655 lines
18 KiB
C
655 lines
18 KiB
C
/*
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* Entropy accumulator implementation
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*
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* Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of mbed TLS (https://tls.mbed.org)
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*/
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#if defined(MBEDTLS_ENTROPY_C)
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#if defined(MBEDTLS_TEST_NULL_ENTROPY)
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#warning "**** WARNING! MBEDTLS_TEST_NULL_ENTROPY defined! "
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#warning "**** THIS BUILD HAS NO DEFINED ENTROPY SOURCES "
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#warning "**** THIS BUILD IS *NOT* SUITABLE FOR PRODUCTION USE "
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#endif
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#include "mbedtls/entropy.h"
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#include "mbedtls/entropy_poll.h"
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#include <string.h>
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#if defined(MBEDTLS_FS_IO)
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#include <stdio.h>
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#endif
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#if defined(MBEDTLS_ENTROPY_NV_SEED)
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#include "mbedtls/platform.h"
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#endif
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#if defined(MBEDTLS_SELF_TEST)
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#if defined(MBEDTLS_PLATFORM_C)
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#include "mbedtls/platform.h"
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#else
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#include <stdio.h>
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#define mbedtls_printf printf
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#endif /* MBEDTLS_PLATFORM_C */
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#endif /* MBEDTLS_SELF_TEST */
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#if defined(MBEDTLS_HAVEGE_C)
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#include "mbedtls/havege.h"
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#endif
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/* Implementation that should never be optimized out by the compiler */
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static void mbedtls_zeroize( void *v, size_t n ) {
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volatile unsigned char *p = v; while( n-- ) *p++ = 0;
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}
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#define ENTROPY_MAX_LOOP 256 /**< Maximum amount to loop before error */
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void mbedtls_entropy_init( mbedtls_entropy_context *ctx )
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{
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memset( ctx, 0, sizeof(mbedtls_entropy_context) );
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#if defined(MBEDTLS_THREADING_C)
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mbedtls_mutex_init( &ctx->mutex );
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#endif
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#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
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mbedtls_sha512_starts( &ctx->accumulator, 0 );
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#else
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mbedtls_sha256_starts( &ctx->accumulator, 0 );
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#endif
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#if defined(MBEDTLS_HAVEGE_C)
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mbedtls_havege_init( &ctx->havege_data );
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#endif
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#if defined(MBEDTLS_TEST_NULL_ENTROPY)
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mbedtls_entropy_add_source( ctx, mbedtls_null_entropy_poll, NULL,
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1, MBEDTLS_ENTROPY_SOURCE_STRONG );
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#endif
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#if !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES)
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#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
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mbedtls_entropy_add_source( ctx, mbedtls_platform_entropy_poll, NULL,
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MBEDTLS_ENTROPY_MIN_PLATFORM,
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MBEDTLS_ENTROPY_SOURCE_STRONG );
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#endif
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#if defined(MBEDTLS_TIMING_C)
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mbedtls_entropy_add_source( ctx, mbedtls_hardclock_poll, NULL,
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MBEDTLS_ENTROPY_MIN_HARDCLOCK,
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MBEDTLS_ENTROPY_SOURCE_WEAK );
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#endif
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#if defined(MBEDTLS_HAVEGE_C)
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mbedtls_entropy_add_source( ctx, mbedtls_havege_poll, &ctx->havege_data,
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MBEDTLS_ENTROPY_MIN_HAVEGE,
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MBEDTLS_ENTROPY_SOURCE_STRONG );
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#endif
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#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
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mbedtls_entropy_add_source( ctx, mbedtls_hardware_poll, NULL,
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MBEDTLS_ENTROPY_MIN_HARDWARE,
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MBEDTLS_ENTROPY_SOURCE_STRONG );
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#endif
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#if defined(MBEDTLS_ENTROPY_NV_SEED)
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mbedtls_entropy_add_source( ctx, mbedtls_nv_seed_poll, NULL,
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MBEDTLS_ENTROPY_BLOCK_SIZE,
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MBEDTLS_ENTROPY_SOURCE_STRONG );
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#endif
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#endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */
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}
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void mbedtls_entropy_free( mbedtls_entropy_context *ctx )
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{
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#if defined(MBEDTLS_HAVEGE_C)
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mbedtls_havege_free( &ctx->havege_data );
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#endif
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#if defined(MBEDTLS_THREADING_C)
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mbedtls_mutex_free( &ctx->mutex );
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#endif
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mbedtls_zeroize( ctx, sizeof( mbedtls_entropy_context ) );
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}
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int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
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mbedtls_entropy_f_source_ptr f_source, void *p_source,
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size_t threshold, int strong )
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{
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int index, ret = 0;
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#if defined(MBEDTLS_THREADING_C)
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if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
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return( ret );
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#endif
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index = ctx->source_count;
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if( index >= MBEDTLS_ENTROPY_MAX_SOURCES )
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{
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ret = MBEDTLS_ERR_ENTROPY_MAX_SOURCES;
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goto exit;
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}
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ctx->source[index].f_source = f_source;
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ctx->source[index].p_source = p_source;
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ctx->source[index].threshold = threshold;
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ctx->source[index].strong = strong;
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ctx->source_count++;
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exit:
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#if defined(MBEDTLS_THREADING_C)
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if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
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return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
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#endif
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return( ret );
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}
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/*
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* Entropy accumulator update
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*/
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static int entropy_update( mbedtls_entropy_context *ctx, unsigned char source_id,
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const unsigned char *data, size_t len )
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{
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unsigned char header[2];
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unsigned char tmp[MBEDTLS_ENTROPY_BLOCK_SIZE];
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size_t use_len = len;
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const unsigned char *p = data;
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if( use_len > MBEDTLS_ENTROPY_BLOCK_SIZE )
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{
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#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
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mbedtls_sha512( data, len, tmp, 0 );
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#else
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mbedtls_sha256( data, len, tmp, 0 );
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#endif
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p = tmp;
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use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
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}
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header[0] = source_id;
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header[1] = use_len & 0xFF;
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#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
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mbedtls_sha512_update( &ctx->accumulator, header, 2 );
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mbedtls_sha512_update( &ctx->accumulator, p, use_len );
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#else
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mbedtls_sha256_update( &ctx->accumulator, header, 2 );
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mbedtls_sha256_update( &ctx->accumulator, p, use_len );
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#endif
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return( 0 );
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}
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int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,
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const unsigned char *data, size_t len )
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{
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int ret;
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#if defined(MBEDTLS_THREADING_C)
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if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
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return( ret );
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#endif
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ret = entropy_update( ctx, MBEDTLS_ENTROPY_SOURCE_MANUAL, data, len );
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#if defined(MBEDTLS_THREADING_C)
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if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
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return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
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#endif
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return( ret );
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}
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/*
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* Run through the different sources to add entropy to our accumulator
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*/
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static int entropy_gather_internal( mbedtls_entropy_context *ctx )
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{
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int ret, i, have_one_strong = 0;
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unsigned char buf[MBEDTLS_ENTROPY_MAX_GATHER];
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size_t olen;
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if( ctx->source_count == 0 )
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return( MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED );
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/*
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* Run through our entropy sources
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*/
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for( i = 0; i < ctx->source_count; i++ )
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{
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if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG )
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have_one_strong = 1;
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olen = 0;
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if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source,
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buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen ) ) != 0 )
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{
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return( ret );
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}
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/*
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* Add if we actually gathered something
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*/
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if( olen > 0 )
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{
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entropy_update( ctx, (unsigned char) i, buf, olen );
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ctx->source[i].size += olen;
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}
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}
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if( have_one_strong == 0 )
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return( MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE );
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return( 0 );
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}
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/*
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* Thread-safe wrapper for entropy_gather_internal()
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*/
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int mbedtls_entropy_gather( mbedtls_entropy_context *ctx )
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{
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int ret;
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#if defined(MBEDTLS_THREADING_C)
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if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
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return( ret );
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#endif
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ret = entropy_gather_internal( ctx );
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#if defined(MBEDTLS_THREADING_C)
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if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
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return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
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#endif
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return( ret );
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}
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int mbedtls_entropy_func( void *data, unsigned char *output, size_t len )
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{
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int ret, count = 0, i, done;
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mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data;
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unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
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if( len > MBEDTLS_ENTROPY_BLOCK_SIZE )
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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#if defined(MBEDTLS_ENTROPY_NV_SEED)
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/* Update the NV entropy seed before generating any entropy for outside
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* use.
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*/
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if( ctx->initial_entropy_run == 0 )
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{
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ctx->initial_entropy_run = 1;
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if( ( ret = mbedtls_entropy_update_nv_seed( ctx ) ) != 0 )
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return( ret );
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}
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#endif
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#if defined(MBEDTLS_THREADING_C)
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if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
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return( ret );
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#endif
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/*
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* Always gather extra entropy before a call
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*/
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do
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{
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if( count++ > ENTROPY_MAX_LOOP )
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{
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ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
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goto exit;
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}
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if( ( ret = entropy_gather_internal( ctx ) ) != 0 )
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goto exit;
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done = 1;
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for( i = 0; i < ctx->source_count; i++ )
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if( ctx->source[i].size < ctx->source[i].threshold )
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done = 0;
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}
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while( ! done );
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memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
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#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
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mbedtls_sha512_finish( &ctx->accumulator, buf );
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/*
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* Reset accumulator and counters and recycle existing entropy
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*/
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memset( &ctx->accumulator, 0, sizeof( mbedtls_sha512_context ) );
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mbedtls_sha512_starts( &ctx->accumulator, 0 );
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mbedtls_sha512_update( &ctx->accumulator, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
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/*
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* Perform second SHA-512 on entropy
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*/
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mbedtls_sha512( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, buf, 0 );
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#else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
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mbedtls_sha256_finish( &ctx->accumulator, buf );
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/*
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* Reset accumulator and counters and recycle existing entropy
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*/
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memset( &ctx->accumulator, 0, sizeof( mbedtls_sha256_context ) );
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mbedtls_sha256_starts( &ctx->accumulator, 0 );
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mbedtls_sha256_update( &ctx->accumulator, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
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/*
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* Perform second SHA-256 on entropy
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*/
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mbedtls_sha256( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, buf, 0 );
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#endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
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for( i = 0; i < ctx->source_count; i++ )
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ctx->source[i].size = 0;
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memcpy( output, buf, len );
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ret = 0;
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exit:
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#if defined(MBEDTLS_THREADING_C)
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if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
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return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
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#endif
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return( ret );
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}
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#if defined(MBEDTLS_ENTROPY_NV_SEED)
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int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx )
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{
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int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
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unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ];
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/* Read new seed and write it to NV */
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if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
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return( ret );
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if( mbedtls_nv_seed_write( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
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return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
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/* Manually update the remaining stream with a separator value to diverge */
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memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
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mbedtls_entropy_update_manual( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
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return( 0 );
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}
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#endif /* MBEDTLS_ENTROPY_NV_SEED */
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#if defined(MBEDTLS_FS_IO)
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int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path )
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{
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int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
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FILE *f;
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unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
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if( ( f = fopen( path, "wb" ) ) == NULL )
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return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
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if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
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goto exit;
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if( fwrite( buf, 1, MBEDTLS_ENTROPY_BLOCK_SIZE, f ) != MBEDTLS_ENTROPY_BLOCK_SIZE )
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{
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ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
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goto exit;
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}
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ret = 0;
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exit:
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fclose( f );
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return( ret );
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}
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int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path )
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{
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FILE *f;
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size_t n;
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unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ];
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if( ( f = fopen( path, "rb" ) ) == NULL )
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return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
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fseek( f, 0, SEEK_END );
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n = (size_t) ftell( f );
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fseek( f, 0, SEEK_SET );
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if( n > MBEDTLS_ENTROPY_MAX_SEED_SIZE )
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n = MBEDTLS_ENTROPY_MAX_SEED_SIZE;
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if( fread( buf, 1, n, f ) != n )
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{
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fclose( f );
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return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
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}
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fclose( f );
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mbedtls_entropy_update_manual( ctx, buf, n );
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return( mbedtls_entropy_write_seed_file( ctx, path ) );
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}
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#endif /* MBEDTLS_FS_IO */
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#if defined(MBEDTLS_SELF_TEST)
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#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
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/*
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* Dummy source function
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*/
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static int entropy_dummy_source( void *data, unsigned char *output,
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size_t len, size_t *olen )
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{
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((void) data);
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memset( output, 0x2a, len );
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*olen = len;
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return( 0 );
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}
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#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
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#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
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static int mbedtls_entropy_source_self_test_gather( unsigned char *buf, size_t buf_len )
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{
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int ret = 0;
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size_t entropy_len = 0;
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size_t olen = 0;
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size_t attempts = buf_len;
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while( attempts > 0 && entropy_len < buf_len )
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{
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if( ( ret = mbedtls_hardware_poll( NULL, buf + entropy_len,
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buf_len - entropy_len, &olen ) ) != 0 )
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return( ret );
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entropy_len += olen;
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attempts--;
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}
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if( entropy_len < buf_len )
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{
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ret = 1;
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}
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return( ret );
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}
|
|
|
|
|
|
static int mbedtls_entropy_source_self_test_check_bits( const unsigned char *buf,
|
|
size_t buf_len )
|
|
{
|
|
unsigned char set= 0xFF;
|
|
unsigned char unset = 0x00;
|
|
size_t i;
|
|
|
|
for( i = 0; i < buf_len; i++ )
|
|
{
|
|
set &= buf[i];
|
|
unset |= buf[i];
|
|
}
|
|
|
|
return( set == 0xFF || unset == 0x00 );
|
|
}
|
|
|
|
/*
|
|
* A test to ensure hat the entropy sources are functioning correctly
|
|
* and there is no obvious failure. The test performs the following checks:
|
|
* - The entropy source is not providing only 0s (all bits unset) or 1s (all
|
|
* bits set).
|
|
* - The entropy source is not providing values in a pattern. Because the
|
|
* hardware could be providing data in an arbitrary length, this check polls
|
|
* the hardware entropy source twice and compares the result to ensure they
|
|
* are not equal.
|
|
* - The error code returned by the entropy source is not an error.
|
|
*/
|
|
int mbedtls_entropy_source_self_test( int verbose )
|
|
{
|
|
int ret = 0;
|
|
unsigned char buf0[2 * sizeof( unsigned long long int )];
|
|
unsigned char buf1[2 * sizeof( unsigned long long int )];
|
|
|
|
if( verbose != 0 )
|
|
mbedtls_printf( " ENTROPY_BIAS test: " );
|
|
|
|
memset( buf0, 0x00, sizeof( buf0 ) );
|
|
memset( buf1, 0x00, sizeof( buf1 ) );
|
|
|
|
if( ( ret = mbedtls_entropy_source_self_test_gather( buf0, sizeof( buf0 ) ) ) != 0 )
|
|
goto cleanup;
|
|
if( ( ret = mbedtls_entropy_source_self_test_gather( buf1, sizeof( buf1 ) ) ) != 0 )
|
|
goto cleanup;
|
|
|
|
/* Make sure that the returned values are not all 0 or 1 */
|
|
if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf0, sizeof( buf0 ) ) ) != 0 )
|
|
goto cleanup;
|
|
if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf1, sizeof( buf1 ) ) ) != 0 )
|
|
goto cleanup;
|
|
|
|
/* Make sure that the entropy source is not returning values in a
|
|
* pattern */
|
|
ret = memcmp( buf0, buf1, sizeof( buf0 ) ) == 0;
|
|
|
|
cleanup:
|
|
if( verbose != 0 )
|
|
{
|
|
if( ret != 0 )
|
|
mbedtls_printf( "failed\n" );
|
|
else
|
|
mbedtls_printf( "passed\n" );
|
|
|
|
mbedtls_printf( "\n" );
|
|
}
|
|
|
|
return( ret != 0 );
|
|
}
|
|
|
|
#endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */
|
|
|
|
/*
|
|
* The actual entropy quality is hard to test, but we can at least
|
|
* test that the functions don't cause errors and write the correct
|
|
* amount of data to buffers.
|
|
*/
|
|
int mbedtls_entropy_self_test( int verbose )
|
|
{
|
|
int ret = 1;
|
|
#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
|
|
mbedtls_entropy_context ctx;
|
|
unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
|
|
unsigned char acc[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
|
|
size_t i, j;
|
|
#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
|
|
|
|
if( verbose != 0 )
|
|
mbedtls_printf( " ENTROPY test: " );
|
|
|
|
#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
|
|
mbedtls_entropy_init( &ctx );
|
|
|
|
/* First do a gather to make sure we have default sources */
|
|
if( ( ret = mbedtls_entropy_gather( &ctx ) ) != 0 )
|
|
goto cleanup;
|
|
|
|
ret = mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16,
|
|
MBEDTLS_ENTROPY_SOURCE_WEAK );
|
|
if( ret != 0 )
|
|
goto cleanup;
|
|
|
|
if( ( ret = mbedtls_entropy_update_manual( &ctx, buf, sizeof buf ) ) != 0 )
|
|
goto cleanup;
|
|
|
|
/*
|
|
* To test that mbedtls_entropy_func writes correct number of bytes:
|
|
* - use the whole buffer and rely on ASan to detect overruns
|
|
* - collect entropy 8 times and OR the result in an accumulator:
|
|
* any byte should then be 0 with probably 2^(-64), so requiring
|
|
* each of the 32 or 64 bytes to be non-zero has a false failure rate
|
|
* of at most 2^(-58) which is acceptable.
|
|
*/
|
|
for( i = 0; i < 8; i++ )
|
|
{
|
|
if( ( ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) ) ) != 0 )
|
|
goto cleanup;
|
|
|
|
for( j = 0; j < sizeof( buf ); j++ )
|
|
acc[j] |= buf[j];
|
|
}
|
|
|
|
for( j = 0; j < sizeof( buf ); j++ )
|
|
{
|
|
if( acc[j] == 0 )
|
|
{
|
|
ret = 1;
|
|
goto cleanup;
|
|
}
|
|
}
|
|
|
|
#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
|
|
if( ( ret = mbedtls_entropy_source_self_test( 0 ) ) != 0 )
|
|
goto cleanup;
|
|
#endif
|
|
|
|
cleanup:
|
|
mbedtls_entropy_free( &ctx );
|
|
#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
|
|
|
|
if( verbose != 0 )
|
|
{
|
|
if( ret != 0 )
|
|
mbedtls_printf( "failed\n" );
|
|
else
|
|
mbedtls_printf( "passed\n" );
|
|
|
|
mbedtls_printf( "\n" );
|
|
}
|
|
|
|
return( ret != 0 );
|
|
}
|
|
#endif /* MBEDTLS_SELF_TEST */
|
|
|
|
#endif /* MBEDTLS_ENTROPY_C */
|