alt Hacker NewsThe Linux kernel is not usable as a security boundary, so anyone who wants to do "shared hosting" and not be hacked needs to use something else, like gVisor or firecracker VMs
The only important system that uses it as a security boundary is Android and there is mitigated by the fact that APKs need user approval, plus strict SELinux and seccomp policy plus the GrapheneOS hardening, and in this case the mitigations succeeded (https://discuss.grapheneos.org/d/35110-grapheneos-is-protect...)
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I thought that was the entire design goal of the Unix model, didn't it originate in the times when hundreds of users logged on to a shared mainframe? There are still public Unix servers like SDF out there. SELinux is just an extra layer so that if someone gets root (ex. due to an exploit in your setuid code or cron jobs etc) it's not game over.
I'm quite sure there are many application hosting providers which rely on container runtime such as runC (default runtime of containerd/Docker), and a shared kernel between users.
A LOT of websites are tenants on WHM/CPanel hosts. Not to mention how many agencies use it for their clients Wordpress sites.