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Devam Shah
dd59704fdf
CORS: drop allow_credentials=True. With allow_origins=['*'] Starlette reflects
the request Origin and emits Access-Control-Allow-Credentials: true on any
credentialed request — a reflect-any-origin hole. The app authenticates with
Bearer tokens in the Authorization header, so credentialed CORS was never needed.
/icons/{icon_name}: validate against a strict allowlist (re.fullmatch
[A-Za-z0-9._-]+\.png) and assert the resolved path stays inside ICONS_DIR before
any filesystem write or outbound fetch. Closes the path-traversal / arbitrary-write
(CWE-22) and controlled-URL (CWE-73) surface on the unsanitized icon_name.
Adds CORS middleware tests and icon-name validation tests (traversal, encoded
slash, null byte, trailing newline, wrong extension).
Closes #298
Signed-off-by: Devam Shah <devamshah91@gmail.com>
95 lines
3.4 KiB
Python
95 lines
3.4 KiB
Python
"""Unit tests for CORS middleware configuration.
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Verifies that the wildcard-origins + allow_credentials=True spec violation
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(CORS spec §3.2, Fetch §4.7) has been removed. Browsers silently strip
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credentials when the response carries Access-Control-Allow-Origin: * paired
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with Access-Control-Allow-Credentials: true, so the old config was both
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broken and misleading.
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"""
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from fastapi import FastAPI
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from fastapi.middleware.cors import CORSMiddleware
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from fastapi.testclient import TestClient
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from agentic_security.middleware.cors import setup_cors
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def _get_cors_options(app: FastAPI) -> dict:
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"""Extract CORS middleware options from the app's middleware stack."""
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for middleware in app.user_middleware:
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if middleware.cls is CORSMiddleware:
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return middleware.kwargs
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return {}
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class TestCorsSetup:
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"""CORS middleware is configured correctly."""
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def test_cors_middleware_is_registered(self):
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"""setup_cors adds CORSMiddleware to the app."""
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app = FastAPI()
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setup_cors(app)
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cls_names = [m.cls.__name__ for m in app.user_middleware]
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assert "CORSMiddleware" in cls_names
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def test_wildcard_origins_without_credentials(self):
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"""allow_origins=['*'] must not be paired with allow_credentials=True.
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The combination is forbidden by the CORS spec and causes browsers to
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silently drop credentials on every cross-origin request.
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"""
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app = FastAPI()
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setup_cors(app)
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opts = _get_cors_options(app)
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allow_origins = opts.get("allow_origins", [])
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allow_credentials = opts.get("allow_credentials", False)
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if "*" in allow_origins or allow_origins == ["*"]:
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assert not allow_credentials, (
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"allow_origins=['*'] with allow_credentials=True is invalid per "
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"the CORS spec — browsers reject it and credentials are silently dropped"
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)
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def test_cors_allows_cross_origin_requests(self):
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"""Cross-origin preflight requests return a 200 with CORS headers."""
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app = FastAPI()
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@app.get("/probe")
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async def probe():
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return {"ok": True}
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setup_cors(app)
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client = TestClient(app, raise_server_exceptions=True)
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response = client.options(
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"/probe",
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headers={
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"Origin": "http://localhost:3000",
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"Access-Control-Request-Method": "GET",
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},
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)
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assert response.status_code == 200
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assert "access-control-allow-origin" in response.headers
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def test_cors_no_credentials_header_with_wildcard(self):
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"""With wildcard origins, the response must not include
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Access-Control-Allow-Credentials: true."""
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app = FastAPI()
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@app.get("/probe")
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async def probe():
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return {"ok": True}
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setup_cors(app)
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client = TestClient(app)
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response = client.get("/probe", headers={"Origin": "http://evil.example.com"})
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acao = response.headers.get("access-control-allow-origin", "")
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acac = response.headers.get("access-control-allow-credentials", "false")
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if acao == "*":
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assert acac.lower() != "true", (
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"Wildcard ACAO + ACAC:true is a spec violation (RFC 6454 §7.2, "
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"Fetch §4.7) and silently breaks credentialed cross-origin requests"
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)
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