blob: f191c16ee29529588cd1805df4ef5cf1d3adaa28 [file] [log] [blame]
// +build linux
package libcontainer
import (
"encoding/json"
"errors"
"io"
"os"
"os/exec"
"path/filepath"
"strconv"
"syscall"
"github.com/opencontainers/runc/libcontainer/cgroups"
"github.com/opencontainers/runc/libcontainer/configs"
"github.com/opencontainers/runc/libcontainer/system"
)
type parentProcess interface {
// pid returns the pid for the running process.
pid() int
// start starts the process execution.
start() error
// send a SIGKILL to the process and wait for the exit.
terminate() error
// wait waits on the process returning the process state.
wait() (*os.ProcessState, error)
// startTime return's the process start time.
startTime() (string, error)
signal(os.Signal) error
externalDescriptors() []string
setExternalDescriptors(fds []string)
}
type setnsProcess struct {
cmd *exec.Cmd
parentPipe *os.File
childPipe *os.File
cgroupPaths map[string]string
config *initConfig
fds []string
}
func (p *setnsProcess) startTime() (string, error) {
return system.GetProcessStartTime(p.pid())
}
func (p *setnsProcess) signal(sig os.Signal) error {
s, ok := sig.(syscall.Signal)
if !ok {
return errors.New("os: unsupported signal type")
}
return syscall.Kill(p.cmd.Process.Pid, s)
}
func (p *setnsProcess) start() (err error) {
defer p.parentPipe.Close()
if err = p.execSetns(); err != nil {
return newSystemError(err)
}
if len(p.cgroupPaths) > 0 {
if err := cgroups.EnterPid(p.cgroupPaths, p.cmd.Process.Pid); err != nil {
return newSystemError(err)
}
}
if err := json.NewEncoder(p.parentPipe).Encode(p.config); err != nil {
return newSystemError(err)
}
if err := syscall.Shutdown(int(p.parentPipe.Fd()), syscall.SHUT_WR); err != nil {
return newSystemError(err)
}
// wait for the child process to fully complete and receive an error message
// if one was encoutered
var ierr *genericError
if err := json.NewDecoder(p.parentPipe).Decode(&ierr); err != nil && err != io.EOF {
return newSystemError(err)
}
if ierr != nil {
return newSystemError(ierr)
}
return nil
}
// execSetns runs the process that executes C code to perform the setns calls
// because setns support requires the C process to fork off a child and perform the setns
// before the go runtime boots, we wait on the process to die and receive the child's pid
// over the provided pipe.
func (p *setnsProcess) execSetns() error {
err := p.cmd.Start()
p.childPipe.Close()
if err != nil {
return newSystemError(err)
}
status, err := p.cmd.Process.Wait()
if err != nil {
p.cmd.Wait()
return newSystemError(err)
}
if !status.Success() {
p.cmd.Wait()
return newSystemError(&exec.ExitError{ProcessState: status})
}
var pid *pid
if err := json.NewDecoder(p.parentPipe).Decode(&pid); err != nil {
p.cmd.Wait()
return newSystemError(err)
}
process, err := os.FindProcess(pid.Pid)
if err != nil {
return err
}
p.cmd.Process = process
return nil
}
// terminate sends a SIGKILL to the forked process for the setns routine then waits to
// avoid the process becomming a zombie.
func (p *setnsProcess) terminate() error {
if p.cmd.Process == nil {
return nil
}
err := p.cmd.Process.Kill()
if _, werr := p.wait(); err == nil {
err = werr
}
return err
}
func (p *setnsProcess) wait() (*os.ProcessState, error) {
err := p.cmd.Wait()
// Return actual ProcessState even on Wait error
return p.cmd.ProcessState, err
}
func (p *setnsProcess) pid() int {
return p.cmd.Process.Pid
}
func (p *setnsProcess) externalDescriptors() []string {
return p.fds
}
func (p *setnsProcess) setExternalDescriptors(newFds []string) {
p.fds = newFds
}
type initProcess struct {
cmd *exec.Cmd
parentPipe *os.File
childPipe *os.File
config *initConfig
manager cgroups.Manager
container *linuxContainer
fds []string
}
func (p *initProcess) pid() int {
return p.cmd.Process.Pid
}
func (p *initProcess) externalDescriptors() []string {
return p.fds
}
func (p *initProcess) start() (err error) {
defer p.parentPipe.Close()
err = p.cmd.Start()
p.childPipe.Close()
if err != nil {
return newSystemError(err)
}
// Save the standard descriptor names before the container process
// can potentially move them (e.g., via dup2()). If we don't do this now,
// we won't know at checkpoint time which file descriptor to look up.
fds, err := getPipeFds(p.pid())
if err != nil {
return newSystemError(err)
}
p.setExternalDescriptors(fds)
// Do this before syncing with child so that no children
// can escape the cgroup
if err := p.manager.Apply(p.pid()); err != nil {
return newSystemError(err)
}
defer func() {
if err != nil {
// TODO: should not be the responsibility to call here
p.manager.Destroy()
}
}()
if p.config.Config.Hooks != nil {
s := configs.HookState{
ID: p.container.id,
Pid: p.pid(),
Root: p.config.Config.Rootfs,
}
for _, hook := range p.config.Config.Hooks.Prestart {
if err := hook.Run(s); err != nil {
return newSystemError(err)
}
}
}
if err := p.createNetworkInterfaces(); err != nil {
return newSystemError(err)
}
if err := p.sendConfig(); err != nil {
return newSystemError(err)
}
// wait for the child process to fully complete and receive an error message
// if one was encoutered
var ierr *genericError
if err := json.NewDecoder(p.parentPipe).Decode(&ierr); err != nil && err != io.EOF {
return newSystemError(err)
}
if ierr != nil {
return newSystemError(ierr)
}
return nil
}
func (p *initProcess) wait() (*os.ProcessState, error) {
err := p.cmd.Wait()
if err != nil {
return p.cmd.ProcessState, err
}
// we should kill all processes in cgroup when init is died if we use host PID namespace
if p.cmd.SysProcAttr.Cloneflags&syscall.CLONE_NEWPID == 0 {
killCgroupProcesses(p.manager)
}
return p.cmd.ProcessState, nil
}
func (p *initProcess) terminate() error {
if p.cmd.Process == nil {
return nil
}
err := p.cmd.Process.Kill()
if _, werr := p.wait(); err == nil {
err = werr
}
return err
}
func (p *initProcess) startTime() (string, error) {
return system.GetProcessStartTime(p.pid())
}
func (p *initProcess) sendConfig() error {
// send the state to the container's init process then shutdown writes for the parent
if err := json.NewEncoder(p.parentPipe).Encode(p.config); err != nil {
return err
}
// shutdown writes for the parent side of the pipe
return syscall.Shutdown(int(p.parentPipe.Fd()), syscall.SHUT_WR)
}
func (p *initProcess) createNetworkInterfaces() error {
for _, config := range p.config.Config.Networks {
strategy, err := getStrategy(config.Type)
if err != nil {
return err
}
n := &network{
Network: *config,
}
if err := strategy.create(n, p.pid()); err != nil {
return err
}
p.config.Networks = append(p.config.Networks, n)
}
return nil
}
func (p *initProcess) signal(sig os.Signal) error {
s, ok := sig.(syscall.Signal)
if !ok {
return errors.New("os: unsupported signal type")
}
return syscall.Kill(p.cmd.Process.Pid, s)
}
func (p *initProcess) setExternalDescriptors(newFds []string) {
p.fds = newFds
}
func getPipeFds(pid int) ([]string, error) {
fds := make([]string, 3)
dirPath := filepath.Join("/proc", strconv.Itoa(pid), "/fd")
for i := 0; i < 3; i++ {
f := filepath.Join(dirPath, strconv.Itoa(i))
target, err := os.Readlink(f)
if err != nil {
return fds, err
}
fds[i] = target
}
return fds, nil
}