Project Description

Nanos is a "unikernel" providing a subset of Linux kernel features. It only allows a single process to run, but has multiple threads. It maintains the kernel-land to user-land boundary unlike other unikernels (so perhaps isn't strictly a unikernel).

I want to use it to run apps in VMs. It's very good for this because it behaves like a container from scratch, only pulling in the files it needs. The kernel itself is very small and lightweight. It's possible to produce very small VMs that boot very quickly. More so perhaps than Linux containers running in firecracker microvms.

Goal for this Hackweek

  • Implement clone3 to support newer glibc's. (PR already])
  • (extra) Fix brk syscall (PR)

Resources

Looking for hackers with the skills:

kernel

This project is part of:

Hack Week 21

Activity

  • over 2 years ago: rpalethorpe added keyword "kernel" to this project.
  • over 2 years ago: rpalethorpe originated this project.

  • Comments

    Be the first to comment!

    Similar Projects

    Model checking the BPF verifier by shunghsiyu

    Project Description

    BPF verifier plays a crucial role in securing the system (though less so now that unprivileged BPF is disabled by default in both upstream and SLES), and bugs in the verifier has lead to privilege escalation vulnerabilities in the past (e.g. CVE-2021-3490).

    One way to check whether the verifer has bugs to use model checking (a formal verification technique), in other words, build a abstract model of how the verifier operates, and then see if certain condition can occur (e.g. incorrect calculation during value tracking of registers) by giving both the model and condition to a solver.

    For the solver I will be using the Z3 SMT solver to do the checking since it provide a Python binding that's relatively easy to use.

    Goal for this Hackweek

    Learn how to use the Z3 Python binding (i.e. Z3Py) to build a model of (part of) the BPF verifier, probably the part that's related to value tracking using tristate numbers (aka tnum), and then check that the algorithm work as intended.

    Resources


    Officially Become a Kernel Hacker! by m.crivellari

    Description

    My studies as well my spare time are dedicated to the Linux Kernel. Currently I'm focusing on interrupts on x86_64, but my interests are not restricted to one specific topic, for now.

    I also "played" a little bit with kernel modules (ie lantern, a toy packet analyzer) and I've added a new syscall in order read from a task A, the memory of a task B.

    Maybe this will be a good chance to...

    Goals

    • create my first kernel patch

    Resources

    Achivements


    RISC-V emulator in GLSL capable of running Linux by favogt

    Description

    There are already numerous ways to run Linux and some programs through emulation in a web browser (e.g. x86 and riscv64 on https://bellard.org/jslinux/), but none use WebGL/WebGPU to run the emulation on the GPU.

    I already made a PoC of an AArch64 (64-bit Arm) emulator in OpenCL which is unfortunately hindered by a multitude of OpenCL compiler bugs on all platforms (Intel with beignet or the new compute runtime and AMD with Mesa Clover and rusticl). With more widespread and thus less broken GLSL vs. OpenCL and the less complex implementation requirements for RV32 (especially 32bit integers instead of 64bit), that should not be a major problem anymore.

    Goals

    Write an RISC-V system emulator in GLSL that is capable of booting Linux and run some userspace programs interactively. Ideally it is small enough to work on online test platforms like Shaderoo with a custom texture that contains bootstrap code, kernel and initrd.

    Minimum:

    riscv32 without FPU (RV32 IMA) and MMU (µClinux), running Linux in M-mode and userspace in U-mode.

    Stretch goals:

    FPU support, S-Mode support with MMU, SMP. Custom web frontend with more possibilities for I/O (disk image, network?).

    Resources

    RISC-V ISA Specifications
    Shaderoo
    OpenGL 4.5 Quick Reference Card

    Result as of Hackweek 2024

    WebGL turned out to be insufficient, it only supports OpenGL ES 3.0 but imageLoad/imageStore needs ES 3.1. So we switched directions and had to write a native C++ host for the shaders.

    As of Hackweek Friday, the kernel attempts to boot and outputs messages, but panics due to missing memory regions.

    Since then, some bugs were fixed and enough hardware emulation implemented, so that now Linux boots with framebuffer support and it's possible to log in and run programs!

    The repo with a demo video is available at https://github.com/Vogtinator/risky-v


    Modularization and Modernization of cifs.ko for Enhanced SMB Protocol Support by hcarvalho

    Creator:
    Enzo Matsumiya ematsumiya@suse.de @ SUSE Samba team
    Members:
    Henrique Carvalho henrique.carvalho@suse.com @ SUSE Samba team

    Description

    Split cifs.ko in 2 separate modules; one for SMB 1.0 and 2.0.x, and another for SMB 2.1, 3.0, and 3.1.1.

    Goals

    Primary

    Start phasing out/deprecation of older SMB versions

    Secondary

    • Clean up of the code (with focus on the newer versions)
    • Update cifs-utils
    • Update documentation
    • Improve backport workflow (see below)

    Technical details

    Ideas for the implementation.

    • fs/smb/client/{old,new}.c to generate the respective modules
      • Maybe don't create separate folders? (re-evaluate as things progresses!)
    • Remove server->{ops,vals} if possible
    • Clean up fs_context.* -- merge duplicate options into one, handle them in userspace utils
    • Reduce code in smb2pdu.c -- tons of functions with very similar init/setup -> send/recv -> handle/free flow
    • Restructure multichannel
      • Treat initial connection as "channel 0" regardless of multichannel enabled/negotiated status, proceed with extra channels accordingly
      • Extra channel just point to "channel 0" as the primary server, no need to allocate an extra TCPServerInfo for each one
    • Authentication mechanisms
      • Modernize algorithms (references: himmelblau, IAKERB/Local KDC, SCRAM, oauth2 (Azure), etc.


    early stage kdump support by mbrugger

    Project Description

    When we experience a early boot crash, we are not able to analyze the kernel dump, as user-space wasn't able to load the crash system. The idea is to make the crash system compiled into the host kernel (think of initramfs) so that we can create a kernel dump really early in the boot process.

    Goal for the Hackweeks

    1. Investigate if this is possible and the implications it would have (done in HW21)
    2. Hack up a PoC (done in HW22 and HW23)
    3. Prepare RFC series (giving it's only one week, we are entering wishful thinking territory here).

    update HW23

    • I was able to include the crash kernel into the kernel Image.
    • I'll need to find a way to load that from init/main.c:start_kernel() probably after kcsan_init()
    • I workaround for a smoke test was to hack kexec_file_load() systemcall which has two problems:
      1. My initramfs in the porduction kernel does not have a new enough kexec version, that's not a blocker but where the week ended
      2. As the crash kernel is part of init.data it will be already stale once I can call kexec_file_load() from user-space.

    The solution is probably to rewrite the POC so that the invocation can be done from init.text (that's my theory) but I'm not sure if I can reuse the kexec infrastructure in the kernel from there, which I rely on heavily.

    update HW24

    • Day1
      • rebased on v6.12 with no problems others then me breaking the config
      • setting up a new compilation and qemu/virtme env
      • getting desperate as nothing works that used to work
    • Day 2
      • getting to call the invocation of loading the early kernel from __init after kcsan_init()
    • Day 3

      • fix problem of memdup not being able to alloc so much memory... use 64K page sizes for now
      • code refactoring
      • I'm now able to load the crash kernel
      • When using virtme I can boot into the crash kernel, also it doesn't boot completely (major milestone!), crash in elfcorehdr_read_notes()
    • Day 4

      • crash systems crashes (no pun intended) in copy_old_mempage() link; will need to understand elfcorehdr...
      • call path vmcore_init() -> parse_crash_elf_headers() -> elfcorehdr_read() -> read_from_oldmem() -> copy_oldmem_page() -> copy_to_iter()
    • Day 5

      • hacking arch/arm64/kernel/crash_dump.c:copy_old_mempage() to see if crash system really starts. It does.
      • fun fact: retested with more reserved memory and with UEFI FW, host kernel crashes in init but directly starts the crash kernel, so it works (somehow) \o/
    • TODOs

      • fix elfcorehdr so that we actually can make use of all this...
      • test where in the boot __init() chain we can/should call kexec_early_dump()