libnvme: Implement 'nvme_generate_tls_key_identity()'

Implement a function to generate the TLS key identity.

Signed-off-by: Hannes Reinecke <hare@suse.de>

src/libnvme.map

@@ -4,6 +4,7 @@ LIBNVME_1_7 {
 		nvme_init_copy_range_f2;
 		nvme_init_copy_range_f3;
 		nvme_insert_tls_key_versioned;
+		nvme_generate_tls_key_identity;
 };
 
 LIBNVME_1_6 {

src/nvme/linux.c

@@ -1231,6 +1231,38 @@ long nvme_insert_tls_key_versioned(const char *keyring, const char *key_type,
 	return key;
 }
 
+char *nvme_generate_tls_key_identity(const char *hostnqn, const char *subsysnqn,
+				     int version, int hmac,
+				     unsigned char *configured_key, int key_len)
+{
+	char *identity;
+	size_t identity_len;
+	unsigned char *psk;
+	int ret;
+
+	identity_len = nvme_identity_len(hmac, version, hostnqn, subsysnqn);
+	if (identity_len < 0)
+		return NULL;
+
+	identity = malloc(identity_len);
+	if (!identity)
+		return NULL;
+
+	psk = malloc(key_len);
+	if (!psk)
+		goto out_free_identity;
+
+	memset(psk, 0, key_len);
+	ret = derive_nvme_keys(hostnqn, subsysnqn, identity, version, hmac,
+			       configured_key, psk, key_len);
+	free(psk);
+out_free_identity:
+	if (ret < 0) {
+		free(identity);
+		identity = NULL;
+	}
+	return identity;
+}
 #else
 long nvme_lookup_keyring(const char *keyring)
 {
@@ -1274,6 +1306,16 @@ long nvme_insert_tls_key_versioned(const char *keyring, const char *key_type,
 	errno = ENOTSUP;
 	return -1;
 }
+
+char *nvme_generate_tls_key_identity(const char *hostnqn, const char *subsysnqn,
+				     int version, int hmac,
+				     unsigned char *configured_key, int key_len)
+{
+	nvme_msg(NULL, LOG_ERR, "key operations not supported; " \
+		 "recompile with keyutils support.\n");
+	errno = ENOTSUP;
+	return -1;
+}
 #endif
 
 long nvme_insert_tls_key(const char *keyring, const char *key_type,

src/nvme/linux.h

@@ -316,4 +316,23 @@ long nvme_insert_tls_key_versioned(const char *keyring, const char *key_type,
 				   int version, int hmac,
 				   unsigned char *configured_key, int key_len);
 
+/**
+ * nvme_generate_tls_key_identity() - Generate the TLS key identity
+ * @hostnqn:	Host NVMe Qualified Name
+ * @subsysnqn:	Subsystem NVMe Qualified Name
+ * @version:	Key version to use
+ * @hmac:	HMAC algorithm
+ * @configured_key:	Configured key data to derive the key from
+ * @key_len:	Length of @configured_key
+ *
+ * Derives a 'retained' TLS key as specified in NVMe TCP and
+ * generate the corresponding TLs identity.
+ *
+ * Return: The string containing the TLS identity. It is the responsibility
+ * of the caller to free the returned string.
+ */
+char *nvme_generate_tls_key_identity(const char *hostnqn, const char *subsysnqn,
+				     int version, int hmac,
+				     unsigned char *configured_key, int key_len);
+
 #endif /* _LIBNVME_LINUX_H */