From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pravin Shelar <pshelar@ovn.org>
Subject: Re: [PATCH v2] openvswitch: Trim off padding before L3+ netfilter processing
Date: Sat, 6 Jan 2018 10:57:56 -0800
Message-ID: <CAOrHB_A1sQWforWuUve5phrxPjSOpbTEQ4F5h3beh1C9qWmUTw@mail.gmail.com>
References: <1513095439-128864-1-git-send-email-eswierk@skyportsystems.com>
 <1513869437-20059-1-git-send-email-eswierk@skyportsystems.com>
 <CAOrHB_D_xUoynncs_W3EcKtpc2yyYuvUgAg1G=7GNJvgnFt=ow@mail.gmail.com>
 <CAO_EM_=J-1s4DPTt6WpBPD2eC2Ek13THQ=6jYeuB0mZB41tpvQ@mail.gmail.com>
 <CAOrHB_D1mj_0O+_e3+GxxcTiuk0B5w5cc6qf90jM+fGiw8oAhw@mail.gmail.com>
 <CAO_EM_kFtsEBbVS9T00skKCpO0C72uDh=KQa8XWqS_8hSUfzVg@mail.gmail.com>
 <CAO_EM_mQgURXZNtW7Qw7OkW4rjp4JWKBmqS8e4pUR=ZuiGCcZQ@mail.gmail.com>
 <CAOrHB_DwPGBEjPReZZ51uked_oq0OYB30S_Y7Si5+eRWF1Pb6Q@mail.gmail.com> <CAO_EM_=2qt3zSW1xprkLvcQVKGRTFMUQxCc4-cVLsUcRLj63Hg@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Cc: ovs-dev <ovs-dev@openvswitch.org>, netdev <netdev@vger.kernel.org>,
        Benjamin Warren <ben@skyportsystems.com>,
        Keith Holleman <holleman@skyportsystems.com>
To: Ed Swierk <eswierk@skyportsystems.com>
Return-path: <netdev-owner@vger.kernel.org>
Received: from relay2-d.mail.gandi.net ([217.70.183.194]:45447 "EHLO
        relay2-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751524AbeAFS56 (ORCPT
        <rfc822;netdev@vger.kernel.org>); Sat, 6 Jan 2018 13:57:58 -0500
Received: from mail-wm0-f52.google.com (mail-wm0-f52.google.com [74.125.82.52])
        (Authenticated sender: pshelar@ovn.org)
        by relay2-d.mail.gandi.net (Postfix) with ESMTPSA id 96364C5A51
        for <netdev@vger.kernel.org>; Sat,  6 Jan 2018 19:57:57 +0100 (CET)
Received: by mail-wm0-f52.google.com with SMTP id 64so7702929wme.3
        for <netdev@vger.kernel.org>; Sat, 06 Jan 2018 10:57:57 -0800 (PST)
In-Reply-To: <CAO_EM_=2qt3zSW1xprkLvcQVKGRTFMUQxCc4-cVLsUcRLj63Hg@mail.gmail.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

On Fri, Jan 5, 2018 at 10:59 PM, Ed Swierk <eswierk@skyportsystems.com> wrote:
>
>
> On Jan 5, 2018 22:17, "Pravin Shelar" <pshelar@ovn.org> wrote:
>
> On Fri, Jan 5, 2018 at 3:20 PM, Ed Swierk <eswierk@skyportsystems.com>
> wrote:
>> On Fri, Jan 5, 2018 at 10:14 AM, Ed Swierk <eswierk@skyportsystems.com>
>> wrote:
>>> On Thu, Jan 4, 2018 at 7:36 PM, Pravin Shelar <pshelar@ovn.org> wrote:
>>>> OVS already pull all required headers in skb linear data, so no need
>>>> to redo all of it. only check required is the ip-checksum validation.
>>>> I think we could avoid it in most of cases by checking skb length to
>>>> ipheader length before verifying the ip header-checksum.
>>>
>>> Shouldn't the IP header checksum be verified even earlier, like in
>>> key_extract(), before actually using any of the fields in the IP
>>> header?
>>
>> Something like this for verifying the IP header checksum (not tested):
>>
> AFAIU openflow does not need this verification, so it is not required
> in flow extract.
>
>
> Okay. How about my proposed trimming implementation, caching the pad length
> in the ovs cb?
>
Caching the length is not that simple, OVS actions can change the
length. Keeping it consistent with packet would be more work, so lets
calculate it in ovs-ct function.