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swift/swift/common/middleware/s3api/acl_handlers.py

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# 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.
"""
------------
Acl Handlers
------------
Why do we need this
^^^^^^^^^^^^^^^^^^^
To make controller classes clean, we need these handlers.
It is really useful for customizing acl checking algorithms for
each controller.
Basic Information
^^^^^^^^^^^^^^^^^
BaseAclHandler wraps basic Acl handling.
(i.e. it will check acl from ACL_MAP by using HEAD)
How to extend
^^^^^^^^^^^^^
Make a handler with the name of the controller.
(e.g. BucketAclHandler is for BucketController)
It consists of method(s) for actual S3 method on controllers as follows.
Example::
class BucketAclHandler(BaseAclHandler):
def PUT:
<< put acl handling algorithms here for PUT bucket >>
.. note::
If the method DON'T need to recall _get_response in outside of
acl checking, the method have to return the response it needs at
the end of method.
"""
from swift.common.middleware.s3api.subresource import ACL, Owner, encode_acl
from swift.common.middleware.s3api.s3response import MissingSecurityHeader, \
MalformedACLError, UnexpectedContent, AccessDenied
from swift.common.middleware.s3api.etree import fromstring, XMLSyntaxError, \
DocumentInvalid
from swift.common.middleware.s3api.utils import MULTIUPLOAD_SUFFIX, \
sysmeta_header
def get_acl_handler(controller_name):
for base_klass in [BaseAclHandler, MultiUploadAclHandler]:
# pylint: disable-msg=E1101
for handler in base_klass.__subclasses__():
handler_suffix_len = len('AclHandler') \
if not handler.__name__ == 'S3AclHandler' else len('Handler')
if handler.__name__[:-handler_suffix_len] == controller_name:
return handler
return BaseAclHandler
class BaseAclHandler(object):
"""
BaseAclHandler: Handling ACL for basic requests mapped on ACL_MAP
"""
def __init__(self, req, logger, container=None, obj=None, headers=None):
self.req = req
self.container = req.container_name if container is None else container
self.obj = req.object_name if obj is None else obj
self.method = req.environ['REQUEST_METHOD']
self.user_id = self.req.user_id
self.headers = req.headers if headers is None else headers
self.logger = logger
def request_with(self, container, obj, headers):
return type(self)(self.req, self.logger,
container=container, obj=obj, headers=headers)
def handle_acl(self, app, method, container=None, obj=None, headers=None):
method = method or self.method
ah = self.request_with(container, obj, headers)
if hasattr(ah, method):
return getattr(ah, method)(app)
else:
return ah._handle_acl(app, method)
def _handle_acl(self, app, sw_method, container=None, obj=None,
permission=None, headers=None):
"""
General acl handling method.
This method expects to call Request._get_response() in outside of
this method so that this method returns response only when sw_method
is HEAD.
"""
container = self.container if container is None else container
obj = self.obj if obj is None else obj
sw_method = sw_method or self.req.environ['REQUEST_METHOD']
resource = 'object' if obj else 'container'
headers = self.headers if headers is None else headers
self.logger.debug(
'checking permission: %s %s %s %s' %
(container, obj, sw_method, dict(headers)))
if not container:
return
if not permission and (self.method, sw_method, resource) in ACL_MAP:
acl_check = ACL_MAP[(self.method, sw_method, resource)]
resource = acl_check.get('Resource') or resource
permission = acl_check['Permission']
if not permission:
self.logger.debug(
'%s %s %s %s' % (container, obj, sw_method, headers))
raise Exception('No permission to be checked exists')
if resource == 'object':
version_id = self.req.params.get('versionId')
if version_id is None:
query = {}
else:
query = {'version-id': version_id}
if self.req.method == 'HEAD':
# This HEAD for ACL is going to also be the definitive response
# to the client so we need to include client params. We don't
# do this for other client request methods because they may
# have invalid combinations of params and headers for a swift
# HEAD request.
part_number = self.req.params.get('partNumber')
if part_number is not None:
query['part-number'] = part_number
resp = self.req.get_acl_response(app, 'HEAD',
container, obj,
headers, query=query)
acl = resp.object_acl
elif resource == 'container':
resp = self.req.get_acl_response(app, 'HEAD',
container, '')
acl = resp.bucket_acl
try:
acl.check_permission(self.user_id, permission)
except Exception as e:
self.logger.debug(acl)
self.logger.debug('permission denined: %s %s %s' %
(e, self.user_id, permission))
raise
if sw_method == 'HEAD':
return resp
def get_acl(self, 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,
as_private=False)
if acl is None:
# Get acl from request body if possible.
if not body:
raise MissingSecurityHeader(missing_header_name='x-amz-acl')
try:
elem = fromstring(body, ACL.root_tag)
acl = ACL.from_elem(
elem, True, self.req.conf.allow_no_owner)
except(XMLSyntaxError, DocumentInvalid):
raise MalformedACLError()
except Exception as e:
self.logger.error(e)
raise
else:
if body:
# Specifying grant with both header and xml is not allowed.
raise UnexpectedContent()
return acl
class BucketAclHandler(BaseAclHandler):
"""
BucketAclHandler: Handler for BucketController
"""
def DELETE(self, app):
if self.container.endswith(MULTIUPLOAD_SUFFIX):
# anyways, delete multiupload container doesn't need acls
# because it depends on GET segment container result for
# cleanup
pass
else:
return self._handle_acl(app, 'DELETE')
def HEAD(self, app):
if self.method == 'DELETE':
return self._handle_acl(app, 'DELETE')
else:
return self._handle_acl(app, 'HEAD')
def GET(self, app):
if self.method == 'DELETE' and \
self.container.endswith(MULTIUPLOAD_SUFFIX):
pass
else:
return self._handle_acl(app, 'GET')
def PUT(self, app):
req_acl = ACL.from_headers(self.req.headers,
Owner(self.user_id, self.user_id))
if not self.req.environ.get('swift_owner'):
raise AccessDenied()
# To avoid overwriting the existing bucket's ACL, we send PUT
# request first before setting the ACL to make sure that the target
# container does not exist.
self.req.get_acl_response(app, 'PUT', self.container)
# update metadata
self.req.bucket_acl = req_acl
# FIXME If this request is failed, there is a possibility that the
# bucket which has no ACL is left.
return self.req.get_acl_response(app, 'POST')
class ObjectAclHandler(BaseAclHandler):
"""
ObjectAclHandler: Handler for ObjectController
"""
def HEAD(self, app):
# No check object permission needed at DELETE Object
if self.method != 'DELETE':
return self._handle_acl(app, 'HEAD')
def PUT(self, app):
b_resp = self._handle_acl(app, 'HEAD', obj='')
req_acl = ACL.from_headers(self.req.headers,
b_resp.bucket_acl.owner,
Owner(self.user_id, self.user_id))
self.req.object_acl = req_acl
class S3AclHandler(BaseAclHandler):
"""
S3AclHandler: Handler for S3AclController
"""
def HEAD(self, app):
self._handle_acl(app, 'HEAD', permission='READ_ACP')
def GET(self, app):
self._handle_acl(app, 'HEAD', permission='READ_ACP')
def PUT(self, app):
if self.req.is_object_request:
b_resp = self.req.get_acl_response(app, 'HEAD', obj='')
o_resp = self._handle_acl(app, 'HEAD', permission='WRITE_ACP')
req_acl = self.get_acl(self.req.headers,
self.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)
for g in req_acl.grants:
self.logger.debug(
'Grant %s %s permission on the object /%s/%s' %
(g.grantee, g.permission, self.req.container_name,
self.req.object_name))
self.req.object_acl = req_acl
else:
self._handle_acl(app, self.method)
def POST(self, app):
if self.req.is_bucket_request:
resp = self._handle_acl(app, 'HEAD', permission='WRITE_ACP')
req_acl = self.get_acl(self.req.headers,
self.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)
for g in req_acl.grants:
self.logger.debug(
'Grant %s %s permission on the bucket /%s' %
(g.grantee, g.permission, self.req.container_name))
self.req.bucket_acl = req_acl
else:
self._handle_acl(app, self.method)
class MultiObjectDeleteAclHandler(BaseAclHandler):
"""
MultiObjectDeleteAclHandler: Handler for MultiObjectDeleteController
"""
def HEAD(self, app):
# Only bucket write acl is required
if not self.obj:
return self._handle_acl(app, 'HEAD')
def DELETE(self, app):
# Only bucket write acl is required
pass
class MultiUploadAclHandler(BaseAclHandler):
"""
MultiUpload stuff requires acl checking just once for BASE container
so that MultiUploadAclHandler extends BaseAclHandler to check acl only
when the verb defined. We should define the verb as the first step to
request to backend Swift at incoming request.
Basic Rules:
- BASE container name is always w/o 'MULTIUPLOAD_SUFFIX'
- Any check timing is ok but we should check it as soon as possible.
========== ====== ============= ==========
Controller Verb CheckResource Permission
========== ====== ============= ==========
Part PUT Container WRITE
Uploads GET Container READ
Uploads POST Container WRITE
Upload GET Container READ
Upload DELETE Container WRITE
Upload POST Container WRITE
========== ====== ============= ==========
"""
def __init__(self, req, logger, **kwargs):
super(MultiUploadAclHandler, self).__init__(req, logger, **kwargs)
self.acl_checked = False
def handle_acl(self, app, method, container=None, obj=None, headers=None):
method = method or self.method
ah = self.request_with(container, obj, headers)
# MultiUpload stuffs don't need acl check basically.
if hasattr(ah, method):
return getattr(ah, method)(app)
def HEAD(self, app):
# For _check_upload_info
self._handle_acl(app, 'HEAD', self.container, '')
class PartAclHandler(MultiUploadAclHandler):
"""
PartAclHandler: Handler for PartController
"""
def __init__(self, req, logger, **kwargs):
# pylint: disable-msg=E1003
super(MultiUploadAclHandler, self).__init__(req, logger, **kwargs)
def HEAD(self, app):
if self.container.endswith(MULTIUPLOAD_SUFFIX):
# For _check_upload_info
container = self.container[:-len(MULTIUPLOAD_SUFFIX)]
self._handle_acl(app, 'HEAD', container, '')
else:
# For check_copy_source
return self._handle_acl(app, 'HEAD', self.container, self.obj)
class UploadsAclHandler(MultiUploadAclHandler):
"""
UploadsAclHandler: Handler for UploadsController
"""
def handle_acl(self, app, method, *args, **kwargs):
method = method or self.method
if hasattr(self, method):
return getattr(self, method)(app)
else:
pass
def GET(self, app):
# List Multipart Upload
self._handle_acl(app, 'GET', self.container, '')
def PUT(self, app):
if not self.acl_checked:
resp = self._handle_acl(app, 'HEAD', obj='')
req_acl = ACL.from_headers(self.req.headers,
resp.bucket_acl.owner,
Owner(self.user_id, self.user_id))
acl_headers = encode_acl('object', req_acl)
self.req.headers[sysmeta_header('object', 'tmpacl')] = \
acl_headers[sysmeta_header('object', 'acl')]
self.acl_checked = True
class UploadAclHandler(MultiUploadAclHandler):
"""
UploadAclHandler: Handler for UploadController
"""
def handle_acl(self, app, method, *args, **kwargs):
method = method or self.method
if hasattr(self, method):
return getattr(self, method)(app)
else:
pass
def HEAD(self, app):
# FIXME: GET HEAD case conflicts with GET service
method = 'GET' if self.method == 'GET' else 'HEAD'
self._handle_acl(app, method, self.container, '')
def PUT(self, app):
container = self.req.container_name + MULTIUPLOAD_SUFFIX
obj = '%s/%s' % (self.obj, self.req.params['uploadId'])
resp = self.req._get_response(app, 'HEAD', container, obj)
self.req.headers[sysmeta_header('object', 'acl')] = \
resp.sysmeta_headers.get(sysmeta_header('object', 'tmpacl'))
"""
ACL_MAP =
{
('<s3_method>', '<swift_method>', '<swift_resource>'):
{'Resource': '<check_resource>',
'Permission': '<check_permission>'},
...
}
s3_method: Method of S3 Request from user to s3api
swift_method: Method of Swift Request from s3api to swift
swift_resource: Resource of Swift Request from s3api to swift
check_resource: <container/object>
check_permission: <OWNER/READ/WRITE/READ_ACP/WRITE_ACP>
"""
ACL_MAP = {
# HEAD Bucket
('HEAD', 'HEAD', 'container'):
{'Permission': 'READ'},
# GET Service
('GET', 'HEAD', 'container'):
{'Permission': 'OWNER'},
# GET Bucket, List Parts, List Multipart Upload
('GET', 'GET', 'container'):
{'Permission': 'READ'},
# PUT Object, PUT Object Copy
('PUT', 'HEAD', 'container'):
{'Permission': 'WRITE'},
# DELETE Bucket
('DELETE', 'DELETE', 'container'):
{'Permission': 'OWNER'},
# HEAD Object
('HEAD', 'HEAD', 'object'):
{'Permission': 'READ'},
# GET Object
('GET', 'GET', 'object'):
{'Permission': 'READ'},
# PUT Object Copy, Upload Part Copy
('PUT', 'HEAD', 'object'):
{'Permission': 'READ'},
# Abort Multipart Upload
('DELETE', 'HEAD', 'container'):
{'Permission': 'WRITE'},
# Delete Object
('DELETE', 'DELETE', 'object'):
{'Resource': 'container',
'Permission': 'WRITE'},
# Complete Multipart Upload, DELETE Multiple Objects,
# Initiate Multipart Upload
('POST', 'HEAD', 'container'):
{'Permission': 'WRITE'},
# Versioning
('PUT', 'POST', 'container'):
{'Permission': 'WRITE'},
('DELETE', 'GET', 'container'):
{'Permission': 'WRITE'},
}
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