1 /**
2  * \file platform_util.h
3  *
4  * \brief Common and shared functions used by multiple modules in the Mbed TLS
5  *        library.
6  */
7 /*
8  *  Copyright (C) 2018, Arm Limited, All Rights Reserved
9  *  SPDX-License-Identifier: Apache-2.0
10  *
11  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
12  *  not use this file except in compliance with the License.
13  *  You may obtain a copy of the License at
14  *
15  *  http://www.apache.org/licenses/LICENSE-2.0
16  *
17  *  Unless required by applicable law or agreed to in writing, software
18  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
19  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
20  *  See the License for the specific language governing permissions and
21  *  limitations under the License.
22  *
23  *  This file is part of Mbed TLS (https://tls.mbed.org)
24  */
25 #ifndef MBEDTLS_PLATFORM_UTIL_H
26 #define MBEDTLS_PLATFORM_UTIL_H
27 
28 #if !defined(MBEDTLS_CONFIG_FILE)
29 #include "mbedtls/config.h"
30 #else
31 #include MBEDTLS_CONFIG_FILE
32 #endif
33 
34 #include <stddef.h>
35 #if defined(MBEDTLS_HAVE_TIME_DATE)
36 #include "mbedtls/platform_time.h"
37 #include <time.h>
38 #endif /* MBEDTLS_HAVE_TIME_DATE */
39 
40 #ifdef __cplusplus
41 extern "C" {
42 #endif
43 
44 #if defined(MBEDTLS_CHECK_PARAMS)
45 
46 #if defined(MBEDTLS_PARAM_FAILED)
47 /** An alternative definition of MBEDTLS_PARAM_FAILED has been set in config.h.
48  *
49  * This flag can be used to check whether it is safe to assume that
50  * MBEDTLS_PARAM_FAILED() will expand to a call to mbedtls_param_failed().
51  */
52 #define MBEDTLS_PARAM_FAILED_ALT
53 #else /* MBEDTLS_PARAM_FAILED */
54 #define MBEDTLS_PARAM_FAILED( cond ) \
55     mbedtls_param_failed( #cond, __FILE__, __LINE__ )
56 
57 /**
58  * \brief       User supplied callback function for parameter validation failure.
59  *              See #MBEDTLS_CHECK_PARAMS for context.
60  *
61  *              This function will be called unless an alternative treatement
62  *              is defined through the #MBEDTLS_PARAM_FAILED macro.
63  *
64  *              This function can return, and the operation will be aborted, or
65  *              alternatively, through use of setjmp()/longjmp() can resume
66  *              execution in the application code.
67  *
68  * \param failure_condition The assertion that didn't hold.
69  * \param file  The file where the assertion failed.
70  * \param line  The line in the file where the assertion failed.
71  */
72 void mbedtls_param_failed( const char *failure_condition,
73                            const char *file,
74                            int line );
75 #endif /* MBEDTLS_PARAM_FAILED */
76 
77 /* Internal macro meant to be called only from within the library. */
78 #define MBEDTLS_INTERNAL_VALIDATE_RET( cond, ret )  \
79     do {                                            \
80         if( !(cond) )                               \
81         {                                           \
82             MBEDTLS_PARAM_FAILED( cond );           \
83             return( ret );                          \
84         }                                           \
85     } while( 0 )
86 
87 /* Internal macro meant to be called only from within the library. */
88 #define MBEDTLS_INTERNAL_VALIDATE( cond )           \
89     do {                                            \
90         if( !(cond) )                               \
91         {                                           \
92             MBEDTLS_PARAM_FAILED( cond );           \
93             return;                                 \
94         }                                           \
95     } while( 0 )
96 
97 #else /* MBEDTLS_CHECK_PARAMS */
98 
99 /* Internal macros meant to be called only from within the library. */
100 #define MBEDTLS_INTERNAL_VALIDATE_RET( cond, ret )  do { } while( 0 )
101 #define MBEDTLS_INTERNAL_VALIDATE( cond )           do { } while( 0 )
102 
103 #endif /* MBEDTLS_CHECK_PARAMS */
104 
105 /* Internal helper macros for deprecating API constants. */
106 #if !defined(MBEDTLS_DEPRECATED_REMOVED)
107 #if defined(MBEDTLS_DEPRECATED_WARNING)
108 /* Deliberately don't (yet) export MBEDTLS_DEPRECATED here
109  * to avoid conflict with other headers which define and use
110  * it, too. We might want to move all these definitions here at
111  * some point for uniformity. */
112 #define MBEDTLS_DEPRECATED __attribute__((deprecated))
113 MBEDTLS_DEPRECATED typedef char const * mbedtls_deprecated_string_constant_t;
114 #define MBEDTLS_DEPRECATED_STRING_CONSTANT( VAL )       \
115     ( (mbedtls_deprecated_string_constant_t) ( VAL ) )
116 MBEDTLS_DEPRECATED typedef int mbedtls_deprecated_numeric_constant_t;
117 #define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT( VAL )       \
118     ( (mbedtls_deprecated_numeric_constant_t) ( VAL ) )
119 #undef MBEDTLS_DEPRECATED
120 #else /* MBEDTLS_DEPRECATED_WARNING */
121 #define MBEDTLS_DEPRECATED_STRING_CONSTANT( VAL ) VAL
122 #define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT( VAL ) VAL
123 #endif /* MBEDTLS_DEPRECATED_WARNING */
124 #endif /* MBEDTLS_DEPRECATED_REMOVED */
125 
126 /**
127  * \brief       Securely zeroize a buffer
128  *
129  *              The function is meant to wipe the data contained in a buffer so
130  *              that it can no longer be recovered even if the program memory
131  *              is later compromised. Call this function on sensitive data
132  *              stored on the stack before returning from a function, and on
133  *              sensitive data stored on the heap before freeing the heap
134  *              object.
135  *
136  *              It is extremely difficult to guarantee that calls to
137  *              mbedtls_platform_zeroize() are not removed by aggressive
138  *              compiler optimizations in a portable way. For this reason, Mbed
139  *              TLS provides the configuration option
140  *              MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
141  *              mbedtls_platform_zeroize() to use a suitable implementation for
142  *              their platform and needs
143  *
144  * \param buf   Buffer to be zeroized
145  * \param len   Length of the buffer in bytes
146  *
147  */
148 void mbedtls_platform_zeroize( void *buf, size_t len );
149 
150 #if defined(MBEDTLS_HAVE_TIME_DATE)
151 /**
152  * \brief      Platform-specific implementation of gmtime_r()
153  *
154  *             The function is a thread-safe abstraction that behaves
155  *             similarly to the gmtime_r() function from Unix/POSIX.
156  *
157  *             Mbed TLS will try to identify the underlying platform and
158  *             make use of an appropriate underlying implementation (e.g.
159  *             gmtime_r() for POSIX and gmtime_s() for Windows). If this is
160  *             not possible, then gmtime() will be used. In this case, calls
161  *             from the library to gmtime() will be guarded by the mutex
162  *             mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is
163  *             enabled. It is recommended that calls from outside the library
164  *             are also guarded by this mutex.
165  *
166  *             If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will
167  *             unconditionally use the alternative implementation for
168  *             mbedtls_platform_gmtime_r() supplied by the user at compile time.
169  *
170  * \param tt     Pointer to an object containing time (in seconds) since the
171  *               epoch to be converted
172  * \param tm_buf Pointer to an object where the results will be stored
173  *
174  * \return      Pointer to an object of type struct tm on success, otherwise
175  *              NULL
176  */
177 struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt,
178                                       struct tm *tm_buf );
179 #endif /* MBEDTLS_HAVE_TIME_DATE */
180 
181 #ifdef __cplusplus
182 }
183 #endif
184 
185 #endif /* MBEDTLS_PLATFORM_UTIL_H */
186