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Subject svn commit: r650570 - /httpd/httpd/trunk/docs/manual/mod/mod_dbd.html.en
Date Tue, 22 Apr 2008 16:19:25 GMT
Author: noodl
Date: Tue Apr 22 09:19:06 2008
New Revision: 650570

Update transformations


Modified: httpd/httpd/trunk/docs/manual/mod/mod_dbd.html.en
--- httpd/httpd/trunk/docs/manual/mod/mod_dbd.html.en (original)
+++ httpd/httpd/trunk/docs/manual/mod/mod_dbd.html.en Tue Apr 22 09:19:06 2008
@@ -56,6 +56,7 @@
 <li><img alt="" src="../images/down.gif" /> <a href="#pooling">Connection
 <li><img alt="" src="../images/down.gif" /> <a href="#API">Apache DBD API</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#prepared">SQL Prepared
+<li><img alt="" src="../images/down.gif" /> <a href="#security">SECURITY
 </ul><h3>See also</h3>
 <ul class="seealso">
 <li><a href="../misc/password_encryptions.html">Password Formats</a></li>
@@ -129,6 +130,42 @@
     <p>It is up to dbd user modules to use the prepared statements
     and document what statements can be specified in httpd.conf,
     or to provide their own directives and use <code>ap_dbd_prepare</code>.</p>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"
+<div class="section">
+<h2><a name="security" id="security">SECURITY WARNING</a></h2>
+    <p>Any web/database application needs to secure itself against SQL
+    injection attacks.  In most cases, Apache DBD is safe, because
+    applications use prepared statements, and untrusted inputs are
+    only ever used as data.  Of course, if you use it via third-party
+    modules, you should ascertain what precautions they may require.</p>
+    <p>However, the <var>FreeTDS</var> driver is inherently
+    <strong>unsafe</strong>.  The underlying library doesn't support
+    prepared statements, so the driver emulates them, and the
+    untrusted input is merged into the SQL statement.</p>
+    <p>It can be made safe by <em>untainting</em> all inputs:
+    a process inspired by Perl's taint checking.  Each input
+    is matched against a regexp, and only the match is used,
+    according to the Perl idiom:</p>
+    <div class="example"><pre><code>  $untrusted =~ /([a-z]+)/;
+  $trusted = $1;</code></pre></div>
+    <p>To use this, the untainting regexps must be included in the
+    prepared statements configured.  The regexp follows immediately
+    after the % in the prepared statement, and is enclosed in
+    curly brackets {}.  For example, if your application expects
+    alphanumeric input, you can use:</p>
+    <div class="example"><p><code>
+       <code>"SELECT foo FROM bar WHERE input = %s"</code>
+    </code></p></div>
+    <p>with other drivers, and suffer nothing worse than a failed query.
+    But with FreeTDS you'd need:</p>
+    <div class="example"><p><code>
+       <code>"SELECT foo FROM bar WHERE input = %{([A-Za-z0-9]+)}s"</code>
+    </code></p></div>
+    <p>Now anything that doesn't match the regexp's $1 match is
+    discarded, so the statement is safe.</p>
+    <p>An alternative to this may be the third-party ODBC driver,
+    which offers the security of genuine prepared statements.</p>
 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"
 <div class="directive-section"><h2><a name="DBDExptime" id="DBDExptime">DBDExptime</a>
<a name="dbdexptime" id="dbdexptime">Directive</a></h2>

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