linux-kernel - Re: [PATCH v5 09/12] crypto: ecdsa - Rename keylen to bufsize where necessary

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Date: Thu, 7 Mar 2024 14:20:12 -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 v5 09/12] crypto: ecdsa - Rename keylen to bufsize where
 necessary



On 3/7/24 14:13, Jarkko Sakkinen wrote:
> On Thu Mar 7, 2024 at 12:22 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>
>> 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);
> 
> nit: still don't get why "* sizeof(u64)" would ever be more readable
> thean "* 8".

Because existing code in crypto uses sizeof(u64) when converting ndigits 
to number of bytes and '8' is not used for converting to bytes. Do we 
need to change this now ? No, I think it's better to conform to existing 
code.

# grep -rI ndigits crypto/ | grep sizeof\(u64\)
crypto/ecrdsa.c:        unsigned int ndigits = req->dst_len / sizeof(u64);
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:        ndigits = ctx->key_len / 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/ecdh.c:      params.key_size > sizeof(u64) * ctx->ndigits)
crypto/ecc.c:   size_t len = ndigits * sizeof(u64);
crypto/ecc.c:           num_bits = sizeof(u64) * ndigits * 8 + 1;
crypto/ecdsa.c: size_t bufsize = ndigits * sizeof(u64);
crypto/ecdsa.c: size_t bufsize = ctx->curve->g.ndigits * sizeof(u64);
crypto/ecdsa.c: ndigits = DIV_ROUND_UP(digitlen, sizeof(u64));

    Stefan

> 
> BR, Jarkko