linux-kernel - Re: [RFC] Second attempt at kernel secure boot support

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Date:	Thu, 1 Nov 2012 14:46:35 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Eric Paris <eparis@...isplace.org>
Cc:	James Bottomley <James.Bottomley@...senpartnership.com>,
	Jiri Kosina <jkosina@...e.cz>, Oliver Neukum <oneukum@...e.de>,
	Chris Friesen <chris.friesen@...band.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Josh Boyer <jwboyer@...il.com>, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org
Subject: Re: [RFC] Second attempt at kernel secure boot support

> Imagine you run windows and you've never heard of Linux.

To those people I think you mean "never heard of Ubuntu" ;-)

> In this case we have a completely 'untrusted' root inside Linux.  From
> the user PoV root and Linux are both malware.  Notice the EXACT same
> attack would work launching rootkit'd Linux from Linux.  So don't
> pretend not to care about Windows.  It's just that launching malware
> Linux seems like a reason to get your key revoked.  We don't want
> signed code which can be used as an attack vector on ourselves or on
> others.
> 
> That make sense?

Not really but it keeps some of the Red Hat security people happy and out
of harms way. With all the current posted RH patches I can still take over
the box as root trivially enough and you seem to have so far abolished
suspend to disk, kexec and a pile of other useful stuff. To actually lock
it down you'll have to do a ton more of this. I suspect folks who know
windows innards well are probably thinking the same about Windows 8 8)

Almost anyone attacking a secure boot box will do it via windows or more
likely via EFI. EFI because its large, new and doesn't a great history,
windows because its the larger target. Actually from what I've seen on
the security front there seems to a distinct view that secure boot is
irrelevant because Windows 8 is so suspend/resume focussed that you might
as well just trojan the box until the next reboot as its likely to be a
couple of weeks a way.

Alan

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