linux-kernel - Re: [SECURITY] /proc/$pid/ leaks contents across setuid exec

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Message-ID: <alpine.LRH.2.00.1102081437430.3879@tundra.namei.org>
Date:	Tue, 8 Feb 2011 14:43:15 +1100 (EST)
From:	James Morris <jmorris@...ei.org>
To:	Kees Cook <kees.cook@...onical.com>
cc:	linux-kernel@...r.kernel.org, Al Viro <viro@....linux.org.uk>
Subject: Re: [SECURITY] /proc/$pid/ leaks contents across setuid exec

On Mon, 7 Feb 2011, Kees Cook wrote:

> Sure, I know about O_CLOEXEC, but this is about protecting the
> just-been-execed setuid process from the attacking process that has no
> reason to set O_CLOEXEC.
> 
> Something like this needs to be enforced on the kernel side. I.e. these
> file in /proc need to have O_CLOEXEC set in a way that cannot be unset.
> 
> > Changing the behavior in the core kernel will break userspace.
> 
> I don't think /proc/$pid/* needs to stay open across execs, does it? Or at
> least the non-0444 files should be handled separately.

Actually, this seems like a more general kind of bug in proc rather than a 
leaked fd.  Each child task should only see its own /proc/[pid] data.



- James
-- 
James Morris
<jmorris@...ei.org>
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