From: Dave Chinner <david@fromorbit.com>
To: "L.A. Walsh" <xfs@tlinx.org>
Cc: xfs-oss <linux-xfs@vger.kernel.org>
Subject: Re: suggested patch to allow user to access their own file...
Date: Sun, 10 Jan 2021 08:13:47 +1100 [thread overview]
Message-ID: <20210109211347.GL331610@dread.disaster.area> (raw)
In-Reply-To: <5FEB204B.9090109@tlinx.org>
On Tue, Dec 29, 2020 at 04:25:47AM -0800, L.A. Walsh wrote:
> xfs_io checks for CAP_SYS_ADMIN in order to open a
> file_by_inode -- however, if the file one is opening
> is owned by the user performing the call, the call should
> not fail.
No. xfs_open_by_handle() requires root permissions because it
bypasses lots of security checks, such as parent directory
permissions, ACLs and security labels.
e.g. backups under a root-only directory heirarchy should not be
accessible to users because users are not allowed to traverse into
those root:root 0700 backup directories because permissions on the
directory inodes do not allow non-root users to enter them.
Hence ...
> (i.e. it opens the user's own file).
... the user doesn't actually own that file, even though it has
their own UID in it...
> It gets rid of some unnecessary error messages if you
> run xfs_restore to restore one of your own files.
That's not really a user case xfs_restore is intended to support.
It's an admin tool to be run by admins, not end users....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
prev parent reply other threads:[~2021-01-09 21:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 12:25 suggested patch to allow user to access their own file L.A. Walsh
2021-01-04 17:08 ` Brian Foster
2021-01-04 18:44 ` Darrick J. Wong
[not found] ` <5FF3796E.5050409@tlinx.org>
2021-01-04 23:15 ` Darrick J. Wong
2021-01-05 0:03 ` L A Walsh
2021-01-09 21:13 ` Dave Chinner [this message]
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