[PATCH 18/21] nvme-auth: target: use crypto library in nvmet_auth_ctrl_hash()

Eric Biggers
2026-03-02T08:01:36Z

For the HMAC computation in nvmet_auth_ctrl_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@kernel.org>
---
drivers/nvme/target/auth.c | 94 ++++++++++----------------------------
1 file changed, 25 insertions(+), 69 deletions(-)

diff --git a/drivers/nvme/target/auth.c b/drivers/nvme/target/auth.c
index fc56ce74d20f2..b7417ab6b035f 100644
--- a/drivers/nvme/target/auth.c
+++ b/drivers/nvme/target/auth.c
@@ -7,11 +7,10 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/err.h>
-#include <crypto/hash.h>
#include <linux/crc32.h>
#include <linux/base64.h>
#include <linux/ctype.h>
#include <linux/random.h>
#include <linux/nvme-auth.h>
@@ -354,51 +353,34 @@ int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
}

int nvmet_auth_ctrl_hash(struct nvmet_req *req, u8 *response,
unsigned int shash_len)
{
- struct crypto_shash *shash_tfm;
- struct shash_desc *shash;
+ struct nvme_auth_hmac_ctx hmac;
struct nvmet_ctrl *ctrl = req->sq->ctrl;
- const char *hash_name;
u8 *challenge = req->sq->dhchap_c2;
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_debug("%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->ctrl_key,
ctrl->subsys->subsysnqn);
- 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;
@@ -410,59 +392,33 @@ int nvmet_auth_ctrl_hash(struct nvmet_req *req, u8 *response,
challenge, shash_len);
if (ret)
goto out_free_challenge;
}

- shash = kzalloc(sizeof(*shash) + crypto_shash_descsize(shash_tfm),
- GFP_KERNEL);
- if (!shash) {
- ret = -ENOMEM;
- goto out_free_challenge;
- }
- shash->tfm = shash_tfm;
+ nvme_auth_hmac_update(&hmac, challenge, shash_len);

- ret = crypto_shash_init(shash);
- if (ret)
- goto out;
- ret = crypto_shash_update(shash, challenge, shash_len);
- if (ret)
- goto out;
put_unaligned_le32(req->sq->dhchap_s2, 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);
+
memset(buf, 0, 4);
- ret = crypto_shash_update(shash, buf, 1);
- if (ret)
- goto out;
- ret = crypto_shash_update(shash, "Controller", 10);
- if (ret)
- goto out;
- ret = crypto_shash_update(shash, ctrl->subsys->subsysnqn,
- strlen(ctrl->subsys->subsysnqn));
- if (ret)
- goto out;
- ret = crypto_shash_update(shash, buf, 1);
- if (ret)
- goto out;
- ret = crypto_shash_update(shash, ctrl->hostnqn, strlen(ctrl->hostnqn));
- if (ret)
- goto out;
- ret = crypto_shash_final(shash, response);
-out:
- kfree(shash);
+ nvme_auth_hmac_update(&hmac, buf, 1);
+ nvme_auth_hmac_update(&hmac, "Controller", 10);
+ nvme_auth_hmac_update(&hmac, ctrl->subsys->subsysnqn,
+ strlen(ctrl->subsys->subsysnqn));
+ nvme_auth_hmac_update(&hmac, buf, 1);
+ nvme_auth_hmac_update(&hmac, ctrl->hostnqn, strlen(ctrl->hostnqn));
+ nvme_auth_hmac_final(&hmac, response);
+ ret = 0;
out_free_challenge:
if (challenge != req->sq->dhchap_c2)
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_exponential(struct nvmet_req *req,
u8 *buf, int buf_size)
--
2.53.0