netdev - Re: [PATCH net-next v2 9/9] net: dsa: mv88e6xxx: add cross-chip bridging

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Date:   Fri, 31 Mar 2017 12:55:03 -0400
From:   Vivien Didelot <vivien.didelot@...oirfairelinux.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...oirfairelinux.com,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>
Subject: Re: [PATCH net-next v2 9/9] net: dsa: mv88e6xxx: add cross-chip bridging

Hi Andrew,

Andrew Lunn <andrew@...n.ch> writes:

> On Thu, Mar 30, 2017 at 05:37:15PM -0400, Vivien Didelot wrote:
>> Implement the DSA cross-chip bridging operations by remapping the local
>> ports an external source port can egress frames to, when this cross-chip
>> port joins or leaves a bridge.
>> 
>> The PVT is no longer configured with all ones allowing any external
>> frame to egress any local port. Only DSA and CPU ports, as well as
>> bridge group members, can egress frames on local ports.
>
> With the ZII devel B, we have two switches with PVT, and one
> without. What happens in this setup? Can the non-PVT switch leak
> frames out user ports which should otherwise be blocked?

If CONFIG_BRIDGE_VLAN_FILTERING isn't enabled in the kernel, the non-PVT
switch would indeed have no mean to restrict arbitrary external
frames. So in that setup, yes the switch can theorically leak frames.

With a VLAN-filtering aware system, the VTU policy and 802.1Q Secure
port mode should guard against that.

Thanks,

        Vivien