mbedtls/library/sha256.c
Manuel Pégourié-Gonnard 69675d056a Fix Lucky 13 cache attack on MD/SHA padding
The basis for the Lucky 13 family of attacks is for an attacker to be able to
distinguish between (long) valid TLS-CBC padding and invalid TLS-CBC padding.
Since our code sets padlen = 0 for invalid padding, the length of the input to
the HMAC function gives information about that.

Information about this length (modulo the MD/SHA block size) can be deduced
from how much MD/SHA padding (this is distinct from TLS-CBC padding) is used.
If MD/SHA padding is read from a (static) buffer, a local attacker could get
information about how much is used via a cache attack targeting that buffer.

Let's get rid of this buffer. Now the only buffer used is the internal MD/SHA
one, which is always read fully by the process() function.
2018-07-12 10:20:33 +02:00

461 lines
13 KiB
C

/*
* FIPS-180-2 compliant SHA-256 implementation
*
* Copyright (C) 2006-2015, 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)
*/
/*
* The SHA-256 Secure Hash Standard was published by NIST in 2002.
*
* http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_SHA256_C)
#include "mbedtls/sha256.h"
#include <string.h>
#if defined(MBEDTLS_SELF_TEST)
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#endif /* MBEDTLS_PLATFORM_C */
#endif /* MBEDTLS_SELF_TEST */
#if !defined(MBEDTLS_SHA256_ALT)
/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n ) {
volatile unsigned char *p = v; while( n-- ) *p++ = 0;
}
/*
* 32-bit integer manipulation macros (big endian)
*/
#ifndef GET_UINT32_BE
#define GET_UINT32_BE(n,b,i) \
do { \
(n) = ( (uint32_t) (b)[(i) ] << 24 ) \
| ( (uint32_t) (b)[(i) + 1] << 16 ) \
| ( (uint32_t) (b)[(i) + 2] << 8 ) \
| ( (uint32_t) (b)[(i) + 3] ); \
} while( 0 )
#endif
#ifndef PUT_UINT32_BE
#define PUT_UINT32_BE(n,b,i) \
do { \
(b)[(i) ] = (unsigned char) ( (n) >> 24 ); \
(b)[(i) + 1] = (unsigned char) ( (n) >> 16 ); \
(b)[(i) + 2] = (unsigned char) ( (n) >> 8 ); \
(b)[(i) + 3] = (unsigned char) ( (n) ); \
} while( 0 )
#endif
void mbedtls_sha256_init( mbedtls_sha256_context *ctx )
{
memset( ctx, 0, sizeof( mbedtls_sha256_context ) );
}
void mbedtls_sha256_free( mbedtls_sha256_context *ctx )
{
if( ctx == NULL )
return;
mbedtls_zeroize( ctx, sizeof( mbedtls_sha256_context ) );
}
void mbedtls_sha256_clone( mbedtls_sha256_context *dst,
const mbedtls_sha256_context *src )
{
*dst = *src;
}
/*
* SHA-256 context setup
*/
void mbedtls_sha256_starts( mbedtls_sha256_context *ctx, int is224 )
{
ctx->total[0] = 0;
ctx->total[1] = 0;
if( is224 == 0 )
{
/* SHA-256 */
ctx->state[0] = 0x6A09E667;
ctx->state[1] = 0xBB67AE85;
ctx->state[2] = 0x3C6EF372;
ctx->state[3] = 0xA54FF53A;
ctx->state[4] = 0x510E527F;
ctx->state[5] = 0x9B05688C;
ctx->state[6] = 0x1F83D9AB;
ctx->state[7] = 0x5BE0CD19;
}
else
{
/* SHA-224 */
ctx->state[0] = 0xC1059ED8;
ctx->state[1] = 0x367CD507;
ctx->state[2] = 0x3070DD17;
ctx->state[3] = 0xF70E5939;
ctx->state[4] = 0xFFC00B31;
ctx->state[5] = 0x68581511;
ctx->state[6] = 0x64F98FA7;
ctx->state[7] = 0xBEFA4FA4;
}
ctx->is224 = is224;
}
#if !defined(MBEDTLS_SHA256_PROCESS_ALT)
static const uint32_t K[] =
{
0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5,
0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5,
0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3,
0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174,
0xE49B69C1, 0xEFBE4786, 0x0FC19DC6, 0x240CA1CC,
0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA,
0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7,
0xC6E00BF3, 0xD5A79147, 0x06CA6351, 0x14292967,
0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13,
0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85,
0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3,
0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070,
0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5,
0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3,
0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208,
0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2,
};
#define SHR(x,n) ((x & 0xFFFFFFFF) >> n)
#define ROTR(x,n) (SHR(x,n) | (x << (32 - n)))
#define S0(x) (ROTR(x, 7) ^ ROTR(x,18) ^ SHR(x, 3))
#define S1(x) (ROTR(x,17) ^ ROTR(x,19) ^ SHR(x,10))
#define S2(x) (ROTR(x, 2) ^ ROTR(x,13) ^ ROTR(x,22))
#define S3(x) (ROTR(x, 6) ^ ROTR(x,11) ^ ROTR(x,25))
#define F0(x,y,z) ((x & y) | (z & (x | y)))
#define F1(x,y,z) (z ^ (x & (y ^ z)))
#define R(t) \
( \
W[t] = S1(W[t - 2]) + W[t - 7] + \
S0(W[t - 15]) + W[t - 16] \
)
#define P(a,b,c,d,e,f,g,h,x,K) \
{ \
temp1 = h + S3(e) + F1(e,f,g) + K + x; \
temp2 = S2(a) + F0(a,b,c); \
d += temp1; h = temp1 + temp2; \
}
void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[64] )
{
uint32_t temp1, temp2, W[64];
uint32_t A[8];
unsigned int i;
for( i = 0; i < 8; i++ )
A[i] = ctx->state[i];
#if defined(MBEDTLS_SHA256_SMALLER)
for( i = 0; i < 64; i++ )
{
if( i < 16 )
GET_UINT32_BE( W[i], data, 4 * i );
else
R( i );
P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i], K[i] );
temp1 = A[7]; A[7] = A[6]; A[6] = A[5]; A[5] = A[4]; A[4] = A[3];
A[3] = A[2]; A[2] = A[1]; A[1] = A[0]; A[0] = temp1;
}
#else /* MBEDTLS_SHA256_SMALLER */
for( i = 0; i < 16; i++ )
GET_UINT32_BE( W[i], data, 4 * i );
for( i = 0; i < 16; i += 8 )
{
P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i+0], K[i+0] );
P( A[7], A[0], A[1], A[2], A[3], A[4], A[5], A[6], W[i+1], K[i+1] );
P( A[6], A[7], A[0], A[1], A[2], A[3], A[4], A[5], W[i+2], K[i+2] );
P( A[5], A[6], A[7], A[0], A[1], A[2], A[3], A[4], W[i+3], K[i+3] );
P( A[4], A[5], A[6], A[7], A[0], A[1], A[2], A[3], W[i+4], K[i+4] );
P( A[3], A[4], A[5], A[6], A[7], A[0], A[1], A[2], W[i+5], K[i+5] );
P( A[2], A[3], A[4], A[5], A[6], A[7], A[0], A[1], W[i+6], K[i+6] );
P( A[1], A[2], A[3], A[4], A[5], A[6], A[7], A[0], W[i+7], K[i+7] );
}
for( i = 16; i < 64; i += 8 )
{
P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], R(i+0), K[i+0] );
P( A[7], A[0], A[1], A[2], A[3], A[4], A[5], A[6], R(i+1), K[i+1] );
P( A[6], A[7], A[0], A[1], A[2], A[3], A[4], A[5], R(i+2), K[i+2] );
P( A[5], A[6], A[7], A[0], A[1], A[2], A[3], A[4], R(i+3), K[i+3] );
P( A[4], A[5], A[6], A[7], A[0], A[1], A[2], A[3], R(i+4), K[i+4] );
P( A[3], A[4], A[5], A[6], A[7], A[0], A[1], A[2], R(i+5), K[i+5] );
P( A[2], A[3], A[4], A[5], A[6], A[7], A[0], A[1], R(i+6), K[i+6] );
P( A[1], A[2], A[3], A[4], A[5], A[6], A[7], A[0], R(i+7), K[i+7] );
}
#endif /* MBEDTLS_SHA256_SMALLER */
for( i = 0; i < 8; i++ )
ctx->state[i] += A[i];
}
#endif /* !MBEDTLS_SHA256_PROCESS_ALT */
/*
* SHA-256 process buffer
*/
void mbedtls_sha256_update( mbedtls_sha256_context *ctx, const unsigned char *input,
size_t ilen )
{
size_t fill;
uint32_t left;
if( ilen == 0 )
return;
left = ctx->total[0] & 0x3F;
fill = 64 - left;
ctx->total[0] += (uint32_t) ilen;
ctx->total[0] &= 0xFFFFFFFF;
if( ctx->total[0] < (uint32_t) ilen )
ctx->total[1]++;
if( left && ilen >= fill )
{
memcpy( (void *) (ctx->buffer + left), input, fill );
mbedtls_sha256_process( ctx, ctx->buffer );
input += fill;
ilen -= fill;
left = 0;
}
while( ilen >= 64 )
{
mbedtls_sha256_process( ctx, input );
input += 64;
ilen -= 64;
}
if( ilen > 0 )
memcpy( (void *) (ctx->buffer + left), input, ilen );
}
/*
* SHA-256 final digest
*/
void mbedtls_sha256_finish( mbedtls_sha256_context *ctx, unsigned char output[32] )
{
uint32_t used;
uint32_t high, low;
/*
* Add padding: 0x80 then 0x00 until 8 bytes remain for the length
*/
used = ctx->total[0] & 0x3F;
ctx->buffer[used++] = 0x80;
if( used <= 56 )
{
/* Enough room for padding + length in current block */
memset( ctx->buffer + used, 0, 56 - used );
}
else
{
/* We'll need an extra block */
memset( ctx->buffer + used, 0, 64 - used );
mbedtls_sha256_process( ctx, ctx->buffer );
memset( ctx->buffer, 0, 56 );
}
/*
* Add message length
*/
high = ( ctx->total[0] >> 29 )
| ( ctx->total[1] << 3 );
low = ( ctx->total[0] << 3 );
PUT_UINT32_BE( high, ctx->buffer, 56 );
PUT_UINT32_BE( low, ctx->buffer, 60 );
mbedtls_sha256_process( ctx, ctx->buffer );
/*
* Output final state
*/
PUT_UINT32_BE( ctx->state[0], output, 0 );
PUT_UINT32_BE( ctx->state[1], output, 4 );
PUT_UINT32_BE( ctx->state[2], output, 8 );
PUT_UINT32_BE( ctx->state[3], output, 12 );
PUT_UINT32_BE( ctx->state[4], output, 16 );
PUT_UINT32_BE( ctx->state[5], output, 20 );
PUT_UINT32_BE( ctx->state[6], output, 24 );
if( ctx->is224 == 0 )
PUT_UINT32_BE( ctx->state[7], output, 28 );
}
#endif /* !MBEDTLS_SHA256_ALT */
/*
* output = SHA-256( input buffer )
*/
void mbedtls_sha256( const unsigned char *input, size_t ilen,
unsigned char output[32], int is224 )
{
mbedtls_sha256_context ctx;
mbedtls_sha256_init( &ctx );
mbedtls_sha256_starts( &ctx, is224 );
mbedtls_sha256_update( &ctx, input, ilen );
mbedtls_sha256_finish( &ctx, output );
mbedtls_sha256_free( &ctx );
}
#if defined(MBEDTLS_SELF_TEST)
/*
* FIPS-180-2 test vectors
*/
static const unsigned char sha256_test_buf[3][57] =
{
{ "abc" },
{ "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq" },
{ "" }
};
static const int sha256_test_buflen[3] =
{
3, 56, 1000
};
static const unsigned char sha256_test_sum[6][32] =
{
/*
* SHA-224 test vectors
*/
{ 0x23, 0x09, 0x7D, 0x22, 0x34, 0x05, 0xD8, 0x22,
0x86, 0x42, 0xA4, 0x77, 0xBD, 0xA2, 0x55, 0xB3,
0x2A, 0xAD, 0xBC, 0xE4, 0xBD, 0xA0, 0xB3, 0xF7,
0xE3, 0x6C, 0x9D, 0xA7 },
{ 0x75, 0x38, 0x8B, 0x16, 0x51, 0x27, 0x76, 0xCC,
0x5D, 0xBA, 0x5D, 0xA1, 0xFD, 0x89, 0x01, 0x50,
0xB0, 0xC6, 0x45, 0x5C, 0xB4, 0xF5, 0x8B, 0x19,
0x52, 0x52, 0x25, 0x25 },
{ 0x20, 0x79, 0x46, 0x55, 0x98, 0x0C, 0x91, 0xD8,
0xBB, 0xB4, 0xC1, 0xEA, 0x97, 0x61, 0x8A, 0x4B,
0xF0, 0x3F, 0x42, 0x58, 0x19, 0x48, 0xB2, 0xEE,
0x4E, 0xE7, 0xAD, 0x67 },
/*
* SHA-256 test vectors
*/
{ 0xBA, 0x78, 0x16, 0xBF, 0x8F, 0x01, 0xCF, 0xEA,
0x41, 0x41, 0x40, 0xDE, 0x5D, 0xAE, 0x22, 0x23,
0xB0, 0x03, 0x61, 0xA3, 0x96, 0x17, 0x7A, 0x9C,
0xB4, 0x10, 0xFF, 0x61, 0xF2, 0x00, 0x15, 0xAD },
{ 0x24, 0x8D, 0x6A, 0x61, 0xD2, 0x06, 0x38, 0xB8,
0xE5, 0xC0, 0x26, 0x93, 0x0C, 0x3E, 0x60, 0x39,
0xA3, 0x3C, 0xE4, 0x59, 0x64, 0xFF, 0x21, 0x67,
0xF6, 0xEC, 0xED, 0xD4, 0x19, 0xDB, 0x06, 0xC1 },
{ 0xCD, 0xC7, 0x6E, 0x5C, 0x99, 0x14, 0xFB, 0x92,
0x81, 0xA1, 0xC7, 0xE2, 0x84, 0xD7, 0x3E, 0x67,
0xF1, 0x80, 0x9A, 0x48, 0xA4, 0x97, 0x20, 0x0E,
0x04, 0x6D, 0x39, 0xCC, 0xC7, 0x11, 0x2C, 0xD0 }
};
/*
* Checkup routine
*/
int mbedtls_sha256_self_test( int verbose )
{
int i, j, k, buflen, ret = 0;
unsigned char buf[1024];
unsigned char sha256sum[32];
mbedtls_sha256_context ctx;
mbedtls_sha256_init( &ctx );
for( i = 0; i < 6; i++ )
{
j = i % 3;
k = i < 3;
if( verbose != 0 )
mbedtls_printf( " SHA-%d test #%d: ", 256 - k * 32, j + 1 );
mbedtls_sha256_starts( &ctx, k );
if( j == 2 )
{
memset( buf, 'a', buflen = 1000 );
for( j = 0; j < 1000; j++ )
mbedtls_sha256_update( &ctx, buf, buflen );
}
else
mbedtls_sha256_update( &ctx, sha256_test_buf[j],
sha256_test_buflen[j] );
mbedtls_sha256_finish( &ctx, sha256sum );
if( memcmp( sha256sum, sha256_test_sum[i], 32 - k * 4 ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
ret = 1;
goto exit;
}
if( verbose != 0 )
mbedtls_printf( "passed\n" );
}
if( verbose != 0 )
mbedtls_printf( "\n" );
exit:
mbedtls_sha256_free( &ctx );
return( ret );
}
#endif /* MBEDTLS_SELF_TEST */
#endif /* MBEDTLS_SHA256_C */