Introduce common personas for secure RBAC

This commit lays down some common personas we're trying to introduce
across OpenStack services. Later commits will use these personas in
ironic's existing policies.

This will help use improve the security posture of OpenStack as a whole
and provide a more consistent experience operators and end users.

Change-Id: I2960d0f808949582dc964f4f5688a462d397de9e

ironic/common/policy.py

@@ -37,6 +37,55 @@ LOG = log.getLogger(__name__)
 DEFAULT_POLICY_FILE = 'policy.yaml'
 opts.set_defaults(cfg.CONF, DEFAULT_POLICY_FILE)
 
+# Generic policy check string for system administrators. These are the people
+# who need the highest level of authorization to operate the deployment.
+# They're allowed to create, read, update, or delete any system-specific
+# resource. They can also operate on project-specific resources where
+# applicable (e.g., cleaning up baremetal hosts)
+SYSTEM_ADMIN = 'role:admin and system_scope:all'
+
+# Generic policy check string for system users who don't require all the
+# authorization that system administrators typically have. This persona, or
+# check string, typically isn't used by default, but it's existence it useful
+# in the event a deployment wants to offload some administrative action from
+# system administrator to system members
+SYSTEM_MEMBER = 'role:member and system_scope:all'
+
+# Generic policy check string for read-only access to system-level resources.
+# This persona is useful for someone who needs access for auditing or even
+# support. These uses are also able to view project-specific resources where
+# applicable (e.g., listing all volumes in the deployment, regardless of the
+# project they belong to).
+SYSTEM_READER = 'role:reader and system_scope:all'
+
+# This check string is reserved for actions that require the highest level of
+# authorization on a project or resources within the project (e.g., setting the
+# default volume type for a project)
+PROJECT_ADMIN = ('role:admin and '
+                 'project_id:%(node.owner)s')
+# This check string is the primary use case for typical end-users, who are
+# working with resources that belong to a project (e.g., creating volumes and
+# backups).
+PROJECT_MEMBER = ('role:member and '
+                  '(project_id:%(node.owner)s or project_id:%(node.lessee)s)')
+
+# This check string should only be used to protect read-only project-specific
+# resources. It should not be used to protect APIs that make writable changes
+# (e.g., updating a volume or deleting a backup).
+PROJECT_READER = ('role:reader and '
+                  '(project_id:%(node.owner)s or project_id:%(node.lessee)s)')
+
+# The following are common composite check strings that are useful for
+# protecting APIs designed to operate with multiple scopes (e.g., a system
+# administrator should be able to delete any baremetal host in the deployment,
+# a project member should only be able to delete hosts in their project).
+SYSTEM_ADMIN_OR_PROJECT_MEMBER = (
+    '(' + SYSTEM_ADMIN + ') or (' + PROJECT_MEMBER + ')'
+)
+SYSTEM_OR_PROJECT_READER = (
+    '(' + SYSTEM_READER + ') or (' + PROJECT_READER + ')'
+)
+
 default_policies = [
     # Legacy setting, don't remove. Likely to be overridden by operators who
     # forget to update their policy.json configuration file.
@@ -62,6 +111,7 @@ default_policies = [
                        '!',
                        description='Show or mask secrets within instance information in API responses'),  # noqa
     # Roles likely to be overridden by operator
+    # TODO(TheJulia): Lets nuke demo from high orbit.
     policy.RuleDefault('is_member',
                        '(project_domain_id:default or project_domain_id:None) and (project_name:demo or project_name:baremetal)',  # noqa
                        description='May be used to restrict access to specific projects'),  # noqa