netdev - Re: [PATCH net-next 3/3] net/sched: Introduce act

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Date:   Tue, 23 Aug 2016 19:05:37 +0300
From:   Amir Vadai <amir@...ai.me>
To:     Jiri Benc <jbenc@...hat.com>
Cc:     Or Gerlitz <gerlitz.or@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Linux Netdev List <netdev@...r.kernel.org>,
        John Fastabend <john.r.fastabend@...el.com>,
        Jiri Pirko <jiri@...lanox.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Or Gerlitz <ogerlitz@...lanox.com>,
        Hadar Har-Zion <hadarh@...lanox.com>
Subject: Re: [PATCH net-next 3/3] net/sched: Introduce act_iptunnel

On Tue, Aug 23, 2016 at 05:33:49PM +0200, Jiri Benc wrote:
> On Tue, 23 Aug 2016 18:28:05 +0300, Amir Vadai wrote:
> > On Mon, Aug 22, 2016 at 08:51:37PM +0200, Jiri Benc wrote:
> > > 2. We may run into problems like tx path seeing the metadata_dst that
> > >    it should not see. This means either this situation or such
> > >    configuration must be prevented somehow.
> [...]
> > Anyway, this issue is orthogonal to this patchset...
> 
> Not really. If it's indeed (2) then such configuration needs to be
> rejected. 
The configuration that needs to be rejected is when act_iptunnel is not
used. So, I guess the fix won't be part of it...

> Or metadata_dst freed at an appropriate place. Thus it's
> something that needs to be handled by this patchset before the uAPI is
> set in stone.
It is already there - user can use act_mirred and redirect skb's with
metadata since shared tunnel devices introduced.
The only thing that was added here, is to enable the user to drop the
metadata, which I think we agree is the ok.

But I agree with you, that I must understand the life cycle of the metadata and dst
better. I will try to understand it better and explain/fix accordingly.

Again, would be happy if someone will chime in and give some hints if it
was a bug, that a user could redirect skb's with metadata, or something
harmless.

Thanks,
Amir
> 
>  Jiri