Commit 3365afd3 authored by Petr Machata's avatar Petr Machata Committed by Jakub Kicinski
Browse files

net: ipv6: ip6mr: Fix in/out netdev to pass to the FORWARD chain 



The netfilter hook is invoked with skb->dev for input netdevice, and
vif_dev for output netdevice. However at the point of invocation, skb->dev
is already set to vif_dev, and MR-forwarded packets are reported with
in=out:

 # ip6tables -A FORWARD -j LOG --log-prefix '[forw]'
 # cd tools/testing/selftests/net/forwarding
 # ./router_multicast.sh
 # dmesg | fgrep '[forw]'
 [ 1670.248245] [forw]IN=v5 OUT=v5 [...]

For reference, IPv4 MR code shows in and out as appropriate.
Fix by caching skb->dev and using the updated value for output netdev.

Fixes: 7bc570c8 ("[IPV6] MROUTE: Support multicast forwarding.")
Signed-off-by: default avatarPetr Machata <petrm@nvidia.com>
Reviewed-by: default avatarIdo Schimmel <idosch@nvidia.com>
Reviewed-by: default avatarNikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/3141ae8386fbe13fef4b793faa75e6bae58d798a.1750113335.git.petrm@nvidia.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent f78c75d8

net/ipv6/ip6mr.c

+2 −1
Original line number Diff line number Diff line
@@ -2039,6 +2039,7 @@ static int ip6mr_forward2(struct net *net, struct mr_table *mrt, 
			  struct sk_buff *skb, int vifi)

{

	struct vif_device *vif = &mrt->vif_table[vifi];

	struct net_device *indev = skb->dev;

	struct net_device *vif_dev;

	struct ipv6hdr *ipv6h;

	struct dst_entry *dst;
@@ -2101,7 +2102,7 @@ static int ip6mr_forward2(struct net *net, struct mr_table *mrt, 
	IP6CB(skb)->flags |= IP6SKB_FORWARDED;



	return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD,

		       net, NULL, skb, skb->dev, vif_dev,

		       net, NULL, skb, indev, skb->dev,

		       ip6mr_forward2_finish);



out_free: