Replaced mbedtls_ssl_safer_memcmp with mbedtls_platform_memcmp

Saves some bytes and mbedtls_platform_memcmp is a bit safer for side channel
attacks.
This commit is contained in:
Teppo Järvelin 2019-10-04 07:49:39 +03:00
parent 650343cdcd
commit 707ceb88f0
8 changed files with 11 additions and 32 deletions

View file

@ -2231,7 +2231,7 @@
#define rsa_rsassa_pss_verify_ext mbedtls_rsa_rsassa_pss_verify_ext #define rsa_rsassa_pss_verify_ext mbedtls_rsa_rsassa_pss_verify_ext
#define rsa_self_test mbedtls_rsa_self_test #define rsa_self_test mbedtls_rsa_self_test
#define rsa_set_padding mbedtls_rsa_set_padding #define rsa_set_padding mbedtls_rsa_set_padding
#define safer_memcmp mbedtls_ssl_safer_memcmp #define safer_memcmp mbedtls_platform_memcmp
#define set_alarm mbedtls_set_alarm #define set_alarm mbedtls_set_alarm
#define sha1 mbedtls_sha1 #define sha1 mbedtls_sha1
#define sha1_context mbedtls_sha1_context #define sha1_context mbedtls_sha1_context

View file

@ -1159,26 +1159,6 @@ void mbedtls_ssl_dtls_replay_update( mbedtls_ssl_context *ssl );
int mbedtls_ssl_session_copy( mbedtls_ssl_session *dst, int mbedtls_ssl_session_copy( mbedtls_ssl_session *dst,
const mbedtls_ssl_session *src ); const mbedtls_ssl_session *src );
/* constant-time buffer comparison */
static inline int mbedtls_ssl_safer_memcmp( const void *a, const void *b, size_t n )
{
size_t i;
volatile const unsigned char *A = (volatile const unsigned char *) a;
volatile const unsigned char *B = (volatile const unsigned char *) b;
volatile unsigned char diff = 0;
for( i = 0; i < n; i++ )
{
/* Read volatile data in order before computing diff.
* This avoids IAR compiler warning:
* 'the order of volatile accesses is undefined ..' */
unsigned char x = A[i], y = B[i];
diff |= x ^ y;
}
return( diff );
}
#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \ #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
defined(MBEDTLS_SSL_PROTO_TLS1_1) defined(MBEDTLS_SSL_PROTO_TLS1_1)
int mbedtls_ssl_get_key_exchange_md_ssl_tls( mbedtls_ssl_context *ssl, int mbedtls_ssl_get_key_exchange_md_ssl_tls( mbedtls_ssl_context *ssl,

View file

@ -28,12 +28,12 @@
#if defined(MBEDTLS_ASN1_WRITE_C) #if defined(MBEDTLS_ASN1_WRITE_C)
#include "mbedtls/asn1write.h" #include "mbedtls/asn1write.h"
#include "mbedtls/platform_util.h"
#include <string.h> #include <string.h>
#if defined(MBEDTLS_PLATFORM_C) #if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h" #include "mbedtls/platform.h"
#include "mbedtls/platform_util.h"
#else #else
#include <stdlib.h> #include <stdlib.h>
#define mbedtls_calloc calloc #define mbedtls_calloc calloc

View file

@ -40,7 +40,6 @@
#if defined(MBEDTLS_ECP_C) #if defined(MBEDTLS_ECP_C)
#include "mbedtls/bignum.h" #include "mbedtls/bignum.h"
#include "mbedtls/ecp.h" #include "mbedtls/ecp.h"
#include "mbedtls/platform_util.h"
#endif #endif
#if defined(MBEDTLS_ECDSA_C) #if defined(MBEDTLS_ECDSA_C)
#include "mbedtls/ecdsa.h" #include "mbedtls/ecdsa.h"

View file

@ -1152,9 +1152,9 @@ static int ssl_parse_renegotiation_info( mbedtls_ssl_context *ssl,
/* Check verify-data in constant-time. The length OTOH is no secret */ /* Check verify-data in constant-time. The length OTOH is no secret */
if( len != 1 + ssl->verify_data_len * 2 || if( len != 1 + ssl->verify_data_len * 2 ||
buf[0] != ssl->verify_data_len * 2 || buf[0] != ssl->verify_data_len * 2 ||
mbedtls_ssl_safer_memcmp( buf + 1, mbedtls_platform_memcmp( buf + 1,
ssl->own_verify_data, ssl->verify_data_len ) != 0 || ssl->own_verify_data, ssl->verify_data_len ) != 0 ||
mbedtls_ssl_safer_memcmp( buf + 1 + ssl->verify_data_len, mbedtls_platform_memcmp( buf + 1 + ssl->verify_data_len,
ssl->peer_verify_data, ssl->verify_data_len ) != 0 ) ssl->peer_verify_data, ssl->verify_data_len ) != 0 )
{ {
MBEDTLS_SSL_DEBUG_MSG( 1, ( "non-matching renegotiation info" ) ); MBEDTLS_SSL_DEBUG_MSG( 1, ( "non-matching renegotiation info" ) );

View file

@ -229,7 +229,7 @@ int mbedtls_ssl_cookie_check( void *p_ctx,
if( ret != 0 ) if( ret != 0 )
return( ret ); return( ret );
if( mbedtls_ssl_safer_memcmp( cookie + 4, ref_hmac, sizeof( ref_hmac ) ) != 0 ) if( mbedtls_platform_memcmp( cookie + 4, ref_hmac, sizeof( ref_hmac ) ) != 0 )
return( -1 ); return( -1 );
#if defined(MBEDTLS_HAVE_TIME) #if defined(MBEDTLS_HAVE_TIME)

View file

@ -160,7 +160,7 @@ static int ssl_parse_renegotiation_info( mbedtls_ssl_context *ssl,
/* Check verify-data in constant-time. The length OTOH is no secret */ /* Check verify-data in constant-time. The length OTOH is no secret */
if( len != 1 + ssl->verify_data_len || if( len != 1 + ssl->verify_data_len ||
buf[0] != ssl->verify_data_len || buf[0] != ssl->verify_data_len ||
mbedtls_ssl_safer_memcmp( buf + 1, ssl->peer_verify_data, mbedtls_platform_memcmp( buf + 1, ssl->peer_verify_data,
ssl->verify_data_len ) != 0 ) ssl->verify_data_len ) != 0 )
{ {
MBEDTLS_SSL_DEBUG_MSG( 1, ( "non-matching renegotiation info" ) ); MBEDTLS_SSL_DEBUG_MSG( 1, ( "non-matching renegotiation info" ) );
@ -4089,7 +4089,7 @@ static int ssl_parse_client_psk_identity( mbedtls_ssl_context *ssl, unsigned cha
/* Identity is not a big secret since clients send it in the clear, /* Identity is not a big secret since clients send it in the clear,
* but treat it carefully anyway, just in case */ * but treat it carefully anyway, just in case */
if( n != ssl->conf->psk_identity_len || if( n != ssl->conf->psk_identity_len ||
mbedtls_ssl_safer_memcmp( ssl->conf->psk_identity, *p, n ) != 0 ) mbedtls_platform_memcmp( ssl->conf->psk_identity, *p, n ) != 0 )
{ {
ret = MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY; ret = MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY;
} }

View file

@ -3083,7 +3083,7 @@ int mbedtls_ssl_decrypt_buf( mbedtls_ssl_context const *ssl,
* *
* Afterwards, we know that data + data_len is followed by at * Afterwards, we know that data + data_len is followed by at
* least maclen Bytes, which justifies the call to * least maclen Bytes, which justifies the call to
* mbedtls_ssl_safer_memcmp() below. * mbedtls_platform_memcmp() below.
* *
* Further, we still know that data_len > minlen */ * Further, we still know that data_len > minlen */
rec->data_len -= transform->maclen; rec->data_len -= transform->maclen;
@ -3105,7 +3105,7 @@ int mbedtls_ssl_decrypt_buf( mbedtls_ssl_context const *ssl,
transform->maclen ); transform->maclen );
/* Compare expected MAC with MAC at the end of the record. */ /* Compare expected MAC with MAC at the end of the record. */
if( mbedtls_ssl_safer_memcmp( data + rec->data_len, mac_expect, if( mbedtls_platform_memcmp( data + rec->data_len, mac_expect,
transform->maclen ) != 0 ) transform->maclen ) != 0 )
{ {
MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) ); MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
@ -3444,7 +3444,7 @@ int mbedtls_ssl_decrypt_buf( mbedtls_ssl_context const *ssl,
MBEDTLS_SSL_DEBUG_BUF( 4, "message mac", data + rec->data_len, transform->maclen ); MBEDTLS_SSL_DEBUG_BUF( 4, "message mac", data + rec->data_len, transform->maclen );
#endif #endif
if( mbedtls_ssl_safer_memcmp( data + rec->data_len, mac_expect, if( mbedtls_platform_memcmp( data + rec->data_len, mac_expect,
transform->maclen ) != 0 ) transform->maclen ) != 0 )
{ {
#if defined(MBEDTLS_SSL_DEBUG_ALL) #if defined(MBEDTLS_SSL_DEBUG_ALL)
@ -7913,7 +7913,7 @@ int mbedtls_ssl_parse_finished( mbedtls_ssl_context *ssl )
return( MBEDTLS_ERR_SSL_BAD_HS_FINISHED ); return( MBEDTLS_ERR_SSL_BAD_HS_FINISHED );
} }
if( mbedtls_ssl_safer_memcmp( ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl ), if( mbedtls_platform_memcmp( ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl ),
buf, hash_len ) != 0 ) buf, hash_len ) != 0 )
{ {
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) ); MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );