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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
package wintun
import (
"encoding/hex"
"errors"
"fmt"
"sync"
"unsafe"
"golang.org/x/crypto/blake2s"
"golang.org/x/sys/windows"
"golang.org/x/text/unicode/norm"
"golang.zx2c4.com/wireguard/ipc/winpipe"
"golang.zx2c4.com/wireguard/tun/wintun/namespaceapi"
)
var (
wintunObjectSecurityAttributes *windows.SecurityAttributes
hasInitializedNamespace bool
initializingNamespace sync.Mutex
)
func initializeNamespace() error {
initializingNamespace.Lock()
defer initializingNamespace.Unlock()
if hasInitializedNamespace {
return nil
}
sd, err := winpipe.SddlToSecurityDescriptor("O:SYD:P(A;;GA;;;SY)")
if err != nil {
return fmt.Errorf("SddlToSecurityDescriptor failed: %v", err)
}
wintunObjectSecurityAttributes = &windows.SecurityAttributes{
Length: uint32(unsafe.Sizeof(windows.SecurityAttributes{})),
SecurityDescriptor: uintptr(unsafe.Pointer(&sd[0])),
}
sid, err := windows.CreateWellKnownSid(windows.WinLocalSystemSid)
if err != nil {
return fmt.Errorf("CreateWellKnownSid(LOCAL_SYSTEM) failed: %v", err)
}
boundary, err := namespaceapi.CreateBoundaryDescriptor("Wintun")
if err != nil {
return fmt.Errorf("CreateBoundaryDescriptor failed: %v", err)
}
err = boundary.AddSid(sid)
if err != nil {
return fmt.Errorf("AddSIDToBoundaryDescriptor failed: %v", err)
}
for {
_, err = namespaceapi.CreatePrivateNamespace(wintunObjectSecurityAttributes, boundary, "Wintun")
if err == windows.ERROR_ALREADY_EXISTS {
_, err = namespaceapi.OpenPrivateNamespace(boundary, "Wintun")
if err == windows.ERROR_PATH_NOT_FOUND {
continue
}
}
if err != nil {
return fmt.Errorf("Create/OpenPrivateNamespace failed: %v", err)
}
break
}
hasInitializedNamespace = true
return nil
}
func (pool Pool) takeNameMutex() (windows.Handle, error) {
err := initializeNamespace()
if err != nil {
return 0, err
}
const mutexLabel = "WireGuard Adapter Name Mutex Stable Suffix v1 jason@zx2c4.com"
b2, _ := blake2s.New256(nil)
b2.Write([]byte(mutexLabel))
b2.Write(norm.NFC.Bytes([]byte(string(pool))))
mutexName := `Wintun\Wintun-Name-Mutex-` + hex.EncodeToString(b2.Sum(nil))
mutex, err := windows.CreateMutex(wintunObjectSecurityAttributes, false, windows.StringToUTF16Ptr(mutexName))
if err != nil {
err = fmt.Errorf("Error creating name mutex: %v", err)
return 0, err
}
event, err := windows.WaitForSingleObject(mutex, windows.INFINITE)
if err != nil {
windows.CloseHandle(mutex)
return 0, fmt.Errorf("Error waiting on name mutex: %v", err)
}
if event != windows.WAIT_OBJECT_0 && event != windows.WAIT_ABANDONED {
windows.CloseHandle(mutex)
return 0, errors.New("Error with event trigger of name mutex")
}
return mutex, nil
}
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