tailscale/util/winutil/winutil_windows.go
Aaron Klotz 3a74f2d2d7 cmd/tailscaled, util/winutil: add accessor functions for Windows system policies.
This patch adds new functions to be used when accessing system policies,
and revises callers to use the new functions. They first attempt the new
registry path for policies, and if that fails, attempt to fall back to the
legacy path.

We keep non-policy variants of these functions because we should be able to
retain the ability to read settings from locations that are not exposed to
sysadmins for group policy edits.

The remaining changes will be done in corp.

Updates https://github.com/tailscale/tailscale/issues/3584

Signed-off-by: Aaron Klotz <aaron@tailscale.com>
2022-02-09 14:58:51 -07:00

133 lines
3.2 KiB
Go

// Copyright (c) 2021 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 winutil
import (
"log"
"syscall"
"golang.org/x/sys/windows"
"golang.org/x/sys/windows/registry"
)
const (
regBase = `SOFTWARE\Tailscale IPN`
regPolicyBase = `SOFTWARE\Policies\Tailscale`
)
// GetDesktopPID searches the PID of the process that's running the
// currently active desktop and whether it was found.
// Usually the PID will be for explorer.exe.
func GetDesktopPID() (pid uint32, ok bool) {
hwnd := windows.GetShellWindow()
if hwnd == 0 {
return 0, false
}
windows.GetWindowThreadProcessId(hwnd, &pid)
return pid, pid != 0
}
func getPolicyString(name, defval string) string {
s, err := getRegStringInternal(regPolicyBase, name)
if err != nil {
// Fall back to the legacy path
return getRegString(name, defval)
}
return s
}
func getPolicyInteger(name string, defval uint64) uint64 {
i, err := getRegIntegerInternal(regPolicyBase, name)
if err != nil {
// Fall back to the legacy path
return getRegInteger(name, defval)
}
return i
}
func getRegString(name, defval string) string {
s, err := getRegStringInternal(regBase, name)
if err != nil {
return defval
}
return s
}
func getRegInteger(name string, defval uint64) uint64 {
i, err := getRegIntegerInternal(regBase, name)
if err != nil {
return defval
}
return i
}
func getRegStringInternal(subKey, name string) (string, error) {
key, err := registry.OpenKey(registry.LOCAL_MACHINE, subKey, registry.READ)
if err != nil {
log.Printf("registry.OpenKey(%v): %v", subKey, err)
return "", err
}
defer key.Close()
val, _, err := key.GetStringValue(name)
if err != nil {
if err != registry.ErrNotExist {
log.Printf("registry.GetStringValue(%v): %v", name, err)
}
return "", err
}
return val, nil
}
func getRegIntegerInternal(subKey, name string) (uint64, error) {
key, err := registry.OpenKey(registry.LOCAL_MACHINE, subKey, registry.READ)
if err != nil {
log.Printf("registry.OpenKey(%v): %v", subKey, err)
return 0, err
}
defer key.Close()
val, _, err := key.GetIntegerValue(name)
if err != nil {
if err != registry.ErrNotExist {
log.Printf("registry.GetIntegerValue(%v): %v", name, err)
}
return 0, err
}
return val, nil
}
var (
kernel32 = syscall.NewLazyDLL("kernel32.dll")
procWTSGetActiveConsoleSessionId = kernel32.NewProc("WTSGetActiveConsoleSessionId")
)
// TODO(crawshaw): replace with x/sys/windows... one day.
// https://go-review.googlesource.com/c/sys/+/331909
func WTSGetActiveConsoleSessionId() uint32 {
r1, _, _ := procWTSGetActiveConsoleSessionId.Call()
return uint32(r1)
}
func isSIDValidPrincipal(uid string) bool {
usid, err := syscall.StringToSid(uid)
if err != nil {
return false
}
_, _, accType, err := usid.LookupAccount("")
if err != nil {
return false
}
switch accType {
case syscall.SidTypeUser, syscall.SidTypeGroup, syscall.SidTypeDomain, syscall.SidTypeAlias, syscall.SidTypeWellKnownGroup, syscall.SidTypeComputer:
return true
default:
// Reject deleted users, invalid SIDs, unknown SIDs, mandatory label SIDs, etc.
return false
}
}