Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755452Ab3DOVGi (ORCPT ); Mon, 15 Apr 2013 17:06:38 -0400 Received: from mail-we0-f170.google.com ([74.125.82.170]:37330 "EHLO mail-we0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753136Ab3DOVGg (ORCPT ); Mon, 15 Apr 2013 17:06:36 -0400 MIME-Version: 1.0 In-Reply-To: <516A1D49.1050100@zytor.com> References: <1365797627-20874-1-git-send-email-keescook@chromium.org> <1365797627-20874-7-git-send-email-keescook@chromium.org> <516A1D49.1050100@zytor.com> Date: Mon, 15 Apr 2013 14:06:33 -0700 Message-ID: Subject: Re: [PATCH 6/6] x86: kaslr: relocate base offset at boot From: Eric Northup To: "H. Peter Anvin" Cc: Yinghai Lu , Kees Cook , Linux Kernel Mailing List , "kernel-hardening@lists.openwall.com" , Thomas Gleixner , Ingo Molnar , "the arch/x86 maintainers" , Jarkko Sakkinen , Matthew Garrett , Matt Fleming , Dan Rosenberg , Julien Tinnes , Will Drewry Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1150 Lines: 27 On Sat, Apr 13, 2013 at 8:06 PM, H. Peter Anvin wrote: > On 04/13/2013 05:37 PM, Yinghai Lu wrote: >> >> so decompress code position is changed? >> >> You may push out bss and other data area of run-time kernel of limit >> that boot loader >> chose according to setup_header.init_size. >> aka that make those area overlap with ram hole or other area like >> boot command line or initrd.... >> > > Is there a strong reason to randomize the physical address on 64 bits > (and if so, shouldn't we do it right?) The reason to randomize the physical address is because of the kernel direct mapping range -- a predictable-to-attackers physical address implies a predictable-to-attackers virtual address. It had seemed to me like changing the virtual base of the direct mapping would be much more involved than physically relocating the kernel, but better suggestions would be most welcome :-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/