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tailscale/wgengine/userspace.go

1528 lines
43 KiB
Go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package wgengine
import (
"bufio"
"bytes"
crand "crypto/rand"
"errors"
"fmt"
"io"
"os"
"reflect"
"runtime"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"go4.org/mem"
"golang.zx2c4.com/wireguard/device"
"golang.zx2c4.com/wireguard/tun"
"inet.af/netaddr"
"tailscale.com/control/controlclient"
"tailscale.com/health"
"tailscale.com/ipn/ipnstate"
"tailscale.com/net/dns"
"tailscale.com/net/dns/resolver"
"tailscale.com/net/flowtrack"
"tailscale.com/net/interfaces"
"tailscale.com/net/packet"
"tailscale.com/net/tsaddr"
"tailscale.com/net/tshttpproxy"
"tailscale.com/net/tstun"
"tailscale.com/tailcfg"
"tailscale.com/tstime/mono"
"tailscale.com/types/ipproto"
"tailscale.com/types/key"
"tailscale.com/types/logger"
"tailscale.com/types/netmap"
"tailscale.com/types/wgkey"
"tailscale.com/util/deephash"
"tailscale.com/version"
"tailscale.com/wgengine/filter"
"tailscale.com/wgengine/magicsock"
"tailscale.com/wgengine/monitor"
"tailscale.com/wgengine/router"
"tailscale.com/wgengine/wgcfg"
"tailscale.com/wgengine/wglog"
)
const magicDNSPort = 53
var magicDNSIP = netaddr.IPv4(100, 100, 100, 100)
// Lazy wireguard-go configuration parameters.
const (
// lazyPeerIdleThreshold is the idle duration after
// which we remove a peer from the wireguard configuration.
// (This includes peers that have never been idle, which
// effectively have infinite idleness)
lazyPeerIdleThreshold = 5 * time.Minute
// packetSendTimeUpdateFrequency controls how often we record
// the time that we wrote a packet to an IP address.
packetSendTimeUpdateFrequency = 10 * time.Second
// packetSendRecheckWireguardThreshold controls how long we can go
// between packet sends to an IP before checking to see
// whether this IP address needs to be added back to the
// Wireguard peer oconfig.
packetSendRecheckWireguardThreshold = 1 * time.Minute
)
// statusPollInterval is how often we ask wireguard-go for its engine
// status (as long as there's activity). See docs on its use below.
const statusPollInterval = 1 * time.Minute
type userspaceEngine struct {
logf logger.Logf
wgLogger *wglog.Logger //a wireguard-go logging wrapper
reqCh chan struct{}
waitCh chan struct{} // chan is closed when first Close call completes; contrast with closing bool
timeNow func() mono.Time
tundev *tstun.Wrapper
wgdev *device.Device
router router.Router
confListenPort uint16 // original conf.ListenPort
dns *dns.Manager
magicConn *magicsock.Conn
linkMon *monitor.Mon
linkMonOwned bool // whether we created linkMon (and thus need to close it)
linkMonUnregister func() // unsubscribes from changes; used regardless of linkMonOwned
birdClient BIRDClient // or nil
testMaybeReconfigHook func() // for tests; if non-nil, fires if maybeReconfigWireguardLocked called
// isLocalAddr reports the whether an IP is assigned to the local
// tunnel interface. It's used to reflect local packets
// incorrectly sent to us.
isLocalAddr atomic.Value // of func(netaddr.IP)bool
// isDNSIPOverTailscale reports the whether a DNS resolver's IP
// is being routed over Tailscale.
isDNSIPOverTailscale atomic.Value // of func(netaddr.IP)bool
wgLock sync.Mutex // serializes all wgdev operations; see lock order comment below
lastCfgFull wgcfg.Config
lastNMinPeers int
lastRouterSig deephash.Sum // of router.Config
lastEngineSigFull deephash.Sum // of full wireguard config
lastEngineSigTrim deephash.Sum // of trimmed wireguard config
lastDNSConfig *dns.Config
recvActivityAt map[tailcfg.NodeKey]mono.Time
trimmedNodes map[tailcfg.NodeKey]bool // set of node keys of peers currently excluded from wireguard config
sentActivityAt map[netaddr.IP]*mono.Time // value is accessed atomically
destIPActivityFuncs map[netaddr.IP]func()
statusBufioReader *bufio.Reader // reusable for UAPI
lastStatusPollTime mono.Time // last time we polled the engine status
lastIsSubnetRouter bool // was the node a primary subnet router in the last run.
mu sync.Mutex // guards following; see lock order comment below
netMap *netmap.NetworkMap // or nil
closing bool // Close was called (even if we're still closing)
statusCallback StatusCallback
peerSequence []wgkey.Key
endpoints []tailcfg.Endpoint
pendOpen map[flowtrack.Tuple]*pendingOpenFlow // see pendopen.go
networkMapCallbacks map[*someHandle]NetworkMapCallback
tsIPByIPPort map[netaddr.IPPort]netaddr.IP // allows registration of IP:ports as belonging to a certain Tailscale IP for whois lookups
pongCallback map[[8]byte]func(packet.TSMPPongReply) // for TSMP pong responses
// Lock ordering: magicsock.Conn.mu, wgLock, then mu.
}
// InternalsGetter is implemented by Engines that can export their internals.
type InternalsGetter interface {
GetInternals() (_ *tstun.Wrapper, _ *magicsock.Conn, ok bool)
}
func (e *userspaceEngine) GetInternals() (_ *tstun.Wrapper, _ *magicsock.Conn, ok bool) {
return e.tundev, e.magicConn, true
}
// BIRDClient handles communication with the BIRD Internet Routing Daemon.
type BIRDClient interface {
EnableProtocol(proto string) error
DisableProtocol(proto string) error
Close() error
}
// Config is the engine configuration.
type Config struct {
// Tun is the device used by the Engine to exchange packets with
// the OS.
// If nil, a fake Device that does nothing is used.
Tun tun.Device
// IsTAP is whether Tun is actually a TAP (Layer 2) device that'll
// require ethernet headers.
IsTAP bool
// Router interfaces the Engine to the OS network stack.
// If nil, a fake Router that does nothing is used.
Router router.Router
// DNS interfaces the Engine to the OS DNS resolver configuration.
// If nil, a fake OSConfigurator that does nothing is used.
DNS dns.OSConfigurator
// LinkMonitor optionally provides an existing link monitor to re-use.
// If nil, a new link monitor is created.
LinkMonitor *monitor.Mon
// ListenPort is the port on which the engine will listen.
// If zero, a port is automatically selected.
ListenPort uint16
// RespondToPing determines whether this engine should internally
// reply to ICMP pings, without involving the OS.
// Used in "fake" mode for development.
RespondToPing bool
// BIRDClient, if non-nil, will be used to configure BIRD whenever
// this node is a primary subnet router.
BIRDClient BIRDClient
}
func NewFakeUserspaceEngine(logf logger.Logf, listenPort uint16) (Engine, error) {
logf("Starting userspace wireguard engine (with fake TUN device)")
return NewUserspaceEngine(logf, Config{
ListenPort: listenPort,
RespondToPing: true,
})
}
// NetstackRouterType is a gross cross-package init-time registration
// from netstack to here, informing this package of netstack's router
// type.
var NetstackRouterType reflect.Type
// IsNetstackRouter reports whether e is either fully netstack based
// (without TUN) or is at least using netstack for routing.
func IsNetstackRouter(e Engine) bool {
switch e := e.(type) {
case *userspaceEngine:
if reflect.TypeOf(e.router) == NetstackRouterType {
return true
}
case *watchdogEngine:
return IsNetstackRouter(e.wrap)
}
return IsNetstack(e)
}
// IsNetstack reports whether e is a netstack-based TUN-free engine.
func IsNetstack(e Engine) bool {
ig, ok := e.(InternalsGetter)
if !ok {
return false
}
tw, _, ok := ig.GetInternals()
if !ok {
return false
}
name, err := tw.Name()
return err == nil && name == "FakeTUN"
}
// NewUserspaceEngine creates the named tun device and returns a
// Tailscale Engine running on it.
func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error) {
var closePool closeOnErrorPool
defer closePool.closeAllIfError(&reterr)
if conf.Tun == nil {
logf("[v1] using fake (no-op) tun device")
conf.Tun = tstun.NewFake()
}
if conf.Router == nil {
logf("[v1] using fake (no-op) OS network configurator")
conf.Router = router.NewFake(logf)
}
if conf.DNS == nil {
logf("[v1] using fake (no-op) DNS configurator")
d, err := dns.NewNoopManager()
if err != nil {
return nil, err
}
conf.DNS = d
}
var tsTUNDev *tstun.Wrapper
if conf.IsTAP {
tsTUNDev = tstun.WrapTAP(logf, conf.Tun)
} else {
tsTUNDev = tstun.Wrap(logf, conf.Tun)
}
closePool.add(tsTUNDev)
e := &userspaceEngine{
timeNow: mono.Now,
logf: logf,
reqCh: make(chan struct{}, 1),
waitCh: make(chan struct{}),
tundev: tsTUNDev,
router: conf.Router,
confListenPort: conf.ListenPort,
birdClient: conf.BIRDClient,
}
if e.birdClient != nil {
// Disable the protocol at start time.
if err := e.birdClient.DisableProtocol("tailscale"); err != nil {
return nil, err
}
}
e.isLocalAddr.Store(tsaddr.NewContainsIPFunc(nil))
e.isDNSIPOverTailscale.Store(tsaddr.NewContainsIPFunc(nil))
if conf.LinkMonitor != nil {
e.linkMon = conf.LinkMonitor
} else {
mon, err := monitor.New(logf)
if err != nil {
return nil, err
}
closePool.add(mon)
e.linkMon = mon
e.linkMonOwned = true
}
tunName, _ := conf.Tun.Name()
e.dns = dns.NewManager(logf, conf.DNS, e.linkMon, fwdDNSLinkSelector{e, tunName})
logf("link state: %+v", e.linkMon.InterfaceState())
unregisterMonWatch := e.linkMon.RegisterChangeCallback(func(changed bool, st *interfaces.State) {
tshttpproxy.InvalidateCache()
e.linkChange(changed, st)
})
closePool.addFunc(unregisterMonWatch)
e.linkMonUnregister = unregisterMonWatch
endpointsFn := func(endpoints []tailcfg.Endpoint) {
e.mu.Lock()
e.endpoints = append(e.endpoints[:0], endpoints...)
e.mu.Unlock()
e.RequestStatus()
}
magicsockOpts := magicsock.Options{
Logf: logf,
Port: conf.ListenPort,
EndpointsFunc: endpointsFn,
DERPActiveFunc: e.RequestStatus,
IdleFunc: e.tundev.IdleDuration,
NoteRecvActivity: e.noteRecvActivity,
LinkMonitor: e.linkMon,
}
var err error
e.magicConn, err = magicsock.NewConn(magicsockOpts)
if err != nil {
return nil, fmt.Errorf("wgengine: %v", err)
}
closePool.add(e.magicConn)
e.magicConn.SetNetworkUp(e.linkMon.InterfaceState().AnyInterfaceUp())
if conf.RespondToPing {
e.tundev.PostFilterIn = echoRespondToAll
}
e.tundev.PreFilterOut = e.handleLocalPackets
if debugConnectFailures() {
if e.tundev.PreFilterIn != nil {
return nil, errors.New("unexpected PreFilterIn already set")
}
e.tundev.PreFilterIn = e.trackOpenPreFilterIn
if e.tundev.PostFilterOut != nil {
return nil, errors.New("unexpected PostFilterOut already set")
}
e.tundev.PostFilterOut = e.trackOpenPostFilterOut
}
e.wgLogger = wglog.NewLogger(logf)
e.tundev.OnTSMPPongReceived = func(pong packet.TSMPPongReply) {
e.mu.Lock()
defer e.mu.Unlock()
cb := e.pongCallback[pong.Data]
e.logf("wgengine: got TSMP pong %02x, peerAPIPort=%v; cb=%v", pong.Data, pong.PeerAPIPort, cb != nil)
if cb != nil {
go cb(pong)
}
}
// wgdev takes ownership of tundev, will close it when closed.
e.logf("Creating wireguard device...")
e.wgdev = device.NewDevice(e.tundev, e.magicConn.Bind(), e.wgLogger.DeviceLogger)
closePool.addFunc(e.wgdev.Close)
closePool.addFunc(func() {
if err := e.magicConn.Close(); err != nil {
e.logf("error closing magicconn: %v", err)
}
})
go func() {
up := false
for event := range e.tundev.EventsUpDown() {
if event&tun.EventUp != 0 && !up {
e.logf("external route: up")
e.RequestStatus()
up = true
}
if event&tun.EventDown != 0 && up {
e.logf("external route: down")
e.RequestStatus()
up = false
}
}
}()
e.logf("Bringing wireguard device up...")
e.wgdev.Up()
e.logf("Bringing router up...")
if err := e.router.Up(); err != nil {
return nil, err
}
// It's a little pointless to apply no-op settings here (they
// should already be empty?), but it at least exercises the
// router implementation early on.
e.logf("Clearing router settings...")
if err := e.router.Set(nil); err != nil {
return nil, err
}
e.logf("Starting link monitor...")
e.linkMon.Start()
go e.pollResolver()
e.logf("Engine created.")
return e, nil
}
// echoRespondToAll is an inbound post-filter responding to all echo requests.
func echoRespondToAll(p *packet.Parsed, t *tstun.Wrapper) filter.Response {
if p.IsEchoRequest() {
header := p.ICMP4Header()
header.ToResponse()
outp := packet.Generate(&header, p.Payload())
t.InjectOutbound(outp)
// We already responded to it, but it's not an error.
// Proceed with regular delivery. (Since this code is only
// used in fake mode, regular delivery just means throwing
// it away. If this ever gets run in non-fake mode, you'll
// get double responses to pings, which is an indicator you
// shouldn't be doing that I guess.)
return filter.Accept
}
return filter.Accept
}
// handleLocalPackets inspects packets coming from the local network
// stack, and intercepts any packets that should be handled by
// tailscaled directly. Other packets are allowed to proceed into the
// main ACL filter.
func (e *userspaceEngine) handleLocalPackets(p *packet.Parsed, t *tstun.Wrapper) filter.Response {
if verdict := e.handleDNS(p, t); verdict == filter.Drop {
// local DNS handled the packet.
return filter.Drop
}
if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
isLocalAddr, ok := e.isLocalAddr.Load().(func(netaddr.IP) bool)
if !ok {
e.logf("[unexpected] e.isLocalAddr was nil, can't check for loopback packet")
} else if isLocalAddr(p.Dst.IP()) {
// macOS NetworkExtension directs packets destined to the
// tunnel's local IP address into the tunnel, instead of
// looping back within the kernel network stack. We have to
// notice that an outbound packet is actually destined for
// ourselves, and loop it back into macOS.
t.InjectInboundCopy(p.Buffer())
return filter.Drop
}
}
return filter.Accept
}
// handleDNS is an outbound pre-filter resolving Tailscale domains.
func (e *userspaceEngine) handleDNS(p *packet.Parsed, t *tstun.Wrapper) filter.Response {
if p.Dst.IP() == magicDNSIP && p.Dst.Port() == magicDNSPort && p.IPProto == ipproto.UDP {
err := e.dns.EnqueueRequest(append([]byte(nil), p.Payload()...), p.Src)
if err != nil {
e.logf("dns: enqueue: %v", err)
}
return filter.Drop
}
return filter.Accept
}
// pollResolver reads responses from the DNS resolver and injects them inbound.
func (e *userspaceEngine) pollResolver() {
for {
bs, to, err := e.dns.NextResponse()
if err == resolver.ErrClosed {
return
}
if err != nil {
e.logf("dns: error: %v", err)
continue
}
h := packet.UDP4Header{
IP4Header: packet.IP4Header{
Src: magicDNSIP,
Dst: to.IP(),
},
SrcPort: magicDNSPort,
DstPort: to.Port(),
}
hlen := h.Len()
// TODO(dmytro): avoid this allocation without importing tstun quirks into dns.
const offset = tstun.PacketStartOffset
buf := make([]byte, offset+hlen+len(bs))
copy(buf[offset+hlen:], bs)
h.Marshal(buf[offset:])
e.tundev.InjectInboundDirect(buf, offset)
}
}
var (
debugTrimWireguardEnv = os.Getenv("TS_DEBUG_TRIM_WIREGUARD")
debugTrimWireguard, _ = strconv.ParseBool(debugTrimWireguardEnv)
)
// forceFullWireguardConfig reports whether we should give wireguard
// our full network map, even for inactive peers
//
// TODO(bradfitz): remove this after our 1.0 launch; we don't want to
// enable wireguard config trimming quite yet because it just landed
// and we haven't got enough time testing it.
func forceFullWireguardConfig(numPeers int) bool {
// Did the user explicitly enable trimmming via the environment variable knob?
if debugTrimWireguardEnv != "" {
return !debugTrimWireguard
}
if opt := controlclient.TrimWGConfig(); opt != "" {
return !opt.EqualBool(true)
}
// On iOS with large networks, it's critical, so turn on trimming.
// Otherwise we run out of memory from wireguard-go goroutine stacks+buffers.
// This will be the default later for all platforms and network sizes.
if numPeers > 50 && version.OS() == "iOS" {
return false
}
return false
}
// isTrimmablePeer reports whether p is a peer that we can trim out of the
// network map.
//
// For implementation simplificy, we can only trim peers that have
// only non-subnet AllowedIPs (an IPv4 /32 or IPv6 /128), which is the
// common case for most peers. Subnet router nodes will just always be
// created in the wireguard-go config.
func isTrimmablePeer(p *wgcfg.Peer, numPeers int) bool {
if forceFullWireguardConfig(numPeers) {
return false
}
// AllowedIPs must all be single IPs, not subnets.
for _, aip := range p.AllowedIPs {
if !aip.IsSingleIP() {
return false
}
}
return true
}
// noteRecvActivity is called by magicsock when a packet has been
// received for the peer with node key nk. Magicsock calls this no
// more than every 10 seconds for a given peer.
func (e *userspaceEngine) noteRecvActivity(nk tailcfg.NodeKey) {
e.wgLock.Lock()
defer e.wgLock.Unlock()
if _, ok := e.recvActivityAt[nk]; !ok {
// Not a trimmable peer we care about tracking. (See isTrimmablePeer)
if e.trimmedNodes[nk] {
e.logf("wgengine: [unexpected] noteReceiveActivity called on idle node %v that's not in recvActivityAt", nk.ShortString())
}
return
}
now := e.timeNow()
e.recvActivityAt[nk] = now
// As long as there's activity, periodically poll the engine to get
// stats for the far away side effect of
// ipn/ipnlocal.LocalBackend.parseWgStatusLocked to log activity, for
// use in various admin dashboards.
// This particularly matters on platforms without a connected GUI, as
// the GUIs generally poll this enough to cause that logging. But
// tailscaled alone did not, hence this.
if e.lastStatusPollTime.IsZero() || now.Sub(e.lastStatusPollTime) >= statusPollInterval {
e.lastStatusPollTime = now
go e.RequestStatus()
}
// If the last activity time jumped a bunch (say, at least
// half the idle timeout) then see if we need to reprogram
// Wireguard. This could probably be just
// lazyPeerIdleThreshold without the divide by 2, but
// maybeReconfigWireguardLocked is cheap enough to call every
// couple minutes (just not on every packet).
if e.trimmedNodes[nk] {
e.logf("wgengine: idle peer %v now active, reconfiguring wireguard", nk.ShortString())
e.maybeReconfigWireguardLocked(nil)
}
}
// isActiveSinceLocked reports whether the peer identified by (nk, ip)
// has had a packet sent to or received from it since t.
//
// e.wgLock must be held.
func (e *userspaceEngine) isActiveSinceLocked(nk tailcfg.NodeKey, ip netaddr.IP, t mono.Time) bool {
if e.recvActivityAt[nk].After(t) {
return true
}
timePtr, ok := e.sentActivityAt[ip]
if !ok {
return false
}
return timePtr.LoadAtomic().After(t)
}
// discoChanged are the set of peers whose disco keys have changed, implying they've restarted.
// If a peer is in this set and was previously in the live wireguard config,
// it needs to be first removed and then re-added to flush out its wireguard session key.
// If discoChanged is nil or empty, this extra removal step isn't done.
//
// e.wgLock must be held.
func (e *userspaceEngine) maybeReconfigWireguardLocked(discoChanged map[tailcfg.NodeKey]bool) error {
if hook := e.testMaybeReconfigHook; hook != nil {
hook()
return nil
}
full := e.lastCfgFull
e.wgLogger.SetPeers(full.Peers)
// Compute a minimal config to pass to wireguard-go
// based on the full config. Prune off all the peers
// and only add the active ones back.
min := full
min.Peers = make([]wgcfg.Peer, 0, e.lastNMinPeers)
// We'll only keep a peer around if it's been active in
// the past 5 minutes. That's more than WireGuard's key
// rotation time anyway so it's no harm if we remove it
// later if it's been inactive.
activeCutoff := e.timeNow().Add(-lazyPeerIdleThreshold)
// Not all peers can be trimmed from the network map (see
// isTrimmablePeer). For those are are trimmable, keep track of
// their NodeKey and Tailscale IPs. These are the ones we'll need
// to install tracking hooks for to watch their send/receive
// activity.
trackNodes := make([]tailcfg.NodeKey, 0, len(full.Peers))
trackIPs := make([]netaddr.IP, 0, len(full.Peers))
trimmedNodes := map[tailcfg.NodeKey]bool{} // TODO: don't re-alloc this map each time
needRemoveStep := false
for i := range full.Peers {
p := &full.Peers[i]
nk := tailcfg.NodeKey(p.PublicKey)
if !isTrimmablePeer(p, len(full.Peers)) {
min.Peers = append(min.Peers, *p)
if discoChanged[nk] {
needRemoveStep = true
}
continue
}
trackNodes = append(trackNodes, nk)
recentlyActive := false
for _, cidr := range p.AllowedIPs {
trackIPs = append(trackIPs, cidr.IP())
recentlyActive = recentlyActive || e.isActiveSinceLocked(nk, cidr.IP(), activeCutoff)
}
if recentlyActive {
min.Peers = append(min.Peers, *p)
if discoChanged[tailcfg.NodeKey(p.PublicKey)] {
needRemoveStep = true
}
} else {
trimmedNodes[tailcfg.NodeKey(p.PublicKey)] = true
}
}
e.lastNMinPeers = len(min.Peers)
if !deephash.Update(&e.lastEngineSigTrim, &min, trimmedNodes, trackNodes, trackIPs) {
// No changes
return nil
}
e.trimmedNodes = trimmedNodes
e.updateActivityMapsLocked(trackNodes, trackIPs)
if needRemoveStep {
minner := min
minner.Peers = nil
numRemove := 0
for _, p := range min.Peers {
if discoChanged[tailcfg.NodeKey(p.PublicKey)] {
numRemove++
continue
}
minner.Peers = append(minner.Peers, p)
}
if numRemove > 0 {
e.logf("wgengine: Reconfig: removing session keys for %d peers", numRemove)
if err := wgcfg.ReconfigDevice(e.wgdev, &minner, e.logf); err != nil {
e.logf("wgdev.Reconfig: %v", err)
return err
}
}
}
e.logf("wgengine: Reconfig: configuring userspace wireguard config (with %d/%d peers)", len(min.Peers), len(full.Peers))
if err := wgcfg.ReconfigDevice(e.wgdev, &min, e.logf); err != nil {
e.logf("wgdev.Reconfig: %v", err)
return err
}
return nil
}
// updateActivityMapsLocked updates the data structures used for tracking the activity
// of wireguard peers that we might add/remove dynamically from the real config
// as given to wireguard-go.
//
// e.wgLock must be held.
func (e *userspaceEngine) updateActivityMapsLocked(trackNodes []tailcfg.NodeKey, trackIPs []netaddr.IP) {
// Generate the new map of which nodekeys we want to track
// receive times for.
mr := map[tailcfg.NodeKey]mono.Time{} // TODO: only recreate this if set of keys changed
for _, nk := range trackNodes {
// Preserve old times in the new map, but also
// populate map entries for new trackNodes values with
// time.Time{} zero values. (Only entries in this map
// are tracked, so the Time zero values allow it to be
// tracked later)
mr[nk] = e.recvActivityAt[nk]
}
e.recvActivityAt = mr
oldTime := e.sentActivityAt
e.sentActivityAt = make(map[netaddr.IP]*mono.Time, len(oldTime))
oldFunc := e.destIPActivityFuncs
e.destIPActivityFuncs = make(map[netaddr.IP]func(), len(oldFunc))
updateFn := func(timePtr *mono.Time) func() {
return func() {
now := e.timeNow()
old := timePtr.LoadAtomic()
// How long's it been since we last sent a packet?
elapsed := now.Sub(old)
if old == 0 {
// For our first packet, old is 0, which has indeterminate meaning.
// Set elapsed to a big number (four score and seven years).
elapsed = 762642 * time.Hour
}
if elapsed >= packetSendTimeUpdateFrequency {
timePtr.StoreAtomic(now)
}
// On a big jump, assume we might no longer be in the wireguard
// config and go check.
if elapsed >= packetSendRecheckWireguardThreshold {
e.wgLock.Lock()
defer e.wgLock.Unlock()
e.maybeReconfigWireguardLocked(nil)
}
}
}
for _, ip := range trackIPs {
timePtr := oldTime[ip]
if timePtr == nil {
timePtr = new(mono.Time)
}
e.sentActivityAt[ip] = timePtr
fn := oldFunc[ip]
if fn == nil {
fn = updateFn(timePtr)
}
e.destIPActivityFuncs[ip] = fn
}
e.tundev.SetDestIPActivityFuncs(e.destIPActivityFuncs)
}
// hasOverlap checks if there is a IPPrefix which is common amongst the two
// provided slices.
func hasOverlap(aips, rips []netaddr.IPPrefix) bool {
for _, aip := range aips {
for _, rip := range rips {
if aip == rip {
return true
}
}
}
return false
}
func (e *userspaceEngine) Reconfig(cfg *wgcfg.Config, routerCfg *router.Config, dnsCfg *dns.Config, debug *tailcfg.Debug) error {
if routerCfg == nil {
panic("routerCfg must not be nil")
}
if dnsCfg == nil {
panic("dnsCfg must not be nil")
}
e.isLocalAddr.Store(tsaddr.NewContainsIPFunc(routerCfg.LocalAddrs))
e.wgLock.Lock()
defer e.wgLock.Unlock()
e.lastDNSConfig = dnsCfg
peerSet := make(map[key.Public]struct{}, len(cfg.Peers))
e.mu.Lock()
e.peerSequence = e.peerSequence[:0]
for _, p := range cfg.Peers {
e.peerSequence = append(e.peerSequence, wgkey.Key(p.PublicKey))
peerSet[key.Public(p.PublicKey)] = struct{}{}
}
e.mu.Unlock()
listenPort := e.confListenPort
if debug != nil && debug.RandomizeClientPort {
listenPort = 0
}
isSubnetRouter := false
if e.birdClient != nil {
isSubnetRouter = hasOverlap(e.netMap.SelfNode.PrimaryRoutes, e.netMap.Hostinfo.RoutableIPs)
}
isSubnetRouterChanged := isSubnetRouter != e.lastIsSubnetRouter
engineChanged := deephash.Update(&e.lastEngineSigFull, cfg)
routerChanged := deephash.Update(&e.lastRouterSig, routerCfg, dnsCfg)
if !engineChanged && !routerChanged && listenPort == e.magicConn.LocalPort() && !isSubnetRouterChanged {
return ErrNoChanges
}
// TODO(bradfitz,danderson): maybe delete this isDNSIPOverTailscale
// field and delete the resolver.ForwardLinkSelector hook and
// instead have ipnlocal populate a map of DNS IP => linkName and
// put that in the *dns.Config instead, and plumb it down to the
// dns.Manager. Maybe also with isLocalAddr above.
e.isDNSIPOverTailscale.Store(tsaddr.NewContainsIPFunc(dnsIPsOverTailscale(dnsCfg, routerCfg)))
// See if any peers have changed disco keys, which means they've restarted.
// If so, we need to update the wireguard-go/device.Device in two phases:
// once without the node which has restarted, to clear its wireguard session key,
// and a second time with it.
discoChanged := make(map[tailcfg.NodeKey]bool)
{
prevEP := make(map[tailcfg.NodeKey]tailcfg.DiscoKey)
for i := range e.lastCfgFull.Peers {
if p := &e.lastCfgFull.Peers[i]; !p.DiscoKey.IsZero() {
prevEP[tailcfg.NodeKey(p.PublicKey)] = p.DiscoKey
}
}
for i := range cfg.Peers {
p := &cfg.Peers[i]
if p.DiscoKey.IsZero() {
continue
}
pub := tailcfg.NodeKey(p.PublicKey)
if old, ok := prevEP[pub]; ok && old != p.DiscoKey {
discoChanged[pub] = true
e.logf("wgengine: Reconfig: %s changed from %q to %q", pub.ShortString(), old, p.DiscoKey)
}
}
}
e.lastCfgFull = *cfg.Clone()
// Tell magicsock about the new (or initial) private key
// (which is needed by DERP) before wgdev gets it, as wgdev
// will start trying to handshake, which we want to be able to
// go over DERP.
if err := e.magicConn.SetPrivateKey(wgkey.Private(cfg.PrivateKey)); err != nil {
e.logf("wgengine: Reconfig: SetPrivateKey: %v", err)
}
e.magicConn.UpdatePeers(peerSet)
e.magicConn.SetPreferredPort(listenPort)
if err := e.maybeReconfigWireguardLocked(discoChanged); err != nil {
return err
}
if routerChanged {
e.logf("wgengine: Reconfig: configuring router")
err := e.router.Set(routerCfg)
health.SetRouterHealth(err)
if err != nil {
return err
}
// Keep DNS configuration after router configuration, as some
// DNS managers refuse to apply settings if the device has no
// assigned address.
e.logf("wgengine: Reconfig: configuring DNS")
err = e.dns.Set(*dnsCfg)
health.SetDNSHealth(err)
if err != nil {
return err
}
}
if isSubnetRouterChanged && e.birdClient != nil {
e.logf("wgengine: Reconfig: configuring BIRD")
var err error
if isSubnetRouter {
err = e.birdClient.EnableProtocol("tailscale")
} else {
err = e.birdClient.DisableProtocol("tailscale")
}
if err != nil {
// Log but don't fail here.
e.logf("wgengine: error configuring BIRD: %v", err)
} else {
e.lastIsSubnetRouter = isSubnetRouter
}
}
e.logf("[v1] wgengine: Reconfig done")
return nil
}
func (e *userspaceEngine) GetFilter() *filter.Filter {
return e.tundev.GetFilter()
}
func (e *userspaceEngine) SetFilter(filt *filter.Filter) {
e.tundev.SetFilter(filt)
}
func (e *userspaceEngine) SetStatusCallback(cb StatusCallback) {
e.mu.Lock()
defer e.mu.Unlock()
e.statusCallback = cb
}
func (e *userspaceEngine) getStatusCallback() StatusCallback {
e.mu.Lock()
defer e.mu.Unlock()
return e.statusCallback
}
var singleNewline = []byte{'\n'}
var ErrEngineClosing = errors.New("engine closing; no status")
func (e *userspaceEngine) getStatus() (*Status, error) {
// Grab derpConns before acquiring wgLock to not violate lock ordering;
// the DERPs method acquires magicsock.Conn.mu.
// (See comment in userspaceEngine's declaration.)
derpConns := e.magicConn.DERPs()
e.wgLock.Lock()
defer e.wgLock.Unlock()
e.mu.Lock()
closing := e.closing
e.mu.Unlock()
if closing {
return nil, ErrEngineClosing
}
if e.wgdev == nil {
// RequestStatus was invoked before the wgengine has
// finished initializing. This can happen when wgegine
// provides a callback to magicsock for endpoint
// updates that calls RequestStatus.
return nil, nil
}
pr, pw := io.Pipe()
defer pr.Close() // to unblock writes on error path returns
errc := make(chan error, 1)
go func() {
defer pw.Close()
// TODO(apenwarr): get rid of silly uapi stuff for in-process comms
// FIXME: get notified of status changes instead of polling.
err := e.wgdev.IpcGetOperation(pw)
if err != nil {
err = fmt.Errorf("IpcGetOperation: %w", err)
}
errc <- err
}()
pp := make(map[wgkey.Key]ipnstate.PeerStatusLite)
var p ipnstate.PeerStatusLite
var hst1, hst2, n int64
br := e.statusBufioReader
if br != nil {
br.Reset(pr)
} else {
br = bufio.NewReaderSize(pr, 1<<10)
e.statusBufioReader = br
}
for {
line, err := br.ReadSlice('\n')
if err == io.EOF {
break
}
if err != nil {
return nil, fmt.Errorf("reading from UAPI pipe: %w", err)
}
line = bytes.TrimSuffix(line, singleNewline)
k := line
var v mem.RO
if i := bytes.IndexByte(line, '='); i != -1 {
k = line[:i]
v = mem.B(line[i+1:])
}
switch string(k) {
case "public_key":
pk, err := key.NewPublicFromHexMem(v)
if err != nil {
return nil, fmt.Errorf("IpcGetOperation: invalid key in line %q", line)
}
if !p.NodeKey.IsZero() {
pp[wgkey.Key(p.NodeKey)] = p
}
p = ipnstate.PeerStatusLite{NodeKey: tailcfg.NodeKey(pk)}
case "rx_bytes":
n, err = mem.ParseInt(v, 10, 64)
p.RxBytes = n
if err != nil {
return nil, fmt.Errorf("IpcGetOperation: rx_bytes invalid: %#v", line)
}
case "tx_bytes":
n, err = mem.ParseInt(v, 10, 64)
p.TxBytes = n
if err != nil {
return nil, fmt.Errorf("IpcGetOperation: tx_bytes invalid: %#v", line)
}
case "last_handshake_time_sec":
hst1, err = mem.ParseInt(v, 10, 64)
if err != nil {
return nil, fmt.Errorf("IpcGetOperation: hst1 invalid: %#v", line)
}
case "last_handshake_time_nsec":
hst2, err = mem.ParseInt(v, 10, 64)
if err != nil {
return nil, fmt.Errorf("IpcGetOperation: hst2 invalid: %#v", line)
}
if hst1 != 0 || hst2 != 0 {
p.LastHandshake = time.Unix(hst1, hst2)
} // else leave at time.IsZero()
}
}
if !p.NodeKey.IsZero() {
pp[wgkey.Key(p.NodeKey)] = p
}
if err := <-errc; err != nil {
return nil, fmt.Errorf("IpcGetOperation: %v", err)
}
e.mu.Lock()
defer e.mu.Unlock()
// Do two passes, one to calculate size and the other to populate.
// This code is sensitive to allocations.
npeers := 0
for _, pk := range e.peerSequence {
if _, ok := pp[pk]; ok { // ignore idle ones not in wireguard-go's config
npeers++
}
}
peers := make([]ipnstate.PeerStatusLite, 0, npeers)
for _, pk := range e.peerSequence {
if p, ok := pp[pk]; ok { // ignore idle ones not in wireguard-go's config
peers = append(peers, p)
}
}
return &Status{
LocalAddrs: append([]tailcfg.Endpoint(nil), e.endpoints...),
Peers: peers,
DERPs: derpConns,
}, nil
}
func (e *userspaceEngine) RequestStatus() {
// This is slightly tricky. e.getStatus() can theoretically get
// blocked inside wireguard for a while, and RequestStatus() is
// sometimes called from a goroutine, so we don't want a lot of
// them hanging around. On the other hand, requesting multiple
// status updates simultaneously is pointless anyway; they will
// all say the same thing.
// Enqueue at most one request. If one is in progress already, this
// adds one more to the queue. If one has been requested but not
// started, it is a no-op.
select {
case e.reqCh <- struct{}{}:
default:
}
// Dequeue at most one request. Another thread may have already
// dequeued the request we enqueued above, which is fine, since the
// information is guaranteed to be at least as recent as the current
// call to RequestStatus().
select {
case <-e.reqCh:
s, err := e.getStatus()
if s == nil && err == nil {
e.logf("[unexpected] RequestStatus: both s and err are nil")
return
}
if cb := e.getStatusCallback(); cb != nil {
cb(s, err)
}
default:
}
}
func (e *userspaceEngine) Close() {
e.mu.Lock()
if e.closing {
e.mu.Unlock()
return
}
e.closing = true
e.mu.Unlock()
r := bufio.NewReader(strings.NewReader(""))
e.wgdev.IpcSetOperation(r)
e.magicConn.Close()
e.linkMonUnregister()
if e.linkMonOwned {
e.linkMon.Close()
}
e.dns.Down()
e.router.Close()
e.wgdev.Close()
e.tundev.Close()
if e.birdClient != nil {
e.birdClient.DisableProtocol("tailscale")
e.birdClient.Close()
}
close(e.waitCh)
}
func (e *userspaceEngine) Wait() {
<-e.waitCh
}
func (e *userspaceEngine) GetLinkMonitor() *monitor.Mon {
return e.linkMon
}
// LinkChange signals a network change event. It's currently
// (2021-03-03) only called on Android.
func (e *userspaceEngine) LinkChange(_ bool) {
e.linkMon.InjectEvent()
}
func (e *userspaceEngine) linkChange(changed bool, cur *interfaces.State) {
up := cur.AnyInterfaceUp()
if !up {
e.logf("LinkChange: all links down; pausing: %v", cur)
} else if changed {
e.logf("LinkChange: major, rebinding. New state: %v", cur)
} else {
e.logf("[v1] LinkChange: minor")
}
health.SetAnyInterfaceUp(up)
e.magicConn.SetNetworkUp(up)
// Hacky workaround for Linux DNS issue 2458: on
// suspend/resume or whenever NetworkManager is started, it
// nukes all systemd-resolved configs. So reapply our DNS
// config on major link change.
if runtime.GOOS == "linux" && changed {
e.wgLock.Lock()
dnsCfg := e.lastDNSConfig
e.wgLock.Unlock()
if dnsCfg != nil {
if err := e.dns.Set(*dnsCfg); err != nil {
e.logf("wgengine: error setting DNS config after major link change: %v", err)
} else {
e.logf("wgengine: set DNS config again after major link change")
}
}
}
why := "link-change-minor"
if changed {
why = "link-change-major"
e.magicConn.Rebind()
}
e.magicConn.ReSTUN(why)
}
func (e *userspaceEngine) AddNetworkMapCallback(cb NetworkMapCallback) func() {
e.mu.Lock()
defer e.mu.Unlock()
if e.networkMapCallbacks == nil {
e.networkMapCallbacks = make(map[*someHandle]NetworkMapCallback)
}
h := new(someHandle)
e.networkMapCallbacks[h] = cb
return func() {
e.mu.Lock()
defer e.mu.Unlock()
delete(e.networkMapCallbacks, h)
}
}
func (e *userspaceEngine) SetNetInfoCallback(cb NetInfoCallback) {
e.magicConn.SetNetInfoCallback(cb)
}
func (e *userspaceEngine) SetDERPMap(dm *tailcfg.DERPMap) {
e.magicConn.SetDERPMap(dm)
}
func (e *userspaceEngine) SetNetworkMap(nm *netmap.NetworkMap) {
e.magicConn.SetNetworkMap(nm)
e.mu.Lock()
e.netMap = nm
callbacks := make([]NetworkMapCallback, 0, 4)
for _, fn := range e.networkMapCallbacks {
callbacks = append(callbacks, fn)
}
e.mu.Unlock()
for _, fn := range callbacks {
fn(nm)
}
}
func (e *userspaceEngine) DiscoPublicKey() tailcfg.DiscoKey {
return e.magicConn.DiscoPublicKey()
}
func (e *userspaceEngine) UpdateStatus(sb *ipnstate.StatusBuilder) {
st, err := e.getStatus()
if err != nil {
e.logf("wgengine: getStatus: %v", err)
return
}
for _, ps := range st.Peers {
sb.AddPeer(key.Public(ps.NodeKey), &ipnstate.PeerStatus{
RxBytes: int64(ps.RxBytes),
TxBytes: int64(ps.TxBytes),
LastHandshake: ps.LastHandshake,
InEngine: true,
})
}
e.magicConn.UpdateStatus(sb)
}
func (e *userspaceEngine) Ping(ip netaddr.IP, useTSMP bool, cb func(*ipnstate.PingResult)) {
res := &ipnstate.PingResult{IP: ip.String()}
peer, err := e.peerForIP(ip)
if err != nil {
e.logf("ping(%v): %v", ip, err)
res.Err = err.Error()
cb(res)
return
}
if peer == nil {
e.logf("ping(%v): no matching peer", ip)
res.Err = "no matching peer"
cb(res)
return
}
pingType := "disco"
if useTSMP {
pingType = "TSMP"
}
e.logf("ping(%v): sending %v ping to %v %v ...", ip, pingType, peer.Key.ShortString(), peer.ComputedName)
if useTSMP {
e.sendTSMPPing(ip, peer, res, cb)
} else {
e.magicConn.Ping(peer, res, cb)
}
}
func (e *userspaceEngine) mySelfIPMatchingFamily(dst netaddr.IP) (src netaddr.IP, err error) {
e.mu.Lock()
defer e.mu.Unlock()
if e.netMap == nil {
return netaddr.IP{}, errors.New("no netmap")
}
for _, a := range e.netMap.Addresses {
if a.IsSingleIP() && a.IP().BitLen() == dst.BitLen() {
return a.IP(), nil
}
}
if len(e.netMap.Addresses) == 0 {
return netaddr.IP{}, errors.New("no self address in netmap")
}
return netaddr.IP{}, errors.New("no self address in netmap matching address family")
}
func (e *userspaceEngine) sendTSMPPing(ip netaddr.IP, peer *tailcfg.Node, res *ipnstate.PingResult, cb func(*ipnstate.PingResult)) {
srcIP, err := e.mySelfIPMatchingFamily(ip)
if err != nil {
res.Err = err.Error()
cb(res)
return
}
var iph packet.Header
if srcIP.Is4() {
iph = packet.IP4Header{
IPProto: ipproto.TSMP,
Src: srcIP,
Dst: ip,
}
} else {
iph = packet.IP6Header{
IPProto: ipproto.TSMP,
Src: srcIP,
Dst: ip,
}
}
var data [8]byte
crand.Read(data[:])
expireTimer := time.AfterFunc(10*time.Second, func() {
e.setTSMPPongCallback(data, nil)
})
t0 := time.Now()
e.setTSMPPongCallback(data, func(pong packet.TSMPPongReply) {
expireTimer.Stop()
d := time.Since(t0)
res.LatencySeconds = d.Seconds()
res.NodeIP = ip.String()
res.NodeName = peer.ComputedName
res.PeerAPIPort = pong.PeerAPIPort
cb(res)
})
var tsmpPayload [9]byte
tsmpPayload[0] = byte(packet.TSMPTypePing)
copy(tsmpPayload[1:], data[:])
tsmpPing := packet.Generate(iph, tsmpPayload[:])
e.tundev.InjectOutbound(tsmpPing)
}
func (e *userspaceEngine) setTSMPPongCallback(data [8]byte, cb func(packet.TSMPPongReply)) {
e.mu.Lock()
defer e.mu.Unlock()
if e.pongCallback == nil {
e.pongCallback = map[[8]byte]func(packet.TSMPPongReply){}
}
if cb == nil {
delete(e.pongCallback, data)
} else {
e.pongCallback[data] = cb
}
}
func (e *userspaceEngine) RegisterIPPortIdentity(ipport netaddr.IPPort, tsIP netaddr.IP) {
e.mu.Lock()
defer e.mu.Unlock()
if e.tsIPByIPPort == nil {
e.tsIPByIPPort = make(map[netaddr.IPPort]netaddr.IP)
}
e.tsIPByIPPort[ipport] = tsIP
}
func (e *userspaceEngine) UnregisterIPPortIdentity(ipport netaddr.IPPort) {
e.mu.Lock()
defer e.mu.Unlock()
if e.tsIPByIPPort == nil {
return
}
delete(e.tsIPByIPPort, ipport)
}
var whoIsSleeps = [...]time.Duration{
0,
10 * time.Millisecond,
20 * time.Millisecond,
50 * time.Millisecond,
100 * time.Millisecond,
}
func (e *userspaceEngine) WhoIsIPPort(ipport netaddr.IPPort) (tsIP netaddr.IP, ok bool) {
// We currently have a registration race,
// https://github.com/tailscale/tailscale/issues/1616,
// so loop a few times for now waiting for the registration
// to appear.
// TODO(bradfitz,namansood): remove this once #1616 is fixed.
for _, d := range whoIsSleeps {
time.Sleep(d)
e.mu.Lock()
tsIP, ok = e.tsIPByIPPort[ipport]
e.mu.Unlock()
if ok {
return tsIP, true
}
}
return tsIP, false
}
// peerForIP returns the Node in the wireguard config
// that's responsible for handling the given IP address.
//
// If none is found in the wireguard config but one is found in
// the netmap, it's described in an error.
//
// If none is found in either place, (nil, nil) is returned.
//
// peerForIP acquires both e.mu and e.wgLock, but neither at the same
// time.
func (e *userspaceEngine) peerForIP(ip netaddr.IP) (n *tailcfg.Node, err error) {
e.mu.Lock()
nm := e.netMap
e.mu.Unlock()
if nm == nil {
return nil, errors.New("no network map")
}
// Check for exact matches before looking for subnet matches.
var bestInNMPrefix netaddr.IPPrefix
var bestInNM *tailcfg.Node
for _, p := range nm.Peers {
for _, a := range p.Addresses {
if a.IP() == ip && a.IsSingleIP() && tsaddr.IsTailscaleIP(ip) {
return p, nil
}
}
for _, cidr := range p.AllowedIPs {
if !cidr.Contains(ip) {
continue
}
if bestInNMPrefix.IsZero() || cidr.Bits() > bestInNMPrefix.Bits() {
bestInNMPrefix = cidr
bestInNM = p
}
}
}
e.wgLock.Lock()
defer e.wgLock.Unlock()
// TODO(bradfitz): this is O(n peers). Add ART to netaddr?
var best netaddr.IPPrefix
var bestKey tailcfg.NodeKey
for _, p := range e.lastCfgFull.Peers {
for _, cidr := range p.AllowedIPs {
if !cidr.Contains(ip) {
continue
}
if best.IsZero() || cidr.Bits() > best.Bits() {
best = cidr
bestKey = tailcfg.NodeKey(p.PublicKey)
}
}
}
// And another pass. Probably better than allocating a map per peerForIP
// call. But TODO(bradfitz): add a lookup map to netmap.NetworkMap.
if !bestKey.IsZero() {
for _, p := range nm.Peers {
if p.Key == bestKey {
return p, nil
}
}
}
if bestInNM == nil {
return nil, nil
}
if bestInNMPrefix.Bits() == 0 {
return nil, errors.New("exit node found but not enabled")
}
return nil, fmt.Errorf("node %q found, but not using its %v route", bestInNM.ComputedNameWithHost, bestInNMPrefix)
}
type closeOnErrorPool []func()
func (p *closeOnErrorPool) add(c io.Closer) { *p = append(*p, func() { c.Close() }) }
func (p *closeOnErrorPool) addFunc(fn func()) { *p = append(*p, fn) }
func (p closeOnErrorPool) closeAllIfError(errp *error) {
if *errp != nil {
for _, closeFn := range p {
closeFn()
}
}
}
// ipInPrefixes reports whether ip is in any of pp.
func ipInPrefixes(ip netaddr.IP, pp []netaddr.IPPrefix) bool {
for _, p := range pp {
if p.Contains(ip) {
return true
}
}
return false
}
// dnsIPsOverTailscale returns the IPPrefixes of DNS resolver IPs that are
// routed over Tailscale. The returned value does not contain duplicates is
// not necessarily sorted.
func dnsIPsOverTailscale(dnsCfg *dns.Config, routerCfg *router.Config) (ret []netaddr.IPPrefix) {
m := map[netaddr.IP]bool{}
add := func(resolvers []netaddr.IPPort) {
for _, resolver := range resolvers {
ip := resolver.IP()
if ipInPrefixes(ip, routerCfg.Routes) && !ipInPrefixes(ip, routerCfg.LocalRoutes) {
m[ip] = true
}
}
}
add(dnsCfg.DefaultResolvers)
for _, resolvers := range dnsCfg.Routes {
add(resolvers)
}
ret = make([]netaddr.IPPrefix, 0, len(m))
for ip := range m {
ret = append(ret, netaddr.IPPrefixFrom(ip, ip.BitLen()))
}
return ret
}
// fwdDNSLinkSelector is userspaceEngine's resolver.ForwardLinkSelector, to pick
// which network interface to send DNS queries out of.
type fwdDNSLinkSelector struct {
ue *userspaceEngine
tunName string
}
func (ls fwdDNSLinkSelector) PickLink(ip netaddr.IP) (linkName string) {
if ls.ue.isDNSIPOverTailscale.Load().(func(netaddr.IP) bool)(ip) {
return ls.tunName
}
return ""
}