core: fix security and concurrency issues found in a backend audit (#2805)

* core: fix security and concurrency issues found in backend audit

Security:
- privesc: pipe the sudo password via stdin (sudo -S) instead of
  embedding it in the command string, so it no longer appears in argv
  (readable by any local user via /proc/<pid>/cmdline or ps)
- greeter: tokenize a session .desktop Exec= line into argv and execve
  directly instead of running it through /bin/sh -c, closing a command-
  injection path via user-writable ~/.local/share/wayland-sessions
- plugins: reject path-separator/.. in plugin id/name before joining
  into a filesystem path, closing an arbitrary-directory-delete in the
  uninstall/update fallback
- keybinds/hyprland: always quote unrecognized bind actions/keys when
  writing generated Lua; only re-emit genuine round-tripped custom Lua
  verbatim (tracked via an explicit flag), closing a Lua-injection path
- desktop/mimeapps: reject newline/bracket in mime/desktop-id fields so
  they can't inject fake sections into the shared mimeapps.list

Robustness / concurrency:
- server: recover panics in the request-dispatch path so one bad
  handler can't crash the daemon and drop every client
- go-wayland: recover panics in the shared dispatch choke point so a
  malformed compositor event can't crash CLI tools / the daemon
- server: per-connection D-Bus client ID instead of a shared constant,
  fixing cross-client signal delivery and subscription teardown
- network: guard the NetworkManager device maps with a mutex (a
  concurrent map read/write here is an unrecoverable fatal error)
- cups: close the event channel on Stop() so Unsubscribe() of the last
  subscriber no longer deadlocks; allocate the fresh channel in Start()
- freedesktop: reuse the shared session conn for the settings watcher
  and tear it down in Close(), fixing a per-Manager conn+goroutine leak
- clipboard: mutex-guard lazy dbusConn creation
- geolocation: use WithMatchMember for the GeoClue2 LocationUpdated
  signal (was WithMatchSender with an interface.member string, so the
  match never fired and live location updates never arrived)
- screenshot: set failed=true on buffer/pool creation errors so the
  dispatch loop doesn't wait forever for a ready/failed that never comes

* apply code review comments

---------

Co-authored-by: bbedward <bbedward@gmail.com>

core/internal/keybinds/providers/hyprland.go

@@ -299,6 +299,9 @@ type hyprlandOverrideBind struct {
 	Options     map[string]any
 	// Unbind: negative override (hl.unbind only, no rebind).
 	Unbind bool
+	// RawLuaAction: Action is a custom hl.* Lua expression round-tripped from an
+	// existing Lua override; re-emit it verbatim instead of quoting it.
+	RawLuaAction bool
 }
 
 func (h *HyprlandProvider) ensureWritableConfig() error {
@@ -1046,18 +1049,26 @@ func luaActionStringFromHyprlangAction(action string) string {
 	if expr, ok := luaActionStringFromKnownHyprlandAction(action); ok {
 		return expr
 	}
-	return action
+	// Unrecognized dispatchers are freeform text, not Lua; forward them to
+	// hyprctl quoted so a stray `"` can't produce broken Lua output.
+	return luaHyprctlDispatchFunction(action)
 }
 
-func luaExprToInternalAction(expr string) string {
+// luaExprToInternalAction converts a parsed Lua bind expression back into
+// "dispatcher params" text. isRawLua reports that expr matched no known hl.*
+// shape and must be re-emitted verbatim as Lua on write-back.
+func luaExprToInternalAction(expr string) (action string, isRawLua bool) {
 	d, p := luaExprToDispatcherParams(expr)
+	if d == expr && p == "" {
+		return expr, true
+	}
 	if d == "exec" && p != "" && !strings.HasPrefix(p, "hyprctl dispatch lua:") {
-		return "exec " + p
+		return "exec " + p, false
 	}
 	if p != "" {
-		return d + " " + p
+		return d + " " + p, false
 	}
-	return d
+	return d, false
 }
 
 func luaBindOptions(bind *hyprlandOverrideBind) []string {
@@ -1075,20 +1086,25 @@ func luaBindOptions(bind *hyprlandOverrideBind) []string {
 }
 
 func writeLuaBindLine(sb *strings.Builder, bind *hyprlandOverrideBind) {
-	key := formatLuaBindKey(bind.Key)
+	key := strconv.Quote(formatLuaBindKey(bind.Key))
 	if bind.Unbind {
-		fmt.Fprintf(sb, `hl.unbind("%s")`, key)
+		fmt.Fprintf(sb, `hl.unbind(%s)`, key)
 		sb.WriteByte('\n')
 		return
 	}
-	expr := luaActionStringFromHyprlangAction(bind.Action)
+	var expr string
+	if bind.RawLuaAction {
+		expr = bind.Action
+	} else {
+		expr = luaActionStringFromHyprlangAction(bind.Action)
+	}
 	opts := luaBindOptions(bind)
-	fmt.Fprintf(sb, `hl.unbind("%s")`, key)
+	fmt.Fprintf(sb, `hl.unbind(%s)`, key)
 	sb.WriteByte('\n')
 	if len(opts) > 0 {
-		fmt.Fprintf(sb, `hl.bind("%s", %s, { %s })`, key, expr, strings.Join(opts, ", "))
+		fmt.Fprintf(sb, `hl.bind(%s, %s, { %s })`, key, expr, strings.Join(opts, ", "))
 	} else {
-		fmt.Fprintf(sb, `hl.bind("%s", %s)`, key, expr)
+		fmt.Fprintf(sb, `hl.bind(%s, %s)`, key, expr)
 	}
 	sb.WriteByte('\n')
 }
@@ -1104,17 +1120,18 @@ func parseLuaBindOverrideLine(line string) (*hyprlandOverrideBind, bool) {
 	}
 	internalKey := luaKeyComboToInternalKey(kbc)
 
-	action := luaExprToInternalAction(actionExpr)
+	action, isRawLua := luaExprToInternalAction(actionExpr)
 	flags := luaBindOptFlags(optSuffix)
 	description := luaBindOptDescription(optSuffix)
 	if description == "" {
 		description = luaLineTrailingComment(line)
 	}
 	return &hyprlandOverrideBind{
-		Key:         internalKey,
-		Action:      action,
-		Description: description,
-		Flags:       flags,
+		Key:          internalKey,
+		Action:       action,
+		Description:  description,
+		Flags:        flags,
+		RawLuaAction: isRawLua,
 	}, true
 }
 

core/internal/keybinds/providers/hyprland_parser_test.go

@@ -147,9 +147,10 @@ hl.bind("SUPER + N", hl.dsp.exec_cmd("dms ipc call notepad toggle"), { descripti
 func TestWriteLuaBindLineLeavesCustomLuaDispatcherRaw(t *testing.T) {
 	var sb strings.Builder
 	writeLuaBindLine(&sb, &hyprlandOverrideBind{
-		Key:         "Super+u",
-		Action:      "hl.dsp.no_op()",
-		Description: "Custom Lua",
+		Key:          "Super+u",
+		Action:       "hl.dsp.no_op()",
+		Description:  "Custom Lua",
+		RawLuaAction: true,
 	})
 
 	want := `hl.unbind("SUPER + U")
@@ -159,6 +160,24 @@ hl.bind("SUPER + U", hl.dsp.no_op(), { description = "Custom Lua" })`
 	}
 }
 
+func TestWriteLuaBindLineQuotesUnrecognizedActionWithoutRawLuaFlag(t *testing.T) {
+	var sb strings.Builder
+	writeLuaBindLine(&sb, &hyprlandOverrideBind{
+		Key:    "Super+u",
+		Action: `customdispatcher "),os.execute("id")--`,
+	})
+
+	got := sb.String()
+	if !strings.Contains(got, "hl.exec_cmd(") {
+		t.Fatalf("expected unrecognized action to go through the hyprctl-dispatch wrapper, got %q", got)
+	}
+	// an unpaired bare quote means the action broke out of its string literal
+	withoutEscapedQuotes := strings.ReplaceAll(got, `\"`, "")
+	if n := strings.Count(withoutEscapedQuotes, `"`); n%2 != 0 {
+		t.Fatalf("action broke out of its string literal (%d unpaired quotes): %q", n, got)
+	}
+}
+
 func TestLuaActionStringFromHyprlangActionUsesNativeDispatchers(t *testing.T) {
 	tests := []struct {
 		action string
@@ -226,15 +245,12 @@ func TestParseLuaBindLineHandlesFunctionDispatcherFallback(t *testing.T) {
 	}
 }
 
-func TestLuaActionStringLeavesCustomLuaDispatcherRaw(t *testing.T) {
+func TestLuaActionStringFromHyprlangActionAlwaysQuotesUnrecognizedText(t *testing.T) {
 	got := luaActionStringFromHyprlangAction("hl.dsp.no_op()")
-	want := `hl.dsp.no_op()`
+	want := `function() hl.exec_cmd("hyprctl dispatch hl.dsp.no_op()") end`
 	if got != want {
 		t.Fatalf("luaActionStringFromHyprlangAction() = %q, want %q", got, want)
 	}
-	if strings.Contains(got, "hl.dispatch") || strings.Contains(got, "hyprctl dispatch") {
-		t.Fatalf("expected custom Lua dispatcher expression to stay raw, got %q", got)
-	}
 }
 
 func TestReadLuaOverrideMigratesTrailingCommentToDescription(t *testing.T) {