208 lines
8.2 KiB
C
208 lines
8.2 KiB
C
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/**
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* \file platform_util.h
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*
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* \brief Common and shared functions used by multiple modules in the Mbed TLS
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* library.
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*/
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/*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef MBEDTLS_PLATFORM_UTIL_H
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#define MBEDTLS_PLATFORM_UTIL_H
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#include "mbedtls/build_info.h"
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#include <stddef.h>
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#if defined(MBEDTLS_HAVE_TIME_DATE)
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#include "mbedtls/platform_time.h"
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#include <time.h>
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#endif /* MBEDTLS_HAVE_TIME_DATE */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Internal macros meant to be called only from within the library. */
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#define MBEDTLS_INTERNAL_VALIDATE_RET(cond, ret) do { } while (0)
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#define MBEDTLS_INTERNAL_VALIDATE(cond) do { } while (0)
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/* Internal helper macros for deprecating API constants. */
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#if !defined(MBEDTLS_DEPRECATED_REMOVED)
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#if defined(MBEDTLS_DEPRECATED_WARNING)
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#define MBEDTLS_DEPRECATED __attribute__((deprecated))
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MBEDTLS_DEPRECATED typedef char const *mbedtls_deprecated_string_constant_t;
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#define MBEDTLS_DEPRECATED_STRING_CONSTANT(VAL) \
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((mbedtls_deprecated_string_constant_t) (VAL))
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MBEDTLS_DEPRECATED typedef int mbedtls_deprecated_numeric_constant_t;
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#define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT(VAL) \
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((mbedtls_deprecated_numeric_constant_t) (VAL))
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#else /* MBEDTLS_DEPRECATED_WARNING */
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#define MBEDTLS_DEPRECATED
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#define MBEDTLS_DEPRECATED_STRING_CONSTANT(VAL) VAL
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#define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT(VAL) VAL
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#endif /* MBEDTLS_DEPRECATED_WARNING */
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#endif /* MBEDTLS_DEPRECATED_REMOVED */
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/* Implementation of the check-return facility.
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* See the user documentation in mbedtls_config.h.
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*
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* Do not use this macro directly to annotate function: instead,
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* use one of MBEDTLS_CHECK_RETURN_CRITICAL or MBEDTLS_CHECK_RETURN_TYPICAL
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* depending on how important it is to check the return value.
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*/
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#if !defined(MBEDTLS_CHECK_RETURN)
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#if defined(__GNUC__)
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#define MBEDTLS_CHECK_RETURN __attribute__((__warn_unused_result__))
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#elif defined(_MSC_VER) && _MSC_VER >= 1700
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#include <sal.h>
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#define MBEDTLS_CHECK_RETURN _Check_return_
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#else
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#define MBEDTLS_CHECK_RETURN
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#endif
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#endif
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/** Critical-failure function
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*
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* This macro appearing at the beginning of the declaration of a function
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* indicates that its return value should be checked in all applications.
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* Omitting the check is very likely to indicate a bug in the application
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* and will result in a compile-time warning if #MBEDTLS_CHECK_RETURN
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* is implemented for the compiler in use.
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*
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* \note The use of this macro is a work in progress.
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* This macro may be added to more functions in the future.
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* Such an extension is not considered an API break, provided that
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* there are near-unavoidable circumstances under which the function
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* can fail. For example, signature/MAC/AEAD verification functions,
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* and functions that require a random generator, are considered
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* return-check-critical.
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*/
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#define MBEDTLS_CHECK_RETURN_CRITICAL MBEDTLS_CHECK_RETURN
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/** Ordinary-failure function
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*
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* This macro appearing at the beginning of the declaration of a function
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* indicates that its return value should be generally be checked in portable
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* applications. Omitting the check will result in a compile-time warning if
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* #MBEDTLS_CHECK_RETURN is implemented for the compiler in use and
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* #MBEDTLS_CHECK_RETURN_WARNING is enabled in the compile-time configuration.
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*
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* You can use #MBEDTLS_IGNORE_RETURN to explicitly ignore the return value
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* of a function that is annotated with #MBEDTLS_CHECK_RETURN.
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*
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* \note The use of this macro is a work in progress.
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* This macro will be added to more functions in the future.
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* Eventually this should appear before most functions returning
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* an error code (as \c int in the \c mbedtls_xxx API or
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* as ::psa_status_t in the \c psa_xxx API).
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*/
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#if defined(MBEDTLS_CHECK_RETURN_WARNING)
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#define MBEDTLS_CHECK_RETURN_TYPICAL MBEDTLS_CHECK_RETURN
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#else
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#define MBEDTLS_CHECK_RETURN_TYPICAL
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#endif
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/** Benign-failure function
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*
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* This macro appearing at the beginning of the declaration of a function
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* indicates that it is rarely useful to check its return value.
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*
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* This macro has an empty expansion. It exists for documentation purposes:
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* a #MBEDTLS_CHECK_RETURN_OPTIONAL annotation indicates that the function
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* has been analyzed for return-check usefulness, whereas the lack of
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* an annotation indicates that the function has not been analyzed and its
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* return-check usefulness is unknown.
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*/
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#define MBEDTLS_CHECK_RETURN_OPTIONAL
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/** \def MBEDTLS_IGNORE_RETURN
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*
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* Call this macro with one argument, a function call, to suppress a warning
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* from #MBEDTLS_CHECK_RETURN due to that function call.
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*/
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#if !defined(MBEDTLS_IGNORE_RETURN)
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/* GCC doesn't silence the warning with just (void)(result).
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* (void)!(result) is known to work up at least up to GCC 10, as well
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* as with Clang and MSVC.
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*
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* https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Non_002dbugs.html
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* https://stackoverflow.com/questions/40576003/ignoring-warning-wunused-result
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* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425#c34
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*/
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#define MBEDTLS_IGNORE_RETURN(result) ((void) !(result))
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#endif
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/**
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* \brief Securely zeroize a buffer
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*
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* The function is meant to wipe the data contained in a buffer so
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* that it can no longer be recovered even if the program memory
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* is later compromised. Call this function on sensitive data
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* stored on the stack before returning from a function, and on
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* sensitive data stored on the heap before freeing the heap
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* object.
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*
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* It is extremely difficult to guarantee that calls to
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* mbedtls_platform_zeroize() are not removed by aggressive
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* compiler optimizations in a portable way. For this reason, Mbed
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* TLS provides the configuration option
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* MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
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* mbedtls_platform_zeroize() to use a suitable implementation for
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* their platform and needs
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*
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* \param buf Buffer to be zeroized
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* \param len Length of the buffer in bytes
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*
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*/
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void mbedtls_platform_zeroize(void *buf, size_t len);
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#if defined(MBEDTLS_HAVE_TIME_DATE)
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/**
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* \brief Platform-specific implementation of gmtime_r()
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*
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* The function is a thread-safe abstraction that behaves
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* similarly to the gmtime_r() function from Unix/POSIX.
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*
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* Mbed TLS will try to identify the underlying platform and
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* make use of an appropriate underlying implementation (e.g.
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* gmtime_r() for POSIX and gmtime_s() for Windows). If this is
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* not possible, then gmtime() will be used. In this case, calls
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* from the library to gmtime() will be guarded by the mutex
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* mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is
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* enabled. It is recommended that calls from outside the library
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* are also guarded by this mutex.
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*
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* If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will
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* unconditionally use the alternative implementation for
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* mbedtls_platform_gmtime_r() supplied by the user at compile time.
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*
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* \param tt Pointer to an object containing time (in seconds) since the
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* epoch to be converted
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* \param tm_buf Pointer to an object where the results will be stored
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*
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* \return Pointer to an object of type struct tm on success, otherwise
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* NULL
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*/
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struct tm *mbedtls_platform_gmtime_r(const mbedtls_time_t *tt,
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struct tm *tm_buf);
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#endif /* MBEDTLS_HAVE_TIME_DATE */
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#ifdef __cplusplus
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}
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#endif
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#endif /* MBEDTLS_PLATFORM_UTIL_H */
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