$OpenBSD$

index 1a38477..5a6e05e 100644
--- content/canvas/src/CanvasUtils.cpp.orig	Fri Feb 20 15:40:36 2015
+++ content/canvas/src/CanvasUtils.cpp	Fri Feb 20 15:40:36 2015
@@ -26,9 +26,121 @@
 
 using namespace mozilla::gfx;
 
+#include "nsIScriptObjectPrincipal.h"
+#include "nsIPermissionManager.h"
+#include "nsIObserverService.h"
+#include "mozilla/Services.h"
+#include "mozIThirdPartyUtil.h"
+#include "nsContentUtils.h"
+#include "nsUnicharUtils.h"
+#include "nsPrintfCString.h"
+#include "nsIConsoleService.h"
+#include "jsapi.h"
+
+#define TOPIC_CANVAS_PERMISSIONS_PROMPT "canvas-permissions-prompt"
+#define PERMISSION_CANVAS_EXTRACT_DATA "canvas/extractData"
+
 namespace mozilla {
 namespace CanvasUtils {
 
+// Check site-specific permission and display prompt if appropriate.
+bool IsImageExtractionAllowed(nsIDocument *aDocument, JSContext *aCx)
+{
+  if (!aDocument || !aCx)
+    return false;
+
+  nsPIDOMWindow *win = aDocument->GetWindow();
+  nsCOMPtr<nsIScriptObjectPrincipal> sop(do_QueryInterface(win));
+  if (sop && nsContentUtils::IsSystemPrincipal(sop->GetPrincipal()))
+    return true;
+
+  // Don't show canvas prompt for chrome scripts (e.g. Page Inspector)
+  if (nsContentUtils::IsCallerChrome())
+    return true;
+
+  JS::AutoFilename scriptFile;
+  unsigned scriptLine = 0;
+  bool isScriptKnown = false;
+  if (JS::DescribeScriptedCaller(aCx, &scriptFile, &scriptLine)) {
+    isScriptKnown = true;
+    // Don't show canvas prompt for PDF.js
+    if (scriptFile.get() &&
+        strcmp(scriptFile.get(), "resource://pdf.js/build/pdf.js") == 0)
+      return true;
+  }
+  bool isAllowed = false;
+  nsCOMPtr<mozIThirdPartyUtil> thirdPartyUtil =
+                                do_GetService(THIRDPARTYUTIL_CONTRACTID);
+  nsCOMPtr<nsIPermissionManager> permissionManager =
+                          do_GetService(NS_PERMISSIONMANAGER_CONTRACTID);
+  if (thirdPartyUtil && permissionManager) {
+    nsCOMPtr<nsIURI> uri;
+    nsresult rv = thirdPartyUtil->GetFirstPartyURI(NULL, aDocument,
+                                                   getter_AddRefs(uri));
+    uint32_t permission = nsIPermissionManager::UNKNOWN_ACTION;
+    if (NS_SUCCEEDED(rv)) {
+      // Allow local files to access canvas data; check content permissions
+      // for remote pages.
+      bool isFileURL = false;
+      (void)uri->SchemeIs("file", &isFileURL);
+      if (isFileURL)
+        permission = nsIPermissionManager::ALLOW_ACTION;
+      else {
+        rv = permissionManager->TestPermission(uri,
+                                PERMISSION_CANVAS_EXTRACT_DATA, &permission);
+      }
+    }
+
+    if (NS_SUCCEEDED(rv)) {
+      isAllowed = (permission == nsIPermissionManager::ALLOW_ACTION);
+
+      if (!isAllowed && (permission != nsIPermissionManager::DENY_ACTION)) {
+        // Log all attempted canvas access and block access by third parties.
+        bool isThirdParty = true;
+        nsIURI *docURI = aDocument->GetDocumentURI();
+        rv = thirdPartyUtil->IsThirdPartyURI(uri, docURI, &isThirdParty);
+        NS_ENSURE_SUCCESS(rv, false);
+
+        nsCString firstPartySpec;
+        rv = uri->GetSpec(firstPartySpec);
+        nsCString docSpec;
+        docURI->GetSpec(docSpec);
+        nsPrintfCString msg("On %s: blocked access to canvas image data"
+                            " from document %s, ",  // L10n
+                            firstPartySpec.get(), docSpec.get());
+        if (isScriptKnown && scriptFile.get()) {
+          msg += nsPrintfCString("script from %s:%u",  // L10n
+                                 scriptFile.get(), scriptLine);
+        } else {
+          msg += nsPrintfCString("unknown script");  // L10n
+        }
+        nsCOMPtr<nsIConsoleService> console
+                              (do_GetService(NS_CONSOLESERVICE_CONTRACTID));
+        if (console)
+          console->LogStringMessage(NS_ConvertUTF8toUTF16(msg).get());
+
+        // Log every canvas access attempt to stdout if debugging:
+#ifdef DEBUG
+        printf("%s\n", msg.get());
+#endif
+        // Ensure URI is valid after logging, but before trying to notify the
+        // user:
+        NS_ENSURE_SUCCESS(rv, false);
+
+        if (!isThirdParty) {
+          // Send notification so that a prompt is displayed.
+          nsCOMPtr<nsIObserverService> obs =
+                                       mozilla::services::GetObserverService();
+          obs->NotifyObservers(win, TOPIC_CANVAS_PERMISSIONS_PROMPT,
+                               NS_ConvertUTF8toUTF16(firstPartySpec).get());
+        }
+      }
+    }
+  }
+
+  return isAllowed;
+}
+
 void
 DoDrawImageSecurityCheck(dom::HTMLCanvasElement *aCanvasElement,
                          nsIPrincipal *aPrincipal,