linux-hardened VS firecracker-containerd

Glossing over their hardening guide, we notice that the kernel-hardened package is mentioned. This is a fork of what once was the kernel of GrapheneOS. While this hardened kernel can be used on a variety of distros, unfortunately this doesn't apply to Fedora Silverblue. Furthermore, I haven't seen any mention of the hardened kernel being used on openSUSE Tumbleweed. Therefore I see no reason to believe that this is possible on openSUSE Aeon either. Though, I'd love to be corrected on this!

Here's the GitHub page for the linux-hardened package in the official Arch repos. You will find that lots of changes come from GrapheneOS. "Forked from GrapheneOS" is in tiny, tiny text near the top-left of the web page underneath the project name.

Here is the source code for the hardened Linux kernel.

so that we can use it liberally in CLI) > **Additionally, here's a 'building from the source section** - https://github.com/firecracker-microvm/firecracker/blob/main/docs/getting-started.md#building-from-source ### Running Firecracker > "*In production, Firecracker is designed to be run securely, inside an execution jail, carefully set up by the jailer binary. This is how our integration test suite does it. However, if you just want to see Firecracker booting up a guest Linux machine, you can do that as well.*" 1. We need to first obtain an "uncompressed Linux kernel binary, and an ext4 file system image (to use as rootfs)" ; great, these are two things that we need to seek out before we move forward in our 'adventure' (*this really feels like a "quest" of some sort, like the ones that they forced you to play on Runescape back in the days*) **How to Decompress Linux Kernel** (explicit instructions to be honest here) - https://0xax.gitbooks.io/linux-insides/content/Booting/linux-bootstrap-5.html **Linux-Hardened Kernel** - https://github.com/anthraxx/linux-hardened (this is something that they're all still actively working on at this very point in time) They also say that we need an 'ext4 file system image' (where do we obtain this from?) - found it **Full Guide on How to Create an EXT4 filesystem image here** -https://fabianlee.org/2020/01/13/linux-mounting-a-loopback-ext4-xfs-filesystem-to-isolate-or-enforce-storage-limits/ Assuming that the above has been handled, the directions insist that we create two separate shell prompts, (one to run Firecracker, and another one to control it [by writing to the API socket]; both shells have to run "in the same directory where the firecracker binary was placed") ^^ What? - This is a pain in the ass because this is something that they should've mentioned earlier (obv. everyone is going to move a binary where the rest of their binaries go ; and you're not going to just load up some random project to be used in that manner) - Not even sure what the end goal of opening up an API socket here would really be But fuck it, let's just assume that we play ball and we adhere to all of these (additional) steps that we're being put through (just for the setup up this virtualization tool!). ### Following Through on the Next Steps 1. Ensuring that Firecracker can create its own API ``` bash rm -f /tmp/firecracker.socket

Officially supported kernels Community support on forum and bug reporting is available for officially supported kernels. Stable — Vanilla Linux kernel and modules, with a few patches applied. https://www.kernel.org/ || linux Hardened — A security-focused Linux kernel applying a set of hardening patches to mitigate kernel and userspace exploits. It also enables more upstream kernel hardening features than linux. https://github.com/anthraxx/linux-hardened || linux-hardened Longterm — Long-term support (LTS) Linux kernel and modules. https://www.kernel.org/ || linux-lts Zen Kernel — Result of a collaborative effort of kernel hackers to provide the best Linux kernel possible for everyday systems. Some more details can be found on https://liquorix.net (which provides kernel binaries based on Zen for Debian). https://github.com/zen-kernel/zen-kernel || linux-zen

Overall those patches do protect you in a lot of cases. Per default upstream features are chose to honor security first. Furthermore patches do frequently protect against upstream failures and vulnerabilities. One of the latest examples is CVE-2022-1729 https://seclists.org/oss-sec/2022/q2/122 a local privilege vulnerability that linux-hardened simply protects since before day 0: https://github.com/anthraxx/linux-hardened/commit/4dd6bdf3b079ef73e597661ee961d225bfccbe2a On top the approach in several places of fail-early instead of potentially continuing with known corruption or certain use-after-free regularly uncovers problems that get fixed upstream and where the vanilla kernels just keep on running, which include exploitable problems. One example of a faulty very recent commit that has been bisected and fixed because of linux-hardened: https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/commit/?h=for-next&id=acde4003efc16480375543638484d8f13f2e99a3

Those two don't protect the kernel itself from "misuse". To do that, there are ways like kernel hardening 3, using hardened kernel 4 5.

My team is working on multi-cloud AWS Bottlerocket remix (Azure, GCP) with opt-in support for [firecracker-containerd](https://github.com/firecracker-microvm/firecracker-containerd) for our in-house CNCF distro, investigating microkernels applicability (tldr; they are not production-ready). We test kubernetes compat and migration plans for over 40+ cherry-picked solutions, and facing numerous compat issues for every k8s update. We do have support for Container Managed Control Planes described above, as well.

You could use a container sandbox like gVisor, light virtual machines as containers (Kata containers, firecracker + containerd) or full virtual machines (virtlet as a CRI).

There is this project, which I have never used, but seems promising. https://github.com/firecracker-microvm/firecracker-container...

, "should represent the path to a file that contains a JSON which stores the entire configuration for all of the microVM's resources" (okay this is fair enough). Also, they stipulate, "**The JSON must contain the configuration for the guest kernel and rootfs, as these are mandatory, but all of the other resources are optional, so it's your choice if you want to configure them or not. Because using this configuration method will also start the microVM, you need to specify all desired pre-boot configurable resources in that JSON.**" **File Names for the Pre-Boot Resources** (included within the greater repo here): 1. **firecracker.yaml** - Names of resources are contained here ; 'file nad the names of their fields are the same that are used in API requests' (cool) 2. **tests/framework/vm_config.json** (boilerplate config file to guide us - great) > *"After the machine is booted, you can still use the socket to send API requests for post-boot operations."* (this honestly feels clunky as a mf) ### Conclusion Somewhat of a pain in the ass (just looking through the directions); the fact that we'd have to go grab a uncompressed kernel image + file system image (ext4) is kind of a fucking hassle / burden. Was hoping for a solution more akin to Docker where it can just be spun up real quick & then deployed. But they claim that this 'jailer' feature (that they keep hyping) will **ensure** (I guess?) that whatever is done within the container will remain within the container (and not escape). I haven't seen anything that sticks out about this project that leads me to believe that it possesses that capability, but I definitely don't want to rule it out. ### Extra Documentation + Information 1. **OSv Running on 'Firecracker'** (yay more work though) - http://blog.osv.io/blog/2019/04/19/making-OSv-run-on-firecraker/ 2. **Building OSv Images Using Docker** - http://blog.osv.io/blog/2015/04/27/docker/ 3. **firecracker containerd** (this is something that's probably important for the overall mission of what we want to accomplish here) - https://github.com/firecracker-microvm/firecracker-containerd ### Firecracker Containerd **Description** - "*firecracker-containerd enables containerd to manage containers as Firecracker microVMs*" - "This repository enables the use of a container runtime, containerd, to manage Firecracker microVMs. Like traditional containers, Firecracker microVMs offer fast start-up and shut-down and minimal overhead. Unlike traditional containers, however, they can provide an additional layer of isolation via the KVM hypervisor." **They Also Identify Potential Use-Cases in the Repo Such as** 1. "*Sandbox a partially or fully untrusted third party container in its own microVM. This would reduce the likelihood of leaking secrets via the third party container, for example.*" 2. "*Bin-pack disparate container workloads on the same host, while maintaining a high level of isolation between containers. Because the overhead of Firecracker is low, the achievable container density per host should be comparable to running containers using kernel-based container runtimes, without the isolation compromise of such solutions. Multi-tenant hosts would particularly benefit from this use case.*" Really interesting feature of this repo here is: "*A root file filesystem image builder that constructs a firecracker microVM root filesystem containing runc and the firecracker-containerd agent.*" (that could save a lot of time on that whole filesystem image thing that they were mentioning prior) **Additional Links of Importance** 1. **Getting Started Guide** - https://github.com/firecracker-microvm/firecracker-containerd/blob/main/docs/getting-started.md 2. **Quickstart Guide** - https://github.com/firecracker-microvm/firecracker-containerd/blob/main/docs/quickstart.md 3. **A Root Filesystem Image Builder** - https://github.com/firecracker-microvm/firecracker-containerd/blob/main/tools/image-builder 4. **Runtime Linking Containerd** - https://github.com/firecracker-microvm/firecracker-containerd/blob/main/runtime **Documentation All Located Here** - https://github.com/firecracker-microvm/firecracker-containerd/tree/main/docs (definitely fucking needed because there's a lot here to wrap one's head around) - **Design Approaches Doc** - https://github.com/firecracker-microvm/firecracker-containerd/blob/main/docs/design-approaches.md - **Shim Architecture** - https://github.com/firecracker-microvm/firecracker-containerd/blob/main/docs/shim-design.md - **Launching 4k VMs Using Firecracker** - https://github.com/firecracker-microvm/firecracker-demo - **firectl** (CLI options for manipulating this tool from terminal ; this is important as well) - https://github.com/firecracker-microvm/firectl [damn, there's a lot that came with this here!]

Exactly, it is about secure multi-tennancy. If I recall correctly firecracker doesn't replace containerd, microVMs still runs some sort of it. Anyway, you still need a base OS because container doesn't have the whole OS image. Also I think you can have multiple containers in a single Fargate task so they have to be isolated too.

How does that compare to firecracker-containerd?

https://github.com/firecracker-microvm/firecracker-container...

This repository enables the use of a container runtime, containerd, to manage Firecracker microVMs. Like traditional containers, Firecracker microVMs offer fast start-up and shut-down and minimal overhead. Unlike traditional containers, however, they can provide an additional layer of isolation via the KVM hypervisor.

I'm really impressed by fly.io, and the candidness with which they share some of their really awesome technology. Being container-first is the next step for PaaS IMO and they are ahead of the pack.

I aim to build a platform like theirs someday (probably not any time soon) but I don't think I'd do any of what they're doing -- it feels unnecessary. Bear with me as I recently learned that they use nomad[0] and some of these suggestions are kubernetes projects but I'd love to hear why the following technologies were decided against (if they were):

- kata-containers[1] (it does the whole container -> VM flow for you, automatically, nemu, firecracker) with multiple VMM options[2]

- linuxkit[3] (let's say you didn't go with kata-containers, this is another container->VM path)

- firecracker-containerd[4] (very minimal keep-your-container-but-run-it-as-a-VM)

- kubevirt[5] (if you just want to actually run VMs, regardless of how you built them)

- Ceph[6] for storage -- make LVM pools and just give them to Ceph, you'll get blocks, distributed filesystems (CephFS), and object gateways (S3/Swift) out of it (in the k8s space Rook manages this)

As an aside to all this, there's also LXD, which supports running "system" (user namespace isolated) containers, VMs (somewhat recent[7][8]), live migration via criu[9], management/migration of underlying filesystems, runs on LVM or zfs[10], it's basically all-in-one, but does fall behind in terms of ecosystem since everyone else is aboard the "cloud native"/"works-with-kubernetes" train.

I've basically how I plan to run a service like fly.io if I ever did -- so maybe my secret is out, but I sure would like to know just how much of this fly.io got built on (if any of it), and/or what was turned down.

[0]: https://news.ycombinator.com/item?id=26745514

[1]: https://github.com/kata-containers/kata-containers

[2]: https://github.com/kata-containers/kata-containers/blob/2fc7...

[3]: https://github.com/linuxkit/linuxkit

[4]: https://github.com/firecracker-microvm/firecracker-container...

[5]: https://github.com/kubevirt/kubevirt

[6]: https://docs.ceph.com/

[7]: https://discuss.linuxcontainers.org/t/running-virtual-machin...

[8]: https://github.com/lxc/lxd/issues/6205

[9]: https://criu.org/Main_Page

[10]: https://linuxcontainers.org/lxd/docs/master/storage

https://github.com/firecracker-microvm/firecracker-container...