linux-kernel - Re: [RFC] Expose request

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Date:   Wed, 15 Sep 2021 18:02:49 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Thomas Weißschuh <thomas@...ch.de>
Cc:     linux-api@...r.kernel.org, linux-kernel@...r.kernel.org,
        Luis Chamberlain <mcgrof@...nel.org>,
        Jessica Yu <jeyu@...nel.org>
Subject: Re: [RFC] Expose request_module via syscall

On Wed, Sep 15, 2021 at 05:49:34PM +0200, Thomas Weißschuh wrote:
> Hi,
> 
> I would like to propose a new syscall that exposes the functionality of
> request_module() to userspace.
> 
> Propsed signature: request_module(char *module_name, char **args, int flags);
> Where args and flags have to be NULL and 0 for the time being.
> 
> Rationale:
> 
> We are using nested, privileged containers which are loading kernel modules.
> Currently we have to always pass around the contents of /lib/modules from the
> root namespace which contains the modules.
> (Also the containers need to have userspace components for moduleloading
> installed)
> 
> The syscall would remove the need for this bookkeeping work.

So you want any container to have the ability to "bust through" the
containers and load a module from the "root" of the system?

That feels dangerous, why not just allow a mount of /lib/modules into
the containers that you want to be able to load a module?

Why are modules somehow "special" here, they are just a resource that
has to be allowed (or not) to be accessed by a container like anything
else on a filesystem.

thanks,

greg k-h