3 ms·

wasmtime works as long as you make sure to include the lib directory % wasmtime run --dir .::/ python.wasm -c 'print("hello world")' hello world disc

by conroy 2y ago

wasmtime works as long as you make sure to include the lib directory % wasmtime run --dir .::/ python.wasm -c 'print("hello world")' hello world disclaimer: I run a code execution API service (https://riza.io/playground https://riza.io/playground) that does this and more (HTTP, packages, etc.)

simonw 2y ago
Wow that's almost what I want. wget https://github.com/brettcannon/cpython-wasi-build/releases/download/v3.13.0/python-3.13.0-wasi_sdk-24.zip unzip python-3.13.0-wasi_sdk-24.zip wasmtime run --dir .::/ python.wasm -c 'print("hello world")' So far so good! But... it looks like that --dir option mounts the current directory as both readable and writable: wasmtime run --dir .::/ python.wasm -c 'print(len(open("python.wasm", "rb").read()))' # Outputs 28775526 But malicious code can break the system like this: wasmtime run --dir .::/ python.wasm -c 'open("python.wasm", "wb").write(b"blah")' And now it fails with an error if you try to run it because we over-wrote python.wasm. Even if I move python.wasm out of the current directory I'd still be able to break things by breaking those other lib files. Although... I guess I could use unix filesystem permissions to make those read-only? That could work.
- compressedgas 2y ago
  You might need to wrap the wasmtime command in firejail or bubblewrap with appropriate arguments to get the operation restrictions you want.
  - sitkack 2y ago
    While that might be a workable stop gap, there is zero reason why this couldn’t be handle in the wasi shim layer. This is exactly what wasi was designed for.
- conroy 2y ago
  This is just a limitation of the wasmtime CLI. The full Rust API let's you mount filesystems as read-only. Not sure why it's not exposed as an argument.
  - simonw 2y ago
    Thanks - I just found an open issue for exposing that in the Python API: https://github.com/bytecodealliance/wasmtime-py/issues/251 https://github.com/bytecodealliance/wasmtime-py/issues/251
avinassh 2y ago
> .::/ whats this magic
- wyldfire 2y ago
  Wild speculation based on very little understanding of WASI/WASM: Perhaps "--dir .::/" means treat the host directory "." as the guest directory "/"?
michaelmior 2y ago
s/disclaimer/shameless plug/ :P Nothing wrong with it, but not really a disclaimer.

by conroy 2y ago

simonw 2y ago

Wow that's almost what I want. wget https://github.com/brettcannon/cpython-wasi-build/releases/download/v3.13.0/python-3.13.0-wasi_sdk-24.zip unzip python-3.13.0-wasi_sdk-24.zip wasmtime run --dir .::/ python.wasm -c 'print("hello world")' So far so good! But... it looks like that --dir option mounts the current directory as both readable and writable: wasmtime run --dir .::/ python.wasm -c 'print(len(open("python.wasm", "rb").read()))' # Outputs 28775526 But malicious code can break the system like this: wasmtime run --dir .::/ python.wasm -c 'open("python.wasm", "wb").write(b"blah")' And now it fails with an error if you try to run it because we over-wrote python.wasm. Even if I move python.wasm out of the current directory I'd still be able to break things by breaking those other lib files. Although... I guess I could use unix filesystem permissions to make those read-only? That could work.

compressedgas 2y ago
You might need to wrap the wasmtime command in firejail or bubblewrap with appropriate arguments to get the operation restrictions you want.
- sitkack 2y ago
  While that might be a workable stop gap, there is zero reason why this couldn’t be handle in the wasi shim layer. This is exactly what wasi was designed for.
conroy 2y ago
This is just a limitation of the wasmtime CLI. The full Rust API let's you mount filesystems as read-only. Not sure why it's not exposed as an argument.
- simonw 2y ago
  Thanks - I just found an open issue for exposing that in the Python API: https://github.com/bytecodealliance/wasmtime-py/issues/251 https://github.com/bytecodealliance/wasmtime-py/issues/251

avinassh 2y ago

> .::/ whats this magic

wyldfire 2y ago
Wild speculation based on very little understanding of WASI/WASM: Perhaps "--dir .::/" means treat the host directory "." as the guest directory "/"?

michaelmior 2y ago

s/disclaimer/shameless plug/ :P Nothing wrong with it, but not really a disclaimer.