From 8bb2e2123ff8c4ae1fd77cf61a55c8ffcdae1444 Mon Sep 17 00:00:00 2001
From: John Lindgren <john@jlindgren.net>
Date: Sun, 15 Oct 2023 02:59:58 -0400
Subject: [PATCH] seat: move session-lock check down to seat_focus() level

We were checking for a locked session in desktop_focus_view(), but there
are several other call sites of seat_focus_surface() which were missing
such a check. Any one of those could cause the lock screen to lose focus
(making the session impossible to unlock) or another surface to gain it
(breaching the session lock).

To fix the issue, make any call to seat_focus_surface() no-op when the
session is locked. Add a specific seat_focus_lock_surface() function
which is the only way to bypass the check and is called only from
session-lock.c.
---
 include/labwc.h    |  7 +++++++
 src/desktop.c      |  8 +-------
 src/seat.c         | 32 ++++++++++++++++++++++++++------
 src/session-lock.c |  2 +-
 4 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/include/labwc.h b/include/labwc.h
index 8d0a1392..54fbe960 100644
--- a/include/labwc.h
+++ b/include/labwc.h
@@ -432,6 +432,13 @@ void seat_init(struct server *server);
 void seat_finish(struct server *server);
 void seat_reconfigure(struct server *server);
 void seat_focus_surface(struct seat *seat, struct wlr_surface *surface);
+
+/**
+ * seat_focus_lock_surface() - ONLY to be called from session-lock.c to
+ * focus lock screen surfaces. Use seat_focus_surface() otherwise.
+ */
+void seat_focus_lock_surface(struct seat *seat, struct wlr_surface *surface);
+
 void seat_set_focus_layer(struct seat *seat, struct wlr_layer_surface_v1 *layer);
 void seat_set_pressed(struct seat *seat, struct view *view,
 	struct wlr_scene_node *node, struct wlr_surface *surface,
diff --git a/src/desktop.c b/src/desktop.c
index 3672e270..607da49c 100644
--- a/src/desktop.c
+++ b/src/desktop.c
@@ -46,12 +46,6 @@ desktop_focus_view(struct view *view, bool raise)
 		return;
 	}
 
-	struct server *server = view->server;
-	if (input_inhibit_blocks_surface(&server->seat, view->surface->resource)
-			|| server->session_lock) {
-		return;
-	}
-
 	if (view->minimized) {
 		/*
 		 * Unminimizing will map the view which triggers a call to this
@@ -80,7 +74,7 @@ desktop_focus_view(struct view *view, bool raise)
 	 * that expect to be able to control focus themselves, but can't
 	 * under labwc since it's disallowed at the wlroots level.
 	 */
-	struct seat *seat = &server->seat;
+	struct seat *seat = &view->server->seat;
 	if (view->surface != seat->seat->keyboard_state.focused_surface) {
 		seat_focus_surface(seat, view->surface);
 	}
diff --git a/src/seat.c b/src/seat.c
index 7852180d..4387b817 100644
--- a/src/seat.c
+++ b/src/seat.c
@@ -472,13 +472,27 @@ seat_reconfigure(struct server *server)
 }
 
 static void
-seat_focus(struct seat *seat, struct wlr_surface *surface)
+seat_focus(struct seat *seat, struct wlr_surface *surface, bool is_lock_surface)
 {
+	/*
+	 * Respect session lock. This check is critical, DO NOT REMOVE.
+	 * It should also come before the !surface condition, or the
+	 * lock screen may lose focus and become impossible to unlock.
+	 */
+	struct server *server = seat->server;
+	if (server->session_lock && !is_lock_surface) {
+		return;
+	}
+
 	if (!surface) {
 		wlr_seat_keyboard_notify_clear_focus(seat->seat);
 		return;
 	}
-	struct wlr_keyboard *kb = &seat->keyboard_group->keyboard;
+
+	/* Respect input inhibit (also used by some lock screens) */
+	if (input_inhibit_blocks_surface(seat, surface->resource)) {
+		return;
+	}
 
 	/*
 	 * Key events associated with keybindings (both pressed and released)
@@ -490,10 +504,10 @@ seat_focus(struct seat *seat, struct wlr_surface *surface)
 	uint32_t *pressed_sent_keycodes = key_state_pressed_sent_keycodes();
 	int nr_pressed_sent_keycodes = key_state_nr_pressed_sent_keycodes();
 
+	struct wlr_keyboard *kb = &seat->keyboard_group->keyboard;
 	wlr_seat_keyboard_notify_enter(seat->seat, surface,
 		pressed_sent_keycodes, nr_pressed_sent_keycodes, &kb->modifiers);
 
-	struct server *server = seat->server;
 	struct wlr_pointer_constraint_v1 *constraint =
 		wlr_pointer_constraints_v1_constraint_for_surface(server->constraints,
 			surface, seat->seat);
@@ -503,12 +517,18 @@ seat_focus(struct seat *seat, struct wlr_surface *surface)
 void
 seat_focus_surface(struct seat *seat, struct wlr_surface *surface)
 {
-	/* Respect layer-shell exlusive keyboard-interactivity. */
+	/* Respect layer-shell exclusive keyboard-interactivity. */
 	if (seat->focused_layer && seat->focused_layer->current.keyboard_interactive
 			== ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_EXCLUSIVE) {
 		return;
 	}
-	seat_focus(seat, surface);
+	seat_focus(seat, surface, /*is_lock_surface*/ false);
+}
+
+void
+seat_focus_lock_surface(struct seat *seat, struct wlr_surface *surface)
+{
+	seat_focus(seat, surface, /*is_lock_surface*/ true);
 }
 
 void
@@ -519,7 +539,7 @@ seat_set_focus_layer(struct seat *seat, struct wlr_layer_surface_v1 *layer)
 		desktop_focus_topmost_view(seat->server);
 		return;
 	}
-	seat_focus(seat, layer->surface);
+	seat_focus(seat, layer->surface, /*is_lock_surface*/ false);
 	if (layer->current.layer >= ZWLR_LAYER_SHELL_V1_LAYER_TOP) {
 		seat->focused_layer = layer;
 	}
diff --git a/src/session-lock.c b/src/session-lock.c
index d3a3ca8a..0f4f8ef6 100644
--- a/src/session-lock.c
+++ b/src/session-lock.c
@@ -29,7 +29,7 @@ static void
 focus_surface(struct session_lock *lock, struct wlr_surface *focused)
 {
 	lock->focused = focused;
-	seat_focus_surface(&g_server->seat, focused);
+	seat_focus_lock_surface(&g_server->seat, focused);
 }
 
 static void