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/files/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/pref_registry/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), render_process_id_(render_process_id) {
  59   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  60 }
  61
  62 DeviceIDFetcher::~DeviceIDFetcher() {}
  63
  64 bool DeviceIDFetcher::Start(const IDCallback& callback) {
  65   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  66
  67   if (in_progress_)
  68     return false;
  69
  70   in_progress_ = true;
  71   callback_ = callback;
  72
  73   BrowserThread::PostTask(
  74       BrowserThread::UI,
  75       FROM_HERE,
  76       base::Bind(&DeviceIDFetcher::CheckPrefsOnUIThread, this));
  77   return true;
  78 }
  79
  80 // static
  81 void DeviceIDFetcher::RegisterProfilePrefs(
  82     user_prefs::PrefRegistrySyncable* prefs) {
  83   prefs->RegisterBooleanPref(prefs::kEnableDRM,
  84                              true,
  85                              user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
  86   prefs->RegisterStringPref(
  87       prefs::kDRMSalt, "", user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
  88 }
  89
  90 // static
  91 base::FilePath DeviceIDFetcher::GetLegacyDeviceIDPath(
  92     const base::FilePath& profile_path) {
  93   return profile_path.AppendASCII(kDRMIdentifierFile);
  94 }
  95
  96 void DeviceIDFetcher::CheckPrefsOnUIThread() {
  97   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  98
  99   Profile* profile = NULL;
 100   RenderProcessHost* render_process_host =
 101       RenderProcessHost::FromID(render_process_id_);
 102   if (render_process_host && render_process_host->GetBrowserContext()) {
 103     profile =
 104         Profile::FromBrowserContext(render_process_host->GetBrowserContext());
 105   }
 106
 107   if (!profile || profile->IsOffTheRecord() ||
 108       !profile->GetPrefs()->GetBoolean(prefs::kEnableDRM)) {
 109     RunCallbackOnIOThread(std::string(), PP_ERROR_NOACCESS);
 110     return;
 111   }
 112
 113   // Check if the salt pref is set. If it isn't, set it.
 114   std::string salt = profile->GetPrefs()->GetString(prefs::kDRMSalt);
 115   if (salt.empty()) {
 116     uint8_t salt_bytes[kSaltLength];
 117     crypto::RandBytes(salt_bytes, arraysize(salt_bytes));
 118     // Since it will be stored in a string pref, convert it to hex.
 119     salt = base::HexEncode(salt_bytes, arraysize(salt_bytes));
 120     profile->GetPrefs()->SetString(prefs::kDRMSalt, salt);
 121   }
 122
 123 #if defined(OS_CHROMEOS)
 124   // Try the legacy path first for ChromeOS. We pass the new salt in as well
 125   // in case the legacy id doesn't exist.
 126   BrowserThread::PostBlockingPoolTask(
 127       FROM_HERE,
 128       base::Bind(&DeviceIDFetcher::LegacyComputeOnBlockingPool,
 129                  this,
 130                  profile->GetPath(),
 131                  salt));
 132 #else
 133   // Get the machine ID and call ComputeOnUIThread with salt + machine_id.
 134   GetMachineIDAsync(
 135       base::Bind(&DeviceIDFetcher::ComputeOnUIThread, this, salt));
 136 #endif
 137 }
 138
 139 void DeviceIDFetcher::ComputeOnUIThread(const std::string& salt,
 140                                         const std::string& machine_id) {
 141   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 142
 143   if (machine_id.empty()) {
 144     LOG(ERROR) << "Empty machine id";
 145     RunCallbackOnIOThread(std::string(), PP_ERROR_FAILED);
 146     return;
 147   }
 148
 149   // Build the identifier as follows:
 150   // SHA256(machine-id||service||SHA256(machine-id||service||salt))
 151   std::vector<uint8> salt_bytes;
 152   if (!base::HexStringToBytes(salt, &salt_bytes))
 153     salt_bytes.clear();
 154   if (salt_bytes.size() != kSaltLength) {
 155     LOG(ERROR) << "Unexpected salt bytes length: " << salt_bytes.size();
 156     RunCallbackOnIOThread(std::string(), PP_ERROR_FAILED);
 157     return;
 158   }
 159
 160   char id_buf[256 / 8];  // 256-bits for SHA256
 161   std::string input = machine_id;
 162   input.append(kDRMIdentifierFile);
 163   input.append(salt_bytes.begin(), salt_bytes.end());
 164   crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
 165   std::string id = base::StringToLowerASCII(
 166       base::HexEncode(reinterpret_cast<const void*>(id_buf), sizeof(id_buf)));
 167   input = machine_id;
 168   input.append(kDRMIdentifierFile);
 169   input.append(id);
 170   crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
 171   id = base::StringToLowerASCII(
 172       base::HexEncode(reinterpret_cast<const void*>(id_buf), sizeof(id_buf)));
 173
 174   RunCallbackOnIOThread(id, PP_OK);
 175 }
 176
 177 // TODO(raymes): This is temporary code to migrate ChromeOS devices to the new
 178 // scheme for generating device IDs. Delete this once we are sure most ChromeOS
 179 // devices have been migrated.
 180 void DeviceIDFetcher::LegacyComputeOnBlockingPool(
 181     const base::FilePath& profile_path,
 182     const std::string& salt) {
 183   std::string id;
 184   // First check if the legacy device ID file exists on ChromeOS. If it does, we
 185   // should just return that.
 186   base::FilePath id_path = GetLegacyDeviceIDPath(profile_path);
 187   if (base::PathExists(id_path)) {
 188     if (base::ReadFileToString(id_path, &id) && !id.empty()) {
 189       RunCallbackOnIOThread(id, PP_OK);
 190       return;
 191     }
 192   }
 193   // If we didn't find an ID, get the machine ID and call the new code path to
 194   // generate an ID.
 195   BrowserThread::PostTask(
 196       BrowserThread::UI,
 197       FROM_HERE,
 198       base::Bind(&GetMachineIDAsync,
 199                  base::Bind(&DeviceIDFetcher::ComputeOnUIThread, this, salt)));
 200 }
 201
 202 void DeviceIDFetcher::RunCallbackOnIOThread(const std::string& id,
 203                                             int32_t result) {
 204   if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
 205     BrowserThread::PostTask(
 206         BrowserThread::IO,
 207         FROM_HERE,
 208         base::Bind(&DeviceIDFetcher::RunCallbackOnIOThread, this, id, result));
 209     return;
 210   }
 211   in_progress_ = false;
 212   callback_.Run(id, result);
 213 }
 214
 215 }  // namespace chrome