As you probably know, Liferay Marketplace is an online store for obtaining applications that run on the Liferay Portal platform. These applications are provided not only by Liferay, but also by partners and independent developers who want you to install and use their applications on your server. Many of these applications are excellent, and we recommend that you try them out for yourself.
Because many of the applications on Marketplace are not provided by Liferay, however, there’s an issue of trust: how do you know these applications are doing what they’re advertised to do? There is a vetting process that they go through before they’re allowed on Marketplace, but if the source code is not provided, there’s no way for even Liferay to know if an app has been properly represented. For this reason, Liferay Portal implements a security layer we call the Portal Access Control List, or PACL.
PACL forces an application to declare up front the functions from Liferay’s APIs that it calls. Anything that’s not declared is not allowed to run. It’s similar to what you might see on your mobile phone when you install an app: you get to see the Liferay API functions the app uses, and then you can decide if you want to install that app based on the permissions it requires. This way, you see right away what portal data that app can access, and the app can do nothing else: you’re protected–if you have PACL enabled. So if you plan to use apps downloaded from Marketplace, it’s important to make sure PACL is enabled.
By default, Liferay’s bundles have PACL turned off. The reason for this is that there is a small performance penalty for having PACL enabled. Since the only reason to have PACL enabled is to install untrusted third party apps from Marketplace (and not everybody does that), we decided to leave PACL turned off by default, so that your portal performs as fast as possible.
All of this is to say: if you intend to use Marketplace apps, please enable
PACL. Later in this chapter, there are sections for all the app servers Liferay
supports. Each of those sections has a subsection that explains how to enable
Java security for that app server, which is a prerequisite for enabling PACL.
Once you have Java security enabled, PACL can be enabled by adding one line to
Save the file and if Liferay is running, restart it. Your portal is now configured to check PACL-enabled Marketplace apps against their declared permissions.
Next, you’ll make sure Liferay is configured properly for your network.