Golang system.Mount函数代码示例

func setupBindmounts(rootfs string, bindMounts libcontainer.Mounts) error {
	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
		}
		if err := system.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 := system.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.Private {
			if err := system.Mount("", dest, "none", uintptr(syscall.MS_PRIVATE), ""); err != nil {
				return fmt.Errorf("mounting %s private %s", dest, err)
			}
		}
	}
	return nil
}

// setupNewMountNamespace is used to initialize a new mount namespace for an new
// container in the rootfs that is specified.
//
// There is no need to unmount the new mounts because as soon as the mount namespace
// is no longer in use, the mounts will be removed automatically
func setupNewMountNamespace(rootfs, console string, readonly bool) error {
	// mount as slave so that the new mounts do not propagate to the host
	if err := system.Mount("", "/", "", syscall.MS_SLAVE|syscall.MS_REC, ""); err != nil {
		return fmt.Errorf("mounting / as slave %s", err)
	}
	if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REC, ""); err != nil {
		return fmt.Errorf("mouting %s as bind %s", rootfs, err)
	}
	if readonly {
		if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REMOUNT|syscall.MS_RDONLY|syscall.MS_REC, ""); err != nil {
			return fmt.Errorf("mounting %s as readonly %s", rootfs, err)
		}
	}
	if err := mountSystem(rootfs); err != nil {
		return fmt.Errorf("mount system %s", err)
	}
	if err := copyDevNodes(rootfs); err != nil {
		return fmt.Errorf("copy dev nodes %s", err)
	}
	// In non-privileged mode, this fails. Discard the error.
	setupLoopbackDevices(rootfs)
	if err := setupDev(rootfs); err != nil {
		return err
	}
	if console != "" {
		if err := setupPtmx(rootfs, console); err != nil {
			return err
		}
	}
	if err := system.Chdir(rootfs); err != nil {
		return fmt.Errorf("chdir into %s %s", rootfs, err)
	}

	pivotDir, err := ioutil.TempDir(rootfs, ".pivot_root")
	if err != nil {
		return fmt.Errorf("can't create pivot_root dir %s", pivotDir, err)
	}
	if err := system.Pivotroot(rootfs, pivotDir); err != nil {
		return fmt.Errorf("pivot_root %s", err)
	}
	if err := system.Chdir("/"); err != nil {
		return fmt.Errorf("chdir / %s", err)
	}

	// path to pivot dir now changed, update
	pivotDir = filepath.Join("/", filepath.Base(pivotDir))

	if err := system.Unmount(pivotDir, syscall.MNT_DETACH); err != nil {
		return fmt.Errorf("unmount pivot_root dir %s", err)
	}

	if err := os.Remove(pivotDir); err != nil {
		return fmt.Errorf("remove pivot_root dir %s", err)
	}

	system.Umask(0022)

	return nil
}

// InitializeMountNamespace setups up the devices, mount points, and filesystems for use inside a
// new mount namepsace
func InitializeMountNamespace(rootfs, console string, container *libcontainer.Container) error {
	var (
		err  error
		flag = syscall.MS_PRIVATE
	)
	if container.NoPivotRoot {
		flag = syscall.MS_SLAVE
	}
	if err := system.Mount("", "/", "", uintptr(flag|syscall.MS_REC), ""); err != nil {
		return fmt.Errorf("mounting / with flags %X %s", (flag | syscall.MS_REC), err)
	}
	if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REC, ""); err != nil {
		return fmt.Errorf("mouting %s as bind %s", rootfs, err)
	}
	if err := mountSystem(rootfs, container); err != nil {
		return fmt.Errorf("mount system %s", err)
	}
	if err := setupBindmounts(rootfs, container.Mounts); err != nil {
		return fmt.Errorf("bind mounts %s", err)
	}
	if err := nodes.CopyN(rootfs, nodes.DefaultNodes, true); err != nil {
		return fmt.Errorf("copy dev nodes %s", err)
	}
	if err := nodes.CopyN(rootfs, nodes.AdditionalNodes, false); err != nil {
		return fmt.Errorf("copy additional dev nodes %s", err)
	}
	if err := SetupPtmx(rootfs, console, container.Context["mount_label"]); err != nil {
		return err
	}
	if err := setupDevSymlinks(rootfs); err != nil {
		return fmt.Errorf("dev symlinks %s", err)
	}
	if err := system.Chdir(rootfs); err != nil {
		return fmt.Errorf("chdir into %s %s", rootfs, err)
	}

	if container.NoPivotRoot {
		err = MsMoveRoot(rootfs)
	} else {
		err = PivotRoot(rootfs)
	}
	if err != nil {
		return err
	}

	if container.ReadonlyFs {
		if err := SetReadonly(); err != nil {
			return fmt.Errorf("set readonly %s", err)
		}
	}

	system.Umask(0022)

	return nil
}

func mountReadonly(path string) error {
	if err := system.Mount("", path, "", syscall.MS_REMOUNT|syscall.MS_RDONLY, ""); err != nil {
		if err == syscall.EINVAL {
			// Probably not a mountpoint, use bind-mount
			if err := system.Mount(path, path, "", syscall.MS_BIND, ""); err != nil {
				return err
			}
			if err := system.Mount(path, path, "", syscall.MS_BIND|syscall.MS_REMOUNT|syscall.MS_RDONLY|syscall.MS_REC|defaultMountFlags, ""); err != nil {
				return err
			}
		} else {
			return err
		}
	}
	return nil
}

// InitializeMountNamespace setups up the devices, mount points, and filesystems for use inside a
// new mount namepsace
func InitializeMountNamespace(rootfs, console string, container *libcontainer.Container) error {
	var (
		err  error
		flag = syscall.MS_PRIVATE
	)
	if container.NoPivotRoot {
		flag = syscall.MS_SLAVE
	}
	if err := system.Mount("", "/", "", uintptr(flag|syscall.MS_REC), ""); err != nil {
		return fmt.Errorf("mounting / as slave %s", err)
	}
	if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REC, ""); err != nil {
		return fmt.Errorf("mouting %s as bind %s", rootfs, err)
	}
	if err := mountSystem(rootfs, container); err != nil {
		return fmt.Errorf("mount system %s", err)
	}
	if err := setupBindmounts(rootfs, container.Mounts); err != nil {
		return fmt.Errorf("bind mounts %s", err)
	}
	if err := nodes.CopyN(rootfs, nodes.DefaultNodes); err != nil {
		return fmt.Errorf("copy dev nodes %s", err)
	}
	if restrictionPath := container.Context["restriction_path"]; restrictionPath != "" {
		if err := restrict.Restrict(rootfs, restrictionPath); err != nil {
			return fmt.Errorf("restrict %s", err)
		}
	}
	if err := SetupPtmx(rootfs, console, container.Context["mount_label"]); err != nil {
		return err
	}
	if err := system.Chdir(rootfs); err != nil {
		return fmt.Errorf("chdir into %s %s", rootfs, err)
	}

	if container.NoPivotRoot {
		err = MsMoveRoot(rootfs)
	} else {
		err = PivotRoot(rootfs)
	}
	if err != nil {
		return err
	}

	if container.ReadonlyFs {
		if err := SetReadonly(); err != nil {
			return fmt.Errorf("set readonly %s", err)
		}
	}

	system.Umask(0022)

	return nil
}

// This has to be called while the container still has CAP_SYS_ADMIN (to be able to perform mounts).
// However, afterwards, CAP_SYS_ADMIN should be dropped (otherwise the user will be able to revert those changes).
func Restrict(mounts ...string) error {
	// remount proc and sys as readonly
	for _, dest := range mounts {
		if err := system.Mount("", dest, "", syscall.MS_REMOUNT|syscall.MS_RDONLY, ""); err != nil {
			return fmt.Errorf("unable to remount %s readonly: %s", dest, err)
		}
	}
	if err := system.Mount("/dev/null", "/proc/kcore", "", syscall.MS_BIND, ""); err != nil {
		return fmt.Errorf("unable to bind-mount /dev/null over /proc/kcore")
	}
	return nil
}

// InitializeMountNamespace sets up the devices, mount points, and filesystems for use inside a
// new mount namespace.
func InitializeMountNamespace(rootfs, console string, mountConfig *MountConfig) error {
	var (
		err  error
		flag = syscall.MS_PRIVATE
	)
	if mountConfig.NoPivotRoot {
		flag = syscall.MS_SLAVE
	}
	if err := system.Mount("", "/", "", uintptr(flag|syscall.MS_REC), ""); err != nil {
		return fmt.Errorf("mounting / with flags %X %s", (flag | syscall.MS_REC), err)
	}
	if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REC, ""); err != nil {
		return fmt.Errorf("mouting %s as bind %s", rootfs, err)
	}
	if err := mountSystem(rootfs, mountConfig); err != nil {
		return fmt.Errorf("mount system %s", err)
	}
	if err := setupBindmounts(rootfs, mountConfig); err != nil {
		return fmt.Errorf("bind mounts %s", err)
	}
	if err := nodes.CreateDeviceNodes(rootfs, mountConfig.DeviceNodes); err != nil {
		return fmt.Errorf("create device nodes %s", err)
	}
	if err := SetupPtmx(rootfs, console, mountConfig.MountLabel); err != nil {
		return err
	}
	if err := setupDevSymlinks(rootfs); err != nil {
		return fmt.Errorf("dev symlinks %s", err)
	}
	if err := system.Chdir(rootfs); err != nil {
		return fmt.Errorf("chdir into %s %s", rootfs, err)
	}

	if mountConfig.NoPivotRoot {
		err = MsMoveRoot(rootfs)
	} else {
		err = PivotRoot(rootfs)
	}
	if err != nil {
		return err
	}

	if mountConfig.ReadonlyFs {
		if err := SetReadonly(); err != nil {
			return fmt.Errorf("set readonly %s", err)
		}
	}

	system.Umask(0022)

	return nil
}

// setupNewMountNamespace is used to initialize a new mount namespace for an new
// container in the rootfs that is specified.
//
// There is no need to unmount the new mounts because as soon as the mount namespace
// is no longer in use, the mounts will be removed automatically
func setupNewMountNamespace(rootfs, console string, readonly, noPivotRoot bool) error {
	flag := syscall.MS_PRIVATE
	if noPivotRoot {
		flag = syscall.MS_SLAVE
	}
	if err := system.Mount("", "/", "", uintptr(flag|syscall.MS_REC), ""); err != nil {
		return fmt.Errorf("mounting / as slave %s", err)
	}
	if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REC, ""); err != nil {
		return fmt.Errorf("mouting %s as bind %s", rootfs, err)
	}
	if readonly {
		if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REMOUNT|syscall.MS_RDONLY|syscall.MS_REC, ""); err != nil {
			return fmt.Errorf("mounting %s as readonly %s", rootfs, err)
		}
	}
	if err := mountSystem(rootfs); err != nil {
		return fmt.Errorf("mount system %s", err)
	}
	if err := copyDevNodes(rootfs); err != nil {
		return fmt.Errorf("copy dev nodes %s", err)
	}
	// In non-privileged mode, this fails. Discard the error.
	setupLoopbackDevices(rootfs)
	if err := setupDev(rootfs); err != nil {
		return err
	}
	if console != "" {
		if err := setupPtmx(rootfs, console); err != nil {
			return err
		}
	}
	if err := system.Chdir(rootfs); err != nil {
		return fmt.Errorf("chdir into %s %s", rootfs, err)
	}

	if noPivotRoot {
		if err := rootMsMove(rootfs); err != nil {
			return err
		}
	} else {
		if err := rootPivot(rootfs); err != nil {
			return err
		}
	}

	system.Umask(0022)

	return nil
}

// setupConsole ensures that the container has a proper /dev/console setup
func setupConsole(rootfs, console string) error {
	oldMask := system.Umask(0000)
	defer system.Umask(oldMask)

	stat, err := os.Stat(console)
	if err != nil {
		return fmt.Errorf("stat console %s %s", console, err)
	}
	var (
		st   = stat.Sys().(*syscall.Stat_t)
		dest = filepath.Join(rootfs, "dev/console")
	)
	if err := os.Remove(dest); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("remove %s %s", dest, err)
	}
	if err := os.Chmod(console, 0600); err != nil {
		return err
	}
	if err := os.Chown(console, 0, 0); err != nil {
		return err
	}
	if err := system.Mknod(dest, (st.Mode&^07777)|0600, int(st.Rdev)); err != nil {
		return fmt.Errorf("mknod %s %s", dest, err)
	}
	if err := system.Mount(console, dest, "bind", syscall.MS_BIND, ""); err != nil {
		return fmt.Errorf("bind %s to %s %s", console, dest, err)
	}
	return nil
}

// Setup initializes the proper /dev/console inside the rootfs path
func Setup(rootfs, consolePath, mountLabel string) error {
	oldMask := system.Umask(0000)
	defer system.Umask(oldMask)

	if err := os.Chmod(consolePath, 0600); err != nil {
		return err
	}
	if err := os.Chown(consolePath, 0, 0); err != nil {
		return err
	}
	if err := label.SetFileLabel(consolePath, mountLabel); err != nil {
		return fmt.Errorf("set file label %s %s", consolePath, err)
	}

	dest := filepath.Join(rootfs, "dev/console")

	f, err := os.Create(dest)
	if err != nil && !os.IsExist(err) {
		return fmt.Errorf("create %s %s", dest, err)
	}
	if f != nil {
		f.Close()
	}

	if err := system.Mount(consolePath, dest, "bind", syscall.MS_BIND, ""); err != nil {
		return fmt.Errorf("bind %s to %s %s", consolePath, dest, err)
	}
	return nil
}

// setupNewMountNamespace is used to initialize a new mount namespace for an new
// container in the rootfs that is specified.
//
// There is no need to unmount the new mounts because as soon as the mount namespace
// is no longer in use, the mounts will be removed automatically
func setupNewMountNamespace(rootfs, console string, readonly bool) error {
	// mount as slave so that the new mounts do not propagate to the host
	if err := system.Mount("", "/", "", syscall.MS_SLAVE|syscall.MS_REC, ""); err != nil {
		return fmt.Errorf("mounting / as slave %s", err)
	}
	if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REC, ""); err != nil {
		return fmt.Errorf("mouting %s as bind %s", rootfs, err)
	}
	if readonly {
		if err := system.Mount(rootfs, rootfs, "bind", syscall.MS_BIND|syscall.MS_REMOUNT|syscall.MS_RDONLY|syscall.MS_REC, ""); err != nil {
			return fmt.Errorf("mounting %s as readonly %s", rootfs, err)
		}
	}
	if err := mountSystem(rootfs); err != nil {
		return fmt.Errorf("mount system %s", err)
	}
	if err := copyDevNodes(rootfs); err != nil {
		return fmt.Errorf("copy dev nodes %s", err)
	}
	// In non-privileged mode, this fails. Discard the error.
	setupLoopbackDevices(rootfs)
	if err := setupDev(rootfs); err != nil {
		return err
	}
	if console != "" {
		if err := setupPtmx(rootfs, console); err != nil {
			return err
		}
	}
	if err := system.Chdir(rootfs); err != nil {
		return fmt.Errorf("chdir into %s %s", rootfs, err)
	}
	if err := system.Mount(rootfs, "/", "", syscall.MS_MOVE, ""); err != nil {
		return fmt.Errorf("mount move %s into / %s", rootfs, err)
	}
	if err := system.Chroot("."); err != nil {
		return fmt.Errorf("chroot . %s", err)
	}
	if err := system.Chdir("/"); err != nil {
		return fmt.Errorf("chdir / %s", err)
	}

	system.Umask(0022)

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

func MsMoveRoot(rootfs string) error {
	if err := system.Mount(rootfs, "/", "", syscall.MS_MOVE, ""); err != nil {
		return fmt.Errorf("mount move %s into / %s", rootfs, err)
	}
	if err := system.Chroot("."); err != nil {
		return fmt.Errorf("chroot . %s", err)
	}
	return system.Chdir("/")
}

// remountProc is used to detach and remount the proc filesystem
// commonly needed with running a new process inside an existing container
func remountProc() error {
	if err := system.Unmount("/proc", syscall.MNT_DETACH); err != nil {
		return err
	}
	if err := system.Mount("proc", "/proc", "proc", uintptr(defaultMountFlags), ""); err != nil {
		return err
	}
	return nil
}

// mountSystem sets up linux specific system mounts like sys, proc, shm, and devpts
// inside the mount namespace
func mountSystem(rootfs string, mountConfig *MountConfig) error {
	for _, m := range newSystemMounts(rootfs, mountConfig.MountLabel, mountConfig.Mounts) {
		if err := os.MkdirAll(m.path, 0755); err != nil && !os.IsExist(err) {
			return fmt.Errorf("mkdirall %s %s", m.path, err)
		}
		if err := system.Mount(m.source, m.path, m.device, uintptr(m.flags), m.data); err != nil {
			return fmt.Errorf("mounting %s into %s %s", m.source, m.path, err)
		}
	}
	return nil
}