[PATCH 11/21] nvme-auth: common: use crypto library in nvme_auth_generate_digest()

[Eric Biggers]

For the HMAC computation in nvme_auth_generate_digest(), use the crypto
library instead of crypto_shash.  This is simpler, faster, and more
reliable.  Notably, this eliminates the crypto transformation object
allocation for every call, which was very slow.

Signed-off-by: Eric Biggers <ebiggers at kernel.org>
---
 drivers/nvme/common/auth.c | 87 +++++++++++---------------------------
 1 file changed, 25 insertions(+), 62 deletions(-)

diff --git a/drivers/nvme/common/auth.c b/drivers/nvme/common/auth.c
index 781d1d5d46dd3..f0b4e1c6ade7e 100644
--- a/drivers/nvme/common/auth.c
+++ b/drivers/nvme/common/auth.c
@@ -559,103 +559,66 @@ EXPORT_SYMBOL_GPL(nvme_auth_generate_psk);
  */
 int nvme_auth_generate_digest(u8 hmac_id, const u8 *psk, size_t psk_len,
 			      const char *subsysnqn, const char *hostnqn,
 			      char **ret_digest)
 {
-	struct crypto_shash *tfm;
-	SHASH_DESC_ON_STACK(shash, tfm);
-	u8 *digest;
+	struct nvme_auth_hmac_ctx hmac;
+	u8 digest[NVME_AUTH_MAX_DIGEST_SIZE];
+	size_t hash_len = nvme_auth_hmac_hash_len(hmac_id);
 	char *enc;
-	const char *hmac_name;
-	size_t digest_len, hmac_len;
+	size_t enc_len;
 	int ret;
 
 	if (WARN_ON(!subsysnqn || !hostnqn))
 		return -EINVAL;
 
-	hmac_name = nvme_auth_hmac_name(hmac_id);
-	if (!hmac_name) {
+	if (hash_len == 0) {
 		pr_warn("%s: invalid hash algorithm %d\n",
 			__func__, hmac_id);
 		return -EINVAL;
 	}
 
-	switch (nvme_auth_hmac_hash_len(hmac_id)) {
+	switch (hash_len) {
 	case 32:
-		hmac_len = 44;
+		enc_len = 44;
 		break;
 	case 48:
-		hmac_len = 64;
+		enc_len = 64;
 		break;
 	default:
 		pr_warn("%s: invalid hash algorithm '%s'\n",
-			__func__, hmac_name);
+			__func__, nvme_auth_hmac_name(hmac_id));
 		return -EINVAL;
 	}
 
-	enc = kzalloc(hmac_len + 1, GFP_KERNEL);
-	if (!enc)
-		return -ENOMEM;
-
-	tfm = crypto_alloc_shash(hmac_name, 0, 0);
-	if (IS_ERR(tfm)) {
-		ret = PTR_ERR(tfm);
-		goto out_free_enc;
-	}
-
-	digest_len = crypto_shash_digestsize(tfm);
-	digest = kzalloc(digest_len, GFP_KERNEL);
-	if (!digest) {
+	enc = kzalloc(enc_len + 1, GFP_KERNEL);
+	if (!enc) {
 		ret = -ENOMEM;
-		goto out_free_tfm;
+		goto out;
 	}
 
-	shash->tfm = tfm;
-	ret = crypto_shash_setkey(tfm, psk, psk_len);
+	ret = nvme_auth_hmac_init(&hmac, hmac_id, psk, psk_len);
 	if (ret)
-		goto out_free_digest;
-
-	ret = crypto_shash_init(shash);
-	if (ret)
-		goto out_free_digest;
-
-	ret = crypto_shash_update(shash, hostnqn, strlen(hostnqn));
-	if (ret)
-		goto out_free_digest;
-
-	ret = crypto_shash_update(shash, " ", 1);
-	if (ret)
-		goto out_free_digest;
-
-	ret = crypto_shash_update(shash, subsysnqn, strlen(subsysnqn));
-	if (ret)
-		goto out_free_digest;
-
-	ret = crypto_shash_update(shash, " NVMe-over-Fabrics", 18);
-	if (ret)
-		goto out_free_digest;
-
-	ret = crypto_shash_final(shash, digest);
-	if (ret)
-		goto out_free_digest;
-
-	ret = base64_encode(digest, digest_len, enc, true, BASE64_STD);
-	if (ret < hmac_len) {
+		goto out;
+	nvme_auth_hmac_update(&hmac, hostnqn, strlen(hostnqn));
+	nvme_auth_hmac_update(&hmac, " ", 1);
+	nvme_auth_hmac_update(&hmac, subsysnqn, strlen(subsysnqn));
+	nvme_auth_hmac_update(&hmac, " NVMe-over-Fabrics", 18);
+	nvme_auth_hmac_final(&hmac, digest);
+
+	ret = base64_encode(digest, hash_len, enc, true, BASE64_STD);
+	if (ret < enc_len) {
 		ret = -ENOKEY;
-		goto out_free_digest;
+		goto out;
 	}
 	*ret_digest = enc;
 	ret = 0;
 
-out_free_digest:
-	kfree_sensitive(digest);
-out_free_tfm:
-	crypto_free_shash(tfm);
-out_free_enc:
+out:
 	if (ret)
 		kfree_sensitive(enc);
-
+	memzero_explicit(digest, sizeof(digest));
 	return ret;
 }
 EXPORT_SYMBOL_GPL(nvme_auth_generate_digest);
 
 /**
-- 
2.53.0