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devices cgroup: allow mkfifo

PATCH In review Serge E. Hallyn 2 participants 2 messages Dec 9, 2008 – Dec 10, 2008 1 message not in the archive Security (LSM)

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Serge E. Hallyn

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PATCH 1/1 devices cgroup: allow mkfifo

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-r/[email protected]>
---
 security/device_cgroup.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
security/device_cgroup.c +3 -0
index 5ba7870..df9d491 100644
@@ -513,6 +513,9 @@ 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);
Signature · 1 line
1.5.4.3

A message that is not in the archive (sent off-list or not yet received): 20081209210802.GA24549-r/[email protected]

#2 lore raw
Quoted 19 lines · Serge E. Hallyn

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-r/[email protected]>
---
 security/device_cgroup.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
security/device_cgroup.c +0 -0
index 5ba7870..df9d491 100644

security/device_cgroup.c int devcgroup_inode_mknod(int mode, dev_t dev) · line 521

Quoted 9 lines
security/device_cgroup.c +3 -0
@@ -513,6 +513,9 @@ 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);

Cool thanks. I am able to create the initctl fifo now.

-- Daniel