linux-kernel - Re: [PATCH] Undo some of the pseudo-security madness

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Date:	Mon, 22 Jan 2007 00:38:16 +0300
From:	Samium Gromoff <_deepfire@...lingofgreen.ru>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Samium Gromoff <_deepfire@...lingofgreen.ru>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Undo some of the pseudo-security madness

At Sun, 21 Jan 2007 03:16:04 +0100,
Arjan van de Ven wrote:
> On Sat, 2007-01-20 at 17:37 +0300, Samium Gromoff wrote:
> > This patch removes the dropping of ADDR_NO_RANDOMIZE upon execution of setuid
> > binaries.
> > 
> > Why? The answer consists of two parts:
> > 
> > Firstly, there are valid applications which need an unadulterated memory map.
> > Some of those which do their memory management, like lisp systems (like SBCL).
> > They try to achieve this by setting ADDR_NO_RANDOMIZE and reexecuting themselves.
> 
> this is a ... funny way of achieving this
> 
> if an application for some reason wants some fixed address for a piece
> of memory there are other ways to do that.... (but to some degree all
> apps that can't take randomization broken; for example a glibc upgrade
> on a system will also move the address space around by virtue of being
> bigger or smaller etc etc)
> > [1]. See the excellent, 'Hackers Hut' by Andries Brouwer, which describes
> > how AS randomisation can be got around by the means of linux-gate.so.1
> 
> got a URL to this? If this is exploiting the fact that the vdso is at a
> fixed spot... it's no longer the case since quite a while.

hmm, it seems to rely on that, yes:

http://www.win.tue.nl/~aeb/linux/hhh/hh-9.html#ss9.6
 
> -- 
> if you want to mail me at work (you don't), use arjan (at) linux.intel.com
> Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org

regards, Samium Gromoff
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