69 lines
2.4 KiB
HTML
69 lines
2.4 KiB
HTML
<html devsite>
|
|
<head>
|
|
<title>Security Enhancements in Android 1.5 through 4.1</title>
|
|
<meta name="project_path" value="/_project.yaml" />
|
|
<meta name="book_path" value="/_book.yaml" />
|
|
</head>
|
|
<body>
|
|
<!--
|
|
Copyright 2017 The Android Open Source Project
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
-->
|
|
|
|
|
|
|
|
<p>
|
|
Android provides a multi-layered security model described in the <a href="/security/index.html">Android
|
|
Security Overview</a>. Each update to Android includes dozens of
|
|
security enhancements to protect users. The following are some of the security
|
|
enhancements introduced in Android versions 1.5 through 4.1:</p>
|
|
|
|
<dl>
|
|
<dt><strong>Android 1.5</strong></dt>
|
|
<dd><ul>
|
|
<li>ProPolice to prevent stack buffer overruns (-fstack-protector)</li>
|
|
<li>safe_iop to reduce integer overflows</li>
|
|
<li>Extensions to OpenBSD dlmalloc to prevent double free() vulnerabilities and
|
|
to prevent chunk consolidation attacks. Chunk consolidation attacks are a
|
|
common way to exploit heap corruption.</li>
|
|
<li>OpenBSD calloc to prevent integer overflows during memory allocation</li>
|
|
</ul>
|
|
</dd>
|
|
|
|
<dt><strong>Android 2.3</strong></dt>
|
|
<dd><ul>
|
|
<li>Format string vulnerability protections (-Wformat-security -Werror=format-security)</li>
|
|
<li>Hardware-based No eXecute (NX) to prevent code execution on the stack and heap</li>
|
|
<li>Linux mmap_min_addr to mitigate null pointer dereference privilege
|
|
escalation (further enhanced in Android 4.1)</li>
|
|
</ul>
|
|
</dd>
|
|
|
|
<dt><strong>Android 4.0</strong></dt>
|
|
<dd>Address Space Layout Randomization (ASLR) to randomize key locations in memory
|
|
</dd>
|
|
|
|
<dt><strong>Android 4.1</strong></dt>
|
|
<dd><ul>
|
|
<li>PIE (Position Independent Executable) support</li>
|
|
<li>Read-only relocations / immediate binding (-Wl,-z,relro -Wl,-z,now)</li>
|
|
<li>dmesg_restrict enabled (avoid leaking kernel addresses)</li>
|
|
<li>kptr_restrict enabled (avoid leaking kernel addresses)</li>
|
|
</ul>
|
|
</dd>
|
|
|
|
</dl>
|
|
|
|
</body>
|
|
</html>
|