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

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Date:   Wed, 24 Aug 2022 09:07:23 +0200
From:   netdev@...io-technology.com
To:     Ido Schimmel <idosch@...dia.com>
Cc:     Vladimir Oltean <olteanv@...il.com>, davem@...emloft.net,
        kuba@...nel.org, netdev@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>, Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Shuah Khan <shuah@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        linux-kernel@...r.kernel.org, bridge@...ts.linux-foundation.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v4 net-next 3/6] drivers: net: dsa: add locked fdb entry
 flag to drivers

On 2022-08-23 14:36, Ido Schimmel wrote:
> On Tue, Aug 23, 2022 at 09:37:54AM +0200, netdev@...io-technology.com 
> wrote:
> 
> "learning on locked on" is really a misconfiguration, but it can also
> happen today and entries do not roam with the "locked" flag for the
> simple reason that it does not exist. I see two options:
> 
> 1. Do not clear / set "locked" flag during roaming. Given learning
> should be disabled on locked ports, then the only half interesting case
> is roaming to an unlocked port. Keeping the "locked" flag basically
> means "if you were to lock the port, then the presence of this entry is
> not enough to let traffic with the SA be forwarded by the bridge".
> Unlikely that anyone will do that.
> 
> 2. Always set "locked" flag for learned entries (new & roamed) on 
> locked
> ports and clear it for learned entries on unlocked ports.
> 
> Both options are consistent in how they treat the "locked" flag (either
> always do nothing or always set/clear) and both do not impact the
> integrity of the solution when configured correctly (disabling learning
> on locked ports). I guess users will find option 2 easier to understand
> / work with.

Roaming to a locked port with an entry without the locked bit set would 
open the port for said MAC without necessary authorization. Thus I think 
that the only real option is the 2. case.