1
0
mirror of https://git.zx2c4.com/wireguard-go synced 2024-11-10 16:59:17 +00:00
wireguard-go/tun/tun_freebsd.go
Jason A. Donenfeld 0ad14a89f5 global: buff -> buf
This always struck me as kind of weird and non-standard.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2023-03-13 17:55:53 +01:00

436 lines
9.6 KiB
Go

/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2023 WireGuard LLC. All Rights Reserved.
*/
package tun
import (
"errors"
"fmt"
"io"
"net"
"os"
"sync"
"syscall"
"unsafe"
"golang.org/x/sys/unix"
)
const (
_TUNSIFHEAD = 0x80047460
_TUNSIFMODE = 0x8004745e
_TUNGIFNAME = 0x4020745d
_TUNSIFPID = 0x2000745f
_SIOCGIFINFO_IN6 = 0xc048696c
_SIOCSIFINFO_IN6 = 0xc048696d
_ND6_IFF_AUTO_LINKLOCAL = 0x20
_ND6_IFF_NO_DAD = 0x100
)
// Iface requests with just the name
type ifreqName struct {
Name [unix.IFNAMSIZ]byte
_ [16]byte
}
// Iface requests with a pointer
type ifreqPtr struct {
Name [unix.IFNAMSIZ]byte
Data uintptr
_ [16 - unsafe.Sizeof(uintptr(0))]byte
}
// Iface requests with MTU
type ifreqMtu struct {
Name [unix.IFNAMSIZ]byte
MTU uint32
_ [12]byte
}
// ND6 flag manipulation
type nd6Req struct {
Name [unix.IFNAMSIZ]byte
Linkmtu uint32
Maxmtu uint32
Basereachable uint32
Reachable uint32
Retrans uint32
Flags uint32
Recalctm int
Chlim uint8
Initialized uint8
Randomseed0 [8]byte
Randomseed1 [8]byte
Randomid [8]byte
}
type NativeTun struct {
name string
tunFile *os.File
events chan Event
errors chan error
routeSocket int
closeOnce sync.Once
}
func (tun *NativeTun) routineRouteListener(tunIfindex int) {
var (
statusUp bool
statusMTU int
)
defer close(tun.events)
data := make([]byte, os.Getpagesize())
for {
retry:
n, err := unix.Read(tun.routeSocket, data)
if err != nil {
if errors.Is(err, syscall.EINTR) {
goto retry
}
tun.errors <- err
return
}
if n < 14 {
continue
}
if data[3 /* type */] != unix.RTM_IFINFO {
continue
}
ifindex := int(*(*uint16)(unsafe.Pointer(&data[12 /* ifindex */])))
if ifindex != tunIfindex {
continue
}
iface, err := net.InterfaceByIndex(ifindex)
if err != nil {
tun.errors <- err
return
}
// Up / Down event
up := (iface.Flags & net.FlagUp) != 0
if up != statusUp && up {
tun.events <- EventUp
}
if up != statusUp && !up {
tun.events <- EventDown
}
statusUp = up
// MTU changes
if iface.MTU != statusMTU {
tun.events <- EventMTUUpdate
}
statusMTU = iface.MTU
}
}
func tunName(fd uintptr) (string, error) {
var ifreq ifreqName
_, _, err := unix.Syscall(unix.SYS_IOCTL, fd, _TUNGIFNAME, uintptr(unsafe.Pointer(&ifreq)))
if err != 0 {
return "", err
}
return unix.ByteSliceToString(ifreq.Name[:]), nil
}
// Destroy a named system interface
func tunDestroy(name string) error {
fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM|unix.SOCK_CLOEXEC, 0)
if err != nil {
return err
}
defer unix.Close(fd)
var ifr [32]byte
copy(ifr[:], name)
_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uintptr(unix.SIOCIFDESTROY), uintptr(unsafe.Pointer(&ifr[0])))
if errno != 0 {
return fmt.Errorf("failed to destroy interface %s: %w", name, errno)
}
return nil
}
func CreateTUN(name string, mtu int) (Device, error) {
if len(name) > unix.IFNAMSIZ-1 {
return nil, errors.New("interface name too long")
}
// See if interface already exists
iface, _ := net.InterfaceByName(name)
if iface != nil {
return nil, fmt.Errorf("interface %s already exists", name)
}
tunFile, err := os.OpenFile("/dev/tun", unix.O_RDWR|unix.O_CLOEXEC, 0)
if err != nil {
return nil, err
}
tun := NativeTun{tunFile: tunFile}
var assignedName string
tun.operateOnFd(func(fd uintptr) {
assignedName, err = tunName(fd)
})
if err != nil {
tunFile.Close()
return nil, err
}
// Enable ifhead mode, otherwise tun will complain if it gets a non-AF_INET packet
ifheadmode := 1
var errno syscall.Errno
tun.operateOnFd(func(fd uintptr) {
_, _, errno = unix.Syscall(unix.SYS_IOCTL, fd, _TUNSIFHEAD, uintptr(unsafe.Pointer(&ifheadmode)))
})
if errno != 0 {
tunFile.Close()
tunDestroy(assignedName)
return nil, fmt.Errorf("unable to put into IFHEAD mode: %w", errno)
}
// Get out of PTP mode.
ifflags := syscall.IFF_BROADCAST | syscall.IFF_MULTICAST
tun.operateOnFd(func(fd uintptr) {
_, _, errno = unix.Syscall(unix.SYS_IOCTL, fd, uintptr(_TUNSIFMODE), uintptr(unsafe.Pointer(&ifflags)))
})
if errno != 0 {
tunFile.Close()
tunDestroy(assignedName)
return nil, fmt.Errorf("unable to put into IFF_BROADCAST mode: %w", errno)
}
// Disable link-local v6, not just because WireGuard doesn't do that anyway, but
// also because there are serious races with attaching and detaching LLv6 addresses
// in relation to interface lifetime within the FreeBSD kernel.
confd6, err := unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM|unix.SOCK_CLOEXEC, 0)
if err != nil {
tunFile.Close()
tunDestroy(assignedName)
return nil, err
}
defer unix.Close(confd6)
var ndireq nd6Req
copy(ndireq.Name[:], assignedName)
_, _, errno = unix.Syscall(unix.SYS_IOCTL, uintptr(confd6), uintptr(_SIOCGIFINFO_IN6), uintptr(unsafe.Pointer(&ndireq)))
if errno != 0 {
tunFile.Close()
tunDestroy(assignedName)
return nil, fmt.Errorf("unable to get nd6 flags for %s: %w", assignedName, errno)
}
ndireq.Flags = ndireq.Flags &^ _ND6_IFF_AUTO_LINKLOCAL
ndireq.Flags = ndireq.Flags | _ND6_IFF_NO_DAD
_, _, errno = unix.Syscall(unix.SYS_IOCTL, uintptr(confd6), uintptr(_SIOCSIFINFO_IN6), uintptr(unsafe.Pointer(&ndireq)))
if errno != 0 {
tunFile.Close()
tunDestroy(assignedName)
return nil, fmt.Errorf("unable to set nd6 flags for %s: %w", assignedName, errno)
}
if name != "" {
confd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM|unix.SOCK_CLOEXEC, 0)
if err != nil {
tunFile.Close()
tunDestroy(assignedName)
return nil, err
}
defer unix.Close(confd)
var newnp [unix.IFNAMSIZ]byte
copy(newnp[:], name)
var ifr ifreqPtr
copy(ifr.Name[:], assignedName)
ifr.Data = uintptr(unsafe.Pointer(&newnp[0]))
_, _, errno = unix.Syscall(unix.SYS_IOCTL, uintptr(confd), uintptr(unix.SIOCSIFNAME), uintptr(unsafe.Pointer(&ifr)))
if errno != 0 {
tunFile.Close()
tunDestroy(assignedName)
return nil, fmt.Errorf("Failed to rename %s to %s: %w", assignedName, name, errno)
}
}
return CreateTUNFromFile(tunFile, mtu)
}
func CreateTUNFromFile(file *os.File, mtu int) (Device, error) {
tun := &NativeTun{
tunFile: file,
events: make(chan Event, 10),
errors: make(chan error, 1),
}
var errno syscall.Errno
tun.operateOnFd(func(fd uintptr) {
_, _, errno = unix.Syscall(unix.SYS_IOCTL, fd, _TUNSIFPID, uintptr(0))
})
if errno != 0 {
tun.tunFile.Close()
return nil, fmt.Errorf("unable to become controlling TUN process: %w", errno)
}
name, err := tun.Name()
if err != nil {
tun.tunFile.Close()
return nil, err
}
tunIfindex, err := func() (int, error) {
iface, err := net.InterfaceByName(name)
if err != nil {
return -1, err
}
return iface.Index, nil
}()
if err != nil {
tun.tunFile.Close()
return nil, err
}
tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW|unix.SOCK_CLOEXEC, unix.AF_UNSPEC)
if err != nil {
tun.tunFile.Close()
return nil, err
}
go tun.routineRouteListener(tunIfindex)
err = tun.setMTU(mtu)
if err != nil {
tun.Close()
return nil, err
}
return tun, nil
}
func (tun *NativeTun) Name() (string, error) {
var name string
var err error
tun.operateOnFd(func(fd uintptr) {
name, err = tunName(fd)
})
if err != nil {
return "", err
}
tun.name = name
return name, nil
}
func (tun *NativeTun) File() *os.File {
return tun.tunFile
}
func (tun *NativeTun) Events() <-chan Event {
return tun.events
}
func (tun *NativeTun) Read(bufs [][]byte, sizes []int, offset int) (int, error) {
select {
case err := <-tun.errors:
return 0, err
default:
buf := bufs[0][offset-4:]
n, err := tun.tunFile.Read(buf[:])
if n < 4 {
return 0, err
}
sizes[0] = n - 4
return 1, err
}
}
func (tun *NativeTun) Write(bufs [][]byte, offset int) (int, error) {
if offset < 4 {
return 0, io.ErrShortBuffer
}
for i, buf := range bufs {
buf = buf[offset-4:]
if len(buf) < 5 {
return i, io.ErrShortBuffer
}
buf[0] = 0x00
buf[1] = 0x00
buf[2] = 0x00
switch buf[4] >> 4 {
case 4:
buf[3] = unix.AF_INET
case 6:
buf[3] = unix.AF_INET6
default:
return i, unix.EAFNOSUPPORT
}
if _, err := tun.tunFile.Write(buf); err != nil {
return i, err
}
}
return len(bufs), nil
}
func (tun *NativeTun) Close() error {
var err1, err2, err3 error
tun.closeOnce.Do(func() {
err1 = tun.tunFile.Close()
err2 = tunDestroy(tun.name)
if tun.routeSocket != -1 {
unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)
err3 = unix.Close(tun.routeSocket)
tun.routeSocket = -1
} else if tun.events != nil {
close(tun.events)
}
})
if err1 != nil {
return err1
}
if err2 != nil {
return err2
}
return err3
}
func (tun *NativeTun) setMTU(n int) error {
fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM|unix.SOCK_CLOEXEC, 0)
if err != nil {
return err
}
defer unix.Close(fd)
var ifr ifreqMtu
copy(ifr.Name[:], tun.name)
ifr.MTU = uint32(n)
_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uintptr(unix.SIOCSIFMTU), uintptr(unsafe.Pointer(&ifr)))
if errno != 0 {
return fmt.Errorf("failed to set MTU on %s: %w", tun.name, errno)
}
return nil
}
func (tun *NativeTun) MTU() (int, error) {
fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM|unix.SOCK_CLOEXEC, 0)
if err != nil {
return 0, err
}
defer unix.Close(fd)
var ifr ifreqMtu
copy(ifr.Name[:], tun.name)
_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uintptr(unix.SIOCGIFMTU), uintptr(unsafe.Pointer(&ifr)))
if errno != 0 {
return 0, fmt.Errorf("failed to get MTU on %s: %w", tun.name, errno)
}
return int(*(*int32)(unsafe.Pointer(&ifr.MTU))), nil
}
func (tun *NativeTun) BatchSize() int {
return 1
}