Commit eb63ecc1 authored Dec 14, 2016 by David Ahern Committed by David S. Miller Dec 17, 2016

net: vrf: Drop conntrack data after pass through VRF device on Tx



Locally originated traffic in a VRF fails in the presence of a POSTROUTING
rule. For example,

    $ iptables -t nat -A POSTROUTING -s 11.1.1.0/24  -j MASQUERADE
    $ ping -I red -c1 11.1.1.3
    ping: Warning: source address might be selected on device other than red.
    PING 11.1.1.3 (11.1.1.3) from 11.1.1.2 red: 56(84) bytes of data.
    ping: sendmsg: Operation not permitted

Worse, the above causes random corruption resulting in a panic in random
places (I have not seen a consistent backtrace).

Call nf_reset to drop the conntrack info following the pass through the
VRF device.  The nf_reset is needed on Tx but not Rx because of the order
in which NF_HOOK's are hit: on Rx the VRF device is after the real ingress
device and on Tx it is is before the real egress device. Connection
tracking should be tied to the real egress device and not the VRF device.

Fixes: 8f58336d ("net: Add ethernet header for pass through VRF device")
Fixes: 35402e31 ("net: Add IPv6 support to VRF device")
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent a0f37efa

drivers/net/vrf.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -366,6 +366,8 @@ static int vrf_finish_output6(struct net net, struct sock sk,
		struct in6_addr *nexthop;
		int ret;

		nf_reset(skb);

		skb->protocol = htons(ETH_P_IPV6);
		skb->dev = dev;

		@@ -547,6 +549,8 @@ static int vrf_finish_output(struct net net, struct sock sk, struct sk_buff *s
		u32 nexthop;
		int ret = -EINVAL;

		nf_reset(skb);

		/* Be paranoid, rather than too clever. */
		if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
		struct sk_buff *skb2;

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