/** * \file platform_util.h * * \brief Common and shared functions used by multiple modules in the Mbed TLS * library. */ /* * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */ #ifndef MBEDTLS_PLATFORM_UTIL_H #define MBEDTLS_PLATFORM_UTIL_H #include "mbedtls/build_info.h" #include #if defined(MBEDTLS_HAVE_TIME_DATE) #include "mbedtls/platform_time.h" #include #endif /* MBEDTLS_HAVE_TIME_DATE */ #ifdef __cplusplus extern "C" { #endif /* Internal helper macros for deprecating API constants. */ #if !defined(MBEDTLS_DEPRECATED_REMOVED) #if defined(MBEDTLS_DEPRECATED_WARNING) #define MBEDTLS_DEPRECATED __attribute__((deprecated)) MBEDTLS_DEPRECATED typedef char const *mbedtls_deprecated_string_constant_t; #define MBEDTLS_DEPRECATED_STRING_CONSTANT(VAL) \ ((mbedtls_deprecated_string_constant_t) (VAL)) MBEDTLS_DEPRECATED typedef int mbedtls_deprecated_numeric_constant_t; #define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT(VAL) \ ((mbedtls_deprecated_numeric_constant_t) (VAL)) #else /* MBEDTLS_DEPRECATED_WARNING */ #define MBEDTLS_DEPRECATED #define MBEDTLS_DEPRECATED_STRING_CONSTANT(VAL) VAL #define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT(VAL) VAL #endif /* MBEDTLS_DEPRECATED_WARNING */ #endif /* MBEDTLS_DEPRECATED_REMOVED */ /* Implementation of the check-return facility. * See the user documentation in mbedtls_config.h. * * Do not use this macro directly to annotate function: instead, * use one of MBEDTLS_CHECK_RETURN_CRITICAL or MBEDTLS_CHECK_RETURN_TYPICAL * depending on how important it is to check the return value. */ #if !defined(MBEDTLS_CHECK_RETURN) #if defined(__GNUC__) #define MBEDTLS_CHECK_RETURN __attribute__((__warn_unused_result__)) #elif defined(_MSC_VER) && _MSC_VER >= 1700 #include #define MBEDTLS_CHECK_RETURN _Check_return_ #else #define MBEDTLS_CHECK_RETURN #endif #endif /** Critical-failure function * * This macro appearing at the beginning of the declaration of a function * indicates that its return value should be checked in all applications. * Omitting the check is very likely to indicate a bug in the application * and will result in a compile-time warning if #MBEDTLS_CHECK_RETURN * is implemented for the compiler in use. * * \note The use of this macro is a work in progress. * This macro may be added to more functions in the future. * Such an extension is not considered an API break, provided that * there are near-unavoidable circumstances under which the function * can fail. For example, signature/MAC/AEAD verification functions, * and functions that require a random generator, are considered * return-check-critical. */ #define MBEDTLS_CHECK_RETURN_CRITICAL MBEDTLS_CHECK_RETURN /** Ordinary-failure function * * This macro appearing at the beginning of the declaration of a function * indicates that its return value should be generally be checked in portable * applications. Omitting the check will result in a compile-time warning if * #MBEDTLS_CHECK_RETURN is implemented for the compiler in use and * #MBEDTLS_CHECK_RETURN_WARNING is enabled in the compile-time configuration. * * You can use #MBEDTLS_IGNORE_RETURN to explicitly ignore the return value * of a function that is annotated with #MBEDTLS_CHECK_RETURN. * * \note The use of this macro is a work in progress. * This macro will be added to more functions in the future. * Eventually this should appear before most functions returning * an error code (as \c int in the \c mbedtls_xxx API or * as ::psa_status_t in the \c psa_xxx API). */ #if defined(MBEDTLS_CHECK_RETURN_WARNING) #define MBEDTLS_CHECK_RETURN_TYPICAL MBEDTLS_CHECK_RETURN #else #define MBEDTLS_CHECK_RETURN_TYPICAL #endif /** Benign-failure function * * This macro appearing at the beginning of the declaration of a function * indicates that it is rarely useful to check its return value. * * This macro has an empty expansion. It exists for documentation purposes: * a #MBEDTLS_CHECK_RETURN_OPTIONAL annotation indicates that the function * has been analyzed for return-check usefulness, whereas the lack of * an annotation indicates that the function has not been analyzed and its * return-check usefulness is unknown. */ #define MBEDTLS_CHECK_RETURN_OPTIONAL /** \def MBEDTLS_IGNORE_RETURN * * Call this macro with one argument, a function call, to suppress a warning * from #MBEDTLS_CHECK_RETURN due to that function call. */ #if !defined(MBEDTLS_IGNORE_RETURN) /* GCC doesn't silence the warning with just (void)(result). * (void)!(result) is known to work up at least up to GCC 10, as well * as with Clang and MSVC. * * https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Non_002dbugs.html * https://stackoverflow.com/questions/40576003/ignoring-warning-wunused-result * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425#c34 */ #define MBEDTLS_IGNORE_RETURN(result) ((void) !(result)) #endif /* If the following macro is defined, the library is being built by the test * framework, and the framework is going to provide a replacement * mbedtls_platform_zeroize() using a preprocessor macro, so the function * declaration should be omitted. */ #if !defined(MBEDTLS_TEST_DEFINES_ZEROIZE) //no-check-names /** * \brief Securely zeroize a buffer * * The function is meant to wipe the data contained in a buffer so * that it can no longer be recovered even if the program memory * is later compromised. Call this function on sensitive data * stored on the stack before returning from a function, and on * sensitive data stored on the heap before freeing the heap * object. * * It is extremely difficult to guarantee that calls to * mbedtls_platform_zeroize() are not removed by aggressive * compiler optimizations in a portable way. For this reason, Mbed * TLS provides the configuration option * MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure * mbedtls_platform_zeroize() to use a suitable implementation for * their platform and needs * * \param buf Buffer to be zeroized * \param len Length of the buffer in bytes * */ void mbedtls_platform_zeroize(void *buf, size_t len); #endif #if defined(MBEDTLS_HAVE_TIME_DATE) /** * \brief Platform-specific implementation of gmtime_r() * * The function is a thread-safe abstraction that behaves * similarly to the gmtime_r() function from Unix/POSIX. * * Mbed TLS will try to identify the underlying platform and * make use of an appropriate underlying implementation (e.g. * gmtime_r() for POSIX and gmtime_s() for Windows). If this is * not possible, then gmtime() will be used. In this case, calls * from the library to gmtime() will be guarded by the mutex * mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is * enabled. It is recommended that calls from outside the library * are also guarded by this mutex. * * If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will * unconditionally use the alternative implementation for * mbedtls_platform_gmtime_r() supplied by the user at compile time. * * \param tt Pointer to an object containing time (in seconds) since the * epoch to be converted * \param tm_buf Pointer to an object where the results will be stored * * \return Pointer to an object of type struct tm on success, otherwise * NULL */ struct tm *mbedtls_platform_gmtime_r(const mbedtls_time_t *tt, struct tm *tm_buf); #endif /* MBEDTLS_HAVE_TIME_DATE */ #ifdef __cplusplus } #endif #endif /* MBEDTLS_PLATFORM_UTIL_H */