Execution Time & Memory Limit [virtualmin]

i’m using virtualmin with CGI server API for all my virtualmin virtual servers.

i’m using a default php.ini for all my virtual server users that i put in /home/php.ini, so when i create a new virtual server that php.ini becomes the php.ini for /home/virtualuser/etc/php5/php.ini that the user can modify for alter php values for its virtual server.

so i need to block certain php variables for all virtual users to certain values:

max execution time and memory limit, i need that users can modify that values but cannot raise them over a certain value i dedice.

user raise its max execution time to 300 or memory limit to 128MB but he can’t raise them over this values.

any suggestion?

i think this is possible with virtualmin where is the menu on webmin control panel to do this?