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