Comment 14 for bug 823775

The strange thing to me is that before the encrypted home is mounted, $HOME is perm'd 500. So not even the owner should be able to write to it. This is by design to prevent you from accidentally writing cleartext data to your home.

Even though that's the case, the failed lightdm login process creates two files in the unmounted, read-only home:
 1) .dmrc
 2) .Xauthority

This seems to me like lightdm is doing some funny business as root, and then chowning this files back over to the user?