netdev - Re: [PATCH] bridge: Forward EAPOL Kconfig option BRIDGE_PAE

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Date:	Tue, 28 Jun 2011 22:22:53 +0100
From:	Nick Carter <ncarter100@...il.com>
To:	David Lamparter <equinox@...c24.net>
Cc:	Stephen Hemminger <shemminger@...ux-foundation.org>,
	netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH] bridge: Forward EAPOL Kconfig option BRIDGE_PAE_FORWARD

On 28 June 2011 22:04, David Lamparter <equinox@...c24.net> wrote:
> On Tue, Jun 28, 2011 at 09:54:01PM +0100, Nick Carter wrote:
>> > 'reinject' isn't possible when it hits that code path - which is pretty
>> > much why I'm saying we should be forwarding everything in the non-STP
>> > case.
>> I'm not sure I like this turn off STP and suddenly start forwarding
>> random groups.  There is no connection between wanting STP on / off
>> and forwarding pae on / off.
>
> I beg to differ, there very much is. You never ever ever want to be
> running STP with 802.1X packets passing through... some client will shut
> down your upstream port, your STP will break and you will die in a fire.
>
> The general idea, though, is that a STP-enabled switch is an intelligent
> switch. And an intelligent switch can speak all those pesky small
> side-dish protocols.
>
> With STP disabled on the other hand, it depends on site policy. Now
> policy...
>
>> There is no dependencies between the protocols.
>> Also on reflection I think a knob per mac group would be better.
>
> .... policy can be done nice and good with ebtables. You can match the
> groups you want, or the protocols, or the phase of the moon.
>
>> We are only interested in 3 and if I enable pae forwarding so I can
>> connect virtual machine supplicants, i don't then want to turn on LDP
>> forwarding which will needlessly hit my virtual machines.
>> So how about sysfs
>> ../bridge/pae_forwarding
>> ../bridge/ldp_forwarding
>> ../bridge/mvrp_forwarding
>
> It's not like either LLDP or MVRP will trash your VMs. Those protocols
> send a packet once per a few seconds.
>
> MVRP is interesting for the STP-enabled case though. I'm not aware of
> any userspace *VRP implementations, and dropping *VRP without an
> userspace daemon to speak it on our behalf means we're creating a *VRP
> border/break.
>
> I would however say that doing an userspace *VRP implementation is a
> better solution than kernel hacks for this particular case.
>
>> > (Some quick googling reveals that hardware switch chips special-drop
>> > 01:80:c2:00:00:01 [802.3x/pause] and :02 [802.3ad/lacp] and nothing
>> > else - for the dumb ones anyway. It also seems like the match for pause
>> > frames usually works on the address, not on the protocol field like we
>> > do it...)
>> 'Enterprise' switches drop :03 [802.1x]
>
> They also speak STP, see above about never STP+1X :)
But if you turn off STP they wont start forwarding 802.1x.
Also having STP on and forwarding 802.1x would be useful (but
non-standard) in some cheap redundant periphery switches, connecting
to a couple of 'core' switches acting as 802.1x authenticators.
Nick
>
> -David
>
>
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