Marco Zecchini
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Example_RTOS
Rtos API example
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ssl_cookie.c
00001 /* 00002 * DTLS cookie callbacks implementation 00003 * 00004 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 00005 * SPDX-License-Identifier: Apache-2.0 00006 * 00007 * Licensed under the Apache License, Version 2.0 (the "License"); you may 00008 * not use this file except in compliance with the License. 00009 * You may obtain a copy of the License at 00010 * 00011 * http://www.apache.org/licenses/LICENSE-2.0 00012 * 00013 * Unless required by applicable law or agreed to in writing, software 00014 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 00015 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00016 * See the License for the specific language governing permissions and 00017 * limitations under the License. 00018 * 00019 * This file is part of mbed TLS (https://tls.mbed.org) 00020 */ 00021 /* 00022 * These session callbacks use a simple chained list 00023 * to store and retrieve the session information. 00024 */ 00025 00026 #if !defined(MBEDTLS_CONFIG_FILE) 00027 #include "mbedtls/config.h" 00028 #else 00029 #include MBEDTLS_CONFIG_FILE 00030 #endif 00031 00032 #if defined(MBEDTLS_SSL_COOKIE_C) 00033 00034 #if defined(MBEDTLS_PLATFORM_C) 00035 #include "mbedtls/platform.h" 00036 #else 00037 #define mbedtls_calloc calloc 00038 #define mbedtls_free free 00039 #endif 00040 00041 #include "mbedtls/ssl_cookie.h" 00042 #include "mbedtls/ssl_internal.h" 00043 00044 #include <string.h> 00045 00046 /* Implementation that should never be optimized out by the compiler */ 00047 static void mbedtls_zeroize( void *v, size_t n ) { 00048 volatile unsigned char *p = v; while( n-- ) *p++ = 0; 00049 } 00050 00051 /* 00052 * If DTLS is in use, then at least one of SHA-1, SHA-256, SHA-512 is 00053 * available. Try SHA-256 first, 512 wastes resources since we need to stay 00054 * with max 32 bytes of cookie for DTLS 1.0 00055 */ 00056 #if defined(MBEDTLS_SHA256_C) 00057 #define COOKIE_MD MBEDTLS_MD_SHA224 00058 #define COOKIE_MD_OUTLEN 32 00059 #define COOKIE_HMAC_LEN 28 00060 #elif defined(MBEDTLS_SHA512_C) 00061 #define COOKIE_MD MBEDTLS_MD_SHA384 00062 #define COOKIE_MD_OUTLEN 48 00063 #define COOKIE_HMAC_LEN 28 00064 #elif defined(MBEDTLS_SHA1_C) 00065 #define COOKIE_MD MBEDTLS_MD_SHA1 00066 #define COOKIE_MD_OUTLEN 20 00067 #define COOKIE_HMAC_LEN 20 00068 #else 00069 #error "DTLS hello verify needs SHA-1 or SHA-2" 00070 #endif 00071 00072 /* 00073 * Cookies are formed of a 4-bytes timestamp (or serial number) and 00074 * an HMAC of timestemp and client ID. 00075 */ 00076 #define COOKIE_LEN ( 4 + COOKIE_HMAC_LEN ) 00077 00078 void mbedtls_ssl_cookie_init( mbedtls_ssl_cookie_ctx *ctx ) 00079 { 00080 mbedtls_md_init( &ctx->hmac_ctx ); 00081 #if !defined(MBEDTLS_HAVE_TIME) 00082 ctx->serial = 0; 00083 #endif 00084 ctx->timeout = MBEDTLS_SSL_COOKIE_TIMEOUT; 00085 00086 #if defined(MBEDTLS_THREADING_C) 00087 mbedtls_mutex_init( &ctx->mutex ); 00088 #endif 00089 } 00090 00091 void mbedtls_ssl_cookie_set_timeout( mbedtls_ssl_cookie_ctx *ctx, unsigned long delay ) 00092 { 00093 ctx->timeout = delay; 00094 } 00095 00096 void mbedtls_ssl_cookie_free( mbedtls_ssl_cookie_ctx *ctx ) 00097 { 00098 mbedtls_md_free( &ctx->hmac_ctx ); 00099 00100 #if defined(MBEDTLS_THREADING_C) 00101 mbedtls_mutex_free( &ctx->mutex ); 00102 #endif 00103 00104 mbedtls_zeroize( ctx, sizeof( mbedtls_ssl_cookie_ctx ) ); 00105 } 00106 00107 int mbedtls_ssl_cookie_setup( mbedtls_ssl_cookie_ctx *ctx, 00108 int (*f_rng)(void *, unsigned char *, size_t), 00109 void *p_rng ) 00110 { 00111 int ret; 00112 unsigned char key[COOKIE_MD_OUTLEN]; 00113 00114 if( ( ret = f_rng( p_rng, key, sizeof( key ) ) ) != 0 ) 00115 return( ret ); 00116 00117 ret = mbedtls_md_setup( &ctx->hmac_ctx , mbedtls_md_info_from_type( COOKIE_MD ), 1 ); 00118 if( ret != 0 ) 00119 return( ret ); 00120 00121 ret = mbedtls_md_hmac_starts( &ctx->hmac_ctx , key, sizeof( key ) ); 00122 if( ret != 0 ) 00123 return( ret ); 00124 00125 mbedtls_zeroize( key, sizeof( key ) ); 00126 00127 return( 0 ); 00128 } 00129 00130 /* 00131 * Generate the HMAC part of a cookie 00132 */ 00133 static int ssl_cookie_hmac( mbedtls_md_context_t *hmac_ctx, 00134 const unsigned char time[4], 00135 unsigned char **p, unsigned char *end, 00136 const unsigned char *cli_id, size_t cli_id_len ) 00137 { 00138 unsigned char hmac_out[COOKIE_MD_OUTLEN]; 00139 00140 if( (size_t)( end - *p ) < COOKIE_HMAC_LEN ) 00141 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); 00142 00143 if( mbedtls_md_hmac_reset( hmac_ctx ) != 0 || 00144 mbedtls_md_hmac_update( hmac_ctx, time, 4 ) != 0 || 00145 mbedtls_md_hmac_update( hmac_ctx, cli_id, cli_id_len ) != 0 || 00146 mbedtls_md_hmac_finish( hmac_ctx, hmac_out ) != 0 ) 00147 { 00148 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); 00149 } 00150 00151 memcpy( *p, hmac_out, COOKIE_HMAC_LEN ); 00152 *p += COOKIE_HMAC_LEN; 00153 00154 return( 0 ); 00155 } 00156 00157 /* 00158 * Generate cookie for DTLS ClientHello verification 00159 */ 00160 int mbedtls_ssl_cookie_write( void *p_ctx, 00161 unsigned char **p, unsigned char *end, 00162 const unsigned char *cli_id, size_t cli_id_len ) 00163 { 00164 int ret; 00165 mbedtls_ssl_cookie_ctx *ctx = (mbedtls_ssl_cookie_ctx *) p_ctx; 00166 unsigned long t; 00167 00168 if( ctx == NULL || cli_id == NULL ) 00169 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); 00170 00171 if( (size_t)( end - *p ) < COOKIE_LEN ) 00172 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); 00173 00174 #if defined(MBEDTLS_HAVE_TIME) 00175 t = (unsigned long) mbedtls_time( NULL ); 00176 #else 00177 t = ctx->serial ++; 00178 #endif 00179 00180 (*p)[0] = (unsigned char)( t >> 24 ); 00181 (*p)[1] = (unsigned char)( t >> 16 ); 00182 (*p)[2] = (unsigned char)( t >> 8 ); 00183 (*p)[3] = (unsigned char)( t ); 00184 *p += 4; 00185 00186 #if defined(MBEDTLS_THREADING_C) 00187 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 00188 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR + ret ); 00189 #endif 00190 00191 ret = ssl_cookie_hmac( &ctx->hmac_ctx , *p - 4, 00192 p, end, cli_id, cli_id_len ); 00193 00194 #if defined(MBEDTLS_THREADING_C) 00195 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 00196 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR + 00197 MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 00198 #endif 00199 00200 return( ret ); 00201 } 00202 00203 /* 00204 * Check a cookie 00205 */ 00206 int mbedtls_ssl_cookie_check( void *p_ctx, 00207 const unsigned char *cookie, size_t cookie_len, 00208 const unsigned char *cli_id, size_t cli_id_len ) 00209 { 00210 unsigned char ref_hmac[COOKIE_HMAC_LEN]; 00211 int ret = 0; 00212 unsigned char *p = ref_hmac; 00213 mbedtls_ssl_cookie_ctx *ctx = (mbedtls_ssl_cookie_ctx *) p_ctx; 00214 unsigned long cur_time, cookie_time; 00215 00216 if( ctx == NULL || cli_id == NULL ) 00217 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); 00218 00219 if( cookie_len != COOKIE_LEN ) 00220 return( -1 ); 00221 00222 #if defined(MBEDTLS_THREADING_C) 00223 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 00224 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR + ret ); 00225 #endif 00226 00227 if( ssl_cookie_hmac( &ctx->hmac_ctx , cookie, 00228 &p, p + sizeof( ref_hmac ), 00229 cli_id, cli_id_len ) != 0 ) 00230 ret = -1; 00231 00232 #if defined(MBEDTLS_THREADING_C) 00233 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 00234 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR + 00235 MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 00236 #endif 00237 00238 if( ret != 0 ) 00239 return( ret ); 00240 00241 if( mbedtls_ssl_safer_memcmp( cookie + 4, ref_hmac, sizeof( ref_hmac ) ) != 0 ) 00242 return( -1 ); 00243 00244 #if defined(MBEDTLS_HAVE_TIME) 00245 cur_time = (unsigned long) mbedtls_time( NULL ); 00246 #else 00247 cur_time = ctx->serial ; 00248 #endif 00249 00250 cookie_time = ( (unsigned long) cookie[0] << 24 ) | 00251 ( (unsigned long) cookie[1] << 16 ) | 00252 ( (unsigned long) cookie[2] << 8 ) | 00253 ( (unsigned long) cookie[3] ); 00254 00255 if( ctx->timeout != 0 && cur_time - cookie_time > ctx->timeout ) 00256 return( -1 ); 00257 00258 return( 0 ); 00259 } 00260 #endif /* MBEDTLS_SSL_COOKIE_C */
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