selabel_x(5) — Linux manual page


selabel_x(5)              SELinux API documentation             selabel_x(5)

NAME         top

       selabel_x  -  userspace  SELinux labeling interface and configuration
       file format for the X Window System contexts backend. This backend is
       also used to determine the default context for labeling remotely con‐
       nected X clients

SYNOPSIS         top

       #include <selinux/label.h>

       int selabel_lookup(struct selabel_handle *hnd,
                          char **context,
                          const char *object_name, int object_type);

       int selabel_lookup_raw(struct selabel_handle *hnd,
                          char **context,
                          const char *object_name, int object_type);

DESCRIPTION         top

       The X contexts backend maps from X Window System object names into
       security contexts. It is used to find the appropriate context for X
       Window System objects whose significance and/or usage semantics are
       determined primarily by name. The returned context must be freed
       using freecon(3).
       selabel_lookup(3) describes the function with its return and error

       This backend is also used to determine the default context for
       labeling remotely connected X clients.

       The object_type argument should be set to one of the following

                     The object_name argument specifies the name of a window
                     property, such as "WM_NAME".

                     The object_name argument specifies the name of a
                     selection, such as "PRIMARY".

                     The object_name argument specifies the name of a
                     protocol extension, such as "RENDER".

                     The object_name argument specifies the name of an event
                     type, such as "X11:ButtonPress".

                     The object_name argument is ignored, however it should
                     be set to either * (an asterisk or 'wildcard' that will
                     select the default entry) or a specific entry such as
                     "remote" in the X contexts file as shown in the EXAMPLE
                     section. The default context for labeling remote X
                     clients is then returned.

                     Like SELABEL_X_PROP, but checks if the property was
                     marked as being polyinstantiated. See NOTES below.

                     Like SELABEL_X_SELN, but checks if the selection was
                     marked as being polyinstantiated. See NOTES below.

       Any messages generated by selabel_lookup(3) are sent to stderr by
       default, although this can be changed by selinux_set_callback(3).

       selabel_lookup_raw behaves identically to selabel_lookup but does not
       perform context translation.

       The FILES section details the configuration files used to determine
       the X object context.

OPTIONS         top

       In addition to the global options described in selabel_open(3), this
       backend recognizes the following options:

                     A non-null value for this option specifies a path to a
                     file that will be opened in lieu of the standard X
                     contexts file (see the FILES section for details).

FILES         top

       The X context file used to retrieve a default context depends on the
       SELABEL_OPT_PATH parameter passed to selabel_open(3). If NULL, then
       the SELABEL_OPT_PATH value will default to the active policy X
       contexts location (as returned by selinux_x_context_path(3)),
       otherwise the actual SELABEL_OPT_PATH value specified is used.

       The default X object contexts file is:

       Where {SELINUXTYPE} is the entry from the selinux configuration file
       config (see selinux_config(5)).

       The entries within the X contexts file are shown in the Object Name
       String Values and FILE FORMAT sections.

Object Name String Values         top

       The string name assigned to each object_type argument that can be
       present in the X contexts file are:

                       │object_typeText Name      │
                       │SELABEL_X_PROP     │ property       │
                       │SELABEL_X_SELN     │ selection      │
                       │SELABEL_X_EXT      │ extension      │
                       │SELABEL_X_EVENT    │ event          │
                       │SELABEL_X_CLIENT   │ client         │
                       │SELABEL_X_POLYPROP │ poly_property  │
                       │SELABEL_X_POLYSELN │ poly_selection │

FILE FORMAT         top

       Each line within the X contexts file is as follows:
              object_type object_name context

                     This is the string representation of the object type
                     shown in the Object Name String Values section.  There
                     can be multiple lines with the same object_type string
                     that will form a block of entries (each with a
                     different object_name entry).
                     These are the object names of the specific X-server
                     resource such as PRIMARY, CUT_BUFFER0 etc. They are
                     generally defined in the X-server source code
                     (protocol.txt and BuiltInAtoms in the dix directory of
                     the xorg-server source package).  The entry can contain
                     '*' for wildcard matching or '?' for substitution.
                     Note that if the '*' is used, then be aware that the
                     order of entries in the file is important. The '*' on
                     its own is used to ensure a default fallback context is
                     assigned and should be the last entry in the
                     object_type block.
                     The security context that will be applied to the

       Example 1:

       # object_type  object_name  context
       selection      PRIMARY      system_u:object_r:clipboard_xselection_t:s0
       selection      *            system_u:object_r:xselection_t:s0

       Example 2 - This example shows how a client entry can be configured
       to ensure an entry is always found:

       # object_type  object_name  context
       client         *            system_u:object_r:remote_t:s0

NOTES         top

       1.  Properties and selections are marked as either polyinstantiated
           or not. For these name types, the "POLY" option searches only the
           names marked as being polyinstantiated, while the other option
           searches only the names marked as not being polyinstantiated.
           Users of the interface should check both mappings, optionally
           taking action based on the result (e.g. polyinstantiating the

       2.  If contexts are to be validated, then the global option
           SELABEL_OPT_VALIDATE must be set before calling selabel_open(3).
           If this is not set, then it is possible for an invalid context to
           be returned.

SEE ALSO         top

       selinux(8), selabel_open(3), selabel_lookup(3), selabel_stats(3),
       selabel_close(3), selinux_set_callback(3), selinux_x_context_path(3),
       freecon(3), selinux_config(5)

COLOPHON         top

       This page is part of the selinux (Security-Enhanced Linux user-space
       libraries and tools) project.  Information about the project can be
       found at ⟨⟩.  If you
       have a bug report for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-09-18.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-09-17.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

Security Enhanced Linux          29 Nov 2011                    selabel_x(5)

Pages that refer to this page: selabel_close(3)selabel_open(3)