hannesm · HackerTrans

hannesm

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A simple scheduler for OCaml 5 (effects, multicore)

discuss.ocaml.org

2 pointsby hannesm3 ปีที่แล้ว1 comments

The Bitcoin Piñata – no candy for you – running since 3 years

hannes.nqsb.io

2 pointsby hannesm8 ปีที่แล้ว0 comments

ICFP programming contest 2015

icfpcontest.org

2 pointsby hannesm11 ปีที่แล้ว0 comments

Signing the OPAM Repository: TUF Meets Git

opam.ocaml.org

42 pointsby hannesm11 ปีที่แล้ว20 comments

OCaml-TLS: the protocol implementation and mitigations to known attacks

openmirage.org

59 pointsby hannesm12 ปีที่แล้ว2 comments

comments

3 ปีที่แล้วdiscuss

What you already can do is attaching gdb -- either live or at a core dump. Please see https://github.com/Solo5/solo5/blob/master/docs/debugging.md for detailed instructions ;)

What you as well can do is record-replay -- well, at least there used to be this option, I'm now lost whether it has never been merged anywhere, or it is stuck in some PR somewhere. This was truly great - since the external interface is so thin, it is easily doable to dump all external events (API calls and returns) onto disk and replay one-by-one, inspecting the state.

3 ปีที่แล้วdiscuss

To be a bit more precise, what we achieved so far: apart from web servers and TLS reverse proxies (with DNS-backed let's encrypt provisioning), DNS authoritative servers, a CalDAV server, git client and servers, SMTP stack (including dkim etc.), OpenVPN implementation, archive mirror (using tar as file system), monitoring with syslog and influx, ...

A big milestone was binary releases and deployment instructions, see https://robur.coop/Projects/Reproducible_builds

see more at https://blog.robur.coop https://hannes.robur.coop https://blog.osau.re/ https://reyn.ir/archive.html

If you're curious how/what to integrate MirageOS into your infrastructure, please reach out (best via email).

3 ปีที่แล้วdiscuss

good news is that MirageOS can as well be executed in a seccomp context with only 5 or 7 system calls allowed -- see the spt target of solo5 https://github.com/solo5/solo5 -- also this great talk by mato https://archive.fosdem.org/2019/schedule/event/solo5_unikern...

3 ปีที่แล้วdiscuss

Some MirageOS developers were hired/acquired by docker -- though not the (open source) project, beither the code... There's still quite some work on MirageOS itself, including reproducible binary builds, VPN, DNS services, orchestration solutions, ...

3 ปีที่แล้วdiscuss

Amazing how little code is needed for that, and how clear the interface is... documentation and tutorials at https://docs.osau.re/miou/

4 ปีที่แล้วdiscuss

srsly it's 2022 and they only have legacy IP and no IPv6?

4 ปีที่แล้วdiscuss

Yes, this is an ordinary Linux binary.

The attack surface is different, you may be interested in https://archive.fosdem.org/2019/schedule/event/solo5_unikern... and/or https://archive.fosdem.org/2019/schedule/event/solo5_unikern... :)

TL;DR: hardware virtualization is pushing trust into hardware -- but can you trust the hardware implementation (to isolate memory)?

4 ปีที่แล้วdiscuss

MirageOS is - similar to the latest OCaml release - only using a single CPU core. You can run multiple unikernels, one on each core. If doing that, you can use Xen vchan (shared memory), or TCP for marshalling.

> Also I would say there are reasons for isolation beyond memory safety.

Would you mind to elaborate which reasons you are thinking of?

4 ปีที่แล้วdiscuss

Maybe https://hannes.robur.coop/Posts/Monitoring sheds some light how to monitor MirageOS unikernels ;)

4 ปีที่แล้วdiscuss

We use asynchronous tasks in MirageOS (cooperative multitasking) using lwt http://ocsigen.org/lwt/latest/manual/manual, so you can serve multiple network connections at the same time.

Since there are no processes, there's no concept of "fork", but indeed you can run multiple tasks at the same time (using the same address space). Why again would you need multiple processes? Since the programming language OCaml has a semantics and is memory-safe, there's no strong reason for isolation at execution time (apart from the C bits, which we try to keep to a minimum and compile with runtime safety flags (red-zone for stack protection, mapping execute-only (seems to only reliably work on OpenBSD), etc.)).

4 ปีที่แล้วdiscuss

In ancient times, only Xen was supported. Nowadays, the support moved to:

  - Xen (PVH)
  - Linux KVM, FreeBSD BHyve, OpenBSD VMM
  - SPT (seccomp, no hardware virtualization)
  - virtio (GCE, ..)
  - muen (muen.sk)

Take a look at https://github.com/solo5/solo5 which is used as the low level bits to run OCaml.

5 ปีที่แล้วdiscuss

Highly recommend the history of English podcast, which goes deep into the topics https://historyofenglishpodcast.com/

10 ปีที่แล้วdiscuss

Processes? Seriously if there's only a single one, why would you waste resources on process management and process information? Just get over it ;) http://unikernel.org https://mirage.io :D

10 ปีที่แล้วdiscuss

Looks like we're on a different Interweb, works for me; and travis was a spurious reporting problem, compiles fine (and is now green just to make you happy) :)

10 ปีที่แล้วdiscuss

There's https://nqsb.io - now even with a libtls.so compat layer (you can LD_PRELOAD our libnqsb-tls https://github.com/mirleft/libnqsb-tls)

Being binary compatible with libssl.so is just insane (too many symbols), but obviously doable. Volunteers welcome

10 ปีที่แล้วdiscuss

Have you seen unikernel approaches like MirageOS (https://mirage.io), which challenge the POSIX basics of operating systems? If not, take a look :)

10 ปีที่แล้วdiscuss

This is similar to my experience verifying imperative code (as part of http://itu.dk/research/tomeso): rewrite code as pure as possible (learning that mutation is premature optimisation), then try to specify and prove it.

Aside, if we're reinventing the wheel anyways, why not in a proper style? There's no reason to not deploy purely functional code (+some effectful shims). Think https://mirage.io https://nqsb.io -- rust has way too much mutation and unsafe builtin already...

10 ปีที่แล้วdiscuss

hmm, my other OS is MirageOS (https://mirage.io) -- also see https://nqsb.io contains my previous two years of work ;)

I'd rather call it extensive exploration than fuzz testing what is in my mind...

10 ปีที่แล้วdiscuss

The specification, as written in the RFC, is pretty useless... But luckily people sat down and formalised TCP/IP as spoken on the Internet (10 years ago, Linux-2.4.20/FreeBSD-4.6/Windows XP): https://www.cl.cam.ac.uk/~pes20/Netsem/index.html

All the code is now BSD licensed https://github.com/PeterSewell/netsem

What is missing in 10 years of TCP? Apart from SACK and delayed ACK not much it seems (in FreeBSD congestion control algorithms are pluggable nowadays).

And I currently revive it (working hard on test suite using DTrace probes) https://www.cl.cam.ac.uk/~pes20/HuginnTCP/

Please ping me if you're interested (hannes at mehnert dot org) and eager to help.

10 ปีที่แล้วdiscuss

You have seen the network semantics research project https://www.cl.cam.ac.uk/~pes20/Netsem/index.html? It is a formal model of TCP/IP validated with Linnux 2.4.20/FreeBSD-4.6/Windows XP (yes, that was ~10 years ago).

It is nowadays BSD licensed on GitHub https://github.com/PeterSewell/netsem (and I'm currently reviving it https://www.cl.cam.ac.uk/~pes20/HuginnTCP/)...