Re: [PATCH v4 net-next 3/6] drivers: net: dsa: add locked fdb entry flag to drivers

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On 2022-08-14 16:55, Ido Schimmel wrote:
On Fri, Aug 12, 2022 at 02:29:48PM +0200, netdev@xxxxxxxxxxxxxxxxxxxx wrote:
On 2022-08-11 13:28, Ido Schimmel wrote:

> > > I'm talking about roaming, not forwarding. Let's say you have a locked
> > > entry with MAC X pointing to port Y. Now you get a packet with SMAC X
> > > from port Z which is unlocked. Will the FDB entry roam to port Z? I
> > > think it should, but at least in current implementation it seems that
> > > the "locked" flag will not be reset and having locked entries pointing
> > > to an unlocked port looks like a bug.

I have made the locked entries sticky in the bridge, so that they don't move to other ports.

> > >
> >

In general I have been thinking that the said setup is a network
configuration error as I was arguing in an earlier conversation with
Vladimir. In this setup we must remember that SMAC X becomes DMAC X in the return traffic on the open port. But the question arises to me why MAC X would be behind the locked port without getting authed while being behind an
open port too?
In a real life setup, I don't think you would want random hosts behind a locked port in the MAB case, but only the hosts you will let through. Other
hosts should be regarded as intruders.

If we are talking about a station move, then the locked entry will age out and MAC X will function normally on the open port after the timeout, which
was a case that was taken up in earlier discussions.

But I will anyhow do some testing with this 'edge case' (of being behind both a locked and an unlocked port) if I may call it so, and see to that the offloaded and non-offloaded cases correspond to each other, and will work
satisfactory.

It would be best to implement these as additional test cases in the
current selftest. Then you can easily test with both veth pairs and
loopbacks and see that the hardware and software data paths behave the
same.


How many loops would be needed to have a selftest with a HUB and a MAC on both a locked and an unlocked port?


I think it will be good to have a flag to enable the mac-auth/MAB feature,
and I suggest just calling the flag 'mab', as it is short.

I have now created the flag to enable Mac-Auth/MAB with iproute2:
bridge link set dev DEV macauth on|off

with the example output from 'bridge -d link show dev DEV' when macauth is enabled: 1: ethX: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master br0 state forwarding priority 32 cost 19 hairpin off guard off root_block off fastleave off learning on flood off mcast_flood on bcast_flood on mcast_router 1 mcast_to_unicast off neigh_suppress off vlan_tunnel off isolated off locked mab on

The flag itself in the code is called BR_PORT_MACAUTH.


Fine by me, but I'm not sure everyone agrees.



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