Date: Thu, 31 May 2001 11:00:18 -0700 From: "Crist Clark" <crist.clark@globalstar.com> To: Dan Pelleg <dpelleg+bsd@REMOVEcs.cmu.edu> Cc: freebsd-security@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG Subject: Re: remounts (was: Re: adding "noschg" to ssh and friends) Message-ID: <3B1686B2.5693822B@globalstar.com> References: <20010531123020.6044537B422@hub.freebsd.org>
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Dan Pelleg wrote: > > "Karsten W. Rohrbach" <karsten@rohrbach.de> wrote: > > there are some real high-impact tweaks to be a little bit safer from > > rootkits. one of them is mounting /tmp noexec. drawback: you got to > > remount it exec for make installworld. > > I always wondered... Why are remounts permitted in all securelevels? I > mean, in a locked-down system where it's acceptable to force a reboot in > order to upgrade (or run a rootkit), I should be able to enforce read-only > mounts. Currently anyone (well, root) can just mount -u -w them. > > Is this an implementation problem in mount(2)? (I haven't looked at the > code). Or is this going to break things for people (amd? in high > securelevels?). What am I missing? I wrote a very simple patch that disallows mount(2) calls at elevated securelevel some time ago. Check the -security archives for December or so. Also look for a long thread on the whole question of turning off mount(2) at high securelevel. As for breaking things, yes, it will. You cannot mount stuff. But that's the whole idea. ;) OK, found it in the archive, http://docs.freebsd.org/mail/archive/2000/freebsd-security/20001224.freebsd-security.html Look at the 'Read-Only Filesystems' thread. -- Crist J. Clark Network Security Engineer crist.clark@globalstar.com Globalstar, L.P. (408) 933-4387 FAX: (408) 933-4926 The information contained in this e-mail message is confidential, intended only for the use of the individual or entity named above. If the reader of this e-mail is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any review, dissemination, distribution or copying of this communication is strictly prohibited. If you have received this e-mail in error, please contact postmaster@globalstar.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
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