Patch "netfilter: xt_osf: Add missing permission checks" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

netfilter: xt_osf: Add missing permission checks

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
netfilter-xt_osf-add-missing-permission-checks.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Kevin Cernekee <[email protected]>
Date: Tue, 5 Dec 2017 15:42:41 -0800
Subject: netfilter: xt_osf: Add missing permission checks

From: Kevin Cernekee <[email protected]>

commit 916a27901de01446bcf57ecca4783f6cff493309 upstream.

The capability check in nfnetlink_rcv() verifies that the caller has CAP_NET_ADMIN in the namespace that "owns" the netlink socket. However, xt_osf_fingers is shared by all net namespaces on the system. An unprivileged user can create user and net namespaces in which he holds CAP_NET_ADMIN to bypass the netlink_net_capable() check:

vpnns -- nfnl_osf -f /tmp/pf.os

vpnns -- nfnl_osf -f /tmp/pf.os -d

These non-root operations successfully modify the systemwide OS fingerprint list. Add new capable() checks so that they can't.

---
 net/netfilter/xt_osf.c |    7 +++++++
 1 file changed, 7 insertions(+)

@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 
+#include <linux/capability.h>
 #include <linux/if.h>
 #include <linux/inetdevice.h>
 #include <linux/ip.h>

@@ -70,6 +71,9 @@ static int xt_osf_add_callback(struct ne
 	struct xt_osf_finger *kf = NULL, *sf;
 	int err = 0;
 
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	if (!osf_attrs[OSF_ATTR_FINGER])
 		return -EINVAL;
 

@@ -115,6 +119,9 @@ static int xt_osf_remove_callback(struct
 	struct xt_osf_finger *sf;
 	int err = -ENOENT;
 
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	if (!osf_attrs[OSF_ATTR_FINGER])
 		return -EINVAL;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/netfilter-xt_osf-add-missing-permission-checks.patch queue-4.14/netfilter-nfnetlink_cthelper-add-missing-permission-checks.patch