Codeigniter removes ALL html tags

If you are referring to the use of methods input, yes you can technically open system/libraries/Input.php, go to this code:

/**
* Clean Input Data
*
* This is a helper function. It escapes data and
* standardizes newline characters to \n
*
* @access   private
* @param    string
* @return   string
*/
function _clean_input_data($str)
{
    if (is_array($str))
    {
        $new_array = array();
        foreach ($str as $key => $val)
        {
            $new_array[$this->_clean_input_keys($key)] = $this->_clean_input_data($val);
        }
        return $new_array;
    }

    // We strip slashes if magic quotes is on to keep things consistent
    if (get_magic_quotes_gpc())
    {
        $str = stripslashes($str);
    }

    // Should we filter the input data?
    if ($this->use_xss_clean === TRUE)
    {
        $str = $this->xss_clean($str);
    }

    // Standardize newlines
    if (strpos($str, "\r") !== FALSE)
    {
        $str = str_replace(array("\r\n", "\r"), "\n", $str);
    }

    return $str;
}

And right after cleaning xss, you can put your own filter function as follows:

// Should we filter the input data?
if ($this->use_xss_clean === TRUE)
{
    $str = $this->xss_clean($str);
}

$str = strip_tags($str);

, , CodeIgniter, . , , , , , , , .

CodeIgniter Form Validation, , php, , strip_tags:

$this->form_validation->set_rules('usertext', 'User Text', 'required|strip_tags');

, , , , , .