Allow rails users to login via vsftpd

Posted by Jason Noble on 09/02/2008 in FreeBSD, pam, postgres, ruby on rails, vsftpd |

So you’ve installed Ruby on Rails with Postgres, and now you want to allow your users to login to your server via FTP.

First we need to install our FTP server. (In the config window, I left the defaults)

freebsd-vm# cd /usr/ports/ftp/vsftpd
freebsd-vm# make install 
cd /usr/ports/ftp/vsftpd && make config;
[...]
      ports included in the Ports Collection. Please type 'make deinstall'
      to deinstall the port if this is a concern.

      For more information, and contact details about the security
      status of this software, see the following webpage: 
http://vsftpd.beasts.org/
freebsd-vm#

Edit the vsftpd conf file.

#vi /usr/local/etc/vsftpd.conf
# Remove all lines and replace with the following
background=YES
listen=YES
anonymous_enable=NO
local_enable=YES
virtual_use_local_privs=YES
write_enable=YES
connect_from_port_20=YES
secure_chroot_dir=/usr/local/share/vsftpd/empty
pam_service_name=vsftpd
guest_enable=YES
user_sub_token=$USER
local_root=/usr/local/www/apache22/data/$USER
chroot_local_user=YES
hide_ids=YES
ftpd_banner=Welcome to FTP server
file_open_mode=0770
local_umask=0000
anon_mkdir_write_enable=NO
guest_username=vsftpd
user_config_dir=/etc/vsftpd/users

Create the vsftpd startup script.

# vi /usr/local/etc/rc.d/vsftpd
#!/bin/sh
#
# $FreeBSD: ports/ftp/vsftpd/files/vsftpd.sh.in,v 1.7 2006/02/20 20:47:01 dougb Exp $
#

# PROVIDE: vsftpd
# REQUIRE: DAEMON

# Add the following line to /etc/rc.conf to enable `vsftpd':
#
# vsftpd_enable="YES"
# vsftpd_flags="/some/path/conf.file" # Not required
#

. "/etc/rc.subr"

name="vsftpd"
rcvar=`set_rcvar`

load_rc_config "$name"
: ${vsftpd_enable:="NO"}
: ${vsftpd_flags:=""}

command="/usr/local/libexec/$name"
required_files="/usr/local/etc/$name.conf"
start_precmd="vsftpd_check"

vsftpd_check()
{
 if grep -q "^ftp[  ]" /etc/inetd.conf ${required_files}
 then
  err 1 "ftp is already activated in /etc/inetd.conf"
 fi
 if ! egrep -q -i -E "^listen.*=.*YES$" ${required_files}
 then
  err 1 "vsftpd script need "listen=YES" on config file"
 fi
 if ! egrep -q -i -E "^background.*=.*YES$" ${required_files}
 then
  err 1 "vsftpd script need "background=YES" on config file"
 fi
}

run_rc_command "$1"

We also need to install the Postgres PAM module.

freebsd-vm# cd /usr/ports/security/pam-pgsql/
freebsd-vm# make install
=> libpam-pgsql-0.6.3.tar.bz2 doesn't seem to exist in /usr/ports/distfiles/.
=> Attempting to fetch from http://nchc.dl.sourceforge.net/sourceforge/pam-pgsql/.
[...]
to use this module. Note, that unlike most other ports, this port
installs a file into /usr/lib directly (/usr/lib/pam_pgsql.so),
because PAM requires that.
===>   Registering installation for pam-pgsql-0.6.3_1
freebsd-vm# 

We need to tell vsftpd to use pam-pgsql for authentication.

freebsd-vm# vi /etc/pam.d/vsftpd
auth    required pam_pgsql.so config_file=/etc/pam_pgsql_vsftpd.conf
account required pam_pgsql.so config_file=/etc/pam_pgsql_vsftpd.conf

freebsd-vm# vi /etc/pam_pgsql_vsftpd.conf
debug
pw_type = md5
connect = hostaddr=127.0.0.1 port=5432 dbname=<font color="red">sample_development</font> \
        user=<font color="red">sample_user</font> password='<font color="red">password</font>' connect_timeout=15
auth_query = select <font color="yellow">password</font> from <font color="yellow">users</font> where <font color="yellow">username</font> = %u
acct_query = select <font color="white">ftp_disabled</font> as acc_expired, \
        0 as acc_new_pwreq, (password ISNULL or password = '') as user_password \ 
        from <font color="white">users</font> where username = %u

freebsd-vm#

(Long lines above with \ in them should be one long continuous line in your config file)

The configuration above assumes three things:

  • Your rails database name is sample_development and can be connected with the username sample_user and the password password (change red items as needed)
  • Your rails users are stored in the users table. The password field is password and the username field is username (change yellow items as needed)
  • Your rails users are stored in the users table. The ftp_disabled field holds whether they should be allowed access (false) or denied (true). (Change white items as needed)

We need to create the user for vsftpd to run as.

freebsd-vm# adduser 
Username: vsftpd
Full name: FTP User
Uid (Leave empty for default): 
Login group [vsftpd]: 
Login group is vsftpd. Invite vsftpd into other groups? []: 
Login class [default]: 
Shell (sh csh tcsh nologin) [sh]: nologin
Home directory [/home/vsftpd]: 
Use password-based authentication? [yes]: no
Lock out the account after creation? [no]: 
Username   : vsftpd
Password   : <disabled>
Full Name  : FTP User
Uid        : 1002
Class      : 
Groups     : vsftpd 
Home       : /home/vsftpd
Shell      : /usr/sbin/nologin
Locked     : no
OK? (yes/no): yes
adduser: INFO: Successfully added (vsftpd) to the user database.
Add another user? (yes/no): no
Goodbye!
freebsd-vm# 

Configure vsftpd to start on boot and manually start vsftpd once.

freebsd-vm# echo vsftpd_enable="YES" >> /etc/rc.conf 
freebsd-vm# chmod 755 /usr/local/etc/rc.d/vsftpd
freebsd-vm# /usr/local/etc/rc.d/vsftpd start
Starting vsftpd.
freebsd-vm# 

Now we need to create a couple of users to test this with. Below we’ll create a user bob that can login and a user bob2 that can not login.

freebsd-vm$ psql -U sample_rails_app sample_rails_app_development
Welcome to psql 8.3.3, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help with psql commands
       \g or terminate with semicolon to execute query
       \q to quit

sample_rails_app_development=> select * from users;
 id | username | password | homedir | ftp_disabled | created_at | updated_at 
----+----------+----------+---------+--------------+------------+------------
(0 rows)
sample_rails_app_development=> insert into users (username,password,homedir,ftp_disabled) values ('bob',md5('bob'),'/home/bob',false);
INSERT 0 1
sample_rails_app_development=> insert into users (username,password,homedir,ftp_disabled) values ('bob2',md5('bob2'),'/home/bob2',true);
INSERT 0 1
sample_rails_app_development=> select * from users;
 id | username |             password             |  homedir   | ftp_disabled | created_at | updated_at 
----+----------+----------------------------------+------------+--------------+------------+------------
  2 | bob      | 9f9d51bc70ef21ca5c14f307980a29d8 | /home/bob  | f            |            | 
  3 | bob2     | 436187b1cb437f7ddb11952542e351a4 | /home/bob2 | t            |            | 
(2 rows)

sample_rails_app_development=> \q
freebsd-vm$ 

Next, we need to create bob’s virtual home directory (as root).

freebsd-vm# mkdir -p /usr/local/www/apache22/data/bob
freebsd-vm# chown vsftpd:vsftpd /usr/local/www/apache22/data/bob

Now we can login as bob (and not bob2).

freebsd-vm$ ftp localhost
Trying 127.0.0.1...
Connected to localhost.
220 Welcome to FTP server
Name (localhost:jasonn): bob
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> pwd
Remote directory: /
ftp> quit
221 Goodbye.
freebsd-vm$ ftp localhost
Trying 127.0.0.1...
Connected to localhost.
220 Welcome to FTP server
Name (localhost:jasonn): bob2
331 Please specify the password.
Password:
530 Login incorrect.
ftp: Login failed.
ftp> quit
221 Goodbye.
freebsd-vm$ 

Now we need a script that will setup the FTP user’s home directory. (Run this in your Rails project’s home directory)

freebsd-vm# echo "User.write_ftp_configs" >> write_ftp_configs
freebsd-vm#

Change the User model in your Rails application

freebsd-vm$ vi app/models/user.rb 

class User < ActiveRecord::Base
  require 'ftools'

  def self.write_ftp_configs
    User.find(:all, :conditions => ["ftp_disabled is false"]).each do |user|
      unless File.directory?(user.homedir)
        # If their home directory doesn't exist, create it
        # and chown the directory to vsftpd (1002)
        File.makedirs user.homedir
        File.chown(1002, 1002, user.homedir)
      end
      if File.directory?("/etc/vsftpd/users")
        unless Dir.entries("/etc/vsftpd/users").include?(user.homedir)
          File.open("/etc/vsftpd/users/#{user.username}", 'w') {|f|
            f.write("local_root=#{user.homedir}\n");
          }
        end
      end
    end
  end
end

Now you just need to setup a cronjob to run as root. This script should cd to your rails root directory and run “script/runner write_ftp_configs”.

WARNING: There may be security implications with this script. If a user has their homedir set to something “sensitive” this script will create that directory for them. Make sure you trust anyone that can add users via your Rails application. You could fix this by adding a validation on the homedir field so that it’s only a subdirectory of a given directory (i.e. $RAILS_ROOT/upload) or something.

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