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Killswitch: Per-function short-circuit mitigation primitive
- PeterWhittaker 6mo agoClever! I know some will say it's like closing the barn door after the horse left, but having this in place to mitigate future vulnerabilities will be handy.
- cyanydeez 6mo agook, but what kind of nefarious use case will it enable if it is accessible to malfeasance.
- ObscureScience 6mo agoI guess it could disable the killswitch
- cyanydeez 6mo agobesides that.
- PeterWhittaker 6mo agoI may be wrong, but on a correctly-configured system, one would have to have root access to act nefariously. Since this is intended to prevent exploitation of vulnerabilities that enable privilege escalation, it feels like a net win.
- frumiousirc 6mo agoIf I'm a malicious actor that gets root, can I killswitch the killswitch?
- htmlenjoyye 6mo agoyou're on the other side of the secure door already killswitch is to prevent you from gaining root
- cowthulhu 6mo agoOnce you’ve got root, you don’t need to exploit compromised code to do whatever you want.
- LoganDark 6mo agoLSMs say otherwise
- worthless-trash 6mo agoring0 loadable kernel modules disagree.
- LoganDark 6mo agoOnly to the extent there is not a deeply embedded core, of course. Or SMM
- worthless-trash 6mo agoNeither of those are LSM though right ?
- tandr 6mo agoOr malloc(), or open()... They kind of discussing it in the thread on how to prevent this from a malicious actor (or from footgunning yourself), but my understanding it is not all that plain and simple...
- tosti 6mo agoBetter tooling for kpatch would be nice tho IIRC canonical makes patches for official ubuntu kernels but acts like a Chinese restaurant (closed kitchen, orders come in through a small hatch behind the counter)
- logdahl 6mo agoSuper cool. Also, love reading high quality linux patches. I think many, myself previously included, are afraid to even read the kernel source as one thinks it must be super complex. Of course some parts really are. However, the code is honestly of such high quality. I also highly value that feeling of realizing something once thought 'arcane' was actually only made by other humans, and it is legal to go read it and learn from it.
- luka598 6mo ago>Assisted-by: Claude:claude-opus-4-7
- Brian_K_White 6mo agoAs an ai critic myself, so what?
- SwellJoe 6mo agoThe author has an @kernel.org address, and has been a regular Linux contributor for over a decade. I'll give him the benefit of the doubt. It's easy to write high quality AI-assisted code (harder than writing vibe-coded slop, but still easier than writing every line of code yourself). Edit: This also reminds me that I've begun to judge projects by whether the developer has public code from before AI. I'm more likely to trust their new code. Which causes me concern about the pipeline for new developers...how am I supposed to know a new user on Github has enough understanding of how software works to be shipping software? It used to be that if a new project by a new dev had good docs, some kind of test coverage, and a coherent git history, I could infer some level of quality. Not true, now, so I probably move on and look for something from someone with a pre-AI track record.
- Phelinofist 6mo agoCould something like this also be done via BPF?
- ARob109 6mo agoThat’s how this[0] project mitigates e.g. CopyFail. BPF LSM if you want to return -EPERM. Or a kprobe that kills the process via bpf_send_signal() if BPF LSM isn’t enabled. [0] https://github.com/cozystack/copy-fail-blocker#how-it-works https://github.com/cozystack/copy-fail-blocker#how-it-works
- ainto 6mo agoWhat about inlined functions?
- Rygian 6mo agoAs addressed in the article ("Choosing the right target"): > Pick the *highest-level* entry point that contains the bug
- xuhu 6mo agoIs there any library that does this safely for user-mode and is currently used in production ?
- DoctorOetker 6mo agothis sounds simple, but not running a function doesn't on its own mean safe behavior, if the caller code wasn't written keeping in mind this novel potential refusal as an outcome still i believe this is the right direction