wiki:AccessControl
Last modified 4 years ago Last modified on 02/22/10 11:57:33

Access control

Summary of Design

Package and Group Authorization

Each package or group has a list of users and their roles. These are set from the 'authorization' tab of a package/group (assuming you are an 'admin' for the particular package/group).

Example 1: Package 'paper-industry-stats':

  • David Brent is an 'admin'
  • Gareth Keenan is an 'editor'
  • Logged-in is an 'reader' (This is a special user, meaning 'anyone who is logged in')
  • Visitor is an 'reader' (Another special user, meaning 'anyone')

i.e. Gareth and David can edit this package, but only Gareth can assign roles (privileges) to new team members. Anyone can see (read) the package.

Example 2: The current default for new packages is:

  • the user who creates it is an 'admin'
  • Visitor and Logged-in are both an 'editor' and 'reader'

Roles

Each role has a list of action priviledges for a package or group.

Currently:

  • An 'admin' can do anything (includes package/group deletion & changing user roles)
  • An 'editor' can edit or read
  • A 'reader' can read

Roles are only editable via the raw Model interface at /admin/ (sysadmin-only).


Design Notes

When a new package is created you as the creator automatically become admin for it and you can assign which other users have write or read access. NB: by default any user (including someone who is not-logged-in) will be able to read and write.

There are "system" level admins for CKAN who may alter permissions on any package.

Use Cases

  • A user means someone who is logged in.
  • A visitor means someone who is not logged in.
  • An entity is the subject of a permission (either a user or a pseudo-user)
  • There are roles named: Admin, Reader, Writer
  1. A visitor visits a package page and reads the content
  1. A visitor visits a package page and edits the package

3+4: Ditto for a user

  1. On package creation if done by a user and not a visitor then user is made the 'admin'
  1. An admin of a package adds a user as an admin
  1. An admin of a package removes a user as an admin
  1. Ditto for admin re. editor
  1. Ditto for admin re. reader
  1. We wish to be able assign roles to 2 specific entire groups in addition to specific users: 'visitor', 'users'. These will be termed pseudo-users as we do not have AC 'groups' as such.
  1. The sysadmin alters the assignment of entities to roles for any package
  1. A visitor goes to a package where the editor role does not include 'visitor' pseudo-user. They are unable to edit the package.
  1. Ditto for user where users pseudo-user does not have editor role and user is not an editor for the package

14+15: Ditto for above re reader role ...

16: Try to edit over REST interface a package for which 'visitor' has Editor role, but no API is supplied. Not allowed.

Optional

  • Support for access-related groups
  • Support for blacklisting

Implementation

      Context
Entity ----> Role

E.g. a user is assigned to a given role for a particular package.

    Context
Role ----> Action/Permission/Capability (on an Object e.g. a Package)

Package level:

  • Package Roles: admin, editor, reader
  • Entities: [email protected]… (user), pseudo-users 'visitor'
  • Assignment of entities to roles in a given context (the package)
  • Roles give permissions (in a given context)
    • admin -> update assignment to roles, delete package, plus editor
    • editor -> update package plus reader
    • reader -> read package

System level permissions:

  • Roles:??
  • create package
  • update assignment of system level role

Determining permissions

def is_allowed(name, action, context=None):
    user = locate_user(name)
    if not user:
        # they are a visitor ...
   
    if context is None:
        context = 'system'
    contextroles = locate_roles(user, context)
    if context != 'system':
        sysrole =
        if sysrole = 'sysadmin':
            # can do anything ...
            return True
    for role in contextroles:
        # assuming 'ORing' of permissions
        if role.is_allowed(action)
            return True
    if visitor:
        visitor_role = locate_roles(visitor, context)
        # check again
    return False

Initializing Permissions for a Package

when we create a package: visitor is given reader and editor roles automatically (ditto for user)

DB Sketch

role enum: admin, editor, reader
action enum: read, edit, delete (to deleted state), purge (destroy), edit-permissions, create
context enum: system, package, tag, group, revision

shortcuts:
sysadmin can do everything on anything
? admin can do everything on the given object


role-action table

role | context | action
admin| package | update
admin| package | update-permissions
admin| package | read
editor| package | update
editor| package | read

user-role table

username.id | context | objectid    | role
xyz.id      | package | geonames.id | admin
rgrp.id     | system  |             | admin
visitor.id  | package | geonames.id | editor 
visitor.id  | package | geonames.id | reader