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/desktop/mimeapps.go

@@ -133,6 +133,11 @@ func mergedAssociations() *MimeAssociations {
 	return merged
 }
 
+// isSafeIniField rejects values that would corrupt a key=value line in mimeapps.list
+func isSafeIniField(s string) bool {
+	return !strings.ContainsAny(s, "\n\r[]")
+}
+
 func writeUserMimeapps(update func(*MimeAssociations)) error {
 	mimeappsWriteMu.Lock()
 	defer mimeappsWriteMu.Unlock()
@@ -152,6 +157,7 @@ func writeUserMimeapps(update func(*MimeAssociations)) error {
 	var buf bytes.Buffer
 	w := bufio.NewWriter(&buf)
 
+	var writeErr error
 	writeSection := func(name string, entries map[string]string) {
 		fmt.Fprintf(w, "[%s]\n", name)
 		keys := make([]string, 0, len(entries))
@@ -160,7 +166,14 @@ func writeUserMimeapps(update func(*MimeAssociations)) error {
 		}
 		sort.Strings(keys)
 		for _, k := range keys {
-			fmt.Fprintf(w, "%s=%s\n", k, entries[k])
+			v := entries[k]
+			if !isSafeIniField(k) || !isSafeIniField(v) {
+				if writeErr == nil {
+					writeErr = fmt.Errorf("invalid mimeapps.list field %q=%q", k, v)
+				}
+				continue
+			}
+			fmt.Fprintf(w, "%s=%s\n", k, v)
 		}
 		fmt.Fprintln(w)
 	}
@@ -177,6 +190,10 @@ func writeUserMimeapps(update func(*MimeAssociations)) error {
 	writeSection(groupAdded, flatten(assoc.Added))
 	writeSection(groupRemoved, flatten(assoc.Removed))
 
+	if writeErr != nil {
+		return writeErr
+	}
+
 	if err := w.Flush(); err != nil {
 		return err
 	}

core/internal/geolocation/client_geoclue.go

@@ -132,7 +132,7 @@ func (c *GeoClueClient) startSignalPump() error {
 	if err := c.dbusConn.AddMatchSignal(
 		dbus.WithMatchObjectPath(c.clientPath),
 		dbus.WithMatchInterface(dbusGeoClueClientInterface),
-		dbus.WithMatchSender(dbusGeoClueClientLocationUpdated),
+		dbus.WithMatchMember("LocationUpdated"),
 	); err != nil {
 		return err
 	}

core/internal/greeter/installer.go

@@ -529,11 +529,23 @@ func execFromDesktopFile(path string) (string, error) {
 	if err != nil {
 		return "", err
 	}
+	inDesktopEntry := false
 	for line := range strings.SplitSeq(string(data), "\n") {
 		trimmed := strings.TrimSpace(line)
-		if strings.HasPrefix(trimmed, "Exec=") {
-			return strings.TrimSpace(trimmed[len("Exec="):]), nil
+		switch {
+		case trimmed == "" || strings.HasPrefix(trimmed, "#"):
+			continue
+		case strings.HasPrefix(trimmed, "[") && strings.HasSuffix(trimmed, "]"):
+			inDesktopEntry = trimmed == "[Desktop Entry]"
+			continue
+		case !inDesktopEntry:
+			continue
 		}
+		key, value, found := strings.Cut(trimmed, "=")
+		if !found || strings.TrimSpace(key) != "Exec" {
+			continue
+		}
+		return strings.TrimSpace(value), nil
 	}
 	return "", fmt.Errorf("no Exec= line found in %s", path)
 }

core/internal/greeter/session_launcher.go

@@ -3,6 +3,7 @@ package greeter
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 	"syscall"
@@ -93,18 +94,95 @@ func resolveSessionExecInDirs(sessionID string, dirs []string) (string, error) {
 	return "", fmt.Errorf("session desktop file %q was not found", id)
 }
 
+// parseExecString splits a Desktop Entry Exec= value into argv without
+// involving a shell, mirroring quickshell's DesktopEntry::parseExecString
+// (string quoting, value escapes, field code stripping).
+func parseExecString(execLine string) []string {
+	var args []string
+	var cur strings.Builder
+	inString := false
+	escape := 0
+	percent := false
+
+	for _, c := range execLine {
+		switch {
+		case escape == 0 && c == '\\':
+			escape = 1
+		case inString:
+			switch {
+			case c == '\\':
+				escape++
+				if escape == 4 {
+					cur.WriteByte('\\')
+					escape = 0
+				}
+			case escape == 2:
+				cur.WriteRune(c)
+				escape = 0
+			case escape != 0:
+				switch c {
+				case 's':
+					cur.WriteByte(' ')
+				case 'n':
+					cur.WriteByte('\n')
+				case 't':
+					cur.WriteByte('\t')
+				case 'r':
+					cur.WriteByte('\r')
+				default:
+					cur.WriteRune(c)
+				}
+				escape = 0
+			case c == '"' || c == '\'':
+				inString = false
+			default:
+				cur.WriteRune(c)
+			}
+		case escape != 0:
+			cur.WriteRune(c)
+			escape = 0
+		case percent:
+			if c == '%' {
+				cur.WriteByte('%')
+			}
+			percent = false
+		case c == '%':
+			percent = true
+		case c == '"' || c == '\'':
+			inString = true
+		case c == ' ':
+			if cur.Len() > 0 {
+				args = append(args, cur.String())
+				cur.Reset()
+			}
+		default:
+			cur.WriteRune(c)
+		}
+	}
+	if cur.Len() > 0 {
+		args = append(args, cur.String())
+	}
+	return args
+}
+
 func LaunchSessionByID(sessionID string) error {
 	execLine, err := ResolveSessionExec(sessionID)
 	if err != nil {
 		return err
 	}
-	execLine = strings.TrimSpace(stripDesktopExecCodes(execLine))
-	if execLine == "" {
+
+	argv := parseExecString(strings.TrimSpace(execLine))
+	if len(argv) == 0 {
 		return fmt.Errorf("session %q has an empty Exec command", sessionID)
 	}
 
+	resolved, err := exec.LookPath(argv[0])
+	if err != nil {
+		return fmt.Errorf("session %q command %q not found: %w", sessionID, argv[0], err)
+	}
+
 	env := append(os.Environ(), "XDG_SESSION_TYPE=wayland")
-	return syscall.Exec("/bin/sh", []string{"sh", "-c", "exec " + execLine}, env)
+	return syscall.Exec(resolved, argv, env)
 }
 
 func LaunchSessionFromMemory(cacheDir, homeDir string) error {

core/internal/greeter/session_launcher_test.go

@@ -0,0 +1,57 @@
+package greeter
+
+import (
+	"path/filepath"
+	"reflect"
+	"testing"
+)
+
+func TestParseExecString(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		exec string
+		want []string
+	}{
+		{"plain", "niri --session", []string{"niri", "--session"}},
+		{"extra spaces", "niri   --session", []string{"niri", "--session"}},
+		{"double quoted arg", `env "with space" run`, []string{"env", "with space", "run"}},
+		{"single quoted arg", `env 'with space' run`, []string{"env", "with space", "run"}},
+		{"escaped quote in quotes", `sh "say \\"hi\\""`, []string{"sh", `say "hi"`}},
+		{"field code dropped", "gnome-session %U", []string{"gnome-session"}},
+		{"field code mid-arg", "app --url=%u --run", []string{"app", "--url=", "--run"}},
+		{"literal percent", "app 100%% done", []string{"app", "100%", "done"}},
+		{"shell metachars stay literal", "sh -c $(reboot); echo", []string{"sh", "-c", "$(reboot);", "echo"}},
+		{"empty", "", nil},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := parseExecString(tt.exec); !reflect.DeepEqual(got, tt.want) {
+				t.Fatalf("parseExecString(%q) = %#v, want %#v", tt.exec, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestExecFromDesktopFileOnlyReadsDesktopEntryGroup(t *testing.T) {
+	t.Parallel()
+
+	path := filepath.Join(t.TempDir(), "example.desktop")
+	writeTestFile(t, path, `[Desktop Action other]
+Exec=/wrong/binary
+
+[Desktop Entry]
+Name=Example
+Exec = /right/binary --flag
+`)
+
+	got, err := execFromDesktopFile(path)
+	if err != nil {
+		t.Fatalf("execFromDesktopFile returned error: %v", err)
+	}
+	if got != "/right/binary --flag" {
+		t.Fatalf("execFromDesktopFile = %q, want %q", got, "/right/binary --flag")
+	}
+}

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) {

core/internal/plugins/manager.go

@@ -64,7 +64,20 @@ func (m *Manager) findInstalledPath(pluginID string) (string, error) {
 	return m.findInDir(systemDir, pluginID)
 }
 
+// isSafePluginPathComponent rejects ids that aren't a single path component,
+// so filepath.Join can't resolve (and later RemoveAll) outside the plugins dir
+func isSafePluginPathComponent(s string) bool {
+	if s == "" || s == "." || s == ".." {
+		return false
+	}
+	return !strings.ContainsAny(s, "/\\")
+}
+
 func (m *Manager) findInDir(dir, pluginID string) (string, error) {
+	if !isSafePluginPathComponent(pluginID) {
+		return "", fmt.Errorf("invalid plugin id: %q", pluginID)
+	}
+
 	// First, check if folder with exact ID name exists
 	exactPath := filepath.Join(dir, pluginID)
 	if exists, _ := afero.DirExists(m.fs, exactPath); exists {
@@ -507,6 +520,10 @@ func (m *Manager) findInstalledPathByIDOrName(idOrName string) (string, error) {
 }
 
 func (m *Manager) findInDirByIDOrName(dir, idOrName string) (string, error) {
+	if !isSafePluginPathComponent(idOrName) {
+		return "", fmt.Errorf("invalid plugin id/name: %q", idOrName)
+	}
+
 	// Check exact folder name match first
 	exactPath := filepath.Join(dir, idOrName)
 	if exists, _ := afero.DirExists(m.fs, exactPath); exists {

core/internal/privesc/privesc.go

@@ -135,15 +135,14 @@ func EscapeSingleQuotes(s string) string {
 }
 
 // MakeCommand returns a bash command string that runs `command` with the
-// detected tool. When the tool supports stdin passwords and password is
-// non-empty, the password is piped in. Otherwise the tool is invoked with
-// no non-interactive flag so that an interactive TTY prompt is still
-// possible for CLI callers.
+// detected tool, prompting interactively on a TTY where applicable. The
+// sudo-with-password case lives in ExecCommand, which pipes the password via
+// stdin so it never lands in argv.
 //
 // If detection fails, the returned shell string exits 1 with an error
 // message so callers that treat the *exec.Cmd as infallible still fail
 // deterministically.
-func MakeCommand(password, command string) string {
+func MakeCommand(command string) string {
 	t, err := Detect()
 	if err != nil {
 		return failingShell(err)
@@ -151,9 +150,6 @@ func MakeCommand(password, command string) string {
 
 	switch t {
 	case ToolSudo:
-		if password != "" {
-			return fmt.Sprintf("echo '%s' | sudo -S %s", EscapeSingleQuotes(password), command)
-		}
 		return fmt.Sprintf("sudo %s", command)
 	case ToolDoas:
 		return fmt.Sprintf("doas sh -c '%s'", EscapeSingleQuotes(command))
@@ -166,9 +162,19 @@ func MakeCommand(password, command string) string {
 
 // ExecCommand builds an exec.Cmd that runs `command` as root via the
 // detected tool. Detection errors surface at Run() time as a failing
-// command writing a clear error to stderr.
+// command writing a clear error to stderr. A sudo password is piped via
+// stdin (sudo -S) so it never appears in argv.
 func ExecCommand(ctx context.Context, password, command string) *exec.Cmd {
-	return exec.CommandContext(ctx, "bash", "-c", MakeCommand(password, command))
+	t, err := Detect()
+	if err != nil {
+		return exec.CommandContext(ctx, "bash", "-c", failingShell(err))
+	}
+	if t == ToolSudo && password != "" {
+		cmd := exec.CommandContext(ctx, "sudo", "-S", "sh", "-c", command)
+		cmd.Stdin = strings.NewReader(password + "\n")
+		return cmd
+	}
+	return exec.CommandContext(ctx, "bash", "-c", MakeCommand(command))
 }
 
 // ExecArgv builds an exec.Cmd that runs argv as root via the detected tool.

core/internal/screenshot/screenshot.go

@@ -747,12 +747,16 @@ func (s *Screenshoter) processFrame(frame *wlr_screencopy.ZwlrScreencopyFrameV1,
 		bpp := format.BytesPerPixel()
 		if int(e.Stride) < int(e.Width)*bpp {
 			log.Error("invalid stride from compositor", "stride", e.Stride, "width", e.Width, "bpp", bpp)
+			// bail out here or the dispatch loop waits forever on a ready/failed
+			// event that never comes (frame.Copy is never called)
+			failed = true
 			return
 		}
 		var err error
 		buf, err = CreateShmBuffer(int(e.Width), int(e.Height), int(e.Stride))
 		if err != nil {
 			log.Error("failed to create buffer", "err", err)
+			failed = true
 			return
 		}
 		buf.Format = format
@@ -771,6 +775,7 @@ func (s *Screenshoter) processFrame(frame *wlr_screencopy.ZwlrScreencopyFrameV1,
 		pool, err = s.shm.CreatePool(buf.Fd(), int32(buf.Size()))
 		if err != nil {
 			log.Error("failed to create pool", "err", err)
+			failed = true
 			return
 		}
 
@@ -779,6 +784,7 @@ func (s *Screenshoter) processFrame(frame *wlr_screencopy.ZwlrScreencopyFrameV1,
 			pool.Destroy()
 			pool = nil
 			log.Error("failed to create wl_buffer", "err", err)
+			failed = true
 			return
 		}
 

core/internal/server/clipboard/manager.go

@@ -1839,21 +1839,34 @@ func (m *Manager) EntryToFile(entry *Entry) string {
 	return ""
 }
 
+func (m *Manager) dbusConnForFlatpak() (*dbus.Conn, error) {
+	m.dbusConnMutex.Lock()
+	defer m.dbusConnMutex.Unlock()
+
+	if m.dbusConn != nil {
+		return m.dbusConn, nil
+	}
+
+	conn, err := dbus.ConnectSessionBus()
+	if err != nil {
+		return nil, fmt.Errorf("connect session bus: %w", err)
+	}
+	if !conn.SupportsUnixFDs() {
+		conn.Close()
+		return nil, fmt.Errorf("D-Bus connection does not support Unix FD passing")
+	}
+	m.dbusConn = conn
+	return conn, nil
+}
+
 func (m *Manager) ExportFileForFlatpak(filePath string) (string, error) {
 	if _, err := os.Stat(filePath); err != nil {
 		return "", fmt.Errorf("file not found: %w", err)
 	}
 
-	if m.dbusConn == nil {
-		conn, err := dbus.ConnectSessionBus()
-		if err != nil {
-			return "", fmt.Errorf("connect session bus: %w", err)
-		}
-		if !conn.SupportsUnixFDs() {
-			conn.Close()
-			return "", fmt.Errorf("D-Bus connection does not support Unix FD passing")
-		}
-		m.dbusConn = conn
+	dbusConn, err := m.dbusConnForFlatpak()
+	if err != nil {
+		return "", err
 	}
 
 	file, err := os.Open(filePath)
@@ -1862,7 +1875,7 @@ func (m *Manager) ExportFileForFlatpak(filePath string) (string, error) {
 	}
 	fd := int(file.Fd())
 
-	portal := m.dbusConn.Object("org.freedesktop.portal.Documents", "/org/freedesktop/portal/documents")
+	portal := dbusConn.Object("org.freedesktop.portal.Documents", "/org/freedesktop/portal/documents")
 
 	var docIds []string
 	var extra map[string]dbus.Variant

core/internal/server/clipboard/types.go

@@ -153,7 +153,9 @@ type Manager struct {
 	notifierWg  sync.WaitGroup
 	lastState   *State
 
-	dbusConn *dbus.Conn
+	// lazily created by dbusConnForFlatpak under dbusConnMutex
+	dbusConn      *dbus.Conn
+	dbusConnMutex sync.Mutex
 }
 
 func (m *Manager) GetState() State {

core/internal/server/cups/subscription.go

@@ -37,6 +37,9 @@ func (sm *SubscriptionManager) Start() error {
 		return fmt.Errorf("subscription manager already running")
 	}
 	sm.running = true
+	// replace the channel closed by the previous Stop(); doing it here rather
+	// than in Stop() guarantees a lagging eventHandler still observes the close
+	sm.eventChan = make(chan SubscriptionEvent, 100)
 	sm.mu.Unlock()
 
 	subID, err := sm.createSubscription()
@@ -206,6 +209,8 @@ func (sm *SubscriptionManager) parseEvent(attrs ipp.Attributes) SubscriptionEven
 }
 
 func (sm *SubscriptionManager) Events() <-chan SubscriptionEvent {
+	sm.mu.Lock()
+	defer sm.mu.Unlock()
 	return sm.eventChan
 }
 
@@ -228,6 +233,13 @@ func (sm *SubscriptionManager) Stop() {
 	}
 
 	sm.stopChan = make(chan struct{})
+
+	// the writer (notificationLoop) joined above, so closing is safe; without
+	// this close Manager.eventHandler never returns and Unsubscribe deadlocks
+	// on eventWG.Wait(). Start() allocates the replacement.
+	sm.mu.Lock()
+	close(sm.eventChan)
+	sm.mu.Unlock()
 }
 
 func (sm *SubscriptionManager) cancelSubscription() {

core/internal/server/cups/subscription_dbus.go

@@ -38,6 +38,8 @@ func (sm *DBusSubscriptionManager) Start() error {
 		return fmt.Errorf("subscription manager already running")
 	}
 	sm.running = true
+	// replaced here rather than in Stop(); see SubscriptionManager.Start()
+	sm.eventChan = make(chan SubscriptionEvent, 100)
 	sm.mu.Unlock()
 
 	conn, err := dbus.ConnectSystemBus()
@@ -252,6 +254,8 @@ func (sm *DBusSubscriptionManager) parseDBusSignal(sig *dbus.Signal) Subscriptio
 }
 
 func (sm *DBusSubscriptionManager) Events() <-chan SubscriptionEvent {
+	sm.mu.Lock()
+	defer sm.mu.Unlock()
 	return sm.eventChan
 }
 
@@ -278,6 +282,12 @@ func (sm *DBusSubscriptionManager) Stop() {
 	}
 
 	sm.stopChan = make(chan struct{})
+
+	// the writer (dbusListenerLoop) joined above, so closing is safe; see
+	// SubscriptionManager.Stop()
+	sm.mu.Lock()
+	close(sm.eventChan)
+	sm.mu.Unlock()
 }
 
 func (sm *DBusSubscriptionManager) cancelSubscription() {

core/internal/server/dbus/handlers.go

@@ -201,6 +201,10 @@ func handleListNames(conn net.Conn, req models.Request, m *Manager) {
 }
 
 func handleSubscribe(conn net.Conn, req models.Request, m *Manager, clientID string) {
+	if id := params.StringOpt(req.Params, "clientId", ""); id != "" {
+		clientID = id
+	}
+
 	bus, err := params.String(req.Params, "bus")
 	if err != nil {
 		models.RespondError(conn, req.ID, err.Error())

core/internal/server/freedesktop/manager.go

@@ -137,22 +137,25 @@ func (m *Manager) consumeSelfEcho(value uint32) bool {
 }
 
 func (m *Manager) watchSettingsChanges() {
-	conn, err := dbus.ConnectSessionBus()
-	if err != nil {
-		log.Warnf("color-scheme watcher: session bus connect: %v", err)
+	// reuse the shared session connection; a dedicated one was unreachable
+	// from Close() and leaked with this goroutine
+	if m.sessionConn == nil {
 		return
 	}
+	conn := m.sessionConn
 
 	if err := conn.AddMatchSignal(
 		dbus.WithMatchInterface(dbusPortalSettingsInterface),
 		dbus.WithMatchMember("SettingChanged"),
 	); err != nil {
 		log.Warnf("Failed to watch portal settings changes: %v", err)
-		conn.Close()
 		return
 	}
 
 	signals := make(chan *dbus.Signal, 64)
+	m.stateMutex.Lock()
+	m.settingsSignals = signals
+	m.stateMutex.Unlock()
 	conn.Signal(signals)
 
 	for sig := range signals {
@@ -309,6 +312,18 @@ func (m *Manager) Close() {
 		m.systemConn.Close()
 	}
 	if m.sessionConn != nil {
+		m.sessionConn.RemoveMatchSignal(
+			dbus.WithMatchInterface(dbusPortalSettingsInterface),
+			dbus.WithMatchMember("SettingChanged"),
+		)
+		m.stateMutex.Lock()
+		signals := m.settingsSignals
+		m.settingsSignals = nil
+		m.stateMutex.Unlock()
+		if signals != nil {
+			m.sessionConn.RemoveSignal(signals)
+			close(signals)
+		}
 		m.sessionConn.Close()
 	}
 }

core/internal/server/freedesktop/types.go

@@ -71,4 +71,6 @@ type Manager struct {
 	screensaverGnomeClaimed       bool
 	selfEchoMu                    sync.Mutex
 	selfEchoes                    []colorSchemeEcho
+	// registered on sessionConn by watchSettingsChanges; guarded by stateMutex
+	settingsSignals chan *dbus.Signal
 }

core/internal/server/network/backend_networkmanager.go

@@ -2,6 +2,7 @@ package network
 
 import (
 	"fmt"
+	"maps"
 	"sync"
 
 	"github.com/AvengeMedia/DankMaterialShell/core/internal/log"
@@ -57,6 +58,11 @@ type NetworkManagerBackend struct {
 	wifiDev         any
 	wifiDevices     map[string]*wifiDeviceInfo
 
+	// devMutex guards ethernetDevices/wifiDevices (written by the signal pump,
+	// read by request handlers). Not reentrant — never hold it across calls
+	// into other backend methods.
+	devMutex sync.RWMutex
+
 	dbusConn *dbus.Conn
 	signals  chan *dbus.Signal
 	sigWG    sync.WaitGroup
@@ -185,12 +191,12 @@ func (b *NetworkManagerBackend) Initialize() error {
 			}
 			hwAddr, _ := w.GetPropertyHwAddress()
 
-			b.ethernetDevices[iface] = &ethernetDeviceInfo{
+			b.setEthernetDeviceInfo(iface, &ethernetDeviceInfo{
 				device:    dev,
 				wired:     w,
 				name:      iface,
 				hwAddress: hwAddr,
-			}
+			})
 
 			if b.ethernetDevice == nil {
 				b.ethernetDevice = dev
@@ -214,12 +220,12 @@ func (b *NetworkManagerBackend) Initialize() error {
 			}
 			hwAddr, _ := w.GetPropertyHwAddress()
 
-			b.wifiDevices[iface] = &wifiDeviceInfo{
+			b.setWifiDeviceInfo(iface, &wifiDeviceInfo{
 				device:    dev,
 				wireless:  w,
 				name:      iface,
 				hwAddress: hwAddr,
-			}
+			})
 
 			if b.wifiDevice == nil {
 				b.wifiDevice = dev
@@ -267,6 +273,80 @@ func (b *NetworkManagerBackend) Initialize() error {
 	return nil
 }
 
+func (b *NetworkManagerBackend) ethernetDevicesSnapshot() map[string]*ethernetDeviceInfo {
+	b.devMutex.RLock()
+	defer b.devMutex.RUnlock()
+	out := make(map[string]*ethernetDeviceInfo, len(b.ethernetDevices))
+	maps.Copy(out, b.ethernetDevices)
+	return out
+}
+
+func (b *NetworkManagerBackend) wifiDevicesSnapshot() map[string]*wifiDeviceInfo {
+	b.devMutex.RLock()
+	defer b.devMutex.RUnlock()
+	out := make(map[string]*wifiDeviceInfo, len(b.wifiDevices))
+	maps.Copy(out, b.wifiDevices)
+	return out
+}
+
+func (b *NetworkManagerBackend) ethernetDeviceByIface(iface string) (*ethernetDeviceInfo, bool) {
+	b.devMutex.RLock()
+	defer b.devMutex.RUnlock()
+	info, ok := b.ethernetDevices[iface]
+	return info, ok
+}
+
+func (b *NetworkManagerBackend) wifiDeviceByIface(iface string) (*wifiDeviceInfo, bool) {
+	b.devMutex.RLock()
+	defer b.devMutex.RUnlock()
+	info, ok := b.wifiDevices[iface]
+	return info, ok
+}
+
+func (b *NetworkManagerBackend) setEthernetDeviceInfo(iface string, info *ethernetDeviceInfo) {
+	b.devMutex.Lock()
+	b.ethernetDevices[iface] = info
+	b.devMutex.Unlock()
+}
+
+func (b *NetworkManagerBackend) setWifiDeviceInfo(iface string, info *wifiDeviceInfo) {
+	b.devMutex.Lock()
+	b.wifiDevices[iface] = info
+	b.devMutex.Unlock()
+}
+
+// removeEthernetDeviceByPath deletes the device and returns a snapshot of
+// what's left so the caller can pick a replacement without holding devMutex
+func (b *NetworkManagerBackend) removeEthernetDeviceByPath(path dbus.ObjectPath) (removed *ethernetDeviceInfo, remaining map[string]*ethernetDeviceInfo, found bool) {
+	b.devMutex.Lock()
+	defer b.devMutex.Unlock()
+	for iface, info := range b.ethernetDevices {
+		if info.device.GetPath() != path {
+			continue
+		}
+		delete(b.ethernetDevices, iface)
+		remaining = make(map[string]*ethernetDeviceInfo, len(b.ethernetDevices))
+		maps.Copy(remaining, b.ethernetDevices)
+		return info, remaining, true
+	}
+	return nil, nil, false
+}
+
+func (b *NetworkManagerBackend) removeWifiDeviceByPath(path dbus.ObjectPath) (removed *wifiDeviceInfo, remaining map[string]*wifiDeviceInfo, found bool) {
+	b.devMutex.Lock()
+	defer b.devMutex.Unlock()
+	for iface, info := range b.wifiDevices {
+		if info.device.GetPath() != path {
+			continue
+		}
+		delete(b.wifiDevices, iface)
+		remaining = make(map[string]*wifiDeviceInfo, len(b.wifiDevices))
+		maps.Copy(remaining, b.wifiDevices)
+		return info, remaining, true
+	}
+	return nil, nil, false
+}
+
 func (b *NetworkManagerBackend) Close() {
 	close(b.stopChan)
 	b.StopMonitoring()

core/internal/server/network/backend_networkmanager_ethernet.go

@@ -323,7 +323,7 @@ func (b *NetworkManagerBackend) GetEthernetDevices() []EthernetDevice {
 }
 
 func (b *NetworkManagerBackend) DisconnectEthernetDevice(device string) error {
-	info, ok := b.ethernetDevices[device]
+	info, ok := b.ethernetDeviceByIface(device)
 	if !ok {
 		return fmt.Errorf("ethernet device %s not found", device)
 	}
@@ -345,9 +345,10 @@ func (b *NetworkManagerBackend) DisconnectEthernetDevice(device string) error {
 }
 
 func (b *NetworkManagerBackend) updateAllEthernetDevices() {
-	devices := make([]EthernetDevice, 0, len(b.ethernetDevices))
+	ethernetDevices := b.ethernetDevicesSnapshot()
+	devices := make([]EthernetDevice, 0, len(ethernetDevices))
 
-	for name, info := range b.ethernetDevices {
+	for name, info := range ethernetDevices {
 		state, _ := info.device.GetPropertyState()
 		connected := state == gonetworkmanager.NmDeviceStateActivated
 		driver, _ := info.device.GetPropertyDriver()

core/internal/server/network/backend_networkmanager_signals.go

@@ -112,7 +112,7 @@ func (b *NetworkManagerBackend) startSignalPump() error {
 		return err
 	}
 
-	for _, info := range b.wifiDevices {
+	for _, info := range b.wifiDevicesSnapshot() {
 		if err := conn.AddMatchSignal(
 			dbus.WithMatchObjectPath(dbus.ObjectPath(info.device.GetPath())),
 			dbus.WithMatchInterface(dbusPropsInterface),
@@ -124,7 +124,7 @@ func (b *NetworkManagerBackend) startSignalPump() error {
 		}
 	}
 
-	for _, info := range b.ethernetDevices {
+	for _, info := range b.ethernetDevicesSnapshot() {
 		if err := conn.AddMatchSignal(
 			dbus.WithMatchObjectPath(dbus.ObjectPath(info.device.GetPath())),
 			dbus.WithMatchInterface(dbusPropsInterface),
@@ -227,7 +227,7 @@ func (b *NetworkManagerBackend) stopSignalPump() {
 		dbus.WithMatchMember("StateChanged"),
 	)
 
-	for _, info := range b.wifiDevices {
+	for _, info := range b.wifiDevicesSnapshot() {
 		b.dbusConn.RemoveMatchSignal(
 			dbus.WithMatchObjectPath(dbus.ObjectPath(info.device.GetPath())),
 			dbus.WithMatchInterface(dbusPropsInterface),
@@ -235,7 +235,7 @@ func (b *NetworkManagerBackend) stopSignalPump() {
 		)
 	}
 
-	for _, info := range b.ethernetDevices {
+	for _, info := range b.ethernetDevicesSnapshot() {
 		b.dbusConn.RemoveMatchSignal(
 			dbus.WithMatchObjectPath(dbus.ObjectPath(info.device.GetPath())),
 			dbus.WithMatchInterface(dbusPropsInterface),
@@ -550,12 +550,12 @@ func (b *NetworkManagerBackend) handleDeviceAdded(devicePath dbus.ObjectPath) {
 		}
 		hwAddr, _ := w.GetPropertyHwAddress()
 
-		b.ethernetDevices[iface] = &ethernetDeviceInfo{
+		b.setEthernetDeviceInfo(iface, &ethernetDeviceInfo{
 			device:    dev,
 			wired:     w,
 			name:      iface,
 			hwAddress: hwAddr,
-		}
+		})
 
 		if b.ethernetDevice == nil {
 			b.ethernetDevice = dev
@@ -573,12 +573,12 @@ func (b *NetworkManagerBackend) handleDeviceAdded(devicePath dbus.ObjectPath) {
 		}
 		hwAddr, _ := w.GetPropertyHwAddress()
 
-		b.wifiDevices[iface] = &wifiDeviceInfo{
+		b.setWifiDeviceInfo(iface, &wifiDeviceInfo{
 			device:    dev,
 			wireless:  w,
 			name:      iface,
 			hwAddress: hwAddr,
-		}
+		})
 
 		if b.wifiDevice == nil {
 			b.wifiDevice = dev
@@ -603,57 +603,49 @@ func (b *NetworkManagerBackend) handleDeviceRemoved(devicePath dbus.ObjectPath)
 		)
 	}
 
-	for iface, info := range b.ethernetDevices {
-		if info.device.GetPath() == devicePath {
-			delete(b.ethernetDevices, iface)
-
-			if b.ethernetDevice != nil {
-				dev := b.ethernetDevice.(gonetworkmanager.Device)
-				if dev.GetPath() == devicePath {
-					b.ethernetDevice = nil
-					for _, remaining := range b.ethernetDevices {
-						b.ethernetDevice = remaining.device
-						break
-					}
+	if _, remaining, found := b.removeEthernetDeviceByPath(devicePath); found {
+		if b.ethernetDevice != nil {
+			dev := b.ethernetDevice.(gonetworkmanager.Device)
+			if dev.GetPath() == devicePath {
+				b.ethernetDevice = nil
+				for _, r := range remaining {
+					b.ethernetDevice = r.device
+					break
 				}
 			}
-
-			b.updateAllEthernetDevices()
-			b.updateEthernetState()
-			b.listEthernetConnections()
-			b.updatePrimaryConnection()
-
-			if b.onStateChange != nil {
-				b.onStateChange()
-			}
-			return
 		}
+
+		b.updateAllEthernetDevices()
+		b.updateEthernetState()
+		b.listEthernetConnections()
+		b.updatePrimaryConnection()
+
+		if b.onStateChange != nil {
+			b.onStateChange()
+		}
+		return
 	}
 
-	for iface, info := range b.wifiDevices {
-		if info.device.GetPath() == devicePath {
-			delete(b.wifiDevices, iface)
-
-			if b.wifiDevice != nil {
-				dev := b.wifiDevice.(gonetworkmanager.Device)
-				if dev.GetPath() == devicePath {
-					b.wifiDevice = nil
-					b.wifiDev = nil
-					for _, remaining := range b.wifiDevices {
-						b.wifiDevice = remaining.device
-						b.wifiDev = remaining.wireless
-						break
-					}
+	if _, remaining, found := b.removeWifiDeviceByPath(devicePath); found {
+		if b.wifiDevice != nil {
+			dev := b.wifiDevice.(gonetworkmanager.Device)
+			if dev.GetPath() == devicePath {
+				b.wifiDevice = nil
+				b.wifiDev = nil
+				for _, r := range remaining {
+					b.wifiDevice = r.device
+					b.wifiDev = r.wireless
+					break
 				}
 			}
-
-			b.updateAllWiFiDevices()
-			b.updateWiFiState()
-
-			if b.onStateChange != nil {
-				b.onStateChange()
-			}
-			return
 		}
+
+		b.updateAllWiFiDevices()
+		b.updateWiFiState()
+
+		if b.onStateChange != nil {
+			b.onStateChange()
+		}
+		return
 	}
 }

core/internal/server/network/backend_networkmanager_state.go

@@ -76,7 +76,7 @@ func (b *NetworkManagerBackend) updateEthernetState() error {
 	var connectedIP string
 	var anyConnected bool
 
-	for name, info := range b.ethernetDevices {
+	for name, info := range b.ethernetDevicesSnapshot() {
 		state, err := info.device.GetPropertyState()
 		if err != nil {
 			continue

core/internal/server/network/backend_networkmanager_wifi.go

@@ -973,7 +973,7 @@ func (b *NetworkManagerBackend) SetWiFiAutoconnect(ssid string, autoconnect bool
 }
 
 func (b *NetworkManagerBackend) ScanWiFiDevice(device string) error {
-	devInfo, ok := b.wifiDevices[device]
+	devInfo, ok := b.wifiDeviceByIface(device)
 	if !ok {
 		return fmt.Errorf("WiFi device not found: %s", device)
 	}
@@ -995,7 +995,7 @@ func (b *NetworkManagerBackend) ScanWiFiDevice(device string) error {
 }
 
 func (b *NetworkManagerBackend) DisconnectWiFiDevice(device string) error {
-	devInfo, ok := b.wifiDevices[device]
+	devInfo, ok := b.wifiDeviceByIface(device)
 	if !ok {
 		return fmt.Errorf("WiFi device not found: %s", device)
 	}
@@ -1047,7 +1047,7 @@ func (b *NetworkManagerBackend) updateAllWiFiDevices() {
 	wifiConnected := b.state.WiFiConnected
 	b.stateMutex.RUnlock()
 
-	for name, devInfo := range b.wifiDevices {
+	for name, devInfo := range b.wifiDevicesSnapshot() {
 		state, _ := devInfo.device.GetPropertyState()
 		connected := state == gonetworkmanager.NmDeviceStateActivated
 
@@ -1211,7 +1211,7 @@ func (b *NetworkManagerBackend) updateAllWiFiDevices() {
 
 func (b *NetworkManagerBackend) getWifiDeviceForConnection(deviceName string) (*wifiDeviceInfo, error) {
 	if deviceName != "" {
-		devInfo, ok := b.wifiDevices[deviceName]
+		devInfo, ok := b.wifiDeviceByIface(deviceName)
 		if !ok {
 			return nil, fmt.Errorf("WiFi device not found: %s", deviceName)
 		}
@@ -1224,7 +1224,7 @@ func (b *NetworkManagerBackend) getWifiDeviceForConnection(deviceName string) (*
 
 	dev := b.wifiDevice.(gonetworkmanager.Device)
 	iface, _ := dev.GetPropertyInterface()
-	if devInfo, ok := b.wifiDevices[iface]; ok {
+	if devInfo, ok := b.wifiDeviceByIface(iface); ok {
 		return devInfo, nil
 	}
 

core/internal/server/server.go

@@ -8,6 +8,7 @@ import (
 	"net"
 	"os"
 	"path/filepath"
+	"runtime/debug"
 	"strconv"
 	"strings"
 	"sync"
@@ -41,7 +42,7 @@ import (
 	"github.com/AvengeMedia/DankMaterialShell/core/pkg/syncmap"
 )
 
-const APIVersion = 27
+const APIVersion = 28
 
 var CLIVersion = "dev"
 
@@ -398,6 +399,11 @@ func InitializeSysUpdateManager() error {
 
 func handleConnection(conn net.Conn) {
 	defer conn.Close()
+	defer func() {
+		if r := recover(); r != nil {
+			log.Errorf("handleConnection panic recovered: panic=%v\n%s", r, debug.Stack())
+		}
+	}()
 
 	caps := getCapabilities()
 	capsData, _ := json.Marshal(caps)
@@ -415,10 +421,21 @@ func handleConnection(conn net.Conn) {
 			continue
 		}
 
-		go RouteRequest(conn, req)
+		go routeRequestRecovered(conn, req)
 	}
 }
 
+// routeRequestRecovered keeps a panicking handler from taking down the whole daemon
+func routeRequestRecovered(conn net.Conn, req models.Request) {
+	defer func() {
+		if r := recover(); r != nil {
+			log.Errorf("RouteRequest panic recovered: method=%s panic=%v\n%s", req.Method, r, debug.Stack())
+			models.RespondError(conn, req.ID, "internal server error")
+		}
+	}()
+	RouteRequest(conn, req)
+}
+
 func getCapabilities() Capabilities {
 	caps := []string{"plugins"}
 
@@ -581,6 +598,11 @@ func notifyCapabilityChange() {
 func handleSubscribe(conn net.Conn, req models.Request) {
 	clientID := fmt.Sprintf("meta-client-%p", conn)
 
+	dbusClient := dbusClientID
+	if id, ok := models.Get[string](req, "clientId"); ok && id != "" {
+		dbusClient = id
+	}
+
 	var services []string
 	if servicesParam, ok := models.Get[[]any](req, "services"); ok {
 		for _, s := range servicesParam {
@@ -1249,10 +1271,10 @@ func handleSubscribe(conn net.Conn, req models.Request) {
 
 	if shouldSubscribe("dbus") && dbusManager != nil {
 		wg.Add(1)
-		dbusChan := dbusManager.SubscribeSignals(dbusClientID)
+		dbusChan := dbusManager.SubscribeSignals(dbusClient)
 		go func() {
 			defer wg.Done()
-			defer dbusManager.UnsubscribeSignals(dbusClientID)
+			defer dbusManager.UnsubscribeSignals(dbusClient)
 
 			for {
 				select {