use rootless netns from c/common

Use the new rootlessnetns logic from c/common, drop the podman code
here and make use of the new much simpler API.

ref: https://github.com/containers/common/pull/1761

[NO NEW TESTS NEEDED]

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

utils/utils.go

@@ -2,20 +2,16 @@ package utils
 
 import (
 	"bytes"
-	"crypto/rand"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
-	"github.com/containers/common/pkg/cgroups"
 	"github.com/containers/storage/pkg/archive"
 	"github.com/containers/storage/pkg/chrootarchive"
-	"github.com/godbus/dbus/v5"
 	"github.com/sirupsen/logrus"
 	"github.com/vbauerster/mpb/v8"
 	"github.com/vbauerster/mpb/v8/decor"
@@ -133,121 +129,6 @@ func RemoveScientificNotationFromFloat(x float64) (float64, error) {
 	return result, nil
 }
 
-var (
-	runsOnSystemdOnce sync.Once
-	runsOnSystemd     bool
-)
-
-// RunsOnSystemd returns whether the system is using systemd
-func RunsOnSystemd() bool {
-	runsOnSystemdOnce.Do(func() {
-		// per sd_booted(3), check for this dir
-		fd, err := os.Stat("/run/systemd/system")
-		runsOnSystemd = err == nil && fd.IsDir()
-	})
-	return runsOnSystemd
-}
-
-func moveProcessPIDFileToScope(pidPath, slice, scope string) error {
-	data, err := os.ReadFile(pidPath)
-	if err != nil {
-		// do not raise an error if the file doesn't exist
-		if os.IsNotExist(err) {
-			return nil
-		}
-		return fmt.Errorf("cannot read pid file: %w", err)
-	}
-	pid, err := strconv.ParseUint(string(data), 10, 0)
-	if err != nil {
-		return fmt.Errorf("cannot parse pid file %s: %w", pidPath, err)
-	}
-
-	return moveProcessToScope(int(pid), slice, scope)
-}
-
-func moveProcessToScope(pid int, slice, scope string) error {
-	err := RunUnderSystemdScope(pid, slice, scope)
-	// If the PID is not valid anymore, do not return an error.
-	if dbusErr, ok := err.(dbus.Error); ok {
-		if dbusErr.Name == "org.freedesktop.DBus.Error.UnixProcessIdUnknown" {
-			return nil
-		}
-	}
-	return err
-}
-
-// MoveRootlessNetnsSlirpProcessToUserSlice moves the slirp4netns process for the rootless netns
-// into a different scope so that systemd does not kill it with a container.
-func MoveRootlessNetnsSlirpProcessToUserSlice(pid int) error {
-	randBytes := make([]byte, 4)
-	_, err := rand.Read(randBytes)
-	if err != nil {
-		return err
-	}
-	return moveProcessToScope(pid, "user.slice", fmt.Sprintf("rootless-netns-%x.scope", randBytes))
-}
-
-// MovePauseProcessToScope moves the pause process used for rootless mode to keep the namespaces alive to
-// a separate scope.
-func MovePauseProcessToScope(pausePidPath string) {
-	var err error
-
-	for i := 0; i < 10; i++ {
-		randBytes := make([]byte, 4)
-		_, err = rand.Read(randBytes)
-		if err != nil {
-			logrus.Errorf("failed to read random bytes: %v", err)
-			continue
-		}
-		err = moveProcessPIDFileToScope(pausePidPath, "user.slice", fmt.Sprintf("podman-pause-%x.scope", randBytes))
-		if err == nil {
-			return
-		}
-	}
-
-	if err != nil {
-		unified, err2 := cgroups.IsCgroup2UnifiedMode()
-		if err2 != nil {
-			logrus.Warnf("Failed to detect if running with cgroup unified: %v", err)
-		}
-		if RunsOnSystemd() && unified {
-			logrus.Warnf("Failed to add pause process to systemd sandbox cgroup: %v", err)
-		} else {
-			logrus.Debugf("Failed to add pause process to systemd sandbox cgroup: %v", err)
-		}
-	}
-}
-
-var (
-	maybeMoveToSubCgroupSync    sync.Once
-	maybeMoveToSubCgroupSyncErr error
-)
-
-// MaybeMoveToSubCgroup moves the current process in a sub cgroup when
-// it is running in the root cgroup on a system that uses cgroupv2.
-func MaybeMoveToSubCgroup() error {
-	maybeMoveToSubCgroupSync.Do(func() {
-		unifiedMode, err := cgroups.IsCgroup2UnifiedMode()
-		if err != nil {
-			maybeMoveToSubCgroupSyncErr = err
-			return
-		}
-		if !unifiedMode {
-			maybeMoveToSubCgroupSyncErr = nil
-			return
-		}
-		cgroup, err := GetOwnCgroup()
-		if err != nil {
-			maybeMoveToSubCgroupSyncErr = err
-			return
-		}
-		if cgroup == "/" {
-			maybeMoveToSubCgroupSyncErr = MoveUnderCgroupSubtree("init")
-		}
-	})
-	return maybeMoveToSubCgroupSyncErr
-}
-
 // GuardedRemoveAll functions much like os.RemoveAll but
 // will not delete certain catastrophic paths.
 func GuardedRemoveAll(path string) error {