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/*
* Platform-specific and custom entropy polling functions
*
* Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_ENTROPY_C)
#include "mbedtls/entropy.h"
#include "mbedtls/entropy_poll.h"
#if defined(MBEDTLS_TIMING_C)
#include <string.h>
#include "mbedtls/timing.h"
#endif
#if defined(MBEDTLS_HAVEGE_C)
#include "mbedtls/havege.h"
#endif
#if defined(MBEDTLS_ENTROPY_NV_SEED)
#include "mbedtls/platform.h"
#endif
#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
#if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
!defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__)
#error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h"
#endif
#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
#if !defined(_WIN32_WINNT)
#define _WIN32_WINNT 0x0400
#endif
#include <windows.h>
#include <bcrypt.h>
#if defined(_MSC_VER) && _MSC_VER <= 1600
/* Visual Studio 2010 and earlier issue a warning when both <stdint.h> and
* <intsafe.h> are included, as they redefine a number of <TYPE>_MAX constants.
* These constants are guaranteed to be the same, though, so we suppress the
* warning when including intsafe.h.
*/
#pragma warning( push )
#pragma warning( disable : 4005 )
#endif
#include <intsafe.h>
#if defined(_MSC_VER) && _MSC_VER <= 1600
#pragma warning( pop )
#endif
int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len,
size_t *olen )
{
ULONG len_as_ulong = 0;
((void) data);
*olen = 0;
/*
* BCryptGenRandom takes ULONG for size, which is smaller than size_t on
* 64-bit Windows platforms. Ensure len's value can be safely converted into
* a ULONG.
*/
if ( FAILED( SizeTToULong( len, &len_as_ulong ) ) )
{
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
}
if ( !BCRYPT_SUCCESS( BCryptGenRandom( NULL, output, len_as_ulong, BCRYPT_USE_SYSTEM_PREFERRED_RNG ) ) )
{
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
}
*olen = len;
return( 0 );
}
#else /* _WIN32 && !EFIX64 && !EFI32 */
/*
* Test for Linux getrandom() support.
* Since there is no wrapper in the libc yet, use the generic syscall wrapper
* available in GNU libc and compatible libc's (eg uClibc).
*/
#if defined(__linux__) && defined(__GLIBC__)
#include <unistd.h>
#include <sys/syscall.h>
#if defined(SYS_getrandom)
#define HAVE_GETRANDOM
static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags )
{
/* MemSan cannot understand that the syscall writes to the buffer */
#if defined(__has_feature)
#if __has_feature(memory_sanitizer)
memset( buf, 0, buflen );
#endif
#endif
return( syscall( SYS_getrandom, buf, buflen, flags ) );
}
#include <sys/utsname.h>
/* Check if version is at least 3.17.0 */
static int check_version_3_17_plus( void )
{
int minor;
struct utsname un;
const char *ver;
/* Get version information */
uname(&un);
ver = un.release;
/* Check major version; assume a single digit */
if( ver[0] < '3' || ver[0] > '9' || ver [1] != '.' )
return( -1 );
if( ver[0] - '0' > 3 )
return( 0 );
/* Ok, so now we know major == 3, check minor.
* Assume 1 or 2 digits. */
if( ver[2] < '0' || ver[2] > '9' )
return( -1 );
minor = ver[2] - '0';
if( ver[3] >= '0' && ver[3] <= '9' )
minor = 10 * minor + ver[3] - '0';
else if( ver [3] != '.' )
return( -1 );
if( minor < 17 )
return( -1 );
return( 0 );
}
static int has_getrandom = -1;
#endif /* SYS_getrandom */
#endif /* __linux__ */
#include <stdio.h>
int mbedtls_platform_entropy_poll( void *data,
unsigned char *output, size_t len, size_t *olen )
{
FILE *file;
size_t read_len;
((void) data);
#if defined(HAVE_GETRANDOM)
if( has_getrandom == -1 )
has_getrandom = ( check_version_3_17_plus() == 0 );
if( has_getrandom )
{
int ret;
if( ( ret = getrandom_wrapper( output, len, 0 ) ) < 0 )
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
*olen = ret;
return( 0 );
}
#endif /* HAVE_GETRANDOM */
*olen = 0;
file = fopen( "/dev/urandom", "rb" );
if( file == NULL )
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
read_len = fread( output, 1, len, file );
if( read_len != len )
{
fclose( file );
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
}
fclose( file );
*olen = len;
return( 0 );
}
#endif /* _WIN32 && !EFIX64 && !EFI32 */
#endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
#if defined(MBEDTLS_TEST_NULL_ENTROPY)
int mbedtls_null_entropy_poll( void *data,
unsigned char *output, size_t len, size_t *olen )
{
((void) data);
((void) output);
*olen = 0;
if( len < sizeof(unsigned char) )
return( 0 );
*olen = sizeof(unsigned char);
return( 0 );
}
#endif
#if defined(MBEDTLS_TIMING_C)
int mbedtls_hardclock_poll( void *data,
unsigned char *output, size_t len, size_t *olen )
{
unsigned long timer = mbedtls_timing_hardclock();
((void) data);
*olen = 0;
if( len < sizeof(unsigned long) )
return( 0 );
memcpy( output, &timer, sizeof(unsigned long) );
*olen = sizeof(unsigned long);
return( 0 );
}
#endif /* MBEDTLS_TIMING_C */
#if defined(MBEDTLS_HAVEGE_C)
int mbedtls_havege_poll( void *data,
unsigned char *output, size_t len, size_t *olen )
{
mbedtls_havege_state *hs = (mbedtls_havege_state *) data;
*olen = 0;
if( mbedtls_havege_random( hs, output, len ) != 0 )
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
*olen = len;
return( 0 );
}
#endif /* MBEDTLS_HAVEGE_C */
#if defined(MBEDTLS_ENTROPY_NV_SEED)
int mbedtls_nv_seed_poll( void *data,
unsigned char *output, size_t len, size_t *olen )
{
unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
((void) data);
memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
if( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
if( len < use_len )
use_len = len;
memcpy( output, buf, use_len );
*olen = use_len;
return( 0 );
}
#endif /* MBEDTLS_ENTROPY_NV_SEED */
#endif /* MBEDTLS_ENTROPY_C */
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