linux-kernel - Re: [PATCH net-next v1 1/1] net: bridge: ensure that link-local traffic cannot unlock a locked port

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Date:   Fri, 1 Jul 2022 18:27:00 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Ido Schimmel <idosch@...dia.com>
Cc:     Hans S <schultz.hans@...il.com>,
        Hans Schultz <hans@...io-technology.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.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>,
        Daniel Borkmann <daniel@...earbox.net>,
        Hans Schultz <schultz.hans+netdev@...il.com>,
        linux-kernel@...r.kernel.org, bridge@...ts.linux-foundation.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next v1 1/1] net: bridge: ensure that link-local
 traffic cannot unlock a locked port

On Fri, Jul 01, 2022 at 04:51:44PM +0300, Ido Schimmel wrote:
> On Fri, Jul 01, 2022 at 09:47:24AM +0200, Hans S wrote:
> > One question though... wouldn't it be an issue that the mentioned
> > option setting is bridge wide, while the patch applies a per-port
> > effect?
> 
> Why would it be an issue? To me, the bigger issue is changing the
> semantics of "locked" in 5.20 compared to previous kernels.
> 
> What is even the use case for enabling learning when the port is locked?
> In current kernels, only SAs from link local traffic will be learned,
> but with this patch, nothing will be learned. So why enable learning in
> the first place? As an administrator, I mark a port as "locked" so that
> only traffic with SAs that I configured will be allowed. Enabling
> learning when the port is locked seems to defeat the purpose?

I think if learning on a locked port doesn't make sense, the bridge
should just reject that configuration.