Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934899Ab3DOWnB (ORCPT ); Mon, 15 Apr 2013 18:43:01 -0400 Received: from mail-ob0-f173.google.com ([209.85.214.173]:43159 "EHLO mail-ob0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932513Ab3DOWm7 (ORCPT ); Mon, 15 Apr 2013 18:42:59 -0400 MIME-Version: 1.0 In-Reply-To: References: <1365797627-20874-1-git-send-email-keescook@chromium.org> <1365797627-20874-7-git-send-email-keescook@chromium.org> <516A1D49.1050100@zytor.com> <516C702C.2030209@zytor.com> <516C751B.4020505@zytor.com> Date: Mon, 15 Apr 2013 15:42:59 -0700 X-Google-Sender-Auth: QmLc9mSe9GWocdmGgBUl_o20LBo Message-ID: Subject: Re: [PATCH 6/6] x86: kaslr: relocate base offset at boot From: Kees Cook To: Yinghai Lu Cc: "H. Peter Anvin" , Eric Northup , 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: 1354 Lines: 34 On Mon, Apr 15, 2013 at 3:38 PM, Yinghai Lu wrote: > On Mon, Apr 15, 2013 at 3:07 PM, Kees Cook wrote: >> On Mon, Apr 15, 2013 at 3:00 PM, Yinghai Lu wrote: >>> also do not overlap with boot_param, command_line, and initrd. >>> >>> and need to double check setup_header.init_size to make sure bss and >>> etc will not >>> fall into memory hole or reserved area in e820. >>> >>> also may need to setup page table for target position as bootloader may only >>> has ident mapping only for loaded bzImage 64 areas. >>> >>> looks you are trying redo the work for bootloader to pick loaded phys addr. >> >> aslr.S's select_aslr_address uses z_extract_offset as the upper bound. > > so the decompressed image is not moved high? No, I mean the size of the relocated image is using z_extract_offset as the end size of the relocated memory. See select_aslr_address. It takes the chosen aslr offset plus the location of z_extract_offset and keeps reducing the offset until it's inside the physical end of memory. -Kees -- Kees Cook Chrome OS Security -- 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/