linux-kernel - Re: [PATCH v2 0/3] initramfs: add support for xattrs in the initial ram disk

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Date:   Tue, 14 May 2019 19:44:42 +0200
From:   Roberto Sassu <roberto.sassu@...wei.com>
To:     Arvind Sankar <nivedita@...m.mit.edu>
CC:     Rob Landley <rob@...dley.net>,
        Arvind Sankar <niveditas98@...il.com>,
        <linux-kernel@...r.kernel.org>, <linux-api@...r.kernel.org>,
        <linux-fsdevel@...r.kernel.org>, <linux-integrity@...r.kernel.org>,
        <initramfs@...r.kernel.org>
Subject: Re: [PATCH v2 0/3] initramfs: add support for xattrs in the initial
 ram disk

On 5/14/2019 5:57 PM, Arvind Sankar wrote:
> On Tue, May 14, 2019 at 11:27:04AM -0400, Arvind Sankar wrote:
>> It's also much easier to change/customize it for the end
>> system's requirements rather than setting the process in stone by
>> putting it inside the kernel.
> 
> As an example, if you allow unverified external initramfs, it seems to
> me that it can try to play games that wouldn't be prevented by the
> in-kernel code: setup /dev in a weird way to try to trick /init, or more
> easily, replace /init by /bin/sh so you get a shell prompt while only
> the initramfs is loaded. It's easy to imagine that a system would want
> to lock itself down to prevent abuses like this.

Yes, these issues should be addressed. But the purpose of this patch set
is simply to set xattrs. And existing protection mechanisms can be
improved later when the basic functionality is there.


> So you might already want an embedded initramfs that can be trusted and
> that can't be overwritten by an external one even outside the
> security.ima stuff.

The same problems exist also the root filesystem. These should be solved
regardless of the filesystem used, for remote attestation and for local
enforcement.

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