HostFunctions is a process-wide singleton (one per gateway engine).
Its `invCtx` field is shared across all WASM instances. For STATELESS
execution the executor sets/clears it per-call but the lock is
released before WASM runs — two concurrent invocations can race on
the field and one's host call can read the other's identity. Window
is microseconds.
For PERSISTENT WS the bug was much worse: invCtx used to be bound
ONCE at instantiation and reused for the connection's lifetime. Two
simultaneous persistent WS connections from different namespaces /
wallets overwrote each other's invCtx, and EVERY subsequent
function_invoke / GetCallerJWTSubject / GetCallerWallet / GetSecret
call from inside the WASM read whatever was bound LAST. Result:
silent identity leak across tenants for as long as the connections
overlapped.
Fix: per-call invCtx propagation through Go's context.Context.
wazero passes the ctx given to api.Function.Call through to host
function callbacks, so every WASM-host hop carries its own invCtx.
- pkg/serverless/invocation_context.go (new): WithInvocationContext +
InvocationContextFromCtx helpers using an unexported invCtxKey.
- pkg/serverless/hostfunctions/invocation_context.go (new):
currentInvocationContext(ctx) — ctx-attached invCtx wins over the
singleton field.
- All host accessors (FunctionInvoke, GetEnv, GetSecret, GetRequestID,
GetCallerWallet, GetWSClientID, GetCallerClaim, GetCallerJWTSubject)
now route through currentInvocationContext(ctx).
- pkg/serverless/persistent/instance.go: every export call's ctx is
wrapped with the per-instance invCtx before being passed to wazero.
- pkg/gateway/handlers/serverless/ws_persistent_handler.go: invCtx is
built per-frame and attached to ctx, not stored on a shared field.
- pkg/serverless/engine.go: removed the SetInvocationContext call at
InstantiatePersistent (no longer needed; ctx carries it).
Stateless still uses the singleton field — its race is latent since
the host-functions split and migrating it is a separate scoped
change.
Tests:
- hostfunctions/invocation_context_test.go covers ctx-wins-over-singleton.
- gateway/handlers/serverless/ws_persistent_handler_test.go covers the
per-frame ctx wiring.
- cli/functions/build_test.go is new coverage for the build path
touched in this change.
VERSION bumped to 0.122.24.
