From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:34066 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2390670AbfFKCv3 (ORCPT ); Mon, 10 Jun 2019 22:51:29 -0400 Date: Mon, 10 Jun 2019 22:51:08 -0400 From: "Theodore Ts'o" Subject: Re: [PATCH] vfs: allow copy_file_range from a swapfile Message-ID: <20190611025108.GB2774@mit.edu> References: <20190610172606.4119-1-amir73il@gmail.com> <20190611011612.GQ1871505@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190611011612.GQ1871505@magnolia> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J. Wong" Cc: Amir Goldstein , Dave Chinner , Christoph Hellwig , linux-xfs@vger.kernel.org, Olga Kornievskaia , Luis Henriques , Al Viro , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org On Mon, Jun 10, 2019 at 06:16:12PM -0700, Darrick J. Wong wrote: > On Mon, Jun 10, 2019 at 08:26:06PM +0300, Amir Goldstein wrote: > > read(2) is allowed from a swapfile, so copy_file_range(2) should > > be allowed as well. > > > > Reported-by: Theodore Ts'o > > Fixes: 96e6e8f4a68d ("vfs: add missing checks to copy_file_range") > > Signed-off-by: Amir Goldstein > > --- > > > > Darrick, > > > > This fixes the generic/554 issue reported by Ted. > > Frankly I think we should go the other way -- non-root doesn't get to > copy from or read from swap files. The issue is that without this patch, *root* doesn't get to copy from swap files. Non-root shouldn't have access via Unix permissions. We could add a special case if we don't trust system administrators to be able to set the Unix permissions correctly, I suppose, but we don't do that for block devices when they are mounted.... - Ted