From d8d04ef43c90079d436b2e49617b4425ba39c28e Mon Sep 17 00:00:00 2001 From: Aymeric Ducroquetz Date: Tue, 25 Oct 2022 22:07:53 +0200 Subject: [PATCH] s3api: Prevent XXE injections Previously, clients could use XML external entities (XXEs) to read arbitrary files from proxy-servers and inject the content into the request. Since many S3 APIs reflect request content back to the user, this could be used to extract any secrets that the swift user could read, such as tempauth credentials, keymaster secrets, etc. Now, disable entity resolution -- any unknown entities will be replaced with an empty string. Without resolving the entities, the request is still processed. [CVE-2022-47950] Closes-Bug: #1998625 Co-Authored-By: Romain de Joux Change-Id: I84494123cfc85e234098c554ecd3e77981f8a096 (cherry picked from commit b8467e190f6fc67fd8fb6a8c5e32b2aa6a10fd8e) --- swift/common/middleware/s3api/etree.py | 2 +- test/functional/s3api/test_xxe_injection.py | 231 ++++++++++++++++++ .../middleware/s3api/test_multi_delete.py | 40 +++ 3 files changed, 272 insertions(+), 1 deletion(-) create mode 100644 test/functional/s3api/test_xxe_injection.py diff --git a/swift/common/middleware/s3api/etree.py b/swift/common/middleware/s3api/etree.py index 987b84a144..e16b753405 100644 --- a/swift/common/middleware/s3api/etree.py +++ b/swift/common/middleware/s3api/etree.py @@ -130,7 +130,7 @@ class _Element(lxml.etree.ElementBase): parser_lookup = lxml.etree.ElementDefaultClassLookup(element=_Element) -parser = lxml.etree.XMLParser() +parser = lxml.etree.XMLParser(resolve_entities=False, no_network=True) parser.set_element_class_lookup(parser_lookup) Element = parser.makeelement diff --git a/test/functional/s3api/test_xxe_injection.py b/test/functional/s3api/test_xxe_injection.py new file mode 100644 index 0000000000..d6cc4c7d1a --- /dev/null +++ b/test/functional/s3api/test_xxe_injection.py @@ -0,0 +1,231 @@ +#!/usr/bin/env python +# Copyright (c) 2022 OpenStack Foundation +# +# Licensed 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. + +import requests + +import botocore + +import test.functional as tf +from test.functional.s3api import S3ApiBaseBoto3 + + +def setUpModule(): + tf.setup_package() + + +def tearDownModule(): + tf.teardown_package() + + +class TestS3ApiXxeInjection(S3ApiBaseBoto3): + + def setUp(self): + super(TestS3ApiXxeInjection, self).setUp() + self.bucket = 'test-s3api-xxe-injection' + + def _create_bucket(self, **kwargs): + resp = self.conn.create_bucket(Bucket=self.bucket, **kwargs) + response_metadata = resp.pop('ResponseMetadata', {}) + self.assertEqual(200, response_metadata.get('HTTPStatusCode')) + + @staticmethod + def _clear_data(request, **_kwargs): + request.data = b'' + + def _presign_url(self, method, key=None, **kwargs): + params = { + 'Bucket': self.bucket + } + if key: + params['Key'] = key + params.update(kwargs) + try: + # https://github.com/boto/boto3/issues/2192 + self.conn.meta.events.register( + 'before-sign.s3.*', self._clear_data) + return self.conn.generate_presigned_url( + method, Params=params, ExpiresIn=60) + finally: + self.conn.meta.events.unregister( + 'before-sign.s3.*', self._clear_data) + + def test_put_bucket_acl(self): + if not tf.cluster_info['s3api'].get('s3_acl'): + self.skipTest('s3_acl must be enabled') + + self._create_bucket() + + url = self._presign_url('put_bucket_acl') + resp = requests.put(url, data=""" + ]> + + + test:tester + test:tester + + + + + name&xxe; + id&xxe; + + WRITE + + + +""") # noqa: E501 + self.assertEqual(200, resp.status_code) + self.assertNotIn(b'xxe', resp.content) + self.assertNotIn(b'[swift-hash]', resp.content) + + acl = self.conn.get_bucket_acl(Bucket=self.bucket) + response_metadata = acl.pop('ResponseMetadata', {}) + self.assertEqual(200, response_metadata.get('HTTPStatusCode')) + self.assertDictEqual({ + 'Owner': { + 'DisplayName': 'test:tester', + 'ID': 'test:tester' + }, + 'Grants': [ + { + 'Grantee': { + 'DisplayName': 'id', + 'ID': 'id', + 'Type': 'CanonicalUser' + }, + 'Permission': 'WRITE' + } + ] + }, acl) + + def test_create_bucket(self): + url = self._presign_url('create_bucket') + resp = requests.put(url, data=""" + ]> + + &xxe; + +""") # noqa: E501 + self.assertEqual(400, resp.status_code) + self.assertNotIn(b'xxe', resp.content) + self.assertNotIn(b'[swift-hash]', resp.content) + + self.assertRaisesRegexp( + botocore.exceptions.ClientError, 'Not Found', + self.conn.head_bucket, Bucket=self.bucket) + + def test_delete_objects(self): + self._create_bucket() + + url = self._presign_url( + 'delete_objects', + Delete={ + 'Objects': [ + { + 'Key': 'string', + 'VersionId': 'string' + } + ] + }) + body = """ + ]> + + + &xxe; + + +""" + body = body.encode('utf-8') + resp = requests.post(url, data=body) + self.assertEqual(400, resp.status_code, resp.content) + self.assertNotIn(b'xxe', resp.content) + self.assertNotIn(b'[swift-hash]', resp.content) + + def test_complete_multipart_upload(self): + self._create_bucket() + + resp = self.conn.create_multipart_upload( + Bucket=self.bucket, Key='test') + response_metadata = resp.pop('ResponseMetadata', {}) + self.assertEqual(200, response_metadata.get('HTTPStatusCode')) + uploadid = resp.get('UploadId') + + try: + url = self._presign_url( + 'complete_multipart_upload', + Key='key', + MultipartUpload={ + 'Parts': [ + { + 'ETag': 'string', + 'PartNumber': 1 + } + ], + }, + UploadId=uploadid) + resp = requests.post(url, data=""" + ]> + + + "{uploadid}" + &xxe; + + +""") # noqa: E501 + self.assertEqual(404, resp.status_code) + self.assertNotIn(b'xxe', resp.content) + self.assertNotIn(b'[swift-hash]', resp.content) + + resp = requests.post(url, data=""" + ]> + + + "&xxe;" + 1 + + +""") # noqa: E501 + self.assertEqual(404, resp.status_code) + self.assertNotIn(b'xxe', resp.content) + self.assertNotIn(b'[swift-hash]', resp.content) + finally: + resp = self.conn.abort_multipart_upload( + Bucket=self.bucket, Key='test', UploadId=uploadid) + response_metadata = resp.pop('ResponseMetadata', {}) + self.assertEqual(204, response_metadata.get('HTTPStatusCode')) + + def test_put_bucket_versioning(self): + self._create_bucket() + + url = self._presign_url( + 'put_bucket_versioning', + VersioningConfiguration={ + 'Status': 'Enabled' + }) + resp = requests.put(url, data=""" + ]> + + &xxe; + +""") # noqa: E501 + self.assertEqual(400, resp.status_code) + self.assertNotIn(b'xxe', resp.content) + self.assertNotIn(b'[swift-hash]', resp.content) + + versioning = self.conn.get_bucket_versioning(Bucket=self.bucket) + response_metadata = versioning.pop('ResponseMetadata', {}) + self.assertEqual(200, response_metadata.get('HTTPStatusCode')) + self.assertDictEqual({}, versioning) diff --git a/test/unit/common/middleware/s3api/test_multi_delete.py b/test/unit/common/middleware/s3api/test_multi_delete.py index 3be972d634..626a554056 100644 --- a/test/unit/common/middleware/s3api/test_multi_delete.py +++ b/test/unit/common/middleware/s3api/test_multi_delete.py @@ -521,6 +521,7 @@ class TestS3ApiMultiDelete(S3ApiTestCase): body=body) status, headers, body = self.call_s3api(req) self.assertEqual(status.split()[0], '200') + self.assertIn(b'Key1Server Error', body) def _test_object_multi_DELETE(self, account): self.keys = ['Key1', 'Key2'] @@ -578,6 +579,45 @@ class TestS3ApiMultiDelete(S3ApiTestCase): elem = fromstring(body) self.assertEqual(len(elem.findall('Deleted')), len(self.keys)) + def test_object_multi_DELETE_with_system_entity(self): + self.keys = ['Key1', 'Key2'] + self.swift.register( + 'DELETE', '/v1/AUTH_test/bucket/%s' % self.keys[0], + swob.HTTPNotFound, {}, None) + self.swift.register( + 'DELETE', '/v1/AUTH_test/bucket/%s' % self.keys[1], + swob.HTTPNoContent, {}, None) + + elem = Element('Delete') + for key in self.keys: + obj = SubElement(elem, 'Object') + SubElement(obj, 'Key').text = key + body = tostring(elem, use_s3ns=False) + body = body.replace( + b'?>\n', + b'?>\n ]>\n', + ).replace(b'>Key1<', b'>Key1&ent;<') + content_md5 = ( + base64.b64encode(md5(body, usedforsecurity=False).digest()) + .strip()) + + req = Request.blank('/bucket?delete', + environ={'REQUEST_METHOD': 'POST'}, + headers={ + 'Authorization': 'AWS test:full_control:hmac', + 'Date': self.get_date_header(), + 'Content-MD5': content_md5}, + body=body) + req.date = datetime.now() + req.content_type = 'text/plain' + + status, headers, body = self.call_s3api(req) + self.assertEqual(status, '200 OK', body) + self.assertIn(b'Key2', body) + self.assertNotIn(b'root:/root', body) + self.assertIn(b'Key1', body) + def _test_no_body(self, use_content_length=False, use_transfer_encoding=False, string_to_md5=b''): content_md5 = (base64.b64encode(