Add chapter Everything is a Capability

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Tate, Hongliang Tian
2022-07-20 23:43:40 -07:00
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@ -71,7 +71,8 @@ Here is an overview of the architecture of KxOS.
## Features
**1. Security by design.** Security is our top priority in the design of KxOS. As such, we adopt the widely acknowledged security best practice of [least privilege principle](https://en.wikipedia.org/wiki/Principle_of_least_privilege) and enforce it in a fashion that leverages the full strengths of Rust. To do so, we partition KxOS into two halves: a _privileged_ OS core and _unprivileged_ OS components. As a result, we can write the OS components almost entirely in _safe_ Rust, while taking extra cautions with the _unsafe_ Rust code in the OS core. Furthermore, we propose the idea of _everything-is-a-capability_, which elevates the status of [capabilities](https://en.wikipedia.org/wiki/Capability-based_security) to the level of a ubiquitous security primitive used throughout the OS. We make novel use of Rust's advanced features (e.g., [type-level programming](https://willcrichton.net/notes/type-level-programming/)) to make capabilities more accessible and efficient. The net result is improved security and uncompromised performance.
**1. Security by design.** Security is our top priority in the design of KxOS. As such, we adopt the widely acknowledged security best practice of [least privilege principle](https://en.wikipedia.org/wiki/Principle_of_least_privilege) and enforce it in a fashion that leverages the full strengths of Rust. To do so, we partition KxOS into two halves: a _privileged_ OS core and _unprivileged_ OS components. All OS components are written entirely in _safe_ Rust and only the privileged OS core
is allowed to have _unsafe_ Rust code. Furthermore, we propose the idea of _everything-is-a-capability_, which elevates the status of [capabilities](https://en.wikipedia.org/wiki/Capability-based_security) to the level of a ubiquitous security primitive used throughout the OS. We make novel use of Rust's advanced features (e.g., [type-level programming](https://willcrichton.net/notes/type-level-programming/)) to make capabilities more accessible and efficient. The net result is improved security and uncompromised performance.
**2. Trustworthy OS-level virtualization.** OS-level virtualization mechanisms (like Linux's cgroups and namespaces) enable containers, a more lightweight and arguably more popular alternative to virtual machines (VMs). But there is one problem with containers: they are not as secure as VMs (see [StackExchange](https://security.stackexchange.com/questions/169642/what-makes-docker-more-secure-than-vms-or-bare-metal), [LWN](https://lwn.net/Articles/796700/), and [AWS](https://docs.aws.amazon.com/AmazonECS/latest/bestpracticesguide/security-tasks-containers.html)). There is a real risk that malicious containers may exploit privilege escalation bugs in the OS kernel to attack the host. [A study](https://dl.acm.org/doi/10.1145/3274694.3274720) found that 11 out of 88 kernel exploits are effective in breaking the container sandbox. The seemingly inherent insecurity of OS kernels leads to a new breed of container implementations (e.g., [Kata](https://katacontainers.io/) and [gVisor](https://gvisor.dev/)) that are based on VMs, instead of kernels, for isolation and sandboxing. We argue that this unfortunate retreat from OS-level virtualization to VM-based one is unwarranted---if the OS kernels are secure enough. And this is exactly what we plan to achieve with KxOS. We aim to provide a trustworthy OS-level virtualization mechanism on KxOS.