+
+ /*
+ * Require Write permission on the keyring. This is essential
+ * because the default keyring may be the session keyring, and
+ * joining a keyring only requires Search permission.
+ *
+ * However, this check is skipped for the "requestor keyring" so
+ * that /sbin/request-key can itself use request_key() to add
+ * keys to the original requestor's destination keyring.
+ */
+ if (dest_keyring && do_perm_check) {
+ ret = key_permission(make_key_ref(dest_keyring, 1),
+ KEY_WRITE);
+ if (ret) {
+ key_put(dest_keyring);
+ return ret;
+ }
+ }