Re: [PATCH] User chroot

[daw@mozart.cs.berkeley.edu (David Wagner)]

H. Peter Anvin wrote:
>By author:    Jorgen Cederlof <jc@lysator.liu.se>
>> If we only allow user chroots for processes that have never been
>> chrooted before, and if the suid/sgid bits won't have any effect under
>> the new root, it should be perfectly safe to allow any user to chroot.
>
>Safe, perhaps, but also completely useless: there is no way the user
>can set up a functional environment inside the chroot.

Why is it useless?  It sounds useful to me, on first glance.  If I want
to run a user-level network daemon I don't trust (for instance, fingerd),
isolating it in a chroot area sounds pretty nice: If there is a buffer
overrun in the daemon, you can get some protection [*] against the rest
of your system being trashed.  Am I missing something obvious?

[*] Yes, I know chroot is not sufficient on its own to completely
    protect against this, but it is a useful part of the puzzle, and
    there are other things we can do to deal with the remaining holes.