Use WebFrame::setIsolatedWorldSecurityOrigin to allow cross-origin XHRs in content scripts.

chrome/renderer/extensions/user_script_slave.cc

 // Copyright (c) 2011 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/renderer/extensions/user_script_slave.h"
 
 #include <map>
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/perftimer.h"
 #include "base/pickle.h"
 #include "base/shared_memory.h"
 #include "base/metrics/histogram.h"
 #include "base/stringprintf.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_set.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/renderer/chrome_render_process_observer.h"
+#include "chrome/renderer/extensions/extension_dispatcher.h"
 #include "chrome/renderer/extensions/extension_groups.h"
 #include "googleurl/src/gurl.h"
 #include "grit/renderer_resources.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebSecurityOrigin.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebSecurityPolicy.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebVector.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
 #include "ui/base/resource/resource_bundle.h"
 
 using WebKit::WebFrame;
+using WebKit::WebSecurityOrigin;
+using WebKit::WebSecurityPolicy;
 using WebKit::WebString;
 using WebKit::WebVector;
 using WebKit::WebView;
 
 // These two strings are injected before and after the Greasemonkey API and
 // user script to wrap it in an anonymous scope.
 static const char kUserScriptHead[] = "(function (unsafeWindow) {\n";
 static const char kUserScriptTail[] = "\n})(window);";
 
 // Sets up the chrome.extension module. This may be run multiple times per
 // context, but the init method deletes itself after the first time.
 static const char kInitExtension[] =
   "if (chrome.initExtension) chrome.initExtension('%s', true, %s);";
 
+// static
+UserScriptSlave::IsolatedWorldMap UserScriptSlave::isolated_world_ids_;
 
-int UserScriptSlave::GetIsolatedWorldId(const std::string& extension_id) {
-  typedef std::map<std::string, int> IsolatedWorldMap;
-
-  static IsolatedWorldMap g_isolated_world_ids;
+// static
+int UserScriptSlave::GetIsolatedWorldId(
+    const Extension* extension, WebFrame* frame) {
   static int g_next_isolated_world_id = 1;
 
-  IsolatedWorldMap::iterator iter = g_isolated_world_ids.find(extension_id);
-  if (iter != g_isolated_world_ids.end())
+  IsolatedWorldMap::iterator iter = isolated_world_ids_.find(extension->id());
+  if (iter != isolated_world_ids_.end()) {
+    // We need to set the isolated world origin even if it's not a new world
+    // since that is stored per frame, and we might not have used this isolated
+    // world in this frame before.
+    frame->setIsolatedWorldSecurityOrigin(
+        iter->second,
+        WebSecurityOrigin::create(extension->url()));
     return iter->second;
+  }
 
   int new_id = g_next_isolated_world_id;
   ++g_next_isolated_world_id;
 
   // This map will tend to pile up over time, but realistically, you're never
   // going to have enough extensions for it to matter.
-  g_isolated_world_ids[extension_id] = new_id;
+  isolated_world_ids_[extension->id()] = new_id;
+  InitializeIsolatedWorld(new_id, extension);
+  frame->setIsolatedWorldSecurityOrigin(
+      new_id,
+      WebSecurityOrigin::create(extension->url()));
   return new_id;
 }
 
+// static
+void UserScriptSlave::InitializeIsolatedWorld(
+    int isolated_world_id,
+    const Extension* extension) {
+  const URLPatternList& permissions =
+      extension->GetEffectiveHostPermissions().patterns();

[Aaron Boodman, 2011/05/29 04:44:09]

Sorry for butting in, but it seems unexpected to me that content_scripts.urls
has the side-effect of allowing cross-origin XHR. Why is that easier to
implement? Couldn't this line just check host_permissions() instead?

[Matt Perry, 2011/05/31 18:13:32]

I advocated doing this for 2 main reasons:
1. From a security perspective, being able to inject script is the same as being
able to issue cross-origin XHR to a host.
2. We have to allow XHR to the origin of the content script's frame. Since the
extension's isolated world has a shared security context, this means it really
has cross-origin access to (host_permissions + all frame origins that this
extension has a content script running on). Given that oddity, it seemed more
reasonable to just allow access to all content_script.urls at all times.

Erik, Mihai, and I were trying to remember why you didn't want cross-origin XHR
to content script URLs. Could you explain the reasoning? It seems to me that
requesting access to a host should be universal, regardless of where you request
it.

+  for (size_t i = 0; i < permissions.size(); ++i) {
+    const char* schemes[] = {
+      chrome::kHttpScheme,
+      chrome::kHttpsScheme,
+      chrome::kFileScheme,
+      chrome::kChromeUIScheme,
+    };
+    for (size_t j = 0; j < arraysize(schemes); ++j) {
+      if (permissions[i].MatchesScheme(schemes[j])) {
+        WebSecurityPolicy::addOriginAccessWhitelistEntry(
+            extension->url(),
+            WebString::fromUTF8(schemes[j]),
+            WebString::fromUTF8(permissions[i].host()),
+            permissions[i].match_subdomains());
+      }
+    }
+  }
+}
+
+// static
+void UserScriptSlave::RemoveIsolatedWorld(const std::string& extension_id) {
+  isolated_world_ids_.erase(extension_id);
+}
+
 UserScriptSlave::UserScriptSlave(const ExtensionSet* extensions)
     : shared_memory_(NULL),
       script_deleter_(&scripts_),
       extensions_(extensions) {
   api_js_ = ResourceBundle::GetSharedInstance().GetRawDataResource(
                 IDR_GREASEMONKEY_API_JS);
 }
 
 UserScriptSlave::~UserScriptSlave() {}
 
@@ skipping 168 matching lines @@
       // and "standalone" user scripts.
       if (script->is_standalone() || script->emulate_greasemonkey()) {
         sources.insert(sources.begin(),
             WebScriptSource(WebString::fromUTF8(api_js_.as_string())));
       }
 
       // Setup chrome.self to contain an Extension object with the correct
       // ID.
       if (!script->extension_id().empty()) {
         InsertInitExtensionCode(&sources, script->extension_id());
-        isolated_world_id = GetIsolatedWorldId(script->extension_id());
+        isolated_world_id = GetIsolatedWorldId(extension, frame);
       }
 
       PerfTimer exec_timer;
       frame->executeScriptInIsolatedWorld(
           isolated_world_id, &sources.front(), sources.size(),
           EXTENSION_GROUP_CONTENT_SCRIPTS);
       UMA_HISTOGRAM_TIMES("Extensions.InjectScriptTime", exec_timer.Elapsed());
     }
   }
 
   // Log debug info.
   if (location == UserScript::DOCUMENT_START) {
     UMA_HISTOGRAM_COUNTS_100("Extensions.InjectStart_CssCount", num_css);
     UMA_HISTOGRAM_COUNTS_100("Extensions.InjectStart_ScriptCount", num_scripts);
     if (num_css || num_scripts)
       UMA_HISTOGRAM_TIMES("Extensions.InjectStart_Time", timer.Elapsed());
   } else if (location == UserScript::DOCUMENT_END) {
     UMA_HISTOGRAM_COUNTS_100("Extensions.InjectEnd_ScriptCount", num_scripts);
     if (num_scripts)
       UMA_HISTOGRAM_TIMES("Extensions.InjectEnd_Time", timer.Elapsed());
   } else if (location == UserScript::DOCUMENT_IDLE) {
     UMA_HISTOGRAM_COUNTS_100("Extensions.InjectIdle_ScriptCount", num_scripts);
     if (num_scripts)
       UMA_HISTOGRAM_TIMES("Extensions.InjectIdle_Time", timer.Elapsed());
   } else {
     NOTREACHED();
   }
 }