linux-kernel - Re: [PATCH v6 10/13] crypto: ecdsa - Rename keylen to bufsize where necessary

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Date: Mon, 18 Mar 2024 23:07:53 +0200
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Stefan Berger" <stefanb@...ux.vnet.ibm.com>,
 <keyrings@...r.kernel.org>, <linux-crypto@...r.kernel.org>,
 <herbert@...dor.apana.org.au>, <davem@...emloft.net>
Cc: <linux-kernel@...r.kernel.org>, <saulo.alessandre@....jus.br>,
 <lukas@...ner.de>, <bbhushan2@...vell.com>, "Stefan Berger"
 <stefanb@...ux.ibm.com>
Subject: Re: [PATCH v6 10/13] crypto: ecdsa - Rename keylen to bufsize where
 necessary

On Tue Mar 12, 2024 at 8:36 PM EET, Stefan Berger wrote:
> From: Stefan Berger <stefanb@...ux.ibm.com>
>
> In some cases the name keylen does not reflect the purpose of the variable

What are "some cases"?

Just pointing out stuff that should be enumerated properly because this 
requires the reader to complete the commit messages by open coding "some
cases".

> anymore once NIST P521 is used but it is the size of the buffer. There-
> for, rename keylen to bufsize where appropriate.
>
> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
> Tested-by: Lukas Wunner <lukas@...ner.de>
> ---
>  crypto/ecdsa.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
> index 4daefb40c37a..4e847b59622a 100644
> --- a/crypto/ecdsa.c
> +++ b/crypto/ecdsa.c
> @@ -35,8 +35,8 @@ struct ecdsa_signature_ctx {
>  static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
>  				  const void *value, size_t vlen, unsigned int ndigits)
>  {
> -	size_t keylen = ndigits * sizeof(u64);
> -	ssize_t diff = vlen - keylen;
> +	size_t bufsize = ndigits * sizeof(u64);
> +	ssize_t diff = vlen - bufsize;
>  	const char *d = value;
>  	u8 rs[ECC_MAX_BYTES];
>  
> @@ -58,7 +58,7 @@ static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
>  		if (diff)
>  			return -EINVAL;
>  	}
> -	if (-diff >= keylen)
> +	if (-diff >= bufsize)
>  		return -EINVAL;
>  
>  	if (diff) {
> @@ -138,7 +138,7 @@ static int ecdsa_verify(struct akcipher_request *req)
>  {
>  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
>  	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
> -	size_t keylen = ctx->curve->g.ndigits * sizeof(u64);
> +	size_t bufsize = ctx->curve->g.ndigits * sizeof(u64);
>  	struct ecdsa_signature_ctx sig_ctx = {
>  		.curve = ctx->curve,
>  	};
> @@ -165,14 +165,14 @@ static int ecdsa_verify(struct akcipher_request *req)
>  		goto error;
>  
>  	/* if the hash is shorter then we will add leading zeros to fit to ndigits */
> -	diff = keylen - req->dst_len;
> +	diff = bufsize - req->dst_len;
>  	if (diff >= 0) {
>  		if (diff)
>  			memset(rawhash, 0, diff);
>  		memcpy(&rawhash[diff], buffer + req->src_len, req->dst_len);
>  	} else if (diff < 0) {
>  		/* given hash is longer, we take the left-most bytes */
> -		memcpy(&rawhash, buffer + req->src_len, keylen);
> +		memcpy(&rawhash, buffer + req->src_len, bufsize);
>  	}
>  
>  	ecc_swap_digits((u64 *)rawhash, hash, ctx->curve->g.ndigits);

BR, Jarkko