[gdm/wip/just-in-time-reauth] manager: explicitly disallow login screen from opening reauth channel

[Ray Strode <halfline src gnome org>]

commit 0c6174a35b7eb5f78bb3687400f7630f57e36185
Author: Ray Strode <rstrode redhat com>
Date:   Wed Feb 12 14:22:31 2014 -0500

    manager: explicitly disallow login screen from opening reauth channel
    
    It doesn't make sense for it to do, and right now the shell does it
    up front, waits for the failure, and then does the "right" thing
    (opens a new auth session) after.
    
    This commit makes the failure explicit, so we can subsequently make
    other cases where a reauth channel is requested work even if there is
    no session to channel to by implicitly creating a transient one just
    in time.  That will come later.

 daemon/gdm-manager.c |  104 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 104 insertions(+), 0 deletions(-)
---
diff --git a/daemon/gdm-manager.c b/daemon/gdm-manager.c
index 5108c37..b3b6370 100644
--- a/daemon/gdm-manager.c
+++ b/daemon/gdm-manager.c
@@ -272,6 +272,95 @@ lookup_by_session_id (const char *id,
         return res;
 }
 
+#ifdef WITH_CONSOLE_KIT
+static gboolean
+is_consolekit_login_session (GdmManager       *self,
+                             GDBusConnection  *connection,
+                             const char       *session_id,
+                             GError          **error)
+{
+        GVariant *reply;
+        char *session_type = NULL;
+
+        reply = g_dbus_connection_call_sync (connection,
+                                             "org.freedesktop.ConsoleKit",
+                                             session_id,
+                                             "org.freedesktop.ConsoleKit.Session",
+                                             "GetSessionType",
+                                             NULL,
+                                             G_VARIANT_TYPE ("(s)"),
+                                             G_DBUS_CALL_FLAGS_NONE,
+                                             -1,
+                                             NULL,
+                                             error);
+        if (reply == NULL) {
+                return FALSE;
+        }
+
+        g_variant_get (reply, "(s)", &session_type);
+        g_variant_unref (reply);
+
+        if (g_strcmp0 (session_type, "LoginWindow") != 0) {
+                g_free (session_type);
+
+                return FALSE;
+        }
+
+        g_free (session_type);
+        return TRUE;
+}
+#endif
+
+#ifdef WITH_SYSTEMD
+static gboolean
+is_systemd_login_session (GdmManager  *self,
+                          const char  *session_id,
+                          GError     **error)
+{
+        char *session_class = NULL;
+        int ret;
+
+        ret = sd_session_get_class (session_id, &session_class);
+
+        if (ret < 0) {
+                g_set_error (error,
+                             GDM_DISPLAY_ERROR,
+                             GDM_DISPLAY_ERROR_GETTING_SESSION_INFO,
+                             "Error getting class for session id %s from systemd: %s",
+                             session_id,
+                             g_strerror (-ret));
+                return FALSE;
+        }
+
+        if (g_strcmp0 (session_class, "greeter") != 0) {
+                g_free (session_class);
+                return FALSE;
+        }
+
+        g_free (session_class);
+        return TRUE;
+}
+#endif
+
+static gboolean
+is_login_session (GdmManager       *self,
+                  GDBusConnection  *connection,
+                  const char       *session_id,
+                  GError          **error)
+{
+#ifdef WITH_SYSTEMD
+        if (LOGIND_RUNNING()) {
+                return is_systemd_login_session (self, session_id, error);
+        }
+#endif
+
+#ifdef WITH_CONSOLE_KIT
+        return is_consolekit_login_session (self, connection, session_id, error);
+#endif
+
+        return FALSE;
+}
+
 static GdmDisplay *
 get_display_and_details_for_bus_sender (GdmManager       *self,
                             GDBusConnection  *connection,
@@ -285,6 +374,7 @@ get_display_and_details_for_bus_sender (GdmManager       *self,
         int         ret;
         GPid        pid;
         uid_t       caller_uid, session_uid;
+        gboolean    is_login_screen;
 
         ret = gdm_dbus_get_pid_for_name (sender, &pid, &error);
 
@@ -313,6 +403,20 @@ get_display_and_details_for_bus_sender (GdmManager       *self,
                 goto out;
         }
 
+        is_login_screen = is_login_session (self, connection, session_id, &error);
+
+        if (error != NULL) {
+                g_debug ("GdmManager: Error while checking if sender is login screen: %s",
+                         error->message);
+                g_error_free (error);
+                goto out;
+        }
+
+        if (is_login_screen) {
+                g_debug ("GdmManager: caller is login screen");
+                goto out;
+        }
+
         if (!get_uid_for_session_id (connection, session_id, &session_uid, &error)) {
                 g_debug ("GdmManager: Error while retrieving uid for session: %s",
                          error->message);