trust anchor: repoint VerifyTrustAnchor at the catalogue pin (not a static list) (#25)

Author: Alexgodoroja

pkg/manifest/manifest.go

@@ -196,49 +196,52 @@ func (m *Manifest) signingPayload() ([]byte, error) {
 	return []byte(payload), nil
 }
 
-// TrustedPublishers is the compile-time-embedded list of publisher
-// ed25519 public keys ("ed25519:<base64>" or raw base64) that are
-// trusted to sign manifests. Empty list = fail-closed (no publisher
-// passes the trust-anchor check). Production builds MUST populate
-// this list with the known-good publisher keys.
-var TrustedPublishers []string
-
-// VerifyTrustAnchor checks that Store.Publisher is on the trusted
-// publishers list. Without this check, VerifySignature only confirms
-// the manifest was signed by whoever claims to be the publisher;
-// VerifyTrustAnchor confirms the publisher itself is known and trusted.
-//
-// Returns nil if Store.Publisher is in TrustedPublishers.
-// Returns an error if TrustedPublishers is empty (fail-closed) or if
-// the publisher is not found.
-func (m *Manifest) VerifyTrustAnchor() error {
-	if len(TrustedPublishers) == 0 {
-		return fmt.Errorf("trust anchor: TrustedPublishers is empty — no publisher is trusted")
+// decodeEd25519Pub parses an "ed25519:<base64>" (or bare base64) public key
+// into raw bytes, validating the length.
+func decodeEd25519Pub(s string) ([]byte, error) {
+	raw := strings.TrimPrefix(strings.TrimSpace(s), "ed25519:")
+	key, err := base64.StdEncoding.DecodeString(raw)
+	if err != nil {
+		return nil, fmt.Errorf("invalid base64: %w", err)
 	}
+	if len(key) != ed25519.PublicKeySize {
+		return nil, fmt.Errorf("wrong key length %d, want %d", len(key), ed25519.PublicKeySize)
+	}
+	return key, nil
+}
 
-	pubkeyRaw, ok := strings.CutPrefix(m.Store.Publisher, "ed25519:")
-	if !ok {
-		return fmt.Errorf("store.publisher must be \"ed25519:<base64>\"")
+// VerifyTrustAnchor confirms that Store.Publisher matches the publisher key the
+// release-signed catalogue pins for this app. This is the trust anchor for
+// non-sideloaded (catalogue) installs: the catalogue is the root of trust
+// (the installer verifies the catalogue signature and pins each app's bundle
+// sha256), and this check re-confirms on every launch that the installed
+// manifest is published by the catalogue-declared key.
+//
+// Without it, VerifySignature alone only proves a manifest is internally
+// self-consistent — a manifest self-signed by ANY key would pass — which would
+// let an app dropped into the install root run with full grants.
+//
+// cataloguePublisher is the "ed25519:<base64>" key the verified catalogue
+// declares for m.ID; the caller (the supervisor) obtains it from the
+// signature-verified catalogue via Config.CataloguePublisher. An empty string
+// means the app is not pinned by the catalogue, which is fail-closed. Returns
+// nil only when the manifest's publisher equals the catalogue-pinned key.
+func (m *Manifest) VerifyTrustAnchor(cataloguePublisher string) error {
+	if strings.TrimSpace(cataloguePublisher) == "" {
+		return fmt.Errorf("trust anchor: %s is not pinned by the signed catalogue", m.ID)
 	}
-	pubkey, err := base64.StdEncoding.DecodeString(pubkeyRaw)
+	pubkey, err := decodeEd25519Pub(m.Store.Publisher)
 	if err != nil {
-		return fmt.Errorf("store.publisher: invalid base64: %w", err)
+		return fmt.Errorf("store.publisher: %w", err)
 	}
-	if len(pubkey) != ed25519.PublicKeySize {
-		return fmt.Errorf("store.publisher: wrong key length %d, want %d", len(pubkey), ed25519.PublicKeySize)
+	trustedKey, err := decodeEd25519Pub(cataloguePublisher)
+	if err != nil {
+		return fmt.Errorf("catalogue publisher for %s: %w", m.ID, err)
 	}
-
-	for _, trusted := range TrustedPublishers {
-		trustedRaw := strings.TrimPrefix(trusted, "ed25519:")
-		trustedKey, err := base64.StdEncoding.DecodeString(trustedRaw)
-		if err != nil {
-			continue // skip malformed entries
-		}
-		if bytes.Equal(pubkey, trustedKey) {
-			return nil
-		}
+	if !bytes.Equal(pubkey, trustedKey) {
+		return fmt.Errorf("trust anchor: publisher %s does not match the catalogue pin for %s", m.Store.Publisher, m.ID)
 	}
-	return fmt.Errorf("trust anchor: publisher %s is not on the trusted-publishers list", m.Store.Publisher)
+	return nil
 }
 
 // VerifySignature checks that Store.Signature is a valid ed25519
@@ -248,9 +251,9 @@ func (m *Manifest) VerifyTrustAnchor() error {
 // (Publisher, ID, ManifestVersion, Binary.SHA256, Grants) will cause
 // verification to fail.
 //
-// IMPORTANT: This does NOT check that Store.Publisher is a trusted key.
-// Callers MUST also call VerifyTrustAnchor() after VerifySignature()
-// to confirm the publisher is on the TrustedPublishers list.
+// IMPORTANT: This does NOT check that Store.Publisher is trusted. For
+// non-sideloaded apps, callers MUST also call VerifyTrustAnchor(cataloguePublisher)
+// to confirm the publisher matches the key the signed catalogue pins for the app.
 func (m *Manifest) VerifySignature() error {
 	pubkeyRaw, ok := strings.CutPrefix(m.Store.Publisher, "ed25519:")
 	if !ok {

pkg/manifest/manifest_test.go

@@ -390,49 +390,39 @@ func TestVerifySignatureRejectsEmptySignature(t *testing.T) {
 	}
 }
 
-func TestVerifyTrustAnchorEmptyListIsFailClosed(t *testing.T) {
-	// With TrustedPublishers empty (default), VerifyTrustAnchor must reject all publishers.
-	orig := TrustedPublishers
-	TrustedPublishers = nil
-	defer func() { TrustedPublishers = orig }()
-
+func TestVerifyTrustAnchorEmptyPinIsFailClosed(t *testing.T) {
+	// An app the catalogue does not pin (empty publisher) must be rejected,
+	// even if its own self-signature is valid.
 	m := mustValid(t)
-	if err := m.VerifyTrustAnchor(); err == nil {
-		t.Error("expected error with empty TrustedPublishers, got nil")
+	if err := m.VerifyTrustAnchor(""); err == nil {
+		t.Error("expected error with empty catalogue pin (app not pinned), got nil")
 	}
 }
 
-func TestVerifyTrustAnchorRejectsUntrustedPublisher(t *testing.T) {
-	trustedPub, _, err := ed25519.GenerateKey(rand.Reader)
+func TestVerifyTrustAnchorRejectsMismatchedPublisher(t *testing.T) {
+	cataloguePub, _, err := ed25519.GenerateKey(rand.Reader)
 	if err != nil {
 		t.Fatal(err)
 	}
-	untrustedPub, _, err := ed25519.GenerateKey(rand.Reader)
+	otherPub, _, err := ed25519.GenerateKey(rand.Reader)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	orig := TrustedPublishers
-	TrustedPublishers = []string{"ed25519:" + base64Enc(trustedPub)}
-	defer func() { TrustedPublishers = orig }()
-
 	m := mustValid(t)
-	m.Store.Publisher = "ed25519:" + base64Enc(untrustedPub)
-	if err := m.VerifyTrustAnchor(); err == nil {
-		t.Error("expected error for untrusted publisher, got nil")
+	m.Store.Publisher = "ed25519:" + base64Enc(otherPub)
+	// Catalogue pins cataloguePub but the manifest is published by otherPub.
+	if err := m.VerifyTrustAnchor("ed25519:" + base64Enc(cataloguePub)); err == nil {
+		t.Error("expected error: manifest publisher does not match the catalogue pin")
 	}
 }
 
-func TestVerifyTrustAnchorAcceptsTrustedPublisher(t *testing.T) {
+func TestVerifyTrustAnchorAcceptsCataloguePinnedPublisher(t *testing.T) {
 	pub, priv, err := ed25519.GenerateKey(rand.Reader)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	orig := TrustedPublishers
-	TrustedPublishers = []string{"ed25519:" + base64Enc(pub)}
-	defer func() { TrustedPublishers = orig }()
-
 	m := mustValid(t)
 	m.Store.Publisher = "ed25519:" + base64Enc(pub)
 	sig, err := signTestManifest(m, priv)
@@ -445,54 +435,29 @@ func TestVerifyTrustAnchorAcceptsTrustedPublisher(t *testing.T) {
 	if err := m.VerifySignature(); err != nil {
 		t.Fatalf("valid signature rejected: %v", err)
 	}
-	// VerifyTrustAnchor must pass because the publisher IS trusted.
-	if err := m.VerifyTrustAnchor(); err != nil {
-		t.Errorf("trusted publisher rejected by VerifyTrustAnchor: %v", err)
+	// VerifyTrustAnchor must pass: the manifest publisher equals the catalogue pin.
+	if err := m.VerifyTrustAnchor("ed25519:" + base64Enc(pub)); err != nil {
+		t.Errorf("catalogue-pinned publisher rejected by VerifyTrustAnchor: %v", err)
 	}
 }
 
-func TestVerifyTrustAnchorMultipleTrustedKeys(t *testing.T) {
-	pub1, _, err := ed25519.GenerateKey(rand.Reader)
-	if err != nil {
-		t.Fatal(err)
-	}
-	pub2, priv2, err := ed25519.GenerateKey(rand.Reader)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	orig := TrustedPublishers
-	TrustedPublishers = []string{
-		"ed25519:" + base64Enc(pub1),
-		"ed25519:" + base64Enc(pub2),
+func TestVerifyTrustAnchorRejectsBadPublisherFormat(t *testing.T) {
+	m := mustValid(t)
+	m.Store.Publisher = "not-valid-publisher"
+	if err := m.VerifyTrustAnchor("ed25519:AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="); err == nil {
+		t.Error("expected error with bad publisher format, got nil")
 	}
-	defer func() { TrustedPublishers = orig }()
+}
 
-	m := mustValid(t)
-	m.Store.Publisher = "ed25519:" + base64Enc(pub2)
-	sig, err := signTestManifest(m, priv2)
+func TestVerifyTrustAnchorRejectsBadCataloguePinFormat(t *testing.T) {
+	pub, _, err := ed25519.GenerateKey(rand.Reader)
 	if err != nil {
 		t.Fatal(err)
 	}
-	m.Store.Signature = sig
-
-	if err := m.VerifySignature(); err != nil {
-		t.Fatalf("valid signature rejected: %v", err)
-	}
-	if err := m.VerifyTrustAnchor(); err != nil {
-		t.Errorf("second trusted publisher rejected: %v", err)
-	}
-}
-
-func TestVerifyTrustAnchorRejectsBadPublisherFormat(t *testing.T) {
-	orig := TrustedPublishers
-	TrustedPublishers = []string{"ed25519:AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="}
-	defer func() { TrustedPublishers = orig }()
-
 	m := mustValid(t)
-	m.Store.Publisher = "not-valid-publisher"
-	if err := m.VerifyTrustAnchor(); err == nil {
-		t.Error("expected error with bad publisher format, got nil")
+	m.Store.Publisher = "ed25519:" + base64Enc(pub)
+	if err := m.VerifyTrustAnchor("not-a-valid-key"); err == nil {
+		t.Error("expected error with malformed catalogue pin, got nil")
 	}
 }
 

plugin/appstore/service.go

@@ -36,6 +36,18 @@ type Config struct {
 	// dev key via NewServiceWithKey.
 	CatalogPubkey []byte
 
+	// CataloguePublisher returns the publisher key ("ed25519:<base64>") that the
+	// release-signed catalogue pins for appID, and whether appID is pinned at
+	// all. It is the trust anchor for non-sideloaded apps: before spawning a
+	// catalogue app the supervisor confirms the installed manifest's publisher
+	// matches this pin (manifest.VerifyTrustAnchor). The daemon supplies it from
+	// the catalogue it has signature-verified with CatalogPubkey.
+	//
+	// When nil (or it reports an app as not pinned), non-sideloaded apps
+	// fail closed — they are not spawned. Sideloaded apps bypass this and are
+	// clamped to the safe grant subset instead.
+	CataloguePublisher func(appID string) (publisher string, pinned bool)
+
 	// Logger optionally redirects internal messages. When nil the
 	// service logs via the standard log package.
 	Logger *log.Logger
@@ -135,13 +147,13 @@ func (s *Service) Order() int { return 120 }
 // Go's structural typing makes this work as long as the methods used here
 // are present on the real types.
 type Deps struct {
-	Streams    any // coreapi.Streams — Dial, Listen, SendDatagram
-	Identity   any // coreapi.Identity — NodeID, Address, PublicKey, Sign
-	Resolver   any
-	Events     any // coreapi.EventBus — Publish, Subscribe
-	Logger     any
-	Trust      any
-	Telemetry  TelemetryEmitter // optional; no-op when nil
+	Streams   any // coreapi.Streams — Dial, Listen, SendDatagram
+	Identity  any // coreapi.Identity — NodeID, Address, PublicKey, Sign
+	Resolver  any
+	Events    any // coreapi.EventBus — Publish, Subscribe
+	Logger    any
+	Trust     any
+	Telemetry TelemetryEmitter // optional; no-op when nil
 }
 
 // Start scans InstallRoot for installed apps, verifies each binary's

plugin/appstore/service_test.go

@@ -20,8 +20,9 @@ func TestStartWarnsOnPlaceholderCatalogPubkey(t *testing.T) {
 	t.Run("placeholder (all-zeros) → warns", func(t *testing.T) {
 		var buf strings.Builder
 		s := NewService(Config{
-			InstallRoot: t.TempDir(),
-			Logger:      log.New(&buf, "", 0),
+			CataloguePublisher: testCatPub,
+			InstallRoot:        t.TempDir(),
+			Logger:             log.New(&buf, "", 0),
 		})
 		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
 		defer cancel()
@@ -38,9 +39,10 @@ func TestStartWarnsOnPlaceholderCatalogPubkey(t *testing.T) {
 		realKey := make([]byte, 32)
 		realKey[0] = 0x01 // any non-zero byte qualifies
 		s := NewService(Config{
-			InstallRoot:   t.TempDir(),
-			CatalogPubkey: realKey,
-			Logger:        log.New(&buf, "", 0),
+			CataloguePublisher: testCatPub,
+			InstallRoot:        t.TempDir(),
+			CatalogPubkey:      realKey,
+			Logger:             log.New(&buf, "", 0),
 		})
 		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
 		defer cancel()
@@ -72,7 +74,7 @@ func TestNewServiceDefaults(t *testing.T) {
 
 func TestStartStopEmptyInstallRoot(t *testing.T) {
 	dir := t.TempDir()
-	s := NewService(Config{InstallRoot: dir})
+	s := NewService(Config{InstallRoot: dir, CataloguePublisher: testCatPub})
 
 	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
 	defer cancel()
@@ -87,7 +89,7 @@ func TestStartStopEmptyInstallRoot(t *testing.T) {
 
 func TestStartCreatesInstallRoot(t *testing.T) {
 	dir := filepath.Join(t.TempDir(), "nested", "apps")
-	s := NewService(Config{InstallRoot: dir})
+	s := NewService(Config{InstallRoot: dir, CataloguePublisher: testCatPub})
 
 	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
 	defer cancel()
@@ -111,8 +113,9 @@ func TestRescanDiscoversAppInstalledMidRun(t *testing.T) {
 	writeValidAppDir(t, root, "io.app1")
 
 	svc := NewService(Config{
-		InstallRoot:    root,
-		RescanInterval: 30 * time.Millisecond, // fast for tests
+		CataloguePublisher: testCatPub,
+		InstallRoot:        root,
+		RescanInterval:     30 * time.Millisecond, // fast for tests
 	})
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 	defer cancel()
@@ -152,8 +155,9 @@ func TestRescanDetectsUninstall(t *testing.T) {
 	writeValidAppDir(t, root, "io.app2")
 
 	svc := NewService(Config{
-		InstallRoot:    root,
-		RescanInterval: 30 * time.Millisecond,
+		CataloguePublisher: testCatPub,
+		InstallRoot:        root,
+		RescanInterval:     30 * time.Millisecond,
 	})
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 	defer cancel()
@@ -195,7 +199,7 @@ func TestRescanResumeClearsSuspendedMarker(t *testing.T) {
 	root := t.TempDir()
 	appDir := writeValidAppDir(t, root, "io.suspended.app")
 
-	sup := newSupervisor(Config{InstallRoot: root}, Deps{}, newQuietLogger(t))
+	sup := newSupervisor(Config{InstallRoot: root, CataloguePublisher: testCatPub}, Deps{}, newQuietLogger(t))
 	sup.mu.Lock()
 	sup.installed["io.suspended.app"] = &installedApp{
 		Dir:        appDir,
@@ -241,8 +245,9 @@ func TestRescanResumesAppOnMarker(t *testing.T) {
 	// exceeding the crash-loop cap; we don't need the live goroutine
 	// for the resume signal to be testable).
 	sup := newSupervisor(Config{
-		InstallRoot:    root,
-		RescanInterval: 20 * time.Millisecond,
+		CataloguePublisher: testCatPub,
+		InstallRoot:        root,
+		RescanInterval:     20 * time.Millisecond,
 	}, Deps{}, newQuietLogger(t))
 	sup.mu.Lock()
 	sup.installed["io.suspended.app"] = &installedApp{
@@ -285,7 +290,7 @@ func TestScanIgnoresInvalidManifest(t *testing.T) {
 	empty := filepath.Join(root, "io.empty.app")
 	_ = os.MkdirAll(empty, 0o755)
 
-	sup := newSupervisor(Config{InstallRoot: root}, Deps{}, newQuietLogger(t))
+	sup := newSupervisor(Config{InstallRoot: root, CataloguePublisher: testCatPub}, Deps{}, newQuietLogger(t))
 	apps, err := sup.scanInstalled()
 	if err != nil {
 		t.Fatalf("scan: %v", err)