discover/device-handler: Prevent normal users changing boot target

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>

2 files changed, 14 insertions, 2 deletions

diff --git a/discover/device-handler.c b/discover/device-handler.c
index 729ed2c..e446cab 100644
--- a/discover/device-handler.c
+++ b/discover/device-handler.c
@@ -81,6 +81,7 @@ struct device_handler {
 	struct autoboot_option	*temp_autoboot;
 
 	struct discover_boot_option *default_boot_option;
+	struct discover_boot_option *last_boot_option;
 	int			default_boot_option_priority;
 
 	struct list		unresolved_boot_options;
@@ -756,6 +757,8 @@ static int default_timeout(void *arg)
 
 	opt = handler->default_boot_option;
 
+	handler->last_boot_option = opt;
+
 	if (handler->sec_to_boot) {
 		countdown_status(handler, opt, handler->sec_to_boot);
 		handler->sec_to_boot--;
@@ -1453,13 +1456,22 @@ static struct discover_boot_option *find_boot_option_by_id(
 }
 
 void device_handler_boot(struct device_handler *handler,
-		struct boot_command *cmd)
+		bool change_default, struct boot_command *cmd)
 {
 	struct discover_boot_option *opt = NULL;
 
 	if (cmd->option_id && strlen(cmd->option_id))
 		opt = find_boot_option_by_id(handler, cmd->option_id);
 
+	/* Don't allow a normal client to change the default */
+	if (!change_default && handler->last_boot_option &&
+			opt != handler->last_boot_option) {
+		pb_log("Non-root user tried to change boot option\n");
+		device_handler_status_err(handler,
+				"Must be root to change default boot option\n");
+		return;
+	}
+
 	if (handler->pending_boot)
 		boot_cancel(handler->pending_boot);
 
diff --git a/discover/device-handler.h b/discover/device-handler.h
index 9696ec0..9619a2d 100644
--- a/discover/device-handler.h
+++ b/discover/device-handler.h
@@ -161,7 +161,7 @@ struct discover_boot_option *device_handler_find_option_by_name(
 		struct device_handler *handler, const char *device,
 		const char *name);
 void device_handler_boot(struct device_handler *handler,
-		struct boot_command *cmd);
+		bool change_default, struct boot_command *cmd);
 void device_handler_cancel_default(struct device_handler *handler);
 void device_handler_update_config(struct device_handler *handler,
 		struct config *config);