From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D819C6778A for ; Thu, 5 Jul 2018 17:36:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 62F2C240C6 for ; Thu, 5 Jul 2018 17:36:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 62F2C240C6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xmission.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753859AbeGERg2 (ORCPT ); Thu, 5 Jul 2018 13:36:28 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:59174 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753428AbeGERg0 (ORCPT ); Thu, 5 Jul 2018 13:36:26 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out01.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1fb8B7-0004Kh-Cn; Thu, 05 Jul 2018 11:36:25 -0600 Received: from [97.119.167.31] (helo=x220.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1fb8B6-0004mS-Rb; Thu, 05 Jul 2018 11:36:25 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Christian Brauner Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, seth.forshee@canonical.com, serge@hallyn.com, containers@lists.linux-foundation.org In-Reply-To: <87lgapwrw4.fsf@xmission.com> (Eric W. Biederman's message of "Thu, 05 Jul 2018 11:48:11 -0500") References: <20180705155120.22102-1-christian@brauner.io> <87lgapwrw4.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) Date: Thu, 05 Jul 2018 12:36:13 -0500 Message-ID: <874lhdwpo2.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1fb8B6-0004mS-Rb;;;mid=<874lhdwpo2.fsf@xmission.com>;;;hst=in02.mta.xmission.com;;;ip=97.119.167.31;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+AaQRG8OK9zxbnR09NTH+Phy7lJS2DbSg= X-SA-Exim-Connect-IP: 97.119.167.31 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH] Revert "vfs: Allow userns root to call mknod on owned filesystems." X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ebiederm@xmission.com (Eric W. Biederman) writes: > Nacked-by: "Eric W. Biederman" > > Your description is usesless. > > It needs to detail exactly what breaks, what regressions and why. > All I see below is hand waving. > > We need to know why this does not work so someone does not come in and try > this again. Or so that someone can fix this and then try again. > > You do not include that kind of information in your commit log. > > Calling mknod to create device nodes can not be widespread. There are > not that many privileged processes and calling mknod outside of being > a specialed process like udev is broken. > > Therefore I refute your assertion that this is a widespread issue. > > > I expect somewhere there is a reasonable argument for reverting this > change on the basis that it causes a regression. You have not made it. > > Until that time I am going to oppose this revert because your > justfication for the revert is lacking. > > > It has never been the case that mknod on a device node will guarantee > that you even can open the device node. The applications that regress > are broken. It doesn't mean we shouldn't be bug compatible, but we darn > well should document very clearly the bugs we are being bug compatible > with. > Further from what I have seen of this issue, there is a compelling case that what the applications that are broken what what is enabled by allowing mknod to succeed. So we absolutely need a good description of what is going on, because at best a revert to fix today's breaking is temporary until userspace gets their bugs fixed. Eric