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From:   Stephan Mueller <smueller@chronox.de>
To:     Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>, simo@redhat.com,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] crypto: drbg - update FIPS CTR self-checks to aes256
Date:   Mon, 30 Oct 2023 11:35:28 +0100
Message-ID: <1906073.RjUZ0rb3Up@tauon.chronox.de>
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References: <20231029204823.663930-1-dimitri.ledkov@canonical.com>
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Am Montag, 30. Oktober 2023, 11:30:32 CET schrieb Dimitri John Ledkov:

Hi Dimitri,

> On Mon, 30 Oct 2023 at 12:23, Stephan Mueller <smueller@chronox.de> wrote:
> > Am Sonntag, 29. Oktober 2023, 21:48:21 CET schrieb Dimitri John Ledkov:
> > 
> > Hi Dimitri,
> > 
> > > When originally drbg was introduced FIPS self-checks for all types but
> > > CTR were using the most preferred parameters for each type of
> > > DRBG. Update CTR self-check to use aes256.
> > > 
> > > Fixes: 541af946fe ("crypto: drbg - SP800-90A Deterministic Random Bit
> > > Generator") Signed-off-by: Dimitri John Ledkov
> > > <dimitri.ledkov@canonical.com>
> > > 
> > > 
> > > 
> > > ---
> > > 
> > >  crypto/drbg.c | 6 +++---
> > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/crypto/drbg.c b/crypto/drbg.c
> > > index 2cce18dcfc..b120e2866b 100644
> > > --- a/crypto/drbg.c
> > > +++ b/crypto/drbg.c
> > > @@ -1478,8 +1478,8 @@ static int drbg_generate(struct drbg_state *drbg,
> > > 
> > >                       err = alg_test("drbg_pr_hmac_sha256",
> > >                       
> > >                                      "drbg_pr_hmac_sha256", 0, 0);
> > >               
> > >               else if (drbg->core->flags & DRBG_CTR)
> > > 
> > > -                     err = alg_test("drbg_pr_ctr_aes128",
> > > -                                    "drbg_pr_ctr_aes128", 0, 0);
> > > +                     err = alg_test("drbg_pr_ctr_aes256",
> > > +                                    "drbg_pr_ctr_aes256", 0, 0);
> > > 
> > >               else
> > >               
> > >                       err = alg_test("drbg_pr_sha256",
> > >                       
> > >                                      "drbg_pr_sha256", 0, 0);
> > > 
> > > @@ -2017,7 +2017,7 @@ static inline int __init
> > > drbg_healthcheck_sanity(void) return 0;
> > > 
> > >  #ifdef CONFIG_CRYPTO_DRBG_CTR
> > > 
> > > -     drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
> > > +     drbg_convert_tfm_core("drbg_nopr_ctr_aes256", &coreref, &pr);
> > > 
> > >  #endif
> > >  #ifdef CONFIG_CRYPTO_DRBG_HASH
> > >  
> > >       drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
> > 
> > I am not sure again whether this warrants a "Fixes" tag, because the first
> > modification is in a commented-out code section and the latter again
> > intends to test the DRBG thresholds and thus just needs "a" DRBG.
> 
> Agreed, it is more of a reference. But yes, I don't believe this needs
> to trigger stable backports - because yes it is like dead code, or
> fips only code which majority kernels don't do. Maybe I should
> reference that commit in description only?

I think this would be good to avoid the need to trigger backports for this 
"trivial" patch.

Thanks a lot.
> 
> > Anyhow:
> > 
> > Reviewed-by: Stephan Mueller <smueller@chronox.de>
> > 
> > 
> > Ciao
> > Stephan


Ciao
Stephan