Re: [kernel-hardening] [PATCH v4 next 0/3] modules: automatic module loading restrictions

[Kees Cook]

On Tue, May 23, 2017 at 12:48 AM, Solar Designer <solar@xxxxxxxxxxxx> wrote:
> For modules_autoload_mode=2, we already seem to have the equivalent of
> modprobe=/bin/true (or does it differ subtly, maybe in return values?),
> which I already use at startup on a GPU box like this (preloading
> modules so that the OpenCL backends wouldn't need the autoloading):
>
> nvidia-smi
> nvidia-modprobe -u -c=0
> #modprobe nvidia_uvm
> #modprobe fglrx
>
> sysctl -w kernel.modprobe=/bin/true
> sysctl -w kernel.hotplug=/bin/true
>
> but it's good to also have this supported more explicitly and more
> consistently through modules_autoload_mode=2 while we're at it.  So I
> support having this mode as well.  I just question the need to have it
> non-resettable.

I agree it's useful to have the explicit =2 state just to avoid
confusion when more systems start implementing
CONFIG_STATIC_USERMODEHELPER and kernel.modprobe becomes read-only
(though the userspace implementation may allow for some way to disable
it, etc). I just like avoiding the upcall to modprobe at all.

-Kees

-- 
Kees Cook
Pixel Security