Commit d1ee2971 authored Jun 05, 2008 by Pavel Emelyanov Committed by Linus Torvalds Jun 06, 2008

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: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus 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 @@ free_and_exit:
		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;

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