/
overlay.go
2240 lines (2029 loc) · 70.9 KB
/
overlay.go
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//go:build linux
// +build linux
package overlay
import (
"bytes"
"encoding/base64"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"path"
"path/filepath"
"strconv"
"strings"
"sync"
"syscall"
graphdriver "github.com/containers/storage/drivers"
"github.com/containers/storage/drivers/overlayutils"
"github.com/containers/storage/drivers/quota"
"github.com/containers/storage/pkg/archive"
"github.com/containers/storage/pkg/chrootarchive"
"github.com/containers/storage/pkg/directory"
"github.com/containers/storage/pkg/fsutils"
"github.com/containers/storage/pkg/idtools"
"github.com/containers/storage/pkg/locker"
"github.com/containers/storage/pkg/mount"
"github.com/containers/storage/pkg/parsers"
"github.com/containers/storage/pkg/system"
"github.com/containers/storage/pkg/unshare"
units "github.com/docker/go-units"
"github.com/hashicorp/go-multierror"
digest "github.com/opencontainers/go-digest"
"github.com/opencontainers/runc/libcontainer/userns"
"github.com/opencontainers/selinux/go-selinux"
"github.com/opencontainers/selinux/go-selinux/label"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"github.com/vbatts/tar-split/tar/storage"
"golang.org/x/sys/unix"
)
var (
// untar defines the untar method
untar = chrootarchive.UntarUncompressed
)
const (
defaultPerms = os.FileMode(0555)
selinuxLabelTest = "system_u:object_r:container_file_t:s0"
)
// This backend uses the overlay union filesystem for containers
// with diff directories for each layer.
// This version of the overlay driver requires at least kernel
// 4.0.0 in order to support mounting multiple diff directories.
// Each container/image has at least a "diff" directory and "link" file.
// If there is also a "lower" file when there are diff layers
// below as well as "merged" and "work" directories. The "diff" directory
// has the upper layer of the overlay and is used to capture any
// changes to the layer. The "lower" file contains all the lower layer
// mounts separated by ":" and ordered from uppermost to lowermost
// layers. The overlay itself is mounted in the "merged" directory,
// and the "work" dir is needed for overlay to work.
// The "link" file for each layer contains a unique string for the layer.
// Under the "l" directory at the root there will be a symbolic link
// with that unique string pointing the "diff" directory for the layer.
// The symbolic links are used to reference lower layers in the "lower"
// file and on mount. The links are used to shorten the total length
// of a layer reference without requiring changes to the layer identifier
// or root directory. Mounts are always done relative to root and
// referencing the symbolic links in order to ensure the number of
// lower directories can fit in a single page for making the mount
// syscall. A hard upper limit of 128 lower layers is enforced to ensure
// that mounts do not fail due to length.
const (
linkDir = "l"
lowerFile = "lower"
maxDepth = 128
// idLength represents the number of random characters
// which can be used to create the unique link identifier
// for every layer. If this value is too long then the
// page size limit for the mount command may be exceeded.
// The idLength should be selected such that following equation
// is true (512 is a buffer for label metadata).
// ((idLength + len(linkDir) + 1) * maxDepth) <= (pageSize - 512)
idLength = 26
)
type overlayOptions struct {
imageStores []string
layerStores []additionalLayerStore
quota quota.Quota
mountProgram string
skipMountHome bool
mountOptions string
ignoreChownErrors bool
forceMask *os.FileMode
}
// Driver contains information about the home directory and the list of active mounts that are created using this driver.
type Driver struct {
name string
home string
runhome string
uidMaps []idtools.IDMap
gidMaps []idtools.IDMap
ctr *graphdriver.RefCounter
quotaCtl *quota.Control
options overlayOptions
naiveDiff graphdriver.DiffDriver
supportsDType bool
supportsVolatile *bool
usingMetacopy bool
locker *locker.Locker
}
type additionalLayerStore struct {
// path is the directory where this store is available on the host.
path string
// withReference is true when the store contains image reference information (base64-encoded)
// in its layer search path so the path to the diff will be
// <path>/base64(reference)/<layerdigest>/
withReference bool
}
var (
backingFs = "<unknown>"
projectQuotaSupported = false
useNaiveDiffLock sync.Once
useNaiveDiffOnly bool
)
func init() {
graphdriver.Register("overlay", Init)
graphdriver.Register("overlay2", Init)
}
func hasMetacopyOption(opts []string) bool {
for _, s := range opts {
if s == "metacopy=on" {
return true
}
}
return false
}
func stripOption(opts []string, option string) []string {
for i, s := range opts {
if s == option {
return stripOption(append(opts[:i], opts[i+1:]...), option)
}
}
return opts
}
func hasVolatileOption(opts []string) bool {
for _, s := range opts {
if s == "volatile" {
return true
}
}
return false
}
func getMountProgramFlagFile(path string) string {
return filepath.Join(path, ".has-mount-program")
}
func checkSupportVolatile(home, runhome string) (bool, error) {
feature := fmt.Sprintf("volatile")
volatileCacheResult, _, err := cachedFeatureCheck(runhome, feature)
var usingVolatile bool
if err == nil {
if volatileCacheResult {
logrus.Debugf("Cached value indicated that volatile is being used")
} else {
logrus.Debugf("Cached value indicated that volatile is not being used")
}
usingVolatile = volatileCacheResult
} else {
usingVolatile, err = doesVolatile(home)
if err == nil {
if usingVolatile {
logrus.Debugf("overlay: test mount indicated that volatile is being used")
} else {
logrus.Debugf("overlay: test mount indicated that volatile is not being used")
}
if err = cachedFeatureRecord(runhome, feature, usingVolatile, ""); err != nil {
return false, errors.Wrap(err, "recording volatile-being-used status")
}
}
}
return usingVolatile, nil
}
// checkAndRecordIDMappedSupport checks and stores if the kernel supports mounting overlay on top of a
// idmapped lower layer.
func checkAndRecordIDMappedSupport(home, runhome string) (bool, error) {
feature := "idmapped-lower-dir"
overlayCacheResult, overlayCacheText, err := cachedFeatureCheck(runhome, feature)
if err == nil {
if overlayCacheResult {
logrus.Debugf("Cached value indicated that overlay is supported")
} else {
logrus.Debugf("Cached value indicated that overlay is not supported")
}
if !overlayCacheResult {
return false, errors.New(overlayCacheText)
}
return true, nil
}
supportsIDMappedMounts, err := supportsIdmappedLowerLayers(home)
if err2 := cachedFeatureRecord(runhome, feature, supportsIDMappedMounts, ""); err2 != nil {
return false, errors.Wrap(err2, "recording overlay idmapped mounts support status")
}
return supportsIDMappedMounts, err
}
func checkAndRecordOverlaySupport(fsMagic graphdriver.FsMagic, home, runhome string) (bool, error) {
var supportsDType bool
if os.Geteuid() != 0 {
return false, nil
}
feature := "overlay"
overlayCacheResult, overlayCacheText, err := cachedFeatureCheck(runhome, feature)
if err == nil {
if overlayCacheResult {
logrus.Debugf("Cached value indicated that overlay is supported")
} else {
logrus.Debugf("Cached value indicated that overlay is not supported")
}
supportsDType = overlayCacheResult
if !supportsDType {
return false, errors.New(overlayCacheText)
}
} else {
supportsDType, err = supportsOverlay(home, fsMagic, 0, 0)
if err != nil {
os.Remove(filepath.Join(home, linkDir))
os.Remove(home)
patherr, ok := err.(*os.PathError)
if ok && patherr.Err == syscall.ENOSPC {
return false, err
}
err = errors.Wrap(err, "kernel does not support overlay fs")
if err2 := cachedFeatureRecord(runhome, feature, false, err.Error()); err2 != nil {
return false, errors.Wrapf(err2, "recording overlay not being supported (%v)", err)
}
return false, err
}
if err = cachedFeatureRecord(runhome, feature, supportsDType, ""); err != nil {
return false, errors.Wrap(err, "recording overlay support status")
}
}
return supportsDType, nil
}
func (d *Driver) getSupportsVolatile() (bool, error) {
if d.supportsVolatile != nil {
return *d.supportsVolatile, nil
}
supportsVolatile, err := checkSupportVolatile(d.home, d.runhome)
if err != nil {
return false, err
}
d.supportsVolatile = &supportsVolatile
return supportsVolatile, nil
}
// isNetworkFileSystem checks if the specified file system is supported by native overlay
// as backing store when running in a user namespace.
func isNetworkFileSystem(fsMagic graphdriver.FsMagic) bool {
switch fsMagic {
// a bunch of network file systems...
case graphdriver.FsMagicNfsFs, graphdriver.FsMagicSmbFs, graphdriver.FsMagicAcfs,
graphdriver.FsMagicAfs, graphdriver.FsMagicCephFs, graphdriver.FsMagicCIFS,
graphdriver.FsMagicFHGFSFs, graphdriver.FsMagicGPFS, graphdriver.FsMagicIBRIX,
graphdriver.FsMagicKAFS, graphdriver.FsMagicLUSTRE, graphdriver.FsMagicNCP,
graphdriver.FsMagicNFSD, graphdriver.FsMagicOCFS2, graphdriver.FsMagicPANFS,
graphdriver.FsMagicPRLFS, graphdriver.FsMagicSMB2, graphdriver.FsMagicSNFS,
graphdriver.FsMagicVBOXSF, graphdriver.FsMagicVXFS:
return true
}
return false
}
// Init returns the a native diff driver for overlay filesystem.
// If overlay filesystem is not supported on the host, a wrapped graphdriver.ErrNotSupported is returned as error.
// If an overlay filesystem is not supported over an existing filesystem then a wrapped graphdriver.ErrIncompatibleFS is returned.
func Init(home string, options graphdriver.Options) (graphdriver.Driver, error) {
opts, err := parseOptions(options.DriverOptions)
if err != nil {
return nil, err
}
fsMagic, err := graphdriver.GetFSMagic(home)
if err != nil {
return nil, err
}
if fsName, ok := graphdriver.FsNames[fsMagic]; ok {
backingFs = fsName
}
runhome := filepath.Join(options.RunRoot, filepath.Base(home))
rootUID, rootGID, err := idtools.GetRootUIDGID(options.UIDMaps, options.GIDMaps)
if err != nil {
return nil, err
}
// Create the driver home dir
if err := idtools.MkdirAllAs(path.Join(home, linkDir), 0700, rootUID, rootGID); err != nil {
return nil, err
}
if err := idtools.MkdirAllAs(runhome, 0700, rootUID, rootGID); err != nil {
return nil, err
}
if opts.mountProgram == "" {
if supported, err := SupportsNativeOverlay(home, runhome); err != nil {
return nil, err
} else if !supported {
if path, err := exec.LookPath("fuse-overlayfs"); err == nil {
opts.mountProgram = path
}
}
}
if opts.mountProgram != "" {
if unshare.IsRootless() && isNetworkFileSystem(fsMagic) && opts.forceMask == nil {
m := os.FileMode(0700)
opts.forceMask = &m
logrus.Warnf("Network file system detected as backing store. Enforcing overlay option `force_mask=\"%o\"`. Add it to storage.conf to silence this warning", m)
}
if err := ioutil.WriteFile(getMountProgramFlagFile(home), []byte("true"), 0600); err != nil {
return nil, err
}
} else {
if opts.forceMask != nil {
return nil, errors.New("'force_mask' is supported only with 'mount_program'")
}
// check if they are running over btrfs, aufs, zfs, overlay, or ecryptfs
switch fsMagic {
case graphdriver.FsMagicAufs, graphdriver.FsMagicZfs, graphdriver.FsMagicOverlay, graphdriver.FsMagicEcryptfs:
return nil, errors.Wrapf(graphdriver.ErrIncompatibleFS, "'overlay' is not supported over %s, a mount_program is required", backingFs)
}
if unshare.IsRootless() && isNetworkFileSystem(fsMagic) {
return nil, errors.Wrapf(graphdriver.ErrIncompatibleFS, "A network file system with user namespaces is not supported. Please use a mount_program")
}
}
var usingMetacopy bool
var supportsDType bool
var supportsVolatile *bool
if opts.mountProgram != "" {
supportsDType = true
t := true
supportsVolatile = &t
} else {
supportsDType, err = checkAndRecordOverlaySupport(fsMagic, home, runhome)
if err != nil {
return nil, err
}
feature := fmt.Sprintf("metacopy(%s)", opts.mountOptions)
metacopyCacheResult, _, err := cachedFeatureCheck(runhome, feature)
if err == nil {
if metacopyCacheResult {
logrus.Debugf("Cached value indicated that metacopy is being used")
} else {
logrus.Debugf("Cached value indicated that metacopy is not being used")
}
usingMetacopy = metacopyCacheResult
} else {
usingMetacopy, err = doesMetacopy(home, opts.mountOptions)
if err == nil {
if usingMetacopy {
logrus.Debugf("overlay: test mount indicated that metacopy is being used")
} else {
logrus.Debugf("overlay: test mount indicated that metacopy is not being used")
}
if err = cachedFeatureRecord(runhome, feature, usingMetacopy, ""); err != nil {
return nil, errors.Wrap(err, "recording metacopy-being-used status")
}
} else {
logrus.Infof("overlay: test mount did not indicate whether or not metacopy is being used: %v", err)
return nil, err
}
}
}
if !opts.skipMountHome {
if err := mount.MakePrivate(home); err != nil {
return nil, err
}
}
fileSystemType := graphdriver.FsMagicOverlay
if opts.mountProgram != "" {
fileSystemType = graphdriver.FsMagicFUSE
}
d := &Driver{
name: "overlay",
home: home,
runhome: runhome,
uidMaps: options.UIDMaps,
gidMaps: options.GIDMaps,
ctr: graphdriver.NewRefCounter(graphdriver.NewFsChecker(fileSystemType)),
supportsDType: supportsDType,
usingMetacopy: usingMetacopy,
supportsVolatile: supportsVolatile,
locker: locker.New(),
options: *opts,
}
d.naiveDiff = graphdriver.NewNaiveDiffDriver(d, graphdriver.NewNaiveLayerIDMapUpdater(d))
if backingFs == "xfs" {
// Try to enable project quota support over xfs.
if d.quotaCtl, err = quota.NewControl(home); err == nil {
projectQuotaSupported = true
} else if opts.quota.Size > 0 || opts.quota.Inodes > 0 {
return nil, fmt.Errorf("Storage options overlay.size and overlay.inodes not supported. Filesystem does not support Project Quota: %v", err)
}
} else if opts.quota.Size > 0 || opts.quota.Inodes > 0 {
// if xfs is not the backing fs then error out if the storage-opt overlay.size is used.
return nil, fmt.Errorf("Storage option overlay.size and overlay.inodes only supported for backingFS XFS. Found %v", backingFs)
}
logrus.Debugf("backingFs=%s, projectQuotaSupported=%v, useNativeDiff=%v, usingMetacopy=%v", backingFs, projectQuotaSupported, !d.useNaiveDiff(), d.usingMetacopy)
return d, nil
}
func parseOptions(options []string) (*overlayOptions, error) {
o := &overlayOptions{}
for _, option := range options {
key, val, err := parsers.ParseKeyValueOpt(option)
if err != nil {
return nil, err
}
trimkey := strings.ToLower(key)
trimkey = strings.TrimPrefix(trimkey, "overlay.")
trimkey = strings.TrimPrefix(trimkey, "overlay2.")
trimkey = strings.TrimPrefix(trimkey, ".")
switch trimkey {
case "override_kernel_check":
logrus.Debugf("overlay: override_kernel_check option was specified, but is no longer necessary")
case "mountopt":
o.mountOptions = val
case "size":
logrus.Debugf("overlay: size=%s", val)
size, err := units.RAMInBytes(val)
if err != nil {
return nil, err
}
o.quota.Size = uint64(size)
case "inodes":
logrus.Debugf("overlay: inodes=%s", val)
inodes, err := strconv.ParseUint(val, 10, 64)
if err != nil {
return nil, err
}
o.quota.Inodes = uint64(inodes)
case "imagestore", "additionalimagestore":
logrus.Debugf("overlay: imagestore=%s", val)
// Additional read only image stores to use for lower paths
if val == "" {
continue
}
for _, store := range strings.Split(val, ",") {
store = filepath.Clean(store)
if !filepath.IsAbs(store) {
return nil, fmt.Errorf("overlay: image path %q is not absolute. Can not be relative", store)
}
st, err := os.Stat(store)
if err != nil {
return nil, fmt.Errorf("overlay: can't stat imageStore dir %s: %v", store, err)
}
if !st.IsDir() {
return nil, fmt.Errorf("overlay: image path %q must be a directory", store)
}
o.imageStores = append(o.imageStores, store)
}
case "additionallayerstore":
logrus.Debugf("overlay: additionallayerstore=%s", val)
// Additional read only layer stores to use for lower paths
if val == "" {
continue
}
for _, lstore := range strings.Split(val, ",") {
elems := strings.Split(lstore, ":")
lstore = filepath.Clean(elems[0])
if !filepath.IsAbs(lstore) {
return nil, fmt.Errorf("overlay: additionallayerstore path %q is not absolute. Can not be relative", lstore)
}
st, err := os.Stat(lstore)
if err != nil {
return nil, errors.Wrap(err, "overlay: can't stat additionallayerstore dir")
}
if !st.IsDir() {
return nil, fmt.Errorf("overlay: additionallayerstore path %q must be a directory", lstore)
}
var withReference bool
for _, e := range elems[1:] {
switch e {
case "ref":
if withReference {
return nil, fmt.Errorf("overlay: additionallayerstore config of %q contains %q option twice", lstore, e)
}
withReference = true
default:
return nil, fmt.Errorf("overlay: additionallayerstore config %q contains unknown option %q", lstore, e)
}
}
o.layerStores = append(o.layerStores, additionalLayerStore{
path: lstore,
withReference: withReference,
})
}
case "mount_program":
logrus.Debugf("overlay: mount_program=%s", val)
if val != "" {
_, err := os.Stat(val)
if err != nil {
return nil, errors.Wrapf(err, "overlay: can't stat program %q", val)
}
}
o.mountProgram = val
case "skip_mount_home":
logrus.Debugf("overlay: skip_mount_home=%s", val)
o.skipMountHome, err = strconv.ParseBool(val)
case "ignore_chown_errors":
logrus.Debugf("overlay: ignore_chown_errors=%s", val)
o.ignoreChownErrors, err = strconv.ParseBool(val)
if err != nil {
return nil, err
}
case "force_mask":
logrus.Debugf("overlay: force_mask=%s", val)
var mask int64
switch val {
case "shared":
mask = 0755
case "private":
mask = 0700
default:
mask, err = strconv.ParseInt(val, 8, 32)
if err != nil {
return nil, err
}
}
m := os.FileMode(mask)
o.forceMask = &m
default:
return nil, fmt.Errorf("overlay: Unknown option %s", key)
}
}
return o, nil
}
func cachedFeatureSet(feature string, set bool) string {
if set {
return fmt.Sprintf("%s-true", feature)
}
return fmt.Sprintf("%s-false", feature)
}
func cachedFeatureCheck(runhome, feature string) (supported bool, text string, err error) {
content, err := ioutil.ReadFile(filepath.Join(runhome, cachedFeatureSet(feature, true)))
if err == nil {
return true, string(content), nil
}
content, err = ioutil.ReadFile(filepath.Join(runhome, cachedFeatureSet(feature, false)))
if err == nil {
return false, string(content), nil
}
return false, "", err
}
func cachedFeatureRecord(runhome, feature string, supported bool, text string) (err error) {
f, err := os.Create(filepath.Join(runhome, cachedFeatureSet(feature, supported)))
if f != nil {
if text != "" {
fmt.Fprintf(f, "%s", text)
}
f.Close()
}
return err
}
func SupportsNativeOverlay(home, runhome string) (bool, error) {
if os.Geteuid() != 0 || home == "" || runhome == "" {
return false, nil
}
var contents string
flagContent, err := ioutil.ReadFile(getMountProgramFlagFile(home))
if err == nil {
contents = strings.TrimSpace(string(flagContent))
}
switch contents {
case "true":
logrus.Debugf("overlay: storage already configured with a mount-program")
return false, nil
default:
needsMountProgram, err := scanForMountProgramIndicators(home)
if err != nil && !os.IsNotExist(err) {
return false, err
}
if err := ioutil.WriteFile(getMountProgramFlagFile(home), []byte(fmt.Sprintf("%t", needsMountProgram)), 0600); err != nil && !os.IsNotExist(err) {
return false, err
}
if needsMountProgram {
return false, nil
}
// fall through to check if we find ourselves needing to use a
// mount program now
case "false":
}
for _, dir := range []string{home, runhome} {
if _, err := os.Stat(dir); err != nil {
_ = idtools.MkdirAllAs(dir, 0700, 0, 0)
}
}
fsMagic, err := graphdriver.GetFSMagic(home)
if err != nil {
return false, err
}
supportsDType, _ := checkAndRecordOverlaySupport(fsMagic, home, runhome)
return supportsDType, nil
}
func supportsOverlay(home string, homeMagic graphdriver.FsMagic, rootUID, rootGID int) (supportsDType bool, err error) {
// We can try to modprobe overlay first
exec.Command("modprobe", "overlay").Run()
logLevel := logrus.ErrorLevel
if unshare.IsRootless() {
logLevel = logrus.DebugLevel
}
layerDir, err := ioutil.TempDir(home, "compat")
if err != nil {
patherr, ok := err.(*os.PathError)
if ok && patherr.Err == syscall.ENOSPC {
return false, err
}
}
if err == nil {
// Check if reading the directory's contents populates the d_type field, which is required
// for proper operation of the overlay filesystem.
supportsDType, err = fsutils.SupportsDType(layerDir)
if err != nil {
return false, err
}
if !supportsDType {
return false, overlayutils.ErrDTypeNotSupported("overlay", backingFs)
}
// Try a test mount in the specific location we're looking at using.
mergedDir := filepath.Join(layerDir, "merged")
lower1Dir := filepath.Join(layerDir, "lower1")
lower2Dir := filepath.Join(layerDir, "lower2")
upperDir := filepath.Join(layerDir, "upper")
workDir := filepath.Join(layerDir, "work")
defer func() {
// Permitted to fail, since the various subdirectories
// can be empty or not even there, and the home might
// legitimately be not empty
_ = unix.Unmount(mergedDir, unix.MNT_DETACH)
_ = os.RemoveAll(layerDir)
_ = os.Remove(home)
}()
_ = idtools.MkdirAs(mergedDir, 0700, rootUID, rootGID)
_ = idtools.MkdirAs(lower1Dir, 0700, rootUID, rootGID)
_ = idtools.MkdirAs(lower2Dir, 0700, rootUID, rootGID)
_ = idtools.MkdirAs(upperDir, 0700, rootUID, rootGID)
_ = idtools.MkdirAs(workDir, 0700, rootUID, rootGID)
flags := fmt.Sprintf("lowerdir=%s:%s,upperdir=%s,workdir=%s", lower1Dir, lower2Dir, upperDir, workDir)
if selinux.GetEnabled() &&
selinux.SecurityCheckContext(selinuxLabelTest) == nil {
// Linux 5.11 introduced unprivileged overlay mounts but it has an issue
// when used together with selinux labels.
// Check that overlay supports selinux labels as well.
flags = label.FormatMountLabel(flags, selinuxLabelTest)
}
if unshare.IsRootless() {
flags = fmt.Sprintf("%s,userxattr", flags)
}
if err := syscall.Mknod(filepath.Join(upperDir, "whiteout"), syscall.S_IFCHR|0600, int(unix.Mkdev(0, 0))); err != nil {
logrus.Debugf("Unable to create kernel-style whiteout: %v", err)
return supportsDType, errors.Wrapf(err, "unable to create kernel-style whiteout")
}
if len(flags) < unix.Getpagesize() {
err := unix.Mount("overlay", mergedDir, "overlay", 0, flags)
if err == nil {
logrus.Debugf("overlay: test mount with multiple lowers succeeded")
return supportsDType, nil
}
logrus.Debugf("overlay: test mount with multiple lowers failed %v", err)
}
flags = fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", lower1Dir, upperDir, workDir)
if selinux.GetEnabled() {
flags = label.FormatMountLabel(flags, selinuxLabelTest)
}
if len(flags) < unix.Getpagesize() {
err := unix.Mount("overlay", mergedDir, "overlay", 0, flags)
if err == nil {
logrus.StandardLogger().Logf(logLevel, "overlay: test mount with multiple lowers failed, but succeeded with a single lower")
return supportsDType, errors.Wrap(graphdriver.ErrNotSupported, "kernel too old to provide multiple lowers feature for overlay")
}
logrus.Debugf("overlay: test mount with a single lower failed %v", err)
}
logrus.StandardLogger().Logf(logLevel, "'overlay' is not supported over %s at %q", backingFs, home)
return supportsDType, errors.Wrapf(graphdriver.ErrIncompatibleFS, "'overlay' is not supported over %s at %q", backingFs, home)
}
logrus.StandardLogger().Logf(logLevel, "'overlay' not found as a supported filesystem on this host. Please ensure kernel is new enough and has overlay support loaded.")
return supportsDType, errors.Wrap(graphdriver.ErrNotSupported, "'overlay' not found as a supported filesystem on this host. Please ensure kernel is new enough and has overlay support loaded.")
}
func (d *Driver) useNaiveDiff() bool {
useNaiveDiffLock.Do(func() {
if d.options.mountProgram != "" {
useNaiveDiffOnly = true
return
}
feature := fmt.Sprintf("native-diff(%s)", d.options.mountOptions)
nativeDiffCacheResult, nativeDiffCacheText, err := cachedFeatureCheck(d.runhome, feature)
if err == nil {
if nativeDiffCacheResult {
logrus.Debugf("Cached value indicated that native-diff is usable")
} else {
logrus.Debugf("Cached value indicated that native-diff is not being used")
logrus.Info(nativeDiffCacheText)
}
useNaiveDiffOnly = !nativeDiffCacheResult
return
}
if err := doesSupportNativeDiff(d.home, d.options.mountOptions); err != nil {
nativeDiffCacheText = fmt.Sprintf("Not using native diff for overlay, this may cause degraded performance for building images: %v", err)
logrus.Info(nativeDiffCacheText)
useNaiveDiffOnly = true
}
cachedFeatureRecord(d.runhome, feature, !useNaiveDiffOnly, nativeDiffCacheText)
})
return useNaiveDiffOnly
}
func (d *Driver) String() string {
return d.name
}
// Status returns current driver information in a two dimensional string array.
// Output contains "Backing Filesystem" used in this implementation.
func (d *Driver) Status() [][2]string {
return [][2]string{
{"Backing Filesystem", backingFs},
{"Supports d_type", strconv.FormatBool(d.supportsDType)},
{"Native Overlay Diff", strconv.FormatBool(!d.useNaiveDiff())},
{"Using metacopy", strconv.FormatBool(d.usingMetacopy)},
}
}
// Metadata returns meta data about the overlay driver such as
// LowerDir, UpperDir, WorkDir and MergeDir used to store data.
func (d *Driver) Metadata(id string) (map[string]string, error) {
dir := d.dir(id)
if _, err := os.Stat(dir); err != nil {
return nil, err
}
metadata := map[string]string{
"WorkDir": path.Join(dir, "work"),
"MergedDir": path.Join(dir, "merged"),
"UpperDir": path.Join(dir, "diff"),
}
lowerDirs, err := d.getLowerDirs(id)
if err != nil {
return nil, err
}
if len(lowerDirs) > 0 {
metadata["LowerDir"] = strings.Join(lowerDirs, ":")
}
return metadata, nil
}
// Cleanup any state created by overlay which should be cleaned when daemon
// is being shutdown. For now, we just have to unmount the bind mounted
// we had created.
func (d *Driver) Cleanup() error {
_ = os.RemoveAll(d.getStagingDir())
return mount.Unmount(d.home)
}
// LookupAdditionalLayer looks up additional layer store by the specified
// digest and ref and returns an object representing that layer.
// This API is experimental and can be changed without bumping the major version number.
// TODO: to remove the comment once it's no longer experimental.
func (d *Driver) LookupAdditionalLayer(dgst digest.Digest, ref string) (graphdriver.AdditionalLayer, error) {
l, err := d.getAdditionalLayerPath(dgst, ref)
if err != nil {
return nil, err
}
// Tell the additional layer store that we use this layer.
// This will increase reference counter on the store's side.
// This will be decreased on Release() method.
notifyUseAdditionalLayer(l)
return &additionalLayer{
path: l,
d: d,
}, nil
}
// LookupAdditionalLayerByID looks up additional layer store by the specified
// ID and returns an object representing that layer.
// This API is experimental and can be changed without bumping the major version number.
// TODO: to remove the comment once it's no longer experimental.
func (d *Driver) LookupAdditionalLayerByID(id string) (graphdriver.AdditionalLayer, error) {
l, err := d.getAdditionalLayerPathByID(id)
if err != nil {
return nil, err
}
// Tell the additional layer store that we use this layer.
// This will increase reference counter on the store's side.
// This will be decreased on Release() method.
notifyUseAdditionalLayer(l)
return &additionalLayer{
path: l,
d: d,
}, nil
}
// CreateFromTemplate creates a layer with the same contents and parent as another layer.
func (d *Driver) CreateFromTemplate(id, template string, templateIDMappings *idtools.IDMappings, parent string, parentIDMappings *idtools.IDMappings, opts *graphdriver.CreateOpts, readWrite bool) error {
if readWrite {
return d.CreateReadWrite(id, template, opts)
}
return d.Create(id, template, opts)
}
// CreateReadWrite creates a layer that is writable for use as a container
// file system.
func (d *Driver) CreateReadWrite(id, parent string, opts *graphdriver.CreateOpts) error {
if opts != nil && len(opts.StorageOpt) != 0 && !projectQuotaSupported {
return fmt.Errorf("--storage-opt is supported only for overlay over xfs with 'pquota' mount option")
}
if opts == nil {
opts = &graphdriver.CreateOpts{
StorageOpt: map[string]string{},
}
}
if _, ok := opts.StorageOpt["size"]; !ok {
if opts.StorageOpt == nil {
opts.StorageOpt = map[string]string{}
}
opts.StorageOpt["size"] = strconv.FormatUint(d.options.quota.Size, 10)
}
if _, ok := opts.StorageOpt["inodes"]; !ok {
if opts.StorageOpt == nil {
opts.StorageOpt = map[string]string{}
}
opts.StorageOpt["inodes"] = strconv.FormatUint(d.options.quota.Inodes, 10)
}
return d.create(id, parent, opts, false)
}
// Create is used to create the upper, lower, and merge directories required for overlay fs for a given id.
// The parent filesystem is used to configure these directories for the overlay.
func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr error) {
if opts != nil && len(opts.StorageOpt) != 0 {
if _, ok := opts.StorageOpt["size"]; ok {
return fmt.Errorf("--storage-opt size is only supported for ReadWrite Layers")
}
if _, ok := opts.StorageOpt["inodes"]; ok {
return fmt.Errorf("--storage-opt inodes is only supported for ReadWrite Layers")
}
}
return d.create(id, parent, opts, true)
}
func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, disableQuota bool) (retErr error) {
dir := d.dir(id)
uidMaps := d.uidMaps
gidMaps := d.gidMaps
if opts != nil && opts.IDMappings != nil {
uidMaps = opts.IDMappings.UIDs()
gidMaps = opts.IDMappings.GIDs()
}
rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)
if err != nil {
return err
}
idPair := idtools.IDPair{
UID: rootUID,
GID: rootGID,
}
// Make the link directory if it does not exist
if err := idtools.MkdirAllAndChownNew(path.Join(d.home, linkDir), 0700, idPair); err != nil {
return err
}
if err := idtools.MkdirAllAndChownNew(path.Dir(dir), 0700, idPair); err != nil {
return err
}
if parent != "" {
st, err := system.Stat(d.dir(parent))
if err != nil {
return err
}
rootUID = int(st.UID())
rootGID = int(st.GID())
}
if err := idtools.MkdirAllAndChownNew(dir, 0700, idPair); err != nil {
return err
}
defer func() {
// Clean up on failure
if retErr != nil {
if err2 := os.RemoveAll(dir); err2 != nil {
logrus.Errorf("While recovering from a failure creating a layer, error deleting %#v: %v", dir, err2)
}
}
}()
if d.quotaCtl != nil && !disableQuota {
quota := quota.Quota{}
if opts != nil && len(opts.StorageOpt) > 0 {
driver := &Driver{}
if err := d.parseStorageOpt(opts.StorageOpt, driver); err != nil {
return err
}
if driver.options.quota.Size > 0 {
quota.Size = driver.options.quota.Size
}
if driver.options.quota.Inodes > 0 {
quota.Inodes = driver.options.quota.Inodes
}
}
// Set container disk quota limit
// If it is set to 0, we will track the disk usage, but not enforce a limit
if err := d.quotaCtl.SetQuota(dir, quota); err != nil {
return err
}
}
perms := defaultPerms
if d.options.forceMask != nil {
perms = *d.options.forceMask
}
if parent != "" {
st, err := system.Stat(filepath.Join(d.dir(parent), "diff"))
if err != nil {
return err
}
perms = os.FileMode(st.Mode())
}
if err := idtools.MkdirAs(path.Join(dir, "diff"), perms, rootUID, rootGID); err != nil {
return err
}
lid := generateID(idLength)
if err := os.Symlink(path.Join("..", id, "diff"), path.Join(d.home, linkDir, lid)); err != nil {
return err
}