PPB_Flash.Navigate(): Disallow certain HTTP request headers.

chrome/renderer/pepper/pepper_flash_renderer_host.cc

 // Copyright (c) 2012 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/pepper/pepper_flash_renderer_host.h"
 
+#include <map>
 #include <vector>
 
+#include "base/lazy_instance.h"
+#include "base/metrics/histogram.h"
+#include "base/strings/string_util.h"
 #include "chrome/renderer/pepper/ppb_pdf_impl.h"
 #include "content/public/renderer/pepper_plugin_instance.h"
 #include "content/public/renderer/render_thread.h"
 #include "content/public/renderer/renderer_ppapi_host.h"
 #include "ipc/ipc_message_macros.h"
+#include "net/http/http_util.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/trusted/ppb_browser_font_trusted.h"
 #include "ppapi/host/dispatch_host_message.h"
 #include "ppapi/proxy/host_dispatcher.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/resource_message_params.h"
 #include "ppapi/proxy/serialized_structs.h"
 #include "ppapi/thunk/enter.h"
 #include "ppapi/thunk/ppb_image_data_api.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/core/SkPoint.h"
 #include "third_party/skia/include/core/SkTemplates.h"
 #include "third_party/skia/include/core/SkTypeface.h"
 #include "ui/gfx/rect.h"
 #include "url/gurl.h"
 
 using ppapi::thunk::EnterResourceNoLock;
 using ppapi::thunk::PPB_ImageData_API;
 
+namespace {
+
+// Some non-simple HTTP request headers that Flash may set.
+// (Please see http://www.w3.org/TR/cors/#simple-header for the definition of
+// simple headers.)
+//
+// The list and the enum defined below are used to collect data about request
+// headers used in PPB_Flash.Navigate() calls, in order to understand the impact
+// of rejecting PPB_Flash.Navigate() requests with non-simple headers.

[Alexei Svitkine (slow), 2014/01/30 20:23:31]

Can you expand the comment to mention that new entries should be added to the
end and existing entries shouldn't be re-ordered or removed, since this ordering
is used in a histogram?

[yzshen1, 2014/01/31 18:14:12]

Done.

+//
+// TODO(yzshen): We should be able to remove the histogram recording code once
+// we get the answer.
+const char* kRejectedHttpRequestHeaders[] = {
+  "authorization",
+  "cache-control",
+  "content-encoding",
+  "content-md5",
+  "content-type",  // If the media type is not one of those covered by the
+                   // simple header definition.
+  "expires",
+  "from",
+  "if-match",
+  "if-none-match",
+  "if-range",
+  "if-unmodified-since",
+  "pragma",
+  "referer"
+};
+
+enum FlashNavigateUsage {
+  // This section must be in the same order as kRejectedHttpRequestHeaders.
+  REJECT_AUTHORIZATION = 0,
+  REJECT_CACHE_CONTROL,
+  REJECT_CONTENT_ENCODING,
+  REJECT_CONTENT_MD5,
+  REJECT_CONTENT_TYPE,
+  REJECT_EXPIRES,
+  REJECT_FROM,
+  REJECT_IF_MATCH,
+  REJECT_IF_NONE_MATCH,
+  REJECT_IF_RANGE,
+  REJECT_IF_UNMODIFIED_SINCE,
+  REJECT_PRAGMA,
+  REJECT_REFERER,
+
+  // The navigate request is rejected because of headers not listed above
+  // (e.g., custom headers).
+  REJECT_OTHER_HEADERS,
+
+  // Total number of rejected navigate requests.
+  TOTAL_REJECTED_NAVIGATE_REQUESTS,
+
+  // Total number of navigate requests.
+  TOTAL_NAVIGATE_REQUESTS,
+
+  FLASH_NAVIGATE_USAGE_ENUM_COUNT
+};
+
+static base::LazyInstance<std::map<std::string, FlashNavigateUsage> >
+    g_rejected_headers = LAZY_INSTANCE_INITIALIZER;
+
+bool IsSimpleHeader(const std::string& lower_case_header_name,
+                    const std::string& header_value) {
+  if (lower_case_header_name == "accept" ||
+      lower_case_header_name == "accept-language" ||
+      lower_case_header_name == "content-language") {
+    return true;
+  }
+
+  if (lower_case_header_name == "content-type") {
+    std::string lower_case_mime_type;
+    std::string lower_case_charset;
+    bool had_charset = false;
+    net::HttpUtil::ParseContentType(header_value, &lower_case_mime_type,
+                                    &lower_case_charset, &had_charset, NULL);
+    return lower_case_mime_type == "application/x-www-form-urlencoded" ||
+           lower_case_mime_type == "multipart/form-data" ||
+           lower_case_mime_type == "text/plain";
+  }
+
+  return false;
+}
+
+}  // namespace
+
 PepperFlashRendererHost::PepperFlashRendererHost(
     content::RendererPpapiHost* host,
     PP_Instance instance,
     PP_Resource resource)
     : ResourceHost(host->GetPpapiHost(), instance, resource),
       host_(host),
       weak_factory_(this) {
 }
 
 PepperFlashRendererHost::~PepperFlashRendererHost() {
@@ skipping 157 matching lines @@
     ppapi::host::HostMessageContext* host_context,
     const ppapi::URLRequestInfoData& data,
     const std::string& target,
     bool from_user_action) {
   // If our PepperPluginInstance is already destroyed, just return a failure.
   content::PepperPluginInstance* plugin_instance =
       host_->GetPluginInstance(pp_instance());
   if (!plugin_instance)
     return PP_ERROR_FAILED;
 
+  std::map<std::string, FlashNavigateUsage>& rejected_headers =
+      g_rejected_headers.Get();
+  if (rejected_headers.empty()) {
+    for (size_t i = 0; i < arraysize(kRejectedHttpRequestHeaders); ++i)
+      rejected_headers[kRejectedHttpRequestHeaders[i]] =
+          static_cast<FlashNavigateUsage>(i);
+  }
+
+  net::HttpUtil::HeadersIterator header_iter(data.headers.begin(),
+                                             data.headers.end(),
+                                             "\n\r");
+  bool rejected = false;
+  while (header_iter.GetNext()) {
+    std::string lower_case_header_name = StringToLowerASCII(header_iter.name());
+    if (!IsSimpleHeader(lower_case_header_name, header_iter.values())) {
+      rejected = true;
+
+      std::map<std::string, FlashNavigateUsage>::const_iterator iter =
+          rejected_headers.find(lower_case_header_name);
+      FlashNavigateUsage usage = iter != rejected_headers.end() ?
+          iter->second : REJECT_OTHER_HEADERS;
+      UMA_HISTOGRAM_ENUMERATION("Plugin.FlashNavigateUsage", usage,

[Alexei Svitkine (slow), 2014/01/30 20:23:31]

Can you make a helper function in the anon namespace that logs this histogram?
It can take |usage| as a param.

(The macro expands to a lot of code, so this will avoid code bloat as well as
possible typos in the name of the histogram since it won't be repeated.)

[yzshen1, 2014/01/31 18:14:12]

Good point! Done.

+                                FLASH_NAVIGATE_USAGE_ENUM_COUNT);
+    }
+  }
+
+  UMA_HISTOGRAM_ENUMERATION("Plugin.FlashNavigateUsage",
+                            TOTAL_NAVIGATE_REQUESTS,
+                            FLASH_NAVIGATE_USAGE_ENUM_COUNT);
+  if (rejected) {
+    UMA_HISTOGRAM_ENUMERATION("Plugin.FlashNavigateUsage",
+                              TOTAL_REJECTED_NAVIGATE_REQUESTS,
+                              FLASH_NAVIGATE_USAGE_ENUM_COUNT);
+    return PP_ERROR_NOACCESS;
+  }
+
   // Navigate may call into Javascript (e.g. with a "javascript:" URL),
   // or do things like navigate away from the page, either one of which will
   // need to re-enter into the plugin. It is safe, because it is essentially
   // equivalent to NPN_GetURL, where Flash would expect re-entrancy.
   ppapi::proxy::HostDispatcher* host_dispatcher =
       ppapi::proxy::HostDispatcher::GetForInstance(pp_instance());
   host_dispatcher->set_allow_plugin_reentrancy();
 
   // Grab a weak pointer to ourselves on the stack so we can check if we are
   // still alive.
@@ skipping 23 matching lines @@
       gfx::Rect(rect.point.x, rect.point.y,rect.size.width, rect.size.height)))
     return PP_OK;
   return PP_ERROR_FAILED;
 }
 
 int32_t PepperFlashRendererHost::OnInvokePrinting(
     ppapi::host::HostMessageContext* host_context) {
   PPB_PDF_Impl::InvokePrintingForInstance(pp_instance());
   return PP_OK;
 }