Re: [PATCH 2/3] Security: Implement disablenetwork semantics. (v4)

From: Pavel Machek
Date: Thu Jan 14 2010 - 04:23:39 EST

> Quoting Michael Stone (michael@xxxxxxxxxx):
> > Serge Hallyn wrote:
> > >Michael, I'm sorry, I should go back and search the thread for the
> > >answer, but don't have time right now - do you really need
> > >disablenetwork to be available to unprivileged users?
> >
> > Rainbow can only drop the networking privileges when we know at app launch time
> > (e.g. based on a manifest or from the human operator) that privileges can be
> > dropped. Unfortunately, most of the really interesting uses of disablenetwork
> > happen *after* rainbow has dropped privilege and handed control the app.
> > Therefore, having an API which can be used by at least some low-privilege
> > processes is important to me.
> >
> > >is it ok to require CAP_SETPCAP (same thing required for dropping privs from
> > >bounding set)?
> >
> > Let me try to restate your idea:
> >
> > We can make disablenetwork safer by permitting its use only where explicitly
> > permitted by some previously privileged ancestor. The securebits facility
> > described in
> >
> >
> >
> > may be a good framework in which to implement this control.
> >
> > Did I understand correctly? If so, then yes, this approach seems like it would
> > work for me.
> That is a little more than I was saying this time though I think I
> suggested it earlier.
> But really I don't think anyone would care to separate a system into
> some processes allowed to do unprivileged disablenetwork and other
> processes not allowed to, so a (root-owned mode 644) sysctl seems just
> as useful.

Global solution like that is always wrong. (And we have better
solution available.)

(cesky, pictures)
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