Dropbox Rust

admin 11/22/2021
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Once the files have been uploaded, they need to be durably persisted as long as the user wishes, and at a moment’s notice they may need to be restored to their original bits exactly in a repeatable, secure way.

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The RUST server header image must adhere to the following: Width: 1024 px; Height: 512 px; File Type:.jpg,.png; The file must be hosted in a publicly accessible web location (Dropbox, Imgur, etc) Get the current RUST server header image. Use the command below to report the current configuration: server.headerimage. On success the console will. Who is using Rust? Companies large and small are using Rust in production all over the world, including Mozilla, Dropbox, npm, Postmates, Braintree and others. Check out this list of current users. Rust is an open source project with an amazing community of people behind it.

May 18, 2020 Rust was created at Mozilla and the project boasts that today, 'Apple, Amazon, Dropbox, Facebook, Google, and Microsoft are choosing to use Rust for its performance, reliability,. Dropbox decided to use a new systems programming language, called Rust, to build this next-generation software-rather than go, the language the rest of the system was written in. This talk will walk through an overview of the though process behind this project, contrast the new design against the old, and detail Rust's role as a pivotal part.

For Dropbox, any decompressor must exhibit three properties:

1. it must be safe and secure, even against bytes crafted by modified or hostile clients,
2. it must be deterministic—the same bytes must result in the same output,
3. it must be fast.

With these properties we can accept any arbitrary bytes from a client and have full knowledge that those bytes factually represent the file data.

Unfortunately, the compressor supplied by the Brotli project only has the third property: it is very fast. Since the Brotli decompressor consists of a substantial amount of C code written by human beings, it is possibly neither deterministic nor safe and secure against carefully crafted hostile data. It could be both secure and deterministic, but there is simply too much code to reason through a mathematical proof of this hypothesis.

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Operating at Dropbox scale, we need to guarantee the security of our data, so our approach was to break down the problem into components. By writing a new Brotli decompressor in a language that is safe and deterministic, we only needed to analyze the language, not all the code written in it. This is because such a language would prevent us from executing unsafe code (eg. array out of bounds access) or nondeterministic code (eg reading uninitialized memory), so therefore we can trust the code to repeatably produce the same output without any security risks.

The Rust programing language fits the bill perfectly: it’s a language that promises memory safety without garbage collection, concurrency without data races, and abstractions without overhead. It also has sufficient performance for our needs. That means that code written in Rust has the same memory requirements as the equivalent code written in C. At Dropbox, many of our services are actually memory bound, so this is a key advantage over a garbage collected language.

Dropbox Rust

We created rust-brotli, a direct port of the C decompressor into safe Rust. We also went one step further and wrote our own Rust memory allocator that can be used to allocate memory in the standard way using Boxes, or from a fixed size allocation on the heap, or even a pool on the stack.

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This allows us to put an upper bound on the memory we would allow for the decode of a single 4MB block. After the virtual memory is allocated, we enable a timer using the alarm syscall, to avoid a runaway process that never returns control. Finally, we enter the process into the secure computing (SECCOMP) mode, disabling any system calls except for read, write, sigreturn and exit.