Thursday, 12 January 2017

Configuring a more secure password hash for OpenLDAP

While working on the Galapagos infrastructure, we ran in to an interesting issue: using passwd(1) as an LDAP user would cause it to add another password instead of modifying it. Setting up the slapo-ppolicy(5) overlay then caused passwd(1) to then fail with:

password change failed: Password policy only allows one password value
passwd: Authentication token manipulation error
passwd: password unchanged

After consulting the #openldap channel on Freenode, the problem turned out to be that although OpenLDAP allows you to set olcPasswordHash on the root cn=config node, it does not work correctly when set there; it must be set under olcDatabase={-1}frontend,cn=config. Note, however, that olcPasswordCryptSaltFormat does belong in cn=config directly.

Sunday, 8 January 2017

Configuring Apache 2.4 to serve GitLab over TLS / HTTPS

As part of my work assisting in the set up of the infrastructure for Galapagos Linux, I volunteered to install and configure GitLab. My colleagues had attempted to use the Debian Omnibus package, but that failed in spectacular ways, including references to directories in the configuration that did not exist after package installation.

The most important piece of advice I can give is that you absolutely must use Bundler v1.10.6 or older[1] to ensure that you do not receive Gemfile.lock errors. You will also need to make a small modification to the Gemfile and Gemfile.lock file to ensure that libv8 is present if you wish to precompile the assets.

Now, for the Apache configuration. Note that I assume you have enabled https in GitLab's config/gitlab.yml and set port: 443. You will need to set a forwarding request header[2] to ensure that GitLab does not throw CSRF authentication errors. Also, if you want to use the recommended Unix sockets of Unicorn, you will need to configure the ProxyPass and ProxyPassReverse to use unix:/path/to/socket|http://HOSTNAME (thanks, Xayto!) - the full VirtualHost for GitLab goes something like this:

<VirtualHost *:443>
        ProxyPass / unix:/home/git/gitlab/tmp/sockets/gitlab.socket|
        ProxyPassReverse / unix:/home/git/gitlab/tmp/sockets/gitlab.socket|
        SSLEngine on
        SSLCertificateFile /path-to-certificate.crt
        SSLCertificateKeyFile /path-to-key.key
        SSLCertificateChainFile /path-to-ca-chain.crt
        Header always set Strict-Transport-Security "max-age=15768000"
        RequestHeader set X_FORWARDED_PROTO 'https'

<VirtualHost *:80>
        Redirect permanent /

Additionally, I recommend that you follow Mozilla MozWiki's great TLS advice or use their super handy, easy config generator as a global configuration that applies to all of your VirtualHosts. On Debian, you can pop that in to /etc/apache2/mods-available/ssl.conf, replacing the parameters they already specify.

Happy hacking!