src/chrome/browser/renderer_host/pepper/device_id_fetcher.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/renderer_host/pepper/device_id_fetcher.h"
   6
   7 #include "base/file_util.h"
   8 #include "base/prefs/pref_service.h"
   9 #include "base/strings/string_number_conversions.h"
  10 #include "chrome/browser/profiles/profile.h"
  11 #include "chrome/common/pref_names.h"
  12 #if defined(OS_CHROMEOS)
  13 #include "chromeos/cryptohome/system_salt_getter.h"
  14 #endif
  15 #include "components/user_prefs/pref_registry_syncable.h"
  16 #include "content/public/browser/browser_context.h"
  17 #include "content/public/browser/browser_ppapi_host.h"
  18 #include "content/public/browser/browser_thread.h"
  19 #include "content/public/browser/render_process_host.h"
  20 #include "crypto/encryptor.h"
  21 #include "crypto/random.h"
  22 #include "crypto/sha2.h"
  23 #include "ppapi/c/pp_errors.h"
  24 #if defined(ENABLE_RLZ)
  25 #include "rlz/lib/machine_id.h"
  26 #endif
  27
  28 using content::BrowserPpapiHost;
  29 using content::BrowserThread;
  30 using content::RenderProcessHost;
  31
  32 namespace chrome {
  33
  34 namespace {
  35
  36 const char kDRMIdentifierFile[] = "Pepper DRM ID.0";
  37
  38 const uint32_t kSaltLength = 32;
  39
  40 void GetMachineIDAsync(
  41     const base::Callback<void(const std::string&)>& callback) {
  42 #if defined(OS_WIN) && defined(ENABLE_RLZ)
  43   std::string result;
  44   rlz_lib::GetMachineId(&result);
  45   callback.Run(result);
  46 #elif defined(OS_CHROMEOS)
  47   chromeos::SystemSaltGetter::Get()->GetSystemSalt(callback);
  48 #else
  49   // Not implemented for other platforms.
  50   NOTREACHED();
  51   callback.Run(std::string());
  52 #endif
  53 }
  54
  55 }  // namespace
  56
  57 DeviceIDFetcher::DeviceIDFetcher(int render_process_id)
  58     : in_progress_(false),
  59       render_process_id_(render_process_id) {
  60   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  61 }
  62
  63 DeviceIDFetcher::~DeviceIDFetcher() {
  64 }
  65
  66 bool DeviceIDFetcher::Start(const IDCallback& callback) {
  67   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  68
  69   if (in_progress_)
  70     return false;
  71
  72   in_progress_ = true;
  73   callback_ = callback;
  74
  75   BrowserThread::PostTask(
  76       BrowserThread::UI, FROM_HERE,
  77       base::Bind(&DeviceIDFetcher::CheckPrefsOnUIThread, this));
  78   return true;
  79 }
  80
  81 // static
  82 void DeviceIDFetcher::RegisterProfilePrefs(
  83     user_prefs::PrefRegistrySyncable* prefs) {
  84   prefs->RegisterBooleanPref(prefs::kEnableDRM,
  85                              true,
  86                              user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
  87   prefs->RegisterStringPref(
  88       prefs::kDRMSalt,
  89       "",
  90       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
  91 }
  92
  93 // static
  94 base::FilePath DeviceIDFetcher::GetLegacyDeviceIDPath(
  95     const base::FilePath& profile_path) {
  96   return profile_path.AppendASCII(kDRMIdentifierFile);
  97 }
  98
  99 void DeviceIDFetcher::CheckPrefsOnUIThread() {
 100   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 101
 102   Profile* profile = NULL;
 103   RenderProcessHost* render_process_host =
 104       RenderProcessHost::FromID(render_process_id_);
 105   if (render_process_host && render_process_host->GetBrowserContext()) {
 106     profile = Profile::FromBrowserContext(
 107         render_process_host->GetBrowserContext());
 108   }
 109
 110   if (!profile ||
 111       profile->IsOffTheRecord() ||
 112       !profile->GetPrefs()->GetBoolean(prefs::kEnableDRM)) {
 113     RunCallbackOnIOThread(std::string(), PP_ERROR_NOACCESS);
 114     return;
 115   }
 116
 117   // Check if the salt pref is set. If it isn't, set it.
 118   std::string salt = profile->GetPrefs()->GetString(prefs::kDRMSalt);
 119   if (salt.empty()) {
 120     uint8_t salt_bytes[kSaltLength];
 121     crypto::RandBytes(salt_bytes, arraysize(salt_bytes));
 122     // Since it will be stored in a string pref, convert it to hex.
 123     salt = base::HexEncode(salt_bytes, arraysize(salt_bytes));
 124     profile->GetPrefs()->SetString(prefs::kDRMSalt, salt);
 125   }
 126
 127 #if defined(OS_CHROMEOS)
 128   // Try the legacy path first for ChromeOS. We pass the new salt in as well
 129   // in case the legacy id doesn't exist.
 130   BrowserThread::PostBlockingPoolTask(
 131       FROM_HERE,
 132       base::Bind(&DeviceIDFetcher::LegacyComputeOnBlockingPool,
 133                  this,
 134                  profile->GetPath(), salt));
 135 #else
 136   // Get the machine ID and call ComputeOnUIThread with salt + machine_id.
 137   GetMachineIDAsync(base::Bind(&DeviceIDFetcher::ComputeOnUIThread,
 138                                this, salt));
 139 #endif
 140 }
 141
 142 void DeviceIDFetcher::ComputeOnUIThread(const std::string& salt,
 143                                         const std::string& machine_id) {
 144   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 145
 146   if (machine_id.empty()) {
 147     LOG(ERROR) << "Empty machine id";
 148     RunCallbackOnIOThread(std::string(), PP_ERROR_FAILED);
 149     return;
 150   }
 151
 152   // Build the identifier as follows:
 153   // SHA256(machine-id||service||SHA256(machine-id||service||salt))
 154   std::vector<uint8> salt_bytes;
 155   if (!base::HexStringToBytes(salt, &salt_bytes))
 156     salt_bytes.clear();
 157   if (salt_bytes.size() != kSaltLength) {
 158     LOG(ERROR) << "Unexpected salt bytes length: " << salt_bytes.size();
 159     RunCallbackOnIOThread(std::string(), PP_ERROR_FAILED);
 160     return;
 161   }
 162
 163   char id_buf[256 / 8];  // 256-bits for SHA256
 164   std::string input = machine_id;
 165   input.append(kDRMIdentifierFile);
 166   input.append(salt_bytes.begin(), salt_bytes.end());
 167   crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
 168   std::string id = StringToLowerASCII(
 169       base::HexEncode(reinterpret_cast<const void*>(id_buf), sizeof(id_buf)));
 170   input = machine_id;
 171   input.append(kDRMIdentifierFile);
 172   input.append(id);
 173   crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
 174   id = StringToLowerASCII(base::HexEncode(
 175         reinterpret_cast<const void*>(id_buf),
 176         sizeof(id_buf)));
 177
 178   RunCallbackOnIOThread(id, PP_OK);
 179 }
 180
 181 // TODO(raymes): This is temporary code to migrate ChromeOS devices to the new
 182 // scheme for generating device IDs. Delete this once we are sure most ChromeOS
 183 // devices have been migrated.
 184 void DeviceIDFetcher::LegacyComputeOnBlockingPool(
 185     const base::FilePath& profile_path,
 186     const std::string& salt) {
 187   std::string id;
 188   // First check if the legacy device ID file exists on ChromeOS. If it does, we
 189   // should just return that.
 190   base::FilePath id_path = GetLegacyDeviceIDPath(profile_path);
 191   if (base::PathExists(id_path)) {
 192     if (base::ReadFileToString(id_path, &id) && !id.empty()) {
 193       RunCallbackOnIOThread(id, PP_OK);
 194       return;
 195     }
 196   }
 197   // If we didn't find an ID, get the machine ID and call the new code path to
 198   // generate an ID.
 199   BrowserThread::PostTask(
 200       BrowserThread::UI, FROM_HERE,
 201       base::Bind(&GetMachineIDAsync,
 202                  base::Bind(&DeviceIDFetcher::ComputeOnUIThread,
 203                             this, salt)));
 204 }
 205
 206 void DeviceIDFetcher::RunCallbackOnIOThread(const std::string& id,
 207                                             int32_t result) {
 208   if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
 209     BrowserThread::PostTask(
 210         BrowserThread::IO, FROM_HERE,
 211         base::Bind(&DeviceIDFetcher::RunCallbackOnIOThread, this, id, result));
 212     return;
 213   }
 214   in_progress_ = false;
 215   callback_.Run(id, result);
 216 }
 217
 218 }  // namespace chrome