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mbedtls/library/ssl_tls13_server.c
XiaokangQian ed582dd023 Update based on comments 
Remove cookie support from server side
Change code to align with coding styles
Re-order functions of client_hello

Change-Id: If31509ece402f8276e6cac37f261e0b166d05e18
Signed-off-by: XiaokangQian <xiaokang.qian@arm.com>
2022-04-20 07:43:48 +00:00

847 lines
28 KiB
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/*
* 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 "ssl_misc.h"
#include "ssl_tls13_keys.h"
#include "ssl_debug_helpers.h"
#include <string.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 */
/* From RFC 8446:
* struct {
* select (Handshake.msg_type) {
* case client_hello:
* ProtocolVersion versions<2..254>;
* case server_hello: // and HelloRetryRequest
* ProtocolVersion selected_version;
* };
* } SupportedVersions;
*/
static int ssl_tls13_parse_supported_versions_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
size_t versions_len;
int tls13_supported = 0;
int major_ver, minor_ver;
const unsigned char *p = buf;
const unsigned char *versions_end;
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 );
if( versions_len % 2 != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid supported version list length %" MBEDTLS_PRINTF_SIZET,
versions_len ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
versions_end = p + versions_len;
while( p < versions_end )
{
mbedtls_ssl_read_version( &major_ver, &minor_ver, ssl->conf->transport, p );
/* In this implementation we only support TLS 1.3 and DTLS 1.3. */
if( major_ver == MBEDTLS_SSL_MAJOR_VERSION_3 &&
minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
{
tls13_supported = 1;
break;
}
p += 2;
}
if( tls13_supported == 0 )
{
/* Here we only support TLS 1.3, we need report "bad protocol" if it
* doesn't support TLS 1.2.
*/
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 [%d:%d]",
major_ver, minor_ver ) );
ssl->major_ver = major_ver;
ssl->minor_ver = minor_ver;
return( 0 );
}
#if ( defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) )
/* This function parses the TLS 1.3 supported_groups extension and
* stores the received groups in ssl->handshake->curves.
*
* From RFC 8446:
* enum {
* ... (0xFFFF)
* } NamedGroup;
* struct {
* NamedGroup named_group_list<2..2^16-1>;
* } NamedGroupList;
*/
static int mbedtls_ssl_tls13_parse_supported_groups_ext(
mbedtls_ssl_context *ssl,
const unsigned char *buf, const unsigned char *end )
{
size_t named_group_list_len, curve_list_len;
const unsigned char *p = buf;
const mbedtls_ecp_curve_info *curve_info, **curves;
const unsigned char *extentions_end;
MBEDTLS_SSL_DEBUG_BUF( 3, "supported_groups extension", p, end - buf );
named_group_list_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, named_group_list_len );
if( named_group_list_len % 2 != 0 )
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
/* At the moment, this can happen when receiving a second
* ClientHello after an HRR. We should properly reset the
* state upon receiving an HRR, in which case we should
* not observe handshake->curves already being allocated. */
if( ssl->handshake->curves != NULL )
{
mbedtls_free( ssl->handshake->curves );
ssl->handshake->curves = NULL;
}
/* Don't allow our peer to make us allocate too much memory,
* and leave room for a final 0
*/
curve_list_len = named_group_list_len / 2 + 1;
if( curve_list_len > MBEDTLS_ECP_DP_MAX )
curve_list_len = MBEDTLS_ECP_DP_MAX;
if( ( curves = mbedtls_calloc( curve_list_len, sizeof( *curves ) ) ) == NULL )
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
extentions_end = p + named_group_list_len;
ssl->handshake->curves = curves;
while ( p < extentions_end && curve_list_len > 1 )
{
uint16_t tls_grp_id = MBEDTLS_GET_UINT16_BE( p, 0 );
curve_info = mbedtls_ecp_curve_info_from_tls_id( tls_grp_id );
/* mbedtls_ecp_curve_info_from_tls_id() uses the mbedtls_ecp_curve_info
* data structure (defined in ecp.c), which only includes the list of
* curves implemented. Hence, we only add curves that are also supported
* and implemented by the server.
*/
if( curve_info != NULL )
{
*curves++ = curve_info;
MBEDTLS_SSL_DEBUG_MSG( 4, ( "supported curve: %s", curve_info->name ) );
curve_list_len--;
}
p += 2;
}
return( 0 );
}
#endif /* MBEDTLS_ECDH_C || ( MBEDTLS_ECDSA_C */
#if defined(MBEDTLS_ECDH_C)
/*
* ssl_tls13_parse_key_shares_ext() verifies whether the information in the
* extension is correct and stores the provided key shares. Whether this is an
* acceptable key share depends on the selected ciphersuite.
*
* Possible return values are:
* - 0: Successful processing of the client provided key share extension.
* - MBEDTLS_ERR_SSL_HRR_REQUIRED: The key share provided by the client
* does not match a group supported by the server. A HelloRetryRequest will
* be needed.
* - Another negative return 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 = 0;
unsigned char const *p = buf;
unsigned char const *extentions_end;
size_t total_extensions_len, key_share_len;
int match_found = 0;
/* From RFC 8446:
*
* struct {
* KeyShareEntry client_shares<0..2^16-1>;
* } KeyShareClientHello;
*
*/
/* Read total legnth of KeyShareClientHello */
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
total_extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, total_extensions_len );
ssl->handshake->offered_group_id = 0;
extentions_end = p + total_extensions_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 < extentions_end; p += key_share_len )
{
uint16_t group;
/*
* struct {
* NamedGroup group;
* opaque key_exchange<1..2^16-1>;
* } KeyShareEntry;
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extentions_end, 4 );
group = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
key_share_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
/* Continue parsing even if we have already found a match,
* for input validation purposes.
*/
if( match_found == 1 )
continue;
/*
* NamedGroup matching
*
* For now, we only support ECDHE groups, but e.g.
* Type 1: ECDHE shares
*
* - Check if we recognize the group
* - Check if it's supported
*/
if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) )
{
const mbedtls_ecp_curve_info *curve_info =
mbedtls_ecp_curve_info_from_tls_id( group );
if( curve_info == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid TLS curve group id" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
match_found = 1;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) );
ret = mbedtls_ssl_tls13_read_public_ecdhe_share( ssl, p, end - p );
if( ret != 0 )
return( ret );
}
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( MBEDTLS_ERR_SSL_HRR_REQUIRED );
}
return( 0 );
}
#endif /* MBEDTLS_ECDH_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 */
}
static int ssl_tls13_client_hello_has_exts( mbedtls_ssl_context *ssl,
int ext_id_mask )
{
int masked = ssl->handshake->extensions_present & ext_id_mask;
return( masked == ext_id_mask );
}
static int ssl_tls13_client_hello_has_cert_extensions( 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_certificate_key_exchange( mbedtls_ssl_context *ssl )
{
if( !mbedtls_ssl_conf_tls13_ephemeral_enabled( ssl ) )
return( 0 );
if( !ssl_tls13_client_hello_has_cert_extensions( 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 CH:
*
* 1) The CH was well-formed and matched the server's configuration.
*
* In this case, the server progresses to sending its ServerHello.
*
* 2) The CH 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 CH 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;
size_t i, j;
size_t legacy_session_id_len;
size_t cipher_suites_len;
size_t extensions_len;
const unsigned char *cipher_suites_start;
const unsigned char *p = buf;
const unsigned char *extensions_end;
const int* cipher_suites;
const mbedtls_ssl_ciphersuite_t* ciphersuite_info;
int hrr_required = 0;
ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
/*
* ClientHello layer:
* 0 . 1 protocol version
* 2 . 33 random bytes ( starting with 4 bytes of Unix time )
* 34 . 34 session id length ( 1 byte )
* 35 . 34+x session id
* 35+x . 35+x DTLS only: cookie length ( 1 byte )
* 36+x . .. DTLS only: cookie
* .. . .. ciphersuite list length ( 2 bytes )
* .. . .. ciphersuite list
* .. . .. compression alg. list length ( 1 byte )
* .. . .. compression alg. list
* .. . .. extensions length ( 2 bytes, optional )
* .. . .. extensions ( optional )
*/
/* Needs to be updated due to mandatory extensions
* 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( !( p[0] == MBEDTLS_SSL_MAJOR_VERSION_3 &&
p[1] == MBEDTLS_SSL_MINOR_VERSION_3 ) )
{
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;
return ret;
}
p += 2;
/*
* Save client random
*/
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes",
p, MBEDTLS_SERVER_HELLO_RANDOM_LEN );
memcpy( &ssl->handshake->randbytes[0], p, MBEDTLS_SERVER_HELLO_RANDOM_LEN );
p += MBEDTLS_SERVER_HELLO_RANDOM_LEN;
/*
* Parse session ID
*/
legacy_session_id_len = p[0];
p++;
if( legacy_session_id_len > 32 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
ssl->session_negotiate->id_len = legacy_session_id_len;
/* Note that this field is echoed even if
* the client's value corresponded to a cached pre-TLS 1.3 session
* which the server has chosen not to resume. A client which
* receives a legacy_session_id_echo field that does not match what
* it sent in the ClientHello MUST abort the handshake with an
* "illegal_parameter" alert.
*/
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, session id",
buf, legacy_session_id_len );
memcpy( &ssl->session_negotiate->id[0], p, legacy_session_id_len );
p += legacy_session_id_len;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
cipher_suites_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, cipher_suites_len );
/* store pointer to ciphersuite list */
cipher_suites_start = p;
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, ciphersuitelist",
p, cipher_suites_len );
/* skip cipher_suites for now */
p += cipher_suites_len;
/* ...
* uint8 legacy_compression_method = 0;
* ...
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
if( p[0] != 0 )
{
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++;
/*
* Check the extensions length
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
extensions_end = p + extensions_len;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 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, 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) || defined(MBEDTLS_ECDSA_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 = mbedtls_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 || MBEDTLS_ECDSA_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 == MBEDTLS_ERR_SSL_HRR_REQUIRED )
{
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_SERVER_HELLO,
buf, p - buf );
/*
* Search for a matching ciphersuite
*/
cipher_suites = ssl->conf->ciphersuite_list;
ciphersuite_info = NULL;
for ( j = 0, p = cipher_suites_start; j < cipher_suites_len; j += 2, p += 2 )
{
for ( i = 0; cipher_suites[i] != 0; i++ )
{
if( MBEDTLS_GET_UINT16_BE(p, 0) != cipher_suites[i] )
continue;
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(
cipher_suites[i] );
if( ciphersuite_info == NULL )
{
MBEDTLS_SSL_DEBUG_MSG(
1,
( "mbedtls_ssl_ciphersuite_from_id: should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
goto have_ciphersuite;
}
}
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
have_ciphersuite:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "selected ciphersuite: %s",
ciphersuite_info->name ) );
ssl->session_negotiate->ciphersuite = cipher_suites[i];
ssl->handshake->ciphersuite_info = ciphersuite_info;
/* List all the extensions we have received */
ssl_tls13_debug_print_client_hello_exts( ssl );
/*
* Determine the key exchange algorithm to use.
* There are three types of key exchanges supported in TLS 1.3:
* - (EC)DH with ECDSA,
* - (EC)DH with PSK,
* - plain PSK.
*
* The PSK-based key exchanges may additionally be used with 0-RTT.
*
* Our built-in order of preference is
* 1 ) Plain PSK Mode
* 2 ) (EC)DHE-PSK Mode
* 3 ) Certificate Mode
*/
if( !ssl_tls13_check_certificate_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 );
}
if( hrr_required == 1 )
return( SSL_CLIENT_HELLO_HRR_REQUIRED );
return( 0 );
}
/* Update the handshake state machine */
static int ssl_tls13_postprocess_client_hello( mbedtls_ssl_context* ssl,
int hrr_required )
{
int ret = 0;
if( ssl->handshake->hello_retry_requests_sent == 0 )
{
hrr_required = SSL_CLIENT_HELLO_HRR_REQUIRED;
}
if( hrr_required == SSL_CLIENT_HELLO_HRR_REQUIRED )
{
/*
* Create stateless transcript hash for HRR
*/
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Reset transcript for HRR" ) );
ret = mbedtls_ssl_reset_transcript_for_hrr( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_reset_transcript_for_hrr",
ret );
return( ret );
}
mbedtls_ssl_session_reset_msg_layer( ssl, 0 );
/* Transmit Hello Retry Request */
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HELLO_RETRY_REQUEST );
return( 0 );
}
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 );
}
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_HELLO );
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 = 0;
int hrr_required = SSL_CLIENT_HELLO_OK;
unsigned char* buf = NULL;
size_t buflen = 0;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse client hello" ) );
ssl->major_ver = MBEDTLS_SSL_MAJOR_VERSION_3;
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 ) );
hrr_required = ret;
MBEDTLS_SSL_DEBUG_MSG( 1, ( "postprocess" ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_client_hello( ssl,
hrr_required ) );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse client hello" ) );
return( ret );
}
/*
* TLS and DTLS 1.3 State Maschine -- server side
*/
int mbedtls_ssl_tls13_handshake_server_step( mbedtls_ssl_context *ssl )
{
int ret = 0;
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:
ssl->handshake->hello_retry_requests_sent = 0;
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_HELLO );
break;
/* ----- READ CLIENT HELLO ----*/
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;
default:
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) );
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
}
return( ret );
}
#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_TLS1_3 */
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