Merge branch 'vrf-looping'

David Ahern says:

====================
net: Fix looping with vrf, xfrms and qdisc on VRF

Trev reported that use of VRFs with xfrms is looping when a qdisc
is added to the VRF device. The combination of xfrm + qdisc is not
handled by the VRF driver which lost track that it has already
seen the packet.

The XFRM_TRANSFORMED flag is used by the netfilter code for a similar
purpose, so re-use for VRF. Patch 1 drops the #ifdef around setting
the flag in the xfrm output functions. Patch 2 adds a check to
the VRF driver for flag; if set the packet has already passed through
the VRF driver once and does not need to recirculated a second time.

This is a day 1 bug with VRFs; stable wise, I would only take this
back to 4.14. I have a set of test cases which I will submit to
net-next.
====================

Signed-off-by: David S. Miller <[e-mail]>

drivers/net/vrf.c

···
 	if (rt6_need_strict(&ipv6_hdr(skb)->daddr))
 		return skb;
 
-	if (qdisc_tx_is_default(vrf_dev))
+	if (qdisc_tx_is_default(vrf_dev) ||
+	    IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED)
 		return vrf_ip6_out_direct(vrf_dev, sk, skb);
 
 	return vrf_ip6_out_redirect(vrf_dev, skb);
···
 	    ipv4_is_lbcast(ip_hdr(skb)->daddr))
 		return skb;
 
-	if (qdisc_tx_is_default(vrf_dev))
+	if (qdisc_tx_is_default(vrf_dev) ||
+	    IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
 		return vrf_ip_out_direct(vrf_dev, sk, skb);
 
 	return vrf_ip_out_redirect(vrf_dev, skb);

net/ipv4/xfrm4_output.c

···
 {
 	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
 
-#ifdef CONFIG_NETFILTER
 	IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
-#endif
 
 	return xfrm_output(sk, skb);
 }

net/ipv6/xfrm6_output.c

···
 {
 	memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 
-#ifdef CONFIG_NETFILTER
 	IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
-#endif
 
 	return xfrm_output(sk, skb);
 }