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

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Date:	Sun, 10 Feb 2013 10:59:54 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
Cc:	Erik Hugne <erik.hugne@...csson.com>, netdev@...r.kernel.org,
	YOSHIFUJI Hideaki <yoshfuji@...e.ad.jp>
Subject: Re: [IPv6] interface-local multicast escapes the local node

On Sat, Feb 09, 2013 at 11:12:46PM +0900, YOSHIFUJI Hideaki wrote:
> It seems applications will join ff01::/16%eth0 instead of ff01::/16%lo.
> If so, your original patch seems better.  My bad, sorry.
> 
> Would you update original one, with minor modification that defers
> kfree_skb() after incrementing MIB, please?

I would add another constraint to the if "&& !(dev->flags & IFF_LOOPBACK)", so
it becomes:

                if (IPV6_ADDR_MC_SCOPE(&ipv6_hdr(skb)->daddr) <=
                    IPV6_ADDR_SCOPE_NODELOCAL &&
                    !(dev->flags & IFF_LOOPBACK))
                        kfree_skb(skb);
                        return 0;
                }


Otherwise ff01::/16%lo would not work because the multicast mirroring through
dev_loopback_xmit won't be taken and the packet would be dropped after that.

Can you confirm? Thanks.

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