ARI: Make ARI applications respect live_dangerously.

DeveloperNote: ARI applications can no longer call "dangerous" dialplan
functions like DB(), FILE(), SHELL(), CURL(), STAT(), etc. without
enabling "live_dangerously" in asterisk.conf.

Resolves: #GHSA-vrfp-mg3q-3959

include/asterisk/stasis_app.h

@@ -631,6 +631,11 @@ int stasis_app_control_answer(struct stasis_app_control *control);
  * \param variable The name of the variable
  * \param value The value to set the variable to
  *
+ * \note The thread that actually does the set will have the inhibit_escalations
+ * flag set before the call to pbx_builtin_setvar_helper to prevent dangerous
+ * dialplan function execution from ARI.  The flag will be reset to its original
+ * state when pbx_builtin_setvar_helper returns.
+ *
  * \return 0 for success.
  * \return -1 for error.
  */

res/stasis/control.c

@@ -745,12 +745,22 @@ static int app_control_set_channel_var(struct stasis_app_control *control,
 	struct ast_channel *chan, void *data)
 {
 	struct chanvar *var = data;
+	/*
+	 * Save the current inhibit state then enable it.
+	 */
+	int inhibited = ast_thread_inhibit_escalations_swap(1);
 
 	if (ast_channel_set_ari_var_reportable(control->channel, var->name, var->report_events)) {
 		return -1;
 	}
 
 	pbx_builtin_setvar_helper(control->channel, var->name, var->value);
+	/*
+	 * Re-enable it if it was originally enabled.
+	 */
+	if (inhibited > 0) {
+		ast_thread_inhibit_escalations();
+	}
 
 	return 0;
 }