Move ops count to top-level context
When a restartable function calls another restartable function, the current
ops_count needs to be shared to avoid either doing too many operations or
returning IN_PROGRESS uselessly. So it needs to be in the top-level context
rather than a specific sub-context.
diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index d9e62f0..9193b77 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -184,7 +184,8 @@
*/
typedef struct
{
- mbedtls_ecp_restart_mul_ctx *rsm; /*!< restart context for ecp_mul() */
+ unsigned ops_done; /*!< current ops count */
+ mbedtls_ecp_restart_mul_ctx *rsm; /*!< ecp_mul_comb() sub-context */
} mbedtls_ecp_restart_ctx;
#endif /* MBEDTLS_ECP_EARLY_RETURN */
diff --git a/library/ecp.c b/library/ecp.c
index fcc3ae0..ecc1815 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -104,7 +104,6 @@
* Restart context type for interrupted operations
*/
struct mbedtls_ecp_restart_mul {
- unsigned ops_done; /* number of operations done this time */
mbedtls_ecp_point R; /* current intermediate result */
size_t i; /* current index in various loops, 0 outside */
mbedtls_ecp_point *T; /* table for precomputed points */
@@ -164,6 +163,8 @@
if( ctx == NULL )
return;
+ ctx->ops_done = 0;
+
ecp_restart_mul_free( ctx->rsm );
mbedtls_free( ctx->rsm );
ctx->rsm = NULL;
@@ -183,7 +184,7 @@
mbedtls_ecp_restart_ctx *rs_ctx,
unsigned ops )
{
- if( rs_ctx != NULL && rs_ctx->rsm != NULL )
+ if( rs_ctx != NULL && ecp_max_ops != 0 )
{
/* scale depending on curve size: the chosen reference is 256-bit,
* and multiplication is quadratic. Round to the closest integer. */
@@ -193,11 +194,11 @@
ops *= 2;
/* avoid infinite loops: always allow first step */
- if( rs_ctx->rsm->ops_done != 0 && rs_ctx->rsm->ops_done + ops > ecp_max_ops )
+ if( rs_ctx->ops_done != 0 && rs_ctx->ops_done + ops > ecp_max_ops )
return( MBEDTLS_ERR_ECP_IN_PROGRESS );
/* update running count */
- rs_ctx->rsm->ops_done += ops;
+ rs_ctx->ops_done += ops;
}
return( 0 );
@@ -1759,7 +1760,7 @@
#endif
#if defined(MBEDTLS_ECP_EARLY_RETURN)
- /* set up restart context if needed */
+ /* set up our own sub-context if needed */
if( ecp_max_ops != 0 && rs_ctx != NULL && rs_ctx->rsm == NULL )
{
rs_ctx->rsm = mbedtls_calloc( 1, sizeof( mbedtls_ecp_restart_mul_ctx ) );
@@ -1770,8 +1771,8 @@
}
/* reset ops count for this call */
- if( rs_ctx != NULL && rs_ctx->rsm != NULL )
- rs_ctx->rsm->ops_done = 0;
+ if( rs_ctx != NULL )
+ rs_ctx->ops_done = 0;
#endif
/* Is P the base point ? */