Re: [PATCH v4.19.y, v4.14.y, v4.9.y] crypto: drbg - add FIPS 140-2 CTRNG for noise source

[Greg KH <gregkh@linuxfoundation.org>]

On Sat, Feb 29, 2020 at 10:01:49AM +0000, Vikash Bansal wrote:
> 
> On 27/02/20, 12:30 PM, "Greg KH" <gregkh@linuxfoundation.org> wrote:
> 
>     
> > On Thu, Feb 27, 2020 at 05:58:05AM +0000, Vikash Bansal wrote:
> >> From: Stephan Mueller <smueller@chronox.de>
> >>
> >> commit db07cd26ac6a418dc2823187958edcfdb415fa83 upstream
> >>
> >> FIPS 140-2 section 4.9.2 requires a continuous self test of the noise
> >> source. Up to kernel 4.8 drivers/char/random.c provided this continuous
> >> self test. Afterwards it was moved to a location that is inconsistent
> >> with the FIPS 140-2 requirements. The relevant patch was
> >> e192be9d9a30555aae2ca1dc3aad37cba484cd4a .
> >>
> >> Thus, the FIPS 140-2 CTRNG is added to the DRBG when it obtains the
> >> seed. This patch resurrects the function drbg_fips_continous_test that
> >> existed some time ago and applies it to the noise sources. The patch
> >> that removed the drbg_fips_continous_test was
> >> b3614763059b82c26bdd02ffcb1c016c1132aad0 .
> >>
> >> The Jitter RNG implements its own FIPS 140-2 self test and thus does not
> >> need to be subjected to the test in the DRBG.
> >>
> >> The patch contains a tiny fix to ensure proper zeroization in case of an
> >> error during the Jitter RNG data gathering.
> >>
> >> Signed-off-by: Stephan Mueller <smueller@chronox.de>
> >> Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
> >> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
> >> Signed-off-by: Vikash Bansal <bvikas@vmware.com>
> >> ---
> >>  crypto/drbg.c         | 94 +++++++++++++++++++++++++++++++++++++++++--
> >>  include/crypto/drbg.h |  2 +
> >>  2 files changed, 93 insertions(+), 3 deletions(-)
> >    
> > This looks like a new feature to me, why is it needed in the stable
> > kernel trees?  What bug does it fix?
> 
> In 4.19.y, 4.14.y & 4.9.y, DRBG implementation is as per NIST recommendation
> defined in NIST SP800-9A and it designed to be ready for FIPS certification.
> But it has missed one of the NIST test requirement define in FIPS 140-2(4.9.2),
> so it is not ready for NIST FIPS certification.
> With this patch FIPS 140-2(4.9.2) continuous test requirement will be fulfilled.

Then use 5.4 or newer kernels if you need such a certification.  Adding
this new feature to older kernels is just that, a new feature.

What is preventing you from using 5.4?  It's much better security wise
than older kernels for a whole load of reasons.

thanks,

greg k-h