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

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Date:   Thu, 17 Mar 2022 09:29:10 +0100
From:   Hans Schultz <schultz.hans@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Hans Schultz <schultz.hans@...il.com>, davem@...emloft.net,
        kuba@...nel.org
Cc:     netdev@...r.kernel.org, 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 ons, mar 16, 2022 at 17:18, Florian Fainelli <f.fainelli@...il.com> wrote:
> 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.

I guess that the proprietary tag scheme a scenario where the packet can
be forwarded to the bridge module's ingress queue on the respective
port?

> -- 
> Florian