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moby--moby/libnetwork/osl/namespace_linux.go
Madhu Venugopal 25f0573785 Make osl sandbox basepath configurable via execroot.
Signed-off-by: Madhu Venugopal <madhu@docker.com>
2016-07-18 05:14:39 -07:00

500 lines
11 KiB
Go

package osl
import (
"fmt"
"io/ioutil"
"net"
"os"
"os/exec"
"path/filepath"
"runtime"
"strconv"
"strings"
"sync"
"syscall"
"time"
log "github.com/Sirupsen/logrus"
"github.com/docker/docker/pkg/reexec"
"github.com/docker/libnetwork/ns"
"github.com/docker/libnetwork/types"
"github.com/vishvananda/netlink"
"github.com/vishvananda/netns"
)
const defaultPrefix = "/var/run/docker"
var (
once sync.Once
garbagePathMap = make(map[string]bool)
gpmLock sync.Mutex
gpmWg sync.WaitGroup
gpmCleanupPeriod = 60 * time.Second
gpmChan = make(chan chan struct{})
prefix = defaultPrefix
)
// The networkNamespace type is the linux implementation of the Sandbox
// interface. It represents a linux network namespace, and moves an interface
// into it when called on method AddInterface or sets the gateway etc.
type networkNamespace struct {
path string
iFaces []*nwIface
gw net.IP
gwv6 net.IP
staticRoutes []*types.StaticRoute
neighbors []*neigh
nextIfIndex int
isDefault bool
nlHandle *netlink.Handle
sync.Mutex
}
// SetBasePath sets the base url prefix for the ns path
func SetBasePath(path string) {
prefix = path
}
func init() {
reexec.Register("netns-create", reexecCreateNamespace)
}
func basePath() string {
return filepath.Join(prefix, "netns")
}
func createBasePath() {
err := os.MkdirAll(basePath(), 0755)
if err != nil {
panic("Could not create net namespace path directory")
}
// Start the garbage collection go routine
go removeUnusedPaths()
}
func removeUnusedPaths() {
gpmLock.Lock()
period := gpmCleanupPeriod
gpmLock.Unlock()
ticker := time.NewTicker(period)
for {
var (
gc chan struct{}
gcOk bool
)
select {
case <-ticker.C:
case gc, gcOk = <-gpmChan:
}
gpmLock.Lock()
pathList := make([]string, 0, len(garbagePathMap))
for path := range garbagePathMap {
pathList = append(pathList, path)
}
garbagePathMap = make(map[string]bool)
gpmWg.Add(1)
gpmLock.Unlock()
for _, path := range pathList {
os.Remove(path)
}
gpmWg.Done()
if gcOk {
close(gc)
}
}
}
func addToGarbagePaths(path string) {
gpmLock.Lock()
garbagePathMap[path] = true
gpmLock.Unlock()
}
func removeFromGarbagePaths(path string) {
gpmLock.Lock()
delete(garbagePathMap, path)
gpmLock.Unlock()
}
// GC triggers garbage collection of namespace path right away
// and waits for it.
func GC() {
gpmLock.Lock()
if len(garbagePathMap) == 0 {
// No need for GC if map is empty
gpmLock.Unlock()
return
}
gpmLock.Unlock()
// if content exists in the garbage paths
// we can trigger GC to run, providing a
// channel to be notified on completion
waitGC := make(chan struct{})
gpmChan <- waitGC
// wait for GC completion
<-waitGC
}
// GenerateKey generates a sandbox key based on the passed
// container id.
func GenerateKey(containerID string) string {
maxLen := 12
// Read sandbox key from host for overlay
if strings.HasPrefix(containerID, "-") {
var (
index int
indexStr string
tmpkey string
)
dir, err := ioutil.ReadDir(basePath())
if err != nil {
return ""
}
for _, v := range dir {
id := v.Name()
if strings.HasSuffix(id, containerID[:maxLen-1]) {
indexStr = strings.TrimSuffix(id, containerID[:maxLen-1])
tmpindex, err := strconv.Atoi(indexStr)
if err != nil {
return ""
}
if tmpindex > index {
index = tmpindex
tmpkey = id
}
}
}
containerID = tmpkey
if containerID == "" {
return ""
}
}
if len(containerID) < maxLen {
maxLen = len(containerID)
}
return basePath() + "/" + containerID[:maxLen]
}
// NewSandbox provides a new sandbox instance created in an os specific way
// provided a key which uniquely identifies the sandbox
func NewSandbox(key string, osCreate, isRestore bool) (Sandbox, error) {
if !isRestore {
err := createNetworkNamespace(key, osCreate)
if err != nil {
return nil, err
}
} else {
once.Do(createBasePath)
}
n := &networkNamespace{path: key, isDefault: !osCreate}
sboxNs, err := netns.GetFromPath(n.path)
if err != nil {
return nil, fmt.Errorf("failed get network namespace %q: %v", n.path, err)
}
defer sboxNs.Close()
n.nlHandle, err = netlink.NewHandleAt(sboxNs, syscall.NETLINK_ROUTE)
if err != nil {
return nil, fmt.Errorf("failed to create a netlink handle: %v", err)
}
if err = n.loopbackUp(); err != nil {
n.nlHandle.Delete()
return nil, err
}
return n, nil
}
func (n *networkNamespace) InterfaceOptions() IfaceOptionSetter {
return n
}
func (n *networkNamespace) NeighborOptions() NeighborOptionSetter {
return n
}
func mountNetworkNamespace(basePath string, lnPath string) error {
return syscall.Mount(basePath, lnPath, "bind", syscall.MS_BIND, "")
}
// GetSandboxForExternalKey returns sandbox object for the supplied path
func GetSandboxForExternalKey(basePath string, key string) (Sandbox, error) {
if err := createNamespaceFile(key); err != nil {
return nil, err
}
if err := mountNetworkNamespace(basePath, key); err != nil {
return nil, err
}
n := &networkNamespace{path: key}
sboxNs, err := netns.GetFromPath(n.path)
if err != nil {
return nil, fmt.Errorf("failed get network namespace %q: %v", n.path, err)
}
defer sboxNs.Close()
n.nlHandle, err = netlink.NewHandleAt(sboxNs, syscall.NETLINK_ROUTE)
if err != nil {
return nil, fmt.Errorf("failed to create a netlink handle: %v", err)
}
if err = n.loopbackUp(); err != nil {
n.nlHandle.Delete()
return nil, err
}
return n, nil
}
func reexecCreateNamespace() {
if len(os.Args) < 2 {
log.Fatal("no namespace path provided")
}
if err := mountNetworkNamespace("/proc/self/ns/net", os.Args[1]); err != nil {
log.Fatal(err)
}
}
func createNetworkNamespace(path string, osCreate bool) error {
if err := createNamespaceFile(path); err != nil {
return err
}
cmd := &exec.Cmd{
Path: reexec.Self(),
Args: append([]string{"netns-create"}, path),
Stdout: os.Stdout,
Stderr: os.Stderr,
}
if osCreate {
cmd.SysProcAttr = &syscall.SysProcAttr{}
cmd.SysProcAttr.Cloneflags = syscall.CLONE_NEWNET
}
if err := cmd.Run(); err != nil {
return fmt.Errorf("namespace creation reexec command failed: %v", err)
}
return nil
}
func unmountNamespaceFile(path string) {
if _, err := os.Stat(path); err == nil {
syscall.Unmount(path, syscall.MNT_DETACH)
}
}
func createNamespaceFile(path string) (err error) {
var f *os.File
once.Do(createBasePath)
// Remove it from garbage collection list if present
removeFromGarbagePaths(path)
// If the path is there unmount it first
unmountNamespaceFile(path)
// wait for garbage collection to complete if it is in progress
// before trying to create the file.
gpmWg.Wait()
if f, err = os.Create(path); err == nil {
f.Close()
}
return err
}
func (n *networkNamespace) loopbackUp() error {
iface, err := n.nlHandle.LinkByName("lo")
if err != nil {
return err
}
return n.nlHandle.LinkSetUp(iface)
}
func (n *networkNamespace) InvokeFunc(f func()) error {
return nsInvoke(n.nsPath(), func(nsFD int) error { return nil }, func(callerFD int) error {
f()
return nil
})
}
// InitOSContext initializes OS context while configuring network resources
func InitOSContext() func() {
runtime.LockOSThread()
if err := ns.SetNamespace(); err != nil {
log.Error(err)
}
return runtime.UnlockOSThread
}
func nsInvoke(path string, prefunc func(nsFD int) error, postfunc func(callerFD int) error) error {
defer InitOSContext()()
newNs, err := netns.GetFromPath(path)
if err != nil {
return fmt.Errorf("failed get network namespace %q: %v", path, err)
}
defer newNs.Close()
// Invoked before the namespace switch happens but after the namespace file
// handle is obtained.
if err := prefunc(int(newNs)); err != nil {
return fmt.Errorf("failed in prefunc: %v", err)
}
if err = netns.Set(newNs); err != nil {
return err
}
defer ns.SetNamespace()
// Invoked after the namespace switch.
return postfunc(ns.ParseHandlerInt())
}
func (n *networkNamespace) nsPath() string {
n.Lock()
defer n.Unlock()
return n.path
}
func (n *networkNamespace) Info() Info {
return n
}
func (n *networkNamespace) Key() string {
return n.path
}
func (n *networkNamespace) Destroy() error {
if n.nlHandle != nil {
n.nlHandle.Delete()
}
// Assuming no running process is executing in this network namespace,
// unmounting is sufficient to destroy it.
if err := syscall.Unmount(n.path, syscall.MNT_DETACH); err != nil {
return err
}
// Stash it into the garbage collection list
addToGarbagePaths(n.path)
return nil
}
// Restore restore the network namespace
func (n *networkNamespace) Restore(ifsopt map[string][]IfaceOption, routes []*types.StaticRoute, gw net.IP, gw6 net.IP) error {
// restore interfaces
for name, opts := range ifsopt {
if !strings.Contains(name, "+") {
return fmt.Errorf("wrong iface name in restore osl sandbox interface: %s", name)
}
seps := strings.Split(name, "+")
srcName := seps[0]
dstPrefix := seps[1]
i := &nwIface{srcName: srcName, dstName: dstPrefix, ns: n}
i.processInterfaceOptions(opts...)
if i.master != "" {
i.dstMaster = n.findDst(i.master, true)
if i.dstMaster == "" {
return fmt.Errorf("could not find an appropriate master %q for %q",
i.master, i.srcName)
}
}
if n.isDefault {
i.dstName = i.srcName
} else {
links, err := n.nlHandle.LinkList()
if err != nil {
return fmt.Errorf("failed to retrieve list of links in network namespace %q during restore", n.path)
}
// due to the docker network connect/disconnect, so the dstName should
// restore from the namespace
for _, link := range links {
addrs, err := n.nlHandle.AddrList(link, netlink.FAMILY_V4)
if err != nil {
return err
}
ifaceName := link.Attrs().Name
if strings.HasPrefix(ifaceName, "vxlan") {
if i.dstName == "vxlan" {
i.dstName = ifaceName
break
}
}
// find the interface name by ip
if i.address != nil {
for _, addr := range addrs {
if addr.IPNet.String() == i.address.String() {
i.dstName = ifaceName
break
}
continue
}
if i.dstName == ifaceName {
break
}
}
// This is to find the interface name of the pair in overlay sandbox
if strings.HasPrefix(ifaceName, "veth") {
if i.master != "" && i.dstName == "veth" {
i.dstName = ifaceName
}
}
}
var index int
indexStr := strings.TrimPrefix(i.dstName, dstPrefix)
if indexStr != "" {
index, err = strconv.Atoi(indexStr)
if err != nil {
return err
}
}
index++
n.Lock()
if index > n.nextIfIndex {
n.nextIfIndex = index
}
n.iFaces = append(n.iFaces, i)
n.Unlock()
}
}
// restore routes
for _, r := range routes {
n.Lock()
n.staticRoutes = append(n.staticRoutes, r)
n.Unlock()
}
// restore gateway
if len(gw) > 0 {
n.Lock()
n.gw = gw
n.Unlock()
}
if len(gw6) > 0 {
n.Lock()
n.gwv6 = gw6
n.Unlock()
}
return nil
}