Re: access to proc filesystem from chrooted process

Andreas Bombe (andreas.bombe@munich.netsurf.de)
Sat, 22 May 1999 18:41:17 +0200

On Fri, May 21, 1999 at 07:23:30PM +0100, Peter Benie wrote:
> Riley Williams writes ("Re: access to proc filesystem from chrooted process"):
> > Unless I'm misunderstanding this, it appears to be pointless since
> > only processes chroot'd to / or /proc could see the entries in the
> > proc file system anyway, as if they're chroot'd anywhere else, they
> > can't even access /proc ???
>
> If you are setting up a server with a chrooted environment for users,
> it is useful to have /proc mounted inside the chroot so that programs
> like top and ps can work, so yes, users can get at /proc.

But then you have to be careful if you use that as a security
enhancement. Programs that are suid root can break out of their chroot
by cd'ing to /proc/1/root. If the user for some reason gets a program
to run outside of the chroot with his uid, they can break out without
suid by using this program's proc entry.

-- 
    Andreas E. Bombe <andreas.bombe@munich.netsurf.de>
    http://home.pages.de/~andreas.bombe/
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