One of the big topics of discourse in the Linux gaming sphere recently has been Tim Sweeney's statement on porting Fortnite to the Steam Deck, where Sweeney argues that Linux would be too difficult of a target and the market not big enough to warrant the amount of resources it would take to bring all of Fortnite on the platform.
The central crux of the issue, from Sweeney's point of view, is that making Easy Anti-Cheat, with all of its capabilities, run on Steam Deck (and thus on Linux) would be extremely difficult. He argues, that for a game of Fortnite's size this would open the flood-gates to significant influx of cheaters.
There have been some responses to this from the Linux side, with some accusing Sweeney of exaggerating the difficulty of such a port or that his statements are conflicting, because he simultaneously believes the Linux market is too small to be worthwhile but also would provide a way for too many cheaters. I will address some of these aspects a bit later, but for now let's focus on the main technical blocker, which is Easy Anti-Cheat.
Easy Anti-Cheat, or EAC, is an anti-cheat solution which apparently comes in a few configurations. We know that it can be run in a configuration where it is compatible with Linux/Proton apparently with just a relatively simple toggle. However, this mode of operation is seemingly a comparatively high-trust configuration, where only part of the anti-tampering protections of EAC are active. This may prevent some cheats but fail to detect others, which can be perfectly reasonable for games, where the number of cheaters and potential cheaters are fairly low or other systems complement the anti-cheat solution. There are plenty of games, even some popular free-to-play titles, which at best have this level of anti-tamper protection and they don't seem to have a major cheating epidemic, so clearly in many cases this should be enough. We also don't know the scope of cheats that are detected by EAC in this configuration, so this system by itself may already be fairly comprehensive.
EAC also contains a kernel-level component, which on Windows is installed as a kernel driver. This allows EAC code to run at a very privileged level and inspect essentially any and all parts of the system in order to detect tampering. This provides a very broad level of monitoring, which is also harder to bypass. Based on Sweeney's comments, this is the mode of operation used by Fortnite. It is also a mode of operation that is technically incompatible with the Linux way of doing things.
In Linux, the standard way of delivering drivers is by submitting the driver into the kernel source code tree, which naturally requires that the driver be open source. Most drivers are delivered this way, where the driver gets tightly integrated into the kernel and the drivers are updated when the kernel is updated. There are of course some notable exceptions to this rule, the largest of which is the Nvidia driver. The Nvidia driver is instead loaded as a separate kernel module, which allows Nvidia to keep its source code hidden, but also allows the driver to be updated separately from the kernel. So, EAC could surely use this approach as well, right?
The separate kernel module approach comes with some gotchas. Firstly, the kernel is licensed under GPLv2 and many of the parts in the kernel require the calling code to also be GPLv2 due to the "viral" quality of GPL. This means that, legally speaking, if Epic were to turn EAC into a kernel module and started poking around the kernel APIs, they'd have to open source EAC or they'd be in a legal grey area. The first approach is obviously not possible due to their business model and the second is at least not a great look.
Another problem with separate kernel modules is that the Linux kernel only guarantees a stable user-facing interface. This means that almost anything is allowed to change inside the kernel as long as user-level programs continue functioning. This is also the reason why sometimes the Nvidia driver stops working when you upgrade from one kernel to the next without installing an up-to-date Nvidia driver as well. So, when Sweeney is complaining about the multitude of kernel configurations, he's not wrong. EAC would need to maintain a compatibility shim similar to that of the Nvidia driver, which ensures that the EAC kernel module functions with each kernel version out there. Every time the kernel updates, an EAC engineer would need to go over the changes and update the compatibility shim every time there's a breaking change while still maintaining the compatibility with older kernel versions.
Theoretically you could overcome this problem somewhat by only targeting the Steam Deck and its SteamOS. This would give you a single kernel version to target, although Epic would need to negotiate with Valve in order to ensure their driver is somehow shipped with SteamOS.
But the problems don't end there. Since Linux is a fully open platform, there is technically nothing that would prevent a determined cheater from cracking open the Linux source code and making some tactical changes to how the kernel behaves, building the kernel and then making the EAC kernel module blind. On Windows the EAC developers can assume that the black box that is the NT kernel is at least somewhat difficult to modify by users. This means that in kernel-space they can assume some level of security through obscurity. On Linux this assumption does not hold. The only way for Epic to overcome that problem would be to negotiate with Valve to lock down the Steam Deck, which Valve has already decided not to do.
So, from EAC's point of view the Linux platform can never be quite fully trusted, which is entirely fair, because from the user's point of view EAC can never be quite fully trusted.
But surely Epic could still somehow bring Fortnite to the Steam Deck, right? Surely they could ship a version of Fortnite without the kernel-level component, right?
That they could, which brings us to the points about market share and the viability of cheating. Sweeney argues that the Linux market is too small, which initially sounds a bit odd because he then goes on to worry about the large numbers of cheaters. The kicker is here that the small Linux market doesn't necessarily guarantee a low number of cheaters. If it turns out that certain cheats are possible via a Linux version of Fortnite, this will attract some cheaters to use the platform in order to bypass EAC. It won't be all of the cheaters, many casual cheaters would likely not bother to learn Linux in order to cheat in a video game, but there is no doubt a group of cheaters that would take the opportunity. So, Fortnite would see some increase in cheating, but without good data it is hard to determine how big that effect would be. However, considering the popularity and free-to-play nature of Fortnite, it could very well be that it would be an attractive enough target for cheaters to attack even if there is a slightly higher initial investment. Cheat makers on the other hand would probably eventually find ways to package their offerings in an accessible enough format, like boot-to-cheat USBs or pre-configured VM images.
Some solutions to this problem have been proposed. For example, they could silo Steam Deck/Linux users in such a way that they will never come into contact with the rest of the playerbase. This would contain cheating, but it's also a hard-handed measure that would likely be unpopular. It would also require some amount of work to accomplish and I think it's fair for Epic to discount options that would cause extra work on them.
So, what's the solution to the problem? Here's the thing: I don't think there is one. My personal opinion is that client-side anti-cheat is fundamentally limited and taking it into the kernel is a bandaid that comes with excessive cost and is simply incompatible with the Linux platform. So, as long as Epic insists on maintaining its current anti-cheat approach with Fortnite, I just don't think there's going to be Fortnite on Linux.
And that doesn't mean Tim Sweeney is wrong or lying about the difficulties of adapting that approach to Linux. It just means that a new or different approach is needed in the future.
Article taken from GamingOnLinux.com.
EagleDelta Feb 9, 2022
Quoting: a0kamiThis indeed brings the question on future multiplayer games targetting Linux.
We need efficient models/processes/methods to prevent cheating by design in multiplayer games to come.
That may be true, but it sounds like right now, the Linux kernel itself is partially the blocker. Even if a specific kernel version was required, there would need to be additional tweaks added (and accepted) into the kernel to prevent users from running/writing programs that use the BPF VM within the kernel, for example.
That seems intense, but there are a few Windows AntiCheats that also require the user to disable certain Windows features just to use them. FaceIT requires that HyperV be disabled to utilize the anti-cheat in the CS:GO client. Basically that means, no VMs, no Docker, no WSL2, and no Application Isolation when running CS:GO on a server using FaceIT.
Anti-Cheat vendors basically would prefer that PCs running their ACs become console-like in user access
Last edited by EagleDelta on 9 February 2022 at 9:00 pm UTC
Quoting: a0kamiThis indeed brings the question on future multiplayer games targetting Linux.
We need efficient models/processes/methods to prevent cheating by design in multiplayer games to come.
What amazes me is that many don't even think about the fact that Valve itself runs a pretty extensive AC system. VAC works very well in conjunction with a pay barrier. Fortnite lacks this pay barrier.
Many of today's cheats are also based on external image recognition that directly controls the input devices. For the kernel, this appears as a normal mouse, keyboard or controller. Nothing at all is installed on the PC or console that could be recognised. EAC is also snake oil. Fortnite is full of cheaters.
I could cheat as much as I wanted in CSGO. Only VACNet/Overwatch would get me at some point and I would have to keep paying money for new accounts. Before that, the trust system would already match me against other cheaters.
In comparison, EAC is a pile of arcane bullshit that now maybe barely works.
Last edited by 1xok on 9 February 2022 at 9:10 pm UTC
No wonder why nobody flipped the switch yet.
Elden Ring has recently announced it will use EAC as well... So there is pretty no hope it will work on Proton :/
While I honestly don't give a shxxx of Fortnite, I would have loved to play Elden Ring on the Steam Deck.
Quoting: SamsaiQuoting: Lancabanwith everything saifd about the Linux kernel and different versions and hackabiltiy etc. yet it plays on Android, even on 3rd party Roms and Kernels just fine.Theoretically yes. I think the overriding issues are that Android is a market big enough to take the risk and generally speaking tech illiterate enough that the likelihood of someone installing a custom ROM to cheat in Fortnite is so unlikely, that it doesn't register as a realistic risk.
Would that not have the same exact issues and from a significantly larger player base than desktop Linux users?
Right now I can take my phone, root it, throw on a different Rom, and even use a different customized kernel, and still play Fortnite. This has been done, proven, viewed, tested, and seems to be OK.
Think you've just shot your own argument in the foot there.
It's a given than 99% of cheaters have no clue on how to write a cheat let alone a kernel driver on windows, Which also would be true for Linux side or the deck.
So the entire premise fails as a result of that theory.
The simple fat is that he has no intention of allowing fortnite on the deck. Am sure if the deck had been produced by say Samsung it wouldn't have been an issue.
Quoting: pete910Think you've just shot your own argument in the foot there.Different argument, production and consumption operate under different rules entirely. For a cheat to be popular, all you need is that 1% to make a few and a distribution method to get them in the hands of would-be cheaters. My argument on Android side is that there isn't an easy distribution method, because replacing a phone ROM is a more complex procedure than installing essentially an application or even booting up a VM image or flashing a USB stick.
It's a given than 99% of cheaters have no clue on how to write a cheat let alone a kernel driver on windows, Which also would be true for Linux side or the deck.
So the entire premise fails as a result of that theory.
And even in the case of some people booting a cheater ROM on their phone, Epic would be willing to make that deal simply due to the size of the market.
Clearly easy anticheat is a very dangerous backdoor in the already subpar protection of windows.
What I don't get is how something like easy anticheat can get it's stuff into the windows kernel. That means that microsoft is supporting them?
Mountain Man Feb 9, 2022
Last edited by Mountain Man on 9 February 2022 at 9:49 pm UTC
Quoting: EagleDeltaQuoting: SamsaiQuoting: Lancabanwith everything saifd about the Linux kernel and different versions and hackabiltiy etc. yet it plays on Android, even on 3rd party Roms and Kernels just fine.Theoretically yes. I think the overriding issues are that Android is a market big enough to take the risk and generally speaking tech illiterate enough that the likelihood of someone installing a custom ROM to cheat in Fortnite is so unlikely, that it doesn't register as a realistic risk.
Would that not have the same exact issues and from a significantly larger player base than desktop Linux users?
Right now I can take my phone, root it, throw on a different Rom, and even use a different customized kernel, and still play Fortnite. This has been done, proven, viewed, tested, and seems to be OK.
From everything I've read, they do try to prevent custom ROMs from playing the game. Even when those Custom ROMs do get it running, they have to have root disabled, play services must be installed, and safetynet must pass its checks, among other things.
So, it still requires a fairly locked down Android OS to run the game.
So in other words, they manage to implement some safeguards even when run under the evil Linux kernel :-)
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