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Date:   Thu, 28 Feb 2019 13:33:37 +0300
From:   Vitaly Chikunov <vt@altlinux.org>
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     David Howells <dhowells@redhat.com>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/4] X.509: Parse public key parameters from x509 for
 akcipher
Message-ID: <20190228103337.sbjujn27qkkgxqt2@altlinux.org>
Mail-Followup-To: Herbert Xu <herbert@gondor.apana.org.au>,
        David Howells <dhowells@redhat.com>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
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 <20190228075141.s6mftb44yuylbzys@gondor.apana.org.au>
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On Thu, Feb 28, 2019 at 05:01:25PM +0800, Herbert Xu wrote:
> On Thu, Feb 28, 2019 at 11:28:01AM +0300, Vitaly Chikunov wrote:
> > On Thu, Feb 28, 2019 at 03:51:41PM +0800, Herbert Xu wrote:
> > > On Thu, Feb 28, 2019 at 10:04:49AM +0300, Vitaly Chikunov wrote:
> > > > 
> > > > It seems that you insist on set_params to be removed and both key and
> > > > params to be passed into set_{pub,priv}_key. This means reworking all
> > > > existing RSA drivers and callers, right? Can you please confirm that
> > > > huge rework to avoid misunderstanding?
> > > 
> > > I don't understand why we even need to touch the existing RSA
> > > drivers.  Nothing needs to change as far as they're concerned.
> > > 
> > > Only the new algorithms would need to decode the extra parameters
> > > in the key stream.
> > 
> >         int (*set_pub_key)(struct crypto_akcipher *tfm, const void *key,
> >                            unsigned int keylen);
> >         int (*set_priv_key)(struct crypto_akcipher *tfm, const void *key,
> >                             unsigned int keylen);
> > 
> > So you want `keylen' not to cover parameters data, but parameters
> > actually present in key after `keylen' bytes (in come packed format)?
> > (And if there is no parameters appended, there is still appended some
> > marker, like 0, to signify that there is no parameters.)
> > 
> > This looks a bit counter-intuitive usage of arguments (as argument
> > signifying length does not cover all arguments data), is this ok to you?
> 
> This is how we handle things in DH as well as other places such
> as authenc.

dh.c (set_secret) is getting buf, len arguments and then parameters are
unpacked from that buffer. I think you want me to do this.

To make the same for set_{pub,priv}_key it will require patching RSA
drivers anyway, since length of the key is stored just once as keylen
argument.

Drivers will be changed to interpret key, keylen as buf, len and actual
keylen will be stored into the buf, and will be unpacked from there.

Thanks,

> 
> Cheers,
> -- 
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt