Move policy code into components/policy.

chrome/browser/policy/cloud/resource_cache.cc

-// Copyright (c) 2013 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/policy/cloud/resource_cache.h"
-
-#include "base/base64.h"
-#include "base/callback.h"
-#include "base/file_util.h"
-#include "base/files/file_enumerator.h"
-#include "base/logging.h"
-#include "base/safe_numerics.h"
-#include "base/sequenced_task_runner.h"
-#include "base/strings/string_util.h"
-
-namespace policy {
-
-namespace {
-
-// Verifies that |value| is not empty and encodes it into base64url format,
-// which is safe to use as a file name on all platforms.
-bool Base64Encode(const std::string& value, std::string* encoded) {
-  DCHECK(!value.empty());
-  if (value.empty() || !base::Base64Encode(value, encoded))
-    return false;
-  base::ReplaceChars(*encoded, "+", "-", encoded);
-  base::ReplaceChars(*encoded, "/", "_", encoded);
-  return true;
-}
-
-// Decodes all elements of |input| from base64url format and stores the decoded
-// elements in |output|.
-bool Base64Encode(const std::set<std::string>& input,
-                  std::set<std::string>* output) {
-  output->clear();
-  for (std::set<std::string>::const_iterator it = input.begin();
-       it != input.end(); ++it) {
-    std::string encoded;
-    if (!Base64Encode(*it, &encoded)) {
-      output->clear();
-      return false;
-    }
-    output->insert(encoded);
-  }
-  return true;
-}
-
-// Decodes |encoded| from base64url format and verifies that the result is not
-// emtpy.
-bool Base64Decode(const std::string& encoded, std::string* value) {
-  std::string buffer;
-  base::ReplaceChars(encoded, "-", "+", &buffer);
-  base::ReplaceChars(buffer, "_", "/", &buffer);
-  return base::Base64Decode(buffer, value) && !value->empty();
-}
-
-}  // namespace
-
-ResourceCache::ResourceCache(
-    const base::FilePath& cache_dir,
-    scoped_refptr<base::SequencedTaskRunner> task_runner)
-    : cache_dir_(cache_dir),
-      task_runner_(task_runner) {
-}
-
-ResourceCache::~ResourceCache() {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-}
-
-bool ResourceCache::Store(const std::string& key,
-                          const std::string& subkey,
-                          const std::string& data) {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-  base::FilePath subkey_path;
-  // Delete the file before writing to it. This ensures that the write does not
-  // follow a symlink planted at |subkey_path|, clobbering a file outside the
-  // cache directory. The mechanism is meant to foil file-system-level attacks
-  // where a symlink is planted in the cache directory before Chrome has
-  // started. An attacker controlling a process running concurrently with Chrome
-  // would be able to race against the protection by re-creating the symlink
-  // between these two calls. There is nothing in file_util that could be used
-  // to protect against such races, especially as the cache is cross-platform
-  // and therefore cannot use any POSIX-only tricks.
-  int size = base::checked_numeric_cast<int>(data.size());
-  return VerifyKeyPathAndGetSubkeyPath(key, true, subkey, &subkey_path) &&
-         base::DeleteFile(subkey_path, false) &&
-         (file_util::WriteFile(subkey_path, data.data(), size) == size);
-}
-
-bool ResourceCache::Load(const std::string& key,
-                         const std::string& subkey,
-                         std::string* data) {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-  base::FilePath subkey_path;
-  // Only read from |subkey_path| if it is not a symlink.
-  if (!VerifyKeyPathAndGetSubkeyPath(key, false, subkey, &subkey_path) ||
-      base::IsLink(subkey_path)) {
-    return false;
-  }
-  data->clear();
-  return base::ReadFileToString(subkey_path, data);
-}
-
-void ResourceCache::LoadAllSubkeys(
-    const std::string& key,
-    std::map<std::string, std::string>* contents) {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-  contents->clear();
-  base::FilePath key_path;
-  if (!VerifyKeyPath(key, false, &key_path))
-    return;
-
-  base::FileEnumerator enumerator(key_path, false, base::FileEnumerator::FILES);
-  for (base::FilePath path = enumerator.Next(); !path.empty();
-       path = enumerator.Next()) {
-    const std::string encoded_subkey = path.BaseName().MaybeAsASCII();
-    std::string subkey;
-    std::string data;
-    // Only read from |subkey_path| if it is not a symlink and its name is
-    // a base64-encoded string.
-    if (!base::IsLink(path) &&
-        Base64Decode(encoded_subkey, &subkey) &&
-        base::ReadFileToString(path, &data)) {
-      (*contents)[subkey].swap(data);
-    }
-  }
-}
-
-void ResourceCache::Delete(const std::string& key, const std::string& subkey) {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-  base::FilePath subkey_path;
-  if (VerifyKeyPathAndGetSubkeyPath(key, false, subkey, &subkey_path))
-    base::DeleteFile(subkey_path, false);
-  // Delete() does nothing if the directory given to it is not empty. Hence, the
-  // call below deletes the directory representing |key| if its last subkey was
-  // just removed and does nothing otherwise.
-  base::DeleteFile(subkey_path.DirName(), false);
-}
-
-void ResourceCache::Clear(const std::string& key) {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-  base::FilePath key_path;
-  if (VerifyKeyPath(key, false, &key_path))
-    base::DeleteFile(key_path, true);
-}
-
-void ResourceCache::FilterSubkeys(const std::string& key,
-                                  const SubkeyFilter& test) {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-
-  base::FilePath key_path;
-  if (!VerifyKeyPath(key, false, &key_path))
-    return;
-
-  base::FileEnumerator enumerator(key_path, false, base::FileEnumerator::FILES);
-  for (base::FilePath subkey_path = enumerator.Next();
-       !subkey_path.empty(); subkey_path = enumerator.Next()) {
-    std::string subkey;
-    // Delete files with invalid names, and files whose subkey doesn't pass the
-    // filter.
-    if (!Base64Decode(subkey_path.BaseName().MaybeAsASCII(), &subkey) ||
-        test.Run(subkey)) {
-      base::DeleteFile(subkey_path, true);
-    }
-  }
-
-  // Delete() does nothing if the directory given to it is not empty. Hence, the
-  // call below deletes the directory representing |key| if all of its subkeys
-  // were just removed and does nothing otherwise.
-  base::DeleteFile(key_path, false);
-}
-
-void ResourceCache::PurgeOtherKeys(const std::set<std::string>& keys_to_keep) {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-  std::set<std::string> encoded_keys_to_keep;
-  if (!Base64Encode(keys_to_keep, &encoded_keys_to_keep))
-    return;
-
-  base::FileEnumerator enumerator(
-      cache_dir_, false, base::FileEnumerator::DIRECTORIES);
-  for (base::FilePath path = enumerator.Next(); !path.empty();
-       path = enumerator.Next()) {
-    const std::string name(path.BaseName().MaybeAsASCII());
-    if (encoded_keys_to_keep.find(name) == encoded_keys_to_keep.end())
-      base::DeleteFile(path, true);
-  }
-}
-
-void ResourceCache::PurgeOtherSubkeys(
-    const std::string& key,
-    const std::set<std::string>& subkeys_to_keep) {
-  DCHECK(task_runner_->RunsTasksOnCurrentThread());
-  base::FilePath key_path;
-  if (!VerifyKeyPath(key, false, &key_path))
-    return;
-
-  std::set<std::string> encoded_subkeys_to_keep;
-  if (!Base64Encode(subkeys_to_keep, &encoded_subkeys_to_keep))
-    return;
-
-  base::FileEnumerator enumerator(key_path, false, base::FileEnumerator::FILES);
-  for (base::FilePath path = enumerator.Next(); !path.empty();
-       path = enumerator.Next()) {
-    const std::string name(path.BaseName().MaybeAsASCII());
-    if (encoded_subkeys_to_keep.find(name) == encoded_subkeys_to_keep.end())
-      base::DeleteFile(path, false);
-  }
-  // Delete() does nothing if the directory given to it is not empty. Hence, the
-  // call below deletes the directory representing |key| if all of its subkeys
-  // were just removed and does nothing otherwise.
-  base::DeleteFile(key_path, false);
-}
-
-bool ResourceCache::VerifyKeyPath(const std::string& key,
-                                  bool allow_create,
-                                  base::FilePath* path) {
-  std::string encoded;
-  if (!Base64Encode(key, &encoded))
-    return false;
-  *path = cache_dir_.AppendASCII(encoded);
-  return allow_create ? base::CreateDirectory(*path) :
-                        base::DirectoryExists(*path);
-}
-
-bool ResourceCache::VerifyKeyPathAndGetSubkeyPath(const std::string& key,
-                                                  bool allow_create_key,
-                                                  const std::string& subkey,
-                                                  base::FilePath* path) {
-  base::FilePath key_path;
-  std::string encoded;
-  if (!VerifyKeyPath(key, allow_create_key, &key_path) ||
-      !Base64Encode(subkey, &encoded)) {
-    return false;
-  }
-  *path = key_path.AppendASCII(encoded);
-  return true;
-}
-
-
-}  // namespace policy