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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Tue, 20 Aug 2019 13:57:00 +0300
Message-ID: <CAKv+Gu9Z=qkEVpkQYsCy5Q_EvMuQ1KzPVataWs+x4vhS_wB27Q@mail.gmail.com>
Subject: Re: [PATCH 2/2] crypto: s5p - use correct block size of 1 for ctr(aes)
To:     Krzysztof Kozlowski <krzk@kernel.org>
Cc:     "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@vger.kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Vladimir Zapolskiy <vz@mleia.com>,
        Kamil Konieczny <k.konieczny@partner.samsung.com>,
        "linux-samsung-soc@vger.kernel.org" 
        <linux-samsung-soc@vger.kernel.org>
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On Tue, 20 Aug 2019 at 13:24, Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On Mon, 19 Aug 2019 at 16:24, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> >
> > Align the s5p ctr(aes) implementation with other implementations
> > of the same mode, by setting the block size to 1.
> >
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > ---
> >  drivers/crypto/s5p-sss.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c
> > index ef90c58edb1f..010f1bb20dad 100644
> > --- a/drivers/crypto/s5p-sss.c
> > +++ b/drivers/crypto/s5p-sss.c
> > @@ -2173,7 +2173,7 @@ static struct crypto_alg algs[] = {
> >                 .cra_flags              = CRYPTO_ALG_TYPE_ABLKCIPHER |
> >                                           CRYPTO_ALG_ASYNC |
> >                                           CRYPTO_ALG_KERN_DRIVER_ONLY,
> > -               .cra_blocksize          = AES_BLOCK_SIZE,
> > +               .cra_blocksize          = 1,
>
> This makes sense but I wonder how does it work later with
> s5p_aes_crypt() and its check for request length alignment
> (AES_BLOCK_SIZE). With block size of 1 byte, I understand that
> req->nbytes can be for example 4 bytes which is not AES block
> aligned... If my reasoning is correct, then the CTR mode in s5p-sss is
> not fully working.
>


I re-ran the kernelci.org tests with this change, and I saw no more failures.

https://kernelci.org/boot/all/job/ardb/branch/for-kernelci/kernel/v5.3-rc1-197-gc8809c50be4f/