Re: [PATCH v8 3/4] crypto: AF_ALG -- add asymmetric cipher

[Tudor Ambarus <tudor.ambarus@microchip.com>]

Hi, Stephan,

>>> +static int akcipher_setprivkey(void *private, const u8 *key,
>>> +			       unsigned int keylen)
>>> +{
>>> +	struct akcipher_tfm *tfm = private;
>>> +	struct crypto_akcipher *akcipher = tfm->akcipher;
>>> +	int err;
>>> +
>>> +	err = crypto_akcipher_set_priv_key(akcipher, key, keylen);
>>> +	tfm->has_key = !err;
>>> +
>>> +	/* Return the maximum size of the akcipher operation. */
>>> +	if (!err)
>>> +		err = crypto_akcipher_maxsize(akcipher);
>>
>> crypto subsystem returns zero when setkey is successful and introduces
>> a new function for determining the maxsize. Should we comply with that?
> 
> The idea is that only when the the setting of the priv key fails, it returns
> the size of the expected privkey.
> 
> Which new function are you referring to?

I was referring to crypto_akcipher_maxsize. When
crypto_akcipher_set_priv_key fails, you are overwriting it's return
value with the value of crypto_akcipher_maxsize, hiding the cause of
the error.

crypto akcipher uses a dedicated function for determining the length of
the output buffer, crypto_akcipher_maxsize. Should we add a new function
pointer in struct af_alg_type that returns the maxsize?

Thanks,
ta