// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome_elf/blacklist/blacklist.h"

#include <assert.h>
#include <string.h>

#include <vector>

#include "chrome/install_static/install_util.h"
#include "chrome_elf/blacklist/blacklist_interceptions.h"
#include "chrome_elf/chrome_elf_constants.h"
#include "chrome_elf/hook_util/hook_util.h"
#include "chrome_elf/nt_registry/nt_registry.h"
#include "sandbox/win/src/interception_internal.h"
#include "sandbox/win/src/internal_types.h"
#include "sandbox/win/src/service_resolver.h"

// http://blogs.msdn.com/oldnewthing/archive/2004/10/25/247180.aspx
extern "C" IMAGE_DOS_HEADER __ImageBase;

namespace blacklist {

// The DLLs listed here are known (or under strong suspicion) of causing crashes
// when they are loaded in the browser. DLLs should only be added to this list
// if there is nothing else Chrome can do to prevent those crashes.
// For more information about how this list is generated, and how to get off
// of it, see:
// https://sites.google.com/a/chromium.org/dev/Home/third-party-developers
// NOTE: Please remember to update the DllHash enum in histograms.xml when
//       adding a new value to the blacklist.
const wchar_t* g_troublesome_dlls[kTroublesomeDllsMaxCount] = {
    L"949ba8b6a9.dll",           // Coupon Time.
    L"activedetect32.dll",       // Lenovo One Key Theater.
                                 // See crbug.com/379218.
    L"activedetect64.dll",       // Lenovo One Key Theater.
    L"bitguard.dll",             // Unknown (suspected malware).
    L"bsvc.dll",                 // Unknown (suspected adware).
    L"chrmxtn.dll",              // Unknown (keystroke logger).
    L"cplushook.dll",            // Unknown (suspected malware).
    L"crdli.dll",                // Linkury Inc.
    L"crdli64.dll",              // Linkury Inc.
    L"datamngr.dll",             // Unknown (suspected adware).
    L"dpinterface32.dll",        // Unknown (suspected adware).
    L"explorerex.dll",           // Unknown (suspected adware).
    L"hk.dll",                   // Unknown (keystroke logger).
    L"libapi2hook.dll",          // V-Bates.
    L"libinject.dll",            // V-Bates.
    L"libinject2.dll",           // V-Bates.
    L"libredir2.dll",            // V-Bates.
    L"libsvn_tsvn32.dll",        // TortoiseSVN.
    L"libwinhook.dll",           // V-Bates.
    L"lmrn.dll",                 // Unknown.
    L"minisp.dll",               // Unknown (suspected malware).
    L"minisp32.dll",             // Unknown (suspected malware).
    L"offerswizarddll.dll",      // Unknown (suspected adware).
    L"safetynut.dll",            // Unknown (suspected adware).
    L"smdmf.dll",                // Unknown (suspected adware).
    L"spappsv32.dll",            // Unknown (suspected adware).
    L"systemk.dll",              // Unknown (suspected adware).
    L"vntsrv.dll",               // Virtual New Tab by APN LLC.
    L"wajam_goblin_64.dll",      // Wajam Internet Technologies.
    L"wajam_goblin.dll",         // Wajam Internet Technologies.
    L"windowsapihookdll32.dll",  // Lenovo One Key Theater.
                                 // See crbug.com/379218.
    L"windowsapihookdll64.dll",  // Lenovo One Key Theater.
    L"virtualcamera.ax",         // %PROGRAMFILES%\ASUS\VirtualCamera.
                                 // See crbug.com/422522.
    L"ycwebcamerasource.ax",     // CyberLink Youcam, crbug.com/424159
    // Keep this null pointer here to mark the end of the list.
    NULL,
};

bool g_blocked_dlls[kTroublesomeDllsMaxCount] = {};
int g_num_blocked_dlls = 0;

}  // namespace blacklist

// Allocate storage for thunks in a page of this module to save on doing
// an extra allocation at run time.
#pragma section(".crthunk", read, execute)
__declspec(allocate(".crthunk")) sandbox::ThunkData g_thunk_storage;

namespace {

// Record if the blacklist was successfully initialized so processes can easily
// determine if the blacklist is enabled for them.
bool g_blacklist_initialized = false;

}  // namespace

namespace blacklist {

#if defined(_WIN64)
// Allocate storage for the pointer to the old NtMapViewOfSectionFunction.
#pragma section(".oldntmap", write, read)
__declspec(allocate(".oldntmap"))
    NtMapViewOfSectionFunction g_nt_map_view_of_section_func = NULL;
#endif

bool LeaveSetupBeacon() {
  HANDLE key_handle = INVALID_HANDLE_VALUE;

  if (!nt::CreateRegKey(nt::HKCU, kRegistryBeaconPath,
                        KEY_QUERY_VALUE | KEY_SET_VALUE, &key_handle))
    return false;

  DWORD blacklist_state = BLACKLIST_STATE_MAX;
  if (!nt::QueryRegValueDWORD(key_handle, kBeaconState, &blacklist_state) ||
      blacklist_state == BLACKLIST_DISABLED) {
    nt::CloseRegKey(key_handle);
    return false;
  }

  // Handle attempt count.
  // Only return true if BL is enabled and succeeded on previous run.
  bool success = false;
  if (blacklist_state == BLACKLIST_ENABLED) {
    // If the blacklist succeeded on the previous run reset the failure
    // counter.  Then update the beacon state.
    if (nt::SetRegValueDWORD(key_handle, kBeaconAttemptCount,
                             static_cast<DWORD>(0))) {
      if (nt::SetRegValueDWORD(key_handle, kBeaconState,
                               BLACKLIST_SETUP_RUNNING))
        success = true;
    }
  } else {
    // Some part of the blacklist setup failed last time.  If this has occured
    // blacklist::kBeaconMaxAttempts times in a row we switch the state to
    // failed and skip setting up the blacklist.
    DWORD attempt_count = 0;

    nt::QueryRegValueDWORD(key_handle, blacklist::kBeaconAttemptCount,
                           &attempt_count);
    ++attempt_count;
    nt::SetRegValueDWORD(key_handle, blacklist::kBeaconAttemptCount,
                         attempt_count);

    if (attempt_count >= blacklist::kBeaconMaxAttempts) {
      blacklist_state = blacklist::BLACKLIST_SETUP_FAILED;
      nt::SetRegValueDWORD(key_handle, blacklist::kBeaconState,
                           blacklist_state);
    }
  }

  nt::CloseRegKey(key_handle);
  return success;
}

bool ResetBeacon() {
  HANDLE key_handle = INVALID_HANDLE_VALUE;

  if (!nt::CreateRegKey(nt::HKCU, kRegistryBeaconPath,
                        KEY_QUERY_VALUE | KEY_SET_VALUE, &key_handle))
    return false;

  DWORD blacklist_state = BLACKLIST_STATE_MAX;
  if (!nt::QueryRegValueDWORD(key_handle, kBeaconState, &blacklist_state)) {
    nt::CloseRegKey(key_handle);
    return false;
  }

  // Reaching this point with the setup running state means the setup did not
  // crash, so we reset to enabled.  Any other state indicates that setup was
  // skipped; in that case we leave the state alone for later recording.
  if (blacklist_state == BLACKLIST_SETUP_RUNNING) {
    if (!nt::SetRegValueDWORD(key_handle, kBeaconState, BLACKLIST_ENABLED)) {
      nt::CloseRegKey(key_handle);
      return false;
    }
  }

  nt::CloseRegKey(key_handle);
  return true;
}

int BlacklistSize() {
  int size = -1;
  while (blacklist::g_troublesome_dlls[++size] != NULL) {
  }

  return size;
}

bool IsBlacklistInitialized() {
  return g_blacklist_initialized;
}

int GetBlacklistIndex(const wchar_t* dll_name) {
  for (int i = 0;
       i < static_cast<int>(kTroublesomeDllsMaxCount) && g_troublesome_dlls[i];
       ++i) {
    if (_wcsicmp(dll_name, g_troublesome_dlls[i]) == 0)
      return i;
  }
  return -1;
}

bool AddDllToBlacklist(const wchar_t* dll_name) {
  int blacklist_size = BlacklistSize();
  // We need to leave one space at the end for the null pointer.
  if (blacklist_size + 1 >= static_cast<int>(kTroublesomeDllsMaxCount))
    return false;
  for (int i = 0; i < blacklist_size; ++i) {
    if (!_wcsicmp(g_troublesome_dlls[i], dll_name))
      return true;
  }

  // Copy string to blacklist.
  wchar_t* str_buffer = new wchar_t[wcslen(dll_name) + 1];
  wcscpy(str_buffer, dll_name);

  g_troublesome_dlls[blacklist_size] = str_buffer;
  g_blocked_dlls[blacklist_size] = false;
  return true;
}

bool RemoveDllFromBlacklist(const wchar_t* dll_name) {
  int blacklist_size = BlacklistSize();
  for (int i = 0; i < blacklist_size; ++i) {
    if (!_wcsicmp(g_troublesome_dlls[i], dll_name)) {
      // Found the thing to remove. Delete it then replace it with the last
      // element.
      delete[] g_troublesome_dlls[i];
      g_troublesome_dlls[i] = g_troublesome_dlls[blacklist_size - 1];
      g_troublesome_dlls[blacklist_size - 1] = NULL;

      // Also update the stats recording if we have blocked this dll or not.
      if (g_blocked_dlls[i])
        --g_num_blocked_dlls;
      g_blocked_dlls[i] = g_blocked_dlls[blacklist_size - 1];
      return true;
    }
  }
  return false;
}

// TODO(csharp): Maybe store these values in the registry so we can
// still report them if Chrome crashes early.
void SuccessfullyBlocked(const wchar_t** blocked_dlls, int* size) {
  if (size == NULL)
    return;

  // If the array isn't valid or big enough, just report the size it needs to
  // be and return.
  if (blocked_dlls == NULL && *size < g_num_blocked_dlls) {
    *size = g_num_blocked_dlls;
    return;
  }

  *size = g_num_blocked_dlls;

  int strings_to_fill = 0;
  for (int i = 0; strings_to_fill < g_num_blocked_dlls && g_troublesome_dlls[i];
       ++i) {
    if (g_blocked_dlls[i]) {
      blocked_dlls[strings_to_fill] = g_troublesome_dlls[i];
      ++strings_to_fill;
    }
  }
}

void BlockedDll(size_t blocked_index) {
  assert(blocked_index < kTroublesomeDllsMaxCount);

  if (!g_blocked_dlls[blocked_index] &&
      blocked_index < kTroublesomeDllsMaxCount) {
    ++g_num_blocked_dlls;
    g_blocked_dlls[blocked_index] = true;
  }
}

bool Initialize(bool force) {
  // Check to see that we found the functions we need in ntdll.
  if (!InitializeInterceptImports())
    return false;

  // Check to see if this is a non-browser process, abort if so.
  if (install_static::IsNonBrowserProcess())
    return false;

  // Check to see if the blacklist beacon is still set to running (indicating a
  // failure) or disabled, and abort if so.
  if (!force && !LeaveSetupBeacon())
    return false;

  // It is possible for other dlls to have already patched code by now and
  // attempting to patch their code might result in crashes.
  const bool kRelaxed = false;

  // Create a thunk via the appropriate ServiceResolver instance.
  sandbox::ServiceResolverThunk* thunk = elf_hook::HookSystemService(kRelaxed);

  // Don't try blacklisting on unsupported OS versions.
  if (!thunk)
    return false;

  BYTE* thunk_storage = reinterpret_cast<BYTE*>(&g_thunk_storage);

  // Mark the thunk storage as readable and writeable, since we
  // ready to write to it.
  DWORD old_protect = 0;
  if (!VirtualProtect(&g_thunk_storage, sizeof(g_thunk_storage),
                      PAGE_EXECUTE_READWRITE, &old_protect)) {
    return false;
  }

  thunk->AllowLocalPatches();

  // We declare this early so it can be used in the 64-bit block below and
  // still work on 32-bit build when referenced at the end of the function.
  BOOL page_executable = false;

// Replace the default NtMapViewOfSection with our patched version.
#if defined(_WIN64)
  NTSTATUS ret =
      thunk->Setup(::GetModuleHandle(sandbox::kNtdllName),
                   reinterpret_cast<void*>(&__ImageBase), "NtMapViewOfSection",
                   NULL, &blacklist::BlNtMapViewOfSection64, thunk_storage,
                   sizeof(sandbox::ThunkData), NULL);

  // Keep a pointer to the original code, we don't have enough space to
  // add it directly to the call.
  g_nt_map_view_of_section_func =
      reinterpret_cast<NtMapViewOfSectionFunction>(thunk_storage);

  // Ensure that the pointer to the old function can't be changed.
  page_executable = VirtualProtect(&g_nt_map_view_of_section_func,
                                   sizeof(g_nt_map_view_of_section_func),
                                   PAGE_EXECUTE_READ, &old_protect);
#else
  NTSTATUS ret =
      thunk->Setup(::GetModuleHandle(sandbox::kNtdllName),
                   reinterpret_cast<void*>(&__ImageBase), "NtMapViewOfSection",
                   NULL, &blacklist::BlNtMapViewOfSection, thunk_storage,
                   sizeof(sandbox::ThunkData), NULL);
#endif
  delete thunk;

  // Record if we have initialized the blacklist.
  g_blacklist_initialized = NT_SUCCESS(ret);

  // Mark the thunk storage as executable and prevent any future writes to it.
  page_executable = page_executable &&
                    VirtualProtect(&g_thunk_storage, sizeof(g_thunk_storage),
                                   PAGE_EXECUTE_READ, &old_protect);

  return NT_SUCCESS(ret) && page_executable;
}

}  // namespace blacklist