Create veth pair

Adds a veth pair with one end attached to the default network namespace and the other end attached to the rancher desktop namespace. Signed-off-by: Nino Kodabande <[email protected]>
rancher-sandbox · Oct 6, 2023 · a6fbc17 · a6fbc17
1 parent 61a006f
commit a6fbc17
Showing 1 changed file with 129 additions and 33 deletions.
diff --git a/cmd/network/setup_linux.go b/cmd/network/setup_linux.go
@@ -18,12 +18,14 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"net"
 	"os"
 	"os/exec"
 	"strconv"
 
 	"github.com/linuxkit/virtsock/pkg/vsock"
 	"github.com/sirupsen/logrus"
+	"github.com/vishvananda/netlink"
 	"github.com/vishvananda/netns"
 
 	"github.com/rancher-sandbox/rancher-desktop-networking/pkg/config"
@@ -43,33 +45,22 @@ var (
 )
 
 const (
-	nsenter            = "/usr/bin/nsenter"
-	unshare            = "/usr/bin/unshare"
-	vsockHandshakePort = 6669
-	vsockDialPort      = 6656
-	defaultTapDevice   = "eth0"
+	nsenter              = "/usr/bin/nsenter"
+	unshare              = "/usr/bin/unshare"
+	vsockHandshakePort   = 6669
+	vsockDialPort        = 6656
+	defaultTapDevice     = "eth0"
+	defaultNSVeth        = "veth0"
+	rancherDesktopNSVeth = "veth1"
+	defaultNamespacePID  = 1
+	cidrOnes             = 24
+	cidrBits             = 32
 )
 
 func main() {
-	flag.BoolVar(&debug, "debug", false, "enable additional debugging")
-	flag.StringVar(&tapIface, "tap-interface", defaultTapDevice, "tap interface name, eg. eth0, eth1")
-	flag.StringVar(&subnet, "subnet", config.DefaultSubnet,
-		fmt.Sprintf("Subnet range with CIDR suffix that is associated to the tap interface, e,g: %s", config.DefaultSubnet))
-	flag.StringVar(&tapDeviceMacAddr, "tap-mac-address", config.TapDeviceMacAddr,
-		"MAC address that is associated to the tap interface")
-	flag.StringVar(&vmSwitchPath, "vm-switch-path", "", "the path to the vm-switch binary that will run in a new namespace")
-	flag.StringVar(&vmSwitchLogFile, "vm-switch-logfile", "", "path to the logfile for vm-switch process")
-	flag.StringVar(&unshareArg, "unshare-arg", "", "the command argument to pass to the unshare program")
-	flag.StringVar(&logFile, "logfile", "/var/log/network-setup.log", "path to the logfile for network setup process")
-	flag.Parse()
+	initializeFlags()
 
-	if err := log.SetOutputFile(logFile, logrus.StandardLogger()); err != nil {
-		logrus.Fatalf("setting logger's output file failed: %v", err)
-	}
-
-	if debug {
-		logrus.SetLevel(logrus.DebugLevel)
-	}
+	setupLogging(logFile)
 
 	if vmSwitchPath == "" {
 		logrus.Fatal("path to the vm-switch process must be provided")
@@ -89,6 +80,8 @@ func main() {
 	}
 	logrus.Debugf("successful connection to host on CID: %v and Port: %d: connection: %+v", vsock.CIDHost, vsockDialPort, vsockConn)
 
+	originNS, _ := netns.Get()
+
 	// setup network namespace
 	ns, err := configureNamespace()
 	if err != nil {
@@ -99,6 +92,82 @@ func main() {
 		logrus.Fatal(err)
 	}
 
+	connFile, err := vsockConn.File()
+	if err != nil {
+		logrus.Fatal(err)
+	}
+
+	vmSwitchCmd := configureVMSwitch(ns,
+		vmSwitchLogFile,
+		vmSwitchPath,
+		tapIface,
+		subnet,
+		tapDeviceMacAddr,
+		connFile)
+
+	if err := vmSwitchCmd.Start(); err != nil {
+		logrus.Fatalf("could not start the vm-switch process: %v", err)
+	}
+	logrus.Infof("successfully started the vm-switch running with a PID: %v", vmSwitchCmd.Process.Pid)
+
+	if err := createVethPair(defaultNamespacePID, vmSwitchCmd.Process.Pid); err != nil {
+		logrus.Fatal(err)
+	}
+	logrus.Infof("created veth pair  %s and %s", defaultNSVeth, rancherDesktopNSVeth)
+
+	if err := configureVethPair(rancherDesktopNSVeth, "192.168.1.2"); err != nil {
+		logrus.Fatalf("failed setting up veth: %s for rancher desktop namespace: %v", rancherDesktopNSVeth, err)
+	}
+
+	// switch back to the original namespace to configure veth0
+	if err := netns.Set(originNS); err != nil {
+		logrus.Fatal(err)
+	}
+	if err := configureVethPair(defaultNSVeth, "192.168.1.1"); err != nil {
+		logrus.Fatalf("failed setting up veth: %s for rancher desktop namespace: %v", rancherDesktopNSVeth, err)
+	}
+
+	if err := originNS.Close(); err != nil {
+		logrus.Error(err)
+	}
+
+	if err := vmSwitchCmd.Wait(); err != nil {
+		logrus.Errorf("vm-switch exited with error: %v", err)
+	}
+}
+
+func initializeFlags() {
+	flag.BoolVar(&debug, "debug", false, "enable additional debugging")
+	flag.StringVar(&tapIface, "tap-interface", defaultTapDevice, "tap interface name, eg. eth0, eth1")
+	flag.StringVar(&subnet, "subnet", config.DefaultSubnet,
+		fmt.Sprintf("Subnet range with CIDR suffix that is associated to the tap interface, e,g: %s", config.DefaultSubnet))
+	flag.StringVar(&tapDeviceMacAddr, "tap-mac-address", config.TapDeviceMacAddr,
+		"MAC address that is associated to the tap interface")
+	flag.StringVar(&vmSwitchPath, "vm-switch-path", "", "the path to the vm-switch binary that will run in a new namespace")
+	flag.StringVar(&vmSwitchLogFile, "vm-switch-logfile", "", "path to the logfile for vm-switch process")
+	flag.StringVar(&unshareArg, "unshare-arg", "", "the command argument to pass to the unshare program")
+	flag.StringVar(&logFile, "logfile", "/var/log/network-setup.log", "path to the logfile for network setup process")
+	flag.Parse()
+}
+
+func setupLogging(logFile string) {
+	if err := log.SetOutputFile(logFile, logrus.StandardLogger()); err != nil {
+		logrus.Fatalf("setting logger's output file failed: %v", err)
+	}
+
+	if debug {
+		logrus.SetLevel(logrus.DebugLevel)
+	}
+}
+
+func configureVMSwitch(
+	ns netns.NsHandle,
+	vmSwitchLogFile,
+	vmSwitchPath,
+	tapIface,
+	subnet,
+	tapDevMacAddr string,
+	connFile *os.File) *exec.Cmd {
 	// Start the vm-switch process in the new namespace; we do
 	// this as the golang runtime can switch threads at will, so it
 	// is safer to have a whole process in a consistent namespace.
@@ -111,7 +180,7 @@ func main() {
 		"-subnet",
 		subnet,
 		"-tap-mac-address",
-		tapDeviceMacAddr,
+		tapDevMacAddr,
 	}
 	if vmSwitchLogFile != "" {
 		args = append(args, "-logfile", vmSwitchLogFile)
@@ -121,21 +190,48 @@ func main() {
 	}
 	vmSwitchCmd := exec.Command(nsenter, args...)
 
-	connFile, err := vsockConn.File()
-	if err != nil {
-		logrus.Fatal(err)
-	}
 	// pass in the vsock connection as a FD to the
 	// vm-switch process in the newely created namespace
 	vmSwitchCmd.ExtraFiles = []*os.File{connFile}
-	if err := vmSwitchCmd.Start(); err != nil {
-		logrus.Fatalf("could not start the vm-switch process: %v", err)
+	return vmSwitchCmd
+}
+
+func createVethPair(defaultNsPid, peerNsPid int) error {
+	veth := &netlink.Veth{
+		LinkAttrs: netlink.LinkAttrs{
+			Name:      defaultNSVeth,
+			Namespace: netlink.NsPid(defaultNsPid),
+		},
+		PeerName:      rancherDesktopNSVeth,
+		PeerNamespace: netlink.NsPid(peerNsPid),
 	}
-	logrus.Infof("successfully started the vm-switch running with a PID: %v", vmSwitchCmd.Process.Pid)
+	if err := netlink.LinkAdd(veth); err != nil {
+		return err
+	}
+	logrus.Infof("created veth pair %s and %s", defaultNSVeth, rancherDesktopNSVeth)
+	return nil
+}
 
-	if err := vmSwitchCmd.Wait(); err != nil {
-		logrus.Errorf("vm-switch exited with error: %v", err)
+func configureVethPair(vethName, ipAddr string) error {
+	veth, err := netlink.LinkByName(vethName)
+	if err != nil {
+		return err
+	}
+
+	vethIP := net.IPNet{
+		IP:   net.ParseIP(ipAddr),
+		Mask: net.CIDRMask(cidrOnes, cidrBits),
+	}
+
+	addr := &netlink.Addr{IPNet: &vethIP, Label: ""}
+	if err := netlink.AddrAdd(veth, addr); err != nil {
+		return err
+	}
+
+	if err := netlink.LinkSetUp(veth); err != nil {
+		return err
 	}
+	return nil
 }
 
 func unshareCmd(ns netns.NsHandle, args string) error {