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

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Date:   Sat, 22 Oct 2022 15:15:03 +0200
From:   netdev@...io-technology.com
To:     Vladimir Oltean <olteanv@...il.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 2022-10-22 14:02, Vladimir Oltean wrote:
> On Sat, Oct 22, 2022 at 09:24:56AM +0200, netdev@...io-technology.com 
> wrote:
>> I will not say that you are not making sense as for the mv88e6xxx, as 
>> it
>> needs port association in all cases with BR_PORT_LOCKED, MAB or not, 
>> and
>> port association is turned on in the driver with learning turned on.
>> 
>> That said, there must be some resolution and agreement overall with 
>> this
>> issue to move on. Right now port association is turned on in the 
>> mv88e6xxx
>> driver when locking the port, thus setting learning off after locking 
>> will
>> break things.
> 
> This already needs to be treated as a bug and fixed on its own. Forget
> about MAB.
> 
> You're saying that when BR_LEARNING=on and BR_PORT_LOCKED=on, the
> mv88e6xxx driver works properly, but the software bridge is broken
> (learns from link-local multicast).
> 
> When BR_LEARNING=off and BR_PORT_LOCKED=on, the software bridge is not
> broken, but the mv88e6xxx driver is, because it requires the PAV
> configured properly.
> 
> And you're saying that I'm the one who suggests things should work
> differently in software mode vs offloaded mode?!

Well :-) To be specific, I am talking about how things work from a user
perspective, where I have kept to BR_LEARNING off before turning
BR_PORT_LOCKED on.

I admit to a weakness in that BR_LEARNING off after BR_PORT_LOCKED on is
a problem that from my perspective at this point would be a user error.

> 
> Why don't you
> (a) deny BR_LEARNING + BR_PORT_LOCKED in the bridge layer
> (b) fix the mv88e6xxx driver to always keep the assoc_vector set
>     properly for the port, if BR_LEARNING *or* BR_PORT_LOCKED is set?

(a) yes, I have thought that documentation could handle this, but maybe
     you are right, maybe it should be enforced...
(b) BR_PORT_LOCKED ensures now that the PAV is correctly set, so I have
     basically distinguished between learning and port association (which
     I know mechanically is the same in mv88e6xxx), but still I have
     adhered to learning off while port association is on for the port.