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      1 // Copyright (c) 2012 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/renderer/extensions/resource_request_policy.h"
      6 
      7 #include "base/command_line.h"
      8 #include "base/logging.h"
      9 #include "base/strings/stringprintf.h"
     10 #include "chrome/common/chrome_switches.h"
     11 #include "chrome/common/extensions/extension_set.h"
     12 #include "chrome/common/extensions/manifest_handlers/icons_handler.h"
     13 #include "chrome/common/extensions/manifest_url_handler.h"
     14 #include "chrome/common/extensions/web_accessible_resources_handler.h"
     15 #include "chrome/common/url_constants.h"
     16 #include "content/public/common/page_transition_types.h"
     17 #include "extensions/common/constants.h"
     18 #include "extensions/common/extension.h"
     19 #include "third_party/WebKit/public/platform/WebString.h"
     20 #include "third_party/WebKit/public/web/WebConsoleMessage.h"
     21 #include "third_party/WebKit/public/web/WebDocument.h"
     22 #include "third_party/WebKit/public/web/WebFrame.h"
     23 #include "url/gurl.h"
     24 
     25 namespace extensions {
     26 
     27 // This method does a security check whether chrome-extension:// URLs can be
     28 // requested by the renderer. Since this is in an untrusted process, the browser
     29 // has a similar check to enforce the policy, in case this process is exploited.
     30 // If you are changing this function, ensure equivalent checks are added to
     31 // extension_protocols.cc's AllowExtensionResourceLoad.
     32 
     33 // static
     34 bool ResourceRequestPolicy::CanRequestResource(
     35     const GURL& resource_url,
     36     blink::WebFrame* frame,
     37     content::PageTransition transition_type,
     38     const ExtensionSet* loaded_extensions) {
     39   CHECK(resource_url.SchemeIs(extensions::kExtensionScheme));
     40 
     41   const Extension* extension =
     42       loaded_extensions->GetExtensionOrAppByURL(resource_url);
     43   if (!extension) {
     44     // Allow the load in the case of a non-existent extension. We'll just get a
     45     // 404 from the browser process.
     46     return true;
     47   }
     48 
     49   // Disallow loading of packaged resources for hosted apps. We don't allow
     50   // hybrid hosted/packaged apps. The one exception is access to icons, since
     51   // some extensions want to be able to do things like create their own
     52   // launchers.
     53   std::string resource_root_relative_path =
     54       resource_url.path().empty() ? std::string()
     55                                   : resource_url.path().substr(1);
     56   if (extension->is_hosted_app() &&
     57       !IconsInfo::GetIcons(extension)
     58           .ContainsPath(resource_root_relative_path)) {
     59     LOG(ERROR) << "Denying load of " << resource_url.spec() << " from "
     60                << "hosted app.";
     61     return false;
     62   }
     63 
     64   // Disallow loading of extension resources which are not explicitly listed
     65   // as web accessible if the manifest version is 2 or greater.
     66   if (!WebAccessibleResourcesInfo::IsResourceWebAccessible(
     67           extension, resource_url.path()) &&
     68       !CommandLine::ForCurrentProcess()->HasSwitch(
     69           switches::kDisableExtensionsResourceWhitelist)) {
     70     GURL frame_url = frame->document().url();
     71     GURL page_url = frame->top()->document().url();
     72 
     73     // Exceptions are:
     74     // - empty origin (needed for some edge cases when we have empty origins)
     75     bool is_empty_origin = frame_url.is_empty();
     76     // - extensions requesting their own resources (frame_url check is for
     77     //     images, page_url check is for iframes)
     78     bool is_own_resource = frame_url.GetOrigin() == extension->url() ||
     79         page_url.GetOrigin() == extension->url();
     80     // - devtools (chrome-extension:// URLs are loaded into frames of devtools
     81     //     to support the devtools extension APIs)
     82     bool is_dev_tools = page_url.SchemeIs(chrome::kChromeDevToolsScheme) &&
     83                         !ManifestURL::GetDevToolsPage(extension).is_empty();
     84     bool transition_allowed =
     85         !content::PageTransitionIsWebTriggerable(transition_type);
     86     // - unreachable web page error page (to allow showing the icon of the
     87     //   unreachable app on this page)
     88     bool is_error_page = frame_url == GURL(content::kUnreachableWebDataURL);
     89 
     90     if (!is_empty_origin && !is_own_resource &&
     91         !is_dev_tools && !transition_allowed && !is_error_page) {
     92       std::string message = base::StringPrintf(
     93           "Denying load of %s. Resources must be listed in the "
     94           "web_accessible_resources manifest key in order to be loaded by "
     95           "pages outside the extension.",
     96           resource_url.spec().c_str());
     97       frame->addMessageToConsole(
     98           blink::WebConsoleMessage(blink::WebConsoleMessage::LevelError,
     99                                     blink::WebString::fromUTF8(message)));
    100       return false;
    101     }
    102   }
    103 
    104   return true;
    105 }
    106 
    107 // static
    108 bool ResourceRequestPolicy::CanRequestExtensionResourceScheme(
    109     const GURL& resource_url,
    110     blink::WebFrame* frame) {
    111   CHECK(resource_url.SchemeIs(chrome::kExtensionResourceScheme));
    112 
    113   GURL frame_url = frame->document().url();
    114   if (!frame_url.is_empty() &&
    115       !frame_url.SchemeIs(extensions::kExtensionScheme)) {
    116     std::string message = base::StringPrintf(
    117         "Denying load of %s. chrome-extension-resources:// can only be "
    118         "loaded from extensions.",
    119       resource_url.spec().c_str());
    120     frame->addMessageToConsole(
    121         blink::WebConsoleMessage(blink::WebConsoleMessage::LevelError,
    122                                   blink::WebString::fromUTF8(message)));
    123     return false;
    124   }
    125 
    126   return true;
    127 }
    128 
    129 ResourceRequestPolicy::ResourceRequestPolicy() {
    130 }
    131 
    132 }  // namespace extensions
    133