tun_darwin (#163)

- Remove water and replace with syscalls for tun setup
- Support named interfaces
- Set up routes with syscalls instead of os/exec

Co-authored-by: Wade Simmons <wade@wades.im>
This commit is contained in:
Chad Harp 2021-11-09 19:24:24 -06:00 committed by GitHub
parent 7801b589b6
commit 1915fab619
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 356 additions and 35 deletions

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@ -37,6 +37,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
- Darwin binaries are now universal (works on both amd64 and arm64), signed, and shipped in a notarized zip file. - Darwin binaries are now universal (works on both amd64 and arm64), signed, and shipped in a notarized zip file.
`nebula-darwin.zip` will be the only darwin release artifact. (#571) `nebula-darwin.zip` will be the only darwin release artifact. (#571)
- Darwin uses syscalls and AF_ROUTE to configure the routing table, instead of
using `/sbin/route`. Setting `tun.dev` is now allowed on Darwin as well, it
must be in the format `utun[0-9]+` or it will be ignored. (#163)
### Deprecated ### Deprecated
- The `preferred_ranges` option has been supported as a replacement for - The `preferred_ranges` option has been supported as a replacement for

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@ -148,7 +148,9 @@ punchy:
tun: tun:
# When tun is disabled, a lighthouse can be started without a local tun interface (and therefore without root) # When tun is disabled, a lighthouse can be started without a local tun interface (and therefore without root)
disabled: false disabled: false
# Name of the device # Name of the device. If not set, a default will be chosen by the OS.
# For macOS: if set, must be in the form `utun[0-9]+`.
# For FreeBSD: Required to be set, must be in the form `tun[0-9]+`.
dev: nebula1 dev: nebula1
# Toggles forwarding of local broadcast packets, the address of which depends on the ip/mask encoded in pki.cert # Toggles forwarding of local broadcast packets, the address of which depends on the ip/mask encoded in pki.cert
drop_local_broadcast: false drop_local_broadcast: false

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@ -7,34 +7,169 @@ import (
"fmt" "fmt"
"io" "io"
"net" "net"
"os/exec" "os"
"strconv" "syscall"
"unsafe"
"github.com/sirupsen/logrus" "github.com/sirupsen/logrus"
"github.com/songgao/water" netroute "golang.org/x/net/route"
"golang.org/x/sys/unix"
) )
type Tun struct { type Tun struct {
io.ReadWriteCloser
Device string Device string
Cidr *net.IPNet Cidr *net.IPNet
MTU int DefaultMTU int
TXQueueLen int
UnsafeRoutes []route UnsafeRoutes []route
l *logrus.Logger l *logrus.Logger
*water.Interface
// cache out buffer since we need to prepend 4 bytes for tun metadata
out []byte
} }
func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) { type sockaddrCtl struct {
scLen uint8
scFamily uint8
ssSysaddr uint16
scID uint32
scUnit uint32
scReserved [5]uint32
}
type ifReq struct {
Name [16]byte
Flags uint16
pad [8]byte
}
func ioctl(a1, a2, a3 uintptr) error {
_, _, errno := unix.Syscall(unix.SYS_IOCTL, a1, a2, a3)
if errno != 0 {
return errno
}
return nil
}
var sockaddrCtlSize uintptr = 32
const (
_SYSPROTO_CONTROL = 2 //define SYSPROTO_CONTROL 2 /* kernel control protocol */
_AF_SYS_CONTROL = 2 //#define AF_SYS_CONTROL 2 /* corresponding sub address type */
_PF_SYSTEM = unix.AF_SYSTEM //#define PF_SYSTEM AF_SYSTEM
_CTLIOCGINFO = 3227799043 //#define CTLIOCGINFO _IOWR('N', 3, struct ctl_info)
utunControlName = "com.apple.net.utun_control"
)
type ifreqAddr struct {
Name [16]byte
Addr unix.RawSockaddrInet4
pad [8]byte
}
type ifreqMTU struct {
Name [16]byte
MTU int32
pad [8]byte
}
type ifreqQLEN struct {
Name [16]byte
Value int32
pad [8]byte
}
func newTun(l *logrus.Logger, name string, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
if len(routes) > 0 { if len(routes) > 0 {
return nil, fmt.Errorf("route MTU not supported in Darwin") return nil, fmt.Errorf("route MTU not supported in Darwin")
} }
// NOTE: You cannot set the deviceName under Darwin, so you must check tun.Device after calling .Activate() ifIndex := -1
return &Tun{ if name != "" && name != "utun" {
Cidr: cidr, _, err := fmt.Sscanf(name, "utun%d", &ifIndex)
MTU: defaultMTU, if err != nil || ifIndex < 0 {
UnsafeRoutes: unsafeRoutes, // NOTE: we don't make this error so we don't break existing
l: l, // configs that set a name before it was used.
}, nil l.Warn("interface name must be utun[0-9]+ on Darwin, ignoring")
ifIndex = -1
}
}
fd, err := unix.Socket(_PF_SYSTEM, unix.SOCK_DGRAM, _SYSPROTO_CONTROL)
if err != nil {
return nil, fmt.Errorf("system socket: %v", err)
}
var ctlInfo = &struct {
ctlID uint32
ctlName [96]byte
}{}
copy(ctlInfo.ctlName[:], []byte(utunControlName))
err = ioctl(uintptr(fd), uintptr(_CTLIOCGINFO), uintptr(unsafe.Pointer(ctlInfo)))
if err != nil {
return nil, fmt.Errorf("CTLIOCGINFO: %v", err)
}
sc := sockaddrCtl{
scLen: uint8(sockaddrCtlSize),
scFamily: unix.AF_SYSTEM,
ssSysaddr: _AF_SYS_CONTROL,
scID: ctlInfo.ctlID,
scUnit: uint32(ifIndex) + 1,
}
_, _, errno := unix.RawSyscall(
unix.SYS_CONNECT,
uintptr(fd),
uintptr(unsafe.Pointer(&sc)),
uintptr(sockaddrCtlSize),
)
if errno != 0 {
return nil, fmt.Errorf("SYS_CONNECT: %v", errno)
}
var ifName struct {
name [16]byte
}
ifNameSize := uintptr(len(ifName.name))
_, _, errno = syscall.Syscall6(syscall.SYS_GETSOCKOPT, uintptr(fd),
2, // SYSPROTO_CONTROL
2, // UTUN_OPT_IFNAME
uintptr(unsafe.Pointer(&ifName)),
uintptr(unsafe.Pointer(&ifNameSize)), 0)
if errno != 0 {
return nil, fmt.Errorf("SYS_GETSOCKOPT: %v", errno)
}
name = string(ifName.name[:ifNameSize-1])
err = syscall.SetNonblock(fd, true)
if err != nil {
return nil, fmt.Errorf("SetNonblock: %v", err)
}
file := os.NewFile(uintptr(fd), "")
tun := &Tun{
ReadWriteCloser: file,
Device: name,
Cidr: cidr,
DefaultMTU: defaultMTU,
TXQueueLen: txQueueLen,
UnsafeRoutes: unsafeRoutes,
l: l,
}
return tun, nil
}
func (t *Tun) deviceBytes() (o [16]byte) {
for i, c := range t.Device {
o[i] = byte(c)
}
return
} }
func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int) (ifce *Tun, err error) { func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int) (ifce *Tun, err error) {
@ -42,43 +177,223 @@ func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU in
} }
func (c *Tun) Close() error { func (c *Tun) Close() error {
if c.Interface != nil { if c.ReadWriteCloser != nil {
return c.Interface.Close() return c.ReadWriteCloser.Close()
} }
return nil return nil
} }
func (c *Tun) Activate() error { func (t *Tun) Activate() error {
var err error devName := t.deviceBytes()
c.Interface, err = water.New(water.Config{
DeviceType: water.TUN, var addr, mask [4]byte
})
copy(addr[:], t.Cidr.IP.To4())
copy(mask[:], t.Cidr.Mask)
s, err := unix.Socket(
unix.AF_INET,
unix.SOCK_DGRAM,
unix.IPPROTO_IP,
)
if err != nil { if err != nil {
return fmt.Errorf("activate failed: %v", err) return err
} }
c.Device = c.Interface.Name() fd := uintptr(s)
// TODO use syscalls instead of exec.Command ifra := ifreqAddr{
if err = exec.Command("/sbin/ifconfig", c.Device, c.Cidr.String(), c.Cidr.IP.String()).Run(); err != nil { Name: devName,
return fmt.Errorf("failed to run 'ifconfig': %s", err) Addr: unix.RawSockaddrInet4{
Family: unix.AF_INET,
Addr: addr,
},
} }
if err = exec.Command("/sbin/route", "-n", "add", "-net", c.Cidr.String(), "-interface", c.Device).Run(); err != nil {
return fmt.Errorf("failed to run 'route add': %s", err) // Set the device ip address
if err = ioctl(fd, unix.SIOCSIFADDR, uintptr(unsafe.Pointer(&ifra))); err != nil {
return fmt.Errorf("failed to set tun address: %s", err)
} }
if err = exec.Command("/sbin/ifconfig", c.Device, "mtu", strconv.Itoa(c.MTU)).Run(); err != nil {
return fmt.Errorf("failed to run 'ifconfig': %s", err) // Set the device network
ifra.Addr.Addr = mask
if err = ioctl(fd, unix.SIOCSIFNETMASK, uintptr(unsafe.Pointer(&ifra))); err != nil {
return fmt.Errorf("failed to set tun netmask: %s", err)
} }
// Unsafe path routes
for _, r := range c.UnsafeRoutes { // Set the device name
if err = exec.Command("/sbin/route", "-n", "add", "-net", r.route.String(), "-interface", c.Device).Run(); err != nil { ifrf := ifReq{Name: devName}
return fmt.Errorf("failed to run 'route add' for unsafe_route %s: %s", r.route.String(), err) if err = ioctl(fd, unix.SIOCGIFFLAGS, uintptr(unsafe.Pointer(&ifrf))); err != nil {
return fmt.Errorf("failed to set tun device name: %s", err)
}
// Set the MTU on the device
ifm := ifreqMTU{Name: devName, MTU: int32(t.DefaultMTU)}
if err = ioctl(fd, unix.SIOCSIFMTU, uintptr(unsafe.Pointer(&ifm))); err != nil {
return fmt.Errorf("Failed to set tun mtu: %v", err)
}
/*
// Set the transmit queue length
ifrq := ifreqQLEN{Name: devName, Value: int32(t.TXQueueLen)}
if err = ioctl(fd, unix.SIOCSIFTXQLEN, uintptr(unsafe.Pointer(&ifrq))); err != nil {
// If we can't set the queue length nebula will still work but it may lead to packet loss
l.WithError(err).Error("Failed to set tun tx queue length")
} }
*/
// Bring up the interface
ifrf.Flags = ifrf.Flags | unix.IFF_UP
if err = ioctl(fd, unix.SIOCSIFFLAGS, uintptr(unsafe.Pointer(&ifrf))); err != nil {
return fmt.Errorf("failed to bring the tun device up: %s", err)
}
routeSock, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
if err != nil {
return fmt.Errorf("unable to create AF_ROUTE socket: %v", err)
}
defer func() {
unix.Shutdown(routeSock, unix.SHUT_RDWR)
err := unix.Close(routeSock)
if err != nil {
t.l.WithError(err).Error("failed to close AF_ROUTE socket")
}
}()
routeAddr := &netroute.Inet4Addr{}
maskAddr := &netroute.Inet4Addr{}
linkAddr, err := getLinkAddr(t.Device)
if err != nil {
return err
}
if linkAddr == nil {
return fmt.Errorf("unable to discover link_addr for tun interface")
}
copy(routeAddr.IP[:], addr[:])
copy(maskAddr.IP[:], mask[:])
err = addRoute(routeSock, routeAddr, maskAddr, linkAddr)
if err != nil {
return err
}
// Run the interface
ifrf.Flags = ifrf.Flags | unix.IFF_UP | unix.IFF_RUNNING
if err = ioctl(fd, unix.SIOCSIFFLAGS, uintptr(unsafe.Pointer(&ifrf))); err != nil {
return fmt.Errorf("failed to run tun device: %s", err)
}
// Unsafe path routes
for _, r := range t.UnsafeRoutes {
copy(routeAddr.IP[:], r.route.IP.To4())
copy(maskAddr.IP[:], net.IP(r.route.Mask).To4())
err = addRoute(routeSock, routeAddr, maskAddr, linkAddr)
if err != nil {
return err
}
// TODO how to set metric
} }
return nil return nil
} }
// Get the LinkAddr for the interface of the given name
// TODO: Is there an easier way to fetch this when we create the interface?
// Maybe SIOCGIFINDEX? but this doesn't appear to exist in the darwin headers.
func getLinkAddr(name string) (*netroute.LinkAddr, error) {
rib, err := netroute.FetchRIB(unix.AF_UNSPEC, unix.NET_RT_IFLIST, 0)
if err != nil {
return nil, err
}
msgs, err := netroute.ParseRIB(unix.NET_RT_IFLIST, rib)
if err != nil {
return nil, err
}
for _, m := range msgs {
switch m := m.(type) {
case *netroute.InterfaceMessage:
if m.Name == name {
sa, ok := m.Addrs[unix.RTAX_IFP].(*netroute.LinkAddr)
if ok {
return sa, nil
}
}
}
}
return nil, nil
}
func addRoute(sock int, addr, mask *netroute.Inet4Addr, link *netroute.LinkAddr) error {
r := netroute.RouteMessage{
Version: unix.RTM_VERSION,
Type: unix.RTM_ADD,
Flags: unix.RTF_UP,
Seq: 1,
Addrs: []netroute.Addr{
unix.RTAX_DST: addr,
unix.RTAX_GATEWAY: link,
unix.RTAX_NETMASK: mask,
},
}
data, err := r.Marshal()
if err != nil {
return fmt.Errorf("failed to create route.RouteMessage: %v", err)
}
_, err = unix.Write(sock, data[:])
if err != nil {
return fmt.Errorf("failed to write route.RouteMessage to socket: %v", err)
}
return nil
}
var _ io.ReadWriteCloser = (*Tun)(nil)
func (t *Tun) Read(to []byte) (int, error) {
buf := make([]byte, len(to)+4)
n, err := t.ReadWriteCloser.Read(buf)
copy(to, buf[4:])
return n - 4, err
}
// Write is only valid for single threaded use
func (t *Tun) Write(from []byte) (int, error) {
buf := t.out
if cap(buf) < len(from)+4 {
buf = make([]byte, len(from)+4)
t.out = buf
}
buf = buf[:len(from)+4]
if len(from) == 0 {
return 0, syscall.EIO
}
// Determine the IP Family for the NULL L2 Header
ipVer := from[0] >> 4
if ipVer == 4 {
buf[3] = syscall.AF_INET
} else if ipVer == 6 {
buf[3] = syscall.AF_INET6
} else {
return 0, fmt.Errorf("Unable to determine IP version from packet")
}
copy(buf[4:], from)
n, err := t.ReadWriteCloser.Write(buf)
return n - 4, err
}
func (c *Tun) CidrNet() *net.IPNet { func (c *Tun) CidrNet() *net.IPNet {
return c.Cidr return c.Cidr
} }