Subject: Re: multicasting netlink messages to groups > 31 from userspace

From: Patrick McHardy <[email-masked]>
Date: Thu, 05 Jul 2007 15:37:34 +0200

Johannes Berg wrote:
> On Wed, 2007-07-04 at 17:00 +0200, Patrick McHardy wrote:
> 
> 
>>Not by itself probably but a user could DoS your wireless connectivity
>>this way.
> 
> 
> Hmm, if anything then not the connectivity but rather the MLME i.e. it
> won't do roaming properly maybe. Maybe we should then have a way to say
> that somebody only wants to receive messages from privileged users, that
> way the MLME process wouldn't be affected.

Earlier filtering makes sense, especially for userspace. The other
part exceeds my wireless knowledge :)

>>I'm not sure, it would probably also have to be called when userspace
>>unsubscribes from a group, no?
> 
> 
> No actually having that hook means I can do without multicast groups by
> just publishing that "send configuration requests to pid N" where N is
> either 0 (in-kernel MLME) or something else (userspace MLME); I just
> didn't know the hook existed.

Even better. Publishing that to userspace is going to be racy though.

> Not that we shouldn't fix the multicast issues anyway though the one
> from this particular thread wouldn't be too interesting right now until
> somebody needs userspace to multicast; the other three patches still
> should be done now before there are more generic netlink multicast
> users.

The genetlink stuff defintely makes sense. I'll have a closer look at
your patches this weekend.