linux-kernel - Re: [PATCH] net: igmp: Use correct source address on IGMPv3 reports

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Message-ID: <20171213171516.GH28466@lunn.ch>
Date:   Wed, 13 Dec 2017 18:15:16 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Kevin Cernekee <cernekee@...omium.org>
Cc:     davem@...emloft.net, kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: igmp: Use correct source address on IGMPv3 reports

On Mon, Dec 11, 2017 at 11:13:45AM -0800, Kevin Cernekee wrote:
> Closing a multicast socket after the final IPv4 address is deleted
> from an interface can generate a membership report that uses the
> source IP from a different interface.  The following test script, run
> from an isolated netns, reproduces the issue:
> 
>     #!/bin/bash
> 
>     ip link add dummy0 type dummy
>     ip link add dummy1 type dummy
>     ip link set dummy0 up
>     ip link set dummy1 up
>     ip addr add 10.1.1.1/24 dev dummy0
>     ip addr add 192.168.99.99/24 dev dummy1
> 
>     tcpdump -U -i dummy0 &
>     socat EXEC:"sleep 2" \
>         UDP4-DATAGRAM:239.101.1.68:8889,ip-add-membership=239.0.1.68:10.1.1.1 &
> 
>     sleep 1
>     ip addr del 10.1.1.1/24 dev dummy0
>     sleep 5
>     kill %tcpdump
> 
> RFC 3376 specifies that the report must be sent with a valid IP source
> address from the destination subnet, or from address 0.0.0.0.  Add an
> extra check to make sure this is the case.
> 
> Signed-off-by: Kevin Cernekee <cernekee@...omium.org>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew