mirror of
https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
153 lines
6.9 KiB
HTML
153 lines
6.9 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Security</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="up" href="env.html" title="Chapter 9. The Berkeley DB Environment" />
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<link rel="prev" href="env_region.html" title="Shared memory regions" />
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<link rel="next" href="env_encrypt.html" title="Encryption" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 18.1.40</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Security</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="env_region.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 9. The Berkeley DB Environment </th>
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<td width="20%" align="right"> <a accesskey="n" href="env_encrypt.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="env_security"></a>Security</h2>
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</div>
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</div>
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</div>
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<p>
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The following are security issues that should be considered
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when writing Berkeley DB applications:
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</p>
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<div class="variablelist">
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<dl>
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<dt>
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<span class="term">Database environment permissions</span>
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</dt>
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<dd>
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The directory used as the Berkeley DB database
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environment should have its permissions set to ensure
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that files in the environment are not accessible to
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users without appropriate permissions. Applications
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that add to the user's permissions (for example, UNIX
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setuid or setgid applications), must be carefully
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checked to not permit illegal use of those permissions
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such as general file access in the environment
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directory.
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</dd>
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<dt>
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<span class="term">Environment variables</span>
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</dt>
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<dd>
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Setting the <a href="../api_reference/C/envopen.html#envopen_DB_USE_ENVIRON" class="olink">DB_USE_ENVIRON</a> and
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<a href="../api_reference/C/envopen.html#envopen_DB_USE_ENVIRON_ROOT" class="olink">DB_USE_ENVIRON_ROOT</a> flags and allowing the use of
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environment variables during file naming can be
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dangerous. Setting those flags in Berkeley DB
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applications with additional permissions (for example,
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UNIX setuid or setgid applications) could potentially
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allow users to read and write databases to which they
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would not normally have access.
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</dd>
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<dt>
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<span class="term">File permissions</span>
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</dt>
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<dd>
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By default, Berkeley DB always creates files
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readable and writable by the owner and the group (that
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is, S_IRUSR, S_IWUSR, S_IRGRP and S_IWGRP; or octal
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mode 0660 on historic UNIX systems). The group
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ownership of created files is based on the system and
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directory defaults, and is not further specified by
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Berkeley DB.
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</dd>
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<dt>
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<span class="term">Temporary backing files</span>
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</dt>
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<dd>
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If an unnamed database is created and the cache
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is too small to hold the database in memory, Berkeley
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DB will create a temporary physical file to enable it
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to page the database to disk as needed. In this case,
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environment variables such as <span class="bold"><strong>TMPDIR</strong></span>
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may be used to specify the
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location of that temporary file. Although temporary
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backing files are created readable and writable by the
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owner only (S_IRUSR and S_IWUSR, or octal mode 0600 on
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historic UNIX systems), some filesystems may not
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sufficiently protect temporary files created in random
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directories from improper access. To be absolutely
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safe, applications storing sensitive data in unnamed
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databases should use the <a href="../api_reference/C/envset_tmp_dir.html" class="olink">DB_ENV->set_tmp_dir()</a> method to
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specify a temporary directory with known
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permissions.
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</dd>
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<dt>
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<span class="term">Tcl API</span>
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</dt>
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<dd>
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The Berkeley DB Tcl API does not attempt to
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avoid evaluating input as Tcl commands. For this
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reason, it may be dangerous to pass unreviewed user
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input through the Berkeley DB Tcl API, as the input
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may subsequently be evaluated as a Tcl command.
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Additionally, the Berkeley DB Tcl API initialization
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routine resets process' effective user and group IDs
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to the real user and group IDs, to minimize the
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effectiveness of a Tcl injection attack.
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</dd>
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<dt>
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<span class="term">Private Environments</span>
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</dt>
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<dd>
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When using the environment flag DB_PRIVATE, it is
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possible for old data in the heap to leak onto unused
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parts of the database page. This can be avoided by
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not using that flag, or by compiling Berkeley DB with
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the UMWR flag.
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</dd>
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</dl>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="env_region.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="env.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="env_encrypt.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Shared memory regions </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Encryption</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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