linux-kernel - MODSIGN without RTC?

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Message-ID: <5112EA69.6010100@ahsoftware.de>
Date:	Thu, 07 Feb 2013 00:42:33 +0100
From:	Alexander Holler <holler@...oftware.de>
To:	linux-kernel@...r.kernel.org
Subject: MODSIGN without RTC?

Hello,

I wanted to try out MODSIGN with kernel 3.7.6 and I've just got hit by:

[    1.346445] X.509: Cert 6a23533cec71c4c52a1618fb4d830e06aa90474e is 
not yet valid

The reason is likely that the (ARM) device in question doesn't have a 
RTC (oh, that topic again ;) ) and gets it's time on boot through NTP.

The used certificate was generated automatically. Having a look at it, 
the following is shown:

        Validity
             Not Before: Feb  6 02:56:46 2013 GMT
             Not After : Jan 13 02:56:46 2113 GMT

Without having thought about possible security problems, my first idea 
would be to let the validity start at 1970. As I never did such I never 
had thought about possible implications when doing such (e.g. I don't 
know if someone checks the start date for plausabilitiy)

Another solution would be to retry loading of the certificate if the 
time gets set (and e.g. differs more than a year).

Has someone already thought about how to solve that problem? Or did 
everyone use sane systems which have a (working) RTC?

Regards,

Alexander
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