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        Mon, 13 Nov 2017 20:11:19 -0000
Subject: Re: [RFC PATCH v2] fw_lockdown: new micro LSM module to prevent
 loading unsigned firmware
From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: David Howells <dhowells@redhat.com>,
        linux-integrity <linux-integrity@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Kyle McMartin <kyle@kernel.org>,
        Ben Hutchings <ben@decadent.org.uk>,
        Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>,
        "AKASHI, Takahiro" <takahiro.akashi@linaro.org>
Date: Mon, 13 Nov 2017 15:11:12 -0500
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On Mon, 2017-11-13 at 20:51 +0100, Luis R. Rodriguez wrote:
> On Mon, Nov 13, 2017 at 02:36:47PM -0500, Mimi Zohar wrote:

> > Huh, I kind of lost you here.  What does "it" refer to in the above
> > sentence?  IMA is in the kernel.  So, who does what checks in
> > userspace?
> 
> Sorry I thought some checks were done in userspace, given that is clarified,
> what I meant is that say a device driver has a signing specification written
> out in the driver, should/can IMA use that on the LSM to verify the detached
> signature file for the firmware?

IMA-appraisal currently supports file signatures as extended
attributes.  Thiago Bauermann posted patches for including appended
signature support to IMA-appraisal.  If someone is interested in
adding detached signature support, they're welcome to do so.

> If it can be all done in kernel, it has me wondering if perhaps one option for
> IMA might be to do only vetting for these types of checks, where the info and
> description to appraise files is all in-kernel. IMA would not be required
> for other files.

We probably can defer this discussion until it is applicable.

Mimi