netdev - Re: multicasting netlink messages to groups

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Message-ID: <468CF41E.4020409@trash.net>
Date:	Thu, 05 Jul 2007 15:37:34 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Johannes Berg <johannes@...solutions.net>
CC:	netdev <netdev@...r.kernel.org>, jamal <hadi@...erus.ca>,
	Thomas Graf <tgraf@...g.ch>,
	Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: multicasting netlink messages to groups > 31 from userspace

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.

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