It doesn't matter what YOU have access to, you have asked the FB server
to create a database in /home/garrett/foo.fdb. It is not running under
your security privilledges (nor root), but rather the user under which
the FB daemon is running.

>
> I'm wondering if the Firebird deamon is trying to create/modify
> something in the background and can't because of file permissions.

This

> is just blind speculation.

Sport on, think of it as you sending a request to the Firebird daemon
and it carrying it out and returning you the result. In this case you
have asked it to create a file and the OS has told it that it isn't
allowed to.