEDTLS_DEBUG_C)
ssl_tls13_debug_print_client_hello_exts( ssl );
#endif /* MBEDTLS_DEBUG_C */
/*
* Here we only support the ephemeral or (EC)DHE key echange mode
*/
if( !ssl_tls13_check_ephemeral_key_exchange( ssl ) )
{
MBEDTLS_SSL_DEBUG_MSG(
1,
( "ClientHello message misses mandatory extensions." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION ,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
return( 0 );
}
static int ssl_tls13_postprocess_client_hello( mbedtls_ssl_context* ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
ret = mbedtls_ssl_tls13_key_schedule_stage_early( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"mbedtls_ssl_tls1_3_key_schedule_stage_early", ret );
return( ret );
}
return( 0 );
}
/*
* Main entry point from the state machine; orchestrates the otherfunctions.
*/
static int ssl_tls13_process_client_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char* buf = NULL;
size_t buflen = 0;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse client hello" ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_fetch_handshake_msg(
ssl, MBEDTLS_SSL_HS_CLIENT_HELLO,
&buf, &buflen ) );
MBEDTLS_SSL_PROC_CHK_NEG( ssl_tls13_parse_client_hello( ssl, buf,
buf + buflen ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_client_hello( ssl ) );
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_HELLO );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse client hello" ) );
return( ret );
}
/*
* Handler for MBEDTLS_SSL_SERVER_HELLO
*/
static int ssl_tls13_prepare_server_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *server_randbytes =
ssl->handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN;
if( ssl->conf->f_rng == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "no RNG provided" ) );
return( MBEDTLS_ERR_SSL_NO_RNG );
}
if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng, server_randbytes,
MBEDTLS_SERVER_HELLO_RANDOM_LEN ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "f_rng", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, random bytes", server_randbytes,
MBEDTLS_SERVER_HELLO_RANDOM_LEN );
#if defined(MBEDTLS_HAVE_TIME)
ssl->session_negotiate->start = time( NULL );
#endif /* MBEDTLS_HAVE_TIME */
return( ret );
}
/*
* ssl_tls13_write_server_hello_supported_versions_ext ():
*
* struct {
* ProtocolVersion selected_version;
* } SupportedVersions;
*/
static int ssl_tls13_write_server_hello_supported_versions_ext(
mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
*out_len = 0;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, write selected version" ) );
/* Check if we have space to write the extension:
* - extension_type (2 bytes)
* - extension_data_length (2 bytes)
* - selected_version (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( buf, end, 6 );
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, buf, 0 );
MBEDTLS_PUT_UINT16_BE( 2, buf, 2 );
mbedtls_ssl_write_version( buf + 4,
ssl->conf->transport,
ssl->tls_version );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "supported version: [%04x]",
ssl->tls_version ) );
*out_len = 6;
return( 0 );
}
/* Generate and export a single key share. For hybrid KEMs, this can
* be called multiple times with the different components of the hybrid. */
static int ssl_tls13_generate_and_write_key_share( mbedtls_ssl_context *ssl,
uint16_t named_group,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
*out_len = 0;
#if defined(MBEDTLS_ECDH_C)
if( mbedtls_ssl_tls13_named_group_is_ecdhe( named_group ) )
{
ret = mbedtls_ssl_tls13_generate_and_write_ecdh_key_exchange(
ssl, named_group, buf, end, out_len );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, "mbedtls_ssl_tls13_generate_and_write_ecdh_key_exchange",
ret );
return( ret );
}
}
else
#endif /* MBEDTLS_ECDH_C */
if( 0 /* Other kinds of KEMs */ )
{
}
else
{
((void) ssl);
((void) named_group);
((void) buf);
((void) end);
ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
return( ret );
}
/*
* ssl_tls13_write_key_share_ext
*
* Structure of key_share extension in ServerHello:
*
* struct {
* NamedGroup group;
* opaque key_exchange<1..2^16-1>;
* } KeyShareEntry;
* struct {
* KeyShareEntry server_share;
* } KeyShareServerHello;
*/
static int ssl_tls13_write_key_share_ext( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
uint16_t group = ssl->handshake->offered_group_id;
unsigned char *server_share = buf + 4;
size_t key_exchange_length;
*out_len = 0;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding key share extension" ) );
/* Check if we have space for header and length fields:
* - extension_type (2 bytes)
* - extension_data_length (2 bytes)
* - group (2 bytes)
* - key_exchange_length (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 8 );
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_KEY_SHARE, p, 0 );
MBEDTLS_PUT_UINT16_BE( group, server_share, 0 );
p += 8;
/* When we introduce PQC-ECDHE hybrids, we'll want to call this
* function multiple times. */
ret = ssl_tls13_generate_and_write_key_share(
ssl, group, server_share + 4, end, &key_exchange_length );
if( ret != 0 )
return( ret );
p += key_exchange_length;
MBEDTLS_PUT_UINT16_BE( key_exchange_length, server_share + 2, 0 );
MBEDTLS_PUT_UINT16_BE( p - server_share, buf, 2 );
*out_len = p - buf;
return( 0 );
}
/*
* Structure of ServerHello message:
*
* struct {
* ProtocolVersion legacy_version = 0x0303; // TLS v1.2
* Random random;
* opaque legacy_session_id_echo<0..32>;
* CipherSuite cipher_suite;
* uint8 legacy_compression_method = 0;
* Extension extensions<6..2^16-1>;
* } ServerHello;
*/
static int ssl_tls13_write_server_hello_body( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
unsigned char *p_extensions_len;
size_t output_len; /* Length of buffer used by function */
*out_len = 0;
/* ...
* ProtocolVersion legacy_version = 0x0303; // TLS 1.2
* ...
* with ProtocolVersion defined as:
* uint16 ProtocolVersion;
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
MBEDTLS_PUT_UINT16_BE( 0x0303, p, 0 );
p += 2;
/* ...
* Random random;
* ...
* with Random defined as:
* opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN];
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN );
memcpy( p, &ssl->handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN],
MBEDTLS_SERVER_HELLO_RANDOM_LEN );
MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, random bytes",
p, MBEDTLS_SERVER_HELLO_RANDOM_LEN );
p += MBEDTLS_SERVER_HELLO_RANDOM_LEN;
/* ...
* opaque legacy_session_id_echo<0..32>;
* ...
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 1 + ssl->session_negotiate->id_len );
*p++ = (unsigned char)ssl->session_negotiate->id_len;
if( ssl->session_negotiate->id_len > 0 )
{
memcpy( p, &ssl->session_negotiate->id[0],
ssl->session_negotiate->id_len );
p += ssl->session_negotiate->id_len;
MBEDTLS_SSL_DEBUG_BUF( 3, "session id", ssl->session_negotiate->id,
ssl->session_negotiate->id_len );
}
/* ...
* CipherSuite cipher_suite;
* ...
* with CipherSuite defined as:
* uint8 CipherSuite[2];
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
MBEDTLS_PUT_UINT16_BE( ssl->session_negotiate->ciphersuite, p, 0 );
p += 2;
MBEDTLS_SSL_DEBUG_MSG( 3,
( "server hello, chosen ciphersuite: %s ( id=%d )",
mbedtls_ssl_get_ciphersuite_name(
ssl->session_negotiate->ciphersuite ),
ssl->session_negotiate->ciphersuite ) );
/* ...
* uint8 legacy_compression_method = 0;
* ...
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 1 );
*p++ = 0x0;
/* ...
* Extension extensions<6..2^16-1>;
* ...
* struct {
* ExtensionType extension_type; (2 bytes)
* opaque extension_data<0..2^16-1>;
* } Extension;
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
p_extensions_len = p;
p += 2;
if( ( ret = ssl_tls13_write_server_hello_supported_versions_ext(
ssl, p, end, &output_len ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, "ssl_tls13_write_server_hello_supported_versions_ext", ret );
return( ret );
}
p += output_len;
if( mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) )
{
ret = ssl_tls13_write_key_share_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
}
MBEDTLS_PUT_UINT16_BE( p - p_extensions_len - 2, p_extensions_len, 0 );
MBEDTLS_SSL_DEBUG_BUF( 4, "server hello extensions",
p_extensions_len, p - p_extensions_len );
*out_len = p - buf;
MBEDTLS_SSL_DEBUG_BUF( 3, "server hello", buf, *out_len );
return( ret );
}
static int ssl_tls13_finalize_write_server_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
ret = mbedtls_ssl_tls13_compute_handshake_transform( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"mbedtls_ssl_tls13_compute_handshake_transform",
ret );
return( ret );
}
mbedtls_ssl_set_outbound_transform( ssl,
ssl->handshake->transform_handshake );
MBEDTLS_SSL_DEBUG_MSG(
3, ( "switching to handshake transform for outbound data" ) );
return( ret );
}
static int ssl_tls13_write_server_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf;
size_t buf_len, msg_len;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server hello" ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_prepare_server_hello( ssl ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_start_handshake_msg( ssl,
MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_server_hello_body( ssl, buf,
buf + buf_len,
&msg_len ) );
mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg(
ssl, buf_len, msg_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_write_server_hello( ssl ) );
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write server hello" ) );
return( ret );
}
/*
* Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS
*/
/*
* struct {
* Extension extensions<0..2 ^ 16 - 1>;
* } EncryptedExtensions;
*
*/
static int ssl_tls13_write_encrypted_extensions_body( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
unsigned char *p = buf;
size_t extensions_len = 0;
unsigned char *p_extensions_len;
*out_len = 0;
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
p_extensions_len = p;
p += 2;
((void) ssl);
extensions_len = ( p - p_extensions_len ) - 2;
MBEDTLS_PUT_UINT16_BE( extensions_len, p_extensions_len, 0 );
*out_len = p - buf;
MBEDTLS_SSL_DEBUG_BUF( 4, "encrypted extensions", buf, *out_len );
return( 0 );
}
static int ssl_tls13_write_encrypted_extensions( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf;
size_t buf_len, msg_len;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write encrypted extensions" ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_start_handshake_msg( ssl,
MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, &buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_encrypted_extensions_body(
ssl, buf, buf + buf_len, &msg_len ) );
mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, msg_len );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg(
ssl, buf_len, msg_len ) );
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
if( mbedtls_ssl_tls13_some_psk_enabled( ssl ) )
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_FINISHED );
else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CERTIFICATE_REQUEST );
#else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_FINISHED );
#endif
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write encrypted extensions" ) );
return( ret );
}
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
#define SSL_CERTIFICATE_REQUEST_SEND_REQUEST 0
#define SSL_CERTIFICATE_REQUEST_SKIP 1
/* Coordination:
* Check whether a CertificateRequest message should be written.
* Returns a negative code on failure, or
* - SSL_CERTIFICATE_REQUEST_SEND_REQUEST
* - SSL_CERTIFICATE_REQUEST_SKIP
* indicating if the writing of the CertificateRequest
* should be skipped or not.
*/
static int ssl_tls13_certificate_request_coordinate( mbedtls_ssl_context *ssl )
{
int authmode;
authmode = ssl->conf->authmode;
if( authmode == MBEDTLS_SSL_VERIFY_NONE )
return( SSL_CERTIFICATE_REQUEST_SKIP );
return( SSL_CERTIFICATE_REQUEST_SEND_REQUEST );
}
/*
* struct {
* opaque certificate_request_context<0..2^8-1>;
* Extension extensions<2..2^16-1>;
* } CertificateRequest;
*
*/
static int ssl_tls13_write_certificate_request_body( mbedtls_ssl_context *ssl,
unsigned char *buf,
const unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
size_t output_len = 0;
unsigned char *p_extensions_len;
*out_len = 0;
/* Check if we have enough space:
* - certificate_request_context (1 byte)
* - extensions length (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 3 );
/*
* Write certificate_request_context
*/
/*
* We use a zero length context for the normal handshake
* messages. For post-authentication handshake messages
* this request context would be set to a non-zero value.
*/
*p++ = 0x0;
/*
* Write extensions
*/
/* The extensions must contain the signature_algorithms. */
p_extensions_len = p;
p += 2;
ret = mbedtls_ssl_write_sig_alg_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
MBEDTLS_PUT_UINT16_BE( p - p_extensions_len - 2, p_extensions_len, 0 );
*out_len = p - buf;
return( 0 );
}
static int ssl_tls13_write_certificate_request( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate request" ) );
MBEDTLS_SSL_PROC_CHK_NEG( ssl_tls13_certificate_request_coordinate( ssl ) );
if( ret == SSL_CERTIFICATE_REQUEST_SEND_REQUEST )
{
unsigned char *buf;
size_t buf_len, msg_len;
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_start_handshake_msg( ssl,
MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, &buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_certificate_request_body(
ssl, buf, buf + buf_len, &msg_len ) );
mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, buf, msg_len );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg(
ssl, buf_len, msg_len ) );
}
else if( ret == SSL_CERTIFICATE_REQUEST_SKIP )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate request" ) );
ret = 0;
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
goto cleanup;
}
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_CERTIFICATE );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write certificate request" ) );
return( ret );
}
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
/*
* TLS 1.3 State Machine -- server side
*/
int mbedtls_ssl_tls13_handshake_server_step( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "tls13 server state: %s(%d)",
mbedtls_ssl_states_str( ssl->state ),
ssl->state ) );
switch( ssl->state )
{
/* start state */
case MBEDTLS_SSL_HELLO_REQUEST:
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_HELLO );
ret = 0;
break;
case MBEDTLS_SSL_CLIENT_HELLO:
ret = ssl_tls13_process_client_hello( ssl );
if( ret != 0 )
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_process_client_hello", ret );
break;
case MBEDTLS_SSL_SERVER_HELLO:
ret = ssl_tls13_write_server_hello( ssl );
break;
case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS:
ret = ssl_tls13_write_encrypted_extensions( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_encrypted_extensions", ret );
return( ret );
}
break;
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
case MBEDTLS_SSL_CERTIFICATE_REQUEST:
ret = ssl_tls13_write_certificate_request( ssl );
break;
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
default:
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) );
return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
}
return( ret );
}
#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_TLS1_3 */