netdev - Re: VRF + ip xfrm, egress ESP packet looping when qdisc configured

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Date:   Sun, 2 Feb 2020 21:04:25 -0700
From:   David Ahern <dsahern@...il.com>
To:     Trev Larock <trev@...ock.ca>
Cc:     Ben Greear <greearb@...delatech.com>, netdev@...r.kernel.org
Subject: Re: VRF + ip xfrm, egress ESP packet looping when qdisc configured

On 2/2/20 8:13 PM, Trev Larock wrote:
> On Mon, Jan 13, 2020 at 11:51 AM David Ahern <dsahern@...il.com> wrote:
>> Trev's problem is looping due to the presence of the qdisc. The vrf
>> driver needs to detect that it has seen the packet and not redirect it
>> again.
> Yes note it was when specifying no dev on the xfrm policy/state.
> For the non-qdisc case the policy triggered from the __ip4_datagram_connect->
> xfrm_lookup and the vrf "direct" route sent it out without any xfrm_lookup call.
> It appears to work but it's not really a "xfrm vrf specific " policy.
> 
> For qdisc the policy matched again on the vrf->xfrm_lookup call.
> 

I understand the problem you are facing. It is limited to xfrm + 	qdisc
on VRF device. I have a proposal for how to fix it:

    https://github.com/dsahern/linux vrf-qdisc-xfrm

Right now I am stuck on debugging related xfrm cases - like xfrm
devices, vrf device in the selector, and vti device. I feel like I need
to get all of them working before sending patches, I just lack enough time.