crypto: ecdsa - Rename keylen to bufsize where necessary

In cases where 'keylen' was referring to the size of the buffer used by
a curve's digits, it does not reflect the purpose of the variable anymore
once NIST P521 is used. What it refers to then is the size of the buffer,
which may be a few bytes larger than the size a coordinate of a key.
Therefore, rename keylen to bufsize where appropriate.
Tested-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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);