Change PolicyLoaderWin to load PReg files if possible.

chrome/browser/policy/policy_loader_win.cc

Index: chrome/browser/policy/policy_loader_win.cc
diff --git a/chrome/browser/policy/policy_loader_win.cc b/chrome/browser/policy/policy_loader_win.cc
index b527308a3b73dde7d3dda7a4d002808b615fa361..9af680970afec4fa99ea02f551dcb715ecb06395 100644
--- a/chrome/browser/policy/policy_loader_win.cc
+++ b/chrome/browser/policy/policy_loader_win.cc
@@ -5,25 +5,34 @@
 #include "chrome/browser/policy/policy_loader_win.h"
 
 #include <string>
+#include <vector>
 
-#include <string.h>
+#include <rpc.h>  // For struct GUID
+#include <shlwapi.h>  // For PathIsUNC()

[Joao da Silva, 2013/04/10 12:32:12]

Suggestion: I find vertically aligned comments easier to parse visually in cases
like this, up to you

[Mattias Nissler (ping if slow), 2013/04/10 13:20:25]

With my nitpick hat on, I'd agree :) But being honest, I can read the
non-aligned style just as well.

I don't care really, so going with your preference.

+#include <windows.h>
 
-#include <userenv.h>
-
-// userenv.dll is required for RegisterGPNotification().
+// shlwapi.dll is required for PathIsUNC().
+#pragma comment(lib, "shlwapi.lib")
+// userenv.dll is required for various GPO functions.
 #pragma comment(lib, "userenv.lib")
 
 #include "base/basictypes.h"
+#include "base/file_util.h"
+#include "base/files/file_path.h"
 #include "base/json/json_reader.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
-#include "base/memory/scoped_ptr.h"
+#include "base/scoped_native_library.h"
+#include "base/stl_util.h"
 #include "base/string16.h"
+#include "base/string_util.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/sys_byteorder.h"
 #include "base/utf_string_conversions.h"
-#include "base/values.h"
 #include "base/win/registry.h"
 #include "chrome/browser/policy/policy_bundle.h"
 #include "chrome/browser/policy/policy_map.h"
+#include "chrome/browser/policy/preg_parser_win.h"
 #include "chrome/common/json_schema/json_schema_constants.h"
 #include "policy/policy_constants.h"
 
@@ -32,70 +41,183 @@ namespace schema = json_schema_constants;
 using base::win::RegKey;
 using base::win::RegistryKeyIterator;
 using base::win::RegistryValueIterator;
-using namespace policy::registry_constants;
 
 namespace policy {
 
-namespace registry_constants {
-  const wchar_t kPathSep[] = L"\\";
-  const wchar_t kThirdParty[] = L"3rdparty";
-  const wchar_t kMandatory[] = L"policy";
-  const wchar_t kRecommended[] = L"recommended";
-  const wchar_t kSchema[] = L"schema";
-}  // namespace registry_constants
-
 namespace {
 
-// Map of registry hives to their corresponding policy scope, in decreasing
-// order of priority.
-const struct {
-  HKEY hive;
-  PolicyScope scope;
-} kHives[] = {
-  { HKEY_LOCAL_MACHINE,   POLICY_SCOPE_MACHINE  },
-  { HKEY_CURRENT_USER,    POLICY_SCOPE_USER     },
+const char kKeyMandatory[] = "policy";
+const char kKeyRecommended[] = "recommended";
+const char kKeySchema[] = "schema";
+const char kKeyThirdParty[] = "3rdparty";
+
+// The GUID of the registry settings group policy extension.
+GUID kRegistrySettingsCSEGUID = REGISTRY_EXTENSION_GUID;
+
+// The PReg file name.
+const base::FilePath::CharType kPRegFileName[] =
+    FILE_PATH_LITERAL("Registry.pol");
+
+// A helper class encapsulating run-time-linked function calls to Wow64 APIs.
+class Wow64Functions {
+ public:
+  Wow64Functions()
+    : kernel32_lib_(base::FilePath(L"kernel32")),
+      is_wow_64_process_(NULL),
+      wow_64_disable_wow_64_fs_redirection_(NULL),
+      wow_64_revert_wow_64_fs_redirection_(NULL) {
+    if (kernel32_lib_.is_valid()) {
+      is_wow_64_process_ = static_cast<IsWow64Process>(
+          kernel32_lib_.GetFunctionPointer("IsWow64Process"));
+      wow_64_disable_wow_64_fs_redirection_ =
+          static_cast<Wow64DisableWow64FSRedirection>(
+              kernel32_lib_.GetFunctionPointer(
+                  "Wow64DisableWow64FsRedirection"));
+      wow_64_revert_wow_64_fs_redirection_ =
+          static_cast<Wow64RevertWow64FSRedirection>(
+              kernel32_lib_.GetFunctionPointer(
+                  "Wow64RevertWow64FsRedirection"));
+    }
+  }
+
+  bool is_valid() {
+    return is_wow_64_process_ &&
+        wow_64_disable_wow_64_fs_redirection_ &&
+        wow_64_revert_wow_64_fs_redirection_;
+ }
+
+  bool IsWow64() {
+    BOOL result = 0;
+    if (!is_wow_64_process_(GetCurrentProcess(), &result))
+      PLOG(WARNING) << "IsWow64ProcFailed";
+    return !!result;
+  }
+
+  bool DisableFsRedirection(PVOID* previous_state) {
+    return !!wow_64_disable_wow_64_fs_redirection_(previous_state);
+  }
+
+  bool RevertFsRedirection(PVOID previous_state) {
+    return !!wow_64_revert_wow_64_fs_redirection_(previous_state);
+  }
+
+ private:
+  base::ScopedNativeLibrary kernel32_lib_;

[Joao da Silva, 2013/04/10 12:32:12]

nit: fields after types

[Mattias Nissler (ping if slow), 2013/04/10 13:20:25]

Done.

+
+  typedef BOOL (WINAPI* IsWow64Process)(HANDLE, PBOOL);
+  typedef BOOL (WINAPI* Wow64DisableWow64FSRedirection)(PVOID*);
+  typedef BOOL (WINAPI* Wow64RevertWow64FSRedirection)(PVOID);
+
+  IsWow64Process is_wow_64_process_;
+  Wow64DisableWow64FSRedirection wow_64_disable_wow_64_fs_redirection_;
+  Wow64RevertWow64FSRedirection wow_64_revert_wow_64_fs_redirection_;
+
+  DISALLOW_COPY_AND_ASSIGN(Wow64Functions);
 };
 
-// Reads a REG_SZ string at |key| named |name| into |result|. Returns false if
-// the string could not be read.
-bool ReadRegistryString(RegKey* key,
-                        const string16& name,
-                        string16* result) {
-  DWORD value_size = 0;
-  DWORD key_type = 0;
-  scoped_array<uint8> buffer;
+// Global Wow64Function instance used by ScopedDisableWow64Redirection below.
+static base::LazyInstance<Wow64Functions> g_wow_64_functions =
+    LAZY_INSTANCE_INITIALIZER;
+
+// Scoper that switches off Wow64 File System Redirection during its lifetime.
+class ScopedDisableWow64Redirection {
+ public:
+  ScopedDisableWow64Redirection()
+    : active_(false),
+      previous_state_(NULL) {
+    Wow64Functions* wow64 = g_wow_64_functions.Pointer();
+    if (wow64->is_valid() && wow64->IsWow64()) {
+      if (wow64->DisableFsRedirection(&previous_state_))
+        active_ = true;
+      else
+        PLOG(WARNING) << "Wow64DisableWow64FSRedirection";
+    }
+  }
 
-  if (key->ReadValue(name.c_str(), 0, &value_size, &key_type) != ERROR_SUCCESS)
-    return false;
-  if (key_type != REG_SZ)
-    return false;
+  ~ScopedDisableWow64Redirection() {
+    if (active_)
+      CHECK(g_wow_64_functions.Get().RevertFsRedirection(previous_state_));
+  }
 
-  // According to the Microsoft documentation, the string
-  // buffer may not be explicitly 0-terminated. Allocate a
-  // slightly larger buffer and pre-fill to zeros to guarantee
-  // the 0-termination.
-  buffer.reset(new uint8[value_size + 2]);
-  memset(buffer.get(), 0, value_size + 2);
-  key->ReadValue(name.c_str(), buffer.get(), &value_size, NULL);
-  result->assign(reinterpret_cast<const wchar_t*>(buffer.get()));
-  return true;
+  bool is_active() { return active_; }
+
+ private:
+  bool active_;
+  PVOID previous_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedDisableWow64Redirection);
+};
+
+// AppliedGPOListProvider implementation that calls actual Windows APIs.
+class WinGPOListProvider : public AppliedGPOListProvider {
+ public:
+  virtual ~WinGPOListProvider() {}
+
+  // AppliedGPOListProvider:
+  virtual DWORD GetAppliedGPOList(DWORD flags,
+                                  LPCTSTR machine_name,
+                                  PSID sid_user,
+                                  GUID* extension_guid,
+                                  PGROUP_POLICY_OBJECT* gpo_list) OVERRIDE{

[Joao da Silva, 2013/04/10 12:32:12]

nit: space between OVERRIDE and {

[Mattias Nissler (ping if slow), 2013/04/10 13:20:25]

Done.

+    return ::GetAppliedGPOList(flags, machine_name, sid_user, extension_guid,
+                               gpo_list);
+  }
+
+  virtual BOOL FreeGPOList(PGROUP_POLICY_OBJECT gpo_list) OVERRIDE {
+    return ::FreeGPOList(gpo_list);
+  }
+};
+
+// The default windows GPO list provider used for PolicyLoaderWin.
+static base::LazyInstance<WinGPOListProvider> g_win_gpo_list_provider =
+    LAZY_INSTANCE_INITIALIZER;
+
+// Returns the entry with key |name| in |dictionary| (can be NULL), or NULL.
+const base::DictionaryValue* GetEntry(const base::DictionaryValue* dictionary,
+                                      const std::string& name) {
+  if (!dictionary)
+    return NULL;
+  const base::DictionaryValue* entry = NULL;
+  dictionary->GetDictionaryWithoutPathExpansion(name, &entry);
+  return entry;
 }
 
-// Reads a REG_DWORD integer at |key| named |name| into |result|. Returns false
-// if the value could no be read.
-bool ReadRegistryInteger(RegKey* key,
-                         const string16& name,
-                         uint32* result) {
-  DWORD dword;
-  if (key->ReadValueDW(name.c_str(), &dword) != ERROR_SUCCESS)
-    return false;
-  *result = dword;
-  return true;
+// Tries to extract the dictionary at |key| in |dict| and returns it.
+scoped_ptr<base::DictionaryValue> RemoveDict(base::DictionaryValue* dict,
+                                             const std::string& key) {
+  base::Value* entry = NULL;
+  base::DictionaryValue* result_dict = NULL;
+  if (dict && dict->RemoveWithoutPathExpansion(key, &entry) && entry) {
+    if (!entry->GetAsDictionary(&result_dict))
+      delete entry;
+  }
+
+  return make_scoped_ptr(result_dict);
+}
+
+std::string GetSchemaTypeForValueType(base::Value::Type value_type) {
+  switch (value_type) {
+    case base::Value::TYPE_DICTIONARY:
+      return json_schema_constants::kObject;
+    case base::Value::TYPE_INTEGER:
+      return json_schema_constants::kInteger;
+    case base::Value::TYPE_LIST:
+      return json_schema_constants::kArray;
+    case base::Value::TYPE_BOOLEAN:
+      return json_schema_constants::kBoolean;
+    case base::Value::TYPE_STRING:
+      return json_schema_constants::kString;
+    default:
+      break;
+  }
+
+  NOTREACHED() << "Unsupported policy value type " << value_type;
+  return json_schema_constants::kNull;
 }
 
 // Returns the Value type described in |schema|, or |default_type| if not found.
-base::Value::Type GetType(const base::DictionaryValue* schema,
-                          base::Value::Type default_type) {
+base::Value::Type GetValueTypeForSchema(const base::DictionaryValue* schema,
+                                        base::Value::Type default_type) {
   // JSON-schema types to base::Value::Type mapping.
   static const struct {
     // JSON schema type.
@@ -115,7 +237,7 @@ base::Value::Type GetType(const base::DictionaryValue* schema,
   if (!schema)
     return default_type;
   std::string type;
-  if (!schema->GetString(schema::kType, &type))
+  if (!schema->GetStringWithoutPathExpansion(schema::kType, &type))
     return default_type;
   for (size_t i = 0; i < arraysize(kSchemaToValueTypeMap); ++i) {
     if (type == kSchemaToValueTypeMap[i].schema_type)
@@ -124,28 +246,11 @@ base::Value::Type GetType(const base::DictionaryValue* schema,
   return default_type;
 }
 
-// Returns the default type for registry entries of |reg_type|, when there is
-// no schema defined type for a policy.
-base::Value::Type GetDefaultFor(DWORD reg_type) {
-  return reg_type == REG_DWORD ? base::Value::TYPE_INTEGER :
-                                 base::Value::TYPE_STRING;
-}
-
-// Returns the entry with key |name| in |dictionary| (can be NULL), or NULL.
-const base::DictionaryValue* GetEntry(const base::DictionaryValue* dictionary,
-                                      const std::string& name) {
-  if (!dictionary)
-    return NULL;
-  const base::DictionaryValue* entry = NULL;
-  dictionary->GetDictionary(name, &entry);
-  return entry;
-}
-
 // Returns the schema for property |name| given the |schema| of an object.
 // Returns the "additionalProperties" schema if no specific schema for
 // |name| is present. Returns NULL if no schema is found.
 const base::DictionaryValue* GetSchemaFor(const base::DictionaryValue* schema,
-                                    const std::string& name) {
+                                          const std::string& name) {
   const base::DictionaryValue* properties =
       GetEntry(schema, schema::kProperties);
   const base::DictionaryValue* sub_schema = GetEntry(properties, name);
@@ -155,241 +260,201 @@ const base::DictionaryValue* GetSchemaFor(const base::DictionaryValue* schema,
   return GetEntry(schema, schema::kAdditionalProperties);
 }
 
-// Converts string |value| to another |type|, if possible.
-base::Value* ConvertStringValue(const string16& value, base::Value::Type type) {
-  switch (type) {
-    case base::Value::TYPE_NULL:
-      return base::Value::CreateNullValue();
-
-    case base::Value::TYPE_BOOLEAN: {
-      int int_value;
-      if (base::StringToInt(value, &int_value))
-        return base::Value::CreateBooleanValue(int_value != 0);
-      return NULL;
+// Reads the subtree of the Windows registry at |root| into the passed |dict|.
+void ReadRegistry(HKEY hive,
+                  const string16& root,
+                  base::DictionaryValue* dict) {
+  // First, read all the values of the key.
+  for (RegistryValueIterator it(hive, root.c_str()); it.Valid(); ++it) {
+    const std::string name = UTF16ToUTF8(it.Name());
+    switch (it.Type()) {
+      case REG_SZ:
+      case REG_EXPAND_SZ:
+        dict->SetStringWithoutPathExpansion(name, UTF16ToUTF8(it.Value()));
+        continue;
+      case REG_DWORD_LITTLE_ENDIAN:
+      case REG_DWORD_BIG_ENDIAN:
+        if (it.ValueSize() == sizeof(DWORD)) {
+          DWORD dword_value = *(reinterpret_cast<const DWORD*>(it.Value()));
+          if (it.Type() == REG_DWORD_BIG_ENDIAN)
+            dword_value = base::NetToHost32(dword_value);
+          else
+            dword_value = base::ByteSwapToLE32(dword_value);
+          dict->SetIntegerWithoutPathExpansion(name, dword_value);
+          continue;
+        }
+      case REG_NONE:
+      case REG_LINK:
+      case REG_MULTI_SZ:
+      case REG_RESOURCE_LIST:
+      case REG_FULL_RESOURCE_DESCRIPTOR:
+      case REG_RESOURCE_REQUIREMENTS_LIST:
+      case REG_QWORD_LITTLE_ENDIAN:
+        // Unsupported type, message gets logged below.
+        break;
     }
 
-    case base::Value::TYPE_INTEGER: {
-      int int_value;
-      if (base::StringToInt(value, &int_value))
-          return base::Value::CreateIntegerValue(int_value);
-      return NULL;
-    }
+    LOG(WARNING) << "Failed to read hive " << hive << " at "
+                 << root << "\\" << name
+                 << " type " << it.Type();
+  }
 
-    case base::Value::TYPE_DOUBLE: {
-      double double_value;
-      if (base::StringToDouble(UTF16ToUTF8(value), &double_value))
-        return base::Value::CreateDoubleValue(double_value);
-      DLOG(WARNING) << "Failed to read policy value as double: " << value;
-      return NULL;
+  // Recurse for all subkeys.
+  for (RegistryKeyIterator it(hive, root.c_str()); it.Valid(); ++it) {
+    std::string name(UTF16ToUTF8(it.Name()));
+    if (dict->HasKey(name)) {
+      DLOG(WARNING) << "Ignoring registry key because a value exists with the "
+                       "same name: " << root << "\\" << name;
+    } else {
+      scoped_ptr<base::DictionaryValue> subdict(new base::DictionaryValue());
+      ReadRegistry(hive, root + L"\\" + it.Name(), subdict.get());
+      dict->SetWithoutPathExpansion(name, subdict.release());
     }
-
-    case base::Value::TYPE_STRING:
-      return base::Value::CreateStringValue(value);
-
-    case base::Value::TYPE_DICTIONARY:
-    case base::Value::TYPE_LIST:
-      return base::JSONReader::Read(UTF16ToUTF8(value));
-
-    case base::Value::TYPE_BINARY:
-      DLOG(WARNING) << "Cannot convert REG_SZ entry to type " << type;
-      return NULL;
   }
-  NOTREACHED();
-  return NULL;
 }
 
-// Converts an integer |value| to another |type|, if possible.
-base::Value* ConvertIntegerValue(uint32 value, base::Value::Type type) {
-  switch (type) {
-    case base::Value::TYPE_BOOLEAN:
-      return base::Value::CreateBooleanValue(value != 0);
-
-    case base::Value::TYPE_INTEGER:
-      return base::Value::CreateIntegerValue(value);
-
-    case base::Value::TYPE_DOUBLE:
-      return base::Value::CreateDoubleValue(value);
-
-    case base::Value::TYPE_NULL:
-    case base::Value::TYPE_STRING:
-    case base::Value::TYPE_BINARY:
-    case base::Value::TYPE_DICTIONARY:
-    case base::Value::TYPE_LIST:
-      DLOG(WARNING) << "Cannot convert REG_DWORD entry to type " << type;
-      return NULL;
+// Converts |value| in raw GPO representation to the internal policy value, as
+// described by |schema|. This maps the ambiguous GPO data types to the
+// internal policy value representations.
+scoped_ptr<base::Value> ConvertPolicyValue(
+    const base::Value& value,
+    const base::DictionaryValue* schema) {
+  // Figure out the type to convert to from the schema.
+  const base::Value::Type result_type(
+      GetValueTypeForSchema(schema, value.GetType()));
+
+  // If the type is good already, go with it.
+  if (value.IsType(result_type)) {
+    // Recurse for complex types if there is a schema.
+    if (schema) {
+      const base::DictionaryValue* dict = NULL;
+      const base::ListValue* list = NULL;
+      if (value.GetAsDictionary(&dict)) {
+        scoped_ptr<base::DictionaryValue> result(new base::DictionaryValue());
+        for (base::DictionaryValue::Iterator entry(*dict); entry.HasNext();
+             entry.Advance()) {
+          scoped_ptr<base::Value> converted_value(
+              ConvertPolicyValue(entry.value(),
+                                 GetSchemaFor(schema, entry.key())));
+          result->SetWithoutPathExpansion(entry.key(),
+                                          converted_value.release());
+        }
+        return result.Pass();
+      } else if (value.GetAsList(&list)) {
+        scoped_ptr<base::ListValue> result(new base::ListValue());
+        const base::DictionaryValue* item_schema =
+            GetEntry(schema, schema::kItems);
+        for (base::ListValue::const_iterator entry(list->begin());
+             entry != list->end(); ++entry) {
+          result->Append(ConvertPolicyValue(**entry, item_schema).release());
+        }
+        return result.Pass();
+      }
+    }
+    return make_scoped_ptr(value.DeepCopy());
   }
-  NOTREACHED();
-  return NULL;
-}
 
-// Reads a value from the registry |key| named |name| with registry type
-// |registry_type| as a value of type |type|.
-// Returns NULL if the value could not be loaded or converted.
-base::Value* ReadPolicyValue(RegKey* key,
-                             const string16& name,
-                             DWORD registry_type,
-                             base::Value::Type type) {
-  switch (registry_type) {
-    case REG_SZ: {
-      string16 value;
-      if (ReadRegistryString(key, name, &value))
-        return ConvertStringValue(value, type);
-      break;
+  // Else, do some conversions to map windows registry data types to JSON types.
+  std::string string_value;
+  int int_value = 0;
+  switch (result_type) {
+    case base::Value::TYPE_NULL: {
+      return make_scoped_ptr(base::Value::CreateNullValue());
     }
-
-    case REG_DWORD: {
-      uint32 value;
-      if (ReadRegistryInteger(key, name, &value))
-        return ConvertIntegerValue(value, type);
+    case base::Value::TYPE_BOOLEAN: {
+      // Accept booleans encoded as either string or integer.
+      if (value.GetAsInteger(&int_value) ||
+          (value.GetAsString(&string_value) &&
+           base::StringToInt(string_value, &int_value))) {
+        return make_scoped_ptr(Value::CreateBooleanValue(int_value != 0));
+      }
       break;
     }
-
-    default:
-      DLOG(WARNING) << "Registry type not supported for key " << name;
+    case base::Value::TYPE_INTEGER: {
+      // Integers may be string-encoded.
+      if (value.GetAsString(&string_value) &&
+          base::StringToInt(string_value, &int_value)) {
+        return make_scoped_ptr(base::Value::CreateIntegerValue(int_value));
+      }
       break;
-  }
-  return NULL;
-}
-
-// Forward declaration for ReadComponentListValue().
-base::DictionaryValue* ReadComponentDictionaryValue(
-    HKEY hive,
-    const string16& path,
-    const base::DictionaryValue* schema);
-
-// Loads the list at |path| in the given |hive|. |schema| is a JSON schema
-// (http://json-schema.org/) that describes the expected type of the list.
-// Ownership of the result is transferred to the caller.
-base::ListValue* ReadComponentListValue(HKEY hive,
-                                        const string16& path,
-                                        const base::DictionaryValue* schema) {
-  // The sub-elements are indexed from 1 to N. They can be represented as
-  // registry values or registry keys though; use |schema| first to try to
-  // determine the right type, and if that fails default to STRING.
-
-  RegKey key(hive, path.c_str(), KEY_READ);
-  if (!key.Valid())
-    return NULL;
-
-  // Get the schema for list items.
-  schema = GetEntry(schema, schema::kItems);
-  base::Value::Type type = GetType(schema, base::Value::TYPE_STRING);
-  base::ListValue* list = new base::ListValue();
-  for (int i = 1; ; ++i) {
-    string16 name = base::IntToString16(i);
-    base::Value* value = NULL;
-    if (type == base::Value::TYPE_DICTIONARY) {
-      value =
-          ReadComponentDictionaryValue(hive, path + kPathSep + name, schema);
-    } else if (type == base::Value::TYPE_LIST) {
-      value = ReadComponentListValue(hive, path + kPathSep + name, schema);
-    } else {
-      DWORD reg_type;
-      key.ReadValue(name.c_str(), NULL, NULL, &reg_type);
-      if (reg_type != REG_NONE)
-        value = ReadPolicyValue(&key, name, reg_type, type);
     }
-    if (value)
-      list->Append(value);
-    else
+    case base::Value::TYPE_DOUBLE: {
+      // Doubles may be string-encoded or integer-encoded.
+      double double_value = 0;
+      if (value.GetAsInteger(&int_value)) {
+        return make_scoped_ptr(base::Value::CreateDoubleValue(int_value));
+      } else if (value.GetAsString(&string_value) &&
+                 base::StringToDouble(string_value, &double_value)) {
+        return make_scoped_ptr(base::Value::CreateDoubleValue(double_value));
+      }
       break;
-  }
-  return list;
-}
-
-// Loads the dictionary at |path| in the given |hive|. |schema| is a JSON
-// schema (http://json-schema.org/) that describes the expected types for the
-// dictionary entries. When the type for a certain entry isn't described in the
-// schema, a default conversion takes place. |schema| can be NULL.
-// Ownership of the result is transferred to the caller.
-base::DictionaryValue* ReadComponentDictionaryValue(
-    HKEY hive,
-    const string16& path,
-    const base::DictionaryValue* schema) {
-  // A "value" in the registry is like a file in a filesystem, and a "key" is
-  // like a directory, that contains other "values" and "keys".
-  // Unfortunately it is possible to have a name both as a "value" and a "key".
-  // In those cases, the sub "key" will be ignored; this choice is arbitrary.
-
-  // First iterate over all the "values" in |path| and convert them; then
-  // recurse into each "key" in |path| and convert them as dictionaries.
-
-  RegKey key(hive, path.c_str(), KEY_READ);
-  if (!key.Valid())
-    return NULL;
-
-  base::DictionaryValue* dict = new base::DictionaryValue();
-  for (RegistryValueIterator it(hive, path.c_str()); it.Valid(); ++it) {
-    string16 name16(it.Name());
-    std::string name(UTF16ToUTF8(name16));
-    const base::DictionaryValue* sub_schema = GetSchemaFor(schema, name);
-    base::Value::Type type = GetType(sub_schema, GetDefaultFor(it.Type()));
-    base::Value* value = ReadPolicyValue(&key, name16, it.Type(), type);
-    if (value)
-      dict->Set(name, value);
-  }
-
-  for (RegistryKeyIterator it(hive, path.c_str()); it.Valid(); ++it) {
-    string16 name16(it.Name());
-    std::string name(UTF16ToUTF8(name16));
-    if (dict->HasKey(name)) {
-      DLOG(WARNING) << "Ignoring registry key because a value exists with the "
-                       "same name: " << path << kPathSep << name;
-      continue;
     }
-
-    const base::DictionaryValue* sub_schema = GetSchemaFor(schema, name);
-    base::Value::Type type = GetType(sub_schema, base::Value::TYPE_DICTIONARY);
-    base::Value* value = NULL;
-    const string16 sub_path = path + kPathSep + name16;
-    if (type == base::Value::TYPE_DICTIONARY) {
-      value = ReadComponentDictionaryValue(hive, sub_path, sub_schema);
-    } else if (type == base::Value::TYPE_LIST) {
-      value = ReadComponentListValue(hive, sub_path, sub_schema);
-    } else {
-      DLOG(WARNING) << "Can't read a simple type in registry key at " << path;
+    case base::Value::TYPE_LIST: {
+      // Lists are encoded as subkeys with numbered value in the registry.
+      const base::DictionaryValue* dict = NULL;
+      if (value.GetAsDictionary(&dict)) {
+        scoped_ptr<base::ListValue> result(new base::ListValue());
+        const base::DictionaryValue* item_schema =
+            GetEntry(schema, schema::kItems);
+        for (int i = 1; ; ++i) {
+          const base::Value* entry = NULL;
+          if (!dict->Get(base::IntToString(i), &entry))
+            break;
+          result->Append(ConvertPolicyValue(*entry, item_schema).release());
+        }
+        return result.Pass();
+      }
+      // Fall through in order to accept lists encoded as JSON strings.
     }
-    if (value)
-      dict->Set(name, value);
+    case base::Value::TYPE_DICTIONARY: {
+      // Dictionaries may be encoded as JSON strings.
+      if (value.GetAsString(&string_value)) {
+        scoped_ptr<base::Value> result(base::JSONReader::Read(string_value));
+        if (result && result->IsType(result_type))
+          return result.Pass();
+      }
+      break;
+    }
+    case base::Value::TYPE_STRING:
+    case base::Value::TYPE_BINARY:
+      // No conversion possible.
+      break;
   }
 
-  return dict;
+  LOG(WARNING) << "Failed to convert " << value.GetType()
+               << " to " << result_type;
+  return make_scoped_ptr(base::Value::CreateNullValue());
 }
 
-// Reads a JSON schema from the given |registry_value|, at the given
-// |registry_key| in |hive|. |registry_value| must be a string (REG_SZ), and
-// is decoded as JSON data. Returns NULL on failure. Ownership is transferred
-// to the caller.
-base::DictionaryValue* ReadRegistrySchema(HKEY hive,
-                                          const string16& registry_key,
-                                          const string16& registry_value) {
-  RegKey key(hive, registry_key.c_str(), KEY_READ);
-  string16 schema;
-  if (!ReadRegistryString(&key, registry_value, &schema))
-    return NULL;
-  // A JSON schema is represented in JSON too.
-  scoped_ptr<base::Value> value(base::JSONReader::Read(UTF16ToUTF8(schema)));
-  if (!value.get())
-    return NULL;
-  base::DictionaryValue* dict = NULL;
-  if (!value->GetAsDictionary(&dict))
-    return NULL;
-  // The top-level entry must be an object, and each of its properties maps
-  // a policy name to its schema.
-  if (GetType(dict, base::Value::TYPE_DICTIONARY) !=
-      base::Value::TYPE_DICTIONARY) {
-    DLOG(WARNING) << "schema top-level type isn't \"object\"";
-    return NULL;
+// Parses |gpo_dict| according to |schema| and writes the resulting policy
+// settings to |policy| for the given |scope| and |level|.
+void ParsePolicy(const base::DictionaryValue* gpo_dict,
+                 PolicyLevel level,
+                 PolicyScope scope,
+                 const base::DictionaryValue* schema,
+                 PolicyMap* policy) {
+  if (!gpo_dict)
+    return;
+
+  scoped_ptr<base::Value> policy_value(ConvertPolicyValue(*gpo_dict, schema));
+  const base::DictionaryValue* policy_dict = NULL;
+  if (!policy_value->GetAsDictionary(&policy_dict) || !policy_dict) {
+    LOG(WARNING) << "Root policy object is not a dictionary!";
+    return;
   }
-  value.release();
-  return dict;
+
+  policy->LoadFrom(policy_dict, level, scope);
 }
 
 }  // namespace
 
-PolicyLoaderWin::PolicyLoaderWin(const PolicyDefinitionList* policy_list)
+PolicyLoaderWin::PolicyLoaderWin(const PolicyDefinitionList* policy_list,
+                                 const string16& chrome_policy_key,
+                                 AppliedGPOListProvider* gpo_provider)
     : is_initialized_(false),
+      chrome_policy_key_(chrome_policy_key),
       policy_list_(policy_list),

[Joao da Silva, 2013/04/10 12:32:12]

The order in the header is different.

[Mattias Nissler (ping if slow), 2013/04/10 13:20:25]

Done.

+      gpo_provider_(gpo_provider),
       user_policy_changed_event_(false, false),
       machine_policy_changed_event_(false, false),
       user_policy_watcher_failed_(false),
@@ -409,155 +474,259 @@ PolicyLoaderWin::~PolicyLoaderWin() {
   machine_policy_watcher_.StopWatching();
 }
 
+// static
+scoped_ptr<PolicyLoaderWin> PolicyLoaderWin::Create(
+    const PolicyDefinitionList* policy_list) {
+  return make_scoped_ptr(
+      new PolicyLoaderWin(policy_list, kRegistryChromePolicyKey,
+                          g_win_gpo_list_provider.Pointer()));
+}
+
 void PolicyLoaderWin::InitOnFile() {
   is_initialized_ = true;
   SetupWatches();
 }
 
 scoped_ptr<PolicyBundle> PolicyLoaderWin::Load() {
-  scoped_ptr<PolicyBundle> bundle(new PolicyBundle());
-  LoadChromePolicy(
-      &bundle->Get(PolicyNamespace(POLICY_DOMAIN_CHROME, std::string())));
-  Load3rdPartyPolicies(bundle.get());
-  return bundle.Pass();
-}
-
-void PolicyLoaderWin::LoadChromePolicy(PolicyMap* chrome_policies) {
   // Reset the watches BEFORE reading the individual policies to avoid
   // missing a change notification.
   if (is_initialized_)
     SetupWatches();
 
-  // |kKeyPaths| is in decreasing order of priority.
+  if (chrome_policy_schema_.empty())
+    BuildChromePolicySchema();
+
+  // Policy scope and corresponding hive.
   static const struct {
-    const wchar_t* path;
-    PolicyLevel level;
-  } kKeyPaths[] = {
-    { kRegistryMandatorySubKey,   POLICY_LEVEL_MANDATORY    },
-    { kRegistryRecommendedSubKey, POLICY_LEVEL_RECOMMENDED  },
+    PolicyScope scope;
+    HKEY hive;
+  } kScopes[] = {
+    { POLICY_SCOPE_MACHINE, HKEY_LOCAL_MACHINE },
+    { POLICY_SCOPE_USER,    HKEY_CURRENT_USER  },
   };
 
-  // Lookup at the mandatory path for both user and machine policies first, and
-  // then at the recommended path.
-  for (size_t k = 0; k < arraysize(kKeyPaths); ++k) {
-    for (size_t h = 0; h < arraysize(kHives); ++h) {
-      // Iterate over keys and values at this hive and path.
-      HKEY hive = kHives[h].hive;
-      string16 path(kKeyPaths[k].path);
-      RegKey key;
-      if (key.Open(hive, path.c_str(), KEY_READ) != ERROR_SUCCESS ||
-          !key.Valid()) {
-        continue;
-      }
+  // Load policy data for the different scopes/levels and merge them.
+  scoped_ptr<PolicyBundle> bundle(new PolicyBundle());
+  PolicyMap* chrome_policy =
+      &bundle->Get(PolicyNamespace(POLICY_DOMAIN_CHROME, std::string()));
+  for (size_t i = 0; i < arraysize(kScopes); ++i) {
+    PolicyScope scope = kScopes[i].scope;
+    base::DictionaryValue gpo_dict;
+
+    HANDLE policy_lock =
+        EnterCriticalPolicySection(scope == POLICY_SCOPE_MACHINE);

[Joao da Silva, 2013/04/10 12:32:12]

Is this needed to read from the registry? If not then the lock/unlock can be
moved to ReadPolicyFromGPO.

[Mattias Nissler (ping if slow), 2013/04/10 13:20:25]

This makes sure GPO doesn't update behind our back while we're reading, so this
is the GPO way for ensuring you're getting a consistent snapshot.

+    if (policy_lock == NULL)
+      PLOG(ERROR) << "EnterCriticalPolicySection";
+
+    if (!ReadPolicyFromGPO(scope, &gpo_dict)) {
+      VLOG(1) << "Failed to read GPO files for " << scope
+              << " falling back to registry.";
+      ReadRegistry(kScopes[i].hive, chrome_policy_key_, &gpo_dict);
+    }
 
-      // Iterate over values for most policies.
-      for (RegistryValueIterator it(hive, path.c_str()); it.Valid(); ++it) {
-        std::string name(UTF16ToUTF8(it.Name()));
-        // Skip if a higher-priority policy value was already inserted, or
-        // if this is the default value (empty string).
-        if (chrome_policies->Get(name) || name.empty())
-          continue;
-        // Get the expected policy type, if this is a known policy.
-        base::Value::Type type = GetDefaultFor(it.Type());
-        for (const PolicyDefinitionList::Entry* e = policy_list_->begin;
-             e != policy_list_->end; ++e) {
-          if (name == e->name) {
-            type = e->value_type;
-            break;
-          }
-        }
-        base::Value* value = ReadPolicyValue(&key, it.Name(), it.Type(), type);
-        if (!value)
-          value = base::Value::CreateNullValue();
-        chrome_policies->Set(name, kKeyPaths[k].level, kHives[h].scope, value);
-      }
+    if (!LeaveCriticalPolicySection(policy_lock))

[Joao da Silva, 2013/04/10 12:32:12]

Is this safe if Enter failed?

[Mattias Nissler (ping if slow), 2013/04/10 13:20:25]

Yes and no :) Yes, because there's no reason why Chrome or the Win API would
crash if the Enter call fails. No, because we might read inconsistent data (in
particular when reading from the registry), but I think doing a best-effort read
is still better than bailing out and running without policy.

+      PLOG(ERROR) << "LeaveCriticalPolicySection";
 
-      // Iterate over keys for policies of type string-list.
-      for (RegistryKeyIterator it(hive, path.c_str()); it.Valid(); ++it) {
-        std::string name(UTF16ToUTF8(it.Name()));
-        // Skip if a higher-priority policy value was already inserted, or
-        // if this is the 3rd party policy subkey.
-        const string16 kThirdParty16(kThirdParty);
-        if (chrome_policies->Get(name) || it.Name() == kThirdParty16)
-          continue;
-        string16 list_path = path + kPathSep + it.Name();
-        RegKey key;
-        if (key.Open(hive, list_path.c_str(), KEY_READ) != ERROR_SUCCESS ||
-            !key.Valid()) {
-          continue;
-        }
-        base::ListValue* result = new base::ListValue();
-        string16 value;
-        int index = 0;
-        while (ReadRegistryString(&key, base::IntToString16(++index), &value))
-          result->Append(base::Value::CreateStringValue(value));
-        chrome_policies->Set(name, kKeyPaths[k].level, kHives[h].scope, result);
-      }
+    // Remove special-cased entries from the GPO dictionary.
+    base::DictionaryValue* temp_dict = NULL;
+    scoped_ptr<base::DictionaryValue> recommended_dict(
+        RemoveDict(&gpo_dict, kKeyRecommended));
+    scoped_ptr<base::DictionaryValue> third_party_dict(
+        RemoveDict(&gpo_dict, kKeyThirdParty));
+
+    // Load Chrome policy.
+    LoadChromePolicy(&gpo_dict, POLICY_LEVEL_MANDATORY, scope, chrome_policy);
+    LoadChromePolicy(recommended_dict.get(), POLICY_LEVEL_RECOMMENDED, scope,
+                     chrome_policy);
+
+    // Load 3rd-party policy.
+    if (third_party_dict)
+      Load3rdPartyPolicy(third_party_dict.get(), scope, bundle.get());
+  }
+
+  return bundle.Pass();
+}
+
+void PolicyLoaderWin::BuildChromePolicySchema() {
+  scoped_ptr<base::DictionaryValue> properties(new base::DictionaryValue());
+  for (const PolicyDefinitionList::Entry* e = policy_list_->begin;
+       e != policy_list_->end; ++e) {
+    const std::string schema_type = GetSchemaTypeForValueType(e->value_type);
+    scoped_ptr<base::DictionaryValue> entry_schema(new base::DictionaryValue());
+    entry_schema->SetStringWithoutPathExpansion(json_schema_constants::kType,
+                                                schema_type);
+
+    if (e->value_type == base::Value::TYPE_LIST) {
+      scoped_ptr<base::DictionaryValue> items_schema(
+          new base::DictionaryValue());
+      items_schema->SetStringWithoutPathExpansion(
+          json_schema_constants::kType, json_schema_constants::kString);
+      entry_schema->SetWithoutPathExpansion(json_schema_constants::kItems,
+                                            items_schema.release());
     }
+    properties->SetWithoutPathExpansion(e->name, entry_schema.release());
   }
+  chrome_policy_schema_.SetStringWithoutPathExpansion(
+      json_schema_constants::kType, json_schema_constants::kObject);
+  chrome_policy_schema_.SetWithoutPathExpansion(
+      json_schema_constants::kProperties, properties.release());
 }
 
-void PolicyLoaderWin::Load3rdPartyPolicies(PolicyBundle* bundle) {
-  // Each 3rd party namespace can have policies on both HKLM and HKCU. They
-  // should be merged, giving priority to HKLM for policies with the same name.
+bool PolicyLoaderWin::ReadPRegFile(const base::FilePath& preg_file,
+                                   base::DictionaryValue* policy) {
+  // The following deals with the minor annoyance that Wow64 FS redirection
+  // might need to be turned off: This is the case if running as a 32-bit
+  // process on a 64-bit system, in which case Wow64 FS redirection redirects
+  // access to the %WINDIR%/System32/GroupPolicy directory to
+  // %WINDIR%/SysWOW64/GroupPolicy, but the file is actually in the
+  // system-native directory.
+  if (file_util::PathExists(preg_file)) {
+    return preg_parser::ReadFile(preg_file, chrome_policy_key_, policy);
+  } else {
+    // Try with redirection switched off.
+    ScopedDisableWow64Redirection redirection_disable;
+    if (redirection_disable.is_active() && file_util::PathExists(preg_file))
+      return preg_parser::ReadFile(preg_file, chrome_policy_key_, policy);
+  }
+
+  // Report the error.
+  LOG(ERROR) << "PReg file doesn't exist: " << preg_file.value();
+  return false;
+}
+
+bool PolicyLoaderWin::LoadGPOPolicy(PolicyScope scope,
+                                    PGROUP_POLICY_OBJECT policy_object_list,
+                                    base::DictionaryValue* policy) {
+  base::DictionaryValue parsed_policy;
+  base::DictionaryValue forced_policy;
+  for (GROUP_POLICY_OBJECT* policy_object = policy_object_list;
+       policy_object; policy_object = policy_object->pNext) {
+    if (policy_object->dwOptions & GPO_FLAG_DISABLE)
+      continue;
+
+    if (PathIsUNC(policy_object->lpFileSysPath)) {
+      // UNC path: Assume this is an AD-managed machine, which updates the
+      // registry via GPO's standard registry CSE periodically. Fall back to
+      // reading from the registry in this case.
+      return false;
+    }
+
+    base::FilePath preg_file_path(
+        base::FilePath(policy_object->lpFileSysPath).Append(kPRegFileName));
+    if (policy_object->dwOptions & GPO_FLAG_FORCE) {
+      base::DictionaryValue new_forced_policy;
+      if (!ReadPRegFile(preg_file_path, &new_forced_policy))
+        return false;
+
+      // Merge with existing forced policy, giving precedence to the existing
+      // forced policy.
+      new_forced_policy.MergeDictionary(&forced_policy);
+      forced_policy.Swap(&new_forced_policy);
+    } else {
+      if (!ReadPRegFile(preg_file_path, &parsed_policy))
+        return false;
+    }
+  }
+
+  // Merge, give precedence to forced policy.
+  parsed_policy.MergeDictionary(&forced_policy);
+  policy->Swap(&parsed_policy);
 
-  // Map of known domain name to their enum values.
+  return true;
+}
+
+
+bool PolicyLoaderWin::ReadPolicyFromGPO(PolicyScope scope,
+                                        base::DictionaryValue* policy) {
+  PGROUP_POLICY_OBJECT policy_object_list = NULL;
+  DWORD flags = scope == POLICY_SCOPE_MACHINE ? GPO_LIST_FLAG_MACHINE : 0;
+  if (gpo_provider_->GetAppliedGPOList(
+          flags, NULL, NULL, &kRegistrySettingsCSEGUID,
+          &policy_object_list) != ERROR_SUCCESS) {
+    PLOG(ERROR) << "GetAppliedGPOList scope " << scope;
+    return false;
+  }
+
+  bool result = LoadGPOPolicy(scope, policy_object_list, policy);
+  if (!gpo_provider_->FreeGPOList(policy_object_list))
+    LOG(WARNING) << "FreeGPOList";
+
+  return result;
+}
+
+void PolicyLoaderWin::LoadChromePolicy(const base::DictionaryValue* gpo_dict,
+                                       PolicyLevel level,
+                                       PolicyScope scope,
+                                       PolicyMap* chrome_policy_map) {
+  PolicyMap policy;
+  ParsePolicy(gpo_dict, level, scope, &chrome_policy_schema_, &policy);
+  chrome_policy_map->MergeFrom(policy);
+}
+
+void PolicyLoaderWin::Load3rdPartyPolicy(
+    const DictionaryValue* gpo_dict,
+    PolicyScope scope,
+    PolicyBundle* bundle) {
+  // Map of known 3rd party policy domain name to their enum values.
   static const struct {
     const char* name;
     PolicyDomain domain;
-  } kDomains[] = {
-    { "extensions",   POLICY_DOMAIN_EXTENSIONS },
+  } k3rdPartyDomains[] = {
+    { "extensions", POLICY_DOMAIN_EXTENSIONS },
   };
 
-  // Map of policy paths to their corresponding policy level, in decreasing
-  // order of priority.
+  // Policy level and corresponding path.
   static const struct {
-    const char* path;
     PolicyLevel level;
-  } kKeyPaths[] = {
-    { "policy",       POLICY_LEVEL_MANDATORY },
-    { "recommended",  POLICY_LEVEL_RECOMMENDED },
+    const char* path;
+  } kLevels[] = {
+    { POLICY_LEVEL_MANDATORY,   kKeyMandatory   },
+    { POLICY_LEVEL_RECOMMENDED, kKeyRecommended },
   };
 
-  // Path where policies for components are stored.
-  const string16 kPathPrefix = string16(kRegistryMandatorySubKey) + kPathSep +
-                               kThirdParty + kPathSep;
-
-  for (size_t h = 0; h < arraysize(kHives); ++h) {
-    HKEY hkey = kHives[h].hive;
-
-    for (size_t d = 0; d < arraysize(kDomains); ++d) {
-      // Each subkey under this domain is a component of that domain.
-      // |domain_path| == SOFTWARE\Policies\Chromium\3rdparty\<domain>
-      string16 domain_path = kPathPrefix + ASCIIToUTF16(kDomains[d].name);
-
-      for (RegistryKeyIterator domain_iterator(hkey, domain_path.c_str());
-           domain_iterator.Valid(); ++domain_iterator) {
-        string16 component(domain_iterator.Name());
-        string16 component_path = domain_path + kPathSep + component;
-
-        // Load the schema for this component's policy, if present.
-        scoped_ptr<base::DictionaryValue> schema(
-            ReadRegistrySchema(hkey, component_path, kSchema));
-
-        for (size_t k = 0; k < arraysize(kKeyPaths); ++k) {
-          string16 path =
-              component_path + kPathSep + ASCIIToUTF16(kKeyPaths[k].path);
-
-          scoped_ptr<base::DictionaryValue> dictionary(
-              ReadComponentDictionaryValue(hkey, path, schema.get()));
-          if (dictionary.get()) {
-            PolicyMap policies;
-            policies.LoadFrom(
-                dictionary.get(), kKeyPaths[k].level, kHives[h].scope);
-            // LoadFrom() overwrites any existing values. Use a temporary map
-            // and then use MergeFrom(), that only overwrites values with lower
-            // priority.
-            bundle->Get(PolicyNamespace(kDomains[d].domain,
-                                        UTF16ToUTF8(component)))
-                .MergeFrom(policies);
-          }
+  for (size_t i = 0; i < arraysize(k3rdPartyDomains); i++) {
+    const char* name = k3rdPartyDomains[i].name;
+    const PolicyDomain domain = k3rdPartyDomains[i].domain;
+    const base::DictionaryValue* domain_dict = NULL;
+    if (!gpo_dict->GetDictionaryWithoutPathExpansion(name, &domain_dict) ||
+        !domain_dict) {
+      continue;
+    }
+
+    for (base::DictionaryValue::Iterator component(*domain_dict);
+         component.HasNext(); component.Advance()) {
+      const base::DictionaryValue* component_dict = NULL;
+      if (!component.value().GetAsDictionary(&component_dict) ||
+          !component_dict) {
+        continue;
+      }
+
+      // Load the schema.
+      scoped_ptr<base::Value> schema;
+      const base::DictionaryValue* schema_dict = NULL;
+      std::string schema_json;
+      if (component_dict->GetStringWithoutPathExpansion(kKeySchema,
+                                                        &schema_json)) {
+        schema.reset(base::JSONReader::Read(schema_json));
+        if (!schema || !schema->GetAsDictionary(&schema_dict)) {
+          LOG(WARNING) << "Failed to parse 3rd-part policy schema for "
+                       << domain << "/" << component.key();
+        }
+      }
+
+      // Parse policy.
+      for (size_t j = 0; j < arraysize(kLevels); j++) {
+        const base::DictionaryValue* policy_dict = NULL;
+        if (!component_dict->GetDictionaryWithoutPathExpansion(
+                kLevels[j].path, &policy_dict) ||
+            !policy_dict) {
+          continue;
         }
+
+        PolicyMap policy;
+        ParsePolicy(policy_dict, kLevels[j].level, scope, schema_dict, &policy);
+        PolicyNamespace policy_namespace(domain, component.key());
+        bundle->Get(policy_namespace).MergeFrom(policy);
       }
     }
   }