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

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Message-ID: <555C3B99.4000000@suse.cz>
Date:	Wed, 20 May 2015 15:45:29 +0800
From:	Michal Marek <mmarek@...e.cz>
To:	Jiri Kosina <jkosina@...e.cz>, David Howells <dhowells@...hat.com>
CC:	Theodore Ts'o <tytso@....edu>,
	Andy Lutomirski <luto@...capital.net>,
	Andy Lutomirski <luto@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Woodhouse <dwmw2@...radead.org>,
	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>
Subject: Re: Should we automatically generate a module signing key at all?

Dne 20.5.2015 v 05:47 Jiri Kosina napsal(a):
> On Tue, 19 May 2015, David Howells wrote:
> 
>> That wouldn't very convenient for building our kernels in our build farm 
>> - we have a lot of machines and all of them would have to be equiped 
>> with the key.  Besides, we *want* to discard the private key where 
>> possible as soon as possible because then we can't leak it and we can't 
>> be forced to disclose it.
> 
> You can still have a dedicated machine that's used just for signing the 
> binaries. That machine wouldn't be connected to the network, would be 
> physically secured, and would sign through a serial line or so.

Right, that's what CONFIG_MODULE_SIG_ALL=n is meant for -- build the
public key into the kernel, but sign the modules later, outside of the
build system. So you still have to trust the build machine to build what
you ask it to build, but you do not have to trust it not to leak your
private key.

Michal
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