Le 25/04/2022 à 23:04, David Li a écrit :
The WebAssembly documentation has a rundown of the techniques used:
https://webassembly.org/docs/security/
I think usually you would run WASM in-process, though we could indeed also put
it in a subprocess to further isolate things.
Would WASM be able to interact in-process with non-WASM buffers safely?
It's not obvious from reading the page above.
It would be interesting to define the Flight "harness" protocol. Handling
heterogeneous arguments may require some evolution in Flight (e.g. if the function is non
scalar and arguments are of different length - we'd need something like the ColumnBag
proposal, so this might be a good reason to revive that).
On Mon, Apr 25, 2022, at 16:35, Antoine Pitrou wrote:
Le 25/04/2022 à 22:19, Wes McKinney a écrit :
I was going to reply to this e-mail thread on user@ but thought I
would start a new thread on dev@.
Executing user-defined functions in memory, especially untrusted
functions, in general is unsafe. For "trusted" functions, having an
in-memory API for writing them in user languages is very useful. I
remember tinkering with adding UDFs in Impala with LLVM IR, which
would allow UDFs to have performance consistent with built-ins
(because built-in functions are all inlined into code-generated
expressions), but segfaults would bring down the server, so only
admins could be trusted to add new UDFs.
However, I wonder if we should eventually define an "external UDF"
protocol and an example UDF "harness", using Flight to do RPC across
the process boundaries. So the idea is that an external local UDF
Flight execution service is spun up, and then data is sent to the UDF
in a DoExchange call.
As Jacques pointed out in an interview 1], a compelling solution to
the UDF sandboxing problem is WASM. This allows "untrusted" WASM
functions to be run safely in-process.
How does the sandboxing work in this case? Is it simply executing in a
separate process with restricted capabilities, or are other mechanisms
put in place?
