xdm_selinux - Man Page

Security-Enhanced Linux secures the xdm processes via flexible mandatory access control.

The xdm processes execute with the xdm_t SELinux type. You can check if you have these processes running by executing the ps command with the -Z qualifier.

For example:

ps -eZ | grep xdm_t

The xdm_t SELinux type can be entered via the user_tmp_t, xdm_exec_t file types.

The default entrypoint paths for the xdm_t domain are the following:

/run/user/[^/]+, /dev/shm/mono.*, /tmp/.ICE-unix(/.*)?, /tmp/.X11-unix(/.*)?, /dev/shm/pulse-shm.*, /run/user, /tmp/.X0-lock, /tmp/hsperfdata_root, /var/tmp/hsperfdata_root, /home/[^/]+/tmp, /home/[^/]+/.tmp, /run/user/[0-9]+, /tmp/gconfd-[^/]+, /usr/bin/[mxgkw]dm, /usr/bin/gdm(3)?, /usr/bin/lxdm(-binary)?, /usr/X11R6/bin/[xgkw]dm, /usr/bin/lightdm*, /usr/bin/razor-lightdm-.*, /usr/bin/nodm, /usr/bin/sddm, /usr/bin/slim, /usr/bin/gpe-dm, /opt/kde3/bin/kdm, /usr/bin/gdm-binary, /usr/bin/mdm-binary, /usr/bin/sddm-greeter, /etc/rc.d/init.d/x11-common, /usr/libexec/gdm-runtime-config, /usr/libexec/gdm-disable-wayland

SELinux defines process types (domains) for each process running on the system

You can see the context of a process using the -Z option to psbP

Policy governs the access confined processes have to files. SELinux xdm policy is very flexible allowing users to setup their xdm processes in as secure a method as possible.

The following process types are defined for xdm:

xdm_t, xdm_unconfined_t

Note: semanage permissive -a xdm_t can be used to make the process type xdm_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated.

SELinux policy is customizable based on least access required.  xdm policy is extremely flexible and has several booleans that allow you to manipulate the policy and run xdm with the tightest access possible.

If you want to allows xdm_t to bind on vnc_port_t(5910), you must turn on the xdm_bind_vnc_tcp_port boolean. Disabled by default.

setsebool -P xdm_bind_vnc_tcp_port 1

If you want to allow the graphical login program to create, read, write, and delete files in the /boot director and DOS filesystem, you must turn on the xdm_manage_bootloader boolean. Enabled by default.

setsebool -P xdm_manage_bootloader 1

If you want to allow the graphical login program to login directly as sysadm_r:sysadm_t, you must turn on the xdm_sysadm_login boolean. Disabled by default.

setsebool -P xdm_sysadm_login 1

If you want to deny user domains applications to map a memory region as both executable and writable, this is dangerous and the executable should be reported in bugzilla, you must turn on the deny_execmem boolean. Disabled by default.

setsebool -P deny_execmem 1

If you want to deny any process from ptracing or debugging any other processes, you must turn on the deny_ptrace boolean. Disabled by default.

setsebool -P deny_ptrace 1

If you want to allow all domains to execute in fips_mode, you must turn on the fips_mode boolean. Enabled by default.

setsebool -P fips_mode 1

If you want to allow confined applications to run with kerberos, you must turn on the kerberos_enabled boolean. Enabled by default.

setsebool -P kerberos_enabled 1

If you want to allow system to run with NIS, you must turn on the nis_enabled boolean. Disabled by default.

setsebool -P nis_enabled 1

If you want to enable polyinstantiated directory support, you must turn on the polyinstantiation_enabled boolean. Disabled by default.

setsebool -P polyinstantiation_enabled 1

If you want to allow unconfined executables to make their stack executable.  This should never, ever be necessary. Probably indicates a badly coded executable, but could indicate an attack. This executable should be reported in bugzilla, you must turn on the selinuxuser_execstack boolean. Enabled by default.

setsebool -P selinuxuser_execstack 1

If you want to support ecryptfs home directories, you must turn on the use_ecryptfs_home_dirs boolean. Disabled by default.

setsebool -P use_ecryptfs_home_dirs 1

If you want to support fusefs home directories, you must turn on the use_fusefs_home_dirs boolean. Disabled by default.

setsebool -P use_fusefs_home_dirs 1

If you want to support NFS home directories, you must turn on the use_nfs_home_dirs boolean. Disabled by default.

setsebool -P use_nfs_home_dirs 1

If you want to support SAMBA home directories, you must turn on the use_samba_home_dirs boolean. Disabled by default.

setsebool -P use_samba_home_dirs 1

SELinux defines port types to represent TCP and UDP ports.

You can see the types associated with a port by using the following command:

semanage port -l

Policy governs the access confined processes have to these ports. SELinux xdm policy is very flexible allowing users to setup their xdm processes in as secure a method as possible.

The following port types are defined for xdm:

    xdmcp_port_t

Default Defined Ports: tcp 177 udp 177

The SELinux process type xdm_t can manage files labeled with the following file types.  The paths listed are the default paths for these file types.  Note the processes UID still need to have DAC permissions.

auth_cache_t

/var/cache/coolkey(/.*)?

auth_home_t

/root/.yubico(/.*)?
/root/.config/Yubico(/.*)?
/root/.google_authenticator
/root/.google_authenticator~
/home/[^/]+/.yubico(/.*)?
/home/[^/]+/.config/Yubico(/.*)?
/home/[^/]+/.google_authenticator
/home/[^/]+/.google_authenticator~

cifs_t

dosfs_t

faillog_t

/var/log/btmp.*
/run/faillock(/.*)?
/var/log/faillog.*
/var/log/tallylog.*

fusefs_t

/run/user/[0-9]+/gvfs

gnome_initial_setup_var_lib_t

/var/lib/gnome-initial-setup(/.*)?

gnome_initial_setup_var_run_t

/run/gnome-initial-setup(/.*)?

initrc_var_run_t

/run/utmp
/run/random-seed
/run/runlevel.dir
/run/setmixer_flag

krb5_host_rcache_t

/var/tmp/krb5_0.rcache2
/var/cache/krb5rcache(/.*)?
/var/tmp/nfs_0
/var/tmp/DNS_25
/var/tmp/host_0
/var/tmp/imap_0
/var/tmp/HTTP_23
/var/tmp/HTTP_48
/var/tmp/ldap_55
/var/tmp/ldap_487
/var/tmp/ldapmap1_0

lastlog_t

/var/log/lastlog.*

nfs_t

pam_var_console_t

/run/console(/.*)?

pam_var_run_t

/var/(db|adm)/sudo(/.*)?
/run/sudo(/.*)?
/run/pam_ssh(/.*)?
/run/sepermit(/.*)?
/var/lib/sudo(/.*)?
/run/pam_mount(/.*)?
/run/pam_timestamp(/.*)?

security_t

/selinux

sysfs_t

/sys(/.*)?

systemd_passwd_var_run_t

/run/systemd/ask-password(/.*)?
/run/systemd/ask-password-block(/.*)?

tmpfs_t

/dev/shm
/run/shm
/usr/lib/udev/devices/shm

user_tmp_t

/run/user/[^/]+
/dev/shm/mono.*
/tmp/.ICE-unix(/.*)?
/tmp/.X11-unix(/.*)?
/dev/shm/pulse-shm.*
/run/user
/tmp/.X0-lock
/tmp/hsperfdata_root
/var/tmp/hsperfdata_root
/home/[^/]+/tmp
/home/[^/]+/.tmp
/run/user/[0-9]+
/tmp/gconfd-[^/]+

user_tmp_type

all user tmp files

var_auth_t

/var/ace(/.*)?
/var/rsa(/.*)?
/var/lib/abl(/.*)?
/var/lib/rsa(/.*)?
/var/lib/pam_ssh(/.*)?
/var/lib/pam_shield(/.*)?
/var/opt/quest/vas/vasd(/.*)?
/var/lib/google-authenticator(/.*)?

wtmp_t

/var/log/wtmp.*

xdm_lock_t

xdm_log_t

/var/log/[mkwx]dm.log.*
/var/log/mdm(/.*)?
/var/log/lxdm.log.*
/var/log/slim.log.*

xdm_spool_t

/var/spool/[mg]dm(/.*)?

xdm_tmpfs_t

xdm_var_lib_t

/var/lib/[mxkwg]dm(/.*)?
/var/cache/[mg]dm(/.*)?
/var/lib/gdm(3)?(/.*)?
/var/lib/lxdm(/.*)?
/var/lib/sddm(/.*)?
/var/lib/lightdm(/.*)?
/var/cache/lightdm(/.*)?
/var/lib/lightdm-data(/.*)?

xdm_var_run_t

/run/[kgm]dm(/.*)?
/run/gdm(3)?.pid
/run/gdm(3)?(/.*)?
/etc/kde[34]?/kdm/backgroundrc
/run/slim.*
/run/lxdm(/.*)?
/run/sddm(/.*)?
/run/xauth(/.*)?
/run/xdmctl(/.*)?
/run/lightdm(/.*)?
/usr/lib/qt-.*/etc/settings(/.*)?
/run/systemd/multi-session-x(/.*)?
/run/xdm.pid
/run/lxdm.pid
/run/lxdm.auth
/run/gdm_socket

xkb_var_lib_t

/var/lib/xkb(/.*)?
/usr/X11R6/lib/X11/xkb/.*
/usr/X11R6/lib/X11/xkb

xserver_log_t

/var/[xgkw]dm(/.*)?
/usr/var/[xgkw]dm(/.*)?
/var/log/gdm(3)?(/.*)?
/var/log/Xorg.*
/var/log/XFree86.*
/var/log/lightdm(/.*)?
/var/log/nvidia-installer.log.*

xserver_tmpfs_t

SELinux requires files to have an extended attribute to define the file type.

You can see the context of a file using the -Z option to lsbP

Policy governs the access confined processes have to these files. SELinux xdm policy is very flexible allowing users to setup their xdm processes in as secure a method as possible.

EQUIVALENCE DIRECTORIES

xdm policy stores data with multiple different file context types under the /var/lib/lightdm directory.  If you would like to store the data in a different directory you can use the semanage command to create an equivalence mapping.  If you wanted to store this data under the /srv directory you would execute the following command:

semanage fcontext -a -e /var/lib/lightdm /srv/lightdm
restorecon -R -v /srv/lightdm

STANDARD FILE CONTEXT

SELinux defines the file context types for the xdm, if you wanted to store files with these types in a different paths, you need to execute the semanage command to specify alternate labeling and then use restorecon to put the labels on disk.

semanage fcontext -a -t xdm_unconfined_exec_t '/srv/xdm/content(/.*)?'
restorecon -R -v /srv/myxdm_content

Note: SELinux often uses regular expressions to specify labels that match multiple files.

The following file types are defined for xdm:

xdm_etc_t

- Set files with the xdm_etc_t type, if you want to store xdm files in the /etc directories.

xdm_exec_t

- Set files with the xdm_exec_t type, if you want to transition an executable to the xdm_t domain.

Paths:

/usr/bin/[mxgkw]dm, /usr/bin/gdm(3)?, /usr/bin/lxdm(-binary)?, /usr/X11R6/bin/[xgkw]dm, /usr/bin/lightdm*, /usr/bin/razor-lightdm-.*, /usr/bin/nodm, /usr/bin/sddm, /usr/bin/slim, /usr/bin/gpe-dm, /opt/kde3/bin/kdm, /usr/bin/gdm-binary, /usr/bin/mdm-binary, /usr/bin/sddm-greeter, /etc/rc.d/init.d/x11-common, /usr/libexec/gdm-runtime-config, /usr/libexec/gdm-disable-wayland

xdm_home_t

- Set files with the xdm_home_t type, if you want to store xdm files in the users home directory.

Paths:

/root/.dmrc.*, /root/.wayland-errors.*, /root/.xsession-errors.*, /home/[^/]+/.dmrc.*, /home/[^/]+/.cache/gdm(/.*)?, /home/[^/]+/.wayland-errors.*, /home/[^/]+/.xsession-errors.*, /home/[^/]+/.local/share/xorg(/.*)?

xdm_lock_t

- Set files with the xdm_lock_t type, if you want to treat the files as xdm lock data, stored under the /var/lock directory

xdm_log_t

- Set files with the xdm_log_t type, if you want to treat the data as xdm log data, usually stored under the /var/log directory.

Paths:

/var/log/[mkwx]dm.log.*, /var/log/mdm(/.*)?, /var/log/lxdm.log.*, /var/log/slim.log.*

xdm_rw_etc_t

- Set files with the xdm_rw_etc_t type, if you want to store xdm rw files in the /etc directories.

Paths:

/etc/X11/wdm(/.*)?, /etc/opt/VirtualGL(/.*)?

xdm_spool_t

- Set files with the xdm_spool_t type, if you want to store the xdm files under the /var/spool directory.

xdm_tmpfs_t

- Set files with the xdm_tmpfs_t type, if you want to store xdm files on a tmpfs file system.

xdm_unconfined_exec_t

- Set files with the xdm_unconfined_exec_t type, if you want to transition an executable to the xdm_unconfined_t domain.

Paths:

/etc/[mg]dm/Init(/.*)?, /etc/[mg]dm/PostLogin(/.*)?, /etc/[mg]dm/PreSession(/.*)?, /etc/[mg]dm/PostSession(/.*)?

xdm_unit_file_t

- Set files with the xdm_unit_file_t type, if you want to treat the files as xdm unit content.

xdm_var_lib_t

- Set files with the xdm_var_lib_t type, if you want to store the xdm files under the /var/lib directory.

Paths:

/var/lib/[mxkwg]dm(/.*)?, /var/cache/[mg]dm(/.*)?, /var/lib/gdm(3)?(/.*)?, /var/lib/lxdm(/.*)?, /var/lib/sddm(/.*)?, /var/lib/lightdm(/.*)?, /var/cache/lightdm(/.*)?, /var/lib/lightdm-data(/.*)?

xdm_var_run_t

- Set files with the xdm_var_run_t type, if you want to store the xdm files under the /run or /var/run directory.

Paths:

/run/[kgm]dm(/.*)?, /run/gdm(3)?.pid, /run/gdm(3)?(/.*)?, /etc/kde[34]?/kdm/backgroundrc, /run/slim.*, /run/lxdm(/.*)?, /run/sddm(/.*)?, /run/xauth(/.*)?, /run/xdmctl(/.*)?, /run/lightdm(/.*)?, /usr/lib/qt-.*/etc/settings(/.*)?, /run/systemd/multi-session-x(/.*)?, /run/xdm.pid, /run/lxdm.pid, /run/lxdm.auth, /run/gdm_socket

Note: File context can be temporarily modified with the chcon command.  If you want to permanently change the file context you need to use the semanage fcontext command.  This will modify the SELinux labeling database.  You will need to use restorecon to apply the labels.

semanage fcontext can also be used to manipulate default file context mappings.

semanage permissive can also be used to manipulate whether or not a process type is permissive.

semanage module can also be used to enable/disable/install/remove policy modules.

semanage port can also be used to manipulate the port definitions

semanage boolean can also be used to manipulate the booleans

system-config-selinux is a GUI tool available to customize SELinux policy settings.

This manual page was auto-generated using sepolicy manpage .

selinux(8), xdm(8), semanage(8), restorecon(8), chcon(1), sepolicy(8), setsebool(8), xdm_unconfined_selinux(8), xdm_unconfined_selinux(8)