From: "Darrick J. Wong" <djwong@kernel.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/1] xfs: online repair of symbolic links
Date: Wed, 28 Feb 2024 10:37:40 -0800 [thread overview]
Message-ID: <20240228183740.GO1927156@frogsfrogsfrogs> (raw)
In-Reply-To: <Zd9sqALoZMOvHm8P@infradead.org>
On Wed, Feb 28, 2024 at 09:26:00AM -0800, Christoph Hellwig wrote:
> On Mon, Feb 26, 2024 at 06:32:51PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> >
> > If a symbolic link target looks bad, try to sift through the rubble to
> > find as much of the target buffer that we can, and stage a new target
> > (short or remote format as needed) in a temporary file and use the
> > atomic extent swapping mechanism to commit the results.
>
> So this basically injects new link paths, which looks really dangerous
> to me, as it creates odd attack vectors. I'd much prefer to not
> "repair" the path, but mark the link bad so that any access but unlike
> returns -EIO.
Ah, you're worried about a symlink foo -> bar getting corrupted and
being repaired into foo -> b, especially if there's actually a "b".
Going back to [1] from last year, I finally /did/ find a magic symlink
target that actually does trip EIO. That solution is to set the buffer
contents to a string that is so long that it exceeds NAME_MAX.
Userspace can readlink this string, but it will never resolve anywhere
in the directory tree.
What if this unconditionally set the link target to DUMMY_TARGET instead
of salvaging partial targets?
--D
[1] https://lore.kernel.org/linux-xfs/20231213013644.GC361584@frogsfrogsfrogs/
next prev parent reply other threads:[~2024-02-28 18:37 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-27 2:18 [PATCHSET v29.['hch@lst.de'] 11/13] xfs: online repair of symbolic links Darrick J. Wong
2024-02-27 2:23 ` Darrick J. Wong
2024-02-27 2:32 ` [PATCH 1/1] " Darrick J. Wong
2024-02-28 17:26 ` Christoph Hellwig
2024-02-28 18:37 ` Darrick J. Wong [this message]
2024-02-28 18:53 ` Christoph Hellwig
2024-02-28 20:52 ` Darrick J. Wong
2024-02-28 22:10 ` Christoph Hellwig
2024-02-28 23:46 ` Darrick J. Wong
2024-02-29 13:25 ` Christoph Hellwig
2024-02-29 17:16 ` Darrick J. Wong
2024-02-29 19:42 ` Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2024-03-27 1:49 [PATCHSET v30.1 12/15] " Darrick J. Wong
2024-03-27 2:05 ` [PATCH 1/1] " Darrick J. Wong
2024-03-27 16:53 ` Christoph Hellwig
2024-03-29 20:44 ` Darrick J. Wong
2024-03-29 20:58 ` Darrick J. Wong
2023-12-31 19:45 [PATCHSET v29.0 23/40] xfsprogs: " Darrick J. Wong
2023-12-31 22:35 ` [PATCH 1/1] xfs: " Darrick J. Wong
2023-12-31 19:31 [PATCHSET v29.0 24/28] " Darrick J. Wong
2023-12-31 20:39 ` [PATCH 1/1] " Darrick J. Wong
2023-05-26 0:36 [PATCHSET v25.0 0/1] " Darrick J. Wong
2023-05-26 1:36 ` [PATCH 1/1] " Darrick J. Wong
2022-12-30 22:14 [PATCHSET v24.0 0/1] " Darrick J. Wong
2022-12-30 22:14 ` [PATCH 1/1] " Darrick J. Wong
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