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/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2018-2020 WireGuard LLC. All Rights Reserved.
*/
#include "elevate.h"
#include "logger.h"
#include <Windows.h>
#include <TlHelp32.h>
_Return_type_success_(return != FALSE) BOOL ElevateToSystem(void)
{
HANDLE CurrentProcessToken, ThreadToken, ProcessSnapshot, WinlogonProcess, WinlogonToken, DuplicatedToken;
PROCESSENTRY32W ProcessEntry = { .dwSize = sizeof(PROCESSENTRY32W) };
BOOL Ret;
DWORD LastError = ERROR_SUCCESS;
TOKEN_PRIVILEGES Privileges = { .PrivilegeCount = 1, .Privileges = { { .Attributes = SE_PRIVILEGE_ENABLED } } };
CHAR LocalSystemSid[0x400];
DWORD RequiredBytes = sizeof(LocalSystemSid);
struct
{
TOKEN_USER MaybeLocalSystem;
CHAR LargeEnoughForLocalSystem[0x400];
} TokenUserBuffer;
Ret = CreateWellKnownSid(WinLocalSystemSid, NULL, &LocalSystemSid, &RequiredBytes);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to create SID");
goto cleanup;
}
Ret = OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &CurrentProcessToken);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to open process token");
goto cleanup;
}
Ret =
GetTokenInformation(CurrentProcessToken, TokenUser, &TokenUserBuffer, sizeof(TokenUserBuffer), &RequiredBytes);
LastError = GetLastError();
CloseHandle(CurrentProcessToken);
if (!Ret)
{
LOG_ERROR(L"Failed to get token information", LastError);
goto cleanup;
}
if (EqualSid(TokenUserBuffer.MaybeLocalSystem.User.Sid, LocalSystemSid))
return TRUE;
Ret = LookupPrivilegeValueW(NULL, SE_DEBUG_NAME, &Privileges.Privileges[0].Luid);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to lookup privilege value");
goto cleanup;
}
ProcessSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if (ProcessSnapshot == INVALID_HANDLE_VALUE)
{
LastError = LOG_LAST_ERROR(L"Failed to create toolhelp snapshot");
goto cleanup;
}
for (Ret = Process32FirstW(ProcessSnapshot, &ProcessEntry); Ret;
Ret = Process32NextW(ProcessSnapshot, &ProcessEntry))
{
if (_wcsicmp(ProcessEntry.szExeFile, L"winlogon.exe"))
continue;
RevertToSelf();
Ret = ImpersonateSelf(SecurityImpersonation);
if (!Ret)
{
LastError = GetLastError();
continue;
}
Ret = OpenThreadToken(GetCurrentThread(), TOKEN_ADJUST_PRIVILEGES, FALSE, &ThreadToken);
if (!Ret)
{
LastError = GetLastError();
continue;
}
Ret = AdjustTokenPrivileges(ThreadToken, FALSE, &Privileges, sizeof(Privileges), NULL, NULL);
LastError = GetLastError();
CloseHandle(ThreadToken);
if (!Ret)
continue;
WinlogonProcess = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, ProcessEntry.th32ProcessID);
if (!WinlogonProcess)
{
LastError = GetLastError();
continue;
}
Ret = OpenProcessToken(WinlogonProcess, TOKEN_IMPERSONATE | TOKEN_DUPLICATE, &WinlogonToken);
LastError = GetLastError();
CloseHandle(WinlogonProcess);
if (!Ret)
continue;
Ret = DuplicateToken(WinlogonToken, SecurityImpersonation, &DuplicatedToken);
LastError = GetLastError();
CloseHandle(WinlogonToken);
if (!Ret)
continue;
if (!GetTokenInformation(DuplicatedToken, TokenUser, &TokenUserBuffer, sizeof(TokenUserBuffer), &RequiredBytes))
goto next;
if (!EqualSid(TokenUserBuffer.MaybeLocalSystem.User.Sid, LocalSystemSid))
{
SetLastError(ERROR_ACCESS_DENIED);
goto next;
}
if (!SetThreadToken(NULL, DuplicatedToken))
goto next;
CloseHandle(DuplicatedToken);
CloseHandle(ProcessSnapshot);
return TRUE;
next:
LastError = GetLastError();
CloseHandle(DuplicatedToken);
}
RevertToSelf();
CloseHandle(ProcessSnapshot);
cleanup:
SetLastError(LastError);
return FALSE;
}
_Return_type_success_(return != NULL) HANDLE GetPrimarySystemTokenFromThread(void)
{
HANDLE CurrentToken, DuplicatedToken;
BOOL Ret;
DWORD LastError;
TOKEN_PRIVILEGES Privileges = { .PrivilegeCount = 1, .Privileges = { { .Attributes = SE_PRIVILEGE_ENABLED } } };
CHAR LocalSystemSid[0x400];
DWORD RequiredBytes = sizeof(LocalSystemSid);
struct
{
TOKEN_USER MaybeLocalSystem;
CHAR LargeEnoughForLocalSystem[0x400];
} TokenUserBuffer;
Ret = CreateWellKnownSid(WinLocalSystemSid, NULL, &LocalSystemSid, &RequiredBytes);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to create SID");
return NULL;
}
Ret = OpenThreadToken(
GetCurrentThread(), TOKEN_QUERY | TOKEN_ADJUST_PRIVILEGES | TOKEN_DUPLICATE, FALSE, &CurrentToken);
if (!Ret && GetLastError() == ERROR_NO_TOKEN)
Ret = OpenProcessToken(
GetCurrentProcess(), TOKEN_QUERY | TOKEN_ADJUST_PRIVILEGES | TOKEN_DUPLICATE, &CurrentToken);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to open token");
return NULL;
}
Ret = GetTokenInformation(CurrentToken, TokenUser, &TokenUserBuffer, sizeof(TokenUserBuffer), &RequiredBytes);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to get token information");
goto cleanup;
}
if (!EqualSid(TokenUserBuffer.MaybeLocalSystem.User.Sid, LocalSystemSid))
{
LOG(WINTUN_LOG_ERR, L"Not SYSTEM");
LastError = ERROR_ACCESS_DENIED;
goto cleanup;
}
Ret = LookupPrivilegeValueW(NULL, SE_ASSIGNPRIMARYTOKEN_NAME, &Privileges.Privileges[0].Luid);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to lookup privilege value");
goto cleanup;
}
Ret = AdjustTokenPrivileges(CurrentToken, FALSE, &Privileges, sizeof(Privileges), NULL, NULL);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to adjust token privileges");
goto cleanup;
}
Ret = DuplicateTokenEx(
CurrentToken,
TOKEN_QUERY | TOKEN_DUPLICATE | TOKEN_ASSIGN_PRIMARY,
NULL,
SecurityImpersonation,
TokenPrimary,
&DuplicatedToken);
if (!Ret)
{
LastError = LOG_LAST_ERROR(L"Failed to duplicate token");
goto cleanup;
}
CloseHandle(CurrentToken);
return DuplicatedToken;
cleanup:
CloseHandle(CurrentToken);
SetLastError(LastError);
return NULL;
}
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