netdev - Re: OVS VXLAN decap rule has full match on TTL for the outer headers?

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Date:	Thu, 10 Dec 2015 15:53:47 -0800
From:	Joe Stringer <joe@....org>
To:	Or Gerlitz <gerlitz.or@...il.com>
Cc:	Jarno Rajahalme <jarno@....org>, Jesse Gross <jesse@...nel.org>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Haggai Eran <haggaie@...lanox.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Ilya Lesokhin <ilyal@...lanox.com>,
	Rony Efraim <ronye@...lanox.com>,
	Hadar Hen Zion <hadarh@...lanox.com>,
	Tal Anker <Ankertal@...lanox.com>
Subject: Re: OVS VXLAN decap rule has full match on TTL for the outer headers?

On 10 December 2015 at 13:43, Or Gerlitz <gerlitz.or@...il.com> wrote:
> On Thu, Dec 10, 2015 at 11:23 PM, Joe Stringer <joe@....org> wrote:
>> On 10 December 2015 at 13:06, Or Gerlitz <gerlitz.or@...il.com> wrote:
>>> On Wed, Dec 9, 2015 at 2:22 AM, Joe Stringer <joe@....org> wrote:
>
>>>>>> As far as the mask, I briefly discussed this with Jarno and it seems
>>>>>> like it could be something as simple as zeroing the ip_ttl mask in
>>>>>> tnl_wc_init().
>
>>>>> to make sure I follow, will that have the consequence that we (user +
>>>>> kernel) will practically not be testing the ttl for these flows?
>
>>>> Yes, it would cause userspace to 'wildcard' the field so the kernel
>>>> flows that are installed will ignore it during lookup.
>
>>> Cool, any chance this is gonna fit into your schedule to meet 4.4? if
>>> not, for 4.5?
>>> Also, can the patch be made simple/small enough to go into -stable as well?
>
>> It's a userspace change.
>
>
> mmm, in a downstream post of this thread [1] Haggai pointed to you
> that there's code in the OVS kernel path that that rejects new tunnel
> flows if they don't have the TTL mask set, so he's wrong? where?
>
> Or.
>
> [1] http://marc.info/?l=linux-netdev&m=144880328121156&w=2

The rejection is within an if statement called "if (!is_mask)", so it
seems to me like it is enforcing the flow key to specify a TTL value
(any), and doesn't care what the mask does.
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