wireguard-go/device/device.go
Josh Bleecher Snyder 63066ce406 device: fix persistent_keepalive_interval data races
Co-authored-by: David Anderson <danderson@tailscale.com>
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2021-01-07 14:49:44 +01:00

562 lines
11 KiB
Go

/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2020 WireGuard LLC. All Rights Reserved.
*/
package device
import (
"runtime"
"sync"
"sync/atomic"
"time"
"golang.org/x/net/ipv4"
"golang.org/x/net/ipv6"
"golang.zx2c4.com/wireguard/conn"
"golang.zx2c4.com/wireguard/ratelimiter"
"golang.zx2c4.com/wireguard/rwcancel"
"golang.zx2c4.com/wireguard/tun"
)
type Device struct {
isUp AtomicBool // device is (going) up
isClosed AtomicBool // device is closed? (acting as guard)
log *Logger
// synchronized resources (locks acquired in order)
state struct {
stopping sync.WaitGroup
sync.Mutex
changing AtomicBool
current bool
}
net struct {
stopping sync.WaitGroup
sync.RWMutex
bind conn.Bind // bind interface
netlinkCancel *rwcancel.RWCancel
port uint16 // listening port
fwmark uint32 // mark value (0 = disabled)
}
staticIdentity struct {
sync.RWMutex
privateKey NoisePrivateKey
publicKey NoisePublicKey
}
peers struct {
sync.RWMutex
keyMap map[NoisePublicKey]*Peer
}
// unprotected / "self-synchronising resources"
allowedips AllowedIPs
indexTable IndexTable
cookieChecker CookieChecker
rate struct {
underLoadUntil atomic.Value
limiter ratelimiter.Ratelimiter
}
pool struct {
messageBufferPool *sync.Pool
messageBufferReuseChan chan *[MaxMessageSize]byte
inboundElementPool *sync.Pool
inboundElementReuseChan chan *QueueInboundElement
outboundElementPool *sync.Pool
outboundElementReuseChan chan *QueueOutboundElement
}
queue struct {
encryption *encryptionQueue
decryption chan *QueueInboundElement
handshake chan QueueHandshakeElement
}
signals struct {
stop chan struct{}
}
tun struct {
device tun.Device
mtu int32
}
}
// An encryptionQueue is a channel of QueueOutboundElements awaiting encryption.
// An encryptionQueue is ref-counted using its wg field.
// An encryptionQueue created with newEncryptionQueue has one reference.
// Every additional writer must call wg.Add(1).
// Every completed writer must call wg.Done().
// When no further writers will be added,
// call wg.Done to remove the initial reference.
// When the refcount hits 0, the queue's channel is closed.
type encryptionQueue struct {
c chan *QueueOutboundElement
wg sync.WaitGroup
}
func newEncryptionQueue() *encryptionQueue {
q := &encryptionQueue{
c: make(chan *QueueOutboundElement, QueueOutboundSize),
}
q.wg.Add(1)
go func() {
q.wg.Wait()
close(q.c)
}()
return q
}
/* Converts the peer into a "zombie", which remains in the peer map,
* but processes no packets and does not exists in the routing table.
*
* Must hold device.peers.Mutex
*/
func unsafeRemovePeer(device *Device, peer *Peer, key NoisePublicKey) {
// stop routing and processing of packets
device.allowedips.RemoveByPeer(peer)
peer.Stop()
// remove from peer map
delete(device.peers.keyMap, key)
}
func deviceUpdateState(device *Device) {
// check if state already being updated (guard)
if device.state.changing.Swap(true) {
return
}
// compare to current state of device
device.state.Lock()
newIsUp := device.isUp.Get()
if newIsUp == device.state.current {
device.state.changing.Set(false)
device.state.Unlock()
return
}
// change state of device
switch newIsUp {
case true:
if err := device.BindUpdate(); err != nil {
device.log.Error.Printf("Unable to update bind: %v\n", err)
device.isUp.Set(false)
break
}
device.peers.RLock()
for _, peer := range device.peers.keyMap {
peer.Start()
if atomic.LoadUint32(&peer.persistentKeepaliveInterval) > 0 {
peer.SendKeepalive()
}
}
device.peers.RUnlock()
case false:
device.BindClose()
device.peers.RLock()
for _, peer := range device.peers.keyMap {
peer.Stop()
}
device.peers.RUnlock()
}
// update state variables
device.state.current = newIsUp
device.state.changing.Set(false)
device.state.Unlock()
// check for state change in the mean time
deviceUpdateState(device)
}
func (device *Device) Up() {
// closed device cannot be brought up
if device.isClosed.Get() {
return
}
device.isUp.Set(true)
deviceUpdateState(device)
}
func (device *Device) Down() {
device.isUp.Set(false)
deviceUpdateState(device)
}
func (device *Device) IsUnderLoad() bool {
// check if currently under load
now := time.Now()
underLoad := len(device.queue.handshake) >= UnderLoadQueueSize
if underLoad {
device.rate.underLoadUntil.Store(now.Add(UnderLoadAfterTime))
return true
}
// check if recently under load
until := device.rate.underLoadUntil.Load().(time.Time)
return until.After(now)
}
func (device *Device) SetPrivateKey(sk NoisePrivateKey) error {
// lock required resources
device.staticIdentity.Lock()
defer device.staticIdentity.Unlock()
if sk.Equals(device.staticIdentity.privateKey) {
return nil
}
device.peers.Lock()
defer device.peers.Unlock()
lockedPeers := make([]*Peer, 0, len(device.peers.keyMap))
for _, peer := range device.peers.keyMap {
peer.handshake.mutex.RLock()
lockedPeers = append(lockedPeers, peer)
}
// remove peers with matching public keys
publicKey := sk.publicKey()
for key, peer := range device.peers.keyMap {
if peer.handshake.remoteStatic.Equals(publicKey) {
unsafeRemovePeer(device, peer, key)
}
}
// update key material
device.staticIdentity.privateKey = sk
device.staticIdentity.publicKey = publicKey
device.cookieChecker.Init(publicKey)
// do static-static DH pre-computations
expiredPeers := make([]*Peer, 0, len(device.peers.keyMap))
for _, peer := range device.peers.keyMap {
handshake := &peer.handshake
handshake.precomputedStaticStatic = device.staticIdentity.privateKey.sharedSecret(handshake.remoteStatic)
expiredPeers = append(expiredPeers, peer)
}
for _, peer := range lockedPeers {
peer.handshake.mutex.RUnlock()
}
for _, peer := range expiredPeers {
peer.ExpireCurrentKeypairs()
}
return nil
}
func NewDevice(tunDevice tun.Device, logger *Logger) *Device {
device := new(Device)
device.isUp.Set(false)
device.isClosed.Set(false)
device.log = logger
device.tun.device = tunDevice
mtu, err := device.tun.device.MTU()
if err != nil {
logger.Error.Println("Trouble determining MTU, assuming default:", err)
mtu = DefaultMTU
}
device.tun.mtu = int32(mtu)
device.peers.keyMap = make(map[NoisePublicKey]*Peer)
device.rate.limiter.Init()
device.rate.underLoadUntil.Store(time.Time{})
device.indexTable.Init()
device.allowedips.Reset()
device.PopulatePools()
// create queues
device.queue.handshake = make(chan QueueHandshakeElement, QueueHandshakeSize)
device.queue.encryption = newEncryptionQueue()
device.queue.decryption = make(chan *QueueInboundElement, QueueInboundSize)
// prepare signals
device.signals.stop = make(chan struct{})
// prepare net
device.net.port = 0
device.net.bind = nil
// start workers
cpus := runtime.NumCPU()
device.state.stopping.Wait()
for i := 0; i < cpus; i += 1 {
device.state.stopping.Add(2) // decryption and handshake
go device.RoutineEncryption()
go device.RoutineDecryption()
go device.RoutineHandshake()
}
device.state.stopping.Add(2)
go device.RoutineReadFromTUN()
go device.RoutineTUNEventReader()
return device
}
func (device *Device) LookupPeer(pk NoisePublicKey) *Peer {
device.peers.RLock()
defer device.peers.RUnlock()
return device.peers.keyMap[pk]
}
func (device *Device) RemovePeer(key NoisePublicKey) {
device.peers.Lock()
defer device.peers.Unlock()
// stop peer and remove from routing
peer, ok := device.peers.keyMap[key]
if ok {
unsafeRemovePeer(device, peer, key)
}
}
func (device *Device) RemoveAllPeers() {
device.peers.Lock()
defer device.peers.Unlock()
for key, peer := range device.peers.keyMap {
unsafeRemovePeer(device, peer, key)
}
device.peers.keyMap = make(map[NoisePublicKey]*Peer)
}
func (device *Device) FlushPacketQueues() {
for {
select {
case elem, ok := <-device.queue.decryption:
if ok {
elem.Drop()
}
case <-device.queue.handshake:
default:
return
}
}
}
func (device *Device) Close() {
if device.isClosed.Swap(true) {
return
}
device.log.Info.Println("Device closing")
device.state.changing.Set(true)
device.state.Lock()
defer device.state.Unlock()
device.tun.device.Close()
device.BindClose()
device.isUp.Set(false)
// We kept a reference to the encryption queue,
// in case we started any new peers that might write to it.
// No new peers are coming; we are done with the encryption queue.
device.queue.encryption.wg.Done()
close(device.signals.stop)
device.state.stopping.Wait()
device.RemoveAllPeers()
device.FlushPacketQueues()
device.rate.limiter.Close()
device.state.changing.Set(false)
device.log.Info.Println("Interface closed")
}
func (device *Device) Wait() chan struct{} {
return device.signals.stop
}
func (device *Device) SendKeepalivesToPeersWithCurrentKeypair() {
if device.isClosed.Get() {
return
}
device.peers.RLock()
for _, peer := range device.peers.keyMap {
peer.keypairs.RLock()
sendKeepalive := peer.keypairs.current != nil && !peer.keypairs.current.created.Add(RejectAfterTime).Before(time.Now())
peer.keypairs.RUnlock()
if sendKeepalive {
peer.SendKeepalive()
}
}
device.peers.RUnlock()
}
func unsafeCloseBind(device *Device) error {
var err error
netc := &device.net
if netc.netlinkCancel != nil {
netc.netlinkCancel.Cancel()
}
if netc.bind != nil {
err = netc.bind.Close()
netc.bind = nil
}
netc.stopping.Wait()
return err
}
func (device *Device) Bind() conn.Bind {
device.net.Lock()
defer device.net.Unlock()
return device.net.bind
}
func (device *Device) BindSetMark(mark uint32) error {
device.net.Lock()
defer device.net.Unlock()
// check if modified
if device.net.fwmark == mark {
return nil
}
// update fwmark on existing bind
device.net.fwmark = mark
if device.isUp.Get() && device.net.bind != nil {
if err := device.net.bind.SetMark(mark); err != nil {
return err
}
}
// clear cached source addresses
device.peers.RLock()
for _, peer := range device.peers.keyMap {
peer.Lock()
defer peer.Unlock()
if peer.endpoint != nil {
peer.endpoint.ClearSrc()
}
}
device.peers.RUnlock()
return nil
}
func (device *Device) BindUpdate() error {
device.net.Lock()
defer device.net.Unlock()
// close existing sockets
if err := unsafeCloseBind(device); err != nil {
return err
}
// open new sockets
if device.isUp.Get() {
// bind to new port
var err error
netc := &device.net
netc.bind, netc.port, err = conn.CreateBind(netc.port)
if err != nil {
netc.bind = nil
netc.port = 0
return err
}
netc.netlinkCancel, err = device.startRouteListener(netc.bind)
if err != nil {
netc.bind.Close()
netc.bind = nil
netc.port = 0
return err
}
// set fwmark
if netc.fwmark != 0 {
err = netc.bind.SetMark(netc.fwmark)
if err != nil {
return err
}
}
// clear cached source addresses
device.peers.RLock()
for _, peer := range device.peers.keyMap {
peer.Lock()
defer peer.Unlock()
if peer.endpoint != nil {
peer.endpoint.ClearSrc()
}
}
device.peers.RUnlock()
// start receiving routines
device.net.stopping.Add(2)
go device.RoutineReceiveIncoming(ipv4.Version, netc.bind)
go device.RoutineReceiveIncoming(ipv6.Version, netc.bind)
device.log.Debug.Println("UDP bind has been updated")
}
return nil
}
func (device *Device) BindClose() error {
device.net.Lock()
err := unsafeCloseBind(device)
device.net.Unlock()
return err
}