linux-kernel - Re: [PATCH] x86: Lock down MSR writing in secure boot

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Message-ID: <1360810018.18083.47.camel@x230.lan>
Date:	Thu, 14 Feb 2013 02:46:58 +0000
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Casey Schaufler <casey@...aufler-ca.com>,
	Borislav Petkov <bp@...en8.de>,
	Kees Cook <keescook@...omium.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	linux-security-module <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH] x86: Lock down MSR writing in secure boot

On Wed, 2013-02-13 at 17:08 -0800, H. Peter Anvin wrote:

> Well, for at least things with device nodes (/dev/mem, /dev/msr and so
> on) it should be possible, no?  ioperm() and iopl() are another matter.

Sure, if we can guarantee that a signed userspace loads a signed SELinux
policy before any unsigned code runs. But, realistically, that's not
going to be possible.

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