1 /* 2 * Platform-specific and custom entropy polling functions 3 * 4 * Copyright The Mbed TLS Contributors 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 47 #if defined(__linux__) && !defined(_GNU_SOURCE) 48 /* Ensure that syscall() is available even when compiling with -std=c99 */ 49 #define _GNU_SOURCE 50 #endif 51 52 #if !defined(MBEDTLS_CONFIG_FILE) 53 #include "mbedtls/config.h" 54 #else 55 #include MBEDTLS_CONFIG_FILE 56 #endif 57 58 #include <string.h> 59 60 #if defined(MBEDTLS_ENTROPY_C) 61 62 #include "mbedtls/entropy.h" 63 #include "mbedtls/entropy_poll.h" 64 65 #if defined(MBEDTLS_TIMING_C) 66 #include "mbedtls/timing.h" 67 #endif 68 #if defined(MBEDTLS_HAVEGE_C) 69 #include "mbedtls/havege.h" 70 #endif 71 #if defined(MBEDTLS_ENTROPY_NV_SEED) 72 #include "mbedtls/platform.h" 73 #endif 74 75 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY) 76 77 #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \ 78 !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \ 79 !defined(__HAIKU__) 80 #error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h" 81 #endif 82 83 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) 84 85 #if !defined(_WIN32_WINNT) 86 #define _WIN32_WINNT 0x0400 87 #endif 88 #include <windows.h> 89 #include <wincrypt.h> 90 91 int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len, 92 size_t *olen ) 93 { 94 HCRYPTPROV provider; 95 ((void) data); 96 *olen = 0; 97 98 if( CryptAcquireContext( &provider, NULL, NULL, 99 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT ) == FALSE ) 100 { 101 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 102 } 103 104 if( CryptGenRandom( provider, (DWORD) len, output ) == FALSE ) 105 { 106 CryptReleaseContext( provider, 0 ); 107 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 108 } 109 110 CryptReleaseContext( provider, 0 ); 111 *olen = len; 112 113 return( 0 ); 114 } 115 #else /* _WIN32 && !EFIX64 && !EFI32 */ 116 117 /* 118 * Test for Linux getrandom() support. 119 * Since there is no wrapper in the libc yet, use the generic syscall wrapper 120 * available in GNU libc and compatible libc's (eg uClibc). 121 */ 122 #if defined(__linux__) && defined(__GLIBC__) 123 #include <unistd.h> 124 #include <sys/syscall.h> 125 #if defined(SYS_getrandom) 126 #define HAVE_GETRANDOM 127 #include <errno.h> 128 129 static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags ) 130 { 131 /* MemSan cannot understand that the syscall writes to the buffer */ 132 #if defined(__has_feature) 133 #if __has_feature(memory_sanitizer) 134 memset( buf, 0, buflen ); 135 #endif 136 #endif 137 return( syscall( SYS_getrandom, buf, buflen, flags ) ); 138 } 139 #endif /* SYS_getrandom */ 140 #endif /* __linux__ */ 141 142 #include <stdio.h> 143 144 int mbedtls_platform_entropy_poll( void *data, 145 unsigned char *output, size_t len, size_t *olen ) 146 { 147 FILE *file; 148 size_t read_len; 149 int ret; 150 ((void) data); 151 152 #if defined(HAVE_GETRANDOM) 153 ret = getrandom_wrapper( output, len, 0 ); 154 if( ret >= 0 ) 155 { 156 *olen = ret; 157 return( 0 ); 158 } 159 else if( errno != ENOSYS ) 160 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 161 /* Fall through if the system call isn't known. */ 162 #else 163 ((void) ret); 164 #endif /* HAVE_GETRANDOM */ 165 166 *olen = 0; 167 168 file = fopen( "/dev/urandom", "rb" ); 169 if( file == NULL ) 170 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 171 172 read_len = fread( output, 1, len, file ); 173 if( read_len != len ) 174 { 175 fclose( file ); 176 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 177 } 178 179 fclose( file ); 180 *olen = len; 181 182 return( 0 ); 183 } 184 #endif /* _WIN32 && !EFIX64 && !EFI32 */ 185 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */ 186 187 #if defined(MBEDTLS_TEST_NULL_ENTROPY) 188 int mbedtls_null_entropy_poll( void *data, 189 unsigned char *output, size_t len, size_t *olen ) 190 { 191 ((void) data); 192 ((void) output); 193 *olen = 0; 194 195 if( len < sizeof(unsigned char) ) 196 return( 0 ); 197 198 *olen = sizeof(unsigned char); 199 200 return( 0 ); 201 } 202 #endif 203 204 #if defined(MBEDTLS_TIMING_C) 205 int mbedtls_hardclock_poll( void *data, 206 unsigned char *output, size_t len, size_t *olen ) 207 { 208 unsigned long timer = mbedtls_timing_hardclock(); 209 ((void) data); 210 *olen = 0; 211 212 if( len < sizeof(unsigned long) ) 213 return( 0 ); 214 215 memcpy( output, &timer, sizeof(unsigned long) ); 216 *olen = sizeof(unsigned long); 217 218 return( 0 ); 219 } 220 #endif /* MBEDTLS_TIMING_C */ 221 222 #if defined(MBEDTLS_HAVEGE_C) 223 int mbedtls_havege_poll( void *data, 224 unsigned char *output, size_t len, size_t *olen ) 225 { 226 mbedtls_havege_state *hs = (mbedtls_havege_state *) data; 227 *olen = 0; 228 229 if( mbedtls_havege_random( hs, output, len ) != 0 ) 230 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 231 232 *olen = len; 233 234 return( 0 ); 235 } 236 #endif /* MBEDTLS_HAVEGE_C */ 237 238 #if defined(MBEDTLS_ENTROPY_NV_SEED) 239 int mbedtls_nv_seed_poll( void *data, 240 unsigned char *output, size_t len, size_t *olen ) 241 { 242 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; 243 size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE; 244 ((void) data); 245 246 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE ); 247 248 if( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 ) 249 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 250 251 if( len < use_len ) 252 use_len = len; 253 254 memcpy( output, buf, use_len ); 255 *olen = use_len; 256 257 return( 0 ); 258 } 259 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 260 261 #endif /* MBEDTLS_ENTROPY_C */ 262