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review.trustedfirmware.org / mirror / mbed-tls.git / ff9fcbcacee78564a946d85480533a2ffe443b0e / . / library / ssl_tls13_client.c
blob: 35679ca74fec7ff2001e8f0e8a7e7d6c58f86c04 [file] [log] [blame]
/*
* 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_CLI_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3)
#include <string.h>
#include "mbedtls/debug.h"
#include "mbedtls/error.h"
#include "mbedtls/platform.h"
#include "ssl_misc.h"
#include "ssl_client.h"
#include "ssl_tls13_keys.h"
#include "ssl_debug_helpers.h"
#define PSA_TO_MBEDTLS_ERR(status) PSA_TO_MBEDTLS_ERR_LIST(status, \
psa_to_ssl_errors, \
psa_generic_status_to_mbedtls)
/* Write extensions */
/*
* ssl_tls13_write_supported_versions_ext():
*
* struct {
* ProtocolVersion versions<2..254>;
* } SupportedVersions;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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;
unsigned char versions_len = (ssl->handshake->min_tls_version <=
MBEDTLS_SSL_VERSION_TLS1_2) ? 4 : 2;
*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 or 4 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR(p, end, 5 + versions_len);
MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, p, 0);
MBEDTLS_PUT_UINT16_BE(versions_len + 1, p, 2);
p += 4;
/* Length of versions */
*p++ = versions_len;
/* Write values of supported versions.
* They are defined by the configuration.
* Currently, we advertise only TLS 1.3 or both TLS 1.3 and TLS 1.2.
*/
mbedtls_ssl_write_version(p, MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_VERSION_TLS1_3);
MBEDTLS_SSL_DEBUG_MSG(3, ("supported version: [3:4]"));
if (ssl->handshake->min_tls_version <= MBEDTLS_SSL_VERSION_TLS1_2) {
mbedtls_ssl_write_version(p + 2, MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_VERSION_TLS1_2);
MBEDTLS_SSL_DEBUG_MSG(3, ("supported version: [3:3]"));
}
*out_len = 5 + versions_len;
mbedtls_ssl_tls13_set_hs_sent_ext_mask(
ssl, MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS);
return 0;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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 (mbedtls_ssl_read_version(buf, ssl->conf->transport) !=
MBEDTLS_SSL_VERSION_TLS1_3) {
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;
}
if (&buf[2] != end) {
MBEDTLS_SSL_DEBUG_MSG(
1, ("supported_versions ext data length incorrect"));
MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
MBEDTLS_ERR_SSL_DECODE_ERROR);
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
return 0;
}
#if defined(MBEDTLS_SSL_ALPN)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_alpn_ext(mbedtls_ssl_context *ssl,
const unsigned char *buf, size_t len)
{
const unsigned char *p = buf;
const unsigned char *end = buf + len;
size_t protocol_name_list_len, protocol_name_len;
const unsigned char *protocol_name_list_end;
/* If we didn't send it, the server shouldn't send it */
if (ssl->conf->alpn_list == NULL) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
/*
* opaque ProtocolName<1..2^8-1>;
*
* struct {
* ProtocolName protocol_name_list<2..2^16-1>
* } ProtocolNameList;
*
* the "ProtocolNameList" MUST contain exactly one "ProtocolName"
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2);
protocol_name_list_len = MBEDTLS_GET_UINT16_BE(p, 0);
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, protocol_name_list_len);
protocol_name_list_end = p + protocol_name_list_len;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, protocol_name_list_end, 1);
protocol_name_len = *p++;
/* Check that the server chosen protocol was in our list and save it */
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, protocol_name_list_end, protocol_name_len);
for (const char **alpn = ssl->conf->alpn_list; *alpn != NULL; alpn++) {
if (protocol_name_len == strlen(*alpn) &&
memcmp(p, *alpn, protocol_name_len) == 0) {
ssl->alpn_chosen = *alpn;
return 0;
}
}
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
#endif /* MBEDTLS_SSL_ALPN */
MBEDTLS_CHECK_RETURN_CRITICAL
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(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH)
if (mbedtls_ssl_tls13_named_group_is_ecdhe(group_id) ||
mbedtls_ssl_tls13_named_group_is_dhe(group_id)) {
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
/* Destroy generated private key. */
status = psa_destroy_key(ssl->handshake->ecdh_psa_privkey);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
MBEDTLS_SSL_DEBUG_RET(1, "psa_destroy_key", ret);
return ret;
}
ssl->handshake->ecdh_psa_privkey = MBEDTLS_SVC_KEY_ID_INIT;
return 0;
} else
#endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */
if (0 /* other KEMs? */) {
/* Do something */
}
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
/*
* Functions for writing key_share extension.
*/
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED)
MBEDTLS_CHECK_RETURN_CRITICAL
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(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH)
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;
}
#if defined(PSA_WANT_ALG_FFDH)
if (mbedtls_ssl_tls13_named_group_is_dhe(*group_list)) {
*group_id = *group_list;
return 0;
}
#endif /* PSA_WANT_ALG_FFDH */
#if defined(PSA_WANT_ALG_ECDH)
for (; *group_list != 0; group_list++) {
if ((mbedtls_ssl_get_psa_curve_info_from_tls_id(
*group_list, NULL, NULL) == PSA_SUCCESS) &&
mbedtls_ssl_tls13_named_group_is_ecdhe(*group_list)) {
*group_id = *group_list;
return 0;
}
}
#endif /* PSA_WANT_ALG_ECDH */
#else
((void) ssl);
((void) group_id);
#endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */
/*
* 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;
*/
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)
{
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(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH)
if (mbedtls_ssl_tls13_named_group_is_ecdhe(group_id) ||
mbedtls_ssl_tls13_named_group_is_dhe(group_id)) {
/* Pointer to group */
unsigned char *group = p;
/* Length of key_exchange */
size_t key_exchange_len = 0;
/* 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 = mbedtls_ssl_tls13_generate_and_write_dh_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 /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */
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);
mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE);
cleanup:
return ret;
}
#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */
/*
* ssl_tls13_parse_hrr_key_share_ext()
* Parse key_share extension in Hello Retry Request
*
* struct {
* NamedGroup selected_group;
* } KeyShareHelloRetryRequest;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_hrr_key_share_ext(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
#if defined(PSA_WANT_ALG_ECDH)
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++) {
if (mbedtls_ssl_tls13_named_group_is_ecdhe(*group_list)) {
if ((mbedtls_ssl_get_psa_curve_info_from_tls_id(
*group_list, NULL, NULL) == PSA_ERROR_NOT_SUPPORTED) ||
*group_list != selected_group) {
found = 1;
break;
}
}
if (mbedtls_ssl_tls13_named_group_is_dhe(*group_list)) {
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;
#else
(void) ssl;
(void) buf;
(void) end;
return MBEDTLS_ERR_SSL_BAD_CONFIG;
#endif
}
/*
* 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;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH)
if (mbedtls_ssl_tls13_named_group_is_ecdhe(group) ||
mbedtls_ssl_tls13_named_group_is_dhe(group)) {
#if defined(PSA_WANT_ALG_ECDH)
if (mbedtls_ssl_tls13_named_group_is_ecdhe(group)) {
if (mbedtls_ssl_get_psa_curve_info_from_tls_id(group, NULL, NULL)
== PSA_ERROR_NOT_SUPPORTED) {
MBEDTLS_SSL_DEBUG_MSG(1, ("Invalid TLS curve group id"));
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
MBEDTLS_SSL_DEBUG_MSG(
2,
("ECDH curve: %s", mbedtls_ssl_get_curve_name_from_tls_id(group)));
}
#endif /* PSA_WANT_ALG_ECDH */
#if defined(PSA_WANT_ALG_FFDH)
if (mbedtls_ssl_tls13_named_group_is_dhe(group)) {
MBEDTLS_SSL_DEBUG_MSG(2,
("DHE group name: %s", mbedtls_ssl_ffdh_name_from_group(group)));
}
#endif /* PSA_WANT_ALG_FFDH */
ret = mbedtls_ssl_tls13_read_public_ecdhe_share(ssl, p, end - p);
if (ret != 0) {
return ret;
}
} else
#endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */
if (0 /* other KEMs? */) {
/* Do something */
} else {
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
return ret;
}
/*
* 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.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_cookie_ext(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
uint16_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->cookie);
handshake->cookie_len = 0;
handshake->cookie = mbedtls_calloc(1, cookie_len);
if (handshake->cookie == NULL) {
MBEDTLS_SSL_DEBUG_MSG(1,
("alloc failed ( %ud bytes )",
cookie_len));
return MBEDTLS_ERR_SSL_ALLOC_FAILED;
}
memcpy(handshake->cookie, p, cookie_len);
handshake->cookie_len = cookie_len;
return 0;
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_cookie_ext(mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len)
{
unsigned char *p = buf;
*out_len = 0;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
if (handshake->cookie == NULL) {
MBEDTLS_SSL_DEBUG_MSG(3, ("no cookie to send; skip extension"));
return 0;
}
MBEDTLS_SSL_DEBUG_BUF(3, "client hello, cookie",
handshake->cookie,
handshake->cookie_len);
MBEDTLS_SSL_CHK_BUF_PTR(p, end, handshake->cookie_len + 6);
MBEDTLS_SSL_DEBUG_MSG(3, ("client hello, adding cookie extension"));
MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_COOKIE, p, 0);
MBEDTLS_PUT_UINT16_BE(handshake->cookie_len + 2, p, 2);
MBEDTLS_PUT_UINT16_BE(handshake->cookie_len, p, 4);
p += 6;
/* Cookie */
memcpy(p, handshake->cookie, handshake->cookie_len);
*out_len = handshake->cookie_len + 6;
mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_COOKIE);
return 0;
}
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED)
/*
* ssl_tls13_write_psk_key_exchange_modes_ext() structure:
*
* 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_write_psk_key_exchange_modes_ext(mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
size_t *out_len)
{
unsigned char *p = buf;
int ke_modes_len = 0;
((void) ke_modes_len);
*out_len = 0;
/* Skip writing extension if no PSK key exchange mode
* is enabled in the config.
*/
if (!mbedtls_ssl_conf_tls13_some_psk_enabled(ssl)) {
MBEDTLS_SSL_DEBUG_MSG(3, ("skip psk_key_exchange_modes extension"));
return 0;
}
/* Require 7 bytes of data, otherwise fail,
* even if extension might be shorter.
*/
MBEDTLS_SSL_CHK_BUF_PTR(p, end, 7);
MBEDTLS_SSL_DEBUG_MSG(
3, ("client hello, adding psk_key_exchange_modes extension"));
MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES, p, 0);
/* Skip extension length (2 bytes) and
* ke_modes length (1 byte) for now.
*/
p += 5;
if (mbedtls_ssl_conf_tls13_psk_ephemeral_enabled(ssl)) {
*p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE;
ke_modes_len++;
MBEDTLS_SSL_DEBUG_MSG(4, ("Adding PSK-ECDHE key exchange mode"));
}
if (mbedtls_ssl_conf_tls13_psk_enabled(ssl)) {
*p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE;
ke_modes_len++;
MBEDTLS_SSL_DEBUG_MSG(4, ("Adding pure PSK key exchange mode"));
}
/* Now write the extension and ke_modes length */
MBEDTLS_PUT_UINT16_BE(ke_modes_len + 1, buf, 2);
buf[4] = ke_modes_len;
*out_len = p - buf;
mbedtls_ssl_tls13_set_hs_sent_ext_mask(
ssl, MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES);
return 0;
}
static psa_algorithm_t ssl_tls13_get_ciphersuite_hash_alg(int ciphersuite)
{
const mbedtls_ssl_ciphersuite_t *ciphersuite_info = NULL;
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(ciphersuite);
if (ciphersuite_info != NULL) {
return mbedtls_psa_translate_md(ciphersuite_info->mac);
}
return PSA_ALG_NONE;
}
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
static int ssl_tls13_has_configured_ticket(mbedtls_ssl_context *ssl)
{
mbedtls_ssl_session *session = ssl->session_negotiate;
return ssl->handshake->resume &&
session != NULL && session->ticket != NULL &&
mbedtls_ssl_conf_tls13_check_kex_modes(
ssl, mbedtls_ssl_session_get_ticket_flags(
session, MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL));
}
#if defined(MBEDTLS_SSL_EARLY_DATA)
static int ssl_tls13_early_data_has_valid_ticket(mbedtls_ssl_context *ssl)
{
mbedtls_ssl_session *session = ssl->session_negotiate;
return ssl->handshake->resume &&
session->tls_version == MBEDTLS_SSL_VERSION_TLS1_3 &&
(session->ticket_flags &
MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA) &&
mbedtls_ssl_tls13_cipher_suite_is_offered(
ssl, session->ciphersuite);
}
#endif
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_ticket_get_identity(mbedtls_ssl_context *ssl,
psa_algorithm_t *hash_alg,
const unsigned char **identity,
size_t *identity_len)
{
mbedtls_ssl_session *session = ssl->session_negotiate;
if (!ssl_tls13_has_configured_ticket(ssl)) {
return -1;
}
*hash_alg = ssl_tls13_get_ciphersuite_hash_alg(session->ciphersuite);
*identity = session->ticket;
*identity_len = session->ticket_len;
return 0;
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_ticket_get_psk(mbedtls_ssl_context *ssl,
psa_algorithm_t *hash_alg,
const unsigned char **psk,
size_t *psk_len)
{
mbedtls_ssl_session *session = ssl->session_negotiate;
if (!ssl_tls13_has_configured_ticket(ssl)) {
return -1;
}
*hash_alg = ssl_tls13_get_ciphersuite_hash_alg(session->ciphersuite);
*psk = session->resumption_key;
*psk_len = session->resumption_key_len;
return 0;
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_psk_get_identity(mbedtls_ssl_context *ssl,
psa_algorithm_t *hash_alg,
const unsigned char **identity,
size_t *identity_len)
{
if (!mbedtls_ssl_conf_has_static_psk(ssl->conf)) {
return -1;
}
*hash_alg = PSA_ALG_SHA_256;
*identity = ssl->conf->psk_identity;
*identity_len = ssl->conf->psk_identity_len;
return 0;
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_psk_get_psk(mbedtls_ssl_context *ssl,
psa_algorithm_t *hash_alg,
const unsigned char **psk,
size_t *psk_len)
{
if (!mbedtls_ssl_conf_has_static_psk(ssl->conf)) {
return -1;
}
*hash_alg = PSA_ALG_SHA_256;
*psk = ssl->conf->psk;
*psk_len = ssl->conf->psk_len;
return 0;
}
static int ssl_tls13_get_configured_psk_count(mbedtls_ssl_context *ssl)
{
int configured_psk_count = 0;
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
if (ssl_tls13_has_configured_ticket(ssl)) {
MBEDTLS_SSL_DEBUG_MSG(3, ("Ticket is configured"));
configured_psk_count++;
}
#endif
if (mbedtls_ssl_conf_has_static_psk(ssl->conf)) {
MBEDTLS_SSL_DEBUG_MSG(3, ("PSK is configured"));
configured_psk_count++;
}
return configured_psk_count;
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_identity(mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
const unsigned char *identity,
size_t identity_len,
uint32_t obfuscated_ticket_age,
size_t *out_len)
{
((void) ssl);
*out_len = 0;
/*
* - identity_len (2 bytes)
* - identity (psk_identity_len bytes)
* - obfuscated_ticket_age (4 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6 + identity_len);
MBEDTLS_PUT_UINT16_BE(identity_len, buf, 0);
memcpy(buf + 2, identity, identity_len);
MBEDTLS_PUT_UINT32_BE(obfuscated_ticket_age, buf, 2 + identity_len);
MBEDTLS_SSL_DEBUG_BUF(4, "write identity", buf, 6 + identity_len);
*out_len = 6 + identity_len;
return 0;
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_binder(mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
int psk_type,
psa_algorithm_t hash_alg,
const unsigned char *psk,
size_t psk_len,
size_t *out_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char binder_len;
unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE];
size_t transcript_len = 0;
*out_len = 0;
binder_len = PSA_HASH_LENGTH(hash_alg);
/*
* - binder_len (1 bytes)
* - binder (binder_len bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 1 + binder_len);
buf[0] = binder_len;
/* Get current state of handshake transcript. */
ret = mbedtls_ssl_get_handshake_transcript(
ssl, mbedtls_hash_info_md_from_psa(hash_alg),
transcript, sizeof(transcript), &transcript_len);
if (ret != 0) {
return ret;
}
ret = mbedtls_ssl_tls13_create_psk_binder(ssl, hash_alg,
psk, psk_len, psk_type,
transcript, buf + 1);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_tls13_create_psk_binder", ret);
return ret;
}
MBEDTLS_SSL_DEBUG_BUF(4, "write binder", buf, 1 + binder_len);
*out_len = 1 + binder_len;
return 0;
}
/*
* mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext() structure:
*
* 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;
*
*/
int mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext(
mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end,
size_t *out_len, size_t *binders_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
int configured_psk_count = 0;
unsigned char *p = buf;
psa_algorithm_t hash_alg = PSA_ALG_NONE;
const unsigned char *identity;
size_t identity_len;
size_t l_binders_len = 0;
size_t output_len;
*out_len = 0;
*binders_len = 0;
/* Check if we have any PSKs to offer. If no, skip pre_shared_key */
configured_psk_count = ssl_tls13_get_configured_psk_count(ssl);
if (configured_psk_count == 0) {
MBEDTLS_SSL_DEBUG_MSG(3, ("skip pre_shared_key extensions"));
return 0;
}
MBEDTLS_SSL_DEBUG_MSG(4, ("Pre-configured PSK number = %d",
configured_psk_count));
/* Check if we have space to write the extension, binders included.
* - extension_type (2 bytes)
* - extension_data_len (2 bytes)
* - identities_len (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR(p, end, 6);
p += 6;
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
if (ssl_tls13_ticket_get_identity(
ssl, &hash_alg, &identity, &identity_len) == 0) {
#if defined(MBEDTLS_HAVE_TIME)
mbedtls_time_t now = mbedtls_time(NULL);
mbedtls_ssl_session *session = ssl->session_negotiate;
uint32_t obfuscated_ticket_age =
(uint32_t) (now - session->ticket_received);
/*
* The ticket timestamp is in seconds but the ticket age is in
* milliseconds. If the ticket was received at the end of a second and
* re-used here just at the beginning of the next second, the computed
* age `now - session->ticket_received` is equal to 1s thus 1000 ms
* while the actual age could be just a few milliseconds or tens of
* milliseconds. If the server has more accurate ticket timestamps
* (typically timestamps in milliseconds), as part of the processing of
* the ClientHello, it may compute a ticket lifetime smaller than the
* one computed here and potentially reject the ticket. To avoid that,
* remove one second to the ticket age if possible.
*/
if (obfuscated_ticket_age > 0) {
obfuscated_ticket_age -= 1;
}
obfuscated_ticket_age *= 1000;
obfuscated_ticket_age += session->ticket_age_add;
ret = ssl_tls13_write_identity(ssl, p, end,
identity, identity_len,
obfuscated_ticket_age,
&output_len);
#else
ret = ssl_tls13_write_identity(ssl, p, end, identity, identity_len,
0, &output_len);
#endif /* MBEDTLS_HAVE_TIME */
if (ret != 0) {
return ret;
}
p += output_len;
l_binders_len += 1 + PSA_HASH_LENGTH(hash_alg);
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
if (ssl_tls13_psk_get_identity(
ssl, &hash_alg, &identity, &identity_len) == 0) {
ret = ssl_tls13_write_identity(ssl, p, end, identity, identity_len, 0,
&output_len);
if (ret != 0) {
return ret;
}
p += output_len;
l_binders_len += 1 + PSA_HASH_LENGTH(hash_alg);
}
MBEDTLS_SSL_DEBUG_MSG(3,
("client hello, adding pre_shared_key extension, "
"omitting PSK binder list"));
/* Take into account the two bytes for the length of the binders. */
l_binders_len += 2;
/* Check if there is enough space for binders */
MBEDTLS_SSL_CHK_BUF_PTR(p, end, l_binders_len);
/*
* - extension_type (2 bytes)
* - extension_data_len (2 bytes)
* - identities_len (2 bytes)
*/
MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_PRE_SHARED_KEY, buf, 0);
MBEDTLS_PUT_UINT16_BE(p - buf - 4 + l_binders_len, buf, 2);
MBEDTLS_PUT_UINT16_BE(p - buf - 6, buf, 4);
*out_len = (p - buf) + l_binders_len;
*binders_len = l_binders_len;
MBEDTLS_SSL_DEBUG_BUF(3, "pre_shared_key identities", buf, p - buf);
return 0;
}
int mbedtls_ssl_tls13_write_binders_of_pre_shared_key_ext(
mbedtls_ssl_context *ssl, unsigned char *buf, unsigned char *end)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
psa_algorithm_t hash_alg = PSA_ALG_NONE;
const unsigned char *psk;
size_t psk_len;
size_t output_len;
/* Check if we have space to write binders_len.
* - binders_len (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2);
p += 2;
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
if (ssl_tls13_ticket_get_psk(ssl, &hash_alg, &psk, &psk_len) == 0) {
ret = ssl_tls13_write_binder(ssl, p, end,
MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION,
hash_alg, psk, psk_len,
&output_len);
if (ret != 0) {
return ret;
}
p += output_len;
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
if (ssl_tls13_psk_get_psk(ssl, &hash_alg, &psk, &psk_len) == 0) {
ret = ssl_tls13_write_binder(ssl, p, end,
MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL,
hash_alg, psk, psk_len,
&output_len);
if (ret != 0) {
return ret;
}
p += output_len;
}
MBEDTLS_SSL_DEBUG_MSG(3, ("client hello, adding PSK binder list."));
/*
* - binders_len (2 bytes)
*/
MBEDTLS_PUT_UINT16_BE(p - buf - 2, buf, 0);
MBEDTLS_SSL_DEBUG_BUF(3, "pre_shared_key binders", buf, p - buf);
mbedtls_ssl_tls13_set_hs_sent_ext_mask(
ssl, MBEDTLS_TLS_EXT_PRE_SHARED_KEY);
return 0;
}
/*
* struct {
* opaque identity<1..2^16-1>;
* uint32 obfuscated_ticket_age;
* } PskIdentity;
*
* opaque PskBinderEntry<32..255>;
*
* struct {
*
* select (Handshake.msg_type) {
* ...
* case server_hello: uint16 selected_identity;
* };
*
* } PreSharedKeyExtension;
*
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_server_pre_shared_key_ext(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
int selected_identity;
const unsigned char *psk;
size_t psk_len;
psa_algorithm_t hash_alg;
MBEDTLS_SSL_CHK_BUF_READ_PTR(buf, end, 2);
selected_identity = MBEDTLS_GET_UINT16_BE(buf, 0);
ssl->handshake->selected_identity = (uint16_t) selected_identity;
MBEDTLS_SSL_DEBUG_MSG(3, ("selected_identity = %d", selected_identity));
if (selected_identity >= ssl_tls13_get_configured_psk_count(ssl)) {
MBEDTLS_SSL_DEBUG_MSG(1, ("Invalid PSK identity."));
MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
if (selected_identity == 0 && ssl_tls13_has_configured_ticket(ssl)) {
ret = ssl_tls13_ticket_get_psk(ssl, &hash_alg, &psk, &psk_len);
} else
#endif
if (mbedtls_ssl_conf_has_static_psk(ssl->conf)) {
ret = ssl_tls13_psk_get_psk(ssl, &hash_alg, &psk, &psk_len);
} else {
MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
if (ret != 0) {
return ret;
}
if (mbedtls_psa_translate_md(ssl->handshake->ciphersuite_info->mac)
!= hash_alg) {
MBEDTLS_SSL_DEBUG_MSG(
1, ("Invalid ciphersuite for external psk."));
MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
ret = mbedtls_ssl_set_hs_psk(ssl, psk, psk_len);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret);
return ret;
}
return 0;
}
#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */
int mbedtls_ssl_tls13_write_client_hello_exts(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 ext_len;
*out_len = 0;
/* Write supported_versions extension
*
* Supported Versions Extension is mandatory with TLS 1.3.
*/
ret = ssl_tls13_write_supported_versions_ext(ssl, p, end, &ext_len);
if (ret != 0) {
return ret;
}
p += ext_len;
/* Echo the cookie if the server provided one in its preceding
* HelloRetryRequest message.
*/
ret = ssl_tls13_write_cookie_ext(ssl, p, end, &ext_len);
if (ret != 0) {
return ret;
}
p += ext_len;
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED)
if (mbedtls_ssl_conf_tls13_some_ephemeral_enabled(ssl)) {
ret = ssl_tls13_write_key_share_ext(ssl, p, end, &ext_len);
if (ret != 0) {
return ret;
}
p += ext_len;
}
#endif
#if defined(MBEDTLS_SSL_EARLY_DATA)
if (mbedtls_ssl_conf_tls13_some_psk_enabled(ssl) &&
ssl_tls13_early_data_has_valid_ticket(ssl) &&
ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_ENABLED) {
ret = mbedtls_ssl_tls13_write_early_data_ext(ssl, p, end, &ext_len);
if (ret != 0) {
return ret;
}
p += ext_len;
/* Initializes the status to `rejected`. It will be updated to
* `accepted` if the EncryptedExtension message contain an early data
* indication extension.
*/
ssl->early_data_status = MBEDTLS_SSL_EARLY_DATA_STATUS_REJECTED;
} else {
MBEDTLS_SSL_DEBUG_MSG(2, ("<= skip write early_data extension"));
ssl->early_data_status = MBEDTLS_SSL_EARLY_DATA_STATUS_NOT_SENT;
}
#endif /* MBEDTLS_SSL_EARLY_DATA */
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED)
/* For PSK-based key exchange we need the pre_shared_key extension
* and the psk_key_exchange_modes extension.
*
* The pre_shared_key extension MUST be the last extension in the
* ClientHello. Servers MUST check that it is the last extension and
* otherwise fail the handshake with an "illegal_parameter" alert.
*
* Add the psk_key_exchange_modes extension.
*/
ret = ssl_tls13_write_psk_key_exchange_modes_ext(ssl, p, end, &ext_len);
if (ret != 0) {
return ret;
}
p += ext_len;
#endif
*out_len = p - buf;
return 0;
}
int mbedtls_ssl_tls13_finalize_client_hello(mbedtls_ssl_context *ssl)
{
((void) ssl);
#if defined(MBEDTLS_SSL_EARLY_DATA)
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
psa_algorithm_t hash_alg = PSA_ALG_NONE;
const unsigned char *psk;
size_t psk_len;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
if (ssl->early_data_status == MBEDTLS_SSL_EARLY_DATA_STATUS_REJECTED) {
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
mbedtls_ssl_handshake_set_state(
ssl, MBEDTLS_SSL_CLIENT_CCS_AFTER_CLIENT_HELLO);
#endif
MBEDTLS_SSL_DEBUG_MSG(
1, ("Set hs psk for early data when writing the first psk"));
ret = ssl_tls13_ticket_get_psk(ssl, &hash_alg, &psk, &psk_len);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(
1, "ssl_tls13_ticket_get_psk", ret);
return ret;
}
ret = mbedtls_ssl_set_hs_psk(ssl, psk, psk_len);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret);
return ret;
}
/*
* Early data are going to be encrypted using the ciphersuite
* associated with the pre-shared key used for the handshake.
* Note that if the server rejects early data, the handshake
* based on the pre-shared key may complete successfully
* with a selected ciphersuite different from the ciphersuite
* associated with the pre-shared key. Only the hashes of the
* two ciphersuites have to be the same. In that case, the
* encrypted handshake data and application data are
* encrypted using a different ciphersuite than the one used for
* the rejected early data.
*/
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(
ssl->session_negotiate->ciphersuite);
ssl->handshake->ciphersuite_info = ciphersuite_info;
/* Enable psk and psk_ephemeral to make stage early happy */
ssl->handshake->key_exchange_mode =
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL;
/* Start the TLS 1.3 key schedule:
* Set the PSK and derive 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", ret);
return ret;
}
/* Derive early data key material */
ret = mbedtls_ssl_tls13_compute_early_transform(ssl);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(
1, "mbedtls_ssl_tls13_compute_early_transform", ret);
return ret;
}
}
#endif /* MBEDTLS_SSL_EARLY_DATA */
return 0;
}
/*
* Functions for parsing and processing Server Hello
*/
/**
* \brief Detect if the ServerHello contains a supported_versions extension
* or not.
*
* \param[in] ssl SSL context
* \param[in] buf Buffer containing the ServerHello message
* \param[in] end End of the buffer containing the ServerHello message
*
* \return 0 if the ServerHello does not contain a supported_versions extension
* \return 1 if the ServerHello contains a supported_versions extension
* \return A negative value if an error occurred while parsing the ServerHello.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_is_supported_versions_ext_present(
mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
const unsigned char *p = buf;
size_t legacy_session_id_echo_len;
const unsigned char *supported_versions_data;
const unsigned char *supported_versions_data_end;
/*
* Check there is enough data to access the legacy_session_id_echo vector
* length:
* - legacy_version 2 bytes
* - random MBEDTLS_SERVER_HELLO_RANDOM_LEN bytes
* - legacy_session_id_echo length 1 byte
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN + 3);
p += MBEDTLS_SERVER_HELLO_RANDOM_LEN + 2;
legacy_session_id_echo_len = *p;
/*
* Jump to the extensions, jumping over:
* - legacy_session_id_echo (legacy_session_id_echo_len + 1) bytes
* - cipher_suite 2 bytes
* - legacy_compression_method 1 byte
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, legacy_session_id_echo_len + 4);
p += legacy_session_id_echo_len + 4;
return mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts(
ssl, p, end,
&supported_versions_data, &supported_versions_data_end);
}
/* Returns a negative value on failure, and otherwise
* - 1 if the last eight bytes of the ServerHello random bytes indicate that
* the server is TLS 1.3 capable but negotiating TLS 1.2 or below.
* - 0 otherwise
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_is_downgrade_negotiation(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
/* First seven bytes of the magic downgrade strings, see RFC 8446 4.1.3 */
static const unsigned char magic_downgrade_string[] =
{ 0x44, 0x4F, 0x57, 0x4E, 0x47, 0x52, 0x44 };
const unsigned char *last_eight_bytes_of_random;
unsigned char last_byte_of_random;
MBEDTLS_SSL_CHK_BUF_READ_PTR(buf, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN + 2);
last_eight_bytes_of_random = buf + 2 + MBEDTLS_SERVER_HELLO_RANDOM_LEN - 8;
if (memcmp(last_eight_bytes_of_random,
magic_downgrade_string,
sizeof(magic_downgrade_string)) == 0) {
last_byte_of_random = last_eight_bytes_of_random[7];
return last_byte_of_random == 0 ||
last_byte_of_random == 1;
}
return 0;
}
/* Returns a negative value on failure, and otherwise
* - SSL_SERVER_HELLO or
* - SSL_SERVER_HELLO_HRR
* to indicate which message is expected and to be parsed next.
*/
#define SSL_SERVER_HELLO 0
#define SSL_SERVER_HELLO_HRR 1
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_server_hello_is_hrr(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
/* 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(mbedtls_ssl_tls13_hello_retry_request_magic));
if (memcmp(buf + 2, mbedtls_ssl_tls13_hello_retry_request_magic,
sizeof(mbedtls_ssl_tls13_hello_retry_request_magic)) == 0) {
return SSL_SERVER_HELLO_HRR;
}
return SSL_SERVER_HELLO;
}
/*
* Returns a negative value on failure, and otherwise
* - SSL_SERVER_HELLO or
* - SSL_SERVER_HELLO_HRR or
* - SSL_SERVER_HELLO_TLS1_2
*/
#define SSL_SERVER_HELLO_TLS1_2 2
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_preprocess_server_hello(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_is_supported_versions_ext_present(
ssl, buf, end));
if (ret == 0) {
MBEDTLS_SSL_PROC_CHK_NEG(
ssl_tls13_is_downgrade_negotiation(ssl, buf, end));
/* If the server is negotiating TLS 1.2 or below and:
* . we did not propose TLS 1.2 or
* . the server responded it is TLS 1.3 capable but negotiating a lower
* version of the protocol and thus we are under downgrade attack
* abort the handshake with an "illegal parameter" alert.
*/
if (handshake->min_tls_version > MBEDTLS_SSL_VERSION_TLS1_2 || ret) {
MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
/*
* Version 1.2 of the protocol has been negotiated, set the
* ssl->keep_current_message flag for the ServerHello to be kept and
* parsed as a TLS 1.2 ServerHello. We also change ssl->tls_version to
* MBEDTLS_SSL_VERSION_TLS1_2 thus from now on mbedtls_ssl_handshake_step()
* will dispatch to the TLS 1.2 state machine.
*/
ssl->keep_current_message = 1;
ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_2;
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_SERVER_HELLO,
buf, (size_t) (end - buf)));
if (mbedtls_ssl_conf_tls13_some_ephemeral_enabled(ssl)) {
ret = ssl_tls13_reset_key_share(ssl);
if (ret != 0) {
return ret;
}
}
return SSL_SERVER_HELLO_TLS1_2;
}
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
ssl->session_negotiate->endpoint = ssl->conf->endpoint;
ssl->session_negotiate->tls_version = ssl->tls_version;
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE;
ret = ssl_server_hello_is_hrr(ssl, buf, end);
switch (ret) {
case SSL_SERVER_HELLO:
MBEDTLS_SSL_DEBUG_MSG(2, ("received ServerHello message"));
break;
case SSL_SERVER_HELLO_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 (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;
}
handshake->hello_retry_request_count++;
break;
}
cleanup:
return ret;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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;
}
/* 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;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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 fatal_alert = 0;
uint32_t allowed_extensions_mask;
int hs_msg_type = is_hrr ? MBEDTLS_SSL_TLS1_3_HS_HELLO_RETRY_REQUEST :
MBEDTLS_SSL_HS_SERVER_HELLO;
/*
* 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 (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);
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 = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER;
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 valid and offered.
*/
if ((mbedtls_ssl_validate_ciphersuite(ssl, ciphersuite_info,
ssl->tls_version,
ssl->tls_version) != 0) ||
!mbedtls_ssl_tls13_cipher_suite_is_offered(ssl, cipher_suite)) {
fatal_alert = MBEDTLS_SSL_ALERT_MSG_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)) {
fatal_alert = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER;
}
if (fatal_alert == MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER) {
MBEDTLS_SSL_DEBUG_MSG(1, ("invalid ciphersuite(%04x) parameter",
cipher_suite));
goto cleanup;
}
/* Configure ciphersuites */
mbedtls_ssl_optimize_checksum(ssl, ciphersuite_info);
handshake->ciphersuite_info = ciphersuite_info;
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 = mbedtls_time(NULL);
#endif /* MBEDTLS_HAVE_TIME */
/* ...
* uint8 legacy_compression_method = 0;
* ...
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1);
if (p[0] != MBEDTLS_SSL_COMPRESS_NULL) {
MBEDTLS_SSL_DEBUG_MSG(1, ("bad legacy compression method"));
fatal_alert = MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER;
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);
handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE;
allowed_extensions_mask = is_hrr ?
MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_HRR :
MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_SH;
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;
ret = mbedtls_ssl_tls13_check_received_extension(
ssl, hs_msg_type, extension_type, allowed_extensions_mask);
if (ret != 0) {
return ret;
}
switch (extension_type) {
case MBEDTLS_TLS_EXT_COOKIE:
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;
case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS:
ret = ssl_tls13_parse_supported_versions_ext(ssl,
p,
extension_data_end);
if (ret != 0) {
goto cleanup;
}
break;
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED)
case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
MBEDTLS_SSL_DEBUG_MSG(3, ("found pre_shared_key extension"));
if ((ret = ssl_tls13_parse_server_pre_shared_key_ext(
ssl, p, extension_data_end)) != 0) {
MBEDTLS_SSL_DEBUG_RET(
1, ("ssl_tls13_parse_server_pre_shared_key_ext"), ret);
return ret;
}
break;
#endif
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 = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT;
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;
default:
ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
goto cleanup;
}
p += extension_data_len;
}
MBEDTLS_SSL_PRINT_EXTS(3, hs_msg_type, handshake->received_extensions);
cleanup:
if (fatal_alert == MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT) {
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 == MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER) {
MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
ret = MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
return ret;
}
#if defined(MBEDTLS_DEBUG_C)
static const char *ssl_tls13_get_kex_mode_str(int mode)
{
switch (mode) {
case MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK:
return "psk";
case MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL:
return "ephemeral";
case MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL:
return "psk_ephemeral";
default:
return "unknown mode";
}
}
#endif /* MBEDTLS_DEBUG_C */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_postprocess_server_hello(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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->received_extensions &
(MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) |
MBEDTLS_SSL_EXT_MASK(KEY_SHARE))) {
/* Only the pre_shared_key extension was received */
case MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY):
handshake->key_exchange_mode =
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK;
break;
/* Only the key_share extension was received */
case MBEDTLS_SSL_EXT_MASK(KEY_SHARE):
handshake->key_exchange_mode =
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL;
break;
/* Both the pre_shared_key and key_share extensions were received */
case (MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) |
MBEDTLS_SSL_EXT_MASK(KEY_SHARE)):
handshake->key_exchange_mode =
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;
}
#if defined(MBEDTLS_SSL_EARLY_DATA)
if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(EARLY_DATA) &&
(handshake->selected_identity != 0 ||
handshake->ciphersuite_info->id !=
ssl->session_negotiate->ciphersuite)) {
/* RFC8446 4.2.11
* If the server supplies an "early_data" extension, the
* client MUST verify that the server's selected_identity
* is 0. If any other value is returned, the client MUST
* abort the handshake with an "illegal_parameter" alert.
*
* RFC 8446 4.2.10
* In order to accept early data, the server MUST have accepted a PSK
* cipher suite and selected the first key offered in the client's
* "pre_shared_key" extension. In addition, it MUST verify that the
* following values are the same as those associated with the
* selected PSK:
* - The TLS version number
* - The selected cipher suite
* - The selected ALPN [RFC7301] protocol, if any
*
* We check here that when early data is involved the server
* selected the cipher suite associated to the pre-shared key
* as it must have.
*/
MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
#endif
if (!mbedtls_ssl_conf_tls13_check_kex_modes(
ssl, handshake->key_exchange_mode)) {
ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
MBEDTLS_SSL_DEBUG_MSG(
2, ("Key exchange mode(%s) is not supported.",
ssl_tls13_get_kex_mode_str(handshake->key_exchange_mode)));
goto cleanup;
}
MBEDTLS_SSL_DEBUG_MSG(
3, ("Selected key exchange mode: %s",
ssl_tls13_get_kex_mode_str(handshake->key_exchange_mode)));
/* Start the TLS 1.3 key scheduling if not already done.
*
* If we proposed early data then we have already derived an
* early secret using the selected PSK and its associated hash.
* It means that if the negotiated key exchange mode is psk or
* psk_ephemeral, we have already correctly computed the
* early secret and thus we do not do it again. In all other
* cases we compute it here.
*/
#if defined(MBEDTLS_SSL_EARLY_DATA)
if (ssl->early_data_status == MBEDTLS_SSL_EARLY_DATA_STATUS_NOT_SENT ||
handshake->key_exchange_mode ==
MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL)
#endif
{
ret = mbedtls_ssl_tls13_key_schedule_stage_early(ssl);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(
1, "mbedtls_ssl_tls13_key_schedule_stage_early", ret);
goto cleanup;
}
}
ret = mbedtls_ssl_tls13_compute_handshake_transform(ssl);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1,
"mbedtls_ssl_tls13_compute_handshake_transform",
ret);
goto cleanup;
}
mbedtls_ssl_set_inbound_transform(ssl, handshake->transform_handshake);
MBEDTLS_SSL_DEBUG_MSG(1, ("Switch to handshake keys for inbound traffic"));
ssl->session_negotiate->ciphersuite = handshake->ciphersuite_info->id;
ssl->session_in = ssl->session_negotiate;
cleanup:
if (ret != 0) {
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE);
}
return ret;
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_postprocess_hrr(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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;
}
ssl->session_negotiate->ciphersuite = ssl->handshake->ciphersuite_info->id;
return 0;
}
/*
* Wait and parse ServerHello handshake message.
* Handler for MBEDTLS_SSL_SERVER_HELLO
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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__));
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg(
ssl, MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len));
ret = ssl_tls13_preprocess_server_hello(ssl, buf, buf + buf_len);
if (ret < 0) {
goto cleanup;
} else {
is_hrr = (ret == SSL_SERVER_HELLO_HRR);
}
if (ret == SSL_SERVER_HELLO_TLS1_2) {
ret = 0;
goto cleanup;
}
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_PROC_CHK(mbedtls_ssl_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));
#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 */
} else {
MBEDTLS_SSL_PROC_CHK(ssl_tls13_postprocess_server_hello(ssl));
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS);
}
cleanup:
MBEDTLS_SSL_DEBUG_MSG(2, ("<= %s ( %s )", __func__,
is_hrr ? "HelloRetryRequest" : "ServerHello"));
return ret;
}
/*
*
* Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS
*
* The EncryptedExtensions message contains any extensions which
* should be protected, i.e., any which are not needed to establish
* the cryptographic context.
*/
/* Parse EncryptedExtensions message
* struct {
* Extension extensions<0..2^16-1>;
* } EncryptedExtensions;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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_handshake_params *handshake = ssl->handshake;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2);
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, "encrypted extensions", p, extensions_len);
handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE;
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);
ret = mbedtls_ssl_tls13_check_received_extension(
ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, extension_type,
MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_EE);
if (ret != 0) {
return ret;
}
switch (extension_type) {
#if defined(MBEDTLS_SSL_ALPN)
case MBEDTLS_TLS_EXT_ALPN:
MBEDTLS_SSL_DEBUG_MSG(3, ("found alpn extension"));
if ((ret = ssl_tls13_parse_alpn_ext(
ssl, p, (size_t) extension_data_len)) != 0) {
return ret;
}
break;
#endif /* MBEDTLS_SSL_ALPN */
#if defined(MBEDTLS_SSL_EARLY_DATA)
case MBEDTLS_TLS_EXT_EARLY_DATA:
if (extension_data_len != 0) {
/* The message must be empty. */
MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
MBEDTLS_ERR_SSL_DECODE_ERROR);
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
break;
#endif /* MBEDTLS_SSL_EARLY_DATA */
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT:
MBEDTLS_SSL_DEBUG_MSG(3, ("found record_size_limit extension"));
ret = mbedtls_ssl_tls13_parse_record_size_limit_ext(
ssl, p, p + extension_data_len);
/* TODO: Return unconditionally here until we handle the record
* size limit correctly. Once handled correctly, only return in
* case of errors. */
return ret;
break;
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
default:
MBEDTLS_SSL_PRINT_EXT(
3, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS,
extension_type, "( ignored )");
break;
}
p += extension_data_len;
}
MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS,
handshake->received_extensions);
/* 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;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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));
#if defined(MBEDTLS_SSL_EARLY_DATA)
if (ssl->handshake->received_extensions &
MBEDTLS_SSL_EXT_MASK(EARLY_DATA)) {
ssl->early_data_status = MBEDTLS_SSL_EARLY_DATA_STATUS_ACCEPTED;
}
#endif
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS,
buf, buf_len));
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_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
((void) ssl);
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED);
#endif
cleanup:
MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse encrypted extensions"));
return ret;
}
/*
* Handler for MBEDTLS_SSL_END_OF_EARLY_DATA
*
* RFC 8446 section 4.5
*
* struct {} EndOfEarlyData;
*
* If the server sent an "early_data" extension in EncryptedExtensions, the
* client MUST send an EndOfEarlyData message after receiving the server
* Finished. Otherwise, the client MUST NOT send an EndOfEarlyData message.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_end_of_early_data(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf = NULL;
size_t buf_len;
MBEDTLS_SSL_DEBUG_MSG(2, ("=> write EndOfEarlyData"));
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg(
ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA,
&buf, &buf_len));
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_hdr_to_checksum(
ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, 0));
MBEDTLS_SSL_PROC_CHK(
mbedtls_ssl_finish_handshake_msg(ssl, buf_len, 0));
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE);
cleanup:
MBEDTLS_SSL_DEBUG_MSG(2, ("<= write EndOfEarlyData"));
return ret;
}
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED)
/*
* STATE HANDLING: CertificateRequest
*
*/
#define SSL_CERTIFICATE_REQUEST_EXPECT_REQUEST 0
#define SSL_CERTIFICATE_REQUEST_SKIP 1
/* Coordination:
* Deals with the ambiguity of not knowing if a CertificateRequest
* will be sent. Returns a negative code on failure, or
* - SSL_CERTIFICATE_REQUEST_EXPECT_REQUEST
* - SSL_CERTIFICATE_REQUEST_SKIP
* indicating if a Certificate Request is expected or not.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_certificate_request_coordinate(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if ((ret = mbedtls_ssl_read_record(ssl, 0)) != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret);
return ret;
}
ssl->keep_current_message = 1;
if ((ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) &&
(ssl->in_msg[0] == MBEDTLS_SSL_HS_CERTIFICATE_REQUEST)) {
MBEDTLS_SSL_DEBUG_MSG(3, ("got a certificate request"));
return SSL_CERTIFICATE_REQUEST_EXPECT_REQUEST;
}
MBEDTLS_SSL_DEBUG_MSG(3, ("got no certificate request"));
return SSL_CERTIFICATE_REQUEST_SKIP;
}
/*
* ssl_tls13_parse_certificate_request()
* Parse certificate 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_parse_certificate_request(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 certificate_request_context_len = 0;
size_t extensions_len = 0;
const unsigned char *extensions_end;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
/* ...
* opaque certificate_request_context<0..2^8-1>
* ...
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1);
certificate_request_context_len = (size_t) p[0];
p += 1;
if (certificate_request_context_len > 0) {
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, certificate_request_context_len);
MBEDTLS_SSL_DEBUG_BUF(3, "Certificate Request Context",
p, certificate_request_context_len);
handshake->certificate_request_context =
mbedtls_calloc(1, certificate_request_context_len);
if (handshake->certificate_request_context == NULL) {
MBEDTLS_SSL_DEBUG_MSG(1, ("buffer too small"));
return MBEDTLS_ERR_SSL_ALLOC_FAILED;
}
memcpy(handshake->certificate_request_context, p,
certificate_request_context_len);
p += certificate_request_context_len;
}
/* ...
* Extension extensions<2..2^16-1>;
* ...
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2);
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;
handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE;
while (p < extensions_end) {
unsigned int extension_type;
size_t extension_data_len;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, 4);
extension_type = MBEDTLS_GET_UINT16_BE(p, 0);
extension_data_len = MBEDTLS_GET_UINT16_BE(p, 2);
p += 4;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, extension_data_len);
ret = mbedtls_ssl_tls13_check_received_extension(
ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, extension_type,
MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CR);
if (ret != 0) {
return ret;
}
switch (extension_type) {
case MBEDTLS_TLS_EXT_SIG_ALG:
MBEDTLS_SSL_DEBUG_MSG(3,
("found signature algorithms extension"));
ret = mbedtls_ssl_parse_sig_alg_ext(ssl, p,
p + extension_data_len);
if (ret != 0) {
return ret;
}
break;
default:
MBEDTLS_SSL_PRINT_EXT(
3, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST,
extension_type, "( ignored )");
break;
}
p += extension_data_len;
}
MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST,
handshake->received_extensions);
/* Check that we consumed all the message. */
if (p != end) {
MBEDTLS_SSL_DEBUG_MSG(1,
("CertificateRequest misaligned"));
goto decode_error;
}
/* RFC 8446 section 4.3.2
*
* The "signature_algorithms" extension MUST be specified
*/
if ((handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(SIG_ALG)) == 0) {
MBEDTLS_SSL_DEBUG_MSG(3,
("no signature algorithms extension found"));
goto decode_error;
}
ssl->handshake->client_auth = 1;
return 0;
decode_error:
MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
MBEDTLS_ERR_SSL_DECODE_ERROR);
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
/*
* Handler for MBEDTLS_SSL_CERTIFICATE_REQUEST
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_process_certificate_request(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse certificate request"));
MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_certificate_request_coordinate(ssl));
if (ret == SSL_CERTIFICATE_REQUEST_EXPECT_REQUEST) {
unsigned char *buf;
size_t buf_len;
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg(
ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST,
&buf, &buf_len));
MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_certificate_request(
ssl, buf, buf + buf_len));
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum(
ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST,
buf, buf_len));
} else if (ret == SSL_CERTIFICATE_REQUEST_SKIP) {
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, ("<= parse certificate request"));
return ret;
}
/*
* Handler for MBEDTLS_SSL_SERVER_CERTIFICATE
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */
/*
* Handler for MBEDTLS_SSL_SERVER_FINISHED
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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;
}
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;
}
#if defined(MBEDTLS_SSL_EARLY_DATA)
if (ssl->early_data_status == MBEDTLS_SSL_EARLY_DATA_STATUS_ACCEPTED) {
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_END_OF_EARLY_DATA);
} else if (ssl->early_data_status == MBEDTLS_SSL_EARLY_DATA_STATUS_REJECTED) {
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE);
} else
#endif /* MBEDTLS_SSL_EARLY_DATA */
{
#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_CERTIFICATE);
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
}
return 0;
}
/*
* Handler for MBEDTLS_SSL_CLIENT_CERTIFICATE
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_client_certificate(mbedtls_ssl_context *ssl)
{
int non_empty_certificate_msg = 0;
MBEDTLS_SSL_DEBUG_MSG(1,
("Switch to handshake traffic keys for outbound traffic"));
mbedtls_ssl_set_outbound_transform(ssl, ssl->handshake->transform_handshake);
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED)
if (ssl->handshake->client_auth) {
int ret = mbedtls_ssl_tls13_write_certificate(ssl);
if (ret != 0) {
return ret;
}
if (mbedtls_ssl_own_cert(ssl) != NULL) {
non_empty_certificate_msg = 1;
}
} else {
MBEDTLS_SSL_DEBUG_MSG(2, ("skip write certificate"));
}
#endif
if (non_empty_certificate_msg) {
mbedtls_ssl_handshake_set_state(ssl,
MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY);
} else {
MBEDTLS_SSL_DEBUG_MSG(2, ("skip write certificate verify"));
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_FINISHED);
}
return 0;
}
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED)
/*
* Handler for MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_client_certificate_verify(mbedtls_ssl_context *ssl)
{
int ret = mbedtls_ssl_tls13_write_certificate_verify(ssl);
if (ret == 0) {
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_FINISHED);
}
return ret;
}
#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */
/*
* Handler for MBEDTLS_SSL_CLIENT_FINISHED
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_write_client_finished(mbedtls_ssl_context *ssl)
{
int ret;
ret = mbedtls_ssl_tls13_write_finished_message(ssl);
if (ret != 0) {
return ret;
}
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);
return ret;
}
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_FLUSH_BUFFERS);
return 0;
}
/*
* Handler for MBEDTLS_SSL_FLUSH_BUFFERS
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_handshake_wrapup(mbedtls_ssl_context *ssl)
{
mbedtls_ssl_tls13_handshake_wrapup(ssl);
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER);
return 0;
}
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_new_session_ticket_exts(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
const unsigned char *p = buf;
handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE;
while (p < end) {
unsigned int extension_type;
size_t extension_data_len;
int ret;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 4);
extension_type = MBEDTLS_GET_UINT16_BE(p, 0);
extension_data_len = MBEDTLS_GET_UINT16_BE(p, 2);
p += 4;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extension_data_len);
ret = mbedtls_ssl_tls13_check_received_extension(
ssl, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, extension_type,
MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_NST);
if (ret != 0) {
return ret;
}
switch (extension_type) {
#if defined(MBEDTLS_SSL_EARLY_DATA)
case MBEDTLS_TLS_EXT_EARLY_DATA:
if (extension_data_len != 4) {
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
MBEDTLS_ERR_SSL_DECODE_ERROR);
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
if (ssl->session != NULL) {
ssl->session->ticket_flags |=
MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA;
}
break;
#endif /* MBEDTLS_SSL_EARLY_DATA */
default:
MBEDTLS_SSL_PRINT_EXT(
3, MBEDTLS_SSL_HS_NEW_SESSION_TICKET,
extension_type, "( ignored )");
break;
}
p += extension_data_len;
}
MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_NEW_SESSION_TICKET,
handshake->received_extensions);
return 0;
}
/*
* From RFC8446, page 74
*
* 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;
*
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_parse_new_session_ticket(mbedtls_ssl_context *ssl,
unsigned char *buf,
unsigned char *end,
unsigned char **ticket_nonce,
size_t *ticket_nonce_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf;
mbedtls_ssl_session *session = ssl->session;
size_t ticket_len;
unsigned char *ticket;
size_t extensions_len;
*ticket_nonce = NULL;
*ticket_nonce_len = 0;
/*
* ticket_lifetime 4 bytes
* ticket_age_add 4 bytes
* ticket_nonce_len 1 byte
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 9);
session->ticket_lifetime = MBEDTLS_GET_UINT32_BE(p, 0);
MBEDTLS_SSL_DEBUG_MSG(3,
("ticket_lifetime: %u",
(unsigned int) session->ticket_lifetime));
session->ticket_age_add = MBEDTLS_GET_UINT32_BE(p, 4);
MBEDTLS_SSL_DEBUG_MSG(3,
("ticket_age_add: %u",
(unsigned int) session->ticket_age_add));
*ticket_nonce_len = p[8];
p += 9;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, *ticket_nonce_len);
*ticket_nonce = p;
MBEDTLS_SSL_DEBUG_BUF(3, "ticket_nonce:", *ticket_nonce, *ticket_nonce_len);
p += *ticket_nonce_len;
/* Ticket */
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2);
ticket_len = MBEDTLS_GET_UINT16_BE(p, 0);
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, ticket_len);
MBEDTLS_SSL_DEBUG_BUF(3, "received ticket", p, ticket_len);
/* Check if we previously received a ticket already. */
if (session->ticket != NULL || session->ticket_len > 0) {
mbedtls_free(session->ticket);
session->ticket = NULL;
session->ticket_len = 0;
}
if ((ticket = mbedtls_calloc(1, ticket_len)) == NULL) {
MBEDTLS_SSL_DEBUG_MSG(1, ("ticket alloc failed"));
return MBEDTLS_ERR_SSL_ALLOC_FAILED;
}
memcpy(ticket, p, ticket_len);
p += ticket_len;
session->ticket = ticket;
session->ticket_len = ticket_len;
/* Clear all flags in ticket_flags */
mbedtls_ssl_session_clear_ticket_flags(
session, MBEDTLS_SSL_TLS1_3_TICKET_FLAGS_MASK);
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2);
extensions_len = MBEDTLS_GET_UINT16_BE(p, 0);
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extensions_len);
MBEDTLS_SSL_DEBUG_BUF(3, "ticket extension", p, extensions_len);
ret = ssl_tls13_parse_new_session_ticket_exts(ssl, p, p + extensions_len);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1,
"ssl_tls13_parse_new_session_ticket_exts",
ret);
return ret;
}
/* session has been updated, allow export */
session->exported = 0;
return 0;
}
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_postprocess_new_session_ticket(mbedtls_ssl_context *ssl,
unsigned char *ticket_nonce,
size_t ticket_nonce_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ssl_session *session = ssl->session;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
psa_algorithm_t psa_hash_alg;
int hash_length;
#if defined(MBEDTLS_HAVE_TIME)
/* Store ticket creation time */
session->ticket_received = mbedtls_time(NULL);
#endif
ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(session->ciphersuite);
if (ciphersuite_info == NULL) {
MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
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;
}
MBEDTLS_SSL_DEBUG_BUF(3, "resumption_master_secret",
session->app_secrets.resumption_master_secret,
hash_length);
/* 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_len,
session->resumption_key,
hash_length);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(2,
"Creating the ticket-resumed PSK failed",
ret);
return ret;
}
session->resumption_key_len = hash_length;
MBEDTLS_SSL_DEBUG_BUF(3, "Ticket-resumed PSK",
session->resumption_key,
session->resumption_key_len);
/* Set ticket_flags depends on the selected key exchange modes */
mbedtls_ssl_session_set_ticket_flags(
session, ssl->conf->tls13_kex_modes);
MBEDTLS_SSL_PRINT_TICKET_FLAGS(4, session->ticket_flags);
return 0;
}
/*
* Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_process_new_session_ticket(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf;
size_t buf_len;
unsigned char *ticket_nonce;
size_t ticket_nonce_len;
MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse new session ticket"));
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg(
ssl, MBEDTLS_SSL_HS_NEW_SESSION_TICKET,
&buf, &buf_len));
MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_new_session_ticket(
ssl, buf, buf + buf_len,
&ticket_nonce, &ticket_nonce_len));
MBEDTLS_SSL_PROC_CHK(ssl_tls13_postprocess_new_session_ticket(
ssl, ticket_nonce, ticket_nonce_len));
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER);
cleanup:
MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse new session ticket"));
return ret;
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
int mbedtls_ssl_tls13_handshake_client_step(mbedtls_ssl_context *ssl)
{
int ret = 0;
switch (ssl->state) {
case MBEDTLS_SSL_HELLO_REQUEST:
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO);
break;
case MBEDTLS_SSL_CLIENT_HELLO:
ret = mbedtls_ssl_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_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_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_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */
case MBEDTLS_SSL_SERVER_FINISHED:
ret = ssl_tls13_process_server_finished(ssl);
break;
case MBEDTLS_SSL_END_OF_EARLY_DATA:
ret = ssl_tls13_write_end_of_early_data(ssl);
break;
case MBEDTLS_SSL_CLIENT_CERTIFICATE:
ret = ssl_tls13_write_client_certificate(ssl);
break;
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED)
case MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY:
ret = ssl_tls13_write_client_certificate_verify(ssl);
break;
#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */
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_BEFORE_2ND_CLIENT_HELLO:
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_CLIENT_CCS_AFTER_SERVER_FINISHED:
ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl);
if (ret == 0) {
mbedtls_ssl_handshake_set_state(
ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE);
}
break;
case MBEDTLS_SSL_CLIENT_CCS_AFTER_CLIENT_HELLO:
ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl);
if (ret == 0) {
mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_HELLO);
#if defined(MBEDTLS_SSL_EARLY_DATA)
MBEDTLS_SSL_DEBUG_MSG(
1, ("Switch to early data keys for outbound traffic"));
mbedtls_ssl_set_outbound_transform(
ssl, ssl->handshake->transform_earlydata);
#endif
}
break;
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET:
ret = ssl_tls13_process_new_session_ticket(ssl);
if (ret != 0) {
break;
}
ret = MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET;
break;
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
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 && MBEDTLS_SSL_PROTO_TLS1_3 */