From d1ee2971f5bd8a16bc5ecfe1b00e14b4fe407c4f Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Thu, 5 Jun 2008 22:46:28 -0700 Subject: [PATCH] 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 Acked-by: Serge Hallyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- security/device_cgroup.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/security/device_cgroup.c b/security/device_cgroup.c index f9941a769738..baf348834b66 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -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) @@ -114,7 +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; }