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 treatment 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 /* Implementation of the check-return facility. 136 * See the user documentation in config.h. 137 * 138 * Do not use this macro directly to annotate function: instead, 139 * use one of MBEDTLS_CHECK_RETURN_CRITICAL or MBEDTLS_CHECK_RETURN_TYPICAL 140 * depending on how important it is to check the return value. 141 */ 142 #if !defined(MBEDTLS_CHECK_RETURN) 143 #if defined(__GNUC__) 144 #define MBEDTLS_CHECK_RETURN __attribute__((__warn_unused_result__)) 145 #elif defined(_MSC_VER) && _MSC_VER >= 1700 146 #include <sal.h> 147 #define MBEDTLS_CHECK_RETURN _Check_return_ 148 #else 149 #define MBEDTLS_CHECK_RETURN 150 #endif 151 #endif 152 153 /** Critical-failure function 154 * 155 * This macro appearing at the beginning of the declaration of a function 156 * indicates that its return value should be checked in all applications. 157 * Omitting the check is very likely to indicate a bug in the application 158 * and will result in a compile-time warning if #MBEDTLS_CHECK_RETURN 159 * is implemented for the compiler in use. 160 * 161 * \note The use of this macro is a work in progress. 162 * This macro may be added to more functions in the future. 163 * Such an extension is not considered an API break, provided that 164 * there are near-unavoidable circumstances under which the function 165 * can fail. For example, signature/MAC/AEAD verification functions, 166 * and functions that require a random generator, are considered 167 * return-check-critical. 168 */ 169 #define MBEDTLS_CHECK_RETURN_CRITICAL MBEDTLS_CHECK_RETURN 170 171 /** Ordinary-failure function 172 * 173 * This macro appearing at the beginning of the declaration of a function 174 * indicates that its return value should be generally be checked in portable 175 * applications. Omitting the check will result in a compile-time warning if 176 * #MBEDTLS_CHECK_RETURN is implemented for the compiler in use and 177 * #MBEDTLS_CHECK_RETURN_WARNING is enabled in the compile-time configuration. 178 * 179 * You can use #MBEDTLS_IGNORE_RETURN to explicitly ignore the return value 180 * of a function that is annotated with #MBEDTLS_CHECK_RETURN. 181 * 182 * \note The use of this macro is a work in progress. 183 * This macro will be added to more functions in the future. 184 * Eventually this should appear before most functions returning 185 * an error code (as \c int in the \c mbedtls_xxx API or 186 * as ::psa_status_t in the \c psa_xxx API). 187 */ 188 #if defined(MBEDTLS_CHECK_RETURN_WARNING) 189 #define MBEDTLS_CHECK_RETURN_TYPICAL MBEDTLS_CHECK_RETURN 190 #else 191 #define MBEDTLS_CHECK_RETURN_TYPICAL 192 #endif 193 194 /** Benign-failure function 195 * 196 * This macro appearing at the beginning of the declaration of a function 197 * indicates that it is rarely useful to check its return value. 198 * 199 * This macro has an empty expansion. It exists for documentation purposes: 200 * a #MBEDTLS_CHECK_RETURN_OPTIONAL annotation indicates that the function 201 * has been analyzed for return-check usefulness, whereas the lack of 202 * an annotation indicates that the function has not been analyzed and its 203 * return-check usefulness is unknown. 204 */ 205 #define MBEDTLS_CHECK_RETURN_OPTIONAL 206 207 /** \def MBEDTLS_IGNORE_RETURN 208 * 209 * Call this macro with one argument, a function call, to suppress a warning 210 * from #MBEDTLS_CHECK_RETURN due to that function call. 211 */ 212 #if !defined(MBEDTLS_IGNORE_RETURN) 213 /* GCC doesn't silence the warning with just (void)(result). 214 * (void)!(result) is known to work up at least up to GCC 10, as well 215 * as with Clang and MSVC. 216 * 217 * https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Non_002dbugs.html 218 * https://stackoverflow.com/questions/40576003/ignoring-warning-wunused-result 219 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425#c34 220 */ 221 #define MBEDTLS_IGNORE_RETURN(result) ( (void) !( result ) ) 222 #endif 223 224 /** 225 * \brief Securely zeroize a buffer 226 * 227 * The function is meant to wipe the data contained in a buffer so 228 * that it can no longer be recovered even if the program memory 229 * is later compromised. Call this function on sensitive data 230 * stored on the stack before returning from a function, and on 231 * sensitive data stored on the heap before freeing the heap 232 * object. 233 * 234 * It is extremely difficult to guarantee that calls to 235 * mbedtls_platform_zeroize() are not removed by aggressive 236 * compiler optimizations in a portable way. For this reason, Mbed 237 * TLS provides the configuration option 238 * MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure 239 * mbedtls_platform_zeroize() to use a suitable implementation for 240 * their platform and needs 241 * 242 * \param buf Buffer to be zeroized 243 * \param len Length of the buffer in bytes 244 * 245 */ 246 void mbedtls_platform_zeroize( void *buf, size_t len ); 247 248 #if defined(MBEDTLS_HAVE_TIME_DATE) 249 /** 250 * \brief Platform-specific implementation of gmtime_r() 251 * 252 * The function is a thread-safe abstraction that behaves 253 * similarly to the gmtime_r() function from Unix/POSIX. 254 * 255 * Mbed TLS will try to identify the underlying platform and 256 * make use of an appropriate underlying implementation (e.g. 257 * gmtime_r() for POSIX and gmtime_s() for Windows). If this is 258 * not possible, then gmtime() will be used. In this case, calls 259 * from the library to gmtime() will be guarded by the mutex 260 * mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is 261 * enabled. It is recommended that calls from outside the library 262 * are also guarded by this mutex. 263 * 264 * If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will 265 * unconditionally use the alternative implementation for 266 * mbedtls_platform_gmtime_r() supplied by the user at compile time. 267 * 268 * \param tt Pointer to an object containing time (in seconds) since the 269 * epoch to be converted 270 * \param tm_buf Pointer to an object where the results will be stored 271 * 272 * \return Pointer to an object of type struct tm on success, otherwise 273 * NULL 274 */ 275 struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt, 276 struct tm *tm_buf ); 277 #endif /* MBEDTLS_HAVE_TIME_DATE */ 278 279 #ifdef __cplusplus 280 } 281 #endif 282 283 #endif /* MBEDTLS_PLATFORM_UTIL_H */ 284