Treat all file: URIs as having a unique origin.

This prevents cross-file access from files loaded into the browser from
the local file system, further restricting the origin policy of file:
URIs.

Added a pref to control this behavior for local file access if required
for certain applications, since this change might break using the
browser to run applications on the local file system that require
access to local files.

1 files changed, 32 insertions, 24 deletions

diff --git a/netwerk/base/nsNetUtil.cpp b/netwerk/base/nsNetUtil.cpp
index 653a9003ee..2974e26b0e 100644
--- a/netwerk/base/nsNetUtil.cpp
+++ b/netwerk/base/nsNetUtil.cpp
@@ -10,6 +10,7 @@
 #include "mozilla/LoadContext.h"
 #include "mozilla/LoadInfo.h"
 #include "mozilla/BasePrincipal.h"
+#include "mozilla/Preferences.h"
 #include "mozilla/Telemetry.h"
 #include "nsNetUtil.h"
 #include "nsNetUtilInlines.h"
@@ -1821,33 +1822,40 @@ NS_RelaxStrictFileOriginPolicy(nsIURI *aTargetURI,
     return false;
   }
 
-  //
-  // If the file to be loaded is in a subdirectory of the source
-  // (or same-dir if source is not a directory) then it will
-  // inherit its source principal and be scriptable by that source.
-  //
-  bool sourceIsDir;
-  bool allowed = false;
-  nsresult rv = sourceFile->IsDirectory(&sourceIsDir);
-  if (NS_SUCCEEDED(rv) && sourceIsDir) {
-    rv = sourceFile->Contains(targetFile, &allowed);
-  } else {
-    nsCOMPtr<nsIFile> sourceParent;
-    rv = sourceFile->GetParent(getter_AddRefs(sourceParent));
-    if (NS_SUCCEEDED(rv) && sourceParent) {
-      rv = sourceParent->Equals(targetFile, &allowed);
-      if (NS_FAILED(rv) || !allowed) {
-        rv = sourceParent->Contains(targetFile, &allowed);
-      } else {
-        MOZ_ASSERT(aAllowDirectoryTarget,
-                   "sourceFile->Parent == targetFile, but targetFile "
-                   "should've been disallowed if it is a directory");
+  bool uniqueOrigin = true;
+  uniqueOrigin = Preferences::GetBool("security.fileuri.unique_origin");
+  
+  // If treating all files as unique origins, we can skip this because
+  // it should always be refused.
+  if (!uniqueOrigin) {
+    //
+    // If the file to be loaded is in a subdirectory of the source
+    // (or same-dir if source is not a directory) then it will
+    // inherit its source principal and be scriptable by that source.
+    //
+    bool sourceIsDir;
+    bool allowed = false;
+    nsresult rv = sourceFile->IsDirectory(&sourceIsDir);
+    if (NS_SUCCEEDED(rv) && sourceIsDir) {
+      rv = sourceFile->Contains(targetFile, &allowed);
+    } else {
+      nsCOMPtr<nsIFile> sourceParent;
+      rv = sourceFile->GetParent(getter_AddRefs(sourceParent));
+      if (NS_SUCCEEDED(rv) && sourceParent) {
+        rv = sourceParent->Equals(targetFile, &allowed);
+        if (NS_FAILED(rv) || !allowed) {
+          rv = sourceParent->Contains(targetFile, &allowed);
+        } else {
+          MOZ_ASSERT(aAllowDirectoryTarget,
+                     "sourceFile->Parent == targetFile, but targetFile "
+                     "should've been disallowed if it is a directory");
+        }
       }
     }
-  }
 
-  if (NS_SUCCEEDED(rv) && allowed) {
-    return true;
+    if (NS_SUCCEEDED(rv) && allowed) {
+      return true;
+    }
   }
 
   return false;