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Date:      Mon, 12 Feb 2001 10:50:20 -0500 (EST)
From:      Robert Watson <rwatson@freebsd.org>
To:        Lists Account <lists@security.za.net>
Cc:        hackers@freebsd.org
Subject:   Re: Jail Pseudo Terminals 
Message-ID:  <Pine.NEB.3.96L.1010212104522.88322B-100000@fledge.watson.org>
In-Reply-To: <Pine.BSF.4.21.0102121540560.80066-100000@security.za.net>

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On Mon, 12 Feb 2001, Lists Account wrote:

> Just a quick question Im hoping someone can help me with.  I extended
> the number of pty's available on my base box just fine, with an edit to
> /etc/ttys and making some new devices, then just a kill -1 1, and
> everything worked fine. 
> 
> I did exactly the same thing under the jail, it didnt work, rebooted the
> box and it still didnt work, does anyone know how to extend the number
> of pty's under a jail?  Any help would be MUCH appreciated

Hmm.  What do you mean by, ``I did exactly the same thing under the jail''
-- the mknod() syscall for device nodes is unavailable under jail() so as
to prevent the creation of inappropriate devices that might allow the
attacker to circumvent the jail() protections.  So there are two things
you could have done: (1) used MAKEDEV under jail(), and either it didn't
generate appropriate error messages, or you missed them, and you should be
running the MAKEDEV in the per-jail /dev directory, but not from within
the jail(), or (2) you ran MAKEDEV outside the jail, and something else is
broken.  My first guess would be that you did (1), and running MAKEDEV
outside of a jail() process but in the jail() /dev will fix things. 

Also, generally speaking, pty's are not managed by init, rather, they are
dynamically allocated using openpty(), so you shouldn't need to HUP init,
or even modify /etc/ttys.  In fact, from within a jail(), you should be
unable to successfully HUP the pid 1 init process. 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Project
robert@fledge.watson.org      NAI Labs, Safeport Network Services




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