netdev - Re: [PATCH net-next] Sysctl parameter to disable TCP RST packet to unknown socket

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Date:   Wed, 2 Sep 2020 23:17:13 +0200
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Mihail Milev <mmilev_ml@...oud.com>, davem@...emloft.net,
        kuba@...nel.org, edumazet@...gle.com
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next] Sysctl parameter to disable TCP RST packet to
 unknown socket

On 9/2/20 12:56 PM, Mihail Milev wrote:
> What?
> 
> Create a new sysctl parameter called tcp_disable_rst_unkn_socket,
> which by default is set to 0 - "disabled". When this parameter is
> set to 1 - "enabled", it suppresses sending a TCP RST packet as a
> response to received TCP packets destined for a socket, which is
> unknown to the kernel.
> 

Well, I am not thrilled by this patch...

1) This seems hacky to only focus on RST packets, while it seems clear you
want to be able to use a user-land TCP stack.

2) No ipv6 support in your patch, this is unfortunate.

3) I do not see how you prevent another program using kernel stack conflicting
with TCP listeners/flows of your user space TCP.