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Date: Mon, 8 Nov 2010 10:03:42 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Ingo Molnar <mingo@elte.hu>
Cc: Kees Cook <kees.cook@canonical.com>, Siarhei Liakh <sliakh.lkml@gmail.com>,
        Rusty Russell <rusty@rustcorp.com.au>, linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Arjan van de Ven <arjan@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [Security] proactive defense: using read-only memory, RO/NX
 modules
Message-ID: <20101108100342.61dde238@lxorguk.ukuu.org.uk>
In-Reply-To: <20101108061324.GA30540@elte.hu>
References: <20101107193520.GO5327@outflux.net>
	<20101108061324.GA30540@elte.hu>
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> Nice! IMHO we need more of that. (If the readonly section gets big enough in 
> practice we could perhaps even mark it large-page in the future. It could serve as 
> an allocator to module code as well - that would probably be a speedup even for 
> modules.)

You ideally want one other thing to go with it. While a non-guest can't
support it the marking of pages "permanently and irrevocably" readonly in
a guest is something a hypedvisor can happily enforce and provide for the
lifetime of the guest.

Alan