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superset2/superset/mcp_service/auth.py

297 lines
9.8 KiB
Python

# 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.
"""
Minimal authentication hooks for MCP tools.
This is a placeholder implementation that provides basic user context.
Future enhancements (to be added in separate PRs):
- JWT token authentication and validation
- User impersonation support
- Permission checking with scopes
- Comprehensive audit logging
- Field-level permissions
"""
import logging
from typing import Any, Callable, TYPE_CHECKING, TypeVar
from flask import g
from flask_appbuilder.security.sqla.models import User
if TYPE_CHECKING:
from superset.connectors.sqla.models import SqlaTable
# Type variable for decorated functions
F = TypeVar("F", bound=Callable[..., Any])
logger = logging.getLogger(__name__)
def get_user_from_request() -> User:
"""
Get the current user for the MCP tool request.
Priority order:
1. g.user if already set (by Preset workspace middleware)
2. MCP_DEV_USERNAME from configuration (for development/testing)
Returns:
User object with roles and groups eagerly loaded
Raises:
ValueError: If user cannot be authenticated or found
"""
from flask import current_app
from sqlalchemy.orm import joinedload
from superset.extensions import db
# First check if user is already set by Preset workspace middleware
if hasattr(g, "user") and g.user:
return g.user
# Fall back to configured username for development/single-user deployments
username = current_app.config.get("MCP_DEV_USERNAME")
if not username:
raise ValueError(
"No authenticated user found. "
"Either pass a valid JWT bearer token or configure "
"MCP_DEV_USERNAME for development."
)
# Query user directly with eager loading to ensure fresh session-bound object
# Do NOT use security_manager.find_user() as it may return cached/detached user
user = (
db.session.query(User)
.options(joinedload(User.roles), joinedload(User.groups))
.filter(User.username == username)
.first()
)
if not user:
raise ValueError(
f"User '{username}' not found. "
f"Please create admin user with: superset fab create-admin"
)
return user
def has_dataset_access(dataset: "SqlaTable") -> bool:
"""
Validate user has access to the dataset.
This function checks if the current user (from Flask g.user context)
has permission to access the given dataset using Superset's security manager.
Args:
dataset: The SqlaTable dataset to check access for
Returns:
True if user has access, False otherwise
Security Note:
This should be called after mcp_auth_hook has set g.user.
Returns False on any error to fail securely.
"""
try:
from superset import security_manager
# Check if user has read access to the dataset
if hasattr(g, "user") and g.user:
# Use Superset's security manager to check dataset access
return security_manager.can_access_datasource(datasource=dataset)
# If no user context, deny access
return False
except Exception as e:
logger.warning("Error checking dataset access: %s", e)
return False # Deny access on error
def _setup_user_context() -> User:
"""
Set up user context for MCP tool execution.
Returns:
User object with roles and groups loaded
"""
user = get_user_from_request()
# Validate user has necessary relationships loaded
# (Force access to ensure they're loaded if lazy)
user_roles = user.roles # noqa: F841
if hasattr(user, "groups"):
user_groups = user.groups # noqa: F841
g.user = user
return user
def _cleanup_session_on_error() -> None:
"""Clean up database session after an exception."""
from superset.extensions import db
# pylint: disable=consider-using-transaction
try:
db.session.rollback()
db.session.remove()
except Exception as e:
logger.warning("Error cleaning up session after exception: %s", e)
def _cleanup_session_finally() -> None:
"""Clean up database session in finally block."""
from superset.extensions import db
# Rollback active session (no exception occurred)
# Do NOT call remove() on success to avoid detaching user
try:
if db.session.is_active:
# pylint: disable=consider-using-transaction
db.session.rollback()
except Exception as e:
logger.warning("Error in finally block: %s", e)
def mcp_auth_hook(tool_func: F) -> F:
"""
Authentication and authorization decorator for MCP tools.
This decorator assumes Flask application context and g.user
have already been set by WorkspaceContextMiddleware.
Supports both sync and async tool functions.
TODO (future PR): Add permission checking
TODO (future PR): Add JWT scope validation
TODO (future PR): Add comprehensive audit logging
"""
import functools
import inspect
import types
is_async = inspect.iscoroutinefunction(tool_func)
if is_async:
@functools.wraps(tool_func)
async def async_wrapper(*args: Any, **kwargs: Any) -> Any:
user = _setup_user_context()
try:
logger.debug(
"MCP tool call: user=%s, tool=%s",
user.username,
tool_func.__name__,
)
result = await tool_func(*args, **kwargs)
return result
except Exception:
_cleanup_session_on_error()
raise
finally:
_cleanup_session_finally()
wrapper = async_wrapper
else:
@functools.wraps(tool_func)
def sync_wrapper(*args: Any, **kwargs: Any) -> Any:
user = _setup_user_context()
try:
logger.debug(
"MCP tool call: user=%s, tool=%s",
user.username,
tool_func.__name__,
)
result = tool_func(*args, **kwargs)
return result
except Exception:
_cleanup_session_on_error()
raise
finally:
_cleanup_session_finally()
wrapper = sync_wrapper
# Merge original function's __globals__ into wrapper's __globals__
# This allows get_type_hints() to resolve type annotations from the
# original module (e.g., Context from fastmcp)
# FastMCP 2.13.2+ uses get_type_hints() which needs access to these types
merged_globals = {**wrapper.__globals__, **tool_func.__globals__} # type: ignore[attr-defined]
new_wrapper = types.FunctionType(
wrapper.__code__, # type: ignore[attr-defined]
merged_globals,
wrapper.__name__,
wrapper.__defaults__, # type: ignore[attr-defined]
wrapper.__closure__, # type: ignore[attr-defined]
)
# Copy __dict__ but exclude __wrapped__
# NOTE: We intentionally do NOT preserve __wrapped__ here.
# Setting __wrapped__ causes inspect.signature() to follow the chain
# and find 'ctx' in the original function's signature, even after
# FastMCP's create_function_without_params removes it from annotations.
# This breaks Pydantic's TypeAdapter which expects signature params
# to match type_hints.
new_wrapper.__dict__.update(
{k: v for k, v in wrapper.__dict__.items() if k != "__wrapped__"}
)
new_wrapper.__module__ = wrapper.__module__
new_wrapper.__qualname__ = wrapper.__qualname__
new_wrapper.__annotations__ = wrapper.__annotations__
# Copy docstring from original function (not wrapper, which may have lost it)
new_wrapper.__doc__ = tool_func.__doc__
# Set __signature__ from the original function, but:
# 1. Remove ctx parameter - FastMCP tools don't expose it to clients
# 2. Skip if original has *args (parse_request output has its own handling)
from fastmcp import Context as FMContext
tool_sig = inspect.signature(tool_func)
has_var_positional = any(
p.kind == inspect.Parameter.VAR_POSITIONAL for p in tool_sig.parameters.values()
)
if not has_var_positional:
# For functions without *args, preserve signature but remove ctx
new_params = []
for _name, param in tool_sig.parameters.items():
# Skip ctx parameter - FastMCP tools don't expose it to clients
if param.annotation is FMContext or (
hasattr(param.annotation, "__name__")
and param.annotation.__name__ == "Context"
):
continue
new_params.append(param)
new_wrapper.__signature__ = tool_sig.replace( # type: ignore[attr-defined]
parameters=new_params
)
# Also remove ctx from annotations to match signature
if "ctx" in new_wrapper.__annotations__:
del new_wrapper.__annotations__["ctx"]
# For functions with *args (parse_request output), the signature
# is already set by parse_request without ctx.
return new_wrapper # type: ignore[return-value]