Merge pull request #38 from DavidBuchanan314/token-revocation

refreshSession, deleteSession

migration_scripts/v2.py

@@ -7,7 +7,8 @@
 
 from millipds import static_config
 
-with apsw.Connection(static_config.MAIN_DB_PATH) as con:
+
+def migrate(con):
 	version_now, *_ = con.execute("SELECT db_version FROM config").fetchone()
 
 	assert version_now == 1
@@ -36,4 +37,9 @@
 
 	con.execute("UPDATE config SET db_version=2")
 
-print("v1 -> v2 Migration successful")
+
+if __name__ == "__main__":
+	with apsw.Connection(static_config.MAIN_DB_PATH) as con:
+		migrate(con)
+
+	print("v1 -> v2 Migration successful")

migration_scripts/v3.py

@@ -0,0 +1,34 @@
+# TODO: some smarter way of handling migrations
+
+import apsw
+import apsw.bestpractice
+
+apsw.bestpractice.apply(apsw.bestpractice.recommended)
+
+from millipds import static_config
+
+
+def migrate(con: apsw.Connection):
+	version_now, *_ = con.execute("SELECT db_version FROM config").fetchone()
+
+	assert version_now == 2
+
+	con.execute(
+		"""
+		CREATE TABLE revoked_token(
+			did TEXT NOT NULL,
+			jti TEXT NOT NULL,
+			expires_at INTEGER NOT NULL,
+			PRIMARY KEY (did, jti)
+		) STRICT, WITHOUT ROWID
+		"""
+	)
+
+	con.execute("UPDATE config SET db_version=3")
+
+
+if __name__ == "__main__":
+	with apsw.Connection(static_config.MAIN_DB_PATH) as con:
+		migrate(con)
+
+	print("v2 -> v3 Migration successful")

src/millipds/appview_proxy.py

@@ -29,14 +29,16 @@ async def service_proxy(request: web.Request, service: Optional[str] = None):
 		)
 		if did_doc is None:
 			return web.HTTPInternalServerError(
-				f"unable to resolve service {service!r}"
+				text=f"unable to resolve service {service!r}"
 			)
-		for service in did_doc.get("service", []):
-			if service.get("id") == fragment:
-				service_route = service["serviceEndpoint"]
+		for service_info in did_doc.get("service", []):
+			if service_info.get("id") == fragment:
+				service_route = service_info["serviceEndpoint"]
 				break
 		else:
-			return web.HTTPBadRequest(f"unable to resolve service {service!r}")
+			return web.HTTPBadRequest(
+				text=f"unable to resolve service {service!r}"
+			)
 	else:  # fall thru to assuming bsky appview
 		service_did = db.config["bsky_appview_did"]
 		service_route = db.config["bsky_appview_pfx"]

src/millipds/auth_bearer.py

@@ -11,6 +11,44 @@
 routes = web.RouteTableDef()
 
 
+def verify_symmetric_token(
+	request: web.Request, token: str, expected_scope: str
+) -> dict:
+	db = get_db(request)
+	try:
+		payload: dict = jwt.decode(
+			jwt=token,
+			key=db.config["jwt_access_secret"],
+			algorithms=["HS256"],
+			audience=db.config["pds_did"],
+			options={
+				"require": ["exp", "iat", "scope", "jti", "sub"],
+				"verify_exp": True,
+				"verify_iat": True,
+				"strict_aud": True,  # may be unnecessary
+			},
+		)
+	except jwt.exceptions.PyJWTError:
+		raise web.HTTPUnauthorized(text="invalid jwt")
+
+	revoked = db.con.execute(
+		"SELECT COUNT(*) FROM revoked_token WHERE did=? AND jti=?",
+		(payload["sub"], payload["jti"]),
+	).fetchone()[0]
+
+	if revoked:
+		raise web.HTTPUnauthorized(text="revoked token")
+
+	# if we reached this far, the payload must've been signed by us
+	if payload.get("scope") != expected_scope:
+		raise web.HTTPUnauthorized(text="invalid jwt scope")
+
+	if not payload.get("sub", "").startswith("did:"):
+		raise web.HTTPUnauthorized(text="invalid jwt: invalid subject")
+
+	return payload
+
+
 def authenticated(handler):
 	"""
 	There are three types of auth:
@@ -39,30 +77,9 @@ async def authentication_handler(request: web.Request, *args, **kwargs):
 		)
 		# logger.info(unverified)
 		if unverified["header"]["alg"] == "HS256":  # symmetric secret
-			try:
-				payload: dict = jwt.decode(
-					jwt=token,
-					key=db.config["jwt_access_secret"],
-					algorithms=["HS256"],
-					audience=db.config["pds_did"],
-					options={
-						"require": ["exp", "iat", "scope"],  # consider iat?
-						"verify_exp": True,
-						"verify_iat": True,
-						"strict_aud": True,  # may be unnecessary
-					},
-				)
-			except jwt.exceptions.PyJWTError:
-				raise web.HTTPUnauthorized(text="invalid jwt")
-
-			# if we reached this far, the payload must've been signed by us
-			if payload.get("scope") != "com.atproto.access":
-				raise web.HTTPUnauthorized(text="invalid jwt scope")
-
-			subject: str = payload.get("sub", "")
-			if not subject.startswith("did:"):
-				raise web.HTTPUnauthorized(text="invalid jwt: invalid subject")
-			request["authed_did"] = subject
+			request["authed_did"] = verify_symmetric_token(
+				request, token, "com.atproto.access"
+			)["sub"]
 		else:  # asymmetric service auth (scoped to a specific lxm)
 			did: str = unverified["payload"]["iss"]
 			if not did.startswith("did:"):
@@ -81,7 +98,7 @@ async def authentication_handler(request: web.Request, *args, **kwargs):
 					algorithms=[alg],
 					audience=db.config["pds_did"],
 					options={
-						"require": ["exp", "iat", "lxm"],
+						"require": ["exp", "iat", "lxm", "jti", "iss"],
 						"verify_exp": True,
 						"verify_iat": True,
 						"strict_aud": True,  # may be unnecessary
@@ -90,6 +107,14 @@ async def authentication_handler(request: web.Request, *args, **kwargs):
 			except jwt.exceptions.PyJWTError:
 				raise web.HTTPUnauthorized(text="invalid jwt")
 
+			revoked = db.con.execute(
+				"SELECT COUNT(*) FROM revoked_token WHERE did=? AND jti=?",
+				(payload["iss"], payload["jti"]),
+			).fetchone()[0]
+
+			if revoked:
+				raise web.HTTPUnauthorized(text="revoked token")
+
 			request_lxm = request.path.rpartition("/")[2].partition("?")[0]
 			if request_lxm != payload.get("lxm"):
 				raise web.HTTPUnauthorized(text="invalid jwt: bad lxm")

src/millipds/database.py

@@ -245,6 +245,19 @@ def _init_tables(self):
 			"""
 		)
 
+		# this is only for the tokens *we* issue, dpop jti will be tracked separately
+		# there's no point remembering that an expired token was revoked, and we'll garbage-collect these periodically
+		self.con.execute(
+			"""
+			CREATE TABLE revoked_token(
+				did TEXT NOT NULL,
+				jti TEXT NOT NULL,
+				expires_at INTEGER NOT NULL,
+				PRIMARY KEY (did, jti)
+			) STRICT, WITHOUT ROWID
+			"""
+		)
+
 	def update_config(
 		self,
 		pds_pfx: Optional[str] = None,

src/millipds/service.py

@@ -25,7 +25,7 @@
 from . import crypto
 from . import util
 from .appview_proxy import service_proxy
-from .auth_bearer import authenticated
+from .auth_bearer import authenticated, verify_symmetric_token
 from .app_util import *
 from .did import DIDResolver
 
@@ -203,6 +203,53 @@ async def server_describe_server(request: web.Request):
 	)
 
 
+def session_info(request: web.Request) -> dict:
+	return {
+		"handle": get_db(request).handle_by_did(request["authed_did"]),
+		"did": request["authed_did"],
+		"email": "tfw_no@email.invalid",  # this and below are just here for testing lol
+		"emailConfirmed": True,
+		# "didDoc": {}, # iiuc this is only used for entryway usecase?
+	}
+
+
+def generate_session_tokens(request: web.Request) -> dict:
+	db = get_db(request)
+	unix_seconds_now = int(time.time())
+	# use the same jti for both tokens, so revoking one revokes both
+	jti = str(uuid.uuid4())
+	access_jwt = jwt.encode(
+		{
+			"scope": "com.atproto.access",
+			"aud": db.config["pds_did"],
+			"sub": request["authed_did"],
+			"iat": unix_seconds_now,
+			"exp": unix_seconds_now + static_config.ACCESS_EXP,
+			"jti": jti,
+		},
+		db.config["jwt_access_secret"],
+		"HS256",
+	)
+
+	refresh_jwt = jwt.encode(
+		{
+			"scope": "com.atproto.refresh",
+			"aud": db.config["pds_did"],
+			"sub": request["authed_did"],
+			"iat": unix_seconds_now,
+			"exp": unix_seconds_now + static_config.REFRESH_EXP,
+			"jti": jti,
+		},
+		db.config["jwt_access_secret"],
+		"HS256",
+	)
+
+	return {
+		"accessJwt": access_jwt,
+		"refreshJwt": refresh_jwt,
+	}
+
+
 # TODO: ratelimit this!!!
 @routes.post("/xrpc/com.atproto.server.createSession")
 async def server_create_session(request: web.Request):
@@ -228,44 +275,53 @@ async def server_create_session(request: web.Request):
 	except ValueError:
 		raise web.HTTPUnauthorized(text="incorrect identifier or password")
 
-	# prepare access tokens
-	unix_seconds_now = int(time.time())
-	access_jwt = jwt.encode(
-		{
-			"scope": "com.atproto.access",
-			"aud": db.config["pds_did"],
-			"sub": did,
-			"iat": unix_seconds_now,
-			"exp": unix_seconds_now + 60 * 60 * 24,  # 24h
-			"jti": str(uuid.uuid4()),
-		},
-		db.config["jwt_access_secret"],
-		"HS256",
+	# both generate_session_tokens and session_info need this
+	request["authed_did"] = did
+
+	return web.json_response(
+		session_info(request) | generate_session_tokens(request)
 	)
 
-	refresh_jwt = jwt.encode(
-		{
-			"scope": "com.atproto.refresh",
-			"aud": db.config["pds_did"],
-			"sub": did,
-			"iat": unix_seconds_now,
-			"exp": unix_seconds_now + 60 * 60 * 24 * 90,  # 90 days!
-			"jti": str(uuid.uuid4()),
-		},
-		db.config["jwt_access_secret"],
-		"HS256",
+
+@routes.post("/xrpc/com.atproto.server.refreshSession")
+async def server_refresh_session(request: web.Request):
+	auth = request.headers.get("Authorization", "")
+	if not auth.startswith("Bearer "):
+		raise web.HTTPUnauthorized(text="invalid auth type")
+	token = auth.removeprefix("Bearer ")
+	token_payload = verify_symmetric_token(
+		request, token, "com.atproto.refresh"
 	)
+	request["authed_did"] = token_payload["sub"]
 
+	get_db(request).con.execute(
+		"INSERT INTO revoked_token (did, jti, expires_at) VALUES (?, ?, ?)",
+		(token_payload["sub"], token_payload["jti"], token_payload["exp"]),
+	)
 	return web.json_response(
-		{
-			"did": did,
-			"handle": handle,
-			"accessJwt": access_jwt,
-			"refreshJwt": refresh_jwt,
-		}
+		session_info(request) | generate_session_tokens(request)
 	)
 
 
+# NOTE: deleteSession requires refresh token as auth, not access token
+@routes.post("/xrpc/com.atproto.server.deleteSession")
+async def server_delete_session(request: web.Request):
+	auth = request.headers.get("Authorization", "")
+	if not auth.startswith("Bearer "):
+		raise web.HTTPUnauthorized(text="invalid auth type")
+	token = auth.removeprefix("Bearer ")
+	token_payload = verify_symmetric_token(
+		request, token, "com.atproto.refresh"
+	)
+
+	get_db(request).con.execute(
+		"INSERT INTO revoked_token (did, jti, expires_at) VALUES (?, ?, ?)",
+		(token_payload["sub"], token_payload["jti"], token_payload["exp"]),
+	)
+
+	return web.Response()
+
+
 @routes.get("/xrpc/com.atproto.server.getServiceAuth")
 @authenticated
 async def server_get_service_auth(request: web.Request):
@@ -302,7 +358,7 @@ async def server_get_service_auth(request: web.Request):
 					"lxm": lxm,
 					"exp": exp,
 					"iat": now,
-					"jti": str(uuid.uuid4())
+					"jti": str(uuid.uuid4()),
 				},
 				signing_key,
 				algorithm=crypto.jwt_signature_alg_for_pem(signing_key),
@@ -381,15 +437,7 @@ async def identity_update_handle(request: web.Request):
 @routes.get("/xrpc/com.atproto.server.getSession")
 @authenticated
 async def server_get_session(request: web.Request):
-	return web.json_response(
-		{
-			"handle": get_db(request).handle_by_did(request["authed_did"]),
-			"did": request["authed_did"],
-			"email": "tfw_no@email.invalid",  # this and below are just here for testing lol
-			"emailConfirmed": True,
-			# "didDoc": {}, # iiuc this is only used for entryway usecase?
-		}
-	)
+	return web.json_response(session_info(request))
 
 
 def construct_app(

src/millipds/static_config.py

@@ -11,7 +11,7 @@
 GROUPNAME = "millipds-sock"
 
 # this gets bumped if we make breaking changes to the db schema
-MILLIPDS_DB_VERSION = 2
+MILLIPDS_DB_VERSION = 3
 
 ATPROTO_REPO_VERSION_3 = 3  # might get bumped if the atproto spec changes
 CAR_VERSION_1 = 1
@@ -29,3 +29,6 @@
 DID_CACHE_ERROR_TTL = 60 * 5  # 5 mins
 
 PLC_DIRECTORY_HOST = "https://plc.directory"
+
+ACCESS_EXP = 60 * 60 * 2  # 2 h
+REFRESH_EXP = 60 * 60 * 24 * 90  # 90 days