linux-kernel - Re: [PULL] modules-next

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Message-ID: <87shuoxc7t.fsf@rustcorp.com.au>
Date:	Tue, 02 Aug 2016 09:40:14 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Ben Hutchings <ben@...adent.org.uk>,
	Jessica Yu <jeyu@...hat.com>, Jiri Kosina <jkosina@...e.cz>,
	Kees Cook <keescook@...omium.org>,
	Libor Pechacek <lpechacek@...e.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Prarit Bhargava <prarit@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PULL] modules-next

Linus Torvalds <torvalds@...ux-foundation.org> writes:
> So this feels wrong to me, can you guys please explain:
>
> On Sun, Jul 31, 2016 at 9:02 PM, Rusty Russell <rusty@...tcorp.com.au> wrote:
>>
>> Ben Hutchings (3):
>>       module: Invalidate signatures on force-loaded modules
>>       module: Disable MODULE_FORCE_LOAD when MODULE_SIG_FORCE is enabled
>
> forcing a load and SIG_FORCE are entirely independent issues, afaik. I
> think requiring signed modules is just a good idea. But that doesn't
> necessarily mean that you don't have a signed module that is signed
> with a key you trust, but you still want to force-load it for the
> wrong kernel version (ie maybe you have a binary-only module from your
> IT department (and your IT department is evil,but at least they sign
> it to show that the module is trust-worthy as coming from them, even
> if they have some dubious behavior), but you did some kernel updates
> that still allow the module to work but the version doesn't match any
> more).
>
> Am I missing something? What's the connection between
> MODULE_FORCE_LOAD and MODULE_SIG_FORCE? Because it smells like they
> are independent and that the above changes are very very dubious.
>
> I didn't actually pull the tree, I just reacted to the pull request itself.

Well, MODULE_FORCE_LOAD is really "I am a doing crazy shit", and
MODULE_SIG_FORCE is "Don't let me do crazy shit".

You have to contrive pretty hard to get a situation where the
combination makes sense, so I tend to let Ben worry about the module
signing stuff.

I can pull them out of modules-next if you'd prefer.

Cheers,
Rusty.