[gdm/gnome-3-24] manager: don't allow autologin from transient displays

[Ray Strode <halfline src gnome org>]

commit 16f646db418aff5b22984b1ea22f05d6e70e072d
Author: Ray Strode <rstrode redhat com>
Date:   Mon Sep 11 16:44:15 2017 -0400

    manager: don't allow autologin from transient displays
    
    In theory, we're only only supposed to allow autologin
    the first time a session is run, but we only count a
    session run, once it's finished.  This means that if a
    user creates a transient session to user switch, before
    they've logged out the first time at boot up, that
    transient session will begin autologin as well (which
    actually gets treated as an auto unlock).
    
    This commit makes sure autologin is only ever run on
    the initial display.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=783779

 daemon/gdm-manager.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/daemon/gdm-manager.c b/daemon/gdm-manager.c
index d080b30..6ef75bd 100644
--- a/daemon/gdm-manager.c
+++ b/daemon/gdm-manager.c
@@ -1573,10 +1573,13 @@ set_up_session (GdmManager *manager,
         ActUserManager *user_manager;
         ActUser *user;
         gboolean loaded;
+        gboolean is_initial_display = FALSE;
         gboolean autologin_enabled = FALSE;
         char *username = NULL;
 
-        if (!manager->priv->ran_once && display_is_on_seat0 (display))
+        g_object_get (G_OBJECT (display), "is-initial", &is_initial_display, NULL);
+
+        if (!manager->priv->ran_once && is_initial_display)
                 autologin_enabled = get_automatic_login_details (manager, &username);
 
         if (!autologin_enabled) {