acl: add preliminary support for S3 ACL

Currently, Swift3 sets and retrieves Swift ACLs for S3 ACL requests.  However,
S3 ACL is too different from Swift ACL to implement the below reference.
  http://docs.aws.amazon.com/AmazonS3/latest/dev/S3_ACLs_UsingACLs.html
With this patch, Swift3 uses its own metadata for ACL
(e.g. X-Container-Sysmeta-Swift3-Acl) to achieve the best S3 compatibility.
This patch only embeds the S3 ACL into the Swift metadata.  The swift3
middleware does not use it for S3 requests yet; this will be addressed later.

Change-Id: I4522910b6b3a0066f24caa98727fdeb85837e42b

swift3/controllers/__init__.py

@@ -19,6 +19,7 @@ from swift3.controllers.bucket import BucketController
 from swift3.controllers.obj import ObjectController
 
 from swift3.controllers.acl import AclController
+from swift3.controllers.s3_acl import AclController as S3AclController
 from swift3.controllers.multi_delete import MultiObjectDeleteController
 from swift3.controllers.multi_upload import UploadController, \
     PartController, UploadsController
@@ -33,6 +34,7 @@ __all__ = [
     'ObjectController',
 
     'AclController',
+    'S3AclController',
     'MultiObjectDeleteController',
     'PartController',
     'UploadsController',

swift3/controllers/s3_acl.py

@@ -0,0 +1,128 @@
+# Copyright (c) 2014 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.
+
+from urllib import quote
+
+from swift3.controllers.base import Controller
+from swift3.response import HTTPOk, MissingSecurityHeader, \
+    UnexpectedContent, MalformedACLError
+from swift3.etree import fromstring, tostring, XMLSyntaxError, DocumentInvalid
+from swift3.subresource import ACL
+from swift3.utils import LOGGER
+
+
+def get_acl(headers, body, bucket_owner, object_owner=None):
+    """
+    Get ACL instance from S3 (e.g. x-amz-grant) headers or S3 acl xml body.
+    """
+    acl = ACL.from_headers(headers, bucket_owner, object_owner)
+
+    if acl is None:
+        # Get acl from request body if possible.
+        if not body:
+            msg = 'Your request was missing a required header'
+            raise MissingSecurityHeader(msg, missing_header_name='x-amz-acl')
+        try:
+            elem = fromstring(body, ACL.root_tag)
+            acl = ACL.from_elem(elem)
+        except(XMLSyntaxError, DocumentInvalid):
+            raise MalformedACLError()
+        except Exception as e:
+            LOGGER.error(e)
+            raise
+    else:
+        if body:
+            # Specifying grant with both header and xml is not allowed.
+            raise UnexpectedContent
+
+    return acl
+
+
+class AclController(Controller):
+    """
+    Handles the following APIs:
+
+     - GET Bucket acl
+     - PUT Bucket acl
+     - GET Object acl
+     - PUT Object acl
+
+    Those APIs are logged as ACL operations in the S3 server log.
+    """
+    def GET(self, req):
+        """
+        Handles GET Bucket acl and GET Object acl.
+        """
+        resp = req.get_response(self.app, 'HEAD')
+        if req.is_object_request:
+            acl = resp.object_acl
+        else:
+            acl = resp.bucket_acl
+
+        acl.check_permission(req.user_id, 'READ_ACP')
+
+        resp = HTTPOk()
+        resp.body = tostring(acl.elem())
+
+        return resp
+
+    def PUT(self, req):
+        """
+        Handles PUT Bucket acl and PUT Object acl.
+        """
+        if req.is_object_request:
+            b_resp = req.get_response(self.app, 'HEAD', obj='')
+            o_resp = req.get_response(self.app, 'HEAD')
+
+            req_acl = get_acl(req.headers, req.xml(ACL.max_xml_length),
+                              b_resp.bucket_acl.owner,
+                              o_resp.object_acl.owner)
+
+            # Don't change the owner of the resource by PUT acl request.
+            o_resp.object_acl.check_owner(req_acl.owner.id)
+            o_resp.object_acl.check_permission(req.user_id, 'WRITE_ACP')
+
+            for g in req_acl.grants:
+                LOGGER.debug('Grant %s %s permission on the object /%s/%s' %
+                             (g.grantee, g.permission, req.container_name,
+                              req.object_name))
+            req.object_acl = req_acl
+            headers = {}
+            src_path = '/%s/%s' % (req.container_name, req.object_name)
+
+            # object-sysmeta' can be updated by 'Copy' method,
+            # but can not be by 'POST' method.
+            # So headers['X-Copy-From'] for copy request is added here.
+            headers['X-Copy-From'] = quote(src_path)
+            headers['Content-Length'] = 0
+            req.get_response(self.app, 'PUT', headers=headers)
+        else:
+            resp = req.get_response(self.app, 'HEAD')
+
+            req_acl = get_acl(req.headers, req.xml(ACL.max_xml_length),
+                              resp.bucket_acl.owner)
+
+            # Don't change the owner of the resource by PUT acl request.
+            resp.bucket_acl.check_owner(req_acl.owner.id)
+            resp.bucket_acl.check_permission(req.user_id, 'WRITE_ACP')
+
+            for g in req_acl.grants:
+                LOGGER.debug('Grant %s %s permission on the bucket /%s' %
+                             (g.grantee, g.permission, req.container_name))
+
+            req.bucket_acl = req_acl
+            req.get_response(self.app, 'POST')
+
+        return HTTPOk()