linux

615 Articles

A Potential Exploit With The Ext Filesystem

December 10, 2024 by 58 Comments

The extended filesystem, otherwise known as ext, has been a fundamental part of Linux since before the 1.0 release in 1994. Currently the filesystem is on its fourth major revision, in use since its release in 2008 thanks to its stability, reliability, and backwards compatibility with the other ext filesystem versions. But with that much history there are bound to be a few issues cropping up here and there. [Will] recently found an exploit with this filesystem that can cause a Linux kernel to immediately panic when a manipulated USB drive is inserted into a computer.

[Will] discovered this quirk when investigating the intricacies of the filesystem for problems and other vulnerabilities. A tool called tune2fs, used for administering and modifying ext filesystems, includes the ability to pass certain commands to the Linux kernel when certain situations arise with the filesystem itself, including that the kernel should panic. One situation is that the ext filesystem itself becomes corrupted, which can then cause the kernel panic. Armed with this knowledge, a USB drive can be purposefully given a corrupted ext filesystem which, when plugged into a Linux machine, can cause the computer to shut down.

The post linked above goes into some discussion about how this exploit could be used maliciously to gain access to a Linux system, including rebooting computers where no access to a power button is otherwise enabled or making other changes to the system before needing a reboot to apply the changes. In general, though, it’s good to assume an attacker could take any route to gain access to a machine. This exploit from a few years ago, for example, allowed another Linux tool to be used to gain root access.

Thanks to [Timothy] for the tip!

Smartphone Runs Home Server

December 9, 2024 by 22 Comments

It’s one of the great tragedies of our technological era. Smartphones that feature an incredible amount of computational power compared to computers the past, are largely locked down by carriers or manufacturers, dooming them to performing trivial tasks far below their true capabilities.

But there is hope. In part one of this build, a OnePlus 6T is stripped of its Android operating system in favor of postmarketOS, a Linux distribution based on Alpine designed for a number of Android phones and tablets as well as some Linux-only handhelds. The guide also demonstrates how to remove the battery and use a modified USB-C cable to essentially trick the battery management system into powering up the phone anyway. The second part of the project dives into the software side, getting the Linux system up and running before installing Docker and whichever Docker containers the user needs.

There are a few downsides to running a server from a smartphone. Although there’s plenty of processing power available for a wide range of applications, most phones won’t have Ethernet support out-of-the-box which forces the use of WiFi. There’s also limited storage options available, so a large NAS system may be out of reach. But for something like a home automation system or a music streaming server this could put plenty of older devices to work again. And if you don’t want to hunt for an Android phone that isn’t completely hobbled out-of-the box you might want to try a phone that’s Linux-based from the get-go instead.

Thanks to [JohnU] for the tip!

FLOSS Weekly Episode 811: Elixir & Nerves – Real Embedded Linux

November 27, 2024 by 1 Comment

This week, Jonathan Bennett and Lars Wikman chat about Elixir and Nerves — a modern language that’s a take on Erlang, and an embedded Linux approach for running Elixir code on devices.

Subscribe to catch the show live, and come to Hackaday for the rest of the story!

Continue reading “FLOSS Weekly Episode 811: Elixir & Nerves – Real Embedded Linux” →

Linux Fu: Audio Network Pipes

November 26, 2024 by 18 Comments

Life was simpler when everything your computer did was text-based. It is easy enough to shove data into one end of a pipe and take it out of the other. Sure, if the pipe extends across the network, you might have to call it a socket and take some special care. But how do you pipe all the data we care about these days? In particular, I found I wanted to transport audio from the output of one program to the input of another. Like most things in Linux, there are many ways you can get this done and — like most things in Linux — only some of those ways will work depending on your setup.

Why?

There are many reasons you might want to take an audio output and process it through a program that expects audio input. In my case, it was ham radio software. I’ve been working on making it possible to operate my station remotely. If all you want to do is talk, it is easy to find software that will connect you over the network.

However, if you want to do digital modes like PSK31, RTTY, or FT8, you may have a problem. The software to handle those modes all expect audio from a soundcard. They also want to send audio to a soundcard. But, in this case, the data is coming from a program.

Of course, one answer is to remote desktop into the computer directly connected to the radio. However, most remote desktop solutions aren’t made for high-fidelity and low-latency audio. Plus, it is nice to have apps running directly on your computer.

I’ll talk about how I’ve remoted my station in a future post, but for right now, just assume we want to get a program’s audio output into another program’s audio input. Continue reading “Linux Fu: Audio Network Pipes” →

I Installed Gentoo So You Don’t Havtoo

November 4, 2024 by 73 Comments

A popular expression in the Linux forums nowadays is noting that someone “uses Arch btw”, signifying that they have the technical chops to install and use Arch Linux, a distribution designed to be cutting edge but that also has a reputation of being for advanced users only. Whether this meme was originally posted seriously or was started as a joke at the expense of some of the more socially unaware Linux users is up for debate. Either way, while it is true that Arch can be harder to install and configure than something like Debian or Fedora, thanks to excellent documentation and modern (but optional) install tools it’s no longer that much harder to run than either of these popular distributions.

For my money, the true mark of a Linux power user is the ability to install and configure Gentoo Linux and use it as a daily driver or as a way to breathe life into aging hardware. Gentoo requires much more configuration than any mainline distribution outside of things like Linux From Scratch, and has been my own technical white whale for nearly two decades now. I was finally able to harpoon this beast recently and hope that my story inspires some to try Gentoo while, at the same time, saving others the hassle.

A Long Process, in More Ways Than One

My first experience with Gentoo was in college at Clemson University in the late ’00s. The computing department there offered an official dual-boot image for any university-supported laptop at the time thanks to major effort from the Clemson Linux User Group, although the image contained the much-more-user-friendly Ubuntu alongside Windows. CLUG was largely responsible for helping me realize that I had options outside of Windows, and eventually I moved completely away from it and began using my own Linux-only installation. Being involved in a Linux community for the first time had me excited to learn about Linux beyond the confines of Ubuntu, though, and I quickly became the type of person featured in this relevant XKCD. So I fired up an old Pentium 4 Dell desktop that I had and attempted my first Gentoo installation.

For the uninitiated, the main thing that separates Gentoo from most other distributions is that it is source-based, meaning that users generally must compile the source code for all the software they want to use on their own machines rather than installing pre-compiled binaries from a repository. So, for a Gentoo installation, everything from the bootloader to the kernel to the desktop to the browser needs to be compiled when it is installed. This can take an extraordinary amount of time especially for underpowered machines, although its ability to customize compile options means that the ability to optimize software for specific computers will allow users to claim that time back when the software is actually used. At least, that’s the theory. Continue reading “I Installed Gentoo So You Don’t Havtoo” →

A screen capture from Portal 2 running in Asahi Linux. The Asahi Linux logo is in the bottom right of the image as a watermark. The environment is a concrete and glass building with elements of nature taking over the room on the other side of the glass from the character. A red circle with a grey cube above it is in the foreground.

Asahi Linux Brings Better Gaming To Apple Silicon

October 29, 2024 by 8 Comments

For those of you longing for better gaming on an Apple Silicon device, Asahi Linux is here to help.

While Apple’s own line of CPUs are relatively new kids on the block, they’ve still been around for four years now, giving hackers ample time to dissect their innards. The team behind Asahi Linux has now brought us “the only conformant OpenGL®, OpenCL™, and Vulkan® drivers” for Apple’s M1 and M2.

The emulation overhead of the system means that most games will need at least 16 GB of RAM to run. Many games are playable, but newer titles can’t yet hit 60 frames per second. The developers are currently focused on “correctness” and hope to improve performance in future updates. Many indie titles are reported to already be working at full speed though.

You can hear more about some of the fiddly bits of how to “tessellate with arcane compute shaders” in the video below. Don’t worry, it’s only 40 minutes of the nine hour video and it should start right at the presentation by GPU dev [Alyssa Rosenzweig].

If you want to see some of how Linux on Apple Silicon started or some of the previous work on hacking the M1 GPU, we have you covered.

Continue reading “Asahi Linux Brings Better Gaming To Apple Silicon” →