kernel-hardening - Re: [PATCH] x86: kaslr: move ELF relocation handling to C

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Message-ID: <CAGXu5jLJDWa5oLwFy7ZA1QdNKAQUCGEkCiVw+AD_1Bf9K8ULrQ@mail.gmail.com>
Date: Mon, 22 Apr 2013 10:59:19 -0700
From: Kees Cook <keescook@...omium.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: "H. Peter Anvin" <hpa@...or.com>, LKML <linux-kernel@...r.kernel.org>, 
	"x86@...nel.org" <x86@...nel.org>, 
	"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, David Woodhouse <David.Woodhouse@...el.com>, 
	Jiri Kosina <jkosina@...e.cz>, Olaf Hering <olaf@...fle.de>, Yinghai Lu <yinghai@...nel.org>, 
	Matt Fleming <matt.fleming@...el.com>, Gokul Caushik <caushik1@...il.com>, 
	Josh Triplett <josh@...htriplett.org>, Joe Millenbach <jmillenbach@...il.com>, 
	Alexander Duyck <alexander.h.duyck@...el.com>, Jacob Shin <jacob.shin@....com>, 
	Pekka Enberg <penberg@...nel.org>, Eric Northup <digitaleric@...gle.com>, 
	Dan Rosenberg <drosenberg@...curity.com>, Julien Tinnes <jln@...gle.com>, 
	Will Drewry <wad@...omium.org>
Subject: Re: [PATCH] x86: kaslr: move ELF relocation handling to C

On Mon, Apr 22, 2013 at 1:04 AM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Kees Cook <keescook@...omium.org> wrote:
>
>> On Sun, Apr 21, 2013 at 2:13 AM, Ingo Molnar <mingo@...nel.org> wrote:
>> >
>> > * Kees Cook <keescook@...omium.org> wrote:
>> >
>> >> Moves the relocation handling into C, after decompression. Only
>> >> kernels that need relocation support will use the code. The new
>> >> CONFIG_RANDOMIZE_BASE does not yet do anything except turn on this logic
>> >> for 64-bit kernels.
>> >
>> > So why not keep the inactive CONFIG_RANDOMIZE_BASE hunks in a separate
>> > patch, and just have this one clean, orthogonal patch that moves
>> > relocation handling into C?
>>
>> I had wanted there to be a way to test building with 64-bit
>> relocations. With this patch and CONFIG_RANDOMIZE_BASE=y, I could do
>> that. Would you rather I remove those pieces?
>
> But AFAICS CONFIG_RANDOMIZE_BASE is not an interactive config option, so
> how did you turn it on?

I directly edited the .config file to enable it.

> But no strong objections in any case.

HPA, any opinion? How would you like to see arranged for tip/kaslr?

-Kees

--
Kees Cook
Chrome OS Security

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