The Flaws of Flatpak - What do you think about Flatpak Security?

redd@discuss.tchncs.de to Linux@lemmy.ml – 48 points –
youtu.be
  • Are you using Flatpaks?
  • Are you trusting Flathub?
  • Do you bother about the sandboxing and security?
48

I expect the Flatpak sandbox to protect my ~/ from getting cluttered by applications, not to protect me from any actually malicious software. The post's premise seems misguided.

YES. I don't understand this delusion people keep perpetuating. Flatpak has a MILD form of container sandboxing. For a real security sandbox we have Firejails or Bubble wrap.

Flatpak is, at it's core, a software development and distribution packaging format. NOT a security implementation.

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I always check my flatpak settings post install before running the app and adjust permissions according to need. I mean it does offer more security to me since it's user installed, I can granularly update permissions and control more or less where and what is can touch.

Alternatives to this are SELinux,AppArmour and firejails which are slightly more inconvenient to use.

To me that is mostly secure,or secure enough.

Well and then there's some immutable distros which might help overall.

Edit: paragraphs

If we admit that then an app store where anyone can create an account and upload software becomes extremely problematic. This is especially true wherein clients autoupgrade very quickly.

Step one. Legit package a popular app Step two. Wait for substantial uptake Step three. Mix in some ad or malware and watch a tens of thousands get instantly owned.

Anybody can become a community packager for Debian, Fedora, etc.

Anyone can't become a packager in 30 seconds in an automated process that they can' t repeat the 47th time they transmit malware.

The process is identical.

You show up with a package. It gets a basic review. You are granted commit access to your package. You can push changes.

There is slightly more oversight in that another mentor often also has commit access but they can’t and don’t review everything.

Yeah, Flatpak was never meant to be a security mechanism. It is a convenient way to add security to userland though.

In addition to own new code, bundled copies of libraries in packages introduces net new attack surface which isn't patched via the regular distribution security patch process. The image decoding lib that allows remote code execution now exists in flatpaks independently from the one in /lib. Every flatpak vendor that contains it has to build and ship their own patched version of it. This is even more valid for any other libraries flatpaks include that don't exist on the system. The most widely used Linux OSes come with security patching processes, expectations and sometimes guarantees. This new attack surface breaks those and the solution is security sandboxing. This approach has been proven in mobile app packaging and distribution systems. Android is a great example where apps are not trusted by default and vulnerable ones rarely cause collateral damage on otherwise up-to-date Android systems. This is an objective problem with the out-of-band distribution model allowed by flatpak and snap or any similar system, whether you care about it or not personally. It's a well understood tradeoff in software development. It has to be addressed as adoption grows or we risk reducing Linux security to the levels of Windows where apps regularly bundle dependencies with no sandboxing whatsoever.

Every Flatpak vendor

So who's that? Flathub and Fedora, the latter of who automate the Flatpak builds from distro packages anyway.

If you're using a smaller distro which is not backed by a huge security team then this is probably an advantage of using Flatpak, not a negative.

Can the Fedora Flatpaks be browsed and downloaded for other distros?

Yes. All Flatpak apps can be used on any distro.

I'm using the Fedora Flatpak Firefox on Debian, because Fedora's Flatpak runtime supports Kerberos authentication, the Flathub runtime doesn't.

All Flatpaks are portable. There is no reason to use their repo usually though as Flathub often has more up to date, featureful, or upstream maintained versions instead.

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Yes, I’m using flatpaks.

Yes, I’m trusting flathub. LOL about people repackaging applications. Wait until they find out the Linux distro they use is a collection of software repackaged by 3rd parties. 😂

Userland hasn’t had any concept of security, so it’s nice people are trying to fix it.

I have a handful of applications from Flathub I trust, but that's it.

I don't see Flatpak as a security mechanism and I don't treat it like one.

This is generally good advice. Would you run the program without a sandbox? No? Then you probably shouldn't run it inside a sandbox either.
You can never be sure that the program isn't using a flaw in the sandbox to break out or is just piggybacking onto a whitelisted action that is required for the program's basic functionality.

And if some program requires r/w for your entire home directory and network access then you might as well not use a sandbox in the first place because it can already do everything useful that it needs to do.

There is a subset of only verified apps, if you want to be secure. But then you lack trustworthy unofficial apps like VLC.

flatpak remote-delete flathub ; flatpak remote-add --subset=verified flathub https://dl.flathub.org/repo/flathub.flatpakrepo

Also until every app uses Portals, and until we have a share portal, most apps are basically unrestricted if you compare it to Android.

Are you using Flatpaks?

Yes, makes Debian desktop perfect. Rock solid base system, all desktop apps updated to the latest and greatest without pollution.

Are you trusting Flathub?

Yes BUT... there should be a way to have / manage / install Flatpaks offline like AppImages and/or easy and officially supported ways of archiving the repository into something useful and easy to use.

Related: https://github.com/flatpak/flatpak/issues/4874

Do you bother about the sandboxing and security?

Too much security already: https://github.com/flathub/org.keepassxc.KeePassXC/issues/29#issuecomment-559476300 A password manger can't community with a Browser as it is. This makes both useless and kills one of the best use cases for Flatpak.

I would love to install a browser, and a password manager through flatpaks but they won’t talk with each other.

I would get an IDE like visual studio code, through flathub, but it doesn’t talk with the system software I want to develop on.

I would love to get Steam or any other games as flatpaks but having to redownload mesa and other system files just for that uses a lot of space and feels like a second OS.

So yeah, I agree with you. It’s awesome! But it has some flaws right now (that I’m sure they’re being worked on)

Yes but they solve the cross distro packing problem and that's neat. The GNOME Software integration is also amazing, those few times when you see that desktop Linux actually can do it. :P

I just hope for better and easier tools to mange the security / process communication. For me flatpaks are more about finally having a fast and decent way of packing stuff across distros with dependencies than a sandbox / security feature.

I’m not against them, at all. I use them extensively. I just wish I could use them for everything!

FWIW I figured out how to get a password manager (Browserpass, not KeePassXC) to communicate with flatpak Chrome if you want some advice on how to get it to work.

But yes, it was way more difficult than it should have been (which is "should work out of the box, just like a regular package"). So if you're just listing some of the shortcomings of flatpak, never mind.

Point away!

OK, so I looked though my browser history, and here are some relevant pages I found:

I don't remember how much I used each one, but eventually I pieced together enough information information to get the Browserpass extension working in the Google Chrome flatpak. But three of those links are KeePassXC, which should be useful for adapting this for your use.

The main file that was having problems was the Browserpass Native Messaging Hosts file in my config directory for the Chrome flatpak, ~/.var/app/com.google.Chrome/config/google-chrome/NativeMessagingHosts/com.github.browserpass.native.json. Originally it was a symlink to a file at /usr/lib/browserpass/hosts/chromium/com.github.browserpass.native.json:

{
    "name": "com.github.browserpass.native",
    "description": "Browserpass native component for the Chromium extension",
    "path": "/usr/bin/browserpass-linux64",
    "type": "stdio",
    "allowed_origins": [
        "chrome-extension://naepdomgkenhinolocfifgehidddafch/"
    ]
}

The call to /usr/bin/browserpass-linux64 did not see to work for me, so I ended up making a copy of the file in the NativeMessagingHosts directory and modified it to point to a script in my home mount:

wile_e8 NativeMessagingHosts $ diff com.github.browserpass.native.json.orig com.github.browserpass.native.json
4c4
<     "path": "/usr/bin/browserpass-linux64",
---
>     "path": "/home/wile_e8/.config/browserpass/browserpass.sh",

I don't remember why I picked to do it inside the ~/.config directory, but it worked so I left it. And here is the script I put at ~/.config/browerpass/browserpass.sh:

#!/bin/sh
cd ~
/usr/bin/flatpak-spawn --host /usr/bin/browserpass-linux64 2>/tmp/error.log

I don't remember how I came up with that script, it must be somewhere in the four links at the top.

Finally, I needed to use Flatseal to allow access to the script. In the Google Chrome settings, under "Filesystem->Other files", I added an entry saying ~/.config/browserpass:ro. Also modified from the default in Flatseal, I have "Filesystem->All user files" enabled, along with "Socket->D-Bus session bus" and "Socket->D-Bus system bus". I don't know how necessary the last three are, but I'm not messing with it now that I have it working.

So, that's what I did to get the Browserpass extension working in the Google Chrome flatpak. You'll have to modify some things to get it working for KeePassXC, or for Firefox. But that general pattern should work.

Hmm I kind of tried that route before but haven't gone so far. I'll check it asap. Thanks!

Keep an eye out, I'll come back to this. It involves posting config file diffs and a script I wrote, it'll be a longer post I don't have the time to write right at this moment.

But yes, the fact that I need to find the time to post all the changes I needed to make to get this to work is part of the problem here.

flatpak create-usb backs up an app and all dependencies for offline use.

Yes, that works really well and whatnot. Totally reliable way of doing it. :P

Because the flatpak components/dependencies of a program can differ depending on the host (for example if you have an NVIDIA card, it will pull some NVIDIA dependencies), so if you export a program from a non-NVIDIA system to the other, it won't be complete to work reliably on the new system, but the missing parts can be downloaded on the Internet, it's still reducing the bandwidth requirement.

For anyone interested: https://docs.flatpak.org/en/latest/usb-drives.html and https://dataswamp.org/~solene/2023-01-01-flatpak-export-import.html

Ah Nvidia, very true. I’m not sure a solution can exist for that. Nvidia needs the driver to match the kernel.

Linux security to me has always been, don't download random packages you don't trust.

Even if you have trust. There can be security vulnerabilites in apps we are using. Flatpak seems to not really help in any way.

And this is why I've never taken much of Linuxs user base seriously when they talk about security. Hilariously bad defense strategy.

I'm mostly using Flatpaks on Tumbleweed, I only use the package manager if I can't find a Flatpak version. Reason for that is that with Flatpak I can precisely know what I manually installed, as Tumbleweed lacks a proper easy way of getting a list of user installed packages

Nope, I'll never use flatpak, appImage, snap, things like this.

If there's no .deb to install, I try to compile it myself.