pam_slurm_adopt - switch to internal version of _pam_drop_reply()

Linux-PAM deprecated _pam_drop_reply().  Implement a basic replacement
internally and use that function instead.

For our use case the response message is simply a single NULL string.

Cherry-picked: 07d30f8
Ticket: 17724

Author: mcmult

contribs/pam_slurm_adopt/helper.c

@@ -100,6 +100,19 @@ _log_msg(int level, const char *format, ...)
 	return;
 }
 
+/*
+ * pam 1.5.3 stopped providing _pam_drop_reply().  Our use does not currently
+ * fetch sensitive data so simply free this structure.
+ */
+static void _pam_slurm_drop_response(struct pam_response *reply, int replies)
+{
+	for (int i = 0; i < replies; i++) {
+		if (reply[i].resp)
+			free(reply[i].resp);
+	}
+	free(reply);
+}
+
 /*
  *  Sends a message to the application informing the user
  *  that access was denied due to Slurm.
@@ -141,7 +154,7 @@ send_user_msg(pam_handle_t *pamh, const char *mesg)
 		_log_msg(LOG_ERR, "unable to converse with app: %s",
 			 pam_strerror(pamh, retval));
 	if (prsp != NULL)
-		_pam_drop_reply(prsp, 1);
+		_pam_slurm_drop_response(prsp, 1);
 
 	return;
 }