NAME¶

xserver_selinux - Security Enhanced Linux Policy for the xserver processes

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 file_type, unlabeled_t, proc_type, xserver_exec_t, filesystem_type, mtrr_device_t, sysctl_type file types.

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

all files on the system, /usr/bin/Xair, /usr/bin/Xorg, /usr/bin/Xephyr, /usr/X11R6/bin/X, /usr/X11R6/bin/Xorg, /usr/X11R6/bin/Xipaq, /usr/local/bin/x11vnc, /usr/X11R6/bin/XFree86, /usr/X11R6/bin/Xwrapper, /etc/init.d/xfree86-common, /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 generated.

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 possible.

If you want to support X userspace object manager, you must turn on the xserver_object_manager boolean. Disabled by default.

setsebool -P xserver_object_manager 1

If you want to allow all daemons the ability to read/write terminals, you must turn on the allow_daemons_use_tty boolean. Disabled by default.

setsebool -P allow_daemons_use_tty 1

If you want to allow all domains to use other domains file descriptors, you must turn on the allow_domain_fd_use boolean. Enabled by default.

setsebool -P allow_domain_fd_use 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 allow_execheap boolean. Disabled by default.

setsebool -P allow_execheap 1

If you want to allow unconfined executables 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 allow_execmem boolean. Enabled by default.

setsebool -P allow_execmem 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 allow_execmod boolean. Enabled by default.

setsebool -P allow_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 allow_execstack boolean. Enabled by default.

setsebool -P allow_execstack 1

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

setsebool -P allow_kerberos 1

If you want to allow sysadm to debug or ptrace all processes, you must turn on the allow_ptrace boolean. Disabled by default.

setsebool -P allow_ptrace 1

If you want to allows XServer to execute writable memory, you must turn on the allow_xserver_execmem boolean. Disabled by default.

setsebool -P allow_xserver_execmem 1

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

setsebool -P allow_ypbind 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 certain domains to map low memory in the kernel, you must turn on the mmap_low_allowed boolean. Disabled by default.

setsebool -P mmap_low_allowed 1

If you want to allow confined applications to use nscd shared memory, you must turn on the nscd_use_shm boolean. Enabled by default.

setsebool -P nscd_use_shm 1

If you want to disable transitions to insmod, you must turn on the secure_mode_insmod boolean. Disabled 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. Disabled by default.

setsebool -P secure_mode_policyload 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

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 6000-6150

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_var_run_t '/srv/myxserver_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_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/Xephyr, /usr/X11R6/bin/X, /usr/X11R6/bin/Xorg, /usr/X11R6/bin/Xipaq, /usr/local/bin/x11vnc, /usr/X11R6/bin/XFree86, /usr/X11R6/bin/Xwrapper, /etc/init.d/xfree86-common

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/[xgk]dm(/.*)?, /var/log/[kw]dm.log.*, /usr/var/[xgkw]dm(/.*)?, /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.

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 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.

AUTHOR¶

This manual page was auto-generated using sepolicy manpage .

SEE ALSO¶

selinux(8), xserver(8), semanage(8), restorecon(8), chcon(1) , setsebool(8)