netdev - Re: [IPv6] interface-local multicast escapes the local node

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Date:	Wed, 6 Feb 2013 14:49:50 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Erik Hugne <erik.hugne@...csson.com>
Cc:	netdev@...r.kernel.org, yoshfuji@...ux-ipv6.org
Subject: Re: [IPv6] interface-local multicast escapes the local node

On Wed, Feb 06, 2013 at 02:07:39PM +0100, Erik Hugne wrote:
> On Wed, Feb 06, 2013 at 01:12:48PM +0100, Hannes Frederic Sowa wrote:
> > Fixing the output path should be relatively straightforward, please test
> > the following patch.
> 
> Tested OK.
> 
> > Looking at the input path, I think there is also no input protection
> > for ff01::/16 addresses from the wire if you bind such an address.
> 
> Yes, this needs to be filtered on the input side aswell.

This patch should do the trick. Perhaps you could also take it for a test
drive? Thanks!

[PATCH net-next] ipv6: don't accept node local multicast traffic from the wire

Cc: Erik Hugne <erik.hugne@...csson.com>
Cc: YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
 net/ipv6/ip6_input.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 4ac5bf3..a2f71d2 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -126,6 +126,16 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt
 	if (ipv6_addr_is_multicast(&hdr->saddr))
 		goto err;
 
+	/*
+	 * RFC4291 2.7
+	 * Interface-Local scope spans only a single interface on a node
+         * and is useful only for loopback transmission of multicast.
+	 */
+	if (ipv6_addr_is_multicast(&hdr->daddr) &&
+	    IPV6_ADDR_MC_SCOPE(&hdr->daddr) <= IPV6_ADDR_SCOPE_NODELOCAL &&
+	    skb->pkt_type != PACKET_LOOPBACK)
+		goto err;
+
 	skb->transport_header = skb->network_header + sizeof(*hdr);
 	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 
-- 
1.8.1


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