netdev - Re: [PATCH v8 net-next 10/12] net: dsa: mv88e6xxx: mac-auth/MAB implementation

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Date:   Fri, 21 Oct 2022 21:14:11 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     netdev@...io-technology.com
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        Oleksandr Mazur <oleksandr.mazur@...ision.eu>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Kurt Kanzenbach <kurt@...utronix.de>,
        Hauke Mehrtens <hauke@...ke-m.de>,
        Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.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>,
        Russell King <linux@...linux.org.uk>,
        Christian Marangi <ansuelsmth@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Yuwei Wang <wangyuweihx@...il.com>,
        Petr Machata <petrm@...dia.com>,
        Ido Schimmel <idosch@...dia.com>,
        Florent Fourcot <florent.fourcot@...irst.fr>,
        Hans Schultz <schultz.hans@...il.com>,
        Joachim Wiberg <troglobit@...il.com>,
        Amit Cohen <amcohen@...dia.com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        bridge@...ts.linux-foundation.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v8 net-next 10/12] net: dsa: mv88e6xxx: mac-auth/MAB
 implementation

On Fri, Oct 21, 2022 at 07:39:34PM +0200, netdev@...io-technology.com wrote:
> Well, with this change, to have MAB working, the bridge would need learning on
> of course, but how things work with the bridge according to the flags, they
> should also work in the offloaded case if you ask me. There should be no
> difference between the two, thus MAB in drivers would have to be with
> learning on.

Am I proposing for things to work differently in the offload and
software case, and not realizing it? :-/

The essence of my proposal was to send a bug fix now which denies
BR_LEARNING to be set together with BR_PORT_LOCKED. The fact that
link-local traffic is learned by the software bridge is something
unintended as far as I understand.

You tried to fix it here, and as far as I could search in my inbox, that
didn't go anywhere:
https://lore.kernel.org/netdev/47d8d747-54ef-df52-3b9c-acb9a77fa14a@blackwall.org/T/#u

I thought only mv88e6xxx offloads BR_PORT_LOCKED, but now, after
searching, I also see prestera has support for it, so let me add
Oleksandr Mazur to the discussion as well. I wonder how they deal with
this? Has somebody come to rely on learning being enabled on a locked
port?

MAB in offloading drivers will have to be with learning on (same as in
software). When BR_PORT_LOCKED | BR_LEARNING will be allowed together
back in net-next (to denote the MAB configuration), offloading drivers
(mv88e6xxx and prestera) will be patched to reject them. They will only
accept the two together when they implement MAB support.

Future drivers after this mess has been cleaned up will have to look at
the BR_PORT_LOCKED and BR_LEARNING flag in combination, to see which
kind of learning is desired on a port (secure, CPU based learning or
autonomous learning).

Am I not making sense?