From: Alexander Holler Subject: Re: [PATCH RESEND/V2] crypto: Ignore validity dates of X.509 certificates at loading/parsing time Date: Thu, 06 Jun 2013 13:17:23 +0200 Message-ID: <51B06FC3.8090405@ahsoftware.de> References: <1364409710-6458-1-git-send-email-holler@ahsoftware.de> <1367503746-6431-1-git-send-email-holler@ahsoftware.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, Herbert Xu , "David S. Miller" , Rusty Russell , David Howells , Josh Boyer , David Woodhouse To: Alexander Holler Return-path: Received: from h1446028.stratoserver.net ([85.214.92.142]:40992 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932627Ab3FFLSR (ORCPT ); Thu, 6 Jun 2013 07:18:17 -0400 In-Reply-To: <1367503746-6431-1-git-send-email-holler@ahsoftware.de> Sender: linux-crypto-owner@vger.kernel.org List-ID: Am 02.05.2013 16:09, schrieb Alexander Holler: > I don't see any real use case where checking the validity dates of X.509 > certificates at parsing time adds any security gain. In contrast, doing so > makes MODSIGN unusable on systems without a RTC (or systems with a possible > wrong date in a existing RTC, or systems where the RTC is read after the keys > got loaded). > > If something really cares about the dates, it should check them at the time > when the certificates are used, not when they are loaded and parsed. > > So just remove the validity check of the dates in the parser. > > Signed-off-by: Alexander Holler > Cc: stable@vger.kernel.org As it just happened to me again and I've recently posted some patches which do make it possible to experience the problem on x86 systems too, here is a reminder. To replay the problem (on x86 or any other arch), apply the 3 patches in this series: https://lkml.org/lkml/2013/6/5/430 build a kernel with CONFIG_MODULE_SIG_FORCE=y and start that kernel with hctosys=none as kernel command line parameter. This will disable the "persistent" clock (and any RTC), thus the kernel will refuse to load modules because it doesn't has a valid time when loading the certificate. Regards, Alexander Holler