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Add check for changing arguments

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In case of argument change, freeing everything is not the most efficient
(wastes one free()+calloc()) but makes the code simpler, which is probably
more important here
This commit is contained in:
Manuel Pégourié-Gonnard 2017-03-14 11:48:38 +01:00
parent 77af79a324
commit 78d564a841
2 changed files with 28 additions and 3 deletions
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24
library/ecp.c
View file

@ -105,6 +105,8 @@ void mbedtls_ecp_set_max_ops( unsigned max_ops )
*/
struct mbedtls_ecp_restart {
unsigned char fake_it; /* for tests: should we fake early return? */
mbedtls_mpi m; /* saved argument: scalar */
mbedtls_ecp_point P; /* saved argument: point */
};
/*
@ -122,6 +124,9 @@ static void ecp_restart_free( mbedtls_ecp_restart_ctx *ctx )
{
if( ctx == NULL )
return;
mbedtls_mpi_free( &ctx->m );
mbedtls_ecp_point_free( &ctx->P );
}
#endif /* MBEDTLS_ECP_EARLY_RETURN */
@ -1514,22 +1519,35 @@ static int ecp_mul_comb( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
size_t d;
mbedtls_ecp_point *T = NULL;
/* set up restart context if needed */
#if defined(MBEDTLS_ECP_EARLY_RETURN)
/* check for restart with new arguments */
if( grp->rs != NULL &&
( mbedtls_mpi_cmp_mpi( m, &grp->rs->m ) != 0 ||
mbedtls_mpi_cmp_mpi( &P->X, &grp->rs->P.X ) != 0 ||
mbedtls_mpi_cmp_mpi( &P->Y, &grp->rs->P.Y ) != 0 ) )
{
ecp_restart_free( grp->rs );
mbedtls_free( grp->rs );
grp->rs = NULL;
}
/* set up restart context if needed */
if( ecp_max_ops != 0 && grp->rs == NULL )
{
grp->rs = mbedtls_calloc( 1, sizeof( mbedtls_ecp_restart_ctx ) );
if( grp->rs == NULL )
return( MBEDTLS_ERR_ECP_ALLOC_FAILED );
ecp_restart_init( grp->rs );
grp->rs->fake_it = 1;
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &grp->rs->m, m ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_copy( &grp->rs->P, P ) );
}
#endif
/* XXX: temporary */
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( grp->rs && grp->rs->fake_it++ != 0 )
if( grp->rs && ++grp->rs->fake_it != 0 )
return( MBEDTLS_ERR_ECP_IN_PROGRESS );
#endif

7
tests/suites/test_suite_ecp.function
View file

@ -121,6 +121,13 @@ void ecp_test_vect_restart( int id,
}
while( ret != 0 );
/* Ok, now start an operation with some arguments, and drop it.
* We'll see if the result of the next operation, with different args,
* are correct regardless (do we discard old context on new args?).
* This also tests that we don't write to R prematurely */
ret = mbedtls_ecp_mul( &grp, &R, &dA, &grp.G, NULL, NULL );
TEST_ASSERT( ret == 0 || ret == MBEDTLS_ERR_ECP_IN_PROGRESS );
/* Non-base point case */
cnt_restarts = 0;
do {