From: Al Viro <viro@ZenIV.linux.org.uk>
To: Christoph Hellwig <hch@lst.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
linux-xfs@vger.kernel.org, Dave Chinner <david@fromorbit.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: xfs: commit 6552321831dc "xfs: remove i_iolock and use i_rwsem in the VFS inode instead" change causes hang
Date: Sun, 8 Jan 2017 19:26:34 +0000 [thread overview]
Message-ID: <20170108192634.GM1555@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170108190955.GA1489@lst.de>
On Sun, Jan 08, 2017 at 08:09:55PM +0100, Christoph Hellwig wrote:
> No. We need an ->ima_measure file_operation, guts of process_measurement
> turned into a library function that the FS can call after taking fs-specific
> locks. And maybe also a small wrapper around it that takes ilock and
> can be used directly for file systems not needing special locking.
Incidentally, it had been literally years since the problems with their
pathname handling had been brought up and we *still* have got no answer.
In the current tree, ima_d_path() is quite capable of returning
path->dentry->d_name.name. Which gets used by subsequent code,
even though there is no warranty whatsoever that it won't be
pointing to freed memory by the time the caller of ima_d_path()
gets it.
Could IMA folks be bothered to explain how the hell is that supposed to
work? Note that the race window is *not* narrow - it includes reading the
file contents, for fuck sake! A plenty of time for the file to be
renamed, and if the name had been long enough to be stored separately,
for the original to be freed/reused/whatnot.
Better yet, in ima_collect_measurement() they have another user of
->d_name.name, with all the same issues.
next prev parent reply other threads:[~2017-01-08 19:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-08 14:48 xfs: commit 6552321831dc "xfs: remove i_iolock and use i_rwsem in the VFS inode instead" change causes hang Mimi Zohar
2017-01-08 14:52 ` Christoph Hellwig
2017-01-08 15:03 ` Mimi Zohar
2017-01-08 15:14 ` Christoph Hellwig
2017-01-08 15:31 ` Mimi Zohar
2017-01-08 15:37 ` Christoph Hellwig
2017-01-08 16:38 ` Mimi Zohar
2017-01-08 16:43 ` Christoph Hellwig
2017-01-08 17:59 ` James Bottomley
2017-01-08 18:18 ` Christoph Hellwig
2017-01-08 18:57 ` James Bottomley
2017-01-08 19:09 ` Christoph Hellwig
2017-01-08 19:26 ` Al Viro [this message]
2017-01-08 20:10 ` Mimi Zohar
2017-01-08 19:39 ` Mimi Zohar
2017-01-09 19:44 ` Jeff Layton
2017-01-10 2:54 ` Mimi Zohar
2017-01-10 16:22 ` Jeff Layton
2017-01-08 19:16 ` Mimi Zohar
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