devcgroup: fix permission check when adding entry to child cgroup
# cat devices.list
c 1:3 r
# echo 'c 1:3 w' > sub/devices.allow
# cat sub/devices.list
c 1:3 w
As illustrated, the parent group has no write permission to /dev/null, so
it's child should not be allowed to add this write permission.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 1e2e28a..ddd92ce 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -300,7 +300,7 @@
continue;
if (whitem->minor != ~0 && whitem->minor != refwh->minor)
continue;
- if (refwh->access & (~(whitem->access | ACC_MASK)))
+ if (refwh->access & (~whitem->access))
continue;
return 1;
}
