From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id EF1B66B00D2 for ; Wed, 3 Jun 2009 15:20:23 -0400 (EDT) Date: Wed, 3 Jun 2009 20:21:17 +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: <20090603202117.39b070d5@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> 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: On Wed, 3 Jun 2009 14:59:51 -0400 (EDT) Christoph Lameter wrote: > We could just move the check for mmap_min_addr out from > CONFIG_SECURITY? > > > Use mmap_min_addr indepedently of security models > > This patch removes the dependency of mmap_min_addr on CONFIG_SECURITY. > It also sets a default mmap_min_addr of 4096. > > mmapping of addresses below 4096 will only be possible for processes > with CAP_SYS_RAWIO. This appears to break the security models as they can no longer replace the CAP_SYS_RAWIO check with something based on the security model. > @@ -1043,6 +1046,9 @@ unsigned long do_mmap_pgoff(struct file > } > } > > + if ((addr < mmap_min_addr) && !capable(CAP_SYS_RAWIO)) > + return -EACCES; > + You can't move this bit here > error = security_file_mmap(file, reqprot, prot, flags, addr, 0); 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. So NAK - not to the idea but to the fact the patch is buggy. Alan -- 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