From e908cc39018c015084ffbffbc5703ccba5c2fbb7 Mon Sep 17 00:00:00 2001 From: Brian Goff Date: Tue, 6 Oct 2020 19:43:24 +0000 Subject: [PATCH] Use real root with 0701 perms Various dirs in /var/lib/docker contain data that needs to be mounted into a container. For this reason, these dirs are set to be owned by the remapped root user, otherwise there can be permissions issues. However, this uneccessarily exposes these dirs to an unprivileged user on the host. Instead, set the ownership of these dirs to the real root (or rather the UID/GID of dockerd) with 0701 permissions, which allows the remapped root to enter the directories but not read/write to them. The remapped root needs to enter these dirs so the container's rootfs can be configured... e.g. to mount /etc/resolve.conf. This prevents an unprivileged user from having read/write access to these dirs on the host. The flip side of this is now any user can enter these directories. Signed-off-by: Brian Goff --- daemon/container_operations_unix.go | 2 +- daemon/create.go | 6 ++---- daemon/daemon.go | 2 +- daemon/daemon_unix.go | 14 ++++++++++---- daemon/graphdriver/aufs/aufs.go | 9 +++------ daemon/graphdriver/btrfs/btrfs.go | 10 +++------- .../graphdriver/fuse-overlayfs/fuseoverlayfs.go | 14 +++++--------- daemon/graphdriver/overlay/overlay.go | 16 +++++++--------- daemon/graphdriver/overlay2/overlay.go | 12 ++++-------- daemon/graphdriver/vfs/driver.go | 5 ++--- daemon/graphdriver/zfs/zfs.go | 6 +----- volume/local/local.go | 11 +++++++++-- 12 files changed, 48 insertions(+), 59 deletions(-) diff --git a/daemon/container_operations_unix.go b/daemon/container_operations_unix.go index f4f1bd2c0b..5521adbd27 100644 --- a/daemon/container_operations_unix.go +++ b/daemon/container_operations_unix.go @@ -466,5 +466,5 @@ func (daemon *Daemon) setupContainerMountsRoot(c *container.Container) error { if err != nil { return err } - return idtools.MkdirAllAndChown(p, 0700, daemon.idMapping.RootPair()) + return idtools.MkdirAllAndChown(p, 0701, idtools.CurrentIdentity()) } diff --git a/daemon/create.go b/daemon/create.go index d4aeb77c7b..e0d6eeea8b 100644 --- a/daemon/create.go +++ b/daemon/create.go @@ -211,12 +211,10 @@ func (daemon *Daemon) create(opts createOpts) (retC *container.Container, retErr } ctr.RWLayer = rwLayer - rootIDs := daemon.idMapping.RootPair() - - if err := idtools.MkdirAndChown(ctr.Root, 0700, rootIDs); err != nil { + if err := idtools.MkdirAndChown(ctr.Root, 0701, idtools.CurrentIdentity()); err != nil { return nil, err } - if err := idtools.MkdirAndChown(ctr.CheckpointDir(), 0700, rootIDs); err != nil { + if err := idtools.MkdirAndChown(ctr.CheckpointDir(), 0700, idtools.CurrentIdentity()); err != nil { return nil, err } diff --git a/daemon/daemon.go b/daemon/daemon.go index ab0db4fa06..794ff9712d 100644 --- a/daemon/daemon.go +++ b/daemon/daemon.go @@ -861,7 +861,7 @@ func NewDaemon(ctx context.Context, config *config.Config, pluginStore *plugin.S } daemonRepo := filepath.Join(config.Root, "containers") - if err := idtools.MkdirAllAndChown(daemonRepo, 0700, rootIDs); err != nil { + if err := idtools.MkdirAllAndChown(daemonRepo, 0701, idtools.CurrentIdentity()); err != nil { return nil, err } diff --git a/daemon/daemon_unix.go b/daemon/daemon_unix.go index 5fa688dff4..b477275228 100644 --- a/daemon/daemon_unix.go +++ b/daemon/daemon_unix.go @@ -1196,7 +1196,7 @@ func setupRemappedRoot(config *config.Config) (*idtools.IdentityMapping, error) return &idtools.IdentityMapping{}, nil } -func setupDaemonRoot(config *config.Config, rootDir string, rootIdentity idtools.Identity) error { +func setupDaemonRoot(config *config.Config, rootDir string, remappedRoot idtools.Identity) error { config.Root = rootDir // the docker root metadata directory needs to have execute permissions for all users (g+x,o+x) // so that syscalls executing as non-root, operating on subdirectories of the graph root @@ -1221,10 +1221,16 @@ func setupDaemonRoot(config *config.Config, rootDir string, rootIdentity idtools // 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 != "" { - config.Root = filepath.Join(rootDir, fmt.Sprintf("%d.%d", rootIdentity.UID, rootIdentity.GID)) + 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, 0700, rootIdentity); err != nil { + if err := idtools.MkdirAllAndChown(config.Root, 0701, 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 @@ -1237,7 +1243,7 @@ func setupDaemonRoot(config *config.Config, rootDir string, rootIdentity idtools if dirPath == "/" { break } - if !idtools.CanAccess(dirPath, rootIdentity) { + if !idtools.CanAccess(dirPath, remappedRoot) { return fmt.Errorf("a subdirectory in your graphroot path (%s) restricts access to the remapped root uid/gid; please fix by allowing 'o+x' permissions on existing directories", config.Root) } } diff --git a/daemon/graphdriver/aufs/aufs.go b/daemon/graphdriver/aufs/aufs.go index 4ecc647bdd..b007274e13 100644 --- a/daemon/graphdriver/aufs/aufs.go +++ b/daemon/graphdriver/aufs/aufs.go @@ -129,18 +129,15 @@ func Init(root string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap locker: locker.New(), } - rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps) - if err != nil { - return nil, err - } + currentID := idtools.CurrentIdentity() // Create the root aufs driver dir - if err := idtools.MkdirAllAndChown(root, 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(root, 0701, currentID); err != nil { return nil, err } // Populate the dir structure for _, p := range paths { - if err := idtools.MkdirAllAndChown(path.Join(root, p), 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(path.Join(root, p), 0701, currentID); err != nil { return nil, err } } diff --git a/daemon/graphdriver/btrfs/btrfs.go b/daemon/graphdriver/btrfs/btrfs.go index 1866b07b88..f9127472f8 100644 --- a/daemon/graphdriver/btrfs/btrfs.go +++ b/daemon/graphdriver/btrfs/btrfs.go @@ -70,11 +70,7 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap return nil, graphdriver.ErrPrerequisites } - rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps) - if err != nil { - return nil, err - } - if err := idtools.MkdirAllAndChown(home, 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(home, 0701, idtools.CurrentIdentity()); err != nil { return nil, err } @@ -525,7 +521,7 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error { if err != nil { return err } - if err := idtools.MkdirAllAndChown(subvolumes, 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(subvolumes, 0701, idtools.CurrentIdentity()); err != nil { return err } if parent == "" { @@ -560,7 +556,7 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error { if err := d.setStorageSize(path.Join(subvolumes, id), driver); err != nil { return err } - if err := idtools.MkdirAllAndChown(quotas, 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(quotas, 0700, idtools.CurrentIdentity()); err != nil { return err } if err := ioutil.WriteFile(path.Join(quotas, id), []byte(fmt.Sprint(driver.options.size)), 0644); err != nil { diff --git a/daemon/graphdriver/fuse-overlayfs/fuseoverlayfs.go b/daemon/graphdriver/fuse-overlayfs/fuseoverlayfs.go index e906cda74d..782e8be984 100644 --- a/daemon/graphdriver/fuse-overlayfs/fuseoverlayfs.go +++ b/daemon/graphdriver/fuse-overlayfs/fuseoverlayfs.go @@ -88,12 +88,7 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap return nil, graphdriver.ErrNotSupported } - rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps) - if err != nil { - return nil, err - } - // Create the driver home dir - if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0701, idtools.CurrentIdentity()); err != nil { return nil, err } @@ -178,10 +173,11 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr } root := idtools.Identity{UID: rootUID, GID: rootGID} - if err := idtools.MkdirAllAndChown(path.Dir(dir), 0700, root); err != nil { + currentID := idtools.CurrentIdentity() + if err := idtools.MkdirAllAndChown(path.Dir(dir), 0701, currentID); err != nil { return err } - if err := idtools.MkdirAndChown(dir, 0700, root); err != nil { + if err := idtools.MkdirAndChown(dir, 0701, currentID); err != nil { return err } @@ -215,7 +211,7 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr return nil } - if err := idtools.MkdirAndChown(path.Join(dir, workDirName), 0700, root); err != nil { + if err := idtools.MkdirAndChown(path.Join(dir, workDirName), 0701, currentID); err != nil { return err } diff --git a/daemon/graphdriver/overlay/overlay.go b/daemon/graphdriver/overlay/overlay.go index 1cffc1b896..90be0e3d64 100644 --- a/daemon/graphdriver/overlay/overlay.go +++ b/daemon/graphdriver/overlay/overlay.go @@ -156,12 +156,8 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap logrus.WithField("storage-driver", "overlay").Warn(overlayutils.ErrDTypeNotSupported("overlay", backingFs)) } - rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps) - if err != nil { - return nil, err - } // Create the driver home dir - if err := idtools.MkdirAllAndChown(home, 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(home, 0701, idtools.CurrentIdentity()); err != nil { return nil, err } @@ -265,10 +261,11 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr } root := idtools.Identity{UID: rootUID, GID: rootGID} - if err := idtools.MkdirAllAndChown(path.Dir(dir), 0700, root); err != nil { + currentID := idtools.CurrentIdentity() + if err := idtools.MkdirAllAndChown(path.Dir(dir), 0701, currentID); err != nil { return err } - if err := idtools.MkdirAndChown(dir, 0700, root); err != nil { + if err := idtools.MkdirAndChown(dir, 0701, currentID); err != nil { return err } @@ -281,6 +278,7 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr // Toplevel images are just a "root" dir if parent == "" { + // This must be 0755 otherwise unprivileged users will in the container will not be able to read / in the container return idtools.MkdirAndChown(path.Join(dir, "root"), 0755, root) } @@ -301,7 +299,7 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr if err := idtools.MkdirAndChown(path.Join(dir, "work"), 0700, root); err != nil { return err } - return ioutil.WriteFile(path.Join(dir, "lower-id"), []byte(parent), 0666) + return ioutil.WriteFile(path.Join(dir, "lower-id"), []byte(parent), 0600) } // Otherwise, copy the upper and the lower-id from the parent @@ -311,7 +309,7 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr return err } - if err := ioutil.WriteFile(path.Join(dir, "lower-id"), lowerID, 0666); err != nil { + if err := ioutil.WriteFile(path.Join(dir, "lower-id"), lowerID, 0600); err != nil { return err } diff --git a/daemon/graphdriver/overlay2/overlay.go b/daemon/graphdriver/overlay2/overlay.go index 11d53029ca..e26fa07c82 100644 --- a/daemon/graphdriver/overlay2/overlay.go +++ b/daemon/graphdriver/overlay2/overlay.go @@ -165,12 +165,7 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap logger.Warn(overlayutils.ErrDTypeNotSupported("overlay2", backingFs)) } - rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps) - if err != nil { - return nil, err - } - // Create the driver home dir - if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0701, idtools.CurrentIdentity()); err != nil { return nil, err } @@ -339,11 +334,12 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr return err } root := idtools.Identity{UID: rootUID, GID: rootGID} + current := idtools.CurrentIdentity() - if err := idtools.MkdirAllAndChown(path.Dir(dir), 0700, root); err != nil { + if err := idtools.MkdirAllAndChown(path.Dir(dir), 0701, current); err != nil { return err } - if err := idtools.MkdirAndChown(dir, 0700, root); err != nil { + if err := idtools.MkdirAndChown(dir, 0701, current); err != nil { return err } diff --git a/daemon/graphdriver/vfs/driver.go b/daemon/graphdriver/vfs/driver.go index b341de5b89..af9b107609 100644 --- a/daemon/graphdriver/vfs/driver.go +++ b/daemon/graphdriver/vfs/driver.go @@ -38,8 +38,7 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap return nil, err } - rootIDs := d.idMapping.RootPair() - if err := idtools.MkdirAllAndChown(home, 0700, rootIDs); err != nil { + if err := idtools.MkdirAllAndChown(home, 0701, idtools.CurrentIdentity()); err != nil { return nil, err } @@ -141,7 +140,7 @@ 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), 0700, rootIDs); err != nil { + if err := idtools.MkdirAllAndChown(filepath.Dir(dir), 0701, idtools.CurrentIdentity()); err != nil { return err } if err := idtools.MkdirAndChown(dir, 0755, rootIDs); err != nil { diff --git a/daemon/graphdriver/zfs/zfs.go b/daemon/graphdriver/zfs/zfs.go index 21c271e2ec..f9099a2094 100644 --- a/daemon/graphdriver/zfs/zfs.go +++ b/daemon/graphdriver/zfs/zfs.go @@ -104,11 +104,7 @@ 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) } - rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps) - if err != nil { - return nil, fmt.Errorf("Failed to get root uid/guid: %v", err) - } - if err := idtools.MkdirAllAndChown(base, 0700, idtools.Identity{UID: rootUID, GID: rootGID}); err != nil { + if err := idtools.MkdirAllAndChown(base, 0701, idtools.CurrentIdentity()); err != nil { return nil, fmt.Errorf("Failed to create '%s': %v", base, err) } diff --git a/volume/local/local.go b/volume/local/local.go index 89252cf627..088502f43b 100644 --- a/volume/local/local.go +++ b/volume/local/local.go @@ -50,7 +50,7 @@ type activeMount struct { func New(scope string, rootIdentity idtools.Identity) (*Root, error) { rootDirectory := filepath.Join(scope, volumesPathName) - if err := idtools.MkdirAllAndChown(rootDirectory, 0700, rootIdentity); err != nil { + if err := idtools.MkdirAllAndChown(rootDirectory, 0701, idtools.CurrentIdentity()); err != nil { return nil, err } @@ -153,8 +153,15 @@ func (r *Root) Create(name string, opts map[string]string) (volume.Volume, error } path := r.DataPath(name) + volRoot := filepath.Dir(path) + // Root dir does not need to be accessed by the remapped root + if err := idtools.MkdirAllAndChown(volRoot, 0701, idtools.CurrentIdentity()); err != nil { + return nil, errors.Wrapf(errdefs.System(err), "error while creating volume root path '%s'", volRoot) + } + + // Remapped root does need access to the data path if err := idtools.MkdirAllAndChown(path, 0755, r.rootIdentity); err != nil { - return nil, errors.Wrapf(errdefs.System(err), "error while creating volume path '%s'", path) + return nil, errors.Wrapf(errdefs.System(err), "error while creating volume data path '%s'", path) } var err error