netdev - Re: ipv4/udp: Verify multicast group is ours in upd_v4_early

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Date:	Thu, 30 Jul 2015 22:26:08 +0200
From:	Kenneth Klette Jonassen <kennetkl@....uio.no>
To:	sbohrer@...advisors.com, netdev <netdev@...r.kernel.org>
Cc:	Yurij.Plotnikov@...etlabs.ru, David Miller <davem@...emloft.net>,
	Ståle Kristoffersen <stalk@...dgetech.tv>
Subject: Re: ipv4/udp: Verify multicast group is ours in upd_v4_early_demux()

Commit 6e54030 breaks the IP_MULTICAST_ALL socket option. There is
already a check in ip_mc_sf_allow() that should do the filtering you
claim to fix. Was it considered?

Commit message:
421b3885bf6d56391297844f43fb7154a6396e12 "udp: ipv4: Add udp early
demux" introduced a regression that allowed sockets bound to INADDR_ANY
to receive packets from multicast groups that the socket had not joined...

man ip(7):
IP_MULTICAST_ALL (since Linux 2.6.31)
This option can be used to modify the delivery policy of
multicast messages to sockets bound to the wildcard INADDR_ANY
address.  The argument is a boolean integer (defaults to 1).
If set to 1, the socket will receive messages from all the
groups that have been joined globally on the whole system.
Otherwise, it will deliver messages only from the groups that
have been explicitly joined…
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