CI框架安全类Security.php源码分析
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CI安全类提供了全局防御CSRF攻击和XSS攻击策略，只需要在配置文件开启即可：
代码如下:
$config['csrf_protection'] = TRUE;
$config['global_xss_filtering'] = TRUE;
并提供了实用方法：
代码如下:
$this->security->xss_clean($data);//第二个参数为TRUE，验证图片安全
$this->security->sanitize_filename()//过滤文件名
CI也提供了安全函数：
xss_clean()//xss过滤
sanitize_filename()//净化文件名
do_hash()//md5或sha加密
strip_image_tags() //删除图片标签的不必要字符
encode_php_tags()//把PHP脚本标签强制转成实体对象
代码如下:
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
* 安全类
*/
class CI_Security {
//url的随机hash值
protected $_xss_hash = '';
//防csrf攻击的cookie标记的哈希值
protected $_csrf_hash = '';
//防csrf cookie过期时间
protected $_csrf_expire = 7200;
//防csrf的cookie名称
protected $_csrf_token_name = 'ci_csrf_token';
//防csrf的token名称
protected $_csrf_cookie_name = 'ci_csrf_token';
//不允许出现的字符串数组
protected $_never_allowed_str = array(
'document.cookie' => '[removed]',
'document.write' => '[removed]',
'.parentNode' => '[removed]',
'.innerHTML' => '[removed]',
'window.location' => '[removed]',
'-moz-binding' => '[removed]',
'<!--' => '<!--',
'-->' => '-->',
'<![CDATA[' => '<![CDATA[',
'<comment>' => '<comment>'
);
//不允许出现的正则表达式数组
protected $_never_allowed_regex = array(
'javascript\s*:',
'expression\s*(\(|&\#40;)', // CSS and IE
'vbscript\s*:', // IE, surprise!
'Redirect\s+302',
"([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?"
);
//构造函数
public function __construct()
{
// CSRF保护是否开启
if (config_item('csrf_protection') === TRUE)
{
// CSRF配置
foreach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key)
{
if (FALSE !== ($val = config_item($key)))
{
$this->{'_'.$key} = $val;
}
}
// _csrf_cookie_name加上cookie前缀
if (config_item('cookie_prefix'))
{
$this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name;
}
// 设置csrf的hash值
$this->_csrf_set_hash();
}
log_message('debug', "Security Class Initialized");
}
// --------------------------------------------------------------------
/**
* Verify Cross Site Request Forgery Protection
*
* @return object
*/
public function csrf_verify()
{
// 如果不是post请求，则设置csrf的cookie值
if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST')
{
return $this->csrf_set_cookie();
}
// Do the tokens exist in both the _POST and _COOKIE arrays?
if ( ! isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name]))
{
$this->csrf_show_error();
}
// token匹配吗
if ($_POST[$this->_csrf_token_name] != $_COOKIE[$this->_csrf_cookie_name])
{
$this->csrf_show_error();
}
// We kill this since we're done and we don't want to
// polute the _POST array
unset($_POST[$this->_csrf_token_name]);
// Nothing should last forever
unset($_COOKIE[$this->_csrf_cookie_name]);
$this->_csrf_set_hash();
$this->csrf_set_cookie();
log_message('debug', 'CSRF token verified');
return $this;
}
// --------------------------------------------------------------------
/**
* 设置csrf的cookie值
*/
public function csrf_set_cookie()
{
$expire = time() + $this->_csrf_expire;
$secure_cookie = (config_item('cookie_secure') === TRUE) ? 1 : 0;
if ($secure_cookie && (empty($_SERVER['HTTPS']) OR strtolower($_SERVER['HTTPS']) === 'off'))
{
return FALSE;
}
setcookie($this->_csrf_cookie_name, $this->_csrf_hash, $expire, config_item('cookie_path'), config_item('cookie_domain'), $secure_cookie);
log_message('debug', "CRSF cookie Set");
return $this;
}
//csrf保存
public function csrf_show_error()
{
show_error('The action you have requested is not allowed.');
}
//获取csrf的hash值
public function get_csrf_hash()
{
return $this->_csrf_hash;
}
//获取csrf的token值
public function get_csrf_token_name()
{
return $this->_csrf_token_name;
}
/**
* XSS 过滤
*/
public function xss_clean($str, $is_image = FALSE)
{
//是否是数组
if (is_array($str))
{
while (list($key) = each($str))
{
$str[$key] = $this->xss_clean($str[$key]);
}
return $str;
}
//去掉可见字符串
$str = remove_invisible_characters($str);
// 验证实体url
$str = $this->_validate_entities($str);
/*
* URL 解码
*
* Just in case stuff like this is submitted:
*
* <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a>
*
* Note: Use rawurldecode() so it does not remove plus signs
*
*/
$str = rawurldecode($str);
/*
* Convert character entities to ASCII
*
* This permits our tests below to work reliably.
* We only convert entities that are within tags since
* these are the ones that will pose security problems.
*
*/
$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_decode_entity'), $str);
/*
* Remove Invisible Characters Again!
*/
$str = remove_invisible_characters($str);
/*
* Convert all tabs to spaces
*
* This prevents strings like this: ja vascript
* NOTE: we deal with spaces between characters later.
* NOTE: preg_replace was found to be amazingly slow here on
* large blocks of data, so we use str_replace.
*/
if (strpos($str, "\t") !== FALSE)
{
$str = str_replace("\t", ' ', $str);
}
/*
* Capture converted string for later comparison
*/
$converted_string = $str;
// Remove Strings that are never allowed
$str = $this->_do_never_allowed($str);
/*
* Makes PHP tags safe
*
* Note: XML tags are inadvertently replaced too:
*
* <?xml
*
* But it doesn't seem to pose a problem.
*/
if ($is_image === TRUE)
{
// Images have a tendency to have the PHP short opening and
// closing tags every so often so we skip those and only
// do the long opening tags.
$str = preg_replace('/<\?(php)/i', "<?\\1", $str);
}
else
{
$str = str_replace(array('<?', '?'.'>'), array('<?', '?>'), $str);
}
/*
* Compact any exploded words
*
* This corrects words like: j a v a s c r i p t
* These words are compacted back to their correct state.
*/
$words = array(
'javascript', 'expression', 'vbscript', 'script', 'base64',
'applet', 'alert', 'document', 'write', 'cookie', 'window'
);
foreach ($words as $word)
{
$temp = '';
for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++)
{
$temp .= substr($word, $i, 1)."\s*";
}
// We only want to do this when it is followed by a non-word character
// That way valid stuff like "dealer to" does not become "dealerto"
$str = preg_replace_callback('#('.substr($temp, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);
}
/*
* Remove disallowed Javascript in links or img tags
* We used to do some version comparisons and use of stripos for PHP5,
* but it is dog slow compared to these simplified non-capturing
* preg_match(), especially if the pattern exists in the string
*/
do
{
$original = $str;
if (preg_match("/<a/i", $str))
{
$str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", array($this, '_js_link_removal'), $str);
}
if (preg_match("/<img/i", $str))
{
$str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", array($this, '_js_img_removal'), $str);
}
if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str))
{
$str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);
}
}
while($original != $str);
unset($original);
// Remove evil attributes such as style, onclick and xmlns
$str = $this->_remove_evil_attributes($str, $is_image);
/*
* Sanitize naughty HTML elements
*
* If a tag containing any of the words in the list
* below is found, the tag gets converted to entities.
*
* So this: <blink>
* Becomes: <blink>
*/
$naughty = 'alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss';
$str = preg_replace_callback('#<(/*\s*)('.$naughty.')([^><]*)([><]*)#is', array($this, '_sanitize_naughty_html'), $str);
/*
* Sanitize naughty scripting elements
*
* Similar to above, only instead of looking for
* tags it looks for PHP and JavaScript commands
* that are disallowed. Rather than removing the
* code, it simply converts the parenthesis to entities
* rendering the code un-executable.
*
* For example: eval('some code')
* Becomes: eval('some code')
*/
$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $str);
// Final clean up
// This adds a bit of extra precaution in case
// something got through the above filters
$str = $this->_do_never_allowed($str);
/*
* Images are Handled in a Special Way
* - Essentially, we want to know that after all of the character
* conversion is done whether any unwanted, likely XSS, code was found.
* If not, we return TRUE, as the image is clean.
* However, if the string post-conversion does not matched the
* string post-removal of XSS, then it fails, as there was unwanted XSS
* code found and removed/changed during processing.
*/
if ($is_image === TRUE)
{
return ($str == $converted_string) ? TRUE: FALSE;
}
log_message('debug', "XSS Filtering completed");
return $str;
}
// --------------------------------------------------------------------
//保护url的随机hash值
public function xss_hash()
{
if ($this->_xss_hash == '')
{
mt_srand();
$this->_xss_hash = md5(time() + mt_rand(0, 1999999999));
}
return $this->_xss_hash;
}
// --------------------------------------------------------------------
/**
* html实体转码
*/
public function entity_decode($str, $charset='UTF-8')
{
if (stristr($str, '&') === FALSE)
{
return $str;
}
$str = html_entity_decode($str, ENT_COMPAT, $charset);
$str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);
return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);
}
// --------------------------------------------------------------------
//过滤文件名，保证文件名安全
public function sanitize_filename($str, $relative_path = FALSE)
{
$bad = array(
"../",
"<!--",
"-->",
"<",
">",
"'",
'"',
'&',
'$',
'#',
'{',
'}',
'[',
']',
'=',
';',
'?',
"%20",
"%22",
"%3c", // <
"%253c", // <
"%3e", // >
"%0e", // >
"%28", // (
"%29", // )
"%2528", // (
"%26", // &
"%24", // $
"%3f", // ?
"%3b", // ;
"%3d" // =
);
if ( ! $relative_path)
{
$bad[] = './';
$bad[] = '/';
}
$str = remove_invisible_characters($str, FALSE);
return stripslashes(str_replace($bad, '', $str));
}
//压缩单词如j a v a s c r i p t成javascript
protected function _compact_exploded_words($matches)
{
return preg_replace('/\s+/s', '', $matches[1]).$matches[2];
}
// --------------------------------------------------------------------
/*
* 去掉一些危害的html属性
*/
protected function _remove_evil_attributes($str, $is_image)
{
// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns
$evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction');
if ($is_image === TRUE)
{
/*
* Adobe Photoshop puts XML metadata into JFIF images,
* including namespacing, so we have to allow this for images.
*/
unset($evil_attributes[array_search('xmlns', $evil_attributes)]);
}
do {
$count = 0;
$attribs = array();
// find occurrences of illegal attribute strings with quotes (042 and 047 are octal quotes)
preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is', $str, $matches, PREG_SET_ORDER);
foreach ($matches as $attr)
{
$attribs[] = preg_quote($attr[0], '/');
}
// find occurrences of illegal attribute strings without quotes
preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*([^\s>]*)/is', $str, $matches, PREG_SET_ORDER);
foreach ($matches as $attr)
{
$attribs[] = preg_quote($attr[0], '/');
}
// replace illegal attribute strings that are inside an html tag
if (count($attribs) > 0)
{
$str = preg_replace('/(<?)(\/?[^><]+?)([^A-Za-z<>\-])(.*?)('.implode('|', $attribs).')(.*?)([\s><]?)([><]*)/i', '$1$2 $4$6$7$8', $str, -1, $count);
}
} while ($count);
return $str;
}
// --------------------------------------------------------------------
/**
* 净化html,补齐未关闭的标签
*/
protected function _sanitize_naughty_html($matches)
{
// encode opening brace
$str = '<'.$matches[1].$matches[2].$matches[3];
// encode captured opening or closing brace to prevent recursive vectors
$str .= str_replace(array('>', '<'), array('>', '<'),
$matches[4]);
return $str;
}
// --------------------------------------------------------------------
/**
* 过滤超链接中js
*/
protected function _js_link_removal($match)
{
return str_replace(
$match[1],
preg_replace(
'#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si',
'',
$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
),
$match[0]
);
}
// --------------------------------------------------------------------
/**
* 过滤图片链接中的js
*/
protected function _js_img_removal($match)
{
return str_replace(
$match[1],
preg_replace(
'#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si',
'',
$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
),
$match[0]
);
}
// --------------------------------------------------------------------
/**
* 转换属性，将一些字符转换成实体
*/
protected function _convert_attribute($match)
{
return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);
}
// --------------------------------------------------------------------
//过滤html标签属性
protected function _filter_attributes($str)
{
$out = '';
if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches))
{
foreach ($matches[0] as $match)
{
$out .= preg_replace("#/\*.*?\*/#s", '', $match);
}
}
return $out;
}
// --------------------------------------------------------------------
//html实体转码
protected function _decode_entity($match)
{
return $this->entity_decode($match[0], strtoupper(config_item('charset')));
}
// --------------------------------------------------------------------
/**
* 验证url实体
*/
protected function _validate_entities($str)
{
/*
* Protect GET variables in URLs
*/
// 901119URL5918AMP18930PROTECT8198
$str = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-]+)|i', $this->xss_hash()."\\1=\\2", $str);
/*
* Validate standard character entities
*
* Add a semicolon if missing. We do this to enable
* the conversion of entities to ASCII later.
*
*/
$str = preg_replace('#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i', "\\1;\\2", $str);
/*
* Validate UTF16 two byte encoding (x00)
*
* Just as above, adds a semicolon if missing.
*
*/
$str = preg_replace('#(&\#x?)([0-9A-F]+);?#i',"\\1\\2;",$str);
/*
* Un-Protect GET variables in URLs
*/
$str = str_replace($this->xss_hash(), '&', $str);
return $str;
}
// ----------------------------------------------------------------------
//过滤不允许出现的字符串
protected function _do_never_allowed($str)
{
$str = str_replace(array_keys($this->_never_allowed_str), $this->_never_allowed_str, $str);
foreach ($this->_never_allowed_regex as $regex)
{
$str = preg_replace('#'.$regex.'#is', '[removed]', $str);
}
return $str;
}
// --------------------------------------------------------------------
//设置csrf的hash值
protected function _csrf_set_hash()
{
if ($this->_csrf_hash == '')
{
// 如果_csrf_cookie_name存在，直接作为csrf hash值
if (isset($_COOKIE[$this->_csrf_cookie_name]) &&
preg_match('#^[0-9a-f]{32}$#iS', $_COOKIE[$this->_csrf_cookie_name]) === 1)
{
return $this->_csrf_hash = $_COOKIE[$this->_csrf_cookie_name];
}
//否则随机一个md5字符串
return $this->_csrf_hash = md5(uniqid(rand(), TRUE));
}
return $this->_csrf_hash;
}
}
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