The SELECT guard was a denylist of DDL/DML verbs. DuckDB's file readers and
setting introspection are plain SELECTs, so it passed all of these:
SELECT * FROM read_csv_auto('/etc/passwd') -> 200, file contents
SELECT * FROM glob('/etc/*') -> 200, directory listing
SELECT current_setting('s3_secret_access_key') -> 200, the bucket credentials
The last one is the worst: bucket mode installed the S3 credentials with
SET s3_secret_access_key, and settings are readable back out. So one
unauthenticated POST returned the ERA5 bucket key in plaintext -- precisely what
the module docstring says this service exists to avoid ("without shipping S3
credentials to every web task"). /query had no authentication of any kind, while
the comparable /internal/* router has gated its whole surface since it landed.
Three changes, outermost first:
- /query now requires the shared internal token, reusing internal_routes'
dependency. Nothing calls it: the only in-repo caller of this service is
era5lake.py hitting /history, and Centralis reaches the lake through its own
DuckDB rather than this endpoint. /history is deliberately left open for now --
gating it means threading the token through the web->lake hot path.
- Credentials are installed as a DuckDB SECRET instead of SET s3_*. Secret values
are opaque: current_setting() returns NULL and duckdb_secrets() lists the name
and scope but no key material.
- Bucket mode disables LocalFileSystem after the views are created (they resolve
lazily, so ordering matters) and locks the configuration. Local mode cannot do
this -- its views read local parquet -- so the function denylist stays as
defence in depth for dev and tests.
The new guard tests assert the *guard* refused, not merely that the request
failed: several of these shapes (read_parquet on a text file, a bare
'/etc/passwd') error inside DuckDB anyway, so a status-only assertion would keep
passing with the guard deleted. That is the trap the original four-case test fell
into -- it tested negatives shaped like the regex that had been written.
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