linux-kernel - Re: Per-process flag set via prctl() to deny module loading?

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Message-ID: <2023041010-vacation-scribble-ba46@gregkh>
Date:   Mon, 10 Apr 2023 20:37:06 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Topi Miettinen <toiwoton@...il.com>
Cc:     linux-modules <linux-modules@...r.kernel.org>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Per-process flag set via prctl() to deny module loading?

On Mon, Apr 10, 2023 at 01:06:00PM +0300, Topi Miettinen wrote:
> I'd propose to add a per-process flag to irrevocably deny any loading of
> kernel modules for the process and its children. The flag could be set (but
> not unset) via prctl() and for unprivileged processes, only when
> NoNewPrivileges is also set. This would be similar to CAP_SYS_MODULE, but
> unlike capabilities, there would be no issues with namespaces since the flag
> isn't namespaced.
> 
> The implementation should be very simple.

Patches are always welcome to be reviewed.

But note, please watch out for processes that cause devices to be found,
and then modules to be loaded that way, it's not going to be as simple
as you might have imagined...

thanks,

greg k-h