Set container file label on workload API directory

This allows the driver to be used within OpenShift without using an init
container to set the label.

Fixes #54.

Signed-off-by: Andrew Harding <[email protected]>

README.md

@@ -87,6 +87,14 @@ Ensure that the Workload API socket directory is shared with the SPIFFE CSI
 Driver via a `hostPath` volume. The directory backing `emptyDir` volumes are
 tied to the pod instance and invalidated when the pod is restarted.
 
+### Permission Denied accessing Workload API directory
+
+This may be caused by SELinux in environments like OpenShift. The SPIFFE CSI
+Driver attempts to set the container file label on the Workload API socket
+directory on startup. Check the logs to see if it was successful. To be
+successful, the Workload API socket directory must be mounted read-write into
+the CSI driver container.
+
 ## Reporting a Vulnerability
 
 Vulnerabilities can be reported by sending an email to [email protected]. A

go.mod

@@ -15,6 +15,7 @@ require (
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/opencontainers/selinux v1.11.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	go.uber.org/atomic v1.10.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect

go.sum

@@ -20,6 +20,8 @@ github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORN
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/opencontainers/selinux v1.11.0 h1:+5Zbo97w3Lbmb3PeqQtpmTkMwsW5nRI3YaLpt7tQ7oU=
+github.com/opencontainers/selinux v1.11.0/go.mod h1:E5dMC3VPuVvVHDYmi78qvhJp8+M586T4DlDRYpFkyec=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=

pkg/driver/driver.go

@@ -8,18 +8,24 @@ import (
 
 	"github.com/container-storage-interface/spec/lib/go/csi"
 	"github.com/go-logr/logr"
+	"github.com/opencontainers/selinux/go-selinux"
 	"github.com/spiffe/spiffe-csi/internal/version"
 	"github.com/spiffe/spiffe-csi/pkg/logkeys"
 	"github.com/spiffe/spiffe-csi/pkg/mount"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
 
+const (
+	seLinuxContainerFileLabel = "container_file_t"
+)
+
 var (
 	// We replace these in tests since bind mounting generally requires root.
 	bindMountRW  = mount.BindMountRW
 	unmount      = mount.Unmount
 	isMountPoint = mount.IsMountPoint
+	chcon        = selinux.Chcon
 )
 
 // Config is the configuration for the driver
@@ -49,6 +55,16 @@ func New(config Config) (*Driver, error) {
 	case config.WorkloadAPISocketDir == "":
 		return nil, errors.New("workload API socket directory is required")
 	}
+
+	// Set the SELinux label on the workload API directory. This allows the
+	// mount to be used within OpenShift, for example. This will fail if the
+	// Workload API socket directory is mounted read-only.
+	if err := chcon(config.WorkloadAPISocketDir, seLinuxContainerFileLabel, true); err != nil {
+		config.Log.Error(err, "Failed to set the container file label on the Workload API socket directory. Is the Workload API directory mounted read-write?")
+	} else {
+		config.Log.Info("Successfully set the container file label on the Workload API socket directory")
+	}
+
 	return &Driver{
 		log:                  config.Log,
 		nodeID:               config.NodeID,

pkg/driver/driver_test.go

@@ -34,31 +34,36 @@ func init() {
 	unmount = func(dst string) error {
 		return os.Remove(metaPath(dst))
 	}
+	chcon = writeSELinuxLabel
 }
 
 func TestNew(t *testing.T) {
 	workloadAPISocketDir := t.TempDir()
 
 	t.Run("node ID is required", func(t *testing.T) {
 		_, err := New(Config{
+			Log:                  logr.Discard(),
 			WorkloadAPISocketDir: workloadAPISocketDir,
 		})
 		require.EqualError(t, err, "node ID is required")
 	})
 
 	t.Run("workload API socket directory is required", func(t *testing.T) {
 		_, err := New(Config{
+			Log:    logr.Discard(),
 			NodeID: testNodeID,
 		})
 		require.EqualError(t, err, "workload API socket directory is required")
 	})
 
 	t.Run("success", func(t *testing.T) {
 		_, err := New(Config{
+			Log:                  logr.Discard(),
 			NodeID:               testNodeID,
 			WorkloadAPISocketDir: workloadAPISocketDir,
 		})
 		require.NoError(t, err)
+		assertSELinuxLabelWritten(t, workloadAPISocketDir)
 	})
 }
 
@@ -469,6 +474,13 @@ func assertNotMounted(t *testing.T, targetPath string) {
 	assert.Error(t, err, "should not be mounted")
 }
 
+func assertSELinuxLabelWritten(t *testing.T, fpath string) {
+	label, err := readSELinuxLabel(fpath)
+	if assert.NoError(t, err, "failed to read selinux label file") {
+		assert.Equal(t, "container_file_t-recursive-true", label)
+	}
+}
+
 func readMeta(targetPath string) (string, error) {
 	data, err := os.ReadFile(metaPath(targetPath))
 	return string(data), err
@@ -478,10 +490,23 @@ func writeMeta(targetPath string, meta string) error {
 	return os.WriteFile(metaPath(targetPath), []byte(meta), 0600)
 }
 
+func readSELinuxLabel(fpath string) (string, error) {
+	data, err := os.ReadFile(seLinuxLabelPath(fpath))
+	return string(data), err
+}
+
+func writeSELinuxLabel(fpath string, label string, recursive bool) error {
+	return os.WriteFile(seLinuxLabelPath(fpath), []byte(fmt.Sprintf("%s-recursive-%t", label, recursive)), 0600)
+}
+
 func metaPath(targetPath string) string {
 	return filepath.Join(targetPath, "meta")
 }
 
+func seLinuxLabelPath(targetPath string) string {
+	return filepath.Join(targetPath, "selinux-label")
+}
+
 func dumpIt(t *testing.T, when, dir string) {
 	t.Logf(">>>>>>>>>> DUMPING %s %s", when, dir)
 	assert.NoError(t, filepath.Walk(dir, filepath.WalkFunc(

test/config/spiffe-csi-driver.yaml

@@ -50,7 +50,7 @@ spec:
             # driver will mount this directory into containers.
             - mountPath: /spire-agent-socket
               name: spire-agent-socket-dir
-              readOnly: true
+                #readOnly: true
             # The volume that will contain the CSI driver socket shared
             # with the kubelet and the driver registrar.
             - mountPath: /spiffe-csi

test/run.sh

@@ -51,6 +51,14 @@ esac
 
 
 cleanup() {
+    if [ -z "${SUCCESS}" ]; then
+        "${KUBECTL}" logs deployment/spire-server -nspire-system --all-containers=true || true
+        "${KUBECTL}" logs daemonset/spire-agent -nspire-system --all-containers=true || true
+        "${KUBECTL}" logs daemonset/spiffe-csi-driver -nspire-system --all-containers=true || true
+        "${KUBECTL}" logs deployment/test-workload-1 --all-containers=true || true
+        "${KUBECTL}" logs deployment/test-workload-2 --all-containers=true || true
+    fi
+
     delete-cluster
     rm -rf "${TMPDIR}"
 }
@@ -104,6 +112,8 @@ apply-yaml() {
     "${KUBECTL}" rollout status -w --timeout=1m -nspire-system deployment/spire-server
     echo "Waiting for SPIRE agent rollout..."
     "${KUBECTL}" rollout status -w --timeout=1m -nspire-system daemonset/spire-agent
+    echo "Waiting for SPIFFE CSI driver rollout..."
+    "${KUBECTL}" rollout status -w --timeout=1m -nspire-system daemonset/spiffe-csi-driver
     echo "Waiting for test workload 1 rollout..."
     "${KUBECTL}" rollout status -w --timeout=1m deployment/test-workload-1
     echo "Waiting for test workload 2 rollout..."
@@ -159,5 +169,5 @@ apply-yaml
 register-workload
 check-workload-status "test-workload-1"
 check-workload-status "test-workload-2"
-"${KUBECTL}" logs -nspire-system daemonset/spiffe-csi-driver -c spiffe-csi-driver
+SUCCESS=1
 echo "Done."