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Commit d1ee2971 authored by Pavel Emelyanov's avatar Pavel Emelyanov Committed by Linus Torvalds
Browse files

devscgroup: make white list more compact in some cases 



Consider you added a 'c foo:bar r' permission to some cgroup and then (a
bit later) 'c'foo:bar w' for it.  After this you'll see the

c foo:bar r
c foo:bar w

lines in a devices.list file.

Another example - consider you added 10 'c foo:bar r' permissions to some
cgroup (e.g.  by mistake).  After this you'll see 10 c foo:bar r lines in
a list file.

This is weird.  This situation also has one more annoying consequence.
Having many items in a white list makes permissions checking slower, sine
it has to walk a longer list.

The proposal is to merge permissions for items, that correspond to the
same device.

Signed-off-by: default avatarPavel Emelyanov <xemul@openvz.org>
Acked-by: default avatarSerge Hallyn <serue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7db9cfd3

security/device_cgroup.c

+16 −2
Original line number Diff line number Diff line
@@ -106,7 +106,7 @@ static int dev_whitelist_copy(struct list_head *dest, struct list_head *orig) 
static int dev_whitelist_add(struct dev_cgroup *dev_cgroup,

			struct dev_whitelist_item *wh)

{

	struct dev_whitelist_item *whcopy;

	struct dev_whitelist_item *whcopy, *walk;



	whcopy = kmalloc(sizeof(*whcopy), GFP_KERNEL);

	if (!whcopy)
@@ -114,6 +114,20 @@ static int dev_whitelist_add(struct dev_cgroup *dev_cgroup, 


	memcpy(whcopy, wh, sizeof(*whcopy));

	spin_lock(&dev_cgroup->lock);

	list_for_each_entry(walk, &dev_cgroup->whitelist, list) {

		if (walk->type != wh->type)

			continue;

		if (walk->major != wh->major)

			continue;

		if (walk->minor != wh->minor)

			continue;



		walk->access |= wh->access;

		kfree(whcopy);

		whcopy = NULL;

	}



	if (whcopy != NULL)

		list_add_tail(&whcopy->list, &dev_cgroup->whitelist);

	spin_unlock(&dev_cgroup->lock);

	return 0;