Kernel Queue: The Complete Guide On The Most Essential Technology For High-Performance I/O
Kernel Queue: The Complete Guide On The Most Essential Technology For High-Performance I/O When talking about high-performance software we probably think of server software (such as nginx) which processes millions requests from thousands clients in parallel. Surely, what makes server software work so fast is high-end CPU running with huge amount of memory and a very fast network link. But even the
How a simple Linux kernel memory corruption bug can lead to complete system compromise
In this case, reallocating the object as one of those three types didn't seem to me like a nice way forward (although it should be possible to exploit this somehow with some effort, e.g. by using count.counter to corrupt the buf field of seq_file). Also, some systems might be using the slab_nomerge kernel command line flag, which disables this merging behavior. Another approach that I didn't look
Microsoft、社内向けLinux「CBL-Mariner 1.0」の「June 2021 Update」を公開
Microsoftは2021年7月8日（米国時間）、社内向けLinuxディストリビューション「CBL-Mariner 1.0」の「June 2021 Update」を公開した。 CBL-Marinerはクラウドインフラとエッジ製品、サービスに向けた一貫したプラットフォームとなるように設計されており、Linuxカーネルのアップデートに合わせて最新の状態に保たれている。 Microsoftは、「SONiC」「Azure Sphere OS」「Windows Subsystem for Linux」（WSL）といったさまざまなLinux関連技術への投資を拡大しており、CBL-Marinerに関する取り組みもその一環だと述べている。 加えて、CBL-Marinerの公開はオープンソースの取り組みと、Linuxコミュニティーに対する貢献の一環と位置付けられている。さらにMicrosoftは、CBL-
GNU/Linux (x86/x86-64) のシステムコールをアセンブラから呼んでみる - CUBE SUGAR CONTAINER
今回は、表題の通り x86/x86-64 の GNU/Linux でシステムコールをアセンブラから呼んでみる。 システムコールは、OS (ディストリビューション) のコアとなるカーネルがユーザ空間のプログラムに向けて提供しているインターフェースのこと。 なお、アセンブラの実装に関しては以下の二つを試した。 NASM (Netwide Assembler) GAS (GNU Assembler) アセンブラには INTEL 記法と AT&T 記法という二つのシンタックスがある。 NASM はデフォルトで INTEL 記法を、GAS はデフォルトで AT&T 記法を使うことになる。 使った環境は次の通り。 $ uname -sr Linux 4.15.0-65-generic $ nasm -v NASM version 2.13.02 $ as -v GNU assembler versio
Microsoft、オープンソースプロジェクト「ebpf-for-windows」を発表
Microsoftは2021年5月10日（米国時間）、「eBPF」（extended Berkeley Packet Filter）を「Windows 10」と「Windows Server 2016」以降で動作させるためのオープンソースプロジェクト「ebpf-for-windows」を発表した。 eBPFはアプリケーションプログラムのコードをカーネル内で安全に実行するための仕組みで、カーネルを拡張するための手間や時間を軽減する。これまでは主にLinuxで活用されてきた。 例えばDoS（サービス妨害）攻撃からの保護機能を追加したり、オブザーバビリティを実現したりする。 ebpf-for-windowsプロジェクトは、Linuxエコシステムで使われてきたeBPFのツールチェーンとAPIを、開発者がWindowsで利用できるようにすることを目指している。 既存のオープンソースeBPFプロジェク
An Interview With Linus Torvalds: Linux and Git - Part 1 30 Years Of Linux
Jeremy founded Tag1 Consulting in 2007. He has been a contributing core Drupal developer since 2002, and helped establish Drupal as a successful CMS through the early popularity of his personal blog, KernelTrap.org. Over the years, he authored and maintained the core statistics module and throttle module, as well as the pager logic and the initial Drupal 5 installer. He continues to contribute to
My First Kernel Module: A Debugging Nightmare
This is the story of the time I wrote some code, deployed it to production, and ended up bricking the server it was running on by frying the kernel. Beautiful rendition of me frying the kernel This post is about perils of concurrency and race conditions. My code was nearly correct, but ultimately, there were two major synchronization bugs that killed it. This is a really long post that gets into t
eBPF - The Future of Networking & Security
Nov 10, 2020eBPF - The Future of Networking & Security Today is an exciting day for the Cilium community: Isovalent, the company behind Cilium, is announcing its $29M Series A financing round backed by Andreessen Horowitz, Google, and Cisco. This is a perfect occasion to take a deeper look into where eBPF-based networking is coming from and to understand what the excitement is all about. Two weeks
Unlocking eBPF power
My first steps with eBPF. In this article I'm describing how I used bluetooth tracing with eBPF to handle locking of my laptop. I heard “eBPF” so many times in recent days that I’ve decided to give it a try. I have very limited knowledge about kernel tracing so I thought it is good opportunity to learn something new. One particular talk (by Brendan Gregg) especially caught my attention and I recom
Sandboxing in Linux with zero lines of code
Modern Linux operating systems provide many tools to run code more securely. There are namespaces (the basic building blocks for containers), Linux Security Modules, Integrity Measurement Architecture etc. In this post we will review Linux seccomp and learn how to sandbox any (even a proprietary) application without writing a single line of code. Tux by Iwan Gabovitch, GPL Sandbox, Simplified Pixa
Why is there a "V" in SIGSEGV Segmentation Fault?
Why is there a "V" in SIGSEGV Segmentation Fault?06/18/2020 Another long night. I was working on my perfect, bug-free program in C, when the predictable thing happened: $ clang skynet.c -o skynet $ ./skynet.out Segmentation fault (core dumped) Oh, well... Maybe I'll be more lucky taking over the world another night. But then it struck me. My program received a SIGSEGV signal and crashed with "Segm
Who murdered my lovely Prometheus container in Kubernetes cluster?
As of October 1, 2023, LINE has been rebranded as LY Corporation. Visit the new blog of LY Corporation here: LY Corporation Tech Blog This blog post is about an interesting experience I had while investigating and resolving a problem that happened in the Prometheus container which was still in the CrashLoopBackoff state. The phenomenon itself and the solution are obvious and simple; so simple that
Teleforking a process onto a different computer! - Tristan Hume
One day a coworker mentioned that he was thinking about APIs for distributed compute clusters and I jokingly responded “clearly the ideal API would be simply calling telefork() and your process wakes up on every machine of the cluster with the return value being the instance ID”. I ended up captivated by this idea: I couldn’t get over how it was clearly silly, yet way easier than any remote job AP
Why you should run a 64 bit OS on your Raspberry Pi4
One of the cool thing of working for a software company is that very often you get new hardware prototypes to test. But this is not the case, I bought the Rpi4 because it’s extremely cheap! The Rpi4 comes with a quad core ARM Cortex A72, up to 4 GB of RAM and a gigabit ethernet port, at a very low price of 35 $. Raspberry provides Raspbian (a Debian derivative), an already ready distro for their p
A new hash algorithm for Git [LWN.net]
Benefits for LWN subscribersThe primary benefit from subscribing to LWN is helping to keep us publishing, but, beyond that, subscribers get immediate access to all site content and access to a number of extra site features. Please sign up today! The Git source-code management system is famously built on the SHA‑1 hashing algorithm, which has become an increasingly weak foundation over the years. S
Announcing WSL 2
Email Subscriptions are here! Get notified in your email when a new post is published to this blog Today we’re unveiling the newest architecture for the Windows Subsystem for Linux: WSL 2! Changes in this new architecture will allow for: dramatic file system performance increases, and full system call compatibility, meaning you can run more Linux apps in WSL 2 such as Docker. What exactly is WSL 2
Go in a scratch VM
We don’t need a distributionMany of us know that you can run Go binaries in “scratch” containers. Your container doesn’t need to be based on Alpine or Ubuntu. It can be based on nothing and contain just the binary you built from Go source. This is largely because Go code can be statically linked, and so requires no installed libraries. But what about VMs? Normally you start from Ubuntu, or Alpine
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GitHub - BCsabaEngine/QemuRpiRunner: Running ARM8 Rpi 3b+ instance in qemu
Redirecting
How io_uring and eBPF Will Revolutionize Programming in Linux
