Messages in this thread | | | Date | Mon, 7 Feb 2011 20:27:08 -0800 | From | Kees Cook <> | Subject | Re: [SECURITY] /proc/$pid/ leaks contents across setuid exec |
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On Tue, Feb 08, 2011 at 02:43:15PM +1100, James Morris wrote: > On Mon, 7 Feb 2011, Kees Cook wrote: > > Sure, I know about O_CLOEXEC, but this is about protecting the > > just-been-execed setuid process from the attacking process that has no > > reason to set O_CLOEXEC. > > > > Something like this needs to be enforced on the kernel side. I.e. these > > file in /proc need to have O_CLOEXEC set in a way that cannot be unset. > > > > > Changing the behavior in the core kernel will break userspace. > > > > I don't think /proc/$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.
Right, that's precisely the problem. The unprivileged process can read the setuid process's /proc files.
-Kees
-- Kees Cook Ubuntu Security Team
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