From 44d54d7d6067ec64b6e14b3b631e8a4e7b8a4e35 Mon Sep 17 00:00:00 2001 From: Brian Goff Date: Tue, 6 Oct 2020 19:43:24 +0000 Subject: [PATCH] [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 (cherry picked from commit e908cc39018c015084ffbffbc5703ccba5c2fbb7) Cherry-pick conflict with eb14d936bfc296f0a85bf4dc9e9bb1f4b4a01282: Kept old `container` variable name. Signed-off-by: Tibor Vass Gbp-Pq: Name cve-2021-21284-3.patch --- engine/daemon/container_operations_unix.go | 2 +- engine/daemon/create.go | 6 ++---- engine/daemon/daemon.go | 2 +- engine/daemon/daemon_unix.go | 14 ++++++++++---- engine/daemon/graphdriver/aufs/aufs.go | 9 +++------ engine/daemon/graphdriver/btrfs/btrfs.go | 10 +++------- engine/daemon/graphdriver/overlay/overlay.go | 16 +++++++--------- engine/daemon/graphdriver/overlay2/overlay.go | 12 ++++-------- engine/daemon/graphdriver/vfs/driver.go | 5 ++--- engine/daemon/graphdriver/zfs/zfs.go | 6 +----- engine/volume/local/local.go | 11 +++++++++-- 11 files changed, 43 insertions(+), 50 deletions(-) diff --git a/engine/daemon/container_operations_unix.go b/engine/daemon/container_operations_unix.go index 9953c7f3..6c58cb7b 100644 --- a/engine/daemon/container_operations_unix.go +++ b/engine/daemon/container_operations_unix.go @@ -407,5 +407,5 @@ 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/engine/daemon/create.go b/engine/daemon/create.go index 1afb1beb..eba24532 100644 --- a/engine/daemon/create.go +++ b/engine/daemon/create.go @@ -161,12 +161,10 @@ func (daemon *Daemon) create(params types.ContainerCreateConfig, managed bool) ( } container.RWLayer = rwLayer - rootIDs := daemon.idMapping.RootPair() - - if err := idtools.MkdirAndChown(container.Root, 0700, rootIDs); err != nil { + if err := idtools.MkdirAndChown(container.Root, 0701, idtools.CurrentIdentity()); err != nil { return nil, err } - if err := idtools.MkdirAndChown(container.CheckpointDir(), 0700, rootIDs); err != nil { + if err := idtools.MkdirAndChown(container.CheckpointDir(), 0700, idtools.CurrentIdentity()); err != nil { return nil, err } diff --git a/engine/daemon/daemon.go b/engine/daemon/daemon.go index be4e8d5d..11edf29b 100644 --- a/engine/daemon/daemon.go +++ b/engine/daemon/daemon.go @@ -740,7 +740,7 @@ 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/engine/daemon/daemon_unix.go b/engine/daemon/daemon_unix.go index dab30a27..dce8767a 100644 --- a/engine/daemon/daemon_unix.go +++ b/engine/daemon/daemon_unix.go @@ -1133,7 +1133,7 @@ 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 @@ -1158,10 +1158,16 @@ 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 @@ -1174,7 +1180,7 @@ 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/engine/daemon/graphdriver/aufs/aufs.go b/engine/daemon/graphdriver/aufs/aufs.go index 114aa9a6..b6d8466b 100644 --- a/engine/daemon/graphdriver/aufs/aufs.go +++ b/engine/daemon/graphdriver/aufs/aufs.go @@ -130,18 +130,15 @@ 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/engine/daemon/graphdriver/btrfs/btrfs.go b/engine/daemon/graphdriver/btrfs/btrfs.go index 7ce7edef..91d20ead 100644 --- a/engine/daemon/graphdriver/btrfs/btrfs.go +++ b/engine/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/engine/daemon/graphdriver/overlay/overlay.go b/engine/daemon/graphdriver/overlay/overlay.go index 08c05e19..a108be35 100644 --- a/engine/daemon/graphdriver/overlay/overlay.go +++ b/engine/daemon/graphdriver/overlay/overlay.go @@ -163,12 +163,8 @@ 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 } @@ -293,10 +289,11 @@ 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 } @@ -309,6 +306,7 @@ 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) } @@ -329,7 +327,7 @@ 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 @@ -339,7 +337,7 @@ 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/engine/daemon/graphdriver/overlay2/overlay.go b/engine/daemon/graphdriver/overlay2/overlay.go index 6da1f25a..ff54ff5b 100644 --- a/engine/daemon/graphdriver/overlay2/overlay.go +++ b/engine/daemon/graphdriver/overlay2/overlay.go @@ -196,12 +196,7 @@ 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 } @@ -391,11 +386,12 @@ 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/engine/daemon/graphdriver/vfs/driver.go b/engine/daemon/graphdriver/vfs/driver.go index 33e6bf6c..ae540a4b 100644 --- a/engine/daemon/graphdriver/vfs/driver.go +++ b/engine/daemon/graphdriver/vfs/driver.go @@ -30,8 +30,7 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap home: home, idMapping: idtools.NewIDMappingsFromMaps(uidMaps, gidMaps), } - 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 } @@ -106,7 +105,7 @@ 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/engine/daemon/graphdriver/zfs/zfs.go b/engine/daemon/graphdriver/zfs/zfs.go index 8a798778..3d2431d6 100644 --- a/engine/daemon/graphdriver/zfs/zfs.go +++ b/engine/daemon/graphdriver/zfs/zfs.go @@ -102,11 +102,7 @@ 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/engine/volume/local/local.go b/engine/volume/local/local.go index 7190de9e..a4e1e614 100644 --- a/engine/volume/local/local.go +++ b/engine/volume/local/local.go @@ -49,7 +49,7 @@ 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 } @@ -146,8 +146,15 @@ 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 -- 2.30.2