Use an alternate mechanism for CreateFile calls in Chrome

BUG=334379

Review URL: https://codereview.chromium.org/138593004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245464 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 683 insertions, 1 deletions

diff --git a/chrome_elf/chrome_elf.def b/chrome_elf/chrome_elf.def
index d7d4c9c..36a1e45 100644
--- a/chrome_elf/chrome_elf.def
+++ b/chrome_elf/chrome_elf.def
@@ -5,4 +5,5 @@
 LIBRARY  "chrome_elf.dll"
 
 EXPORTS
+  CreateFileW=chrome_redirects.CreateFileW
   SignalChromeElf
diff --git a/chrome_elf/chrome_elf.gyp b/chrome_elf/chrome_elf.gyp
index 92c8294..94dd695 100644
--- a/chrome_elf/chrome_elf.gyp
+++ b/chrome_elf/chrome_elf.gyp
@@ -11,6 +11,35 @@
     'blacklist.gypi',
   ],
   'targets': [
+   {
+      'target_name': 'chrome_redirects',
+      'type': 'shared_library',
+      'include_dirs': [
+        '..',
+      ],
+      'sources': [
+        'chrome_redirects.def',
+      ],
+      'dependencies': [
+        'chrome_elf_lib',
+      ],
+      'msvs_settings': {
+        'VCLinkerTool': {
+          'BaseAddress': '0x01c10000',
+          # Set /SUBSYSTEM:WINDOWS.
+          'SubSystem': '2',
+        },
+      },
+      'conditions': [
+        ['component=="shared_library"', {
+          # In component builds, all targets depend on chrome_redirects by
+          # default. Remove it here to avoid a circular dependency.
+          'dependencies!': [
+            '../chrome_elf/chrome_elf.gyp:chrome_redirects',
+          ],
+        }],
+      ],
+    },
     {
       'target_name': 'chrome_elf',
       'type': 'shared_library',
@@ -25,11 +54,12 @@
       'dependencies': [
         'blacklist',
         'chrome_elf_lib',
+        'chrome_redirects',
       ],
       'msvs_settings': {
         'VCLinkerTool': {
           'BaseAddress': '0x01c20000',
-          # Set /SUBSYSTEM:WINDOWS for chrome_elf.dll (for consistency).
+          # Set /SUBSYSTEM:WINDOWS.
           'SubSystem': '2',
           'AdditionalDependencies!': [
             'user32.lib',
@@ -45,6 +75,7 @@
       'type': 'executable',
       'sources': [
         'blacklist/test/blacklist_test.cc',
+        'create_file/chrome_create_file_unittest.cc',
         'elf_imports_unittest.cc',
         'ntdll_cache_unittest.cc',
       ],
@@ -73,10 +104,23 @@
         '..',
       ],
       'sources': [
+        'chrome_elf_constants.cc',
+        'chrome_elf_constants.h',
         'chrome_elf_types.h',
+        'create_file/chrome_create_file.cc',
+        'create_file/chrome_create_file.h',
         'ntdll_cache.cc',
         'ntdll_cache.h',
       ],
+      'conditions': [
+        ['component=="shared_library"', {
+          # In component builds, all targets depend on chrome_redirects by
+          # default. Remove it here to avoid a circular dependency.
+          'dependencies!': [
+            '../chrome_elf/chrome_elf.gyp:chrome_redirects',
+          ],
+        }],
+      ],
     },
   ],
 }
diff --git a/chrome_elf/chrome_elf_constants.cc b/chrome_elf/chrome_elf_constants.cc
new file mode 100644
index 0000000..45229be
--- /dev/null
+++ b/chrome_elf/chrome_elf_constants.cc
@@ -0,0 +1,13 @@
+// Copyright 2014 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/chrome_elf_constants.h"
+
+const wchar_t kUserDataDirName[] = L"User Data";
+
+#if defined(GOOGLE_CHROME_BUILD)
+const wchar_t kAppDataDirName[] = L"Google\\Chrome";
+#else
+const wchar_t kAppDataDirName[] = L"Chromium";
+#endif
diff --git a/chrome_elf/chrome_elf_constants.h b/chrome_elf/chrome_elf_constants.h
new file mode 100644
index 0000000..7b10896
--- /dev/null
+++ b/chrome_elf/chrome_elf_constants.h
@@ -0,0 +1,14 @@
+// Copyright 2014 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.
+
+// A handful of resource-like constants related to the ChromeELF.
+
+#ifndef CHROME_ELF_CHROME_ELF_CONSTANTS_H_
+#define CHROME_ELF_CHROME_ELF_CONSTANTS_H_
+
+// directory names
+extern const wchar_t kAppDataDirName[];
+extern const wchar_t kUserDataDirName[];
+
+#endif  // CHROME_ELF_CHROME_ELF_CONSTANTS_H_
diff --git a/chrome_elf/chrome_redirects.def b/chrome_elf/chrome_redirects.def
new file mode 100644
index 0000000..30eb718
--- /dev/null
+++ b/chrome_elf/chrome_redirects.def
@@ -0,0 +1,8 @@
+; Copyright 2014 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.
+
+LIBRARY  "chrome_redirects.dll"
+
+EXPORTS
+  CreateFileW=CreateFileWRedirect
diff --git a/chrome_elf/create_file/chrome_create_file.cc b/chrome_elf/create_file/chrome_create_file.cc
new file mode 100644
index 0000000..529e014
--- /dev/null
+++ b/chrome_elf/create_file/chrome_create_file.cc
@@ -0,0 +1,237 @@
+// Copyright 2014 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/create_file/chrome_create_file.h"
+
+#include <string>
+
+#include "base/strings/string16.h"
+#include "chrome_elf/chrome_elf_constants.h"
+#include "chrome_elf/ntdll_cache.h"
+#include "sandbox/win/src/nt_internals.h"
+
+namespace {
+
+// From ShlObj.h in the Windows SDK.
+#define CSIDL_LOCAL_APPDATA 0x001c
+
+typedef BOOL (WINAPI *PathIsUNCFunction)(
+  IN LPCWSTR path);
+
+typedef BOOL (WINAPI *PathAppendFunction)(
+  IN LPWSTR path,
+  IN LPCWSTR more);
+
+typedef BOOL (WINAPI *PathIsPrefixFunction)(
+  IN LPCWSTR prefix,
+  IN LPCWSTR path);
+
+typedef HRESULT (WINAPI *SHGetFolderPathFunction)(
+  IN HWND hwnd_owner,
+  IN int folder,
+  IN HANDLE token,
+  IN DWORD flags,
+  OUT LPWSTR path);
+
+PathIsUNCFunction g_path_is_unc_func;
+PathAppendFunction g_path_append_func;
+PathIsPrefixFunction g_path_is_prefix_func;
+SHGetFolderPathFunction g_get_folder_func;
+
+// Populates the g_*_func pointers to functions which will be used in
+// ShouldBypass(). Chrome_elf cannot have a load-time dependency on shell32 or
+// shlwapi as this would induce a load-time dependency on user32.dll. Instead,
+// the addresses of the functions we need are retrieved the first time this
+// method is called, and cached to avoid subsequent calls to GetProcAddress().
+// It is assumed that the host process will never unload these functions.
+// Returns true if all the functions needed are present.
+bool PopulateShellFunctions() {
+  // Early exit if functions have already been populated.
+  if (g_path_is_unc_func && g_path_append_func &&
+      g_path_is_prefix_func && g_get_folder_func) {
+    return true;
+  }
+
+  // Get the addresses of the functions we need and store them for future use.
+  // These handles are intentionally leaked to ensure that these modules do not
+  // get unloaded.
+  HMODULE shell32 = ::LoadLibrary(L"shell32.dll");
+  HMODULE shlwapi = ::LoadLibrary(L"shlwapi.dll");
+
+  if (!shlwapi || !shell32)
+    return false;
+
+  g_path_is_unc_func = reinterpret_cast<PathIsUNCFunction>(
+      ::GetProcAddress(shlwapi, "PathIsUNCW"));
+  g_path_append_func = reinterpret_cast<PathAppendFunction>(
+      ::GetProcAddress(shlwapi, "PathAppendW"));
+  g_path_is_prefix_func = reinterpret_cast<PathIsPrefixFunction>(
+      ::GetProcAddress(shlwapi, "PathIsPrefixW"));
+  g_get_folder_func = reinterpret_cast<SHGetFolderPathFunction>(
+      ::GetProcAddress(shell32, "SHGetFolderPathW"));
+
+  return g_path_is_unc_func && g_path_append_func &&
+      g_path_is_prefix_func && g_get_folder_func;
+}
+
+}  // namespace
+
+HANDLE WINAPI CreateFileWRedirect(
+    LPCWSTR file_name,
+    DWORD desired_access,
+    DWORD share_mode,
+    LPSECURITY_ATTRIBUTES security_attributes,
+    DWORD creation_disposition,
+    DWORD flags_and_attributes,
+    HANDLE template_file) {
+  if (ShouldBypass(file_name)) {
+    return CreateFileNTDLL(file_name,
+                           desired_access,
+                           share_mode,
+                           security_attributes,
+                           creation_disposition,
+                           flags_and_attributes,
+                           template_file);
+  }
+  return CreateFile(file_name,
+                    desired_access,
+                    share_mode,
+                    security_attributes,
+                    creation_disposition,
+                    flags_and_attributes,
+                    template_file);
+
+}
+
+HANDLE CreateFileNTDLL(
+    LPCWSTR file_name,
+    DWORD desired_access,
+    DWORD share_mode,
+    LPSECURITY_ATTRIBUTES security_attributes,
+    DWORD creation_disposition,
+    DWORD flags_and_attributes,
+    HANDLE template_file) {
+  HANDLE file_handle = INVALID_HANDLE_VALUE;
+  NTSTATUS result = STATUS_UNSUCCESSFUL;
+  IO_STATUS_BLOCK io_status_block = {};
+
+  // Convert from Win32 domain to to NT creation disposition values.
+  switch (creation_disposition) {
+    case CREATE_NEW:
+      creation_disposition = FILE_CREATE;
+      break;
+    case CREATE_ALWAYS:
+      creation_disposition = FILE_OVERWRITE_IF;
+      break;
+    case OPEN_EXISTING:
+      creation_disposition = FILE_OPEN;
+      break;
+    case OPEN_ALWAYS:
+      creation_disposition = FILE_OPEN_IF;
+      break;
+    case TRUNCATE_EXISTING:
+      creation_disposition = FILE_OVERWRITE;
+      break;
+    default:
+      SetLastError(ERROR_INVALID_PARAMETER);
+      return INVALID_HANDLE_VALUE;
+  }
+
+  if (!g_ntdll_lookup["NtCreateFile"] ||
+      !g_ntdll_lookup["RtlInitUnicodeString"]) {
+    return INVALID_HANDLE_VALUE;
+  }
+
+  NtCreateFileFunction create_file =
+      reinterpret_cast<NtCreateFileFunction>(g_ntdll_lookup["NtCreateFile"]);
+
+  RtlInitUnicodeStringFunction init_unicode_string =
+      reinterpret_cast<RtlInitUnicodeStringFunction>(
+          g_ntdll_lookup["RtlInitUnicodeString"]);
+
+  UNICODE_STRING path_unicode_string;
+
+  // Format the path into an NT path. Arguably this should be done with
+  // RtlDosPathNameToNtPathName_U, but afaict this is equivalent for
+  // local paths. Using this with a UNC path name will almost certainly
+  // break in interesting ways.
+  base::string16 filename_string(L"\\??\\");
+  filename_string += file_name;
+
+  init_unicode_string(&path_unicode_string, filename_string.c_str());
+
+  OBJECT_ATTRIBUTES path_attributes = {};
+  InitializeObjectAttributes(&path_attributes,
+                             &path_unicode_string,
+                             OBJ_CASE_INSENSITIVE,
+                             NULL,   // No Root Directory
+                             NULL);  // No Security Descriptor
+
+  // Set create_options, desired_access, and flags_and_attributes to match those
+  // set by kernel32!CreateFile.
+  ULONG create_options = FILE_ATTRIBUTE_DEVICE | FILE_ATTRIBUTE_ARCHIVE;
+  desired_access |= 0x100080;
+  flags_and_attributes &= 0x2FFA7;
+
+  result = create_file(&file_handle,
+                       desired_access,
+                       &path_attributes,
+                       &io_status_block,
+                       0,  // Allocation size
+                       flags_and_attributes,
+                       share_mode,
+                       creation_disposition,
+                       create_options,
+                       NULL,
+                       0);
+
+  if (result != STATUS_SUCCESS) {
+    if (result == STATUS_OBJECT_NAME_COLLISION &&
+        creation_disposition == FILE_CREATE) {
+      SetLastError(ERROR_FILE_EXISTS);
+    }
+    return INVALID_HANDLE_VALUE;
+  }
+
+  if (creation_disposition == FILE_OPEN_IF) {
+    SetLastError(io_status_block.Information == FILE_OPENED ?
+        ERROR_ALREADY_EXISTS : ERROR_SUCCESS);
+  } else if (creation_disposition == FILE_OVERWRITE_IF) {
+    SetLastError(io_status_block.Information == FILE_OVERWRITTEN ?
+        ERROR_ALREADY_EXISTS : ERROR_SUCCESS);
+  } else {
+    SetLastError(ERROR_SUCCESS);
+  }
+
+  return file_handle;
+}
+
+bool ShouldBypass(LPCWSTR file_name) {
+  // If the shell functions are not present, forward the call to kernel32.
+  if (!PopulateShellFunctions())
+    return false;
+
+  // Forward all UNC filepaths to kernel32.
+  if (g_path_is_unc_func(file_name))
+    return false;
+
+  wchar_t local_appdata_path[MAX_PATH];
+
+  // Get the %LOCALAPPDATA% Path and append the location of our UserData
+  // directory to it.
+  HRESULT appdata_result = g_get_folder_func(
+      NULL, CSIDL_LOCAL_APPDATA, NULL, 0, local_appdata_path);
+
+  // If getting the %LOCALAPPDATA% path or appending to it failed, then forward
+  // the call to kernel32.
+  if (!SUCCEEDED(appdata_result) ||
+      !g_path_append_func(local_appdata_path, kAppDataDirName) ||
+      !g_path_append_func(local_appdata_path, kUserDataDirName)) {
+    return false;
+  }
+
+  // Check if we are trying to access something in the UserData dir. If so,
+  // then redirect the call to bypass kernel32.
+  return !!g_path_is_prefix_func(local_appdata_path, file_name);
+}
diff --git a/chrome_elf/create_file/chrome_create_file.h b/chrome_elf/create_file/chrome_create_file.h
new file mode 100644
index 0000000..dac93af
--- /dev/null
+++ b/chrome_elf/create_file/chrome_create_file.h
@@ -0,0 +1,38 @@
+// Copyright 2014 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.
+
+#ifndef CHROME_ELF_CREATE_FILE_CHROME_CREATE_FILE_H_
+#define CHROME_ELF_CREATE_FILE_CHROME_CREATE_FILE_H_
+
+#include <windows.h>
+
+#include "chrome_elf/chrome_elf_types.h"
+
+// A CreateFileW replacement that will call NTCreateFile directly when the
+// criteria defined in ShouldBypass() are satisfied for |lp_file_name|.
+extern "C" HANDLE WINAPI CreateFileWRedirect(
+    LPCWSTR file_name,
+    DWORD desired_access,
+    DWORD share_mode,
+    LPSECURITY_ATTRIBUTES security_attributes,
+    DWORD creation_disposition,
+    DWORD flags_and_attributes,
+    HANDLE template_file);
+
+// Partial reimplementation of kernel32!CreateFile (very partial: only handles
+// reading and writing to files in the User Data directory).
+HANDLE CreateFileNTDLL(
+    LPCWSTR file_name,
+    DWORD desired_access,
+    DWORD share_mode,
+    LPSECURITY_ATTRIBUTES security_attributes,
+    DWORD creation_disposition,
+    DWORD flags_and_attributes,
+    HANDLE template_file);
+
+// Determines whether or not we should use our version of CreateFile, or the
+// system version (only uses ours if we're writing to the user data directory).
+bool ShouldBypass(LPCWSTR file_name);
+
+#endif  // CHROME_ELF_CREATE_FILE_CHROME_CREATE_FILE_H_
diff --git a/chrome_elf/create_file/chrome_create_file_unittest.cc b/chrome_elf/create_file/chrome_create_file_unittest.cc
new file mode 100644
index 0000000..217d129
--- /dev/null
+++ b/chrome_elf/create_file/chrome_create_file_unittest.cc
@@ -0,0 +1,327 @@
+// Copyright 2014 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/create_file/chrome_create_file.h"
+
+#include <windows.h>
+
+#include <bitset>
+#include <string>
+
+#include "base/base_paths_win.h"
+#include "base/file_util.h"
+#include "base/files/file_path.h"
+#include "base/files/scoped_temp_dir.h"
+#include "base/path_service.h"
+#include "base/threading/platform_thread.h"
+#include "base/win/iat_patch_function.h"
+#include "base/win/scoped_handle.h"
+#include "base/win/windows_version.h"
+#include "chrome_elf/chrome_elf_constants.h"
+#include "chrome_elf/ntdll_cache.h"
+#include "sandbox/win/src/nt_internals.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+
+
+namespace {
+
+// Test fixtures -------------------------------------------------------------
+
+class ChromeCreateFileTest : public PlatformTest {
+ protected:
+  struct NtCreateFileParams {
+    ACCESS_MASK desired_access;
+    OBJECT_ATTRIBUTES object_attributes;
+    PLARGE_INTEGER allocation_size;
+    ULONG file_attributes;
+    ULONG share_access;
+    ULONG create_disposition;
+    ULONG create_options;
+    PVOID ea_buffer;
+    ULONG ea_length;
+  };
+
+  enum CallPath {
+    ELF,
+    KERNEL
+  };
+
+  template<CallPath path>
+  static NTSTATUS WINAPI FakeNtCreateFile(
+      PHANDLE file_handle,
+      ACCESS_MASK desired_access,
+      POBJECT_ATTRIBUTES object_attributes,
+      PIO_STATUS_BLOCK io_status_block,
+      PLARGE_INTEGER allocation_size,
+      ULONG file_attributes,
+      ULONG share_access,
+      ULONG create_disposition,
+      ULONG create_options,
+      PVOID ea_buffer,
+      ULONG ea_length) {
+    return self_->HandleCreateFileCall(file_handle,
+        desired_access,
+        object_attributes,
+        io_status_block,
+        allocation_size,
+        file_attributes,
+        share_access,
+        create_disposition,
+        create_options,
+        ea_buffer,
+        ea_length,
+        path);
+  }
+
+  virtual void SetUp() OVERRIDE {
+    original_thread_ = base::PlatformThread::CurrentId();
+    InitCache();
+    PlatformTest::SetUp();
+
+    base::FilePath user_data_dir;
+    PathService::Get(base::DIR_LOCAL_APP_DATA, &user_data_dir);
+    ASSERT_TRUE(temp_dir_.CreateUniqueTempDirUnderPath(user_data_dir));
+    ASSERT_TRUE(temp_dir2_.CreateUniqueTempDir());
+    self_ = this;
+  }
+
+  void RedirectNtCreateFileCalls() {
+    old_func_ptr_ =
+        reinterpret_cast<NtCreateFileFunction>(g_ntdll_lookup["NtCreateFile"]);
+
+    // KernelBase.dll only exists for Win7 and later, prior to that, kernel32
+    // imports from ntdll directly.
+    if (base::win::GetVersion() < base::win::VERSION_WIN7) {
+      patcher_.Patch(L"kernel32.dll", "ntdll.dll", "NtCreateFile",
+          reinterpret_cast<void(*)()>(&FakeNtCreateFile<KERNEL>));
+    } else {
+      patcher_.Patch(L"kernelbase.dll", "ntdll.dll", "NtCreateFile",
+          reinterpret_cast<void(*)()>(&FakeNtCreateFile<KERNEL>));
+    }
+
+    g_ntdll_lookup["NtCreateFile"] = reinterpret_cast<void(*)()>(
+        &ChromeCreateFileTest::FakeNtCreateFile<ELF>);
+  }
+
+  void ResetNtCreateFileCalls() {
+    g_ntdll_lookup["NtCreateFile"] = reinterpret_cast<void*>(old_func_ptr_);
+    patcher_.Unpatch();
+  }
+
+  NTSTATUS HandleCreateFileCall(PHANDLE file_handle,
+      ACCESS_MASK desired_access,
+      POBJECT_ATTRIBUTES object_attributes,
+      PIO_STATUS_BLOCK io_status_block,
+      PLARGE_INTEGER allocation_size,
+      ULONG file_attributes,
+      ULONG share_access,
+      ULONG create_disposition,
+      ULONG create_options,
+      PVOID ea_buffer,
+      ULONG ea_length,
+      CallPath call_path) {
+    if (original_thread_ == base::PlatformThread::CurrentId()) {
+      SetParams(desired_access,
+          object_attributes,
+          allocation_size,
+          file_attributes,
+          share_access,
+          create_disposition,
+          create_options,
+          ea_buffer,
+          ea_length,
+          call_path == ELF ? &elf_params_ : &kernel_params_);
+    }
+
+    // Forward the call to the real NTCreateFile.
+    return old_func_ptr_(file_handle,
+        desired_access,
+        object_attributes,
+        io_status_block,
+        allocation_size,
+        file_attributes,
+        share_access,
+        create_disposition,
+        create_options,
+        ea_buffer,
+        ea_length);
+  }
+
+  void SetParams(ACCESS_MASK desired_access,
+      POBJECT_ATTRIBUTES object_attributes,
+      PLARGE_INTEGER allocation_size,
+      ULONG file_attributes,
+      ULONG share_access,
+      ULONG create_disposition,
+      ULONG create_options,
+      PVOID ea_buffer,
+      ULONG ea_length,
+      NtCreateFileParams* params) {
+    params->desired_access = desired_access;
+    params->object_attributes.Length = object_attributes->Length;
+    params->object_attributes.ObjectName = object_attributes->ObjectName;
+    params->object_attributes.RootDirectory = object_attributes->RootDirectory;
+    params->object_attributes.Attributes = object_attributes->Attributes;
+    params->object_attributes.SecurityDescriptor =
+        object_attributes->SecurityDescriptor;
+    params->object_attributes.SecurityQualityOfService =
+        object_attributes->SecurityQualityOfService;
+    params->allocation_size = allocation_size;
+    params->file_attributes = file_attributes;
+    params->share_access = share_access;
+    params->create_disposition = create_disposition;
+    params->create_options = create_options;
+    params->ea_buffer = ea_buffer;
+    params->ea_length = ea_length;
+  }
+
+  void CheckParams() {
+    std::bitset<32> elf((int) elf_params_.desired_access);
+    std::bitset<32> ker((int) kernel_params_.desired_access);
+
+    EXPECT_EQ(kernel_params_.desired_access, elf_params_.desired_access)
+        << elf << "\n" << ker;
+    EXPECT_EQ(kernel_params_.object_attributes.Length,
+              elf_params_.object_attributes.Length);
+    EXPECT_EQ(kernel_params_.object_attributes.RootDirectory,
+              elf_params_.object_attributes.RootDirectory);
+    EXPECT_EQ(kernel_params_.object_attributes.Attributes,
+              elf_params_.object_attributes.Attributes);
+    EXPECT_EQ(kernel_params_.object_attributes.SecurityDescriptor,
+              elf_params_.object_attributes.SecurityDescriptor);
+    EXPECT_EQ(kernel_params_.allocation_size, elf_params_.allocation_size);
+    EXPECT_EQ(kernel_params_.file_attributes, elf_params_.file_attributes);
+    EXPECT_EQ(kernel_params_.share_access, elf_params_.share_access);
+    EXPECT_EQ(kernel_params_.create_disposition,
+              elf_params_.create_disposition);
+    EXPECT_EQ(kernel_params_.create_options, elf_params_.create_options);
+    EXPECT_EQ(kernel_params_.ea_buffer, elf_params_.ea_buffer);
+    EXPECT_EQ(kernel_params_.ea_length, elf_params_.ea_length);
+  }
+
+  void DoWriteCheck(const base::FilePath& path, bool is_system) {
+    base::win::ScopedHandle file_handle;
+    const char kTestData[] = "0123456789";
+    int buffer_size = sizeof(kTestData) - 1;
+    DWORD bytes_written;
+
+    if (is_system) {
+      file_handle.Set(::CreateFileW(path.value().c_str(),
+                                    GENERIC_WRITE,
+                                    0,
+                                    NULL,
+                                    CREATE_ALWAYS,
+                                    FILE_ATTRIBUTE_NORMAL,
+                                    NULL));
+    } else {
+      file_handle.Set(CreateFileNTDLL(path.value().c_str(),
+                                      GENERIC_WRITE,
+                                      0,
+                                      NULL,
+                                      CREATE_ALWAYS,
+                                      FILE_ATTRIBUTE_NORMAL,
+                                      NULL));
+    }
+
+
+    EXPECT_FALSE(file_handle == INVALID_HANDLE_VALUE);
+    ::WriteFile(file_handle, kTestData, buffer_size, &bytes_written, NULL);
+    EXPECT_EQ(buffer_size, bytes_written);
+  }
+
+  void DoReadCheck(const base::FilePath& path, bool is_system) {
+    base::win::ScopedHandle file_handle;
+    const char kTestData[] = "0123456789";
+    int buffer_size = sizeof(kTestData) - 1;
+    DWORD bytes_read;
+    char read_buffer[10];
+
+     if (is_system) {
+      file_handle.Set(::CreateFileW(path.value().c_str(),
+                                    GENERIC_READ,
+                                    0,
+                                    NULL,
+                                    OPEN_ALWAYS,
+                                    FILE_ATTRIBUTE_NORMAL,
+                                    NULL));
+    } else {
+      file_handle.Set(CreateFileNTDLL(path.value().c_str(),
+                                      GENERIC_READ,
+                                      0,
+                                      NULL,
+                                      OPEN_ALWAYS,
+                                      FILE_ATTRIBUTE_NORMAL,
+                                      NULL));
+    }
+
+    EXPECT_FALSE(file_handle == INVALID_HANDLE_VALUE);
+    ::ReadFile(file_handle, read_buffer, buffer_size, &bytes_read, NULL);
+    EXPECT_EQ(buffer_size, bytes_read);
+    EXPECT_EQ(0, memcmp(kTestData, read_buffer, bytes_read));
+  }
+
+  static ChromeCreateFileTest* self_;
+
+  NtCreateFileFunction old_func_ptr_;
+  base::ScopedTempDir temp_dir_;
+  base::ScopedTempDir temp_dir2_;
+  base::win::IATPatchFunction patcher_;
+  NtCreateFileParams kernel_params_;
+  NtCreateFileParams elf_params_;
+  base::PlatformThreadId original_thread_;
+};
+
+ChromeCreateFileTest* ChromeCreateFileTest::self_ = NULL;
+
+// Tests ---------------------------------------------------------------------
+
+TEST_F(ChromeCreateFileTest, CheckWriteAndReadParams) {
+  RedirectNtCreateFileCalls();
+
+  // Make sure we can write to this file handle when called via the system.
+  base::FilePath junk_path_1 = temp_dir_.path().Append(L"junk_1.txt");
+  base::FilePath junk_path_2 = temp_dir_.path().Append(L"junk_2.txt");
+  DoWriteCheck(junk_path_1, true);
+  DoWriteCheck(junk_path_2, false);
+  CheckParams();
+
+  // Make sure we can read from this file handle when called via the system.
+  DoReadCheck(junk_path_1, true);
+  DoReadCheck(junk_path_2, false);
+  CheckParams();
+
+  ResetNtCreateFileCalls();
+}
+
+TEST_F(ChromeCreateFileTest, BypassTest) {
+  std::wstring UNC_filepath_file(L"\\\\.\\some_file.txt");
+
+  base::FilePath local_path;
+  PathService::Get(base::DIR_LOCAL_APP_DATA, &local_path);
+  local_path = local_path.Append(kAppDataDirName).Append(
+      kUserDataDirName).Append(L"default\\Preferences");
+
+  base::FilePath desktop_path;
+  PathService::Get(base::DIR_USER_DESKTOP, &desktop_path);
+  desktop_path = desktop_path.Append(L"Downloads\\junk.txt");
+
+  EXPECT_FALSE(ShouldBypass(UNC_filepath_file.c_str()));
+  EXPECT_FALSE(ShouldBypass(desktop_path.value().c_str()));
+  EXPECT_TRUE(ShouldBypass(local_path.value().c_str()));
+}
+
+TEST_F(ChromeCreateFileTest, NtCreateFileAddressCheck) {
+  HMODULE ntdll_handle = ::GetModuleHandle(L"ntdll.dll");
+  EXPECT_EQ(::GetProcAddress(ntdll_handle, "NtCreateFile"),
+            g_ntdll_lookup["NtCreateFile"]);
+}
+
+TEST_F(ChromeCreateFileTest, ReadWriteFromNtDll) {
+  base::FilePath file_name = temp_dir_.path().Append(L"some_file.txt");
+  DoWriteCheck(file_name, false);
+  DoReadCheck(file_name, false);
+}
+
+}  // namespace