entropy_poll.c 5.7 KB

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  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. #if !defined(MBEDTLS_CONFIG_FILE)
  22. #include "mbedtls/config.h"
  23. #else
  24. #include MBEDTLS_CONFIG_FILE
  25. #endif
  26. #if defined(MBEDTLS_ENTROPY_C)
  27. #include "mbedtls/entropy.h"
  28. #include "mbedtls/entropy_poll.h"
  29. #if defined(MBEDTLS_TIMING_C)
  30. #include <string.h>
  31. #include "mbedtls/timing.h"
  32. #endif
  33. #if defined(MBEDTLS_HAVEGE_C)
  34. #include "mbedtls/havege.h"
  35. #endif
  36. #if defined(MBEDTLS_ENTROPY_NV_SEED)
  37. #include "mbedtls/platform.h"
  38. #endif
  39. #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
  40. #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
  41. !defined(__APPLE__) && !defined(_WIN32)
  42. #error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h"
  43. #endif
  44. #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
  45. #if !defined(_WIN32_WINNT)
  46. #define _WIN32_WINNT 0x0400
  47. #endif
  48. #include <windows.h>
  49. #include <wincrypt.h>
  50. int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len,
  51. size_t *olen )
  52. {
  53. HCRYPTPROV provider;
  54. ((void) data);
  55. *olen = 0;
  56. if( CryptAcquireContext( &provider, NULL, NULL,
  57. PROV_RSA_FULL, CRYPT_VERIFYCONTEXT ) == FALSE )
  58. {
  59. return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  60. }
  61. if( CryptGenRandom( provider, (DWORD) len, output ) == FALSE )
  62. {
  63. CryptReleaseContext( provider, 0 );
  64. return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  65. }
  66. CryptReleaseContext( provider, 0 );
  67. *olen = len;
  68. return( 0 );
  69. }
  70. #else /* _WIN32 && !EFIX64 && !EFI32 */
  71. /*
  72. * Test for Linux getrandom() support.
  73. * Since there is no wrapper in the libc yet, use the generic syscall wrapper
  74. * available in GNU libc and compatible libc's (eg uClibc).
  75. */
  76. #if defined(__linux__) && defined(__GLIBC__)
  77. #include <unistd.h>
  78. #include <sys/syscall.h>
  79. #if defined(SYS_getrandom)
  80. #define HAVE_GETRANDOM
  81. #include <errno.h>
  82. static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags )
  83. {
  84. /* MemSan cannot understand that the syscall writes to the buffer */
  85. #if defined(__has_feature)
  86. #if __has_feature(memory_sanitizer)
  87. memset( buf, 0, buflen );
  88. #endif
  89. #endif
  90. return( syscall( SYS_getrandom, buf, buflen, flags ) );
  91. }
  92. #endif /* SYS_getrandom */
  93. #endif /* __linux__ */
  94. #include <stdio.h>
  95. int mbedtls_platform_entropy_poll( void *data,
  96. unsigned char *output, size_t len, size_t *olen )
  97. {
  98. FILE *file;
  99. size_t read_len;
  100. int ret;
  101. ((void) data);
  102. #if defined(HAVE_GETRANDOM)
  103. ret = getrandom_wrapper( output, len, 0 );
  104. if( ret >= 0 )
  105. {
  106. *olen = ret;
  107. return( 0 );
  108. }
  109. else if( errno != ENOSYS )
  110. return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  111. /* Fall through if the system call isn't known. */
  112. #else
  113. ((void) ret);
  114. #endif /* HAVE_GETRANDOM */
  115. *olen = 0;
  116. file = fopen( "/dev/urandom", "rb" );
  117. if( file == NULL )
  118. return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  119. read_len = fread( output, 1, len, file );
  120. if( read_len != len )
  121. {
  122. fclose( file );
  123. return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  124. }
  125. fclose( file );
  126. *olen = len;
  127. return( 0 );
  128. }
  129. #endif /* _WIN32 && !EFIX64 && !EFI32 */
  130. #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
  131. #if defined(MBEDTLS_TEST_NULL_ENTROPY)
  132. int mbedtls_null_entropy_poll( void *data,
  133. unsigned char *output, size_t len, size_t *olen )
  134. {
  135. ((void) data);
  136. ((void) output);
  137. *olen = 0;
  138. if( len < sizeof(unsigned char) )
  139. return( 0 );
  140. *olen = sizeof(unsigned char);
  141. return( 0 );
  142. }
  143. #endif
  144. #if defined(MBEDTLS_TIMING_C)
  145. int mbedtls_hardclock_poll( void *data,
  146. unsigned char *output, size_t len, size_t *olen )
  147. {
  148. unsigned long timer = mbedtls_timing_hardclock();
  149. ((void) data);
  150. *olen = 0;
  151. if( len < sizeof(unsigned long) )
  152. return( 0 );
  153. memcpy( output, &timer, sizeof(unsigned long) );
  154. *olen = sizeof(unsigned long);
  155. return( 0 );
  156. }
  157. #endif /* MBEDTLS_TIMING_C */
  158. #if defined(MBEDTLS_HAVEGE_C)
  159. int mbedtls_havege_poll( void *data,
  160. unsigned char *output, size_t len, size_t *olen )
  161. {
  162. mbedtls_havege_state *hs = (mbedtls_havege_state *) data;
  163. *olen = 0;
  164. if( mbedtls_havege_random( hs, output, len ) != 0 )
  165. return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  166. *olen = len;
  167. return( 0 );
  168. }
  169. #endif /* MBEDTLS_HAVEGE_C */
  170. #if defined(MBEDTLS_ENTROPY_NV_SEED)
  171. int mbedtls_nv_seed_poll( void *data,
  172. unsigned char *output, size_t len, size_t *olen )
  173. {
  174. unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
  175. size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
  176. ((void) data);
  177. memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
  178. if( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
  179. return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  180. if( len < use_len )
  181. use_len = len;
  182. memcpy( output, buf, use_len );
  183. *olen = use_len;
  184. return( 0 );
  185. }
  186. #endif /* MBEDTLS_ENTROPY_NV_SEED */
  187. #endif /* MBEDTLS_ENTROPY_C */