fix: use file-read-data instead of file-read* in macOS Seatbelt deny rules (#20)

Seatbelt ignores wildcard denies (file-read*) when a specific allow
(file-read-data) covers the same path. This made all denyRead rules on
macOS completely ineffective — .env files and user-configured denyRead
paths were readable despite deny rules in the profile.

Fixes #18

Author: tito

internal/sandbox/integration_macos_test.go

@@ -163,6 +163,87 @@ func TestMacOS_SeatbeltAllowsTmpGreywall(t *testing.T) {
 	assertFileExists(t, testFile)
 }
 
+// ============================================================================
+// Sensitive File Read Blocking Tests
+// ============================================================================
+
+// TestMacOS_SeatbeltBlocksEnvFileRead verifies that .env files cannot be read
+// even though the workspace directory has a broad file-read-data allow.
+// This is the regression test for the Seatbelt deny file-read* vs file-read-data bug:
+// Seatbelt ignores wildcard denies (file-read*) when a specific allow (file-read-data)
+// covers the same path. Deny rules must use file-read-data to be effective.
+func TestMacOS_SeatbeltBlocksEnvFileRead(t *testing.T) {
+	skipIfAlreadySandboxed(t)
+
+	workspace := createTempWorkspace(t)
+	createTestFile(t, workspace, ".env", "SECRET_KEY=supersecret")
+	createTestFile(t, workspace, "README.md", "hello")
+
+	cfg := testConfigWithWorkspace(workspace)
+	cfg.Filesystem.DefaultDenyRead = boolPtr(true)
+	cfg.Filesystem.AllowRead = []string{workspace}
+	cfg.Filesystem.DenyRead = []string{filepath.Join(workspace, ".env")}
+
+	// .env should be blocked
+	result := runUnderSandbox(t, cfg, "cat "+filepath.Join(workspace, ".env"), workspace)
+	assertBlocked(t, result)
+
+	// Regular files should still be readable
+	result = runUnderSandbox(t, cfg, "cat "+filepath.Join(workspace, "README.md"), workspace)
+	assertAllowed(t, result)
+	assertContains(t, result.Stdout, "hello")
+}
+
+// TestMacOS_SeatbeltBlocksEnvVariantsRead verifies that .env.* variants are also blocked.
+func TestMacOS_SeatbeltBlocksEnvVariantsRead(t *testing.T) {
+	skipIfAlreadySandboxed(t)
+
+	workspace := createTempWorkspace(t)
+	createTestFile(t, workspace, ".env.local", "LOCAL_SECRET=abc")
+	createTestFile(t, workspace, ".env.production", "PROD_SECRET=xyz")
+
+	cfg := testConfigWithWorkspace(workspace)
+	cfg.Filesystem.DefaultDenyRead = boolPtr(true)
+	cfg.Filesystem.AllowRead = []string{workspace}
+	cfg.Filesystem.DenyRead = []string{
+		filepath.Join(workspace, ".env.local"),
+		filepath.Join(workspace, ".env.production"),
+	}
+
+	result := runUnderSandbox(t, cfg, "cat "+filepath.Join(workspace, ".env.local"), workspace)
+	assertBlocked(t, result)
+
+	result = runUnderSandbox(t, cfg, "cat "+filepath.Join(workspace, ".env.production"), workspace)
+	assertBlocked(t, result)
+}
+
+// TestMacOS_SeatbeltBlocksUserDenyReadPaths verifies that user-configured
+// denyRead paths are blocked even in legacy mode (defaultDenyRead=false).
+func TestMacOS_SeatbeltBlocksUserDenyReadPaths(t *testing.T) {
+	skipIfAlreadySandboxed(t)
+
+	workspace := createTempWorkspace(t)
+	secretDir := filepath.Join(workspace, "secrets")
+	if err := os.MkdirAll(secretDir, 0o750); err != nil {
+		t.Fatalf("failed to create secrets dir: %v", err)
+	}
+	createTestFile(t, workspace, "secrets/api_key.txt", "my-api-key")
+	createTestFile(t, workspace, "public.txt", "public data")
+
+	cfg := testConfigWithWorkspace(workspace)
+	cfg.Filesystem.DefaultDenyRead = boolPtr(false) // legacy mode
+	cfg.Filesystem.DenyRead = []string{secretDir}
+
+	// Secret file should be blocked
+	result := runUnderSandbox(t, cfg, "cat "+filepath.Join(secretDir, "api_key.txt"), workspace)
+	assertBlocked(t, result)
+
+	// Public file should still be readable
+	result = runUnderSandbox(t, cfg, "cat public.txt", workspace)
+	assertAllowed(t, result)
+	assertContains(t, result.Stdout, "public data")
+}
+
 // ============================================================================
 // Network Blocking Tests
 // ============================================================================

internal/sandbox/macos.go

@@ -229,19 +229,21 @@ func generateReadRules(defaultDenyRead bool, cwd string, allowPaths, denyPaths [
 			}
 		}
 
-		// Deny sensitive files within CWD (Seatbelt evaluates deny before allow)
+		// Deny sensitive files within CWD.
+		// Must use file-read-data (not file-read*) because Seatbelt ignores
+		// wildcard denies when a specific allow (file-read-data) covers the same path.
 		if cwd != "" {
 			for _, f := range SensitiveProjectFiles {
 				p := filepath.Join(cwd, f)
 				rules = append(rules,
-					"(deny file-read*",
+					"(deny file-read-data",
 					fmt.Sprintf("  (literal %s)", escapePath(p)),
 					fmt.Sprintf("  (with message %q))", logTag),
 				)
 			}
 			// Also deny .env.* pattern via regex
 			rules = append(rules,
-				"(deny file-read*",
+				"(deny file-read-data",
 				fmt.Sprintf("  (regex %s)", escapePath("^"+regexp.QuoteMeta(cwd)+"/\\.env\\..*$")),
 				fmt.Sprintf("  (with message %q))", logTag),
 			)
@@ -252,23 +254,21 @@ func generateReadRules(defaultDenyRead bool, cwd string, allowPaths, denyPaths [
 	}
 
 	// In both modes, deny specific paths (denyRead takes precedence).
-	// Note: We use file-read* (not file-read-data) so denied paths are fully hidden.
-	// In defaultDenyRead mode, this overrides the global file-read-metadata allow,
-	// meaning denied paths can't even be listed or stat'd - more restrictive than
-	// default mode where denied paths are still visible but unreadable.
+	// Must use file-read-data (not file-read*) because Seatbelt ignores
+	// wildcard denies when a specific allow (file-read-data) covers the same path.
 	for _, pathPattern := range denyPaths {
 		normalized := NormalizePath(pathPattern)
 
 		if ContainsGlobChars(normalized) {
 			regex := GlobToRegex(normalized)
 			rules = append(rules,
-				"(deny file-read*",
+				"(deny file-read-data",
 				fmt.Sprintf("  (regex %s)", escapePath(regex)),
 				fmt.Sprintf("  (with message %q))", logTag),
 			)
 		} else {
 			rules = append(rules,
-				"(deny file-read*",
+				"(deny file-read-data",
 				fmt.Sprintf("  (subpath %s)", escapePath(normalized)),
 				fmt.Sprintf("  (with message %q))", logTag),
 			)

internal/sandbox/macos_test.go

@@ -264,6 +264,108 @@ func TestMacOS_DefaultDenyRead(t *testing.T) {
 	}
 }
 
+// TestMacOS_DenyReadUsesExactOperation verifies that deny read rules use file-read-data
+// (not file-read*) in the generated Seatbelt profile. Seatbelt ignores wildcard denies
+// (file-read*) when a specific allow (file-read-data) covers the same path.
+func TestMacOS_DenyReadUsesExactOperation(t *testing.T) {
+	tests := []struct {
+		name            string
+		defaultDenyRead bool
+		denyRead        []string
+		cwd             string
+	}{
+		{
+			name:            "defaultDenyRead with sensitive project files",
+			defaultDenyRead: true,
+			denyRead:        nil,
+			cwd:             "/home/user/project",
+		},
+		{
+			name:            "defaultDenyRead with user denyRead paths",
+			defaultDenyRead: true,
+			denyRead:        []string{"/home/user/secrets", "/home/user/.ssh/id_*"},
+			cwd:             "/home/user/project",
+		},
+		{
+			name:            "legacy mode with user denyRead paths",
+			defaultDenyRead: false,
+			denyRead:        []string{"/home/user/secrets"},
+			cwd:             "/home/user/project",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			params := MacOSSandboxParams{
+				Command:         "echo test",
+				DefaultDenyRead: tt.defaultDenyRead,
+				Cwd:             tt.cwd,
+				ReadDenyPaths:   tt.denyRead,
+			}
+
+			profile := GenerateSandboxProfile(params)
+
+			// Must NOT contain "deny file-read*" (wildcard deny is ineffective)
+			if strings.Contains(profile, "(deny file-read*") {
+				t.Errorf("profile must NOT use 'deny file-read*' (wildcard deny is ignored by Seatbelt when a specific allow covers the same path)\nProfile:\n%s", profile)
+			}
+
+			// Must contain "deny file-read-data" for deny rules to work
+			if tt.defaultDenyRead || len(tt.denyRead) > 0 {
+				if !strings.Contains(profile, "(deny file-read-data") {
+					t.Errorf("profile must use 'deny file-read-data' for deny rules to be effective\nProfile:\n%s", profile)
+				}
+			}
+		})
+	}
+}
+
+// TestMacOS_DenyReadSensitiveProjectFiles verifies that the generated profile
+// contains deny rules for all sensitive project files (.env, .env.local, etc.).
+func TestMacOS_DenyReadSensitiveProjectFiles(t *testing.T) {
+	cwd := "/home/user/project"
+	params := MacOSSandboxParams{
+		Command:         "cat .env",
+		DefaultDenyRead: true,
+		Cwd:             cwd,
+	}
+
+	profile := GenerateSandboxProfile(params)
+
+	for _, f := range SensitiveProjectFiles {
+		expected := fmt.Sprintf(`(deny file-read-data
+  (literal %q)`, cwd+"/"+f)
+		if !strings.Contains(profile, expected) {
+			t.Errorf("profile missing deny rule for sensitive file %q\nExpected to contain: %s", f, expected)
+		}
+	}
+
+	// Also check .env.* regex pattern
+	if !strings.Contains(profile, `(deny file-read-data
+  (regex`) {
+		t.Errorf("profile missing regex deny rule for .env.* pattern")
+	}
+}
+
+// TestMacOS_DenyReadUserPaths verifies that user-configured denyRead paths
+// appear in the generated profile with file-read-data (not file-read*).
+func TestMacOS_DenyReadUserPaths(t *testing.T) {
+	params := MacOSSandboxParams{
+		Command:         "echo test",
+		DefaultDenyRead: false,
+		Cwd:             "/home/user/project",
+		ReadDenyPaths:   []string{"/home/user/secrets"},
+	}
+
+	profile := GenerateSandboxProfile(params)
+
+	expected := `(deny file-read-data
+  (subpath "/home/user/secrets")`
+	if !strings.Contains(profile, expected) {
+		t.Errorf("profile missing deny rule for user denyRead path\nExpected: %s\nProfile:\n%s", expected, profile)
+	}
+}
+
 // TestExpandMacOSTmpPaths verifies that /tmp and /private/tmp paths are properly mirrored.
 func TestExpandMacOSTmpPaths(t *testing.T) {
 	tests := []struct {