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
7 *
8 * Licensed under the Apache License, Version 2.0 (the "License"); you may
9 * not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
16 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20
21 /*
22 * Ensure gmtime_r is available even with -std=c99; must be defined before
23 * mbedtls_config.h, which pulls in glibc's features.h. Harmless on other platforms.
24 */
25 #if !defined(_POSIX_C_SOURCE)
26 #define _POSIX_C_SOURCE 200112L
27 #endif
28
29 #include "common.h"
30
31 #include "mbedtls/platform_util.h"
32 #include "mbedtls/platform.h"
33 #include "mbedtls/threading.h"
34
35 #include <stddef.h>
36 #include <string.h>
37
38 #if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT)
39 /*
40 * This implementation should never be optimized out by the compiler
41 *
42 * This implementation for mbedtls_platform_zeroize() was inspired from Colin
43 * Percival's blog article at:
44 *
45 * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
46 *
47 * It uses a volatile function pointer to the standard memset(). Because the
48 * pointer is volatile the compiler expects it to change at
49 * any time and will not optimize out the call that could potentially perform
50 * other operations on the input buffer instead of just setting it to 0.
51 * Nevertheless, as pointed out by davidtgoldblatt on Hacker News
52 * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for
53 * details), optimizations of the following form are still possible:
54 *
55 * if( memset_func != memset )
56 * memset_func( buf, 0, len );
57 *
58 * Note that it is extremely difficult to guarantee that
59 * mbedtls_platform_zeroize() will not be optimized out by aggressive compilers
60 * in a portable way. For this reason, Mbed TLS also provides the configuration
61 * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
62 * mbedtls_platform_zeroize() to use a suitable implementation for their
63 * platform and needs.
64 */
65 void * (* const volatile memset_func)( void *, int, size_t ) = memset;
66
mbedtls_platform_zeroize(void * buf,size_t len)67 void mbedtls_platform_zeroize( void *buf, size_t len )
68 {
69 MBEDTLS_INTERNAL_VALIDATE( len == 0 || buf != NULL );
70
71 if( len > 0 )
72 memset_func( buf, 0, len );
73 }
74 #endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */
75
76 #if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
77 #define __STDC_WANT_LIB_EXT1__ 1 /* Ask for the C11 gmtime_s() if it's available */
78 #include <time.h>
79 #if !defined(_WIN32) && (defined(unix) || \
80 defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
81 defined(__MACH__)))
82 #include <unistd.h>
83 #endif /* !_WIN32 && (unix || __unix || __unix__ ||
84 * (__APPLE__ && __MACH__)) */
85
86 #if !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \
87 ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \
88 _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) )
89 /*
90 * This is a convenience shorthand macro to avoid checking the long
91 * preprocessor conditions above. Ideally, we could expose this macro in
92 * platform_util.h and simply use it in platform_util.c, threading.c and
93 * threading.h. However, this macro is not part of the Mbed TLS public API, so
94 * we keep it private by only defining it in this file
95 */
96 #if ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) || \
97 ( defined(__MINGW32__) && !defined(__MINGW64_VERSION_MAJOR) )
98 #define PLATFORM_UTIL_USE_GMTIME
99 #endif
100
101 #endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \
102 ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \
103 _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */
104
mbedtls_platform_gmtime_r(const mbedtls_time_t * tt,struct tm * tm_buf)105 struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt,
106 struct tm *tm_buf )
107 {
108 #if defined(_WIN32) && !defined(PLATFORM_UTIL_USE_GMTIME)
109 #if defined(__STDC_LIB_EXT1__)
110 return( ( gmtime_s( tt, tm_buf ) == 0 ) ? NULL : tm_buf );
111 #else
112 /* MSVC and mingw64 argument order and return value are inconsistent with the C11 standard */
113 return( ( gmtime_s( tm_buf, tt ) == 0 ) ? tm_buf : NULL );
114 #endif
115 #elif !defined(PLATFORM_UTIL_USE_GMTIME)
116 return( gmtime_r( tt, tm_buf ) );
117 #else
118 struct tm *lt;
119
120 #if defined(MBEDTLS_THREADING_C)
121 if( mbedtls_mutex_lock( &mbedtls_threading_gmtime_mutex ) != 0 )
122 return( NULL );
123 #endif /* MBEDTLS_THREADING_C */
124
125 lt = gmtime( tt );
126
127 if( lt != NULL )
128 {
129 memcpy( tm_buf, lt, sizeof( struct tm ) );
130 }
131
132 #if defined(MBEDTLS_THREADING_C)
133 if( mbedtls_mutex_unlock( &mbedtls_threading_gmtime_mutex ) != 0 )
134 return( NULL );
135 #endif /* MBEDTLS_THREADING_C */
136
137 return( ( lt == NULL ) ? NULL : tm_buf );
138 #endif /* _WIN32 && !EFIX64 && !EFI32 */
139 }
140 #endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */
141
142 #if defined(MBEDTLS_TEST_HOOKS)
143 void (*mbedtls_test_hook_test_fail)( const char *, int, const char *);
144 #endif /* MBEDTLS_TEST_HOOKS */
145
146
