[gdm/fix-jump-back-to-login-screen: 11/21] manager: allow multiple xdmcp logins for the same user

[Ray Strode <halfline src gnome org>]

commit ec9f23ca25d296b9e32dedb4f1f5daa58b5d0cd1
Author: Ray Strode <rstrode redhat com>
Date:   Thu Dec 20 14:51:38 2018 -0500

    manager: allow multiple xdmcp logins for the same user

 common/gdm-settings-keys.h |  1 +
 daemon/gdm-manager.c       | 71 ++++++++++++++++++++++++++++++++++------------
 data/gdm.schemas.in        |  5 ++++
 3 files changed, 59 insertions(+), 18 deletions(-)
---
diff --git a/common/gdm-settings-keys.h b/common/gdm-settings-keys.h
index 87685d3cd..4b3a1ffeb 100644
--- a/common/gdm-settings-keys.h
+++ b/common/gdm-settings-keys.h
@@ -57,6 +57,7 @@ G_BEGIN_DECLS
 #define GDM_KEY_MAX_WAIT_INDIRECT "xdmcp/MaxWaitIndirect"
 #define GDM_KEY_PING_INTERVAL "xdmcp/PingIntervalSeconds"
 #define GDM_KEY_WILLING "xdmcp/Willing"
+#define GDM_KEY_ALLOW_MULTIPLE_SESSIONS_PER_USER "xdmcp/AllowMultipleSessionsPerUser"
 
 #define GDM_KEY_MULTICAST "chooser/Multicast"
 #define GDM_KEY_MULTICAST_ADDR "chooser/MulticastAddr"
diff --git a/daemon/gdm-manager.c b/daemon/gdm-manager.c
index cc61efc93..dc839aeb8 100644
--- a/daemon/gdm-manager.c
+++ b/daemon/gdm-manager.c
@@ -593,7 +593,7 @@ switch_to_compatible_user_session (GdmManager *manager,
         gboolean    ret;
         const char *username;
         const char *seat_id;
-        const char *ssid_to_activate;
+        const char *ssid_to_activate = NULL;
         GdmSession *existing_session;
 
         ret = FALSE;
@@ -601,31 +601,44 @@ switch_to_compatible_user_session (GdmManager *manager,
         username = gdm_session_get_username (session);
         seat_id = gdm_session_get_display_seat_id (session);
 
-        if (!fail_if_already_switched) {
-                session = NULL;
-        }
+        if (!fail_if_already_switched)
+                ssid_to_activate = gdm_session_get_session_id (session);
 
-        existing_session = find_session_for_user_on_seat (manager, username, seat_id, session);
+        if (ssid_to_activate == NULL) {
+                if (!seat_id || !sd_seat_can_multi_session (seat_id)) {
+                        g_debug ("GdmManager: unable to activate existing sessions from login screen unless 
on seat0");
+                        goto out;
+                }
 
-        if (existing_session != NULL) {
-                ssid_to_activate = gdm_session_get_session_id (existing_session);
-                if (seat_id != NULL) {
-                        res = gdm_activate_session_by_id (manager->priv->connection, seat_id, 
ssid_to_activate);
-                        if (! res) {
-                                g_debug ("GdmManager: unable to activate session: %s", ssid_to_activate);
-                                goto out;
-                        }
+                if (!fail_if_already_switched) {
+                        session = NULL;
                 }
 
-                res = session_unlock (manager, ssid_to_activate);
-                if (!res) {
-                        /* this isn't fatal */
-                        g_debug ("GdmManager: unable to unlock session: %s", ssid_to_activate);
+                existing_session = find_session_for_user_on_seat (manager, username, seat_id, session);
+
+                if (existing_session != NULL) {
+                        ssid_to_activate = gdm_session_get_session_id (existing_session);
                 }
-        } else {
+        }
+
+        if (ssid_to_activate == NULL) {
                 goto out;
         }
 
+        if (seat_id != NULL) {
+                res = gdm_activate_session_by_id (manager->priv->connection, seat_id, ssid_to_activate);
+                if (! res) {
+                        g_debug ("GdmManager: unable to activate session: %s", ssid_to_activate);
+                        goto out;
+                }
+        }
+
+        res = session_unlock (manager, ssid_to_activate);
+        if (!res) {
+                /* this isn't fatal */
+                g_debug ("GdmManager: unable to unlock session: %s", ssid_to_activate);
+        }
+
         ret = TRUE;
 
  out:
@@ -1116,6 +1129,20 @@ open_temporary_reauthentication_channel (GdmManager            *self,
         return g_strdup (address);
 }
 
+static gboolean
+remote_users_can_log_in_more_than_once (GdmManager *manager)
+{
+        gboolean enabled;
+
+        enabled = FALSE;
+
+        gdm_settings_direct_get_boolean (GDM_KEY_ALLOW_MULTIPLE_SESSIONS_PER_USER, &enabled);
+
+       g_debug ("GdmDisplay: Remote users allowed to log in more than once: %s", enabled? "yes" : "no");
+
+        return enabled;
+}
+
 static gboolean
 gdm_manager_handle_open_reauthentication_channel (GdmDBusManager        *manager,
                                                   GDBusMethodInvocation *invocation,
@@ -1148,6 +1175,14 @@ gdm_manager_handle_open_reauthentication_channel (GdmDBusManager        *manager
                 return TRUE;
         }
 
+        if (is_login_screen && is_remote && remote_users_can_log_in_more_than_once (self)) {
+                g_dbus_method_invocation_return_error_literal (invocation,
+                                                               G_DBUS_ERROR,
+                                                               G_DBUS_ERROR_ACCESS_DENIED,
+                                                               "Login screen creates new sessions for remote 
connections");
+                return TRUE;
+        }
+
         if (is_login_screen) {
                 g_debug ("GdmManager: looking for login screen session for user %s on seat %s", username, 
seat_id);
                 session = find_session_for_user_on_seat (self,
diff --git a/data/gdm.schemas.in b/data/gdm.schemas.in
index a1035f95e..929d13d90 100644
--- a/data/gdm.schemas.in
+++ b/data/gdm.schemas.in
@@ -139,6 +139,11 @@
       <signature>s</signature>
       <default>@gdmconfdir@/Xwilling</default>
     </schema>
+    <schema>
+      <key>xdmcp/AllowMultipleSessionsPerUser</key>
+      <signature>b</signature>
+      <default>false</default>
+    </schema>
   </schemalist>
 </gdmschemafile>