devscgroup: make white list more compact in some cases

d1ee2971 · Pavel Emelyanov <[email protected]> · 2008-06-05 22:46:28 -07:00

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 <[email protected]>
Acked-by: Serge Hallyn <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: d1ee2971f5bd8a16bc5ecfe1b00e14b4fe407c4f
Parents: 7db9cfd3

Changes

1 files changed · +16 −2

File	Status	Add	Del	Content
security/device_cgroup.c	modified	+16	−2	View file

security/device_cgroup.c

View file

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index f9941a7..baf3488 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -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)
@@ -114,7 +114,21 @@ static int dev_whitelist_add(struct dev_cgroup *dev_cgroup,
 
 	memcpy(whcopy, wh, sizeof(*whcopy));
 	spin_lock(&dev_cgroup->lock);
-	list_add_tail(&whcopy->list, &dev_cgroup->whitelist);
+	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;
 }