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

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Message-ID: <1360736860.18083.33.camel@x230.lan>
Date:	Wed, 13 Feb 2013 06:27:40 +0000
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	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 Tue, 2013-02-12 at 22:12 -0800, H. Peter Anvin wrote:

> Sounds like you are thinking of CAP_SYS_ADMIN, but I don't really see a 
> huge difference between MSRs and I/O control registers... just different 
> address spaces.

Not having CAP_SYS_RAWIO blocks various SCSI commands, for instance.
These might result in the ability to write individual blocks or destroy
the device firmware, but do any of them permit modifying the running
kernel?