[398] | 1 | /*
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| 2 | * Common and shared functions used by multiple modules in the Mbed TLS
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| 3 | * library.
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| 4 | *
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| 5 | * Copyright (C) 2018, Arm Limited, All Rights Reserved
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| 6 | * SPDX-License-Identifier: Apache-2.0
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| 7 | *
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| 8 | * Licensed under the Apache License, Version 2.0 (the "License"); you may
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| 9 | * not use this file except in compliance with the License.
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| 10 | * You may obtain a copy of the License at
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| 11 | *
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| 12 | * http://www.apache.org/licenses/LICENSE-2.0
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| 13 | *
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| 14 | * Unless required by applicable law or agreed to in writing, software
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| 15 | * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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| 16 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 17 | * See the License for the specific language governing permissions and
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| 18 | * limitations under the License.
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| 19 | *
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| 20 | * This file is part of Mbed TLS (https://tls.mbed.org)
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| 21 | */
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| 22 |
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| 23 | /*
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| 24 | * Ensure gmtime_r is available even with -std=c99; must be defined before
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| 25 | * config.h, which pulls in glibc's features.h. Harmless on other platforms.
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| 26 | */
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| 27 | #if !defined(_POSIX_C_SOURCE)
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| 28 | #define _POSIX_C_SOURCE 200112L
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| 29 | #endif
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| 30 |
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| 31 | #if !defined(MBEDTLS_CONFIG_FILE)
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| 32 | #include "mbedtls/config.h"
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| 33 | #else
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| 34 | #include MBEDTLS_CONFIG_FILE
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| 35 | #endif
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| 36 |
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| 37 | #include "mbedtls/platform_util.h"
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| 38 | #include "mbedtls/platform.h"
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| 39 | #include "mbedtls/threading.h"
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| 40 |
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| 41 | #include <stddef.h>
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| 42 | #include <string.h>
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| 43 |
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| 44 | #if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT)
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| 45 | /*
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| 46 | * This implementation should never be optimized out by the compiler
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| 47 | *
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| 48 | * This implementation for mbedtls_platform_zeroize() was inspired from Colin
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| 49 | * Percival's blog article at:
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| 50 | *
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| 51 | * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
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| 52 | *
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| 53 | * It uses a volatile function pointer to the standard memset(). Because the
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| 54 | * pointer is volatile the compiler expects it to change at
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| 55 | * any time and will not optimize out the call that could potentially perform
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| 56 | * other operations on the input buffer instead of just setting it to 0.
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| 57 | * Nevertheless, as pointed out by davidtgoldblatt on Hacker News
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| 58 | * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for
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| 59 | * details), optimizations of the following form are still possible:
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| 60 | *
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| 61 | * if( memset_func != memset )
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| 62 | * memset_func( buf, 0, len );
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| 63 | *
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| 64 | * Note that it is extremely difficult to guarantee that
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| 65 | * mbedtls_platform_zeroize() will not be optimized out by aggressive compilers
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| 66 | * in a portable way. For this reason, Mbed TLS also provides the configuration
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| 67 | * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
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| 68 | * mbedtls_platform_zeroize() to use a suitable implementation for their
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| 69 | * platform and needs.
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| 70 | */
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| 71 | static void * (* const volatile memset_func)( void *, int, size_t ) = memset;
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| 72 |
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| 73 | void mbedtls_platform_zeroize( void *buf, size_t len )
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| 74 | {
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| 75 | memset_func( buf, 0, len );
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| 76 | }
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| 77 | #endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */
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| 78 |
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| 79 | #if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
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| 80 | #include <time.h>
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| 81 | #if !defined(_WIN32) && (defined(unix) || \
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| 82 | defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
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| 83 | defined(__MACH__)))
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| 84 | #include <unistd.h>
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| 85 | #endif /* !_WIN32 && (unix || __unix || __unix__ ||
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| 86 | * (__APPLE__ && __MACH__)) */
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| 87 |
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| 88 | #if !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \
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| 89 | ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \
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| 90 | _POSIX_THREAD_SAFE_FUNCTIONS >= 20112L ) )
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| 91 | /*
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| 92 | * This is a convenience shorthand macro to avoid checking the long
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| 93 | * preprocessor conditions above. Ideally, we could expose this macro in
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| 94 | * platform_util.h and simply use it in platform_util.c, threading.c and
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| 95 | * threading.h. However, this macro is not part of the Mbed TLS public API, so
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| 96 | * we keep it private by only defining it in this file
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| 97 | */
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| 98 | #if ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) )
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| 99 | #define PLATFORM_UTIL_USE_GMTIME
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| 100 | #endif /* ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) */
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| 101 |
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| 102 | #endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \
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| 103 | ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \
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| 104 | _POSIX_THREAD_SAFE_FUNCTIONS >= 20112L ) ) */
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| 105 |
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| 106 | struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt,
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| 107 | struct tm *tm_buf )
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| 108 | {
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| 109 | #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
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| 110 | return( ( gmtime_s( tm_buf, tt ) == 0 ) ? tm_buf : NULL );
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| 111 | #elif !defined(PLATFORM_UTIL_USE_GMTIME)
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| 112 | return( gmtime_r( tt, tm_buf ) );
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| 113 | #else
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| 114 | struct tm *lt;
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| 115 |
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| 116 | #if defined(MBEDTLS_THREADING_C)
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| 117 | if( mbedtls_mutex_lock( &mbedtls_threading_gmtime_mutex ) != 0 )
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| 118 | return( NULL );
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| 119 | #endif /* MBEDTLS_THREADING_C */
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| 120 |
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| 121 | lt = gmtime( tt );
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| 122 |
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| 123 | if( lt != NULL )
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| 124 | {
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| 125 | memcpy( tm_buf, lt, sizeof( struct tm ) );
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| 126 | }
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| 127 |
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| 128 | #if defined(MBEDTLS_THREADING_C)
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| 129 | if( mbedtls_mutex_unlock( &mbedtls_threading_gmtime_mutex ) != 0 )
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| 130 | return( NULL );
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| 131 | #endif /* MBEDTLS_THREADING_C */
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| 132 |
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| 133 | return( ( lt == NULL ) ? NULL : tm_buf );
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| 134 | #endif /* _WIN32 && !EFIX64 && !EFI32 */
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| 135 | }
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| 136 | #endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */
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