On Thu, Jul 30, 2015 at 10:26:08PM +0200, Kenneth Klette Jonassen wrote: > 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…
Do you have an application or test case that is now broken after this commit? Or is this just a theoretical breakage based off of my commit message? If you have a simple example test case can you share it? Also if this breaks your application but you don't have a test case can you describe the breakage? Is IP_MULTICAST_ALL 0 or 1? Are you not receiving packets or receiving packets you don't expect to receive? I admittedly haven't tried to create a test case yet, but looking over the code I'm not sure how this could have broken IP_MULTICAST_ALL. Commit 6e54030 added a call to ip_check_mc_rcu() which as far as I can tell checks to see that a received multicast packet was a mc address joined on that interface. Without this check it is possible to receive multicast packets for an address that hasn't been joined on that machine at all. Which was the bug I was fixing. The ip_mc_sf_allow() check comes next, and is still there. It should continue to provide the behavior you quoted from the man page. It isn't/wasn't sufficient to use IP_MULTICAST_ALL as a fix for the original bug because as I mentioned above you could receive packets that nothing on the machine had joined. -- Shawn -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
