.\" Copyright (c) 2003 Networks Associates Technology, Inc.
.\" All rights reserved.
.\" 
.\" This software was developed for the FreeBSD Project by Chris Costello
.\" at Safeport Network Services and Network Associates Labs, 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.
.\" 
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\" 
.\" $FreeBSD$
.Dd JANUARY 8, 2003
.Os
.Dt MAC 4
.Sh NAME
.Nm mac
.Nd Mandatory Access Control
.Sh SYNOPSIS
.Cd "options MAC"
.Sh DESCRIPTION
.Ss Introduction
The Mandatory Access Control, or MAC, framework allows administrators to
finely control system security by providing for a loadable security policy
architecture.
It is important to note that due to its nature, MAC security policies may
only further restrict security; they cannot override traditional UNIX
security provisions such as file permissions and superuser checks.
.Pp
Currently, the following MAC policy modules are shipped with
.Fx :
.Bl -column ".Xr mac_seeotheruids 4" "low-watermark mac policy " ".Em Labeling" "boot only"
.It Sy Name Ta Sy Description Ta Sy Labeling Ta Sy "Load time"
.It Xr mac_biba 4 Ta "Biba integrity policy" Ta yes Ta boot only
.It Xr mac_bsdextended 4 Ta "File system firewall" Ta no Ta any time
.It Xr mac_ifoff 4 Ta "Interface silencing" Ta no Ta any time
.It Xr mac_lomac 4 Ta "Low-Watermark MAC policy" Ta yes Ta boot only
.It Xr mac_mls 4 Ta "Confidentiality policy" Ta yes Ta boot only
.It Xr mac_none 4 Ta "Sample no-op policy" Ta no Ta any time
.It Xr mac_partition 4 Ta "Process partition policy" Ta yes Ta any time
.It Xr mac_seeotheruids 4 Ta "See-other-UIDs policy" Ta no Ta any time
.It Xr mac_test 4 Ta "MAC testing policy" Ta no Ta any time
.El
.Ss MAC Labels
Each system subject (processes, sockets, etc.) and each system object
(file system objects, sockets, etc.) can carry with it a MAC label.
MAC labels can contain data in an arbitrary format
used by the MAC policies in order to help determine how to determine
access rights for a given operation.
Most MAC labels on system subjects and objects
can be modified directly or indirectly by the system
administrator.
More information on the format for MAC labels can be found in the
.Xr maclabel 7
man page.
.Ss Policy Enforcement
MAC can be configured to enforce only specific portions of
policies
(see
.Sx "Runtime Configuration" ) .
Policy enforcement is divided into the following areas of the system:
.Bl -ohang
.It Sy File System
File system mounts, modifying directories, modifying files, etc.
.It Sy KLD
Loading, unloading, and retrieving statistics on loaded kernel modules
.It Sy Network
Network interfaces,
.Xr bpf 4
.It Sy Pipes
Creation of and operation on
.Xr pipe 2
objects
.It Sy Processes
Debugging
(e.g.
.Xr ktrace 2 ) ,
process visibility
.Xr ( ps 1 ) ,
process execution
.Xr ( execve 2 ) ,
signalling
.Xr ( kill 2 )
.It Sy Sockets
Creation and operation on
.Xr socket 2
objects
.It Sy System
Kernel environment
.Xr ( kenv 1 ) ,
system accounting
.Xr ( acct 2 ) ,
.Xr reboot 2 ,
.Xr settimeofday 2 ,
.Xr swapon 2 ,
.Xr sysctl 3 ,
.Sm off
.Xr nfsd 8 -
related
.Sm on
operations
.It Sy VM
.Sm off
.Xr mmap 2 -
ed
.Sm on
files
.El
.Ss Setting MAC labels
From the command line, each type of system object has its own means for setting
and modifying its MAC policy label.
.Bl -column "user (by login class)" "Xr login.conf 5" -offset indent
.It Sy "Subject/Object" Ta Sy "Utility"
.It "File system object" Ta Xr setfmac 8
.It "Network interface" Ta Xr ifconfig 8
.It "TTY (by login class)" Ta Xr login.conf 5
.It "User (by login class)" Ta Xr login.conf 5
.El
.Pp
Additionally, the
.Xr setpmac 8
command can be used to run a command with a different process label than
the shell's current label.
.Ss Programming With MAC
MAC security enforcement itself is transparent to application
programs, with the exception that some programs may need to be aware of
additional
.Xr errno 2
returns from various system calls.
.Pp
The interface for retrieving, handling, and setting policy labels
is documented in the
.Xr mac 3
man page.
.Ss Runtime Configuration
The following
.Xr sysctl 8
MIBs are available for fine-tuning the enforcement of MAC policies.
Unless specifically noted, all MIBs default to
.Li 1
(that is, all areas are enforced by default):
.Bl -tag -width "security.mac.mmap_revocation"
.It Va security.mac.enforce_fs
Enforce MAC policies for file system accesses
.It Va security.mac.enforce_kld
Enforce MAC policies on
.Xr kld 4
.It Va security.mac.enforce_network
Enforce MAC policies on network interfaces
.It Va security.mac.enforce_pipe
Enforce MAC policies on pipes
.It Va security.mac.enforce_process
Enforce MAC policies between system processes
(e.g.
.Xr ps 1 ,
.Xr ktrace 2 )
.It Va security.mac.enforce_socket
Enforce MAC policies on sockets
.It Va security.mac.enforce_system
Enforce MAC policies on system-related items
(e.g.
.Xr kenv 1 ,
.Xr acct 2 ,
.Xr reboot 2 )
.It Va security.mac.enforce_vm
Enforce MAC policies on
.Xr mmap 2
and
.Xr mprotect 2
.It Va security.mac.mmap_revocation
Revoke
.Xr mmap 2
access to files on subject relabel
.It Va security.mac.mmap_revocation_via_cow
Revoke
.Xr mmap 2
access to files via copy-on-write semantics;
mapped regions will still appear writable, but will no longer
effect a change on the underlying vnode
(Default: 0)
.El
.Sh SEE ALSO
.Xr mac 3 ,
.Xr mac_biba 4 ,
.Xr mac_bsdextended 4 ,
.Xr mac_ifoff 4 ,
.Xr mac_lomac 4 ,
.Xr mac_mls 4 ,
.Xr mac_none 4 ,
.Xr mac_partition 4 ,
.Xr mac_seeotheruids 4 ,
.Xr mac_test 4 ,
.Xr login.5 ,
.Xr maclabel 7 ,
.Xr getfmac 8 ,
.Xr setfmac 8 ,
.Xr getpmac 8 ,
.Xr setpmac 8 ,
.Xr mac 9
.Rs
.%B "The FreeBSD Handbook"
.%T "Mandatory Access Control"
.%O http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/mac.html
.Re
.Sh HISTORY
The
.Nm
implementation first appeared in
.Fx 5.0
and was developed by the TrustedBSD Project.
.Sh AUTHORS
This software was contributed to the
.Fx
Project by Network Associates Labs,
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.