From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 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> Date: Thu, 05 Jul 2018 12:36:13 -0500 Message-ID: <874lhdwpo2.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [PATCH] Revert "vfs: Allow userns root to call mknod on owned filesystems." Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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