[PATCH 4.14 53/89] netfilter: ipv6: Preserve link scope traffic original oif

Greg Kroah-Hartman
2018-12-14T12:32:00Z

[ Upstream commit 508b09046c0f21678652fb66fd1e9959d55591d2 ]

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@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.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 9bf260459f83..1f8b1a433b5d 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -25,7 +25,8 @@ 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,
--
2.19.1