linux-kernel - Re: [PATCH v4 09/12] crypto: ecdsa - Rename keylen to bufsize where necessary

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Date: Fri, 1 Mar 2024 15:47:44 -0500
From: Stefan Berger <stefanb@...ux.ibm.com>
To: Jarkko Sakkinen <jarkko@...nel.org>, 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
Subject: Re: [PATCH v4 09/12] crypto: ecdsa - Rename keylen to bufsize where
 necessary



On 3/1/24 15:41, Jarkko Sakkinen wrote:
> On Fri Mar 1, 2024 at 4:20 AM EET, Stefan Berger wrote:
>> In some cases the name keylen does not reflect the purpose of the variable
>> 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>
>> ---
>>   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);
> 
> why not just "* 8"? using sizeof here makes this function only unreadable.

'unreadable' is a 'strong' word ...

# grep -r -E "ndigits \*" crypto/ | grep sizeof
crypto/ecrdsa.c:            req->dst_len != ctx->curve->g.ndigits * 
sizeof(u64) ||
crypto/ecrdsa.c:        vli_from_be64(r, sig + ndigits * sizeof(u64), 
ndigits);
crypto/ecrdsa.c:            ctx->curve->g.ndigits * sizeof(u64) != 
ctx->digest_len)
crypto/ecrdsa.c:            ctx->key_len != ctx->curve->g.ndigits * 
sizeof(u64) * 2)
crypto/ecrdsa.c:        vli_from_le64(ctx->pub_key.y, ctx->key + ndigits 
* sizeof(u64),
crypto/ecrdsa.c:        return ctx->pub_key.ndigits * sizeof(u64);
crypto/ecc.c:   size_t len = ndigits * sizeof(u64);
crypto/ecc.c:   num_bits = sizeof(u64) * ndigits * 8 + 1;
crypto/ecdsa.c: size_t keylen = ndigits * sizeof(u64);
crypto/ecdsa.c: size_t keylen = ctx->curve->g.ndigits * sizeof(u64);

    Stefan