Lock down docker root dir perms.

Do not use 0701 perms.
0701 dir perms allows anyone to traverse the docker dir.
It happens to allow any user to execute, as an example, suid binaries
from image rootfs dirs because it allows traversal AND critically
container users need to be able to do execute things.

0701 on lower directories also happens to allow any user to modify
     things in, for instance, the overlay upper dir which neccessarily
     has 0755 permissions.

This changes to use 0710 which allows users in the group to traverse.
In userns mode the UID owner is (real) root and the GID is the remapped
root's GID.

This prevents anyone but the remapped root to traverse our directories
(which is required for userns with runc).

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit ef7237442147441a7cadcda0600be1186d81ac73)
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit 93ac040bf0c0b51d9a7fedaf994bf5bf1d68ee0e)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/container_operations_unix.go

@@ -458,5 +458,5 @@ func (daemon *Daemon) setupContainerMountsRoot(c *container.Container) error {
 	if err != nil {
 		return err
 	}
-	return idtools.MkdirAllAndChown(p, 0701, idtools.CurrentIdentity())
+	return idtools.MkdirAllAndChown(p, 0710, idtools.Identity{UID: idtools.CurrentIdentity().UID, GID: daemon.IdentityMapping().RootPair().GID})
 }

daemon/create.go

@@ -171,10 +171,11 @@ func (daemon *Daemon) create(opts createOpts) (retC *container.Container, retErr
 	}
 	ctr.RWLayer = rwLayer
 
-	if err := idtools.MkdirAndChown(ctr.Root, 0701, idtools.CurrentIdentity()); err != nil {
+	current := idtools.CurrentIdentity()
+	if err := idtools.MkdirAndChown(ctr.Root, 0710, idtools.Identity{UID: current.UID, GID: daemon.IdentityMapping().RootPair().GID}); err != nil {
 		return nil, err
 	}
-	if err := idtools.MkdirAndChown(ctr.CheckpointDir(), 0700, idtools.CurrentIdentity()); err != nil {
+	if err := idtools.MkdirAndChown(ctr.CheckpointDir(), 0700, current); err != nil {
 		return nil, err
 	}
 

daemon/daemon.go

@@ -845,7 +845,10 @@ func NewDaemon(ctx context.Context, config *config.Config, pluginStore *plugin.S
 	}
 
 	daemonRepo := filepath.Join(config.Root, "containers")
-	if err := idtools.MkdirAllAndChown(daemonRepo, 0701, idtools.CurrentIdentity()); err != nil {
+	if err := idtools.MkdirAllAndChown(daemonRepo, 0710, idtools.Identity{
+		UID: idtools.CurrentIdentity().UID,
+		GID: rootIDs.GID,
+	}); err != nil {
 		return nil, err
 	}
 

daemon/daemon_unix.go

@@ -1224,21 +1224,21 @@ func setupDaemonRoot(config *config.Config, rootDir string, remappedRoot idtools
 		}
 	}
 
+	id := idtools.Identity{UID: idtools.CurrentIdentity().UID, GID: remappedRoot.GID}
+	// First make sure the current root dir has the correct perms.
+	if err := idtools.MkdirAllAndChown(config.Root, 0710, id); err != nil {
+		return errors.Wrapf(err, "could not create or set daemon root permissions: %s", config.Root)
+	}
+
 	// if user namespaces are enabled we will create a subtree underneath the specified root
 	// with any/all specified remapped root uid/gid options on the daemon creating
 	// a new subdirectory with ownership set to the remapped uid/gid (so as to allow
 	// `chdir()` to work for containers namespaced to that uid/gid)
 	if config.RemappedRoot != "" {
-		id := idtools.CurrentIdentity()
-		// First make sure the current root dir has the correct perms.
-		if err := idtools.MkdirAllAndChown(config.Root, 0701, id); err != nil {
-			return errors.Wrapf(err, "could not create or set daemon root permissions: %s", config.Root)
-		}
-
 		config.Root = filepath.Join(rootDir, fmt.Sprintf("%d.%d", remappedRoot.UID, remappedRoot.GID))
 		logrus.Debugf("Creating user namespaced daemon root: %s", config.Root)
 		// Create the root directory if it doesn't exist
-		if err := idtools.MkdirAllAndChown(config.Root, 0701, id); err != nil {
+		if err := idtools.MkdirAllAndChown(config.Root, 0710, id); err != nil {
 			return fmt.Errorf("Cannot create daemon root: %s: %v", config.Root, err)
 		}
 		// we also need to verify that any pre-existing directories in the path to

daemon/graphdriver/aufs/aufs.go

@@ -130,14 +130,23 @@ func Init(root string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
 	}
 
 	currentID := idtools.CurrentIdentity()
+	_, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)
+	if err != nil {
+		return nil, err
+	}
+	dirID := idtools.Identity{
+		UID: currentID.UID,
+		GID: rootGID,
+	}
+
 	// Create the root aufs driver dir
-	if err := idtools.MkdirAllAndChown(root, 0701, currentID); err != nil {
+	if err := idtools.MkdirAllAndChown(root, 0710, dirID); err != nil {
 		return nil, err
 	}
 
 	// Populate the dir structure
 	for _, p := range paths {
-		if err := idtools.MkdirAllAndChown(path.Join(root, p), 0701, currentID); err != nil {
+		if err := idtools.MkdirAllAndChown(path.Join(root, p), 0710, dirID); err != nil {
 			return nil, err
 		}
 	}

daemon/graphdriver/btrfs/btrfs.go

@@ -71,7 +71,14 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
 		return nil, graphdriver.ErrPrerequisites
 	}
 
-	if err := idtools.MkdirAllAndChown(home, 0701, idtools.CurrentIdentity()); err != nil {
+	remappedRoot := idtools.NewIDMappingsFromMaps(uidMaps, gidMaps)
+	currentID := idtools.CurrentIdentity()
+	dirID := idtools.Identity{
+		UID: currentID.UID,
+		GID: remappedRoot.RootPair().GID,
+	}
+
+	if err := idtools.MkdirAllAndChown(home, 0710, dirID); err != nil {
 		return nil, err
 	}
 
@@ -488,7 +495,14 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error {
 	if err != nil {
 		return err
 	}
-	if err := idtools.MkdirAllAndChown(subvolumes, 0701, idtools.CurrentIdentity()); err != nil {
+
+	currentID := idtools.CurrentIdentity()
+	dirID := idtools.Identity{
+		UID: currentID.UID,
+		GID: rootGID,
+	}
+
+	if err := idtools.MkdirAllAndChown(subvolumes, 0710, dirID); err != nil {
 		return err
 	}
 	if parent == "" {

daemon/graphdriver/fuse-overlayfs/fuseoverlayfs.go

@@ -88,7 +88,17 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
 		return nil, graphdriver.ErrNotSupported
 	}
 
-	if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0701, idtools.CurrentIdentity()); err != nil {
+	remappedRoot := idtools.NewIDMappingsFromMaps(uidMaps, gidMaps)
+	currentID := idtools.CurrentIdentity()
+	dirID := idtools.Identity{
+		UID: currentID.UID,
+		GID: remappedRoot.RootPair().GID,
+	}
+
+	if err := idtools.MkdirAllAndChown(home, 0710, dirID); err != nil {
+		return nil, err
+	}
+	if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 700, currentID); err != nil {
 		return nil, err
 	}
 
@@ -173,11 +183,15 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr
 	}
 	root := idtools.Identity{UID: rootUID, GID: rootGID}
 
-	currentID := idtools.CurrentIdentity()
-	if err := idtools.MkdirAllAndChown(path.Dir(dir), 0701, currentID); err != nil {
+	dirID := idtools.Identity{
+		UID: rootUID,
+		GID: rootGID,
+	}
+
+	if err := idtools.MkdirAllAndChown(path.Dir(dir), 0710, dirID); err != nil {
 		return err
 	}
-	if err := idtools.MkdirAndChown(dir, 0701, currentID); err != nil {
+	if err := idtools.MkdirAndChown(dir, 0710, dirID); err != nil {
 		return err
 	}
 
@@ -211,7 +225,7 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr
 		return nil
 	}
 
-	if err := idtools.MkdirAndChown(path.Join(dir, workDirName), 0701, currentID); err != nil {
+	if err := idtools.MkdirAndChown(path.Join(dir, workDirName), 0710, dirID); err != nil {
 		return err
 	}
 

daemon/graphdriver/overlay/overlay.go

@@ -156,11 +156,20 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
 		logrus.WithField("storage-driver", "overlay").Warn(overlayutils.ErrDTypeNotSupported("overlay", backingFs))
 	}
 
-	// Create the driver home dir
-	if err := idtools.MkdirAllAndChown(home, 0701, idtools.CurrentIdentity()); err != nil {
+	currentID := idtools.CurrentIdentity()
+	_, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)
+	if err != nil {
 		return nil, err
 	}
+	dirID := idtools.Identity{
+		UID: currentID.UID,
+		GID: rootGID,
+	}
 
+	// Create the driver home dir
+	if err := idtools.MkdirAllAndChown(home, 0710, dirID); err != nil {
+		return nil, err
+	}
 	d := &Driver{
 		home:          home,
 		uidMaps:       uidMaps,
@@ -262,10 +271,11 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr
 	root := idtools.Identity{UID: rootUID, GID: rootGID}
 
 	currentID := idtools.CurrentIdentity()
-	if err := idtools.MkdirAllAndChown(path.Dir(dir), 0701, currentID); err != nil {
-		return err
+	dirID := idtools.Identity{
+		UID: currentID.UID,
+		GID: rootGID,
 	}
-	if err := idtools.MkdirAndChown(dir, 0701, currentID); err != nil {
+	if err := idtools.MkdirAndChown(dir, 0710, dirID); err != nil {
 		return err
 	}
 

daemon/graphdriver/overlay2/overlay.go

@@ -165,7 +165,20 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
 		logger.Warn(overlayutils.ErrDTypeNotSupported("overlay2", backingFs))
 	}
 
-	if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0701, idtools.CurrentIdentity()); err != nil {
+	_, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)
+	if err != nil {
+		return nil, err
+	}
+
+	cur := idtools.CurrentIdentity()
+	dirID := idtools.Identity{
+		UID: cur.UID,
+		GID: rootGID,
+	}
+	if err := idtools.MkdirAllAndChown(home, 0710, dirID); err != nil {
+		return nil, err
+	}
+	if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0700, cur); err != nil {
 		return nil, err
 	}
 
@@ -344,12 +357,15 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr
 		return err
 	}
 	root := idtools.Identity{UID: rootUID, GID: rootGID}
-	current := idtools.CurrentIdentity()
+	dirID := idtools.Identity{
+		UID: idtools.CurrentIdentity().UID,
+		GID: rootGID,
+	}
 
-	if err := idtools.MkdirAllAndChown(path.Dir(dir), 0701, current); err != nil {
+	if err := idtools.MkdirAllAndChown(path.Dir(dir), 0710, dirID); err != nil {
 		return err
 	}
-	if err := idtools.MkdirAndChown(dir, 0701, current); err != nil {
+	if err := idtools.MkdirAndChown(dir, 0710, dirID); err != nil {
 		return err
 	}
 

daemon/graphdriver/vfs/driver.go

@@ -37,8 +37,16 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
 	if err := d.parseOptions(options); err != nil {
 		return nil, err
 	}
+	_, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)
+	if err != nil {
+		return nil, err
+	}
 
-	if err := idtools.MkdirAllAndChown(home, 0701, idtools.CurrentIdentity()); err != nil {
+	dirID := idtools.Identity{
+		UID: idtools.CurrentIdentity().UID,
+		GID: rootGID,
+	}
+	if err := idtools.MkdirAllAndChown(home, 0710, dirID); err != nil {
 		return nil, err
 	}
 
@@ -140,7 +148,12 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error {
 func (d *Driver) create(id, parent string, size uint64) error {
 	dir := d.dir(id)
 	rootIDs := d.idMapping.RootPair()
-	if err := idtools.MkdirAllAndChown(filepath.Dir(dir), 0701, idtools.CurrentIdentity()); err != nil {
+
+	dirID := idtools.Identity{
+		UID: idtools.CurrentIdentity().UID,
+		GID: rootIDs.GID,
+	}
+	if err := idtools.MkdirAllAndChown(filepath.Dir(dir), 0710, dirID); err != nil {
 		return err
 	}
 	if err := idtools.MkdirAndChown(dir, 0755, rootIDs); err != nil {

daemon/graphdriver/zfs/zfs.go

@@ -105,7 +105,16 @@ func Init(base string, opt []string, uidMaps, gidMaps []idtools.IDMap) (graphdri
 		return nil, fmt.Errorf("BUG: zfs get all -t filesystem -rHp '%s' should contain '%s'", options.fsName, options.fsName)
 	}
 
-	if err := idtools.MkdirAllAndChown(base, 0701, idtools.CurrentIdentity()); err != nil {
+	_, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)
+	if err != nil {
+		return nil, err
+	}
+
+	dirID := idtools.Identity{
+		UID: idtools.CurrentIdentity().UID,
+		GID: rootGID,
+	}
+	if err := idtools.MkdirAllAndChown(base, 0710, dirID); err != nil {
 		return nil, fmt.Errorf("Failed to create '%s': %v", base, err)
 	}