Re: Trusted kernel patchset for Secure Boot lockdown

From: Josh Boyer <jwboyer@fedoraproject.org>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Matthew Garrett <matthew.garrett@nebula.com>,
	"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
	Kees Cook <keescook@chromium.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
	James Morris <jmorris@namei.org>,
	linux-security-module <linux-security-module@vger.kernel.org>
Subject: Re: Trusted kernel patchset for Secure Boot lockdown
Date: Fri, 28 Feb 2014 07:50:44 -0500	[thread overview]
Message-ID: <CA+5PVA763nsmS8kA28XJvRbCnzvrfgTXJ1aUykJktnT5Jcj_yg@mail.gmail.com> (raw)
In-Reply-To: <CA+5PVA4GNWFx5bDM912TYmDbMHmZpb2X=Tzo85mGEGATvbW70A@mail.gmail.com>

On Thu, Feb 27, 2014 at 2:11 PM, Josh Boyer <jwboyer@fedoraproject.org> wrote:
> On Thu, Feb 27, 2014 at 2:07 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
>> On Thu, Feb 27, 2014 at 01:04:34PM -0500, Josh Boyer wrote:
>>> On Wed, Feb 26, 2014 at 3:11 PM, Matthew Garrett
>>> <matthew.garrett@nebula.com> wrote:
>>> > The conclusion we came to at Plumbers was that this patchset was basically
>>> > fine but that Linus hated the name "securelevel" more than I hate pickled
>>> > herring, so after thinking about this for a few months I've come up with
>>> > "Trusted Kernel". This flag indicates that the kernel is, via some
>>> > external mechanism, trusted and should behave that way. If firmware has
>>> > some way to verify the kernel, it can pass that information on. If userspace
>>> > has some way to verify the kernel, it can set the flag itself. However,
>>> > userspace should not attempt to use the flag as a means to verify that the
>>> > kernel was trusted - untrusted userspace could have set it on an untrusted
>>> > kernel, but by the same metric an untrusted kernel could just set it itself.
>>>
>>> FWIW, I've been running a kernel using this patchset in place of the
>>> patchset Fedora typically carries for this purpose for a bit.  Things
>>> appear to be working as expected and the protections remain the same.
>>>
>>> It would be really nice to get this set of patches in so some of the
>>> other patches that depend on them can start being pushed as well.
>>
>> What other patches depend on this series?  Why aren't they also in this
>> series?
>
> The patches we have to import certificates from the UEFI db and dbx
> vars, and MokListRT and apply them to signed module verification.
> Looking at them closely, there are pieces that could be sent now as
> they are slightly orthogonal to what this patchset is doing, which is
> probably why they aren't in this patchset to begin with.  I'll have to
> figure out which of those actually depend on anything in Matthew's
> series.

OK, I figured it out.  I have a patch that adds an EFI_SECURE_BOOT
x86_efi_facility bit, and that is used in the later patches where
applicable.  The patch that adds it depends on patch 12 in Matthew's
series.

There are a few patches that are mostly stand-alone and I'll try and
get those sent out soon.  They're a mix of things from David Howells
and myself, and should probably go through the security tree.

josh