Fix allow netbird traffic for nftables and userspace (#1446)

Add default allow rules for input and output chains as part of the allownetbird call for userspace mode

.github/workflows/android-build-validation.yml

@@ -22,6 +22,13 @@ jobs:
           go-version: "1.21.x"
       - name: Setup Android SDK
         uses: android-actions/setup-android@v2
+
+      - name: Setup Java
+        uses: actions/setup-java@v3
+        with:
+          java-version: "8"
+          distribution: "adopt"
+
       - name: NDK Cache
         id: ndk-cache
         uses: actions/cache@v3
@@ -38,4 +45,4 @@ jobs:
         run: PATH=$PATH:$(go env GOPATH) gomobile bind -o $GITHUB_WORKSPACE/netbird.aar -javapkg=io.netbird.gomobile -ldflags="-X golang.zx2c4.com/wireguard/ipc.socketDirectory=/data/data/io.netbird.client/cache/wireguard -X github.com/netbirdio/netbird/version.version=buildtest"  $GITHUB_WORKSPACE/client/android
         env:
           CGO_ENABLED: 0
-          ANDROID_NDK_HOME: /usr/local/lib/android/sdk/ndk/23.1.7779620
+          ANDROID_NDK_HOME: /usr/local/lib/android/sdk/ndk/23.1.7779620

client/firewall/nftables/acl_linux.go

@@ -58,6 +58,7 @@ type AclManager struct {
 type iFaceMapper interface {
 	Name() string
 	Address() iface.WGAddress
+	IsUserspaceBind() bool
 }
 
 func newAclManager(table *nftables.Table, wgIface iFaceMapper, routeingFwChainName string) (*AclManager, error) {
@@ -198,6 +199,81 @@ func (m *AclManager) DeleteRule(rule firewall.Rule) error {
 	return nil
 }
 
+// createDefaultAllowRules In case if the USP firewall manager can use the native firewall manager we must to create allow rules for
+// input and output chains
+func (m *AclManager) createDefaultAllowRules() error {
+	expIn := []expr.Any{
+		&expr.Payload{
+			DestRegister: 1,
+			Base:         expr.PayloadBaseNetworkHeader,
+			Offset:       12,
+			Len:          4,
+		},
+		// mask
+		&expr.Bitwise{
+			SourceRegister: 1,
+			DestRegister:   1,
+			Len:            4,
+			Mask:           []byte{0x00, 0x00, 0x00, 0x00},
+			Xor:            zeroXor,
+		},
+		// net address
+		&expr.Cmp{
+			Register: 1,
+			Data:     []byte{0x00, 0x00, 0x00, 0x00},
+		},
+		&expr.Verdict{
+			Kind: expr.VerdictAccept,
+		},
+	}
+
+	_ = m.rConn.InsertRule(&nftables.Rule{
+		Table:    m.workTable,
+		Chain:    m.chainInputRules,
+		Position: 0,
+		Exprs:    expIn,
+	})
+
+	expOut := []expr.Any{
+		&expr.Payload{
+			DestRegister: 1,
+			Base:         expr.PayloadBaseNetworkHeader,
+			Offset:       16,
+			Len:          4,
+		},
+		// mask
+		&expr.Bitwise{
+			SourceRegister: 1,
+			DestRegister:   1,
+			Len:            4,
+			Mask:           []byte{0x00, 0x00, 0x00, 0x00},
+			Xor:            zeroXor,
+		},
+		// net address
+		&expr.Cmp{
+			Register: 1,
+			Data:     []byte{0x00, 0x00, 0x00, 0x00},
+		},
+		&expr.Verdict{
+			Kind: expr.VerdictAccept,
+		},
+	}
+
+	_ = m.rConn.InsertRule(&nftables.Rule{
+		Table:    m.workTable,
+		Chain:    m.chainOutputRules,
+		Position: 0,
+		Exprs:    expOut,
+	})
+
+	err := m.rConn.Flush()
+	if err != nil {
+		log.Debugf("failed to create default allow rules: %s", err)
+		return err
+	}
+	return nil
+}
+
 // Flush rule/chain/set operations from the buffer
 //
 // Method also get all rules after flush and refreshes handle values in the rulesets

client/firewall/nftables/manager_linux.go

@@ -106,11 +106,19 @@ func (m *Manager) RemoveRoutingRules(pair firewall.RouterPair) error {
 }
 
 // AllowNetbird allows netbird interface traffic
-// todo review this method usage
 func (m *Manager) AllowNetbird() error {
+	if !m.wgIface.IsUserspaceBind() {
+		return nil
+	}
+
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 
+	err := m.aclManager.createDefaultAllowRules()
+	if err != nil {
+		return fmt.Errorf("failed to create default allow rules: %v", err)
+	}
+
 	chains, err := m.rConn.ListChainsOfTableFamily(nftables.TableFamilyIPv4)
 	if err != nil {
 		return fmt.Errorf("list of chains: %w", err)
@@ -145,6 +153,7 @@ func (m *Manager) AllowNetbird() error {
 	if err != nil {
 		return fmt.Errorf("failed to flush allow input netbird rules: %v", err)
 	}
+
 	return nil
 }
 

client/firewall/nftables/manager_linux_test.go

@@ -37,6 +37,8 @@ func (i *iFaceMock) Address() iface.WGAddress {
 	panic("AddressFunc is not set")
 }
 
+func (i *iFaceMock) IsUserspaceBind() bool { return false }
+
 func TestNftablesManager(t *testing.T) {
 	mock := &iFaceMock{
 		NameFunc: func() string {

client/internal/acl/manager_test.go

@@ -38,7 +38,7 @@ func TestDefaultManager(t *testing.T) {
 	defer ctrl.Finish()
 
 	ifaceMock := mocks.NewMockIFaceMapper(ctrl)
-	ifaceMock.EXPECT().IsUserspaceBind().Return(true)
+	ifaceMock.EXPECT().IsUserspaceBind().Return(true).AnyTimes()
 	ifaceMock.EXPECT().SetFilter(gomock.Any())
 	ip, network, err := net.ParseCIDR("172.0.0.1/32")
 	if err != nil {
@@ -331,7 +331,7 @@ func TestDefaultManagerEnableSSHRules(t *testing.T) {
 	defer ctrl.Finish()
 
 	ifaceMock := mocks.NewMockIFaceMapper(ctrl)
-	ifaceMock.EXPECT().IsUserspaceBind().Return(true)
+	ifaceMock.EXPECT().IsUserspaceBind().Return(true).AnyTimes()
 	ifaceMock.EXPECT().SetFilter(gomock.Any())
 	ip, network, err := net.ParseCIDR("172.0.0.1/32")
 	if err != nil {

iface/tun_usp_linux.go

@@ -45,6 +45,7 @@ func (t *tunUSPDevice) Create() (wgConfigurer, error) {
 	log.Info("create tun interface")
 	tunIface, err := tun.CreateTUN(t.name, t.mtu)
 	if err != nil {
+		log.Debugf("faile to create tun unterface (%s, %d): %s", t.name, t.mtu, err)
 		return nil, err
 	}
 	t.wrapper = newDeviceWrapper(tunIface)