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

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Message-ID: <20221021112216.6bw6sjrieh2znlti@skbuf>
Date:   Fri, 21 Oct 2022 14:22:16 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     netdev@...io-technology.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 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.