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#include "securec.h"
31
32#ifndef __STDC_WANT_LIB_EXT1__
33#define __STDC_WANT_LIB_EXT1__ 1 /* Ask for the C11 gmtime_s() and memset_s() if available */
34#endif
35#include <string.h>
36
37#if defined(_WIN32)
38#include <windows.h>
39#endif
40
41// Detect platforms known to support explicit_bzero()
42#if defined(__GLIBC__) && (__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 25)
43#define MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO 1
44#elif (defined(__FreeBSD__) && (__FreeBSD_version >= 1100037)) || defined(__OpenBSD__)
45#define MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO 1
46#endif
47
48#if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT)
49
50#undef HAVE_MEMORY_SANITIZER
51#if defined(__has_feature)
52#if __has_feature(memory_sanitizer)
53#include <sanitizer/msan_interface.h>
54#define HAVE_MEMORY_SANITIZER
55#endif
56#endif
57
58/*
59 * Where possible, we try to detect the presence of a platform-provided
60 * secure memset, such as explicit_bzero(), that is safe against being optimized
61 * out, and use that.
62 *
63 * For other platforms, we provide an implementation that aims not to be
64 * optimized out by the compiler.
65 *
66 * This implementation for mbedtls_platform_zeroize() was inspired from Colin
67 * Percival's blog article at:
68 *
69 * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
70 *
71 * It uses a volatile function pointer to the standard memset(). Because the
72 * pointer is volatile the compiler expects it to change at
73 * any time and will not optimize out the call that could potentially perform
74 * other operations on the input buffer instead of just setting it to 0.
75 * Nevertheless, as pointed out by davidtgoldblatt on Hacker News
76 * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for
77 * details), optimizations of the following form are still possible:
78 *
79 * if (memset_func != memset)
80 *     memset_func(buf, 0, len);
81 *
82 * Note that it is extremely difficult to guarantee that
83 * the memset() call will not be optimized out by aggressive compilers
84 * in a portable way. For this reason, Mbed TLS also provides the configuration
85 * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
86 * mbedtls_platform_zeroize() to use a suitable implementation for their
87 * platform and needs.
88 */
89#if !defined(MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO) && !(defined(__STDC_LIB_EXT1__) && \
90    !defined(__IAR_SYSTEMS_ICC__)) \
91    && !defined(_WIN32)
92static void *(*const volatile memset_func)(void *, int, size_t) = memset;
93#endif
94
95void mbedtls_platform_zeroize(void *buf, size_t len)
96{
97    if (len > 0) {
98#if defined(MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO)
99        explicit_bzero(buf, len);
100#if defined(HAVE_MEMORY_SANITIZER)
101        /* You'd think that Msan would recognize explicit_bzero() as
102         * equivalent to bzero(), but it actually doesn't on several
103         * platforms, including Linux (Ubuntu 20.04).
104         * https://github.com/google/sanitizers/issues/1507
105         * https://github.com/openssh/openssh-portable/commit/74433a19bb6f4cef607680fa4d1d7d81ca3826aa
106         */
107        __msan_unpoison(buf, len);
108#endif
109#elif defined(__STDC_LIB_EXT1__) && !defined(__IAR_SYSTEMS_ICC__)
110        memset_s(buf, len, 0, len);
111#elif defined(_WIN32)
112        SecureZeroMemory(buf, len);
113#else
114        memset_func(buf, 0, len);
115#endif
116
117#if defined(__GNUC__)
118        /* For clang and recent gcc, pretend that we have some assembly that reads the
119         * zero'd memory as an additional protection against being optimised away. */
120#if defined(__clang__) || (__GNUC__ >= 10)
121#if defined(__clang__)
122#pragma clang diagnostic push
123#pragma clang diagnostic ignored "-Wvla"
124#elif defined(MBEDTLS_COMPILER_IS_GCC)
125#pragma GCC diagnostic push
126#pragma GCC diagnostic ignored "-Wvla"
127#endif
128        asm volatile ("" : : "m" (*(char (*)[len]) buf) :);
129#if defined(__clang__)
130#pragma clang diagnostic pop
131#elif defined(MBEDTLS_COMPILER_IS_GCC)
132#pragma GCC diagnostic pop
133#endif
134#endif
135#endif
136    }
137}
138#endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */
139
140void mbedtls_zeroize_and_free(void *buf, size_t len)
141{
142    if (buf != NULL) {
143        mbedtls_platform_zeroize(buf, len);
144    }
145
146    mbedtls_free(buf);
147}
148
149#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
150#include <time.h>
151#if !defined(_WIN32) && (defined(unix) || \
152    defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
153    defined(__MACH__)) || defined__midipix__)
154#include <unistd.h>
155#endif /* !_WIN32 && (unix || __unix || __unix__ ||
156        * (__APPLE__ && __MACH__) || __midipix__) */
157
158#if !((defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L) ||     \
159    (defined(_POSIX_THREAD_SAFE_FUNCTIONS) &&                     \
160    _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L))
161/*
162 * This is a convenience shorthand macro to avoid checking the long
163 * preprocessor conditions above. Ideally, we could expose this macro in
164 * platform_util.h and simply use it in platform_util.c, threading.c and
165 * threading.h. However, this macro is not part of the Mbed TLS public API, so
166 * we keep it private by only defining it in this file
167 */
168#if !(defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)) || \
169    (defined(__MINGW32__) && !defined(__MINGW64_VERSION_MAJOR))
170#define PLATFORM_UTIL_USE_GMTIME
171#endif
172
173#endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \
174             ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \
175                _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */
176
177struct tm *mbedtls_platform_gmtime_r(const mbedtls_time_t *tt,
178                                     struct tm *tm_buf)
179{
180#if defined(_WIN32) && !defined(PLATFORM_UTIL_USE_GMTIME)
181#if defined(__STDC_LIB_EXT1__)
182    return (gmtime_s(tt, tm_buf) == 0) ? NULL : tm_buf;
183#else
184    /* MSVC and mingw64 argument order and return value are inconsistent with the C11 standard */
185    return (gmtime_s(tm_buf, tt) == 0) ? tm_buf : NULL;
186#endif
187#elif !defined(PLATFORM_UTIL_USE_GMTIME)
188    return gmtime_r(tt, tm_buf);
189#else
190    struct tm *lt;
191
192#if defined(MBEDTLS_THREADING_C)
193    if (mbedtls_mutex_lock(&mbedtls_threading_gmtime_mutex) != 0) {
194        return NULL;
195    }
196#endif /* MBEDTLS_THREADING_C */
197
198    lt = gmtime(tt);
199
200    if (lt != NULL) {
201        memcpy(tm_buf, lt, sizeof(struct tm));
202    }
203
204#if defined(MBEDTLS_THREADING_C)
205    if (mbedtls_mutex_unlock(&mbedtls_threading_gmtime_mutex) != 0) {
206        return NULL;
207    }
208#endif /* MBEDTLS_THREADING_C */
209
210    return (lt == NULL) ? NULL : tm_buf;
211#endif /* _WIN32 && !EFIX64 && !EFI32 */
212}
213#endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */
214
215#if defined(MBEDTLS_TEST_HOOKS)
216void (*mbedtls_test_hook_test_fail)(const char *, int, const char *);
217#endif /* MBEDTLS_TEST_HOOKS */
218
219#if defined(MBEDTLS_HAVE_TIME) && !defined(MBEDTLS_PLATFORM_MS_TIME_ALT)
220
221#include <time.h>
222#if !defined(_WIN32) && \
223    (defined(unix) || defined(__unix) || defined(__unix__) || \
224    (defined(__APPLE__) && defined(__MACH__)) || defined(__HAIKU__) || defined(__midipix__))
225#include <unistd.h>
226#endif \
227    /* !_WIN32 && (unix || __unix || __unix__ || (__APPLE__ && __MACH__) || __HAIKU__ || __midipix__) */
228#if (defined(_POSIX_VERSION) && _POSIX_VERSION >= 199309L) || defined(__HAIKU__) || defined(__unix__)
229mbedtls_ms_time_t mbedtls_ms_time(void)
230{
231    int ret;
232    struct timespec tv;
233    mbedtls_ms_time_t current_ms;
234
235#if defined(__linux__) && defined(CLOCK_BOOTTIME) || defined(__midipix__)
236    ret = clock_gettime(CLOCK_BOOTTIME, &tv);
237#else
238    ret = clock_gettime(CLOCK_MONOTONIC, &tv);
239#endif
240    if (ret) {
241        return time(NULL) * 1000;
242    }
243
244    current_ms = tv.tv_sec;
245
246    return current_ms*1000 + tv.tv_nsec / 1000000;
247}
248#elif defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || \
249    defined(__MINGW32__) || defined(_WIN64)
250#include <windows.h>
251mbedtls_ms_time_t mbedtls_ms_time(void)
252{
253    FILETIME ct;
254    mbedtls_ms_time_t current_ms;
255
256    GetSystemTimeAsFileTime(&ct);
257    current_ms = ((mbedtls_ms_time_t) ct.dwLowDateTime +
258                  ((mbedtls_ms_time_t) (ct.dwHighDateTime) << 32LL))/10000;
259    return current_ms;
260}
261#else
262#error "No mbedtls_ms_time available"
263#endif
264#endif /* MBEDTLS_HAVE_TIME && !MBEDTLS_PLATFORM_MS_TIME_ALT */
265