proxmark3/common/mbedtls/ssl_cookie.c
2021-05-14 14:07:59 +02:00

241 lines
6.9 KiB
C

/*
* 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)
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
#include "mbedtls/ssl_cookie.h"
#include "mbedtls/ssl_internal.h"
#include "mbedtls/error.h"
#include "mbedtls/platform_util.h"
#include <string.h>
/*
* If DTLS is in use, then at least one of SHA-1, SHA-256, SHA-512 is
* available. Try SHA-256 first, 512 wastes resources since we need to stay
* with max 32 bytes of cookie for DTLS 1.0
*/
#if defined(MBEDTLS_SHA256_C)
#define COOKIE_MD MBEDTLS_MD_SHA224
#define COOKIE_MD_OUTLEN 32
#define COOKIE_HMAC_LEN 28
#elif defined(MBEDTLS_SHA512_C)
#define COOKIE_MD MBEDTLS_MD_SHA384
#define COOKIE_MD_OUTLEN 48
#define COOKIE_HMAC_LEN 28
#elif defined(MBEDTLS_SHA1_C)
#define COOKIE_MD MBEDTLS_MD_SHA1
#define COOKIE_MD_OUTLEN 20
#define COOKIE_HMAC_LEN 20
#else
#error "DTLS hello verify needs SHA-1 or SHA-2"
#endif
/*
* Cookies are formed of a 4-bytes timestamp (or serial number) and
* an HMAC of timestemp and client ID.
*/
#define COOKIE_LEN ( 4 + COOKIE_HMAC_LEN )
void mbedtls_ssl_cookie_init(mbedtls_ssl_cookie_ctx *ctx) {
mbedtls_md_init(&ctx->hmac_ctx);
#if !defined(MBEDTLS_HAVE_TIME)
ctx->serial = 0;
#endif
ctx->timeout = MBEDTLS_SSL_COOKIE_TIMEOUT;
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init(&ctx->mutex);
#endif
}
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) {
mbedtls_md_free(&ctx->hmac_ctx);
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_free(&ctx->mutex);
#endif
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) {
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));
return (0);
}
/*
* Generate the HMAC part of a cookie
*/
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);
}
/*
* 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) {
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
(*p)[0] = (unsigned char)(t >> 24);
(*p)[1] = (unsigned char)(t >> 16);
(*p)[2] = (unsigned char)(t >> 8);
(*p)[3] = (unsigned char)(t);
*p += 4;
#if defined(MBEDTLS_THREADING_C)
if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0)
return (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_ERR_SSL_INTERNAL_ERROR +
MBEDTLS_ERR_THREADING_MUTEX_ERROR);
#endif
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) {
unsigned char ref_hmac[COOKIE_HMAC_LEN];
int ret = 0;
unsigned char *p = ref_hmac;
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_THREADING_C)
if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0)
return (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)
return (MBEDTLS_ERR_SSL_INTERNAL_ERROR +
MBEDTLS_ERR_THREADING_MUTEX_ERROR);
#endif
if (ret != 0)
return (ret);
if (mbedtls_ssl_safer_memcmp(cookie + 4, ref_hmac, sizeof(ref_hmac)) != 0)
return (-1);
#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)
return (-1);
return (0);
}
#endif /* MBEDTLS_SSL_COOKIE_C */