mirror of https://github.com/k3s-io/k3s
83 lines
2.4 KiB
Go
83 lines
2.4 KiB
Go
package tmpfssymlink
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import (
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"io/ioutil"
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"os"
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"path/filepath"
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"golang.org/x/sys/unix"
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"github.com/pkg/errors"
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"github.com/rootless-containers/rootlesskit/pkg/copyup"
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)
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func NewChildDriver() copyup.ChildDriver {
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return &childDriver{}
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}
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type childDriver struct {
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}
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func (d *childDriver) CopyUp(dirs []string) ([]string, error) {
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// we create bind0 outside of StateDir so as to allow
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// copying up /run with stateDir=/run/user/1001/rootlesskit/default.
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bind0, err := ioutil.TempDir("/tmp", "rootlesskit-b")
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if err != nil {
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return nil, errors.Wrap(err, "creating bind0 directory under /tmp")
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}
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defer os.RemoveAll(bind0)
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var copied []string
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for _, d := range dirs {
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d := filepath.Clean(d)
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if d == "/tmp" {
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// TODO: we can support copy-up /tmp by changing bind0TempDir
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return copied, errors.New("/tmp cannot be copied up")
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}
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if err := unix.Mount(d, bind0, "", uintptr(unix.MS_BIND|unix.MS_REC), ""); err != nil {
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return copied, errors.Wrapf(err, "failed to create bind mount on %s", d)
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}
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if err := unix.Mount("none", d, "tmpfs", 0, ""); err != nil {
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return copied, errors.Wrapf(err, "failed to mount tmpfs on %s", d)
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}
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bind1, err := ioutil.TempDir(d, ".ro")
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if err != nil {
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return copied, errors.Wrapf(err, "creating a directory under %s", d)
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}
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if err := unix.Mount(bind0, bind1, "", uintptr(unix.MS_MOVE), ""); err != nil {
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return copied, errors.Wrapf(err, "failed to move mount point from %s to %s", bind0, bind1)
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}
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files, err := ioutil.ReadDir(bind1)
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if err != nil {
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return copied, errors.Wrapf(err, "reading dir %s", bind1)
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}
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for _, f := range files {
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fFull := filepath.Join(bind1, f.Name())
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var symlinkSrc string
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if f.Mode()&os.ModeSymlink != 0 {
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symlinkSrc, err = os.Readlink(fFull)
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if err != nil {
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return copied, errors.Wrapf(err, "reading dir %s", fFull)
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}
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} else {
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symlinkSrc = filepath.Join(filepath.Base(bind1), f.Name())
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}
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symlinkDst := filepath.Join(d, f.Name())
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// `mount` may create extra `/etc/mtab` after mounting empty tmpfs on /etc
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// https://github.com/rootless-containers/rootlesskit/issues/45
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if err = os.RemoveAll(symlinkDst); err != nil {
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return copied, errors.Wrapf(err, "removing %s", symlinkDst)
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}
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if err := os.Symlink(symlinkSrc, symlinkDst); err != nil {
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return copied, errors.Wrapf(err, "symlinking %s to %s", symlinkSrc, symlinkDst)
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}
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}
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copied = append(copied, d)
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}
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return copied, nil
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}
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