blob: ef4d1886d3a373b584246502ef96e4a35df2e6d3 [file] [log] [blame]
/*
* DTLS cookie callbacks implementation
*
* 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.
*/
/*
* These session callbacks use a simple chained list
* to store and retrieve the session information.
*/
#include "common.h"
#if defined(MBEDTLS_SSL_COOKIE_C)
#include "mbedtls/platform.h"
#include "mbedtls/ssl_cookie.h"
#include "ssl_misc.h"
#include "mbedtls/error.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/constant_time.h"
#include "mbedtls/legacy_or_psa.h"
#include <string.h>
#if defined(MBEDTLS_USE_PSA_CRYPTO)
#define PSA_TO_MBEDTLS_ERR(status) PSA_TO_MBEDTLS_ERR_LIST(status, \
psa_to_ssl_errors, \
psa_generic_status_to_mbedtls)
#endif
/*
* If DTLS is in use, then at least one of SHA-256 or SHA-384 is
* available. Try SHA-256 first as 384 wastes resources
*/
#if defined(MBEDTLS_HAS_ALG_SHA_256_VIA_LOWLEVEL_OR_PSA)
#define COOKIE_MD MBEDTLS_MD_SHA256
#define COOKIE_MD_OUTLEN 32
#define COOKIE_HMAC_LEN 28
#elif defined(MBEDTLS_HAS_ALG_SHA_384_VIA_LOWLEVEL_OR_PSA)
#define COOKIE_MD MBEDTLS_MD_SHA384
#define COOKIE_MD_OUTLEN 48
#define COOKIE_HMAC_LEN 28
#else
#error "DTLS hello verify needs SHA-256 or SHA-384"
#endif
/*
* Cookies are formed of a 4-bytes timestamp (or serial number) and
* an HMAC of timestamp and client ID.
*/
#define COOKIE_LEN (4 + COOKIE_HMAC_LEN)
void mbedtls_ssl_cookie_init(mbedtls_ssl_cookie_ctx *ctx)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
ctx->psa_hmac_key = MBEDTLS_SVC_KEY_ID_INIT;
#else
mbedtls_md_init(&ctx->hmac_ctx);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#if !defined(MBEDTLS_HAVE_TIME)
ctx->serial = 0;
#endif
ctx->timeout = MBEDTLS_SSL_COOKIE_TIMEOUT;
#if !defined(MBEDTLS_USE_PSA_CRYPTO)
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init(&ctx->mutex);
#endif
#endif /* !MBEDTLS_USE_PSA_CRYPTO */
}
void mbedtls_ssl_cookie_set_timeout(mbedtls_ssl_cookie_ctx *ctx, unsigned long delay)
{
ctx->timeout = delay;
}
void mbedtls_ssl_cookie_free(mbedtls_ssl_cookie_ctx *ctx)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_destroy_key(ctx->psa_hmac_key);
#else
mbedtls_md_free(&ctx->hmac_ctx);
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_free(&ctx->mutex);
#endif
#endif /* MBEDTLS_USE_PSA_CRYPTO */
mbedtls_platform_zeroize(ctx, sizeof(mbedtls_ssl_cookie_ctx));
}
int mbedtls_ssl_cookie_setup(mbedtls_ssl_cookie_ctx *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
psa_algorithm_t alg;
(void) f_rng;
(void) p_rng;
alg = mbedtls_hash_info_psa_from_md(COOKIE_MD);
if (alg == 0) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
ctx->psa_hmac_alg = PSA_ALG_TRUNCATED_MAC(PSA_ALG_HMAC(alg),
COOKIE_HMAC_LEN);
psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_VERIFY_MESSAGE |
PSA_KEY_USAGE_SIGN_MESSAGE);
psa_set_key_algorithm(&attributes, ctx->psa_hmac_alg);
psa_set_key_type(&attributes, PSA_KEY_TYPE_HMAC);
psa_set_key_bits(&attributes, PSA_BYTES_TO_BITS(COOKIE_MD_OUTLEN));
if ((status = psa_generate_key(&attributes,
&ctx->psa_hmac_key)) != PSA_SUCCESS) {
return PSA_TO_MBEDTLS_ERR(status);
}
#else
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char key[COOKIE_MD_OUTLEN];
if ((ret = f_rng(p_rng, key, sizeof(key))) != 0) {
return ret;
}
ret = mbedtls_md_setup(&ctx->hmac_ctx, mbedtls_md_info_from_type(COOKIE_MD), 1);
if (ret != 0) {
return ret;
}
ret = mbedtls_md_hmac_starts(&ctx->hmac_ctx, key, sizeof(key));
if (ret != 0) {
return ret;
}
mbedtls_platform_zeroize(key, sizeof(key));
#endif /* MBEDTLS_USE_PSA_CRYPTO */
return 0;
}
#if !defined(MBEDTLS_USE_PSA_CRYPTO)
/*
* Generate the HMAC part of a cookie
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_cookie_hmac(mbedtls_md_context_t *hmac_ctx,
const unsigned char time[4],
unsigned char **p, unsigned char *end,
const unsigned char *cli_id, size_t cli_id_len)
{
unsigned char hmac_out[COOKIE_MD_OUTLEN];
MBEDTLS_SSL_CHK_BUF_PTR(*p, end, COOKIE_HMAC_LEN);
if (mbedtls_md_hmac_reset(hmac_ctx) != 0 ||
mbedtls_md_hmac_update(hmac_ctx, time, 4) != 0 ||
mbedtls_md_hmac_update(hmac_ctx, cli_id, cli_id_len) != 0 ||
mbedtls_md_hmac_finish(hmac_ctx, hmac_out) != 0) {
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
memcpy(*p, hmac_out, COOKIE_HMAC_LEN);
*p += COOKIE_HMAC_LEN;
return 0;
}
#endif /* !MBEDTLS_USE_PSA_CRYPTO */
/*
* Generate cookie for DTLS ClientHello verification
*/
int mbedtls_ssl_cookie_write(void *p_ctx,
unsigned char **p, unsigned char *end,
const unsigned char *cli_id, size_t cli_id_len)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
size_t sign_mac_length = 0;
#endif
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ssl_cookie_ctx *ctx = (mbedtls_ssl_cookie_ctx *) p_ctx;
unsigned long t;
if (ctx == NULL || cli_id == NULL) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
MBEDTLS_SSL_CHK_BUF_PTR(*p, end, COOKIE_LEN);
#if defined(MBEDTLS_HAVE_TIME)
t = (unsigned long) mbedtls_time(NULL);
#else
t = ctx->serial++;
#endif
MBEDTLS_PUT_UINT32_BE(t, *p, 0);
*p += 4;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_mac_sign_setup(&operation, ctx->psa_hmac_key,
ctx->psa_hmac_alg);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto exit;
}
status = psa_mac_update(&operation, *p - 4, 4);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto exit;
}
status = psa_mac_update(&operation, cli_id, cli_id_len);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto exit;
}
status = psa_mac_sign_finish(&operation, *p, COOKIE_MD_OUTLEN,
&sign_mac_length);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto exit;
}
*p += COOKIE_HMAC_LEN;
ret = 0;
#else
#if defined(MBEDTLS_THREADING_C)
if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_SSL_INTERNAL_ERROR, ret);
}
#endif
ret = ssl_cookie_hmac(&ctx->hmac_ctx, *p - 4,
p, end, cli_id, cli_id_len);
#if defined(MBEDTLS_THREADING_C)
if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_SSL_INTERNAL_ERROR,
MBEDTLS_ERR_THREADING_MUTEX_ERROR);
}
#endif
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#if defined(MBEDTLS_USE_PSA_CRYPTO)
exit:
status = psa_mac_abort(&operation);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
return ret;
}
/*
* Check a cookie
*/
int mbedtls_ssl_cookie_check(void *p_ctx,
const unsigned char *cookie, size_t cookie_len,
const unsigned char *cli_id, size_t cli_id_len)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
#else
unsigned char ref_hmac[COOKIE_HMAC_LEN];
unsigned char *p = ref_hmac;
#endif
int ret = 0;
mbedtls_ssl_cookie_ctx *ctx = (mbedtls_ssl_cookie_ctx *) p_ctx;
unsigned long cur_time, cookie_time;
if (ctx == NULL || cli_id == NULL) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (cookie_len != COOKIE_LEN) {
return -1;
}
#if defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_mac_verify_setup(&operation, ctx->psa_hmac_key,
ctx->psa_hmac_alg);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto exit;
}
status = psa_mac_update(&operation, cookie, 4);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto exit;
}
status = psa_mac_update(&operation, cli_id,
cli_id_len);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto exit;
}
status = psa_mac_verify_finish(&operation, cookie + 4,
COOKIE_HMAC_LEN);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto exit;
}
ret = 0;
#else
#if defined(MBEDTLS_THREADING_C)
if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_SSL_INTERNAL_ERROR, ret);
}
#endif
if (ssl_cookie_hmac(&ctx->hmac_ctx, cookie,
&p, p + sizeof(ref_hmac),
cli_id, cli_id_len) != 0) {
ret = -1;
}
#if defined(MBEDTLS_THREADING_C)
if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_SSL_INTERNAL_ERROR,
MBEDTLS_ERR_THREADING_MUTEX_ERROR);
}
#endif
if (ret != 0) {
goto exit;
}
if (mbedtls_ct_memcmp(cookie + 4, ref_hmac, sizeof(ref_hmac)) != 0) {
ret = -1;
goto exit;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#if defined(MBEDTLS_HAVE_TIME)
cur_time = (unsigned long) mbedtls_time(NULL);
#else
cur_time = ctx->serial;
#endif
cookie_time = ((unsigned long) cookie[0] << 24) |
((unsigned long) cookie[1] << 16) |
((unsigned long) cookie[2] << 8) |
((unsigned long) cookie[3]);
if (ctx->timeout != 0 && cur_time - cookie_time > ctx->timeout) {
ret = -1;
goto exit;
}
exit:
#if defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_mac_abort(&operation);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
}
#else
mbedtls_platform_zeroize(ref_hmac, sizeof(ref_hmac));
#endif /* MBEDTLS_USE_PSA_CRYPTO */
return ret;
}
#endif /* MBEDTLS_SSL_COOKIE_C */