Guide Safeguarding Against Unchecked And Potentially Damaging Plugins

[Cr1MsOn]

As Mojang continue to work towards the Minecraft Plugin API (cleaning up and rewriting the code), the code within Minecraft and CraftBukkit will undoubtedly shift. Fortunately, as the majority of the plugins available have been developed using only the Bukkit API (which was designed to be resilient and mostly update proof), this code shifting should not affect most of your servers.

If, however, you happen to be running a plugin that uses code outside of the Bukkit API (like Minecraft or CraftBukkit code), those plugins are highly likely to break and bring down your servers with them - often without any advanced warning - whenever a Minecraft update is released. In response to this very real problem, we've had to make the difficult decision of forcing plugin developers that use Minecraft and/or CraftBukkit code within their plugins to re-evaluate their work with the release of every Minecraft update to ensure they are still functioning as intended.

It is important to note that even if a plugin you have been using has been working fine across Minecraft updates until now, there is simply no way to guarantee that this will always be the case. Making the assumption that it will work with every update is like playing Russian roulette with your server.

The problem:
With the extensive work being done to Minecraft to accommodate the Minecraft Plugin API, the Minecraft code is now more unpredictable and volatile than ever before. These changes have made it clear that allowing plugins to run unchecked across Minecraft updates is a big mistake that puts your servers at significant risk of being silently damaged. Neither Bukkit nor plugin developers have any control over the Minecraft (and, as it is built upon Minecraft itself, CraftBukkit) code. Therefore, if a plugin uses code outside of the Bukkit API and it has not been verified to work on the Minecraft version your server is running, using it can only lead to unpredictable problems.

What makes matters worse and more confusing is that there is no easy way for you, as a server admin, to tell if the plugins you are using utilise only the Bukkit API or unsupported code within Minecraft and/or CraftBukkit itself. As plugin developers have no incentive to do so, they have not been putting up a notice informing server admins that their plugins use more than just the Bukkit API and thus server admins are left in the dark. Without this important knowledge, server admins have been blindly running plugins that are not ensured to function as intended across Minecraft versions, potentially and unknowingly putting their servers at risk.

Up until this safeguard was introduced, plugin developers were not required to verify that their plugins continued to function as they intended whenever a Minecraft update came out. As a result, potentially unstable plugins have been running unchecked on your server with no indication that they could damage your server at any time without any advanced warning. The fact of the matter is: plugins that depend on Minecraft or CraftBukkit code need to have their code verified whenever a Minecraft update is released before it can be said with absolute certainty that a plugin is safe to run on your server.

In summary:
- Mojang is cleaning up and rewriting the Minecraft code in anticipation for the Minecraft Plugin API.
- Plugins that use Minecraft or CraftBukkit code will break in unpredictable ways.
- You aren't told that a plugin is using unsupported and volatile code, so you likely aren't aware that plugins you are using could be silently breaking your servers.

The solution:
To address this problem, we've made the difficult decision of including a safeguard directly into CraftBukkit. This safeguard serves many purposes but the major ones are: it will help protect your server against unchecked plugins, it will make determining which plugins are breaking with every Minecraft updates and it will force plugin developers to take responsibility for what their plugins do to your server.

With this safeguard in place, a potentially damaging plugin will not be able to run until it has been updated with a version that has been checked by the plugin developer. Granted, plugin developers have the option of completely bypassing this safeguard and putting your server at risk. However, if they choose to do this it will be very clear who was responsible for any damage done to your server and you'll know to avoid that developer's work in the future.

Note: this safeguard is not intended to stop the use of code outside of the Bukkit API, but rather to promote more responsible use of it if a plugin developer decides to do so.

So what does this safeguard mean for you?
Server Admins:
If you are a server admin that only uses plugins developed against the Bukkit API, this safeguard doesn't affect you at all. If you are a server admin that uses plugins which use Minecraft or CraftBukkit code (which we do not support or recommend using) then this safeguard means that those plugins will need to be updated with every Minecraft update.

It is important to note that while this safeguard does force plugin developers to take some sort of action to get their plugins built against Minecraft or CraftBukkit working on a new Minecraft version, plugin developers have the option of bypassing it. They can blindly update a few lines in their code to mark it as working with a new Minecraft update or utilise a bypass to trick the safeguard into letting the plugin run. As such, we recommend that server admins be wary of plugin developers who decide to work around this, as they are willingly putting your server at risk.

Plugin Developers:
If you are a plugin developer that purely uses the Bukkit API this safeguard does not affect you in any way.

If, however, you depend on the extremely volatile and unsupported CraftBukkit OR Minecraft code, you will now have to re-evaluate your plugins with every Minecraft update release. As this is what you should have been doing anyway as a responsible developer, this should not affect your update process in any way.

We are not trying to make utilising Minecraft or CraftBukkit code within your plugins more difficult, we are simply trying to promote using it more responsibly if you have a need to do so within your plugins. If there is no way for you to avoid using the volatile and unsupported internals of Minecraft or CraftBukkit, we recommend trying to work with us to design an addition to the Bukkit API that removes this need.

What if I'd rather take the risk?
Server Admins:
If you'd rather put your server at risk by running unchecked code, you are free to bypass this safeguard, however you will no longer receive support from us as a result. If you'd still like to bypass or disable this safeguard, you have the option of running an unofficial build or a tool to update the plugins you use. Unfortunately, since providing support for code we did not write is next to impossible, we still do not allow the discussion and distribution of unofficial builds within our community.

Plugin Developers:
Plugin developers bypassing this safeguard are willingly putting servers at risk with their unpredictable and unchecked code. If you as a plugin developer choose to bypass this safeguard bear in mind that you are taking full responsibility for anything your plugin does to a server and that this decision can affect your reputation as a developer.

There are several ways to bypass this safeguard that I'm sure many of you will be discussing on these forums, however, we would like to make it clear that plugins using any bypass that includes dynamic code generation will be denied from BukkitDev without hesitation due to the inherent security risks it poses for servers.

Whether you are a server admin or a plugin developer, you are free to discuss ways to get around this safeguard provided it does not involve an unofficial build. The issue with unofficial builds is that regardless of where people get them from, we almost inevitably end up having to provide support for them.

We know that this safeguard might cause a few of you some headaches, however we feel that choosing to let servers burn in the coming weeks is not a viable option. Thank you for your continued support, cooperation and understanding in this matter. This was a difficult decision for us to make, but preventing unchecked plugins from silently destroying servers was a big incentive for us.

 

Credits: Bukkit forum.