Copilot commented on code in PR #39604:
URL: https://github.com/apache/superset/pull/39604#discussion_r3237598198
##########
superset/mcp_service/mcp_config.py:
##########
@@ -284,56 +287,88 @@
def create_default_mcp_auth_factory(app: Flask) -> Optional[Any]:
- """Default MCP auth factory using app.config values."""
- if not app.config.get("MCP_AUTH_ENABLED", False):
- return None
+ """Default MCP auth factory using app.config values.
- jwks_uri = app.config.get("MCP_JWKS_URI")
- public_key = app.config.get("MCP_JWT_PUBLIC_KEY")
- secret = app.config.get("MCP_JWT_SECRET")
+ Returns an auth provider when ``MCP_AUTH_ENABLED=True`` (JWT verifier,
+ optionally wrapped with ``CompositeTokenVerifier`` for API keys) or
+ when only ``FAB_API_KEY_ENABLED=True`` (API-key-only verifier that
+ rejects all non-API-key Bearer tokens at the transport).
+ """
+ auth_enabled = app.config.get("MCP_AUTH_ENABLED", False)
+ api_key_enabled = app.config.get("FAB_API_KEY_ENABLED", False)
- if not (jwks_uri or public_key or secret):
- logger.warning("MCP_AUTH_ENABLED is True but no JWT keys/secret
configured")
+ if not (auth_enabled or api_key_enabled):
return None
- try:
- debug_errors = app.config.get("MCP_JWT_DEBUG_ERRORS", False)
+ jwt_verifier: Any | None = None
- common_kwargs: dict[str, Any] = {
- "issuer": app.config.get("MCP_JWT_ISSUER"),
- "audience": app.config.get("MCP_JWT_AUDIENCE"),
- "required_scopes": app.config.get("MCP_REQUIRED_SCOPES", []),
- }
+ if auth_enabled:
+ jwks_uri = app.config.get("MCP_JWKS_URI")
+ public_key = app.config.get("MCP_JWT_PUBLIC_KEY")
+ secret = app.config.get("MCP_JWT_SECRET")
- # For HS256 (symmetric), use the secret as the public_key parameter
- if app.config.get("MCP_JWT_ALGORITHM") == "HS256" and secret:
- common_kwargs["public_key"] = secret
- common_kwargs["algorithm"] = "HS256"
- else:
- # For RS256 (asymmetric), use public key or JWKS
- common_kwargs["jwks_uri"] = jwks_uri
- common_kwargs["public_key"] = public_key
- common_kwargs["algorithm"] = app.config.get("MCP_JWT_ALGORITHM",
"RS256")
-
- if debug_errors:
- # DetailedJWTVerifier: detailed server-side logging of JWT
- # validation failures. HTTP responses are always generic per
- # RFC 6750 Section 3.1.
- from superset.mcp_service.jwt_verifier import DetailedJWTVerifier
-
- auth_provider = DetailedJWTVerifier(**common_kwargs)
+ if not (jwks_uri or public_key or secret):
+ logger.warning("MCP_AUTH_ENABLED is True but no JWT keys/secret
configured")
+ if not api_key_enabled:
+ return None
else:
- # Default JWTVerifier: minimal logging, generic error responses.
- from fastmcp.server.auth.providers.jwt import JWTVerifier
+ try:
+ jwt_verifier = _build_jwt_verifier(
+ app=app,
+ jwks_uri=jwks_uri,
+ public_key=public_key,
+ secret=secret,
+ )
+ except Exception: # noqa: BLE001 — JWT lib raises many types;
broad catch intentional
+ # Do not log the exception — it may contain secrets (e.g., key
material)
+ logger.error("Failed to create MCP JWT verifier")
+ if not api_key_enabled:
+ return None
+
+ if api_key_enabled:
+ api_key_prefixes = app.config.get("FAB_API_KEY_PREFIXES", ["sst_"])
+ logger.info("API key auth enabled for MCP")
+ return CompositeTokenVerifier(
+ jwt_verifier=jwt_verifier,
+ api_key_prefixes=api_key_prefixes,
+ )
Review Comment:
`FAB_API_KEY_PREFIXES` is read from config as `Any` and passed straight into
`CompositeTokenVerifier`. If a user misconfigures this (e.g. sets a string or
includes empty/whitespace prefixes), `token.startswith(prefix)` can misclassify
tokens (or match everything), causing unexpected auth failures/DoS. Consider
normalizing/validating here (coerce to a list of non-empty strings; otherwise
fall back to the default and log a warning).
##########
superset/mcp_service/composite_token_verifier.py:
##########
@@ -0,0 +1,105 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+"""
+Composite token verifier for MCP authentication.
+
+Routes Bearer tokens to the appropriate verifier based on prefix:
+- Tokens matching FAB_API_KEY_PREFIXES (e.g. ``sst_``) are passed through
+ to the Flask layer where ``_resolve_user_from_api_key()`` handles
+ actual validation via FAB SecurityManager.
+- All other tokens are delegated to the wrapped JWT verifier (when one is
+ configured); when no JWT verifier is configured, non-API-key tokens are
+ rejected at the transport layer.
+"""
+
+import logging
+
+from fastmcp.server.auth import AccessToken
+from fastmcp.server.auth.providers.jwt import TokenVerifier
+
+logger = logging.getLogger(__name__)
+
+# Namespaced claim that flags an AccessToken as an API-key pass-through.
+# Namespacing avoids collision with custom claims an external IdP might
+# happen to mint on a JWT — a plain ``_api_key_passthrough`` claim could
+# be silently misidentified as a Superset API-key request.
+API_KEY_PASSTHROUGH_CLAIM = "_superset_mcp_api_key_passthrough"
+
+
+class CompositeTokenVerifier(TokenVerifier):
+ """Routes Bearer tokens between API key pass-through and JWT verification.
+
+ API key tokens (identified by prefix) are accepted at the transport layer
+ with a marker claim so that ``_resolve_user_from_jwt_context()`` can
+ detect them and fall through to ``_resolve_user_from_api_key()`` for
+ actual validation.
+
+ Args:
+ jwt_verifier: The wrapped JWT verifier for non-API-key tokens.
+ When ``None``, only API-key tokens are accepted; all other
+ Bearer tokens are rejected at the transport layer (used when
+ ``MCP_AUTH_ENABLED=False`` but ``FAB_API_KEY_ENABLED=True``).
+ api_key_prefixes: List of prefixes that identify API key tokens
+ (e.g. ``["sst_"]``).
+ """
+
+ def __init__(
+ self,
+ jwt_verifier: TokenVerifier | None,
+ api_key_prefixes: list[str],
+ ) -> None:
+ super().__init__(
+ base_url=getattr(jwt_verifier, "base_url", None),
+ required_scopes=getattr(jwt_verifier, "required_scopes", None) or
[],
+ )
+ self._jwt_verifier = jwt_verifier
+ self._api_key_prefixes = tuple(api_key_prefixes)
+
Review Comment:
`api_key_prefixes` is converted to a tuple and then used in `startswith`
checks without any validation. If the list contains `""`/whitespace or
non-strings, every token can match or matching can behave unexpectedly.
Recommend filtering/validating prefixes in `__init__` (non-empty `str` only)
and raising or warning on invalid config to avoid misclassification/DoS.
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