From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id D781E6B008A for ; Wed, 3 Jun 2009 17:06:55 -0400 (EDT) Date: Wed, 3 Jun 2009 22:07:39 +0100 From: Alan Cox Subject: Re: Security fix for remapping of page 0 (was [PATCH] Change ZERO_SIZE_PTR to point at unmapped space) Message-ID: <20090603220739.1f6fb518@lxorguk.ukuu.org.uk> In-Reply-To: References: <20090530230022.GO6535@oblivion.subreption.com> <20090531022158.GA9033@oblivion.subreption.com> <20090602203405.GC6701@oblivion.subreption.com> <20090603182949.5328d411@lxorguk.ukuu.org.uk> <20090603180037.GB18561@oblivion.subreption.com> <20090603183939.GC18561@oblivion.subreption.com> <20090603202117.39b070d5@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Linus Torvalds , "Larry H." , linux-mm@kvack.org, Rik van Riel , linux-kernel@vger.kernel.org, pageexec@freemail.hu List-ID: > > You need it in the default (no security) version of security_file_mmap() > > in security.h not hard coded into do_mmap_pgoff, and leave the one in > > cap_* alone. > > But that would still leave it up to the security "models" to check > for basic security issues. Correct. You have no knowledge of the policy at the higher level. In the SELinux case security labels are used to identify code which is permitted to map low pages. That means the root/RAW_IO security sledgehammer can be replaced with a more secure labelling system. Other policy systems might do it on namespaces (perhaps /bin and /usr/bin mapping zero OK, /home not etc) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org