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

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Date:   Fri, 21 Oct 2022 15:16:21 +0200
From:   netdev@...io-technology.com
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        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 2022-10-21 13:22, Vladimir Oltean wrote:
> On Fri, Oct 21, 2022 at 08:47:42AM +0200, netdev@...io-technology.com 
> wrote:
>> On 2022-10-21 00:57, Vladimir Oltean wrote:
>> > On Thu, Oct 20, 2022 at 10:20:50PM +0200, netdev@...io-technology.com
>> > wrote:
>> > > In general locked ports block traffic from a host based on if there
>> > > is a
>> > > FDB entry or not. In the non-offloaded case, there is only CPU
>> > > assisted
>> > > learning, so the normal learning mechanism has to be disabled as any
>> > > learned entry will open the port for the learned MAC,vlan.
>> >
>> > Does it have to be that way? Why can't BR_LEARNING on a BR_PORT_LOCKED
>> > cause the learned FDB entries to have BR_FDB_LOCKED, and everything
>> > would be ok in that case (the port will not be opened for the learned
>> > MAC/VLAN)?
>> 
>> I suppose you are right that basing it solely on BR_FDB_LOCKED is 
>> possible.
>> 
>> The question is then maybe if the common case where you don't need 
>> learned
>> entries for the scheme to work, e.g. with EAPOL link local packets, 
>> requires
>> less CPU load to work and is cleaner than if using BR_FDB_LOCKED 
>> entries?
> 
> I suppose the real question is what does the bridge currently do with
> BR_LEARNING + BR_PORT_LOCKED, and if that is sane and useful in any 
> case?
> It isn't a configuration that's rejected, for sure. The configuration
> could be rejected via a bug fix patch, then in net-next it could be 
> made
> to learn these addresses with the BR_FDB_LOCKED flag.
> 
> To your question regarding the common case (no MAB): that can be 
> supported
> just fine when BR_LEARNING is off and BR_PORT_LOCKED is on, no?
> No BR_FDB_LOCKED entries will be learned.

As it is now in the bridge, the locked port part is handled before 
learning
in the ingress data path, so with BR_LEARNING and BR_PORT_LOCKED, I 
think it
will work as it does now except link local packages.

If your suggestion of BR_LEARNING causing BR_FDB_LOCKED on a locked 
port, I
guess it would be implemented under br_fdb_update() and BR_LEARNING +
BR_PORT_LOCKED would go together, forcing BR_LEARNING in this case, thus 
also
for all drivers?