Re: [PATCH v5 3/8] crypto: hctr2 - Add HCTR2 support

[Eric Biggers <ebiggers@kernel.org>]

On Wed, Apr 27, 2022 at 12:37:54AM +0000, Nathan Huckleberry wrote:
> +static int hctr2_create_common(struct crypto_template *tmpl,
> +			       struct rtattr **tb,
> +			       const char *xctr_name,
> +			       const char *polyval_name)
> +{
> +	u32 mask;
> +	struct skcipher_instance *inst;
> +	struct hctr2_instance_ctx *ictx;
> +	struct skcipher_alg *xctr_alg;
> +	struct crypto_alg *blockcipher_alg;
> +	struct shash_alg *polyval_alg;
> +	char blockcipher_name[CRYPTO_MAX_ALG_NAME];
> +	int len;
> +	int err;
> +
> +	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
> +	if (err)
> +		return err;
> +
> +	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
> +	if (!inst)
> +		return -ENOMEM;
> +	ictx = skcipher_instance_ctx(inst);
> +
> +	/* Stream cipher, xctr(block_cipher) */
> +	err = crypto_grab_skcipher(&ictx->xctr_spawn,
> +				   skcipher_crypto_instance(inst),
> +				   xctr_name, 0, mask);
> +	if (err)
> +		goto err_free_inst;
> +	xctr_alg = crypto_spawn_skcipher_alg(&ictx->xctr_spawn);
> +
> +	err = -EINVAL;
> +	if (strncmp(xctr_alg->base.cra_name, "xctr(", 5))
> +		goto err_free_inst;
> +	len = strscpy(blockcipher_name, xctr_name + 5,
> +		      sizeof(blockcipher_name));

Found a bug here; 'xctr_name' in the strscpy() statement needs to be
xctr_alg->base.cra_name.  Otherwise something like
'hctr2_base(xctr-aes-aesni,polyval-clmulni)' doesn't work, as it will try to
extract the block cipher name from the driver name "xctr-aes-aesni" instead of
from the algorithm name "xctr(aes)" as intended.

- Eric