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References: <20190815192858.28125-1-ard.biesheuvel@linaro.org>
 <20190815192858.28125-2-ard.biesheuvel@linaro.org> <20190819063218.GA31821@gondor.apana.org.au>
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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Mon, 19 Aug 2019 17:14:25 +0300
Message-ID: <CAKv+Gu9Zcaq5gygGtgmf5f4L6U6sBDd0CVAzrBydjiLDenyrag@mail.gmail.com>
Subject: Re: [PATCH v12 1/4] crypto: essiv - create wrapper template for ESSIV generation
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@vger.kernel.org>, Eric Biggers <ebiggers@google.com>,
        device-mapper development <dm-devel@redhat.com>,
        linux-fscrypt@vger.kernel.org,
        Gilad Ben-Yossef <gilad@benyossef.com>,
        Milan Broz <gmazyland@gmail.com>
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On Mon, 19 Aug 2019 at 09:32, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Thu, Aug 15, 2019 at 10:28:55PM +0300, Ard Biesheuvel wrote:
> >
> > +     /* Synchronous hash, e.g., "sha256" */
> > +     ictx->hash = crypto_alloc_shash(shash_name, 0, 0);
> > +     if (IS_ERR(ictx->hash)) {
> > +             err = PTR_ERR(ictx->hash);
> > +             goto out_drop_skcipher;
> > +     }
>
> Holding a reference to this algorithm for the life-time of the
> instance is not nice.  How about just doing a lookup as you were
> doing before with crypto_alg_mod_lookup and getting the cra_name
> from that?
>

OK, but it should be the cra_driver_name not the cra_name. Otherwise,
allocating essiv(cbc(aes),sha256-generic) may end up using a different
implementation of sha256, which would be bad.