media: Verify CDM Host files

chrome/common/media/cdm_host_file_path.cc

+// Copyright 2017 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/common/media/cdm_host_file_path.h"
+
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/path_service.h"
+#include "build/build_config.h"
+#include "chrome/common/chrome_version.h"
+
+#if defined(OS_MACOSX)
+#include "base/mac/bundle_locations.h"
+#include "chrome/common/chrome_constants.h"
+#endif
+
+namespace {
+
+using content::CdmHostFilePath;
+
+// TODO(xhwang): Move this to a common place if needed.
+const base::FilePath::CharType kSignatureFileExtension[] =
+    FILE_PATH_LITERAL(".sig");
+
+// Returns the signature file path given the |file_path|. This function should
+// only be used when the signature file and the file are located in the same
+// directory.
+base::FilePath GetSigFilePath(const base::FilePath& file_path) {
+  return file_path.AddExtension(kSignatureFileExtension);
+}
+
+#if defined(OS_WIN)
+
+void AddCdmHostFilePathsWin(std::vector<CdmHostFilePath>* cdm_host_file_paths) {
+  static const base::FilePath::CharType* const kUnversionedFiles[] = {
+      FILE_PATH_LITERAL("chrome.exe")};

[tinskip1, 2017/01/19 03:42:47]

Can we get the actual name of the executable to deal with renaming?

[xhwang, 2017/01/19 08:30:51]

It's possible. I thought about using PathService::Get(FILE_EXE, exe_path) to get
the executable path but didn't do it for the following reasons:

- The current code is consistent with existing binary integrity analyzer code at
https://cs.chromium.org/chromium/src/chrome/browser/safe_browsing/incident_re...

- I still need to hard code chrome.dll and chrome_child.dll.

- PathService::Get(FILE_EXE, exe_path) could return "<path>/browser_tests" when
running browser tests, which gets a bit confusing.

[tinskip1, 2017/01/19 17:36:38]

I'm just concerned about getting a bunch of VMP validation failures because
users might rename chrome.exe. We can leave for now and see how things go.

[xhwang, 2017/01/19 17:57:11]

In that case do you expect the user also rename the sig file? I don't feel this
is the use case we want to support.

+  static const base::FilePath::CharType* const kVersionedFiles[] = {
+      FILE_PATH_LITERAL("chrome.dll"), FILE_PATH_LITERAL("chrome_child.dll")};
+
+  // Find where chrome.exe is installed.
+  base::FilePath chrome_exe_dir;
+  if (!PathService::Get(base::DIR_EXE, &chrome_exe_dir))
+    NOTREACHED();
+
+  cdm_host_file_paths->reserve(arraysize(kUnversionedFiles) +
+                               arraysize(kVersionedFiles));
+
+  for (size_t i = 0; i < arraysize(kUnversionedFiles); ++i) {
+    base::FilePath file_path = chrome_exe_dir.Append(kUnversionedFiles[i]);
+    DVLOG(2) << __func__ << ": unversioned file " << i << " at "
+             << file_path.value();
+    cdm_host_file_paths->push_back(
+        CdmHostFilePath(file_path, GetSigFilePath(file_path)));
+  }
+
+  base::FilePath version_dir(chrome_exe_dir.AppendASCII(CHROME_VERSION_STRING));
+  for (size_t i = 0; i < arraysize(kVersionedFiles); ++i) {
+    base::FilePath file_path = version_dir.Append(kVersionedFiles[i]);
+    DVLOG(2) << __func__ << ": versioned file " << i << " at "
+             << file_path.value();
+    cdm_host_file_paths->push_back(
+        CdmHostFilePath(file_path, GetSigFilePath(file_path)));
+  }
+}
+
+#elif defined(OS_MACOSX)
+
+void AddCdmHostFilePathsMac(std::vector<CdmHostFilePath>* cdm_host_file_paths) {
+  base::FilePath chrome_framework_path =
+      base::mac::FrameworkBundlePath().Append(chrome::kFrameworkExecutableName);
+
+  DVLOG(2) << __func__
+           << ": chrome_framework_path=" << chrome_framework_path.value();
+  cdm_host_file_paths->push_back(CdmHostFilePath(
+      chrome_framework_path, GetSigFilePath(chrome_framework_path)));
+}
+
+#elif defined(OS_LINUX)
+
+void AddCdmHostFilePathsLinux(
+    std::vector<CdmHostFilePath>* cdm_host_file_paths) {
+  base::FilePath chrome_exe_dir;
+  if (!PathService::Get(base::DIR_EXE, &chrome_exe_dir))
+    NOTREACHED();
+
+  base::FilePath chrome_path =
+      chrome_exe_dir.Append(FILE_PATH_LITERAL("chrome"));
+  DVLOG(2) << __func__ << ": chrome_path=" << chrome_path.value();
+  cdm_host_file_paths->push_back(
+      CdmHostFilePath(chrome_path, GetSigFilePath(chrome_path)));
+}
+
+#endif  // defined(OS_WIN)
+
+}  // namespace
+
+void AddCdmHostFilePaths(
+    std::vector<content::CdmHostFilePath>* cdm_host_file_paths) {
+  DVLOG(1) << __func__;
+  DCHECK(cdm_host_file_paths);
+  DCHECK(cdm_host_file_paths->empty());
+
+#if defined(OS_WIN)
+  AddCdmHostFilePathsWin(cdm_host_file_paths);
+#elif defined(OS_MACOSX)
+  AddCdmHostFilePathsMac(cdm_host_file_paths);
+#elif defined(OS_LINUX)
+  AddCdmHostFilePathsLinux(cdm_host_file_paths);
+#endif  // defined(OS_WIN)
+}