Matthew Garrett

I have a Samsung Q800A soundbar. It ships with built-in support for the Apple Airplay protocol, but I’m not really an Apple kind of guy so that’s never been particularly helpful for me. So, instead, I have a Chromecast Audio plugged into it via TOSLINK, and that works fine - except for the fact that there’s no way to explicitly pick TOSLINK as the audio input. Instead, there’s a “Digital In” option that refers to both the optical in and eARC input from a TV. Not inherently a problem, given I’m…

Epic just announced the upcoming version 2 of their Linux implementation of Easy Anti-Cheat. It’s based on using the Linux eBPF security module to monitor what’s happening, and then a bunch of extra infrastructure to make sure this can’t be bypassed. The core part of this is requiring secure boot be enabled (ensuring that modified kernels can’t be used), using measured boot to verify that secure boot is enabled and which keys are used (to prevent you from just signing your own modified kernel),…

(This is an updated version of an older post - the introduction remains the same, the technical details are different) Linux draws a distinction between code running in kernel (kernel space) and applications running in userland (user space). This is enforced at the hardware level - in x86-speak1, kernel space code runs in ring 0 and user space code runs in ring 32. If you’re running in ring 3 and you attempt to touch memory that’s only accessible in ring 0, the hardware will raise a fault. No…

I’m looking at something entirely unrelated, but tripped over some search results that made me realise that a lot of people still think getting errors like ACPI Warning: SystemIO range 0x0000000000001828-0x000000000000182F conflicts with OpRegion 0x0000000000001800-0x000000000000187F indicate a firmware bug. This is generally untrue. We need to dive a little into what ACPI is to clarify why. The Advanced Configuration and Power Interface1 specification defines a whole bunch of stuff, but what’s…

I’m on a VPN setup with several friends that, obviously, includes a VoIP network. I also have an old magicJack adapter and a deep and abiding need to use hardware in ways I should not. There was obvious synergy here. Plugging in the magicJack gives a USB vendor id of 0x06e6, which belonged to a company called TigerJet who made a range of chips for hooking up phones to computers, either via USB or PCI. Some more digging suggested that it was a 580 part, and someone had conveniently uploaded some…

As is the case for many people working in the security industry, the last few months of my life have been focused on dealing with people wanting to use LLMs everywhere. From an enterprise security perspective that’s not an inherent problem - what’s more of a problem is that people want those agents to have access to resources like their calendar and email and so on, and now we have somewhat non-deterministic agents that seem very enthusiastic to achieve what you asked whether that’s a good idea…

When you log into a service you’re given an authentication token. Each further request to the site includes that token, allowing the server to figure out who you are and ensuring that you have access to your data. Depending on site policy, this token may either be stored in memory (and so vanish if you restart your browser) or disk. The token is the proof of your identity. As far as the site is concerned, anyone with your token is you. These tokens may be traditional browser cookies, but they…

Because I am bad at giving up on things, I’ve been running my own email server for over 20 years. Some of that time it’s been a PC at the end of a DSL line, some of that time it’s been a Mac Mini in a data centre, and some of that time it’s been a hosted VM. Last year I decided to bring it in house, and since then I’ve been gradually consolidating as much of the rest of my online presence as possible on it. I mentioned this on Mastodon and a couple of people asked for more details, so here we…