From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2120.oracle.com ([156.151.31.85]:47130 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725987AbeLCTLj (ORCPT ); Mon, 3 Dec 2018 14:11:39 -0500 Date: Mon, 3 Dec 2018 11:11:30 -0800 From: "Darrick J. Wong" Subject: Re: [PATCH 08/11] vfs: push EXDEV check down into ->remap_file_range Message-ID: <20181203191130.GD24487@magnolia> References: <20181203083416.28978-1-david@fromorbit.com> <20181203083416.28978-9-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-unionfs-owner@vger.kernel.org To: Amir Goldstein Cc: Dave Chinner , linux-fsdevel , linux-xfs , Olga Kornievskaia , Linux NFS Mailing List , overlayfs , ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org List-ID: On Mon, Dec 03, 2018 at 01:04:07PM +0200, Amir Goldstein wrote: > On Mon, Dec 3, 2018 at 10:34 AM Dave Chinner wrote: > > > > From: Dave Chinner > > > > before we can enable cross-device copies into copy_file_range(), > > we have to ensure that ->remap_file_range() implemenations will > > correctly reject attempts to do cross filesystem clones. Currently > > But you only fixed remap_file_range() implemenations of xfs and ocfs2... > > > these checks are done above calls to ->remap_file_range(), but > > we need to drive them inwards so that we get EXDEV protection for all > > callers of ->remap_file_range(). > > > > Signed-off-by: Dave Chinner > > --- > > fs/read_write.c | 21 +++++++++++++-------- > > 1 file changed, 13 insertions(+), 8 deletions(-) > > > > diff --git a/fs/read_write.c b/fs/read_write.c > > index 3288db1d5f21..174cf92eea1d 100644 > > --- a/fs/read_write.c > > +++ b/fs/read_write.c > > @@ -1909,6 +1909,19 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in, > > bool same_inode = (inode_in == inode_out); > > int ret; > > > > + /* > > + * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on > > + * the same mount. Practically, they only need to be on the same file > > + * system. We check this here rather than at the ioctl layers because > > + * this is effectively a limitation of the fielsystem implementations, > > + * not so much the API itself. Further, ->remap_file_range() can be > > + * called from syscalls that don't have cross device copy restrictions > > + * (such as copy_file_range()) and so we need to catch them before we > > + * do any damage. > > + */ > > + if (inode_in->i_sb != inode_out->i_sb) > > + return -EXDEV; > > + > > /* Don't touch certain kinds of inodes */ > > if (IS_IMMUTABLE(inode_out)) > > return -EPERM; > > @@ -2013,14 +2026,6 @@ loff_t do_clone_file_range(struct file *file_in, loff_t pos_in, > > if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode)) > > return -EINVAL; > > > > - /* > > - * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on > > - * the same mount. Practically, they only need to be on the same file > > - * system. > > - */ > > - if (inode_in->i_sb != inode_out->i_sb) > > - return -EXDEV; > > - > I think this is sort of backwards -- the checks should stay in do_clone_file_range, and vfs_copy_file_range should be calling that instead of directly calling ->remap_range(): vfs_copy_file_range() { file_start_write(...); ret = do_clone_file_range(...); if (ret > 0) return ret; ret = do_copy_file_range(...); file_end_write(...); return ret; } > That leaves {nfs42,cifs,btrfs}_remap_file_range() exposed to passing > files not of their own fs type let alone same sb when do_clone_file_range() > is called from ovl_copy_up_data(). ...and then I think this problem goes away. --D > Thanks, > Amir.