vsftpd: pam_userdb permission denied

I've been trying to set up VSFTPD on Centos 6.6 to allow virtual users. Below is my vsftpd.conf, which is configured to allow only virtual users in /etc/vsftpd/vsftpd-virtual-user.db. listen=YES local_umask=002 anonymous_enable=NO local_enable=YES virtual_use_local_privs=YES write_enable=YES pam_service_name=vsftpd_virtual guest_enable=YES local_root=/var/sites chroot_local_user=YES hide_ids=YES connect_from_port_20=YES pasv_enable=YES pasv_addr_resolve=YES pasv_address=10.175.9.23 pasv_min_port=1024 pasv_max_port=65535 I have also set up the vsftpd_virtual module in /etc/pam.d/vsftpd_virtual which contains the following: #%PAM-1.0 auth required pam_userdb.so db=/etc/vsftpd/vsftpd-virtual-user account required pam_userdb.so db=/etc/vsftpd/vsftpd-virtual-user session required pam_loginuid.so When trying to log in to FTP on localhost, I'm getting a 530 error from FTP and the following line in /var/log/secure: vsftpd: pam_userdb(vsftpd_virtual:auth): user_lookup: could not open database `/etc/vsftpd/vsftpd-virtual-user': Permission denied The file permissions for the database file seem fine, but I may be wrong: Access: (0777/-rwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root)