mirror of
https://github.com/k3s-io/kubernetes.git
synced 2025-10-31 05:40:42 +00:00
215 lines
7.3 KiB
Go
215 lines
7.3 KiB
Go
// +build linux
|
|
|
|
package libcontainer
|
|
|
|
import (
|
|
"fmt"
|
|
"os"
|
|
"os/exec"
|
|
"runtime"
|
|
"syscall" //only for Exec
|
|
|
|
"github.com/opencontainers/runc/libcontainer/apparmor"
|
|
"github.com/opencontainers/runc/libcontainer/configs"
|
|
"github.com/opencontainers/runc/libcontainer/keys"
|
|
"github.com/opencontainers/runc/libcontainer/seccomp"
|
|
"github.com/opencontainers/runc/libcontainer/system"
|
|
"github.com/opencontainers/selinux/go-selinux/label"
|
|
"github.com/pkg/errors"
|
|
|
|
"golang.org/x/sys/unix"
|
|
)
|
|
|
|
type linuxStandardInit struct {
|
|
pipe *os.File
|
|
consoleSocket *os.File
|
|
parentPid int
|
|
fifoFd 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
|
|
}
|
|
|
|
func (l *linuxStandardInit) Init() error {
|
|
runtime.LockOSThread()
|
|
defer runtime.UnlockOSThread()
|
|
if !l.config.Config.NoNewKeyring {
|
|
if err := label.SetKeyLabel(l.config.ProcessLabel); err != nil {
|
|
return err
|
|
}
|
|
defer label.SetKeyLabel("")
|
|
ringname, keepperms, newperms := l.getSessionRingParams()
|
|
|
|
// Do not inherit the parent's session keyring.
|
|
if sessKeyId, err := keys.JoinSessionKeyring(ringname); err != nil {
|
|
// If keyrings aren't supported then it is likely we are on an
|
|
// older kernel (or inside an LXC container). While we could bail,
|
|
// the security feature we are using here is best-effort (it only
|
|
// really provides marginal protection since VFS credentials are
|
|
// the only significant protection of keyrings).
|
|
//
|
|
// TODO(cyphar): Log this so people know what's going on, once we
|
|
// have proper logging in 'runc init'.
|
|
if errors.Cause(err) != unix.ENOSYS {
|
|
return errors.Wrap(err, "join session keyring")
|
|
}
|
|
} else {
|
|
// Make session keyring searcheable. If we've gotten this far we
|
|
// bail on any error -- we don't want to have a keyring with bad
|
|
// permissions.
|
|
if err := keys.ModKeyringPerm(sessKeyId, keepperms, newperms); err != nil {
|
|
return errors.Wrap(err, "mod keyring permissions")
|
|
}
|
|
}
|
|
}
|
|
|
|
if err := setupNetwork(l.config); err != nil {
|
|
return err
|
|
}
|
|
if err := setupRoute(l.config.Config); err != nil {
|
|
return err
|
|
}
|
|
|
|
label.Init()
|
|
if err := prepareRootfs(l.pipe, l.config); err != nil {
|
|
return err
|
|
}
|
|
// Set up the console. This has to be done *before* we finalize the rootfs,
|
|
// but *after* we've given the user the chance to set up all of the mounts
|
|
// they wanted.
|
|
if l.config.CreateConsole {
|
|
if err := setupConsole(l.consoleSocket, l.config, true); err != nil {
|
|
return err
|
|
}
|
|
if err := system.Setctty(); err != nil {
|
|
return errors.Wrap(err, "setctty")
|
|
}
|
|
}
|
|
|
|
// Finish the rootfs setup.
|
|
if l.config.Config.Namespaces.Contains(configs.NEWNS) {
|
|
if err := finalizeRootfs(l.config.Config); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
|
|
if hostname := l.config.Config.Hostname; hostname != "" {
|
|
if err := unix.Sethostname([]byte(hostname)); err != nil {
|
|
return errors.Wrap(err, "sethostname")
|
|
}
|
|
}
|
|
if err := apparmor.ApplyProfile(l.config.AppArmorProfile); err != nil {
|
|
return errors.Wrap(err, "apply apparmor profile")
|
|
}
|
|
|
|
for key, value := range l.config.Config.Sysctl {
|
|
if err := writeSystemProperty(key, value); err != nil {
|
|
return errors.Wrapf(err, "write sysctl key %s", key)
|
|
}
|
|
}
|
|
for _, path := range l.config.Config.ReadonlyPaths {
|
|
if err := readonlyPath(path); err != nil {
|
|
return errors.Wrapf(err, "readonly path %s", path)
|
|
}
|
|
}
|
|
for _, path := range l.config.Config.MaskPaths {
|
|
if err := maskPath(path, l.config.Config.MountLabel); err != nil {
|
|
return errors.Wrapf(err, "mask path %s", path)
|
|
}
|
|
}
|
|
pdeath, err := system.GetParentDeathSignal()
|
|
if err != nil {
|
|
return errors.Wrap(err, "get pdeath signal")
|
|
}
|
|
if l.config.NoNewPrivileges {
|
|
if err := unix.Prctl(unix.PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0); err != nil {
|
|
return errors.Wrap(err, "set nonewprivileges")
|
|
}
|
|
}
|
|
// 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 errors.Wrap(err, "sync ready")
|
|
}
|
|
if err := label.SetProcessLabel(l.config.ProcessLabel); err != nil {
|
|
return errors.Wrap(err, "set process label")
|
|
}
|
|
defer label.SetProcessLabel("")
|
|
// Without NoNewPrivileges seccomp is a privileged operation, so we need to
|
|
// do this before dropping capabilities; otherwise do it as late as possible
|
|
// just before execve so as few syscalls take place after it as possible.
|
|
if l.config.Config.Seccomp != nil && !l.config.NoNewPrivileges {
|
|
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 errors.Wrap(err, "restore pdeath signal")
|
|
}
|
|
// Compare the parent from the initial start of the init process and make
|
|
// sure that it did not change. if the parent changes that means it died
|
|
// and we were reparented to something else so we should just kill ourself
|
|
// and not cause problems for someone else.
|
|
if unix.Getppid() != l.parentPid {
|
|
return unix.Kill(unix.Getpid(), unix.SIGKILL)
|
|
}
|
|
// Check for the arg before waiting to make sure it exists and it is
|
|
// returned as a create time error.
|
|
name, err := exec.LookPath(l.config.Args[0])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
// Close the pipe to signal that we have completed our init.
|
|
l.pipe.Close()
|
|
// Wait for the FIFO to be opened on the other side before exec-ing the
|
|
// user process. We open it through /proc/self/fd/$fd, because the fd that
|
|
// was given to us was an O_PATH fd to the fifo itself. Linux allows us to
|
|
// re-open an O_PATH fd through /proc.
|
|
fd, err := unix.Open(fmt.Sprintf("/proc/self/fd/%d", l.fifoFd), unix.O_WRONLY|unix.O_CLOEXEC, 0)
|
|
if err != nil {
|
|
return newSystemErrorWithCause(err, "open exec fifo")
|
|
}
|
|
if _, err := unix.Write(fd, []byte("0")); err != nil {
|
|
return newSystemErrorWithCause(err, "write 0 exec fifo")
|
|
}
|
|
// Close the O_PATH fifofd fd before exec because the kernel resets
|
|
// dumpable in the wrong order. This has been fixed in newer kernels, but
|
|
// we keep this to ensure CVE-2016-9962 doesn't re-emerge on older kernels.
|
|
// N.B. the core issue itself (passing dirfds to the host filesystem) has
|
|
// since been resolved.
|
|
// https://github.com/torvalds/linux/blob/v4.9/fs/exec.c#L1290-L1318
|
|
unix.Close(l.fifoFd)
|
|
// Set seccomp as close to execve as possible, so as few syscalls take
|
|
// place afterward (reducing the amount of syscalls that users need to
|
|
// enable in their seccomp profiles).
|
|
if l.config.Config.Seccomp != nil && l.config.NoNewPrivileges {
|
|
if err := seccomp.InitSeccomp(l.config.Config.Seccomp); err != nil {
|
|
return newSystemErrorWithCause(err, "init seccomp")
|
|
}
|
|
}
|
|
if err := syscall.Exec(name, l.config.Args[0:], os.Environ()); err != nil {
|
|
return newSystemErrorWithCause(err, "exec user process")
|
|
}
|
|
return nil
|
|
}
|