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

[netdev]

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.