[3.16.y-ckt stable] Patch "ip_forward: Drop frames with attached skb->sk" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ip_forward: Drop frames with attached skb->sk

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt11.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From ee446a4d19dd24463ea5f830ae9a26238923f6df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20P=C3=B6hn?= <sebastian.poehn at gmail.com>
Date: Mon, 20 Apr 2015 09:19:20 +0200
Subject: ip_forward: Drop frames with attached skb->sk

commit 2ab957492d13bb819400ac29ae55911d50a82a13 upstream.

Initial discussion was:
[FYI] xfrm: Don't lookup sk_policy for timewait sockets

Forwarded frames should not have a socket attached. Especially
tw sockets will lead to panics later-on in the stack.

This was observed with TPROXY assigning a tw socket and broken
policy routing (misconfigured). As a result frame enters
forwarding path instead of input. We cannot solve this in
TPROXY as it cannot know that policy routing is broken.

v2:
Remove useless comment

Signed-off-by: Sebastian Poehn <sebastian.poehn at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/ipv4/ip_forward.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index 787b3c294ce6..d5410b57da19 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -81,6 +81,9 @@ int ip_forward(struct sk_buff *skb)
 	if (skb->pkt_type != PACKET_HOST)
 		goto drop;

+	if (unlikely(skb->sk))
+		goto drop;
+
 	if (skb_warn_if_lro(skb))
 		goto drop;