linux-kernel - Re: [PATCH 0/4] KEYS: validate key trust with owner and builtin keys only

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Message-ID: <20140610212516.GB10614@srcf.ucam.org>
Date:	Tue, 10 Jun 2014 22:25:16 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Cc:	Josh Boyer <jwboyer@...hat.com>,
	David Howells <dhowells@...hat.com>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Dmitry Kasatkin <d.kasatkin@...sung.com>,
	keyrings <keyrings@...ux-nfs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-security-module <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH 0/4] KEYS: validate key trust with owner and builtin keys
 only

On Wed, Jun 11, 2014 at 12:17:53AM +0300, Dmitry Kasatkin wrote:

> It is probably just a paranoia...
> Kconfig MODULE_SIG_UEFI should tell about threat of loading kernel
> modules from NSA or Lenovo signed by MS or Lenovo keys..
>
> This hole is opened without warning...

It's not typically a hole. If an attacker has root they can just replace 
your bootloader with one signed by a trusted key and then have that 
modify the kernel before booting it.

If you're using a TPM then you can mitigate this, but if you have a TPM 
then you're already performing some extra steps during the boot process. 
Just add a sysfs knob that lets you drop the db keys and incorporate 
that into the TPM management code.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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