xserver_selinux − Security Enhanced Linux Policy for the xserver processes
Security-Enhanced Linux secures the xserver processes via flexible mandatory access control.
The xserver processes execute with the xserver_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 xserver_t
The xserver_t SELinux type can be entered via the mtrr_device_t, unlabeled_t, proc_type, xserver_exec_t, sysctl_type, file_type, filesystem_type file types.
The default entrypoint paths for the xserver_t domain are the following:
/dev/cpu/mtrr, /usr/bin/Xair, /usr/bin/Xorg, /usr/bin/Xvnc, /usr/bin/Xephyr, /usr/bin/x11vnc, /usr/X11R6/bin/X, /usr/X11R6/bin/Xorg, /usr/X11R6/bin/Xipaq, /usr/X11R6/bin/XFree86, /usr/X11R6/bin/Xwrapper, all files on the system
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 ps
Policy governs the access confined processes have to files. SELinux xserver policy is very flexible allowing users to setup their xserver processes in as secure a method as possible.
The following process types are defined for xserver:
xserver_t
Note: semanage permissive -a xserver_t can be used to make the process type xserver_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. xserver policy is extremely flexible and has several booleans that allow you to manipulate the policy and run xserver with the tightest access possible.
If you want to allows XServer to execute writable memory, you must turn on the xserver_execmem boolean. Disabled by default.
setsebool -P xserver_execmem 1
If you want to support X userspace object manager, you must turn on the xserver_object_manager boolean. Enabled by default.
setsebool -P xserver_object_manager 1
If you want to allow users to resolve user passwd entries directly from ldap rather then using a sssd server, you must turn on the authlogin_nsswitch_use_ldap boolean. Disabled by default.
setsebool -P authlogin_nsswitch_use_ldap 1
If you want to allow all daemons the ability to read/write terminals, you must turn on the daemons_use_tty boolean. Disabled by default.
setsebool -P daemons_use_tty 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. Enabled 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. Enabled by default.
setsebool -P deny_ptrace 1
If you want to allow all domains to use other domains file descriptors, you must turn on the domain_fd_use boolean. Enabled by default.
setsebool -P domain_fd_use 1
If you want to allow all domains to have the kernel load modules, you must turn on the domain_kernel_load_modules boolean. Disabled by default.
setsebool -P domain_kernel_load_modules 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 enable reading of urandom for all domains, you must turn on the global_ssp boolean. Disabled by default.
setsebool -P global_ssp 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 control the ability to mmap a low area of the address space, as configured by /proc/sys/kernel/mmap_min_addr, you must turn on the mmap_low_allowed boolean. Disabled by default.
setsebool -P mmap_low_allowed 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 allow confined applications to use nscd shared memory, you must turn on the nscd_use_shm boolean. Disabled by default.
setsebool -P nscd_use_shm 1
If you want to disable kernel module loading, you must turn on the secure_mode_insmod boolean. Enabled by default.
setsebool -P secure_mode_insmod 1
If you want to allow unconfined executables to make their heap memory executable. Doing this is a really bad idea. Probably indicates a badly coded executable, but could indicate an attack. This executable should be reported in bugzilla, you must turn on the selinuxuser_execheap boolean. Disabled by default.
setsebool -P selinuxuser_execheap 1
If you want to allow all unconfined executables to use libraries requiring text relocation that are not labeled textrel_shlib_t, you must turn on the selinuxuser_execmod boolean. Enabled by default.
setsebool -P selinuxuser_execmod 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
If you want to allow confined virtual guests to interact with the xserver, you must turn on the virt_use_xserver boolean. Disabled by default.
setsebool -P virt_use_xserver 1
If you want to allow ZoneMinder to run su/sudo, you must turn on the zoneminder_run_sudo boolean. Disabled by default.
setsebool -P zoneminder_run_sudo 1
If you want to allow users to resolve user passwd entries directly from ldap rather then using a sssd server for the xserver_t, you must turn on the authlogin_nsswitch_use_ldap boolean.
setsebool -P authlogin_nsswitch_use_ldap 1
If you want to allow confined applications to run with kerberos for the xserver_t, you must turn on the kerberos_enabled boolean.
setsebool -P kerberos_enabled 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 xserver policy is very flexible allowing users to setup their xserver processes in as secure a method as possible.
The following
port types are defined for xserver:
xserver_port_t
Default Defined Ports:
tcp 6000-6020
The SELinux process type xserver_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.
bluetooth_helper_tmpfs_t
chrome_sandbox_tmpfs_t
cifs_t
consolekit_tmpfs_t
ecryptfs_t
/home/[^/]*/.Private(/.*)?
/home/[^/]*/.ecryptfs(/.*)?
fusefs_t
/var/run/[^/]*/gvfs
games_tmpfs_t
gpg_pinentry_tmpfs_t
mplayer_tmpfs_t
mtrr_device_t
/dev/cpu/mtrr
nfs_t
proc_type
pulseaudio_tmpfs_t
rhgb_tmpfs_t
sandbox_xserver_tmpfs_t
semanage_store_t
/etc/share/selinux/mls(/.*)?
/etc/share/selinux/targeted(/.*)?
smzy_security_t
/selinux
ssh_tmpfs_t
sysctl_type
sysfs_t
/sys(/.*)?
systemd_passwd_var_run_t
/var/run/systemd/ask-password(/.*)?
/var/run/systemd/ask-password-block(/.*)?
tmpfs_t
/dev/shm
/lib/udev/devices/shm
/usr/lib/udev/devices/shm
tvtime_tmpfs_t
unlabeled_t
user_fonts_cache_t
/root/.fontconfig(/.*)?
/root/.fonts/auto(/.*)?
/root/.fonts.cache-.*
/home/[^/]*/.fontconfig(/.*)?
/home/[^/]*/.fonts/auto(/.*)?
/home/[^/]*/.fonts.cache-.*
user_tmpfs_t
/dev/shm/mono.*
/dev/shm/pulse-shm.*
vmware_tmpfs_t
wireshark_tmpfs_t
xdm_log_t
/var/log/[mkwx]dm.log.*
/var/log/mdm(/.*)?
/var/log/lxdm.log.*
/var/log/slim.log.*
xdm_tmp_t
/tmp/.X11-unix(/.*)?
/tmp/.ICE-unix(/.*)?
/tmp/.X0-lock
xdm_tmpfs_t
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/nvidia-installer.log.*
xserver_tmpfs_t
xserver_var_lib_t
/var/lib/xorg(/.*)?
xserver_var_run_t
/var/run/xorg(/.*)?
/var/run/video.rom
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 ls
Policy governs the access confined processes have to these files. SELinux xserver policy is very flexible allowing users to setup their xserver processes in as secure a method as possible.
STANDARD FILE CONTEXT
SELinux defines the file context types for the xserver, if you wanted to store files with these types in a diffent paths, you need to execute the semanage command to sepecify alternate labeling and then use restorecon to put the labels on disk.
semanage
fcontext -a -t xserver_etc_t
’/srv/xserver/content(/.*)?’
restorecon -R -v /srv/myxserver_content
Note: SELinux often uses regular expressions to specify labels that match multiple files.
The following file types are defined for xserver:
xserver_etc_t
- Set files with the xserver_etc_t type, if you want to store xserver files in the /etc directories.
xserver_exec_t
- Set files
with the xserver_exec_t type, if you want to transition an
executable to the xserver_t domain.
Paths:
/usr/bin/Xair, /usr/bin/Xorg, /usr/bin/Xvnc, /usr/bin/Xephyr, /usr/bin/x11vnc, /usr/X11R6/bin/X, /usr/X11R6/bin/Xorg, /usr/X11R6/bin/Xipaq, /usr/X11R6/bin/XFree86, /usr/X11R6/bin/Xwrapper
xserver_log_t
- Set files
with the xserver_log_t type, if you want to treat the data
as xserver log data, usually stored under the /var/log
directory.
Paths:
/var/[xgkw]dm(/.*)?, /usr/var/[xgkw]dm(/.*)?, /var/log/gdm(3)?(/.*)?, /var/log/Xorg.*, /var/log/XFree86.*, /var/log/nvidia-installer.log.*
xserver_tmpfs_t
- Set files with the xserver_tmpfs_t type, if you want to store xserver files on a tmpfs file system.
xserver_var_lib_t
- Set files with the xserver_var_lib_t type, if you want to store the xserver files under the /var/lib directory.
xserver_var_run_t
- Set files
with the xserver_var_run_t type, if you want to store the
xserver files under the /run or /var/run directory.
Paths:
/var/run/xorg(/.*)?, /var/run/video.rom
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), xserver(8), semanage(8), restorecon(8), chcon(1), sepolicy(8) , setsebool(8)