netdev - [PATCH 12/16] netfilter: ipv6: Preserve link scope traffic original oif

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Message-Id: <20181128101741.20924-13-pablo@netfilter.org>
Date:   Wed, 28 Nov 2018 11:17:37 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 12/16] netfilter: ipv6: Preserve link scope traffic original oif

From: Alin Nastac <alin.nastac@...il.com>

When ip6_route_me_harder is invoked, it resets outgoing interface of:
  - link-local scoped packets sent by neighbor discovery
  - multicast packets sent by MLD host
  - multicast packets send by MLD proxy daemon that sets outgoing
    interface through IPV6_PKTINFO ipi6_ifindex

Link-local and multicast packets must keep their original oif after
ip6_route_me_harder is called.

Signed-off-by: Alin Nastac <alin.nastac@...il.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/ipv6/netfilter.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 5ae8e1c51079..8b075f0bc351 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -24,7 +24,8 @@ int ip6_route_me_harder(struct net *net, struct sk_buff *skb)
 	unsigned int hh_len;
 	struct dst_entry *dst;
 	struct flowi6 fl6 = {
-		.flowi6_oif = sk ? sk->sk_bound_dev_if : 0,
+		.flowi6_oif = sk && sk->sk_bound_dev_if ? sk->sk_bound_dev_if :
+			rt6_need_strict(&iph->daddr) ? skb_dst(skb)->dev->ifindex : 0,
 		.flowi6_mark = skb->mark,
 		.flowi6_uid = sock_net_uid(net, sk),
 		.daddr = iph->daddr,
-- 
2.11.0