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

Commit 508b09046c0f ("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: 508b09046c0f ("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>

diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 8b075f0bc35169b4098bda738950d631b62ec415..6d0b1f3e927bd75f07cc36fe7b087723e05b85b2 100644 (file)
--- 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,