ReactOS  0.4.15-dev-4927-gfe8f806
platform_util.c
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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 */
#define MBEDTLS_INTERNAL_VALIDATE(cond)
GLenum GLuint GLenum GLsizei const GLchar * buf
Definition: glext.h:7751
Common and shared functions used by multiple modules in the Mbed TLS library.
time_t mbedtls_time_t
Definition: platform_time.h:78
Threading abstraction layer.
static void *(*constvolatile memset_func)(void *, int, size_t)
Definition: platform_util.c:96
#define memcpy(s1, s2, n)
Definition: mkisofs.h:878
GLenum GLsizei len
Definition: glext.h:6722
Definition: time.h:68
#define NULL
Definition: types.h:112
_CRTIMP struct tm *__cdecl gmtime(const time_t *_Time)
Definition: time.h:415
void mbedtls_platform_zeroize(void *buf, size_t len)
Securely zeroize a buffer.
Definition: platform_util.c:98
#define memset(x, y, z)
Definition: compat.h:39