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

Commit 508b090 ("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: 508b090 ("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>
torvalds · Feb 5, 2019 · 15df03c · 15df03c
1 parent f6ac858
commit 15df03c
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
@@ -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);
 	unsigned int hh_len;
 	struct dst_entry *dst;
+	int strict = (ipv6_addr_type(&iph->daddr) &
+		      (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL));
 	struct flowi6 fl6 = {
 		.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_uid = sock_net_uid(net, sk),
 		.daddr = iph->daddr,