[PATCH 17/21] nvme-auth: target: use crypto library in nvmet_auth_host_hash()

[Eric Biggers]

For the HMAC computation in nvmet_auth_host_hash(), 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/target/auth.c | 90 ++++++++++++--------------------------
 1 file changed, 28 insertions(+), 62 deletions(-)

diff --git a/drivers/nvme/target/auth.c b/drivers/nvme/target/auth.c
index 08c1783d70fc4..fc56ce74d20f2 100644
--- a/drivers/nvme/target/auth.c
+++ b/drivers/nvme/target/auth.c
@@ -281,51 +281,34 @@ bool nvmet_check_auth_status(struct nvmet_req *req)
 }
 
 int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
 			 unsigned int shash_len)
 {
-	struct crypto_shash *shash_tfm;
-	SHASH_DESC_ON_STACK(shash, shash_tfm);
+	struct nvme_auth_hmac_ctx hmac;
 	struct nvmet_ctrl *ctrl = req->sq->ctrl;
-	const char *hash_name;
 	u8 *challenge = req->sq->dhchap_c1;
 	struct nvme_dhchap_key *transformed_key;
 	u8 buf[4];
 	int ret;
 
-	hash_name = nvme_auth_hmac_name(ctrl->shash_id);
-	if (!hash_name) {
-		pr_warn("Hash ID %d invalid\n", ctrl->shash_id);
-		return -EINVAL;
-	}
-
-	shash_tfm = crypto_alloc_shash(hash_name, 0, 0);
-	if (IS_ERR(shash_tfm)) {
-		pr_err("failed to allocate shash %s\n", hash_name);
-		return PTR_ERR(shash_tfm);
-	}
-
-	if (shash_len != crypto_shash_digestsize(shash_tfm)) {
-		pr_err("%s: hash len mismatch (len %d digest %d)\n",
-			__func__, shash_len,
-			crypto_shash_digestsize(shash_tfm));
-		ret = -EINVAL;
-		goto out_free_tfm;
-	}
-
 	transformed_key = nvme_auth_transform_key(ctrl->host_key,
 						  ctrl->hostnqn);
-	if (IS_ERR(transformed_key)) {
-		ret = PTR_ERR(transformed_key);
-		goto out_free_tfm;
-	}
+	if (IS_ERR(transformed_key))
+		return PTR_ERR(transformed_key);
 
-	ret = crypto_shash_setkey(shash_tfm, transformed_key->key,
+	ret = nvme_auth_hmac_init(&hmac, ctrl->shash_id, transformed_key->key,
 				  transformed_key->len);
 	if (ret)
 		goto out_free_response;
 
+	if (shash_len != nvme_auth_hmac_hash_len(ctrl->shash_id)) {
+		pr_err("%s: hash len mismatch (len %u digest %zu)\n", __func__,
+		       shash_len, nvme_auth_hmac_hash_len(ctrl->shash_id));
+		ret = -EINVAL;
+		goto out_free_response;
+	}
+
 	if (ctrl->dh_gid != NVME_AUTH_DHGROUP_NULL) {
 		challenge = kmalloc(shash_len, GFP_KERNEL);
 		if (!challenge) {
 			ret = -ENOMEM;
 			goto out_free_response;
@@ -334,58 +317,41 @@ int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
 						    req->sq->dhchap_skey,
 						    req->sq->dhchap_skey_len,
 						    req->sq->dhchap_c1,
 						    challenge, shash_len);
 		if (ret)
-			goto out;
+			goto out_free_challenge;
 	}
 
 	pr_debug("ctrl %d qid %d host response seq %u transaction %d\n",
 		 ctrl->cntlid, req->sq->qid, req->sq->dhchap_s1,
 		 req->sq->dhchap_tid);
 
-	shash->tfm = shash_tfm;
-	ret = crypto_shash_init(shash);
-	if (ret)
-		goto out;
-	ret = crypto_shash_update(shash, challenge, shash_len);
-	if (ret)
-		goto out;
+	nvme_auth_hmac_update(&hmac, challenge, shash_len);
+
 	put_unaligned_le32(req->sq->dhchap_s1, buf);
-	ret = crypto_shash_update(shash, buf, 4);
-	if (ret)
-		goto out;
+	nvme_auth_hmac_update(&hmac, buf, 4);
+
 	put_unaligned_le16(req->sq->dhchap_tid, buf);
-	ret = crypto_shash_update(shash, buf, 2);
-	if (ret)
-		goto out;
+	nvme_auth_hmac_update(&hmac, buf, 2);
+
 	*buf = req->sq->sc_c;
-	ret = crypto_shash_update(shash, buf, 1);
-	if (ret)
-		goto out;
-	ret = crypto_shash_update(shash, "HostHost", 8);
-	if (ret)
-		goto out;
+	nvme_auth_hmac_update(&hmac, buf, 1);
+	nvme_auth_hmac_update(&hmac, "HostHost", 8);
 	memset(buf, 0, 4);
-	ret = crypto_shash_update(shash, ctrl->hostnqn, strlen(ctrl->hostnqn));
-	if (ret)
-		goto out;
-	ret = crypto_shash_update(shash, buf, 1);
-	if (ret)
-		goto out;
-	ret = crypto_shash_update(shash, ctrl->subsys->subsysnqn,
-				  strlen(ctrl->subsys->subsysnqn));
-	if (ret)
-		goto out;
-	ret = crypto_shash_final(shash, response);
-out:
+	nvme_auth_hmac_update(&hmac, ctrl->hostnqn, strlen(ctrl->hostnqn));
+	nvme_auth_hmac_update(&hmac, buf, 1);
+	nvme_auth_hmac_update(&hmac, ctrl->subsys->subsysnqn,
+			      strlen(ctrl->subsys->subsysnqn));
+	nvme_auth_hmac_final(&hmac, response);
+	ret = 0;
+out_free_challenge:
 	if (challenge != req->sq->dhchap_c1)
 		kfree(challenge);
 out_free_response:
+	memzero_explicit(&hmac, sizeof(hmac));
 	nvme_auth_free_key(transformed_key);
-out_free_tfm:
-	crypto_free_shash(shash_tfm);
 	return ret;
 }
 
 int nvmet_auth_ctrl_hash(struct nvmet_req *req, u8 *response,
 			 unsigned int shash_len)
-- 
2.53.0