218 lines
5.9 KiB
Groff
218 lines
5.9 KiB
Groff
.\" Copyright (c) 2003 Networks Associates Technology, Inc.
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.\" All rights reserved.
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.\"
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.\" This software was developed for the FreeBSD Project by Chris Costello
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.\" at Safeport Network Services and Network Associates Labs, the
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.\" Security Research Division of Network Associates, Inc. under
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.\" DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
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.\" DARPA CHATS research program.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 9, 2004
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.Dt MAC_PORTACL 4
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.Os
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.Sh NAME
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.Nm mac_portacl
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.Nd "network port access control policy"
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.Sh SYNOPSIS
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To compile the port access control policy into your kernel,
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place the following lines in your kernel
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configuration file:
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.Bd -ragged -offset indent
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.Cd "options MAC"
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.Cd "options MAC_PORTACL"
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.Ed
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.Pp
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Alternately, to load the port access control policy module at boot time,
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place the following line in your kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "options MAC"
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.Ed
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.Pp
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and in
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.Xr loader.conf 5 :
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.Pp
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.Dl "mac_portacl_load=""YES"""
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.Sh DESCRIPTION
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The
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.Nm
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policy allows administrators to administratively limit binding to
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local
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.Tn UDP
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and
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.Tn TCP
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ports via the
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.Xr sysctl 8
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interface.
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.Pp
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In order to enable the
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.Nm
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policy, MAC policy must be enforced on sockets
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(see
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.Xr mac 4 ) ,
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and the port(s) protected by
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.Nm
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must not be included in the range specified by
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the
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.Va net.inet.ip.portrange.reservedlow
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and
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.Va net.inet.ip.portrange.reservedhigh
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.Xr sysctl 8
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MIBs.
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.Pp
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The
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.Nm
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policy only affects ports explicitly bound by a user process (either
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for a listen/outgoing
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.Tn TCP
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socket, or a send/receive
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.Tn UDP
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socket).
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This policy will not limit ports bound implicitly for outgoing
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connections where the process has not explicitly selected a port:
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these are automatically selected by the IP stack.
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.Pp
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When
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.Nm
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is enabled, it will control binding access to ports up to the port
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number set in the
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.Va security.mac.portacl.port_high
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.Xr sysctl 8
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variable.
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By default, all attempts to bind to
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.Nm
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controlled ports will fail if not explicitly allowed by the port
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access control list, though binding by the superuser will be allowed,
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if the
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.Xr sysctl 8
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variable
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.Va security.mac.portacl.suser_exempt
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is set to a non-zero value.
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.Ss Runtime Configuration
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The following
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.Xr sysctl 8
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MIBs are available for fine-tuning the enforcement of this MAC policy.
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All
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.Xr sysctl 8
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variables, except
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.Va security.mac.portacl.rules ,
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can also be set as
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.Xr loader 8
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tunables in
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.Xr loader.conf 5 .
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.Bl -tag -width indent
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.It Va security.mac.portacl.enabled
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Enforce the
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.Nm
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policy.
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(Default: 1).
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.It Va security.mac.portacl.port_high
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The highest port number
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.Nm
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will enforce rules for.
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(Default: 1023).
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.It Va security.mac.portacl.rules
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The port access control list is specified in the following format:
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.Pp
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.Sm off
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.D1 Ar idtype : id : protocol : port Op , Ar idtype : id : protocol : port , ...
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.Sm on
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.Bl -tag -width ".Ar protocol"
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.It Ar idtype
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Describes the type of subject match to be performed.
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Either
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.Li uid
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for user ID matching, or
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.Li gid
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for group ID matching.
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.It Ar id
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The user or group ID (depending on
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.Ar idtype )
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allowed to bind to the specified port.
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.Bf -emphasis
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NOTE: User and group names are not valid; only the actual ID numbers
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may be used.
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.Ef
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.It Ar protocol
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Describes which protocol this entry applies to.
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Either
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.Li tcp
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or
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.Li udp
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are supported.
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.It Ar port
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Describes which port this entry applies to.
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.Bf -emphasis
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NOTE: MAC security policies may not override other security system policies
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by allowing accesses that they may deny, such as
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.Va net.inet.ip.portrange.reservedlow /
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.Va net.inet.ip.portrange.reservedhigh .
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.Ef
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If the specified port falls within the range specified, the
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.Nm
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entry will not function
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(i.e., even the specified user/group may not be able to bind to the specified
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port).
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.El
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.It Va security.mac.portacl.suser_exempt
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Allow superuser (i.e., root) to bind to all
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.Nm
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protected ports, even if the port access control list does not
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explicitly allow this.
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(Default: 1).
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.It Va security.mac.portacl.autoport_exempt
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Allow applications to use automatic binding to port 0.
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Applications use port 0 as a request for automatic port allocation when
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binding an IP address to a socket.
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This tunable will exempt port 0 allocation from rule checking.
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(Default: 1).
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.El
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.Sh SEE ALSO
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.Xr mac 3 ,
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.Xr ip 4 ,
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.Xr mac_biba 4 ,
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.Xr mac_bsdextended 4 ,
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.Xr mac_ifoff 4 ,
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.Xr mac_mls 4 ,
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.Xr mac_none 4 ,
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.Xr mac_partition 4 ,
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.Xr mac_seeotheruids 4 ,
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.Xr mac_test 4 ,
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.Xr mac 9
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.Sh HISTORY
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MAC first appeared in
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.Fx 5.0
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and
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.Nm
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first appeared in
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.Fx 5.1 .
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.Sh AUTHORS
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This software was contributed to the
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.Fx
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Project by NAI Labs, the Security Research Division of Network Associates
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Inc.\& under DARPA/SPAWAR contract N66001-01-C-8035
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.Pq Dq CBOSS ,
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as part of the DARPA CHATS research program.
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