4.20-stable review patch. If anyone has any objections, please let me know.
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From: Eli Cooper elicooper@gmx.com
commit 15df03c661cb362366ecfc3a21820cb934f3e4ca upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/ipv6/netfilter.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/net/ipv6/netfilter.c +++ b/net/ipv6/netfilter.c @@ -23,9 +23,11 @@ int ip6_route_me_harder(struct net *net, 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,