clean up setup/launcher code and enable better control over shares

In the past Wayland, X and PulseAudio are shared unconditionally. This can unnecessarily increase attack surface as some of these resources might not be needed at all. This commit moves all environment preparation code to the internal app package and selectively call them based on flags.

An "enablements" bitfield is introduced tracking all enabled shares. This value is registered after successful child process launch and stored in launcher states.

Code responsible for running the child process is isolated to its own app/run file and cleaned up. Launch method selection is also extensively cleaned up.

The internal state/track readLaunchers function now takes uid as an argument. Launcher state is now printed using text/tabwriter and argv is only emitted when verbose.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

4 files changed, 86 insertions, 14 deletions

diff --git a/internal/state/enablement.go b/internal/state/enablement.go
new file mode 100644
index 00000000..9358f432
--- /dev/null
+++ b/internal/state/enablement.go
@@ -0,0 +1,34 @@
+package state
+
+type (
+	Enablement  uint8
+	Enablements uint64
+)
+
+const (
+	EnableWayland Enablement = iota
+	EnableX
+	EnableDBus
+	EnablePulse
+
+	enableLength
+)
+
+var enablementString = [enableLength]string{
+	"Wayland",
+	"X11",
+	"D-Bus",
+	"PulseAudio",
+}
+
+func (e Enablement) String() string {
+	return enablementString[e]
+}
+
+func (e Enablement) Mask() Enablements {
+	return 1 << e
+}
+
+func (es Enablements) Has(e Enablement) bool {
+	return es&e.Mask() != 0
+}
diff --git a/internal/state/exit.go b/internal/state/exit.go
index e0e2c04a..3da1f48e 100644
--- a/internal/state/exit.go
+++ b/internal/state/exit.go
@@ -33,7 +33,7 @@ func BeforeExit() {
 		}
 	}
 
-	if d, err := readLaunchers(); err != nil {
+	if d, err := readLaunchers(u.Uid); err != nil {
 		fmt.Println("Error reading active launchers:", err)
 		os.Exit(1)
 	} else if len(d) > 0 {
diff --git a/internal/state/register.go b/internal/state/register.go
index 2fff565e..25c22894 100644
--- a/internal/state/register.go
+++ b/internal/state/register.go
@@ -4,6 +4,13 @@ func RegisterRevertPath(p string) {
 	cleanupCandidate = append(cleanupCandidate, p)
 }
 
+func RegisterEnablement(e Enablements) {
+	if enablements != nil {
+		panic("enablement state set twice")
+	}
+	enablements = &e
+}
+
 func XcbActionComplete() {
 	if xcbActionComplete {
 		Fatal("xcb inserted twice")
diff --git a/internal/state/track.go b/internal/state/track.go
index 913d684d..96e9353d 100644
--- a/internal/state/track.go
+++ b/internal/state/track.go
@@ -10,6 +10,8 @@ import (
 	"os/exec"
 	"path"
 	"strconv"
+	"strings"
+	"text/tabwriter"
 
 	"git.ophivana.moe/cat/fortify/internal/system"
 )
@@ -22,13 +24,15 @@ var (
 	statePath         string
 	cleanupCandidate  []string
 	xcbActionComplete bool
+	enablements       *Enablements
 )
 
 type launcherState struct {
-	PID      int
-	Launcher string
-	Argv     []string
-	Command  []string
+	PID        int
+	Launcher   string
+	Argv       []string
+	Command    []string
+	Capability Enablements
 }
 
 func init() {
@@ -40,15 +44,41 @@ func Early() {
 		return
 	}
 
-	launchers, err := readLaunchers()
+	launchers, err := readLaunchers(u.Uid)
 	if err != nil {
 		fmt.Println("Error reading launchers:", err)
 		os.Exit(1)
 	}
 
-	fmt.Println("\tPID\tLauncher")
+	stdout := tabwriter.NewWriter(os.Stdout, 0, 1, 4, ' ', 0)
+	if !system.V.Verbose {
+		_, _ = fmt.Fprintln(stdout, "\tPID\tEnablements\tLauncher\tCommand")
+	} else {
+		_, _ = fmt.Fprintln(stdout, "\tPID\tArgv")
+	}
+
 	for _, state := range launchers {
-		fmt.Printf("\t%d\t%s\nCommand: %s\nArgv: %s\n", state.PID, state.Launcher, state.Command, state.Argv)
+		enablementsDescription := strings.Builder{}
+		for i := Enablement(0); i < enableLength; i++ {
+			if state.Capability.Has(i) {
+				enablementsDescription.WriteString(", " + i.String())
+			}
+		}
+		if enablementsDescription.Len() == 0 {
+			enablementsDescription.WriteString("none")
+		}
+
+		if !system.V.Verbose {
+			_, _ = fmt.Fprintf(stdout, "\t%d\t%s\t%s\t%s\n",
+				state.PID, strings.TrimPrefix(enablementsDescription.String(), ", "), state.Launcher,
+				state.Command)
+		} else {
+			_, _ = fmt.Fprintf(stdout, "\t%d\t%s\n",
+				state.PID, state.Argv)
+		}
+	}
+	if err = stdout.Flush(); err != nil {
+		fmt.Println("warn: error formatting output:", err)
 	}
 
 	os.Exit(0)
@@ -58,10 +88,11 @@ func Early() {
 func SaveProcess(uid string, cmd *exec.Cmd) error {
 	statePath = path.Join(system.V.RunDir, uid, strconv.Itoa(cmd.Process.Pid))
 	state := launcherState{
-		PID:      cmd.Process.Pid,
-		Launcher: cmd.Path,
-		Argv:     cmd.Args,
-		Command:  command,
+		PID:        cmd.Process.Pid,
+		Launcher:   cmd.Path,
+		Argv:       cmd.Args,
+		Command:    command,
+		Capability: *enablements,
 	}
 
 	if err := os.Mkdir(path.Join(system.V.RunDir, uid), 0700); err != nil && !errors.Is(err, fs.ErrExist) {
@@ -81,10 +112,10 @@ func SaveProcess(uid string, cmd *exec.Cmd) error {
 	}
 }
 
-func readLaunchers() ([]*launcherState, error) {
+func readLaunchers(uid string) ([]*launcherState, error) {
 	var f *os.File
 	var r []*launcherState
-	launcherPrefix := path.Join(system.V.RunDir, u.Uid)
+	launcherPrefix := path.Join(system.V.RunDir, uid)
 
 	if pl, err := os.ReadDir(launcherPrefix); err != nil {
 		return nil, err