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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
package service
import (
"golang.org/x/sys/windows"
"golang.org/x/sys/windows/svc"
"golang.org/x/sys/windows/svc/debug"
"golang.org/x/sys/windows/svc/eventlog"
"golang.zx2c4.com/wireguard/windows/conf"
"log"
"os"
"strconv"
"sync"
"syscall"
"unsafe"
)
const (
wtsSessionLogon uint32 = 5
wtsSessionLogoff uint32 = 6
)
type wtsState int
const (
wtsActive wtsState = iota
wtsConnected
wtsConnectQuery
wtsShadow
wtsDisconnected
wtsIdle
wtsListen
wtsReset
wtsDown
wtsInit
)
type wtsSessionNotification struct {
size uint32
sessionID uint32
}
type wtsSessionInfo struct {
sessionID uint32
windowStationName *uint16
state wtsState
}
type wellKnownSidType uint32
const (
winBuiltinAdministratorsSid wellKnownSidType = 26
)
//sys wtfQueryUserToken(session uint32, token *windows.Token) (err error) = wtsapi32.WTSQueryUserToken
//sys wtsEnumerateSessions(handle windows.Handle, reserved uint32, version uint32, sessions **wtsSessionInfo, count *uint32) (err error) = wtsapi32.WTSEnumerateSessionsW
//sys wtsFreeMemory(ptr uintptr) = wtsapi32.WTSFreeMemory
//sys createWellKnownSid(sidType wellKnownSidType, domainSid *windows.SID, sid *windows.SID, sizeSid *uint32) (err error) = advapi32.CreateWellKnownSid
//TODO: Upstream this to x/sys/windows
func localWellKnownSid(sidType wellKnownSidType) (*windows.SID, error) {
n := uint32(50)
for {
b := make([]byte, n)
sid := (*windows.SID)(unsafe.Pointer(&b[0]))
err := createWellKnownSid(sidType, nil, sid, &n)
if err == nil {
return sid, nil
}
if err != windows.ERROR_INSUFFICIENT_BUFFER {
return nil, err
}
if n <= uint32(len(b)) {
return nil, err
}
}
}
type managerService struct{}
type elogger struct {
debug.Log
}
func (elog elogger) Write(p []byte) (n int, err error) {
msg := string(p)
n = len(msg)
err = elog.Warning(1, msg)
return
}
func (service *managerService) Execute(args []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (svcSpecificEC bool, exitCode uint32) {
changes <- svc.Status{State: svc.StartPending}
//TODO: remember to clean this up in the msi uninstaller
eventlog.InstallAsEventCreate("WireGuard", eventlog.Info|eventlog.Warning|eventlog.Error)
elog, err := eventlog.Open("WireGuard")
if err != nil {
changes <- svc.Status{State: svc.StopPending}
exitCode = ERROR_LOG_CONTAINER_OPEN_FAILED
return
}
log.SetOutput(elogger{elog})
path, err := os.Executable()
if err != nil {
elog.Error(1, "Unable to determine own executable path: "+err.Error())
changes <- svc.Status{State: svc.StopPending}
exitCode = ERROR_BAD_PATHNAME
return
}
adminSid, err := localWellKnownSid(winBuiltinAdministratorsSid)
if err != nil {
elog.Error(1, "Unable to find Administrators SID: "+err.Error())
changes <- svc.Status{State: svc.StopPending}
exitCode = ERROR_SERVER_SID_MISMATCH
return
}
devNull, err := os.OpenFile(os.DevNull, os.O_RDWR, 0)
if err != nil {
elog.Error(1, "Unable to open NUL file: "+err.Error())
changes <- svc.Status{State: svc.StopPending}
exitCode = ERROR_FILE_NOT_FOUND
return
}
err = trackExistingTunnels()
if err != nil {
elog.Error(1, "Unable to track existing tunnels: "+err.Error())
changes <- svc.Status{State: svc.StopPending}
exitCode = ERROR_NO_TRACKING_SERVICE
return
}
conf.RegisterStoreChangeCallback(func() { conf.MigrateUnencryptedConfigs() }) // Ignore return value for now, but could be useful later.
conf.RegisterStoreChangeCallback(IPCServerNotifyTunnelsChange)
procs := make(map[uint32]*os.Process)
procsLock := sync.Mutex{}
var startProcess func(session uint32)
startProcess = func(session uint32) {
for {
var userToken windows.Token
err := wtfQueryUserToken(session, &userToken)
if err != nil {
return
}
//TODO: SECURITY CRITICIAL!
//TODO: Isn't it better to use an impersonation token and userToken.IsMember instead?
gs, err := userToken.GetTokenGroups()
if err != nil {
elog.Error(1, "Unable to lookup user groups from token: "+err.Error())
return
}
p := unsafe.Pointer(&gs.Groups[0])
//TODO: x/sys/windows/svc/security.go uses 2 << 20, but shouldn't this be 1 << 20? Send upstream
groups := (*[1 << 20]windows.SIDAndAttributes)(p)[:gs.GroupCount]
isAdmin := false
for _, g := range groups {
if windows.EqualSid(g.Sid, adminSid) {
isAdmin = true
break
}
}
if !isAdmin {
return
}
user, err := userToken.GetTokenUser()
if err != nil {
elog.Error(1, "Unable to lookup user from token: "+err.Error())
return
}
username, domain, accType, err := user.User.Sid.LookupAccount("")
if err != nil {
elog.Error(1, "Unable to lookup username from sid: "+err.Error())
return
}
if accType != windows.SidTypeUser {
return
}
ourReader, theirReader, theirReaderStr, ourWriter, theirWriter, theirWriterStr, err := inheritableSocketpairEmulation()
if err != nil {
elog.Error(1, "Unable to create two inheritable pipes: "+err.Error())
return
}
ourEvents, theirEvents, theirEventStr, err := inheritableEvents()
err = IPCServerListen(ourReader, ourWriter, ourEvents)
if err != nil {
elog.Error(1, "Unable to listen on IPC pipes: "+err.Error())
return
}
elog.Info(1, "Starting UI process for user: "+username+", domain: "+domain)
attr := &os.ProcAttr{
Sys: &syscall.SysProcAttr{
Token: syscall.Token(userToken),
},
Files: []*os.File{devNull, devNull, devNull},
}
proc, err := os.StartProcess(path, []string{path, "/ui", theirReaderStr, theirWriterStr, theirEventStr}, attr)
theirReader.Close()
theirWriter.Close()
theirEvents.Close()
if err != nil {
elog.Error(1, "Unable to start manager UI process: "+err.Error())
return
}
procsLock.Lock()
procs[session] = proc
procsLock.Unlock()
proc.Wait()
procsLock.Lock()
delete(procs, session)
procsLock.Unlock()
ourReader.Close()
ourWriter.Close()
ourEvents.Close()
}
}
var sessionsPointer *wtsSessionInfo
var count uint32
err = wtsEnumerateSessions(0, 0, 1, &sessionsPointer, &count)
if err != nil {
elog.Error(1, "Unable to enumerate current sessions: "+err.Error())
changes <- svc.Status{State: svc.StopPending}
exitCode = ERROR_BAD_LOGON_SESSION_STATE
return
}
sessions := *(*[]wtsSessionInfo)(unsafe.Pointer(&struct {
addr *wtsSessionInfo
len int
cap int
}{sessionsPointer, int(count), int(count)}))
for _, session := range sessions {
if session.state == wtsActive {
go startProcess(session.sessionID)
}
}
wtsFreeMemory(uintptr(unsafe.Pointer(sessionsPointer)))
changes <- svc.Status{State: svc.Running, Accepts: svc.AcceptStop | svc.AcceptSessionChange}
uninstall := false
loop:
for {
select {
case <-quitManagersChan:
uninstall = true
break loop
case c := <-r:
switch c.Cmd {
case svc.Stop:
break loop
case svc.Interrogate:
changes <- c.CurrentStatus
case svc.SessionChange:
//TODO: All the logic here depends on https://go-review.googlesource.com/c/sys/+/158698 being merged
if c.EventType != wtsSessionLogon && c.EventType != wtsSessionLogoff {
continue
}
sessionNotification := (*wtsSessionNotification)(unsafe.Pointer(c.EventData))
if uintptr(sessionNotification.size) != unsafe.Sizeof(*sessionNotification) {
elog.Error(1, "Unexpected size of WTSSESSION_NOTIFICATION: "+strconv.Itoa(int(sessionNotification.size)))
continue
}
if c.EventType == wtsSessionLogoff {
procsLock.Lock()
if proc, ok := procs[sessionNotification.sessionID]; ok {
proc.Kill()
}
procsLock.Unlock()
} else if c.EventType == wtsSessionLogon {
procsLock.Lock()
if _, ok := procs[sessionNotification.sessionID]; !ok {
go startProcess(sessionNotification.sessionID)
}
procsLock.Unlock()
}
default:
elog.Info(1, "Unexpected service control request "+strconv.Itoa(int(c.Cmd)))
}
}
}
changes <- svc.Status{State: svc.StopPending}
procsLock.Lock()
for _, proc := range procs {
proc.Kill()
}
procsLock.Unlock()
if uninstall {
err = UninstallManager()
if err != nil {
elog.Error(1, "Unable to uninstaller manager when quitting: "+err.Error())
}
}
return
}
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