Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755653AbZFCRg6 (ORCPT ); Wed, 3 Jun 2009 13:36:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753596AbZFCRgv (ORCPT ); Wed, 3 Jun 2009 13:36:51 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:56955 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752823AbZFCRgv (ORCPT ); Wed, 3 Jun 2009 13:36:51 -0400 Date: Wed, 3 Jun 2009 10:35:10 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Alan Cox cc: Christoph Lameter , "Larry H." , linux-mm@kvack.org, Rik van Riel , linux-kernel@vger.kernel.org, pageexec@freemail.hu Subject: Re: Security fix for remapping of page 0 (was [PATCH] Change ZERO_SIZE_PTR to point at unmapped space) In-Reply-To: <20090603182949.5328d411@lxorguk.ukuu.org.uk> Message-ID: References: <20090530192829.GK6535@oblivion.subreption.com> <20090530230022.GO6535@oblivion.subreption.com> <20090531022158.GA9033@oblivion.subreption.com> <20090602203405.GC6701@oblivion.subreption.com> <20090603182949.5328d411@lxorguk.ukuu.org.uk> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 952 Lines: 23 On Wed, 3 Jun 2009, Alan Cox wrote: > > One way you could approach this would be to write a security module for > non SELINUX users - one that did one thing alone - decide whether the app > being run was permitted to map the low 64K perhaps by checking the > security label on the file. Unnecessary. I really think that 99% of all people are perfectly fine with just the "mmap_min_addr" rule, and no more. The rest could just use SElinux or set it to zero. It's not like allowing mmap's at NULL is a huge problem. Sure, it allows a certain kind of attack vector, but it's by no means an easy or common one - you need to already have gotten fairly good local access to take advantage of it. Linus -- 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/