.\" Copyright (c) 2001, 2003 Networks Associates Technology, Inc.
.\" Copyright (c) 2009 Robert N. M. Watson
.\" All rights reserved.
.\"
.\" This software was developed for the FreeBSD Project by Chris
.\" Costello at Safeport Network Services and Network Associates
.\" Laboratories, the Security Research Division of Network Associates,
.\" Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part
.\" of the DARPA CHATS research program.
.\"
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.\" are met:
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.\" $FreeBSD$
.\"
.Dd July 25, 2015
.Dt MAC 3
.Os
.Sh NAME
.Nm mac
.Nd introduction to the MAC security API
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/mac.h
.Pp
In the kernel configuration file:
.Cd "options MAC"
.Sh DESCRIPTION
Mandatory Access Control labels describe confidentiality, integrity, and
other security attributes of operating system objects, overriding
discretionary access control.
Not all system objects support MAC labeling, and MAC policies must be
explicitly enabled by the administrator.
This API, based on POSIX.1e, includes routines to retrieve, manipulate, set,
and convert to and from text the MAC labels on files and processes.
.Pp
MAC labels consist of a set of (name, value) tuples, representing security
attributes from MAC policies.
For example, this label contains security labels defined by two policies,
.Xr mac_biba 4
and
.Xr mac_mls 4 :
.Bd -literal -offset indent
biba/low,mls/low
.Ed
.Pp
Further syntax and semantics of MAC labels may be found in
.Xr maclabel 7 .
.Pp
Applications operate on labels stored in
.Vt mac_t ,
but can convert between this internal format and a text format for the
purposes of presentation to uses or external storage.
When querying a label on an object, a
.Vt mac_t
must first be prepared using the interfaces described in
.Xr mac_prepare 3 ,
allowing the application to declare which policies it wishes to interrogate.
The application writer can also rely on default label names declared in
.Xr mac.conf 5 .
.Pp
When finished with a
.Vt mac_t ,
the application must call
.Xr mac_free 3
to release its storage.
.Pp
The following functions are defined:
.Bl -tag -width indent
.It Fn mac_is_present
This function, described in
.Xr mac_is_present 3 ,
allows applications to test whether MAC is configured, as well as whether
specific policies are configured.
.It Fn mac_get_fd , Fn mac_get_file , Fn mac_get_link , Fn mac_get_peer
These functions, described in
.Xr mac_get 3 ,
retrieve the MAC labels associated with file descriptors, files, and socket
peers.
.It Fn mac_get_pid , Fn mac_get_proc
These functions, described in
.Xr mac_get 3 ,
retrieve the MAC labels associated with processes.
.It Fn mac_set_fd , Fn mac_set_file , Fn mac_set_link
These functions, described in
.Xr mac_set 3 ,
set the MAC labels associated with file descriptors and files.
.It Fn mac_set_proc
This function, described in
.Xr mac_set 3 ,
sets the MAC label associated with the current process.
.It Fn mac_free
This function, described in
.Xr mac_free 3 ,
frees working MAC label storage.
.It Fn mac_from_text
This function, described in
.Xr mac_text 3 ,
converts a text-form MAC label into working MAC label storage,
.Vt mac_t .
.It Fn mac_prepare , Fn mac_prepare_file_label , Fn mac_prepare_ifnet_label , Fn mac_prepare_process_label , Fn mac_prepare_type
These functions,  described in
.Xr mac_prepare 3 ,
allocate working storage for MAC label operations.
.Xr mac_prepare 3
prepares a label based on caller-specified label names; the other calls
rely on the default configuration specified in
.Xr mac.conf 5 .
.It Fn mac_to_text
This function is described in
.Xr mac_text 3 ,
and may be used to convert a
.Vt mac_t
into a text-form MAC label.
.El
.Sh FILES
.Bl -tag -width ".Pa /etc/mac.conf" -compact
.It Pa /etc/mac.conf
MAC library configuration file, documented in
.Xr mac.conf 5 .
Provides default behavior for applications aware of MAC labels on
system objects, but without policy-specific knowledge.
.El
.Sh SEE ALSO
.Xr mac_free 3 ,
.Xr mac_get 3 ,
.Xr mac_is_present 3 ,
.Xr mac_prepare 3 ,
.Xr mac_set 3 ,
.Xr mac_text 3 ,
.Xr posix1e 3 ,
.Xr mac 4 ,
.Xr mac.conf 5 ,
.Xr mac 9
.Sh STANDARDS
These APIs are loosely based on the APIs described in POSIX.1e, as described
in IEEE POSIX.1e draft 17.
However, the resemblance of these APIs to the POSIX APIs is loose, as the
POSIX APIs were unable to express some notions required for flexible and
extensible access control.
.Sh HISTORY
Support for Mandatory Access Control was introduced in
.Fx 5.0
as part of the
.Tn TrustedBSD
Project.