Re: [PATCH v13 0/9] LSM: Multiple concurrent LSMs

From: Paul Moore
Date: Thu Apr 25 2013 - 11:07:12 EST


On Wednesday, April 24, 2013 05:43:08 PM Casey Schaufler wrote:
> On 4/24/2013 4:00 PM, John Johansen wrote:
> > On 04/24/2013 02:15 PM, Paul Moore wrote:
> >> On Wednesday, April 24, 2013 01:22:20 PM Casey Schaufler wrote:

...

> >>> An interesting aside that may be relevant is that the error
> >>> condition behavior makes it advisable to have the LSM you care
> >>> about most go last. If the networking components were strictly
> >>> FCFS you might have to chose an ordering you might not want for
> >>> other reasons.
> >>
> >> Well, maybe not ... I think. If we take a FCFS approach to the network
> >> controls then only one LSM is really ever going to throw an error on the
> >> network hooks, yes?
>
> You set up the order you want to get the networking handled
> correctly and you could get filesystem hooks in the wrong order.
> Not that that really ought to be a problem, but there are wonky
> admin tools out there.

I don't quite follow; can you be a bit more explicit about getting the
filesystem hooks in the wrong order?

> >> I'm still in favor of assigning the network hooks to the LSM at boot
> >> based on the "security=" configuration.
> >
> > yeah dealing with selection at boot time is going to be needed
> > at some point, whether its now or later ...
>
> I'll have a go at it then. What that would mean is that:
>
> security=smack,selinux
>
> gives Smack NetLabel and SELinux xfrm and secmark while
>
> security=selinux,smack
>
> gives SELinux all three.

That seems reasonable, it also keeps the door open for adding a specific
network hook ordering option, e.g. "security_net=", at a later date if
necessary.

> I would still like it to be possible to explicitly configure the allocation
> at build time.

I suppose I have no object to that, I would just place my vote to have the
dynamic FCFS (or LCFS if that makes more sense) assignment be the Kconfig
default.

--
paul moore
www.paul-moore.com

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