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// +build linux
package libcontainer
import (
"fmt"
"io"
"os"
"syscall"
"github.com/opencontainers/runc/libcontainer/apparmor"
"github.com/opencontainers/runc/libcontainer/configs"
"github.com/opencontainers/runc/libcontainer/keys"
"github.com/opencontainers/runc/libcontainer/label"
"github.com/opencontainers/runc/libcontainer/seccomp"
"github.com/opencontainers/runc/libcontainer/system"
)
type linuxStandardInit struct {
pipe io.ReadWriter
parentPid int
config *initConfig
}
func (l *linuxStandardInit) getSessionRingParams() (string, uint32, uint32) {
var newperms uint32
if l.config.Config.Namespaces.Contains(configs.NEWUSER) {
// with user ns we need 'other' search permissions
newperms = 0x8
} else {
// without user ns we need 'UID' search permissions
newperms = 0x80000
}
// create a unique per session container name that we can
// join in setns; however, other containers can also join it
return fmt.Sprintf("_ses.%s", l.config.ContainerId), 0xffffffff, newperms
}
// PR_SET_NO_NEW_PRIVS isn't exposed in Golang so we define it ourselves copying the value
// the kernel
const PR_SET_NO_NEW_PRIVS = 0x26
func (l *linuxStandardInit) Init() error {
ringname, keepperms, newperms := l.getSessionRingParams()
// do not inherit the parent's session keyring
sessKeyId, err := keyctl.JoinSessionKeyring(ringname)
if err != nil {
return err
}
// make session keyring searcheable
if err := keyctl.ModKeyringPerm(sessKeyId, keepperms, newperms); err != nil {
return err
}
var console *linuxConsole
if l.config.Console != "" {
console = newConsoleFromPath(l.config.Console)
if err := console.dupStdio(); err != nil {
return err
}
}
if console != nil {
if err := system.Setctty(); err != nil {
return err
}
}
if err := setupNetwork(l.config); err != nil {
return err
}
if err := setupRoute(l.config.Config); err != nil {
return err
}
label.Init()
// InitializeMountNamespace() can be executed only for a new mount namespace
if l.config.Config.Namespaces.Contains(configs.NEWNS) {
if err := setupRootfs(l.config.Config, console, l.pipe); err != nil {
return err
}
}
if hostname := l.config.Config.Hostname; hostname != "" {
if err := syscall.Sethostname([]byte(hostname)); err != nil {
return err
}
}
if err := apparmor.ApplyProfile(l.config.AppArmorProfile); err != nil {
return err
}
if err := label.SetProcessLabel(l.config.ProcessLabel); err != nil {
return err
}
for key, value := range l.config.Config.Sysctl {
if err := writeSystemProperty(key, value); err != nil {
return err
}
}
for _, path := range l.config.Config.ReadonlyPaths {
if err := remountReadonly(path); err != nil {
return err
}
}
for _, path := range l.config.Config.MaskPaths {
if err := maskFile(path); err != nil {
return err
}
}
pdeath, err := system.GetParentDeathSignal()
if err != nil {
return err
}
if l.config.NoNewPrivileges {
if err := system.Prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0); err != nil {
return err
}
}
// Tell our parent that we're ready to Execv. This must be done before the
// Seccomp rules have been applied, because we need to be able to read and
// write to a socket.
if err := syncParentReady(l.pipe); err != nil {
return err
}
if l.config.Config.Seccomp != nil {
if err := seccomp.InitSeccomp(l.config.Config.Seccomp); err != nil {
return err
}
}
if err := finalizeNamespace(l.config); err != nil {
return err
}
// finalizeNamespace can change user/group which clears the parent death
// signal, so we restore it here.
if err := pdeath.Restore(); err != nil {
return err
}
// compare the parent from the inital start of the init process and make sure that it did not change.
// if the parent changes that means it died and we were reparened to something else so we should
// just kill ourself and not cause problems for someone else.
if syscall.Getppid() != l.parentPid {
return syscall.Kill(syscall.Getpid(), syscall.SIGKILL)
}
return system.Execv(l.config.Args[0], l.config.Args[0:], os.Environ())
}
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