.\" Copyright (c) 2002 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 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.
.\"
.\" 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
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.\"
.Dd October 11, 2024
.Dt MAC_BSDEXTENDED 4
.Os
.Sh NAME
.Nm mac_bsdextended
.Nd "file system firewall policy"
.Sh SYNOPSIS
To compile the file system firewall policy into your kernel,
place the following lines in your kernel configuration file:
.Bd -ragged -offset indent
.Cd "options MAC"
.Cd "options MAC_BSDEXTENDED"
.Ed
.Pp
Alternately, to load the file system firewall policy module at boot time,
place the following line in your kernel configuration file:
.Bd -ragged -offset indent
.Cd "options MAC"
.Ed
.Pp
and in
.Xr loader.conf 5 :
.Bd -literal -offset indent
mac_bsdextended_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
security policy module provides an interface for the system administrator
to impose mandatory rules regarding users and some system objects.
Rules are uploaded to the module
(typically using
.Xr ugidfw 8 ,
or some other tool utilizing
.Xr libugidfw 3 )
where they are stored internally
and used to determine whether to allow or deny specific accesses
(see
.Xr ugidfw 8 ) .
.Sh IMPLEMENTATION NOTES
While the traditional
.Xr mac 9
entry points are implemented,
policy labels are not used;
instead, access control decisions are made by iterating through the internal
list of rules until a rule
which denies the particular access
is found,
or the end of the list is reached.
The
.Nm
policy works similar to
.Xr ipfw 8
or by using a
.Em first match semantic .
This means that not all rules are applied,
only the first matched rule; thus if
Rule A allows access and Rule B blocks
access, Rule B will never be applied.
.Sh SYSCTL VARIABLES
The following sysctls may be used to tweak the behavior of
.Nm :
.Bl -tag -width indent
.It Va security.mac.bsdextended.enabled
Set to zero or one to toggle the policy off or on.
.It Va security.mac.bsdextended.rule_count
List the number of defined rules, the maximum rule count is
current set at 256.
.It Va security.mac.bsdextended.rule_slots
List the number of rule slots currently being used.
.It Va security.mac.bsdextended.firstmatch_enabled
Toggle between the old all rules match functionality
and the new first rule matches functionality.
This is enabled by default.
.It Va security.mac.bsdextended.logging
Log all access violations via the
.Dv AUTHPRIV
.Xr syslog 3
facility.
.It Va security.mac.bsdextended.rules
Currently does nothing interesting.
.El
.Sh SEE ALSO
.Xr libugidfw 3 ,
.Xr syslog 3 ,
.Xr mac 4 ,
.Xr mac_biba 4 ,
.Xr mac_ddb 4 ,
.Xr mac_ifoff 4 ,
.Xr mac_lomac 4 ,
.Xr mac_mls 4 ,
.Xr mac_none 4 ,
.Xr mac_partition 4 ,
.Xr mac_portacl 4 ,
.Xr mac_seeotheruids 4 ,
.Xr mac_test 4 ,
.Xr ipfw 8 ,
.Xr ugidfw 8 ,
.Xr mac 9
.Sh HISTORY
The
.Nm
policy module first appeared in
.Fx 5.0
and was developed by the
.Tn TrustedBSD
Project.
.Pp
The "match first case" and logging capabilities were later added by
.An Tom Rhodes Aq Mt trhodes@FreeBSD.org .
.Sh AUTHORS
This software was contributed to the
.Fx
Project by NAI Labs, the Security Research Division of Network Associates
Inc.\& under DARPA/SPAWAR contract N66001-01-C-8035
.Pq Dq CBOSS ,
as part of the DARPA CHATS research program.