Golang symlink.FollowSymlinkInScope函数代码示例

func readUserFile(c *container.Container, p string) (io.ReadCloser, error) {
	fp, err := symlink.FollowSymlinkInScope(filepath.Join(c.BaseFS, p), c.BaseFS)
	if err != nil {
		return nil, err
	}
	return os.Open(fp)
}

// CopyImagePathContent copies files in destination to the volume.
func (container *Container) CopyImagePathContent(v volume.Volume, destination string) error {
	rootfs, err := symlink.FollowSymlinkInScope(filepath.Join(container.BaseFS, destination), container.BaseFS)
	if err != nil {
		return err
	}

	if _, err = ioutil.ReadDir(rootfs); err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}

	id := stringid.GenerateNonCryptoID()
	path, err := v.Mount(id)
	if err != nil {
		return err
	}

	defer func() {
		if err := v.Unmount(id); err != nil {
			logrus.Warnf("error while unmounting volume %s: %v", v.Name(), err)
		}
	}()
	return copyExistingContents(rootfs, path)
}

func checkoutGit(fragment, root string) (string, error) {
	refAndDir := strings.SplitN(fragment, ":", 2)

	if len(refAndDir[0]) != 0 {
		if output, err := gitWithinDir(root, "checkout", refAndDir[0]); err != nil {
			return "", fmt.Errorf("Error trying to use git: %s (%s)", err, output)
		}
	}

	if len(refAndDir) > 1 && len(refAndDir[1]) != 0 {
		newCtx, err := symlink.FollowSymlinkInScope(filepath.Join(root, refAndDir[1]), root)
		if err != nil {
			return "", fmt.Errorf("Error setting git context, %q not within git root: %s", refAndDir[1], err)
		}

		fi, err := os.Stat(newCtx)
		if err != nil {
			return "", err
		}
		if !fi.IsDir() {
			return "", fmt.Errorf("Error setting git context, not a directory: %s", newCtx)
		}
		root = newCtx
	}

	return root, nil
}

// GetResourcePath evaluates `path` in the scope of the container's basefs, with proper path
// sanitisation. Symlinks are all scoped to the basefs of the container, as
// though the container's basefs was `/`.
//
// The basefs of a container is the host-facing path which is bind-mounted as
// `/` inside the container. This method is essentially used to access a
// particular path inside the container as though you were a process in that
// container.
//
// NOTE: The returned path is *only* safely scoped inside the container's basefs
//       if no component of the returned path changes (such as a component
//       symlinking to a different path) between using this method and using the
//       path. See symlink.FollowSymlinkInScope for more details.
func (container *Container) GetResourcePath(path string) (string, error) {
	// IMPORTANT - These are paths on the OS where the daemon is running, hence
	// any filepath operations must be done in an OS agnostic way.
	cleanPath := filepath.Join(string(os.PathSeparator), path)
	r, e := symlink.FollowSymlinkInScope(filepath.Join(container.basefs, cleanPath), container.basefs)
	return r, e
}

func (m *Mount) initialize() error {
	// No need to initialize anything since it's already been initialized
	if hostPath, exists := m.container.Volumes[m.MountToPath]; exists {
		// If this is a bind-mount/volumes-from, maybe it was passed in at start instead of create
		// We need to make sure bind-mounts/volumes-from passed on start can override existing ones.
		if (!m.volume.IsBindMount && !m.isBind) && m.from == nil {
			return nil
		}
		if m.volume.Path == hostPath {
			return nil
		}

		// Make sure we remove these old volumes we don't actually want now.
		// Ignore any errors here since this is just cleanup, maybe someone volumes-from'd this volume
		if v := m.container.daemon.volumes.Get(hostPath); v != nil {
			v.RemoveContainer(m.container.ID)
			m.container.daemon.volumes.Delete(v.Path)
		}
	}

	// This is the full path to container fs + mntToPath
	containerMntPath, err := symlink.FollowSymlinkInScope(filepath.Join(m.container.basefs, m.MountToPath), m.container.basefs)
	if err != nil {
		return err
	}
	m.container.VolumesRW[m.MountToPath] = m.Writable
	m.container.Volumes[m.MountToPath] = m.volume.Path
	m.volume.AddContainer(m.container.ID)
	if m.Writable && m.copyData {
		// Copy whatever is in the container at the mntToPath to the volume
		copyExistingContents(containerMntPath, m.volume.Path)
	}

	return nil
}

func (c *tarSumContext) normalize(path string) (cleanpath, fullpath string, err error) {
	cleanpath = filepath.Clean(string(os.PathSeparator) + path)[1:]
	fullpath, err = symlink.FollowSymlinkInScope(filepath.Join(c.root, path), c.root)
	if err != nil {
		return "", "", fmt.Errorf("Forbidden path outside the build context: %s (%s)", path, fullpath)
	}
	_, err = os.Lstat(fullpath)
	if err != nil {
		return "", "", convertPathError(err, path)
	}
	return
}

func (m *Mount) bindMount(rootfs, mountLabel string) error {
	var (
		flags = syscall.MS_BIND | syscall.MS_REC
		dest  = filepath.Join(rootfs, m.Destination)
	)

	if !m.Writable {
		flags = flags | syscall.MS_RDONLY
	}

	if m.Slave {
		flags = flags | syscall.MS_SLAVE
	}

	stat, err := os.Stat(m.Source)
	if err != nil {
		return err
	}

	// FIXME: (crosbymichael) This does not belong here and should be done a layer above
	dest, err = symlink.FollowSymlinkInScope(dest, rootfs)
	if err != nil {
		return err
	}

	if err := createIfNotExists(dest, stat.IsDir()); err != nil {
		return fmt.Errorf("creating new bind mount target %s", err)
	}

	if err := syscall.Mount(m.Source, dest, "bind", uintptr(flags), ""); err != nil {
		return fmt.Errorf("mounting %s into %s %s", m.Source, dest, err)
	}

	if !m.Writable {
		if err := syscall.Mount(m.Source, dest, "bind", uintptr(flags|syscall.MS_REMOUNT), ""); err != nil {
			return fmt.Errorf("remounting %s into %s %s", m.Source, dest, err)
		}
	}

	if m.Relabel != "" {
		if err := label.Relabel(m.Source, mountLabel, m.Relabel); err != nil {
			return fmt.Errorf("relabeling %s to %s %s", m.Source, mountLabel, err)
		}
	}

	if m.Private {
		if err := syscall.Mount("", dest, "none", uintptr(syscall.MS_PRIVATE), ""); err != nil {
			return fmt.Errorf("mounting %s private %s", dest, err)
		}
	}

	return nil
}

// GetResourcePath evaluates `path` in the scope of the container's BaseFS, with proper path
// sanitisation. Symlinks are all scoped to the BaseFS of the container, as
// though the container's BaseFS was `/`.
//
// The BaseFS of a container is the host-facing path which is bind-mounted as
// `/` inside the container. This method is essentially used to access a
// particular path inside the container as though you were a process in that
// container.
//
// NOTE: The returned path is *only* safely scoped inside the container's BaseFS
//       if no component of the returned path changes (such as a component
//       symlinking to a different path) between using this method and using the
//       path. See symlink.FollowSymlinkInScope for more details.
func (container *Container) GetResourcePath(path string) (string, error) {
	// IMPORTANT - These are paths on the OS where the daemon is running, hence
	// any filepath operations must be done in an OS agnostic way.

	cleanPath := cleanResourcePath(path)
	r, e := symlink.FollowSymlinkInScope(filepath.Join(container.BaseFS, cleanPath), container.BaseFS)

	// Log this here on the daemon side as there's otherwise no indication apart
	// from the error being propagated all the way back to the client. This makes
	// debugging significantly easier and clearly indicates the error comes from the daemon.
	if e != nil {
		logrus.Errorf("Failed to FollowSymlinkInScope BaseFS %s cleanPath %s path %s %s\n", container.BaseFS, cleanPath, path, e)
	}
	return r, e
}

func (v *Volume) initialize(container *Container) error {
	var err error
	v.VolPath = filepath.Clean(v.VolPath)

	// Do not initialize an existing volume
	if _, exists := container.Volumes[v.VolPath]; exists {
		return nil
	}

	// If it's not a bindmount we need to create the dir on the host
	if !v.isBindMount {
		v.HostPath, err = createVolumeHostPath(container)
		if err != nil {
			return err
		}
	}

	hostPath, err := filepath.EvalSymlinks(v.HostPath)
	if err != nil {
		return err
	}

	// Create the mountpoint
	// This is the path to the volume within the container FS
	// This differs from `hostPath` in that `hostPath` refers to the place where
	// the volume data is actually stored on the host
	fullVolPath, err := symlink.FollowSymlinkInScope(filepath.Join(container.basefs, v.VolPath), container.basefs)
	if err != nil {
		return err
	}

	container.Volumes[v.VolPath] = hostPath
	container.VolumesRW[v.VolPath] = v.isRw()

	volIsDir, err := v.isDir()
	if err != nil {
		return err
	}
	if err := createIfNotExists(fullVolPath, volIsDir); err != nil {
		return err
	}

	// Do not copy or change permissions if we are mounting from the host
	if v.isRw() && !v.isBindMount {
		return copyExistingContents(fullVolPath, hostPath)
	}
	return nil
}

// Reads a Dockerfile from the current context. It assumes that the
// 'filename' is a relative path from the root of the context
func (b *Builder) readDockerfile(origFile string) error {
	filename, err := symlink.FollowSymlinkInScope(filepath.Join(b.contextPath, origFile), b.contextPath)
	if err != nil {
		return fmt.Errorf("The Dockerfile (%s) must be within the build context", origFile)
	}

	fi, err := os.Lstat(filename)
	if os.IsNotExist(err) {
		return fmt.Errorf("Cannot locate specified Dockerfile: %s", origFile)
	}
	if fi.Size() == 0 {
		return ErrDockerfileEmpty
	}

	f, err := os.Open(filename)
	if err != nil {
		return err
	}

	b.dockerfile, err = parser.Parse(f)
	f.Close()

	if err != nil {
		return err
	}

	// After the Dockerfile has been parsed, we need to check the .dockerignore
	// file for either "Dockerfile" or ".dockerignore", and if either are
	// present then erase them from the build context. These files should never
	// have been sent from the client but we did send them to make sure that
	// we had the Dockerfile to actually parse, and then we also need the
	// .dockerignore file to know whether either file should be removed.
	// Note that this assumes the Dockerfile has been read into memory and
	// is now safe to be removed.

	excludes, _ := utils.ReadDockerIgnore(filepath.Join(b.contextPath, ".dockerignore"))
	if rm, _ := fileutils.Matches(".dockerignore", excludes); rm == true {
		os.Remove(filepath.Join(b.contextPath, ".dockerignore"))
		b.context.(tarsum.BuilderContext).Remove(".dockerignore")
	}
	if rm, _ := fileutils.Matches(b.dockerfileName, excludes); rm == true {
		os.Remove(filepath.Join(b.contextPath, b.dockerfileName))
		b.context.(tarsum.BuilderContext).Remove(b.dockerfileName)
	}

	return nil
}

func mountToRootfs(m *specs.Mount, rootfs, mountLabel string) error {
	// TODO: we don't use mountLabel here because it looks like mountLabel is
	// only significant when SELinux is enabled.
	var (
		dest = m.Destination
	)
	if !strings.HasPrefix(dest, rootfs) {
		dest = filepath.Join(rootfs, dest)
	}

	switch m.Type {
	case "proc", "sysfs", "mqueue", "tmpfs", "cgroup", "devpts":
		glog.V(3).Infof("Skip mount point %q of type %s", m.Destination, m.Type)
		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 := mount.Mount(m.Source, dest, m.Type, strings.Join(m.Options, ",")); err != nil {
			return err
		}
	default:
		if err := os.MkdirAll(dest, 0755); err != nil {
			return err
		}
		return mount.Mount(m.Source, dest, m.Type, strings.Join(m.Options, ","))
	}
	return nil
}

func setupBindmounts(rootfs string, mountConfig *MountConfig) error {
	bindMounts := mountConfig.Mounts
	for _, m := range bindMounts.OfType("bind") {
		var (
			flags = syscall.MS_BIND | syscall.MS_REC
			dest  = filepath.Join(rootfs, m.Destination)
		)
		if !m.Writable {
			flags = flags | syscall.MS_RDONLY
		}

		stat, err := os.Stat(m.Source)
		if err != nil {
			return err
		}

		dest, err = symlink.FollowSymlinkInScope(dest, rootfs)
		if err != nil {
			return err
		}

		if err := createIfNotExists(dest, stat.IsDir()); err != nil {
			return fmt.Errorf("Creating new bind-mount target, %s", err)
		}

		if err := syscall.Mount(m.Source, dest, "bind", uintptr(flags), ""); err != nil {
			return fmt.Errorf("mounting %s into %s %s", m.Source, dest, err)
		}
		if !m.Writable {
			if err := syscall.Mount(m.Source, dest, "bind", uintptr(flags|syscall.MS_REMOUNT), ""); err != nil {
				return fmt.Errorf("remounting %s into %s %s", m.Source, dest, err)
			}
		}
		if m.Relabel != "" {
			if err := label.Relabel(m.Source, mountConfig.MountLabel, m.Relabel); err != nil {
				return fmt.Errorf("relabeling %s to %s %s", m.Source, mountConfig.MountLabel, err)
			}
		}
		if m.Private {
			if err := syscall.Mount("", dest, "none", uintptr(syscall.MS_PRIVATE), ""); err != nil {
				return fmt.Errorf("mounting %s private %s", dest, err)
			}
		}
	}
	return nil
}

// getDockerfileRelPath uses the given context directory for a `docker build`
// and returns the absolute path to the context directory, the relative path of
// the dockerfile in that context directory, and a non-nil error on success.
func getDockerfileRelPath(givenContextDir, givenDockerfile string) (absContextDir, relDockerfile string, err error) {
	if absContextDir, err = filepath.Abs(givenContextDir); err != nil {
		return "", "", fmt.Errorf("unable to get absolute context directory: %v", err)
	}

	absDockerfile := givenDockerfile
	if absDockerfile == "" {
		// No -f/--file was specified so use the default relative to the
		// context directory.
		absDockerfile = filepath.Join(absContextDir, api.DefaultDockerfileName)

		// Just to be nice ;-) look for 'dockerfile' too but only
		// use it if we found it, otherwise ignore this check
		if _, err = os.Lstat(absDockerfile); os.IsNotExist(err) {
			altPath := filepath.Join(absContextDir, strings.ToLower(api.DefaultDockerfileName))
			if _, err = os.Lstat(altPath); err == nil {
				absDockerfile = altPath
			}
		}
	}

	// If not already an absolute path, the Dockerfile path should be joined to
	// the base directory.
	if !filepath.IsAbs(absDockerfile) {
		absDockerfile = filepath.Join(absContextDir, absDockerfile)
	}

	// Verify that 'filename' is within the build context
	absDockerfile, err = symlink.FollowSymlinkInScope(absDockerfile, absContextDir)
	if err != nil {
		return "", "", fmt.Errorf("The Dockerfile (%s) must be within the build context (%s)", givenDockerfile, givenContextDir)
	}

	if _, err := os.Lstat(absDockerfile); err != nil {
		if os.IsNotExist(err) {
			return "", "", fmt.Errorf("Cannot locate Dockerfile: absDockerfile: %q", absDockerfile)
		}
		return "", "", fmt.Errorf("unable to stat Dockerfile: %v", err)
	}

	if relDockerfile, err = filepath.Rel(absContextDir, absDockerfile); err != nil {
		return "", "", fmt.Errorf("unable to get relative Dockerfile path: %v", err)
	}

	return absContextDir, relDockerfile, nil
}

// CopyImagePathContent copies files in destination to the volume.
func (container *Container) CopyImagePathContent(v volume.Volume, destination string) error {
	rootfs, err := symlink.FollowSymlinkInScope(filepath.Join(container.BaseFS, destination), container.BaseFS)
	if err != nil {
		return err
	}

	if _, err = ioutil.ReadDir(rootfs); err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}

	path, err := v.Mount()
	if err != nil {
		return err
	}
	defer v.Unmount()
	return copyExistingContents(rootfs, path)
}

func (d *driver) setupMounts(container *configs.Config, c *execdriver.Command) error {
	userMounts := make(map[string]struct{})
	for _, m := range c.Mounts {
		userMounts[m.Destination] = struct{}{}
	}

	// Filter out mounts that are overriden by user supplied mounts
	var defaultMounts []*configs.Mount
	_, mountDev := userMounts["/dev"]
	for _, m := range container.Mounts {
		if _, ok := userMounts[m.Destination]; !ok {
			if mountDev && strings.HasPrefix(m.Destination, "/dev/") {
				continue
			}
			defaultMounts = append(defaultMounts, m)
		}
	}
	container.Mounts = defaultMounts

	for _, m := range c.Mounts {
		dest, err := symlink.FollowSymlinkInScope(filepath.Join(c.Rootfs, m.Destination), c.Rootfs)
		if err != nil {
			return err
		}
		flags := syscall.MS_BIND | syscall.MS_REC
		if !m.Writable {
			flags |= syscall.MS_RDONLY
		}
		if m.Slave {
			flags |= syscall.MS_SLAVE
		}

		container.Mounts = append(container.Mounts, &configs.Mount{
			Source:      m.Source,
			Destination: dest,
			Device:      "bind",
			Flags:       flags,
		})
	}
	return nil
}