Re: [PATCH RESEND/V2] crypto: Ignore validity dates of X.509 certificates at loading/parsing time

From: Rusty Russell
Date: Thu Jun 06 2013 - 23:03:27 EST

Alexander Holler <holler@xxxxxxxxxxxxx> writes:
> 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 <holler@xxxxxxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx
> 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:
> 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


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