This post explains how to limit users to only their home directory in vsftpd ftp demon so that the users will be in a jail environment and he can not change to other directories.
Open the vstpd configuration file
Add the following variable
Restart the vsftpd service
Now on wards when the user logs in via ftp he gets into his home directory. But he cannot change the directory out of it. This is known as jailed environment.