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)

(cherry picked from commit 2285ee9)
(cherry picked from commit d4a09f25a186223c104f7480d78c599b14481746)

airflow/bin/cli.py

@@ -1326,21 +1326,64 @@ def scheduler(args):
 
 @cli_utils.action_logging
 def serve_logs(args):
-    print("Starting flask")
-    import flask
-    flask_app = flask.Flask(__name__)
-
-    @flask_app.route('/log/<path:filename>')
-    def serve_logs(filename):  # noqa
-        log = os.path.expanduser(conf.get('core', 'BASE_LOG_FOLDER'))
-        return flask.send_from_directory(
-            log,
-            filename,
-            mimetype="application/json",
-            as_attachment=False)
+    from flask import Flask, abort, request, send_from_directory
+    from itsdangerous import TimedJSONWebSignatureSerializer
+
+    def flask_app():  # noqa: D103
+        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(filename):  # noqa
+            log = os.path.expanduser(conf.get('core', 'BASE_LOG_FOLDER'))
+            return flask.send_from_directory(
+                log,
+                filename,
+                mimetype="application/json",
+                as_attachment=False)
+
+        return flask_app
+
+    app = flask_app()
 
     worker_log_server_port = int(conf.get('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)
 
 
 def _serve_logs(env, skip_serve_logs=False):

airflow/utils/log/file_task_handler.py

@@ -22,6 +22,7 @@
 from typing import Optional
 
 import requests
+from itsdangerous import TimedJSONWebSignatureSerializer
 
 from airflow.configuration import conf
 from airflow.configuration import AirflowConfigException
@@ -160,7 +161,17 @@ def _read(self, ti, try_number, metadata=None):
                 except (AirflowConfigException, ValueError):
                     pass
 
-                response = requests.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 = requests.get(
+                    url, timeout=timeout, headers={'Authorization': signer.dumps(log_relative_path)}
+                )
                 response.encoding = "utf-8"
 
                 # Check if the resource was properly fetched