Commit 15df03c6 authored Jan 21, 2019 by Eli Cooper Committed by Pablo Neira Ayuso Feb 05, 2019

netfilter: ipv6: Don't preserve original oif for loopback address

Commit 508b0904 ("netfilter: ipv6: Preserve link scope traffic
original oif") made ip6_route_me_harder() keep the original oif for
link-local and multicast packets. However, it also affected packets
for the loopback address because it used rt6_need_strict().

REDIRECT rules in the OUTPUT chain rewrite the destination to loopback
address; thus its oif should not be preserved. This commit fixes the bug
that redirected local packets are being dropped. Actually the packet was
not exactly dropped; Instead it was sent out to the original oif rather
than lo. When a packet with daddr ::1 is sent to the router, it is
effectively dropped.

Fixes: 508b0904 ("netfilter: ipv6: Preserve link scope traffic original oif")
Signed-off-by: Eli Cooper <elicooper@gmx.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

parent f6ac8585

net/ipv6/netfilter.c

+3 −1

Original line number	Original line	Diff line number	Diff line
	@@ -23,9 +23,11 @@ int ip6_route_me_harder(struct net net, struct sk_buff skb)
	struct sock *sk = sk_to_full_sk(skb->sk);		struct sock *sk = sk_to_full_sk(skb->sk);
	unsigned int hh_len;		unsigned int hh_len;
	struct dst_entry *dst;		struct dst_entry *dst;
			int strict = (ipv6_addr_type(&iph->daddr) &
			(IPV6_ADDR_MULTICAST \| IPV6_ADDR_LINKLOCAL));
	struct flowi6 fl6 = {		struct flowi6 fl6 = {
	.flowi6_oif = sk && sk->sk_bound_dev_if ? sk->sk_bound_dev_if :		.flowi6_oif = sk && sk->sk_bound_dev_if ? sk->sk_bound_dev_if :
	rt6_need_strict(&iph->daddr) ? skb_dst(skb)->dev->ifindex : 0,		strict ? skb_dst(skb)->dev->ifindex : 0,
	.flowi6_mark = skb->mark,		.flowi6_mark = skb->mark,
	.flowi6_uid = sock_net_uid(net, sk),		.flowi6_uid = sock_net_uid(net, sk),
	.daddr = iph->daddr,		.daddr = iph->daddr,

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