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mbedtls/library/ssl_tls13_client.c
Xiaofei Bai d25fab6f79 Update based on comments 
Signed-off-by: Xiaofei Bai <xiaofei.bai@arm.com>
2021-12-02 06:36:27 +00:00

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/*
* TLS 1.3 client-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.
*
* This file is part of mbed TLS ( https://tls.mbed.org )
*/
#include "common.h"
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
#if defined(MBEDTLS_SSL_CLI_C)
#include <string.h>
#include "mbedtls/debug.h"
#include "mbedtls/error.h"
#include "mbedtls/platform.h"
#include "ssl_misc.h"
#include "ecdh_misc.h"
#include "ssl_tls13_keys.h"
/* Write extensions */
/*
* ssl_tls13_write_supported_versions_ext():
*
* struct {
* ProtocolVersion versions<2..254>;
* } SupportedVersions;
*/
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;
*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 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 7 );
/* Write extension_type */
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, p, 0 );
/* Write extension_data_length */
MBEDTLS_PUT_UINT16_BE( 3, p, 2 );
p += 4;
/* Length of versions */
*p++ = 0x2;
/* Write values of supported versions.
*
* They are defined by the configuration.
*
* Currently, only one version is advertised.
*/
mbedtls_ssl_write_version( ssl->conf->max_major_ver,
ssl->conf->max_minor_ver,
ssl->conf->transport, p );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "supported version: [%d:%d]",
ssl->conf->max_major_ver,
ssl->conf->max_minor_ver ) );
*out_len = 7;
return( 0 );
}
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( buf[0] != MBEDTLS_SSL_MAJOR_VERSION_3 ||
buf[1] != MBEDTLS_SSL_MINOR_VERSION_4 )
{
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 );
}
return( 0 );
}
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
/*
* Functions for writing supported_groups extension.
*
* Stucture of supported_groups:
* enum {
* secp256r1(0x0017), secp384r1(0x0018), secp521r1(0x0019),
* x25519(0x001D), x448(0x001E),
* ffdhe2048(0x0100), ffdhe3072(0x0101), ffdhe4096(0x0102),
* ffdhe6144(0x0103), ffdhe8192(0x0104),
* ffdhe_private_use(0x01FC..0x01FF),
* ecdhe_private_use(0xFE00..0xFEFF),
* (0xFFFF)
* } NamedGroup;
* struct {
* NamedGroup named_group_list<2..2^16-1>;
* } NamedGroupList;
*/
#if defined(MBEDTLS_ECDH_C)
/*
* In versions of TLS prior to TLS 1.3, this extension was named
* 'elliptic_curves' and only contained elliptic curve groups.
*/
static int ssl_tls13_write_named_group_list_ecdhe( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
unsigned char *p = buf;
*out_len = 0;
const uint16_t *group_list = mbedtls_ssl_get_groups( ssl );
if( group_list == NULL )
return( MBEDTLS_ERR_SSL_BAD_CONFIG );
for ( ; *group_list != 0; group_list++ )
{
const mbedtls_ecp_curve_info *curve_info;
curve_info = mbedtls_ecp_curve_info_from_tls_id( *group_list );
if( curve_info == NULL )
continue;
if( !mbedtls_ssl_tls13_named_group_is_ecdhe( *group_list ) )
continue;
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2);
MBEDTLS_PUT_UINT16_BE( *group_list, p, 0 );
p += 2;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "NamedGroup: %s ( %x )",
curve_info->name, *group_list ) );
}
*out_len = p - buf;
return( 0 );
}
#else
static int ssl_tls13_write_named_group_list_ecdhe( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
((void) ssl);
((void) buf);
((void) end);
*out_len = 0;
return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
}
#endif /* MBEDTLS_ECDH_C */
static int ssl_tls13_write_named_group_list_dhe( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
((void) ssl);
((void) buf);
((void) end);
*out_len = 0;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "write_named_group_dhe is not implemented" ) );
return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
}
static int ssl_tls13_write_supported_groups_ext( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
unsigned char *p = buf ;
unsigned char *named_group_list; /* Start of named_group_list */
size_t named_group_list_len; /* Length of named_group_list */
size_t output_len = 0;
int ret_ecdhe, ret_dhe;
*out_len = 0;
if( !mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) )
return( 0 );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding supported_groups extension" ) );
/* Check if we have space for header and length fields:
* - extension_type (2 bytes)
* - extension_data_length (2 bytes)
* - named_group_list_length (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
p += 6;
named_group_list = p;
ret_ecdhe = ssl_tls13_write_named_group_list_ecdhe( ssl, p, end, &output_len );
if( ret_ecdhe != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_named_group_list_ecdhe", ret_ecdhe );
}
p += output_len;
ret_dhe = ssl_tls13_write_named_group_list_dhe( ssl, p, end, &output_len );
if( ret_dhe != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_named_group_list_dhe", ret_dhe );
}
p += output_len;
/* Both ECDHE and DHE failed. */
if( ret_ecdhe != 0 && ret_dhe != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Both ECDHE and DHE groups are fail. " ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/* Length of named_group_list*/
named_group_list_len = p - named_group_list;
if( named_group_list_len == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "No group available." ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/* Write extension_type */
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_GROUPS, buf, 0 );
/* Write extension_data_length */
MBEDTLS_PUT_UINT16_BE( named_group_list_len + 2, buf, 2 );
/* Write length of named_group_list */
MBEDTLS_PUT_UINT16_BE( named_group_list_len, buf, 4 );
MBEDTLS_SSL_DEBUG_BUF( 3, "Supported groups extension", buf + 4, named_group_list_len + 2 );
*out_len = p - buf;
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS;
return( 0 );
}
/*
* Functions for writing key_share extension.
*/
#if defined(MBEDTLS_ECDH_C)
static int ssl_tls13_generate_and_write_ecdh_key_exchange(
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;
const mbedtls_ecp_curve_info *curve_info =
mbedtls_ecp_curve_info_from_tls_id( named_group );
if( curve_info == NULL )
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "offer curve %s", curve_info->name ) );
if( ( ret = mbedtls_ecdh_setup_no_everest( &ssl->handshake->ecdh_ctx,
curve_info->grp_id ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_setup_no_everest", ret );
return( ret );
}
ret = mbedtls_ecdh_tls13_make_params( &ssl->handshake->ecdh_ctx, out_len,
buf, end - buf,
ssl->conf->f_rng, ssl->conf->p_rng );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_tls13_make_params", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
MBEDTLS_DEBUG_ECDH_Q );
return( 0 );
}
#endif /* MBEDTLS_ECDH_C */
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(MBEDTLS_ECDH_C)
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++ )
{
const mbedtls_ecp_curve_info *curve_info;
curve_info = mbedtls_ecp_curve_info_from_tls_id( *group_list );
if( curve_info != NULL &&
mbedtls_ssl_tls13_named_group_is_ecdhe( *group_list ) )
{
*group_id = *group_list;
return( 0 );
}
}
#else
((void) ssl);
((void) group_id);
#endif /* MBEDTLS_ECDH_C */
/*
* Add DHE named groups here.
* Pick first available DHE group compatible with TLS 1.3
*/
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;
*/
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;
if( !mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) )
return( 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_dhe( 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(MBEDTLS_ECDH_C)
if( mbedtls_ssl_tls13_named_group_is_ecdhe( group_id ) )
{
/* Pointer to group */
unsigned char *group = p;
/* Length of key_exchange */
size_t key_exchange_len;
/* 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 = ssl_tls13_generate_and_write_ecdh_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 /* MBEDTLS_ECDH_C */
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 );
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE;
cleanup:
return( ret );
}
#if defined(MBEDTLS_ECDH_C)
static int ssl_tls13_check_ecdh_params( const mbedtls_ssl_context *ssl )
{
const mbedtls_ecp_curve_info *curve_info;
mbedtls_ecp_group_id grp_id;
#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
grp_id = ssl->handshake->ecdh_ctx.grp.id;
#else
grp_id = ssl->handshake->ecdh_ctx.grp_id;
#endif
curve_info = mbedtls_ecp_curve_info_from_grp_id( grp_id );
if( curve_info == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) );
if( mbedtls_ssl_check_curve( ssl, grp_id ) != 0 )
return( -1 );
MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
MBEDTLS_DEBUG_ECDH_QP );
return( 0 );
}
static int ssl_tls13_read_public_ecdhe_share( mbedtls_ssl_context *ssl,
const unsigned char *buf,
size_t buf_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
ret = mbedtls_ecdh_tls13_read_public( &ssl->handshake->ecdh_ctx,
buf, buf_len );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ecdh_tls13_read_public" ), ret );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
if( ssl_tls13_check_ecdh_params( ssl ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "ssl_tls13_check_ecdh_params() failed!" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
return( 0 );
}
#endif /* MBEDTLS_ECDH_C */
/*
* 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;
*/
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_ECDH_C)
if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) )
{
/* Complete ECDHE key agreement */
ret = ssl_tls13_read_public_ecdhe_share( ssl, p, end - p );
if( ret != 0 )
return( ret );
}
else
#endif /* MBEDTLS_ECDH_C */
if( 0 /* other KEMs? */ )
{
/* Do something */
}
else
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE;
return( ret );
}
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
/* Write cipher_suites
* CipherSuite cipher_suites<2..2^16-2>;
*/
static int ssl_tls13_write_client_hello_cipher_suites(
mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
unsigned char *p = buf;
const int *ciphersuite_list;
unsigned char *cipher_suites; /* Start of the cipher_suites list */
size_t cipher_suites_len;
*out_len = 0 ;
/*
* Ciphersuite list
*
* This is a list of the symmetric cipher options supported by
* the client, specifically the record protection algorithm
* ( including secret key length ) and a hash to be used with
* HKDF, in descending order of client preference.
*/
ciphersuite_list = ssl->conf->ciphersuite_list;
/* Check there is space for the cipher suite list length (2 bytes). */
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
p += 2;
/* Write cipher_suites */
cipher_suites = p;
for ( size_t i = 0; ciphersuite_list[i] != 0; i++ )
{
int cipher_suite = ciphersuite_list[i];
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( cipher_suite );
if( ciphersuite_info == NULL )
continue;
if( !( MBEDTLS_SSL_MINOR_VERSION_4 >= ciphersuite_info->min_minor_ver &&
MBEDTLS_SSL_MINOR_VERSION_4 <= ciphersuite_info->max_minor_ver ) )
continue;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, add ciphersuite: %04x, %s",
(unsigned int) cipher_suite,
ciphersuite_info->name ) );
/* Check there is space for the cipher suite identifier (2 bytes). */
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
MBEDTLS_PUT_UINT16_BE( cipher_suite, p, 0 );
p += 2;
}
/* Write the cipher_suites length in number of bytes */
cipher_suites_len = p - cipher_suites;
MBEDTLS_PUT_UINT16_BE( cipher_suites_len, buf, 0 );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "client hello, got %" MBEDTLS_PRINTF_SIZET " cipher suites",
cipher_suites_len/2 ) );
/* Output the total length of cipher_suites field. */
*out_len = p - buf;
return( 0 );
}
/*
* Structure of ClientHello message:
*
* 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;
*/
static int ssl_tls13_write_client_hello_body( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
int ret;
unsigned char *p_extensions_len; /* Pointer to extensions length */
size_t output_len; /* Length of buffer used by function */
size_t extensions_len; /* Length of the list of extensions*/
/* Buffer management */
unsigned char *p = buf;
*out_len = 0;
/* No validation needed here. It has been done by ssl_conf_check() */
ssl->major_ver = ssl->conf->min_major_ver;
ssl->minor_ver = ssl->conf->min_minor_ver;
/*
* Write legacy_version
* ProtocolVersion legacy_version = 0x0303; // TLS v1.2
*
* For TLS 1.3 we use the legacy version number {0x03, 0x03}
* instead of the true version number.
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
MBEDTLS_PUT_UINT16_BE( 0x0303, p, 0 );
p += 2;
/* Write the random bytes ( random ).*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
memcpy( p, ssl->handshake->randbytes, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes",
p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN;
/*
* Write legacy_session_id
*
* Versions of TLS before TLS 1.3 supported a "session resumption" feature
* which has been merged with pre-shared keys in this version. A client
* which has a cached session ID set by a pre-TLS 1.3 server SHOULD set
* this field to that value. In compatibility mode, this field MUST be
* non-empty, so a client not offering a pre-TLS 1.3 session MUST generate
* a new 32-byte value. This value need not be random but SHOULD be
* unpredictable to avoid implementations fixating on a specific value
* ( also known as ossification ). Otherwise, it MUST be set as a zero-length
* vector ( i.e., a zero-valued single byte length field ).
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 1 );
*p++ = 0; /* session id length set to zero */
/* Write cipher_suites */
ret = ssl_tls13_write_client_hello_cipher_suites( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
/* Write legacy_compression_methods
*
* For every TLS 1.3 ClientHello, this vector MUST contain exactly
* one byte set to zero, which corresponds to the 'null' compression
* method in prior versions of TLS.
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
*p++ = 1;
*p++ = MBEDTLS_SSL_COMPRESS_NULL;
/* Write extensions */
/* Keeping track of the included extensions */
ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
/* First write extensions, then the total length */
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
p_extensions_len = p;
p += 2;
/* Write supported_versions extension
*
* Supported Versions Extension is mandatory with TLS 1.3.
*/
ret = ssl_tls13_write_supported_versions_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
/* Write supported_groups extension
*
* It is REQUIRED for ECDHE cipher_suites.
*/
ret = ssl_tls13_write_supported_groups_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
/* Write key_share extension
*
* We need to send the key shares under three conditions:
* 1) A certificate-based ciphersuite is being offered. In this case
* supported_groups and supported_signature extensions have been
* successfully added.
* 2) A PSK-based ciphersuite with ECDHE is offered. In this case the
* psk_key_exchange_modes has been added as the last extension.
* 3) Or, in case all ciphers are supported ( which includes #1 and #2
* from above )
*/
ret = ssl_tls13_write_key_share_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
/* Write signature_algorithms extension
*
* It is REQUIRED for certificate authenticated cipher_suites.
*/
ret = mbedtls_ssl_tls13_write_sig_alg_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
/* Write server name extension */
ret = mbedtls_ssl_write_hostname_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
/* Add more extensions here */
/* Write the length of the list of extensions. */
extensions_len = p - p_extensions_len - 2;
MBEDTLS_PUT_UINT16_BE( extensions_len, p_extensions_len, 0 );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, total extension length: %" MBEDTLS_PRINTF_SIZET ,
extensions_len ) );
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello extensions", p_extensions_len, extensions_len );
*out_len = p - buf;
return( 0 );
}
static int ssl_tls13_finalize_client_hello( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_HELLO );
return( 0 );
}
static int ssl_tls13_prepare_client_hello( mbedtls_ssl_context *ssl )
{
int ret;
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,
ssl->handshake->randbytes,
MBEDTLS_CLIENT_HELLO_RANDOM_LEN ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "f_rng", ret );
return( ret );
}
return( 0 );
}
/*
* Write ClientHello handshake message.
* Handler for MBEDTLS_SSL_CLIENT_HELLO
*/
static int ssl_tls13_write_client_hello( mbedtls_ssl_context *ssl )
{
int ret = 0;
unsigned char *buf;
size_t buf_len, msg_len;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write client hello" ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_prepare_client_hello( ssl ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_start_handshake_msg(
ssl, MBEDTLS_SSL_HS_CLIENT_HELLO,
&buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_client_hello_body( ssl, buf,
buf + buf_len,
&msg_len ) );
mbedtls_ssl_tls13_add_hs_hdr_to_checksum( ssl,
MBEDTLS_SSL_HS_CLIENT_HELLO,
msg_len );
ssl->handshake->update_checksum( ssl, buf, msg_len );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_client_hello( ssl ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_finish_handshake_msg( ssl,
buf_len,
msg_len ) );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write client hello" ) );
return ret;
}
/*
* Functions for parsing and processing Server Hello
*/
/* Returns a negative value on failure, and otherwise
* - SSL_SERVER_HELLO_COORDINATE_HELLO or
* - SSL_SERVER_HELLO_COORDINATE_HRR
* to indicate which message is expected and to be parsed next. */
#define SSL_SERVER_HELLO_COORDINATE_HELLO 0
#define SSL_SERVER_HELLO_COORDINATE_HRR 1
static int ssl_server_hello_is_hrr( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
static const unsigned char magic_hrr_string[MBEDTLS_SERVER_HELLO_RANDOM_LEN] =
{ 0xCF, 0x21, 0xAD, 0x74, 0xE5, 0x9A, 0x61, 0x11,
0xBE, 0x1D, 0x8C, 0x02, 0x1E, 0x65, 0xB8, 0x91,
0xC2, 0xA2, 0x11, 0x16, 0x7A, 0xBB, 0x8C, 0x5E,
0x07, 0x9E, 0x09, 0xE2, 0xC8, 0xA8, 0x33 ,0x9C };
/* 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( magic_hrr_string ) );
if( memcmp( buf + 2, magic_hrr_string, sizeof( magic_hrr_string ) ) == 0 )
{
return( SSL_SERVER_HELLO_COORDINATE_HRR );
}
return( SSL_SERVER_HELLO_COORDINATE_HELLO );
}
/* Fetch and preprocess
* Returns a negative value on failure, and otherwise
* - SSL_SERVER_HELLO_COORDINATE_HELLO or
* - SSL_SERVER_HELLO_COORDINATE_HRR
*/
static int ssl_tls13_server_hello_coordinate( mbedtls_ssl_context *ssl,
unsigned char **buf,
size_t *buf_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_read_record( ssl, 0 ) );
if( ( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE ) ||
( ssl->in_msg[0] != MBEDTLS_SSL_HS_SERVER_HELLO ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "unexpected message" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE,
MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
}
*buf = ssl->in_msg + 4;
*buf_len = ssl->in_hslen - 4;
ret = ssl_server_hello_is_hrr( ssl, *buf, *buf + *buf_len );
switch( ret )
{
case SSL_SERVER_HELLO_COORDINATE_HELLO:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "received ServerHello message" ) );
break;
case SSL_SERVER_HELLO_COORDINATE_HRR:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "received HelloRetryRequest message" ) );
break;
}
cleanup:
return( ret );
}
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 );
}
static int ssl_tls13_cipher_suite_is_offered( mbedtls_ssl_context *ssl,
int cipher_suite )
{
const int *ciphersuite_list = ssl->conf->ciphersuite_list;
/* Check whether we have offered this ciphersuite */
for ( size_t i = 0; ciphersuite_list[i] != 0; i++ )
{
if( ciphersuite_list[i] == cipher_suite )
{
return( 1 );
}
}
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;
*/
static int ssl_tls13_parse_server_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 extensions_len;
const unsigned char *extensions_end;
uint16_t cipher_suite;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
/*
* 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( !( 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 );
return( MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
}
p += 2;
/* ...
* Random random;
* ...
* with Random defined as:
* opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN];
*/
memcpy( &ssl->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 )
{
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
/* ...
* 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;
/*
* Check whether this ciphersuite is supported and offered.
* Via the force_ciphersuite version we may have instructed the client
* to use a different ciphersuite.
*/
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( cipher_suite );
if( ciphersuite_info == NULL ||
ssl_tls13_cipher_suite_is_offered( ssl, cipher_suite ) == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "ciphersuite(%04x) not found or not offered",
cipher_suite ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
/* Configure ciphersuites */
mbedtls_ssl_optimize_checksum( ssl, ciphersuite_info );
ssl->handshake->ciphersuite_info = ciphersuite_info;
ssl->session_negotiate->ciphersuite = cipher_suite;
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 = time( NULL );
#endif /* MBEDTLS_HAVE_TIME */
/* ...
* 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++;
/* ...
* 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 );
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 );
switch( extension_type )
{
case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS:
MBEDTLS_SSL_DEBUG_MSG( 3,
( "found supported_versions extension" ) );
ret = ssl_tls13_parse_supported_versions_ext( ssl,
p,
p + extension_data_len );
if( ret != 0 )
return( ret );
break;
case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension." ) );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key:Not supported yet" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT,
MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
case MBEDTLS_TLS_EXT_KEY_SHARE:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found key_shares extension" ) );
if( ( ret = ssl_tls13_parse_key_share_ext( ssl,
p, p + extension_data_len ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"ssl_tls13_parse_key_share_ext",
ret );
return( ret );
}
break;
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
default:
MBEDTLS_SSL_DEBUG_MSG(
3,
( "unknown extension found: %u ( ignoring )",
extension_type ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT,
MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
}
p += extension_data_len;
}
return( 0 );
}
static int ssl_tls13_finalize_server_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ssl_key_set traffic_keys;
mbedtls_ssl_transform *transform_handshake = NULL;
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->extensions_present &
( MBEDTLS_SSL_EXT_PRE_SHARED_KEY | MBEDTLS_SSL_EXT_KEY_SHARE ) )
{
/* Only the pre_shared_key extension was received */
case MBEDTLS_SSL_EXT_PRE_SHARED_KEY:
handshake->tls13_kex_modes = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK;
break;
/* Only the key_share extension was received */
case MBEDTLS_SSL_EXT_KEY_SHARE:
handshake->tls13_kex_modes = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL;
break;
/* Both the pre_shared_key and key_share extensions were received */
case ( MBEDTLS_SSL_EXT_PRE_SHARED_KEY | MBEDTLS_SSL_EXT_KEY_SHARE ):
handshake->tls13_kex_modes = 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;
}
/* Start the TLS 1.3 key schedule: Set the PSK and derive early secret.
*
* TODO: We don't have to do this in case we offered 0-RTT and the
* server accepted it. In this case, we could skip generating
* the 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_data",
ret );
goto cleanup;
}
/* Compute handshake secret */
ret = mbedtls_ssl_tls13_key_schedule_stage_handshake( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_derive_master_secret", ret );
goto cleanup;
}
/* Next evolution in key schedule: Establish handshake secret and
* key material. */
ret = mbedtls_ssl_tls13_generate_handshake_keys( ssl, &traffic_keys );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_generate_handshake_keys",
ret );
goto cleanup;
}
transform_handshake = mbedtls_calloc( 1, sizeof( mbedtls_ssl_transform ) );
if( transform_handshake == NULL )
{
ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
goto cleanup;
}
ret = mbedtls_ssl_tls13_populate_transform( transform_handshake,
ssl->conf->endpoint,
ssl->session_negotiate->ciphersuite,
&traffic_keys,
ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_populate_transform", ret );
goto cleanup;
}
handshake->transform_handshake = transform_handshake;
mbedtls_ssl_set_inbound_transform( ssl, transform_handshake );
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Switch to handshake keys for inbound traffic" ) );
ssl->session_in = ssl->session_negotiate;
/*
* State machine update
*/
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS );
cleanup:
mbedtls_platform_zeroize( &traffic_keys, sizeof( traffic_keys ) );
if( ret != 0 )
{
mbedtls_free( transform_handshake );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
return( ret );
}
/*
* Wait and parse ServerHello handshake message.
* Handler for MBEDTLS_SSL_SERVER_HELLO
*/
static int ssl_tls13_process_server_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf;
size_t buf_len;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> %s", __func__ ) );
/* Coordination step
* - Fetch record
* - Make sure it's either a ServerHello or a HRR.
* - Switch processing routine in case of HRR
*/
ssl->major_ver = MBEDTLS_SSL_MAJOR_VERSION_3;
ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
ret = ssl_tls13_server_hello_coordinate( ssl, &buf, &buf_len );
/* Parsing step
* We know what message to expect by now and call
* the respective parsing function.
*/
if( ret == SSL_SERVER_HELLO_COORDINATE_HELLO )
{
MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_server_hello( ssl, buf,
buf + buf_len ) );
mbedtls_ssl_tls13_add_hs_msg_to_checksum( ssl,
MBEDTLS_SSL_HS_SERVER_HELLO,
buf, buf_len );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_server_hello( ssl ) );
}
else if( ret == SSL_SERVER_HELLO_COORDINATE_HRR )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "HRR not supported" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE ,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
}
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= %s", __func__ ) );
return( ret );
}
/*
*
* EncryptedExtensions message
*
* The EncryptedExtensions message contains any extensions which
* should be protected, i.e., any which are not needed to establish
* the cryptographic context.
*/
/*
* Overview
*/
/* Main entry point; orchestrates the other functions */
static int ssl_tls13_process_encrypted_extensions( mbedtls_ssl_context *ssl );
static int ssl_tls13_parse_encrypted_extensions( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end );
static int ssl_tls13_postprocess_encrypted_extensions( mbedtls_ssl_context *ssl );
/*
* Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS
*/
static int ssl_tls13_process_encrypted_extensions( mbedtls_ssl_context *ssl )
{
int ret;
unsigned char *buf;
size_t buf_len;
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 ) );
mbedtls_ssl_tls13_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, buf_len );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_encrypted_extensions( ssl ) );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse encrypted extensions" ) );
return( ret );
}
/* Parse EncryptedExtensions message
* struct {
* Extension extensions<0..2^16-1>;
* } EncryptedExtensions;
*/
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_CHK_BUF_READ_PTR( p, end, 2 );
extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_DEBUG_BUF( 3, "encrypted extensions", p, extensions_len );
extensions_end = p + extensions_len;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, extensions_len );
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 );
/* The client MUST check EncryptedExtensions for the
* presence of any forbidden extensions and if any are found MUST abort
* the handshake with an "unsupported_extension" alert.
*/
switch( extension_type )
{
case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found extensions supported groups" ) );
break;
default:
MBEDTLS_SSL_DEBUG_MSG(
3, ( "unsupported extension found: %u ", extension_type) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT,
MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
return ( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
}
p += extension_data_len;
}
/* 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 );
}
static int ssl_tls13_postprocess_encrypted_extensions( mbedtls_ssl_context *ssl )
{
#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
((void) ssl);
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_FINISHED );
#endif
return( 0 );
}
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
/*
* Handler for MBEDTLS_SSL_CERTIFICATE_REQUEST
*/
static int ssl_tls13_process_certificate_request( mbedtls_ssl_context *ssl )
{
int ret = mbedtls_ssl_read_record( ssl, 0 );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
return( ret );
}
if( ( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE ) &&
( ssl->in_msg[0] == MBEDTLS_SSL_HS_CERTIFICATE_REQUEST ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "CertificateRequest not supported" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
ssl->keep_current_message = 1;
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_CERTIFICATE );
return( 0 );
}
/*
* Handler for MBEDTLS_SSL_SERVER_CERTIFICATE
*/
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
*/
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_KEY_EXCHANGE_WITH_CERT_ENABLED */
/*
* Handler for MBEDTLS_SSL_SERVER_FINISHED
*/
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 );
mbedtls_ssl_set_outbound_transform( ssl, ssl->handshake->transform_handshake );
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_FINISHED );
return( 0 );
}
/*
* Handler for MBEDTLS_SSL_CLIENT_FINISHED
*/
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 );
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_FLUSH_BUFFERS );
return( 0 );
}
/*
* Handler for MBEDTLS_SSL_FLUSH_BUFFERS
*/
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
*/
static int ssl_tls13_handshake_wrapup( mbedtls_ssl_context *ssl )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Switch to application keys for inbound traffic" ) );
mbedtls_ssl_set_inbound_transform ( ssl, ssl->transform_application );
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Switch to application keys for outbound traffic" ) );
mbedtls_ssl_set_outbound_transform( ssl, ssl->transform_application );
mbedtls_ssl_tls13_handshake_wrapup( ssl );
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HANDSHAKE_OVER );
return( 0 );
}
int mbedtls_ssl_tls13_handshake_client_step( mbedtls_ssl_context *ssl )
{
int ret = 0;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "tls13 client state: %d", ssl->state ) );
switch( ssl->state )
{
/*
* ssl->state is initialized as HELLO_REQUEST. It is the same
* as CLIENT_HELLO state.
*/
case MBEDTLS_SSL_HELLO_REQUEST:
case MBEDTLS_SSL_CLIENT_HELLO:
ret = ssl_tls13_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_KEY_EXCHANGE_WITH_CERT_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_KEY_EXCHANGE_WITH_CERT_ENABLED */
case MBEDTLS_SSL_SERVER_FINISHED:
ret = ssl_tls13_process_server_finished( ssl );
break;
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;
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 */
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
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