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Update webpage "Documentation - hardened_malloc" from version "5.0.1" to "5.0.2"

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<!DOCTYPE html>
<!-- Inferencium - Website - Documentation - hardened_malloc -->
<!-- Version: 5.0.1 -->
<!-- Version: 5.0.2 -->
<!-- Copyright 2023 Jake Winters -->
<!-- SPDX-License-Identifier: BSD-3-Clause -->
@ -34,12 +34,16 @@
<section id="introduction">
<p>This documentation contains instructions to use
<a href="https://github.com/GrapheneOS/hardened_malloc">hardened_malloc</a>
memory allocator as the system's default memory allocator. These instructions apply to both musl and
glibc C libraries on Unix-based and Unix-like systems.</p>
memory allocator as the system's default memory allocator via dynamic linking as a shared library. These
instructions apply to both musl and glibc C libraries on Linux-based systems.</p>
<p>hardened_malloc can also be used per-application and/or per-user, in which case root permissions are
not required; this documentation focuses on system-wide usage of hardened_malloc, assumes root
privileges, and assumes the compiled library will be located in a path readable and executable by all
users of the system.</p>
privileges, and assumes the compiled library will readable and executable by all users of the
system.</p>
<p>This documentation uses
<a href="https://refspecs.linuxfoundation.org/FHS_3.0/fhs/index.html">Linux Filesystem Hierarchy Standard</a>
paths, with the modern <code>/usr/</code> merge approach of most Linux distributions. For non-standard
configurations, adjust the paths accordingly.</p>
<p>For the complete hardened_malloc documentation, visit its
<a href="https://github.com/GrapheneOS/hardened_malloc#hardened_malloc">official documentation</a>.</p>
<p>This documentation is also available in portable AsciiDoc format in my
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</nav>
<section id="memory_pages">
<h2><a href="#memory_pages">Increase Permitted Amount of Memory Pages</a></h2>
<p>Add <code>vm.max_map_count = 1048576</code> to <code>/etc/sysctl.conf</code> to accommodate
hardened_malloc's large amount of guard pages.</p>
<p>Add the following to <code>/etc/sysctl.conf</code> or a configuration file within
<code>/etc/sysctl.d/</code>to accommodate hardened_malloc's large amount of guard pages:</p>
<pre>vm.max_map_count = 1048576</pre>
</section>
<section id="clone_source_code">
<h2><a href="#clone_source_code">Clone hardened_malloc Source Code</a></h2>
<p><code>$ git clone https://github.com/GrapheneOS/hardened_malloc.git</code></p>
<pre>$ git clone https://github.com/GrapheneOS/hardened_malloc.git</pre>
</section>
<section id="enter_local_repository">
<h2><a href="#enter_local_repository">Enter hardened_malloc Local Git Repository</a></h2>
<p><code>$ cd hardened_malloc/</code></p>
<pre>$ cd hardened_malloc/</pre>
</section>
<section id="compile">
<h2><a href="#compile">Compile hardened_malloc</a></h2>
<p><code>$ make <var>&lt;arguments&gt;</var></code></p>
<pre>$ make <var>&lt;arguments&gt;</var></pre>
<p><code>CONFIG_N_ARENA=<var>n</var></code> can be adjusted to increase parallel performance at the
expense of memory usage, or decrease memory usage at the expense of parallel performance, where
<code><var>n</var></code> is a non-negative integer. Higher values prefer parallel performance,
whereas lower values prefer lower memory usage. Note that having too many arenas may cause memory
fragmentation and decrease system performance. The number of arenas has no impact on the security
properties of hardened_malloc.</p>
<table align="center">
<thead>
<tr>
<th id="arena-min">Minimum</th>
<th id="arena-max">Maximum</th>
<th id="arena-def">Default</th>
</tr>
</thead>
<tbody>
<tr>
<td headers="arena-min">1</td>
<td headers="arena-max">256</td>
<td headers="arena-def">4</td>
</tr>
</tbody>
</table>
<div style="overflow-x:auto;">
<table align="center">
<thead>
<tr>
<th id="arena-min">Minimum</th>
<th id="arena-max">Maximum</th>
<th id="arena-def">Default</th>
</tr>
</thead>
<tbody>
<tr>
<td headers="arena-min">1</td>
<td headers="arena-max">256</td>
<td headers="arena-def">4</td>
</tr>
</tbody>
</table>
</div>
<p>For extra security, <code>CONFIG_SEAL_METADATA=true</code> can be used in order to control
whether
<a href="https://www.kernel.org/doc/html/v6.7/core-api/protection-keys.html">Memory Protection Keys</a>
<a href="https://www.kernel.org/doc/html/v6.9/core-api/protection-keys.html">Memory Protection Keys</a>
are used to disable access to all writable allocator state outside of the memory allocator code.
It's currently disabled by default due to a significant performance cost for this use case on
current-generation hardware. Whether or not this feature is enabled, the metadata is all contained
within an isolated memory region with high-entropy random guard regions around it.</p>
<p>For low-memory systems, <code>VARIANT=light</code> can be used to compile the light variant of
hardened_malloc, which sacrifices some security for much less memory usage. This option still
produces a more hardened memory allocator than both the default musl and glibc allocators, despite
the security sacrifices over the full variant.</p>
hardened_malloc, which sacrifices some security for less memory usage. This option still produces a
more hardened memory allocator than both the default musl and glibc allocators, despite the security
sacrifices over the full variant.</p>
<p>For all compile-time options, see the
<a href="https://github.com/GrapheneOS/hardened_malloc#configuration">configuration section</a>
of hardened_malloc's extensive official documentation.</p>
of hardened_malloc's official documentation.</p>
</section>
<section id="copy_library">
<h2><a href="#copy_library">Copy Compiled hardened_malloc Library</a></h2>
<p><code># cp out/libhardened_malloc.so <var>&lt;target path&gt;</var></code></p>
<pre># cp out/libhardened_malloc.so /usr/local/lib/libhardened_malloc.so</pre>
</section>
<section id="preload_on_boot">
<h2><a href="#preload_on_boot">Set System to Preload hardened_malloc on Boot</a></h2>
<p><b>musl-based systems:</b> Add <code>LD_PRELOAD=<var>&lt;hardened_malloc path&gt;</var></code> to
<code>/etc/environment</code></p>
<p><b>glibc-based systems:</b> Add <code><var>&lt;hardened_malloc path&gt;</var></code> to
<code>/etc/ld.so.preload</code></p>
<p>In order to preload the hardened_malloc shared library on boot, perform the following
actions:</p>
<p><b>musl-based systems:</b> Add the following to <code>/etc/environment</code> or a configuration
file within <code>/etc/environment.d/</code>:</p>
<pre>LD_PRELOAD=/usr/local/lib/libhardened_malloc.so</pre>
<p><b>glibc-based systems:</b> Add the following to <code>/etc/ld.so.preload</code>:</p>
<pre>/usr/local/lib/libhardened_malloc.so</pre>
</section>
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