Birbla

Join the discussion

Write your take first — we'll ask for email only when you're ready to publish.

Sign in
  • Hacker News
  • The embedded and military markets may keep funding them for the foreseeable future but they need a native seL4/Linux if they want to honestly claim they are improving systems' security with their capability model.

    Secure–boot virtualization platforms are dime a dozen nowadays.

    by avadodin
  • "native seL4/Linux"? seL4 can already host Linux VMs, and there are various methods of running Linux code / binaries without hardware virtualisation.
    by jdub
  • The current value is that you can take an existing specialist/military device that used distinct physical chips for provable isolation, and consolidate them all onto one chip (lowering cost/power/space), while still saying that you met the security requirements

    So its more of an economic argument than that of increasing security

    by boredatoms
  • > but they need a native seL4/Linux if they want to honestly claim they are improving systems' security with their capability model.

    Are you using "seL4/Linux" in the style of "GNU/Linux"? Because then it should be "GNU/seL4" - that would describe an OS exposing the GNU core utilities on top of the seL4 kernel. There's no way to mix the Linux kernel with the seL4 kernel, other than using one to run VMs of the other.

    by simiones
  • Read the fine print, "non-MCS (mixed criticality systems), unicore"
    by i_am_a_peasant
  • What operating systems use SeL4? I know of the following:

    - GenodeOS

    - LionsOS

    - A chinese car maker was using it as a hypervisor in their cars, IIRC

    - What else? Are there any private deployments you guys are aware of?

    by kvuj
  • The Secure Enclave on iOS devices runs sepOS, and earlier fork of the UNSW/NICTA L4 nano kernel work. Obviously Apple has huge resources to verify their own kernel on their own hardware, but seL4 is likely much more secure. With Apple's appetite for architectural security improvements I think they will eventually move to an seL4 derivative with special hardware security add-ons.

    There are a number of talks at the upcoming seL4 summit, but see 2025, e.g. Kry10 KOS.

    https://sel4.systems/Summit/2025/program.html

    by angry_octet
  • Coming soon: a side-channel timing attack which completely invalidates this result
    by StilesCrisis
  • There's another can of worms that are rowhammer-esque attacks.
    by IsTom
  • the proofs prove certain things they do not prove a system is infallable or actually secure they rule out certain things in certain parts of the code.
    by saidnooneever
  • Side channel timing attacks are micro architectural. The SeL4 security proofs are architectural.
    by CalChris
  • Are timing (over network) attacks, physical access, etc. typically excluded from research like this for being “out of scope”, so to speak? I’m not familiar.
    by msdz
  • Although, there is ongoing research regarding time protection (https://trustworthy.systems/projects/timeprotection/) which prevents exactly timing channels. Including proofs of seL4 providing time protection.
    by fosslinux
  • I don't think a side channel attack against L4 would be particularly useful - the kernel's tiny, and doesn't really do much other than scheduling, IPC and capabilities. Anything you might want to learn lives in other processes.

    That said, the big caveat of the whole thing, is that by pushing stuff traditionally considered to be sensitive to user space doesn't solve security or stability, it makes it other people's problem. There's no reason you couldn't do a side channel (or a different kind of) attack against a process that hosts the filesystem.

    by torginus
  • That's a bit unfair. Any side–channel attack that invalidates seL4 security guarantees —assuming the proofs are valid— also invalidates any other imaginable OS'.

    We're in the philosophical territory of tasking infallible beings with stopping their own flawless creations.

    by avadodin
  • The assumptions the proof makes are pretty clearly listed: https://sel4.systems/Verification/assumptions.html

    The one covering side channels is pretty honest:

    Information side-channels: this assumption applies to the confidentiality proof only and is not present for functional correctness or integrity. The assumption is that the binary-level model of the hardware captures all relevant information channels. We know this not to be the case. This is not a problem for the validity of the confidentiality proof, but means that its conclusion (that secrets do not leak) holds only for the channels visible in the model. This is a standard situation in information flow proofs: they can never be absolute. As mentioned above, in practice the proof covers all in-kernel storage channels but does not cover timing channels.

    So the proof won't be invalidated at it does not cover that particular threat.

    Now the question is how useful the is a proof not covering side channels? I'd say pretty useful and it doesn't mean they don't have counter measures for to counter their exploitation, nor that they are not effective, just that a proof of efficiency is out of reach for now.

    by brohee