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mbedtls/library/ssl_tls13_server.c
Manuel Pégourié-Gonnard e3358e14b2
Merge pull request #6051 from mprse/permissions_2b_v2 
Permissions 2b: TLS 1.3 sigalg selection
2022-09-28 09:50:04 +02:00

3095 lines
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/*
* TLS 1.3 server-side functions
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "common.h"
#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3)
#include "mbedtls/debug.h"
#include "mbedtls/error.h"
#include "mbedtls/platform.h"
#include "mbedtls/constant_time.h"
#include "ssl_misc.h"
#include "ssl_tls13_keys.h"
#include "ssl_debug_helpers.h"
#if defined(MBEDTLS_ECP_C)
#include "mbedtls/ecp.h"
#endif /* MBEDTLS_ECP_C */
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif /* MBEDTLS_PLATFORM_C */
#include "ssl_misc.h"
#include "ssl_tls13_keys.h"
#include "ssl_debug_helpers.h"
static const mbedtls_ssl_ciphersuite_t *ssl_tls13_validate_peer_ciphersuite(
mbedtls_ssl_context *ssl,
unsigned int cipher_suite )
{
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
if( ! mbedtls_ssl_tls13_cipher_suite_is_offered( ssl, cipher_suite ) )
return( NULL );
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( cipher_suite );
if( ( mbedtls_ssl_validate_ciphersuite( ssl, ciphersuite_info,
ssl->tls_version,
ssl->tls_version ) != 0 ) )
{
return( NULL );
}
return( ciphersuite_info );
}
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
/* From RFC 8446:
*
* enum { psk_ke(0), psk_dhe_ke(1), (255) } PskKeyExchangeMode;
* struct {
* PskKeyExchangeMode ke_modes<1..255>;
* } PskKeyExchangeModes;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
const unsigned char *p = buf;
size_t ke_modes_len;
int ke_modes = 0;
/* Read ke_modes length (1 Byte) */
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
ke_modes_len = *p++;
/* Currently, there are only two PSK modes, so even without looking
* at the content, something's wrong if the list has more than 2 items. */
if( ke_modes_len > 2 )
{
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, ke_modes_len );
while( ke_modes_len-- != 0 )
{
switch( *p++ )
{
case MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE:
ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Found PSK KEX MODE" ) );
break;
case MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE:
ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Found PSK_EPHEMERAL KEX MODE" ) );
break;
default:
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
}
ssl->handshake->tls13_kex_modes = ke_modes;
return( 0 );
}
#define SSL_TLS1_3_OFFERED_PSK_NOT_MATCH 1
#define SSL_TLS1_3_OFFERED_PSK_MATCH 0
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_offered_psks_check_identity_match_ticket(
mbedtls_ssl_context *ssl,
const unsigned char *identity,
size_t identity_len,
uint32_t obfuscated_ticket_age,
mbedtls_ssl_session *session )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *ticket_buffer;
#if defined(MBEDTLS_HAVE_TIME)
mbedtls_time_t now;
uint64_t age_in_s;
int64_t age_diff_in_ms;
#endif
((void) obfuscated_ticket_age);
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> check_identity_match_ticket" ) );
/* Ticket parser is not configured, Skip */
if( ssl->conf->f_ticket_parse == NULL || identity_len == 0 )
return( 0 );
/* We create a copy of the encrypted ticket since the ticket parsing
* function is allowed to use its input buffer as an output buffer
* (in-place decryption). We do, however, need the original buffer for
* computing the PSK binder value.
*/
ticket_buffer = mbedtls_calloc( 1, identity_len );
if( ticket_buffer == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "buffer too small" ) );
return ( MBEDTLS_ERR_SSL_ALLOC_FAILED );
}
memcpy( ticket_buffer, identity, identity_len );
if( ( ret = ssl->conf->f_ticket_parse( ssl->conf->p_ticket,
session,
ticket_buffer, identity_len ) ) != 0 )
{
if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket is not authentic" ) );
else if( ret == MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED )
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket is expired" ) );
else
MBEDTLS_SSL_DEBUG_RET( 1, "ticket_parse", ret );
}
/* We delete the temporary buffer */
mbedtls_free( ticket_buffer );
if( ret != 0 )
goto exit;
ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED;
#if defined(MBEDTLS_HAVE_TIME)
now = mbedtls_time( NULL );
if( now < session->start )
{
MBEDTLS_SSL_DEBUG_MSG(
3, ( "Ticket expired: now=%" MBEDTLS_PRINTF_LONGLONG
", start=%" MBEDTLS_PRINTF_LONGLONG,
(long long)now, (long long)session->start ) );
goto exit;
}
age_in_s = (uint64_t)( now - session->start );
/* RFC 8446 section 4.6.1
*
* Servers MUST NOT use any value greater than 604800 seconds (7 days).
*
* RFC 8446 section 4.2.11.1
*
* Clients MUST NOT attempt to use tickets which have ages greater than
* the "ticket_lifetime" value which was provided with the ticket.
*
* For time being, the age MUST be less than 604800 seconds (7 days).
*/
if( age_in_s > 604800 )
{
MBEDTLS_SSL_DEBUG_MSG(
3, ( "Ticket expired: Ticket age exceed limitation ticket_age=%lu",
(long unsigned int)age_in_s ) );
goto exit;
}
/* RFC 8446 section 4.2.10
*
* For PSKs provisioned via NewSessionTicket, a server MUST validate that
* the ticket age for the selected PSK identity (computed by subtracting
* ticket_age_add from PskIdentity.obfuscated_ticket_age modulo 2^32) is
* within a small tolerance of the time since the ticket was issued.
*
* NOTE: When `now == session->start`, `age_diff_in_ms` may be negative
* as the age units are different on the server (s) and in the
* client (ms) side. Add a -1000 ms tolerance window to take this
* into account.
*/
age_diff_in_ms = age_in_s * 1000;
age_diff_in_ms -= ( obfuscated_ticket_age - session->ticket_age_add );
if( age_diff_in_ms <= -1000 ||
age_diff_in_ms > MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE )
{
MBEDTLS_SSL_DEBUG_MSG(
3, ( "Ticket expired: Ticket age outside tolerance window "
"( diff=%d )", (int)age_diff_in_ms ) );
goto exit;
}
ret = 0;
#endif /* MBEDTLS_HAVE_TIME */
exit:
if( ret != 0 )
mbedtls_ssl_session_free( session );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= check_identity_match_ticket" ) );
return( ret );
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_offered_psks_check_identity_match(
mbedtls_ssl_context *ssl,
const unsigned char *identity,
size_t identity_len,
uint32_t obfuscated_ticket_age,
int *psk_type,
mbedtls_ssl_session *session )
{
((void) session);
((void) obfuscated_ticket_age);
*psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
MBEDTLS_SSL_DEBUG_BUF( 4, "identity", identity, identity_len );
ssl->handshake->resume = 0;
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
if( ssl_tls13_offered_psks_check_identity_match_ticket(
ssl, identity, identity_len, obfuscated_ticket_age,
session ) == SSL_TLS1_3_OFFERED_PSK_MATCH )
{
ssl->handshake->resume = 1;
*psk_type = MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION;
mbedtls_ssl_set_hs_psk( ssl,
session->resumption_key,
session->resumption_key_len );
MBEDTLS_SSL_DEBUG_BUF( 4, "Ticket-resumed PSK:",
session->resumption_key,
session->resumption_key_len );
MBEDTLS_SSL_DEBUG_MSG( 4, ( "ticket: obfuscated_ticket_age: %u",
(unsigned)obfuscated_ticket_age ) );
return( SSL_TLS1_3_OFFERED_PSK_MATCH );
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
/* Check identity with external configured function */
if( ssl->conf->f_psk != NULL )
{
if( ssl->conf->f_psk(
ssl->conf->p_psk, ssl, identity, identity_len ) == 0 )
{
return( SSL_TLS1_3_OFFERED_PSK_MATCH );
}
return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
}
MBEDTLS_SSL_DEBUG_BUF( 5, "identity", identity, identity_len );
/* Check identity with pre-configured psk */
if( ssl->conf->psk_identity != NULL &&
identity_len == ssl->conf->psk_identity_len &&
mbedtls_ct_memcmp( ssl->conf->psk_identity,
identity, identity_len ) == 0 )
{
mbedtls_ssl_set_hs_psk( ssl, ssl->conf->psk, ssl->conf->psk_len );
return( SSL_TLS1_3_OFFERED_PSK_MATCH );
}
return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_offered_psks_check_binder_match( mbedtls_ssl_context *ssl,
const unsigned char *binder,
size_t binder_len,
int psk_type,
psa_algorithm_t psk_hash_alg )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char transcript[PSA_HASH_MAX_SIZE];
size_t transcript_len;
unsigned char *psk;
size_t psk_len;
unsigned char server_computed_binder[PSA_HASH_MAX_SIZE];
/* Get current state of handshake transcript. */
ret = mbedtls_ssl_get_handshake_transcript(
ssl, mbedtls_hash_info_md_from_psa( psk_hash_alg ),
transcript, sizeof( transcript ), &transcript_len );
if( ret != 0 )
return( ret );
ret = mbedtls_ssl_tls13_export_handshake_psk( ssl, &psk, &psk_len );
if( ret != 0 )
return( ret );
ret = mbedtls_ssl_tls13_create_psk_binder( ssl, psk_hash_alg,
psk, psk_len, psk_type,
transcript,
server_computed_binder );
#if defined(MBEDTLS_USE_PSA_CRYPTO)
mbedtls_free( (void*)psk );
#endif
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "PSK binder calculation failed." ) );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder ( computed ): ",
server_computed_binder, transcript_len );
MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder ( received ): ", binder, binder_len );
if( mbedtls_ct_memcmp( server_computed_binder, binder, binder_len ) == 0 )
{
return( SSL_TLS1_3_OFFERED_PSK_MATCH );
}
mbedtls_platform_zeroize( server_computed_binder,
sizeof( server_computed_binder ) );
return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_select_ciphersuite_for_psk(
mbedtls_ssl_context *ssl,
const unsigned char *cipher_suites,
const unsigned char *cipher_suites_end,
uint16_t *selected_ciphersuite,
const mbedtls_ssl_ciphersuite_t **selected_ciphersuite_info )
{
psa_algorithm_t psk_hash_alg = PSA_ALG_SHA_256;
*selected_ciphersuite = 0;
*selected_ciphersuite_info = NULL;
/* RFC 8446, page 55.
*
* For externally established PSKs, the Hash algorithm MUST be set when the
* PSK is established or default to SHA-256 if no such algorithm is defined.
*
*/
/*
* Search for a matching ciphersuite
*/
for ( const unsigned char *p = cipher_suites;
p < cipher_suites_end; p += 2 )
{
uint16_t cipher_suite;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 );
ciphersuite_info = ssl_tls13_validate_peer_ciphersuite( ssl,
cipher_suite );
if( ciphersuite_info == NULL )
continue;
/* MAC of selected ciphersuite MUST be same with PSK binder if exist.
* Otherwise, client should reject.
*/
if( psk_hash_alg == mbedtls_psa_translate_md( ciphersuite_info->mac ) )
{
*selected_ciphersuite = cipher_suite;
*selected_ciphersuite_info = ciphersuite_info;
return( 0 );
}
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "No matched ciphersuite" ) );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_select_ciphersuite_for_resumption(
mbedtls_ssl_context *ssl,
const unsigned char *cipher_suites,
const unsigned char *cipher_suites_end,
mbedtls_ssl_session *session,
uint16_t *selected_ciphersuite,
const mbedtls_ssl_ciphersuite_t **selected_ciphersuite_info )
{
*selected_ciphersuite = 0;
*selected_ciphersuite_info = NULL;
for( const unsigned char *p = cipher_suites; p < cipher_suites_end; p += 2 )
{
uint16_t cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 );
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
if( cipher_suite != session->ciphersuite )
continue;
ciphersuite_info = ssl_tls13_validate_peer_ciphersuite( ssl,
cipher_suite );
if( ciphersuite_info == NULL )
continue;
*selected_ciphersuite = cipher_suite;
*selected_ciphersuite_info = ciphersuite_info;
return( 0 );
}
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_session_copy_ticket( mbedtls_ssl_session *dst,
const mbedtls_ssl_session *src )
{
dst->ticket_age_add = src->ticket_age_add;
dst->ticket_flags = src->ticket_flags;
dst->resumption_key_len = src->resumption_key_len;
if( src->resumption_key_len == 0 )
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
memcpy( dst->resumption_key, src->resumption_key, src->resumption_key_len );
return( 0 );
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
/* Parser for pre_shared_key extension in client hello
* struct {
* opaque identity<1..2^16-1>;
* uint32 obfuscated_ticket_age;
* } PskIdentity;
*
* opaque PskBinderEntry<32..255>;
*
* struct {
* PskIdentity identities<7..2^16-1>;
* PskBinderEntry binders<33..2^16-1>;
* } OfferedPsks;
*
* struct {
* select (Handshake.msg_type) {
* case client_hello: OfferedPsks;
* ....
* };
* } PreSharedKeyExtension;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
const unsigned char *pre_shared_key_ext,
const unsigned char *pre_shared_key_ext_end,
const unsigned char *ciphersuites,
const unsigned char *ciphersuites_end )
{
const unsigned char *identities = pre_shared_key_ext;
const unsigned char *p_identity_len;
size_t identities_len;
const unsigned char *identities_end;
const unsigned char *binders;
const unsigned char *p_binder_len;
size_t binders_len;
const unsigned char *binders_end;
int matched_identity = -1;
int identity_id = -1;
MBEDTLS_SSL_DEBUG_BUF( 3, "pre_shared_key extension",
pre_shared_key_ext,
pre_shared_key_ext_end - pre_shared_key_ext );
/* identities_len 2 bytes
* identities_data >= 7 bytes
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( identities, pre_shared_key_ext_end, 7 + 2 );
identities_len = MBEDTLS_GET_UINT16_BE( identities, 0 );
p_identity_len = identities + 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p_identity_len, pre_shared_key_ext_end,
identities_len );
identities_end = p_identity_len + identities_len;
/* binders_len 2 bytes
* binders >= 33 bytes
*/
binders = identities_end;
MBEDTLS_SSL_CHK_BUF_READ_PTR( binders, pre_shared_key_ext_end, 33 + 2 );
binders_len = MBEDTLS_GET_UINT16_BE( binders, 0 );
p_binder_len = binders + 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p_binder_len, pre_shared_key_ext_end, binders_len );
binders_end = p_binder_len + binders_len;
ssl->handshake->update_checksum( ssl, pre_shared_key_ext,
identities_end - pre_shared_key_ext );
while( p_identity_len < identities_end && p_binder_len < binders_end )
{
const unsigned char *identity;
size_t identity_len;
uint32_t obfuscated_ticket_age;
const unsigned char *binder;
size_t binder_len;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
int psk_type;
uint16_t cipher_suite;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
mbedtls_ssl_session session;
mbedtls_ssl_session_init( &session );
#endif
MBEDTLS_SSL_CHK_BUF_READ_PTR( p_identity_len, identities_end, 2 + 1 + 4 );
identity_len = MBEDTLS_GET_UINT16_BE( p_identity_len, 0 );
identity = p_identity_len + 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( identity, identities_end, identity_len + 4 );
obfuscated_ticket_age = MBEDTLS_GET_UINT32_BE( identity , identity_len );
p_identity_len += identity_len + 6;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p_binder_len, binders_end, 1 + 32 );
binder_len = *p_binder_len;
binder = p_binder_len + 1;
MBEDTLS_SSL_CHK_BUF_READ_PTR( binder, binders_end, binder_len );
p_binder_len += binder_len + 1;
identity_id++;
if( matched_identity != -1 )
continue;
ret = ssl_tls13_offered_psks_check_identity_match(
ssl, identity, identity_len, obfuscated_ticket_age,
&psk_type, &session );
if( ret != SSL_TLS1_3_OFFERED_PSK_MATCH )
continue;
MBEDTLS_SSL_DEBUG_MSG( 4, ( "found matched identity" ) );
switch( psk_type )
{
case MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL:
ret = ssl_tls13_select_ciphersuite_for_psk(
ssl, ciphersuites, ciphersuites_end,
&cipher_suite, &ciphersuite_info );
break;
case MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION:
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
ret = ssl_tls13_select_ciphersuite_for_resumption(
ssl, ciphersuites, ciphersuites_end, &session,
&cipher_suite, &ciphersuite_info );
if( ret != 0 )
mbedtls_ssl_session_free( &session );
#else
ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
#endif
break;
default:
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
if( ret != 0 )
{
/* See below, no cipher_suite available, abort handshake */
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
MBEDTLS_SSL_DEBUG_RET(
2, "ssl_tls13_select_ciphersuite", ret );
return( ret );
}
ret = ssl_tls13_offered_psks_check_binder_match(
ssl, binder, binder_len, psk_type,
mbedtls_psa_translate_md( ciphersuite_info->mac ) );
if( ret != SSL_TLS1_3_OFFERED_PSK_MATCH )
{
/* For security reasons, the handshake should be aborted when we
* fail to validate a binder value. See RFC 8446 section 4.2.11.2
* and appendix E.6. */
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
mbedtls_ssl_session_free( &session );
#endif
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Invalid binder." ) );
MBEDTLS_SSL_DEBUG_RET( 1,
"ssl_tls13_offered_psks_check_binder_match" , ret );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( ret );
}
matched_identity = identity_id;
/* Update handshake parameters */
ssl->handshake->ciphersuite_info = ciphersuite_info;
ssl->session_negotiate->ciphersuite = cipher_suite;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "overwrite ciphersuite: %04x - %s",
cipher_suite, ciphersuite_info->name ) );
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
if( psk_type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION )
{
ret = ssl_tls13_session_copy_ticket( ssl->session_negotiate,
&session );
mbedtls_ssl_session_free( &session );
if( ret != 0 )
return( ret );
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
}
if( p_identity_len != identities_end || p_binder_len != binders_end )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key extesion decode error" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
MBEDTLS_ERR_SSL_DECODE_ERROR );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
/* Update the handshake transcript with the binder list. */
ssl->handshake->update_checksum( ssl,
identities_end,
(size_t)( binders_end - identities_end ) );
if( matched_identity == -1 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "No matched PSK or ticket." ) );
return( MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
}
ssl->handshake->selected_identity = (uint16_t)matched_identity;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Pre shared key found" ) );
return( 0 );
}
/*
* struct {
* select ( Handshake.msg_type ) {
* ....
* case server_hello:
* uint16 selected_identity;
* }
* } PreSharedKeyExtension;
*/
static int ssl_tls13_write_server_pre_shared_key_ext( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *olen )
{
unsigned char *p = (unsigned char*)buf;
*olen = 0;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if( mbedtls_svc_key_id_is_null( ssl->handshake->psk_opaque ) )
#else
if( ssl->handshake->psk == NULL )
#endif
{
/* We shouldn't have called this extension writer unless we've
* chosen to use a PSK. */
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding pre_shared_key extension" ) );
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_PRE_SHARED_KEY, p, 0 );
MBEDTLS_PUT_UINT16_BE( 2, p, 2 );
MBEDTLS_PUT_UINT16_BE( ssl->handshake->selected_identity, p, 4 );
*olen = 6;
MBEDTLS_SSL_DEBUG_MSG( 4, ( "sent selected_identity: %u",
ssl->handshake->selected_identity ) );
return( 0 );
}
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
/* From RFC 8446:
* struct {
* ProtocolVersion versions<2..254>;
* } SupportedVersions;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_supported_versions_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
const unsigned char *p = buf;
size_t versions_len;
const unsigned char *versions_end;
uint16_t tls_version;
int tls13_supported = 0;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
versions_len = p[0];
p += 1;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, versions_len );
versions_end = p + versions_len;
while( p < versions_end )
{
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, versions_end, 2 );
tls_version = mbedtls_ssl_read_version( p, ssl->conf->transport );
p += 2;
/* In this implementation we only support TLS 1.3 and DTLS 1.3. */
if( tls_version == MBEDTLS_SSL_VERSION_TLS1_3 )
{
tls13_supported = 1;
break;
}
}
if( !tls13_supported )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS 1.3 is not supported by the client" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION,
MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
return( MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
}
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Negotiated version. Supported is [%04x]",
(unsigned int)tls_version ) );
return( 0 );
}
#if defined(MBEDTLS_ECDH_C)
/*
*
* From RFC 8446:
* enum {
* ... (0xFFFF)
* } NamedGroup;
* struct {
* NamedGroup named_group_list<2..2^16-1>;
* } NamedGroupList;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_supported_groups_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
const unsigned char *p = buf;
size_t named_group_list_len;
const unsigned char *named_group_list_end;
MBEDTLS_SSL_DEBUG_BUF( 3, "supported_groups extension", p, end - buf );
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
named_group_list_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, named_group_list_len );
named_group_list_end = p + named_group_list_len;
ssl->handshake->hrr_selected_group = 0;
while( p < named_group_list_end )
{
uint16_t named_group;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, named_group_list_end, 2 );
named_group = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_DEBUG_MSG( 2,
( "got named group: %s(%04x)",
mbedtls_ssl_named_group_to_str( named_group ),
named_group ) );
if( ! mbedtls_ssl_named_group_is_offered( ssl, named_group ) ||
! mbedtls_ssl_named_group_is_supported( named_group ) ||
ssl->handshake->hrr_selected_group != 0 )
{
continue;
}
MBEDTLS_SSL_DEBUG_MSG( 2,
( "add named group %s(%04x) into received list.",
mbedtls_ssl_named_group_to_str( named_group ),
named_group ) );
ssl->handshake->hrr_selected_group = named_group;
}
return( 0 );
}
#endif /* MBEDTLS_ECDH_C */
#define SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH 1
#if defined(MBEDTLS_ECDH_C)
/*
* ssl_tls13_parse_key_shares_ext() verifies whether the information in the
* extension is correct and stores the first acceptable key share and its associated group.
*
* Possible return values are:
* - 0: Successful processing of the client provided key share extension.
* - SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH: The key shares provided by the client
* does not match a group supported by the server. A HelloRetryRequest will
* be needed.
* - A negative value for fatal errors.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_key_shares_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char const *p = buf;
unsigned char const *client_shares_end;
size_t client_shares_len;
/* From RFC 8446:
*
* struct {
* KeyShareEntry client_shares<0..2^16-1>;
* } KeyShareClientHello;
*
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
client_shares_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, client_shares_len );
ssl->handshake->offered_group_id = 0;
client_shares_end = p + client_shares_len;
/* We try to find a suitable key share entry and copy it to the
* handshake context. Later, we have to find out whether we can do
* something with the provided key share or whether we have to
* dismiss it and send a HelloRetryRequest message.
*/
while( p < client_shares_end )
{
uint16_t group;
size_t key_exchange_len;
const unsigned char *key_exchange;
/*
* struct {
* NamedGroup group;
* opaque key_exchange<1..2^16-1>;
* } KeyShareEntry;
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, client_shares_end, 4 );
group = MBEDTLS_GET_UINT16_BE( p, 0 );
key_exchange_len = MBEDTLS_GET_UINT16_BE( p, 2 );
p += 4;
key_exchange = p;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, client_shares_end, key_exchange_len );
p += key_exchange_len;
/* Continue parsing even if we have already found a match,
* for input validation purposes.
*/
if( ! mbedtls_ssl_named_group_is_offered( ssl, group ) ||
! mbedtls_ssl_named_group_is_supported( group ) ||
ssl->handshake->offered_group_id != 0 )
{
continue;
}
/*
* For now, we only support ECDHE groups.
*/
if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH group: %s (%04x)",
mbedtls_ssl_named_group_to_str( group ),
group ) );
ret = mbedtls_ssl_tls13_read_public_ecdhe_share(
ssl, key_exchange - 2, key_exchange_len + 2 );
if( ret != 0 )
return( ret );
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Unrecognized NamedGroup %u",
(unsigned) group ) );
continue;
}
ssl->handshake->offered_group_id = group;
}
if( ssl->handshake->offered_group_id == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "no matching key share" ) );
return( SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH );
}
return( 0 );
}
#endif /* MBEDTLS_ECDH_C */
#if defined(MBEDTLS_DEBUG_C)
static void ssl_tls13_debug_print_client_hello_exts( mbedtls_ssl_context *ssl )
{
((void) ssl);
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Supported Extensions:" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- KEY_SHARE_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_KEY_SHARE ) > 0 ) ? "TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- PSK_KEY_EXCHANGE_MODES_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) > 0 ) ?
"TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- PRE_SHARED_KEY_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) > 0 ) ? "TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- SIGNATURE_ALGORITHM_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_SIG_ALG ) > 0 ) ? "TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- SUPPORTED_GROUPS_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_SUPPORTED_GROUPS ) >0 ) ?
"TRUE" : "FALSE" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- SUPPORTED_VERSION_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS ) > 0 ) ?
"TRUE" : "FALSE" ) );
#if defined ( MBEDTLS_SSL_SERVER_NAME_INDICATION )
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- SERVERNAME_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_SERVERNAME ) > 0 ) ?
"TRUE" : "FALSE" ) );
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
#if defined ( MBEDTLS_SSL_ALPN )
MBEDTLS_SSL_DEBUG_MSG( 3,
( "- ALPN_EXTENSION ( %s )",
( ( ssl->handshake->extensions_present
& MBEDTLS_SSL_EXT_ALPN ) > 0 ) ?
"TRUE" : "FALSE" ) );
#endif /* MBEDTLS_SSL_ALPN */
}
#endif /* MBEDTLS_DEBUG_C */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_client_hello_has_exts( mbedtls_ssl_context *ssl,
int exts_mask )
{
int masked = ssl->handshake->extensions_present & exts_mask;
return( masked == exts_mask );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange(
mbedtls_ssl_context *ssl )
{
return( ssl_tls13_client_hello_has_exts(
ssl,
MBEDTLS_SSL_EXT_SUPPORTED_GROUPS |
MBEDTLS_SSL_EXT_KEY_SHARE |
MBEDTLS_SSL_EXT_SIG_ALG ) );
}
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_client_hello_has_exts_for_psk_key_exchange(
mbedtls_ssl_context *ssl )
{
return( ssl_tls13_client_hello_has_exts(
ssl,
MBEDTLS_SSL_EXT_PRE_SHARED_KEY |
MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange(
mbedtls_ssl_context *ssl )
{
return( ssl_tls13_client_hello_has_exts(
ssl,
MBEDTLS_SSL_EXT_SUPPORTED_GROUPS |
MBEDTLS_SSL_EXT_KEY_SHARE |
MBEDTLS_SSL_EXT_PRE_SHARED_KEY |
MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) );
}
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_check_ephemeral_key_exchange( mbedtls_ssl_context *ssl )
{
return( mbedtls_ssl_conf_tls13_ephemeral_enabled( ssl ) &&
ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange( ssl ) );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_check_psk_key_exchange( mbedtls_ssl_context *ssl )
{
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
return( mbedtls_ssl_conf_tls13_psk_enabled( ssl ) &&
mbedtls_ssl_tls13_psk_enabled( ssl ) &&
ssl_tls13_client_hello_has_exts_for_psk_key_exchange( ssl ) );
#else
((void) ssl);
return( 0 );
#endif
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_check_psk_ephemeral_key_exchange( mbedtls_ssl_context *ssl )
{
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
return( mbedtls_ssl_conf_tls13_psk_ephemeral_enabled( ssl ) &&
mbedtls_ssl_tls13_psk_ephemeral_enabled( ssl ) &&
ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange( ssl ) );
#else
((void) ssl);
return( 0 );
#endif
}
static int ssl_tls13_determine_key_exchange_mode( mbedtls_ssl_context *ssl )
{
/*
* Determine the key exchange algorithm to use.
* There are three types of key exchanges supported in TLS 1.3:
* - (EC)DH with ECDSA,
* - (EC)DH with PSK,
* - plain PSK.
*
* The PSK-based key exchanges may additionally be used with 0-RTT.
*
* Our built-in order of preference is
* 1 ) (EC)DHE-PSK Mode ( psk_ephemeral )
* 2 ) Certificate Mode ( ephemeral )
* 3 ) Plain PSK Mode ( psk )
*/
ssl->handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE;
if( ssl_tls13_check_psk_ephemeral_key_exchange( ssl ) )
{
ssl->handshake->key_exchange_mode =
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: psk_ephemeral" ) );
}
else
if( ssl_tls13_check_ephemeral_key_exchange( ssl ) )
{
ssl->handshake->key_exchange_mode =
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: ephemeral" ) );
}
else
if( ssl_tls13_check_psk_key_exchange( ssl ) )
{
ssl->handshake->key_exchange_mode =
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: psk" ) );
}
else
{
MBEDTLS_SSL_DEBUG_MSG(
1,
( "ClientHello message misses mandatory extensions." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION ,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
return( 0 );
}
#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
static psa_algorithm_t ssl_tls13_iana_sig_alg_to_psa_alg( uint16_t sig_alg )
{
switch( sig_alg )
{
case MBEDTLS_TLS1_3_SIG_ECDSA_SECP256R1_SHA256:
return( PSA_ALG_ECDSA( PSA_ALG_SHA_256 ) );
case MBEDTLS_TLS1_3_SIG_ECDSA_SECP384R1_SHA384:
return( PSA_ALG_ECDSA( PSA_ALG_SHA_384 ) );
case MBEDTLS_TLS1_3_SIG_ECDSA_SECP521R1_SHA512:
return( PSA_ALG_ECDSA( PSA_ALG_SHA_512 ) );
case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA256:
return( PSA_ALG_RSA_PSS( PSA_ALG_SHA_256 ) );
case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA384:
return( PSA_ALG_RSA_PSS( PSA_ALG_SHA_384 ) );
case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA512:
return( PSA_ALG_RSA_PSS( PSA_ALG_SHA_512 ) );
case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA256:
return( PSA_ALG_RSA_PKCS1V15_SIGN( PSA_ALG_SHA_256 ) );
case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA384:
return( PSA_ALG_RSA_PKCS1V15_SIGN( PSA_ALG_SHA_384 ) );
case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA512:
return( PSA_ALG_RSA_PKCS1V15_SIGN( PSA_ALG_SHA_512 ) );
default:
return( PSA_ALG_NONE );
}
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
/*
* Pick best ( private key, certificate chain ) pair based on the signature
* algorithms supported by the client.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_pick_key_cert( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_key_cert *key_cert, *key_cert_list;
const uint16_t *sig_alg = ssl->handshake->received_sig_algs;
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
if( ssl->handshake->sni_key_cert != NULL )
key_cert_list = ssl->handshake->sni_key_cert;
else
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
key_cert_list = ssl->conf->key_cert;
if( key_cert_list == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server has no certificate" ) );
return( -1 );
}
for( ; *sig_alg != MBEDTLS_TLS1_3_SIG_NONE; sig_alg++ )
{
if( !mbedtls_ssl_sig_alg_is_offered( ssl, *sig_alg ) )
continue;
if( !mbedtls_ssl_tls13_sig_alg_for_cert_verify_is_supported( *sig_alg ) )
continue;
for( key_cert = key_cert_list; key_cert != NULL;
key_cert = key_cert->next )
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_algorithm_t psa_alg = PSA_ALG_NONE;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
MBEDTLS_SSL_DEBUG_CRT( 3, "certificate (chain) candidate",
key_cert->cert );
/*
* This avoids sending the client a cert it'll reject based on
* keyUsage or other extensions.
*/
if( mbedtls_x509_crt_check_key_usage(
key_cert->cert, MBEDTLS_X509_KU_DIGITAL_SIGNATURE ) != 0 ||
mbedtls_x509_crt_check_extended_key_usage(
key_cert->cert, MBEDTLS_OID_SERVER_AUTH,
MBEDTLS_OID_SIZE( MBEDTLS_OID_SERVER_AUTH ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "certificate mismatch: "
"(extended) key usage extension" ) );
continue;
}
MBEDTLS_SSL_DEBUG_MSG( 3,
( "ssl_tls13_pick_key_cert:"
"check signature algorithm %s [%04x]",
mbedtls_ssl_sig_alg_to_str( *sig_alg ),
*sig_alg ) );
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_alg = ssl_tls13_iana_sig_alg_to_psa_alg( *sig_alg );
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if( mbedtls_ssl_tls13_check_sig_alg_cert_key_match(
*sig_alg, &key_cert->cert->pk )
#if defined(MBEDTLS_USE_PSA_CRYPTO)
&& psa_alg != PSA_ALG_NONE &&
mbedtls_pk_can_do_ext( &key_cert->cert->pk, psa_alg,
PSA_KEY_USAGE_SIGN_HASH ) == 1
#endif /* MBEDTLS_USE_PSA_CRYPTO */
)
{
ssl->handshake->key_cert = key_cert;
MBEDTLS_SSL_DEBUG_MSG( 3,
( "ssl_tls13_pick_key_cert:"
"selected signature algorithm"
" %s [%04x]",
mbedtls_ssl_sig_alg_to_str( *sig_alg ),
*sig_alg ) );
MBEDTLS_SSL_DEBUG_CRT(
3, "selected certificate (chain)",
ssl->handshake->key_cert->cert );
return( 0 );
}
}
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "ssl_tls13_pick_key_cert:"
"no suitable certificate found" ) );
return( -1 );
}
#endif /* MBEDTLS_X509_CRT_PARSE_C &&
MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
/*
*
* STATE HANDLING: ClientHello
*
* There are three possible classes of outcomes when parsing the ClientHello:
*
* 1) The ClientHello was well-formed and matched the server's configuration.
*
* In this case, the server progresses to sending its ServerHello.
*
* 2) The ClientHello was well-formed but didn't match the server's
* configuration.
*
* For example, the client might not have offered a key share which
* the server supports, or the server might require a cookie.
*
* In this case, the server sends a HelloRetryRequest.
*
* 3) The ClientHello was ill-formed
*
* In this case, we abort the handshake.
*
*/
/*
* Structure of this message:
*
* uint16 ProtocolVersion;
* opaque Random[32];
* uint8 CipherSuite[2]; // Cryptographic suite selector
*
* struct {
* ProtocolVersion legacy_version = 0x0303; // TLS v1.2
* Random random;
* opaque legacy_session_id<0..32>;
* CipherSuite cipher_suites<2..2^16-2>;
* opaque legacy_compression_methods<1..2^8-1>;
* Extension extensions<8..2^16-1>;
* } ClientHello;
*/
#define SSL_CLIENT_HELLO_OK 0
#define SSL_CLIENT_HELLO_HRR_REQUIRED 1
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const unsigned char *p = buf;
size_t legacy_session_id_len;
size_t cipher_suites_len;
const unsigned char *cipher_suites_end;
size_t extensions_len;
const unsigned char *extensions_end;
int hrr_required = 0;
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
const unsigned char *cipher_suites;
const unsigned char *pre_shared_key_ext = NULL;
const unsigned char *pre_shared_key_ext_end = NULL;
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
/*
* ClientHello layout:
* 0 . 1 protocol version
* 2 . 33 random bytes
* 34 . 34 session id length ( 1 byte )
* 35 . 34+x session id
* .. . .. ciphersuite list length ( 2 bytes )
* .. . .. ciphersuite list
* .. . .. compression alg. list length ( 1 byte )
* .. . .. compression alg. list
* .. . .. extensions length ( 2 bytes, optional )
* .. . .. extensions ( optional )
*/
/*
* Minimal length ( with everything empty and extensions omitted ) is
* 2 + 32 + 1 + 2 + 1 = 38 bytes. Check that first, so that we can
* read at least up to session id length without worrying.
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 38 );
/* ...
* ProtocolVersion legacy_version = 0x0303; // TLS 1.2
* ...
* with ProtocolVersion defined as:
* uint16 ProtocolVersion;
*/
if( mbedtls_ssl_read_version( p, ssl->conf->transport ) !=
MBEDTLS_SSL_VERSION_TLS1_2 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Unsupported version of TLS." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION,
MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
return ( MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
}
p += 2;
/*
* Only support TLS 1.3 currently, temporarily set the version.
*/
ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_3;
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
/* Store minor version for later use with ticket serialization. */
ssl->session_negotiate->tls_version = MBEDTLS_SSL_VERSION_TLS1_3;
ssl->session_negotiate->endpoint = ssl->conf->endpoint;
#endif
/* ...
* Random random;
* ...
* with Random defined as:
* opaque Random[32];
*/
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes",
p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
memcpy( &ssl->handshake->randbytes[0], p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN;
/* ...
* opaque legacy_session_id<0..32>;
* ...
*/
legacy_session_id_len = p[0];
p++;
if( legacy_session_id_len > sizeof( ssl->session_negotiate->id ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
ssl->session_negotiate->id_len = legacy_session_id_len;
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, session id",
p, legacy_session_id_len );
/*
* Check we have enough data for the legacy session identifier
* and the ciphersuite list length.
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, legacy_session_id_len + 2 );
memcpy( &ssl->session_negotiate->id[0], p, legacy_session_id_len );
p += legacy_session_id_len;
cipher_suites_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
/* Check we have enough data for the ciphersuite list, the legacy
* compression methods and the length of the extensions.
*
* cipher_suites cipher_suites_len bytes
* legacy_compression_methods 2 bytes
* extensions_len 2 bytes
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, cipher_suites_len + 2 + 2 );
/* ...
* CipherSuite cipher_suites<2..2^16-2>;
* ...
* with CipherSuite defined as:
* uint8 CipherSuite[2];
*/
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
cipher_suites = p;
#endif
cipher_suites_end = p + cipher_suites_len;
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, ciphersuitelist",
p, cipher_suites_len );
/*
* Search for a matching ciphersuite
*/
for ( ; p < cipher_suites_end; p += 2 )
{
uint16_t cipher_suite;
const mbedtls_ssl_ciphersuite_t* ciphersuite_info;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, cipher_suites_end, 2 );
cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 );
ciphersuite_info = ssl_tls13_validate_peer_ciphersuite(
ssl,cipher_suite );
if( ciphersuite_info == NULL )
continue;
ssl->session_negotiate->ciphersuite = cipher_suite;
ssl->handshake->ciphersuite_info = ciphersuite_info;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "selected ciphersuite: %04x - %s",
cipher_suite,
ciphersuite_info->name ) );
}
if( ssl->handshake->ciphersuite_info == NULL )
{
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return ( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
/* ...
* opaque legacy_compression_methods<1..2^8-1>;
* ...
*/
if( p[0] != 1 || p[1] != MBEDTLS_SSL_COMPRESS_NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad legacy compression method" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
return ( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
p += 2;
/* ...
* Extension extensions<8..2^16-1>;
* ...
* with Extension defined as:
* struct {
* ExtensionType extension_type;
* opaque extension_data<0..2^16-1>;
* } Extension;
*/
extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, extensions_len );
extensions_end = p + extensions_len;
MBEDTLS_SSL_DEBUG_BUF( 3, "client hello extensions", p, extensions_len );
while( p < extensions_end )
{
unsigned int extension_type;
size_t extension_data_len;
const unsigned char *extension_data_end;
/* RFC 8446, page 57
*
* The "pre_shared_key" extension MUST be the last extension in the
* ClientHello (this facilitates implementation as described below).
* Servers MUST check that it is the last extension and otherwise fail
* the handshake with an "illegal_parameter" alert.
*/
if( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY )
{
MBEDTLS_SSL_DEBUG_MSG(
3, ( "pre_shared_key is not last extension." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
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_SERVER_NAME_INDICATION)
case MBEDTLS_TLS_EXT_SERVERNAME:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found ServerName extension" ) );
ret = mbedtls_ssl_parse_server_name_ext( ssl, p,
extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, "mbedtls_ssl_parse_servername_ext", ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SERVERNAME;
break;
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
#if defined(MBEDTLS_ECDH_C)
case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found supported group extension" ) );
/* Supported Groups Extension
*
* When sent by the client, the "supported_groups" extension
* indicates the named groups which the client supports,
* ordered from most preferred to least preferred.
*/
ret = ssl_tls13_parse_supported_groups_ext(
ssl, p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"mbedtls_ssl_parse_supported_groups_ext", ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_GROUPS;
break;
#endif /* MBEDTLS_ECDH_C */
#if defined(MBEDTLS_ECDH_C)
case MBEDTLS_TLS_EXT_KEY_SHARE:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found key share extension" ) );
/*
* Key Share Extension
*
* When sent by the client, the "key_share" extension
* contains the endpoint's cryptographic parameters for
* ECDHE/DHE key establishment methods.
*/
ret = ssl_tls13_parse_key_shares_ext(
ssl, p, extension_data_end );
if( ret == SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "HRR needed " ) );
hrr_required = 1;
}
if( ret < 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, "ssl_tls13_parse_key_shares_ext", ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE;
break;
#endif /* MBEDTLS_ECDH_C */
case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found supported versions extension" ) );
ret = ssl_tls13_parse_supported_versions_ext(
ssl, p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
( "ssl_tls13_parse_supported_versions_ext" ), ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS;
break;
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
case MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found psk key exchange modes extension" ) );
ret = ssl_tls13_parse_key_exchange_modes_ext(
ssl, p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, "ssl_tls13_parse_key_exchange_modes_ext", ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES;
break;
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension" ) );
if( ( ssl->handshake->extensions_present &
MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) == 0 )
{
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
/* Delay processing of the PSK identity once we have
* found out which algorithms to use. We keep a pointer
* to the buffer and the size for later processing.
*/
pre_shared_key_ext = p;
pre_shared_key_ext_end = extension_data_end;
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
break;
#if defined(MBEDTLS_SSL_ALPN)
case MBEDTLS_TLS_EXT_ALPN:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found alpn extension" ) );
ret = mbedtls_ssl_parse_alpn_ext( ssl, p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, ( "mbedtls_ssl_parse_alpn_ext" ), ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_ALPN;
break;
#endif /* MBEDTLS_SSL_ALPN */
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
case MBEDTLS_TLS_EXT_SIG_ALG:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found signature_algorithms extension" ) );
ret = mbedtls_ssl_parse_sig_alg_ext(
ssl, p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
( "ssl_parse_supported_signature_algorithms_server_ext ( %d )",
ret ) );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SIG_ALG;
break;
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
default:
MBEDTLS_SSL_DEBUG_MSG( 3,
( "unknown extension found: %ud ( ignoring )",
extension_type ) );
}
p += extension_data_len;
}
#if defined(MBEDTLS_DEBUG_C)
/* List all the extensions we have received */
ssl_tls13_debug_print_client_hello_exts( ssl );
#endif /* MBEDTLS_DEBUG_C */
mbedtls_ssl_add_hs_hdr_to_checksum( ssl,
MBEDTLS_SSL_HS_CLIENT_HELLO,
p - buf );
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
/* Update checksum with either
* - The entire content of the CH message, if no PSK extension is present
* - The content up to but excluding the PSK extension, if present.
*/
/* If we've settled on a PSK-based exchange, parse PSK identity ext */
if( mbedtls_ssl_tls13_some_psk_enabled( ssl ) &&
mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) &&
( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) )
{
ssl->handshake->update_checksum( ssl, buf,
pre_shared_key_ext - buf );
ret = ssl_tls13_parse_pre_shared_key_ext( ssl,
pre_shared_key_ext,
pre_shared_key_ext_end,
cipher_suites,
cipher_suites_end );
if( ret == MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY )
{
ssl->handshake->extensions_present &= ~MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
}
else if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_pre_shared_key_ext" ),
ret );
return( ret );
}
}
else
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
{
ssl->handshake->update_checksum( ssl, buf, p - buf );
}
ret = ssl_tls13_determine_key_exchange_mode( ssl );
if( ret < 0 )
return( ret );
mbedtls_ssl_optimize_checksum( ssl, ssl->handshake->ciphersuite_info );
return( hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK );
}
/* Update the handshake state machine */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_postprocess_client_hello( mbedtls_ssl_context* ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/*
* Server certificate selection
*/
if( ssl->conf->f_cert_cb && ( ret = ssl->conf->f_cert_cb( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "f_cert_cb", ret );
return( ret );
}
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
ssl->handshake->sni_name = NULL;
ssl->handshake->sni_name_len = 0;
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
ret = mbedtls_ssl_tls13_key_schedule_stage_early( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"mbedtls_ssl_tls1_3_key_schedule_stage_early", ret );
return( ret );
}
return( 0 );
}
/*
* Main entry point from the state machine; orchestrates the otherfunctions.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_process_client_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char* buf = NULL;
size_t buflen = 0;
int parse_client_hello_ret;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse client hello" ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_fetch_handshake_msg(
ssl, MBEDTLS_SSL_HS_CLIENT_HELLO,
&buf, &buflen ) );
MBEDTLS_SSL_PROC_CHK_NEG( ssl_tls13_parse_client_hello( ssl, buf,
buf + buflen ) );
parse_client_hello_ret = ret; /* Store return value of parse_client_hello,
* only SSL_CLIENT_HELLO_OK or
* SSL_CLIENT_HELLO_HRR_REQUIRED at this
* stage as negative error codes are handled
* by MBEDTLS_SSL_PROC_CHK_NEG. */
MBEDTLS_SSL_PROC_CHK( ssl_tls13_postprocess_client_hello( ssl ) );
if( parse_client_hello_ret == SSL_CLIENT_HELLO_OK )
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_HELLO );
else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HELLO_RETRY_REQUEST );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse client hello" ) );
return( ret );
}
/*
* Handler for MBEDTLS_SSL_SERVER_HELLO
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_prepare_server_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *server_randbytes =
ssl->handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN;
if( ssl->conf->f_rng == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "no RNG provided" ) );
return( MBEDTLS_ERR_SSL_NO_RNG );
}
if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng, server_randbytes,
MBEDTLS_SERVER_HELLO_RANDOM_LEN ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "f_rng", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, random bytes", server_randbytes,
MBEDTLS_SERVER_HELLO_RANDOM_LEN );
#if defined(MBEDTLS_HAVE_TIME)
ssl->session_negotiate->start = time( NULL );
#endif /* MBEDTLS_HAVE_TIME */
return( ret );
}
/*
* ssl_tls13_write_server_hello_supported_versions_ext ():
*
* struct {
* ProtocolVersion selected_version;
* } SupportedVersions;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_server_hello_supported_versions_ext(
mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
*out_len = 0;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, write selected version" ) );
/* Check if we have space to write the extension:
* - extension_type (2 bytes)
* - extension_data_length (2 bytes)
* - selected_version (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( buf, end, 6 );
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, buf, 0 );
MBEDTLS_PUT_UINT16_BE( 2, buf, 2 );
mbedtls_ssl_write_version( buf + 4,
ssl->conf->transport,
ssl->tls_version );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "supported version: [%04x]",
ssl->tls_version ) );
*out_len = 6;
return( 0 );
}
/* Generate and export a single key share. For hybrid KEMs, this can
* be called multiple times with the different components of the hybrid. */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_generate_and_write_key_share( mbedtls_ssl_context *ssl,
uint16_t named_group,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
*out_len = 0;
#if defined(MBEDTLS_ECDH_C)
if( mbedtls_ssl_tls13_named_group_is_ecdhe( named_group ) )
{
ret = mbedtls_ssl_tls13_generate_and_write_ecdh_key_exchange(
ssl, named_group, buf, end, out_len );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, "mbedtls_ssl_tls13_generate_and_write_ecdh_key_exchange",
ret );
return( ret );
}
}
else
#endif /* MBEDTLS_ECDH_C */
if( 0 /* Other kinds of KEMs */ )
{
}
else
{
((void) ssl);
((void) named_group);
((void) buf);
((void) end);
ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
return( ret );
}
/*
* ssl_tls13_write_key_share_ext
*
* Structure of key_share extension in ServerHello:
*
* struct {
* NamedGroup group;
* opaque key_exchange<1..2^16-1>;
* } KeyShareEntry;
* struct {
* KeyShareEntry server_share;
* } KeyShareServerHello;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_key_share_ext( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
uint16_t group = ssl->handshake->offered_group_id;
unsigned char *server_share = buf + 4;
size_t key_exchange_length;
*out_len = 0;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding key share extension" ) );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "server hello, write selected_group: %s (%04x)",
mbedtls_ssl_named_group_to_str( group ),
group ) );
/* Check if we have space for header and length fields:
* - extension_type (2 bytes)
* - extension_data_length (2 bytes)
* - group (2 bytes)
* - key_exchange_length (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 8 );
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_KEY_SHARE, p, 0 );
MBEDTLS_PUT_UINT16_BE( group, server_share, 0 );
p += 8;
/* When we introduce PQC-ECDHE hybrids, we'll want to call this
* function multiple times. */
ret = ssl_tls13_generate_and_write_key_share(
ssl, group, server_share + 4, end, &key_exchange_length );
if( ret != 0 )
return( ret );
p += key_exchange_length;
MBEDTLS_PUT_UINT16_BE( key_exchange_length, server_share + 2, 0 );
MBEDTLS_PUT_UINT16_BE( p - server_share, buf, 2 );
*out_len = p - buf;
return( 0 );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_hrr_key_share_ext( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
uint16_t selected_group = ssl->handshake->hrr_selected_group;
/* key_share Extension
*
* struct {
* select (Handshake.msg_type) {
* ...
* case hello_retry_request:
* NamedGroup selected_group;
* ...
* };
* } KeyShare;
*/
*out_len = 0;
/*
* For a pure PSK key exchange, there is no group to agree upon. The purpose
* of the HRR is then to transmit a cookie to force the client to demonstrate
* reachability at their apparent network address (primarily useful for DTLS).
*/
if( ! mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral( ssl ) )
return( 0 );
/* We should only send the key_share extension if the client's initial
* key share was not acceptable. */
if( ssl->handshake->offered_group_id != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Skip key_share extension in HRR" ) );
return( 0 );
}
if( selected_group == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "no matching named group found" ) );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
/* Check if we have enough space:
* - extension_type (2 bytes)
* - extension_data_length (2 bytes)
* - selected_group (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( buf, end, 6 );
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_KEY_SHARE, buf, 0 );
MBEDTLS_PUT_UINT16_BE( 2, buf, 2 );
MBEDTLS_PUT_UINT16_BE( selected_group, buf, 4 );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "HRR selected_group: %s (%x)",
mbedtls_ssl_named_group_to_str( selected_group ),
selected_group ) );
*out_len = 6;
return( 0 );
}
/*
* Structure of ServerHello message:
*
* struct {
* ProtocolVersion legacy_version = 0x0303; // TLS v1.2
* Random random;
* opaque legacy_session_id_echo<0..32>;
* CipherSuite cipher_suite;
* uint8 legacy_compression_method = 0;
* Extension extensions<6..2^16-1>;
* } ServerHello;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_server_hello_body( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len,
int is_hrr )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
unsigned char *p_extensions_len;
size_t output_len;
*out_len = 0;
/* ...
* ProtocolVersion legacy_version = 0x0303; // TLS 1.2
* ...
* with ProtocolVersion defined as:
* uint16 ProtocolVersion;
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
MBEDTLS_PUT_UINT16_BE( 0x0303, p, 0 );
p += 2;
/* ...
* Random random;
* ...
* with Random defined as:
* opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN];
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN );
if( is_hrr )
{
memcpy( p, mbedtls_ssl_tls13_hello_retry_request_magic,
MBEDTLS_SERVER_HELLO_RANDOM_LEN );
}
else
{
memcpy( p, &ssl->handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN],
MBEDTLS_SERVER_HELLO_RANDOM_LEN );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, random bytes",
p, MBEDTLS_SERVER_HELLO_RANDOM_LEN );
p += MBEDTLS_SERVER_HELLO_RANDOM_LEN;
/* ...
* opaque legacy_session_id_echo<0..32>;
* ...
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 1 + ssl->session_negotiate->id_len );
*p++ = (unsigned char)ssl->session_negotiate->id_len;
if( ssl->session_negotiate->id_len > 0 )
{
memcpy( p, &ssl->session_negotiate->id[0],
ssl->session_negotiate->id_len );
p += ssl->session_negotiate->id_len;
MBEDTLS_SSL_DEBUG_BUF( 3, "session id", ssl->session_negotiate->id,
ssl->session_negotiate->id_len );
}
/* ...
* CipherSuite cipher_suite;
* ...
* with CipherSuite defined as:
* uint8 CipherSuite[2];
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
MBEDTLS_PUT_UINT16_BE( ssl->session_negotiate->ciphersuite, p, 0 );
p += 2;
MBEDTLS_SSL_DEBUG_MSG( 3,
( "server hello, chosen ciphersuite: %s ( id=%d )",
mbedtls_ssl_get_ciphersuite_name(
ssl->session_negotiate->ciphersuite ),
ssl->session_negotiate->ciphersuite ) );
/* ...
* uint8 legacy_compression_method = 0;
* ...
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 1 );
*p++ = MBEDTLS_SSL_COMPRESS_NULL;
/* ...
* Extension extensions<6..2^16-1>;
* ...
* struct {
* ExtensionType extension_type; (2 bytes)
* opaque extension_data<0..2^16-1>;
* } Extension;
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
p_extensions_len = p;
p += 2;
if( ( ret = ssl_tls13_write_server_hello_supported_versions_ext(
ssl, p, end, &output_len ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, "ssl_tls13_write_server_hello_supported_versions_ext", ret );
return( ret );
}
p += output_len;
if( mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral( ssl ) )
{
if( is_hrr )
ret = ssl_tls13_write_hrr_key_share_ext( ssl, p, end, &output_len );
else
ret = ssl_tls13_write_key_share_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
}
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
if( !is_hrr && mbedtls_ssl_tls13_key_exchange_mode_with_psk( ssl ) )
{
ret = ssl_tls13_write_server_pre_shared_key_ext( ssl, p, end, &output_len );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_server_pre_shared_key_ext",
ret );
return( ret );
}
p += output_len;
}
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
MBEDTLS_PUT_UINT16_BE( p - p_extensions_len - 2, p_extensions_len, 0 );
MBEDTLS_SSL_DEBUG_BUF( 4, "server hello extensions",
p_extensions_len, p - p_extensions_len );
*out_len = p - buf;
MBEDTLS_SSL_DEBUG_BUF( 3, "server hello", buf, *out_len );
return( ret );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_finalize_write_server_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
ret = mbedtls_ssl_tls13_compute_handshake_transform( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"mbedtls_ssl_tls13_compute_handshake_transform",
ret );
return( ret );
}
return( ret );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_server_hello( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf;
size_t buf_len, msg_len;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server hello" ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_prepare_server_hello( ssl ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_start_handshake_msg( ssl,
MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_server_hello_body( ssl, buf,
buf + buf_len,
&msg_len,
0 ) );
mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg(
ssl, buf_len, msg_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_write_server_hello( ssl ) );
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
/* The server sends a dummy change_cipher_spec record immediately
* after its first handshake message. This may either be after
* a ServerHello or a HelloRetryRequest.
*/
mbedtls_ssl_handshake_set_state(
ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO );
#else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS );
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write server hello" ) );
return( ret );
}
/*
* Handler for MBEDTLS_SSL_HELLO_RETRY_REQUEST
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_prepare_hello_retry_request( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if( ssl->handshake->hello_retry_request_count > 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Too many HRRs" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
/*
* Create stateless transcript hash for HRR
*/
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Reset transcript for HRR" ) );
ret = mbedtls_ssl_reset_transcript_for_hrr( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_reset_transcript_for_hrr", ret );
return( ret );
}
mbedtls_ssl_session_reset_msg_layer( ssl, 0 );
return( 0 );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_hello_retry_request( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf;
size_t buf_len, msg_len;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write hello retry request" ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_prepare_hello_retry_request( ssl ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_start_handshake_msg(
ssl, MBEDTLS_SSL_HS_SERVER_HELLO,
&buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_server_hello_body( ssl, buf,
buf + buf_len,
&msg_len,
1 ) );
mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg( ssl, buf_len,
msg_len ) );
ssl->handshake->hello_retry_request_count++;
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
/* The server sends a dummy change_cipher_spec record immediately
* after its first handshake message. This may either be after
* a ServerHello or a HelloRetryRequest.
*/
mbedtls_ssl_handshake_set_state(
ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST );
#else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_HELLO );
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write hello retry request" ) );
return( ret );
}
/*
* Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS
*/
/*
* struct {
* Extension extensions<0..2 ^ 16 - 1>;
* } EncryptedExtensions;
*
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_encrypted_extensions_body( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
size_t extensions_len = 0;
unsigned char *p_extensions_len;
size_t output_len;
*out_len = 0;
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
p_extensions_len = p;
p += 2;
((void) ssl);
((void) ret);
((void) output_len);
#if defined(MBEDTLS_SSL_ALPN)
ret = mbedtls_ssl_write_alpn_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
#endif /* MBEDTLS_SSL_ALPN */
extensions_len = ( p - p_extensions_len ) - 2;
MBEDTLS_PUT_UINT16_BE( extensions_len, p_extensions_len, 0 );
*out_len = p - buf;
MBEDTLS_SSL_DEBUG_BUF( 4, "encrypted extensions", buf, *out_len );
return( 0 );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_encrypted_extensions( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf;
size_t buf_len, msg_len;
mbedtls_ssl_set_outbound_transform( ssl,
ssl->handshake->transform_handshake );
MBEDTLS_SSL_DEBUG_MSG(
3, ( "switching to handshake transform for outbound data" ) );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write encrypted extensions" ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_start_handshake_msg( ssl,
MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, &buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_encrypted_extensions_body(
ssl, buf, buf + buf_len, &msg_len ) );
mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, msg_len );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg(
ssl, buf_len, msg_len ) );
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
if( mbedtls_ssl_tls13_key_exchange_mode_with_psk( ssl ) )
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_FINISHED );
else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CERTIFICATE_REQUEST );
#else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_FINISHED );
#endif
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write encrypted extensions" ) );
return( ret );
}
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
#define SSL_CERTIFICATE_REQUEST_SEND_REQUEST 0
#define SSL_CERTIFICATE_REQUEST_SKIP 1
/* Coordination:
* Check whether a CertificateRequest message should be written.
* Returns a negative code on failure, or
* - SSL_CERTIFICATE_REQUEST_SEND_REQUEST
* - SSL_CERTIFICATE_REQUEST_SKIP
* indicating if the writing of the CertificateRequest
* should be skipped or not.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_certificate_request_coordinate( mbedtls_ssl_context *ssl )
{
int authmode;
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
if( ssl->handshake->sni_authmode != MBEDTLS_SSL_VERIFY_UNSET )
authmode = ssl->handshake->sni_authmode;
else
#endif
authmode = ssl->conf->authmode;
if( authmode == MBEDTLS_SSL_VERIFY_NONE )
return( SSL_CERTIFICATE_REQUEST_SKIP );
ssl->handshake->certificate_request_sent = 1;
return( SSL_CERTIFICATE_REQUEST_SEND_REQUEST );
}
/*
* struct {
* opaque certificate_request_context<0..2^8-1>;
* Extension extensions<2..2^16-1>;
* } CertificateRequest;
*
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_certificate_request_body( mbedtls_ssl_context *ssl,
unsigned char *buf,
const unsigned char *end,
size_t *out_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
size_t output_len = 0;
unsigned char *p_extensions_len;
*out_len = 0;
/* Check if we have enough space:
* - certificate_request_context (1 byte)
* - extensions length (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 3 );
/*
* Write certificate_request_context
*/
/*
* We use a zero length context for the normal handshake
* messages. For post-authentication handshake messages
* this request context would be set to a non-zero value.
*/
*p++ = 0x0;
/*
* Write extensions
*/
/* The extensions must contain the signature_algorithms. */
p_extensions_len = p;
p += 2;
ret = mbedtls_ssl_write_sig_alg_ext( ssl, p, end, &output_len );
if( ret != 0 )
return( ret );
p += output_len;
MBEDTLS_PUT_UINT16_BE( p - p_extensions_len - 2, p_extensions_len, 0 );
*out_len = p - buf;
return( 0 );
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_certificate_request( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate request" ) );
MBEDTLS_SSL_PROC_CHK_NEG( ssl_tls13_certificate_request_coordinate( ssl ) );
if( ret == SSL_CERTIFICATE_REQUEST_SEND_REQUEST )
{
unsigned char *buf;
size_t buf_len, msg_len;
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_start_handshake_msg( ssl,
MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, &buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_certificate_request_body(
ssl, buf, buf + buf_len, &msg_len ) );
mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, buf, msg_len );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg(
ssl, buf_len, msg_len ) );
}
else if( ret == SSL_CERTIFICATE_REQUEST_SKIP )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate request" ) );
ret = 0;
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
goto cleanup;
}
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_CERTIFICATE );
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write certificate request" ) );
return( ret );
}
/*
* Handler for MBEDTLS_SSL_SERVER_CERTIFICATE
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_server_certificate( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
#if defined(MBEDTLS_X509_CRT_PARSE_C)
if( ( ssl_tls13_pick_key_cert( ssl ) != 0 ) ||
mbedtls_ssl_own_cert( ssl ) == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "No certificate available." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE);
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
#endif /* MBEDTLS_X509_CRT_PARSE_C */
ret = mbedtls_ssl_tls13_write_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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_certificate_verify( mbedtls_ssl_context *ssl )
{
int ret = mbedtls_ssl_tls13_write_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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_server_finished( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
ret = mbedtls_ssl_tls13_write_finished_message( ssl );
if( ret != 0 )
return( ret );
ret = mbedtls_ssl_tls13_compute_application_transform( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( ret );
}
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Switch to handshake keys for inbound traffic" ) );
mbedtls_ssl_set_inbound_transform( ssl, ssl->handshake->transform_handshake );
if( ssl->handshake->certificate_request_sent )
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE );
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "skip parse certificate" ) );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "skip parse certificate verify" ) );
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_FINISHED );
}
return( 0 );
}
/*
* Handler for MBEDTLS_SSL_CLIENT_FINISHED
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_process_client_finished( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
ret = mbedtls_ssl_tls13_process_finished_message( ssl );
if( ret != 0 )
return( ret );
ret = mbedtls_ssl_tls13_compute_resumption_master_secret( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"mbedtls_ssl_tls13_compute_resumption_master_secret", ret );
}
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HANDSHAKE_WRAPUP );
return( 0 );
}
/*
* Handler for MBEDTLS_SSL_HANDSHAKE_WRAPUP
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_handshake_wrapup( mbedtls_ssl_context *ssl )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "handshake: done" ) );
mbedtls_ssl_tls13_handshake_wrapup( ssl );
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_NEW_SESSION_TICKET );
#else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HANDSHAKE_OVER );
#endif
return( 0 );
}
/*
* Handler for MBEDTLS_SSL_NEW_SESSION_TICKET
*/
#define SSL_NEW_SESSION_TICKET_SKIP 0
#define SSL_NEW_SESSION_TICKET_WRITE 1
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_new_session_ticket_coordinate( mbedtls_ssl_context *ssl )
{
/* Check whether the use of session tickets is enabled */
if( ssl->conf->f_ticket_write == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "NewSessionTicket: disabled,"
" callback is not set" ) );
return( SSL_NEW_SESSION_TICKET_SKIP );
}
if( ssl->conf->new_session_tickets_count == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "NewSessionTicket: disabled,"
" configured count is zero" ) );
return( SSL_NEW_SESSION_TICKET_SKIP );
}
if( ssl->handshake->new_session_tickets_count == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "NewSessionTicket: all tickets have "
"been sent." ) );
return( SSL_NEW_SESSION_TICKET_SKIP );
}
return( SSL_NEW_SESSION_TICKET_WRITE );
}
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_prepare_new_session_ticket( mbedtls_ssl_context *ssl,
unsigned char *ticket_nonce,
size_t ticket_nonce_size )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ssl_session *session = ssl->session;
mbedtls_ssl_ciphersuite_t *ciphersuite_info;
psa_algorithm_t psa_hash_alg;
int hash_length;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> prepare NewSessionTicket msg" ) );
#if defined(MBEDTLS_HAVE_TIME)
session->start = mbedtls_time( NULL );
#endif
/* Generate ticket_age_add */
if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng,
(unsigned char *) &session->ticket_age_add,
sizeof( session->ticket_age_add ) ) != 0 ) )
{
MBEDTLS_SSL_DEBUG_RET( 1, "generate_ticket_age_add", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket_age_add: %u",
(unsigned int)session->ticket_age_add ) );
/* Generate ticket_nonce */
ret = ssl->conf->f_rng( ssl->conf->p_rng, ticket_nonce, ticket_nonce_size );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "generate_ticket_nonce", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "ticket_nonce:",
ticket_nonce, ticket_nonce_size );
ciphersuite_info =
(mbedtls_ssl_ciphersuite_t *) ssl->handshake->ciphersuite_info;
psa_hash_alg = mbedtls_psa_translate_md( ciphersuite_info->mac );
hash_length = PSA_HASH_LENGTH( psa_hash_alg );
if( hash_length == -1 ||
(size_t)hash_length > sizeof( session->resumption_key ) )
{
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/* In this code the psk key length equals the length of the hash */
session->resumption_key_len = hash_length;
session->ciphersuite = ciphersuite_info->id;
/* Compute resumption key
*
* HKDF-Expand-Label( resumption_master_secret,
* "resumption", ticket_nonce, Hash.length )
*/
ret = mbedtls_ssl_tls13_hkdf_expand_label(
psa_hash_alg,
session->app_secrets.resumption_master_secret,
hash_length,
MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( resumption ),
ticket_nonce,
ticket_nonce_size,
session->resumption_key,
hash_length );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 2,
"Creating the ticket-resumed PSK failed",
ret );
return ( ret );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "Ticket-resumed PSK",
session->resumption_key,
session->resumption_key_len );
MBEDTLS_SSL_DEBUG_BUF( 3, "resumption_master_secret",
session->app_secrets.resumption_master_secret,
hash_length );
return( 0 );
}
/* This function creates a NewSessionTicket message in the following format:
*
* struct {
* uint32 ticket_lifetime;
* uint32 ticket_age_add;
* opaque ticket_nonce<0..255>;
* opaque ticket<1..2^16-1>;
* Extension extensions<0..2^16-2>;
* } NewSessionTicket;
*
* The ticket inside the NewSessionTicket message is an encrypted container
* carrying the necessary information so that the server is later able to
* re-start the communication.
*
* The following fields are placed inside the ticket by the
* f_ticket_write() function:
*
* - creation time (start)
* - flags (flags)
* - age add (ticket_age_add)
* - key (key)
* - key length (key_len)
* - ciphersuite (ciphersuite)
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_new_session_ticket_body( mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len,
unsigned char *ticket_nonce,
size_t ticket_nonce_size )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
mbedtls_ssl_session *session = ssl->session;
size_t ticket_len;
uint32_t ticket_lifetime;
*out_len = 0;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write NewSessionTicket msg" ) );
/*
* ticket_lifetime 4 bytes
* ticket_age_add 4 bytes
* ticket_nonce 1 + ticket_nonce_size bytes
* ticket >=2 bytes
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 + 4 + 1 + ticket_nonce_size + 2 );
/* Generate ticket and ticket_lifetime */
ret = ssl->conf->f_ticket_write( ssl->conf->p_ticket,
session,
p + 9 + ticket_nonce_size + 2,
end,
&ticket_len,
&ticket_lifetime);
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "write_ticket", ret );
return( ret );
}
/* RFC 8446 4.6.1
* ticket_lifetime: Indicates the lifetime in seconds as a 32-bit
* unsigned integer in network byte order from the time of ticket
* issuance. Servers MUST NOT use any value greater than
* 604800 seconds (7 days). The value of zero indicates that the
* ticket should be discarded immediately. Clients MUST NOT cache
* tickets for longer than 7 days, regardless of the ticket_lifetime,
* and MAY delete tickets earlier based on local policy. A server
* MAY treat a ticket as valid for a shorter period of time than what
* is stated in the ticket_lifetime.
*/
ticket_lifetime %= 604800;
MBEDTLS_PUT_UINT32_BE( ticket_lifetime, p, 0 );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket_lifetime: %u",
( unsigned int )ticket_lifetime ) );
/* Write ticket_age_add */
MBEDTLS_PUT_UINT32_BE( session->ticket_age_add, p, 4 );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket_age_add: %u",
( unsigned int )session->ticket_age_add ) );
/* Write ticket_nonce */
p[8] = ( unsigned char )ticket_nonce_size;
if( ticket_nonce_size > 0 )
{
memcpy( p + 9, ticket_nonce, ticket_nonce_size );
}
p += 9 + ticket_nonce_size;
/* Write ticket */
MBEDTLS_PUT_UINT16_BE( ticket_len, p, 0 );
p += 2;
MBEDTLS_SSL_DEBUG_BUF( 4, "ticket", p, ticket_len);
p += ticket_len;
/* Ticket Extensions
*
* Note: We currently don't have any extensions.
* Set length to zero.
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
MBEDTLS_PUT_UINT16_BE( 0, p, 0 );
p += 2;
*out_len = p - buf;
MBEDTLS_SSL_DEBUG_BUF( 4, "ticket", buf, *out_len );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write new session ticket" ) );
return( 0 );
}
/*
* Handler for MBEDTLS_SSL_NEW_SESSION_TICKET
*/
static int ssl_tls13_write_new_session_ticket( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_PROC_CHK_NEG( ssl_tls13_write_new_session_ticket_coordinate( ssl ) );
if( ret == SSL_NEW_SESSION_TICKET_WRITE )
{
unsigned char ticket_nonce[MBEDTLS_SSL_TLS1_3_TICKET_NONCE_LENGTH];
unsigned char *buf;
size_t buf_len, msg_len;
MBEDTLS_SSL_PROC_CHK( ssl_tls13_prepare_new_session_ticket(
ssl, ticket_nonce, sizeof( ticket_nonce ) ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_start_handshake_msg( ssl,
MBEDTLS_SSL_HS_NEW_SESSION_TICKET, &buf, &buf_len ) );
MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_new_session_ticket_body(
ssl, buf, buf + buf_len, &msg_len,
ticket_nonce, sizeof( ticket_nonce ) ) );
MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg(
ssl, buf_len, msg_len ) );
/* Limit session tickets count to one when resumption connection.
*
* See document of mbedtls_ssl_conf_new_session_tickets.
*/
if( ssl->handshake->resume == 1 )
ssl->handshake->new_session_tickets_count = 0;
else
ssl->handshake->new_session_tickets_count--;
mbedtls_ssl_handshake_set_state( ssl,
MBEDTLS_SSL_NEW_SESSION_TICKET_FLUSH );
}
else
{
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HANDSHAKE_OVER );
}
cleanup:
return( ret );
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
/*
* TLS 1.3 State Machine -- server side
*/
int mbedtls_ssl_tls13_handshake_server_step( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "tls13 server state: %s(%d)",
mbedtls_ssl_states_str( ssl->state ),
ssl->state ) );
switch( ssl->state )
{
/* start state */
case MBEDTLS_SSL_HELLO_REQUEST:
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_HELLO );
ret = 0;
break;
case MBEDTLS_SSL_CLIENT_HELLO:
ret = ssl_tls13_process_client_hello( ssl );
if( ret != 0 )
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_process_client_hello", ret );
break;
case MBEDTLS_SSL_HELLO_RETRY_REQUEST:
ret = ssl_tls13_write_hello_retry_request( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_hello_retry_request", ret );
return( ret );
}
break;
case MBEDTLS_SSL_SERVER_HELLO:
ret = ssl_tls13_write_server_hello( ssl );
break;
case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS:
ret = ssl_tls13_write_encrypted_extensions( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_encrypted_extensions", ret );
return( ret );
}
break;
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
case MBEDTLS_SSL_CERTIFICATE_REQUEST:
ret = ssl_tls13_write_certificate_request( ssl );
break;
case MBEDTLS_SSL_SERVER_CERTIFICATE:
ret = ssl_tls13_write_server_certificate( ssl );
break;
case MBEDTLS_SSL_CERTIFICATE_VERIFY:
ret = ssl_tls13_write_certificate_verify( ssl );
break;
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
/*
* Injection of dummy-CCS's for middlebox compatibility
*/
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
case MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST:
ret = mbedtls_ssl_tls13_write_change_cipher_spec( ssl );
if( ret == 0 )
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CLIENT_HELLO );
break;
case MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO:
ret = mbedtls_ssl_tls13_write_change_cipher_spec( ssl );
if( ret == 0 )
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS );
break;
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
case MBEDTLS_SSL_SERVER_FINISHED:
ret = ssl_tls13_write_server_finished( ssl );
break;
case MBEDTLS_SSL_CLIENT_FINISHED:
ret = ssl_tls13_process_client_finished( ssl );
break;
case MBEDTLS_SSL_HANDSHAKE_WRAPUP:
ret = ssl_tls13_handshake_wrapup( ssl );
break;
case MBEDTLS_SSL_CLIENT_CERTIFICATE:
ret = mbedtls_ssl_tls13_process_certificate( ssl );
if( ret == 0 )
{
if( ssl->session_negotiate->peer_cert != NULL )
{
mbedtls_ssl_handshake_set_state(
ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY );
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "skip parse certificate verify" ) );
mbedtls_ssl_handshake_set_state(
ssl, MBEDTLS_SSL_CLIENT_FINISHED );
}
}
break;
case MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY:
ret = mbedtls_ssl_tls13_process_certificate_verify( ssl );
if( ret == 0 )
{
mbedtls_ssl_handshake_set_state(
ssl, MBEDTLS_SSL_CLIENT_FINISHED );
}
break;
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
case MBEDTLS_SSL_NEW_SESSION_TICKET:
ret = ssl_tls13_write_new_session_ticket( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1,
"ssl_tls13_write_new_session_ticket ",
ret );
}
break;
case MBEDTLS_SSL_NEW_SESSION_TICKET_FLUSH:
/* This state is necessary to do the flush of the New Session
* Ticket message written in MBEDTLS_SSL_NEW_SESSION_TICKET
* as part of ssl_prepare_handshake_step.
*/
ret = 0;
if( ssl->handshake->new_session_tickets_count == 0 )
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_HANDSHAKE_OVER );
else
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_NEW_SESSION_TICKET );
break;
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
default:
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) );
return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
}
return( ret );
}
#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_TLS1_3 */
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