1 /*
2 * Platform-specific and custom entropy polling functions
3 *
4 * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: GPL-2.0
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * This file is part of mbed TLS (https://tls.mbed.org)
22 */
23
24 #if defined(__linux__)
25 /* Ensure that syscall() is available even when compiling with -std=c99 */
26 #define _GNU_SOURCE
27 #endif
28
29 #if !defined(MBEDTLS_CONFIG_FILE)
30 #include "mbedtls/config.h"
31 #else
32 #include MBEDTLS_CONFIG_FILE
33 #endif
34
35 #include <string.h>
36
37 #if defined(MBEDTLS_ENTROPY_C)
38
39 #include "mbedtls/entropy.h"
40 #include "mbedtls/entropy_poll.h"
41
42 #if defined(MBEDTLS_TIMING_C)
43 #include "mbedtls/timing.h"
44 #endif
45 #if defined(MBEDTLS_HAVEGE_C)
46 #include "mbedtls/havege.h"
47 #endif
48 #if defined(MBEDTLS_ENTROPY_NV_SEED)
49 #include "mbedtls/platform.h"
50 #endif
51
52 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
53
54 #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
55 !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \
56 !defined(__HAIKU__)
57 #error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h"
58 #endif
59
60 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
61
62 #if !defined(_WIN32_WINNT)
63 #define _WIN32_WINNT 0x0400
64 #endif
65 #include <windows.h>
66 #include <wincrypt.h>
67
mbedtls_platform_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)68 int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len,
69 size_t *olen )
70 {
71 HCRYPTPROV provider;
72 ((void) data);
73 *olen = 0;
74
75 if( CryptAcquireContext( &provider, NULL, NULL,
76 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT ) == FALSE )
77 {
78 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
79 }
80
81 if( CryptGenRandom( provider, (DWORD) len, output ) == FALSE )
82 {
83 CryptReleaseContext( provider, 0 );
84 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
85 }
86
87 CryptReleaseContext( provider, 0 );
88 *olen = len;
89
90 return( 0 );
91 }
92 #else /* _WIN32 && !EFIX64 && !EFI32 */
93
94 /*
95 * Test for Linux getrandom() support.
96 * Since there is no wrapper in the libc yet, use the generic syscall wrapper
97 * available in GNU libc and compatible libc's (eg uClibc).
98 */
99 #if defined(__linux__) && defined(__GLIBC__)
100 #include <unistd.h>
101 #include <sys/syscall.h>
102 #if defined(SYS_getrandom)
103 #define HAVE_GETRANDOM
104 #include <errno.h>
105
getrandom_wrapper(void * buf,size_t buflen,unsigned int flags)106 static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags )
107 {
108 /* MemSan cannot understand that the syscall writes to the buffer */
109 #if defined(__has_feature)
110 #if __has_feature(memory_sanitizer)
111 memset( buf, 0, buflen );
112 #endif
113 #endif
114 return( syscall( SYS_getrandom, buf, buflen, flags ) );
115 }
116 #endif /* SYS_getrandom */
117 #endif /* __linux__ */
118
119 #include <stdio.h>
120
mbedtls_platform_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)121 int mbedtls_platform_entropy_poll( void *data,
122 unsigned char *output, size_t len, size_t *olen )
123 {
124 FILE *file;
125 size_t read_len;
126 int ret;
127 ((void) data);
128
129 #if defined(HAVE_GETRANDOM)
130 ret = getrandom_wrapper( output, len, 0 );
131 if( ret >= 0 )
132 {
133 *olen = ret;
134 return( 0 );
135 }
136 else if( errno != ENOSYS )
137 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
138 /* Fall through if the system call isn't known. */
139 #else
140 ((void) ret);
141 #endif /* HAVE_GETRANDOM */
142
143 *olen = 0;
144
145 file = fopen( "/dev/urandom", "rb" );
146 if( file == NULL )
147 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
148
149 read_len = fread( output, 1, len, file );
150 if( read_len != len )
151 {
152 fclose( file );
153 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
154 }
155
156 fclose( file );
157 *olen = len;
158
159 return( 0 );
160 }
161 #endif /* _WIN32 && !EFIX64 && !EFI32 */
162 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
163
164 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
mbedtls_null_entropy_poll(void * data,unsigned char * output,size_t len,size_t * olen)165 int mbedtls_null_entropy_poll( void *data,
166 unsigned char *output, size_t len, size_t *olen )
167 {
168 ((void) data);
169 ((void) output);
170 *olen = 0;
171
172 if( len < sizeof(unsigned char) )
173 return( 0 );
174
175 *olen = sizeof(unsigned char);
176
177 return( 0 );
178 }
179 #endif
180
181 #if defined(MBEDTLS_TIMING_C)
mbedtls_hardclock_poll(void * data,unsigned char * output,size_t len,size_t * olen)182 int mbedtls_hardclock_poll( void *data,
183 unsigned char *output, size_t len, size_t *olen )
184 {
185 unsigned long timer = mbedtls_timing_hardclock();
186 ((void) data);
187 *olen = 0;
188
189 if( len < sizeof(unsigned long) )
190 return( 0 );
191
192 memcpy( output, &timer, sizeof(unsigned long) );
193 *olen = sizeof(unsigned long);
194
195 return( 0 );
196 }
197 #endif /* MBEDTLS_TIMING_C */
198
199 #if defined(MBEDTLS_HAVEGE_C)
mbedtls_havege_poll(void * data,unsigned char * output,size_t len,size_t * olen)200 int mbedtls_havege_poll( void *data,
201 unsigned char *output, size_t len, size_t *olen )
202 {
203 mbedtls_havege_state *hs = (mbedtls_havege_state *) data;
204 *olen = 0;
205
206 if( mbedtls_havege_random( hs, output, len ) != 0 )
207 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
208
209 *olen = len;
210
211 return( 0 );
212 }
213 #endif /* MBEDTLS_HAVEGE_C */
214
215 #if defined(MBEDTLS_ENTROPY_NV_SEED)
mbedtls_nv_seed_poll(void * data,unsigned char * output,size_t len,size_t * olen)216 int mbedtls_nv_seed_poll( void *data,
217 unsigned char *output, size_t len, size_t *olen )
218 {
219 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
220 size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
221 ((void) data);
222
223 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
224
225 if( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
226 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
227
228 if( len < use_len )
229 use_len = len;
230
231 memcpy( output, buf, use_len );
232 *olen = use_len;
233
234 return( 0 );
235 }
236 #endif /* MBEDTLS_ENTROPY_NV_SEED */
237
238 #endif /* MBEDTLS_ENTROPY_C */
239