linux-kernel - Re: [PATCH 2/4] crypto: drbg - update FIPS CTR self-checks to aes256

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Message-ID: <CADWks+Z0b8GPSg37=TQK_5LqVejC_CzbOxn_TUsvkQ45TOyuYw@mail.gmail.com>
Date:   Mon, 30 Oct 2023 12:30:32 +0200
From:   Dimitri John Ledkov <dimitri.ledkov@...onical.com>
To:     Stephan Mueller <smueller@...onox.de>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>, simo@...hat.com,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] crypto: drbg - update FIPS CTR self-checks to aes256

On Mon, 30 Oct 2023 at 12:23, Stephan Mueller <smueller@...onox.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@...onical.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?

> Anyhow:
>
> Reviewed-by: Stephan Mueller <smueller@...onox.de>
>
>
> Ciao
> Stephan
>
>

-- 
okurrr,

Dimitri