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debuser
  Post  Post subject: Vsftpd and SELinux - Making them work together for system users  |  Posted: Sun Jan 03, 2010 2:53 pm

Joined: Thu Aug 06, 2009 2:48 am
Posts: 105

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Vsftpd and SELinux - Making them work together for system users

Vsftpd will work by default if SELinux is turned of or set to permissive mode.

For security paranoias (like me), SELinux in Enforced mode will not, by default, allow users to FTP to their home directories. This is because their security context will be:
Code:
# ls -Zda ~user
drwxr-x---  user user system_u:object_r:default_t      /home2/user

system_u - system user
object_r - system object
default_t - default label

The above selinux security context will not allow vsftpd daemon to chdir to this directory (after user has authenticated ok), giving the following error:
Code:
500 OOPS: cannot change directory:/home/user


Selinux has a series of default boolean values, including ones that refer to ftp protocol:
Code:
# getsebool -a | grep -i ftp
allow_ftpd_anon_write --> off
allow_ftpd_full_access --> off
allow_ftpd_use_cifs --> off
allow_ftpd_use_nfs --> off
allow_tftp_anon_write --> off
ftp_home_dir --> off
ftpd_disable_trans --> off
ftpd_is_daemon --> on
httpd_enable_ftp_server --> off
tftpd_disable_trans --> off


The boolean that I'm interested in here is: ftp_home_dir - Allow ftp to read and write files in the user home directories
So I'm gonna change this boolean to "on" and test again.
Code:
setsebool -P ftp_home_dir=1


Now, ftp localhost with user user will work.

For more info about SELinux booleans see /usr/share/doc/selinux-policy-x.x.x/html/global_tunables.html file or take a look below:
Quote:
Global tunables:
allow_cvs_read_shadow
Default value
false
Description
Allow cvs daemon to read shadow
allow_execheap
Default value
false
Description
Allow making the heap executable.
allow_execmem
Default value
false
Description
Allow making anonymous memory executable, e.g. for runtime-code generation or executable stack.
allow_execmod
Default value
false
Description
Allow making a modified private file mapping executable (text relocation).
allow_execstack
Default value
false
Description
Allow making the stack executable via mprotect. Also requires allow_execmem.
allow_ftpd_anon_write
Default value
false
Description
Allow ftp servers to modify public files used for public file transfer services.
allow_gpg_execstack
Default value
false
Description
Allow gpg executable stack
allow_gssd_read_tmp
Default value
true
Description
Allow gssd to read temp directory.
allow_httpd_anon_write
Default value
false
Description
Allow Apache to modify public files used for public file transfer services.
allow_java_execstack
Default value
false
Description
Allow java executable stack
allow_kerberos
Default value
false
Description
Allow system to run with kerberos
allow_ptrace
Default value
false
Description
Allow sysadm to ptrace all processes
allow_rsync_anon_write
Default value
false
Description
Allow rsync to modify public files used for public file transfer services.
allow_saslauthd_read_shadow
Default value
false
Description
Allow sasl to read shadow
allow_smbd_anon_write
Default value
false
Description
Allow samba to modify public files used for public file transfer services.
allow_ssh_keysign
Default value
false
Description
allow host key based authentication
allow_user_mysql_connect
Default value
false
Description
Allow users to connect to mysql
allow_write_xshm
Default value
false
Description
Allows clients to write to the X server shared memory segments.
allow_ypbind
Default value
false
Description
Allow system to run with NIS
cdrecord_read_content
Default value
false
Description
Allow cdrecord to read various content. nfs, samba, removable devices, user temp and untrusted content files
cron_can_relabel
Default value
false
Description
Allow system cron jobs to relabel filesystem for restoring file contexts.
fcron_crond
Default value
false
Description
Enable extra rules in the cron domain to support fcron.
ftp_home_dir
Default value
false
Description
Allow ftp to read and write files in the user home directories
ftpd_is_daemon
Default value
false
Description
Allow ftpd to run directly without inetd
httpd_builtin_scripting
Default value
false
Description
Allow httpd to use built in scripting (usually php)
httpd_can_network_connect
Default value
false
Description
Allow http daemon to tcp connect
httpd_can_network_connect_db
Default value
false
Description
Allow httpd to connect to mysql/posgresql
httpd_can_network_relay
Default value
false
Description
Allow httpd to act as a relay
httpd_enable_cgi
Default value
false
Description
Allow httpd cgi support
httpd_enable_ftp_server
Default value
false
Description
Allow httpd to act as a FTP server by listening on the ftp port.
httpd_enable_homedirs
Default value
false
Description
Allow httpd to read home directories
httpd_ssi_exec
Default value
false
Description
Run SSI execs in system CGI script domain.
httpd_tty_comm
Default value
false
Description
Allow http daemon to communicate with the TTY
httpd_unified
Default value
false
Description
Run CGI in the main httpd domain
named_write_master_zones
Default value
false
Description
Allow BIND to write the master zone files. Generally this is used for dynamic DNS.
nfs_export_all_ro
Default value
false
Description
Allow nfs to be exported read only
nfs_export_all_rw
Default value
false
Description
Allow nfs to be exported read/write.
pppd_can_insmod
Default value
false
Description
Allow pppd to load kernel modules for certain modems
pppd_for_user
Default value
false
Description
Allow pppd to be run for a regular user
read_default_t
Default value
false
Description
Allow reading of default_t files.
read_untrusted_content
Default value
false
Description
Allow applications to read untrusted content If this is disallowed, Internet content has to be manually relabeled for read access to be granted
run_ssh_inetd
Default value
false
Description
Allow ssh to run from inetd instead of as a daemon.
samba_enable_home_dirs
Default value
false
Description
Allow samba to export user home directories.
spamassasin_can_network
Default value
false
Description
Allow spamassassin to do DNS lookups
spamassassin_can_network
Default value
false
Description
Allow user spamassassin clients to use the network.
spamd_enable_home_dirs
Default value
true
Description
Allow spammd to read/write user home directories.
squid_connect_any
Default value
false
Description
Allow squid to connect to all ports, not just HTTP, FTP, and Gopher ports.
ssh_sysadm_login
Default value
false
Description
Allow ssh logins as sysadm_r:sysadm_t
staff_read_sysadm_file
Default value
false
Description
Allow staff_r users to search the sysadm home dir and read files (such as ~/.bashrc)
stunnel_is_daemon
Default value
false
Description
Configure stunnel to be a standalone daemon or inetd service.
use_nfs_home_dirs
Default value
false
Description
Support NFS home directories
use_samba_home_dirs
Default value
false
Description
Support SAMBA home directories
user_direct_mouse
Default value
false
Description
Allow regular users direct mouse access
user_dmesg
Default value
false
Description
Allow users to read system messages.
user_net_control
Default value
false
Description
Allow users to control network interfaces (also needs USERCTL=true)
user_ping
Default value
false
Description
Control users use of ping and traceroute
user_rw_noexattrfile
Default value
false
Description
Allow user to r/w files on filesystems that do not have extended attributes (FAT, CDROM, FLOPPY)
user_rw_usb
Default value
false
Description
Allow users to rw usb devices
user_tcp_server
Default value
false
Description
Allow users to run TCP servers (bind to ports and accept connection from the same domain and outside users) disabling this forces FTP passive mode and may change other protocols.
user_ttyfile_stat
Default value
false
Description
Allow w to display everyone
write_untrusted_content
Default value
false
Description
Allow applications to write untrusted content If this is disallowed, no Internet content will be stored.
xdm_sysadm_login
Default value
false
Description
Allow xdm logins as sysadm





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