api: begin to separate rundll32 jumps

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

api/adapter.c

@@ -1642,212 +1642,6 @@ cleanupDevInfo:
     return Result;
 }
 
-#ifdef MAYBE_WOW64
-
-typedef struct _PROCESS_STDOUT_STATE
-{
-    HANDLE Stdout;
-    WCHAR *Response;
-    DWORD ResponseCapacity;
-} PROCESS_STDOUT_STATE;
-
-static DWORD WINAPI
-ProcessStdout(_Inout_ PROCESS_STDOUT_STATE *State)
-{
-    for (DWORD Offset = 0, MaxLen = State->ResponseCapacity - 1; Offset < MaxLen;)
-    {
-        DWORD SizeRead;
-        if (!ReadFile(State->Stdout, State->Response + Offset, sizeof(WCHAR) * (MaxLen - Offset), &SizeRead, NULL))
-            return ERROR_SUCCESS;
-        if (SizeRead % sizeof(WCHAR))
-            return ERROR_INVALID_DATA;
-        Offset += SizeRead / sizeof(WCHAR);
-        State->Response[Offset] = 0;
-    }
-    return ERROR_BUFFER_OVERFLOW;
-}
-
-static DWORD WINAPI
-ProcessStderr(_In_ HANDLE Stderr)
-{
-    enum
-    {
-        OnNone,
-        OnLevelStart,
-        OnLevel,
-        OnLevelEnd,
-        OnSpace,
-        OnMsg
-    } State = OnNone;
-    WCHAR Msg[0x200];
-    DWORD Count = 0;
-    WINTUN_LOGGER_LEVEL Level = WINTUN_LOG_INFO;
-    for (;;)
-    {
-        WCHAR Buf[0x200];
-        DWORD SizeRead;
-        if (!ReadFile(Stderr, Buf, sizeof(Buf), &SizeRead, NULL))
-            return ERROR_SUCCESS;
-        if (SizeRead % sizeof(WCHAR))
-            return ERROR_INVALID_DATA;
-        SizeRead /= sizeof(WCHAR);
-        for (DWORD i = 0; i < SizeRead; ++i)
-        {
-            WCHAR c = Buf[i];
-            if (State == OnNone && c == L'[')
-                State = OnLevelStart;
-            else if (
-                State == OnLevelStart && ((Level = WINTUN_LOG_INFO, c == L'+') ||
-                                          (Level = WINTUN_LOG_WARN, c == L'-') || (Level = WINTUN_LOG_ERR, c == L'!')))
-                State = OnLevelEnd;
-            else if (State == OnLevelEnd && c == L']')
-                State = OnSpace;
-            else if (State == OnSpace && !iswspace(c) || State == OnMsg && c != L'\r' && c != L'\n')
-            {
-                if (Count < _countof(Msg) - 1)
-                    Msg[Count++] = c;
-                State = OnMsg;
-            }
-            else if (State == OnMsg && c == L'\n')
-            {
-                Msg[Count] = 0;
-                Logger(Level, Msg);
-                State = OnNone;
-                Count = 0;
-            }
-        }
-    }
-}
-
-static WINTUN_STATUS
-ExecuteRunDll32(
-    _In_z_ const WCHAR *Arguments,
-    _Out_z_cap_c_(ResponseCapacity) WCHAR *Response,
-    _In_ DWORD ResponseCapacity)
-{
-    WCHAR WindowsDirectory[MAX_PATH];
-    if (!GetWindowsDirectoryW(WindowsDirectory, _countof(WindowsDirectory)))
-        return LOG_LAST_ERROR(L"Failed to get Windows folder");
-    WCHAR RunDll32Path[MAX_PATH];
-    if (!PathCombineW(RunDll32Path, WindowsDirectory, L"Sysnative\\rundll32.exe"))
-        return ERROR_BUFFER_OVERFLOW;
-
-    DWORD Result;
-    WCHAR RandomTempSubDirectory[MAX_PATH];
-    if ((Result = CreateTemporaryDirectory(RandomTempSubDirectory)) != ERROR_SUCCESS)
-        return LOG(WINTUN_LOG_ERR, L"Failed to create temporary folder"), Result;
-    WCHAR DllPath[MAX_PATH] = { 0 };
-    if (!PathCombineW(DllPath, RandomTempSubDirectory, L"wintun.dll"))
-    {
-        Result = ERROR_BUFFER_OVERFLOW;
-        goto cleanupDirectory;
-    }
-    const WCHAR *WintunDllResourceName;
-    switch (NativeMachine)
-    {
-    case IMAGE_FILE_MACHINE_AMD64:
-        WintunDllResourceName = L"wintun-amd64.dll";
-        break;
-    case IMAGE_FILE_MACHINE_ARM64:
-        WintunDllResourceName = L"wintun-arm64.dll";
-        break;
-    default:
-        LOG(WINTUN_LOG_ERR, L"Unsupported platform");
-        Result = ERROR_NOT_SUPPORTED;
-        goto cleanupDirectory;
-    }
-    if ((Result = ResourceCopyToFile(DllPath, WintunDllResourceName)) != ERROR_SUCCESS)
-    {
-        LOG(WINTUN_LOG_ERR, L"Failed to copy resource");
-        goto cleanupDelete;
-    }
-    size_t CommandLineLen = 10 + MAX_PATH + 2 + wcslen(Arguments) + 1;
-    WCHAR *CommandLine = HeapAlloc(ModuleHeap, 0, CommandLineLen * sizeof(WCHAR));
-    if (!CommandLine)
-    {
-        LOG(WINTUN_LOG_ERR, L"Out of memory");
-        Result = ERROR_OUTOFMEMORY;
-        goto cleanupDelete;
-    }
-    if (_snwprintf_s(CommandLine, CommandLineLen, _TRUNCATE, L"rundll32 \"%.*s\",%s", MAX_PATH, DllPath, Arguments) ==
-        -1)
-    {
-        LOG(WINTUN_LOG_ERR, L"Command line too long");
-        Result = ERROR_INVALID_PARAMETER;
-        goto cleanupDelete;
-    }
-    HANDLE StreamRStdout = INVALID_HANDLE_VALUE, StreamRStderr = INVALID_HANDLE_VALUE,
-           StreamWStdout = INVALID_HANDLE_VALUE, StreamWStderr = INVALID_HANDLE_VALUE;
-    if (!CreatePipe(&StreamRStdout, &StreamWStdout, &SecurityAttributes, 0) ||
-        !CreatePipe(&StreamRStderr, &StreamWStderr, &SecurityAttributes, 0))
-    {
-        Result = LOG_LAST_ERROR(L"Failed to create pipes");
-        goto cleanupPipes;
-    }
-    if (!SetHandleInformation(StreamWStdout, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT) ||
-        !SetHandleInformation(StreamWStderr, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT))
-    {
-        Result = LOG_LAST_ERROR(L"Failed to set handle info");
-        goto cleanupPipes;
-    }
-    if (ResponseCapacity)
-        Response[0] = 0;
-    PROCESS_STDOUT_STATE ProcessStdoutState = { .Stdout = StreamRStdout,
-                                                .Response = Response,
-                                                .ResponseCapacity = ResponseCapacity };
-    HANDLE ThreadStdout = NULL, ThreadStderr = NULL;
-    if ((ThreadStdout = CreateThread(&SecurityAttributes, 0, ProcessStdout, &ProcessStdoutState, 0, NULL)) == NULL ||
-        (ThreadStderr = CreateThread(&SecurityAttributes, 0, ProcessStderr, StreamRStderr, 0, NULL)) == NULL)
-    {
-        Result = LOG_LAST_ERROR(L"Failed to spawn readers");
-        goto cleanupThreads;
-    }
-    STARTUPINFOW si = { .cb = sizeof(STARTUPINFO),
-                        .dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES,
-                        .wShowWindow = SW_HIDE,
-                        .hStdOutput = StreamWStdout,
-                        .hStdError = StreamWStderr };
-    PROCESS_INFORMATION pi;
-    if (!CreateProcessW(RunDll32Path, CommandLine, NULL, NULL, TRUE, 0, NULL, NULL, &si, &pi))
-    {
-        Result = LOG_LAST_ERROR(L"Creating process failed");
-        goto cleanupThreads;
-    }
-    WaitForSingleObject(pi.hProcess, INFINITE);
-    CloseHandle(pi.hProcess);
-    CloseHandle(pi.hThread);
-cleanupThreads:
-    if (ThreadStderr)
-    {
-        CloseHandle(StreamWStderr);
-        StreamWStderr = INVALID_HANDLE_VALUE;
-        WaitForSingleObject(ThreadStderr, INFINITE);
-        CloseHandle(ThreadStderr);
-    }
-    if (ThreadStdout)
-    {
-        CloseHandle(StreamWStdout);
-        StreamWStdout = INVALID_HANDLE_VALUE;
-        WaitForSingleObject(ThreadStdout, INFINITE);
-        if (!GetExitCodeThread(ThreadStdout, &Result))
-            Result = LOG_LAST_ERROR(L"Failed to retrieve stdout reader result");
-        else if (Result != ERROR_SUCCESS)
-            LOG_ERROR(L"Failed to read process output", Result);
-        CloseHandle(ThreadStdout);
-    }
-cleanupPipes:
-    CloseHandle(StreamRStderr);
-    CloseHandle(StreamWStderr);
-    CloseHandle(StreamRStdout);
-    CloseHandle(StreamWStdout);
-    HeapFree(ModuleHeap, 0, CommandLine);
-cleanupDelete:
-    DeleteFileW(DllPath);
-cleanupDirectory:
-    RemoveDirectoryW(RandomTempSubDirectory);
-    return Result;
-}
-
 static WINTUN_STATUS
 GetAdapter(_In_z_ const WCHAR *Pool, _In_ const GUID *CfgInstanceID, _Out_ WINTUN_ADAPTER **Adapter)
 {
@@ -1871,57 +1665,7 @@ cleanupMutex:
     return Result;
 }
 
-static WINTUN_STATUS
+#include "rundll32.h"
-CreateAdapterNatively(
-    _In_z_ const WCHAR *Pool,
-    _In_z_ const WCHAR *Name,
-    _In_opt_ const GUID *RequestedGUID,
-    _Out_ WINTUN_ADAPTER **Adapter,
-    _Inout_ BOOL *RebootRequired)
-{
-    LOG(WINTUN_LOG_INFO, L"Spawning native process");
-    WCHAR RequestedGUIDStr[MAX_GUID_STRING_LEN];
-    WCHAR Arguments[15 + WINTUN_MAX_POOL + 3 + MAX_ADAPTER_NAME + 2 + MAX_GUID_STRING_LEN + 1];
-    if (_snwprintf_s(
-            Arguments,
-            _countof(Arguments),
-            _TRUNCATE,
-            RequestedGUID ? L"CreateAdapter \"%s\" \"%s\" %.*s" : L"CreateAdapter \"%s\" \"%s\"",
-            Pool,
-            Name,
-            RequestedGUID ? StringFromGUID2(RequestedGUID, RequestedGUIDStr, _countof(RequestedGUIDStr)) : 0,
-            RequestedGUIDStr) == -1)
-        return LOG(WINTUN_LOG_ERR, L"Command line too long"), ERROR_INVALID_PARAMETER;
-    WCHAR Response[8 + 1 + MAX_GUID_STRING_LEN + 1 + 8 + 1];
-    DWORD Result = ExecuteRunDll32(Arguments, Response, _countof(Response));
-    if (Result != ERROR_SUCCESS)
-    {
-        LOG(WINTUN_LOG_ERR, L"Error executing worker process");
-        return Result;
-    }
-    int Argc;
-    WCHAR **Argv = CommandLineToArgvW(Response, &Argc);
-    GUID CfgInstanceID;
-    if (Argc < 3 || FAILED(CLSIDFromString(Argv[1], &CfgInstanceID)))
-    {
-        LOG(WINTUN_LOG_ERR, L"Incomplete or invalid response");
-        Result = ERROR_INVALID_PARAMETER;
-        goto cleanupArgv;
-    }
-    Result = wcstoul(Argv[0], NULL, 16);
-    if (Result == ERROR_SUCCESS && GetAdapter(Pool, &CfgInstanceID, Adapter) != ERROR_SUCCESS)
-    {
-        LOG(WINTUN_LOG_ERR, L"Failed to get adapter");
-        Result = ERROR_FILE_NOT_FOUND;
-    }
-    if (wcstoul(Argv[2], NULL, 16))
-        *RebootRequired = TRUE;
-cleanupArgv:
-    LocalFree(Argv);
-    return Result;
-}
-
-#endif
 
 WINTUN_STATUS WINAPI
 WintunCreateAdapter(
@@ -1941,7 +1685,7 @@ WintunCreateAdapter(
 #ifdef MAYBE_WOW64
     if (NativeMachine != IMAGE_FILE_PROCESS)
     {
-        Result = CreateAdapterNatively(Pool, Name, RequestedGUID, Adapter, RebootRequired);
+        Result = CreateAdapterViaRundll32(Pool, Name, RequestedGUID, Adapter, RebootRequired);
         RevertToSelf();
         return Result;
     }
@@ -1951,48 +1695,6 @@ WintunCreateAdapter(
     return Result;
 }
 
-#ifdef MAYBE_WOW64
-
-static WINTUN_STATUS
-DeleteAdapterNatively(_In_ const WINTUN_ADAPTER *Adapter, _In_ BOOL ForceCloseSessions, _Inout_ BOOL *RebootRequired)
-{
-    LOG(WINTUN_LOG_INFO, L"Spawning native process");
-    WCHAR GuidStr[MAX_GUID_STRING_LEN];
-    WCHAR Arguments[16 + MAX_GUID_STRING_LEN + 1];
-    if (_snwprintf_s(
-            Arguments,
-            _countof(Arguments),
-            _TRUNCATE,
-            L"DeleteAdapter %d %.*s",
-            ForceCloseSessions ? 1 : 0,
-            StringFromGUID2(&Adapter->CfgInstanceID, GuidStr, _countof(GuidStr)),
-            GuidStr) == -1)
-        return LOG(WINTUN_LOG_ERR, L"Command line too long"), ERROR_INVALID_PARAMETER;
-    WCHAR Response[8 + 1 + 8 + 1];
-    DWORD Result = ExecuteRunDll32(Arguments, Response, _countof(Response));
-    if (Result != ERROR_SUCCESS)
-    {
-        LOG(WINTUN_LOG_ERR, L"Error executing worker process");
-        return Result;
-    }
-    int Argc;
-    WCHAR **Argv = CommandLineToArgvW(Response, &Argc);
-    if (Argc < 2)
-    {
-        LOG(WINTUN_LOG_ERR, L"Incomplete or invalid response");
-        Result = ERROR_INVALID_PARAMETER;
-        goto cleanupArgv;
-    }
-    Result = wcstoul(Argv[0], NULL, 16);
-    if (wcstoul(Argv[1], NULL, 16))
-        *RebootRequired = TRUE;
-cleanupArgv:
-    LocalFree(Argv);
-    return Result;
-}
-
-#endif
-
 WINTUN_STATUS WINAPI
 WintunDeleteAdapter(_In_ const WINTUN_ADAPTER *Adapter, _In_ BOOL ForceCloseSessions, _Out_opt_ BOOL *RebootRequired)
 {
@@ -2007,7 +1709,7 @@ WintunDeleteAdapter(_In_ const WINTUN_ADAPTER *Adapter, _In_ BOOL ForceCloseSess
 #ifdef MAYBE_WOW64
     if (NativeMachine != IMAGE_FILE_PROCESS)
     {
-        Result = DeleteAdapterNatively(Adapter, ForceCloseSessions, RebootRequired);
+        Result = DeleteAdapterViaRundll32(Adapter, ForceCloseSessions, RebootRequired);
         RevertToSelf();
         return Result;
     }
@@ -2046,35 +1748,6 @@ cleanupToken:
     return Result;
 }
 
-#ifdef MAYBE_WOW64
-
-static WINTUN_STATUS
-DeleteDriverNatively()
-{
-    LOG(WINTUN_LOG_INFO, L"Spawning native process");
-    WCHAR Response[8 + 1];
-    DWORD Result = ExecuteRunDll32(L"DeleteDriver", Response, _countof(Response));
-    if (Result != ERROR_SUCCESS)
-    {
-        LOG(WINTUN_LOG_ERR, L"Error executing worker process");
-        return Result;
-    }
-    int Argc;
-    WCHAR **Argv = CommandLineToArgvW(Response, &Argc);
-    if (Argc < 1)
-    {
-        LOG(WINTUN_LOG_ERR, L"Incomplete or invalid response");
-        Result = ERROR_INVALID_PARAMETER;
-        goto cleanupArgv;
-    }
-    Result = wcstoul(Argv[0], NULL, 16);
-cleanupArgv:
-    LocalFree(Argv);
-    return Result;
-}
-
-#endif
-
 static WINTUN_STATUS
 DeleteAllOurAdapters(void)
 {
@@ -2121,17 +1794,18 @@ WintunDeleteDriver(void)
     if (!ElevateToSystem())
         return LOG(WINTUN_LOG_ERR, L"Failed to impersonate SYSTEM user"), ERROR_ACCESS_DENIED;
 
+    DWORD Result = ERROR_SUCCESS;
+
 #ifdef MAYBE_WOW64
     if (NativeMachine != IMAGE_FILE_PROCESS)
     {
-        Result = DeleteDriverNatively();
+        Result = DeleteDriverViaRundll32();
         RevertToSelf();
         return Result;
     }
 #endif
 
     /* DeleteAllOurAdapters(); */
-    DWORD Result = ERROR_SUCCESS;
     HANDLE DriverInstallationLock = NamespaceTakeDriverInstallationMutex();
     if (!DriverInstallationLock)
     {

api/api.vcxproj

@@ -160,6 +160,7 @@ lib.exe /def:nci.def /out:"$(IntDir)nci.lib" /machine:$(PlatformTarget) /nologo
     <ClInclude Include="entry.h" />
     <ClInclude Include="adapter.h" />
     <ClInclude Include="elevate.h" />
+    <ClInclude Include="rundll32.h" />
     <ClInclude Include="logger.h" />
     <ClInclude Include="namespace.h" />
     <ClInclude Include="nci.h" />

api/api.vcxproj.filters

@@ -58,6 +58,9 @@
     <ClInclude Include="entry.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="rundll32.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="namespace.c">

api/rundll32.h

@@ -0,0 +1,323 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2018-2020 WireGuard LLC. All Rights Reserved.
+ */
+
+/* TODO: This is currently #include'd in adapter.c. Move into rundll32.c properly. */
+
+typedef struct _PROCESS_STDOUT_STATE
+{
+    HANDLE Stdout;
+    WCHAR *Response;
+    DWORD ResponseCapacity;
+} PROCESS_STDOUT_STATE;
+
+static DWORD WINAPI
+ProcessStdout(_Inout_ PROCESS_STDOUT_STATE *State)
+{
+    for (DWORD Offset = 0, MaxLen = State->ResponseCapacity - 1; Offset < MaxLen;)
+    {
+        DWORD SizeRead;
+        if (!ReadFile(State->Stdout, State->Response + Offset, sizeof(WCHAR) * (MaxLen - Offset), &SizeRead, NULL))
+            return ERROR_SUCCESS;
+        if (SizeRead % sizeof(WCHAR))
+            return ERROR_INVALID_DATA;
+        Offset += SizeRead / sizeof(WCHAR);
+        State->Response[Offset] = 0;
+    }
+    return ERROR_BUFFER_OVERFLOW;
+}
+
+static DWORD WINAPI
+ProcessStderr(_In_ HANDLE Stderr)
+{
+    enum
+    {
+        OnNone,
+        OnLevelStart,
+        OnLevel,
+        OnLevelEnd,
+        OnSpace,
+        OnMsg
+    } State = OnNone;
+    WCHAR Msg[0x200];
+    DWORD Count = 0;
+    WINTUN_LOGGER_LEVEL Level = WINTUN_LOG_INFO;
+    for (;;)
+    {
+        WCHAR Buf[0x200];
+        DWORD SizeRead;
+        if (!ReadFile(Stderr, Buf, sizeof(Buf), &SizeRead, NULL))
+            return ERROR_SUCCESS;
+        if (SizeRead % sizeof(WCHAR))
+            return ERROR_INVALID_DATA;
+        SizeRead /= sizeof(WCHAR);
+        for (DWORD i = 0; i < SizeRead; ++i)
+        {
+            WCHAR c = Buf[i];
+            if (State == OnNone && c == L'[')
+                State = OnLevelStart;
+            else if (
+                State == OnLevelStart && ((Level = WINTUN_LOG_INFO, c == L'+') ||
+                                          (Level = WINTUN_LOG_WARN, c == L'-') || (Level = WINTUN_LOG_ERR, c == L'!')))
+                State = OnLevelEnd;
+            else if (State == OnLevelEnd && c == L']')
+                State = OnSpace;
+            else if (State == OnSpace && !iswspace(c) || State == OnMsg && c != L'\r' && c != L'\n')
+            {
+                if (Count < _countof(Msg) - 1)
+                    Msg[Count++] = c;
+                State = OnMsg;
+            }
+            else if (State == OnMsg && c == L'\n')
+            {
+                Msg[Count] = 0;
+                Logger(Level, Msg);
+                State = OnNone;
+                Count = 0;
+            }
+        }
+    }
+}
+
+static WINTUN_STATUS
+ExecuteRunDll32(
+    _In_z_ const WCHAR *Arguments,
+    _Out_z_cap_c_(ResponseCapacity) WCHAR *Response,
+    _In_ DWORD ResponseCapacity)
+{
+    WCHAR WindowsDirectory[MAX_PATH];
+    if (!GetWindowsDirectoryW(WindowsDirectory, _countof(WindowsDirectory)))
+        return LOG_LAST_ERROR(L"Failed to get Windows folder");
+    WCHAR RunDll32Path[MAX_PATH];
+    if (!PathCombineW(RunDll32Path, WindowsDirectory, L"Sysnative\\rundll32.exe"))
+        return ERROR_BUFFER_OVERFLOW;
+
+    DWORD Result;
+    WCHAR RandomTempSubDirectory[MAX_PATH];
+    if ((Result = CreateTemporaryDirectory(RandomTempSubDirectory)) != ERROR_SUCCESS)
+        return LOG(WINTUN_LOG_ERR, L"Failed to create temporary folder"), Result;
+    WCHAR DllPath[MAX_PATH] = { 0 };
+    if (!PathCombineW(DllPath, RandomTempSubDirectory, L"wintun.dll"))
+    {
+        Result = ERROR_BUFFER_OVERFLOW;
+        goto cleanupDirectory;
+    }
+    const WCHAR *WintunDllResourceName;
+    switch (NativeMachine)
+    {
+    case IMAGE_FILE_MACHINE_AMD64:
+        WintunDllResourceName = L"wintun-amd64.dll";
+        break;
+    case IMAGE_FILE_MACHINE_ARM64:
+        WintunDllResourceName = L"wintun-arm64.dll";
+        break;
+    default:
+        LOG(WINTUN_LOG_ERR, L"Unsupported platform");
+        Result = ERROR_NOT_SUPPORTED;
+        goto cleanupDirectory;
+    }
+    if ((Result = ResourceCopyToFile(DllPath, WintunDllResourceName)) != ERROR_SUCCESS)
+    {
+        LOG(WINTUN_LOG_ERR, L"Failed to copy resource");
+        goto cleanupDelete;
+    }
+    size_t CommandLineLen = 10 + MAX_PATH + 2 + wcslen(Arguments) + 1;
+    WCHAR *CommandLine = HeapAlloc(ModuleHeap, 0, CommandLineLen * sizeof(WCHAR));
+    if (!CommandLine)
+    {
+        LOG(WINTUN_LOG_ERR, L"Out of memory");
+        Result = ERROR_OUTOFMEMORY;
+        goto cleanupDelete;
+    }
+    if (_snwprintf_s(CommandLine, CommandLineLen, _TRUNCATE, L"rundll32 \"%.*s\",%s", MAX_PATH, DllPath, Arguments) ==
+        -1)
+    {
+        LOG(WINTUN_LOG_ERR, L"Command line too long");
+        Result = ERROR_INVALID_PARAMETER;
+        goto cleanupDelete;
+    }
+    HANDLE StreamRStdout = INVALID_HANDLE_VALUE, StreamRStderr = INVALID_HANDLE_VALUE,
+           StreamWStdout = INVALID_HANDLE_VALUE, StreamWStderr = INVALID_HANDLE_VALUE;
+    if (!CreatePipe(&StreamRStdout, &StreamWStdout, &SecurityAttributes, 0) ||
+        !CreatePipe(&StreamRStderr, &StreamWStderr, &SecurityAttributes, 0))
+    {
+        Result = LOG_LAST_ERROR(L"Failed to create pipes");
+        goto cleanupPipes;
+    }
+    if (!SetHandleInformation(StreamWStdout, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT) ||
+        !SetHandleInformation(StreamWStderr, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT))
+    {
+        Result = LOG_LAST_ERROR(L"Failed to set handle info");
+        goto cleanupPipes;
+    }
+    if (ResponseCapacity)
+        Response[0] = 0;
+    PROCESS_STDOUT_STATE ProcessStdoutState = { .Stdout = StreamRStdout,
+                                                .Response = Response,
+                                                .ResponseCapacity = ResponseCapacity };
+    HANDLE ThreadStdout = NULL, ThreadStderr = NULL;
+    if ((ThreadStdout = CreateThread(&SecurityAttributes, 0, ProcessStdout, &ProcessStdoutState, 0, NULL)) == NULL ||
+        (ThreadStderr = CreateThread(&SecurityAttributes, 0, ProcessStderr, StreamRStderr, 0, NULL)) == NULL)
+    {
+        Result = LOG_LAST_ERROR(L"Failed to spawn readers");
+        goto cleanupThreads;
+    }
+    STARTUPINFOW si = { .cb = sizeof(STARTUPINFO),
+                        .dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES,
+                        .wShowWindow = SW_HIDE,
+                        .hStdOutput = StreamWStdout,
+                        .hStdError = StreamWStderr };
+    PROCESS_INFORMATION pi;
+    if (!CreateProcessW(RunDll32Path, CommandLine, NULL, NULL, TRUE, 0, NULL, NULL, &si, &pi))
+    {
+        Result = LOG_LAST_ERROR(L"Creating process failed");
+        goto cleanupThreads;
+    }
+    WaitForSingleObject(pi.hProcess, INFINITE);
+    CloseHandle(pi.hProcess);
+    CloseHandle(pi.hThread);
+cleanupThreads:
+    if (ThreadStderr)
+    {
+        CloseHandle(StreamWStderr);
+        StreamWStderr = INVALID_HANDLE_VALUE;
+        WaitForSingleObject(ThreadStderr, INFINITE);
+        CloseHandle(ThreadStderr);
+    }
+    if (ThreadStdout)
+    {
+        CloseHandle(StreamWStdout);
+        StreamWStdout = INVALID_HANDLE_VALUE;
+        WaitForSingleObject(ThreadStdout, INFINITE);
+        if (!GetExitCodeThread(ThreadStdout, &Result))
+            Result = LOG_LAST_ERROR(L"Failed to retrieve stdout reader result");
+        else if (Result != ERROR_SUCCESS)
+            LOG_ERROR(L"Failed to read process output", Result);
+        CloseHandle(ThreadStdout);
+    }
+cleanupPipes:
+    CloseHandle(StreamRStderr);
+    CloseHandle(StreamWStderr);
+    CloseHandle(StreamRStdout);
+    CloseHandle(StreamWStdout);
+    HeapFree(ModuleHeap, 0, CommandLine);
+cleanupDelete:
+    DeleteFileW(DllPath);
+cleanupDirectory:
+    RemoveDirectoryW(RandomTempSubDirectory);
+    return Result;
+}
+
+static WINTUN_STATUS
+CreateAdapterViaRundll32(
+    _In_z_ const WCHAR *Pool,
+    _In_z_ const WCHAR *Name,
+    _In_opt_ const GUID *RequestedGUID,
+    _Out_ WINTUN_ADAPTER **Adapter,
+    _Inout_ BOOL *RebootRequired)
+{
+    LOG(WINTUN_LOG_INFO, L"Spawning native process");
+    WCHAR RequestedGUIDStr[MAX_GUID_STRING_LEN];
+    WCHAR Arguments[15 + WINTUN_MAX_POOL + 3 + MAX_ADAPTER_NAME + 2 + MAX_GUID_STRING_LEN + 1];
+    if (_snwprintf_s(
+            Arguments,
+            _countof(Arguments),
+            _TRUNCATE,
+            RequestedGUID ? L"CreateAdapter \"%s\" \"%s\" %.*s" : L"CreateAdapter \"%s\" \"%s\"",
+            Pool,
+            Name,
+            RequestedGUID ? StringFromGUID2(RequestedGUID, RequestedGUIDStr, _countof(RequestedGUIDStr)) : 0,
+            RequestedGUIDStr) == -1)
+        return LOG(WINTUN_LOG_ERR, L"Command line too long"), ERROR_INVALID_PARAMETER;
+    WCHAR Response[8 + 1 + MAX_GUID_STRING_LEN + 1 + 8 + 1];
+    DWORD Result = ExecuteRunDll32(Arguments, Response, _countof(Response));
+    if (Result != ERROR_SUCCESS)
+    {
+        LOG(WINTUN_LOG_ERR, L"Error executing worker process");
+        return Result;
+    }
+    int Argc;
+    WCHAR **Argv = CommandLineToArgvW(Response, &Argc);
+    GUID CfgInstanceID;
+    if (Argc < 3 || FAILED(CLSIDFromString(Argv[1], &CfgInstanceID)))
+    {
+        LOG(WINTUN_LOG_ERR, L"Incomplete or invalid response");
+        Result = ERROR_INVALID_PARAMETER;
+        goto cleanupArgv;
+    }
+    Result = wcstoul(Argv[0], NULL, 16);
+    if (Result == ERROR_SUCCESS && GetAdapter(Pool, &CfgInstanceID, Adapter) != ERROR_SUCCESS)
+    {
+        LOG(WINTUN_LOG_ERR, L"Failed to get adapter");
+        Result = ERROR_FILE_NOT_FOUND;
+    }
+    if (wcstoul(Argv[2], NULL, 16))
+        *RebootRequired = TRUE;
+cleanupArgv:
+    LocalFree(Argv);
+    return Result;
+}
+
+static WINTUN_STATUS
+DeleteAdapterViaRundll32(_In_ const WINTUN_ADAPTER *Adapter, _In_ BOOL ForceCloseSessions, _Inout_ BOOL *RebootRequired)
+{
+    LOG(WINTUN_LOG_INFO, L"Spawning native process");
+    WCHAR GuidStr[MAX_GUID_STRING_LEN];
+    WCHAR Arguments[16 + MAX_GUID_STRING_LEN + 1];
+    if (_snwprintf_s(
+            Arguments,
+            _countof(Arguments),
+            _TRUNCATE,
+            L"DeleteAdapter %d %.*s",
+            ForceCloseSessions ? 1 : 0,
+            StringFromGUID2(&Adapter->CfgInstanceID, GuidStr, _countof(GuidStr)),
+            GuidStr) == -1)
+        return LOG(WINTUN_LOG_ERR, L"Command line too long"), ERROR_INVALID_PARAMETER;
+    WCHAR Response[8 + 1 + 8 + 1];
+    DWORD Result = ExecuteRunDll32(Arguments, Response, _countof(Response));
+    if (Result != ERROR_SUCCESS)
+    {
+        LOG(WINTUN_LOG_ERR, L"Error executing worker process");
+        return Result;
+    }
+    int Argc;
+    WCHAR **Argv = CommandLineToArgvW(Response, &Argc);
+    if (Argc < 2)
+    {
+        LOG(WINTUN_LOG_ERR, L"Incomplete or invalid response");
+        Result = ERROR_INVALID_PARAMETER;
+        goto cleanupArgv;
+    }
+    Result = wcstoul(Argv[0], NULL, 16);
+    if (wcstoul(Argv[1], NULL, 16))
+        *RebootRequired = TRUE;
+cleanupArgv:
+    LocalFree(Argv);
+    return Result;
+}
+
+static WINTUN_STATUS
+DeleteDriverViaRundll32()
+{
+    LOG(WINTUN_LOG_INFO, L"Spawning native process");
+    WCHAR Response[8 + 1];
+    DWORD Result = ExecuteRunDll32(L"DeleteDriver", Response, _countof(Response));
+    if (Result != ERROR_SUCCESS)
+    {
+        LOG(WINTUN_LOG_ERR, L"Error executing worker process");
+        return Result;
+    }
+    int Argc;
+    WCHAR **Argv = CommandLineToArgvW(Response, &Argc);
+    if (Argc < 1)
+    {
+        LOG(WINTUN_LOG_ERR, L"Incomplete or invalid response");
+        Result = ERROR_INVALID_PARAMETER;
+        goto cleanupArgv;
+    }
+    Result = wcstoul(Argv[0], NULL, 16);
+cleanupArgv:
+    LocalFree(Argv);
+    return Result;
+}