[patch 25/94] devices cgroup: allow mkfifo

[Greg KH]

2.6.28-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Serge E. Hallyn <serue@xxxxxxxxxx>

commit 0b82ac37b889ec881b645860da3775118effb3ca upstream.

The devcgroup_inode_permission() hook in the devices whitelist cgroup has
always bypassed access checks on fifos.  But the mknod hook did not.  The
devices whitelist is only about block and char devices, and fifos can't
even be added to the whitelist, so fifos can't be created at all except by
tasks which have 'a' in their whitelist (meaning they have access to all
devices).

Fix the behavior by bypassing access checks to mkfifo.

Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Paul Menage <menage@xxxxxxxxxx>
Cc: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Reported-by: Daniel Lezcano <dlezcano@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 security/device_cgroup.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -513,6 +513,9 @@ int devcgroup_inode_mknod(int mode, dev_
 	struct dev_cgroup *dev_cgroup;
 	struct dev_whitelist_item *wh;
 
+	if (!S_ISBLK(mode) && !S_ISCHR(mode))
+		return 0;
+
 	rcu_read_lock();
 
 	dev_cgroup = task_devcgroup(current);

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