From owner-freebsd-security Fri Dec 22 12:44:10 2000 From owner-freebsd-security@FreeBSD.ORG Fri Dec 22 12:44:07 2000 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7400637B400 for ; Fri, 22 Dec 2000 12:44:07 -0800 (PST) Received: from daffy.napanet.net (daffy.napanet.net [206.81.96.18]) by mx1.FreeBSD.org (Postfix) with ESMTP id D03E86E2555 for ; Fri, 22 Dec 2000 12:44:02 -0800 (PST) Received: from sb (dialup-157.oakland.ca.interx.net [209.209.29.157]) by daffy.napanet.net (8.9.3/8.9.3) with SMTP id MAA48369; Fri, 22 Dec 2000 12:42:18 -0800 (PST) Message-ID: <005001c06c57$adab1980$3da2169d@napanet.net> From: "VP of Engineering" To: "Michael A. Williams" , References: <20001219114936.A23819@rfx-64-6-211-149.users.reflexco> <3A3FC57F.E80331A7@netxsecure.net> Subject: Re: Read-Only Filesystems Date: Fri, 22 Dec 2000 12:42:16 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Not quite as secure as putting your read only files on a separate drive and placing the "read-only" jumper on the drive - then it requires getting into the machine itself. Last time I checked this was a feature on many SCSI drives, not many IDE drives. Steve ----- Original Message ----- From: "Michael A. Williams" To: Sent: Tuesday, December 19, 2000 12:30 PM Subject: Re: Read-Only Filesystems > How about applying the immutable flag (uchg) with chflags to selected > branches of the file system tree and in combination with kernel > securelevel 2 then a reboot at the console into single user mode is > required to reverse the immutable state of the files. > In the end this comes down to physical security of the console. > > cheers, > Mike. > > > "Crist J. Clark" wrote: > > > > I was recently playing around with the idea of having a read-only root > > filesystem. However, it has become clear that there is no way to > > prevent root from changing the mount properties on any filesystem, > > including the root filesystem, provided there is no hardware-level > > block on writing and there is someplace (anyplace) where root can > > write. > > > > Is that accurate? I guess one must go to a "trusted OS" to get that > > type of functionality? > > -- > > Crist J. Clark cjclark@alum.mit.edu > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > with "unsubscribe freebsd-security" in the body of the message > > -- > Michael A. Williams, InfoSec Technology Manager > NetXSecure NZ Limited, mike@netxsecure.net www.netxsecure.com > Ph.+64.9.278.8348, Fax.+64.9.278.8352, Mob.+64.21.995.914 > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-security" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message