From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f198.google.com (mail-pl1-f198.google.com [209.85.214.198]) by kanga.kvack.org (Postfix) with ESMTP id 9AE056B027D for ; Tue, 9 Oct 2018 21:02:59 -0400 (EDT) Received: by mail-pl1-f198.google.com with SMTP id 43-v6so2730189ple.19 for ; Tue, 09 Oct 2018 18:02:59 -0700 (PDT) Received: from ipmail06.adl6.internode.on.net (ipmail06.adl6.internode.on.net. [150.101.137.145]) by mx.google.com with ESMTP id i64-v6si23475531pli.56.2018.10.09.18.02.57 for ; Tue, 09 Oct 2018 18:02:58 -0700 (PDT) Date: Wed, 10 Oct 2018 12:02:08 +1100 From: Dave Chinner Subject: Re: [PATCH v2 00/25] fs: fixes for serious clone/dedupe problems Message-ID: <20181010010208.GI6311@dastard> References: <153913023835.32295.13962696655740190941.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <153913023835.32295.13962696655740190941.stgit@magnolia> Sender: owner-linux-mm@kvack.org List-ID: To: "Darrick J. Wong" Cc: sandeen@redhat.com, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, ocfs2-devel@oss.oracle.com On Tue, Oct 09, 2018 at 05:10:38PM -0700, Darrick J. Wong wrote: > Hi all, > > Dave, Eric, and I have been chasing a stale data exposure bug in the XFS > reflink implementation, and tracked it down to reflink forgetting to do > some of the file-extending activities that must happen for regular > writes. > > We then started auditing the clone, dedupe, and copyfile code and > realized that from a file contents perspective, clonerange isn't any > different from a regular file write. Unfortunately, we also noticed > that *unlike* a regular write, clonerange skips a ton of overflow > checks, such as validating the ranges against s_maxbytes, MAX_NON_LFS, > and RLIMIT_FSIZE. We also observed that cloning into a file did not > strip security privileges (suid, capabilities) like a regular write > would. I also noticed that xfs and ocfs2 need to dump the page cache > before remapping blocks, not after. > > In fixing the range checking problems I also realized that both dedupe > and copyfile tell userspace how much of the requested operation was > acted upon. Since the range validation can shorten a clone request (or > we can ENOSPC midway through), we might as well plumb the short > operation reporting back through the VFS indirection code to userspace. > > So, here's the whole giant pile of patches[1] that fix all the problems. > The patch "generic: test reflink side effects" recently sent to fstests > exercises the fixes in this series. Tests are in [2]. Can you rebase this on the for-next branch on the xfs tree which already contains some of the initial fixes in the series and a couple of other reflink/dedupe data corruption fixes? I'm planning on pushing them to Greg tomorrow, so you'll have to do this soon anyway.... Cheers, Dave. -- Dave Chinner david@fromorbit.com