1 /*
2 * Platform-specific and custom entropy polling functions
3 *
4 * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: Apache-2.0
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 *
19 * This file is part of mbed TLS (https://tls.mbed.org)
20 */
21
22 #if !defined(MBEDTLS_CONFIG_FILE)
23 #include "mbedtls/config.h"
24 #else
25 #include MBEDTLS_CONFIG_FILE
26 #endif
27
28 #if defined(MBEDTLS_ENTROPY_C)
29
30 #include "mbedtls/entropy.h"
31 #include "mbedtls/entropy_poll.h"
32
33 #if defined(MBEDTLS_TIMING_C)
34 #include <string.h>
35 #include "mbedtls/timing.h"
36 #endif
37 #if defined(MBEDTLS_HAVEGE_C)
38 #include "mbedtls/havege.h"
39 #endif
40 #if defined(MBEDTLS_ENTROPY_NV_SEED)
41 #include "mbedtls/platform.h"
42 #endif
43
44 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
45
46 #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
47 !defined(__APPLE__) && !defined(_WIN32)
48 #error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h"
49 #endif
50
51 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
52
53 #if !defined(_WIN32_WINNT)
54 #define _WIN32_WINNT 0x0400
55 #endif
56 #include <windows.h>
57 #include <wincrypt.h>
58
mbedtls_platform_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)59 int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len,
60 size_t *olen )
61 {
62 HCRYPTPROV provider;
63 ((void) data);
64 *olen = 0;
65
66 if( CryptAcquireContext( &provider, NULL, NULL,
67 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT ) == FALSE )
68 {
69 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
70 }
71
72 if( CryptGenRandom( provider, (DWORD) len, output ) == FALSE )
73 {
74 CryptReleaseContext( provider, 0 );
75 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
76 }
77
78 CryptReleaseContext( provider, 0 );
79 *olen = len;
80
81 return( 0 );
82 }
83 #else /* _WIN32 && !EFIX64 && !EFI32 */
84
85 /*
86 * Test for Linux getrandom() support.
87 * Since there is no wrapper in the libc yet, use the generic syscall wrapper
88 * available in GNU libc and compatible libc's (eg uClibc).
89 */
90 #if defined(__linux__) && defined(__GLIBC__)
91 #include <unistd.h>
92 #include <sys/syscall.h>
93 #if defined(SYS_getrandom)
94 #define HAVE_GETRANDOM
95
getrandom_wrapper(void * buf,size_t buflen,unsigned int flags)96 static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags )
97 {
98 /* MemSan cannot understand that the syscall writes to the buffer */
99 #if defined(__has_feature)
100 #if __has_feature(memory_sanitizer)
101 memset( buf, 0, buflen );
102 #endif
103 #endif
104
105 return( syscall( SYS_getrandom, buf, buflen, flags ) );
106 }
107
108 #include <sys/utsname.h>
109 /* Check if version is at least 3.17.0 */
check_version_3_17_plus(void)110 static int check_version_3_17_plus( void )
111 {
112 int minor;
113 struct utsname un;
114 const char *ver;
115
116 /* Get version information */
117 uname(&un);
118 ver = un.release;
119
120 /* Check major version; assume a single digit */
121 if( ver[0] < '3' || ver[0] > '9' || ver [1] != '.' )
122 return( -1 );
123
124 if( ver[0] - '0' > 3 )
125 return( 0 );
126
127 /* Ok, so now we know major == 3, check minor.
128 * Assume 1 or 2 digits. */
129 if( ver[2] < '0' || ver[2] > '9' )
130 return( -1 );
131
132 minor = ver[2] - '0';
133
134 if( ver[3] >= '0' && ver[3] <= '9' )
135 minor = 10 * minor + ver[3] - '0';
136 else if( ver [3] != '.' )
137 return( -1 );
138
139 if( minor < 17 )
140 return( -1 );
141
142 return( 0 );
143 }
144 static int has_getrandom = -1;
145 #endif /* SYS_getrandom */
146 #endif /* __linux__ */
147
148 #include <stdio.h>
149
mbedtls_platform_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)150 int mbedtls_platform_entropy_poll( void *data,
151 unsigned char *output, size_t len, size_t *olen )
152 {
153 FILE *file;
154 size_t read_len;
155 ((void) data);
156
157 #if defined(HAVE_GETRANDOM)
158 if( has_getrandom == -1 )
159 has_getrandom = ( check_version_3_17_plus() == 0 );
160
161 if( has_getrandom )
162 {
163 int ret;
164
165 if( ( ret = getrandom_wrapper( output, len, 0 ) ) < 0 )
166 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
167
168 *olen = ret;
169 return( 0 );
170 }
171 #endif /* HAVE_GETRANDOM */
172
173 *olen = 0;
174
175 file = fopen( "/dev/urandom", "rb" );
176 if( file == NULL )
177 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
178
179 read_len = fread( output, 1, len, file );
180 if( read_len != len )
181 {
182 fclose( file );
183 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
184 }
185
186 fclose( file );
187 *olen = len;
188
189 return( 0 );
190 }
191 #endif /* _WIN32 && !EFIX64 && !EFI32 */
192 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
193
194 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
mbedtls_null_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)195 int mbedtls_null_entropy_poll( void *data,
196 unsigned char *output, size_t len, size_t *olen )
197 {
198 ((void) data);
199 ((void) output);
200 *olen = 0;
201
202 if( len < sizeof(unsigned char) )
203 return( 0 );
204
205 *olen = sizeof(unsigned char);
206
207 return( 0 );
208 }
209 #endif
210
211 #if defined(MBEDTLS_TIMING_C)
mbedtls_hardclock_poll(void * data,unsigned char * output,size_t len,size_t * olen)212 int mbedtls_hardclock_poll( void *data,
213 unsigned char *output, size_t len, size_t *olen )
214 {
215 unsigned long timer = mbedtls_timing_hardclock();
216 ((void) data);
217 *olen = 0;
218
219 if( len < sizeof(unsigned long) )
220 return( 0 );
221
222 memcpy( output, &timer, sizeof(unsigned long) );
223 *olen = sizeof(unsigned long);
224
225 return( 0 );
226 }
227 #endif /* MBEDTLS_TIMING_C */
228
229 #if defined(MBEDTLS_HAVEGE_C)
mbedtls_havege_poll(void * data,unsigned char * output,size_t len,size_t * olen)230 int mbedtls_havege_poll( void *data,
231 unsigned char *output, size_t len, size_t *olen )
232 {
233 mbedtls_havege_state *hs = (mbedtls_havege_state *) data;
234 *olen = 0;
235
236 if( mbedtls_havege_random( hs, output, len ) != 0 )
237 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
238
239 *olen = len;
240
241 return( 0 );
242 }
243 #endif /* MBEDTLS_HAVEGE_C */
244
245 #if defined(MBEDTLS_ENTROPY_NV_SEED)
mbedtls_nv_seed_poll(void * data,unsigned char * output,size_t len,size_t * olen)246 int mbedtls_nv_seed_poll( void *data,
247 unsigned char *output, size_t len, size_t *olen )
248 {
249 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
250 size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
251 ((void) data);
252
253 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
254
255 if( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
256 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
257
258 if( len < use_len )
259 use_len = len;
260
261 memcpy( output, buf, use_len );
262 *olen = use_len;
263
264 return( 0 );
265 }
266 #endif /* MBEDTLS_ENTROPY_NV_SEED */
267
268 #endif /* MBEDTLS_ENTROPY_C */
269
