Am 07.02.2013 08:01, schrieb Alexander Holler:
Am 07.02.2013 07:42, schrieb Geert Uytterhoeven:
On Thu, Feb 7, 2013 at 2:06 AM, Alexander Holler <hol...@ahsoftware.de> wrote:
Am 07.02.2013 00:42, schrieb Alexander Holler:
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?
Another option would be to make a configure option to just ignore the date.
Or an option to auto-advance the clock to the "Not Before" date if needed...
I'm not sure if I would like to use MODSIGN when I have to fear that the
machine wouldn't start when the RTC fails or got set to a wrong date.
Hmm, nice failure mode...
And the dream of every vendor, finally a working expiration date. And a
nice TV-B-Gone, just feed a wrong date once. ;)
I've digged a bit around about how to disable the date check, but then
decided that I shouldn't try to implement that
(CONFIG_MODSIGN_IGNORE_DATES) because of missing knowledge about the
(usage of) crypto-api.
I think adding attributes to the key and the parsed key like bool
ingore_dates and bool parsed_dates_invalid might be an option. Using
such x509_key_preparse() could just set parsed_dates_invalid instead of
returning with -EKEYREJECTED or -EKEYEXPIRED, if it encounters invalid
dates.
Regards,
Alexander
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