mod_userdir, PHP + open_basedir

Hello!

I'm administrating an intranet server in a small school. There is about
600 users and they can create their web presentation and save it into
www directory in their home directories.

I use mod_userdir to publish their sites. But I don't want users to
work with files out of their homes (via PHP). I set open_basedir to
".:/tmp" for now, but that is not what I want to do.

-- my configuration --

UserDir www
UserDir disabled root admin

# home directory is here: /home/group-name/user-name
<Directory /home/*/*/www/>
Options Indexes
AllowOverride Indexes
Order deny,allow
Deny from all
Allow from 127.0.0.1 192.168.1.0
php_admin_value open_basedir ".:/tmp"
</Directory>

-- end of my configuration --

It is possible to set open_basedir in accordance to username?

If I use DirectoryMatch instead of Directory, is there any variable
that will contain the name of directory suiting the regular expression
after DirectoryMatch directive?

Or is there any other way, how to do it?

Thx. Sorry for my bad english. (Debian Linux - testing)