netdev - Re: [PATCH v5 net-next 6/6] selftests: forwarding: add test of MAC-Auth Bypass to locked port tests

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Message-ID: <d020fe746b30dd048970b3668ffad498@kapio-technology.com>
Date:   Wed, 28 Sep 2022 09:29:00 +0200
From:   netdev@...io-technology.com
To:     Ido Schimmel <idosch@...dia.com>
Cc:     Vladimir Oltean <olteanv@...il.com>, 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>,
        Christian Marangi <ansuelsmth@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Yuwei Wang <wangyuweihx@...il.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 v5 net-next 6/6] selftests: forwarding: add test of
 MAC-Auth Bypass to locked port tests

On 2022-09-28 08:59, Ido Schimmel wrote:
> Sorry for the delay, was away.

Good to have you back. :-)

> 
> On Tue, Sep 27, 2022 at 10:33:10AM +0200, netdev@...io-technology.com 
> wrote:
>> On 2022-09-21 09:15, Ido Schimmel wrote:
>> > 	bridge fdb add `mac_get $h2` dev br0 blackhole
>> 
>> To make this work, I think we need to change the concept, so that 
>> blackhole
>> FDB entries are added to ports connected to the bridge, thus
>>      bridge fdb add MAC dev $swpX master blackhole
>> 
>> This makes sense as the driver adds them based on the port where the 
>> SMAC is
>> seen, even though the effect of the blackhole FDB entry is switch 
>> wide.
> 
> Asking user space to associate a blackhole entry with a bridge port 
> does
> not make sense to me because unlike regular entries, blackhole entries
> do not forward packets out of this port. Blackhole routes and nexthops
> are not associated with a device either.
> 
>> Adding them to the bridge (e.g. f.ex. br0) will not work in the SW 
>> bridge as
>> the entries then are not found.
> 
> Why not found? This works:
> 
>  # bridge fdb add 00:11:22:33:44:55 dev br0 self local
>  $ bridge fdb get 00:11:22:33:44:55 br br0
>  00:11:22:33:44:55 dev br0 master br0 permanent
> 
> With blackhole support I expect:
> 
>  # bridge fdb add 00:11:22:33:44:55 dev br0 self local blackhole
>  $ bridge fdb get 00:11:22:33:44:55 br br0
>  00:11:22:33:44:55 dev br0 master br0 permanent blackhole

In my previous replies, I have notified that fdb_find_rcu() does not 
find the entry added with br0, and thus fdb_add_entry() that does the 
replace does not replace but adds a new entry. I have been thinking that 
it is because when added with br0 as dev it is added to dev br0's fdb, 
which is not the same as 'dev <Dev> master' fdb...

I think bridge fdb get works in a different way, as I know the get 
functionality gets all fdb entries from all devices and filters them (if 
I am not mistaken)...