From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2D3953FD4 for ; Tue, 26 Mar 2024 23:55:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711497356; cv=none; b=KdKrL65EDfuSmqRsEBiBvTSAfUEvDZc51iq7Ew61HVyUxDw18sGYnemo/hYrGkXOAy/st2kn/l7j7RC1R4Mgw3CeIeM9e272Q/8WUwV8PHwavdmVtGiooMRNBXpCWcx0Dp+t5sKRYlSnAVJTre/cwhIHFyHPUPxqirYHyfdgXEA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711497356; c=relaxed/simple; bh=nTsjuWRBzs6ll6Ln6p1WmIeya74BF+wioNG3VxeygSM=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XFoAccZevn8vwF7CzR2jVxZuywoJ2yfHDzi3jW43RlhFiPXcjEYSBvcxF+C39XrQAkm2KeIpD+9vB31Rc1HWy2QmoIkflK1Tw94FZ1Dc3FkDpxLDe3CMUj478fiu8DVXOPia3rzeDx/kd4dRdtB28572zfDe8P4J3/s8M9ft2Lo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tbr52LBF; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tbr52LBF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97CB2C433C7; Tue, 26 Mar 2024 23:55:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711497355; bh=nTsjuWRBzs6ll6Ln6p1WmIeya74BF+wioNG3VxeygSM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=tbr52LBF3VFSRGzP/8QnAlFF4dZwJvSJxKJlVyq5uaw8OzVvMRgkS6w6IQfTK3ncj p2ktA1Riqzo0COWMM2c+KlahS0sHNr6E2YEJSwJ8ZTwicUDqoevFfUdvNbUuXbINdM nKlJHHqn9j3+p2bvtr8MS6jVmNiu60hydBq1UpIOU0q493IFu3+ykMd6PQueCEW49e fFbzwacldKbh48GGCGnT7GD1QnkcfZT6UKfBqpkYvN+emggiCPypKAwmiHyE7WyQdd Q+E6jgcO7AWdXVjBpHaCJs2TocLOYTozlwxl00gMBwGNotd1ThwdEPVxdlXhEufP89 Lhjd5McpdtvxQ== Date: Tue, 26 Mar 2024 16:55:54 -0700 From: Jakub Kicinski To: Neal Cardwell Cc: Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org Subject: Re: ICMP_PARAMETERPROB and ICMP_TIME_EXCEEDED during connect Message-ID: <20240326165554.541551c3@kernel.org> In-Reply-To: References: <20240326133412.47cf6d99@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tue, 26 Mar 2024 23:03:26 +0100 Neal Cardwell wrote: > On Tue, Mar 26, 2024 at 9:34=E2=80=AFPM Jakub Kicinski = wrote: > > > > Hi! > > > > I got a report from a user surprised/displeased that ICMP_TIME_EXCEEDED > > breaks connect(), while TCP RFCs say it shouldn't. Even pointing a > > finger at Linux, RFC5461: > > > > A number of TCP implementations have modified their reaction to all > > ICMP soft errors and treat them as hard errors when they are received > > for connections in the SYN-SENT or SYN-RECEIVED states. For example, > > this workaround has been implemented in the Linux kernel since > > version 2.0.0 (released in 1996) [Linux]. However, it should be > > noted that this change violates section 4.2.3.9 of [RFC1122], which > > states that these ICMP error messages indicate soft error conditions > > and that, therefore, TCP MUST NOT abort the corresponding connection. > > > > Is there any reason we continue with this behavior or is it just that > > nobody ever sent a patch? =20 >=20 > Back in November of 2023 Eric did merge a patch to bring the > processing in line with section 4.2.3.9 of [RFC1122]: >=20 > 0a8de364ff7a tcp: no longer abort SYN_SENT when receiving some ICMP >=20 > However, the fixed behavior did not meet some expectations of Vagrant > (see the netdev thread "Bug report connect to VM with Vagrant"), so > for now it got reverted: >=20 > b59db45d7eba tcp: Revert no longer abort SYN_SENT when receiving some ICMP >=20 > I think the hope was to root-cause the Vagrant issue, fix Vagrant's > assumptions, then resubmit Eric's commit. Eric mentioned on Jan 8, > 2024: "We will submit the patch again for 6.9, once we get to the root > cause." But I don't think anyone has had time to do that yet. Ah. Thank you!!