[PATCH 3/9] xen/gnttab: limit cache flush operation to guests allowed cache control

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Whether a domain is allowed to issue cache-control operations is reported
by the cache_flush_permitted() check.  Introduce such check to limit the
availability of GNTTABOP_cache_flush to only guests that are granted cache
control.

Fixes: 18e8d22fe750 ("introduce GNTTABOP_cache_flush")
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/common/grant_table.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index e75ff98aff1c..d874ac5f1241 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -3780,6 +3780,11 @@ long do_grant_table_op(
 
         if ( unlikely(!guest_handle_okay(cflush, count)) )
             goto out;
+
+        rc = -EPERM;
+        if ( !cache_flush_permitted(current->domain) )
+            goto out;
+
         rc = gnttab_cache_flush(cflush, &opaque_in, count);
         if ( rc >= 0 )
         {
-- 
2.48.1