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 OR GPL-2.0-or-later 6 * 7 * This file is provided under the Apache License 2.0, or the 8 * GNU General Public License v2.0 or later. 9 * 10 * ********** 11 * Apache License 2.0: 12 * 13 * Licensed under the Apache License, Version 2.0 (the "License"); you may 14 * not use this file except in compliance with the License. 15 * You may obtain a copy of the License at 16 * 17 * http://www.apache.org/licenses/LICENSE-2.0 18 * 19 * Unless required by applicable law or agreed to in writing, software 20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 22 * See the License for the specific language governing permissions and 23 * limitations under the License. 24 * 25 * ********** 26 * 27 * ********** 28 * GNU General Public License v2.0 or later: 29 * 30 * This program is free software; you can redistribute it and/or modify 31 * it under the terms of the GNU General Public License as published by 32 * the Free Software Foundation; either version 2 of the License, or 33 * (at your option) any later version. 34 * 35 * This program is distributed in the hope that it will be useful, 36 * but WITHOUT ANY WARRANTY; without even the implied warranty of 37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 38 * GNU General Public License for more details. 39 * 40 * You should have received a copy of the GNU General Public License along 41 * with this program; if not, write to the Free Software Foundation, Inc., 42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 43 * 44 * ********** 45 * 46 * This file is part of mbed TLS (https://tls.mbed.org) 47 */ 48 49 #if !defined(MBEDTLS_CONFIG_FILE) 50 #include "mbedtls/config.h" 51 #else 52 #include MBEDTLS_CONFIG_FILE 53 #endif 54 55 #if defined(MBEDTLS_ENTROPY_C) 56 57 #include "mbedtls/entropy.h" 58 #include "mbedtls/entropy_poll.h" 59 60 #if defined(MBEDTLS_TIMING_C) 61 #include <string.h> 62 #include "mbedtls/timing.h" 63 #endif 64 #if defined(MBEDTLS_HAVEGE_C) 65 #include "mbedtls/havege.h" 66 #endif 67 #if defined(MBEDTLS_ENTROPY_NV_SEED) 68 #include "mbedtls/platform.h" 69 #endif 70 71 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY) 72 73 #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \ 74 !defined(__APPLE__) && !defined(_WIN32) 75 #error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h" 76 #endif 77 78 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) 79 80 #if !defined(_WIN32_WINNT) 81 #define _WIN32_WINNT 0x0400 82 #endif 83 #include <windows.h> 84 #include <wincrypt.h> 85 86 int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len, 87 size_t *olen ) 88 { 89 HCRYPTPROV provider; 90 ((void) data); 91 *olen = 0; 92 93 if( CryptAcquireContext( &provider, NULL, NULL, 94 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT ) == FALSE ) 95 { 96 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 97 } 98 99 if( CryptGenRandom( provider, (DWORD) len, output ) == FALSE ) 100 { 101 CryptReleaseContext( provider, 0 ); 102 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 103 } 104 105 CryptReleaseContext( provider, 0 ); 106 *olen = len; 107 108 return( 0 ); 109 } 110 #else /* _WIN32 && !EFIX64 && !EFI32 */ 111 112 /* 113 * Test for Linux getrandom() support. 114 * Since there is no wrapper in the libc yet, use the generic syscall wrapper 115 * available in GNU libc and compatible libc's (eg uClibc). 116 */ 117 #if defined(__linux__) && defined(__GLIBC__) 118 #include <unistd.h> 119 #include <sys/syscall.h> 120 #if defined(SYS_getrandom) 121 #define HAVE_GETRANDOM 122 #include <errno.h> 123 124 static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags ) 125 { 126 /* MemSan cannot understand that the syscall writes to the buffer */ 127 #if defined(__has_feature) 128 #if __has_feature(memory_sanitizer) 129 memset( buf, 0, buflen ); 130 #endif 131 #endif 132 return( syscall( SYS_getrandom, buf, buflen, flags ) ); 133 } 134 #endif /* SYS_getrandom */ 135 #endif /* __linux__ */ 136 137 #include <stdio.h> 138 139 int mbedtls_platform_entropy_poll( void *data, 140 unsigned char *output, size_t len, size_t *olen ) 141 { 142 FILE *file; 143 size_t read_len; 144 int ret; 145 ((void) data); 146 147 #if defined(HAVE_GETRANDOM) 148 ret = getrandom_wrapper( output, len, 0 ); 149 if( ret >= 0 ) 150 { 151 *olen = ret; 152 return( 0 ); 153 } 154 else if( errno != ENOSYS ) 155 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 156 /* Fall through if the system call isn't known. */ 157 #else 158 ((void) ret); 159 #endif /* HAVE_GETRANDOM */ 160 161 *olen = 0; 162 163 file = fopen( "/dev/urandom", "rb" ); 164 if( file == NULL ) 165 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 166 167 read_len = fread( output, 1, len, file ); 168 if( read_len != len ) 169 { 170 fclose( file ); 171 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 172 } 173 174 fclose( file ); 175 *olen = len; 176 177 return( 0 ); 178 } 179 #endif /* _WIN32 && !EFIX64 && !EFI32 */ 180 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */ 181 182 #if defined(MBEDTLS_TEST_NULL_ENTROPY) 183 int mbedtls_null_entropy_poll( void *data, 184 unsigned char *output, size_t len, size_t *olen ) 185 { 186 ((void) data); 187 ((void) output); 188 *olen = 0; 189 190 if( len < sizeof(unsigned char) ) 191 return( 0 ); 192 193 *olen = sizeof(unsigned char); 194 195 return( 0 ); 196 } 197 #endif 198 199 #if defined(MBEDTLS_TIMING_C) 200 int mbedtls_hardclock_poll( void *data, 201 unsigned char *output, size_t len, size_t *olen ) 202 { 203 unsigned long timer = mbedtls_timing_hardclock(); 204 ((void) data); 205 *olen = 0; 206 207 if( len < sizeof(unsigned long) ) 208 return( 0 ); 209 210 memcpy( output, &timer, sizeof(unsigned long) ); 211 *olen = sizeof(unsigned long); 212 213 return( 0 ); 214 } 215 #endif /* MBEDTLS_TIMING_C */ 216 217 #if defined(MBEDTLS_HAVEGE_C) 218 int mbedtls_havege_poll( void *data, 219 unsigned char *output, size_t len, size_t *olen ) 220 { 221 mbedtls_havege_state *hs = (mbedtls_havege_state *) data; 222 *olen = 0; 223 224 if( mbedtls_havege_random( hs, output, len ) != 0 ) 225 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 226 227 *olen = len; 228 229 return( 0 ); 230 } 231 #endif /* MBEDTLS_HAVEGE_C */ 232 233 #if defined(MBEDTLS_ENTROPY_NV_SEED) 234 int mbedtls_nv_seed_poll( void *data, 235 unsigned char *output, size_t len, size_t *olen ) 236 { 237 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; 238 size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE; 239 ((void) data); 240 241 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE ); 242 243 if( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 ) 244 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 245 246 if( len < use_len ) 247 use_len = len; 248 249 memcpy( output, buf, use_len ); 250 *olen = use_len; 251 252 return( 0 ); 253 } 254 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 255 256 #endif /* MBEDTLS_ENTROPY_C */ 257