Subject: Re: How to enable/disable security features on mmap() ?
From: Arjan van de Ven <arjan@infradead.org>
To: Emmanuel Fleury <emmanuel.fleury@labri.fr>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
In-Reply-To: <43984595.1090406@labri.fr>
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	 <43984154.5050502@labri.fr>  <43984595.1090406@labri.fr>
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Date: Thu, 08 Dec 2005 15:49:09 +0100
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On Thu, 2005-12-08 at 15:39 +0100, Emmanuel Fleury wrote:
> I guess that setting the variable randomize_va_space to 0 just remove
> the stack pointer (sp) randomization.
> 
> Seen in arch/i386/kernel/process.c:
> 
> unsigned long arch_align_stack(unsigned long sp)
> {
>         if (randomize_va_space)
>                 sp -= get_random_int() % 8192;
>         return sp & ~0xf;
> }
> 
> Why not having defined this as a CONFIG_STACK_RANDOMIZATION variables

well it's a /proc/ variable already! So you can just turn it off
entirely at runtime. (what is better is that you use the setarch program
to turn it off for selected programs though...)


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