linux-kernel - Re: [PATCH net-next 0/3] Extend locked port feature with FDB locked flag (MAC-Auth/MAB)

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Date:   Wed, 16 Mar 2022 17:18:30 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Hans Schultz <schultz.hans@...il.com>, davem@...emloft.net,
        kuba@...nel.org
Cc:     netdev@...r.kernel.org,
        Hans Schultz <schultz.hans+netdev@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Ido Schimmel <idosch@...dia.com>, linux-kernel@...r.kernel.org,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next 0/3] Extend locked port feature with FDB locked
 flag (MAC-Auth/MAB)



On 3/10/2022 6:23 AM, Hans Schultz wrote:
> This patch set extends the locked port feature for devices
> that are behind a locked port, but do not have the ability to
> authorize themselves as a supplicant using IEEE 802.1X.
> Such devices can be printers, meters or anything related to
> fixed installations. Instead of 802.1X authorization, devices
> can get access based on their MAC addresses being whitelisted.
> 
> For an authorization daemon to detect that a device is trying
> to get access through a locked port, the bridge will add the
> MAC address of the device to the FDB with a locked flag to it.
> Thus the authorization daemon can catch the FDB add event and
> check if the MAC address is in the whitelist and if so replace
> the FDB entry without the locked flag enabled, and thus open
> the port for the device.
> 
> This feature is known as MAC-Auth or MAC Authentication Bypass
> (MAB) in Cisco terminology, where the full MAB concept involves
> additional Cisco infrastructure for authorization. There is no
> real authentication process, as the MAC address of the device
> is the only input the authorization daemon, in the general
> case, has to base the decision if to unlock the port or not.
> 
> With this patch set, an implementation of the offloaded case is
> supplied for the mv88e6xxx driver. When a packet ingresses on
> a locked port, an ATU miss violation event will occur. When
> handling such ATU miss violation interrupts, the MAC address of
> the device is added to the FDB with a zero destination port
> vector (DPV) and the MAC address is communicated through the
> switchdev layer to the bridge, so that a FDB entry with the
> locked flag enabled can be added.

FWIW, we may have about a 30% - 70% split between switches that will 
signal ATU violations over a side band interrupt, like mv88e6xxx will, 
and the rest will likely signal such events via the proprietary tag format.
-- 
Florian