containerd affected by a local privilege escalation via wide permissions on CRI directory

@@ -80,10 +80,16 @@ func CreateTopLevelDirectories(config *srvconfig.Config) error {
 		return errors.New("root and state must be different paths")
 	}
 
-	if err := sys.MkdirAllWithACL(config.Root, 0o711); err != nil {
+	if err := sys.MkdirAllWithACL(config.Root, 0o700); err != nil {
+		return err
+	}
+	// chmod is needed for upgrading from an older release that created the dir with 0o711
+	if err := os.Chmod(config.Root, 0o700); err != nil {
 		return err
 	}
 
+	// For supporting userns-remapped containers, the state dir cannot be just mkdired with 0o700.
+	// Each of plugins creates a dedicated directory beneath the state dir with appropriate permission bits.
 	if err := sys.MkdirAllWithACL(config.State, 0o711); err != nil {
 		return err
 	}
@@ -98,7 +104,11 @@ func CreateTopLevelDirectories(config *srvconfig.Config) error {
 	}
 
 	if config.TempDir != "" {
-		if err := sys.MkdirAllWithACL(config.TempDir, 0o711); err != nil {
+		if err := sys.MkdirAllWithACL(config.TempDir, 0o700); err != nil {
+			return err
+		}
+		// chmod is needed for upgrading from an older release that created the dir with 0o711
+		if err := os.Chmod(config.Root, 0o700); err != nil {
 			return err
 		}
 		if runtime.GOOS == "windows" {

@@ -92,6 +92,8 @@ func init() {
 			}
 			root, state := ic.Properties[plugins.PropertyRootDir], ic.Properties[plugins.PropertyStateDir]
 			for _, d := range []string{root, state} {
+				// root:  the parent of this directory is created as 0o700, not 0o711.
+				// state: the parent of this directory is created as 0o711 too, so as to support userns-remapped containers.
 				if err := os.MkdirAll(d, 0711); err != nil {
 					return nil, err
 				}

@@ -79,6 +79,13 @@ func initCRIRuntime(ic *plugin.InitContext) (interface{}, error) {
 	rootDir := filepath.Join(containerdRootDir, "io.containerd.grpc.v1.cri")
 	containerdStateDir := filepath.Dir(ic.Properties[plugins.PropertyStateDir])
 	stateDir := filepath.Join(containerdStateDir, "io.containerd.grpc.v1.cri")
+	if err := os.MkdirAll(stateDir, 0o700); err != nil {
+		return nil, err
+	}
+	// chmod is needed for upgrading from an older release that created the dir with 0o755
+	if err := os.Chmod(stateDir, 0o700); err != nil {
+		return nil, err
+	}
 	c := criconfig.Config{
 		RuntimeConfig:      *pluginConfig,
 		ContainerdRootDir:  containerdRootDir,

@@ -68,7 +68,11 @@ func init() {
 			state := ic.Properties[plugins.PropertyStateDir]
 			root := ic.Properties[plugins.PropertyRootDir]
 			for _, d := range []string{root, state} {
-				if err := os.MkdirAll(d, 0711); err != nil {
+				if err := os.MkdirAll(d, 0700); err != nil {
+					return nil, err
+				}
+				// chmod is needed for upgrading from an older release that created the dir with 0o711
+				if err := os.Chmod(d, 0o700); err != nil {
 					return nil, err
 				}
 			}