From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?UTF-8?Q?Jan_Grash=c3=b6fer?= <jan.grashoefer@gmail.com>
Subject: Re: vlan missing with AF_PACKET and auxdata
Date: Mon, 24 Sep 2018 14:22:17 +0200
Message-ID: <29cdf22a-eceb-eab9-979d-049e261a6064@gmail.com>
References: <9a284a4d29bb3301f50d7993c6bebb04@walle.cc>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Cc: "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        "Steinar H. Gunderson" <sesse@google.com>, heiko.thiery@gmail.com
To: Michael Walle <michael@walle.cc>, netdev@vger.kernel.org
Return-path: <netdev-owner@vger.kernel.org>
Received: from mail-wr1-f68.google.com ([209.85.221.68]:43412 "EHLO
        mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1732161AbeIXSYM (ORCPT
        <rfc822;netdev@vger.kernel.org>); Mon, 24 Sep 2018 14:24:12 -0400
Received: by mail-wr1-f68.google.com with SMTP id z14-v6so1957798wrs.10
        for <netdev@vger.kernel.org>; Mon, 24 Sep 2018 05:22:20 -0700 (PDT)
In-Reply-To: <9a284a4d29bb3301f50d7993c6bebb04@walle.cc>
Content-Language: en-US
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

Hi Michael,

On 24/09/2018 14:01, Michael Walle wrote:
> I'm using the AF_PACKET socket with setsockopt(PACKET_AUXDATA) to get 
> the incoming VLAN tag. Correct me if I'm wrong, but as far as I see the 
> first VLAN tag is always stripped - either in hardware or in 
> net/core/dev.c in __netif_receive_skb_core() - and stored in 
> skb->vlan_tci. Therefore, it won't be in the packet data anymore.

although the documentation says "SOCK_RAW packets are passed to and from 
the device driver without any changes in the packet data." [1] that's 
correct and was discussed here: 
https://www.spinics.net/lists/netdev/msg440313.html

Result of the discussion: Won't fix, too complicated.

Jan

[1] http://man7.org/linux/man-pages/man7/packet.7.html