X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=udev.c;h=67b86e5916ced757a921bbbd442bee3e876c6298;hp=bf18a568eaae06b7ce09b3ea0ca79ddde3be0434;hb=5aebfbcb62614fc2bf2b1579d62e3fe272c6751a;hpb=3d150dfb28efbaf0b25f154fb8955c47d606c3d5;ds=sidebyside

diff --git a/udev.c b/udev.c
index bf18a568e..67b86e591 100644
--- a/udev.c
+++ b/udev.c
@@ -63,6 +63,60 @@ static inline char *get_seqnum(void)
 	return seqnum;
 }
 
+#ifdef USE_DBUS
+
+/** Global variable for the connection the to system message bus or #NULL
+ *  if we cannot connect or acquire the org.kernel.udev service
+ */
+DBusConnection* sysbus_connection;
+
+/** Disconnect from the system message bus */
+static void sysbus_disconnect()
+{
+        if (sysbus_connection == NULL)
+                return;
+
+        dbus_connection_disconnect(sysbus_connection);
+        sysbus_connection = NULL;
+}
+
+/** Connect to the system message bus */
+static void sysbus_connect()
+{
+        DBusError error;
+
+        /* Connect to a well-known bus instance, the system bus */
+        dbus_error_init(&error);
+        sysbus_connection = dbus_bus_get(DBUS_BUS_SYSTEM, &error);
+        if (sysbus_connection == NULL) {
+                dbg("cannot connect to system message bus, error %s: %s", 
+                    error.name, error.message);
+                dbus_error_free(&error);
+                return;
+        }
+
+        /*  Acquire the org.kernel.udev service such that listeners
+         *  know that the message is really from us and not from a
+         *  random attacker. See the file udev_sysbus_policy.conf for
+         *  details.
+         *
+         *  Note that a service can have multiple owners (though there
+         *  is a concept of a primary owner for reception of messages)
+         *  so no race is introduced if two copies of udev is running
+         *  at the same time.
+         */
+        dbus_bus_acquire_service(sysbus_connection, "org.kernel.udev", 0, 
+                                 &error);
+        if (dbus_error_is_set(&error)) {
+                printf("cannot acquire org.kernel.udev service, error %s: %s'",
+                       error.name, error.message);
+                sysbus_disconnect();
+                return;
+        }
+}
+
+#endif /* USE_DBUS */
+
 int main(int argc, char **argv, char **envp)
 {
 	char *action;
@@ -111,6 +165,11 @@ int main(int argc, char **argv, char **envp)
 	/* initialize our configuration */
 	udev_init_config();
 
+#ifdef USE_DBUS
+        /* connect to the system message bus */
+        sysbus_connect();
+#endif /* USE_DBUS */
+
 	/* initialize udev database */
 	retval = udevdb_init(UDEVDB_DEFAULT);
 	if (retval != 0) {
@@ -133,6 +192,11 @@ int main(int argc, char **argv, char **envp)
 	}
 	udevdb_exit();
 
+#ifdef USE_DBUS
+        /* disconnect from the system message bus */
+        sysbus_disconnect();
+#endif /* USE_DBUS */
+
 exit:	
 	return retval;
 }