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https://github.com/kemko/nomad.git
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7b27bc344b
* Move task directory destroy logic from alloc_dir to task_dir * Update errors to wrap error cause * Use constants for file permissions * Make multierror handling consistent. * Make helpers for directory creation * Move mount dir unlink to task_dir Unlink method * Make constant for file mode 710 Co-authored-by: Tim Gross <tgross@hashicorp.com> Co-authored-by: Michael Schurter <mschurter@hashicorp.com>
107 lines
2.6 KiB
Go
107 lines
2.6 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: BUSL-1.1
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//go:build linux
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package allocdir
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import (
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"fmt"
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"os"
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"path/filepath"
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"syscall"
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"golang.org/x/sys/unix"
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)
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const (
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// secretDirTmpfsSize is the size of the tmpfs per task in MBs
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secretDirTmpfsSize = 1
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// secretMarker is the filename of the marker created so Nomad doesn't
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// try to mount the secrets tmpfs more than once
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secretMarker = ".nomad-mount"
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)
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// linkDir bind mounts src to dst as Linux doesn't support hardlinking
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// directories.
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func linkDir(src, dst string) error {
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if err := os.MkdirAll(dst, fileMode777); err != nil {
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return err
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}
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return syscall.Mount(src, dst, "", syscall.MS_BIND, "")
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}
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// mountDir bind mounts old to next using the given file mode.
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func mountDir(old, next string, uid, gid int, mode os.FileMode) error {
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if err := os.MkdirAll(next, mode); err != nil {
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return err
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}
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opts := unix.MS_BIND | unix.MS_NOSUID | unix.MS_NOATIME
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if err := unix.Mount(old, next, "", uintptr(opts), ""); err != nil {
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return err
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}
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return os.Chown(next, uid, gid)
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}
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// unlinkDir unmounts a bind mounted directory as Linux doesn't support
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// hardlinking directories. If the dir is already unmounted no error is
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// returned.
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func unlinkDir(dir string) error {
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if err := syscall.Unmount(dir, 0); err != nil {
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if err != syscall.EINVAL {
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return err
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}
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}
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return nil
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}
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// createSecretDir creates the secrets dir folder at the given path using a
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// tmpfs
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func createSecretDir(dir string) error {
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// Only mount the tmpfs if we are root
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if unix.Geteuid() == 0 {
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if err := os.MkdirAll(dir, fileMode777); err != nil {
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return err
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}
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// Check for marker file and skip mounting if it exists
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marker := filepath.Join(dir, secretMarker)
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if _, err := os.Stat(marker); err == nil {
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return nil
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}
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flags := uintptr(syscall.MS_NOEXEC)
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options := fmt.Sprintf("size=%dm", secretDirTmpfsSize)
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if err := syscall.Mount("tmpfs", dir, "tmpfs", flags, options); err != nil {
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return os.NewSyscallError("mount", err)
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}
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// Create the marker file so we don't try to mount more than once
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f, err := os.OpenFile(marker, os.O_RDWR|os.O_CREATE, fileMode666)
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if err != nil {
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// Hard fail since if this fails something is really wrong
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return err
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}
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f.Close()
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return nil
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}
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return os.MkdirAll(dir, fileMode777)
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}
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// createSecretDir removes the secrets dir folder
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func removeSecretDir(dir string) error {
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if unix.Geteuid() == 0 {
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if err := unlinkDir(dir); err != nil {
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// Ignore invalid path errors
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if err != syscall.ENOENT {
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return os.NewSyscallError("unmount", err)
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}
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}
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}
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return os.RemoveAll(dir)
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}
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