From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753645AbbCCHbm (ORCPT ); Tue, 3 Mar 2015 02:31:42 -0500 Received: from mail-wi0-f179.google.com ([209.85.212.179]:38987 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752602AbbCCHbj (ORCPT ); Tue, 3 Mar 2015 02:31:39 -0500 Date: Tue, 3 Mar 2015 08:31:32 +0100 From: Ingo Molnar To: Kees Cook Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , linux390@de.ibm.com, x86@kernel.org, Alexander Viro , Oleg Nesterov , Andy Lutomirski , "David A. Long" , Andrey Ryabinin , Arun Chandran , Yann Droneaud , Min-Hua Chen , Paul Burton , Alex Smith , Markos Chandras , Jeff Bailey , Vineeth Vijayan , Michael Holzheu , Ben Hutchings , Hector Marco-Gisbert , Borislav Petkov , Jan-Simon =?iso-8859-1?Q?M=F6ller?= , linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, Linus Torvalds , Borislav Petkov , "H. Peter Anvin" , Thomas Gleixner Subject: Re: [PATCH v2 0/5] split ET_DYN ASLR from mmap ASLR Message-ID: <20150303073132.GA30602@gmail.com> References: <1425341988-1599-1-git-send-email-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1425341988-1599-1-git-send-email-keescook@chromium.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Kees Cook wrote: > To address the "offset2lib" ASLR weakness[1], this separates ET_DYN > ASLR from mmap ASLR, as already done on s390. The architectures > that are already randomizing mmap (arm, arm64, mips, powerpc, s390, > and x86), have their various forms of arch_mmap_rnd() made available > via the new CONFIG_ARCH_HAS_ELF_RANDOMIZE. For these architectures, > arch_randomize_brk() is collapsed as well. > > This is an alternative to the solutions in: > https://lkml.org/lkml/2015/2/23/442 Looks good so far: Reviewed-by: Ingo Molnar While reviewing this series I also noticed that the following code could be factored out from architecture mmap code as well: - arch_pick_mmap_layout() uses very similar patterns across the platforms, with only few variations. Many architectures use the same duplicated mmap_is_legacy() helper as well. There's usually just trivial differences between mmap_legacy_base() approaches as well. - arch_mmap_rnd(): the PF_RANDOMIZE checks are needlessly exposed to the arch routine - the arch routine should only concentrate on arch details, not generic flags like PF_RANDOMIZE. In theory the mmap layout could be fully parametrized as well: i.e. no callback functions to architectures by default at all: just declarations of bits of randomization desired (or, available address space bits), and perhaps an arch helper to allow 32-bit vs. 64-bit address space distinctions. 'Weird' architectures could provide special routines, but only by overriding the default behavior, which should be generic, safe and robust. Thanks, Ingo