netdev - Re: [PATCH net v2 1/1] net/sched: act_ct: Fix flow table lookup failure with no originating ifindex

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Message-ID: <YhKCtlpgJlliT9Bc@salvia>
Date:   Sun, 20 Feb 2022 19:04:38 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Paul Blakey <paulb@...dia.com>
Cc:     dev@...nvswitch.org, netdev@...r.kernel.org,
        Jamal Hadi Salim <jhs@...atatu.com>, davem@...emloft.net,
        Jiri Pirko <jiri@...dia.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        netfilter-devel@...r.kernel.org,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Oz Shlomo <ozsh@...dia.com>, Vlad Buslov <vladbu@...dia.com>,
        Roi Dayan <roid@...dia.com>,
        Ariel Levkovich <lariel@...dia.com>, coreteam@...filter.org
Subject: Re: [PATCH net v2 1/1] net/sched: act_ct: Fix flow table lookup
 failure with no originating ifindex

Hi Paul,

On Sun, Feb 20, 2022 at 11:32:26AM +0200, Paul Blakey wrote:
> After cited commit optimizted hw insertion, flow table entries are
> populated with ifindex information which was intended to only be used
> for HW offload. This tuple ifindex is hashed in the flow table key, so
> it must be filled for lookup to be successful. But tuple ifindex is only
> relevant for the netfilter flowtables (nft), so it's not filled in
> act_ct flow table lookup, resulting in lookup failure, and no SW
> offload and no offload teardown for TCP connection FIN/RST packets.
> 
> To fix this, remove ifindex from hash, and allow lookup without
> the ifindex. Act ct will lookup without the ifindex filled.

I think it is good to add FLOW_OFFLOAD_XMIT_TC (instead of relying on
FLOW_OFFLOAD_XMIT_UNSPEC), this allows for more tc specific fields in
the future.

See attached patch.

Thanks.

View attachment "x.patch" of type "text/x-diff" (2402 bytes)