diff options
Diffstat (limited to 'static/freebsd/man4/mac_biba.4 3.html')
| -rw-r--r-- | static/freebsd/man4/mac_biba.4 3.html | 197 |
1 files changed, 0 insertions, 197 deletions
diff --git a/static/freebsd/man4/mac_biba.4 3.html b/static/freebsd/man4/mac_biba.4 3.html deleted file mode 100644 index 2c1611ce..00000000 --- a/static/freebsd/man4/mac_biba.4 3.html +++ /dev/null @@ -1,197 +0,0 @@ -<table class="head"> - <tr> - <td class="head-ltitle">MAC_BIBA(4)</td> - <td class="head-vol">Device Drivers Manual</td> - <td class="head-rtitle">MAC_BIBA(4)</td> - </tr> -</table> -<div class="manual-text"> -<section class="Sh"> -<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1> -<p class="Pp"><code class="Nm">mac_biba</code> — <span class="Nd">Biba - data integrity policy</span></p> -</section> -<section class="Sh"> -<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1> -<p class="Pp">To compile Biba into your kernel, place the following lines in - your kernel configuration file:</p> -<div class="Bd Pp Bd-indent"><code class="Cd">options MAC</code> -<br/> -<code class="Cd">options MAC_BIBA</code></div> -<p class="Pp">Alternately, to load the Biba module at boot time, place the - following line in your kernel configuration file:</p> -<div class="Bd Pp Bd-indent"><code class="Cd">options MAC</code></div> -<p class="Pp">and in <a class="Xr">loader.conf(5)</a>:</p> -<div class="Bd Pp Bd-indent Li"> -<pre>mac_biba_load="YES"</pre> -</div> -</section> -<section class="Sh"> -<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1> -<p class="Pp">The <code class="Nm">mac_biba</code> policy module implements the - Biba integrity model, which protects the integrity of system objects and - subjects by means of a strict information flow policy. In Biba, all system - subjects and objects are assigned integrity labels, made up of hierarchal - grades, and non-hierarchal components. Together, these label elements permit - all labels to be placed in a partial order, with information flow - protections based on a dominance operator describing the order. The - hierarchal grade field is expressed as a value between 0 and 65535, with - higher values reflecting higher integrity. The non-hierarchal compartment - field is expressed as a set of up to 256 components, numbered from 0 to 255. - A complete label consists of both hierarchal and non-hierarchal - elements.</p> -<p class="Pp">Three special label values exist:</p> -<table class="Bl-column Bd-indent"> - <tr id="Label"> - <td><a class="permalink" href="#Label"><b class="Sy">Label</b></a></td> - <td><a class="permalink" href="#Comparison"><b class="Sy" id="Comparison">Comparison</b></a></td> - </tr> - <tr id="biba/low"> - <td><a class="permalink" href="#biba/low"><code class="Li">biba/low</code></a></td> - <td>lower than all other labels</td> - </tr> - <tr id="biba/equal"> - <td><a class="permalink" href="#biba/equal"><code class="Li">biba/equal</code></a></td> - <td>equal to all other labels</td> - </tr> - <tr id="biba/high"> - <td><a class="permalink" href="#biba/high"><code class="Li">biba/high</code></a></td> - <td>higher than all other labels</td> - </tr> -</table> -<p class="Pp">The “<code class="Li">biba/high</code>” label is - assigned to system objects which affect the integrity of the system as a - whole. The “<code class="Li">biba/equal</code>” label may be - used to indicate that a particular subject or object is exempt from the Biba - protections. These special label values are not specified as containing any - compartments, although in a label comparison, - “<code class="Li">biba/high</code>” appears to contain all - compartments, “<code class="Li">biba/equal</code>” the same - compartments as the other label to which it is being compared, and - “<code class="Li">biba/low</code>” none.</p> -<p class="Pp">In general, Biba access control takes the following model:</p> -<ul class="Bl-bullet"> - <li>A subject at the same integrity level as an object may both read from and - write to the object as though Biba protections were not in place.</li> - <li>A subject at a higher integrity level than an object may write to the - object, but not read the object.</li> - <li>A subject at a lower integrity level than an object may read the object, - but not write to the object.</li> - <li>If the subject and object labels may not be compared in the partial order, - all access is restricted.</li> -</ul> -<p class="Pp">These rules prevent subjects of lower integrity from influencing - the behavior of higher integrity subjects by preventing the flow of - information, and hence control, from allowing low integrity subjects to - modify either a high integrity object or high integrity subjects acting on - those objects. Biba integrity policies may be appropriate in a number of - environments, both from the perspective of preventing corruption of the - operating system, and corruption of user data if marked as higher integrity - than the attacker. In traditional trusted operating systems, the Biba - integrity model is used to protect the Trusted Code Base (TCB).</p> -<p class="Pp">The Biba integrity model is similar to - <a class="Xr">mac_lomac(4)</a>, with the exception that LOMAC permits access - by a higher integrity subject to a lower integrity object, but downgrades - the integrity level of the subject to prevent integrity rules from being - violated. Biba is a fixed label policy in that all subject and object label - changes are explicit, whereas LOMAC is a floating label policy.</p> -<p class="Pp">The Biba integrity model is also similar to - <a class="Xr">mac_mls(4)</a>, with the exception that the dominance operator - and access rules are reversed, preventing the downward flow of information - rather than the upward flow of information. Multi-Level Security (MLS) - protects the confidentiality, rather than the integrity, of subjects and - objects.</p> -<section class="Ss"> -<h2 class="Ss" id="Label_Format"><a class="permalink" href="#Label_Format">Label - Format</a></h2> -<p class="Pp">Almost all system objects are tagged with an effective, active - label element, reflecting the integrity of the object, or integrity of the - data contained in the object. In general, objects labels are represented in - the following form:</p> -<p class="Pp"></p> -<div class="Bd - Bd-indent"><code class="Li">biba/</code><var class="Ar">grade</var>:<var class="Ar">compartments</var></div> -<p class="Pp">For example:</p> -<div class="Bd Pp Bd-indent Li"> -<pre>biba/10:2+3+6 -biba/low</pre> -</div> -<p class="Pp">Subject labels consist of three label elements: an effective - (active) label, as well as a range of available labels. This range is - represented using two ordered Biba label elements, and when set on a - process, permits the process to change its active label to any label of - greater or equal integrity to the low end of the range, and lesser or equal - integrity to the high end of the range. In general, subject labels are - represented in the following form:</p> -<p class="Pp"></p> -<div class="Bd - Bd-indent"><code class="Li">biba/</code><var class="Ar">effectivegrade</var>:<var class="Ar">effectivecompartments</var>(<var class="Ar">lograde</var>:<var class="Ar">locompartments-</var></div> -<div class="Bd - Bd-indent"><var class="Ar">higrade</var>:<var class="Ar">hicompartments</var></div> -) -<p class="Pp">For example:</p> -<div class="Bd Pp Bd-indent Li"> -<pre>biba/10:2+3+6(5:2+3-20:2+3+4+5+6) -biba/high(low-high)</pre> -</div> -<p class="Pp">Valid ranged labels must meet the following requirement regarding - their elements:</p> -<p class="Pp"></p> -<div class="Bd Bd-indent"><var class="Ar">rangehigh</var> - <span class="No">≥</span> <var class="Ar">effective</var> - <span class="No">≥</span> <var class="Ar">rangelow</var></div> -<p class="Pp">One class of objects with ranges currently exists, the network - interface. In the case of the network interface, the effective label element - references the default label for packets received over the interface, and - the range represents the range of acceptable labels of packets to be - transmitted over the interface.</p> -</section> -<section class="Ss"> -<h2 class="Ss" id="Runtime_Configuration"><a class="permalink" href="#Runtime_Configuration">Runtime - Configuration</a></h2> -<p class="Pp">The following <a class="Xr">sysctl(8)</a> MIBs are available for - fine-tuning the enforcement of this MAC policy.</p> -<dl class="Bl-tag"> - <dt id="security.mac.biba.enabled"><var class="Va">security.mac.biba.enabled</var></dt> - <dd>Enables enforcement of the Biba integrity policy. (Default: 1).</dd> - <dt id="security.mac.biba.ptys_equal"><var class="Va">security.mac.biba.ptys_equal</var></dt> - <dd>Label <a class="Xr">pty(4)</a>s as - “<code class="Li">biba/equal</code>” upon creation. - (Default: 0).</dd> - <dt id="security.mac.biba.revocation_enabled"><var class="Va">security.mac.biba.revocation_enabled</var></dt> - <dd>Revoke access to objects if the label is changed to dominate the subject. - (Default: 0).</dd> -</dl> -</section> -</section> -<section class="Sh"> -<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE - ALSO</a></h1> -<p class="Pp"><a class="Xr">mac(4)</a>, <a class="Xr">mac_bsdextended(4)</a>, - <a class="Xr">mac_ifoff(4)</a>, <a class="Xr">mac_lomac(4)</a>, - <a class="Xr">mac_mls(4)</a>, <a class="Xr">mac_none(4)</a>, - <a class="Xr">mac_partition(4)</a>, <a class="Xr">mac_portacl(4)</a>, - <a class="Xr">mac_seeotheruids(4)</a>, <a class="Xr">mac_test(4)</a>, - <a class="Xr">maclabel(7)</a>, <a class="Xr">mac(9)</a></p> -</section> -<section class="Sh"> -<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1> -<p class="Pp">The <code class="Nm">mac_biba</code> policy module first appeared - in <span class="Ux">FreeBSD 5.0</span> and was developed by the TrustedBSD - Project.</p> -</section> -<section class="Sh"> -<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1> -<p class="Pp">This software was contributed to the - <span class="Ux">FreeBSD</span> 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.</p> -</section> -</div> -<table class="foot"> - <tr> - <td class="foot-date">November 18, 2002</td> - <td class="foot-os">FreeBSD 15.0</td> - </tr> -</table> |