netdev - Re: [PATCH net-next v3 1/2] net: dsa: untag the bridge pvid from rx skbs

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Message-ID: <c8ca2861-44b2-4333-d63e-638dfe2f06a0@gmail.com>
Date:   Wed, 23 Sep 2020 15:06:33 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vladimir Oltean <vladimir.oltean@....com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "olteanv@...il.com" <olteanv@...il.com>,
        "nikolay@...dia.com" <nikolay@...dia.com>
Subject: Re: [PATCH net-next v3 1/2] net: dsa: untag the bridge pvid from rx
 skbs

On 9/23/20 3:01 PM, Vladimir Oltean wrote:
> On Wed, Sep 23, 2020 at 02:51:09PM -0700, Florian Fainelli wrote:
>> Speaking of that part of the code, I was also wondering whether you
>> wanted this to be netdev_for_each_upper_dev_rcu(br, upper_dev, iter) and
>> catch a bridge device upper as opposed to a switch port upper? Either
>> way is fine and there are possibly use cases for either.
> 
> So, yeah, both use cases are valid, and I did in fact mean uppers of the
> bridge, but now that you're raising the point, do we actually support
> properly the use case with an 8021q upper of a bridged port? My
> understanding is that this VLAN-tagged traffic should not be switched on
> RX. So without some ACL rule on ingress that the driver must install, I
> don't see how that can work properly.

Is not this a problem only if the DSA master does VLAN receive filtering
though? In a bridge with vlan_filtering=0 the switch port is supposed to
accept any VLAN tagged frames because it does not do ingress VLAN ID
checking.

Prior to your patch, I would always install a br0.1 upper to pop the
default_pvid and that would work fine because the underlying DSA master
does not do VLAN filtering.
-- 
Florian