Re: taskstats root only breaking iotop

From: Vasiliy Kulikov
Date: Tue Oct 04 2011 - 09:32:34 EST

On Mon, Oct 03, 2011 at 15:31 +0300, Adrian Bunk wrote:
> On Sun, Oct 02, 2011 at 02:54:57PM +0400, Vasiliy Kulikov wrote:
> > (cc'ed kernel-hardening)
> >
> > On Sun, Oct 02, 2011 at 12:22 +0200, Guillaume Chazarain wrote:
> > > On Sun, Oct 2, 2011 at 2:20 AM, Linus Torvalds
> > > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> > > > So I don't see why you ask for it. What could possibly be a valid use-case?
> > >
> > > Right, kbyte granularity is enough.
> >
> > It is not enough. In some border cases an attacker may still learn
> > private information given the counters with _arbitrary_ granularity:
> >
> >
> If you request a CVE for that, shouldn't there also be a CVE for
> /proc/<pid>/cmdline being readable by all users?
> I'd expect "ps -ef" to be more likely to give private information to an
> attacker than counters with kbyte granularity, or am I wrong on that?

I agree that world-readable cmdline can be a privacy issue in some
cases. I tried to push a patch introducing procfs mount option to
restrict /proc/PID/ to PID owner to address the issue (as world-readable
cmdline and other files are already used by plenty of programs and
unconditionally breaking backward compatibility is not good, a
configuration mechanism is needed), but it didn't receive positive
feedback. A more detailed explanation from Solar Designer:

Andrew Morton complained that it is too specific to our needs and one
might want to define more fine granted procfs security model:

I've tried to address it and defined per-file policy:

No comments so far :(

Vasiliy Kulikov - bringing security into open computing environments
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