OK, eu fiz isso usando as duas opções a seguir em vsftpd.conf
file:
chroot_local_user=YES
passwd_chroot_enable=YES
passwd_chroot_enable If enabled, along with chroot_local_user , then a chroot() jail location may be specified on a per-user basis. Each user's jail is derived from their home directory string in /etc/passwd. The occurrence of /./ in the home directory string denotes that the jail is at that particular location in the path.