Excessive for my threat model, one more thing which could break something (even if by no fault of its own).

I like it, but many of my devices don’t use it.

It surprises me. Rather it’s not SELinux it’s userland stuff that reports the wrong error.

Say I try to mount a directory into a podman container and try to read a file. I get some variety of file not found (it’s right there, I can see it) or permission denied error (its permissions are 777) but in reality its label is wrong.

For 2 years, I had to set up production environments on RHEL, mostly Apache and Keycloak servers. I had a limited, very specific list of sudo permissions, and I had to ask very specifically what I else needed, which was then granted by people who neither knew nor cared what I was working on.

SELinux permission problems were always the fallback reason when nothing else made sense. With my permissions, I could not just straight up check for it. E. g. Apache would not server a folder, cryptic error -> check file permissions -> check general Apache config problems -> assume SELinux permission is missing and request it, supplying the exact command they need to type.

1. It’s extraordinarily complex.

The reality is that security is not just technical implementation, but also actually getting people to use the solutions. “Stop disabling SELinux” is not a real answer to when people disable it, like we have one person in this thread.

Another problem with complex security solutions is they are hard to get right. Even if you enable them and configure them, without being an expert, it’s possible you left a gap here or there, and holes and gaps in these solutions.*

2. Like so many other complex linux security solutions, it is lacking effectiveness due to still sharing the same kernel.

There is a good, but bit dated writeup here about the problems with Linux security, from an architecturual perspective: https://madaidans-insecurities.github.io/linux.html . But, the short version is that the Linux kernel is large and complex, and has a lot of attack surface. And it’s a frequent source of vulnerabilities because attackers can hit it as long as they access to the kernel, even if they are in a container/sandbox. Like, copyfail and dirtyfrag would punch through containers, but also punch through SELinux.

For example, just earlier on lemmy someone dropped a zero day that punches through SELinux: https://programming.dev/post/51103657

Now, SELinux can be used to restrict what a root shell could do after escalating… but that’s further complexity you have to learn to configure, and configure it correctly as well.

Ultimately, none of the Linux security solutions come anywhere near the isolation of simply running something in a virtual machine. Which, also happens to be a lot simpler and actually possible to get people to use.

*(putting this at the bottom because it veers off topic) I have a greater argument and problem with mentalities like this. I have noticed a pattern, where many of the more effortfull and toil intensive security solutions are recommended by people who have the time, energy, and skills to execute them. They have a bias/blindspot to the realities, which is that not everyone is in the same situation as them.

For example, updating/patching software. Linux distros like RHEL or Debian, have a policy where they only do security updates, and don’t do feature updates or bugfixes. This enables them to ship automatic updates, so that security issues are automatically handled.

On the other hand software like Windows, likes to bundle in breaking changes along with security updates. So automatic updates get disabled because “They might break something”. And then, people don’t update them, and environments get horrifically out of date, because not enough money/time/people is put into regular IT people who are in charge of maintaining them.

But some environments, have heroes, people who go around patching everything and keeping everything up to date and secure. And when they see these environments that don’t have everything patched, they usually give the advice of “You should patch everything” (while simultaneously advising against auto updates), not understanding that these environments are lacking a key ingredient: Themselves.

Sure, I could be a hero. I could “patch” everything manually. I could deploy SELinux. But that would only last until I get burnt out, or leave. Once I’m gone, SELinux, the patches, any similar security solutions are gone. I’ve met so many people, even in cybersecurity, that are apathetic about security, even though they might have cared once upon a time.

I’ve encountered it very little, but when I encounter it it’s because I try to do something and it doesn’t work. So I check the permissions with ls -l, and it all seems reasonable. Huh, this should work. Try again, nope. Hmm. 20 minutes of trying random variations, strange results. Oh fuck, is this SELinux? Shit. Where do those configs exist again? How do I configure that? Google “SELinux cheat sheet” hmmm, I don’t have enough context to use that, Google “SELinux getting started”. Read tutorial, try to skim just enough to figure out what’s going wrong for me.

So I don’t hate it, I just haven’t ever had a use for it, but it has surprised me in a bad way before and cost me a lot of time and confusion, but I’ve never spent the time getting familiar because I’ve never had a use for it. And it comes up rarely enough I never remember anything about it by the time it bites me. I can’t even recall now what I was trying to do the last time I bumped into it.

It’s awesome, but very complicated to use and overkill for most homegamer setups.

The first interaction most people have with it is when it stops something they want to do from working and it’s not obvious why. Then the first selinux command they learn is how to disable it.

Linux permissions are obvious, straightforward, and very easy to change - They rule.

SELinux permissions are impossible to see, seemingly pointlessly more complex, and I don’t know how to check them or change them i.e. They drool.

As a power user who is constantly changing system stuff, installing weird stuff, running weird servers, disabling SELinux is like, step 2 of installing Linux for me (and honestly, even if you’re not a power user, I can assure you at least ONE issue you’ve faced was actually caused by SELinux under the hood). I have wasted whole days working out just that SELinux is causing my fucking issue, and then days more on how to fix the permissions, and then days more doing those again when those permissions RESET as it is wont to do and days more trying to make my needed changes permanent. And let’s not even get started on how to transplant an SELinux permissions structure from one disk to another. So instead of a week’s worth of frustrating work every year, I can spend one minute disabling SELinux.

Its implementation feels contradictory to the most basic principles of understandable and workable systems. It’s like the NSA wanted to make software that was the diametric opposite of the Zen of Python. It’s ugly, it’s implicit, it’s complicated, nested, dense, unreadable, full of special cases, and silent errors, it constantly guesses in the face of ambiguity (which is why I have to constantly correct it).

Basically, I have wasted too much of my life faffing with an opaque and ludicrously complex permissions layer that seems to be there solely as a ‘just in case’ my already existing permissions aren’t good enough.

It’s an unnecessary layer of complexity. I am the only user of my personal laptop. I don’t need fine-grained permissions. Linux users and groups are enough for any permission needs I might have, like docker group, audio and video groups, etc. I don’t have any “classified” documents on my computer. My home directory and root are on different disks. I can easily format and reinstall my system if something goes wrong and keep all my personal data.

I’m more familiar with AppArmor, and my distro’s forum gives the impression that switching involves a lot of configuration to get things working as expected…which, AppArmor did too, but I’ve done that already. Next time I install, I might try SELinux.

If you’re mandated or regulated to implement MLS or MAC etc, SELinux is a security control that enables you to comply through expanded and expressive policy controls.

When I hear dislike for it, it’s usually because people are using SELinux as a “make my personal computer safer” tool rather than the “we’ve hundreds of thousands of differently classified sensitive documents and thousands of employees with different clearances”.

MAC/DAC/MLS isn’t designed for personal computing and if you think SELinux is the solution you personally need, you might need to reevaluate your threat model (as any external actor will seek to bypass kernel controls entirely e.g. CVE-2025-0078).

I no reasons for disliking it. SELinux is an incredibly powerful security tool.

I don’t dislike it. I have no opinion on it. It’s something I have never looked into heavily enough as it has never been a potential solution to a problem I may have encountered. There are no security or hardening areas that I currently class as gaps that need plugging in any of my systems where I would consider looking into selinux.

Uh. I guess people have random opinions and blast them on the internet. I can see how someone would misconfigure their computer and then blame it on the software. Or use software they don’t need, which just adds unnecessary complexity and more issues. Other than that, I don’t think there’s anything wrong with SELinux.

After switching between distros for 8+ years and settling on Fedora KDE, I don’t think I’ve ever had SELinux get in my way for anything.

Who said that? I really like it.