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Date: Mon, 1 Sep 2008 09:38:27 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Stephen Hemminger <stephen.hemminger@vyatta.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>,
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       Robert Hancock <hancockr@shaw.ca>, netdev@vger.kernel.org,
       LKML <linux-kernel@vger.kernel.org>, bridge@lists.linux-foundation.org
Subject: Re: [RFC] bridge: STP timer management range checking
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> > Seems bogus extra code to me - stops things working that should be
> > allowed too.
> >   
> The timer configuration is propagated in network protocol, so 
> misconfigured Linux box
> could survive but effect other devices on the network that are less 
> robust. Maybe the

That would be irrelevant. CAP_NET_ADMIN lets you make that size mess
anyway.

> small values would cause some other bridge to crash, go infinite loop, ...
> More likely robust devices might ignore our packets (because values out 
> of range), leading to
> routing loops and other disasters.

Spamming tree isn't secure, news at 11.

> The kernel does need to stop administrative settings from taking out a 
> network. 

If you have CAP_NET_ADMIN you can trivially take out the network unless
it is properly switched.

Now you might want your pretty little GUI and/or config tools to warn
people that their configuration is outside 802 specs but that is a
different matter altogether

Alan