I have a directory named dir1, owned by root, with permissions 777 set. I have a file named file1 inside of dir1, owned by root, with permissions 644 set. I'm logged in as a normal user named user1.

Why is it that if I edit file1 inside vim, which states that it is a readonly file, I can save it via 'wq!'? My expectation is that unless I sudo in, I ought to be denied write access.

I have noticed that following the edit, the ownership of file1 has changed from root to user1. I also noticed, if I change dir1 permission to 775, my expectations are met. That is, I am denied write access.