Only allow webserver to request from the worker log server (apache#16754

)


Logs _shouldn't_ contain any sensitive info, but they often do by
mistake. As an extra level of protection we shouldn't allow anything
other than the webserver to access the logs.

(We can't change the bind IP form 0.0.0.0 as for it to be useful it
needs to be accessed from different hosts -- i.e. the webserver will
almost always be on a different node)

airflow/utils/log/file_task_handler.py

@@ -22,6 +22,7 @@
 from typing import TYPE_CHECKING, Optional
 
 import httpx
+from itsdangerous import TimedJSONWebSignatureSerializer
 
 from airflow.configuration import AirflowConfigException, conf
 from airflow.utils.helpers import parse_template_string
@@ -172,7 +173,17 @@ def _read(self, ti, try_number, metadata=None):
                 except (AirflowConfigException, ValueError):
                     pass
 
-                response = httpx.get(url, timeout=timeout)
+                signer = TimedJSONWebSignatureSerializer(
+                    secret_key=conf.get('webserver', 'secret_key'),
+                    algorithm_name='HS512',
+                    expires_in=conf.getint('webserver', 'log_request_clock_grace', fallback=30),
+                    # This isn't really a "salt", more of a signing context
+                    salt='task-instance-logs',
+                )
+
+                response = httpx.get(
+                    url, timeout=timeout, headers={'Authorization': signer.dumps(log_relative_path)}
+                )
                 response.encoding = "utf-8"
 
                 # Check if the resource was properly fetched

airflow/utils/serve_logs.py

@@ -17,25 +17,66 @@
 
 """Serve logs process"""
 import os
+import time
 
-import flask
+from flask import Flask, abort, request, send_from_directory
+from itsdangerous import TimedJSONWebSignatureSerializer
 from setproctitle import setproctitle
 
 from airflow.configuration import conf
 
 
-def serve_logs():
-    """Serves logs generated by Worker"""
-    print("Starting flask")
-    flask_app = flask.Flask(__name__)
-    setproctitle("airflow serve-logs")
+def flask_app():
+    flask_app = Flask(__name__)
+    max_request_age = conf.getint('webserver', 'log_request_clock_grace', fallback=30)
+    log_directory = os.path.expanduser(conf.get('logging', 'BASE_LOG_FOLDER'))
+
+    signer = TimedJSONWebSignatureSerializer(
+        secret_key=conf.get('webserver', 'secret_key'),
+        algorithm_name='HS512',
+        expires_in=max_request_age,
+        # This isn't really a "salt", more of a signing context
+        salt='task-instance-logs',
+    )
+
+    # Prevent direct access to the logs port
+    @flask_app.before_request
+    def validate_pre_signed_url():
+        try:
+            auth = request.headers['Authorization']
+
+            # We don't actually care about the payload, just that the signature
+            # was valid and the `exp` claim is correct
+            filename, headers = signer.loads(auth, return_header=True)
+
+            issued_at = int(headers['iat'])
+            expires_at = int(headers['exp'])
+        except Exception:
+            abort(403)
+
+        if filename != request.view_args['filename']:
+            abort(403)
+
+        # Validate the `iat` and `exp` are within `max_request_age` of now.
+        now = int(time.time())
+        if abs(now - issued_at) > max_request_age:
+            abort(403)
+        if abs(now - expires_at) > max_request_age:
+            abort(403)
+        if issued_at > expires_at or expires_at - issued_at > max_request_age:
+            abort(403)
 
     @flask_app.route('/log/<path:filename>')
     def serve_logs_view(filename):
-        log_directory = os.path.expanduser(conf.get('logging', 'BASE_LOG_FOLDER'))
-        return flask.send_from_directory(
-            log_directory, filename, mimetype="application/json", as_attachment=False
-        )
+        return send_from_directory(log_directory, filename, mimetype="application/json", as_attachment=False)
+
+    return flask_app
+
+
+def serve_logs():
+    """Serves logs generated by Worker"""
+    setproctitle("airflow serve-logs")
+    app = flask_app()
 
     worker_log_server_port = conf.getint('celery', 'WORKER_LOG_SERVER_PORT')
-    flask_app.run(host='0.0.0.0', port=worker_log_server_port)
+    app.run(host='0.0.0.0', port=worker_log_server_port)

tests/utils/test_serve_logs.py

@@ -14,33 +14,97 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-import os
-import unittest
-from multiprocessing import Process
-from os.path import basename
-from tempfile import NamedTemporaryFile
-from time import sleep
+from typing import TYPE_CHECKING
 
 import pytest
-import requests
+from itsdangerous import TimedJSONWebSignatureSerializer
 
 from airflow.configuration import conf
-from airflow.utils.serve_logs import serve_logs
+from airflow.utils.serve_logs import flask_app
+from tests.test_utils.config import conf_vars
+
+if TYPE_CHECKING:
+    from flask.testing import FlaskClient
 
 LOG_DATA = "Airflow log data" * 20
 
 
-@pytest.mark.quarantined
-class TestServeLogs(unittest.TestCase):
-    def test_should_serve_file(self):
-        log_dir = os.path.expanduser(conf.get('logging', 'BASE_LOG_FOLDER'))
-        log_port = conf.get('celery', 'WORKER_LOG_SERVER_PORT')
-        with NamedTemporaryFile(dir=log_dir) as f:
-            f.write(LOG_DATA.encode())
-            f.flush()
-            sub_proc = Process(target=serve_logs)
-            sub_proc.start()
-            sleep(1)
-            log_url = f"http://localhost:{log_port}/log/{basename(f.name)}"
-            assert LOG_DATA == requests.get(log_url).content.decode()
-            sub_proc.terminate()
+@pytest.fixture
+def client(tmpdir):
+    with conf_vars({('logging', 'base_log_folder'): str(tmpdir)}):
+        app = flask_app()
+
+        yield app.test_client()
+
+
+@pytest.fixture
+def sample_log(tmpdir):
+    f = tmpdir / 'sample.log'
+    f.write(LOG_DATA.encode())
+
+    return f
+
+
+@pytest.fixture
+def signer():
+    return TimedJSONWebSignatureSerializer(
+        secret_key=conf.get('webserver', 'secret_key'),
+        algorithm_name='HS512',
+        expires_in=30,
+        # This isn't really a "salt", more of a signing context
+        salt='task-instance-logs',
+    )
+
+
+@pytest.mark.usefixtures('sample_log')
+class TestServeLogs:
+    def test_forbidden_no_auth(self, client: "FlaskClient"):
+        assert 403 == client.get('/log/sample.log').status_code
+
+    def test_should_serve_file(self, client: "FlaskClient", signer):
+        assert (
+            LOG_DATA
+            == client.get(
+                '/log/sample.log',
+                headers={
+                    'Authorization': signer.dumps('sample.log'),
+                },
+            ).data.decode()
+        )
+
+    def test_forbidden_too_long_validity(self, client: "FlaskClient", signer):
+        signer.expires_in = 3600
+        assert (
+            403
+            == client.get(
+                '/log/sample.log',
+                headers={
+                    'Authorization': signer.dumps('sample.log'),
+                },
+            ).status_code
+        )
+
+    def test_forbidden_expired(self, client: "FlaskClient", signer):
+        # Fake the time we think we are
+        signer.now = lambda: 0
+        assert (
+            403
+            == client.get(
+                '/log/sample.log',
+                headers={
+                    'Authorization': signer.dumps('sample.log'),
+                },
+            ).status_code
+        )
+
+    def test_wrong_context(self, client: "FlaskClient", signer):
+        signer.salt = None
+        assert (
+            403
+            == client.get(
+                '/log/sample.log',
+                headers={
+                    'Authorization': signer.dumps('sample.log'),
+                },
+            ).status_code
+        )