linux-kernel - Re: Should we automatically generate a module signing key at all?

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Message-ID: <1432065634.3277.81.camel@infradead.org>
Date:	Tue, 19 May 2015 21:00:34 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	David Howells <dhowells@...hat.com>,
	Michal Marek <mmarek@...e.cz>,
	Abelardo Ricart III <aricart@...nix.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Sedat Dilek <sedat.dilek@...il.com>, keyrings@...ux-nfs.org,
	Rusty Russell <rusty@...tcorp.com.au>,
	LSM List <linux-security-module@...r.kernel.org>,
	Borislav Petkov <bp@...en8.de>, Jiri Kosina <jkosina@...e.cz>
Subject: Re: Should we automatically generate a module signing key at all?

On Tue, 2015-05-19 at 11:49 -0700, Andy Lutomirski wrote:
> 
> If we use hashes instead of signatures on in-tree modules (at least in
> the case where no long-term key is provided), then generation of the
> temporary signing key stops being an issue because there is no longer
> a temporary signing key.

With signatures I can make a one-line change to a module and rebuild it,
and still load it without having to rebuild my vmlinux to 'permit' it.

My signing key is valid for as long as I *choose* it to be valid.

I appreciate why that's a problem in your scenario, but it's a valid and
useful feature of signatures, and I don't think we can just abandon it.

-- 
dwmw2


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