linux-kernel - Re: [PATCH RFC 2/2] crypto: RSA: KEYS: convert rsa and public key to new PKE API

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Message-ID: <4394.1430497303@warthog.procyon.org.uk>
Date:	Fri, 01 May 2015 17:21:43 +0100
From:	David Howells <dhowells@...hat.com>
To:	Tadeusz Struk <tadeusz.struk@...el.com>
Cc:	dhowells@...hat.com, herbert@...dor.apana.org.au, corbet@....net,
	keescook@...omium.org, qat-linux@...el.com, jwboyer@...hat.com,
	richard@....at, d.kasatkin@...sung.com,
	linux-kernel@...r.kernel.org, steved@...hat.com, vgoyal@...hat.com,
	james.l.morris@...cle.com, jkosina@...e.cz,
	zohar@...ux.vnet.ibm.com, davem@...emloft.net, jdelvare@...e.de,
	linux-crypto@...r.kernel.org
Subject: Re: [PATCH RFC 2/2] crypto: RSA: KEYS: convert rsa and public key to new PKE API

Tadeusz Struk <tadeusz.struk@...el.com> wrote:

> +Additionally public key algorithm names are defined:
> +#define PKEY_ALGO_DSA "dsa"
> +#define PKEY_ALGO_RSA "rsa"
> +These will be used to allocate public key tfm instances.

These should be a blank line either side of the two #defines and the #defines
should be indented a tab.

> -	BUG_ON(ctx->sinfo->sig.pkey_algo != PKEY_ALGO_RSA);
> +	BUG_ON(strcmp(ctx->sinfo->sig.pkey_algo, PKEY_ALGO_RSA));

If you make PKEY_ALGO_RSA a const char [] can you use != here?

Oh, and can you do either != 0 or == 0 on the end of your strcmp()?  It's a
bit more obvious since strcmp()'s return is sort of inverse.

> +			.verify = RSA_verify_signature,
> +			.capabilities = PKEY_CAN_VERIFY,

Can we keep .verify_signature as the name of the first.  The second is
redundant given the function pointers.

> +		if (cert->pub && !IS_ERR(cert->pub->tfm))
> +			crypto_free_pke(cert->pub->tfm);
> ...
> +
> +	cert->pub->tfm = crypto_alloc_pke(ctx->cert->sig.pkey_algo, 0, 0);
> +	if (IS_ERR(cert->pub->tfm)) {
> +		pr_err("Failed to alloc pkey algo %s\n",
> +		       ctx->cert->sig.pkey_algo);
> +		goto error_decode;
> +	}
> +

Given that X.509 certs can hang around for a very long time, having a tfm in
the cert is probably a bad idea as it may pin resources such as crypto h/w.

> -	ctx->cert->pub->pkey_algo = PKEY_ALGO_RSA;
> -

I think you need this rather than the above.  You should only get the tfm when
you actually need it.

> -	pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]);
> +	pr_devel("Cert Key Algo: %s\n", pke_alg_name(cert->pub->tfm));

pkey_algo_name() perhaps?

> +	pr_devel("Cert Signature: %s + %s\n", cert->sig.pkey_algo,

Split line at that comma please.  That way all the arguments line up.

> -	cert->pub->algo = pkey_algo[cert->pub->pkey_algo];

Might still need this.

> -enum pkey_algo {
> -	PKEY_ALGO_DSA,
> -	PKEY_ALGO_RSA,
> -	PKEY_ALGO__LAST
> -};

This represents a value seen external to the kernel - at least for the
moment.  Switching to PKCS#7 module sigs would cure that.

> +#define PKEY_ALGO_DSA "dsa"
> +#define PKEY_ALGO_RSA "rsa"

const char []

> +int public_key_verify_signature(const struct public_key *pk,
> +				const struct public_key_signature *sig);

Retain the extern please and the following blank line.

> +static const char *const pkey_algo_name[] = {
> +	PKEY_ALGO_DSA, PKEY_ALGO_RSA
> +};
> +

Split the list over multiple lines, please.  Better still, move to PKCS#7.

David
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