platform_util.c (8811B)
1 /* 2 * Common and shared functions used by multiple modules in the Mbed TLS 3 * library. 4 * 5 * Copyright The Mbed TLS Contributors 6 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 7 */ 8 9 /* 10 * Ensure gmtime_r is available even with -std=c99; must be defined before 11 * mbedtls_config.h, which pulls in glibc's features.h. Harmless on other platforms 12 * except OpenBSD, where it stops us accessing explicit_bzero. 13 */ 14 #if !defined(_POSIX_C_SOURCE) && !defined(__OpenBSD__) 15 #define _POSIX_C_SOURCE 200112L 16 #endif 17 18 #if !defined(_GNU_SOURCE) 19 /* Clang requires this to get support for explicit_bzero */ 20 #define _GNU_SOURCE 21 #endif 22 23 #include "common.h" 24 25 #include "mbedtls/platform_util.h" 26 #include "mbedtls/platform.h" 27 #include "mbedtls/threading.h" 28 29 #include <stddef.h> 30 31 #ifndef __STDC_WANT_LIB_EXT1__ 32 #define __STDC_WANT_LIB_EXT1__ 1 /* Ask for the C11 gmtime_s() and memset_s() if available */ 33 #endif 34 #include <string.h> 35 36 #if defined(_WIN32) 37 #include <windows.h> 38 #endif 39 40 // Detect platforms known to support explicit_bzero() 41 #if defined(__GLIBC__) && (__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 25) 42 #define MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO 1 43 #elif (defined(__FreeBSD__) && (__FreeBSD_version >= 1100037)) || defined(__OpenBSD__) 44 #define MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO 1 45 #endif 46 47 #if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT) 48 49 #undef HAVE_MEMORY_SANITIZER 50 #if defined(__has_feature) 51 #if __has_feature(memory_sanitizer) 52 #include <sanitizer/msan_interface.h> 53 #define HAVE_MEMORY_SANITIZER 54 #endif 55 #endif 56 57 /* 58 * Where possible, we try to detect the presence of a platform-provided 59 * secure memset, such as explicit_bzero(), that is safe against being optimized 60 * out, and use that. 61 * 62 * For other platforms, we provide an implementation that aims not to be 63 * optimized out by the compiler. 64 * 65 * This implementation for mbedtls_platform_zeroize() was inspired from Colin 66 * Percival's blog article at: 67 * 68 * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html 69 * 70 * It uses a volatile function pointer to the standard memset(). Because the 71 * pointer is volatile the compiler expects it to change at 72 * any time and will not optimize out the call that could potentially perform 73 * other operations on the input buffer instead of just setting it to 0. 74 * Nevertheless, as pointed out by davidtgoldblatt on Hacker News 75 * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for 76 * details), optimizations of the following form are still possible: 77 * 78 * if (memset_func != memset) 79 * memset_func(buf, 0, len); 80 * 81 * Note that it is extremely difficult to guarantee that 82 * the memset() call will not be optimized out by aggressive compilers 83 * in a portable way. For this reason, Mbed TLS also provides the configuration 84 * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure 85 * mbedtls_platform_zeroize() to use a suitable implementation for their 86 * platform and needs. 87 */ 88 #if !defined(MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO) && !(defined(__STDC_LIB_EXT1__) && \ 89 !defined(__IAR_SYSTEMS_ICC__)) \ 90 && !defined(_WIN32) 91 static void *(*const volatile memset_func)(void *, int, size_t) = memset; 92 #endif 93 94 void mbedtls_platform_zeroize(void *buf, size_t len) 95 { 96 if (len > 0) { 97 #if defined(MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO) 98 explicit_bzero(buf, len); 99 #if defined(HAVE_MEMORY_SANITIZER) 100 /* You'd think that Msan would recognize explicit_bzero() as 101 * equivalent to bzero(), but it actually doesn't on several 102 * platforms, including Linux (Ubuntu 20.04). 103 * https://github.com/google/sanitizers/issues/1507 104 * https://github.com/openssh/openssh-portable/commit/74433a19bb6f4cef607680fa4d1d7d81ca3826aa 105 */ 106 __msan_unpoison(buf, len); 107 #endif 108 #elif defined(__STDC_LIB_EXT1__) && !defined(__IAR_SYSTEMS_ICC__) 109 memset_s(buf, len, 0, len); 110 #elif defined(_WIN32) 111 SecureZeroMemory(buf, len); 112 #else 113 memset_func(buf, 0, len); 114 #endif 115 116 #if defined(__GNUC__) 117 /* For clang and recent gcc, pretend that we have some assembly that reads the 118 * zero'd memory as an additional protection against being optimised away. */ 119 #if defined(__clang__) || (__GNUC__ >= 10) 120 #if defined(__clang__) 121 #pragma clang diagnostic push 122 #pragma clang diagnostic ignored "-Wvla" 123 #elif defined(MBEDTLS_COMPILER_IS_GCC) 124 #pragma GCC diagnostic push 125 #pragma GCC diagnostic ignored "-Wvla" 126 #endif 127 asm volatile ("" : : "m" (*(char (*)[len]) buf) :); 128 #if defined(__clang__) 129 #pragma clang diagnostic pop 130 #elif defined(MBEDTLS_COMPILER_IS_GCC) 131 #pragma GCC diagnostic pop 132 #endif 133 #endif 134 #endif 135 } 136 } 137 #endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */ 138 139 void mbedtls_zeroize_and_free(void *buf, size_t len) 140 { 141 if (buf != NULL) { 142 mbedtls_platform_zeroize(buf, len); 143 } 144 145 mbedtls_free(buf); 146 } 147 148 #if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT) 149 #include <time.h> 150 #if !defined(_WIN32) && (defined(unix) || \ 151 defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \ 152 defined(__MACH__)) || defined(__midipix__)) 153 #include <unistd.h> 154 #endif /* !_WIN32 && (unix || __unix || __unix__ || 155 * (__APPLE__ && __MACH__) || __midipix__) */ 156 157 #if !((defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L) || \ 158 (defined(_POSIX_THREAD_SAFE_FUNCTIONS) && \ 159 _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L)) 160 /* 161 * This is a convenience shorthand macro to avoid checking the long 162 * preprocessor conditions above. Ideally, we could expose this macro in 163 * platform_util.h and simply use it in platform_util.c, threading.c and 164 * threading.h. However, this macro is not part of the Mbed TLS public API, so 165 * we keep it private by only defining it in this file 166 */ 167 #if !(defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)) || \ 168 (defined(__MINGW32__) && !defined(__MINGW64_VERSION_MAJOR)) 169 #define PLATFORM_UTIL_USE_GMTIME 170 #endif 171 172 #endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \ 173 ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \ 174 _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */ 175 176 struct tm *mbedtls_platform_gmtime_r(const mbedtls_time_t *tt, 177 struct tm *tm_buf) 178 { 179 #if defined(_WIN32) && !defined(PLATFORM_UTIL_USE_GMTIME) 180 #if defined(__STDC_LIB_EXT1__) 181 return (gmtime_s(tt, tm_buf) == 0) ? NULL : tm_buf; 182 #else 183 /* MSVC and mingw64 argument order and return value are inconsistent with the C11 standard */ 184 return (gmtime_s(tm_buf, tt) == 0) ? tm_buf : NULL; 185 #endif 186 #elif !defined(PLATFORM_UTIL_USE_GMTIME) 187 return gmtime_r(tt, tm_buf); 188 #else 189 struct tm *lt; 190 191 #if defined(MBEDTLS_THREADING_C) 192 if (mbedtls_mutex_lock(&mbedtls_threading_gmtime_mutex) != 0) { 193 return NULL; 194 } 195 #endif /* MBEDTLS_THREADING_C */ 196 197 lt = gmtime(tt); 198 199 if (lt != NULL) { 200 memcpy(tm_buf, lt, sizeof(struct tm)); 201 } 202 203 #if defined(MBEDTLS_THREADING_C) 204 if (mbedtls_mutex_unlock(&mbedtls_threading_gmtime_mutex) != 0) { 205 return NULL; 206 } 207 #endif /* MBEDTLS_THREADING_C */ 208 209 return (lt == NULL) ? NULL : tm_buf; 210 #endif /* _WIN32 && !EFIX64 && !EFI32 */ 211 } 212 #endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */ 213 214 #if defined(MBEDTLS_TEST_HOOKS) 215 void (*mbedtls_test_hook_test_fail)(const char *, int, const char *); 216 #endif /* MBEDTLS_TEST_HOOKS */ 217 218 #if defined(MBEDTLS_HAVE_TIME) && !defined(MBEDTLS_PLATFORM_MS_TIME_ALT) 219 220 #include <time.h> 221 #if !defined(_WIN32) && \ 222 (defined(unix) || defined(__unix) || defined(__unix__) || \ 223 (defined(__APPLE__) && defined(__MACH__)) || defined(__HAIKU__) || defined(__midipix__)) 224 #include <unistd.h> 225 #endif \ 226 /* !_WIN32 && (unix || __unix || __unix__ || (__APPLE__ && __MACH__) || __HAIKU__ || __midipix__) */ 227 #if (defined(_POSIX_VERSION) && _POSIX_VERSION >= 199309L) || defined(__HAIKU__) 228 mbedtls_ms_time_t mbedtls_ms_time(void) 229 { 230 int ret; 231 struct timespec tv; 232 mbedtls_ms_time_t current_ms; 233 234 #if defined(__linux__) && defined(CLOCK_BOOTTIME) || defined(__midipix__) 235 ret = clock_gettime(CLOCK_BOOTTIME, &tv); 236 #else 237 ret = clock_gettime(CLOCK_MONOTONIC, &tv); 238 #endif 239 if (ret) { 240 return time(NULL) * 1000; 241 } 242 243 current_ms = tv.tv_sec; 244 245 return current_ms*1000 + tv.tv_nsec / 1000000; 246 } 247 #elif defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || \ 248 defined(__MINGW32__) || defined(_WIN64) 249 #include <windows.h> 250 mbedtls_ms_time_t mbedtls_ms_time(void) 251 { 252 FILETIME ct; 253 mbedtls_ms_time_t current_ms; 254 255 GetSystemTimeAsFileTime(&ct); 256 current_ms = ((mbedtls_ms_time_t) ct.dwLowDateTime + 257 ((mbedtls_ms_time_t) (ct.dwHighDateTime) << 32LL))/10000; 258 return current_ms; 259 } 260 #else 261 #error "No mbedtls_ms_time available" 262 #endif 263 #endif /* MBEDTLS_HAVE_TIME && !MBEDTLS_PLATFORM_MS_TIME_ALT */