Messages in this thread |  | | From | "Albert D. Cahalan" <> | | Subject | Re: [PATCH] User chroot | | Date | Tue, 26 Jun 2001 23:32:59 -0400 (EDT) |
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H. Peter Anvin writes: > [somebody]
>> Have you ever wondered why normal users are not allowed to chroot? >> >> I have. The reasons I can figure out are: >> >> * Changing root makes it trivial to trick suid/sgid binaries to do >> nasty things. >> >> * If root calls chroot and changes uid, he expects that the process >> can not escape to the old root by calling chroot again. >> >> 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. In other > words, it's all pain, no gain.
Normal users can use an environment provided for them.
While trying to figure out why the "heyu" program would not work on a Red Hat box, I did just this. As root I set up all the device files needed, along Debian libraries and the heyu executable itself. It was annoying that I couldn't try out my chroot environment as a regular user.
Creating the device files isn't a big deal. It wouldn't be hard to write a setuid app to make the few needed devices. If we had per-user limits, "mount --bind /dev/zero /foo/zero" could be allowed. One way or another, devices can be provided.
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