Date: Mon, 24 Jul 2000 11:27:42 -0400 From: Thomas Stromberg <tstromberg@rtci.com> To: Paul Hart <hart@iserver.com> Cc: freebsd-security@FreeBSD.ORG Subject: Re: Status of FreeBSD security work? Audit, regression and cryptoswap? Message-ID: <397C606E.131A5CAE@rtci.com> References: <Pine.BSF.4.21.0007231906050.32554-100000@anchovy.orem.iserver.com>
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Paul Hart wrote:
> One other bad thing about using CFS for a home directory is the fact that
> cdetach cannot make distinctions about whether it is the owner of the CFS
> mount who is detaching it. As long as you know the name of the mount you
> can detach mounts belonging to other people. Since your home directory
> needs to be a fixed (and well-known) path name, you can become vulnerable
> to a lame variety of denial-of-service attack against your account.
>
> Paul Hart
What we did here for the cfs security disk script was:
$target = sprintf("/crypt/.%lx", int(rand(999999)));
Which provides a relatively randomized mountpoint which lies only in the
knowledge of cfsd and the perl script. I also take advantage of the cfs
feature which hides directories starting with a .
This of course is by no means perfect, but it was secure enough for our
requirements.
However, if you wanted to make use of this as a home directory, you'd
have
to symlink to it (what I did), which would publicize the mountpoint.
<mindlessbabble>
Though I guess some wierd antics can be done by changing the $HOME
variable. ps -e will still find it however, and not all software
respects
$HOME. One could also dynamically modify their getpwent() info, and
store
it in a privatized location (nss-ldap anyone?).. This however is pure
and
utter insanity :) It'd be much easier to mod the cfs code.
</mindlessbabble>
I'd love to see tcfs ported to FreeBSD, maybe it will alleviate some of
the
hackery.
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--
thomas r. stromberg : tstromberg@rtci.com
senior systems administrator : http://www.afterthought.org/
research triangle commerce, inc. : 1.919.657.1317
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