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To: daw@mozart.cs.berkeley.edu (David Wagner)
Cc: linux-kernel@vger.kernel.org
Reply-To: linux-kernel@vger.kernel.org
Subject: Re: can chroot be made safe for non-root?
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	<aokl28$955$2@abraham.cs.berkeley.edu>
From: Philippe Troin <phil@fifi.org>
Date: 16 Oct 2002 15:04:11 -0700
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daw@mozart.cs.berkeley.edu (David Wagner) writes:

> Philippe Troin  wrote:
> >Eric Buddington <eric@ma-northadams1b-3.bur.adelphia.net> writes:
> >> Would it be reasonable to allow non-root processes to chroot(), if the
> >> chroot syscall also changed the cwd for non-root processes?
> >
> >No.
> >
> >  fd = open("/", O_RDONLY);
> >  chroot("/tmp");
> >  fchdir(fd);
> >
> >and you're out of the chroot.
> 
> Irrelevant.  If a process *wants* to voluntarily sandbox itself, it can
> close all open file descriptors before sandboxing.

You missed the point.

If the process can be forced to run the above (possibly via a stack
overflow), then it is out of the chroot.

Phil.
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