linux-kernel - Re: [PATCH] x86: NX protection for kernel data

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Message-ID: <20090719131808.77f986f3@infradead.org>
Date:	Sun, 19 Jul 2009 13:18:08 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Siarhei Liakh <sliakh.lkml@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	Andi Kleen <andi@...stfloor.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Ingo Molnar <mingo@...e.hu>, James Morris <jmorris@...ei.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@....de>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-cris-kernel@...s.com,
	Roland Dreier <rdreier@...co.com>
Subject: Re: [PATCH] x86: NX protection for kernel data

On Sun, 19 Jul 2009 15:43:06 -0400
Siarhei Liakh <sliakh.lkml@...il.com> wrote:

> This patch expands functionality of CONFIG_DEBUG_RODATA to set main
> (static) kernel data area as NX.
> The following steps are taken to achieve this:
> 1. Linker scripts are adjusted so .text always starts and end on a
> page boundary 2. Linker scripts are adjusted so .rodata and .data
> always starts and end on a page boundary
> 3. void mark_nxdata_nx(void) added to arch/x86/mm/init_64.c and
> arch/x86/mm/init_32.c with actual functionality: NX is set for all
> pages from _etext through _edata
> 4. mark_nxdata_nx() called from init_post(void) in init/main.c
> 
> The patch have been developed for Linux 2.6.30 x86 by Siarhei Liakh
> <sliakh.lkml@...il.com> and Xuxian Jiang <jiang@...ncsu.edu>.

I like the idea, and am happy to see the lack of ifdefs ;)

I wonder if we should have a testcase for this though similar to 
how stackprotector and rodata get tested already....
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