php脚本process.php由表单提交调用，跨域php脚本common.php包含在process.php中。我得到了以下错误。
Warning: require_once(/home/m64/public_html/hosting/example.com/libs/common.php) [function.require-once]: failed to open stream: Permission denied in /home/example_b.com/public_html/m/process.php on line 13
Fatal error: require_once() [function.require]: Failed opening required '/home/m64/public_html/hosting/example.com/libs/common.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/example_b.com/public_html/m/process.php on line 13
example.com和example_b.com是不同的域，但在同一台服务器上。这两个域都在分离的cPanel帐户上。我对cPanel都有完全的访问控制权。如何为每个域授予文件访问权限？