Re: request_module vs. modprobe blacklist (and security subsystem implications)

[Rusty Russell <rusty@rustcorp.com.au>]

On Sat, 24 Oct 2009 12:53:50 am Eric Paris wrote:
> On Fri, 2009-10-23 at 19:46 +1030, Rusty Russell wrote:
> > On Fri, 23 Oct 2009 01:00:22 am Eric Paris wrote:
> > > > If a userspace program tries some security exploit that has been closed, do
> > > > you want to warn about it?  Because that seems to be the question here.
> > > 
> > > I say yes.  Knowing that malicious activity is taking place, even if it
> > > didn't hurt anything is useful.
> > 
> > Hi Eric,
> > 
> > Your proposal is troubling for three reasons:
> > 
> > 1) You would disable logging for things you actually want logged.
> 
> I would?

Yep, admin disables loading of ipx to prevent hole.  Now, you no longer get
logging notification.

> > 2) What *actually* happens when ssh tries to load ipv6 is that
> >    "modprobe net-pf-10" gets called.
> > 3) Containing modprobe behavior in one set of config files is really nice.
> 
> It is it also means that we, somewhat regularly call userspace
> needlessly and there is nothing an admin can do to stop it.

Yes, but that's nothing to do with SELinux; we exec modprobe for no effect.
Yet I've yet to see a report that this is a performance issue.  These brains
are in userspace for a reason.

> But it appears you disagree that fixing that problem is worth it, and I
> don't feel strongly enough to keep arguing  :)

But we have learnt something, at least!

Cheers,
Rusty.