netdev - Re: [PATCH net-next 1/2] tcp: conditionally call ip_icmp_error() from tcp_v4

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Message-ID: <CANn89i+SB1Kg=9DY8aTRWu0YKM7+RYdH0sUnVW==TVvLmrTiuw@mail.gmail.com>
Date: Thu, 18 Apr 2024 20:09:38 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: David Ahern <dsahern@...nel.org>
Cc: Paolo Abeni <pabeni@...hat.com>, "David S . Miller" <davem@...emloft.net>, 
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org, 
	Neal Cardwell <ncardwell@...gle.com>, Dragos Tatulea <dtatulea@...dia.com>, eric.dumazet@...il.com, 
	Maciej Żenczykowski <maze@...gle.com>, 
	Willem de Bruijn <willemb@...gle.com>, Shachar Kagan <skagan@...dia.com>
Subject: Re: [PATCH net-next 1/2] tcp: conditionally call ip_icmp_error() from tcp_v4_err()

On Thu, Apr 18, 2024 at 8:02 PM David Ahern <dsahern@...nel.org> wrote:
>
> On 4/18/24 11:47 AM, Eric Dumazet wrote:
> > I think the userspace program relied on a bug added in linux in 2020
>
> which test - when was it added? nettest.c and the fcnal script were
> merged in 2019.

The test relies on connect() being aborted by EHOSTUNREACH

This is in complete violation with RFC

Even our own net.ipv4/icmp.c states this clearly.

 RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED
MUST be considered 'transient errs'.

Your program wants to use RECVERR instead of depending on a bug that
we are trying very hard to solve.