EtherGuard-VPN/device/device.go
Dmytro Shynkevych 4369db522b device: wait for routines to stop before removing peers
Peers are currently removed after Device's goroutines are signaled to stop,
but without waiting for them to actually do so, which is racy.

For example, RoutineHandshake may be in Peer.SendKeepalive
when the corresponding peer is removed, which closes its nonce channel.
This causes a send on a closed channel, as observed in tailscale/tailscale#487.

This patch seems to be the correct synchronizing action:
Peer's goroutines are receivers and handle channel closure gracefully,
so Device's goroutines are the ones that should be fully stopped first.

Signed-Off-By: Dmytro Shynkevych <dmytro@tailscale.com>
2020-07-04 20:29:31 +10:00

548 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 {
starting sync.WaitGroup
stopping sync.WaitGroup
sync.Mutex
changing AtomicBool
current bool
}
net struct {
starting sync.WaitGroup
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 chan *QueueOutboundElement
decryption chan *QueueInboundElement
handshake chan QueueHandshakeElement
}
signals struct {
stop chan struct{}
}
tun struct {
device tun.Device
mtu int32
}
}
/* 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 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 = make(chan *QueueOutboundElement, QueueOutboundSize)
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.starting.Wait()
device.state.stopping.Wait()
for i := 0; i < cpus; i += 1 {
device.state.starting.Add(3)
device.state.stopping.Add(3)
go device.RoutineEncryption()
go device.RoutineDecryption()
go device.RoutineHandshake()
}
device.state.starting.Add(2)
device.state.stopping.Add(2)
go device.RoutineReadFromTUN()
go device.RoutineTUNEventReader()
device.state.starting.Wait()
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 elem, ok := <-device.queue.encryption:
if ok {
elem.Drop()
}
case <-device.queue.handshake:
default:
return
}
}
}
func (device *Device) Close() {
if device.isClosed.Swap(true) {
return
}
device.state.starting.Wait()
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)
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.starting.Add(2)
device.net.stopping.Add(2)
go device.RoutineReceiveIncoming(ipv4.Version, netc.bind)
go device.RoutineReceiveIncoming(ipv6.Version, netc.bind)
device.net.starting.Wait()
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
}