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

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Commit 508b09046c ("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: 508b09046c ("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>
This commit is contained in:
Eli Cooper 2019-01-21 18:45:27 +08:00 committed by Pablo Neira Ayuso
parent f6ac858589
commit 15df03c661
1 changed files with 3 additions and 1 deletions
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4
net/ipv6/netfilter.c
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@ -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,