From owner-freebsd-security Sun Mar 14 9:25:12 1999 Delivered-To: freebsd-security@freebsd.org Received: from fledge.watson.org (FLEDGE.RES.CMU.EDU [128.2.93.229]) by hub.freebsd.org (Postfix) with ESMTP id 3521915428 for ; Sun, 14 Mar 1999 09:25:05 -0800 (PST) (envelope-from robert@cyrus.watson.org) Received: from fledge.watson.org (robert@fledge.pr.watson.org [192.0.2.3]) by fledge.watson.org (8.8.8/8.8.8) with SMTP id MAA05307; Sun, 14 Mar 1999 12:24:43 -0500 (EST) (envelope-from robert@cyrus.watson.org) Date: Sun, 14 Mar 1999 12:24:43 -0500 (EST) From: Robert Watson X-Sender: robert@fledge.watson.org Reply-To: Robert Watson To: Peter Jeremy Cc: freebsd-security@FreeBSD.ORG Subject: Re: ACL's In-Reply-To: <99Mar14.195521est.40346@border.alcanet.com.au> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Sun, 14 Mar 1999, Peter Jeremy wrote: > Robert Watson wrote: > > >I.e., user creates a hard link to /usr/sbin/somesetuidbin to > >/usr/tmp/mytemp. > > Normal users shouldn't have write permission anywhere on a partition > containing system binaries - this also removes the problem. (Note > that /usr/tmp is accessible only by root under FreeBSD). But many common FS arrangements do use the same partition for a world-writable directory and the binaries. For example: /var on /usr/var (/var has /var/tmp) /usr/local/ on /usr (The tex port requires a world-writable temp directory) /tmp on / (/sbin is usually on /; default install I believe) /home on /usr/home (default install I believe) I like the idea of the FS namespace having consistent semantics--counter-intuitive security behavior like "the system is relatively secure as long as you don't partition the system in any way that allows these files to be on the same partition as these files..." seems best to be avoided. I think hard links are neat, et al, but I really don't think they add any new useful functionality above symlinks, and they can certainly introduce new problems. They save a little disk space here and there (as long as you don't recursive move anything)... Robert N Watson robert@fledge.watson.org http://www.watson.org/~robert/ PGP key fingerprint: 03 01 DD 8E 15 67 48 73 25 6D 10 FC EC 68 C1 1C Carnegie Mellon University http://www.cmu.edu/ TIS Labs at Network Associates, Inc. http://www.tis.com/ Safeport Network Services http://www.safeport.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message