From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. Bruce Fields" Subject: Re: [Lsf-pc] [LSF/MM ATTEND] Richacls Date: Tue, 13 Jan 2015 12:40:29 -0500 Message-ID: <20150113174029.GA4156@fieldses.org> References: <1626890778.1513173.1421087867777.JavaMail.zimbra@redhat.com> <1137663039.1544780.1421096804147.JavaMail.zimbra@redhat.com> <20150112223016.GB1940@fieldses.org> <20150113101435.GA28924@quack.suse.cz> <54B534C3.3090608@redhat.com> <20150113164802.GA5830@samba2> <54B5548E.5030808@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jeremy Allison , Jan Kara , linux-fsdevel@vger.kernel.org, lsf-pc@lists.linux-foundation.org To: Andreas Gruenbacher Return-path: Received: from fieldses.org ([174.143.236.118]:50081 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751749AbbAMRkf (ORCPT ); Tue, 13 Jan 2015 12:40:35 -0500 Content-Disposition: inline In-Reply-To: <54B5548E.5030808@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Jan 13, 2015 at 06:23:26PM +0100, Andreas Gruenbacher wrote: > On 01/13/2015 05:48 PM, Jeremy Allison wrote: > >My understanding of Christoph's objection (although I'm sure > >he can chime in himself :-) was that he wanted to see POSIX > >ACLs reworked as a mapping on top of RichACLs, so that ultimately > >RichACLs would be the only on-disk format of the EA. > > > >I think that is doable, as I think any POSIX ACL can be represented > >as an underlying RichACL, just not the reverse. > > On of the differences is that permissions in POSIX ACLs do > accumulate, while in NFSv4 and CIFS ACLs, and therefore also > richacls, they do not. So the two models are really not > interchangeable, however annoying that may be. > > For example, with the following POSIX ACL, a non-root process in > group 5001 and 5002 would not be allowed to open f with O_RDWR, only > with O_RDONLY *or* O_WRONLY. > > # file: f > # owner: root > # group: root > user::rw- > group::rw- > group:5001:r-- > group:5002:-w- > mask::rw- > other::--- > > In all the other ACL models, the process would be allowed to open f > with O_RDWR. If we modified the behavior to permit O_RDWR in this case, would that cause anyone a problem? > The rationale for this behavior in POSIX ACLs was / is consistency > with how the traditional POSIX file permission model works -- > determine which of the (three) sets of permissions applies to a > process, then check only that set. The "consistency" leads to kind of weird corner case here. --b.