rootless cni without infra container

Instead of creating an extra container create a network and mount
namespace inside the podman user namespace. This ns is used to
for rootless cni operations.
This helps to align the rootless and rootful network code path.
If we run as rootless we just have to set up a extra net ns and
initialize slirp4netns in it. The ocicni lib will be called in
that net ns.

This design allows allows easier maintenance, no extra container
with pause processes, support for rootless cni with --uidmap
and possibly more.

The biggest problem is backwards compatibility. I don't think
live migration can be possible. If the user reboots or restart
all cni containers everything should work as expected again.
The user is left with the rootless-cni-infa container and image
but this can safely be removed.

To make the existing cni configs work we need execute the cni plugins
in a extra mount namespace. This ensures that we can safely mount over
/run and /var which have to be writeable for the cni plugins without
removing access to these files by the main podman process. One caveat
is that we need to keep the netns files at `XDG_RUNTIME_DIR/netns`
accessible.

`XDG_RUNTIME_DIR/rootless-cni/{run,var}` will be mounted to `/{run,var}`.
To ensure that we keep the netns directory we bind mount this relative
to the new root location, e.g. XDG_RUNTIME_DIR/rootless-cni/run/user/1000/netns
before we mount the run directory. The run directory is mounted recursive,
this makes the netns directory at the same path accessible as before.

This also allows iptables-legacy to work because /run/xtables.lock is
now writeable.

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>

libpod/container_internal_linux.go

@@ -92,11 +92,7 @@ func (c *Container) prepare() error {
 		// Set up network namespace if not already set up
 		noNetNS := c.state.NetNS == nil
 		if c.config.CreateNetNS && noNetNS && !c.config.PostConfigureNetNS {
-			if rootless.IsRootless() && len(c.config.Networks) > 0 {
-				netNS, networkStatus, createNetNSErr = AllocRootlessCNI(context.Background(), c)
-			} else {
 			netNS, networkStatus, createNetNSErr = c.runtime.createNetNS(c)
-			}
 			if createNetNSErr != nil {
 				return
 			}

libpod/network/create.go

@@ -11,7 +11,6 @@ import (
 	"github.com/containernetworking/cni/pkg/version"
 	"github.com/containers/common/pkg/config"
 	"github.com/containers/podman/v3/pkg/domain/entities"
-	"github.com/containers/podman/v3/pkg/rootless"
 	"github.com/containers/podman/v3/pkg/util"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -223,9 +222,8 @@ func createBridge(name string, options entities.NetworkCreateOptions, runtimeCon
 	plugins = append(plugins, NewPortMapPlugin())
 	plugins = append(plugins, NewFirewallPlugin())
 	plugins = append(plugins, NewTuningPlugin())
-	// if we find the dnsname plugin or are rootless, we add configuration for it
-	// the rootless-cni-infra container has the dnsname plugin always installed
-	if (HasDNSNamePlugin(runtimeConfig.Network.CNIPluginDirs) || rootless.IsRootless()) && !options.DisableDNS {
+	// if we find the dnsname plugin we add configuration for it
+	if HasDNSNamePlugin(runtimeConfig.Network.CNIPluginDirs) && !options.DisableDNS {
 		if options.Internal {
 			logrus.Warnf("dnsname and --internal networks are incompatible.  dnsname plugin not configured for network %s", name)
 		} else {

libpod/networking_linux.go

@@ -4,7 +4,6 @@ package libpod
 
 import (
 	"bytes"
-	"context"
 	"crypto/rand"
 	"fmt"
 	"io"
@@ -29,7 +28,9 @@ import (
 	"github.com/containers/podman/v3/pkg/netns"
 	"github.com/containers/podman/v3/pkg/rootless"
 	"github.com/containers/podman/v3/pkg/rootlessport"
+	"github.com/containers/podman/v3/pkg/util"
 	"github.com/cri-o/ocicni/pkg/ocicni"
+	"github.com/opencontainers/selinux/go-selinux/label"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"github.com/vishvananda/netlink"
@@ -46,6 +47,9 @@ const (
 
 	// slirp4netnsMTU the default MTU override
 	slirp4netnsMTU = 65520
+
+	// rootlessCNINSName is the file name for the rootless network namespace bind mount
+	rootlessCNINSName = "rootless-cni-ns"
 )
 
 // Get an OCICNI network config
@@ -102,8 +106,222 @@ func (r *Runtime) getPodNetwork(id, name, nsPath string, networks []string, port
 	return ctrNetwork
 }
 
+type rootlessCNI struct {
+	ns  ns.NetNS
+	dir string
+}
+
+func (r *rootlessCNI) Do(toRun func() error) error {
+	err := r.ns.Do(func(_ ns.NetNS) error {
+		// before we can run the given function
+		// we have to setup all mounts correctly
+
+		// create a new mount namespace
+		// this should happen inside the netns thread
+		err := unix.Unshare(unix.CLONE_NEWNS)
+		if err != nil {
+			return errors.Wrapf(err, "cannot create a new mount namespace")
+		}
+
+		netNsDir, err := netns.GetNSRunDir()
+		if err != nil {
+			return errors.Wrap(err, "could not get network namespace directory")
+		}
+		newNetNsDir := filepath.Join(r.dir, netNsDir)
+		// mount the netns into the new run to keep them accessible
+		// otherwise cni setup will fail because it cannot access the netns files
+		err = unix.Mount(netNsDir, newNetNsDir, "none", unix.MS_BIND|unix.MS_SHARED|unix.MS_REC, "")
+		if err != nil {
+			return errors.Wrap(err, "failed to mount netns directory for rootless cni")
+		}
+
+		// also keep /run/systemd if it exists
+		// many files are symlinked into this dir, for example systemd-resolved links
+		// /etc/resolv.conf but the dnsname plugin needs access to this file
+		runSystemd := "/run/systemd"
+		_, err = os.Stat(runSystemd)
+		if err == nil {
+			newRunSystemd := filepath.Join(r.dir, runSystemd[1:])
+			err = unix.Mount(runSystemd, newRunSystemd, "none", unix.MS_BIND|unix.MS_REC, "")
+			if err != nil {
+				return errors.Wrap(err, "failed to mount /run/systemd directory for rootless cni")
+			}
+		}
+
+		// cni plugins need access to /var and /run
+		runDir := filepath.Join(r.dir, "run")
+		varDir := filepath.Join(r.dir, "var")
+		// make sure to mount var first
+		err = unix.Mount(varDir, "/var", "none", unix.MS_BIND, "")
+		if err != nil {
+			return errors.Wrap(err, "failed to mount /var for rootless cni")
+		}
+		// recursive mount to keep the netns mount
+		err = unix.Mount(runDir, "/run", "none", unix.MS_BIND|unix.MS_REC, "")
+		if err != nil {
+			return errors.Wrap(err, "failed to mount /run for rootless cni")
+		}
+
+		// run the given function in the correct namespace
+		err = toRun()
+		return err
+	})
+	return err
+}
+
+// getRootlessCNINetNs returns the rootless cni object. If create is set to true
+// the rootless cni namespace will be created if it does not exists already.
+func (r *Runtime) getRootlessCNINetNs(new bool) (*rootlessCNI, error) {
+	var rootlessCNINS *rootlessCNI
+	if rootless.IsRootless() {
+		runDir, err := util.GetRuntimeDir()
+		if err != nil {
+			return nil, err
+		}
+		cniDir := filepath.Join(runDir, "rootless-cni")
+
+		nsDir, err := netns.GetNSRunDir()
+		if err != nil {
+			return nil, err
+		}
+		path := filepath.Join(nsDir, rootlessCNINSName)
+		ns, err := ns.GetNS(path)
+		if err != nil {
+			if new {
+				// create a new namespace
+				logrus.Debug("creating rootless cni network namespace")
+				ns, err = netns.NewNSWithName(rootlessCNINSName)
+				if err != nil {
+					return nil, errors.Wrap(err, "error creating rootless cni network namespace")
+				}
+
+				// setup slirp4netns here
+				path := r.config.Engine.NetworkCmdPath
+				if path == "" {
+					var err error
+					path, err = exec.LookPath("slirp4netns")
+					if err != nil {
+						return nil, err
+					}
+				}
+
+				syncR, syncW, err := os.Pipe()
+				if err != nil {
+					return nil, errors.Wrapf(err, "failed to open pipe")
+				}
+				defer errorhandling.CloseQuiet(syncR)
+				defer errorhandling.CloseQuiet(syncW)
+
+				netOptions, err := parseSlirp4netnsNetworkOptions(r, nil)
+				if err != nil {
+					return nil, err
+				}
+				slirpFeatures, err := checkSlirpFlags(path)
+				if err != nil {
+					return nil, errors.Wrapf(err, "error checking slirp4netns binary %s: %q", path, err)
+				}
+				cmdArgs, err := createBasicSlirp4netnsCmdArgs(netOptions, slirpFeatures)
+				if err != nil {
+					return nil, err
+				}
+				// the slirp4netns arguments being passed are describes as follows:
+				// from the slirp4netns documentation: https://github.com/rootless-containers/slirp4netns
+				// -c, --configure Brings up the tap interface
+				// -e, --exit-fd=FD specify the FD for terminating slirp4netns
+				// -r, --ready-fd=FD specify the FD to write to when the initialization steps are finished
+				cmdArgs = append(cmdArgs, "-c", "-r", "3")
+				cmdArgs = append(cmdArgs, "--netns-type=path", ns.Path(), "tap0")
+
+				cmd := exec.Command(path, cmdArgs...)
+				logrus.Debugf("slirp4netns command: %s", strings.Join(cmd.Args, " "))
+				cmd.SysProcAttr = &syscall.SysProcAttr{
+					Setpgid: true,
+				}
+
+				// workaround for https://github.com/rootless-containers/slirp4netns/pull/153
+				if !netOptions.noPivotRoot && slirpFeatures.HasEnableSandbox {
+					cmd.SysProcAttr.Cloneflags = syscall.CLONE_NEWNS
+					cmd.SysProcAttr.Unshareflags = syscall.CLONE_NEWNS
+				}
+
+				// Leak one end of the pipe in slirp4netns
+				cmd.ExtraFiles = append(cmd.ExtraFiles, syncW)
+
+				logPath := filepath.Join(r.config.Engine.TmpDir, "slirp4netns-rootless-cni.log")
+				logFile, err := os.Create(logPath)
+				if err != nil {
+					return nil, errors.Wrapf(err, "failed to open slirp4netns log file %s", logPath)
+				}
+				defer logFile.Close()
+				// Unlink immediately the file so we won't need to worry about cleaning it up later.
+				// It is still accessible through the open fd logFile.
+				if err := os.Remove(logPath); err != nil {
+					return nil, errors.Wrapf(err, "delete file %s", logPath)
+				}
+				cmd.Stdout = logFile
+				cmd.Stderr = logFile
+				if err := cmd.Start(); err != nil {
+					return nil, errors.Wrapf(err, "failed to start slirp4netns process")
+				}
+				defer func() {
+					if err := cmd.Process.Release(); err != nil {
+						logrus.Errorf("unable to release command process: %q", err)
+					}
+				}()
+
+				if err := waitForSync(syncR, cmd, logFile, 1*time.Second); err != nil {
+					return nil, err
+				}
+
+				// create cni directories to store files
+				// they will be bind mounted to the correct location in a extra mount ns
+				err = os.MkdirAll(filepath.Join(cniDir, "var"), 0700)
+				if err != nil {
+					return nil, errors.Wrap(err, "could not create rootless-cni var directory")
+				}
+				runDir := filepath.Join(cniDir, "run")
+				err = os.MkdirAll(runDir, 0700)
+				if err != nil {
+					return nil, errors.Wrap(err, "could not create rootless-cni run directory")
+				}
+				// relabel the new run directory to the iptables /run label
+				// this is important, otherwise the iptables command will fail
+				err = label.Relabel(runDir, "system_u:object_r:iptables_var_run_t:s0", false)
+				if err != nil {
+					return nil, errors.Wrap(err, "could not create relabel rootless-cni run directory")
+				}
+				// create systemd run directory
+				err = os.MkdirAll(filepath.Join(runDir, "systemd"), 0700)
+				if err != nil {
+					return nil, errors.Wrap(err, "could not create rootless-cni systemd directory")
+				}
+				// create the directory for the netns files at the same location
+				// relative to the rootless-cni location
+				err = os.MkdirAll(filepath.Join(cniDir, nsDir), 0700)
+				if err != nil {
+					return nil, errors.Wrap(err, "could not create rootless-cni netns directory")
+				}
+			} else {
+				// return a error if we could not get the namespace and should no create one
+				return nil, errors.Wrap(err, "error getting rootless cni network namespace")
+			}
+		}
+
+		rootlessCNINS = &rootlessCNI{
+			ns:  ns,
+			dir: cniDir,
+		}
+	}
+	return rootlessCNINS, nil
+}
+
 // Create and configure a new network namespace for a container
 func (r *Runtime) configureNetNS(ctr *Container, ctrNS ns.NetNS) ([]*cnitypes.Result, error) {
+	rootlessCNINS, err := r.getRootlessCNINetNs(true)
+	if err != nil {
+		return nil, err
+	}
+
 	var requestedIP net.IP
 	if ctr.requestedIP != nil {
 		requestedIP = ctr.requestedIP
@@ -147,9 +365,11 @@ func (r *Runtime) configureNetNS(ctr *Container, ctrNS ns.NetNS) ([]*cnitypes.Re
 		podNetwork.Aliases = aliases
 	}
 
-	results, err := r.netPlugin.SetUpPod(podNetwork)
+	var results []ocicni.NetResult
+	setUpPod := func() error {
+		results, err = r.netPlugin.SetUpPod(podNetwork)
 		if err != nil {
-		return nil, errors.Wrapf(err, "error configuring network namespace for container %s", ctr.ID())
+			return errors.Wrapf(err, "error configuring network namespace for container %s", ctr.ID())
 		}
 		defer func() {
 			if err != nil {
@@ -158,6 +378,18 @@ func (r *Runtime) configureNetNS(ctr *Container, ctrNS ns.NetNS) ([]*cnitypes.Re
 				}
 			}
 		}()
+		return nil
+	}
+	// rootlessCNINS is nil if we are root
+	if rootlessCNINS != nil {
+		// execute the cni setup in the rootless net ns
+		err = rootlessCNINS.Do(setUpPod)
+	} else {
+		err = setUpPod()
+	}
+	if err != nil {
+		return nil, err
+	}
 
 	networkStatus := make([]*cnitypes.Result, 0)
 	for idx, r := range results {
@@ -192,7 +424,7 @@ func (r *Runtime) createNetNS(ctr *Container) (n ns.NetNS, q []*cnitypes.Result,
 	logrus.Debugf("Made network namespace at %s for container %s", ctrNS.Path(), ctr.ID())
 
 	networkStatus := []*cnitypes.Result{}
-	if !rootless.IsRootless() && !ctr.config.NetMode.IsSlirp4netns() {
+	if !ctr.config.NetMode.IsSlirp4netns() {
 		networkStatus, err = r.configureNetNS(ctr, ctrNS)
 	}
 	return ctrNS, networkStatus, err
@@ -221,6 +453,17 @@ type slirp4netnsCmd struct {
 	Args    slirp4netnsCmdArg `json:"arguments"`
 }
 
+type slirp4netnsNetworkOptions struct {
+	cidr                string
+	disableHostLoopback bool
+	enableIPv6          bool
+	isSlirpHostForward  bool
+	noPivotRoot         bool
+	mtu                 int
+	outboundAddr        string
+	outboundAddr6       string
+}
+
 func checkSlirpFlags(path string) (*slirpFeatures, error) {
 	cmd := exec.Command(path, "--help")
 	out, err := cmd.CombinedOutput()
@@ -256,11 +499,137 @@ func (r *Runtime) setupRootlessNetNS(ctr *Container) error {
 	return nil
 }
 
+func parseSlirp4netnsNetworkOptions(r *Runtime, extraOptions []string) (*slirp4netnsNetworkOptions, error) {
+	slirpOptions := append(r.config.Engine.NetworkCmdOptions, extraOptions...)
+	slirp4netnsOpts := &slirp4netnsNetworkOptions{
+		// overwrite defaults
+		disableHostLoopback: true,
+		mtu:                 slirp4netnsMTU,
+		noPivotRoot:         r.config.Engine.NoPivotRoot,
+	}
+	for _, o := range slirpOptions {
+		parts := strings.SplitN(o, "=", 2)
+		if len(parts) < 2 {
+			return nil, errors.Errorf("unknown option for slirp4netns: %q", o)
+		}
+		option, value := parts[0], parts[1]
+		switch option {
+		case "cidr":
+			ipv4, _, err := net.ParseCIDR(value)
+			if err != nil || ipv4.To4() == nil {
+				return nil, errors.Errorf("invalid cidr %q", value)
+			}
+			slirp4netnsOpts.cidr = value
+		case "port_handler":
+			switch value {
+			case "slirp4netns":
+				slirp4netnsOpts.isSlirpHostForward = true
+			case "rootlesskit":
+				slirp4netnsOpts.isSlirpHostForward = false
+			default:
+				return nil, errors.Errorf("unknown port_handler for slirp4netns: %q", value)
+			}
+		case "allow_host_loopback":
+			switch value {
+			case "true":
+				slirp4netnsOpts.disableHostLoopback = false
+			case "false":
+				slirp4netnsOpts.disableHostLoopback = true
+			default:
+				return nil, errors.Errorf("invalid value of allow_host_loopback for slirp4netns: %q", value)
+			}
+		case "enable_ipv6":
+			switch value {
+			case "true":
+				slirp4netnsOpts.enableIPv6 = true
+			case "false":
+				slirp4netnsOpts.enableIPv6 = false
+			default:
+				return nil, errors.Errorf("invalid value of enable_ipv6 for slirp4netns: %q", value)
+			}
+		case "outbound_addr":
+			ipv4 := net.ParseIP(value)
+			if ipv4 == nil || ipv4.To4() == nil {
+				_, err := net.InterfaceByName(value)
+				if err != nil {
+					return nil, errors.Errorf("invalid outbound_addr %q", value)
+				}
+			}
+			slirp4netnsOpts.outboundAddr = value
+		case "outbound_addr6":
+			ipv6 := net.ParseIP(value)
+			if ipv6 == nil || ipv6.To4() != nil {
+				_, err := net.InterfaceByName(value)
+				if err != nil {
+					return nil, errors.Errorf("invalid outbound_addr6: %q", value)
+				}
+			}
+			slirp4netnsOpts.outboundAddr6 = value
+		case "mtu":
+			var err error
+			slirp4netnsOpts.mtu, err = strconv.Atoi(value)
+			if slirp4netnsOpts.mtu < 68 || err != nil {
+				return nil, errors.Errorf("invalid mtu %q", value)
+			}
+		default:
+			return nil, errors.Errorf("unknown option for slirp4netns: %q", o)
+		}
+	}
+	return slirp4netnsOpts, nil
+}
+
+func createBasicSlirp4netnsCmdArgs(options *slirp4netnsNetworkOptions, features *slirpFeatures) ([]string, error) {
+	cmdArgs := []string{}
+	if options.disableHostLoopback && features.HasDisableHostLoopback {
+		cmdArgs = append(cmdArgs, "--disable-host-loopback")
+	}
+	if options.mtu > -1 && features.HasMTU {
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--mtu=%d", options.mtu))
+	}
+	if !options.noPivotRoot && features.HasEnableSandbox {
+		cmdArgs = append(cmdArgs, "--enable-sandbox")
+	}
+	if features.HasEnableSeccomp {
+		cmdArgs = append(cmdArgs, "--enable-seccomp")
+	}
+
+	if options.cidr != "" {
+		if !features.HasCIDR {
+			return nil, errors.Errorf("cidr not supported")
+		}
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--cidr=%s", options.cidr))
+	}
+
+	if options.enableIPv6 {
+		if !features.HasIPv6 {
+			return nil, errors.Errorf("enable_ipv6 not supported")
+		}
+		cmdArgs = append(cmdArgs, "--enable-ipv6")
+	}
+
+	if options.outboundAddr != "" {
+		if !features.HasOutboundAddr {
+			return nil, errors.Errorf("outbound_addr not supported")
+		}
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--outbound-addr=%s", options.outboundAddr))
+	}
+
+	if options.outboundAddr6 != "" {
+		if !features.HasOutboundAddr || !features.HasIPv6 {
+			return nil, errors.Errorf("outbound_addr6 not supported")
+		}
+		if !options.enableIPv6 {
+			return nil, errors.Errorf("enable_ipv6=true is required for outbound_addr6")
+		}
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--outbound-addr6=%s", options.outboundAddr6))
+	}
+
+	return cmdArgs, nil
+}
+
 // setupSlirp4netns can be called in rootful as well as in rootless
 func (r *Runtime) setupSlirp4netns(ctr *Container) error {
 	path := r.config.Engine.NetworkCmdPath
-	slirpOptions := r.config.Engine.NetworkCmdOptions
-	noPivotRoot := r.config.Engine.NoPivotRoot
 	if path == "" {
 		var err error
 		path, err = exec.LookPath("slirp4netns")
@@ -280,139 +649,21 @@ func (r *Runtime) setupSlirp4netns(ctr *Container) error {
 	havePortMapping := len(ctr.Config().PortMappings) > 0
 	logPath := filepath.Join(ctr.runtime.config.Engine.TmpDir, fmt.Sprintf("slirp4netns-%s.log", ctr.config.ID))
 
-	cidr := ""
-	isSlirpHostForward := false
-	disableHostLoopback := true
-	enableIPv6 := false
-	outboundAddr := ""
-	outboundAddr6 := ""
-	mtu := slirp4netnsMTU
-
+	ctrNetworkSlipOpts := []string{}
 	if ctr.config.NetworkOptions != nil {
-		slirpOptions = append(slirpOptions, ctr.config.NetworkOptions["slirp4netns"]...)
+		ctrNetworkSlipOpts = append(ctrNetworkSlipOpts, ctr.config.NetworkOptions["slirp4netns"]...)
 	}
-
-	for _, o := range slirpOptions {
-		parts := strings.SplitN(o, "=", 2)
-		if len(parts) < 2 {
-			return errors.Errorf("unknown option for slirp4netns: %q", o)
-		}
-		option, value := parts[0], parts[1]
-		switch option {
-		case "cidr":
-			ipv4, _, err := net.ParseCIDR(value)
-			if err != nil || ipv4.To4() == nil {
-				return errors.Errorf("invalid cidr %q", value)
-			}
-			cidr = value
-		case "port_handler":
-			switch value {
-			case "slirp4netns":
-				isSlirpHostForward = true
-			case "rootlesskit":
-				isSlirpHostForward = false
-			default:
-				return errors.Errorf("unknown port_handler for slirp4netns: %q", value)
-			}
-		case "allow_host_loopback":
-			switch value {
-			case "true":
-				disableHostLoopback = false
-			case "false":
-				disableHostLoopback = true
-			default:
-				return errors.Errorf("invalid value of allow_host_loopback for slirp4netns: %q", value)
-			}
-		case "enable_ipv6":
-			switch value {
-			case "true":
-				enableIPv6 = true
-			case "false":
-				enableIPv6 = false
-			default:
-				return errors.Errorf("invalid value of enable_ipv6 for slirp4netns: %q", value)
-			}
-		case "outbound_addr":
-			ipv4 := net.ParseIP(value)
-			if ipv4 == nil || ipv4.To4() == nil {
-				_, err := net.InterfaceByName(value)
+	netOptions, err := parseSlirp4netnsNetworkOptions(r, ctrNetworkSlipOpts)
 	if err != nil {
-					return errors.Errorf("invalid outbound_addr %q", value)
+		return err
 	}
-			}
-			outboundAddr = value
-		case "outbound_addr6":
-			ipv6 := net.ParseIP(value)
-			if ipv6 == nil || ipv6.To4() != nil {
-				_, err := net.InterfaceByName(value)
-				if err != nil {
-					return errors.Errorf("invalid outbound_addr6: %q", value)
-				}
-			}
-			outboundAddr6 = value
-		case "mtu":
-			mtu, err = strconv.Atoi(value)
-			if mtu < 68 || err != nil {
-				return errors.Errorf("invalid mtu %q", value)
-			}
-		default:
-			return errors.Errorf("unknown option for slirp4netns: %q", o)
-		}
-	}
-
-	cmdArgs := []string{}
 	slirpFeatures, err := checkSlirpFlags(path)
 	if err != nil {
 		return errors.Wrapf(err, "error checking slirp4netns binary %s: %q", path, err)
 	}
-	if disableHostLoopback && slirpFeatures.HasDisableHostLoopback {
-		cmdArgs = append(cmdArgs, "--disable-host-loopback")
-	}
-	if mtu > -1 && slirpFeatures.HasMTU {
-		cmdArgs = append(cmdArgs, fmt.Sprintf("--mtu=%d", mtu))
-	}
-	if !noPivotRoot && slirpFeatures.HasEnableSandbox {
-		cmdArgs = append(cmdArgs, "--enable-sandbox")
-	}
-	if slirpFeatures.HasEnableSeccomp {
-		cmdArgs = append(cmdArgs, "--enable-seccomp")
-	}
-
-	if cidr != "" {
-		if !slirpFeatures.HasCIDR {
-			return errors.Errorf("cidr not supported")
-		}
-		cmdArgs = append(cmdArgs, fmt.Sprintf("--cidr=%s", cidr))
-	}
-
-	if enableIPv6 {
-		if !slirpFeatures.HasIPv6 {
-			return errors.Errorf("enable_ipv6 not supported")
-		}
-		cmdArgs = append(cmdArgs, "--enable-ipv6")
-	}
-
-	if outboundAddr != "" {
-		if !slirpFeatures.HasOutboundAddr {
-			return errors.Errorf("outbound_addr not supported")
-		}
-		cmdArgs = append(cmdArgs, fmt.Sprintf("--outbound-addr=%s", outboundAddr))
-	}
-
-	if outboundAddr6 != "" {
-		if !slirpFeatures.HasOutboundAddr || !slirpFeatures.HasIPv6 {
-			return errors.Errorf("outbound_addr6 not supported")
-		}
-		if !enableIPv6 {
-			return errors.Errorf("enable_ipv6=true is required for outbound_addr6")
-		}
-		cmdArgs = append(cmdArgs, fmt.Sprintf("--outbound-addr6=%s", outboundAddr6))
-	}
-
-	var apiSocket string
-	if havePortMapping && isSlirpHostForward {
-		apiSocket = filepath.Join(ctr.runtime.config.Engine.TmpDir, fmt.Sprintf("%s.net", ctr.config.ID))
-		cmdArgs = append(cmdArgs, "--api-socket", apiSocket)
+	cmdArgs, err := createBasicSlirp4netnsCmdArgs(netOptions, slirpFeatures)
+	if err != nil {
+		return err
 	}
 
 	// the slirp4netns arguments being passed are describes as follows:
@@ -421,6 +672,12 @@ func (r *Runtime) setupSlirp4netns(ctr *Container) error {
 	// -e, --exit-fd=FD specify the FD for terminating slirp4netns
 	// -r, --ready-fd=FD specify the FD to write to when the initialization steps are finished
 	cmdArgs = append(cmdArgs, "-c", "-e", "3", "-r", "4")
+
+	var apiSocket string
+	if havePortMapping && netOptions.isSlirpHostForward {
+		apiSocket = filepath.Join(ctr.runtime.config.Engine.TmpDir, fmt.Sprintf("%s.net", ctr.config.ID))
+		cmdArgs = append(cmdArgs, "--api-socket", apiSocket)
+	}
 	netnsPath := ""
 	if !ctr.config.PostConfigureNetNS {
 		ctr.rootlessSlirpSyncR, ctr.rootlessSlirpSyncW, err = os.Pipe()
@@ -444,7 +701,7 @@ func (r *Runtime) setupSlirp4netns(ctr *Container) error {
 	}
 
 	// workaround for https://github.com/rootless-containers/slirp4netns/pull/153
-	if !noPivotRoot && slirpFeatures.HasEnableSandbox {
+	if !netOptions.noPivotRoot && slirpFeatures.HasEnableSandbox {
 		cmd.SysProcAttr.Cloneflags = syscall.CLONE_NEWNS
 		cmd.SysProcAttr.Unshareflags = syscall.CLONE_NEWNS
 	}
@@ -478,7 +735,7 @@ func (r *Runtime) setupSlirp4netns(ctr *Container) error {
 	}
 
 	if havePortMapping {
-		if isSlirpHostForward {
+		if netOptions.isSlirpHostForward {
 			return r.setupRootlessPortMappingViaSlirp(ctr, cmd, apiSocket)
 		}
 		return r.setupRootlessPortMappingViaRLK(ctr, netnsPath)
@@ -789,8 +1046,11 @@ func (r *Runtime) teardownCNI(ctr *Container) error {
 		return err
 	}
 
-	// rootless containers do not use the CNI plugin directly
-	if !rootless.IsRootless() && !ctr.config.NetMode.IsSlirp4netns() && len(networks) > 0 {
+	if !ctr.config.NetMode.IsSlirp4netns() && len(networks) > 0 {
+		rootlessCNINS, err := r.getRootlessCNINetNs(false)
+		if err != nil {
+			return err
+		}
 		var requestedIP net.IP
 		if ctr.requestedIP != nil {
 			requestedIP = ctr.requestedIP
@@ -811,9 +1071,21 @@ func (r *Runtime) teardownCNI(ctr *Container) error {
 
 		podNetwork := r.getPodNetwork(ctr.ID(), ctr.Name(), ctr.state.NetNS.Path(), networks, ctr.config.PortMappings, requestedIP, requestedMAC, ctr.state.NetInterfaceDescriptions)
 
+		tearDownPod := func() error {
 			if err := r.netPlugin.TearDownPod(podNetwork); err != nil {
 				return errors.Wrapf(err, "error tearing down CNI namespace configuration for container %s", ctr.ID())
 			}
+			return nil
+		}
+
+		// rootlessCNINS is nil if we are root
+		if rootlessCNINS != nil {
+			// execute the cni setup in the rootless net ns
+			err = rootlessCNINS.Do(tearDownPod)
+		} else {
+			err = tearDownPod()
+		}
+		return err
 	}
 	return nil
 }
@@ -824,18 +1096,6 @@ func (r *Runtime) teardownNetNS(ctr *Container) error {
 		return err
 	}
 
-	networks, _, err := ctr.networks()
-	if err != nil {
-		return err
-	}
-
-	// CNI-in-slirp4netns
-	if rootless.IsRootless() && len(networks) != 0 {
-		if err := DeallocRootlessCNI(context.Background(), ctr); err != nil {
-			return errors.Wrapf(err, "error tearing down CNI-in-slirp4netns for container %s", ctr.ID())
-		}
-	}
-
 	// First unmount the namespace
 	if err := netns.UnmountNS(ctr.state.NetNS); err != nil {
 		return errors.Wrapf(err, "error unmounting network namespace for container %s", ctr.ID())

libpod/runtime.go

@@ -436,13 +436,11 @@ func makeRuntime(ctx context.Context, runtime *Runtime) (retErr error) {
 	}
 
 	// Set up the CNI net plugin
-	if !rootless.IsRootless() {
 	netPlugin, err := ocicni.InitCNI(runtime.config.Network.DefaultNetwork, runtime.config.Network.NetworkConfigDir, runtime.config.Network.CNIPluginDirs...)
 	if err != nil {
 		return errors.Wrapf(err, "error configuring CNI network plugin")
 	}
 	runtime.netPlugin = netPlugin
-	}
 
 	// We now need to see if the system has restarted
 	// We check for the presence of a file in our tmp directory to verify this

pkg/netns/netns_linux.go

@@ -35,9 +35,9 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-// get NSRunDir returns the dir of where to create the netNS. When running
+// GetNSRunDir returns the dir of where to create the netNS. When running
 // rootless, it needs to be at a location writable by user.
-func getNSRunDir() (string, error) {
+func GetNSRunDir() (string, error) {
 	if rootless.IsRootless() {
 		rootlessDir, err := util.GetRuntimeDir()
 		if err != nil {
@@ -51,16 +51,22 @@ func getNSRunDir() (string, error) {
 // NewNS creates a new persistent (bind-mounted) network namespace and returns
 // an object representing that namespace, without switching to it.
 func NewNS() (ns.NetNS, error) {
-	nsRunDir, err := getNSRunDir()
-	if err != nil {
-		return nil, err
-	}
-
 	b := make([]byte, 16)
-	_, err = rand.Reader.Read(b)
+	_, err := rand.Reader.Read(b)
 	if err != nil {
 		return nil, fmt.Errorf("failed to generate random netns name: %v", err)
 	}
+	nsName := fmt.Sprintf("cni-%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
+	return NewNSWithName(nsName)
+}
+
+// NewNSWithName creates a new persistent (bind-mounted) network namespace and returns
+// an object representing that namespace, without switching to it.
+func NewNSWithName(name string) (ns.NetNS, error) {
+	nsRunDir, err := GetNSRunDir()
+	if err != nil {
+		return nil, err
+	}
 
 	// Create the directory for mounting network namespaces
 	// This needs to be a shared mountpoint in case it is mounted in to
@@ -93,10 +99,8 @@ func NewNS() (ns.NetNS, error) {
 		}
 	}
 
-	nsName := fmt.Sprintf("cni-%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
-
 	// create an empty file at the mount point
-	nsPath := path.Join(nsRunDir, nsName)
+	nsPath := path.Join(nsRunDir, name)
 	mountPointFd, err := os.Create(nsPath)
 	if err != nil {
 		return nil, err
@@ -177,7 +181,7 @@ func NewNS() (ns.NetNS, error) {
 
 // UnmountNS unmounts the NS held by the netns object
 func UnmountNS(ns ns.NetNS) error {
-	nsRunDir, err := getNSRunDir()
+	nsRunDir, err := GetNSRunDir()
 	if err != nil {
 		return err
 	}

test/system/500-networking.bats

@@ -143,13 +143,6 @@ load helpers
 
     run_podman network rm $mynetname
     run_podman 1 network rm $mynetname
-
-    # rootless CNI leaves behind an image pulled by SHA, hence with no tag.
-    # Remove it if present; we can only remove it by ID.
-    run_podman images --format '{{.Id}}' rootless-cni-infra
-    if [ -n "$output" ]; then
-        run_podman rmi $output
-    fi
 }
 
 @test "podman network reload" {