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Digg Chapter 10. Magic QuotesTable of Contents
Warning:
This feature is DEPRECATED and REMOVED as of PHP 6.0.0. Relying on this feature is highly discouraged. Magic Quotes is a process that automagically escapes incoming data to the PHP script. It's preferred to code with magic quotes off and to instead escape the data at runtime, as needed.
When on, all There are three magic quote directives:
Code Examples / Notes » security.magicquotes07-dec-2005 02:09
You should try to avoid magic_quotes in all its flavors, use add_slashes() and strip_slashes() instead with user input and you will save time and avoid common problems that come along. You should know also that if your server has php suexec enabled you won't be able use php_flag in .htaccess file to change php values like magic_quotes or register_globals. In this case you might wanna try creating a php.ini file on the same directory as your script and add something like this: magic_quotes_runtime=off magic_quotes_gpc=off magic_quotes_sybase=off register_globals=on ; only as an example ---- Mel http://www.webhostingjournal.net/ 27-feb-2006 11:11
Using the .htaccess file may not always be possible for instance if you are running php on a windows IIS server. Also the code by jfrim at idirect dot com doesn't actually fix the problem as it is stripping slashes, what you need to do is addslashes to things coming in. the code by jfrim at idirect dot com is the right idea though although rather than saying stripslashes, you simply need to say addslashes and it should work. jfrim
Unfortunately magic_quotes_gpc can not be changed at run-time, but here's a code block which will effectively get rid of it when executed. Use this for PHP scripts which must be portable or run on servers where magic_quotes_gpc could be configured either way. Note that the PHP help is a little misleading... Magic_quotes_gpc affects more than just the Get, Post, and Cookie data! <?php //Prevent Magic Quotes from affecting scripts, regardless of server settings //Make sure when reading file data, //PHP doesn't "magically" mangle backslashes! set_magic_quotes_runtime(FALSE); if (get_magic_quotes_gpc()) { /* All these global variables are slash-encoded by default, because magic_quotes_gpc is set by default! (And magic_quotes_gpc affects more than just $_GET, $_POST, and $_COOKIE) */ $_SERVER = stripslashes_array($_SERVER); $_GET = stripslashes_array($_GET); $_POST = stripslashes_array($_POST); $_COOKIE = stripslashes_array($_COOKIE); $_FILES = stripslashes_array($_FILES); $_ENV = stripslashes_array($_ENV); $_REQUEST = stripslashes_array($_REQUEST); $HTTP_SERVER_VARS = stripslashes_array($HTTP_SERVER_VARS); $HTTP_GET_VARS = stripslashes_array($HTTP_GET_VARS); $HTTP_POST_VARS = stripslashes_array($HTTP_POST_VARS); $HTTP_COOKIE_VARS = stripslashes_array($HTTP_COOKIE_VARS); $HTTP_POST_FILES = stripslashes_array($HTTP_POST_FILES); $HTTP_ENV_VARS = stripslashes_array($HTTP_ENV_VARS); if (isset($_SESSION)) { #These are unconfirmed (?) $_SESSION = stripslashes_array($_SESSION, ''); $HTTP_SESSION_VARS = stripslashes_array($HTTP_SESSION_VARS, ''); } /* The $GLOBALS array is also slash-encoded, but when all the above are changed, $GLOBALS is updated to reflect those changes. (Therefore $GLOBALS should never be modified directly). $GLOBALS also contains infinite recursion, so it's dangerous... */ } function stripslashes_array($data) { if (is_array($data)){ foreach ($data as $key => $value){ $data[$key] = stripslashes_array($value); } return $data; }else{ return stripslashes($data); } } ?> richard dot spindler
to turn of magic quotes put the following line into the .htaccess file: php_flag magic_quotes_gpc off nitrous
This "feature" is the cause of so many escaping problems. It's very important to understand the implications of what magic quotes really do. Nearly every call, except those being written directly to the database, using user submitted data will require a call to strip_slashes. It gets very ugly very fast. What should be done is proper escaping of shell parameters and database parameters. PHP provides several escaping functions intended for this purpose. Slashes alone don't cut it anyway. 26-feb-2007 07:57
Or more simply: <?php private function stripslashes_deep($value) { $value = is_array($value) ? array_map(array($this, "stripslashes_deep"), $value) : stripslashes($value); return $value; } ?> php
most of the user contributed code related to stripping magic quotes posted could open vulnerabilities in your scripts as mentioned with a better sollution at: http://talks.php.net/show/php-best-practices/26 it supprises me that this link has not been previously referenced. judas dot iscariote
Just for the record. this feature has been removed as of PHP6. now PHP works always like if magic_quotes_gpc Off. get_magic_quotes_gpc, get_magic_quotes_runtime are kept but always return false, set_magic_quotes_runtime raises an E_CORE_ERROR. this is great news, magic_quotes were a big annoyance. webmaster
In response to jfrim at idirect dot com and the poster at 17-Jan-2007 09:37: Here's the code I use: <?php if (get_magic_quotes_gpc()) { function stripslashes_array($array) { return is_array($array) ? array_map('stripslashes_array', $array) : stripslashes($array); } $_COOKIE = stripslashes_array($_COOKIE); $_FILES = stripslashes_array($_FILES); $_GET = stripslashes_array($_GET); $_POST = stripslashes_array($_POST); $_REQUEST = stripslashes_array($_REQUEST); } ?> Magic_quotes_gpc does NOT effect $_SERVER or $_ENV, I tested this myself on Windows with Apache and PHP 5. Removing slashes from them when there were none added to begin with ruins the variables in them! I'm not sure at the moment whether it affects $_FILES or not, still looking into that one. shaun
In my tests with $_FILE, I found that file uploading didn't work when it was included in the function (Confirmed on Windows, not Apache.) The problem caused is: It removes the trailing / from what I have the tmp directory defined as. So: When PHP tries to move a tmp file using move_uploaded_file, it's trying to move tmpxxxx.tmp Whereas it should be trying to move: tmp/xxxx.tmp In conclusion: I found it easiest just to leave the $_FILES array alone. $_FILES works differently than $_POST anyway. It outputs an error if the file is invalid, so I'm not sure how someone could inject bad code into the field. If anyone else can check this problem on a Linux/Unix server, that would be great. 17-jan-2007 05:37
I think most of the people posting below are a little confused about how this works... To the person who said use addslashes rather than stripslashes... Well, the prefered use of MAGIC_QUOTES_GPC is off, so if you are designing code in such a manner well, using addlashes is of course going to do the same thing as having it turned on. DUH! Next on the agenda, is the guy who posted the code which the above anonymous person(s) made a comment about. Good, except design your code to not use the HTTP_GET_VARS etc at all, PHP3 is completely outdated... Turn off these options in your .INI/.htaccess/registry files (etc) as well! Additionally, I do not believe that MAGIC_QUOTES affects $_SERVER or $_ENV. I also don't think it affects $_FILES however these values ARE submitted from the user therefor may get escaped. Heres some code directly from a CMS I'm working on. # strips slashes to a multi dimensional array, by reference function stripslashes_arrays(&$array) { if ( is_array($array) ) { $keys = array_keys($array); foreach ( $keys as $key ) { if ( is_array($array[$key]) ) { stripslashes_arrays($array[$key]); } else { $array[$key] = stripslashes($array[$key]); } } } } # --- Handle input var escapes # magic_quotes_runtime could corrupt data, # so make sure it's turned off... set_magic_quotes_runtime(0); # All escapes are handled from code... # So rather, strip slashes if magic quotes is enabled if( get_magic_quotes_gpc() ) { stripslashes_arrays($_GET); stripslashes_arrays($_POST); stripslashes_arrays($_COOKIE); # stripslashes_arrays($_FILES); # verify $_FILES gets escapes by MAGIC_QUOTES first } 17-jul-2005 03:44
Bright minds will have noticed, that one uses stripslashes() once on the input and saves that content for further processing. Then use addslashes() once before sending the content to the database or flat file. Hint: if the application is using a MySql database, don't use addslashes() but mysql_real_escape_string(). edward
All the code listed on this page is not necessary if you use the php_flag directive in a .htaccess file. This allows you to disable magic quotes completely, without the need to adjust your php.ini file or (re)process the user's input. Just take a look at http://www.php.net/manual/en/security.magicquotes.php#55935 Gist of his note: in the .htaccess file, add a line php_flag magic_quotes_gpc off That's it. Thank you very much, richard dot spindler :) ! thomas dot hoggard
/**** * Recursivly removes all magicQuotes with multi-dimensional array support ****/ function removeMagicQuotes ($postArray, $trim = false) { if (get_magic_quotes_gpc() == 1) { $newArray = array(); foreach ($postArray as $key => $val) { if (is_array($val)) { $newArray[$key] = removeMagicQuotes ($val, $trim); } else { if ($trim == true) { $val = trim($val); } $newArray[$key] = stripslashes($val); } } return $newArray; } else { return $postArray; } } |
