linux-kernel - Re: [PATCH RFC] mm: protect suid binaries against rowhammer with copy-on-read mappings

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Date:	Thu, 19 Mar 2015 16:24:39 +0300
From:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:	Vlastimil Babka <vbabka@...e.cz>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Konstantin Khlebnikov <koct9i@...il.com>
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@...capital.net>
Subject: Re: [PATCH RFC] mm: protect suid binaries against rowhammer with
 copy-on-read mappings

On 19.03.2015 16:04, Vlastimil Babka wrote:
> On 03/18/2015 12:41 PM, Konstantin Khlebnikov wrote:
>> On 18.03.2015 12:57, Kirill A. Shutemov wrote:
>>>
>>> I don't think it worth it. The only right way to fix the problem is ECC
>>> memory.
>>>
>>
>> ECC seems good protection until somebody figure out how to break it too.
>
> I doubt that kind of attitude can get us very far. If we can't trust the
> hardware, we lose sooner or later.
>

Obviously ECC was designed for protecting against cosmic rays which 
flips several bits. If attacker modifies whole cacheline he can chose
value which have the same ECC. I hope next generation of DRAM (or PRAM)
wouldn't be affected.

Software solution is possible: we can put untrusted applications into
special ghetto memory zone. This is relatively easy for virtual 
machines. And it seems might work for normal tasks too (page-cache
pages should be doubled or handled in the way similar to copy-on-read
from that patch).

-- 
Konstantin
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