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

[James Morris]

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@xxxxxxxxx>
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