247 lines
7.8 KiB
Groff
247 lines
7.8 KiB
Groff
.\" 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 July 25, 2015
|
|
.Dt MAC 4
|
|
.Os
|
|
.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 restrict access relative to one another and the base system policy;
|
|
they cannot override traditional
|
|
.Ux
|
|
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_portacl 4 Ta "Port bind(2) access control" Ta no 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 contain data in an arbitrary format
|
|
taken into consideration in making access control decisions
|
|
for a given operation.
|
|
Most MAC labels on system subjects and objects
|
|
can be modified directly or indirectly by the system
|
|
administrator.
|
|
The format for a given policy's label may vary depending on the type
|
|
of object or subject being labeled.
|
|
More information on the format for MAC labels can be found in the
|
|
.Xr maclabel 7
|
|
man page.
|
|
.Ss MAC Support for UFS2 File Systems
|
|
By default, file system enforcement of labeled MAC policies relies on
|
|
a single file system label
|
|
(see
|
|
.Sx "MAC Labels" )
|
|
in order to make access control decisions for all the files in a particular
|
|
file system.
|
|
With some policies, this configuration may not allow administrators to take
|
|
full advantage of features.
|
|
In order to enable support for labeling files on an individual basis
|
|
for a particular file system,
|
|
the
|
|
.Dq multilabel
|
|
flag must be enabled on the file system.
|
|
To set the
|
|
.Dq multilabel
|
|
flag, drop to single-user mode and unmount the file system,
|
|
then execute the following command:
|
|
.Pp
|
|
.Dl "tunefs -l enable" Ar filesystem
|
|
.Pp
|
|
where
|
|
.Ar filesystem
|
|
is either the mount point
|
|
(in
|
|
.Xr fstab 5 )
|
|
or the special file
|
|
(in
|
|
.Pa /dev )
|
|
corresponding to the file system on which to enable multilabel support.
|
|
.Ss Policy Enforcement
|
|
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 ,
|
|
packet delivery and transmission,
|
|
interface configuration
|
|
.Xr ( ioctl 2 ,
|
|
.Xr ifconfig 8 )
|
|
.It Sy Pipes
|
|
Creation of and operation on
|
|
.Xr pipe 2
|
|
objects
|
|
.It Sy Processes
|
|
Debugging
|
|
(e.g.\&
|
|
.Xr ktrace 2 ) ,
|
|
process visibility
|
|
.Pq Xr ps 1 ,
|
|
process execution
|
|
.Pq Xr execve 2 ,
|
|
signalling
|
|
.Pq Xr kill 2
|
|
.It Sy Sockets
|
|
Creation of and operation on
|
|
.Xr socket 2
|
|
objects
|
|
.It Sy System
|
|
Kernel environment
|
|
.Pq Xr kenv 1 ,
|
|
system accounting
|
|
.Pq Xr acct 2 ,
|
|
.Xr reboot 2 ,
|
|
.Xr settimeofday 2 ,
|
|
.Xr swapon 2 ,
|
|
.Xr sysctl 3 ,
|
|
.Xr nfsd 8 Ns
|
|
-related operations
|
|
.It Sy VM
|
|
.Xr mmap 2 Ns
|
|
-ed 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 setfmac 8 , Xr setfsmac 8" -offset indent
|
|
.It Sy "Subject/Object" Ta Sy "Utility"
|
|
.It "File system object" Ta Xr setfmac 8 , Xr setfsmac 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 su 1
|
|
and
|
|
.Xr setpmac 8
|
|
utilities 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.
|
|
.\" *** XXX ***
|
|
.\" Support for this feature is poor and should not be encouraged.
|
|
.\"
|
|
.\" .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).
|
|
.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_portacl 4 ,
|
|
.Xr mac_seeotheruids 4 ,
|
|
.Xr mac_test 4 ,
|
|
.Xr login.conf 5 ,
|
|
.Xr maclabel 7 ,
|
|
.Xr getfmac 8 ,
|
|
.Xr getpmac 8 ,
|
|
.Xr setfmac 8 ,
|
|
.Xr setpmac 8 ,
|
|
.Xr mac 9
|
|
.Rs
|
|
.%B "The FreeBSD Handbook"
|
|
.%T "Mandatory Access Control"
|
|
.%U https://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
|
|
.Tn 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
|
|
.Pq Dq CBOSS ,
|
|
as part of the DARPA CHATS research program.
|
|
.Sh BUGS
|
|
While the MAC Framework design is intended to support the containment of
|
|
the root user, not all attack channels are currently protected by entry
|
|
point checks.
|
|
As such, MAC Framework policies should not be relied on, in isolation,
|
|
to protect against a malicious privileged user.
|