1 /*
2 * Platform-specific and custom entropy polling functions
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 */
7
8 #if defined(__linux__) && !defined(_GNU_SOURCE)
9 /* Ensure that syscall() is available even when compiling with -std=c99 */
10 #define _GNU_SOURCE
11 #endif
12
13 #include "common.h"
14
15 #include <string.h>
16
17 #if defined(MBEDTLS_ENTROPY_C)
18
19 #include "mbedtls/entropy.h"
20 #include "mbedtls/entropy_poll.h"
21 #include "mbedtls/error.h"
22
23 #if defined(MBEDTLS_TIMING_C)
24 #include "mbedtls/timing.h"
25 #endif
26 #if defined(MBEDTLS_HAVEGE_C)
27 #include "mbedtls/havege.h"
28 #endif
29 #include "mbedtls/platform.h"
30
31 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
32
33 #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
34 !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \
35 !defined(__HAIKU__) && !defined(__midipix__)
36 #error \
37 "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h"
38 #endif
39
40 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
41
42 #if !defined(_WIN32_WINNT)
43 #define _WIN32_WINNT 0x0400
44 #endif
45 #include <windows.h>
46 #include <wincrypt.h>
47
mbedtls_platform_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)48 int mbedtls_platform_entropy_poll(void *data, unsigned char *output, size_t len,
49 size_t *olen)
50 {
51 HCRYPTPROV provider;
52 ((void) data);
53 *olen = 0;
54
55 if (CryptAcquireContext(&provider, NULL, NULL,
56 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT) == FALSE) {
57 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
58 }
59
60 if (CryptGenRandom(provider, (DWORD) len, output) == FALSE) {
61 CryptReleaseContext(provider, 0);
62 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
63 }
64
65 CryptReleaseContext(provider, 0);
66 *olen = len;
67
68 return 0;
69 }
70 #else /* _WIN32 && !EFIX64 && !EFI32 */
71
72 /*
73 * Test for Linux getrandom() support.
74 * Since there is no wrapper in the libc yet, use the generic syscall wrapper
75 * available in GNU libc and compatible libc's (eg uClibc).
76 */
77 #if ((defined(__linux__) && defined(__GLIBC__)) || defined(__midipix__))
78 #include <unistd.h>
79 #include <sys/syscall.h>
80 #if defined(SYS_getrandom)
81 #define HAVE_GETRANDOM
82 #include <errno.h>
83
getrandom_wrapper(void * buf,size_t buflen,unsigned int flags)84 static int getrandom_wrapper(void *buf, size_t buflen, unsigned int flags)
85 {
86 /* MemSan cannot understand that the syscall writes to the buffer */
87 #if defined(__has_feature)
88 #if __has_feature(memory_sanitizer)
89 memset(buf, 0, buflen);
90 #endif
91 #endif
92 return syscall(SYS_getrandom, buf, buflen, flags);
93 }
94 #endif /* SYS_getrandom */
95 #endif /* __linux__ || __midipix__ */
96
97 #if defined(__FreeBSD__) || defined(__DragonFly__)
98 #include <sys/param.h>
99 #if (defined(__FreeBSD__) && __FreeBSD_version >= 1200000) || \
100 (defined(__DragonFly__) && __DragonFly_version >= 500700)
101 #include <errno.h>
102 #include <sys/random.h>
103 #define HAVE_GETRANDOM
getrandom_wrapper(void * buf,size_t buflen,unsigned int flags)104 static int getrandom_wrapper(void *buf, size_t buflen, unsigned int flags)
105 {
106 return getrandom(buf, buflen, flags);
107 }
108 #endif /* (__FreeBSD__ && __FreeBSD_version >= 1200000) ||
109 (__DragonFly__ && __DragonFly_version >= 500700) */
110 #endif /* __FreeBSD__ || __DragonFly__ */
111
112 /*
113 * Some BSD systems provide KERN_ARND.
114 * This is equivalent to reading from /dev/urandom, only it doesn't require an
115 * open file descriptor, and provides up to 256 bytes per call (basically the
116 * same as getentropy(), but with a longer history).
117 *
118 * Documentation: https://netbsd.gw.com/cgi-bin/man-cgi?sysctl+7
119 */
120 #if (defined(__FreeBSD__) || defined(__NetBSD__)) && !defined(HAVE_GETRANDOM)
121 #include <sys/param.h>
122 #include <sys/sysctl.h>
123 #if defined(KERN_ARND)
124 #define HAVE_SYSCTL_ARND
125
sysctl_arnd_wrapper(unsigned char * buf,size_t buflen)126 static int sysctl_arnd_wrapper(unsigned char *buf, size_t buflen)
127 {
128 int name[2];
129 size_t len;
130
131 name[0] = CTL_KERN;
132 name[1] = KERN_ARND;
133
134 while (buflen > 0) {
135 len = buflen > 256 ? 256 : buflen;
136 if (sysctl(name, 2, buf, &len, NULL, 0) == -1) {
137 return -1;
138 }
139 buflen -= len;
140 buf += len;
141 }
142 return 0;
143 }
144 #endif /* KERN_ARND */
145 #endif /* __FreeBSD__ || __NetBSD__ */
146
147 #include <stdio.h>
148
mbedtls_platform_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)149 int mbedtls_platform_entropy_poll(void *data,
150 unsigned char *output, size_t len, size_t *olen)
151 {
152 FILE *file;
153 size_t read_len;
154 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
155 ((void) data);
156
157 #if defined(HAVE_GETRANDOM)
158 ret = getrandom_wrapper(output, len, 0);
159 if (ret >= 0) {
160 *olen = ret;
161 return 0;
162 } else if (errno != ENOSYS) {
163 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
164 }
165 /* Fall through if the system call isn't known. */
166 #else
167 ((void) ret);
168 #endif /* HAVE_GETRANDOM */
169
170 #if defined(HAVE_SYSCTL_ARND)
171 ((void) file);
172 ((void) read_len);
173 if (sysctl_arnd_wrapper(output, len) == -1) {
174 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
175 }
176 *olen = len;
177 return 0;
178 #else
179
180 *olen = 0;
181
182 file = fopen("/dev/urandom", "rb");
183 if (file == NULL) {
184 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
185 }
186
187 read_len = fread(output, 1, len, file);
188 if (read_len != len) {
189 fclose(file);
190 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
191 }
192
193 fclose(file);
194 *olen = len;
195
196 return 0;
197 #endif /* HAVE_SYSCTL_ARND */
198 }
199 #endif /* _WIN32 && !EFIX64 && !EFI32 */
200 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
201
202 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
mbedtls_null_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)203 int mbedtls_null_entropy_poll(void *data,
204 unsigned char *output, size_t len, size_t *olen)
205 {
206 ((void) data);
207 ((void) output);
208
209 *olen = 0;
210 if (len < sizeof(unsigned char)) {
211 return 0;
212 }
213
214 output[0] = 0;
215 *olen = sizeof(unsigned char);
216 return 0;
217 }
218 #endif
219
220 #if defined(MBEDTLS_TIMING_C)
mbedtls_hardclock_poll(void * data,unsigned char * output,size_t len,size_t * olen)221 int mbedtls_hardclock_poll(void *data,
222 unsigned char *output, size_t len, size_t *olen)
223 {
224 unsigned long timer = mbedtls_timing_hardclock();
225 ((void) data);
226 *olen = 0;
227
228 if (len < sizeof(unsigned long)) {
229 return 0;
230 }
231
232 memcpy(output, &timer, sizeof(unsigned long));
233 *olen = sizeof(unsigned long);
234
235 return 0;
236 }
237 #endif /* MBEDTLS_TIMING_C */
238
239 #if defined(MBEDTLS_HAVEGE_C)
mbedtls_havege_poll(void * data,unsigned char * output,size_t len,size_t * olen)240 int mbedtls_havege_poll(void *data,
241 unsigned char *output, size_t len, size_t *olen)
242 {
243 mbedtls_havege_state *hs = (mbedtls_havege_state *) data;
244 *olen = 0;
245
246 if (mbedtls_havege_random(hs, output, len) != 0) {
247 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
248 }
249
250 *olen = len;
251
252 return 0;
253 }
254 #endif /* MBEDTLS_HAVEGE_C */
255
256 #if defined(MBEDTLS_ENTROPY_NV_SEED)
mbedtls_nv_seed_poll(void * data,unsigned char * output,size_t len,size_t * olen)257 int mbedtls_nv_seed_poll(void *data,
258 unsigned char *output, size_t len, size_t *olen)
259 {
260 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
261 size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
262 ((void) data);
263
264 memset(buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE);
265
266 if (mbedtls_nv_seed_read(buf, MBEDTLS_ENTROPY_BLOCK_SIZE) < 0) {
267 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
268 }
269
270 if (len < use_len) {
271 use_len = len;
272 }
273
274 memcpy(output, buf, use_len);
275 *olen = use_len;
276
277 return 0;
278 }
279 #endif /* MBEDTLS_ENTROPY_NV_SEED */
280
281 #endif /* MBEDTLS_ENTROPY_C */
282