PolkitSystemBusName: Add public API to retrieve Unix user

And change the duplicated code in the backend session monitors to use
it.  This just a code cleanup resulting from review after
CVE-2013-4288.  There's no security impact from this patch, it just
removes duplicated code.

https://bugs.freedesktop.org/show_bug.cgi?id=69538

4 files changed, 62 insertions, 38 deletions

diff --git a/src/polkit/polkitsystembusname.c b/src/polkit/polkitsystembusname.c
index 2a297c4..51e4a69 100644
--- a/src/polkit/polkitsystembusname.c
+++ b/src/polkit/polkitsystembusname.c
@@ -25,6 +25,7 @@
 
 #include <string.h>
 #include "polkitsystembusname.h"
+#include "polkitunixuser.h"
 #include "polkitsubject.h"
 #include "polkitprivate.h"
 
@@ -396,3 +397,58 @@ polkit_system_bus_name_get_process_sync (PolkitSystemBusName  *system_bus_name,
   return ret;
 }
 
+/**
+ * polkit_system_bus_name_get_user_sync:
+ * @system_bus_name: A #PolkitSystemBusName.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
+ * @error: (allow-none): Return location for error or %NULL.
+ *
+ * Synchronously gets a #PolkitUnixUser object for @system_bus_name;
+ * the calling thread is blocked until a reply is received.
+ *
+ * Returns: (allow-none) (transfer full): A #PolkitUnixUser object or %NULL if @error is set.
+ **/
+PolkitUnixUser *
+polkit_system_bus_name_get_user_sync (PolkitSystemBusName  *system_bus_name,
+				      GCancellable         *cancellable,
+				      GError              **error)
+{
+  GDBusConnection *connection;
+  PolkitUnixUser *ret;
+  GVariant *result;
+  guint32 uid;
+
+  g_return_val_if_fail (POLKIT_IS_SYSTEM_BUS_NAME (system_bus_name), NULL);
+  g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  ret = NULL;
+
+  connection = g_bus_get_sync (G_BUS_TYPE_SYSTEM, cancellable, error);
+  if (connection == NULL)
+    goto out;
+
+  result = g_dbus_connection_call_sync (connection,
+                                        "org.freedesktop.DBus",       /* name */
+                                        "/org/freedesktop/DBus",      /* object path */
+                                        "org.freedesktop.DBus",       /* interface name */
+                                        "GetConnectionUnixUser",      /* method */
+                                        g_variant_new ("(s)", system_bus_name->name),
+                                        G_VARIANT_TYPE ("(u)"),
+                                        G_DBUS_CALL_FLAGS_NONE,
+                                        -1,
+                                        cancellable,
+                                        error);
+  if (result == NULL)
+    goto out;
+
+  g_variant_get (result, "(u)", &uid);
+  g_variant_unref (result);
+
+  ret = (PolkitUnixUser*)polkit_unix_user_new (uid);
+
+ out:
+  if (connection != NULL)
+    g_object_unref (connection);
+  return ret;
+}
diff --git a/src/polkit/polkitsystembusname.h b/src/polkit/polkitsystembusname.h
index 1fc464f..38d31f7 100644
--- a/src/polkit/polkitsystembusname.h
+++ b/src/polkit/polkitsystembusname.h
@@ -56,6 +56,10 @@ PolkitSubject  *polkit_system_bus_name_get_process_sync   (PolkitSystemBusName
                                                            GCancellable         *cancellable,
                                                            GError              **error);
 
+PolkitUnixUser * polkit_system_bus_name_get_user_sync     (PolkitSystemBusName  *system_bus_name,
+							   GCancellable         *cancellable,
+							   GError              **error);
+
 G_END_DECLS
 
 #endif /* __POLKIT_SYSTEM_BUS_NAME_H */
diff --git a/src/polkitbackend/polkitbackendsessionmonitor-systemd.c b/src/polkitbackend/polkitbackendsessionmonitor-systemd.c
index 58593c3..0185310 100644
--- a/src/polkitbackend/polkitbackendsessionmonitor-systemd.c
+++ b/src/polkitbackend/polkitbackendsessionmonitor-systemd.c
@@ -277,25 +277,7 @@ polkit_backend_session_monitor_get_user_for_subject (PolkitBackendSessionMonitor
     }
   else if (POLKIT_IS_SYSTEM_BUS_NAME (subject))
     {
-      GVariant *result;
-
-      result = g_dbus_connection_call_sync (monitor->system_bus,
-                                            "org.freedesktop.DBus",
-                                            "/org/freedesktop/DBus",
-                                            "org.freedesktop.DBus",
-                                            "GetConnectionUnixUser",
-                                            g_variant_new ("(s)", polkit_system_bus_name_get_name (POLKIT_SYSTEM_BUS_NAME (subject))),
-                                            G_VARIANT_TYPE ("(u)"),
-                                            G_DBUS_CALL_FLAGS_NONE,
-                                            -1, /* timeout_msec */
-                                            NULL, /* GCancellable */
-                                            error);
-      if (result == NULL)
-        goto out;
-      g_variant_get (result, "(u)", &uid);
-      g_variant_unref (result);
-
-      ret = polkit_unix_user_new (uid);
+      ret = (PolkitIdentity*)polkit_system_bus_name_get_user_sync (POLKIT_SYSTEM_BUS_NAME (subject), NULL, error);
     }
   else if (POLKIT_IS_UNIX_SESSION (subject))
     {
diff --git a/src/polkitbackend/polkitbackendsessionmonitor.c b/src/polkitbackend/polkitbackendsessionmonitor.c
index 9c331b6..4075d3f 100644
--- a/src/polkitbackend/polkitbackendsessionmonitor.c
+++ b/src/polkitbackend/polkitbackendsessionmonitor.c
@@ -306,25 +306,7 @@ polkit_backend_session_monitor_get_user_for_subject (PolkitBackendSessionMonitor
     }
   else if (POLKIT_IS_SYSTEM_BUS_NAME (subject))
     {
-      GVariant *result;
-
-      result = g_dbus_connection_call_sync (monitor->system_bus,
-                                            "org.freedesktop.DBus",
-                                            "/org/freedesktop/DBus",
-                                            "org.freedesktop.DBus",
-                                            "GetConnectionUnixUser",
-                                            g_variant_new ("(s)", polkit_system_bus_name_get_name (POLKIT_SYSTEM_BUS_NAME (subject))),
-                                            G_VARIANT_TYPE ("(u)"),
-                                            G_DBUS_CALL_FLAGS_NONE,
-                                            -1, /* timeout_msec */
-                                            NULL, /* GCancellable */
-                                            error);
-      if (result == NULL)
-        goto out;
-      g_variant_get (result, "(u)", &uid);
-      g_variant_unref (result);
-
-      ret = polkit_unix_user_new (uid);
+      ret = (PolkitIdentity*)polkit_system_bus_name_get_user_sync (POLKIT_SYSTEM_BUS_NAME (subject));
     }
   else if (POLKIT_IS_UNIX_SESSION (subject))
     {