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

From: YOSHIFUJI Hideaki <[email-masked]>
Date: Thu, 07 Feb 2013 00:32:17 +0900

Hannes Frederic Sowa wrote:
> 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 <[email-masked]>
> Cc: YOSHIFUJI Hideaki <[email-masked]>
> Signed-off-by: Hannes Frederic Sowa <[email-masked]>
> ---
>  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);

NAK.

Well, do you have relevant RFC?
RFC4291 says that we should drop ff00::/16, but not ff01::/16.

--yoshfuji