For a website I'm using a nginx configuration that requires a client ssl certificate. I want my Symfony/php project to be able to verify that a client ssl certificate is being used (and provide some extra information from the certificate as well). So I was thinking of doing this by adding it to the request http header.

In my nginx site configuration I have set:

ssl_client_certificate /home/user/ssl/ca.crt;
ssl_verify_client on;

This works, the client certificate is obligatory.

But I want my underlaying Symfony/php project to be able to verify that a client certificate is being used. I was thinking of adding it to the http request header, but I seem only to be able to add it to the http response header (back to the browser) like this (in the same nginx site config):

location / {
        try_files $uri /app.php$is_args$args;
        add_header X-ssl-client-verify $ssl_client_verify;
    }

In firefox I can see this response header indeed, but that is not what I want (and can be a security hazzard). I've also looked into this:

proxy_set_header X-ssl-client-verify $ssl_client_verify;

But this does not work because I'm not using a proxy.

Is there some other way to add an element to the request header? Or is there an alternative way to get client ssl certificate information into my Symfony / php project?