Use samesite lax for portal cookies

[Josue-T]

The problem

YunoHost-Apps/synapse_ynh#497

After more investigation it seem to be related to the samesite settings of the yunohost.portal cookie.

So I did 2 test one with yunohost 11 and one with yunohost 12. With this process:

• Install synapse
• Install element (on the yunohost instance)
• Login on the SSO
• Try to login on matrix from the local element instance
  • Pass on Yunohost 11
  • Pass on Yunohost 12
• Try to login on matrix from https://app.element.io (which is a completely other domain)
  • Pass on Yunohost 11
  • Fail on Yunohost 12

Now try to do this small fix on yunohost 12 and see that it solve the issue.

Note that there was already a discussion about this some year ago here: YunoHost/SSOwat#103

Solution

Use the same settings than on bullseye for the SSO cookie.

PR Status

Tested and it fixed the issue

How to test

Try to connect to a synapse server on a yunohost instance from https://app.element.io