use libnetwork/slirp4netns from c/common

Most of the code moved there so if from there and remove it here.

Some extra changes are required here. This is a bit of a mess. The pipe
handling makes this a bit more difficult.

[NO NEW TESTS NEEDED] This is just a rework, existing tests must pass.

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

vendor/github.com/containers/common/libnetwork/slirp4netns/const.go

@@ -0,0 +1,12 @@
+package slirp4netns
+
+const (
+	ipv6ConfDefaultAcceptDadSysctl = "/proc/sys/net/ipv6/conf/default/accept_dad"
+	BinaryName                     = "slirp4netns"
+
+	// defaultMTU the default MTU override
+	defaultMTU = 65520
+
+	// default slirp4ns subnet
+	defaultSubnet = "10.0.2.0/24"
+)

vendor/github.com/containers/common/libnetwork/slirp4netns/slirp4netns.go

@@ -0,0 +1,750 @@
+//go:build linux
+// +build linux
+
+package slirp4netns
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/containernetworking/plugins/pkg/ns"
+	"github.com/containers/common/libnetwork/types"
+	"github.com/containers/common/pkg/config"
+	"github.com/containers/common/pkg/rootlessport"
+	"github.com/containers/common/pkg/servicereaper"
+	"github.com/containers/common/pkg/util"
+	"github.com/sirupsen/logrus"
+)
+
+type slirpFeatures struct {
+	HasDisableHostLoopback bool
+	HasMTU                 bool
+	HasEnableSandbox       bool
+	HasEnableSeccomp       bool
+	HasCIDR                bool
+	HasOutboundAddr        bool
+	HasIPv6                bool
+}
+
+type slirp4netnsCmdArg struct {
+	Proto     string `json:"proto,omitempty"`
+	HostAddr  string `json:"host_addr"`
+	HostPort  uint16 `json:"host_port"`
+	GuestAddr string `json:"guest_addr"`
+	GuestPort uint16 `json:"guest_port"`
+}
+
+type slirp4netnsCmd struct {
+	Execute string            `json:"execute"`
+	Args    slirp4netnsCmdArg `json:"arguments"`
+}
+
+type networkOptions struct {
+	cidr                string
+	disableHostLoopback bool
+	enableIPv6          bool
+	isSlirpHostForward  bool
+	noPivotRoot         bool
+	mtu                 int
+	outboundAddr        string
+	outboundAddr6       string
+}
+
+type SetupOptions struct {
+	// Config used to get slip4netns path and other default options
+	Config *config.Config
+	// ContainerID is the ID of the container
+	ContainerID string
+	// Netns path to the netns
+	Netns string
+	// ContainerPID is the pid of container process
+	ContainerPID int
+	// Ports the should be forwarded
+	Ports []types.PortMapping
+	// ExtraOptions for slirp4netns that were set on the cli
+	ExtraOptions []string
+	// Slirp4netnsExitPipeR pipe used to exit the slirp4netns process.
+	// This is must be the reading end, the writer must be kept open until you want the
+	// process to exit. For podman, conmon will hold the pipe open.
+	// It can be set to nil in which case we do not use the pipe exit and the caller
+	// must use the returned pid to kill the process after it is done.
+	Slirp4netnsExitPipeR *os.File
+	// RootlessPortSyncPipe pipe used to exit the rootlessport process.
+	// Same as Slirp4netnsExitPipeR, except this is only used when ports are given.
+	RootlessPortExitPipeR *os.File
+}
+
+// SetupResult return type from Setup()
+type SetupResult struct {
+	// Pid of the created slirp4netns process
+	Pid int
+	// Subnet which is used by slirp4netns
+	Subnet *net.IPNet
+	// IPv6 whenever Ipv6 is enabled in slirp4netns
+	IPv6 bool
+}
+
+type logrusDebugWriter struct {
+	prefix string
+}
+
+func (w *logrusDebugWriter) Write(p []byte) (int, error) {
+	logrus.Debugf("%s%s", w.prefix, string(p))
+	return len(p), nil
+}
+
+func checkSlirpFlags(path string) (*slirpFeatures, error) {
+	cmd := exec.Command(path, "--help")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return nil, fmt.Errorf("slirp4netns %q: %w", out, err)
+	}
+	return &slirpFeatures{
+		HasDisableHostLoopback: strings.Contains(string(out), "--disable-host-loopback"),
+		HasMTU:                 strings.Contains(string(out), "--mtu"),
+		HasEnableSandbox:       strings.Contains(string(out), "--enable-sandbox"),
+		HasEnableSeccomp:       strings.Contains(string(out), "--enable-seccomp"),
+		HasCIDR:                strings.Contains(string(out), "--cidr"),
+		HasOutboundAddr:        strings.Contains(string(out), "--outbound-addr"),
+		HasIPv6:                strings.Contains(string(out), "--enable-ipv6"),
+	}, nil
+}
+
+func parseNetworkOptions(config *config.Config, extraOptions []string) (*networkOptions, error) {
+	options := make([]string, 0, len(config.Engine.NetworkCmdOptions)+len(extraOptions))
+	options = append(options, config.Engine.NetworkCmdOptions...)
+	options = append(options, extraOptions...)
+	opts := &networkOptions{
+		// overwrite defaults
+		disableHostLoopback: true,
+		mtu:                 defaultMTU,
+		noPivotRoot:         config.Engine.NoPivotRoot,
+		enableIPv6:          true,
+	}
+	for _, o := range options {
+		parts := strings.SplitN(o, "=", 2)
+		if len(parts) < 2 {
+			return nil, fmt.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, fmt.Errorf("invalid cidr %q", value)
+			}
+			opts.cidr = value
+		case "port_handler":
+			switch value {
+			case "slirp4netns":
+				opts.isSlirpHostForward = true
+			case "rootlesskit":
+				opts.isSlirpHostForward = false
+			default:
+				return nil, fmt.Errorf("unknown port_handler for slirp4netns: %q", value)
+			}
+		case "allow_host_loopback":
+			switch value {
+			case "true":
+				opts.disableHostLoopback = false
+			case "false":
+				opts.disableHostLoopback = true
+			default:
+				return nil, fmt.Errorf("invalid value of allow_host_loopback for slirp4netns: %q", value)
+			}
+		case "enable_ipv6":
+			switch value {
+			case "true":
+				opts.enableIPv6 = true
+			case "false":
+				opts.enableIPv6 = false
+			default:
+				return nil, fmt.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, fmt.Errorf("invalid outbound_addr %q", value)
+				}
+			}
+			opts.outboundAddr = value
+		case "outbound_addr6":
+			ipv6 := net.ParseIP(value)
+			if ipv6 == nil || ipv6.To4() != nil {
+				_, err := net.InterfaceByName(value)
+				if err != nil {
+					return nil, fmt.Errorf("invalid outbound_addr6: %q", value)
+				}
+			}
+			opts.outboundAddr6 = value
+		case "mtu":
+			var err error
+			opts.mtu, err = strconv.Atoi(value)
+			if opts.mtu < 68 || err != nil {
+				return nil, fmt.Errorf("invalid mtu %q", value)
+			}
+		default:
+			return nil, fmt.Errorf("unknown option for slirp4netns: %q", o)
+		}
+	}
+	return opts, nil
+}
+
+func createBasicSlirpCmdArgs(options *networkOptions, 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, fmt.Errorf("cidr not supported")
+		}
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--cidr=%s", options.cidr))
+	}
+
+	if options.enableIPv6 {
+		if !features.HasIPv6 {
+			return nil, fmt.Errorf("enable_ipv6 not supported")
+		}
+		cmdArgs = append(cmdArgs, "--enable-ipv6")
+	}
+
+	if options.outboundAddr != "" {
+		if !features.HasOutboundAddr {
+			return nil, fmt.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, fmt.Errorf("outbound_addr6 not supported")
+		}
+		if !options.enableIPv6 {
+			return nil, fmt.Errorf("enable_ipv6=true is required for outbound_addr6")
+		}
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--outbound-addr6=%s", options.outboundAddr6))
+	}
+
+	return cmdArgs, nil
+}
+
+// Setup can be called in rootful as well as in rootless.
+// Spawns the slirp4netns process and setup port forwarding if ports are given.
+func Setup(opts *SetupOptions) (*SetupResult, error) {
+	path := opts.Config.Engine.NetworkCmdPath
+	if path == "" {
+		var err error
+		path, err = opts.Config.FindHelperBinary(BinaryName, true)
+		if err != nil {
+			return nil, fmt.Errorf("could not find slirp4netns, the network namespace can't be configured: %w", err)
+		}
+	}
+
+	syncR, syncW, err := os.Pipe()
+	if err != nil {
+		return nil, fmt.Errorf("failed to open pipe: %w", err)
+	}
+	defer closeQuiet(syncR)
+	defer closeQuiet(syncW)
+
+	havePortMapping := len(opts.Ports) > 0
+	logPath := filepath.Join(opts.Config.Engine.TmpDir, fmt.Sprintf("slirp4netns-%s.log", opts.ContainerID))
+
+	netOptions, err := parseNetworkOptions(opts.Config, opts.ExtraOptions)
+	if err != nil {
+		return nil, err
+	}
+	slirpFeatures, err := checkSlirpFlags(path)
+	if err != nil {
+		return nil, fmt.Errorf("checking slirp4netns binary %s: %q: %w", path, err, err)
+	}
+	cmdArgs, err := createBasicSlirpCmdArgs(netOptions, slirpFeatures)
+	if err != nil {
+		return nil, err
+	}
+
+	// the slirp4netns arguments being passed are described 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")
+	if opts.Slirp4netnsExitPipeR != nil {
+		cmdArgs = append(cmdArgs, "-e", "4")
+	}
+
+	var apiSocket string
+	if havePortMapping && netOptions.isSlirpHostForward {
+		apiSocket = filepath.Join(opts.Config.Engine.TmpDir, fmt.Sprintf("%s.net", opts.ContainerID))
+		cmdArgs = append(cmdArgs, "--api-socket", apiSocket)
+	}
+
+	cmdArgs = append(cmdArgs, "--netns-type=path", opts.Netns, "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, the other will be sent to conmon
+	cmd.ExtraFiles = append(cmd.ExtraFiles, syncW)
+	if opts.Slirp4netnsExitPipeR != nil {
+		cmd.ExtraFiles = append(cmd.ExtraFiles, opts.Slirp4netnsExitPipeR)
+	}
+
+	logFile, err := os.Create(logPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open slirp4netns log file %s: %w", logPath, err)
+	}
+	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, fmt.Errorf("delete file %s: %w", logPath, err)
+	}
+	cmd.Stdout = logFile
+	cmd.Stderr = logFile
+
+	var slirpReadyWg, netnsReadyWg *sync.WaitGroup
+	if netOptions.enableIPv6 {
+		// use two wait groups to make sure we set the sysctl before
+		// starting slirp and reset it only after slirp is ready
+		slirpReadyWg = &sync.WaitGroup{}
+		netnsReadyWg = &sync.WaitGroup{}
+		slirpReadyWg.Add(1)
+		netnsReadyWg.Add(1)
+
+		go func() {
+			err := ns.WithNetNSPath(opts.Netns, func(_ ns.NetNS) error {
+				// Duplicate Address Detection slows the ipv6 setup down for 1-2 seconds.
+				// Since slirp4netns is run in its own namespace and not directly routed
+				// we can skip this to make the ipv6 address immediately available.
+				// We change the default to make sure the slirp tap interface gets the
+				// correct value assigned so DAD is disabled for it
+				// Also make sure to change this value back to the original after slirp4netns
+				// is ready in case users rely on this sysctl.
+				orgValue, err := os.ReadFile(ipv6ConfDefaultAcceptDadSysctl)
+				if err != nil {
+					netnsReadyWg.Done()
+					// on ipv6 disabled systems the sysctl does not exist
+					// so we should not error
+					if errors.Is(err, os.ErrNotExist) {
+						return nil
+					}
+					return err
+				}
+				err = os.WriteFile(ipv6ConfDefaultAcceptDadSysctl, []byte("0"), 0o644)
+				netnsReadyWg.Done()
+				if err != nil {
+					return err
+				}
+
+				// wait until slirp4nets is ready before resetting this value
+				slirpReadyWg.Wait()
+				return os.WriteFile(ipv6ConfDefaultAcceptDadSysctl, orgValue, 0o644)
+			})
+			if err != nil {
+				logrus.Warnf("failed to set net.ipv6.conf.default.accept_dad sysctl: %v", err)
+			}
+		}()
+
+		// wait until we set the sysctl
+		netnsReadyWg.Wait()
+	}
+
+	if err := cmd.Start(); err != nil {
+		if netOptions.enableIPv6 {
+			slirpReadyWg.Done()
+		}
+		return nil, fmt.Errorf("failed to start slirp4netns process: %w", err)
+	}
+	defer func() {
+		servicereaper.AddPID(cmd.Process.Pid)
+		if err := cmd.Process.Release(); err != nil {
+			logrus.Errorf("Unable to release command process: %q", err)
+		}
+	}()
+
+	err = waitForSync(syncR, cmd, logFile, 1*time.Second)
+	if netOptions.enableIPv6 {
+		slirpReadyWg.Done()
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	// Set a default slirp subnet. Parsing a string with the net helper is easier than building the struct myself
+	_, slirpSubnet, _ := net.ParseCIDR(defaultSubnet)
+
+	// Set slirp4netnsSubnet addresses now that we are pretty sure the command executed
+	if netOptions.cidr != "" {
+		ipv4, ipv4network, err := net.ParseCIDR(netOptions.cidr)
+		if err != nil || ipv4.To4() == nil {
+			return nil, fmt.Errorf("invalid cidr %q", netOptions.cidr)
+		}
+		slirpSubnet = ipv4network
+	}
+
+	if havePortMapping {
+		if netOptions.isSlirpHostForward {
+			err = setupRootlessPortMappingViaSlirp(opts.Ports, cmd, apiSocket)
+		} else {
+			err = SetupRootlessPortMappingViaRLK(opts, slirpSubnet, nil)
+		}
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return &SetupResult{
+		Pid:    cmd.Process.Pid,
+		Subnet: slirpSubnet,
+		IPv6:   netOptions.enableIPv6,
+	}, nil
+}
+
+// Get expected slirp ipv4 address based on subnet. If subnet is null use default subnet
+// Reference: https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md#description
+func GetIP(subnet *net.IPNet) (*net.IP, error) {
+	_, slirpSubnet, _ := net.ParseCIDR(defaultSubnet)
+	if subnet != nil {
+		slirpSubnet = subnet
+	}
+	expectedIP, err := addToIP(slirpSubnet, uint32(100))
+	if err != nil {
+		return nil, fmt.Errorf("calculating expected ip for slirp4netns: %w", err)
+	}
+	return expectedIP, nil
+}
+
+// Get expected slirp Gateway ipv4 address based on subnet
+// Reference: https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md#description
+func GetGateway(subnet *net.IPNet) (*net.IP, error) {
+	_, slirpSubnet, _ := net.ParseCIDR(defaultSubnet)
+	if subnet != nil {
+		slirpSubnet = subnet
+	}
+	expectedGatewayIP, err := addToIP(slirpSubnet, uint32(2))
+	if err != nil {
+		return nil, fmt.Errorf("calculating expected gateway ip for slirp4netns: %w", err)
+	}
+	return expectedGatewayIP, nil
+}
+
+// Get expected slirp DNS ipv4 address based on subnet
+// Reference: https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md#description
+func GetDNS(subnet *net.IPNet) (*net.IP, error) {
+	_, slirpSubnet, _ := net.ParseCIDR(defaultSubnet)
+	if subnet != nil {
+		slirpSubnet = subnet
+	}
+	expectedDNSIP, err := addToIP(slirpSubnet, uint32(3))
+	if err != nil {
+		return nil, fmt.Errorf("calculating expected dns ip for slirp4netns: %w", err)
+	}
+	return expectedDNSIP, nil
+}
+
+// Helper function to calculate slirp ip address offsets
+// Adapted from: https://github.com/signalsciences/ipv4/blob/master/int.go#L12-L24
+func addToIP(subnet *net.IPNet, offset uint32) (*net.IP, error) {
+	// I have no idea why I have to do this, but if I don't ip is 0
+	ipFixed := subnet.IP.To4()
+
+	ipInteger := uint32(ipFixed[3]) | uint32(ipFixed[2])<<8 | uint32(ipFixed[1])<<16 | uint32(ipFixed[0])<<24
+	ipNewRaw := ipInteger + offset
+	// Avoid overflows
+	if ipNewRaw < ipInteger {
+		return nil, fmt.Errorf("integer overflow while calculating ip address offset, %s + %d", ipFixed, offset)
+	}
+	ipNew := net.IPv4(byte(ipNewRaw>>24), byte(ipNewRaw>>16&0xFF), byte(ipNewRaw>>8)&0xFF, byte(ipNewRaw&0xFF))
+	if !subnet.Contains(ipNew) {
+		return nil, fmt.Errorf("calculated ip address %s is not within given subnet %s", ipNew.String(), subnet.String())
+	}
+	return &ipNew, nil
+}
+
+func waitForSync(syncR *os.File, cmd *exec.Cmd, logFile io.ReadSeeker, timeout time.Duration) error {
+	prog := filepath.Base(cmd.Path)
+	if len(cmd.Args) > 0 {
+		prog = cmd.Args[0]
+	}
+	b := make([]byte, 16)
+	for {
+		if err := syncR.SetDeadline(time.Now().Add(timeout)); err != nil {
+			return fmt.Errorf("setting %s pipe timeout: %w", prog, err)
+		}
+		// FIXME: return err as soon as proc exits, without waiting for timeout
+		_, err := syncR.Read(b)
+		if err == nil {
+			break
+		}
+		if errors.Is(err, os.ErrDeadlineExceeded) {
+			// Check if the process is still running.
+			var status syscall.WaitStatus
+			pid, err := syscall.Wait4(cmd.Process.Pid, &status, syscall.WNOHANG, nil)
+			if err != nil {
+				return fmt.Errorf("failed to read %s process status: %w", prog, err)
+			}
+			if pid != cmd.Process.Pid {
+				continue
+			}
+			if status.Exited() {
+				// Seek at the beginning of the file and read all its content
+				if _, err := logFile.Seek(0, 0); err != nil {
+					logrus.Errorf("Could not seek log file: %q", err)
+				}
+				logContent, err := io.ReadAll(logFile)
+				if err != nil {
+					return fmt.Errorf("%s failed: %w", prog, err)
+				}
+				return fmt.Errorf("%s failed: %q", prog, logContent)
+			}
+			if status.Signaled() {
+				return fmt.Errorf("%s killed by signal", prog)
+			}
+			continue
+		}
+		return fmt.Errorf("failed to read from %s sync pipe: %w", prog, err)
+	}
+	return nil
+}
+
+func SetupRootlessPortMappingViaRLK(opts *SetupOptions, slirpSubnet *net.IPNet, netStatus map[string]types.StatusBlock) error {
+	syncR, syncW, err := os.Pipe()
+	if err != nil {
+		return fmt.Errorf("failed to open pipe: %w", err)
+	}
+	defer closeQuiet(syncR)
+	defer closeQuiet(syncW)
+
+	logPath := filepath.Join(opts.Config.Engine.TmpDir, fmt.Sprintf("rootlessport-%s.log", opts.ContainerID))
+	logFile, err := os.Create(logPath)
+	if err != nil {
+		return fmt.Errorf("failed to open rootlessport log file %s: %w", logPath, err)
+	}
+	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 fmt.Errorf("delete file %s: %w", logPath, err)
+	}
+
+	childIP := GetRootlessPortChildIP(slirpSubnet, netStatus)
+	cfg := rootlessport.Config{
+		Mappings:    opts.Ports,
+		NetNSPath:   opts.Netns,
+		ExitFD:      3,
+		ReadyFD:     4,
+		TmpDir:      opts.Config.Engine.TmpDir,
+		ChildIP:     childIP,
+		ContainerID: opts.ContainerID,
+		RootlessCNI: netStatus != nil,
+	}
+	cfgJSON, err := json.Marshal(cfg)
+	if err != nil {
+		return err
+	}
+	cfgR := bytes.NewReader(cfgJSON)
+	var stdout bytes.Buffer
+	path, err := opts.Config.FindHelperBinary(rootlessport.BinaryName, false)
+	if err != nil {
+		return err
+	}
+	cmd := exec.Command(path)
+	cmd.Args = []string{rootlessport.BinaryName}
+
+	// Leak one end of the pipe in rootlessport process, the other will be sent to conmon
+	cmd.ExtraFiles = append(cmd.ExtraFiles, opts.RootlessPortExitPipeR, syncW)
+	cmd.Stdin = cfgR
+	// stdout is for human-readable error, stderr is for debug log
+	cmd.Stdout = &stdout
+	cmd.Stderr = io.MultiWriter(logFile, &logrusDebugWriter{"rootlessport: "})
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Setpgid: true,
+	}
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("failed to start rootlessport process: %w", err)
+	}
+	defer func() {
+		servicereaper.AddPID(cmd.Process.Pid)
+		if err := cmd.Process.Release(); err != nil {
+			logrus.Errorf("Unable to release rootlessport process: %q", err)
+		}
+	}()
+	if err := waitForSync(syncR, cmd, logFile, 3*time.Second); err != nil {
+		stdoutStr := stdout.String()
+		if stdoutStr != "" {
+			// err contains full debug log and too verbose, so return stdoutStr
+			logrus.Debug(err)
+			return fmt.Errorf("rootlessport " + strings.TrimSuffix(stdoutStr, "\n"))
+		}
+		return err
+	}
+	logrus.Debug("rootlessport is ready")
+	return nil
+}
+
+func setupRootlessPortMappingViaSlirp(ports []types.PortMapping, cmd *exec.Cmd, apiSocket string) (err error) {
+	const pidWaitTimeout = 60 * time.Second
+	chWait := make(chan error)
+	go func() {
+		interval := 25 * time.Millisecond
+		for i := time.Duration(0); i < pidWaitTimeout; i += interval {
+			// Check if the process is still running.
+			var status syscall.WaitStatus
+			pid, err := syscall.Wait4(cmd.Process.Pid, &status, syscall.WNOHANG, nil)
+			if err != nil {
+				break
+			}
+			if pid != cmd.Process.Pid {
+				continue
+			}
+			if status.Exited() || status.Signaled() {
+				chWait <- fmt.Errorf("slirp4netns exited with status %d", status.ExitStatus())
+			}
+			time.Sleep(interval)
+		}
+	}()
+	defer close(chWait)
+
+	// wait that API socket file appears before trying to use it.
+	if _, err := util.WaitForFile(apiSocket, chWait, pidWaitTimeout); err != nil {
+		return fmt.Errorf("waiting for slirp4nets to create the api socket file %s: %w", apiSocket, err)
+	}
+
+	// for each port we want to add we need to open a connection to the slirp4netns control socket
+	// and send the add_hostfwd command.
+	for _, port := range ports {
+		protocols := strings.Split(port.Protocol, ",")
+		for _, protocol := range protocols {
+			hostIP := port.HostIP
+			if hostIP == "" {
+				hostIP = "0.0.0.0"
+			}
+			for i := uint16(0); i < port.Range; i++ {
+				if err := openSlirp4netnsPort(apiSocket, protocol, hostIP, port.HostPort+i, port.ContainerPort+i); err != nil {
+					return err
+				}
+			}
+		}
+	}
+	logrus.Debug("slirp4netns port-forwarding setup via add_hostfwd is ready")
+	return nil
+}
+
+// openSlirp4netnsPort sends the slirp4netns pai quey to the given socket
+func openSlirp4netnsPort(apiSocket, proto, hostip string, hostport, guestport uint16) error {
+	conn, err := net.Dial("unix", apiSocket)
+	if err != nil {
+		return fmt.Errorf("cannot open connection to %s: %w", apiSocket, err)
+	}
+	defer func() {
+		if err := conn.Close(); err != nil {
+			logrus.Errorf("Unable to close slirp4netns connection: %q", err)
+		}
+	}()
+	apiCmd := slirp4netnsCmd{
+		Execute: "add_hostfwd",
+		Args: slirp4netnsCmdArg{
+			Proto:     proto,
+			HostAddr:  hostip,
+			HostPort:  hostport,
+			GuestPort: guestport,
+		},
+	}
+	// create the JSON payload and send it.  Mark the end of request shutting down writes
+	// to the socket, as requested by slirp4netns.
+	data, err := json.Marshal(&apiCmd)
+	if err != nil {
+		return fmt.Errorf("cannot marshal JSON for slirp4netns: %w", err)
+	}
+	if _, err := conn.Write([]byte(fmt.Sprintf("%s\n", data))); err != nil {
+		return fmt.Errorf("cannot write to control socket %s: %w", apiSocket, err)
+	}
+	if err := conn.(*net.UnixConn).CloseWrite(); err != nil {
+		return fmt.Errorf("cannot shutdown the socket %s: %w", apiSocket, err)
+	}
+	buf := make([]byte, 2048)
+	readLength, err := conn.Read(buf)
+	if err != nil {
+		return fmt.Errorf("cannot read from control socket %s: %w", apiSocket, err)
+	}
+	// if there is no 'error' key in the received JSON data, then the operation was
+	// successful.
+	var y map[string]interface{}
+	if err := json.Unmarshal(buf[0:readLength], &y); err != nil {
+		return fmt.Errorf("parsing error status from slirp4netns: %w", err)
+	}
+	if e, found := y["error"]; found {
+		return fmt.Errorf("from slirp4netns while setting up port redirection: %v", e)
+	}
+	return nil
+}
+
+func GetRootlessPortChildIP(slirpSubnet *net.IPNet, netStatus map[string]types.StatusBlock) string {
+	if slirpSubnet != nil {
+		slirp4netnsIP, err := GetIP(slirpSubnet)
+		if err != nil {
+			return ""
+		}
+		return slirp4netnsIP.String()
+	}
+
+	var ipv6 net.IP
+	for _, status := range netStatus {
+		for _, netInt := range status.Interfaces {
+			for _, netAddress := range netInt.Subnets {
+				ipv4 := netAddress.IPNet.IP.To4()
+				if ipv4 != nil {
+					return ipv4.String()
+				}
+				ipv6 = netAddress.IPNet.IP
+			}
+		}
+	}
+	if ipv6 != nil {
+		return ipv6.String()
+	}
+	return ""
+}
+
+// closeQuiet closes a file and logs any error. Should only be used within
+// a defer.
+func closeQuiet(f *os.File) {
+	if err := f.Close(); err != nil {
+		logrus.Errorf("Unable to close file %s: %q", f.Name(), err)
+	}
+}

vendor/github.com/containers/common/pkg/rootlessport/rootlessport_linux.go

@@ -0,0 +1,27 @@
+//go:build linux
+// +build linux
+
+// Rootlessport Config type for use in podman/cmd/rootlessport.
+package rootlessport
+
+import (
+	"github.com/containers/common/libnetwork/types"
+)
+
+const (
+	// BinaryName is the binary name for the parent process.
+	BinaryName = "rootlessport"
+)
+
+// Config needs to be provided to the process via stdin as a JSON string.
+// stdin needs to be closed after the message has been written.
+type Config struct {
+	Mappings    []types.PortMapping
+	NetNSPath   string
+	ExitFD      int
+	ReadyFD     int
+	TmpDir      string
+	ChildIP     string
+	ContainerID string
+	RootlessCNI bool
+}

vendor/github.com/containers/common/pkg/servicereaper/service.go

@@ -0,0 +1,65 @@
+//go:build linux
+// +build linux
+
+package servicereaper
+
+import (
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+
+	"github.com/sirupsen/logrus"
+)
+
+type service struct {
+	pidMap map[int]bool
+	mutex  *sync.Mutex
+}
+
+var s = service{
+	pidMap: map[int]bool{},
+	mutex:  &sync.Mutex{},
+}
+
+func AddPID(pid int) {
+	s.mutex.Lock()
+	s.pidMap[pid] = true
+	s.mutex.Unlock()
+}
+
+func Start() {
+	// create signal channel and only wait for SIGCHLD
+	sigc := make(chan os.Signal, 1)
+	signal.Notify(sigc, syscall.SIGCHLD)
+	// wait and reap in an  extra goroutine
+	go reaper(sigc)
+}
+
+func reaper(sigc chan os.Signal) {
+	for {
+		// block until we receive SIGCHLD
+		<-sigc
+		s.mutex.Lock()
+		for pid := range s.pidMap {
+			var status syscall.WaitStatus
+			waitpid, err := syscall.Wait4(pid, &status, syscall.WNOHANG, nil)
+			if err != nil {
+				// do not log error for ECHILD
+				if err != syscall.ECHILD {
+					logrus.Warnf("Wait for pid %d failed: %v ", pid, err)
+				}
+				delete(s.pidMap, pid)
+				continue
+			}
+			// if pid == 0 nothing happened
+			if waitpid == 0 {
+				continue
+			}
+			if status.Exited() || status.Signaled() {
+				delete(s.pidMap, pid)
+			}
+		}
+		s.mutex.Unlock()
+	}
+}