Re: [PATCH v5 next 1/5] modules:capabilities: add request_module_cap()

[Kees Cook <keescook@chromium.org>]

On Tue, Nov 28, 2017 at 11:14 AM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> kmod is just a helper to poke userpsace to load a module, that's it.
>
> The old init_module() and newer finit_module() do the real handy work or
> module loading, and both currently only use may_init_module():
>
> static int may_init_module(void)
> {
>         if (!capable(CAP_SYS_MODULE) || modules_disabled)
>                 return -EPERM;
>
>         return 0;
> }
>
> This begs the question:
>
>   o If userspace just tries to just use raw finit_module() do we want similar
>     checks?
>
> Otherwise, correct me if I'm wrong this all seems pointless.

Hm? That's direct-loading, not auto-loading. This series is only about
auto-loading.

We already have a global sysctl for blocking direct-loading (modules_disabled).

> If we want something similar I think we might need to be processing aliases and
> check for the aliases for their desired restrictions on finit_module(),

We don't need to handle aliases.

-Kees

-- 
Kees Cook
Pixel Security