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dockerd: fix rootless detection (alternative to #39024) 

The `--rootless` flag had a couple of issues:
* #38702: euid=0, $USER="root" but no access to cgroup ("rootful" Docker in rootless Docker)
* #39009: euid=0 but $USER="docker" (rootful boot2docker)

To fix #38702, XDG dirs are ignored as in rootful Docker, unless the
dockerd is directly running under RootlessKit namespaces.

RootlessKit detection is implemented by checking whether `$ROOTLESSKIT_STATE_DIR` is set.

To fix #39009, the non-robust `$USER` check is now completely removed.

The entire logic can be illustrated as follows:

```
withRootlessKit := getenv("ROOTLESSKIT_STATE_DIR")
rootlessMode := withRootlessKit || cliFlag("--rootless")
honorXDG := withRootlessKit
useRootlessKitDockerProxy := withRootlessKit
removeCgroupSpec := rootlessMode
adjustOOMScoreAdj := rootlessMode
```

Close #39024
Fix #38702 #39009

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
This commit is contained in:
Akihiro Suda 2019-04-19 16:53:58 +09:00
parent 3cd54c28fd
commit 3518383ed9
8 changed files with 61 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
cmd/dockerd/config_common_unix.go
View File

@ -9,12 +9,11 @@ import (
"github.com/docker/docker/daemon/config"
"github.com/docker/docker/opts"
"github.com/docker/docker/pkg/homedir"
"github.com/docker/docker/rootless"
"github.com/spf13/pflag"
)
func getDefaultPidFile() (string, error) {
if !rootless.RunningWithNonRootUsername() {
if !honorXDG {
return "/var/run/docker.pid", nil
}
runtimeDir, err := homedir.GetRuntimeDir()
@ -25,7 +24,7 @@ func getDefaultPidFile() (string, error) {
}
func getDefaultDataRoot() (string, error) {
if !rootless.RunningWithNonRootUsername() {
if !honorXDG {
return "/var/lib/docker", nil
}
dataHome, err := homedir.GetDataHome()
@ -36,7 +35,7 @@ func getDefaultDataRoot() (string, error) {
}
func getDefaultExecRoot() (string, error) {
if !rootless.RunningWithNonRootUsername() {
if !honorXDG {
return "/var/run/docker", nil
}
runtimeDir, err := homedir.GetRuntimeDir()

19
cmd/dockerd/config_unix.go
View File

@ -3,10 +3,13 @@
package main
import (
"os/exec"
"github.com/docker/docker/daemon/config"
"github.com/docker/docker/opts"
"github.com/docker/docker/rootless"
"github.com/docker/go-units"
"github.com/pkg/errors"
"github.com/spf13/pflag"
)
@ -35,7 +38,16 @@ func installConfigFlags(conf *config.Config, flags *pflag.FlagSet) error {
flags.BoolVar(&conf.BridgeConfig.EnableIPv6, "ipv6", false, "Enable IPv6 networking")
flags.StringVar(&conf.BridgeConfig.FixedCIDRv6, "fixed-cidr-v6", "", "IPv6 subnet for fixed IPs")
flags.BoolVar(&conf.BridgeConfig.EnableUserlandProxy, "userland-proxy", true, "Use userland proxy for loopback traffic")
flags.StringVar(&conf.BridgeConfig.UserlandProxyPath, "userland-proxy-path", "", "Path to the userland proxy binary")
defaultUserlandProxyPath := ""
if rootless.RunningWithRootlessKit() {
var err error
// use rootlesskit-docker-proxy for exposing the ports in RootlessKit netns to the initial namespace.
defaultUserlandProxyPath, err = exec.LookPath(rootless.RootlessKitDockerProxyBinary)
if err != nil {
return errors.Wrapf(err, "running with RootlessKit, but %s not installed", rootless.RootlessKitDockerProxyBinary)
}
}
flags.StringVar(&conf.BridgeConfig.UserlandProxyPath, "userland-proxy-path", defaultUserlandProxyPath, "Path to the userland proxy binary")
flags.StringVar(&conf.CgroupParent, "cgroup-parent", "", "Set parent cgroup for all containers")
flags.StringVar(&conf.RemappedRoot, "userns-remap", "", "User/Group setting for user namespaces")
flags.BoolVar(&conf.LiveRestoreEnabled, "live-restore", false, "Enable live restore of docker when containers are still running")
@ -49,7 +61,8 @@ func installConfigFlags(conf *config.Config, flags *pflag.FlagSet) error {
flags.BoolVar(&conf.NoNewPrivileges, "no-new-privileges", false, "Set no-new-privileges by default for new containers")
flags.StringVar(&conf.IpcMode, "default-ipc-mode", config.DefaultIpcMode, `Default mode for containers ipc ("shareable" | "private")`)
flags.Var(&conf.NetworkConfig.DefaultAddressPools, "default-address-pool", "Default address pools for node specific local networks")
// Mostly users don't need to set this flag explicitly.
flags.BoolVar(&conf.Rootless, "rootless", rootless.RunningWithNonRootUsername(), "Enable rootless mode (experimental)")
// rootless needs to be explicitly specified for running "rootful" dockerd in rootless dockerd (#38702)
// Note that defaultUserlandProxyPath and honorXDG are configured according to the value of rootless.RunningWithRootlessKit, not the value of --rootless.
flags.BoolVar(&conf.Rootless, "rootless", rootless.RunningWithRootlessKit(), "Enable rootless mode; typically used with RootlessKit (experimental)")
return nil
}

12
cmd/dockerd/daemon.go
View File

@ -103,6 +103,12 @@ func (cli *DaemonCli) start(opts *daemonOptions) (err error) {
if cli.Config.IsRootless() {
logrus.Warn("Running in rootless mode. Cgroups, AppArmor, and CRIU are disabled.")
}
if rootless.RunningWithRootlessKit() {
logrus.Info("Running with RootlessKit integration")
if !cli.Config.IsRootless() {
return fmt.Errorf("rootless mode needs to be enabled for running with RootlessKit")
}
}
} else {
if cli.Config.IsRootless() {
return fmt.Errorf("rootless mode is supported only when running in experimental mode")
@ -591,7 +597,7 @@ func loadListeners(cli *DaemonCli, serverConfig *apiserver.Config) ([]string, er
var hosts []string
for i := 0; i < len(cli.Config.Hosts); i++ {
var err error
if cli.Config.Hosts[i], err = dopts.ParseHost(cli.Config.TLS, rootless.RunningWithNonRootUsername(), cli.Config.Hosts[i]); err != nil {
if cli.Config.Hosts[i], err = dopts.ParseHost(cli.Config.TLS, honorXDG, cli.Config.Hosts[i]); err != nil {
return nil, errors.Wrapf(err, "error parsing -H %s", cli.Config.Hosts[i])
}
@ -668,9 +674,9 @@ func validateAuthzPlugins(requestedPlugins []string, pg plugingetter.PluginGette
return nil
}
func systemContainerdRunning(isRootless bool) (string, bool, error) {
func systemContainerdRunning(honorXDG bool) (string, bool, error) {
addr := containerddefaults.DefaultAddress
if isRootless {
if honorXDG {
runtimeDir, err := homedir.GetRuntimeDir()
if err != nil {
return "", false, err

5
cmd/dockerd/daemon_unix.go
View File

@ -18,14 +18,13 @@ import (
"github.com/docker/docker/daemon/config"
"github.com/docker/docker/libcontainerd/supervisor"
"github.com/docker/docker/pkg/homedir"
"github.com/docker/docker/rootless"
"github.com/docker/libnetwork/portallocator"
"github.com/pkg/errors"
"golang.org/x/sys/unix"
)
func getDefaultDaemonConfigDir() (string, error) {
if !rootless.RunningWithNonRootUsername() {
if !honorXDG {
return "/etc/docker", nil
}
// NOTE: CLI uses ~/.docker while the daemon uses ~/.config/docker, because
@ -148,7 +147,7 @@ func newCgroupParent(config *config.Config) string {
func (cli *DaemonCli) initContainerD(ctx context.Context) (func(time.Duration) error, error) {
var waitForShutdown func(time.Duration) error
if cli.Config.ContainerdAddr == "" {
systemContainerdAddr, ok, err := systemContainerdRunning(cli.Config.IsRootless())
systemContainerdAddr, ok, err := systemContainerdRunning(honorXDG)
if err != nil {
return nil, errors.Wrap(err, "could not determine whether the system containerd is running")
}

13
cmd/dockerd/docker.go
View File

@ -10,11 +10,16 @@ import (
"github.com/docker/docker/pkg/jsonmessage"
"github.com/docker/docker/pkg/reexec"
"github.com/docker/docker/pkg/term"
"github.com/docker/docker/rootless"
"github.com/moby/buildkit/util/apicaps"
"github.com/sirupsen/logrus"
"github.com/spf13/cobra"
)
var (
honorXDG bool
)
func newDaemonCommand() (*cobra.Command, error) {
opts := newDaemonOptions(config.New())
@ -53,6 +58,14 @@ func init() {
if dockerversion.ProductName != "" {
apicaps.ExportedProduct = dockerversion.ProductName
}
// When running with RootlessKit, $XDG_RUNTIME_DIR, $XDG_DATA_HOME, and $XDG_CONFIG_HOME needs to be
// honored as the default dirs, because we are unlikely to have permissions to access the system-wide
// directories.
//
// Note that even running with --rootless, when not running with RootlessKit, honorXDG needs to be kept false,
// because the system-wide directories in the current mount namespace are expected to be accessible.
// ("rootful" dockerd in rootless dockerd, #38702)
honorXDG = rootless.RunningWithRootlessKit()
}
func main() {

3
docs/rootless.md
View File

@ -55,10 +55,9 @@ penguin:231072:65536
You need to run `dockerd-rootless.sh` instead of `dockerd`.
```console
$ dockerd-rootless.sh --experimental --userland-proxy --userland-proxy-path=$(which rootlesskit-docker-proxy)"
$ dockerd-rootless.sh --experimental
```
As Rootless mode is experimental per se, currently you always need to run `dockerd-rootless.sh` with `--experimental`.
Also, to expose ports, you need to set `--userland-proxy-path` to the path of `rootlesskit-docker-proxy` binary.
Remarks:
* The socket path is set to `$XDG_RUNTIME_DIR/docker.sock` by default. `$XDG_RUNTIME_DIR` is typically set to `/run/user/$UID`.

6
opts/hosts.go
View File

@ -45,13 +45,13 @@ func ValidateHost(val string) (string, error) {
}
// ParseHost and set defaults for a Daemon host string.
// defaultToTLS is preferred over defaultToUnixRootless.
func ParseHost(defaultToTLS, defaultToUnixRootless bool, val string) (string, error) {
// defaultToTLS is preferred over defaultToUnixXDG.
func ParseHost(defaultToTLS, defaultToUnixXDG bool, val string) (string, error) {
host := strings.TrimSpace(val)
if host == "" {
if defaultToTLS {
host = DefaultTLSHost
} else if defaultToUnixRootless {
} else if defaultToUnixXDG {
runtimeDir, err := homedir.GetRuntimeDir()
if err != nil {
return "", err

29
rootless/rootless.go
View File

@ -5,22 +5,21 @@ import (
"sync"
)
var (
runningWithNonRootUsername bool
runningWithNonRootUsernameOnce sync.Once
const (
// RootlessKitDockerProxyBinary is the binary name of rootlesskit-docker-proxy
RootlessKitDockerProxyBinary = "rootlesskit-docker-proxy"
)
// RunningWithNonRootUsername returns true if we $USER is set to a non-root value,
// regardless to the UID/EUID value.
//
// The value of this variable is mostly used for configuring default paths.
// If the value is true, $HOME and $XDG_RUNTIME_DIR should be honored for setting up the default paths.
// If false (not only EUID==0 but also $USER==root), $HOME and $XDG_RUNTIME_DIR should be ignored
// even if we are in a user namespace.
func RunningWithNonRootUsername() bool {
runningWithNonRootUsernameOnce.Do(func() {
u := os.Getenv("USER")
runningWithNonRootUsername = u != "" && u != "root"
var (
runningWithRootlessKit bool
runningWithRootlessKitOnce sync.Once
)
// RunningWithRootlessKit returns true if running under RootlessKit namespaces.
func RunningWithRootlessKit() bool {
runningWithRootlessKitOnce.Do(func() {
u := os.Getenv("ROOTLESSKIT_STATE_DIR")
runningWithRootlessKit = u != ""
})
return runningWithNonRootUsername
return runningWithRootlessKit
}