Re: Special Kernel Modification

[Jorgen Cederlof <jc@lysator.liu.se>]

On Sun, Nov 04, 2001 at 19:29:01 -0500, lonnie@outstep.com wrote:

> From what I can see. With chrooting, I have to make a complete
> "fake" system an then place the users below that into a home
> directory, or make a complete "fake" system for each user.
> 
> I was trying to find a simple solution that would allow for:
> 
> I was initially thinking about something like this for each user:
> 
> /system (real) /dev/hda4 (chrooted also)
>       |
>       /bin
>       /etc
>       /lib

chtrunk (http://noid.sf.net/chtrunk.html) can set up the namespace
dynamically for you. Instead of creating a complete system by hand and
run chroot, just run (you don't need to be root):

   chtrunk -s /bin /etc /lib /home/user -c program_to_run

This will give that program access to /bin, /etc, /lib and the home
directory, but nothing more.

You can use

   chtrunk -s /bin /etc /lib /home/user /tmp=/home/user/tmp -c program

to give every user their own private /tmp.

As a bonus, the suid/sgid bits will have no effect for these users,
which will prevent them from becoming root through buggy suid
programs.

    Jörgen