Add flow monitor for mbedtls_platform_memcpy() and mbedtls_platform_memmove()
Signed-off-by: Piotr Nowicki <piotr.nowicki@arm.com>
diff --git a/library/platform_util.c b/library/platform_util.c
index 28790a4..3b098d2 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -127,20 +127,29 @@
start_offset = (size_t) mbedtls_platform_random_in_range( (uint32_t) num );
rnd_data = (char) mbedtls_platform_random_in_range( 256 );
- /* Start from a random location */
+ /* Perform a memset operations with random data and start from a random
+ * location */
+ for( i = start_offset; i < num; ++i )
+ {
+ b[i] = rnd_data;
+ flow_counter++;
+ }
+
+ /* Start from a random location with target data */
for( i = start_offset; i < num; ++i )
{
b[i] = value;
flow_counter++;
}
- /* Perform a memset operations with random data */
+ /* Second memset operation with random data */
for( i = 0; i < start_offset; ++i )
{
b[i] = rnd_data;
+ flow_counter++;
}
- /* Finish a memset operations with correct data */
+ /* Finish memset operation with correct data */
for( i = 0; i < start_offset; ++i )
{
b[i] = value;
@@ -148,10 +157,10 @@
}
/* check the correct number of iterations */
- if( flow_counter == num )
+ if( flow_counter == 2 * num )
{
mbedtls_platform_random_delay();
- if( flow_counter == num )
+ if( flow_counter == 2 * num )
{
return ptr;
}
@@ -161,33 +170,61 @@
void *mbedtls_platform_memcpy( void *dst, const void *src, size_t num )
{
- /* Randomize start offset. */
- size_t start_offset = (size_t) mbedtls_platform_random_in_range( (uint32_t) num );
- /* Randomize initial data to prevent leakage while copying */
- uint32_t data = mbedtls_platform_random_in_range( 256 );
+ size_t i;
+ volatile size_t flow_counter = 0;
- /* Use memset with random value at first to increase security - memset is
- not normally part of the memcpy function and here can be useed
- with regular, unsecured implementation */
- memset( (void *) dst, data, num );
- memcpy( (void *) ( (unsigned char *) dst + start_offset ),
- (void *) ( (unsigned char *) src + start_offset ),
- ( num - start_offset ) );
- return( memcpy( (void *) dst, (void *) src, start_offset ) );
+ if( num > 0 )
+ {
+ /* Randomize start offset. */
+ size_t start_offset = (size_t) mbedtls_platform_random_in_range( (uint32_t) num );
+ /* Randomize initial data to prevent leakage while copying */
+ uint32_t data = mbedtls_platform_random_in_range( 256 );
+
+ /* Use memset with random value at first to increase security - memset is
+ not normally part of the memcpy function and here can be useed
+ with regular, unsecured implementation */
+ memset( (void *) dst, data, num );
+
+ /* Make a copy starting from a random location. */
+ i = start_offset;
+ do
+ {
+ ( (char*) dst )[i] = ( (char*) src )[i];
+ flow_counter++;
+ }
+ while( ( i = ( i + 1 ) % num ) != start_offset );
+ }
+
+ /* check the correct number of iterations */
+ if( flow_counter == num )
+ {
+ mbedtls_platform_random_delay();
+ if( flow_counter == num )
+ {
+ return dst;
+ }
+ }
+ return NULL;
}
int mbedtls_platform_memmove( void *dst, const void *src, size_t num )
{
+ void *ret1 = NULL;
+ void *ret2 = NULL;
/* The buffers can have a common part, so we cannot do a copy from a random
* location. By using a temporary buffer we can do so, but the cost of it
* is using more memory and longer transfer time. */
void *tmp = mbedtls_calloc( 1, num );
if( tmp != NULL )
{
- mbedtls_platform_memcpy( tmp, src, num );
- mbedtls_platform_memcpy( dst, tmp, num );
+ ret1 = mbedtls_platform_memcpy( tmp, src, num );
+ ret2 = mbedtls_platform_memcpy( dst, tmp, num );
mbedtls_free( tmp );
- return 0;
+ if( ret1 == tmp && ret2 == dst )
+ {
+ return 0;
+ }
+ return MBEDTLS_ERR_PLATFORM_FAULT_DETECTED;
}
return MBEDTLS_ERR_PLATFORM_ALLOC_FAILED;