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4300a52606
Kernel 5.11 introduced support for rootless overlayfs, but incompatible with SELinux. On the other hand, fuse-overlayfs is compatible. Close issue 42333 Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
79 lines
2.7 KiB
Go
79 lines
2.7 KiB
Go
// +build linux
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package overlayutils // import "github.com/docker/docker/daemon/graphdriver/overlayutils"
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import (
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"fmt"
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"io/ioutil"
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"os"
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"path"
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"path/filepath"
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"github.com/docker/docker/daemon/graphdriver"
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"github.com/pkg/errors"
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"github.com/sirupsen/logrus"
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"golang.org/x/sys/unix"
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)
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// ErrDTypeNotSupported denotes that the backing filesystem doesn't support d_type.
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func ErrDTypeNotSupported(driver, backingFs string) error {
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msg := fmt.Sprintf("%s: the backing %s filesystem is formatted without d_type support, which leads to incorrect behavior.", driver, backingFs)
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if backingFs == "xfs" {
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msg += " Reformat the filesystem with ftype=1 to enable d_type support."
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}
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if backingFs == "extfs" {
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msg += " Reformat the filesystem (or use tune2fs) with -O filetype flag to enable d_type support."
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}
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msg += " Backing filesystems without d_type support are not supported."
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return graphdriver.NotSupportedError(msg)
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}
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// SupportsOverlay checks if the system supports overlay filesystem
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// by performing an actual overlay mount.
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//
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// checkMultipleLowers parameter enables check for multiple lowerdirs,
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// which is required for the overlay2 driver.
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func SupportsOverlay(d string, checkMultipleLowers bool) error {
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// We can't rely on go-selinux.GetEnabled() to detect whether SELinux is enabled,
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// because RootlessKit doesn't mount /sys/fs/selinux in the child: https://github.com/rootless-containers/rootlesskit/issues/94
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// So we check $_DOCKERD_ROOTLESS_SELINUX, which is set by dockerd-rootless.sh .
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if os.Getenv("_DOCKERD_ROOTLESS_SELINUX") == "1" {
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// Kernel 5.11 introduced support for rootless overlayfs, but incompatible with SELinux,
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// so fallback to fuse-overlayfs.
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// https://github.com/moby/moby/issues/42333
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return errors.New("overlay is not supported for Rootless with SELinux")
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}
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td, err := ioutil.TempDir(d, "check-overlayfs-support")
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if err != nil {
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return err
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}
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defer func() {
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if err := os.RemoveAll(td); err != nil {
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logrus.Warnf("Failed to remove check directory %v: %v", td, err)
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}
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}()
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for _, dir := range []string{"lower1", "lower2", "upper", "work", "merged"} {
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if err := os.Mkdir(filepath.Join(td, dir), 0755); err != nil {
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return err
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}
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}
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mnt := filepath.Join(td, "merged")
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lowerDir := path.Join(td, "lower2")
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if checkMultipleLowers {
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lowerDir += ":" + path.Join(td, "lower1")
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}
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opts := fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", lowerDir, path.Join(td, "upper"), path.Join(td, "work"))
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if err := unix.Mount("overlay", mnt, "overlay", 0, opts); err != nil {
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return errors.Wrap(err, "failed to mount overlay")
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}
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if err := unix.Unmount(mnt, 0); err != nil {
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logrus.Warnf("Failed to unmount check directory %v: %v", mnt, err)
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}
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return nil
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}
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