Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755819AbbESRov (ORCPT ); Tue, 19 May 2015 13:44:51 -0400 Received: from mail-ie0-f180.google.com ([209.85.223.180]:34590 "EHLO mail-ie0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751261AbbESRor (ORCPT ); Tue, 19 May 2015 13:44:47 -0400 MIME-Version: 1.0 In-Reply-To: <555A88FB.7000809@kernel.org> References: <31154.1431965087@warthog.procyon.org.uk> <555A88FB.7000809@kernel.org> Date: Tue, 19 May 2015 10:44:47 -0700 X-Google-Sender-Auth: 0JDuzRraS1uEtIYI2do6dCzTGJI Message-ID: Subject: Re: Should we automatically generate a module signing key at all? From: Linus Torvalds To: Andy Lutomirski Cc: David Howells , Michal Marek , David Woodhouse , Abelardo Ricart III , Linux Kernel Mailing List , Sedat Dilek , keyrings@linux-nfs.org, Rusty Russell , LSM List , Borislav Petkov , Jiri Kosina Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1438 Lines: 30 On Mon, May 18, 2015 at 5:51 PM, Andy Lutomirski wrote: > > I think we should get rid of the idea of automatically generated signing > keys entirely. Instead I think we should generate, at build time, a list of > all the module hashes and link that into vmlinux. Ugh. I think that would be a mistake. It doesn't add any new security (it's 100% equivalent to just using a throw-away key), and it adds new complexity and a new ordering dependency. Yes, yes, "throwing away the key" is a somewhat gray area, and just unlinking the key-file without any secure erase in theory makes it recoverable. In practice, though, it is fine. If you have an attacker that has raw access to your disk and almost infinite resources, they have easier ways to make your life miserable. Even a non-secure unlinking of the temporary key file is going to make things like rootkit authors give up on trying to recover it. Really. So creating a whole new infrastructure that is more inconvenient than just key signing and cannot be used to handle cases that key signing *does* handle is definitely not worth it. It's technically the inferior solution, and it's more work. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/