common/mbedtls/platform_util.h

   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 The Mbed TLS Contributors
   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 #ifndef MBEDTLS_PLATFORM_UTIL_H
  24 #define MBEDTLS_PLATFORM_UTIL_H
  25
  26 #if !defined(MBEDTLS_CONFIG_FILE)
  27 #include "mbedtls/config.h"
  28 #else
  29 #include MBEDTLS_CONFIG_FILE
  30 #endif
  31
  32 #include <stddef.h>
  33 #if defined(MBEDTLS_HAVE_TIME_DATE)
  34 #include "mbedtls/platform_time.h"
  35 #include <time.h>
  36 #endif /* MBEDTLS_HAVE_TIME_DATE */
  37
  38 #ifdef __cplusplus
  39 extern "C" {
  40 #endif
  41
  42 #if defined(MBEDTLS_CHECK_PARAMS)
  43
  44 #if defined(MBEDTLS_CHECK_PARAMS_ASSERT)
  45 /* Allow the user to define MBEDTLS_PARAM_FAILED to something like assert
  46  * (which is what our config.h suggests). */
  47 #include <assert.h>
  48 #endif /* MBEDTLS_CHECK_PARAMS_ASSERT */
  49
  50 #if defined(MBEDTLS_PARAM_FAILED)
  51 /** An alternative definition of MBEDTLS_PARAM_FAILED has been set in config.h.
  52  *
  53  * This flag can be used to check whether it is safe to assume that
  54  * MBEDTLS_PARAM_FAILED() will expand to a call to mbedtls_param_failed().
  55  */
  56 #define MBEDTLS_PARAM_FAILED_ALT
  57
  58 #elif defined(MBEDTLS_CHECK_PARAMS_ASSERT)
  59 #define MBEDTLS_PARAM_FAILED( cond ) assert( cond )
  60 #define MBEDTLS_PARAM_FAILED_ALT
  61
  62 #else /* MBEDTLS_PARAM_FAILED */
  63 #define MBEDTLS_PARAM_FAILED( cond ) \
  64     mbedtls_param_failed( #cond, __FILE__, __LINE__ )
  65
  66 /**
  67  * \brief       User supplied callback function for parameter validation failure.
  68  *              See #MBEDTLS_CHECK_PARAMS for context.
  69  *
  70  *              This function will be called unless an alternative treatement
  71  *              is defined through the #MBEDTLS_PARAM_FAILED macro.
  72  *
  73  *              This function can return, and the operation will be aborted, or
  74  *              alternatively, through use of setjmp()/longjmp() can resume
  75  *              execution in the application code.
  76  *
  77  * \param failure_condition The assertion that didn't hold.
  78  * \param file  The file where the assertion failed.
  79  * \param line  The line in the file where the assertion failed.
  80  */
  81 void mbedtls_param_failed(const char *failure_condition,
  82                           const char *file,
  83                           int line);
  84 #endif /* MBEDTLS_PARAM_FAILED */
  85
  86 /* Internal macro meant to be called only from within the library. */
  87 #define MBEDTLS_INTERNAL_VALIDATE_RET( cond, ret )  \
  88     do {                                            \
  89         if( !(cond) )                               \
  90         {                                           \
  91             MBEDTLS_PARAM_FAILED( cond );           \
  92             return( ret );                          \
  93         }                                           \
  94     } while( 0 )
  95
  96 /* Internal macro meant to be called only from within the library. */
  97 #define MBEDTLS_INTERNAL_VALIDATE( cond )           \
  98     do {                                            \
  99         if( !(cond) )                               \
 100         {                                           \
 101             MBEDTLS_PARAM_FAILED( cond );           \
 102             return;                                 \
 103         }                                           \
 104     } while( 0 )
 105
 106 #else /* MBEDTLS_CHECK_PARAMS */
 107
 108 /* Internal macros meant to be called only from within the library. */
 109 #define MBEDTLS_INTERNAL_VALIDATE_RET( cond, ret )  do { } while( 0 )
 110 #define MBEDTLS_INTERNAL_VALIDATE( cond )           do { } while( 0 )
 111
 112 #endif /* MBEDTLS_CHECK_PARAMS */
 113
 114 /* Internal helper macros for deprecating API constants. */
 115 #if !defined(MBEDTLS_DEPRECATED_REMOVED)
 116 #if defined(MBEDTLS_DEPRECATED_WARNING)
 117 /* Deliberately don't (yet) export MBEDTLS_DEPRECATED here
 118  * to avoid conflict with other headers which define and use
 119  * it, too. We might want to move all these definitions here at
 120  * some point for uniformity. */
 121 #define MBEDTLS_DEPRECATED __attribute__((deprecated))
 122 MBEDTLS_DEPRECATED typedef char const *mbedtls_deprecated_string_constant_t;
 123 #define MBEDTLS_DEPRECATED_STRING_CONSTANT( VAL )       \
 124     ( (mbedtls_deprecated_string_constant_t) ( VAL ) )
 125 MBEDTLS_DEPRECATED typedef int mbedtls_deprecated_numeric_constant_t;
 126 #define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT( VAL )       \
 127     ( (mbedtls_deprecated_numeric_constant_t) ( VAL ) )
 128 #undef MBEDTLS_DEPRECATED
 129 #else /* MBEDTLS_DEPRECATED_WARNING */
 130 #define MBEDTLS_DEPRECATED_STRING_CONSTANT( VAL ) VAL
 131 #define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT( VAL ) VAL
 132 #endif /* MBEDTLS_DEPRECATED_WARNING */
 133 #endif /* MBEDTLS_DEPRECATED_REMOVED */
 134
 135 /**
 136  * \brief       Securely zeroize a buffer
 137  *
 138  *              The function is meant to wipe the data contained in a buffer so
 139  *              that it can no longer be recovered even if the program memory
 140  *              is later compromised. Call this function on sensitive data
 141  *              stored on the stack before returning from a function, and on
 142  *              sensitive data stored on the heap before freeing the heap
 143  *              object.
 144  *
 145  *              It is extremely difficult to guarantee that calls to
 146  *              mbedtls_platform_zeroize() are not removed by aggressive
 147  *              compiler optimizations in a portable way. For this reason, Mbed
 148  *              TLS provides the configuration option
 149  *              MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
 150  *              mbedtls_platform_zeroize() to use a suitable implementation for
 151  *              their platform and needs
 152  *
 153  * \param buf   Buffer to be zeroized
 154  * \param len   Length of the buffer in bytes
 155  *
 156  */
 157 void mbedtls_platform_zeroize(void *buf, size_t len);
 158
 159 #if defined(MBEDTLS_HAVE_TIME_DATE)
 160 /**
 161  * \brief      Platform-specific implementation of gmtime_r()
 162  *
 163  *             The function is a thread-safe abstraction that behaves
 164  *             similarly to the gmtime_r() function from Unix/POSIX.
 165  *
 166  *             Mbed TLS will try to identify the underlying platform and
 167  *             make use of an appropriate underlying implementation (e.g.
 168  *             gmtime_r() for POSIX and gmtime_s() for Windows). If this is
 169  *             not possible, then gmtime() will be used. In this case, calls
 170  *             from the library to gmtime() will be guarded by the mutex
 171  *             mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is
 172  *             enabled. It is recommended that calls from outside the library
 173  *             are also guarded by this mutex.
 174  *
 175  *             If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will
 176  *             unconditionally use the alternative implementation for
 177  *             mbedtls_platform_gmtime_r() supplied by the user at compile time.
 178  *
 179  * \param tt     Pointer to an object containing time (in seconds) since the
 180  *               epoch to be converted
 181  * \param tm_buf Pointer to an object where the results will be stored
 182  *
 183  * \return      Pointer to an object of type struct tm on success, otherwise
 184  *              NULL
 185  */
 186 struct tm *mbedtls_platform_gmtime_r(const mbedtls_time_t *tt,
 187                                      struct tm *tm_buf);
 188 #endif /* MBEDTLS_HAVE_TIME_DATE */
 189
 190 #ifdef __cplusplus
 191 }
 192 #endif
 193
 194 #endif /* MBEDTLS_PLATFORM_UTIL_H */