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From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	Olga Kornievskaia <olga.kornievskaia@gmail.com>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	overlayfs <linux-unionfs@vger.kernel.org>,
	ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org
Subject: Re: [PATCH 08/11] vfs: push EXDEV check down into ->remap_file_range
Date: Mon, 3 Dec 2018 11:11:30 -0800
Message-ID: <20181203191130.GD24487@magnolia> (raw)
In-Reply-To: <CAOQ4uxgwZLsO1yV37_CHaZ-O+-+-OggSP9g6m9YE57kLPc5yDw@mail.gmail.com>

On Mon, Dec 03, 2018 at 01:04:07PM +0200, Amir Goldstein wrote:
> On Mon, Dec 3, 2018 at 10:34 AM Dave Chinner <david@fromorbit.com> wrote:
> >
> > From: Dave Chinner <dchinner@redhat.com>
> >
> > 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 <dchinner@redhat.com>
> > ---
> >  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.

  reply index

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-03  8:34 [PATCH 0/11] fs: fixes for major copy_file_range() issues Dave Chinner
2018-12-03  8:34 ` [PATCH 01/11] vfs: copy_file_range source range over EOF should fail Dave Chinner
2018-12-03 12:46   ` Amir Goldstein
2018-12-04 15:13     ` Christoph Hellwig
2018-12-04 21:29       ` Dave Chinner
2018-12-04 21:47         ` Olga Kornievskaia
2018-12-04 22:31           ` Dave Chinner
2018-12-05 16:51             ` bfields
2019-05-20  9:10             ` Amir Goldstein
2019-05-20 13:12               ` Olga Kornievskaia
2019-05-20 13:36                 ` Amir Goldstein
2019-05-20 13:58                   ` Olga Kornievskaia
2019-05-20 14:02                     ` Amir Goldstein
2018-12-05 14:12         ` Christoph Hellwig
2018-12-05 21:08           ` Dave Chinner
2018-12-05 21:30             ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 02/11] vfs: introduce generic_copy_file_range() Dave Chinner
2018-12-03 10:03   ` Amir Goldstein
2018-12-03 23:00     ` Dave Chinner
2018-12-04 15:14   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 03/11] vfs: no fallback for ->copy_file_range Dave Chinner
2018-12-03 10:22   ` Amir Goldstein
2018-12-03 23:02     ` Dave Chinner
2018-12-06  4:16       ` Amir Goldstein
2018-12-06 21:30         ` Dave Chinner
2018-12-07  5:38           ` Amir Goldstein
2018-12-03 18:23   ` Anna Schumaker
2018-12-04 15:16   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 04/11] vfs: add missing checks to copy_file_range Dave Chinner
2018-12-03 12:42   ` Amir Goldstein
2018-12-03 19:04   ` Darrick J. Wong
2018-12-03 21:33   ` Olga Kornievskaia
2018-12-03 23:04     ` Dave Chinner
2018-12-04 15:18   ` Christoph Hellwig
2018-12-12 11:31   ` Luis Henriques
2018-12-12 16:42     ` Darrick J. Wong
2018-12-12 18:55     ` Olga Kornievskaia
2018-12-12 19:42       ` Matthew Wilcox
2018-12-12 20:22         ` Olga Kornievskaia
2018-12-13 10:29           ` Luis Henriques
2018-12-03  8:34 ` [PATCH 05/11] vfs: use inode_permission in copy_file_range() Dave Chinner
2018-12-03 12:47   ` Amir Goldstein
2018-12-03 18:18   ` Darrick J. Wong
2018-12-03 23:55     ` Dave Chinner
2018-12-05 17:28       ` bfields
2018-12-03 18:53   ` Eric Biggers
2018-12-04 15:19   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 06/11] vfs: copy_file_range needs to strip setuid bits Dave Chinner
2018-12-03 12:51   ` Amir Goldstein
2018-12-04 15:21   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 07/11] vfs: copy_file_range should update file timestamps Dave Chinner
2018-12-03 10:47   ` Amir Goldstein
2018-12-03 17:33     ` Olga Kornievskaia
2018-12-03 18:22       ` Darrick J. Wong
2018-12-03 23:19     ` Dave Chinner
2018-12-04 15:24   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 08/11] vfs: push EXDEV check down into ->remap_file_range Dave Chinner
2018-12-03 11:04   ` Amir Goldstein
2018-12-03 19:11     ` Darrick J. Wong [this message]
2018-12-03 23:37       ` Dave Chinner
2018-12-03 23:58         ` Darrick J. Wong
2018-12-04  9:17           ` Amir Goldstein
2018-12-03 23:34     ` Dave Chinner
2018-12-03 18:24   ` Darrick J. Wong
2018-12-04  8:18   ` Olga Kornievskaia
2018-12-03  8:34 ` [PATCH 09/11] vfs: push copy_file_ranges -EXDEV checks down Dave Chinner
2018-12-03 12:36   ` Amir Goldstein
2018-12-03 17:58   ` Olga Kornievskaia
2018-12-03 18:53   ` Anna Schumaker
2018-12-03 19:27     ` Olga Kornievskaia
2018-12-03 23:40     ` Dave Chinner
2018-12-04 15:43   ` Christoph Hellwig
2018-12-04 22:18     ` Dave Chinner
2018-12-04 23:33       ` Olga Kornievskaia
2018-12-05 14:09       ` Christoph Hellwig
2018-12-05 17:01         ` Olga Kornievskaia
2018-12-03  8:34 ` [PATCH 10/11] vfs: allow generic_copy_file_range to copy across devices Dave Chinner
2018-12-03 12:54   ` Amir Goldstein
2018-12-03  8:34 ` [PATCH 11/11] ovl: allow cross-device copy_file_range calls Dave Chinner
2018-12-03 12:55   ` Amir Goldstein
2018-12-03  8:39 ` [PATCH 12/11] man-pages: copy_file_range updates Dave Chinner
2018-12-03 13:05   ` Amir Goldstein
2019-05-21  5:52   ` Amir Goldstein

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