Generate and connect a Pepper identifier for Chrome OS

chrome/browser/chromeos/system/drm_settings.cc

+// Copyright (c) 2012 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/browser/chromeos/system/drm_settings.h"
+
+#include "base/bind.h"
+#include "base/chromeos/chromeos_version.h"
+#include "base/command_line.h"
+#include "base/file_path.h"
+#include "base/file_util.h"
+#include "base/path_service.h"
+#include "base/string_number_conversions.h"
+#include "base/string_util.h"
+#include "chrome/browser/chromeos/cros/cros_library.h"
+#include "chrome/browser/chromeos/cros/cryptohome_library.h"
+#include "chrome/browser/chromeos/login/user_manager.h"
+#include "chrome/common/chrome_paths.h"
+#include "chrome/common/chrome_switches.h"
+#include "content/public/browser/browser_thread.h"
+#include "crypto/encryptor.h"
+#include "crypto/sha2.h"
+
+using content::BrowserThread;
+
+namespace {
+
+// This constant is mirrored in
+//   content/browser/renderer_host/pepper_message_filter.cc
+// for OnGetDeviceID.
+//
+// This ID file is solely for use via the private pepper API.
+//
+// NOTE! Changing this value will also change the generated value
+//       do not do so without accounting for the change.
+const char kDRMIdentifierFile[] = "Pepper DRM ID.0";
+
+void ManageDrmIdentifierOnFileThread(bool enable, const std::string& email) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
+  // Drop the file under <data>/<profile>/<drm id file>.
+  // TODO(wad) get the profile directory in a more succinct fashion.
+  FilePath drm_id_file;
+  PathService::Get(chrome::DIR_USER_DATA, &drm_id_file);
+  const CommandLine& cmd_line = *CommandLine::ForCurrentProcess();
+  FilePath profile = cmd_line.GetSwitchValuePath(switches::kLoginProfile);
+  if (profile.empty()) {
+    LOG(ERROR) << "called with no login-profile!";
+    return;
+  }
+  drm_id_file = drm_id_file.AppendASCII(profile.value());
+  drm_id_file = drm_id_file.AppendASCII(kDRMIdentifierFile);
+
+  // The file will be regenerated or deleted at toggle-time.
+  file_util::Delete(drm_id_file, false);
+
+  // If DRM support is disabled, then do nothing else.
+  if (!enable)
+    return;
+
+  // Build the identifier as follows:
+  // SHA256(system-salt||service||SHA256(system-salt||service||email))
+  chromeos::CryptohomeLibrary* c_home =
+    chromeos::CrosLibrary::Get()->GetCryptohomeLibrary();
+  std::string salt = c_home->GetSystemSalt();
+  char id_buf[256 / 8];  // 256-bits for SHA256
+  std::string input = salt;
+  input.append(kDRMIdentifierFile);
+  input.append(email);
+  crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
+  std::string id = StringToLowerASCII(base::HexEncode(
+        reinterpret_cast<const void*>(id_buf),
+        sizeof(id_buf)));
+  input = salt;
+  input.append(kDRMIdentifierFile);
+  input.append(id);
+  crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
+  id = StringToLowerASCII(base::HexEncode(
+        reinterpret_cast<const void*>(id_buf),
+        sizeof(id_buf)));
+
+  if (file_util::WriteFile(drm_id_file, id.c_str(), id.length()) !=
+      static_cast<int>(id.length())) {
+    LOG(ERROR) << "Failed to write " << drm_id_file.value();
+    return;
+  }
+}
+
+}  // namespace
+
+namespace chromeos {
+namespace system {
+
+void ToggleDrm(bool enable) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // Never generate the file in Guest mode.
+  if (UserManager::Get()->IsLoggedInAsGuest() ||
+      UserManager::Get()->IsLoggedInAsDemoUser())
+    return;
+
+  // The user email address is included in the hash to keep the identifier
+  // from being the same across users.
+  std::string email = UserManager::Get()->GetLoggedInUser().email();
+  DCHECK(email.length() == 0);
+
+  // Generate a DRM identifier on the FILE thread.
+  // The DRM identifier is a per-user, per-OS-install identifier that is used
+  // by privileged pepper plugins specifically for deriving
+  // per-content-provider identifiers.  The user must be able to clear it,
+  // reset it, and deny its use.
+  BrowserThread::PostTask(
+      BrowserThread::FILE, FROM_HERE,
+      base::Bind(&ManageDrmIdentifierOnFileThread, enable, email));
+}
+
+}  // namespace system
+}  // namespace chromeos