linux-kernel - Re: [PATCH v5 next 2/5] modules:capabilities: add cap_kernel_module

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Date:   Thu, 30 Nov 2017 03:05:58 +0100
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Djalal Harouni <tixxdz@...il.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Andy Lutomirski <luto@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        James Morris <james.l.morris@...cle.com>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        Solar Designer <solar@...nwall.com>,
        Serge Hallyn <serge@...lyn.com>, Jessica Yu <jeyu@...nel.org>,
        Rusty Russell <rusty@...tcorp.com.au>,
        linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        kernel-hardening@...ts.openwall.com,
        Jonathan Corbet <corbet@....net>,
        Ingo Molnar <mingo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v5 next 2/5] modules:capabilities: add
 cap_kernel_module_request() permission check

On Mon, Nov 27, 2017 at 06:18:35PM +0100, Djalal Harouni wrote:
> +/* Determine whether a module auto-load operation is permitted. */
> +int may_autoload_module(char *kmod_name, int required_cap,
> +			const char *kmod_prefix);
> +

While we are reviewing a general LSM for this, it has me wondering if an LSM or
userspace feed info may every want to use other possible context we could add for
free to make a determination.

For instance since all request_module() calls are in header files, we could 
for add for free THIS_MODULE as context to may_autoload_module() as well, so
struct module. The LSM could in theory then also help ensure only specific
modules are allowed to request a module load. Perhaps userspace could say
only built-in code could request certain modules.

Just a thought.

  Luis