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References: <20230217144348.1537615-1-ardb@kernel.org> <Y/L6rSGDidhhWq2v@gondor.apana.org.au>
 <CAMj1kXE8ZjVh=hLVgnRGr8cJpkqzRHsVxuq3dm1P=Aqc1QpcXg@mail.gmail.com> <ZAsDT00Jgs2p6luL@gondor.apana.org.au>
In-Reply-To: <ZAsDT00Jgs2p6luL@gondor.apana.org.au>
From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Fri, 10 Mar 2023 17:18:05 +0100
Message-ID: <CAMj1kXHhF7CyeGV2QHu6MRVQNKo1EHFkshewOfptEOdJ5znJDA@mail.gmail.com>
Subject: Re: [PATCH v2] crypto: lib - implement library version of AES in CFB mode
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     linux-crypto@vger.kernel.org, ebiggers@kernel.org,
        James Bottomley <James.Bottomley@hansenpartnership.com>
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Precedence: bulk

On Fri, 10 Mar 2023 at 11:15, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Mon, Feb 20, 2023 at 08:28:05AM +0100, Ard Biesheuvel wrote:
> >
> > We would still not have any in-tree users of cfb(aes) or any other
> > cfb(*), so in that sense, yes.
> >
> > However, skciphers can be called from user space, and we also rely on
> > this template for the extended testing of the various cfb() hardware
> > implementations that we have in the tree.
> >
> > So the answer is no, I suppose. I would like to simplify it a bit,
> > though - it is a bit more complicated than it needs to be.
>
> Could we hold onto this for a little bit? I'd like to finally
> remove crypto_cipher, and in doing so I will add a virtual address
> interface (i.e., not sg) to skcipher like we do with scomp and shash.
>

Does that mean you are bringing back blkcipher? I think that would the
right thing to do tbh, although it might make sense to enhance
skcipher (and aead) to support this.

Could we perhaps update struct skcipher_request so it can describe
virtually mapped address ranges, but permit this only for synchronous
implementations? Then, we could update the skcipher walker code to
produce a single walk step covering the entire range, and just use the
provided virtual addresses directly, rather than going through a
mapping interface?