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Date: Mon, 22 Apr 2013 10:59:19 -0700
Message-ID: <CAGXu5jLJDWa5oLwFy7ZA1QdNKAQUCGEkCiVw+AD_1Bf9K8ULrQ@mail.gmail.com>
Subject: Re: [PATCH] x86: kaslr: move ELF relocation handling to C
From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>, LKML <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "kernel-hardening@lists.openwall.com" 
	<kernel-hardening@lists.openwall.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        David Woodhouse <David.Woodhouse@intel.com>,
        Jiri Kosina <jkosina@suse.cz>, Olaf Hering <olaf@aepfle.de>,
        Yinghai Lu <yinghai@kernel.org>, Matt Fleming <matt.fleming@intel.com>,
        Gokul Caushik <caushik1@gmail.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Joe Millenbach <jmillenbach@gmail.com>,
        Alexander Duyck <alexander.h.duyck@intel.com>,
        Jacob Shin <jacob.shin@amd.com>, Pekka Enberg <penberg@kernel.org>,
        Eric Northup <digitaleric@google.com>,
        Dan Rosenberg <drosenberg@vsecurity.com>,
        Julien Tinnes <jln@google.com>, Will Drewry <wad@chromium.org>
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On Mon, Apr 22, 2013 at 1:04 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Kees Cook <keescook@chromium.org> wrote:
>
>> On Sun, Apr 21, 2013 at 2:13 AM, Ingo Molnar <mingo@kernel.org> wrote:
>> >
>> > * Kees Cook <keescook@chromium.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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