[luau] restricting directory access

[Warren Togami]

----- Original Message -----
From: "Jimen Ching" <jching at flex.com>
To: <luau at videl.ics.hawaii.edu>
Sent: Friday, April 26, 2002 10:15 AM
Subject: Re: [luau] restricting directory access


> > or they can use programs on the server (or upload their own) to
> >use the server as an relay from which they can scan and attack other
> >machines.
>
> True, but _your_ server is safe.  ;-)  Seriously, if you are so uptight
> that you are not willing to let a user cd out of their home directory, and
> yet you allow them to upload anything they want?  This completely defeats
> the purpose of the cd limitation.
>

It would take more than cd limitation alone to keep users from mischief.
Certain kernel patches like vserver can strip away system priveledges, and
you can use iptables to prevent ANY outgoing network stuff from a certain
portion of your system.  You can also mount the /home directory with nodev,
noexec, nosuid disallowing device files, executable files and setuid files
further locking down security.

If they cannot access the network or other portions of the server, even if
they manage to execute something like a perl script, they can't do anything
but mess up their own home directory.  If they manage to crack root using a
kernel bug, they can mess up files within their own jail, but they still
wont be able to use the network, directly access hardware or do anything
else to the rest of the system.

Outside of this you can run tripwire to monitor the jail cells.  If they
start to mess with stuff that they aren't supposed to, Tripwire will alert
the administrator.  This type of setup is NEARLY IMPOSSIBLE to compromise
Tripwire.