mod_suexec ignored by php

Question

I set up a virtual host that uses mod_suexec to run PHP scripts as a different user than www-data.

<VirtualHost *:80>
    ServerName my.server.com
    DocumentRoot /srv/my-site
    SuexecUserGroup webconfig webconfig
</VirtualHost>

However, when I create a directory or a file (mkdir, file_put_contents), those files/dirs have www-data as an owner. I also can not read files that are only readable by webconfig.

I also noticed this strange behaviour: This php file:

echo get_current_user()."\n";
echo `whoami`."\n";
echo exec('whoami')."\n";

produces the following output:

webconfig
www-data
www-data

Answer 1

mod_php5 is actually incompatible with mod_suexec. As described in this article, you have to use mod_suphp and php-cgi instead. The downside is that this decreases performance.

A simple solution that works for Ubuntu is

apt-get install -y suphp-common, libapache2-mod-suphp
a2dismod php5
a2enmod suphp

The linked article describes how to use mod_php5 for some vhosts and mod_suphp for others.