Add preference to allow the loading of FTP subresources for corner cases

dom/security/nsContentSecurityManager.cpp

@@ -98,6 +98,9 @@ nsContentSecurityManager::CheckFTPSubresourceLoad(nsIChannel* aChannel)
   // We dissallow using FTP resources as a subresource everywhere.
   // The only valid way to use FTP resources is loading it as
   // a top level document.
+  if (!mozilla::net::nsIOService::BlockFTPSubresources()) {
+    return NS_OK;
+  }
 
   nsCOMPtr<nsILoadInfo> loadInfo = aChannel->GetLoadInfo();
   if (!loadInfo) {

modules/libpref/init/all.js

@@ -5448,6 +5448,9 @@ pref("layout.css.servo.enabled", true);
 // URL-Bar will not be blocked when flipping this pref.
 pref("security.data_uri.block_toplevel_data_uri_navigations", true);
 
+// If true, all FTP subresource loads will be blocked.
+pref("security.block_ftp_subresources", true);
+
 // Disable Storage api in release builds.
 #ifdef NIGHTLY_BUILD
 pref("dom.storageManager.enabled", true);

netwerk/base/nsIOService.cpp

@@ -166,6 +166,7 @@ uint32_t   nsIOService::gDefaultSegmentSize = 4096;
 uint32_t   nsIOService::gDefaultSegmentCount = 24;
 
 bool nsIOService::sBlockToplevelDataUriNavigations = false;
+bool nsIOService::sBlockFTPSubresources = false;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -243,6 +244,8 @@ nsIOService::Init()
 
     Preferences::AddBoolVarCache(&sBlockToplevelDataUriNavigations,
                                  "security.data_uri.block_toplevel_data_uri_navigations", false);
+    Preferences::AddBoolVarCache(&sBlockFTPSubresources,
+                                 "security.block_ftp_subresources", true);
     Preferences::AddBoolVarCache(&mOfflineMirrorsConnectivity, OFFLINE_MIRRORS_CONNECTIVITY, true);
 
     gIOService = this;
@@ -1869,5 +1872,11 @@ nsIOService::BlockToplevelDataUriNavigations()
   return sBlockToplevelDataUriNavigations;
 }
 
+/*static*/ bool
+nsIOService::BlockFTPSubresources()
+{
+  return sBlockFTPSubresources;
+}
+
 } // namespace net
 } // namespace mozilla

netwerk/base/nsIOService.h

@@ -94,6 +94,8 @@ public:
 
     static bool BlockToplevelDataUriNavigations();
 
+    static bool BlockFTPSubresources();
+
     // Used to trigger a recheck of the captive portal status
     nsresult RecheckCaptivePortal();
 private:
@@ -175,6 +177,8 @@ private:
 
     static bool                          sBlockToplevelDataUriNavigations;
 
+    static bool                          sBlockFTPSubresources;
+
     // Time a network tearing down started.
     mozilla::Atomic<PRIntervalTime> mNetTearingDownStarted;
 public: