From owner-freebsd-security Wed Dec 20 17:41:31 2000 From owner-freebsd-security@FreeBSD.ORG Wed Dec 20 17:41:29 2000 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from fw.wintelcom.net (ns1.wintelcom.net [209.1.153.20]) by hub.freebsd.org (Postfix) with ESMTP id 8357D37B400; Wed, 20 Dec 2000 17:41:29 -0800 (PST) Received: (from bright@localhost) by fw.wintelcom.net (8.10.0/8.10.0) id eBL1fTM14340; Wed, 20 Dec 2000 17:41:29 -0800 (PST) Date: Wed, 20 Dec 2000 17:41:29 -0800 From: Alfred Perlstein To: Kris Kennaway Cc: Mark Zielinski , cjclark@alum.mit.edu, freebsd-security@FreeBSD.ORG Subject: Re: Read-Only Filesystems Message-ID: <20001220174129.F19572@fw.wintelcom.net> References: <20001219114936.A23819@rfx-64-6-211-149.users.reflexco> <20001219120953.S19572@fw.wintelcom.net> <20001219211642.D13474@citusc.usc.edu> <3A40BED3.1070909@2cactus.com> <20001220174056.C22288@citusc.usc.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20001220174056.C22288@citusc.usc.edu>; from kris@FreeBSD.ORG on Wed, Dec 20, 2000 at 05:40:56PM -0800 Sender: bright@fw.wintelcom.net Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org * Kris Kennaway [001220 17:39] wrote: > On Wed, Dec 20, 2000 at 02:14:43PM +0000, Mark Zielinski wrote: > > This is a attack that we fixed in SecureBSD by not allowing > > filesystems to be un-mounted and re-mounted back in May of 1999. > > We added security checks to the mount() and unmount() system calls > > based upon a MIB called securebsd.options.mount which could be > > turned on or off depending upon your securelevel setting. > > The argument is that securelevel is fundamentally flawed and fairly > useless as a security feature, unless you treat every system reboot > (expected or not) as a potential compromise. Actually, securelevel as a all-covering blanket would work better if people implemented fixes for it like a solution for the mount problem described here. Securelevel is hard to implement, but hard to mess up unlike ACLs which are both hard to implement and hard to deploy. -- -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] "I have the heart of a child; I keep it in a jar on my desk." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message