daemon/container_operations_unix.go
//go:build linux || freebsd
package daemon // import "github.com/docker/docker/daemon"
import (
"context"
"fmt"
"os"
"path/filepath"
"strconv"
"syscall"
"github.com/containerd/log"
"github.com/docker/docker/container"
"github.com/docker/docker/daemon/config"
"github.com/docker/docker/daemon/links"
"github.com/docker/docker/daemon/network"
"github.com/docker/docker/errdefs"
"github.com/docker/docker/libnetwork"
"github.com/docker/docker/pkg/idtools"
"github.com/docker/docker/pkg/process"
"github.com/docker/docker/pkg/stringid"
"github.com/moby/sys/mount"
"github.com/opencontainers/selinux/go-selinux/label"
"github.com/pkg/errors"
"golang.org/x/sys/unix"
)
func (daemon *Daemon) setupLinkedContainers(ctr *container.Container) ([]string, error) {
var env []string
children := daemon.children(ctr)
bridgeSettings := ctr.NetworkSettings.Networks[network.DefaultNetwork]
if bridgeSettings == nil || bridgeSettings.EndpointSettings == nil {
return nil, nil
}
for linkAlias, child := range children {
if !child.IsRunning() {
return nil, fmt.Errorf("Cannot link to a non running container: %s AS %s", child.Name, linkAlias)
}
childBridgeSettings := child.NetworkSettings.Networks[network.DefaultNetwork]
if childBridgeSettings == nil || childBridgeSettings.EndpointSettings == nil {
return nil, fmt.Errorf("container %s not attached to default bridge network", child.ID)
}
link := links.NewLink(
bridgeSettings.IPAddress,
childBridgeSettings.IPAddress,
linkAlias,
child.Config.Env,
child.Config.ExposedPorts,
)
env = append(env, link.ToEnv()...)
}
return env, nil
}
func (daemon *Daemon) getIPCContainer(id string) (*container.Container, error) {
// Check if the container exists, is running, and not restarting
ctr, err := daemon.GetContainer(id)
if err != nil {
return nil, errdefs.InvalidParameter(err)
}
if !ctr.IsRunning() {
return nil, errNotRunning(id)
}
if ctr.IsRestarting() {
return nil, errContainerIsRestarting(id)
}
// Check the container ipc is shareable
if st, err := os.Stat(ctr.ShmPath); err != nil || !st.IsDir() {
if err == nil || os.IsNotExist(err) {
return nil, errdefs.InvalidParameter(errors.New("container " + id + ": non-shareable IPC (hint: use IpcMode:shareable for the donor container)"))
}
// stat() failed?
return nil, errdefs.System(errors.Wrap(err, "container "+id))
}
return ctr, nil
}
func (daemon *Daemon) getPIDContainer(id string) (*container.Container, error) {
ctr, err := daemon.GetContainer(id)
if err != nil {
return nil, errdefs.InvalidParameter(err)
}
if !ctr.IsRunning() {
return nil, errNotRunning(id)
}
if ctr.IsRestarting() {
return nil, errContainerIsRestarting(id)
}
return ctr, nil
}
// setupContainerDirs sets up base container directories (root, ipc, tmpfs and secrets).
func (daemon *Daemon) setupContainerDirs(ctr *container.Container) (_ []container.Mount, err error) {
if err := daemon.setupContainerMountsRoot(ctr); err != nil {
return nil, err
}
if err := daemon.setupIPCDirs(ctr); err != nil {
return nil, err
}
if err := daemon.setupSecretDir(ctr); err != nil {
return nil, err
}
defer func() {
if err != nil {
daemon.cleanupSecretDir(ctr)
}
}()
var ms []container.Mount
if !ctr.HostConfig.IpcMode.IsPrivate() && !ctr.HostConfig.IpcMode.IsEmpty() {
ms = append(ms, ctr.IpcMounts()...)
}
tmpfsMounts, err := ctr.TmpfsMounts()
if err != nil {
return nil, err
}
ms = append(ms, tmpfsMounts...)
secretMounts, err := ctr.SecretMounts()
if err != nil {
return nil, err
}
ms = append(ms, secretMounts...)
return ms, nil
}
func (daemon *Daemon) setupIPCDirs(ctr *container.Container) error {
ipcMode := ctr.HostConfig.IpcMode
switch {
case ipcMode.IsContainer():
ic, err := daemon.getIPCContainer(ipcMode.Container())
if err != nil {
return errors.Wrapf(err, "failed to join IPC namespace")
}
ctr.ShmPath = ic.ShmPath
case ipcMode.IsHost():
if _, err := os.Stat("/dev/shm"); err != nil {
return fmt.Errorf("/dev/shm is not mounted, but must be for --ipc=host")
}
ctr.ShmPath = "/dev/shm"
case ipcMode.IsPrivate(), ipcMode.IsNone():
// c.ShmPath will/should not be used, so make it empty.
// Container's /dev/shm mount comes from OCI spec.
ctr.ShmPath = ""
case ipcMode.IsEmpty():
// A container was created by an older version of the daemon.
// The default behavior used to be what is now called "shareable".
fallthrough
case ipcMode.IsShareable():
rootIDs := daemon.idMapping.RootPair()
if !ctr.HasMountFor("/dev/shm") {
shmPath, err := ctr.ShmResourcePath()
if err != nil {
return err
}
if err := idtools.MkdirAllAndChown(shmPath, 0o700, rootIDs); err != nil {
return err
}
shmproperty := "mode=1777,size=" + strconv.FormatInt(ctr.HostConfig.ShmSize, 10)
if err := unix.Mount("shm", shmPath, "tmpfs", uintptr(unix.MS_NOEXEC|unix.MS_NOSUID|unix.MS_NODEV), label.FormatMountLabel(shmproperty, ctr.GetMountLabel())); err != nil {
return fmt.Errorf("mounting shm tmpfs: %s", err)
}
if err := os.Chown(shmPath, rootIDs.UID, rootIDs.GID); err != nil {
return err
}
ctr.ShmPath = shmPath
}
default:
return fmt.Errorf("invalid IPC mode: %v", ipcMode)
}
return nil
}
func (daemon *Daemon) setupSecretDir(ctr *container.Container) (setupErr error) {
if len(ctr.SecretReferences) == 0 && len(ctr.ConfigReferences) == 0 {
return nil
}
if err := daemon.createSecretsDir(ctr); err != nil {
return err
}
defer func() {
if setupErr != nil {
daemon.cleanupSecretDir(ctr)
}
}()
if ctr.DependencyStore == nil {
return fmt.Errorf("secret store is not initialized")
}
// retrieve possible remapped range start for root UID, GID
rootIDs := daemon.idMapping.RootPair()
for _, s := range ctr.SecretReferences {
// TODO (ehazlett): use type switch when more are supported
if s.File == nil {
log.G(context.TODO()).Error("secret target type is not a file target")
continue
}
// secrets are created in the SecretMountPath on the host, at a
// single level
fPath, err := ctr.SecretFilePath(*s)
if err != nil {
return errors.Wrap(err, "error getting secret file path")
}
if err := idtools.MkdirAllAndChown(filepath.Dir(fPath), 0o700, rootIDs); err != nil {
return errors.Wrap(err, "error creating secret mount path")
}
log.G(context.TODO()).WithFields(log.Fields{
"name": s.File.Name,
"path": fPath,
}).Debug("injecting secret")
secret, err := ctr.DependencyStore.Secrets().Get(s.SecretID)
if err != nil {
return errors.Wrap(err, "unable to get secret from secret store")
}
if err := os.WriteFile(fPath, secret.Spec.Data, s.File.Mode); err != nil {
return errors.Wrap(err, "error injecting secret")
}
uid, err := strconv.Atoi(s.File.UID)
if err != nil {
return err
}
gid, err := strconv.Atoi(s.File.GID)
if err != nil {
return err
}
if err := os.Chown(fPath, rootIDs.UID+uid, rootIDs.GID+gid); err != nil {
return errors.Wrap(err, "error setting ownership for secret")
}
if err := os.Chmod(fPath, s.File.Mode); err != nil {
return errors.Wrap(err, "error setting file mode for secret")
}
}
for _, configRef := range ctr.ConfigReferences {
// TODO (ehazlett): use type switch when more are supported
if configRef.File == nil {
// Runtime configs are not mounted into the container, but they're
// a valid type of config so we should not error when we encounter
// one.
if configRef.Runtime == nil {
log.G(context.TODO()).Error("config target type is not a file or runtime target")
}
// However, in any case, this isn't a file config, so we have no
// further work to do
continue
}
fPath, err := ctr.ConfigFilePath(*configRef)
if err != nil {
return errors.Wrap(err, "error getting config file path for container")
}
if err := idtools.MkdirAllAndChown(filepath.Dir(fPath), 0o700, rootIDs); err != nil {
return errors.Wrap(err, "error creating config mount path")
}
log.G(context.TODO()).WithFields(log.Fields{
"name": configRef.File.Name,
"path": fPath,
}).Debug("injecting config")
config, err := ctr.DependencyStore.Configs().Get(configRef.ConfigID)
if err != nil {
return errors.Wrap(err, "unable to get config from config store")
}
if err := os.WriteFile(fPath, config.Spec.Data, configRef.File.Mode); err != nil {
return errors.Wrap(err, "error injecting config")
}
uid, err := strconv.Atoi(configRef.File.UID)
if err != nil {
return err
}
gid, err := strconv.Atoi(configRef.File.GID)
if err != nil {
return err
}
if err := os.Chown(fPath, rootIDs.UID+uid, rootIDs.GID+gid); err != nil {
return errors.Wrap(err, "error setting ownership for config")
}
if err := os.Chmod(fPath, configRef.File.Mode); err != nil {
return errors.Wrap(err, "error setting file mode for config")
}
}
return daemon.remountSecretDir(ctr)
}
// createSecretsDir is used to create a dir suitable for storing container secrets.
// In practice this is using a tmpfs mount and is used for both "configs" and "secrets"
func (daemon *Daemon) createSecretsDir(ctr *container.Container) error {
// retrieve possible remapped range start for root UID, GID
rootIDs := daemon.idMapping.RootPair()
dir, err := ctr.SecretMountPath()
if err != nil {
return errors.Wrap(err, "error getting container secrets dir")
}
// create tmpfs
if err := idtools.MkdirAllAndChown(dir, 0o700, rootIDs); err != nil {
return errors.Wrap(err, "error creating secret local mount path")
}
tmpfsOwnership := fmt.Sprintf("uid=%d,gid=%d", rootIDs.UID, rootIDs.GID)
if err := mount.Mount("tmpfs", dir, "tmpfs", "nodev,nosuid,noexec,"+tmpfsOwnership); err != nil {
return errors.Wrap(err, "unable to setup secret mount")
}
return nil
}
func (daemon *Daemon) remountSecretDir(ctr *container.Container) error {
dir, err := ctr.SecretMountPath()
if err != nil {
return errors.Wrap(err, "error getting container secrets path")
}
if err := label.Relabel(dir, ctr.MountLabel, false); err != nil {
log.G(context.TODO()).WithError(err).WithField("dir", dir).Warn("Error while attempting to set selinux label")
}
rootIDs := daemon.idMapping.RootPair()
tmpfsOwnership := fmt.Sprintf("uid=%d,gid=%d", rootIDs.UID, rootIDs.GID)
// remount secrets ro
if err := mount.Mount("tmpfs", dir, "tmpfs", "remount,ro,"+tmpfsOwnership); err != nil {
return errors.Wrap(err, "unable to remount dir as readonly")
}
return nil
}
func (daemon *Daemon) cleanupSecretDir(ctr *container.Container) {
dir, err := ctr.SecretMountPath()
if err != nil {
log.G(context.TODO()).WithError(err).WithField("container", ctr.ID).Warn("error getting secrets mount path for container")
}
if err := mount.RecursiveUnmount(dir); err != nil {
log.G(context.TODO()).WithField("dir", dir).WithError(err).Warn("Error while attempting to unmount dir, this may prevent removal of container.")
}
if err := os.RemoveAll(dir); err != nil {
log.G(context.TODO()).WithField("dir", dir).WithError(err).Error("Error removing dir.")
}
}
func killProcessDirectly(ctr *container.Container) error {
pid := ctr.GetPID()
if pid == 0 {
// Ensure that we don't kill ourselves
return nil
}
if err := unix.Kill(pid, syscall.SIGKILL); err != nil {
if err != unix.ESRCH {
return errdefs.System(err)
}
err = errNoSuchProcess{pid, syscall.SIGKILL}
log.G(context.TODO()).WithError(err).WithField("container", ctr.ID).Debug("no such process")
return err
}
// In case there were some exceptions(e.g., state of zombie and D)
if process.Alive(pid) {
// Since we can not kill a zombie pid, add zombie check here
isZombie, err := process.Zombie(pid)
if err != nil {
log.G(context.TODO()).WithError(err).WithField("container", ctr.ID).Warn("Container state is invalid")
return err
}
if isZombie {
return errdefs.System(errors.Errorf("container %s PID %d is zombie and can not be killed. Use the --init option when creating containers to run an init inside the container that forwards signals and reaps processes", stringid.TruncateID(ctr.ID), pid))
}
}
return nil
}
func isLinkable(child *container.Container) bool {
// A container is linkable only if it belongs to the default network
_, ok := child.NetworkSettings.Networks[network.DefaultNetwork]
return ok
}
// TODO(aker): remove when we make the default bridge network behave like any other network
func enableIPOnPredefinedNetwork() bool {
return false
}
// serviceDiscoveryOnDefaultNetwork indicates if service discovery is supported on the default network
// TODO(aker): remove when we make the default bridge network behave like any other network
func serviceDiscoveryOnDefaultNetwork() bool {
return false
}
func buildSandboxPlatformOptions(ctr *container.Container, cfg *config.Config, sboxOptions *[]libnetwork.SandboxOption) error {
var err error
var originResolvConfPath string
// Set the correct paths for /etc/hosts and /etc/resolv.conf, based on the
// networking-mode of the container. Note that containers with "container"
// networking are already handled in "initializeNetworking()" before we reach
// this function, so do not have to be accounted for here.
switch {
case ctr.HostConfig.NetworkMode.IsHost():
// In host-mode networking, the container does not have its own networking
// namespace, so both `/etc/hosts` and `/etc/resolv.conf` should be the same
// as on the host itself. The container gets a copy of these files.
*sboxOptions = append(
*sboxOptions,
libnetwork.OptionOriginHostsPath("/etc/hosts"),
)
originResolvConfPath = "/etc/resolv.conf"
case ctr.HostConfig.NetworkMode.IsUserDefined():
// The container uses a user-defined network. We use the embedded DNS
// server for container name resolution and to act as a DNS forwarder
// for external DNS resolution.
// We parse the DNS server(s) that are defined in /etc/resolv.conf on
// the host, which may be a local DNS server (for example, if DNSMasq or
// systemd-resolvd are in use). The embedded DNS server forwards DNS
// resolution to the DNS server configured on the host, which in itself
// may act as a forwarder for external DNS servers.
// If systemd-resolvd is used, the "upstream" DNS servers can be found in
// /run/systemd/resolve/resolv.conf. We do not query those DNS servers
// directly, as they can be dynamically reconfigured.
originResolvConfPath = "/etc/resolv.conf"
default:
// For other situations, such as the default bridge network, container
// discovery / name resolution is handled through /etc/hosts, and no
// embedded DNS server is available. Without the embedded DNS, we
// cannot use local DNS servers on the host (for example, if DNSMasq or
// systemd-resolvd is used). If systemd-resolvd is used, we try to
// determine the external DNS servers that are used on the host.
// This situation is not ideal, because DNS servers configured in the
// container are not updated after the container is created, but the
// DNS servers on the host can be dynamically updated.
//
// Copy the host's resolv.conf for the container (/run/systemd/resolve/resolv.conf or /etc/resolv.conf)
originResolvConfPath = cfg.GetResolvConf()
}
// Allow tests to point at their own resolv.conf file.
if envPath := os.Getenv("DOCKER_TEST_RESOLV_CONF_PATH"); envPath != "" {
log.G(context.TODO()).Infof("Using OriginResolvConfPath from env: %s", envPath)
originResolvConfPath = envPath
}
*sboxOptions = append(*sboxOptions, libnetwork.OptionOriginResolvConfPath(originResolvConfPath))
ctr.HostsPath, err = ctr.GetRootResourcePath("hosts")
if err != nil {
return err
}
*sboxOptions = append(*sboxOptions, libnetwork.OptionHostsPath(ctr.HostsPath))
ctr.ResolvConfPath, err = ctr.GetRootResourcePath("resolv.conf")
if err != nil {
return err
}
*sboxOptions = append(*sboxOptions, libnetwork.OptionResolvConfPath(ctr.ResolvConfPath))
return nil
}
func (daemon *Daemon) initializeNetworkingPaths(ctr *container.Container, nc *container.Container) error {
ctr.HostnamePath = nc.HostnamePath
ctr.HostsPath = nc.HostsPath
ctr.ResolvConfPath = nc.ResolvConfPath
return nil
}
func (daemon *Daemon) setupContainerMountsRoot(ctr *container.Container) error {
// get the root mount path so we can make it unbindable
p, err := ctr.MountsResourcePath("")
if err != nil {
return err
}
return idtools.MkdirAllAndChown(p, 0o710, idtools.Identity{UID: idtools.CurrentIdentity().UID, GID: daemon.IdentityMapping().RootPair().GID})
}