EtherGuard-VPN/device/uapi.go
Josh Bleecher Snyder 0bcb822e5b device: overhaul device state management
This commit simplifies device state management.
It creates a single unified state variable and documents its semantics.

It also makes state changes more atomic.
As an example of the sort of bug that occurred due to non-atomic state changes,
the following sequence of events used to occur approximately every 2.5 million test runs:

* RoutineTUNEventReader received an EventDown event.
* It called device.Down, which called device.setUpDown.
* That set device.state.changing, but did not yet attempt to lock device.state.Mutex.
* Test completion called device.Close.
* device.Close locked device.state.Mutex.
* device.Close blocked on a call to device.state.stopping.Wait.
* device.setUpDown then attempted to lock device.state.Mutex and blocked.

Deadlock results. setUpDown cannot progress because device.state.Mutex is locked.
Until setUpDown returns, RoutineTUNEventReader cannot call device.state.stopping.Done.
Until device.state.stopping.Done gets called, device.state.stopping.Wait is blocked.
As long as device.state.stopping.Wait is blocked, device.state.Mutex cannot be unlocked.
This commit fixes that deadlock by holding device.state.mu
when checking that the device is not closed.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
2021-02-08 10:32:07 -08:00

459 lines
12 KiB
Go

/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
*/
package device
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"net"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"golang.zx2c4.com/wireguard/conn"
"golang.zx2c4.com/wireguard/ipc"
)
type IPCError struct {
code int64 // error code
err error // underlying/wrapped error
}
func (s IPCError) Error() string {
return fmt.Sprintf("IPC error %d: %v", s.code, s.err)
}
func (s IPCError) Unwrap() error {
return s.err
}
func (s IPCError) ErrorCode() int64 {
return s.code
}
func ipcErrorf(code int64, msg string, args ...interface{}) *IPCError {
return &IPCError{code: code, err: fmt.Errorf(msg, args...)}
}
var byteBufferPool = &sync.Pool{
New: func() interface{} { return new(bytes.Buffer) },
}
// IpcGetOperation implements the WireGuard configuration protocol "get" operation.
// See https://www.wireguard.com/xplatform/#configuration-protocol for details.
func (device *Device) IpcGetOperation(w io.Writer) error {
device.ipcMutex.RLock()
defer device.ipcMutex.RUnlock()
buf := byteBufferPool.Get().(*bytes.Buffer)
buf.Reset()
defer byteBufferPool.Put(buf)
sendf := func(format string, args ...interface{}) {
fmt.Fprintf(buf, format, args...)
buf.WriteByte('\n')
}
keyf := func(prefix string, key *[32]byte) {
buf.Grow(len(key)*2 + 2 + len(prefix))
buf.WriteString(prefix)
buf.WriteByte('=')
const hex = "0123456789abcdef"
for i := 0; i < len(key); i++ {
buf.WriteByte(hex[key[i]>>4])
buf.WriteByte(hex[key[i]&0xf])
}
buf.WriteByte('\n')
}
func() {
// lock required resources
device.net.RLock()
defer device.net.RUnlock()
device.staticIdentity.RLock()
defer device.staticIdentity.RUnlock()
device.peers.RLock()
defer device.peers.RUnlock()
// serialize device related values
if !device.staticIdentity.privateKey.IsZero() {
keyf("private_key", (*[32]byte)(&device.staticIdentity.privateKey))
}
if device.net.port != 0 {
sendf("listen_port=%d", device.net.port)
}
if device.net.fwmark != 0 {
sendf("fwmark=%d", device.net.fwmark)
}
// serialize each peer state
for _, peer := range device.peers.keyMap {
peer.RLock()
defer peer.RUnlock()
keyf("public_key", (*[32]byte)(&peer.handshake.remoteStatic))
keyf("preshared_key", (*[32]byte)(&peer.handshake.presharedKey))
sendf("protocol_version=1")
if peer.endpoint != nil {
sendf("endpoint=%s", peer.endpoint.DstToString())
}
nano := atomic.LoadInt64(&peer.stats.lastHandshakeNano)
secs := nano / time.Second.Nanoseconds()
nano %= time.Second.Nanoseconds()
sendf("last_handshake_time_sec=%d", secs)
sendf("last_handshake_time_nsec=%d", nano)
sendf("tx_bytes=%d", atomic.LoadUint64(&peer.stats.txBytes))
sendf("rx_bytes=%d", atomic.LoadUint64(&peer.stats.rxBytes))
sendf("persistent_keepalive_interval=%d", atomic.LoadUint32(&peer.persistentKeepaliveInterval))
device.allowedips.EntriesForPeer(peer, func(ip net.IP, cidr uint) bool {
sendf("allowed_ip=%s/%d", ip.String(), cidr)
return true
})
}
}()
// send lines (does not require resource locks)
if _, err := w.Write(buf.Bytes()); err != nil {
return ipcErrorf(ipc.IpcErrorIO, "failed to write output: %w", err)
}
return nil
}
// IpcSetOperation implements the WireGuard configuration protocol "set" operation.
// See https://www.wireguard.com/xplatform/#configuration-protocol for details.
func (device *Device) IpcSetOperation(r io.Reader) (err error) {
device.ipcMutex.Lock()
defer device.ipcMutex.Unlock()
defer func() {
if err != nil {
device.log.Errorf("%v", err)
}
}()
peer := new(ipcSetPeer)
deviceConfig := true
scanner := bufio.NewScanner(r)
for scanner.Scan() {
line := scanner.Text()
if line == "" {
// Blank line means terminate operation.
return nil
}
parts := strings.Split(line, "=")
if len(parts) != 2 {
return ipcErrorf(ipc.IpcErrorProtocol, "failed to parse line %q, found %d =-separated parts, want 2", line, len(parts))
}
key := parts[0]
value := parts[1]
if key == "public_key" {
if deviceConfig {
deviceConfig = false
}
peer.handlePostConfig()
// Load/create the peer we are now configuring.
err := device.handlePublicKeyLine(peer, value)
if err != nil {
return err
}
continue
}
var err error
if deviceConfig {
err = device.handleDeviceLine(key, value)
} else {
err = device.handlePeerLine(peer, key, value)
}
if err != nil {
return err
}
}
peer.handlePostConfig()
if err := scanner.Err(); err != nil {
return ipcErrorf(ipc.IpcErrorIO, "failed to read input: %w", err)
}
return nil
}
func (device *Device) handleDeviceLine(key, value string) error {
switch key {
case "private_key":
var sk NoisePrivateKey
err := sk.FromMaybeZeroHex(value)
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to set private_key: %w", err)
}
device.log.Verbosef("UAPI: Updating private key")
device.SetPrivateKey(sk)
case "listen_port":
port, err := strconv.ParseUint(value, 10, 16)
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to parse listen_port: %w", err)
}
// update port and rebind
device.log.Verbosef("UAPI: Updating listen port")
device.net.Lock()
device.net.port = uint16(port)
device.net.Unlock()
if err := device.BindUpdate(); err != nil {
return ipcErrorf(ipc.IpcErrorPortInUse, "failed to set listen_port: %w", err)
}
case "fwmark":
mark, err := strconv.ParseUint(value, 10, 32)
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "invalid fwmark: %w", err)
}
device.log.Verbosef("UAPI: Updating fwmark")
if err := device.BindSetMark(uint32(mark)); err != nil {
return ipcErrorf(ipc.IpcErrorPortInUse, "failed to update fwmark: %w", err)
}
case "replace_peers":
if value != "true" {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to set replace_peers, invalid value: %v", value)
}
device.log.Verbosef("UAPI: Removing all peers")
device.RemoveAllPeers()
default:
return ipcErrorf(ipc.IpcErrorInvalid, "invalid UAPI device key: %v", key)
}
return nil
}
// An ipcSetPeer is the current state of an IPC set operation on a peer.
type ipcSetPeer struct {
*Peer // Peer is the current peer being operated on
dummy bool // dummy reports whether this peer is a temporary, placeholder peer
created bool // new reports whether this is a newly created peer
}
func (peer *ipcSetPeer) handlePostConfig() {
if peer.Peer != nil && !peer.dummy && peer.Peer.device.isUp() {
peer.SendStagedPackets()
}
}
func (device *Device) handlePublicKeyLine(peer *ipcSetPeer, value string) error {
// Load/create the peer we are configuring.
var publicKey NoisePublicKey
err := publicKey.FromHex(value)
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to get peer by public key: %w", err)
}
// Ignore peer with the same public key as this device.
device.staticIdentity.RLock()
peer.dummy = device.staticIdentity.publicKey.Equals(publicKey)
device.staticIdentity.RUnlock()
if peer.dummy {
peer.Peer = &Peer{}
} else {
peer.Peer = device.LookupPeer(publicKey)
}
peer.created = peer.Peer == nil
if peer.created {
peer.Peer, err = device.NewPeer(publicKey)
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to create new peer: %w", err)
}
device.log.Verbosef("%v - UAPI: Created", peer.Peer)
}
return nil
}
func (device *Device) handlePeerLine(peer *ipcSetPeer, key, value string) error {
switch key {
case "update_only":
// allow disabling of creation
if value != "true" {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to set update only, invalid value: %v", value)
}
if peer.created && !peer.dummy {
device.RemovePeer(peer.handshake.remoteStatic)
peer.Peer = &Peer{}
peer.dummy = true
}
case "remove":
// remove currently selected peer from device
if value != "true" {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to set remove, invalid value: %v", value)
}
if !peer.dummy {
device.log.Verbosef("%v - UAPI: Removing", peer.Peer)
device.RemovePeer(peer.handshake.remoteStatic)
}
peer.Peer = &Peer{}
peer.dummy = true
case "preshared_key":
device.log.Verbosef("%v - UAPI: Updating preshared key", peer.Peer)
peer.handshake.mutex.Lock()
err := peer.handshake.presharedKey.FromHex(value)
peer.handshake.mutex.Unlock()
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to set preshared key: %w", err)
}
case "endpoint":
device.log.Verbosef("%v - UAPI: Updating endpoint", peer.Peer)
endpoint, err := conn.CreateEndpoint(value)
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to set endpoint %v: %w", value, err)
}
peer.Lock()
defer peer.Unlock()
peer.endpoint = endpoint
case "persistent_keepalive_interval":
device.log.Verbosef("%v - UAPI: Updating persistent keepalive interval", peer.Peer)
secs, err := strconv.ParseUint(value, 10, 16)
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to set persistent keepalive interval: %w", err)
}
old := atomic.SwapUint32(&peer.persistentKeepaliveInterval, uint32(secs))
// Send immediate keepalive if we're turning it on and before it wasn't on.
if old == 0 && secs != 0 {
if err != nil {
return ipcErrorf(ipc.IpcErrorIO, "failed to get tun device status: %w", err)
}
if device.isUp() && !peer.dummy {
peer.SendKeepalive()
}
}
case "replace_allowed_ips":
device.log.Verbosef("%v - UAPI: Removing all allowedips", peer.Peer)
if value != "true" {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to replace allowedips, invalid value: %v", value)
}
if peer.dummy {
return nil
}
device.allowedips.RemoveByPeer(peer.Peer)
case "allowed_ip":
device.log.Verbosef("%v - UAPI: Adding allowedip", peer.Peer)
_, network, err := net.ParseCIDR(value)
if err != nil {
return ipcErrorf(ipc.IpcErrorInvalid, "failed to set allowed ip: %w", err)
}
if peer.dummy {
return nil
}
ones, _ := network.Mask.Size()
device.allowedips.Insert(network.IP, uint(ones), peer.Peer)
case "protocol_version":
if value != "1" {
return ipcErrorf(ipc.IpcErrorInvalid, "invalid protocol version: %v", value)
}
default:
return ipcErrorf(ipc.IpcErrorInvalid, "invalid UAPI peer key: %v", key)
}
return nil
}
func (device *Device) IpcGet() (string, error) {
buf := new(strings.Builder)
if err := device.IpcGetOperation(buf); err != nil {
return "", err
}
return buf.String(), nil
}
func (device *Device) IpcSet(uapiConf string) error {
return device.IpcSetOperation(strings.NewReader(uapiConf))
}
func (device *Device) IpcHandle(socket net.Conn) {
defer socket.Close()
buffered := func(s io.ReadWriter) *bufio.ReadWriter {
reader := bufio.NewReader(s)
writer := bufio.NewWriter(s)
return bufio.NewReadWriter(reader, writer)
}(socket)
for {
op, err := buffered.ReadString('\n')
if err != nil {
return
}
// handle operation
switch op {
case "set=1\n":
err = device.IpcSetOperation(buffered.Reader)
case "get=1\n":
var nextByte byte
nextByte, err = buffered.ReadByte()
if err != nil {
return
}
if nextByte != '\n' {
err = ipcErrorf(ipc.IpcErrorInvalid, "trailing character in UAPI get: %q", nextByte)
break
}
err = device.IpcGetOperation(buffered.Writer)
default:
device.log.Errorf("invalid UAPI operation: %v", op)
return
}
// write status
var status *IPCError
if err != nil && !errors.As(err, &status) {
// shouldn't happen
status = ipcErrorf(ipc.IpcErrorUnknown, "other UAPI error: %w", err)
}
if status != nil {
device.log.Errorf("%v", status)
fmt.Fprintf(buffered, "errno=%d\n\n", status.ErrorCode())
} else {
fmt.Fprintf(buffered, "errno=0\n\n")
}
buffered.Flush()
}
}