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Date: Tue, 6 Nov 2012 15:06:57 +0100
From: Marcus Meissner <>
Subject: Re: Re: TTY handling when executing code in
	different lower-privileged context (su, virt containers)

On Wed, Nov 07, 2012 at 12:37:25AM +1100, David Black wrote:
> >In both cases, paranoid administrators might decide to use /dev/null
> >as stdin/stdout/stderr when just starting non-interactive programs in
> >different context, while they could replace the privileged shell with
> >exec when interactive context switch is needed (no shell, no escalation).
> >
> >Any opinions on that?
> >
> Perhaps if sudo/su determine if a user is running 'interactively' they
> could use a pseudo-pty ?

There were fixes released btw ...  (If we are talking about the same

SUSE at least did release fixes for the terminal character injection,
by opening a new session.

(CVE-2005-4890 is this whole issue I think.)

Ludwig Nussel tried to also use pseudo tty, but this gets kind of
messy soon, especially if you start with the signal handling required
(ctrl-z and ctrl-c over su are supposed to work...).

Fun enough, after release one of our customers reported to actually use
code like:

	su nobody -c "echo Test >/dev/tty" 

Ciao, Marcus

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