wsl: usernet: Don't always bind to port 2222

podman-machine starts gvproxy without specifying -ssh-port.
This means it will always bind port 2222 (see
containers/gvisor-tap-vsock#402), effectively
bypassing the dynamic ssh port allocation.

I don't think wsl needs this port to be opened/bound on the host, but
this commit starts gvproxy with -ssh-port set to the dynamic SSH port to
avoid port conflicts with crc.
When gvproxy allows to disable this port forwarding entirely, we can
revise this.

This should fix containers#20327

Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>

pkg/machine/wsl/usermodenet.go

@@ -32,7 +32,7 @@ fi
 if [[ ! $ROUTE =~ default\ via ]]; then
 	exit 3
 fi
-nohup $GVFORWARDER -iface podman-usermode -stop-if-exist ignore -url "stdio:$GVPROXY?listen-stdio=accept" > /var/log/vm.log 2> /var/log/vm.err  < /dev/null &
+nohup $GVFORWARDER -iface podman-usermode -stop-if-exist ignore -url "stdio:$GVPROXY?listen-stdio=accept&ssh-port=$GVSSHPORT" > /var/log/vm.log 2> /var/log/vm.err  < /dev/null &
 echo $! > $STATE/vm.pid
 sleep 1
 ps -eo args | grep -q -m1 ^$GVFORWARDER || exit 42
@@ -99,7 +99,7 @@ func startUserModeNetworking(mc *vmconfigs.MachineConfig) error {
 
 	// Start or reuse
 	if !running {
-		if err := launchUserModeNetDist(exe); err != nil {
+		if err := launchUserModeNetDist(exe, mc.SSH.Port); err != nil {
 			return err
 		}
 	}
@@ -168,15 +168,15 @@ func isGvProxyVMRunning() bool {
 	return wslInvoke(userModeDist, "bash", "-c", cmd) == nil
 }
 
-func launchUserModeNetDist(exeFile string) error {
+func launchUserModeNetDist(exeFile string, sshPort int) error {
 	fmt.Println("Starting user-mode networking...")
 
 	exe, err := specgen.ConvertWinMountPath(exeFile)
 	if err != nil {
 		return err
 	}
 
-	cmdStr := fmt.Sprintf("GVPROXY=%q\nGVFORWARDER=%q\n%s", exe, gvForwarderPath, startUserModeNet)
+	cmdStr := fmt.Sprintf("GVPROXY=%q\nGVFORWARDER=%q\nGVSSHPORT=%d\n%s", exe, gvForwarderPath, sshPort, startUserModeNet)
 	if err := wslPipe(cmdStr, userModeDist, "bash"); err != nil {
 		_ = terminateDist(userModeDist)