Merge branch 'benzea/fix-multiple-greeter-sessions' into 'master'

manager: Try looking up session based on PID first

See merge request GNOME/gdm!90

6 files changed, 53 insertions, 17 deletions

diff --git a/NEWS b/NEWS
index eba83b06..0ec0c08f 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,6 @@
+- Always use separate session bus for greeter sessions
+  This runs dbus-run-session, so the binary needs to be available
+
 ==============
 Version 3.34.1
 ==============
diff --git a/common/gdm-common.c b/common/gdm-common.c
index 41bdb389..b8de7555 100644
--- a/common/gdm-common.c
+++ b/common/gdm-common.c
@@ -497,7 +497,7 @@ goto_login_session (GDBusConnection  *connection,
          * since the data allocated is from libsystemd-logind, which
          * does not use GLib's g_malloc (). */
 
-        if (!gdm_find_display_session_for_uid (getuid (), &our_session, &local_error)) {
+        if (!gdm_find_display_session (0, getuid (), &our_session, &local_error)) {
                 g_propagate_prefixed_error (error, local_error, _("Could not identify the current session: "));
 
                 return FALSE;
@@ -898,16 +898,38 @@ _systemd_session_is_active (const char *session_id)
 }
 
 gboolean
-gdm_find_display_session_for_uid (const uid_t uid,
-                                  char      **out_session_id,
-                                  GError    **error)
+gdm_find_display_session (GPid        pid,
+                          const uid_t uid,
+                          char      **out_session_id,
+                          GError    **error)
 {
         char *local_session_id = NULL;
         g_auto(GStrv) sessions = NULL;
         int n_sessions;
+        int res;
 
         g_return_val_if_fail (out_session_id != NULL, FALSE);
 
+        /* First try to look up the session using the pid. We need this
+         * at least for the greeter, because it currently runs multiple
+         * sessions under the same user.
+         * See also commit 2b52d8933c8ab38e7ee83318da2363d00d8c5581
+         * which added an explicit dbus-run-session for all but seat0.
+         */
+        res = sd_pid_get_session (pid, &local_session_id);
+        if (res >= 0) {
+                g_debug ("GdmCommon: Found session %s for PID %d, using", local_session_id, pid);
+
+                *out_session_id = g_strdup (local_session_id);
+                free (local_session_id);
+
+                return TRUE;
+        } else {
+                if (res != -ENODATA)
+                        g_warning ("GdmCommon: Failed to retrieve session information for pid %d: %s",
+                                   pid, strerror (-res));
+        }
+
         g_debug ("Finding a graphical session for user %d", uid);
 
         n_sessions = sd_uid_get_sessions (uid,
diff --git a/common/gdm-common.h b/common/gdm-common.h
index 5c3fe137..001b70c1 100644
--- a/common/gdm-common.h
+++ b/common/gdm-common.h
@@ -51,9 +51,10 @@ int            gdm_wait_on_and_disown_pid (int pid,
 int            gdm_signal_pid            (int pid,
                                           int signal);
 
-gboolean       gdm_find_display_session_for_uid (const uid_t uid,
-                                                 char      **out_session_id,
-                                                 GError    **error);
+gboolean       gdm_find_display_session (GPid        pid,
+                                         const uid_t uid,
+                                         char      **out_session_id,
+                                         GError    **error);
 
 gboolean       gdm_get_pwent_for_name    (const char     *name,
                                           struct passwd **pwentp);
diff --git a/daemon/gdm-manager.c b/daemon/gdm-manager.c
index 907eca37..d8dfa843 100644
--- a/daemon/gdm-manager.c
+++ b/daemon/gdm-manager.c
@@ -501,7 +501,7 @@ get_display_and_details_for_bus_sender (GdmManager       *self,
                 goto out;
         }
 
-        ret = gdm_find_display_session_for_uid (caller_uid, &session_id, &error);
+        ret = gdm_find_display_session (pid, caller_uid, &session_id, &error);
 
         if (!ret) {
                 g_debug ("GdmManager: Unable to find display session for uid %d: %s",
diff --git a/daemon/gdm-session.c b/daemon/gdm-session.c
index 4e303e70..ca7d98f1 100644
--- a/daemon/gdm-session.c
+++ b/daemon/gdm-session.c
@@ -2900,23 +2900,33 @@ gdm_session_start_session (GdmSession *self,
 
                 g_free (command);
         } else {
+                /* FIXME:
+                 * Always use a separate DBus bus for each greeter session.
+                 * Firstly, this means that if we run multiple greeter session
+                 * (which we really should not do, but have to currently), then
+                 * each one will get its own DBus session bus.
+                 * But, we also explicitly do this for seat0, because that way
+                 * it cannot make use of systemd to run the GNOME session. This
+                 * prevents the session lookup logic from getting confused.
+                 * This has a similar effect as passing --builtin to gnome-session.
+                 *
+                 * We really should not be doing this. But the fix is to use
+                 * separate dynamically created users and that requires some
+                 * major refactorings.
+                 */
                 if (run_launcher) {
                         if (is_x11) {
-                                program = g_strdup_printf (LIBEXECDIR "/gdm-x-session %s\"%s\"",
+                                program = g_strdup_printf (LIBEXECDIR "/gdm-x-session %s\"dbus-run-session -- %s\"",
                                                            register_session ? "--register-session " : "",
                                                            self->selected_program);
                         } else {
-                                program = g_strdup_printf (LIBEXECDIR "/gdm-wayland-session %s\"%s\"",
+                                program = g_strdup_printf (LIBEXECDIR "/gdm-wayland-session %s\"dbus-run-session -- %s\"",
                                                            register_session ? "--register-session " : "",
                                                            self->selected_program);
                         }
                 } else {
-                        if (g_strcmp0 (self->display_seat_id, "seat0") != 0) {
-                                program = g_strdup_printf ("dbus-run-session -- %s",
-                                                           self->selected_program);
-                        } else {
-                                program = g_strdup (self->selected_program);
-                        }
+                        program = g_strdup_printf ("dbus-run-session -- %s",
+                                                   self->selected_program);
                 }
         }
 
diff --git a/libgdm/gdm-user-switching.c b/libgdm/gdm-user-switching.c
index 3a33fcbb..20235fd8 100644
--- a/libgdm/gdm-user-switching.c
+++ b/libgdm/gdm-user-switching.c
@@ -203,7 +203,7 @@ goto_login_session (GDBusConnection  *connection,
         /* Note that we mostly use free () here, instead of g_free ()
          * since the data allocated is from libsystemd-logind, which
          * does not use GLib's g_malloc (). */
-        if (!gdm_find_display_session_for_uid (getuid (), &our_session, &local_error)) {
+        if (!gdm_find_display_session (0, getuid (), &our_session, &local_error)) {
                 g_propagate_prefixed_error (error, local_error, _("Could not identify the current session: "));
 
                 return FALSE;