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      1 //===- KillTheDoctor - Prevent Dr. Watson from stopping tests ---*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This program provides an extremely hacky way to stop Dr. Watson from starting
     11 // due to unhandled exceptions in child processes.
     12 //
     13 // This simply starts the program named in the first positional argument with
     14 // the arguments following it under a debugger. All this debugger does is catch
     15 // any unhandled exceptions thrown in the child process and close the program
     16 // (and hopefully tells someone about it).
     17 //
     18 // This also provides another really hacky method to prevent assert dialog boxes
     19 // from popping up. When --no-user32 is passed, if any process loads user32.dll,
     20 // we assume it is trying to call MessageBoxEx and terminate it. The proper way
     21 // to do this would be to actually set a break point, but there's quite a bit
     22 // of code involved to get the address of MessageBoxEx in the remote process's
     23 // address space due to Address space layout randomization (ASLR). This can be
     24 // added if it's ever actually needed.
     25 //
     26 // If the subprocess exits for any reason other than successful termination, -1
     27 // is returned. If the process exits normally the value it returned is returned.
     28 //
     29 // I hate Windows.
     30 //
     31 //===----------------------------------------------------------------------===//
     32 
     33 #include "llvm/ADT/STLExtras.h"
     34 #include "llvm/ADT/SmallString.h"
     35 #include "llvm/ADT/SmallVector.h"
     36 #include "llvm/ADT/StringExtras.h"
     37 #include "llvm/ADT/StringRef.h"
     38 #include "llvm/ADT/Twine.h"
     39 #include "llvm/Support/CommandLine.h"
     40 #include "llvm/Support/ManagedStatic.h"
     41 #include "llvm/Support/PrettyStackTrace.h"
     42 #include "llvm/Support/Signals.h"
     43 #include "llvm/Support/WindowsError.h"
     44 #include "llvm/Support/raw_ostream.h"
     45 #include "llvm/Support/type_traits.h"
     46 #include <algorithm>
     47 #include <cerrno>
     48 #include <cstdlib>
     49 #include <map>
     50 #include <string>
     51 #include <system_error>
     52 
     53 // These includes must be last.
     54 #include <Windows.h>
     55 #include <WinError.h>
     56 #include <Dbghelp.h>
     57 #include <psapi.h>
     58 
     59 using namespace llvm;
     60 
     61 #undef max
     62 
     63 namespace {
     64   cl::opt<std::string> ProgramToRun(cl::Positional,
     65     cl::desc("<program to run>"));
     66   cl::list<std::string>  Argv(cl::ConsumeAfter,
     67     cl::desc("<program arguments>..."));
     68   cl::opt<bool> TraceExecution("x",
     69     cl::desc("Print detailed output about what is being run to stderr."));
     70   cl::opt<unsigned> Timeout("t", cl::init(0),
     71     cl::desc("Set maximum runtime in seconds. Defaults to infinite."));
     72   cl::opt<bool> NoUser32("no-user32",
     73     cl::desc("Terminate process if it loads user32.dll."));
     74 
     75   StringRef ToolName;
     76 
     77   template <typename HandleType>
     78   class ScopedHandle {
     79     typedef typename HandleType::handle_type handle_type;
     80 
     81     handle_type Handle;
     82 
     83   public:
     84     ScopedHandle()
     85       : Handle(HandleType::GetInvalidHandle()) {}
     86 
     87     explicit ScopedHandle(handle_type handle)
     88       : Handle(handle) {}
     89 
     90     ~ScopedHandle() {
     91       HandleType::Destruct(Handle);
     92     }
     93 
     94     ScopedHandle& operator=(handle_type handle) {
     95       // Cleanup current handle.
     96       if (!HandleType::isValid(Handle))
     97         HandleType::Destruct(Handle);
     98       Handle = handle;
     99       return *this;
    100     }
    101 
    102     operator bool() const {
    103       return HandleType::isValid(Handle);
    104     }
    105 
    106     operator handle_type() {
    107       return Handle;
    108     }
    109   };
    110 
    111   // This implements the most common handle in the Windows API.
    112   struct CommonHandle {
    113     typedef HANDLE handle_type;
    114 
    115     static handle_type GetInvalidHandle() {
    116       return INVALID_HANDLE_VALUE;
    117     }
    118 
    119     static void Destruct(handle_type Handle) {
    120       ::CloseHandle(Handle);
    121     }
    122 
    123     static bool isValid(handle_type Handle) {
    124       return Handle != GetInvalidHandle();
    125     }
    126   };
    127 
    128   struct FileMappingHandle {
    129     typedef HANDLE handle_type;
    130 
    131     static handle_type GetInvalidHandle() {
    132       return NULL;
    133     }
    134 
    135     static void Destruct(handle_type Handle) {
    136       ::CloseHandle(Handle);
    137     }
    138 
    139     static bool isValid(handle_type Handle) {
    140       return Handle != GetInvalidHandle();
    141     }
    142   };
    143 
    144   struct MappedViewOfFileHandle {
    145     typedef LPVOID handle_type;
    146 
    147     static handle_type GetInvalidHandle() {
    148       return NULL;
    149     }
    150 
    151     static void Destruct(handle_type Handle) {
    152       ::UnmapViewOfFile(Handle);
    153     }
    154 
    155     static bool isValid(handle_type Handle) {
    156       return Handle != GetInvalidHandle();
    157     }
    158   };
    159 
    160   struct ProcessHandle : CommonHandle {};
    161   struct ThreadHandle  : CommonHandle {};
    162   struct TokenHandle   : CommonHandle {};
    163   struct FileHandle    : CommonHandle {};
    164 
    165   typedef ScopedHandle<FileMappingHandle>       FileMappingScopedHandle;
    166   typedef ScopedHandle<MappedViewOfFileHandle>  MappedViewOfFileScopedHandle;
    167   typedef ScopedHandle<ProcessHandle>           ProcessScopedHandle;
    168   typedef ScopedHandle<ThreadHandle>            ThreadScopedHandle;
    169   typedef ScopedHandle<TokenHandle>             TokenScopedHandle;
    170   typedef ScopedHandle<FileHandle>              FileScopedHandle;
    171 }
    172 
    173 static std::error_code windows_error(DWORD E) { return mapWindowsError(E); }
    174 
    175 static std::error_code GetFileNameFromHandle(HANDLE FileHandle,
    176                                              std::string &Name) {
    177   char Filename[MAX_PATH+1];
    178   bool Success = false;
    179   Name.clear();
    180 
    181   // Get the file size.
    182   LARGE_INTEGER FileSize;
    183   Success = ::GetFileSizeEx(FileHandle, &FileSize);
    184 
    185   if (!Success)
    186     return windows_error(::GetLastError());
    187 
    188   // Create a file mapping object.
    189   FileMappingScopedHandle FileMapping(
    190     ::CreateFileMappingA(FileHandle,
    191                          NULL,
    192                          PAGE_READONLY,
    193                          0,
    194                          1,
    195                          NULL));
    196 
    197   if (!FileMapping)
    198     return windows_error(::GetLastError());
    199 
    200   // Create a file mapping to get the file name.
    201   MappedViewOfFileScopedHandle MappedFile(
    202     ::MapViewOfFile(FileMapping, FILE_MAP_READ, 0, 0, 1));
    203 
    204   if (!MappedFile)
    205     return windows_error(::GetLastError());
    206 
    207   Success = ::GetMappedFileNameA(::GetCurrentProcess(),
    208                                 MappedFile,
    209                                 Filename,
    210                                 array_lengthof(Filename) - 1);
    211 
    212   if (!Success)
    213     return windows_error(::GetLastError());
    214   else {
    215     Name = Filename;
    216     return std::error_code();
    217   }
    218 }
    219 
    220 /// @brief Find program using shell lookup rules.
    221 /// @param Program This is either an absolute path, relative path, or simple a
    222 ///        program name. Look in PATH for any programs that match. If no
    223 ///        extension is present, try all extensions in PATHEXT.
    224 /// @return If ec == errc::success, The absolute path to the program. Otherwise
    225 ///         the return value is undefined.
    226 static std::string FindProgram(const std::string &Program,
    227                                std::error_code &ec) {
    228   char PathName[MAX_PATH + 1];
    229   typedef SmallVector<StringRef, 12> pathext_t;
    230   pathext_t pathext;
    231   // Check for the program without an extension (in case it already has one).
    232   pathext.push_back("");
    233   SplitString(std::getenv("PATHEXT"), pathext, ";");
    234 
    235   for (pathext_t::iterator i = pathext.begin(), e = pathext.end(); i != e; ++i){
    236     SmallString<5> ext;
    237     for (std::size_t ii = 0, e = i->size(); ii != e; ++ii)
    238       ext.push_back(::tolower((*i)[ii]));
    239     LPCSTR Extension = NULL;
    240     if (ext.size() && ext[0] == '.')
    241       Extension = ext.c_str();
    242     DWORD length = ::SearchPathA(NULL,
    243                                  Program.c_str(),
    244                                  Extension,
    245                                  array_lengthof(PathName),
    246                                  PathName,
    247                                  NULL);
    248     if (length == 0)
    249       ec = windows_error(::GetLastError());
    250     else if (length > array_lengthof(PathName)) {
    251       // This may have been the file, return with error.
    252       ec = windows_error(ERROR_BUFFER_OVERFLOW);
    253       break;
    254     } else {
    255       // We found the path! Return it.
    256       ec = std::error_code();
    257       break;
    258     }
    259   }
    260 
    261   // Make sure PathName is valid.
    262   PathName[MAX_PATH] = 0;
    263   return PathName;
    264 }
    265 
    266 static StringRef ExceptionCodeToString(DWORD ExceptionCode) {
    267   switch(ExceptionCode) {
    268   case EXCEPTION_ACCESS_VIOLATION: return "EXCEPTION_ACCESS_VIOLATION";
    269   case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
    270     return "EXCEPTION_ARRAY_BOUNDS_EXCEEDED";
    271   case EXCEPTION_BREAKPOINT: return "EXCEPTION_BREAKPOINT";
    272   case EXCEPTION_DATATYPE_MISALIGNMENT:
    273     return "EXCEPTION_DATATYPE_MISALIGNMENT";
    274   case EXCEPTION_FLT_DENORMAL_OPERAND: return "EXCEPTION_FLT_DENORMAL_OPERAND";
    275   case EXCEPTION_FLT_DIVIDE_BY_ZERO: return "EXCEPTION_FLT_DIVIDE_BY_ZERO";
    276   case EXCEPTION_FLT_INEXACT_RESULT: return "EXCEPTION_FLT_INEXACT_RESULT";
    277   case EXCEPTION_FLT_INVALID_OPERATION:
    278     return "EXCEPTION_FLT_INVALID_OPERATION";
    279   case EXCEPTION_FLT_OVERFLOW: return "EXCEPTION_FLT_OVERFLOW";
    280   case EXCEPTION_FLT_STACK_CHECK: return "EXCEPTION_FLT_STACK_CHECK";
    281   case EXCEPTION_FLT_UNDERFLOW: return "EXCEPTION_FLT_UNDERFLOW";
    282   case EXCEPTION_ILLEGAL_INSTRUCTION: return "EXCEPTION_ILLEGAL_INSTRUCTION";
    283   case EXCEPTION_IN_PAGE_ERROR: return "EXCEPTION_IN_PAGE_ERROR";
    284   case EXCEPTION_INT_DIVIDE_BY_ZERO: return "EXCEPTION_INT_DIVIDE_BY_ZERO";
    285   case EXCEPTION_INT_OVERFLOW: return "EXCEPTION_INT_OVERFLOW";
    286   case EXCEPTION_INVALID_DISPOSITION: return "EXCEPTION_INVALID_DISPOSITION";
    287   case EXCEPTION_NONCONTINUABLE_EXCEPTION:
    288     return "EXCEPTION_NONCONTINUABLE_EXCEPTION";
    289   case EXCEPTION_PRIV_INSTRUCTION: return "EXCEPTION_PRIV_INSTRUCTION";
    290   case EXCEPTION_SINGLE_STEP: return "EXCEPTION_SINGLE_STEP";
    291   case EXCEPTION_STACK_OVERFLOW: return "EXCEPTION_STACK_OVERFLOW";
    292   default: return "<unknown>";
    293   }
    294 }
    295 
    296 int main(int argc, char **argv) {
    297   // Print a stack trace if we signal out.
    298   sys::PrintStackTraceOnErrorSignal();
    299   PrettyStackTraceProgram X(argc, argv);
    300   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    301 
    302   ToolName = argv[0];
    303 
    304   cl::ParseCommandLineOptions(argc, argv, "Dr. Watson Assassin.\n");
    305   if (ProgramToRun.size() == 0) {
    306     cl::PrintHelpMessage();
    307     return -1;
    308   }
    309 
    310   if (Timeout > std::numeric_limits<uint32_t>::max() / 1000) {
    311     errs() << ToolName << ": Timeout value too large, must be less than: "
    312                        << std::numeric_limits<uint32_t>::max() / 1000
    313                        << '\n';
    314     return -1;
    315   }
    316 
    317   std::string CommandLine(ProgramToRun);
    318 
    319   std::error_code ec;
    320   ProgramToRun = FindProgram(ProgramToRun, ec);
    321   if (ec) {
    322     errs() << ToolName << ": Failed to find program: '" << CommandLine
    323            << "': " << ec.message() << '\n';
    324     return -1;
    325   }
    326 
    327   if (TraceExecution)
    328     errs() << ToolName << ": Found Program: " << ProgramToRun << '\n';
    329 
    330   for (std::vector<std::string>::iterator i = Argv.begin(),
    331                                           e = Argv.end();
    332                                           i != e; ++i) {
    333     CommandLine.push_back(' ');
    334     CommandLine.append(*i);
    335   }
    336 
    337   if (TraceExecution)
    338     errs() << ToolName << ": Program Image Path: " << ProgramToRun << '\n'
    339            << ToolName << ": Command Line: " << CommandLine << '\n';
    340 
    341   STARTUPINFO StartupInfo;
    342   PROCESS_INFORMATION ProcessInfo;
    343   std::memset(&StartupInfo, 0, sizeof(StartupInfo));
    344   StartupInfo.cb = sizeof(StartupInfo);
    345   std::memset(&ProcessInfo, 0, sizeof(ProcessInfo));
    346 
    347   // Set error mode to not display any message boxes. The child process inherits
    348   // this.
    349   ::SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX);
    350   ::_set_error_mode(_OUT_TO_STDERR);
    351 
    352   BOOL success = ::CreateProcessA(ProgramToRun.c_str(),
    353                             LPSTR(CommandLine.c_str()),
    354                                   NULL,
    355                                   NULL,
    356                                   FALSE,
    357                                   DEBUG_PROCESS,
    358                                   NULL,
    359                                   NULL,
    360                                   &StartupInfo,
    361                                   &ProcessInfo);
    362   if (!success) {
    363     errs() << ToolName << ": Failed to run program: '" << ProgramToRun << "': "
    364            << std::error_code(windows_error(::GetLastError())).message()
    365            << '\n';
    366     return -1;
    367   }
    368 
    369   // Make sure ::CloseHandle is called on exit.
    370   std::map<DWORD, HANDLE> ProcessIDToHandle;
    371 
    372   DEBUG_EVENT DebugEvent;
    373   std::memset(&DebugEvent, 0, sizeof(DebugEvent));
    374   DWORD dwContinueStatus = DBG_CONTINUE;
    375 
    376   // Run the program under the debugger until either it exits, or throws an
    377   // exception.
    378   if (TraceExecution)
    379     errs() << ToolName << ": Debugging...\n";
    380 
    381   while(true) {
    382     DWORD TimeLeft = INFINITE;
    383     if (Timeout > 0) {
    384       FILETIME CreationTime, ExitTime, KernelTime, UserTime;
    385       ULARGE_INTEGER a, b;
    386       success = ::GetProcessTimes(ProcessInfo.hProcess,
    387                                   &CreationTime,
    388                                   &ExitTime,
    389                                   &KernelTime,
    390                                   &UserTime);
    391       if (!success) {
    392         ec = windows_error(::GetLastError());
    393 
    394         errs() << ToolName << ": Failed to get process times: "
    395                << ec.message() << '\n';
    396         return -1;
    397       }
    398       a.LowPart = KernelTime.dwLowDateTime;
    399       a.HighPart = KernelTime.dwHighDateTime;
    400       b.LowPart = UserTime.dwLowDateTime;
    401       b.HighPart = UserTime.dwHighDateTime;
    402       // Convert 100-nanosecond units to milliseconds.
    403       uint64_t TotalTimeMiliseconds = (a.QuadPart + b.QuadPart) / 10000;
    404       // Handle the case where the process has been running for more than 49
    405       // days.
    406       if (TotalTimeMiliseconds > std::numeric_limits<uint32_t>::max()) {
    407         errs() << ToolName << ": Timeout Failed: Process has been running for"
    408                               "more than 49 days.\n";
    409         return -1;
    410       }
    411 
    412       // We check with > instead of using Timeleft because if
    413       // TotalTimeMiliseconds is greater than Timeout * 1000, TimeLeft would
    414       // underflow.
    415       if (TotalTimeMiliseconds > (Timeout * 1000)) {
    416         errs() << ToolName << ": Process timed out.\n";
    417         ::TerminateProcess(ProcessInfo.hProcess, -1);
    418         // Otherwise other stuff starts failing...
    419         return -1;
    420       }
    421 
    422       TimeLeft = (Timeout * 1000) - static_cast<uint32_t>(TotalTimeMiliseconds);
    423     }
    424     success = WaitForDebugEvent(&DebugEvent, TimeLeft);
    425 
    426     if (!success) {
    427       DWORD LastError = ::GetLastError();
    428       ec = windows_error(LastError);
    429 
    430       if (LastError == ERROR_SEM_TIMEOUT || LastError == WSAETIMEDOUT) {
    431         errs() << ToolName << ": Process timed out.\n";
    432         ::TerminateProcess(ProcessInfo.hProcess, -1);
    433         // Otherwise other stuff starts failing...
    434         return -1;
    435       }
    436 
    437       errs() << ToolName << ": Failed to wait for debug event in program: '"
    438              << ProgramToRun << "': " << ec.message() << '\n';
    439       return -1;
    440     }
    441 
    442     switch(DebugEvent.dwDebugEventCode) {
    443     case CREATE_PROCESS_DEBUG_EVENT:
    444       // Make sure we remove the handle on exit.
    445       if (TraceExecution)
    446         errs() << ToolName << ": Debug Event: CREATE_PROCESS_DEBUG_EVENT\n";
    447       ProcessIDToHandle[DebugEvent.dwProcessId] =
    448         DebugEvent.u.CreateProcessInfo.hProcess;
    449       ::CloseHandle(DebugEvent.u.CreateProcessInfo.hFile);
    450       break;
    451     case EXIT_PROCESS_DEBUG_EVENT: {
    452         if (TraceExecution)
    453           errs() << ToolName << ": Debug Event: EXIT_PROCESS_DEBUG_EVENT\n";
    454 
    455         // If this is the process we originally created, exit with its exit
    456         // code.
    457         if (DebugEvent.dwProcessId == ProcessInfo.dwProcessId)
    458           return DebugEvent.u.ExitProcess.dwExitCode;
    459 
    460         // Otherwise cleanup any resources we have for it.
    461         std::map<DWORD, HANDLE>::iterator ExitingProcess =
    462           ProcessIDToHandle.find(DebugEvent.dwProcessId);
    463         if (ExitingProcess == ProcessIDToHandle.end()) {
    464           errs() << ToolName << ": Got unknown process id!\n";
    465           return -1;
    466         }
    467         ::CloseHandle(ExitingProcess->second);
    468         ProcessIDToHandle.erase(ExitingProcess);
    469       }
    470       break;
    471     case CREATE_THREAD_DEBUG_EVENT:
    472       ::CloseHandle(DebugEvent.u.CreateThread.hThread);
    473       break;
    474     case LOAD_DLL_DEBUG_EVENT: {
    475         // Cleanup the file handle.
    476         FileScopedHandle DLLFile(DebugEvent.u.LoadDll.hFile);
    477         std::string DLLName;
    478         ec = GetFileNameFromHandle(DLLFile, DLLName);
    479         if (ec) {
    480           DLLName = "<failed to get file name from file handle> : ";
    481           DLLName += ec.message();
    482         }
    483         if (TraceExecution) {
    484           errs() << ToolName << ": Debug Event: LOAD_DLL_DEBUG_EVENT\n";
    485           errs().indent(ToolName.size()) << ": DLL Name : " << DLLName << '\n';
    486         }
    487 
    488         if (NoUser32 && sys::path::stem(DLLName) == "user32") {
    489           // Program is loading user32.dll, in the applications we are testing,
    490           // this only happens if an assert has fired. By now the message has
    491           // already been printed, so simply close the program.
    492           errs() << ToolName << ": user32.dll loaded!\n";
    493           errs().indent(ToolName.size())
    494                  << ": This probably means that assert was called. Closing "
    495                     "program to prevent message box from popping up.\n";
    496           dwContinueStatus = DBG_CONTINUE;
    497           ::TerminateProcess(ProcessIDToHandle[DebugEvent.dwProcessId], -1);
    498           return -1;
    499         }
    500       }
    501       break;
    502     case EXCEPTION_DEBUG_EVENT: {
    503         // Close the application if this exception will not be handled by the
    504         // child application.
    505         if (TraceExecution)
    506           errs() << ToolName << ": Debug Event: EXCEPTION_DEBUG_EVENT\n";
    507 
    508         EXCEPTION_DEBUG_INFO  &Exception = DebugEvent.u.Exception;
    509         if (Exception.dwFirstChance > 0) {
    510           if (TraceExecution) {
    511             errs().indent(ToolName.size()) << ": Debug Info : ";
    512             errs() << "First chance exception at "
    513                    << Exception.ExceptionRecord.ExceptionAddress
    514                    << ", exception code: "
    515                    << ExceptionCodeToString(
    516                         Exception.ExceptionRecord.ExceptionCode)
    517                    << " (" << Exception.ExceptionRecord.ExceptionCode << ")\n";
    518           }
    519           dwContinueStatus = DBG_EXCEPTION_NOT_HANDLED;
    520         } else {
    521           errs() << ToolName << ": Unhandled exception in: " << ProgramToRun
    522                  << "!\n";
    523                  errs().indent(ToolName.size()) << ": location: ";
    524                  errs() << Exception.ExceptionRecord.ExceptionAddress
    525                         << ", exception code: "
    526                         << ExceptionCodeToString(
    527                             Exception.ExceptionRecord.ExceptionCode)
    528                         << " (" << Exception.ExceptionRecord.ExceptionCode
    529                         << ")\n";
    530           dwContinueStatus = DBG_CONTINUE;
    531           ::TerminateProcess(ProcessIDToHandle[DebugEvent.dwProcessId], -1);
    532           return -1;
    533         }
    534       }
    535       break;
    536     default:
    537       // Do nothing.
    538       if (TraceExecution)
    539         errs() << ToolName << ": Debug Event: <unknown>\n";
    540       break;
    541     }
    542 
    543     success = ContinueDebugEvent(DebugEvent.dwProcessId,
    544                                  DebugEvent.dwThreadId,
    545                                  dwContinueStatus);
    546     if (!success) {
    547       ec = windows_error(::GetLastError());
    548       errs() << ToolName << ": Failed to continue debugging program: '"
    549              << ProgramToRun << "': " << ec.message() << '\n';
    550       return -1;
    551     }
    552 
    553     dwContinueStatus = DBG_CONTINUE;
    554   }
    555 
    556   assert(0 && "Fell out of debug loop. This shouldn't be possible!");
    557   return -1;
    558 }
    559