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Subject: Re: [PATCH] ima: define new policy condition based on the
 filesystem name
From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-integrity <linux-integrity@vger.kernel.org>,
        linux-security-module <linux-security-module@vger.kernel.org>,
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        Dongsu Park <dongsu@kinvolk.io>,
        Alban Crequy <alban@kinvolk.io>,
        Seth Forshee <seth.forshee@canonical.com>
Date: Mon, 15 Jan 2018 11:40:07 -0500
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On Mon, 2018-01-15 at 08:27 -0800, Christoph Hellwig wrote:
> On Mon, Jan 15, 2018 at 11:20:36AM -0500, Mimi Zohar wrote:
> > Some filesystems do not export the filesystem's magic number, as it is
> > considered internal, private data.  In other cases, the policy rule
> > needs to identify a specifically mounted filesystem (eg. rootfs).
> 
> No, it doesn't.  Policies based on a file system type are complete and
> utterly bogus.   rootfs should not be treated any different from other
> file systems.

rootfs IS different than other filesystems, as other filesystems
uniquely identify the underlying filesystem type.  rootfs can be a
ramfs or tmpfs filesystem.  Only tmpfs supports xattrs.

Mimi