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Wasm in the browser is pretty cool, but I still don’t understand why you would want to give up the advantages of native code when running server side. Native co

Wasm in the browser is pretty cool, but I still don’t understand why you would want to give up the advantages of native code when running server side. Native code is faster and can actually use features of your hardware like the MMU, giving you things like virtual address space and memory protections. If you want to glue modules together, we can already do that - just expose symbols in your libraries and link them together.

necessary 4y ago
If I understand the sandboxing capabilities correctly, it seems like it could be a neat way to run untrusted code from users.
- eyberg 4y ago
  That's looking from the outside in but consider looking at it from the end-user (read: attacker's) viewpoint. The lack of memory protections that wasm currently has such as the lack of read-only memory or memory randomizations or anything else you really can't run any code with any level of assurance that it won't be taken advantage of. Typically a software engineer doesn't have to think about someone being able to rewrite a function during run-time or a statically defined variable because those memory protections are in place. It simply isn't allowed. However in wasm land, if you have a function that is say 'func isAdmin()' for instance you'd expect to return true if the logic is correct but without memory protections an attacker can force it to return true every time. This is one of the pretty serious features missing in wasm currently.
  - int_19h 4y ago
    wasm has separate address spaces for code and data, and wasm code does not even have read access to the code space, much less writing to it. The call stack is also completely isolated and not addressable. So how exactly would malicious code running in a wasm sandbox "rewrite a function"?
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  - colordrops 4y ago
    How is this possible in wasm? Forgive my ignorance? Would this only be the case if multiple binaries are running in the same VM?

necessary 4y ago

If I understand the sandboxing capabilities correctly, it seems like it could be a neat way to run untrusted code from users.

eyberg 4y ago
That's looking from the outside in but consider looking at it from the end-user (read: attacker's) viewpoint. The lack of memory protections that wasm currently has such as the lack of read-only memory or memory randomizations or anything else you really can't run any code with any level of assurance that it won't be taken advantage of. Typically a software engineer doesn't have to think about someone being able to rewrite a function during run-time or a statically defined variable because those memory protections are in place. It simply isn't allowed. However in wasm land, if you have a function that is say 'func isAdmin()' for instance you'd expect to return true if the logic is correct but without memory protections an attacker can force it to return true every time. This is one of the pretty serious features missing in wasm currently.
- int_19h 4y ago
  wasm has separate address spaces for code and data, and wasm code does not even have read access to the code space, much less writing to it. The call stack is also completely isolated and not addressable. So how exactly would malicious code running in a wasm sandbox "rewrite a function"?
  - deleted 4y ago
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- colordrops 4y ago
  How is this possible in wasm? Forgive my ignorance? Would this only be the case if multiple binaries are running in the same VM?