Linux (Ubuntu) Prevent User from Renaming Mounted Directory

So, I have a FTP setup on Ubuntu.

They have access to these directories as home:

/home/{user}
/home/{user}

I have directories outside of home:

/var/ftp/shared/legal
/var/ftp/shared/finance

The above are mounted to the users home directory as:

/home/{user}/legal
/home/{user}/finance

My question is, how can I prevent the user from renaming their "legal | finance" directory in their home directory while being able to add directories and files? Would they even be able to do this by default?

Thanks in advance

Solution

I think you can't. The ability of renaming files (or directories) within a directory depends on the permissions the user has over the parent directory, not the file (or directory) to be renamed. Given those subfolders are in the home directories, the users will always be able to rename those subdirectories.