/* * Common and shared functions used by multiple modules in the Mbed TLS * library. * * 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. */ /* * Ensure gmtime_r is available even with -std=c99; must be defined before * config.h, which pulls in glibc's features.h. Harmless on other platforms. */ #if !defined(_POSIX_C_SOURCE) #define _POSIX_C_SOURCE 200112L #endif #include "common.h" #include "mbedtls/platform_util.h" #include "mbedtls/platform.h" #include "mbedtls/threading.h" #include <stddef.h> #include <string.h> #if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT) /* * This implementation should never be optimized out by the compiler * * This implementation for mbedtls_platform_zeroize() was inspired from Colin * Percival's blog article at: * * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html * * It uses a volatile function pointer to the standard memset(). Because the * pointer is volatile the compiler expects it to change at * any time and will not optimize out the call that could potentially perform * other operations on the input buffer instead of just setting it to 0. * Nevertheless, as pointed out by davidtgoldblatt on Hacker News * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for * details), optimizations of the following form are still possible: * * if( memset_func != memset ) * memset_func( buf, 0, len ); * * Note that it is extremely difficult to guarantee that * mbedtls_platform_zeroize() will not be optimized out by aggressive compilers * in a portable way. For this reason, Mbed TLS also provides the configuration * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure * mbedtls_platform_zeroize() to use a suitable implementation for their * platform and needs. */ static void * (* const volatile memset_func)( void *, int, size_t ) = memset; void mbedtls_platform_zeroize( void *buf, size_t len ) { MBEDTLS_INTERNAL_VALIDATE( len == 0 || buf != NULL ); if( len > 0 ) memset_func( buf, 0, len ); } #endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */ #if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT) #include <time.h> #if !defined(_WIN32) && (defined(unix) || \ defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \ defined(__MACH__))) #include <unistd.h> #endif /* !_WIN32 && (unix || __unix || __unix__ || * (__APPLE__ && __MACH__)) */ #if !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \ ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \ _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) /* * This is a convenience shorthand macro to avoid checking the long * preprocessor conditions above. Ideally, we could expose this macro in * platform_util.h and simply use it in platform_util.c, threading.c and * threading.h. However, this macro is not part of the Mbed TLS public API, so * we keep it private by only defining it in this file */ #if ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) #define PLATFORM_UTIL_USE_GMTIME #endif /* ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) */ #endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \ ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \ _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */ struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt, struct tm *tm_buf ) { #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) return( ( gmtime_s( tm_buf, tt ) == 0 ) ? tm_buf : NULL ); #elif !defined(PLATFORM_UTIL_USE_GMTIME) return( gmtime_r( tt, tm_buf ) ); #else struct tm *lt; #if defined(MBEDTLS_THREADING_C) if( mbedtls_mutex_lock( &mbedtls_threading_gmtime_mutex ) != 0 ) return( NULL ); #endif /* MBEDTLS_THREADING_C */ lt = gmtime( tt ); if( lt != NULL ) { memcpy( tm_buf, lt, sizeof( struct tm ) ); } #if defined(MBEDTLS_THREADING_C) if( mbedtls_mutex_unlock( &mbedtls_threading_gmtime_mutex ) != 0 ) return( NULL ); #endif /* MBEDTLS_THREADING_C */ return( ( lt == NULL ) ? NULL : tm_buf ); #endif /* _WIN32 && !EFIX64 && !EFI32 */ } #endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */