1 // SPDX-License-Identifier: Apache-2.0 2 /* 3 * Platform-specific and custom entropy polling functions 4 * 5 * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved 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(__linux__) 23 /* Ensure that syscall() is available even when compiling with -std=c99 */ 24 #define _GNU_SOURCE 25 #endif 26 27 #if !defined(MBEDTLS_CONFIG_FILE) 28 #include "mbedtls/config.h" 29 #else 30 #include MBEDTLS_CONFIG_FILE 31 #endif 32 33 #include <string.h> 34 35 #if defined(MBEDTLS_ENTROPY_C) 36 37 #include "mbedtls/entropy.h" 38 #include "mbedtls/entropy_poll.h" 39 #include "mbedtls/error.h" 40 41 #if defined(MBEDTLS_TIMING_C) 42 #include "mbedtls/timing.h" 43 #endif 44 #if defined(MBEDTLS_HAVEGE_C) 45 #include "mbedtls/havege.h" 46 #endif 47 #if defined(MBEDTLS_ENTROPY_NV_SEED) 48 #include "mbedtls/platform.h" 49 #endif 50 51 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY) 52 53 #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \ 54 !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \ 55 !defined(__HAIKU__) 56 #error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h" 57 #endif 58 59 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) 60 61 #if !defined(_WIN32_WINNT) 62 #define _WIN32_WINNT 0x0400 63 #endif 64 #include <windows.h> 65 #include <wincrypt.h> 66 67 int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len, 68 size_t *olen ) 69 { 70 HCRYPTPROV provider; 71 ((void) data); 72 *olen = 0; 73 74 if( CryptAcquireContext( &provider, NULL, NULL, 75 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT ) == FALSE ) 76 { 77 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 78 } 79 80 if( CryptGenRandom( provider, (DWORD) len, output ) == FALSE ) 81 { 82 CryptReleaseContext( provider, 0 ); 83 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 84 } 85 86 CryptReleaseContext( provider, 0 ); 87 *olen = len; 88 89 return( 0 ); 90 } 91 #else /* _WIN32 && !EFIX64 && !EFI32 */ 92 93 /* 94 * Test for Linux getrandom() support. 95 * Since there is no wrapper in the libc yet, use the generic syscall wrapper 96 * available in GNU libc and compatible libc's (eg uClibc). 97 */ 98 #if defined(__linux__) && defined(__GLIBC__) 99 #include <unistd.h> 100 #include <sys/syscall.h> 101 #if defined(SYS_getrandom) 102 #define HAVE_GETRANDOM 103 #include <errno.h> 104 105 static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags ) 106 { 107 /* MemSan cannot understand that the syscall writes to the buffer */ 108 #if defined(__has_feature) 109 #if __has_feature(memory_sanitizer) 110 memset( buf, 0, buflen ); 111 #endif 112 #endif 113 return( syscall( SYS_getrandom, buf, buflen, flags ) ); 114 } 115 #endif /* SYS_getrandom */ 116 #endif /* __linux__ */ 117 118 #include <stdio.h> 119 120 int mbedtls_platform_entropy_poll( void *data, 121 unsigned char *output, size_t len, size_t *olen ) 122 { 123 FILE *file; 124 size_t read_len; 125 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 126 ((void) data); 127 128 #if defined(HAVE_GETRANDOM) 129 ret = getrandom_wrapper( output, len, 0 ); 130 if( ret >= 0 ) 131 { 132 *olen = ret; 133 return( 0 ); 134 } 135 else if( errno != ENOSYS ) 136 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 137 /* Fall through if the system call isn't known. */ 138 #else 139 ((void) ret); 140 #endif /* HAVE_GETRANDOM */ 141 142 *olen = 0; 143 144 file = fopen( "/dev/urandom", "rb" ); 145 if( file == NULL ) 146 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 147 148 read_len = fread( output, 1, len, file ); 149 if( read_len != len ) 150 { 151 fclose( file ); 152 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 153 } 154 155 fclose( file ); 156 *olen = len; 157 158 return( 0 ); 159 } 160 #endif /* _WIN32 && !EFIX64 && !EFI32 */ 161 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */ 162 163 #if defined(MBEDTLS_TEST_NULL_ENTROPY) 164 int mbedtls_null_entropy_poll( void *data, 165 unsigned char *output, size_t len, size_t *olen ) 166 { 167 ((void) data); 168 ((void) output); 169 *olen = 0; 170 171 if( len < sizeof(unsigned char) ) 172 return( 0 ); 173 174 *olen = sizeof(unsigned char); 175 176 return( 0 ); 177 } 178 #endif 179 180 #if defined(MBEDTLS_TIMING_C) 181 int mbedtls_hardclock_poll( void *data, 182 unsigned char *output, size_t len, size_t *olen ) 183 { 184 unsigned long timer = mbedtls_timing_hardclock(); 185 ((void) data); 186 *olen = 0; 187 188 if( len < sizeof(unsigned long) ) 189 return( 0 ); 190 191 memcpy( output, &timer, sizeof(unsigned long) ); 192 *olen = sizeof(unsigned long); 193 194 return( 0 ); 195 } 196 #endif /* MBEDTLS_TIMING_C */ 197 198 #if defined(MBEDTLS_HAVEGE_C) 199 int mbedtls_havege_poll( void *data, 200 unsigned char *output, size_t len, size_t *olen ) 201 { 202 mbedtls_havege_state *hs = (mbedtls_havege_state *) data; 203 *olen = 0; 204 205 if( mbedtls_havege_random( hs, output, len ) != 0 ) 206 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 207 208 *olen = len; 209 210 return( 0 ); 211 } 212 #endif /* MBEDTLS_HAVEGE_C */ 213 214 #if defined(MBEDTLS_ENTROPY_NV_SEED) 215 int mbedtls_nv_seed_poll( void *data, 216 unsigned char *output, size_t len, size_t *olen ) 217 { 218 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; 219 size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE; 220 ((void) data); 221 222 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE ); 223 224 if( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 ) 225 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 226 227 if( len < use_len ) 228 use_len = len; 229 230 memcpy( output, buf, use_len ); 231 *olen = use_len; 232 233 return( 0 ); 234 } 235 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 236 237 #endif /* MBEDTLS_ENTROPY_C */ 238