Re: [PATCH try #2] security: Convert LSM into a static interface

[Adrian Bunk <bunk@stusta.de>]

On Tue, Jun 26, 2007 at 09:06:44AM -0500, Serge E. Hallyn wrote:
> Quoting Adrian Bunk (bunk@stusta.de):
> > On Mon, Jun 25, 2007 at 10:57:31PM -0500, Serge E. Hallyn wrote:
> > > Quoting James Morris (jmorris@namei.org):
> > > > On Mon, 25 Jun 2007, Andreas Gruenbacher wrote:
> > > > 
> > > > > It's useful for some LSMs to be modular, and LSMs which are y/n options won't 
> > > > > have any security architecture issues with unloading at all. 
> > > > 
> > > > Which LSMs?  Upstream, there are SELinux and capabilty, and they're not 
> > > > safe as loadable modules.
> > > > 
> > > > > The mere fact 
> > > > > that SELinux cannot be built as a module is a rather weak argument for 
> > > > > disabling LSM modules as a whole, so  please don't.
> > > > 
> > > > That's not the argument.  Please review the thread.
> > > 
> > > The argument is 'abuse', right?
> > > 
> > > Abuse is defined as using the LSM hooks for non-security applications,
> > > right?
> > > 
> > > It seems to me that the community is doing a good job of discouraging
> > > such abuse - by redirecting the "wrong-doers" to implement proper
> > > upstream solutions, i.e. taskstats, the audit subsystem, etc.
> > > 
> > > Such encouragement seems a far better response than taking away freedoms
> > > and flexibility from everyone.
> > 
> > We are not living in a world where everyone had good intentions...
> 
> Oh no, i took a wrong turn somewhere  :)
> 
> > For _some_ "wrong-doers" your approach works.
> > 
> > But how do you convince the "wrong-doers" who do things like putting 
> > MODULE_LICENSE("GPL") into their binary-only modules and who ignore you 
> > and get away because noone sues them?
> 
> Do these really exist?  Maybe noone sues them because noone knows who
> they are...

   http://lwn.net/Articles/82306/

> But - note that you've changed completely the meaning of 'abuse'.
> So mine was wrong?

Technical and legal abuse are related.

For GPL'ed modules you might assume good faith and get the authors to do 
things in a proper way. Authors of legally questionable modules that 
cheat in many ways are quite a different issue.

> > The spirit of the GPLv2 is to defend the freedom of the software 
> > (different from the spirit of the BSD licence), and considering that 
> > there aren't many people defending the GPLv2 copyright of the Linux 
> > kernel at court against abusers, making it harder for people to do the 
> > abuse might not be the worst choice...
> 
> Well, but you seem to be saying that the license means squat, and
> resorting to making things inconvenient rather than illegal.

No, the point is that there's no reason for making illegal things 
convenient.

I'm not talking about removing things that are used inside the kernel, 
but what you call "freedom" can also be called "hooks for possible abuse".

Additionally, it both makes the kernel bigger for everyone and requires 
proper handling of loading/unloading in the security architecture.

> Now I guess if it really is accepted that that's the way it should be,
> then this patch will go in.
> 
> -serge

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed