Re: Linux Security *Module* Framework (Was: LSM conversion tostatic interface)

From: Arjan van de Ven
Date: Mon Oct 29 2007 - 01:17:28 EST


On Sun, 28 Oct 2007 15:08:56 -0700
Crispin Cowan <crispin@xxxxxxxxxxxxxxxx> wrote:

> To reject an LSM for providing "bad" security, IMHO you should have to
> show how it is possible to subvert the self-stated goals of that LSM.
> Complaints that the LSM fails to meet some goal outside of its stated
> purpose is irrelevant. Conjecture that it probably can be violated
> because of $contrivance is just so much FUD.

exactly; this is why I've been pushing recently for each new LSM to at
least document and make explicit what it tries to protect / protect
against (threat model and defense model in traditional security terms).
Without such an explicit description it's both impossible to
"neutrally" review a proposed LSM towards its goals, and it ends up as
a result with people making assumptions and attacking the model because
there's no separation between code and model.


> Exception: it is valid to say that the self-stated goal is too narrow
> to be useful. But IMHO that bar of "too narrow" should be very, very
> low. Defenses against specific modes of attack would be a fine thing
> to build up in the library of LSMs, especially if we got a decent
> stacking module so that they could be composed.

again I agree pretty much; I do want to reserve some minimum "common
sense" bar because people may (and probably will) do silly things withs
LSMs that are really not the right thing to do objectively.


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