xserver_selinux(8) SELinux Policy xserver xserver_selinux(8)NAMExserver_selinux - Security Enhanced Linux Policy for the xserver pro‐
cesses
DESCRIPTION
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
ENTRYPOINTS
The xserver_t SELinux type can be entered via the xserver_exec_t,
filesystem_type, unlabeled_t, proc_type, file_type, sysctl_type,
mtrr_device_t file types.
The default entrypoint paths for the xserver_t domain are the follow‐
ing:
/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, /dev/cpu/mtrr
PROCESS TYPES
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 gener‐
ated.
BOOLEANS
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 possi‐
ble.
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 authlo‐
gin_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 bool‐
ean. 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 boolean to determine whether the system permits loading
policy, setting enforcing mode, and changing boolean values. Set this
to true and you have to reboot to set it back, you must turn on the
secure_mode_policyload boolean. Enabled by default.
setsebool -P secure_mode_policyload 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 selin‐
uxuser_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 exe‐
cutable. 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_exec‐
stack 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
NSSWITCH DOMAIN
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
PORT TYPES
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
MANAGED FILES
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.
file_type
all files on the system
FILE CONTEXTS
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/lightdm(/.*)?, /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 data‐
base. You will need to use restorecon to apply the labels.
COMMANDS
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 pol‐
icy 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 pol‐
icy settings.
AUTHOR
This manual page was auto-generated using sepolicy manpage .
SEE ALSOselinux(8), xserver(8), semanage(8), restorecon(8), chcon(1), sepol‐
icy(8) , setsebool(8)xserver 13-11-20 xserver_selinux(8)
