devices cgroup: allow mkfifo

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@us.ibm.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: James Morris <jmorris@namei.org>
Reported-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 46f23971f7e4208d9487cbb9cf477790a8fb378a..9ef066ded23a4962ee98c4e220de20ef69768cdf 100644 (file)
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -543,6 +543,9 @@ int devcgroup_inode_mknod(int mode, dev_t 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);