session - How to tell PHP to use SameSite=None for cross-site cookies?

Question

According to the article here https://php.watch/articles/PHP-Samesite-cookies and PHP documenation at https://www.php.net/manual/en/session.security.ini.php, There are only 2 possible config options for this new feature, added in PHP 7.3:

1. session.cookie_samesite=Lax
2. session.cookie_samesite=Strict

Yet, according to the Chrome console, this needs to be set to "None":

A cookie associated with a cross-site resource at URL was set without the SameSite attribute. It has been blocked, as Chrome now only delivers cookies with cross-site requests if they are set with SameSite=None and Secure. You can review cookies in developer tools under Application>Storage>Cookies and see more details at URL and URL.

Because of this, I can no longer set cross-site cookies. What is the workaround?

Answer 1

You can set the value to "None" using ini_set. There's no check that the value is supported when that function is used:

ini_set('session.cookie_samesite', 'None');
session_start();

session_set_cookie_params can also set it:

session_set_cookie_params(['samesite' => 'None']);
session_start();

The bug report for this to be supported in php.ini is here.

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As @shrimpwagon said in a comment below, session.cookie_secure must be true for this to work. PHP doesn't require it, but browsers do.