libekmfweb: Re-encipher the identity key

The identity key of the client is a secure key enciphered with the master key of a cryptographic adapter (APQN). When the master key of the used APQNs is changed, the identity key must be re-enciphered under the new master key. Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
2026-08-05 02:14:52 +00:00 · 2020-04-23 15:41:12 +02:00
parent 5fb30f1e6f
commit 1cdfb4946e
5 changed files with 355 additions and 1 deletions
@@ -1209,6 +1209,92 @@ int ekmf_generate_identity_key(const struct ekmf_config *config,
 	return 0;
 }

+/**
+ * Re-encipher the secure identity key (form field identity_secure_key in
+ * config) used to identify the client to EKMFWeb.
+ * The secure key blob is encrypted using the HSM master key. Whenever the HSM
+ * master key is being changed, the secure identity key must be re-enciphered.
+ * You can either pro-actively re-encipher a secure key once the new master key
+ * has been prepared (but not yet made active): to_new = true; or you can
+ * re-encipher a secure key when the HSM master key has already been changed:
+ * to_new = false. This requires that the HSM still has the old master key.
+ * Not all HSMs support this.
+ *
+ * For pro-active re-encipherment it is suggested to store the re-enciphered
+ * secure key on a separate place, until the new HSM master key has been made
+ * active. Specify a file name in reenc_secure_key to do so. For an in-place
+ * re-encipherment, set reenc_secure_key = NULL.
+ *
+ * @param config            the configuration structure. Only field
+ *                          identity_secure_key must be specified, all others
+ *                          are optional.
+ * @param to_new            If true: the identity key is re-enciphered from the
+ *                          current to the new master key.
+ *                          If false: the identity key is re-enciphered from the
+ *                          old to the current master key.
+ * @param reenc_secure_key  if not NULL, then the re-enciphered secure key is
+ *                          stored into the filename specified here. Otherwise
+ *                          the re-enciphered secure key replaces the original
+ *                          secure identity key.
+ * @param ext_lib           External secure key crypto library to use
+ * @param verbose           if true, verbose messages are printed
+ *
+ * @returns a negative errno in case of an error, 0 if success.
+ * A -ENODEV indicates that the master keys are not loaded.
+ */
+int ekmf_reencipher_identity_key(const struct ekmf_config *config,
+				 bool to_new, const char *reenc_secure_key,
+				 const struct ekmf_ext_lib *ext_lib,
+				 bool verbose)
+{
+	unsigned char key_blob[MAX_KEY_BLOB_SIZE];
+	size_t key_blob_size = sizeof(key_blob);
+	const char *out_file;
+	int rc;
+
+	if (config == NULL || ext_lib == NULL)
+		return -EINVAL;
+	if (config->identity_secure_key == NULL)
+		return -EINVAL;
+
+	rc = read_key_blob(config->identity_secure_key, key_blob,
+			   &key_blob_size);
+	if (rc != 0) {
+		pr_verbose(verbose, "Failed to read identity key from file "
+			   "'%s': %s", config->identity_secure_key,
+			   strerror(-rc));
+		return rc;
+	}
+
+	switch (ext_lib->type) {
+	case EKMF_EXT_LIB_CCA:
+		rc = cca_reencipher_key(ext_lib->cca, key_blob, key_blob_size,
+					to_new, verbose);
+		break;
+	default:
+		pr_verbose(verbose, "Invalid ext lib type: %d", ext_lib->type);
+		return -EINVAL;
+	}
+
+	if (rc != 0) {
+		pr_verbose(verbose, "Failed to re-encipher the secure identity "
+			   "key from file '%s': %s",
+			   config->identity_secure_key, strerror(-rc));
+		return rc;
+	}
+
+	out_file = reenc_secure_key != NULL ? reenc_secure_key :
+						config->identity_secure_key;
+	rc = write_key_blob(out_file, key_blob, key_blob_size);
+	if (rc != 0) {
+		pr_verbose(verbose, "Failed to write identity key to file "
+			   "'%s': %s", out_file, strerror(-rc));
+		return rc;
+	}
+
+	return 0;
+}
+
 /**
 * Library constructor
 */