diff --git a/overlay/tun.go b/overlay/tun.go index ddf44a3..90778c2 100644 --- a/overlay/tun.go +++ b/overlay/tun.go @@ -81,3 +81,27 @@ func prefixToMask(prefix netip.Prefix) netip.Addr { addr, _ := netip.AddrFromSlice(net.CIDRMask(prefix.Bits(), pLen)) return addr } + +func flipBytes(b []byte) []byte { + for i := 0; i < len(b); i++ { + b[i] ^= 0xFF + } + return b +} +func orBytes(a []byte, b []byte) []byte { + ret := make([]byte, len(a)) + for i := 0; i < len(a); i++ { + ret[i] = a[i] | b[i] + } + return ret +} + +func getBroadcast(cidr netip.Prefix) netip.Addr { + broadcast, _ := netip.AddrFromSlice( + orBytes( + cidr.Addr().AsSlice(), + flipBytes(prefixToMask(cidr).AsSlice()), + ), + ) + return broadcast +} diff --git a/overlay/tun_freebsd.go b/overlay/tun_freebsd.go index f597881..0dd8228 100644 --- a/overlay/tun_freebsd.go +++ b/overlay/tun_freebsd.go @@ -501,30 +501,6 @@ func (t *tun) deviceBytes() (o [16]byte) { return } -func flipBytes(b []byte) []byte { - for i := 0; i < len(b); i++ { - b[i] ^= 0xFF - } - return b -} -func orBytes(a []byte, b []byte) []byte { - ret := make([]byte, len(a)) - for i := 0; i < len(a); i++ { - ret[i] = a[i] | b[i] - } - return ret -} - -func getBroadcast(cidr netip.Prefix) netip.Addr { - broadcast, _ := netip.AddrFromSlice( - orBytes( - cidr.Addr().AsSlice(), - flipBytes(prefixToMask(cidr).AsSlice()), - ), - ) - return broadcast -} - func addRoute(prefix netip.Prefix, gateway netroute.Addr) error { sock, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC) if err != nil { diff --git a/overlay/tun_netbsd.go b/overlay/tun_netbsd.go index 5ff9b0f..597c591 100644 --- a/overlay/tun_netbsd.go +++ b/overlay/tun_netbsd.go @@ -4,13 +4,12 @@ package overlay import ( + "errors" "fmt" "io" "net/netip" "os" - "os/exec" "regexp" - "strconv" "sync/atomic" "syscall" "unsafe" @@ -20,11 +19,42 @@ import ( "github.com/slackhq/nebula/config" "github.com/slackhq/nebula/routing" "github.com/slackhq/nebula/util" + netroute "golang.org/x/net/route" + "golang.org/x/sys/unix" ) -type ifreqDestroy struct { - Name [16]byte - pad [16]byte +const ( + SIOCAIFADDR_IN6 = 0x8080696b + TUNSIFHEAD = 0x80047442 + TUNSIFMODE = 0x80047458 +) + +type ifreqAlias4 struct { + Name [unix.IFNAMSIZ]byte + Addr unix.RawSockaddrInet4 + DstAddr unix.RawSockaddrInet4 + MaskAddr unix.RawSockaddrInet4 +} + +type ifreqAlias6 struct { + Name [unix.IFNAMSIZ]byte + Addr unix.RawSockaddrInet6 + DstAddr unix.RawSockaddrInet6 + PrefixMask unix.RawSockaddrInet6 + Flags uint32 + Lifetime addrLifetime +} + +type ifreq struct { + Name [unix.IFNAMSIZ]byte + data int +} + +type addrLifetime struct { + Expire uint64 + Preferred uint64 + Vltime uint32 + Pltime uint32 } type tun struct { @@ -34,40 +64,18 @@ type tun struct { Routes atomic.Pointer[[]Route] routeTree atomic.Pointer[bart.Table[routing.Gateways]] l *logrus.Logger - - io.ReadWriteCloser + f *os.File + fd int } -func (t *tun) Close() error { - if t.ReadWriteCloser != nil { - if err := t.ReadWriteCloser.Close(); err != nil { - return err - } - - s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_IP) - if err != nil { - return err - } - defer syscall.Close(s) - - ifreq := ifreqDestroy{Name: t.deviceBytes()} - - err = ioctl(uintptr(s), syscall.SIOCIFDESTROY, uintptr(unsafe.Pointer(&ifreq))) - - return err - } - return nil -} +var deviceNameRE = regexp.MustCompile(`^tun[0-9]+$`) func newTunFromFd(_ *config.C, _ *logrus.Logger, _ int, _ []netip.Prefix) (*tun, error) { return nil, fmt.Errorf("newTunFromFd not supported in NetBSD") } -var deviceNameRE = regexp.MustCompile(`^tun[0-9]+$`) - func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, _ bool) (*tun, error) { // Try to open tun device - var file *os.File var err error deviceName := c.GetString("tun.dev", "") if deviceName == "" { @@ -77,17 +85,23 @@ func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, _ bool) ( return nil, fmt.Errorf("a device name in the format of /dev/tunN must be specified") } - file, err = os.OpenFile("/dev/"+deviceName, os.O_RDWR, 0) + fd, err := unix.Open("/dev/"+deviceName, os.O_RDWR, 0) if err != nil { return nil, err } + err = unix.SetNonblock(fd, true) + if err != nil { + l.WithError(err).Warn("Failed to set the tun device as nonblocking") + } + t := &tun{ - ReadWriteCloser: file, - Device: deviceName, - vpnNetworks: vpnNetworks, - MTU: c.GetInt("tun.mtu", DefaultMTU), - l: l, + f: os.NewFile(uintptr(fd), ""), + fd: fd, + Device: deviceName, + vpnNetworks: vpnNetworks, + MTU: c.GetInt("tun.mtu", DefaultMTU), + l: l, } err = t.reload(c, true) @@ -105,40 +119,225 @@ func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, _ bool) ( return t, nil } +func (t *tun) Close() error { + if t.f != nil { + if err := t.f.Close(); err != nil { + return fmt.Errorf("error closing tun file: %w", err) + } + + // t.f.Close should have handled it for us but let's be extra sure + _ = unix.Close(t.fd) + + s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_IP) + if err != nil { + return err + } + defer syscall.Close(s) + + ifr := ifreq{Name: t.deviceBytes()} + err = ioctl(uintptr(s), syscall.SIOCIFDESTROY, uintptr(unsafe.Pointer(&ifr))) + return err + } + return nil +} + +func (t *tun) Read(to []byte) (int, error) { + rc, err := t.f.SyscallConn() + if err != nil { + return 0, fmt.Errorf("failed to get syscall conn for tun: %w", err) + } + + var errno syscall.Errno + var n uintptr + err = rc.Read(func(fd uintptr) bool { + // first 4 bytes is protocol family, in network byte order + head := [4]byte{} + iovecs := []syscall.Iovec{ + {&head[0], 4}, + {&to[0], uint64(len(to))}, + } + + n, _, errno = syscall.Syscall(syscall.SYS_READV, fd, uintptr(unsafe.Pointer(&iovecs[0])), uintptr(2)) + if errno.Temporary() { + // We got an EAGAIN, EINTR, or EWOULDBLOCK, go again + return false + } + return true + }) + if err != nil { + if err == syscall.EBADF || err.Error() == "use of closed file" { + // Go doesn't export poll.ErrFileClosing but happily reports it to us so here we are + // https://github.com/golang/go/blob/master/src/internal/poll/fd_poll_runtime.go#L121 + return 0, os.ErrClosed + } + return 0, fmt.Errorf("failed to make read call for tun: %w", err) + } + + if errno != 0 { + return 0, fmt.Errorf("failed to make inner read call for tun: %w", errno) + } + + // fix bytes read number to exclude header + bytesRead := int(n) + if bytesRead < 0 { + return bytesRead, nil + } else if bytesRead < 4 { + return 0, nil + } else { + return bytesRead - 4, nil + } +} + +// Write is only valid for single threaded use +func (t *tun) Write(from []byte) (int, error) { + if len(from) <= 1 { + return 0, syscall.EIO + } + + ipVer := from[0] >> 4 + var head [4]byte + // first 4 bytes is protocol family, in network byte order + if ipVer == 4 { + head[3] = syscall.AF_INET + } else if ipVer == 6 { + head[3] = syscall.AF_INET6 + } else { + return 0, fmt.Errorf("unable to determine IP version from packet") + } + + rc, err := t.f.SyscallConn() + if err != nil { + return 0, err + } + + var errno syscall.Errno + var n uintptr + err = rc.Write(func(fd uintptr) bool { + iovecs := []syscall.Iovec{ + {&head[0], 4}, + {&from[0], uint64(len(from))}, + } + + n, _, errno = syscall.Syscall(syscall.SYS_WRITEV, fd, uintptr(unsafe.Pointer(&iovecs[0])), uintptr(2)) + // According to NetBSD documentation for TUN, writes will only return errors in which + // this packet will never be delivered so just go on living life. + return true + }) + if err != nil { + return 0, err + } + + if errno != 0 { + return 0, errno + } + + return int(n) - 4, err +} + func (t *tun) addIp(cidr netip.Prefix) error { - var err error + if cidr.Addr().Is4() { + var req ifreqAlias4 + req.Name = t.deviceBytes() + req.Addr = unix.RawSockaddrInet4{ + Len: unix.SizeofSockaddrInet4, + Family: unix.AF_INET, + Addr: cidr.Addr().As4(), + } + req.DstAddr = unix.RawSockaddrInet4{ + Len: unix.SizeofSockaddrInet4, + Family: unix.AF_INET, + Addr: cidr.Addr().As4(), + } + req.MaskAddr = unix.RawSockaddrInet4{ + Len: unix.SizeofSockaddrInet4, + Family: unix.AF_INET, + Addr: prefixToMask(cidr).As4(), + } - // TODO use syscalls instead of exec.Command - cmd := exec.Command("/sbin/ifconfig", t.Device, cidr.String(), cidr.Addr().String()) - t.l.Debug("command: ", cmd.String()) - if err = cmd.Run(); err != nil { - return fmt.Errorf("failed to run 'ifconfig': %s", err) + s, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_IP) + if err != nil { + return err + } + defer syscall.Close(s) + + if err := ioctl(uintptr(s), unix.SIOCAIFADDR, uintptr(unsafe.Pointer(&req))); err != nil { + return fmt.Errorf("failed to set tun address %s: %s", cidr.Addr(), err) + } + + return nil } - cmd = exec.Command("/sbin/route", "-n", "add", "-net", cidr.String(), cidr.Addr().String()) - t.l.Debug("command: ", cmd.String()) - if err = cmd.Run(); err != nil { - return fmt.Errorf("failed to run 'route add': %s", err) + if cidr.Addr().Is6() { + var req ifreqAlias6 + req.Name = t.deviceBytes() + req.Addr = unix.RawSockaddrInet6{ + Len: unix.SizeofSockaddrInet6, + Family: unix.AF_INET6, + Addr: cidr.Addr().As16(), + } + req.PrefixMask = unix.RawSockaddrInet6{ + Len: unix.SizeofSockaddrInet6, + Family: unix.AF_INET6, + Addr: prefixToMask(cidr).As16(), + } + req.Lifetime = addrLifetime{ + Vltime: 0xffffffff, + Pltime: 0xffffffff, + } + + s, err := unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM, unix.IPPROTO_IP) + if err != nil { + return err + } + defer syscall.Close(s) + + if err := ioctl(uintptr(s), SIOCAIFADDR_IN6, uintptr(unsafe.Pointer(&req))); err != nil { + return fmt.Errorf("failed to set tun address %s: %s", cidr.Addr().String(), err) + } + return nil } - cmd = exec.Command("/sbin/ifconfig", t.Device, "mtu", strconv.Itoa(t.MTU)) - t.l.Debug("command: ", cmd.String()) - if err = cmd.Run(); err != nil { - return fmt.Errorf("failed to run 'ifconfig': %s", err) - } - - // Unsafe path routes - return t.addRoutes(false) + return fmt.Errorf("unknown address type %v", cidr) } func (t *tun) Activate() error { + mode := int32(unix.IFF_BROADCAST) + err := ioctl(uintptr(t.fd), TUNSIFMODE, uintptr(unsafe.Pointer(&mode))) + if err != nil { + return fmt.Errorf("failed to set tun device mode: %w", err) + } + + v := 1 + err = ioctl(uintptr(t.fd), TUNSIFHEAD, uintptr(unsafe.Pointer(&v))) + if err != nil { + return fmt.Errorf("failed to set tun device head: %w", err) + } + + err = t.doIoctlByName(unix.SIOCSIFMTU, uint32(t.MTU)) + if err != nil { + return fmt.Errorf("failed to set tun mtu: %w", err) + } + for i := range t.vpnNetworks { - err := t.addIp(t.vpnNetworks[i]) + err = t.addIp(t.vpnNetworks[i]) if err != nil { return err } } - return nil + + return t.addRoutes(false) +} + +func (t *tun) doIoctlByName(ctl uintptr, value uint32) error { + s, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_IP) + if err != nil { + return err + } + defer syscall.Close(s) + + ir := ifreq{Name: t.deviceBytes(), data: int(value)} + err = ioctl(uintptr(s), ctl, uintptr(unsafe.Pointer(&ir))) + return err } func (t *tun) reload(c *config.C, initial bool) error { @@ -197,21 +396,23 @@ func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) { func (t *tun) addRoutes(logErrors bool) error { routes := *t.Routes.Load() + for _, r := range routes { if len(r.Via) == 0 || !r.Install { // We don't allow route MTUs so only install routes with a via continue } - cmd := exec.Command("/sbin/route", "-n", "add", "-net", r.Cidr.String(), t.vpnNetworks[0].Addr().String()) - t.l.Debug("command: ", cmd.String()) - if err := cmd.Run(); err != nil { - retErr := util.NewContextualError("failed to run 'route add' for unsafe_route", map[string]any{"route": r}, err) + err := addRoute(r.Cidr, t.vpnNetworks) + if err != nil { + retErr := util.NewContextualError("Failed to add route", map[string]any{"route": r}, err) if logErrors { retErr.Log(t.l) } else { return retErr } + } else { + t.l.WithField("route", r).Info("Added route") } } @@ -224,10 +425,8 @@ func (t *tun) removeRoutes(routes []Route) error { continue } - //TODO: CERT-V2 is this right? - cmd := exec.Command("/sbin/route", "-n", "delete", "-net", r.Cidr.String(), t.vpnNetworks[0].Addr().String()) - t.l.Debug("command: ", cmd.String()) - if err := cmd.Run(); err != nil { + err := delRoute(r.Cidr, t.vpnNetworks) + if err != nil { t.l.WithError(err).WithField("route", r).Error("Failed to remove route") } else { t.l.WithField("route", r).Info("Removed route") @@ -242,3 +441,123 @@ func (t *tun) deviceBytes() (o [16]byte) { } return } + +func addRoute(prefix netip.Prefix, gateways []netip.Prefix) error { + sock, 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 unix.Close(sock) + + route := &netroute.RouteMessage{ + Version: unix.RTM_VERSION, + Type: unix.RTM_ADD, + Flags: unix.RTF_UP | unix.RTF_GATEWAY, + Seq: 1, + } + + if prefix.Addr().Is4() { + gw, err := selectGateway(prefix, gateways) + if err != nil { + return err + } + route.Addrs = []netroute.Addr{ + unix.RTAX_DST: &netroute.Inet4Addr{IP: prefix.Masked().Addr().As4()}, + unix.RTAX_NETMASK: &netroute.Inet4Addr{IP: prefixToMask(prefix).As4()}, + unix.RTAX_GATEWAY: &netroute.Inet4Addr{IP: gw.Addr().As4()}, + } + } else { + gw, err := selectGateway(prefix, gateways) + if err != nil { + return err + } + route.Addrs = []netroute.Addr{ + unix.RTAX_DST: &netroute.Inet6Addr{IP: prefix.Masked().Addr().As16()}, + unix.RTAX_NETMASK: &netroute.Inet6Addr{IP: prefixToMask(prefix).As16()}, + unix.RTAX_GATEWAY: &netroute.Inet6Addr{IP: gw.Addr().As16()}, + } + } + + data, err := route.Marshal() + if err != nil { + return fmt.Errorf("failed to create route.RouteMessage: %w", err) + } + + _, err = unix.Write(sock, data[:]) + if err != nil { + if errors.Is(err, unix.EEXIST) { + // Try to do a change + route.Type = unix.RTM_CHANGE + data, err = route.Marshal() + if err != nil { + return fmt.Errorf("failed to create route.RouteMessage for change: %w", err) + } + _, err = unix.Write(sock, data[:]) + return err + } + return fmt.Errorf("failed to write route.RouteMessage to socket: %w", err) + } + + return nil +} + +func delRoute(prefix netip.Prefix, gateways []netip.Prefix) error { + sock, 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 unix.Close(sock) + + route := netroute.RouteMessage{ + Version: unix.RTM_VERSION, + Type: unix.RTM_DELETE, + Seq: 1, + } + + if prefix.Addr().Is4() { + gw, err := selectGateway(prefix, gateways) + if err != nil { + return err + } + route.Addrs = []netroute.Addr{ + unix.RTAX_DST: &netroute.Inet4Addr{IP: prefix.Masked().Addr().As4()}, + unix.RTAX_NETMASK: &netroute.Inet4Addr{IP: prefixToMask(prefix).As4()}, + unix.RTAX_GATEWAY: &netroute.Inet4Addr{IP: gw.Addr().As4()}, + } + } else { + gw, err := selectGateway(prefix, gateways) + if err != nil { + return err + } + route.Addrs = []netroute.Addr{ + unix.RTAX_DST: &netroute.Inet6Addr{IP: prefix.Masked().Addr().As16()}, + unix.RTAX_NETMASK: &netroute.Inet6Addr{IP: prefixToMask(prefix).As16()}, + unix.RTAX_GATEWAY: &netroute.Inet6Addr{IP: gw.Addr().As16()}, + } + } + + data, err := route.Marshal() + if err != nil { + return fmt.Errorf("failed to create route.RouteMessage: %w", err) + } + _, err = unix.Write(sock, data[:]) + if err != nil { + return fmt.Errorf("failed to write route.RouteMessage to socket: %w", err) + } + + return nil +} + +func selectGateway(dest netip.Prefix, gateways []netip.Prefix) (netip.Prefix, error) { + for _, gateway := range gateways { + if dest.Addr().Is4() && gateway.Addr().Is4() { + return gateway, nil + } + + if dest.Addr().Is6() && gateway.Addr().Is6() { + return gateway, nil + } + } + + return netip.Prefix{}, fmt.Errorf("no gateway found for %v in the list of vpn networks", dest) +}