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Refactor mounts into pkg to make changes easier

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Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
This commit is contained in:
Michael Crosby 2014-04-11 15:06:56 +00:00
parent 323ea01c18
commit a77846506b
9 changed files with 191 additions and 138 deletions
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144
libcontainer/mount/init.go Normal file
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// +build linux
package mount
import (
"fmt"
"github.com/dotcloud/docker/pkg/label"
"github.com/dotcloud/docker/pkg/libcontainer"
"github.com/dotcloud/docker/pkg/libcontainer/mount/nodes"
"github.com/dotcloud/docker/pkg/libcontainer/security/restrict"
"github.com/dotcloud/docker/pkg/system"
"os"
"path/filepath"
"syscall"
)
// default mount point flags
const defaultMountFlags = syscall.MS_NOEXEC | syscall.MS_NOSUID | syscall.MS_NODEV
type mount struct {
source string
path string
device string
flags int
data string
}
// 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
}
// mountSystem sets up linux specific system mounts like sys, proc, shm, and devpts
// inside the mount namespace
func mountSystem(rootfs string, container *libcontainer.Container) error {
for _, m := range newSystemMounts(rootfs, container.Context["mount_label"], container.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
}
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
}
func newSystemMounts(rootfs, mountLabel string, mounts libcontainer.Mounts) []mount {
devMounts := []mount{
{source: "shm", path: filepath.Join(rootfs, "dev", "shm"), device: "tmpfs", flags: defaultMountFlags, data: label.FormatMountLabel("mode=1777,size=65536k", mountLabel)},
{source: "devpts", path: filepath.Join(rootfs, "dev", "pts"), device: "devpts", flags: syscall.MS_NOSUID | syscall.MS_NOEXEC, data: label.FormatMountLabel("newinstance,ptmxmode=0666,mode=620,gid=5", mountLabel)},
}
systemMounts := []mount{
{source: "proc", path: filepath.Join(rootfs, "proc"), device: "proc", flags: defaultMountFlags},
}
if len(mounts.OfType("devtmpfs")) == 1 {
systemMounts = append(systemMounts, mount{source: "tmpfs", path: filepath.Join(rootfs, "dev"), device: "tmpfs", flags: syscall.MS_NOSUID | syscall.MS_STRICTATIME, data: "mode=755"})
}
systemMounts = append(systemMounts, devMounts...)
if len(mounts.OfType("sysfs")) == 1 {
systemMounts = append(systemMounts, mount{source: "sysfs", path: filepath.Join(rootfs, "sys"), device: "sysfs", flags: defaultMountFlags})
}
return systemMounts
}

19
libcontainer/mount/msmoveroot.go Normal file
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// +build linux
package mount
import (
"fmt"
"github.com/dotcloud/docker/pkg/system"
"syscall"
)
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("/")
}

49
libcontainer/mount/nodes/nodes.go Normal file
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// +build linux
package nodes
import (
"fmt"
"github.com/dotcloud/docker/pkg/system"
"os"
"path/filepath"
"syscall"
)
// Default list of device nodes to copy
var DefaultNodes = []string{
"null",
"zero",
"full",
"random",
"urandom",
"tty",
}
// CopyN copies the device node from the host into the rootfs
func CopyN(rootfs string, nodesToCopy []string) error {
oldMask := system.Umask(0000)
defer system.Umask(oldMask)
for _, node := range nodesToCopy {
if err := Copy(rootfs, node); err != nil {
return err
}
}
return nil
}
func Copy(rootfs, node string) error {
stat, err := os.Stat(filepath.Join("/dev", node))
if err != nil {
return err
}
var (
dest = filepath.Join(rootfs, "dev", node)
st = stat.Sys().(*syscall.Stat_t)
)
if err := system.Mknod(dest, st.Mode, int(st.Rdev)); err != nil && !os.IsExist(err) {
return fmt.Errorf("copy %s %s", node, err)
}
return nil
}

31
libcontainer/mount/pivotroot.go Normal file
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// +build linux
package mount
import (
"fmt"
"github.com/dotcloud/docker/pkg/system"
"io/ioutil"
"os"
"path/filepath"
"syscall"
)
func PivotRoot(rootfs string) error {
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)
}
return os.Remove(pivotDir)
}

26
libcontainer/mount/ptmx.go Normal file
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// +build linux
package mount
import (
"fmt"
"github.com/dotcloud/docker/pkg/libcontainer/console"
"os"
"path/filepath"
)
func SetupPtmx(rootfs, consolePath, mountLabel string) error {
ptmx := filepath.Join(rootfs, "dev/ptmx")
if err := os.Remove(ptmx); err != nil && !os.IsNotExist(err) {
return err
}
if err := os.Symlink("pts/ptmx", ptmx); err != nil {
return fmt.Errorf("symlink dev ptmx %s", err)
}
if consolePath != "" {
if err := console.Setup(rootfs, consolePath, mountLabel); err != nil {
return err
}
}
return nil
}

12
libcontainer/mount/readonly.go Normal file
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// +build linux
package mount
import (
"github.com/dotcloud/docker/pkg/system"
"syscall"
)
func SetReadonly() error {
return system.Mount("/", "/", "bind", syscall.MS_BIND|syscall.MS_REMOUNT|syscall.MS_RDONLY|syscall.MS_REC, "")
}

31
libcontainer/mount/remount.go Normal file
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// +build linux
package mount
import (
"github.com/dotcloud/docker/pkg/system"
"syscall"
)
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
}
func RemountSys() error {
if err := system.Unmount("/sys", syscall.MNT_DETACH); err != nil {
if err != syscall.EINVAL {
return err
}
} else {
if err := system.Mount("sysfs", "/sys", "sysfs", uintptr(defaultMountFlags), ""); err != nil {
return err
}
}
return nil
}