# Copyright 2012 Google Inc. All Rights Reserved. # # 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 gslib.help_provider import HELP_NAME from gslib.help_provider import HELP_NAME_ALIASES from gslib.help_provider import HELP_ONE_LINE_SUMMARY from gslib.help_provider import HelpProvider from gslib.help_provider import HELP_TEXT from gslib.help_provider import HelpType from gslib.help_provider import HELP_TYPE _detailed_help_text = (""" OVERVIEW Access Control Lists (ACLs) allow you to control who can read and write your data, and who can read and write the ACLs themselves. If not specified at the time an object is uploaded (e.g., via the gsutil cp -a option), objects will be created with a default object ACL set on the bucket (see "gsutil help setdefacl"). You can replace the ACL on an object or bucket using the gsutil setacl command (see "gsutil help setacl"), or modify the existing ACL using the gsutil chacl command (see "gsutil help chacl"). BUCKET VS OBJECT ACLS In Google Cloud Storage, the bucket ACL works as follows: - Users granted READ access are allowed to list the bucket contents. - Users granted WRITE access are allowed READ access and also are allowed to write and delete objects in that bucket -- including overwriting previously written objects. - Users granted FULL_CONTROL access are allowed WRITE access and also are allowed to read and write the bucket's ACL. The object ACL works as follows: - Users granted READ access are allowed to read the object's data and metadata. - Users granted FULL_CONTROL access are allowed READ access and also are allowed to read and write the object's ACL. A couple of points are worth noting, that sometimes surprise users: 1. There is no WRITE access for objects; attempting to set an ACL with WRITE permission for an object will result in an error. 2. The bucket ACL plays no role in determining who can read objects; only the object ACL matters for that purpose. This is different from how things work in Linux file systems, where both the file and directory permission control file read access. It also means, for example, that someone with FULL_CONTROL over the bucket may not have read access to objects in the bucket. This is by design, and supports useful cases. For example, you might want to set up bucket ownership so that a small group of administrators have FULL_CONTROL on the bucket (with the ability to delete data to control storage costs), but not grant those users read access to the object data (which might be sensitive data that should only be accessed by a different specific group of users). CANNED ACLS The simplest way to set an ACL on a bucket or object is using a "canned ACL". The available canned ACLs are: project-private Gives permission to the project team based on their roles. Anyone who is part of the team has READ permission, and project owners and project editors have FULL_CONTROL permission. This is the default ACL for newly created buckets. This is also the default ACL for newly created objects unless the default object ACL for that bucket has been changed. For more details see "gsutil help projects". private Gives the requester (and only the requester) FULL_CONTROL permission for a bucket or object. public-read Gives the requester FULL_CONTROL permission and gives all users READ permission. When you apply this to an object, anyone on the Internet can read the object without authenticating. public-read-write Gives the requester FULL_CONTROL permission and gives all users READ and WRITE permission. This ACL applies only to buckets. authenticated-read Gives the requester FULL_CONTROL permission and gives all authenticated Google account holders READ permission. bucket-owner-read Gives the requester FULL_CONTROL permission and gives the bucket owner READ permission. This is used only with objects. bucket-owner-full-control Gives the requester FULL_CONTROL permission and gives the bucket owner FULL_CONTROL permission. This is used only with objects. ACL XML When you use a canned ACL, it is translated into an XML representation that can later be retrieved and edited to specify more fine-grained detail about who can read and write buckets and objects. By running the gsutil getacl command you can retrieve the ACL XML, and edit it to customize the permissions. As an example, if you create an object in a bucket that has no default object ACL set and then retrieve the ACL on the object, it will look something like this: 00b4903a9740e42c29800f53bd5a9a62a2f96eb3f64a4313a115df3f3a776bf7 00b4903a9740e42c29800f53bd5a9a62a2f96eb3f64a4313a115df3f3a776bf7 FULL_CONTROL 00b4903a977fd817e9da167bc81306489181a110456bb635f466d71cf90a0d51 FULL_CONTROL 00b4903a974898cc8fc309f2f2835308ba3d3df1b889d3fc7e33e187d52d8e71 READ The ACL consists of an Owner element and a collection of Entry elements, each of which specifies a Scope and a Permission. Scopes are the way you specify an individual or group of individuals, and Permissions specify what access they're permitted. This particular ACL grants FULL_CONTROL to two groups (which means members of those groups are allowed to read the object and read and write the ACL), and READ permission to a third group. The project groups are (in order) the owners group, editors group, and viewers group. The 64 digit hex identifiers used in this ACL are called canonical IDs, and are used to identify predefined groups associated with the project that owns the bucket. For more information about project groups, see "gsutil help projects". Here's an example of an ACL specified using the GroupByEmail and GroupByDomain scopes: FULL_CONTROL travel-companion-owners@googlegroups.com READ example.com This ACL grants members of an email group FULL_CONTROL, and grants READ access to any user in a domain (which must be a Google Apps for Business domain). By applying email group grants to a collection of objects you can edit access control for large numbers of objects at once via http://groups.google.com. That way, for example, you can easily and quickly change access to a group of company objects when employees join and leave your company (i.e., without having to individually change ACLs across potentially millions of objects). SHARING SCENARIOS For more detailed examples how to achieve various useful sharing use cases see https://developers.google.com/storage/docs/collaboration """) class CommandOptions(HelpProvider): """Additional help about Access Control Lists.""" help_spec = { # Name of command or auxiliary help info for which this help applies. HELP_NAME : 'acls', # List of help name aliases. HELP_NAME_ALIASES : ['acl', 'ACL', 'access control', 'access control list', 'authorization', 'canned', 'canned acl'], # Type of help: HELP_TYPE : HelpType.ADDITIONAL_HELP, # One line summary of this help. HELP_ONE_LINE_SUMMARY : 'Working with Access Control Lists', # The full help text. HELP_TEXT : _detailed_help_text, }