netdev - Re: [PATCH net-next 16/17] Documentation: networking: dsa: Add details about NXP SJA1105 driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <47131b09-8f39-0cdc-70cd-809b64448097@gmail.com>
Date:   Wed, 3 Apr 2019 13:09:29 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     f.fainelli@...il.com, vivien.didelot@...il.com,
        davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linus.walleij@...aro.org,
        georg.waibel@...sor-technik.de
Subject: Re: [PATCH net-next 16/17] Documentation: networking: dsa: Add
 details about NXP SJA1105 driver

On 4/3/19 12:24 AM, Andrew Lunn wrote:
>> +The switches do not support switch tagging in hardware. But they do support
>> +customizing the TPID by which VLAN traffic is identified as such. The switch
>> +driver is leveraging CONFIG_NET_DSA_TAG_8021Q by requesting that special VLANs
>> +(with a custom TPID of ETH_P_EDSA instead of ETH_P_8021Q)
> 
> Hi Vladimir
> 
> Reusing ETH_P_EDSA is possibility going to case problems in tcpdump.
> It has code which looks for this Ethertype and uses it to call the
> Marvell EDSA header decoder code. This is not going to work for your
> switch, where you have a normal VLAN header.
> 
> I wounder if we should allocate a new EtherType for this application
> of VLANs?
> 
>     Andrew
> 

Hi Andrew,

This makes me wonder whether I would be able to use an EtherType range 
to support cascading switch tags on SJA1105.
In theory if I were to consistently lie to all switches within a switch 
tree, I could make all of them see each other's fake VLAN-tagged traffic 
as untagged.
By the way what is the simple ETH_P_DSA used for?

Thank you,
-Vladimir