linux-kernel - Re: [PATCH 1/1] dm: add message command to disallow device open

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Date:   Wed, 3 Aug 2022 12:30:16 -0400
From:   Mike Snitzer <snitzer@...hat.com>
To:     Daniil Lunev <dlunev@...omium.org>
Cc:     Eric Biggers <ebiggers@...nel.org>,
        Brian Geffon <bgeffon@...gle.com>,
        Mike Snitzer <snitzer@...nel.org>,
        linux-kernel@...r.kernel.org,
        Zdenek Kabelac <zdenek.kabelac@...il.com>, dm-devel@...hat.com,
        Mikulas Patocka <mpatocka@...hat.com>,
        Alasdair Kergon <agk@...hat.com>
Subject: Re: [PATCH 1/1] dm: add message command to disallow device open

On Wed, Aug 03 2022 at 12:29P -0400,
Daniil Lunev <dlunev@...omium.org> wrote:

> > This seems like an access control policy, which the Linux kernel already has a
> > lot of mechanisms for.  Chrome OS already uses SELinux.  Couldn't this be solved
> > by giving the device node an SELinux label that no one has permission to open?
> That would be the ideal solution, but there is a number of challenges
> that prevent
> us enabling enforcement on all SELinux domains unfortunately. While in the long
> run that would be a preferred option, in the short run this doesn't
> seem feasible. I
> would assume the problem of enabling full SELInux enforcement would plague
> any big project that didn't have them enabled from the get going.
> --Daniil

I'm not going to take this patch. It isn't the proper way to handle
preventing use of a DM device. In addition, the patch's header doesn't
speak to a proper review/audit of implications this change would have
on all aspects of a DM device's capabilities. If Chrome OS needs this
as a stop-gap then please carry it as needed.

Regards,
Mike