func mountToRootfs(m *configs.Mount, rootfs, mountLabel string) error {
var (
dest = m.Destination
)
if !strings.HasPrefix(dest, rootfs) {
dest = filepath.Join(rootfs, dest)
}
switch m.Device {
case "proc", "sysfs":
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
// Selinux kernels do not support labeling of /proc or /sys
return mountPropagate(m, rootfs, "")
case "mqueue":
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
if err := mountPropagate(m, rootfs, mountLabel); err != nil {
// older kernels do not support labeling of /dev/mqueue
if err := mountPropagate(m, rootfs, ""); err != nil {
return err
}
}
return label.SetFileLabel(dest, mountLabel)
case "tmpfs":
stat, err := os.Stat(dest)
if err != nil {
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
}
if err := mountPropagate(m, rootfs, mountLabel); err != nil {
return err
}
if stat != nil {
if err = os.Chmod(dest, stat.Mode()); err != nil {
return err
}
}
return nil
case "devpts":
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
return mountPropagate(m, rootfs, mountLabel)
case "securityfs":
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
return mountPropagate(m, rootfs, mountLabel)
case "bind":
stat, err := os.Stat(m.Source)
if err != nil {
// error out if the source of a bind mount does not exist as we will be
// unable to bind anything to it.
return err
}
// ensure that the destination of the bind mount is resolved of symlinks at mount time because
// any previous mounts can invalidate the next mount's destination.
// this can happen when a user specifies mounts within other mounts to cause breakouts or other
// evil stuff to try to escape the container's rootfs.
if dest, err = symlink.FollowSymlinkInScope(filepath.Join(rootfs, m.Destination), rootfs); err != nil {
return err
}
if err := checkMountDestination(rootfs, dest); err != nil {
return err
}
// update the mount with the correct dest after symlinks are resolved.
m.Destination = dest
if err := createIfNotExists(dest, stat.IsDir()); err != nil {
return err
}
if err := mountPropagate(m, rootfs, mountLabel); err != nil {
return err
}
// bind mount won't change mount options, we need remount to make mount options effective.
// first check that we have non-default options required before attempting a remount
if m.Flags&^(syscall.MS_REC|syscall.MS_REMOUNT|syscall.MS_BIND) != 0 {
// only remount if unique mount options are set
if err := remount(m, rootfs); err != nil {
return err
}
}
if m.Relabel != "" {
if err := label.Validate(m.Relabel); err != nil {
return err
}
shared := label.IsShared(m.Relabel)
if err := label.Relabel(m.Source, mountLabel, shared); err != nil {
return err
}
}
case "cgroup":
binds, err := getCgroupMounts(m)
if err != nil {
return err
}
var merged []string
for _, b := range binds {
ss := filepath.Base(b.Destination)
if strings.Contains(ss, ",") {
merged = append(merged, ss)
}
}
tmpfs := &configs.Mount{
Source: "tmpfs",
Device: "tmpfs",
Destination: m.Destination,
Flags: defaultMountFlags,
Data: "mode=755",
PropagationFlags: m.PropagationFlags,
}
if err := mountToRootfs(tmpfs, rootfs, mountLabel); err != nil {
return err
}
for _, b := range binds {
if err := mountToRootfs(b, rootfs, mountLabel); err != nil {
return err
}
}
// create symlinks for merged cgroups
cwd, err := os.Getwd()
if err != nil {
return err
}
if err := os.Chdir(filepath.Join(rootfs, m.Destination)); err != nil {
return err
}
for _, mc := range merged {
for _, ss := range strings.Split(mc, ",") {
if err := os.Symlink(mc, ss); err != nil {
// if cgroup already exists, then okay(it could have been created before)
if os.IsExist(err) {
continue
}
os.Chdir(cwd)
return err
}
}
}
if err := os.Chdir(cwd); err != nil {
return err
}
if m.Flags&syscall.MS_RDONLY != 0 {
// remount cgroup root as readonly
mcgrouproot := &configs.Mount{
Destination: m.Destination,
Flags: defaultMountFlags | syscall.MS_RDONLY,
}
if err := remount(mcgrouproot, rootfs); err != nil {
return err
}
}
default:
return fmt.Errorf("unknown mount device %q to %q", m.Device, m.Destination)
}
return nil
}
func mountToRootfs(m *configs.Mount, rootfs, mountLabel string) error {
var (
dest = m.Destination
)
if !strings.HasPrefix(dest, rootfs) {
dest = filepath.Join(rootfs, dest)
}
switch m.Device {
case "proc", "sysfs":
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
// Selinux kernels do not support labeling of /proc or /sys
return mountPropagate(m, rootfs, "")
case "mqueue":
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
if err := mountPropagate(m, rootfs, mountLabel); err != nil {
// older kernels do not support labeling of /dev/mqueue
if err := mountPropagate(m, rootfs, ""); err != nil {
return err
}
return label.SetFileLabel(dest, mountLabel)
}
return nil
case "tmpfs":
copyUp := m.Extensions&configs.EXT_COPYUP == configs.EXT_COPYUP
tmpDir := ""
stat, err := os.Stat(dest)
if err != nil {
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
}
if copyUp {
tmpDir, err = ioutil.TempDir("/tmp", "runctmpdir")
if err != nil {
return newSystemErrorWithCause(err, "tmpcopyup: failed to create tmpdir")
}
defer os.RemoveAll(tmpDir)
m.Destination = tmpDir
}
if err := mountPropagate(m, rootfs, mountLabel); err != nil {
return err
}
if copyUp {
if err := fileutils.CopyDirectory(dest, tmpDir); err != nil {
errMsg := fmt.Errorf("tmpcopyup: failed to copy %s to %s: %v", dest, tmpDir, err)
if err1 := syscall.Unmount(tmpDir, syscall.MNT_DETACH); err1 != nil {
return newSystemErrorWithCausef(err1, "tmpcopyup: %v: failed to unmount", errMsg)
}
return errMsg
}
if err := syscall.Mount(tmpDir, dest, "", syscall.MS_MOVE, ""); err != nil {
errMsg := fmt.Errorf("tmpcopyup: failed to move mount %s to %s: %v", tmpDir, dest, err)
if err1 := syscall.Unmount(tmpDir, syscall.MNT_DETACH); err1 != nil {
return newSystemErrorWithCausef(err1, "tmpcopyup: %v: failed to unmount", errMsg)
}
return errMsg
}
}
if stat != nil {
if err = os.Chmod(dest, stat.Mode()); err != nil {
return err
}
}
return nil
case "bind":
stat, err := os.Stat(m.Source)
if err != nil {
// error out if the source of a bind mount does not exist as we will be
// unable to bind anything to it.
return err
}
// ensure that the destination of the bind mount is resolved of symlinks at mount time because
// any previous mounts can invalidate the next mount's destination.
// this can happen when a user specifies mounts within other mounts to cause breakouts or other
// evil stuff to try to escape the container's rootfs.
if dest, err = symlink.FollowSymlinkInScope(filepath.Join(rootfs, m.Destination), rootfs); err != nil {
return err
}
if err := checkMountDestination(rootfs, dest); err != nil {
return err
}
// update the mount with the correct dest after symlinks are resolved.
m.Destination = dest
if err := createIfNotExists(dest, stat.IsDir()); err != nil {
return err
}
if err := mountPropagate(m, rootfs, mountLabel); err != nil {
return err
}
// bind mount won't change mount options, we need remount to make mount options effective.
// first check that we have non-default options required before attempting a remount
if m.Flags&^(syscall.MS_REC|syscall.MS_REMOUNT|syscall.MS_BIND) != 0 {
// only remount if unique mount options are set
if err := remount(m, rootfs); err != nil {
return err
}
}
if m.Relabel != "" {
if err := label.Validate(m.Relabel); err != nil {
return err
}
shared := label.IsShared(m.Relabel)
if err := label.Relabel(m.Source, mountLabel, shared); err != nil {
return err
}
}
case "cgroup":
binds, err := getCgroupMounts(m)
if err != nil {
return err
}
var merged []string
for _, b := range binds {
ss := filepath.Base(b.Destination)
if strings.Contains(ss, ",") {
merged = append(merged, ss)
}
}
tmpfs := &configs.Mount{
Source: "tmpfs",
Device: "tmpfs",
Destination: m.Destination,
Flags: defaultMountFlags,
Data: "mode=755",
PropagationFlags: m.PropagationFlags,
}
if err := mountToRootfs(tmpfs, rootfs, mountLabel); err != nil {
return err
}
for _, b := range binds {
if err := mountToRootfs(b, rootfs, mountLabel); err != nil {
return err
}
}
for _, mc := range merged {
for _, ss := range strings.Split(mc, ",") {
// symlink(2) is very dumb, it will just shove the path into
// the link and doesn't do any checks or relative path
// conversion. Also, don't error out if the cgroup already exists.
if err := os.Symlink(mc, filepath.Join(rootfs, m.Destination, ss)); err != nil && !os.IsExist(err) {
return err
}
}
}
if m.Flags&syscall.MS_RDONLY != 0 {
// remount cgroup root as readonly
mcgrouproot := &configs.Mount{
Source: m.Destination,
Device: "bind",
Destination: m.Destination,
Flags: defaultMountFlags | syscall.MS_RDONLY | syscall.MS_BIND,
}
if err := remount(mcgrouproot, rootfs); err != nil {
return err
}
}
default:
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}
return mountPropagate(m, rootfs, mountLabel)
}
return nil
}