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Flatpak – a security nightmare – 2 years later (2020)

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221–230 of 296 posts

Re: Flatpak – a security nightmare – 2 years later (2020)

#221
All the things like flatpak annoy me because I have a gut feeling that capsicum is the most incremental change to unix that is both secure and ergonomic, and all these other things sacrifice one or both of those with tons of complexity.

Just abandon the epicycles already!

Re: Flatpak – a security nightmare – 2 years later (2020)

#223
post #24

One thing I've not understood about flatpak (or their competition for that matter) is why don't these permissions get prompted when they're used? Similar to iOS and Android, ping the user and confirm whether or not they want to give the application this permission. Perhaps even allow for customising the permissions (e.g. when it asks for permission to the homedir, you can override what the homedir would be when promp…

I think its more of a one step at a time thing. There is nothing about the design of flatpak which prevents permission popups. The problem is that every desktop program must be rewritten to support this idea and most linux desktop app devs are only vaguely aware of flatpak, let alone ready to start designing specifically for it. The current strategy seems to be having outsiders packaging all the desktop software in t…

> The problem is that every desktop program must be rewritten to support this idea

No, and expecting that to work is obviously ridiculous. This type of problem needs to be solved in a way which requires no changes at all from developers, or it will almost certainly go nowhere.

Re: Flatpak – a security nightmare – 2 years later (2020)

#224
post #36

Earlier quoted context omitted.

This is probably quite hard to implement without modifying the packaged applications. Needs something like a mechanism of pausing, instead of denying, a system call in the kernel and calling back to userspace, which would then load new policy into the ruleset on the fly and resume execution. Oh and reverse engineer the high level intent of the user / application far enough to present an intelligible question to the p…

Doesn't this imply that Linux is falling behind somewhat in the area of permissions management? Personally, i think that limiting access to files and such based on users and groups simply isn't enough and instead the user should be prompted (or should be able to configure) which piece of software is allowed to do what (network access, file system access, talking to specific devices) based on their own individual need…

> Doesn't this imply that Linux is falling behind somewhat in the area of permissions management?

This happened years ago. Linux is way behind.

Re: Flatpak – a security nightmare – 2 years later (2020)

#225

Earlier quoted context omitted.

The technological ludditism is exhausting. We know some things are *objectively* better than the status quo. With attack surface as big as a modern browser or media player, not having sandboxing would be a mistake. Just the people who are stuck to 1970's way of doing things and fear new things oppose sandboxing.

So you think that disallowing access to word processor files to zip and unzip, or backup utilities, or ... is a perfectly reasonable way of doing things? Because that's what we do on the web. Every app only has access to it's own files and 10 or so standard clipboard formats (and ONLY through the clipboard).

Having a portal that dictates file access would be a perfectly reasonable way of doing things, and that's the direction that Flatpak security is at least starting to move in.

There are security models that allow sharing files that don't give direct access to the entire filesystem. A word processor might need access to my Documents folder, but I might choose not to give it access to anything outside of that folder. Or I might choose to tell it it's been given access to a Documents folder, but really it has access to a VFS mount that is a composite of several folders inside of Documents including some shared folders outside of Documents.

This kind of "portal" idea is incidentally also what browser manufacturers are considering as they start to explore offering native file access[0] (although this is obviously an area that in browsers needs to be approached with a lot of caution). I don't think Google's proposal is the best way to handle this, I think it could be better. But it's still better than what's happening on desktops with native apps.

[0]: https://web.dev/file-system-access/

Re: Flatpak – a security nightmare – 2 years later (2020)

#226
post #28

Earlier quoted context omitted.

It's almost as if the people riding the "sandbox everything" wave have realized that an operating system is more than a set of disconnected pieces of software. And that to make it an operating system, those pieces must interact, and not be isolated from each other. Go figure. Soon they'll reinvent the classical Linux distro. Poorly. But with a cool name.

The technological ludditism is exhausting. We know some things are *objectively* better than the status quo. With attack surface as big as a modern browser or media player, not having sandboxing would be a mistake. Just the people who are stuck to 1970's way of doing things and fear new things oppose sandboxing.

I dislike sandboxes that

- have complicated permissions that users misunderstand or can be tricked into misconfiguring through inattention, misleading user interface or fatigue

- aren't actually sandboxes because the isolation they claim isn't actually achieved (I usually call these "security holes")

- are used to artificially force markets (e.g., Microsoft's UWP)

Other than that, they're great.

Signed, cranky, pre-morning-coffee programmer speaking ex cathedra from the 1970s

Re: Flatpak – a security nightmare – 2 years later (2020)

#227
post #24

One thing I've not understood about flatpak (or their competition for that matter) is why don't these permissions get prompted when they're used? Similar to iOS and Android, ping the user and confirm whether or not they want to give the application this permission. Perhaps even allow for customising the permissions (e.g. when it asks for permission to the homedir, you can override what the homedir would be when promp…

As a desktop app developer this is what I need.

I publish a snap variation and so many edge cases break the security system and make the app unusable.

Home perms? What if the user symlinks something into their home directory? Etc

Re: Flatpak – a security nightmare – 2 years later (2020)

#228
How does snap compare to this: let’s say the Chromium snap? It’s advertised as sandboxed but obviously can download files to your Download directory, it can print PDFs etc, access Webcam of course for video conferences. How is sandboxing supposed to work here?

Re: Flatpak – a security nightmare – 2 years later (2020)

#229
post #16
post #7

Response from a Flatpak package maintainer - https://theevilskeleton.frama.io/2021/02/11/response-to-flat... I'll leave others to make their own minds up, but I personally think the original article is FUD in a similar vein to some of the SystemD and Wayland nonsense that gets upvoted occasionally.

I don't agree with your assessment at all. The linked article seems to mostly agree with the criticism levied, but disagrees mainly with the severity and degree of the issues. For example, OP says: > Almost all popular applications on flathub come with filesystem=host, filesystem=home or device=all permissions The response says that no, not "almost all"; out of the 50 surveyed apps, 23 of them had excessive permissio…

> and some things aren't even possible to do on X11

I think they are, simply based on the fact that we can run untrusted stuff inside VirtualBox (and with quite good performance).

Re: Flatpak – a security nightmare – 2 years later (2020)

#230
post #181

Earlier quoted context omitted.

The problem with existing OSes is that they do not offer any restrictions on how the pieces can interact. There’s no well defined API or principles.

Not saying it's perfect, but sure there is! https://en.wikipedia.org/wiki/POSIX for example.

Definitely not perfect, but I wish people would lean on good old fashion unix more for these things instead of implementing it worse on top of it.

I skimmed the article and it looks like one thing they do is have a daemon in the background to intercept data in and out, when they could just make user groups and normal file permissions.

I know it's almost a meme at this point, but plan9 had a great system for this.

You were able to define a filesystem layered on top of your own, exposing and linking files/folders however you please to any process.

So say you have a web server. You can make a layer that only has /www and /configs, linked to some folder in /var/foo/webstuff, and /etc/fooserver/configs or something.

No reason why you couldn't standardize an interface for systems like flatpak to safely use your filesystem.

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