123 lines
4.2 KiB
C
123 lines
4.2 KiB
C
/*
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* 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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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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/*
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* Ensure gmtime_r is available even with -std=c99; must be defined before
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* config.h, which pulls in glibc's features.h. Harmless on other platforms.
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*/
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#if !defined(_POSIX_C_SOURCE)
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#define _POSIX_C_SOURCE 200112L
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#endif
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#include "common.h"
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#include "mbedtls/platform_util.h"
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#include "mbedtls/platform.h"
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#include "mbedtls/threading.h"
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#include <stddef.h>
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#include <string.h>
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#if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT)
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/*
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* This implementation should never be optimized out by the compiler
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*
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* This implementation for mbedtls_platform_zeroize() was inspired from Colin
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* Percival's blog article at:
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*
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* http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
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*
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* It uses a volatile function pointer to the standard memset(). Because the
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* pointer is volatile the compiler expects it to change at
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* any time and will not optimize out the call that could potentially perform
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* other operations on the input buffer instead of just setting it to 0.
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* Nevertheless, as pointed out by davidtgoldblatt on Hacker News
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* (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for
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* details), optimizations of the following form are still possible:
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*
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* if( memset_func != memset )
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* memset_func( buf, 0, len );
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*
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* Note that it is extremely difficult to guarantee that
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* mbedtls_platform_zeroize() will not be optimized out by aggressive compilers
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* in a portable way. For this reason, Mbed TLS also provides the configuration
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* option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
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* mbedtls_platform_zeroize() to use a suitable implementation for their
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* platform and needs.
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*/
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static void *(*const volatile memset_func)(void *, int, size_t) = memset;
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void mbedtls_platform_zeroize(void *buf, size_t len)
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{
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MBEDTLS_INTERNAL_VALIDATE(len == 0 || buf != NULL);
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if (len > 0) {
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memset_func(buf, 0, len);
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}
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}
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#endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */
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#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
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#include <time.h>
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#if !defined(_WIN32) && (defined(unix) || \
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defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
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defined(__MACH__)) || defined(__midipix__))
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#include <unistd.h>
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#endif /* !_WIN32 && (unix || __unix || __unix__ ||
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* (__APPLE__ && __MACH__)) || __midipix__ */
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#if !((defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L) || \
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(defined(_POSIX_THREAD_SAFE_FUNCTIONS) && \
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_POSIX_THREAD_SAFE_FUNCTIONS >= 200112L))
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/*
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* This is a convenience shorthand macro to avoid checking the long
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* preprocessor conditions above. Ideally, we could expose this macro in
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* platform_util.h and simply use it in platform_util.c, threading.c and
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* threading.h. However, this macro is not part of the Mbed TLS public API, so
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* we keep it private by only defining it in this file
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*/
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#if !(defined(_WIN32) && !defined(EFIX64) && !defined(EFI32))
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#define PLATFORM_UTIL_USE_GMTIME
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#endif /* ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) */
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#endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \
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( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \
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_POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */
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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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{
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#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
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return (gmtime_s(tm_buf, tt) == 0) ? tm_buf : NULL;
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#elif !defined(PLATFORM_UTIL_USE_GMTIME)
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return gmtime_r(tt, tm_buf);
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#else
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struct tm *lt;
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#if defined(MBEDTLS_THREADING_C)
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if (mbedtls_mutex_lock(&mbedtls_threading_gmtime_mutex) != 0) {
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return NULL;
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}
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#endif /* MBEDTLS_THREADING_C */
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lt = gmtime(tt);
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if (lt != NULL) {
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memcpy(tm_buf, lt, sizeof(struct tm));
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}
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#if defined(MBEDTLS_THREADING_C)
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if (mbedtls_mutex_unlock(&mbedtls_threading_gmtime_mutex) != 0) {
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return NULL;
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}
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#endif /* MBEDTLS_THREADING_C */
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return (lt == NULL) ? NULL : tm_buf;
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#endif /* _WIN32 && !EFIX64 && !EFI32 */
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}
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#endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */
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