Re: [PATCH v24 11/12] LRNG - add SP800-90B compliant health tests

[Stephan Müller]

Am Mittwoch, 13. November 2019, 07:02:40 CET schrieb Alexander E. Patrakov:

Hi Alexander,

> ÑÑ, 13 ÐÐÑÐ. 2019 Ð. Ð 05:38, Stephan MÃller <smueller@xxxxxxxxxx>:
> > Am Dienstag, 12. November 2019, 20:58:32 CET schrieb Alexander E.
> > Patrakov:
> > 
> > Hi Alexander,
> > 
> > > > +config LRNG_HEALTH_TESTS
> > > > +   bool "Enable noise source online health tests"
> > > > +   help
> > > > +     The online health tests validate the noise source at
> > > > +     runtime for fatal errors. These tests include SP800-90B
> > > > +     compliant tests which are invoked if the system is booted
> > > > +     with fips=1. In case of fatal errors during active
> > > > +     SP800-90B tests, the issue is logged and the noise
> > > > +     data is discarded. These tests are required for full
> > > > +     compliance with SP800-90B.
> > > 
> > > How have you tested that these tests work at runtime? Maybe add some
> > > code under a new CONFIG item that depends on CONFIG_BROKEN that
> > > deliberately botches the RNG and triggers failures?
> > 
> > I am unable to find sensible information about CONFIG_BROKEN in the recent
> > kernel tree.
> > 
> > Do you happen to have a pointer on how that option is to be used?
> 
> This option is not used on its own. You create a new option,
> CONFIG_TEST_LRNG_FAILURE_MODE or something like that, and put your
> code under the ifdef guarded by that option. And then, to prevent
> ordinary users and allyesconfig from selecting it, in Kconfig you say:
> "depends on BROKEN". This way, the option becomes unselectable in
> menuconfig but still works as intended when added manually to .config
> (obviously, with the BROKEN dependency removed locally).
> 
> Definition:
> https://github.com/torvalds/linux/blob/9c7db5004280767566e91a33445bf93aa479
> ef02/init/Kconfig#L68 Example usage:
> https://github.com/torvalds/linux/blob/c87237110f2553b4200a8b3401a01198edfc
> f0d9/drivers/gpu/drm/i915/Kconfig.debug#L166

I added such support to the LRNG.

Thank you for your suggestion.
> 
> --
> Alexander E. Patrakov


Ciao
Stephan