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mbedtls/library/ssl_tls13_client.c
XiaokangQian d59be77ce7 Refine code based on comments 
Add comments for parse hrr key share and cookie
Change variable names based on RFC8466
Refine fatal allerts in parse server hello and hrr

Signed-off-by: XiaokangQian <xiaokang.qian@arm.com>
2022-01-26 10:53:15 +00:00

1888 lines
62 KiB
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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)
#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"
#include "ssl_debug_helpers.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)
static int ssl_tls13_reset_key_share( mbedtls_ssl_context *ssl )
{
uint16_t group_id = ssl->handshake->offered_group_id;
if( group_id == 0 )
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
#if defined(MBEDTLS_ECDH_C)
if( mbedtls_ssl_tls13_named_group_is_ecdhe( group_id ) )
{
mbedtls_ecdh_free( &ssl->handshake->ecdh_ctx );
return( 0 );
}
else
#endif /* MBEDTLS_ECDH_C */
if( 0 /* other KEMs? */ )
{
/* Do something */
}
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/*
* 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;
/* 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_hrr_key_share_ext()
* Parse key_share extension in Hello Retry Request
*
* struct {
* NamedGroup selected_group;
* } KeyShareHelloRetryRequest;
*/
static int ssl_tls13_parse_hrr_key_share_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
const mbedtls_ecp_curve_info *curve_info = NULL;
const unsigned char *p = buf;
int selected_group;
int found = 0;
const uint16_t *group_list = mbedtls_ssl_get_groups( ssl );
if( group_list == NULL )
return( MBEDTLS_ERR_SSL_BAD_CONFIG );
MBEDTLS_SSL_DEBUG_BUF( 3, "key_share extension", p, end - buf );
/* Read selected_group */
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
selected_group = MBEDTLS_GET_UINT16_BE( p, 0 );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "selected_group ( %d )", selected_group ) );
/* Upon receipt of this extension in a HelloRetryRequest, the client
* MUST first verify that the selected_group field corresponds to a
* group which was provided in the "supported_groups" extension in the
* original ClientHello.
* The supported_group was based on the info in ssl->conf->group_list.
*
* If the server provided a key share that was not sent in the ClientHello
* then the client MUST abort the handshake with an "illegal_parameter" alert.
*/
for( ; *group_list != 0; group_list++ )
{
curve_info = mbedtls_ecp_curve_info_from_tls_id( *group_list );
if( curve_info == NULL || curve_info->tls_id != selected_group )
continue;
/* We found a match */
found = 1;
break;
}
/* Client MUST verify that the selected_group field does not
* correspond to a group which was provided in the "key_share"
* extension in the original ClientHello. If the server sent an
* HRR message with a key share already provided in the
* ClientHello then the client MUST abort the handshake with
* an "illegal_parameter" alert.
*/
if( found == 0 || selected_group == ssl->handshake->offered_group_id )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid key share in HRR" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
/* Remember server's preference for next ClientHello */
ssl->handshake->offered_group_id = selected_group;
return( 0 );
}
/*
* 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 */
#if defined(MBEDTLS_SSL_COOKIE_C)
/*
* ssl_tls13_parse_cookie_ext()
* Parse cookie extension in Hello Retry Request
*
* struct {
* opaque cookie<1..2^16-1>;
* } Cookie;
*
* When sending a HelloRetryRequest, the server MAY provide a "cookie"
* extension to the client (this is an exception to the usual rule that
* the only extensions that may be sent are those that appear in the
* ClientHello). When sending the new ClientHello, the client MUST copy
* the contents of the extension received in the HelloRetryRequest into
* a "cookie" extension in the new ClientHello. Clients MUST NOT use
* cookies in their initial ClientHello in subsequent connections.
*/
static int ssl_tls13_parse_cookie_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
size_t cookie_len;
const unsigned char *p = buf;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
/* Retrieve length field of cookie */
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
cookie_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, cookie_len );
MBEDTLS_SSL_DEBUG_BUF( 3, "cookie extension", p, cookie_len );
mbedtls_free( handshake->verify_cookie );
handshake->verify_cookie = mbedtls_calloc( 1, cookie_len );
if( handshake->verify_cookie == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
( "alloc failed ( %" MBEDTLS_PRINTF_SIZET " bytes )",
cookie_len ) );
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
}
memcpy( handshake->verify_cookie, p, cookie_len );
handshake->verify_cookie_len = (unsigned char) cookie_len;
return( 0 );
}
#endif /* MBEDTLS_SSL_COOKIE_C */
/* 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 ).
*/
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
MBEDTLS_SSL_CHK_BUF_PTR( p, end, ssl->session_negotiate->id_len + 1 );
*p++ = (unsigned char)ssl->session_negotiate->id_len;
memcpy( p, ssl->session_negotiate->id, 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 );
#else
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 1 );
*p++ = 0; /* session id length set to zero */
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
/* 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)
/*
* Add the extensions related to (EC)DHE ephemeral key establishment only if
* enabled as per the configuration.
*/
if( mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) )
{
ret = mbedtls_ssl_write_supported_groups_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
ret = ssl_tls13_write_key_share_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
ret = mbedtls_ssl_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 );
}
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
/*
* Create a session identifier for the purpose of middlebox compatibility
* only if one has not been created already.
*/
if( ssl->session_negotiate->id_len == 0 )
{
/* Creating a session id with 32 byte length */
if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng,
ssl->session_negotiate->id, 32 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "creating session id failed", ret );
return( ret );
}
ssl->session_negotiate->id_len = 32;
}
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
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_tls13_fetch_handshake_msg( ssl,
MBEDTLS_SSL_HS_SERVER_HELLO,
buf, buf_len ) );
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" ) );
/* If a client receives a second
* HelloRetryRequest in the same connection (i.e., where the ClientHello
* was itself in response to a HelloRetryRequest), it MUST abort the
* handshake with an "unexpected_message" alert.
*/
if( ssl->handshake->hello_retry_request_count > 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Multiple HRRs received" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE,
MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
}
/*
* Clients must abort the handshake with an "illegal_parameter"
* alert if the HelloRetryRequest would not result in any change
* in the ClientHello.
* In a PSK only key exchange that what we expect.
*/
if( ! mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
( "Unexpected HRR in pure PSK key exchange." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
ssl->handshake->hello_retry_request_count++;
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;
*/
#define ALERT_UNSUPPORTED_EXTENSION_FOUND ( 1 << 0 )
#define ALERT_ILLEGAL_PARAMETER_FOUND ( 1 << 1 )
static int ssl_tls13_parse_server_hello( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end,
int is_hrr )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const unsigned char *p = buf;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
size_t extensions_len;
const unsigned char *extensions_end;
uint16_t cipher_suite;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
int supported_versions_ext_found = 0;
int fatal_alert_found = 0;
/*
* 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 );
ret = MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION;
goto cleanup;
}
p += 2;
/* ...
* Random random;
* ...
* with Random defined as:
* opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN];
*/
if( !is_hrr )
{
memcpy( &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 )
{
fatal_alert_found |= ALERT_ILLEGAL_PARAMETER_FOUND;
goto cleanup;
}
/* ...
* 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;
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( cipher_suite );
/*
* Check whether this ciphersuite is supported and offered.
* Via the force_ciphersuite version we may have instructed the client
* to use a different ciphersuite.
*/
if( ciphersuite_info == NULL ||
ssl_tls13_cipher_suite_is_offered( ssl, cipher_suite ) == 0 )
{
ret = MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
/*
* If we received an HRR before and that the proposed selected
* ciphersuite in this server hello is not the same as the one
* proposed in the HRR, we abort the handshake and send an
* "illegal_parameter" alert.
*/
else if( ( !is_hrr ) && ( handshake->hello_retry_request_count > 0 ) &&
( cipher_suite != ssl->session_negotiate->ciphersuite ) )
{
ret = MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
if( ret == MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid ciphersuite(%04x) parameter",
cipher_suite ) );
fatal_alert_found |= ALERT_ILLEGAL_PARAMETER_FOUND;
goto cleanup;
}
/* Configure ciphersuites */
mbedtls_ssl_optimize_checksum( ssl, ciphersuite_info );
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" ) );
fatal_alert_found |= ALERT_ILLEGAL_PARAMETER_FOUND;
goto cleanup;
}
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;
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_SSL_COOKIE_C)
case MBEDTLS_TLS_EXT_COOKIE:
if( !is_hrr )
{
fatal_alert_found |= ALERT_UNSUPPORTED_EXTENSION_FOUND;
goto cleanup;
}
ret = ssl_tls13_parse_cookie_ext( ssl,
p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"ssl_tls13_parse_cookie_ext",
ret );
goto cleanup;
}
break;
#endif /* MBEDTLS_SSL_COOKIE_C */
case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS:
supported_versions_ext_found = 1;
MBEDTLS_SSL_DEBUG_MSG( 3,
( "found supported_versions extension" ) );
ret = ssl_tls13_parse_supported_versions_ext( ssl,
p,
extension_data_end );
if( ret != 0 )
goto cleanup;
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" ) );
fatal_alert_found |= ALERT_UNSUPPORTED_EXTENSION_FOUND;
goto cleanup;
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
case MBEDTLS_TLS_EXT_KEY_SHARE:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found key_shares extension" ) );
if( ! mbedtls_ssl_conf_tls13_some_ephemeral_enabled( ssl ) )
{
fatal_alert_found |= ALERT_UNSUPPORTED_EXTENSION_FOUND;
goto cleanup;
}
if( is_hrr )
ret = ssl_tls13_parse_hrr_key_share_ext( ssl,
p, extension_data_end );
else
ret = ssl_tls13_parse_key_share_ext( ssl,
p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"ssl_tls13_parse_key_share_ext",
ret );
goto cleanup;
}
break;
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
default:
MBEDTLS_SSL_DEBUG_MSG(
3,
( "unknown extension found: %u ( ignoring )",
extension_type ) );
fatal_alert_found |= ALERT_UNSUPPORTED_EXTENSION_FOUND;
goto cleanup;
}
p += extension_data_len;
}
if( !supported_versions_ext_found )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "supported_versions not found" ) );
fatal_alert_found |= ALERT_ILLEGAL_PARAMETER_FOUND;
goto cleanup;
}
cleanup:
if( fatal_alert_found & ALERT_UNSUPPORTED_EXTENSION_FOUND )
{
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT,
MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
ret = MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION;
}
else if ( fatal_alert_found & ALERT_ILLEGAL_PARAMETER_FOUND )
{
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
ret = MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
return( ret );
}
static int ssl_tls13_postprocess_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 );
}
static int ssl_tls13_postprocess_hrr( mbedtls_ssl_context *ssl )
{
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
/* If not offering early data, the client sends a dummy CCS record
* immediately before its second flight. This may either be before
* its second ClientHello or before its encrypted handshake flight.
*/
mbedtls_ssl_handshake_set_state( ssl,
MBEDTLS_SSL_CLIENT_CCS_BEFORE_2ND_CLIENT_HELLO );
#else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_HELLO );
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
mbedtls_ssl_session_reset_msg_layer( ssl, 0 );
/*
* We are going to re-generate a shared secret corresponding to the group
* selected by the server, which is different from the group for which we
* generated a shared secret in the first client hello.
* Thus, reset the shared secret.
*/
ret = ssl_tls13_reset_key_share( ssl );
if( ret != 0 )
return( ret );
#else
((void) ssl);
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
return( 0 );
}
/*
* 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 = NULL;
size_t buf_len = 0;
int is_hrr = 0;
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 );
if( ret < 0 )
goto cleanup;
else
is_hrr = ( ret == SSL_SERVER_HELLO_COORDINATE_HRR );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_server_hello( ssl, buf,
buf + buf_len,
is_hrr ) );
if( is_hrr )
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_reset_transcript_for_hrr( ssl ) );
mbedtls_ssl_tls13_add_hs_msg_to_checksum( ssl,
MBEDTLS_SSL_HS_SERVER_HELLO,
buf, buf_len );
if( is_hrr )
MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_hrr( ssl ) );
else
MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_server_hello( ssl ) );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= %s:is_hrr = %d", __func__, is_hrr ) );
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 );
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
mbedtls_ssl_handshake_set_state(
ssl,
MBEDTLS_SSL_CLIENT_CCS_AFTER_SERVER_FINISHED );
#else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_FINISHED );
#endif
return( 0 );
}
/*
* Handler for MBEDTLS_SSL_CLIENT_CCS_AFTER_SERVER_FINISHED
*/
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
static int ssl_tls13_write_change_cipher_spec( mbedtls_ssl_context *ssl )
{
int ret;
ret = mbedtls_ssl_tls13_write_change_cipher_spec( ssl );
if( ret != 0 )
return( ret );
return( 0 );
}
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
/*
* Handler for MBEDTLS_SSL_CLIENT_FINISHED
*/
static int ssl_tls13_write_client_finished( mbedtls_ssl_context *ssl )
{
int ret;
mbedtls_ssl_set_outbound_transform( ssl, ssl->handshake->transform_handshake );
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: %s(%d)",
mbedtls_ssl_states_str( ssl->state ),
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;
/*
* Injection of dummy-CCS's for middlebox compatibility
*/
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
case MBEDTLS_SSL_CLIENT_CCS_AFTER_SERVER_FINISHED:
case MBEDTLS_SSL_CLIENT_CCS_BEFORE_2ND_CLIENT_HELLO:
ret = ssl_tls13_write_change_cipher_spec( ssl );
break;
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
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 */
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