Файл: CodeIgniter-3.0.3/user_guide/libraries/security.html
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<div class="section" id="security-class">
<h1>Security Class<a class="headerlink" href="#security-class" title="Permalink to this headline">¶</a></h1>
<p>The Security Class contains methods that help you create a secure
application, processing input data for security.</p>
<div class="contents local topic" id="contents">
<ul class="simple">
<li><a class="reference internal" href="#xss-filtering" id="id1">XSS Filtering</a></li>
<li><a class="reference internal" href="#cross-site-request-forgery-csrf" id="id2">Cross-site request forgery (CSRF)</a></li>
<li><a class="reference internal" href="#class-reference" id="id3">Class Reference</a></li>
</ul>
</div>
<div class="custom-index container"></div><div class="section" id="xss-filtering">
<h2><a class="toc-backref" href="#id1">XSS Filtering</a><a class="headerlink" href="#xss-filtering" title="Permalink to this headline">¶</a></h2>
<p>CodeIgniter comes with a Cross Site Scripting prevention filter, which
looks for commonly used techniques to trigger JavaScript or other types
of code that attempt to hijack cookies or do other malicious things.
If anything disallowed is encountered it is rendered safe by converting
the data to character entities.</p>
<p>To filter data through the XSS filter use the <tt class="docutils literal"><span class="pre">xss_clean()</span></tt> method:</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$data</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-></span><span class="na">security</span><span class="o">-></span><span class="na">xss_clean</span><span class="p">(</span><span class="nv">$data</span><span class="p">);</span>
</pre></div>
</div>
<p>An optional second parameter, <em>is_image</em>, allows this function to be used
to test images for potential XSS attacks, useful for file upload
security. When this second parameter is set to TRUE, instead of
returning an altered string, the function returns TRUE if the image is
safe, and FALSE if it contained potentially malicious information that a
browser may attempt to execute.</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="k">if</span> <span class="p">(</span><span class="nv">$this</span><span class="o">-></span><span class="na">security</span><span class="o">-></span><span class="na">xss_clean</span><span class="p">(</span><span class="nv">$file</span><span class="p">,</span> <span class="k">TRUE</span><span class="p">)</span> <span class="o">===</span> <span class="k">FALSE</span><span class="p">)</span>
<span class="p">{</span>
<span class="c1">// file failed the XSS test</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="cross-site-request-forgery-csrf">
<h2><a class="toc-backref" href="#id2">Cross-site request forgery (CSRF)</a><a class="headerlink" href="#cross-site-request-forgery-csrf" title="Permalink to this headline">¶</a></h2>
<p>You can enable CSRF protection by altering your <strong>application/config/config.php</strong>
file in the following way:</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$config</span><span class="p">[</span><span class="s1">'csrf_protection'</span><span class="p">]</span> <span class="o">=</span> <span class="k">TRUE</span><span class="p">;</span>
</pre></div>
</div>
<p>If you use the <a class="reference internal" href="../helpers/form_helper.html"><em>form helper</em></a>, then
<tt class="xref py py-func docutils literal"><span class="pre">form_open()</span></tt> will automatically insert a hidden csrf field in
your forms. If not, then you can use <tt class="docutils literal"><span class="pre">get_csrf_token_name()</span></tt>
and <tt class="docutils literal"><span class="pre">get_csrf_hash()</span></tt></p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$csrf</span> <span class="o">=</span> <span class="k">array</span><span class="p">(</span>
<span class="s1">'name'</span> <span class="o">=></span> <span class="nv">$this</span><span class="o">-></span><span class="na">security</span><span class="o">-></span><span class="na">get_csrf_token_name</span><span class="p">(),</span>
<span class="s1">'hash'</span> <span class="o">=></span> <span class="nv">$this</span><span class="o">-></span><span class="na">security</span><span class="o">-></span><span class="na">get_csrf_hash</span><span class="p">()</span>
<span class="p">);</span>
<span class="o">...</span>
<span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"hidden"</span> <span class="nx">name</span><span class="o">=</span><span class="s2">"<?=</span><span class="si">$csrf['name']</span><span class="s2">;?>"</span> <span class="nx">value</span><span class="o">=</span><span class="s2">"<?=</span><span class="si">$csrf['hash']</span><span class="s2">;?>"</span> <span class="o">/></span>
</pre></div>
</div>
<p>Tokens may be either regenerated on every submission (default) or
kept the same throughout the life of the CSRF cookie. The default
regeneration of tokens provides stricter security, but may result
in usability concerns as other tokens become invalid (back/forward
navigation, multiple tabs/windows, asynchronous actions, etc). You
may alter this behavior by editing the following config parameter</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$config</span><span class="p">[</span><span class="s1">'csrf_regenerate'</span><span class="p">]</span> <span class="o">=</span> <span class="k">TRUE</span><span class="p">;</span>
</pre></div>
</div>
<p>Select URIs can be whitelisted from csrf protection (for example API
endpoints expecting externally POSTed content). You can add these URIs
by editing the ‘csrf_exclude_uris’ config parameter:</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$config</span><span class="p">[</span><span class="s1">'csrf_exclude_uris'</span><span class="p">]</span> <span class="o">=</span> <span class="k">array</span><span class="p">(</span><span class="s1">'api/person/add'</span><span class="p">);</span>
</pre></div>
</div>
<p>Regular expressions are also supported (case-insensitive):</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$config</span><span class="p">[</span><span class="s1">'csrf_exclude_uris'</span><span class="p">]</span> <span class="o">=</span> <span class="k">array</span><span class="p">(</span>
<span class="s1">'api/record/[0-9]+'</span><span class="p">,</span>
<span class="s1">'api/title/[a-z]+'</span>
<span class="p">);</span>
</pre></div>
</div>
</div>
<div class="section" id="class-reference">
<h2><a class="toc-backref" href="#id3">Class Reference</a><a class="headerlink" href="#class-reference" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="CI_Security">
<em class="property">class </em><tt class="descname">CI_Security</tt><a class="headerlink" href="#CI_Security" title="Permalink to this definition">¶</a></dt>
<dd><dl class="method">
<dt id="CI_Security::xss_clean">
<tt class="descname">xss_clean</tt><big>(</big><em>$str</em><span class="optional">[</span>, <em>$is_image = FALSE</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#CI_Security::xss_clean" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$str</strong> (<em>mixed</em>) – Input string or an array of strings</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">XSS-clean data</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">mixed</p>
</td>
</tr>
</tbody>
</table>
<p>Tries to remove XSS exploits from the input data and returns the cleaned string.
If the optional second parameter is set to true, it will return boolean TRUE if the image is safe to use and FALSE if malicious data was detected in it.</p>
</dd></dl>
<dl class="method">
<dt id="CI_Security::sanitize_filename">
<tt class="descname">sanitize_filename</tt><big>(</big><em>$str</em><span class="optional">[</span>, <em>$relative_path = FALSE</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#CI_Security::sanitize_filename" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$str</strong> (<em>string</em>) – File name/path</li>
<li><strong>$relative_path</strong> (<em>bool</em>) – Whether to preserve any directories in the file path</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Sanitized file name/path</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>Tries to sanitize filenames in order to prevent directory traversal attempts
and other security threats, which is particularly useful for files that were supplied via user input.</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$filename</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-></span><span class="na">security</span><span class="o">-></span><span class="na">sanitize_filename</span><span class="p">(</span><span class="nv">$this</span><span class="o">-></span><span class="na">input</span><span class="o">-></span><span class="na">post</span><span class="p">(</span><span class="s1">'filename'</span><span class="p">));</span>
</pre></div>
</div>
<p>If it is acceptable for the user input to include relative paths, e.g.
<em>file/in/some/approved/folder.txt</em>, you can set the second optional parameter, <tt class="docutils literal"><span class="pre">$relative_path</span></tt> to TRUE.</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$filename</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-></span><span class="na">security</span><span class="o">-></span><span class="na">sanitize_filename</span><span class="p">(</span><span class="nv">$this</span><span class="o">-></span><span class="na">input</span><span class="o">-></span><span class="na">post</span><span class="p">(</span><span class="s1">'filename'</span><span class="p">),</span> <span class="k">TRUE</span><span class="p">);</span>
</pre></div>
</div>
</dd></dl>
<dl class="method">
<dt id="CI_Security::get_csrf_token_name">
<tt class="descname">get_csrf_token_name</tt><big>(</big><big>)</big><a class="headerlink" href="#CI_Security::get_csrf_token_name" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Returns:</th><td class="field-body">CSRF token name</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body">string</td>
</tr>
</tbody>
</table>
<p>Returns the CSRF token name (the <tt class="docutils literal"><span class="pre">$config['csrf_token_name']</span></tt> value).</p>
</dd></dl>
<dl class="method">
<dt id="CI_Security::get_csrf_hash">
<tt class="descname">get_csrf_hash</tt><big>(</big><big>)</big><a class="headerlink" href="#CI_Security::get_csrf_hash" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Returns:</th><td class="field-body">CSRF hash</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body">string</td>
</tr>
</tbody>
</table>
<p>Returns the CSRF hash value. Useful in combination with <tt class="docutils literal"><span class="pre">get_csrf_token_name()</span></tt>
for manually building forms or sending valid AJAX POST requests.</p>
</dd></dl>
<dl class="method">
<dt id="CI_Security::entity_decode">
<tt class="descname">entity_decode</tt><big>(</big><em>$str</em><span class="optional">[</span>, <em>$charset = NULL</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#CI_Security::entity_decode" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$str</strong> (<em>string</em>) – Input string</li>
<li><strong>$charset</strong> (<em>string</em>) – Character set of the input string</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Entity-decoded string</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>This method acts a lot like PHP’s own native <tt class="docutils literal"><span class="pre">html_entity_decode()</span></tt> function in ENT_COMPAT mode, only
it tries to detect HTML entities that don’t end in a semicolon because some browsers allow that.</p>
<p>If the <tt class="docutils literal"><span class="pre">$charset</span></tt> parameter is left empty, then your configured <tt class="docutils literal"><span class="pre">$config['charset']</span></tt> value will be used.</p>
</dd></dl>
<dl class="method">
<dt id="CI_Security::get_random_bytes">
<tt class="descname">get_random_bytes</tt><big>(</big><em>$length</em><big>)</big><a class="headerlink" href="#CI_Security::get_random_bytes" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$length</strong> (<em>int</em>) – Output length</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">A binary stream of random bytes or FALSE on failure</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>A convenience method for getting proper random bytes via <tt class="docutils literal"><span class="pre">mcrypt_create_iv()</span></tt>,
<tt class="docutils literal"><span class="pre">/dev/urandom</span></tt> or <tt class="docutils literal"><span class="pre">openssl_random_pseudo_bytes()</span></tt> (in that order), if one
of them is available.</p>
<p>Used for generating CSRF and XSS tokens.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">The output is NOT guaranteed to be cryptographically secure,
just the best attempt at that.</p>
</div>
</dd></dl>
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