reference_policy.md

The Reference Policy

• Reference Policy Overview
  • Distributing Policies
  • Policy Functionality
  • Reference Policy Module Files
• Reference Policy Source
  • Source Layout
  • Reference Policy Files and Directories
  • Source Configuration Files
    • Reference Policy Build Options - build.conf
    • Reference Policy Build Options - policy/modules.conf
      • Building the modules.conf File
  • Source Installation and Build Make Options
  • Booleans, Global Booleans and Tunable Booleans
  • Modular Policy Build Structure
    • Base Module Build
    • Module Build
  • Creating Additional Layers
• Installing and Building the Reference Policy Source
  • Building Standard Reference Policy
  • Building the Fedora Policy
• Reference Policy Headers
  • Building and Installing the Header Files
  • Using the Reference Policy Headers
  • Using Fedora Supplied Headers
• Reference Policy Support Macros
  • Loadable Policy Macros
    • policy_module Macro
    • gen_require Macro
    • optional_policy Macro
    • gen_tunable Macro
    • tunable_policy Macro
    • interface Macro
    • template Macro
  • Miscellaneous Macros
    • gen_context Macro
    • gen_user Macro
    • gen_bool Macro
  • MLS and MCS Macros
    • gen_cats Macro
    • gen_sens Macro
    • gen_levels Macro
  • ifdef / ifndef Parameters
    • hide_broken_symptoms
    • enable_mls and enable_mcs
    • enable_ubac
    • direct_sysadm_daemon
• Module Expansion Process

The Reference Policy is now the standard policy source used to build Linux SELinux policies. This provides a single source tree with supporting documentation that can be used to build policies for different purposes such as: confining important daemons, supporting MLS / MCS type policies and locking down systems so that all processes are under SELinux control.

This section details how the Reference Policy is:

1. Constructed and types of policy builds supported.
2. Adding new modules to the build.
3. Installation as a full Reference Policy source or as Header files.
4. Impact of the migration process being used to convert compiled module files (*.pp) to CIL.
5. Modifying the configuration files to build new policies.
6. Explain the support macros.

Note that the Reference Policy uses NAME to define the policy name. This then becomes part of the policy location (i.e. /etc/selinux/<NAME>). In most documentation the policy name is defined using the <SELINUXTYPE> convention, as that is from the /etc/selinux/config file entry SELINUXTYPE=. This part of the Notebook uses both forms.

Reference Policy Overview

Strictly speaking the 'Reference Policy' should refer to the policy taken from the master repository or the latest released version. This is because most Linux distributors take a released version and then tailor it to their specific requirements.

All examples in this section are based on the master Reference Policy repository that can be checked out using the following:

# Check out the core policy:
git clone https://github.com/SELinuxProject/refpolicy.git

A list of releases can be found at https://github.com/SELinuxProject/refpolicy/releases

The Fedora distribution is built from a specific standard Reference Policy build, modified and distributed by Red Hat as a source RPM. These RPMs can be obtained from http://koji.fedoraproject.org. The master Fedora policy source can be found at: https://github.com/fedora-selinux/selinux-policy

Figure 26: The Reference Policy Source Tree shows the layout of the reference policy source tree, that once installed would be located at

/etc/selinux/<SELINUXTYPE>/src/policy

Where the <SELINUXTYPE> entry is taken from the build.conf file as discussed in the Reference Policy Build Options - build.conf section. The Installing and Building the Reference Policy Source section explains a simple build from source.

Figure 26: The Reference Policy Source Tree - When building a modular policy, files are added to the policy store. For monolithic builds the policy store is not used.

The Reference Policy can be used to build two policy types:

1. Loadable Module Policy - A policy that has a base module for core services and has the ability to load / unload modules to support applications as required. This is now the standard used by Linux distributions.
2. Monolithic Policy - A policy that has all the required policy information in a single base policy and does not require the services of the module infrastructure (semanage(8) or semodule(8)). These are more suitable for embedded or minimal systems.

Each of the policy types are built using module files that define the specific rules required by the policy as detailed in the Reference Policy Module Files section. Note that the monolithic policy is built using the same module files by forming a single 'base' source file.

The Reference Policy relies heavily on the m4(1) macro processor as the majority of supporting services are m4 macros.

Distributing Policies

It is possible to distribute the Reference Policy in two forms:

1. As source code that is then used to build policies. This is not the general way policies are distributed as it contains the complete source that most administrators do not need. The Reference Policy Source section describes the source and the Installing and Building the Reference Policy Source section describes how to install the source and build a policy.
2. As 'Policy Headers'. This is the most common way to distribute the Reference Policy. Basically, the modules that make up 'the distribution' are pre-built and then linked to form a base and optional modules. The 'headers' that make-up the policy are then distributed along with makefiles and documentation. A policy writer can then build policy using the core modules supported by the distribution, and using development tools they can add their own policy modules. The Reference Policy Headers section describes how these are installed and used to build modules.

The policy header files and documentation for Fedora are distributed in:

• selinux-policy - Contains the SELinux /etc/selinux/config file and rpm macros
• selinux-policy-devel - Contains the 'Policy Header' development environment that is located at /usr/share/selinux/devel
• selinux-policy-doc - Contains man pages and the html policy documentation that is located at /usr/share/doc/selinux-policy/html

These rpms contain a specific policy type containing configuration files and packaged policy modules (*.pp). The policy will be installed in the /etc/selinux/<SELINUXTYPE> directory, along with its configuration files.

• selinux-policy-targeted - This is the default Fedora policy.
• selinux-policy-minimum
• selinux-policy-mls

The selinux-policy-sandbox rpm contains the sandbox module for use by the policycoreutils-sandbox package. This will be installed as a module for one of the three main policies described above.

Policy Functionality

As can be seen from the policies distributed with Fedora above, they can be classified by the name of the functionality they support (taken from the SELINUXTYPE entry of the build.conf as shown in the Reference Policy Build Options - build.conf section, for example the Fedora policies support:

• minimum - MCS policy that supports a minimal set of confined daemons within their own domains. The remainder run in the unconfined_t space.
• targeted - MCS policy that supports a greater number of confined daemons and can also confine other areas and users.
• mls - MLS policy for server based systems.

Reference Policy Module Files

The reference policy modules are constructed using a mixture of support macros, interface calls and Kernel Policy Language Statements, using three principle types of source file:

• A private policy file that contains statements required to enforce policy on the specific GNU / Linux service being defined within the module. These files are named <module_name>.te. For example the ada.te file shown below has two statements:
  • one to state that the ada_t process has permission to write to the stack and memory allocated to a file.
  • one that states that if the unconfined_domain module is loaded, then allow the ada_t domain unconfined access. Note that if the flow of this statement is followed it will be seen that many more interfaces and macros are called to build the final raw SELinux language statements. An expanded module source isshown in the Module Expansion Process section.
• An external interface file that defines the services available to other modules. These files are named <module_name>.if. For example the ada.if file shown below has two interfaces defined for other modules to call:
  • ada_domtrans - that allows another module (running in domain $1) to run the ada application in the ada_t domain.
  • ada_run - that allows another module to run the ada application in the ada_t domain (via the ada_domtrans interface), then associate the ada_t domain to the caller defined role ($2) and terminal ($3). Provided of course that the caller domain has permission. Note that there are two types of interface specification:
  • Access Interfaces - These are the most common and define interfaces that .te modules can call as described in the ada examples. They are generated by the interface macro as detailed in the interface section.
  • Template Interfaces - These are required whenever a module is required in different domains and allows the type(s) to be redefined by adding a prefix supplied by the calling module. The basic idea is to set up an application in a domain that is suitable for the defined SELinux user and role to access but not others. These are generated by the template macro as detailed in the template section.
• A file labeling file that defines the labels to be added to files for the specified module. These files are named <module_name>.fc. The build process will amalgamate all the *.fc files and finally form the file_contexts file that will be used to label the filesystem. For example the ada.fc file shown below requires that the specified files are labeled system_u:object_r:ada_exec_t:s0. The <module_name> must be unique within the reference policy source tree and should reflect the specific Linux service being enforced by the policy.

The following examples from the ada module files show how they are made from the Policy Macros, Interface calls and kernel policy statements and rules:

ada.te file contents:

policy_module(ada, 1.5.0)

########################################
#
# Declarations
#

attribute_role ada_roles;			# Kernel policy statement
roleattribute system_r ada_roles;

type ada_t;
type ada_exec_t;
application_domain(ada_t, ada_exec_t)		# call into 'application.if'
role ada_roles types ada_t;

########################################
#
# Local policy
#

allow ada_t self:process { execstack execmem };

userdom_use_inherited_user_terminals(ada_t)	# call into 'userdomain.if'

optional_policy(`				# Macro in loadable_module.spt
	unconfined_domain(ada_t)
')

ada.if 'interface calls' file contents:

## <summary>GNAT Ada95 compiler.</summary>

########################################
## <summary>
##	Execute the ada program in the ada domain.
## </summary>
## <param name="domain">
##	<summary>
##	Domain allowed to transition.
##	</summary>
## </param>
#
interface(*ada_domtrans',*			# Defining an interface
	gen_require(`				# Macro in loadable_module.spt
		type ada_t, ada_exec_t;
	')

	corecmd_search_bin($1)
	domtrans_pattern($1, ada_exec_t, ada_t)	# Macro in misc_patterns.spt
')

########################################
## <summary>
##	Execute ada in the ada domain, and
##	allow the specified role the ada domain.
## </summary>
## <param name="domain">
##	<summary>
##	Domain allowed to transition.
##	</summary>
## </param>
## <param name="role">
##	<summary>
##	Role allowed access.
##	</summary>
## </param>
#
interface(*ada_run',*
	gen_require(`
		attribute_role ada_roles;
	')

	ada_domtrans($1)
	roleattribute $2 ada_roles;		# Kernel policy statement
')

ada.fc file contents:

				# gen_context is a macro in misc_macros.spt
/usr/bin/gnatbind	--	gen_context(system_u:object_r:ada_exec_t,s0)
/usr/bin/gnatls	--	gen_context(system_u:object_r:ada_exec_t,s0)
/usr/bin/gnatmake	--	gen_context(system_u:object_r:ada_exec_t,s0)

/usr/libexec/gcc(/.*)?/gnat1	--	gen_context(system_u:object_r:ada_exec_t,s0)

Reference Policy Documentation

One of the advantages of the reference policy is that it is possible to automatically generate documentation as a part of the build process. This documentation is defined in XML and generated as HTML files suitable for viewing via a browser.

The documentation for Fedora can be viewed in a browser using /usr/share/doc/selinux-policy/html/index.html once the selinux-policy-doc rpm has been installed. The documentation for the Reference Policy source will be available at <location>/src/policy/doc/html once make html has been executed (the <location> is the location of the installed source after make install-src has been executed as described in the Installing and Building the Reference Policy Source section). The Reference Policy documentation may also be available at a default location of /usr/share/doc/refpolicy-<VERSION>/html if make install-doc has been executed (where <VERSION/> is the entry from the source VERSION file.

Figure 27 shows an example screen shot of the documentation produced for the ada module interfaces.

Figure 27: Example Documentation Screen Shot

Reference Policy Source

This section explains the source layout and configuration files, with the actual installation and building covered in the Installing and Building the Reference Policy Source section.

The source has a README file containing information on the configuration and installation processes that has been used within this section (and updated with the authors comments as necessary). There is also a VERSION file that contains the Reference Policy release date, this can then be used to obtain a change list https://github.com/SELinuxProject/refpolicy/releases.

Source Layout

Figure 26: The Reference Policy Source Tree shows the layout of the reference policy source tree, that once installed would be located at:

/etc/selinux/<SELINUXTYPE>/src/policy

The following sections detail the source contents:

• Reference Policy Files and Directories - Describes the files and their location.
• Source Configuration Files - Details the contents of the build.conf and modules.conf configuration files.
• Source Installation and Build Make Options - Describes the make targets.
• Modular Policy Build Structure - Describes how the various source files are linked together to form a base policy module base.conf during the build process.

The Installing and Building the Reference Policy Source section then describes how the initial source is installed and configured to allow a policy to be built.

Reference Policy Files and Directories

The Reference Policy Files and Directories list shows the major files and their directories with a description of each taken from the README file (with comments added). All directories are relative to the root of the Reference Policy source directory ./policy.

The build.conf and modules.conf configuration files are further detailed in the Source Configuration Files section as they define how the policy will be built.

During the build process, a file is generated in the ./policy directory called either policy.conf or base.conf depending whether a monolithic or modular policy is being built. This file is explained in the Modular Policy Build Structure section.

Reference Policy Files and Directories:

Makefile

• General rules for building the policy.

Rules.modular

• Makefile rules specific to building loadable module policies.

Rules.monolithic

• Makefile rules specific to building monolithic policies.

build.conf

• Options which influence the building of the policy, such as the policy type and distribution. This file is described in the Reference Policy Build Options - build.conf section.

config/appconfig-<type>

• Application configuration files for all configurations of the Reference Policy where <type> is taken from the build.conf TYPE entry that are currently: standard, MLS and MCS). These files are used by SELinux-aware programs and described in the SELinux Configuration Files section.

config/file_contexts.subs_dist

• Used to configure file context aliases (see the contexts/files/file_contexts.subs and file_contexts.subs_dist File section).

config/local.users

• The file read by load policy for adding SELinux users to the policy on the fly. Note that this file is not used in the modular policy build.

doc/html/*

• When make html has been executed, contains the in-policy XML documentation, presented in web page form.

doc/policy.dtd

• The doc/policy.xml file is validated against this DTD.

doc/policy.xml

• This file is generated/updated by the conf and html make targets. It contains the complete XML documentation included in the policy.

doc/templates/*

• Templates used for documentation web pages.

man/*

• Various man pages for modules (ftp, http etc.)

support/*

• Tools used in the build process.

policy/flask/initial_sids

• This file has declarations for each initial SID. The file usage in policy generation is described in the Modular Policy Build Structure section.

policy/flask/security_classes

• This file has declarations for each security class. The file usage in policy generation is described in the Modular Policy Build Structure section.

policy/flask/access_vectors

• This file defines the common permissions and class specific permissions and is described in the Modular Policy Build Structure section.

policy/modules/*

• Each directory represents a layer in Reference Policy. All of the modules are contained in one of these layers. The contrib modules are supplied externally to the Reference Policy, then linked into the build. The files present in each directory are: metadata.xml that describes the layer and <module_name>.te, .if and .fc that contain policy source as described in the Reference Policy Module Files section. The file usage in policy generation is described in the Modular Policy Build Structure section.

policy/support/*

• Reference Policy support macros are described in the Reference Policy support Macros section.

policy/booleans.conf

• This file is generated/updated by make conf. It contains the booleans in the policy and their default values. If tunables are implemented as booleans, tunables will also be included. This file will be installed as the /etc/selinux/<NAME>/booleans file (note that this is not true for any system that implements the modular policy - see the Booleans, Global Booleans and Tunable Booleans section).

policy/constraints

• This file defines constraints on permissions in the form of boolean expressions that must be satisfied in order for specified permissions to be granted. These constraints are used to further refine the type enforcement rules and the role allow rules. Typically, these constraints are used to restrict changes in user identity or role to certain domains. (Note that this file does not contain the MLS / MCS constraints as they are in the mls and mcs files described below). The file usage in policy generation is described in the Modular Policy Build Structure section.

policy/context_defaults

• This would contain any specific default_user, default_role, default_type and/or default_range rules required by the policy.

policy/global_booleans

• This file defines all booleans that have a global scope, their default value, and documentation. See the Booleans, Global Booleans and Tunable Booleans section.

policy/global_tunables

• This file defines all tunables that have a global scope, their default value, and documentation. See the Booleans, Global Booleans and Tunable Booleans section.

policy/mcs

• This contains information used to generate the sensitivity, category, level and mlsconstraint statements used to define the MCS configuration. The file usage in policy generation is described in the Modular Policy Build Structure section.

policy/mls

• This contains information used to generate the sensitivity, category, level and mlsconstraint statements used to define the MLS configuration. The file usage in policy generation is described in the Modular Policy Build Structure section.

policy/modules.conf

• This file contains a listing of available modules, and how they will be used when building Reference Policy. To prevent a module from being used, set the module to "off". For monolithic policies, modules set to "base" and "module" will be included in the policy. For modular policies, modules set to "base" will be included in the base module; those set to "module" will be compiled as individual loadable modules. This file is described in the Reference Policy Build Options - policy/modules.conf section.

policy/policy_capabilities

• This file defines the policy capabilities that can be enabled in the policy. The file usage in policy generation is described in the Modular Policy Build Structure section.

policy/users

• This file defines the users included in the policy. The file usage in policy generation is described in the Modular Policy Build Structure section.

securetty_types and setrans.conf

• These files are not part of the standard Reference Policy distribution but are added by Fedora source updates.

Source Configuration Files

There are two major configuration files (build.conf and modules.conf) that define the policy to be built and are detailed in this section.

Reference Policy Build Options - build.conf

This file defines the policy type to be built that will influence its name and where the source will be located once it is finally installed. An example file content is shown in the Installing and Building the Reference Policy Source section where it is used to install and then build the policy.

The build.conf Entries below explains the fields that can be defined within this file. The supplied fields will then be used by the make process to set m4 macro parameters. These macro definitions are also used within the module source files to control how the policy is built with examples shown in the ifdef section.

build.conf Entries:

TYPE

• String - Available options are standard, mls, and mcs. For a type enforcement only system, set standard. This optionally enables multi-level security (MLS) or multi-category security (MCS) features. This option controls enable_mls, and enable_mcs policy blocks.

NAME

• String (optional) - Sets the name of the policy; the <NAME> is used when installing files to e.g., /etc/selinux/<NAME> and /usr/share/selinux/<NAME>. If not set, the policy type (TYPE) is used.

DISTRO

• String (optional) - Enable distribution-specific policy. Available options are redhat, gentoo, and debian. This option controls distro_redhat, distro_gentoo, and distro_debian build option policy blocks.

MONOLITHIC

• Boolean - If set, a monolithic policy is built, otherwise a modular policy is built.

DIRECT_INITRC

• Boolean - If set, sysadm will be allowed to directly run init scripts, instead of requiring the run_init tool. This is a build option instead of a tunable since role transitions do not work in conditional policy. This option controls direct_sysadm_daemon policy blocks.

OUTPUT_POLICY

• Integer - Set the version of the policy created when building a monolithic policy. This option has no effect on modular policy.

UNK_PERMS

• String - Set the kernel behavior for handling of permissions defined in the kernel but missing from the policy. The permissions can either be allowed (allow), denied (deny), or the policy loading can be rejected (reject).

UBAC

• Boolean - If set, the SELinux user will be used additionally for approximate role separation.

SYSTEMD

• Boolean - If set, systemd(1) will be assumed to be the init process provider.

MLS_SENS

• Integer - Set the number of sensitivities in the MLS policy. Ignored on TYPE entries of standard and mcs.

MLS_CATS

• Integer - Set the number of categories in the MLS policy. Ignored on TYPE entries of standard and mcs.

MCS_CATS

• Integer - Set the number of categories in the MCS policy. Ignored on TYPE entries of standard and mls.

QUIET

• Boolean - If set, the build system will only display status messages and error messages. This option has no effect on policy.

WERROR

• Boolean - If set, the build system will treat warnings as errors. If any warnings are encountered, the build will fail.

Reference Policy Build Options - policy/modules.conf

This file will not be present until make conf is run and controls what modules are built within the policy, see the Building the modules.conf File section.

Example entries:

# Layer: kernel
# Module: kernel
# Required in base
#
# Policy for kernel threads, proc filesystem,and unlabeled processes and
# objects.
#
kernel = base

# Layer: admin
# Module: amanda
#
# Advanced Maryland Automatic Network Disk Archiver.
#
amanda = module

# Layer: admin
# Module: ddcprobe
#
# ddcprobe retrieves monitor and graphics card information
#

ddcprobe = off

The only active lines (those without comments) contain:

<module_name> = base | module | off

However note that the comments are important as they form part of the documentation when it is generated by the make html target.

Where:

module_name

• The name of the module to be included within the build.

base

• The module will be in the base module for a modular policy build (build.conf entry MONOLITHIC = n).

module

• The module will be built as a loadable module for a modular policy build. If a monolithic policy is being built (build.conf entry MONOLITHIC = y), then this module will be built into the base module.

off

• The module will not be included in any build.

Generally it is up to the policy distributor to decide which modules are in the base and those that are loadable, however there are some modules that MUST be in the base module. To highlight this there is a special entry at the start of the modules interface file (.if) that has the entry <required val="true"> as shown below (taken from the kernel.if file):

## <summary>
##	Policy for kernel threads, proc filesystem,
##	and unlabeled processes and objects.
## </summary>
## <required val="true">
##	This module has initial SIDs.
## </required>

The modules.conf file will also reflect that a module is required in the base by adding a comment 'Required in base' when the make conf target is executed (as all the .if files are checked during this process and the modules.conf file updated).

# Layer: kernel
# Module: kernel
# Required in base
#
# Policy for kernel threads, proc filesystem,
# and unlabeled processes and objects.
#
kernel = base

Those marked as Required in base are shown in the Mandatory modules.conf Entries (note that Fedora and the standard Reference Policy may be different)

Mandatory modules.conf Entries: 'Layer - Module Name - Comments'

kernel

• corecommands

  • Core policy for shells and generic programs in: /bin, /sbin, /usr/bin, and /usr/sbin. The .fc file sets up the labels for these items.
  • All the interface calls start with 'corecmd_'.

• corenetwork

  • Policy controlling access to network objects and also contains the initial SIDs for these. The .if file is large and automatically generated.
  • All the interface calls start with 'corenet_'.

• devices

  • This module creates the device node concept and provides the policy for many of the device files. Notable exceptions are the mass storage and terminal devices that are covered by other modules (that is a char or block device file, usually in /dev). All types that are used to label device nodes should use the dev_node macro. Additionally this module controls access to:
    1. the device directories containing device nodes.
    2. device nodes as a group
    3. individual access to specific device nodes covered by this module.
  • All the interface calls start with 'dev_'.

• domain

  • Contains the core policy for forming and managing domains.
  • All the interface calls start with 'domain_'.

• files

  • This module contains basic filesystem types and interfaces and includes:
    1. The concept of different file types including basic files, mount points, tmp files, etc.
    2. Access to groups of files and all files.
    3. Types and interfaces for the basic filesystem layout (/, /etc, /tmp ...).
    4. Contains the file initial SID.
  • All the interface calls start with 'files_'.

• filesystem

  • Contains the policy for filesystems and the initial SID.
  • All the interface calls start with 'fs_'.

• kernel

  • Contains the policy for kernel threads, proc filesystem, and unlabeled processes and objects. This module has initial SIDs.
  • All the interface calls start with 'kernel_'.

• mcs

  • Policy for Multicategory security. The .te file only contains attributes used in MCS policy.
  • All the interface calls start with 'mcs_'.

• mls

  • Policy for Multilevel security. The .te file only contains attributes used in MLS policy. All the interface calls start with 'mls_'.

• selinux

  • Contains the policy for the kernel SELinux security interface (selinuxfs).
  • All the interface calls start with 'selinux_'.

• terminal

  • Contains the policy for terminals.
  • All the interface calls start with 'term_'.

• ubac

  • Disabled by Fedora but enabled on standard Ref Policy. Support user-based access control.

system

• application

  • Enabled by Fedora but not standard Ref Policy. Defines attributes and interfaces for all user apps.

• setrans

  • Enabled by Fedora but not standard Ref Policy. Support for mcstransd(8).

Building the modules.conf File

The file can be created by an editor, however it is generally built initially by make conf that will add any additional modules to the file. The file can then be edited to configure the required modules as base, module or off.

As will be seen in the Installing and Building the Reference Policy Source section, the Fedora reference policy source comes with a number of pre-configured files that are used to produce the required policy including multiple versions of the modules.conf file.

Source Installation and Build Make Options

This section explains the various make options available that have been taken from the README file (with some additional minor comments).

General Make targets:

install-src

• Install the policy sources into /etc/selinux/<NAME>/src/policy, where <NAME> is defined in the build.conf file. If it is not defined, then TYPE is used instead. If a build.conf does not have the information, then the Makefile will default to the current entry in the /etc/selinux/config file or default to refpolicy. A pre-existing source policy will be moved to /etc/selinux/<NAME>/src/policy.bak.

conf

• Regenerate policy.xml, and update/create modules.conf and booleans.conf. This should be done after adding or removing modules, or after running the bare target. If the configuration files exist, their settings will be preserved. This must be run on policy sources that are checked out from the CVS repository before they can be used. Note that if make bare has been executed before this make target, or it is a first build, then the modules/kernel/corenetwork.??.in files will be used to generate the corenetwork.te and corenetwork.if module files. These *.in files may be edited to configure network ports etc. (see the # network_node example entries in corenetwork.te).

clean

• Delete all temporary files, compiled policy, and file_contexts. Configuration files are left intact.

bare

• Do the clean make target and also delete configuration files, web page documentation, and policy.xml.

html

• Regenerate policy.xml and create web page documentation in the doc/html directory.

install-appconfig

• Installs the appropriate SELinux-aware configuration files.

Make targets specific to modular (loadable modules) policies:

base

• Compile and package the base module. This is the default target for modular policies.

modules

• Compile and package all Reference Policy modules configured to be built as loadable modules.

MODULENAME.pp

• Compile and package the MODULENAME Reference Policy module.

all

• Compile and package the base module and all Reference Policy modules configured to be built as loadable modules.

install

• Compile, package, and install the base module and Reference Policy modules configured to be built as loadable modules.

load

• Compile, package, and install the base module and Reference Policy modules configured to be built as loadable modules, then insert them into the module store.

validate

• Validate if the configured modules can successfully link and expand.

install-headers

• Install the policy headers into /usr/share/selinux/<NAME>. The headers are sufficient for building a policy module locally, without requiring the complete Reference Policy sources. The build.conf settings for this policy configuration should be set before using this target.

install-docs

• Build and install the documentation and example module source with Makefile. The default location is /usr/share/doc/refpolicy-<VERSION>, where the version is the value in the VERSION file.

Make targets specific to monolithic policies:

policy

• Compile a policy locally for development and testing. This is the default target for monolithic policies.

install

• Compile and install the policy and file contexts.

load

• Compile and install the policy and file contexts, then load the policy.

enableaudit

• Remove all dontaudit rules from policy.conf.

relabel

• Relabel the filesystem.

checklabels

• Check the labels on the filesystem, and report when a file would be relabeled, but do not change its label.

restorelabels

• Relabel the filesystem and report each file that is relabeled.

Booleans, Global Booleans and Tunable Booleans

The three files booleans.conf, global_booleans and global_tunables are built and used as follows:

booleans.conf

• This file is generated / updated by make conf, and contains all the booleans in the policy with their default values. If tunable and global booleans are implemented then these are also included. This file can also be delivered as a part of the Fedora reference policy source as shown in the Installing and Building the Reference Policy Source section. This is generally because other default values are used for booleans and not those defined within the modules themselves (i.e. distribution specific booleans). When the make install is executed, this file will be used to set the default values. Note that if booleans are updated locally the policy store will contain a booleans.local file.

global_booleans

• These are booleans that have been defined in the global_tunables file using the gen_bool macro. They are normally booleans for managing the overall policy and currently consist of the following (where the default values are false): secure_mode

global_tunables

• These are booleans that have been defined in module files using the gen_tunable macro and added to the global_tunables file by make conf. The tunable_policy macros are defined in each module where policy statements or interface calls are required. They are booleans for managing specific areas of policy that are global in scope. An example is allow_execstack that will allow all processes running in unconfined_t to make their stacks executable.

Modular Policy Build Structure

This section explains the way a modular policy is constructed, this does not really need to be known but is used to show the files used that can then be investigated if required.

When make all or make load or make install are executed the build.conf and modules.conf files are used to define the policy name and what modules will be built in the base and those as individual loadable modules.

Basically the source modules (.te, .if and .fc) and core flask files are rebuilt in the tmp directory where the reference policy macros in the source modules will be expanded to form actual policy language statements as described in the Kernel Policy Language section. The Base Module Build section shows these temporary files that are used to form the base.conf (for modular policies) or the policy.conf (for a monolithic policy) file during policy generation.

The base.conf file will consist of language statements taken from the module defined as base in the modules.conf file along with the constraints, users etc. that are required to build a complete policy.

The individual loadable modules are built in much the same way as shown in the Module Build section.

Base Module Build

The following shows the temporary build files used to build the base module base.conf as a part of the make process.

tmp/pre_te_files.conf

• policy/flask/security_classes
  • The object classes supported by the kernel
• policy/flask/initial_sids
  • The initial SIDs supported by the kernel.
• policy/flask/access_vectors
  • The object class permissions supported by the kernel.
• policy/mls or policy/mcs
  • This is either the expanded mls or mcs file depending on the type of policy being built.
• policy/policy_capabilities
  • These are the policy capabilities that can be configured / enabled to support the policy.

tmp/all_attrs_types.conf

• policy/modules/*/*.te and policy/modules/*/*.if
  • This area contains all the attribute, bool, type and typealias statements extracted from the .te and .if files that form the base module.

tmp/global_bools.conf

• policy/global_tunables.conf and policy/global_bools.conf
  • Contains the global and tunable bools extracted from the conf files.

tmp/only_te_rules.conf

• policy/modules
  • Contains the rules extracted from each of the modules .te and .if files defined in the modules.conf file as base.

tmp/all_post.conf

• policy/users
  • Contains the expanded users from the users file.
• policy/constraints
  • Contains the expanded constraints from the constraints file.
• policy/modules/*/*.te
  • Contains the default SID labeling extracted from the .te files.
• policy/modules/*/*.te and policy/modules/*/*.if
  • Contains the fs_use_xattr, fs_use_task, fs_use_trans and genfscon statements extracted from each of the modules .te and .if files defined in the modules.conf file as base.
  • Contains the netifcon, nodecon and portcon statements extracted from each of the modules .te and .if files defined in the modules.conf file as base.

tmp/base.fc.tmp

• policy/modules/*/*.fc
  • Contains the expanded file context file entries extracted from the .fc files defined in the modules.conf file as base.

tmp/seusers

• policy/seusers
  • Expanded seusers file.

These are the commands used to compile, link and load the base policy module, where UNK_PERMS and NAME are those defined in the build.conf file:

semodule_package -o $@ -m $(base_mod) -f $(base_fc) -u $(users_extra) -s $(tmpdir)/seusers
...
checkmodule -U $(UNK_PERMS) base.conf -o tmp/base.mod*
...
semodule -s $(NAME) -i $(modpkgdir)/$(notdir $(base_pkg)) $(foreach mod,$(mod_pkgs),-i $(modpkgdir)/$(mod))

Module Build

The following shows the temporary module files used to build each module as a part of the make process (i.e. those modules marked as module in modules.conf).

tmp/<module_name>.tmp

• policy/modules/*/<module_name>.te and policy/modules/*/<module_name>.if
  • For each module defined as module in the modules.conf configuration file, a source module is produced that has been extracted from the .te and .if files for that module.

tmp<module_name>.mod

• tmp/<module_name>.tmp
  • For each module defined as module in the modules.conf configuration file, an object module is produced from executing the checkmodule(8) command shown below.

tmp/<module_name>.fc.tmp

• policy/modules/*/<module_name>.fc
  • For each module defined as module in the modules.conf configuration file, an expanded file context file is built.

These are the commands (from Rules.modular) is used to build each module and insert it into the module store, where NAME is that defined in the build.conf file:

checkmodule -m $(@:.mod=.tmp) -o $@
...
semodule_package -o $@ -m $< -f $<.fc
...
semodule -s $(NAME) -i $(modpkgdir)/$(notdir $(base_pkg)) $(foreach mod,$(mod_pkgs),-i $(modpkgdir)/$(mod))

Creating Additional Layers

One objective of the reference policy is to separate the modules into different layers reflecting their 'service' (e.g. kernel, system, app etc.). While it can sometimes be difficult to determine where a particular module should reside, it does help separation, however because the way the build process works, each module must have a unique name.

If a new layer is required, then the following will need to be completed:

1. Create a new layer directory ./policy/modules/LAYERNAME that reflects the layer's purpose.
2. In the ./policy/modules/LAYERNAME directory create a metadata.xml file. This is an XML file with a summary tag and optional desc (long description) tag that should describe the purpose of the layer and will be used as a part of the documentation. An example is as follows:

<summary>ABC modules for the XYZ components.</summary>

Installing and Building the Reference Policy Source

This section will give a brief overview of how to build the Reference Policy for an MCS modular build that is similar (but not the same) as the Fedora targeted policy. The Fedora version of the targeted policy build is discussed but building without using the rpm spec file is more complex.

Building Standard Reference Policy

This will run through a simple configuration process and build of a reference policy similar to the Fedora targeted policy. By convention the source is installed in a central location and then for each type of policy a copy of the source is installed at /etc/selinux/<SELINUXTYPE>/src/policy.

The basic steps are:

• Install master Reference Policy Source:

# Check out the core policy:
git clone https://github.com/SELinuxProject/refpolicy.git

• Edit the build.conf file to reflect the policy to be built, the minimum required is setting the NAME = entry. An example file with NAME = refpolicy-test is as follows:

########################################
#
# Policy build options
#

# Policy version
# By default, checkpolicy will create the highest
# version policy it supports.  Setting this will
# override the version.  This only has an
# effect for monolithic policies.
#OUTPUT_POLICY = 18

# Policy Type
# standard, mls, mcs
# Note Red Hat always build the MCS Policy Type for their 'targeted' version.
TYPE = mcs

# Policy Name
# If set, this will be used as the policy
# name.  Otherwise the policy type will be
# used for the name.
# This entry is also used by the 'make install-src' process to copy the
# source to the /etc/selinux/<NAME>/src/policy directory.
NAME = refpolicy-test

# Distribution
# Some distributions have portions of policy
# for programs or configurations specific to the
# distribution.  Setting this will enable options
# for the distribution.
# redhat, gentoo, debian, suse, and rhel4 are current options.
# Fedora users should enable redhat.
DISTRO = redhat

# Unknown Permissions Handling
# The behavior for handling permissions defined in the
# kernel but missing from the policy.  The permissions
# can either be allowed, denied, or the policy loading
# can be rejected.
# allow, deny, and reject are current options.
# Fedora use allow for all policies except MLS that uses 'deny'.
UNK_PERMS = deny

# Direct admin init
# Setting this will allow sysadm to directly
# run init scripts, instead of requiring run_init.
# This is a build option, as role transitions do
# not work in conditional policy.
DIRECT_INITRC = n

# Systemd
# Setting this will configure systemd as the init system.
SYSTEMD = y

# Build monolithic policy.  Putting y here
# will build a monolithic policy.
MONOLITHIC = n

# User-based access control (UBAC)
# Enable UBAC for role separations.
# Note Fedora disables UBAC.
UBAC = n

# Custom build options.  This field enables custom
# build options.  Putting foo here will enable
# build option blocks named foo.  Options should be
# separated by spaces.
CUSTOM_BUILDOPT =

# Number of MLS Sensitivities
# The sensitivities will be s0 to s(MLS_SENS-1).
# Dominance will be in increasing numerical order
# with s0 being lowest.
MLS_SENS = 16

# Number of MLS Categories
# The categories will be c0 to c(MLS_CATS-1).
MLS_CATS = 1024

# Number of MCS Categories
# The categories will be c0 to c(MLS_CATS-1).
MCS_CATS = 1024

# Set this to y to only display status messages
# during build.
QUIET = n

# Set this to treat warnings as errors.
WERROR = n

• Run make install-src to install source at policy build location.
• Change to the /etc/selinux/<SELINUXTYPE>/src/policy directory where an unconfigured basic policy has been installed.
• Run make conf to build an initial policy/booleans.conf and policy/modules.conf files. For this simple configuration these files will not be edited.
  • This process will also build the policy/modules/kernel/corenetwork.te and corenetwork.if files if not already present. These would be based on the contents of corenetwork.te.in and corenetwork.if.in configuration files (for this simple configuration these files will not be edited).
• Run make load to build the policy, add the modules to the store and install the binary kernel policy plus its supporting configuration files.
• As the Reference Policy has NOT been tailored specifically for Fedora, it MUST be run in permissive mode.
• The policy should now be built and can be checked using tools such as apol(8) or loaded by editing the /etc/selinux/config file, running 'touch /.autorelabel' and rebooting the system.

Building the Fedora Policy

Note, the Fedora selinux-policy started life as Reference Policy Version: 2.20130424 and, is now basically a large patch on top of the original Reference Policy.

Building Fedora policies by hand is complex as they use the rpmbuild/SPECS/selinux-policy.spec file, therefore this section will give an overview of how this can be achieved, the reader can then experiment (the spec file gives an insight). The build process assumes that an equivalent 'targeted' policy will be built named 'targeted-FEDORA'.

Note: The following steps were tested on Fedora 31 with no problems.

Install the source as follows:

rpm -Uvh selinux-policy-<version>.src.rpm

The rpmbuild/SOURCES directory contents that will be used to build a copy of the targeted policy are as follows (there are other files, however they are not required for this exercise):

selinux-policy-<commit_num>.tar.gz

• The Reference Policy version 2.20130424 with Fedora specific updates that should be unpacked into: rpmbuild/SOURCES/selinux-policy-<commit_num>

selinux-policy-contrib-<commit_num>.tar.gz

• The Reference Policy contribution modules. Unpack the files and install them into: rpmbuild/SOURCES/selinux-policy-<commit_num>/policy/modules/contrib

container-selinux.tgz

• Fedora Containers module. Unpack and then install into: rpmbuild/SOURCES/selinux-policy-<commit_num>/policy/modules/contrib

permissivedomains.cil

• Badly named file – just adds system_r to roleattributeset. Copy this to *rpmbuild/SOURCES/selinux-policy-<commit_num> as it will be installed by semodule once the policy has been built.

modules-targeted-base.conf and modules-targeted-contrib.conf

• Concatenate both files and copy this to become: rpmbuild/SOURCES/selinux-policy-<commit_num>/policy/modules.conf

booleans-targeted.conf

• Replace the rpmbuild/SOURCES/selinux-policy-<commit_num>/policy/booleans.conf file with this version.

securetty_types-targeted

• Replace the rpmbuild/SOURCES/selinux-policy-<commit_num>/config/appconfig-mcs/securetty_types file with this version.

users-targeted

• Replace the rpmbuild/SOURCES/selinux-policy-<commit_num>/policy/users file with this version.

The basic steps to build are:

• Edit the rpmbuild/SOURCES/selinux-policy-<commit_num>build.conf file to reflect the policy to be built (as this is an earlier version of the Reference Policy it has less options than the current Reference Policy):

############################################
# Policy build options
#
# Policy version
# By default, checkpolicy will create the highest version policy it supports.
# Setting this will override the version. This only has an effect for
# monolithic policies.
#OUTPUT_POLICY = 18

# Policy Type
# standard, mls, mcs. Note Red Hat builds the MCS Policy Type
# for their 'targeted' version.
TYPE = mcs

# Policy Name
# If set, this will be used as the policy name. Otherwise the policy type
# will be used for the name. This entry is also used by the 'make install-src'
# process to copy the source to the:
#    /etc/selinux/<SELINUXTYPE>/src/policy directory.
NAME = targeted-FEDORA

# Distribution
# Some distributions have portions of policy for programs or configurations
# specific to the distribution. Setting this will enable options for the
# distribution. redhat, gentoo, debian, suse, and rhel4 are current options.
# Fedora users should enable redhat.
DISTRO = redhat

# Unknown Permissions Handling
# The behaviour for handling permissions defined in the kernel but missing
# from the policy. The permissions can either be allowed, denied, or
# the policy loading can be rejected.
# allow, deny, and reject are current options. Fedora use allow for all
# policies except MLS that uses 'deny'.
UNK_PERMS = allow

# Direct admin init
# Setting this will allow sysadm to directly run init scripts, instead of
# requiring run_init. This is a build option, as role transitions do not
# work in conditional policy.
DIRECT_INITRC = n

# Build monolithic policy. Putting y here will build a monolithic
policy.
MONOLITHIC = n

# User-based access control (UBAC)
# Enable UBAC for role separations. Note Fedora disables UBAC.
UBAC = n

# Custom build options. This field enables custom build options. Putting
# foo here will enable build option blocks foo. Options should be
separated by spaces.
CUSTOM_BUILDOPT =

# Number of MLS Sensitivities
# The sensitivities will be s0 to s(MLS_SENS-1). Dominance will be in
# increasing numerical order with s0 being lowest.
MLS_SENS = 16

# Number of MLS Categories.
# The categories will be c0 to c(MLS_CATS-1).
MLS_CATS = 1024

# Number of MCS Categories
# The categories will be c0 to c(MLC_CATS-1).
MCS_CATS = 1024

# Set this to y to only display status messages during build.
QUIET = n

• From rpmbuild/SOURCES/selinux-policy-<commit_num> run make conf to initialise the build (it creates two important files in ./selinux-policy-<commit_num>/policy/modules/kernel called corenetwork.te and corenetwork.if).
• From rpmbuild/SOURCES/selinux-policy-<commit_num> run make install-src to install source at policy build location.
• Change to the /etc/selinux/targeted-FEDORA/src/policy directory where the policy has been installed.
• Run make load to build the policy, add the modules to the store and install the binary kernel policy plus its supporting configuration files.
  • Note that the policy store will default to /var/lib/selinux/targeted-FEDORA, with the modules in active/modules/400/<module_name>, there will also be CIL versions of the modules.
• Install the permissivedomains.cil module as follows:
  • semodule -s targeted-FEDORA -i permissivedomains.cil
• The policy should now be built and can be checked using tools such as apol(8) or loaded by editing the /etc/selinux/config file (setting to permissive mode for safety), running 'touch /.autorelabel' and rebooting the system. It should have the same number of rules, types, classes etc. as the original release.

Reference Policy Headers

This method of building policy and adding new modules is used for distributions that do not require access to the source code.

Note that the Reference Policy header and the Fedora policy header installations are slightly different as described below.

Building and Installing the Header Files

To be able to fully build the policy headers from the reference policy source two steps are required:

1. Ensure the source is installed and configured as described in the Installing and Building the Reference Policy Source section. This is because the make load (or make install) command will package all the modules as defined in the modules.conf file, producing a base.pp and the relevant .pp packages. The build process will then install these in the /usr/share/selinux/<SELINUXTYPE> directory.
2. Execute the make install-headers that will:
   • Produce a build.conf file that represents the contents of the master build.conf file and place it in the /usr/share/selinux/<SELINUXTYPE>/include directory.
   • Produce the XML documentation set that reflects the source and place it in the /usr/share/selinux/<SELINUXTYPE>/include directory.
   • Copy a development Makefile for building from policy headers to the /usr/share/selinux/<SELINUXTYPE>/include directory.
   • Copy the support macros .spt files to the /usr/share/selinux/<SELINUXTYPE>/include/support directory. This will also include an all_perms.spt file that will contain macros to allow all classes and permissions to be resolved.
   • Copy the module interface files (.if) to the relevant module directories at: /usr/share/selinux/<SELINUXTYPE>/include/modules.

Using the Reference Policy Headers

Note that this section describes the standard Reference Policy headers, the Fedora installation is slightly different and described in the Using Fedora Supplied Headers section.

Once the headers are installed as defined above, new modules can be built in any local directory. An example set of module files are located in the reference policy source at /etc/selinux/<SELINUXTYPE>/src/policy/doc and are called example.te, example.if, and example.fc.

During the header build process a Makefile was included in the headers directory. This Makefile can be used to build the example modules by using makes -f option as follows (assuming that the example module files are in the local directory):

make -f /usr/share/selinux/<NAME>/include/Makefile

However there is another Makefile (./policy/doc Makefile.example) that can be installed in the users home directory ($HOME) that will call the master Makefile:

AWK ?= gawk

NAME ?= $(shell $(AWK) -F= '/^SELINUXTYPE/{ print $$2 }' /etc/selinux/config)
SHAREDIR ?= /usr/share/selinux
HEADERDIR := $(SHAREDIR)/$(NAME)/include

include $(HEADERDIR)/Makefile

The Header Policy Build Make Targets shows the make targets for modules built from headers.

Header Policy Build Make Targets:

MODULENAME.pp

• Compile and package the MODULENAME local module.

all

• Compile and package the modules in the current directory.

load

• Compile and package the modules in the current directory, then insert them into the module store.

refresh

• Attempts to reinsert all modules that are currently in the module store from the local and system module packages.

xml

• Build a policy.xml from the XML included with the base policy headers and any XML in the modules in the current directory.

Using Fedora Supplied Headers

The Fedora distribution installs the headers in a slightly different manner as Fedora installs (via the selinux-policy-devel rpm):

• A modules-base.lst and modules-contrib.lst containing a list of installed modules under /usr/share/selinux/<NAME>.
• The development header files are installed in the /usr/share/selinux/devel directory. The example modules are also in this directory and the Makefile is also slightly different to that used by the Reference Policy source.
• The documentation is installed in the /usr/share/doc/selinux-policy/html directory.

An example usage to build a policy module called ipsec_test_policy.te and insert this into the policy store is:

make -f /usr/share/selinux/devel/Makefile ipsec_test_policy.pp
semodule -i ipsec_test_policy.pp

Reference Policy Support Macros

This section explains some of the support macros used to build reference policy source modules. These macros are located at:

• ./policy/support for the reference policy source.
• /usr/share/selinux/<NAME>/include/support for Reference Policy installed header files.
• /usr/share/selinux/devel/support for Fedora installed header files.

The following support macro file contents are explained:

• loadable_module.spt - Loadable module support.
• misc_macros.spt - Generate users, bools and security contexts.
• mls_mcs_macros.spt - MLS / MCS support.
• file_patterns.spt - Sets up allow rules via parameters for files and directories.
• ipc_patterns.spt - Sets up allow rules via parameters for Unix domain sockets.
• misc_patterns.spt - Domain and process transitions.
• obj_perm_sets.spt - Object classes and permissions.

When the header files are installed the all_perms.spt support macro file is also installed that describes all classes and permissions configured in the original source policy.

Support Macros described in this section:

loadable_module.spt

• policy_module Macro

  • For adding the module statement and mandatory require block entries.

• gen_require Macro

  • For use in interfaces to optionally insert a require block.

• optional_policy Macro

  • Optional policy handling.

• gen_tunable Macro

  • Tunable declaration.

• tunable_policy Macro

  • Tunable policy handling.

• interface Macro

  • Generate the access interface block.

• template Macro

  • Generate template interface block.

misc_macros.spt

• gen_context Macro

  • Generate a security context.

• gen_user Macro

  • Generate an SELinux user.

• gen_bool Macro

  • Generate a boolean.

mls_mcs_macros.spt

• gen_cats Macro

  • Declares categories c0 to c(N-1).

• gen_sens Macro

  • Declares sensitivities s0 to s(N-1) with dominance in increasing numeric order with s0 lowest, s(N-1) highest.

• gen_levels Macro

  • Generate levels from s0 to (N-1) with categories c0 to (M-1).

Notes:

1. The macro calls can be in any configuration file read by the build process and can be found in (for example) the users, mls, mcs and constraints files.
2. There are four main m4 ifdef parameters used within modules:
   • enable_mcs - this is used to test if the MCS policy is being built.
   • enable_mls - this is used to test if the MLS policy is being built.
   • enable_ubac - this enables the user based access control within the constraints file.
   • hide_broken_symptoms - this is used to hide errors in modules with dontaudit rules.

These are also mentioned as they are set by the initial build process with examples shown in the ifdef section.

1. The macro examples in this section have been taken from the reference policy module files and shown in each relevant "Example Macro" section. The macros are then expanded by the build process to form modules containing the policy language statements and rules in the tmp directory. These files have been extracted and modified for readability, then shown in each relevant "Expanded Macro" section.
2. An example policy that has had macros expanded is shown in the Module Expansion Process section.
3. Be aware that spaces between macro names and their parameters are not allowed:

Correct:

policy_module(ftp, 1.7.0)

Incorrect:

policy_module (ftp, 1.7.0)

Loadable Policy Macros

The loadable policy module support macros are located in the loadable_module.spt file.

policy_module Macro

This macro will add the module to a loadable module, and automatically add a require with pre-defined information for all loadable modules such as the system_r role, kernel classes and permissions, and optionally MCS / MLS information (sensitivity and category statements).

The macro definition is:

policy_module(module_name,version)

Where:

policy_module

• The policy_module macro keyword.

module_name

• The module identifier that must be unique in the module layers.

version_number

• The module version number in M.m.m format (where M = major version number and m = minor version numbers). Since release 2.20220106 the version_number argument is optional. If missing '1' is set as a default to satisfy the policy syntax.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
Yes	No	No

Example Macro:

# This example is from the modules/services/ftp.te module:
#

policy_module(ftp, 1.23.0)

Expanded Macro:

# This is the expanded macro from the tmp/ftp.tmp file:
#
module ftp 1.23.0;

require {
	role system_r;
	class security {compute_av compute_create .... };
	....
	class capability2 (mac_override mac_admin };
	# If MLS or MCS configured then the:
	sensitivity s0;
	....
	category c0;
	....
}

gen_require Macro

For use within module files to insert a require block.

The macro definition is:

gen_require(`require_statements')

Where:

gen_require

• The gen_require macro keyword.

require_statements

• These statements consist of those allowed in the policy language require Statement.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
Yes	Yes	No

Example Macro:

# This example is from the modules/services/cron.te module:
#

gen_require(`class passwd rootok;')

Expanded Macro:

# This is the expanded macro from the tmp/cron.tmp file:
#

require {
	class passwd rootok;
}

optional_policy Macro

For use within module files to insert an optional block that will be expanded by the build process only if the modules containing the access or template interface calls that follow are present. If one module is present and the other is not, then the optional statements are not included.

The macro definition is:

optional_policy(`optional_statements')

Where:

optional_policy

• The optional_policy macro keyword.

optional_statements

• These statements consist of those allowed in the policy language optional Statement.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
Yes	Yes	No

Example Macro:

# This example is from the modules/services/ftp.te module and
# shows the optional_policy macro with two levels.
#

optional_policy(`
	corecmd_exec_shell(ftpd_t)

	files_read_usr_files(ftpd_t)

	cron_system_entry(ftpd_t, ftpd_exec_t)

	optional_policy(`
		logrotate_exec(ftpd_t)
	')
')

Expanded Macro:

# This is the expanded macro from the tmp/ftp.tmp file showing
# the policy language statements with both optional levels expanded.
#

optional {
	##### begin corecmd_exec_shell(ftpd_t) depth: 1
	require {
		type shell_exec_t;
		} # end require

		##### begin corecmd_list_bin(ftpd_t) depth: 2
		require {
			type bin_t;
			} # end require

			##### begin corecmd_search_bin(ftpd_t) depth: 3
			require {
				type bin_t;
			} # end require
			allow ftpd_t bin_t:dir { getattr search open };
			allow ftpd_t bin_t:lnk_file { getattr read };

				##### begin files_search_usr(ftpd_t) depth: 4
				require {
					type usr_t;
				} # end require
				allow ftpd_t usr_t:dir { getattr search open };
			##### end files_search_usr(ftpd_t) depth: 3
		##### end corecmd_search_bin(ftpd_t) depth: 2
		allow ftpd_t bin_t:dir { getattr search open };
		allow ftpd_t bin_t:dir { getattr search open read lock ioctl };
	##### end corecmd_list_bin(ftpd_t) depth: 1
	allow ftpd_t shell_exec_t:file { { getattr open map read execute ioctl } ioctl lock execute_no_trans };
	##### end corecmd_exec_shell(ftpd_t) depth: 0

	##### begin files_read_usr_files(ftpd_t) depth: 1
	require {
		type usr_t;
	} # end require
	allow ftpd_t usr_t:dir { getattr search open read lock ioctl };
	allow ftpd_t usr_t:dir { getattr search open };
	allow ftpd_t usr_t:file { getattr open read lock ioctl };
	allow ftpd_t usr_t:dir { getattr search open };
	allow ftpd_t usr_t:lnk_file { getattr read };
	##### end files_read_usr_files(ftpd_t) depth: 0

	##### begin cron_system_entry(ftpd_t,ftpd_exec_t) depth: 1
	require {
		type crond_t, system_cronjob_t;
		type user_cron_spool_log_t;
	} # end require
	allow ftpd_t user_cron_spool_log_t:dir { getattr search open };
	allow ftpd_t user_cron_spool_log_t:file { open { getattr read write append ioctl lock } };
	allow system_cronjob_t ftpd_exec_t:file { getattr open map read execute ioctl };
	allow system_cronjob_t ftpd_t:process transition;
	dontaudit system_cronjob_t ftpd_t:process { noatsecure siginh rlimitinh };
	type_transition system_cronjob_t ftpd_exec_t:process ftpd_t;
	allow ftpd_t system_cronjob_t:fd use;
	allow ftpd_t system_cronjob_t:fifo_file { getattr read write append ioctl lock };
	allow ftpd_t system_cronjob_t:process sigchld;
	allow crond_t ftpd_exec_t:file { getattr open map read execute ioctl };
	allow crond_t ftpd_t:process transition;
	dontaudit crond_t ftpd_t:process { noatsecure siginh rlimitinh };
	type_transition crond_t ftpd_exec_t:process ftpd_t;
	allow ftpd_t crond_t:fd use;
	allow ftpd_t crond_t:fifo_file { getattr read write append ioctl lock };
	allow ftpd_t crond_t:process sigchld;
	role system_r types ftpd_t;
	##### end cron_system_entry(ftpd_t,ftpd_exec_t) depth: 0
	optional {
		##### begin logrotate_exec(ftpd_t) depth: 1
		require {
			type logrotate_exec_t;
		} # end require

			##### begin corecmd_search_bin(ftpd_t) depth: 2
			require {
				type bin_t;
			} # end require
			allow ftpd_t bin_t:dir { getattr search open };
			allow ftpd_t bin_t:lnk_file { getattr read };

				##### begin files_search_usr(ftpd_t) depth: 3
				require {
					type usr_t;
				} # end require
				allow ftpd_t usr_t:dir { getattr search open };
			##### end files_search_usr(ftpd_t) depth: 2
		##### end corecmd_search_bin(ftpd_t) depth: 1

		allow ftpd_t logrotate_exec_t:file { { getattr open map read execute ioctl } ioctl lock execute_no_trans };

	##### end logrotate_exec(ftpd_t) depth: 0
	}
} # end optional

gen_tunable Macro

This macro defines booleans that are global in scope. The corresponding tunable_policy macro contains the supporting statements allowed or not depending on the value of the boolean. These entries are extracted as a part of the build process (by the make conf target) and added to the global_tunables file where they can then be used to alter the default values for the make load or make install targets.

Note that the comments shown in the example MUST be present as they are used to describe the function and are extracted for the documentation.

The macro definition is:

gen_tunable(`boolean_name',boolean_value)

Where:

gen_tunable

• The gen_tunable macro keyword.

boolean_name

• The boolean identifier.

boolean_value

The boolean value that can be either true or false.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
Yes	Yes	No

Example Macro:

# This example is from the modules/services/ftp.te module:

## <desc>
##	<p>
##	Determine whether ftpd can use NFS
##	used for public file transfer services.
##	</p>
## </desc>
gen_tunable(allow_ftpd_use_nfs, false)

Expanded Macro:

# This is the expanded macro from the tmp/ftp.tmp file:
#

bool allow_ftpd_use_nfs false;

tunable_policy Macro

This macro contains the statements allowed or not depending on the value of the boolean defined by the gen_tunable macro.

The macro definition is:

tunable_policy('gen_tunable_id',tunable_policy_rules`)

Where:

tunable_policy

• The tunable_policy macro keyword.

gen_tunable_id

• This is the boolean identifier defined by the gen_tunable macro. It is possible to have multiple entries separated by && or || as shown in the example.

tunable_policy_rules

• These are the policy rules and statements as defined in the if statement policy language section.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
Yes	Yes	No

Example Macro:

# This example is from the modules/services/ftp.te module
# showing the use of the boolean with the && operator.
#

tunable_policy(`allow_ftpd_use_nfs && allow_ftpd_anon_write',`
	fs_manage_nfs_files(ftpd_t)
')

Expanded Macro:

# This is the expanded macro from the tmp/ftp.tmp file.
#

if (allow_ftpd_use_nfs && allow_ftpd_anon_write) {
	##### begin fs_manage_nfs_files(ftpd_t)
	require {
		type nfs_t;
	} # end require
	allow ftpd_t nfs_t:dir { read getattr lock search ioctl add_name remove_name write };
	allow ftpd_t nfs_t:file { create open getattr setattr read write append rename link unlink ioctl lock };
} # end allow_ftpd_use_nfs && allow_ftpd_anon_write

interface Macro

Access interface macros are defined in the interface module file (.if) and form the interface through which other modules can call on the modules services (as shown in and described in the Module Expansion Process section.

The macro definition is:

interface(`name',`interface_rules')

Where:

interface

• The interface macro keyword.

name

• The interface identifier that should be named to reflect the module identifier and its purpose.

interface_rules

• This can consist of the support macros, policy language statements or other interface calls as required to provide the service.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
No	Yes	No

Example Interface Definition:

Note that the comments shown in the example MUST be present as they are used to describe the function and are extracted for the documentation.

# This example is from the modules/services/ftp.if module
# showing the 'ftp_read_config' interface.
#

########################################
## <summary>
##	Read ftpd configuration files.
## </summary>
## <param name="domain">
##	<summary>
##	Domain allowed access.
##	</summary>
## </param>
#
interface(`ftp_read_config',`
	gen_require(`
		type ftpd_etc_t;
	')

	files_search_etc($1)
	allow $1 ftpd_etc_t:file read_file_perms;
')

Expanded Macro: (taken from the base.conf file):

# Access Interfaces are only expanded at policy compile time
# if they are called by a module that requires their services.
#

# In this example the ftp_read_config interface is called from
# the init.te module via the optional_policy macro as shown
# below with the expanded code shown afterwards.

#
######## From ./policy/policy/modules/system/init.te ########
#

# optional_policy(`
# 	ftp_read_config(initrc_t)
# ')

#
############ Expanded policy statements taken from init.tmp ##############
#
optional {
	##### begin ftp_read_config(initrc_t) depth: 1
	require {
		type ftpd_etc_t;
	} # end require

	##### begin files_search_etc(initrc_t) depth: 2
	require {
		type etc_t;
	} # end require

	allow initrc_t etc_t:dir { getattr search open };
	##### end files_search_etc(initrc_t) depth: 1
	allow initrc_t ftpd_etc_t:file { getattr open read lock ioctl };
	##### end ftp_read_config(initrc_t) depth: 0
} # end optional

template Macro

A template interface is used to help create a domain and set up the appropriate rules and statements to run an application / process. The basic idea is to set up an application in a domain that is suitable for the defined SELinux user and role to access but not others. Should a different user / role need to access the same application, another domain would be allocated (these are known as 'derived domains' as the domain name is derived from caller information).

The main differences between an application interface and a template interface are:

• An access interface is called by other modules to perform a service.
• A template interface allows an application to be run in a domain based on user / role information to isolate different instances.

Note that the comments shown in the example MUST be present as they are used to describe the function and are extracted for the documentation.

The macro definition is:

template(`name',`template_rules')

Where:

template

• The template macro keyword.

name

• The template identifier that should be named to reflect the module identifier and its purpose. By convention the last component is _template (e.g. ftp_per_role_template).

template_rules

• This can consist of the support macros, policy language statements or interface calls as required to provide the service.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
No	Yes	No

Example Macro:

# This example is from the modules/services/djbdns.if module
# showing the 'djbdns_daemontools_domain_template' template interface.
#

#######################################
## <summary>
##	The template to define a djbdns domain.
## </summary>
## <param name="domain_prefix">
##	<summary>
##	Domain prefix to be used.
##	</summary>
## </param>
#
template(`djbdns_daemontools_domain_template',`
	gen_require(`
		attribute djbdns_domain;
	')

	########################################
	#
	# Declarations
	#

	type djbdns_$1_t, djbdns_domain;
	type djbdns_$1_exec_t;
	domain_type(djbdns_$1_t)
	domain_entry_file(djbdns_$1_t, djbdns_$1_exec_t)
	role system_r types djbdns_$1_t;

	type djbdns_$1_conf_t;
	files_config_file(djbdns_$1_conf_t)

	########################################
	#
	# Local policy
	#

	daemontools_service_domain(djbdns_$1_t, djbdns_$1_exec_t)
	daemontools_read_svc(djbdns_$1_t)

	allow djbdns_$1_t djbdns_$1_conf_t:dir list_dir_perms;
	allow djbdns_$1_t djbdns_$1_conf_t:file read_file_perms;
')

Expanded Macro:

# Template Interfaces are only expanded at policy compile time
# if they are called by a module that requires their services.
# This has been called from services/djbdns.te via:
#    djbdns_daemontools_domain_template(dnscache)
# and expanded in tmp/djbdns.tmp.
#

# Note these are very long, so only start / end shown. To trace these:
# 1) Note the line number where djbdns_daemontools_domain_template(dnscache)
#    is called in djbdns.te. In this case it is line 13.
# 2) In the appropriate tmp file where the macro has been expanded, in this
#    case tmp/djbdns.tmp, search for '#line 13'. These entries are all the
#    expanded components to build djbdns_daemontools_domain_template(dnscache).

##### begin djbdns_daemontools_domain_template(dnscache) depth: 1
	require {
		attribute djbdns_domain;
	} # end require

	########################################
	#
	# Declarations
	#
	type djbdns_dnscache_t, djbdns_domain;
	type djbdns_dnscache_exec_t;
##### begin domain_type(djbdns_dnscache_t) depth: 2
	# start with basic domain
......
......
......
##### end files_search_var(djbdns_dnscache_t) depth: 2
	allow djbdns_dnscache_t svc_svc_t:dir { getattr search open read lock ioctl };
	allow djbdns_dnscache_t svc_svc_t:file { getattr open read lock ioctl };
##### end daemontools_read_svc(djbdns_dnscache_t) depth: 1
	allow djbdns_dnscache_t djbdns_dnscache_conf_t:dir { getattr search open read lock ioctl };
	allow djbdns_dnscache_t djbdns_dnscache_conf_t:file { getattr open read lock ioctl };
##### end djbdns_daemontools_domain_template(dnscache) depth: 0

Miscellaneous Macros

These macros are in the misc_macros.spt file.

gen_context Macro

This macro is used to generate a valid security context and can be used in any of the module files. Its most general use is in the .fc file where it is used to set the files security context.

The macro definition is:

gen_context(context[,mls,[mcs_categories]])

Where:

gen_context

• The gen_context macro keyword.

context

• The security context to be generated. This can include macros that are relevant to a context as shown in the example below.

mls

• MLS labels if MLS enabled in the policy.

mcs_categories

• MCS categories if MCS is enabled. MLS argument is required, but ignored.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
Yes	Yes	Yes

Example Macro (MCS):

# This example shows gen_context being used for a custom app

/var/lib/custom_app(/.*)?  gen_context(system_u:object_r:custom_app_t,mls_systemhigh,c9)

Expanded Macro (MCS):

# This is the expanded entry built into contexts/files/file_contexts:

/var/lib/custom_app(/.*)?  system_u:object_r:custom_app_t:s0:c9

Example Macro (MLS):

# This example shows gen_context being used to generate a
# security context in the kernel/storage.fc module:

/dev/\.tmp-block-.* -c gen_context(system_u:object_r:fixed_disk_device_t,mls_systemhigh)

Expanded Macro (MLS):

# This is the expanded entry built into contexts/files/file_contexts:

/dev/\.tmp-block-.*  -c  system_u:object_r:fixed_disk_device_t:s15:c0.c1023

gen_user Macro

This macro is used to generate a valid user Statement and add an entry in the users_extra configuration file if it exists.

The macro definition is:

gen_user(username, prefix, role_set, mls_defaultlevel, mls_range, [mcs_categories])

Where:

gen_user

• The gen_user macro keyword.

username

• The SELinux user id.

prefix

• SELinux users without the prefix will not be in the users_extra file. This is added to user directories by genhomedircon as discussed in the Building the File Labeling Support Files section.

role_set

• The user roles.

mls_defaultlevel

• The default level if MLS / MCS policy.

mls_range

• The range if MLS / MCS policy.

mcs_categories

The categories if MLS / MCS policy.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
Yes	No	No

Example Macro:

# This example has been taken from the policy/policy/users file:
#

ifdef(`direct_sysadm_daemon',*
	gen_user(root, sysadm, sysadm_r staff_r ifdef(`enable_mls',`secadm_r auditadm_r') system_r, s0, s0 - mls_systemhigh, mcs_allcats)
',`
	gen_user(root, sysadm, sysadm_r staff_r ifdef(`enable_mls',`secadm_r auditadm_r'), s0, s0 - mls_systemhigh, mcs_allcats)
')

Expanded Macro:

# The expanded gen_user macro from the base.conf for an MLS
# build. Note that the prefix is not present. This is added to
# the users_extra file as shown below.
#

user root roles { sysadm_r staff_r secadm_r auditadm_r } level s0 range s0 - s15:c0.c1023;

# policy/tmp/users_extra file entry:
#

user root prefix sysadm;

gen_bool Macro

This macro defines a boolean and requires the following steps:

1. Declare the boolean in the global_booleans file.
2. Use the boolean in a module fileswith an if / else Statement as shown in the example.

Note that the comments shown in the example MUST be present as they are used to describe the function and are extracted for the documentation.

The macro definition is:

gen_bool(name,default_value)

Where:

gen_bool

• The gen_bool macro keyword.

name

• The boolean identifier.

default_value

• The value true or false.

The macro is only valid in the global_booleans file but the boolean declared can be used in the following module types:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
Yes	Yes	No

Example Macro:

# This example is from kernel/kernel.te  where the bool is declared.
# The comments must be present as it is used to generate the documentation.
#

## <desc>
## <p>
## Disable kernel module loading.
## </p>
## </desc>
gen_bool(secure_mode_insmod, false)

# Example usage from the kernel/kernel.te module:
#

if( ! secure_mode_insmod ) {
	allow can_load_kernmodule self:capability sys_module;
	allow can_load_kernmodule self:system module_load;

	files_load_kernel_modules(can_load_kernmodule)

	# load_module() calls stop_machine() which
	# calls sched_setscheduler()
	# gt: there seems to be no trace of the above, at
	# least in kernel versions greater than 2.6.37...
	allow can_load_kernmodule self:capability sys_nice;
	kernel_setsched(can_load_kernmodule)
}

# This example is from policy/booleans.conf where the bool set for policy.
#
# Disable kernel module loading.
#
secure_mode_insmod = false

Expanded Macro:

# This has been taken from the base.conf source file after
# expansion by the build process of the kernel.te module.
#

########################################
#
# Kernel module loading policy
#

if( ! secure_mode_insmod ) {
	allow can_load_kernmodule self:capability sys_module;
	allow can_load_kernmodule self:system module_load;
##### begin files_load_kernel_modules(can_load_kernmodule) depth: 1
##### begin files_read_kernel_modules(can_load_kernmodule) depth: 2
	allow can_load_kernmodule modules_object_t:dir { getattr search open read lock ioctl };
	allow can_load_kernmodule modules_object_t:dir { getattr search open };
	allow can_load_kernmodule modules_object_t:file { getattr open read lock ioctl };
	allow can_load_kernmodule modules_object_t:dir { getattr search open };
	allow can_load_kernmodule modules_object_t:lnk_file { getattr read };
##### end files_read_kernel_modules(can_load_kernmodule) depth: 1
	allow can_load_kernmodule modules_object_t:system module_load;
##### end files_load_kernel_modules(can_load_kernmodule) depth: 0
	# load_module() calls stop_machine() which
	# calls sched_setscheduler()
	# gt: there seems to be no trace of the above, at
	# least in kernel versions greater than 2.6.37...
	allow can_load_kernmodule self:capability sys_nice;
	allow can_load_kernmodule kernel_t:process setsched;
##### end kernel_setsched(can_load_kernmodule) depth: 0
}

MLS and MCS Macros

These macros are in the mls_mcs_macros.spt file.

gen_cats Macro

This macro will generate a category statement for each category defined. These are then used in the base.conf / policy.conf source file and also inserted into each module by the policy_module. The policy/policy/mcs and mls configuration files are the only files that contain this macro in the current reference policy.

The macro definition is:

gen_cats(mcs_num_cats | mls_num_cats)

Where:

gen_cats

• The gen_cats macro keyword.

mcs_num_cats

mls_num_cats

• These are the maximum number of categories that have been extracted from the build.conf file MCS_CATS or MLS_CATS entries and set as m4 parameters.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
na	na	na

Example Macro:

# This example is from the policy/policy/mls configuration file.
#

gen_cats(mls_num_cats)

Expanded Macro:

# This example has been extracted from the base.conf source file.

category c0;
category c1;
...
category c1023;

gen_sens Macro

This macro will generate a sensitivity for each sensitivity defined. These are then used in the base.conf / policy.conf source file and also inserted into each module by the policy_module. The policy/policy/mcs and mls configuration files are the only files that contain this macro in the current reference policy (note that the mcs file has gen_sens(1) as only one sensitivity is required).

The macro definition is:

gen_sens(mls_num_sens)

Where:

gen_sens

• The gen_sens macro keyword.

mls_num_sens

• These are the maximum number of sensitivities that have been extracted from the build.conf file MLS_SENS entries and set as an m4 parameter.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
na	na	na

Example Macro:

# This example is from the policy/policy/mls configuration file.
#

gen_cats(mls_num_sens)

Expanded Macro:

# This example has been extracted from the base.conf source file.

sensitivity s0;
sensitivity s1;
...
sensitivity s15;

gen_levels Macro

This macro will generate a level for each level defined. These are then used in the base.conf / policy.conf source file. The policy/policy/mcs and mls configuration files are the only files that contain this macro in the current reference policy.

The macro definition is:

gen_levels(mls_num_sens,mls_num_cats)

Where:

gen_levels

• The gen_levels macro keyword.

mls_num_sens

• This is the parameter that defines the number of sensitivities to generate. The MCS policy is set to '1'.

mls_num_cats

mcs_num_cats

• This is the parameter that defines the number of categories to generate.

The macro is valid in:

Private Policy File (.te)	External Interface File (.if)	File Labeling Policy File (.fc)
na	na	na

Example Macro:

# This example is from the policy/policy/mls configuration file.
#

gen_levels(mls_num_sens,mls_num_cats)

Expanded Macro:

# This example has been extracted from the base.conf source file.
# Note that the all categories are allocated to each sensitivity.

level s0:c0.c1023;
level s1:c0.c1023;
...
level s15:c0.c1023;

System High/Low Parameters

These macros define system high etc. as shown.

mls_systemlow

# gives:

s0

mls_systemhigh

# gives:

s15:c0.c1023

mcs_systemlow

# gives:

s0

mcs_systemhigh

# gives:

s0:c0.c1023

mcs_allcats

# gives:

c0.c1023

ifdef / ifndef Parameters

This section contains examples of the common ifdef / ifndef parameters that can be used in module source files.

hide_broken_symptoms

This is used within modules as shown in the example. The parameter is set up by the Makefile at the start of the build process.

Example Macro:

# This example is from the modules/kernel/domain.te module.
#

ifdef(`hide_broken_symptoms',`
	# This check is in the general socket
	# listen code, before protocol-specific
	# listen function is called, so bad calls
	# to listen on UDP sockets should be silenced
	dontaudit domain self:udp_socket listen;
')

enable_mls and enable_mcs

These are used within modules as shown in the example. The parameters are set up by the Makefile with information taken from the build.conf file at the start of the build process.

Example Macros:

# This example is from the modules/kernel/kernel.te module.
#

ifdef(`enable_mls',`
	role secadm_r;
	role auditadm_r;
')

# This example is from the modules/services/ftp.te module.
#

ifdef(`enable_mcs',`
	init_ranged_daemon_domain(ftpd_t, ftpd_exec_t, s0 - mcs_systemhigh)
')

enable_ubac

This is used within the ./policy/constraints configuration file to set up various attributes to support user based access control (UBAC). These attributes are then used within the various modules that want to support UBAC. This support was added in version 2 of the Reference Policy.

The parameter is set up by the Makefile with information taken from the build.conf file at the start of the build process (ubac = y | ubac = n).

Example Macro:

# This example is from the policy/constraints file.
# Note that the ubac_constrained_type attribute is defined in
# modules/kernel/ubac.te module.

define(`basic_ubac_conditions',`
	ifdef(`enable_ubac',`
		u1 == u2
		or u1 == system_u
		or u2 == system_u
		or t1 != ubac_constrained_type
		or t2 != ubac_constrained_type
	')
')

direct_sysadm_daemon

This is used within modules as shown in the example. The parameter is set up by the Makefile with information taken from the build.conf file at the start of the build process (if DIRECT_INITRC = y).

Example Macros:

# This example is from the modules/system/selinuxutil.te module.
#

ifndef(`direct_sysadm_daemon',`
	ifdef(`distro_gentoo',`
		# Gentoo integrated run_init:
		init_script_file_entry_type(run_init_t)

		init_exec_rc(run_init_t)
	')
')

Module Expansion Process

The objective of this section is to show how the modules are expanded by the reference policy build process to form files that can then be compiled and then loaded into the policy store by using the make MODULENAME.pp target.

The files shown are those produced by the build process using the ada policy modules from the Reference Policy source tree (ada.te, ada.if and ada.fc) that are shown in the Reference Policy Module Files section.

The initial build process will build the source text files in the policy/tmp directory as ada.tmp and ada.mod.fc (that are basically build equivalent ada.conf and ada.fc formatted files). The basic steps are shown in , and the resulting expanded code shown in and then described in the Module Expansion Process section.

Figure 28: The make ada sequence of events

Figure 29: The expansion process

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