linux-kernel - Re: [RFC, PATCH] pagemap: do not leak physical addresses to non-privileged userspace

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Message-ID: <20150316211122.GD11441@amd>
Date:	Mon, 16 Mar 2015 22:11:22 +0100
From:	Pavel Machek <pavel@....cz>
To:	"Kirill A. Shutemov" <kirill@...temov.name>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	Mark Seaborn <mseaborn@...omium.org>,
	Andy Lutomirski <luto@...capital.net>
Subject: Re: [RFC, PATCH] pagemap: do not leak physical addresses to
 non-privileged userspace

On Mon 2015-03-09 23:11:12, Kirill A. Shutemov wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> 
> As pointed by recent post[1] on exploiting DRAM physical imperfection,
> /proc/PID/pagemap exposes sensitive information which can be used to do
> attacks.
> 
> This is RFC patch which disallow anybody without CAP_SYS_ADMIN to read
> the pagemap.
> 
> Any comments?
> 
> [1]
http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html

Note that this kind of attack still works without pagemap, it just
takes longer. Actually the first demo program is not using pagemap.

Can we do anything about that? Disabling cache flushes from userland
should make it no longer exploitable.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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