| /* |
| * 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 "ssl_misc.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_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 |
| |
| 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_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 ) |
| return( MBEDTLS_ERROR_ADD( 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 */ |