[RFC] Turn lockdown into an LSM

[James Morris]

On Tue, 21 May 2019, Matthew Garrett wrote:

> Hi James,
> 
> This is a quick attempt to integrate lockdown into the existing LSM
> framework. It adds a new lockdown security hook and an LSM that defines
> the existing coarse-grained policy, and also adds a new
> DEFINE_EARLY_LSM() definition in order to permit lockdown (and
> potentially other modules) to be initialised at the top of kernel init
> in order to allow policy to be imposed on stuff that happens in
> setup_arch(). The goal here is to allow policy to be devolved to other
> LSMs on systems that have a secure mechanism for loading LSM policy
> early in boot, allowing creation of arbitrarily complicated policies
> without interfering with the common-case coarse-grained approach.
> 
> This should probably be extended so a uapi-exposed constant is passed to
> the hook in order to make it easier to write policy in other LSMs, but
> does this broadly look like you were imagining?

This looks promising!

An LSM could also potentially implement its own policy for the hook.

-- 
James Morris
<jmorris at namei.org>