From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2130.oracle.com ([156.151.31.86]:51000 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750818AbeEKX6a (ORCPT ); Fri, 11 May 2018 19:58:30 -0400 Date: Fri, 11 May 2018 16:58:22 -0700 From: "Darrick J. Wong" To: Mark Fasheh Cc: linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH 1/2] vfs: allow dedupe of user owned read-only files Message-ID: <20180511235822.GF9510@magnolia> References: <20180511192651.21324-1-mfasheh@suse.de> <20180511192651.21324-2-mfasheh@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180511192651.21324-2-mfasheh@suse.de> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, May 11, 2018 at 12:26:50PM -0700, Mark Fasheh wrote: > The permission check in vfs_dedupe_file_range() is too coarse - We > only allow dedupe of the destination file if the user is root, or > they have the file open for write. > > This effectively limits a non-root user from deduping their own > read-only files. As file data during a dedupe does not change, > this is unexpected behavior and this has caused a number of issue > reports. For an example, see: > > https://github.com/markfasheh/duperemove/issues/129 > > So change the check so we allow dedupe on the target if: > > - the root or admin is asking for it > - the owner of the file is asking for the dedupe > - the process has write access > > Signed-off-by: Mark Fasheh Sounds fine I guess.... Acked-by: Darrick J. Wong --D > --- > fs/read_write.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/read_write.c b/fs/read_write.c > index c4eabbfc90df..77986a2e2a3b 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -2036,7 +2036,8 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same) > > if (info->reserved) { > info->status = -EINVAL; > - } else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) { > + } else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE) || > + uid_eq(current_fsuid(), dst->i_uid))) { > info->status = -EINVAL; > } else if (file->f_path.mnt != dst_file->f_path.mnt) { > info->status = -EXDEV; > -- > 2.15.1 >