Enforce cache_path requirements for NetworkService (see issue #2622).

This change adds a new CefSettings.root_cache_path value that must be either
equal to or a parent directory of all CefSettings.cache_path and
CefRequestContextSettings.cache_path values. The sandbox may block read/write
access from the NetworkService to directories that do not meet this requirement.

To test: Run cefclient with a combination of the following flags:

--cache-path=c:\temp\cache
  Cache data should be persisted to the specified directory.

--request-context-per-browser
  A separate numbered cache directory should be created underneath the
  cache-path directory for each new browser instance.

--enable-network-service --disable-extensions
  Same tests, but with NetworkService enabled.

Known issues:
- When NetworkService is enabled a C:\temp\cache\cache\Cache directory is
  created (should be C:\temp\cache\Cache).

libcef/browser/browser_context.cc

@@ -24,7 +24,6 @@
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/strings/string_util.h"
-#include "base/threading/thread_restrictions.h"
 #include "chrome/browser/font_family_cache.h"
 #include "chrome/browser/plugins/chrome_plugin_service_filter.h"
 #include "chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
@@ -260,16 +259,13 @@ CefBrowserContext::~CefBrowserContext() {
 }
 
 void CefBrowserContext::Initialize() {
+  CefContext* context = CefContext::Get();
+
   cache_path_ = base::FilePath(CefString(&settings_.cache_path));
-  if (!cache_path_.empty()) {
-    base::ThreadRestrictions::ScopedAllowIO allow_io;
-    if (!base::DirectoryExists(cache_path_) &&
-        !base::CreateDirectory(cache_path_)) {
-      LOG(ERROR) << "The cache_path directory could not be created: "
-                 << cache_path_.value();
-      cache_path_ = base::FilePath();
-      CefString(&settings_.cache_path).clear();
-    }
+  if (!context->ValidateCachePath(cache_path_)) {
+    // Reset to in-memory storage.
+    CefString(&settings_.cache_path).clear();
+    cache_path_ = base::FilePath();
   }
 
   if (!cache_path_.empty())
@@ -278,7 +274,7 @@ void CefBrowserContext::Initialize() {
   if (settings_.accept_language_list.length == 0) {
     // Use the global language list setting.
     CefString(&settings_.accept_language_list) =
-        CefString(&CefContext::Get()->settings().accept_language_list);
+        CefString(&context->settings().accept_language_list);
   }
 
   // Initialize the PrefService object.

libcef/browser/chrome_browser_process_stub.cc

@@ -7,6 +7,7 @@
 
 #include "libcef/browser/browser_context.h"
 #include "libcef/browser/chrome_profile_manager_stub.h"
+#include "libcef/browser/context.h"
 #include "libcef/browser/prefs/browser_prefs.h"
 #include "libcef/browser/thread_util.h"
 #include "libcef/common/cef_switches.h"
@@ -39,11 +40,13 @@ void ChromeBrowserProcessStub::Initialize() {
   DCHECK(!context_initialized_);
   DCHECK(!shutdown_);
 
+  const CefSettings& settings = CefContext::Get()->settings();
+  const base::FilePath& cache_path =
+      base::FilePath(CefString(&settings.cache_path));
+
   // Used for very early NetworkService initialization.
-  // TODO(cef): These preferences could be persisted in the DIR_USER_DATA
-  // directory.
-  local_state_ =
-      browser_prefs::CreatePrefService(nullptr, base::FilePath(), false);
+  local_state_ = browser_prefs::CreatePrefService(
+      nullptr, cache_path, !!settings.persist_user_preferences);
 
   initialized_ = true;
 }

libcef/browser/content_browser_client.cc

@@ -49,6 +49,7 @@
 #include "base/json/json_reader.h"
 #include "base/path_service.h"
 #include "base/stl_util.h"
+#include "base/threading/thread_restrictions.h"
 #include "cef/grit/cef_resources.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_service.h"
@@ -57,7 +58,6 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/renderer_host/pepper/chrome_browser_pepper_host_factory.h"
 #include "chrome/common/chrome_paths.h"
-#include "chrome/common/chrome_paths_internal.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/constants.mojom.h"
 #include "chrome/grit/browser_resources.h"
@@ -1200,6 +1200,11 @@ void CefContentBrowserClient::OnNetworkServiceCreated(
   DCHECK(local_state);
 
   if (!SystemNetworkContextManager::GetInstance()) {
+    // TODO(network): This triggers creation of ChromeBrowserPolicyConnector via
+    // ChromeBrowserProcessStub::policy_service() which loads some system DLLs
+    // on Windows. Determine the correct initialization timing to avoid the need
+    // for ScopedAllowIO here.
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
     SystemNetworkContextManager::CreateInstance(local_state);
   }
   // Need to set up global NetworkService state before anything else uses it.
@@ -1215,24 +1220,26 @@ network::mojom::NetworkContextPtr CefContentBrowserClient::CreateNetworkContext(
   return profile->CreateNetworkContext(in_memory, relative_partition_path);
 }
 
+// The sandbox may block read/write access from the NetworkService to
+// directories that are not returned by this method.
 std::vector<base::FilePath>
 CefContentBrowserClient::GetNetworkContextsParentDirectory() {
-  base::FilePath user_data_dir;
-  base::PathService::Get(chrome::DIR_USER_DATA, &user_data_dir);
-  DCHECK(!user_data_dir.empty());
+  base::FilePath user_data_path;
+  base::PathService::Get(chrome::DIR_USER_DATA, &user_data_path);
+  DCHECK(!user_data_path.empty());
 
-  // TODO(cef): Do we really want to create a cache directory underneath
-  // DIR_USER_DATA?
-  base::FilePath cache_dir;
-  chrome::GetUserCacheDirectory(user_data_dir, &cache_dir);
-  DCHECK(!cache_dir.empty());
+  // The CefContext::ValidateCachePath method enforces the requirement that all
+  // cache_path values be either equal to or a child of root_cache_path.
+  const base::FilePath& root_cache_path =
+      base::FilePath(CefString(&CefContext::Get()->settings().root_cache_path));
 
-  // On some platforms, the cache is a child of the user_data_dir so only
-  // return the one path.
-  if (user_data_dir.IsParent(cache_dir))
-    return {user_data_dir};
+  // root_cache_path may sometimes be empty or a child of user_data_path, so
+  // only return the one path in that case.
+  if (root_cache_path.empty() || user_data_path.IsParent(root_cache_path)) {
+    return {user_data_path};
+  }
 
-  return {user_data_dir, cache_dir};
+  return {user_data_path, root_cache_path};
 }
 
 bool CefContentBrowserClient::HandleExternalProtocol(

libcef/browser/context.cc

@@ -22,6 +22,7 @@
 #include "base/files/file_util.h"
 #include "base/run_loop.h"
 #include "base/synchronization/waitable_event.h"
+#include "base/threading/thread_restrictions.h"
 #include "components/network_session_configurator/common/network_switches.h"
 #include "content/app/content_service_manager_main_delegate.h"
 #include "content/browser/startup_helper.h"
@@ -370,6 +371,18 @@ bool CefContext::Initialize(const CefMainArgs& args,
   SignalChromeElf();
 #endif
 
+  base::FilePath cache_path = base::FilePath(CefString(&settings_.cache_path));
+  if (!ValidateCachePath(cache_path)) {
+    // Reset to in-memory storage.
+    CefString(&settings_.cache_path).clear();
+    cache_path = base::FilePath();
+  }
+  const base::FilePath& root_cache_path =
+      base::FilePath(CefString(&settings_.root_cache_path));
+  if (root_cache_path.empty() && !cache_path.empty()) {
+    CefString(&settings_.root_cache_path) = CefString(&settings_.cache_path);
+  }
+
   main_delegate_.reset(new CefMainDelegate(application));
   browser_info_manager_.reset(new CefBrowserInfoManager);
 
@@ -533,6 +546,31 @@ void CefContext::PopulateRequestContextSettings(
       CefString(&settings_.accept_language_list);
 }
 
+bool CefContext::ValidateCachePath(const base::FilePath& cache_path) {
+  if (cache_path.empty())
+    return true;
+
+  const base::FilePath& root_cache_path =
+      base::FilePath(CefString(&settings_.root_cache_path));
+  if (!root_cache_path.empty() && root_cache_path != cache_path &&
+      !root_cache_path.IsParent(cache_path)) {
+    LOG(ERROR) << "The cache_path directory (" << cache_path.value()
+               << ") is not a child of the root_cache_path directory ("
+               << root_cache_path.value() << ")";
+    return false;
+  }
+
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
+  if (!base::DirectoryExists(cache_path) &&
+      !base::CreateDirectory(cache_path)) {
+    LOG(ERROR) << "The cache_path directory (" << cache_path.value()
+               << ") could not be created.";
+    return false;
+  }
+
+  return true;
+}
+
 void CefContext::OnContextInitialized() {
   CEF_REQUIRE_UIT();
 

libcef/browser/context.h

@@ -73,10 +73,13 @@ class CefContext {
 
   CefTraceSubscriber* GetTraceSubscriber();
 
-  // Populate the request context settings based on CefSettings and command-
-  // line flags.
+  // Populate request context settings for the global system context based on
+  // CefSettings and command-line flags.
   void PopulateRequestContextSettings(CefRequestContextSettings* settings);
 
+  // Verify that |cache_path| is valid and create it if necessary.
+  bool ValidateCachePath(const base::FilePath& cache_path);
+
  private:
   void OnContextInitialized();
 

libcef/browser/prefs/browser_prefs.cc

@@ -193,6 +193,12 @@ std::unique_ptr<PrefService> CreatePrefService(Profile* profile,
     // Based on ProfileImpl::RegisterProfilePrefs.
     registry->RegisterBooleanPref(prefs::kPrintingEnabled, true);
 
+    // Cache preferences.
+    // Based on ProfileImpl::RegisterProfilePrefs.
+    registry->RegisterFilePathPref(prefs::kDiskCacheDir, cache_path);
+    registry->RegisterIntegerPref(prefs::kDiskCacheSize, 0);
+    registry->RegisterIntegerPref(prefs::kMediaCacheSize, 0);
+
     // Spell checking preferences.
     // Modify defaults from SpellcheckServiceFactory::RegisterProfilePrefs.
     std::string spellcheck_lang =