netdev - [PATCH] net: ipv6: Failure to disable forwarding per interface via sysctl

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Date:   Fri, 16 Sep 2016 10:48:10 +0100
From:   Mike Manning <mmanning@...cade.com>
To:     <netdev@...r.kernel.org>
Subject: [PATCH] net: ipv6: Failure to disable forwarding per interface via sysctl

Disabling forwarding per interface via sysctl continues to allow
forwarding. This is contrary to the sysctl documentation stating that
the forwarding sysctl is per interface, whereas currently it is only
the sysctl for all interfaces that has an effect on forwarding. The
solution is to drop any received packets instead of forwarding them
if the ingress device has a per-device forwarding sysctl that is unset.

Signed-off-by: Mike Manning <mmanning@...cade.com>
---
 net/ipv6/ip6_output.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 1dfc402..37cd1d0 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -380,11 +380,15 @@ int ip6_forward(struct sk_buff *skb)
 	struct ipv6hdr *hdr = ipv6_hdr(skb);
 	struct inet6_skb_parm *opt = IP6CB(skb);
 	struct net *net = dev_net(dst->dev);
+	struct inet6_dev *idev = __in6_dev_get(skb->dev);
 	u32 mtu;

 	if (net->ipv6.devconf_all->forwarding == 0)
 		goto error;

+	if (idev && !idev->cnf.forwarding)
+		goto error;
+
 	if (skb->pkt_type != PACKET_HOST)
 		goto drop;

-- 
1.7.10.4