[PATCH] net: netfilter: Fix ipv6 rp_filter dropping vrf packets by mistake

From: linmiaohe
Date: Wed Apr 24 2019 - 03:27:47 EST


From: Miaohe Lin <linmiaohe@xxxxxxxxxx>

When firewall is enabled with rp_filter, vrf ipv6 packets
will be dropped because in device is vrf but out device
is an enslaved device. So rt->rt6i_idev->dev != dev and
maybe return false in func rpfilter_lookup_reverse6.

Here is the out message when I ping the peer:
ip vrf exec vrf1 ping 2013::2 -c 1
1 packets transmitted, 0 received, 100% packet loss, time 0ms

The drop info in /var/log/message:
Apr 24 14:59:45 localhost kernel: [81316.158259] rpfilter_DROP: IN=vrf1
OUT= MAC=52:54:00:9e:dd:c1:52:54:00:4f:81:38:86:dd
SRC=2013:0000:0000:0000:0000:0000:0000:0002
DST=2013:0000:0000:0000:0000:0000:0000:0001 LEN=104 TC=0 HOPLIMIT=64
FLOWLBL=1032942 PROTO=ICMPv6 TYPE=129 CODE=0 ID=14943 SEQ=1

Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
net/ipv6/netfilter/ip6t_rpfilter.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/net/ipv6/netfilter/ip6t_rpfilter.c b/net/ipv6/netfilter/ip6t_rpfilter.c
index c3c6b09acdc4..5cbc91f53736 100644
--- a/net/ipv6/netfilter/ip6t_rpfilter.c
+++ b/net/ipv6/netfilter/ip6t_rpfilter.c
@@ -73,6 +73,12 @@ static bool rpfilter_lookup_reverse6(struct net *net, const struct sk_buff *skb,
goto out;
}

+ if (netif_is_l3_master(dev)) {
+ dev = __dev_get_by_index(dev_net(dev), IP6CB(skb)->iif);
+ if (!dev)
+ goto out;
+ }
+
if (rt->rt6i_idev->dev == dev || (flags & XT_RPFILTER_LOOSE))
ret = true;
out:
--
2.19.1