rootless: fix pod rm when uid in the container != 0

join the user namespace where the pod is running, so that we can both
manage the storage and correctly send the kill signal to a process
which is not running as root in the namespace.

Closes: containers#2577

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

cmd/podman/main.go

@@ -70,6 +70,8 @@ var cmdsNotRequiringRootless = map[*cobra.Command]bool{
 	_mountCommand:   true,
 	_killCommand:    true,
 	_pauseCommand:   true,
+	_podKillCommand: true,
+	_podRmCommand:   true,
 	_restartCommand: true,
 	_runCommand:     true,
 	_unpauseCommand: true,

cmd/podman/pod_rm.go

@@ -2,9 +2,11 @@ package main
 
 import (
 	"fmt"
+	"os"
 
 	"github.com/containers/libpod/cmd/podman/cliconfig"
 	"github.com/containers/libpod/pkg/adapter"
+	"github.com/containers/libpod/pkg/rootless"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -46,11 +48,40 @@ func init() {
 
 // podRmCmd deletes pods
 func podRmCmd(c *cliconfig.PodRmValues) error {
+	if os.Geteuid() != 0 {
+		rootless.SetSkipStorageSetup(true)
+	}
 	runtime, err := adapter.GetRuntime(&c.PodmanCommand)
 	if err != nil {
 		return errors.Wrapf(err, "could not get runtime")
 	}
 	defer runtime.Shutdown(false)
+
+	if rootless.IsRootless() {
+		var pod *adapter.Pod
+		if c.All || len(c.InputArgs) > 1 {
+			return errors.New("rootless mode doesn't support more than 1 pod")
+		}
+		if c.Latest {
+			pod, err = runtime.GetLatestPod()
+			if err != nil {
+				return errors.Wrapf(err, "unable to get latest pod")
+			}
+		} else {
+			pod, err = runtime.LookupPod(c.InputArgs[0])
+			if err != nil {
+				return err
+			}
+		}
+		became, ret, err := runtime.JoinOrCreateRootlessPod(pod)
+		if err != nil {
+			return err
+		}
+		if became {
+			os.Exit(ret)
+		}
+	}
+
 	podRmIds, podRmErrors := runtime.RemovePods(getContext(), c)
 	for _, p := range podRmIds {
 		fmt.Println(p)

pkg/adapter/runtime.go

@@ -337,3 +337,40 @@ func IsImageNotFound(err error) bool {
 func (r *LocalRuntime) HealthCheck(c *cliconfig.HealthCheckValues) (libpod.HealthCheckStatus, error) {
 	return r.Runtime.HealthCheck(c.InputArgs[0])
 }
+
+// JoinOrCreateRootlessPod joins the specified pod if it is running or it creates a new user namespace
+// if the pod is stopped
+func (r *LocalRuntime) JoinOrCreateRootlessPod(pod *Pod) (bool, int, error) {
+	if os.Geteuid() == 0 {
+		return false, 0, nil
+	}
+
+	inspect, err := pod.Inspect()
+	if err != nil {
+		return false, 0, err
+	}
+	for _, ctr := range inspect.Containers {
+		prevCtr, err := r.LookupContainer(ctr.ID)
+		if err != nil {
+			return false, -1, err
+		}
+		s, err := prevCtr.State()
+		if err != nil {
+			return false, -1, err
+		}
+		if s != libpod.ContainerStateRunning && s != libpod.ContainerStatePaused {
+			continue
+		}
+		data, err := ioutil.ReadFile(prevCtr.Config().ConmonPidFile)
+		if err != nil {
+			return false, -1, errors.Wrapf(err, "cannot read conmon PID file %q", prevCtr.Config().ConmonPidFile)
+		}
+		conmonPid, err := strconv.Atoi(string(data))
+		if err != nil {
+			return false, -1, errors.Wrapf(err, "cannot parse PID %q", data)
+		}
+		return rootless.JoinDirectUserAndMountNS(uint(conmonPid))
+	}
+
+	return rootless.BecomeRootInUserNS()
+}

pkg/adapter/runtime_remote.go

@@ -751,3 +751,10 @@ func IsImageNotFound(err error) bool {
 func (r *LocalRuntime) HealthCheck(c *cliconfig.HealthCheckValues) (libpod.HealthCheckStatus, error) {
 	return -1, libpod.ErrNotImplemented
 }
+
+// JoinOrCreateRootlessPod joins the specified pod if it is running or it creates a new user namespace
+// if the pod is stopped
+func (r *LocalRuntime) JoinOrCreateRootlessPod(pod *Pod) (bool, int, error) {
+	// Nothing to do in the remote case
+	return true, 0, nil
+}