SSO with CN or email from client certificate?

I’m using Seafile behind Apache. I use my own rootCA to issue client certificates. I’ve configured verification of client certificates in Apaches vHost-config like this:

SSLCACertificateFile /path/to/rootCA.pem
SSLCARevocationFile /path/to/crl-file.crl
SSLVerifyClient require

Is it possible in Seafile to use SSL_CLIENT_S_DN_CN or SSL_CLIENT_S_DN_Email from apaches StdEnvVars for SSO-Authentication (without password and without Shibboleth overhead)?

No it’s not currently supported.