Codeigniter CSRF protection VS tabs

Question

In the newish CodeIgniter v3, CSRF tokens are only valid once. As a result, I'm having some trouble dealing with multiple tabs:

1. Open a tab with Form1
2. Open a tab with Form2
3. Submit the tab with Form 1
4. Submit the tab with Form 2

Step 4 will results in a CSRF error. Obviously this is not ideal... How is onemeant to solve this?

Answer 1

Background

There is no need to regenerate the CSRF token upon each form submission. There is little security benefit - if the attacker could retrieve the token from your page then they already have won. This will enable your site to run cross-tabs without error.

See this page for some background on the security aspect: Why [you shouldn't] refresh CSRF token per form request?.

CodeIgniter v3

v3 uses a configuration item named csrf_regenerate. Set this to FALSE to prevent regeneration after each request.

CodeIgniter v2

The code CodeIgniter uses is discussed in this post: CSRF Protection in CodeIgniter 2.0: A closer look. The relevant code is below:

function csrf_verify()
{
    // If no POST data exists we will set the CSRF cookie
    if (count($_POST) == 0)
    {
        return $this>csrf_set_cookie();
    }

    // Do the tokens exist in both the _POST and _COOKIE arrays?
    if ( ! isset($_POST[$this->csrf_token_name]) OR
         ! isset($_COOKIE[$this->csrf_cookie_name]) )
    {
        $this->csrf_show_error();
    }

    // Do the tokens match?
    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]);

    // Re-generate CSRF Token and Cookie
    unset($_COOKIE[$this->csrf_cookie_name]);
    $this->_csrf_set_hash();
    $this->csrf_set_cookie();

    log_message('debug', "CSRF token verified ");
}

Simply remove the following code from the function:

// Re-generate CSRF Token and Cookie
unset($_COOKIE[$this->csrf_cookie_name]);
$this->_csrf_set_hash();
$this->csrf_set_cookie();