netdev - Re: [PATCH V4 net 0/2] ipv6: fix flowlabel issue for reset packet

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Date:   Fri, 18 Aug 2017 15:27:09 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     kafai@...com
Cc:     tom@...bertland.com, shli@...nel.org, netdev@...r.kernel.org
Subject: Re: [PATCH V4 net 0/2] ipv6: fix flowlabel issue for reset packet

From: Martin KaFai Lau <kafai@...com>
Date: Fri, 18 Aug 2017 13:51:36 -0700

> It seems like that middle box specifically drops TCP_RST if it
> does not know anything about this flow.  Since the flowlabel of the TCP_RST
> (sent in TW state) is always different, it always lands to a different middle
> box.  All of these TCP_RST cannot be delivered.

This really is illegal behavior.  The flow label is not a flow _KEY_
by any definition whatsoever.

Flow labels are an optimization, not a determinant for flow matching
particularly for proper TCP state processing.

I'd rather you invest all of this energy getting that vendor to fix
their kit.

Thank you.