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Date:   Fri, 21 Oct 2022 14:22:16 +0300
From:   Vladimir Oltean <olteanv@gmail.com>
To:     netdev@kapio-technology.com
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Subject: Re: [PATCH v8 net-next 10/12] net: dsa: mv88e6xxx: mac-auth/MAB
 implementation
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On Fri, Oct 21, 2022 at 08:47:42AM +0200, netdev@kapio-technology.com wrote:
> On 2022-10-21 00:57, Vladimir Oltean wrote:
> > On Thu, Oct 20, 2022 at 10:20:50PM +0200, netdev@kapio-technology.com
> > wrote:
> > > In general locked ports block traffic from a host based on if there
> > > is a
> > > FDB entry or not. In the non-offloaded case, there is only CPU
> > > assisted
> > > learning, so the normal learning mechanism has to be disabled as any
> > > learned entry will open the port for the learned MAC,vlan.
> > 
> > Does it have to be that way? Why can't BR_LEARNING on a BR_PORT_LOCKED
> > cause the learned FDB entries to have BR_FDB_LOCKED, and everything
> > would be ok in that case (the port will not be opened for the learned
> > MAC/VLAN)?
> 
> I suppose you are right that basing it solely on BR_FDB_LOCKED is possible.
> 
> The question is then maybe if the common case where you don't need learned
> entries for the scheme to work, e.g. with EAPOL link local packets, requires
> less CPU load to work and is cleaner than if using BR_FDB_LOCKED entries?

I suppose the real question is what does the bridge currently do with
BR_LEARNING + BR_PORT_LOCKED, and if that is sane and useful in any case?
It isn't a configuration that's rejected, for sure. The configuration
could be rejected via a bug fix patch, then in net-next it could be made
to learn these addresses with the BR_FDB_LOCKED flag.

To your question regarding the common case (no MAB): that can be supported
just fine when BR_LEARNING is off and BR_PORT_LOCKED is on, no?
No BR_FDB_LOCKED entries will be learned.