1 /* 2 * Common and shared functions used by multiple modules in the Mbed TLS 3 * library. 4 * 5 * Copyright The Mbed TLS Contributors 6 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 7 * 8 * This file is provided under the Apache License 2.0, or the 9 * GNU General Public License v2.0 or later. 10 * 11 * ********** 12 * Apache License 2.0: 13 * 14 * Licensed under the Apache License, Version 2.0 (the "License"); you may 15 * not use this file except in compliance with the License. 16 * You may obtain a copy of the License at 17 * 18 * http://www.apache.org/licenses/LICENSE-2.0 19 * 20 * Unless required by applicable law or agreed to in writing, software 21 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 22 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 23 * See the License for the specific language governing permissions and 24 * limitations under the License. 25 * 26 * ********** 27 * 28 * ********** 29 * GNU General Public License v2.0 or later: 30 * 31 * This program is free software; you can redistribute it and/or modify 32 * it under the terms of the GNU General Public License as published by 33 * the Free Software Foundation; either version 2 of the License, or 34 * (at your option) any later version. 35 * 36 * This program is distributed in the hope that it will be useful, 37 * but WITHOUT ANY WARRANTY; without even the implied warranty of 38 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 39 * GNU General Public License for more details. 40 * 41 * You should have received a copy of the GNU General Public License along 42 * with this program; if not, write to the Free Software Foundation, Inc., 43 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 44 * 45 * ********** 46 */ 47 48 /* 49 * Ensure gmtime_r is available even with -std=c99; must be defined before 50 * config.h, which pulls in glibc's features.h. Harmless on other platforms. 51 */ 52 #if !defined(_POSIX_C_SOURCE) 53 #define _POSIX_C_SOURCE 200112L 54 #endif 55 56 #if !defined(MBEDTLS_CONFIG_FILE) 57 #include "mbedtls/config.h" 58 #else 59 #include MBEDTLS_CONFIG_FILE 60 #endif 61 62 #include "mbedtls/platform_util.h" 63 #include "mbedtls/platform.h" 64 #include "mbedtls/threading.h" 65 66 #include <stddef.h> 67 #include <string.h> 68 69 #if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT) 70 /* 71 * This implementation should never be optimized out by the compiler 72 * 73 * This implementation for mbedtls_platform_zeroize() was inspired from Colin 74 * Percival's blog article at: 75 * 76 * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html 77 * 78 * It uses a volatile function pointer to the standard memset(). Because the 79 * pointer is volatile the compiler expects it to change at 80 * any time and will not optimize out the call that could potentially perform 81 * other operations on the input buffer instead of just setting it to 0. 82 * Nevertheless, as pointed out by davidtgoldblatt on Hacker News 83 * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for 84 * details), optimizations of the following form are still possible: 85 * 86 * if( memset_func != memset ) 87 * memset_func( buf, 0, len ); 88 * 89 * Note that it is extremely difficult to guarantee that 90 * mbedtls_platform_zeroize() will not be optimized out by aggressive compilers 91 * in a portable way. For this reason, Mbed TLS also provides the configuration 92 * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure 93 * mbedtls_platform_zeroize() to use a suitable implementation for their 94 * platform and needs. 95 */ 96 static void * (* const volatile memset_func)( void *, int, size_t ) = memset; 97 98 void mbedtls_platform_zeroize( void *buf, size_t len ) 99 { 100 MBEDTLS_INTERNAL_VALIDATE( len == 0 || buf != NULL ); 101 102 if( len > 0 ) 103 memset_func( buf, 0, len ); 104 } 105 #endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */ 106 107 #if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT) 108 #include <time.h> 109 #if !defined(_WIN32) && (defined(unix) || \ 110 defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \ 111 defined(__MACH__))) 112 #include <unistd.h> 113 #endif /* !_WIN32 && (unix || __unix || __unix__ || 114 * (__APPLE__ && __MACH__)) */ 115 116 #if !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \ 117 ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \ 118 _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) 119 /* 120 * This is a convenience shorthand macro to avoid checking the long 121 * preprocessor conditions above. Ideally, we could expose this macro in 122 * platform_util.h and simply use it in platform_util.c, threading.c and 123 * threading.h. However, this macro is not part of the Mbed TLS public API, so 124 * we keep it private by only defining it in this file 125 */ 126 #if ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) 127 #define PLATFORM_UTIL_USE_GMTIME 128 #endif /* ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) */ 129 130 #endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \ 131 ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \ 132 _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */ 133 134 struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt, 135 struct tm *tm_buf ) 136 { 137 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) 138 return( ( gmtime_s( tm_buf, tt ) == 0 ) ? tm_buf : NULL ); 139 #elif !defined(PLATFORM_UTIL_USE_GMTIME) 140 return( gmtime_r( tt, tm_buf ) ); 141 #else 142 struct tm *lt; 143 144 #if defined(MBEDTLS_THREADING_C) 145 if( mbedtls_mutex_lock( &mbedtls_threading_gmtime_mutex ) != 0 ) 146 return( NULL ); 147 #endif /* MBEDTLS_THREADING_C */ 148 149 lt = gmtime( tt ); 150 151 if( lt != NULL ) 152 { 153 memcpy( tm_buf, lt, sizeof( struct tm ) ); 154 } 155 156 #if defined(MBEDTLS_THREADING_C) 157 if( mbedtls_mutex_unlock( &mbedtls_threading_gmtime_mutex ) != 0 ) 158 return( NULL ); 159 #endif /* MBEDTLS_THREADING_C */ 160 161 return( ( lt == NULL ) ? NULL : tm_buf ); 162 #endif /* _WIN32 && !EFIX64 && !EFI32 */ 163 } 164 #endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */ 165