Commit 71972b9f authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Keith Busch
Browse files

nvme: add nvme_auth_generate_digest() 



Add a function to calculate the PSK digest as specified in TP8018.

Signed-off-by: default avatarHannes Reinecke <hare@kernel.org>
Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
parent 5c12a9cd

drivers/nvme/common/auth.c

+134 −0
Original line number Diff line number Diff line
@@ -558,5 +558,139 @@ int nvme_auth_generate_psk(u8 hmac_id, u8 *skey, size_t skey_len, 
}

EXPORT_SYMBOL_GPL(nvme_auth_generate_psk);



/**

 * nvme_auth_generate_digest - Generate TLS PSK digest

 * @hmac_id: Hash function identifier

 * @psk: Generated input PSK

 * @psk_len: Length of @psk

 * @subsysnqn: NQN of the subsystem

 * @hostnqn: NQN of the host

 * @ret_digest: Pointer to the returned digest

 *

 * Generate a TLS PSK digest as specified in TP8018 Section 3.6.1.3:

 *   TLS PSK and PSK identity Derivation

 *

 * The PSK digest shall be computed by encoding in Base64 (refer to RFC

 * 4648) the result of the application of the HMAC function using the hash

 * function specified in item 4 above (ie the hash function of the cipher

 * suite associated with the PSK identity) with the PSK as HMAC key to the

 * concatenation of:

 * - the NQN of the host (i.e., NQNh) not including the null terminator;

 * - a space character;

 * - the NQN of the NVM subsystem (i.e., NQNc) not including the null

 *   terminator;

 * - a space character; and

 * - the seventeen ASCII characters "NVMe-over-Fabrics"

 * (i.e., <PSK digest> = Base64(HMAC(PSK, NQNh || " " || NQNc || " " ||

 *  "NVMe-over-Fabrics"))).

 * The length of the PSK digest depends on the hash function used to compute

 * it as follows:

 * - If the SHA-256 hash function is used, the resulting PSK digest is 44

 *   characters long; or

 * - If the SHA-384 hash function is used, the resulting PSK digest is 64

 *   characters long.

 *

 * Returns 0 on success with a valid digest pointer in @ret_digest, or a

 * negative error number on failure.

 */

int nvme_auth_generate_digest(u8 hmac_id, u8 *psk, size_t psk_len,

		char *subsysnqn, char *hostnqn, u8 **ret_digest)

{

	struct crypto_shash *tfm;

	SHASH_DESC_ON_STACK(shash, tfm);

	u8 *digest, *enc;

	const char *hmac_name;

	size_t digest_len, hmac_len;

	int ret;



	if (WARN_ON(!subsysnqn || !hostnqn))

		return -EINVAL;



	hmac_name = nvme_auth_hmac_name(hmac_id);

	if (!hmac_name) {

		pr_warn("%s: invalid hash algorithm %d\n",

			__func__, hmac_id);

		return -EINVAL;

	}



	switch (nvme_auth_hmac_hash_len(hmac_id)) {

	case 32:

		hmac_len = 44;

		break;

	case 48:

		hmac_len = 64;

		break;

	default:

		pr_warn("%s: invalid hash algorithm '%s'\n",

			__func__, hmac_name);

		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) {

		ret = -ENOMEM;

		goto out_free_tfm;

	}



	shash->tfm = tfm;

	ret = crypto_shash_setkey(tfm, 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);

	if (ret < hmac_len) {

		ret = -ENOKEY;

		goto out_free_digest;

	}

	*ret_digest = enc;

	ret = 0;



out_free_digest:

	kfree_sensitive(digest);

out_free_tfm:

	crypto_free_shash(tfm);

out_free_enc:

	if (ret)

		kfree_sensitive(enc);



	return ret;

}

EXPORT_SYMBOL_GPL(nvme_auth_generate_digest);



MODULE_DESCRIPTION("NVMe Authentication framework");

MODULE_LICENSE("GPL v2");

include/linux/nvme-auth.h

+2 −0
Original line number Diff line number Diff line
@@ -43,5 +43,7 @@ int nvme_auth_gen_shared_secret(struct crypto_kpp *dh_tfm, 
int nvme_auth_generate_psk(u8 hmac_id, u8 *skey, size_t skey_len,

			   u8 *c1, u8 *c2, size_t hash_len,

			   u8 **ret_psk, size_t *ret_len);

int nvme_auth_generate_digest(u8 hmac_id, u8 *psk, size_t psk_len,

		char *subsysnqn, char *hostnqn, u8 **ret_digest);



#endif /* _NVME_AUTH_H */