how to keep file ownership while using tar
You want to "preserve" file attributes while doing tar -x with the -p switch. Obviously you need to be root for this to to have the desired result.
-p, --insecure, --preserve-permissions (x mode only) Preserve file permissions. Attempt to restore the full permissions, including owner, file modes, file flags and ACLs, if available,Many POSIX systems also ship pax, cpio that can work as alternatives to tar.