From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH rfc 1/4] net-timestamp: pull headers for SOCK_STREAM Date: Tue, 25 Nov 2014 14:54:34 -0500 (EST) Message-ID: <20141125.145434.1790615963499624322.davem@davemloft.net> References: <1416938286-14147-2-git-send-email-willemb@google.com> <20141125.134240.861582393401487675.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, luto@amacapital.net, richardcochran@gmail.com To: willemb@google.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:37807 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750860AbaKYTyh (ORCPT ); Tue, 25 Nov 2014 14:54:37 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Willem de Bruijn Date: Tue, 25 Nov 2014 14:52:00 -0500 > On Tue, Nov 25, 2014 at 1:42 PM, David Miller wrote: >> From: Willem de Bruijn >> Date: Tue, 25 Nov 2014 12:58:03 -0500 >> >> What's the harm in exposing the headers? Either it's harmful, and >> therefore doing so for UDP is bad too, or it's harmless and > > Headers may expose information not available otherwise. I don't > immediately see critical problems, but that does not mean that they > might not lurk there. > > We so far avoid exposing the sequence number, though keeping it hidden > is more about third parties. More in general, unprivileged processes > may start requesting timestamps only to learn tcp state that they > should either get from tcpinfo or cannot currently get at all, likely > for good reason. A far-fetched example is identifying admin iptables > tos mangling rules by reading the tos bits at the driver layer. At least > on my machine, iptables -L is privileged. > >> we should probably leave it alone to not risk breaking anyone. > > That's fair. I sent it for rfc first for that reason. I won't resubmit > unless more serious concerns are raised. I just worry about the potential breakage. Your concerns are valid... I honestly don't know what we should do here. Both choices have merit.