Chroot php-fpm process to user’s home

I'm in the process of moving each of my websites that are on a single server from a single PHP instance (whereby all of the files in all websites were owned by apache, and just the default php library was installed without php-fpm) … and I'm installing a php-fpm pool for each individual website.

Better security and separation of the websites is my goal, the biggest goal being that the PHP scripts in 1 website won't be able to access PHP scripts from another website.

I'm apparently doing something wrong.

My environment:

• CentOS 7
• PHP 5.4.16
• Apache 2.4.6

Here's an example php-fpm pool config file:

[root@host]# cat /etc/php-fpm.d/website1.com.conf 
    [website1.com]
    user = user1
    group = user1
    listen = /var/run/php-fpm/website1.com.sock
    listen.owner = user1
    listen.group = user1
    php_admin_value[disable_functions] = exec,passthru,shell_exec,system
    php_admin_flag[allow_url_fopen] = on
    php_admin_value[short_open_tag] = On
    pm = ondemand
    pm.max_children = 5
    pm.start_servers = 2
    pm.min_spare_servers = 1
    pm.max_spare_servers = 3
    chdir = /home/www/website1.com/

And here is its corresponding vhost file in Apache:

[root@host]# cat /etc/httpd/conf.d/website1.com.conf 
        <VirtualHost *:80>
                ServerAdmin admin@my-host.com
                ServerName website1.com
        ServerAlias www.website1.com
        DocumentRoot /home/www/website1.com/www
                <Directory "/home/www/website1.com/www">
                        Options Includes FollowSymLinks
                        AllowOverride All
                        Order allow,deny
                        Allow from all
                </Directory>
        ErrorLog /home/www/website1.com/logs/errors
        CustomLog /home/www/website1.com/logs/access_log common
                <FilesMatch "\.php$">
                        SetHandler "proxy:unix:///var/run/php-fpm/website1.com.sock|fcgi://website1.com/"
                </FilesMatch>

        </VirtualHost>

All files and folders are owned solely by user1 (the group is also set to user1).

I have a PHP script inside of "website2" that is still able to access "website1" content. The settings in the php-fpm pool config file for "website2" and the settings in "website2" Apache vhost config file are identical to website 1 (with the exception of different folder paths, home directory, chroot, etc…).

This is my test script, located in /home/www/website2/www/ and accessible via the website2.com domain name:

<?php
$test = file_get_contents('/home/www/website1.com/www/wp-config.php');
echo $test;
#$files = scandir('/home/www');
#print_r($files);
?>

The output of this script is somewhat unexpected, however. I don't see the full contents of wp-config.php. Instead, what I see is everything beyond a certain point in the file (if you're familiar with wp-config.php, I see everything after the define('SECURE_AUTH_KEY','foo') entry).

Why can this test script, which is running under "user2" access and echo out some of the contents of wp-config.php found in the "user1" directory? I thought that the chdir = /home/www/website1.com/ directive would prevent this sort of thing.