Added security to ISM

_im-plugin/ism/api.md

@@ -2,7 +2,7 @@
 layout: default
 title: ISM API
 parent: Index State Management
-nav_order: 5
+nav_order: 20
 ---
 
 # ISM API

_im-plugin/ism/security.md

@@ -0,0 +1,40 @@
+---
+layout: default
+title: ISM security
+nav_order: 10
+parent: Index State Management
+has_children: false
+---
+
+# ISM security
+
+Using the security plugin with index state management lets you limit non-admin users to certain actions. For example, you might want to set up your security such that a group of users can only read ISM policies, while others can create, delete, or change policies.
+
+All index state management data are protected as system indices, and only a super admin or an admin with a Transport Layer Security (TLS) certificate can access system indices. For more information, see [System indices]({{site.url}}{{site.baseurl}}/security-plugin/configuration/system-indices).
+
+## Basic permissions
+
+The security plugin comes with two built-in roles that cover most ISM use cases: `ism_read_access` and `ism_full_access`. For descriptions of each, see [Predefined roles]({{site.url}}{{site.baseurl}}/security-plugin/access-control/users-roles#predefined-roles).
+
+With security enabled, users not only need the correct index management permissions, but they also need permissions to relevant indices to execute [REST API]({{site.url}}{{site.baseurl}}/im-plugin/ism/api) calls. For example, if a user wants to use the REST API to attach a policy to an index named `system-logs`, they would need the necessary REST API permissions as well as access to `system-logs`.
+
+## (Advanced) Limit access by backend role
+
+You can use backend roles to configure fine-grained access to ISM policies and actions. For example, users of different departments in an organization might view different policies depending on what roles and permissions they are assigned.
+
+First, ensure your users have the appropriate [backend roles]({{site.url}}{{site.baseurl}}/security-plugin/access-control/index/). Backend roles usually come from an [LDAP server]({{site.url}}{{site.baseurl}}/security-plugin/configuration/ldap/) or [SAML provider]({{site.url}}{{site.baseurl}}/security-plugin/configuration/saml/). However, if you use the internal user database, you can use the REST API to [add them manually]({{site.url}}{{site.baseurl}}/security-plugin/access-control/api#create-user).
+
+Use the REST API to enable the following setting:
+
+```json
+PUT _cluster/settings
+{
+  "transient": {
+    "plugins.index_management.filter_by_backend_roles": "true"
+  }
+}
+```
+
+With security enabled, only users who share at least one backend role can see and execute the policies and actions relevant to their roles.
+
+For example, consider a scenario with three users: `John` and `Jill`, who have the backend role `helpdesk_staff`, and `Jane`, who has the backend role `phone_operator`. `John` wants to create a policy that performs a rollup job on an index named `airline_data`, so `John` would need a backend role that has permissions to access that index, create relevant policies, and execute relevant actions, and `Jill` would be able to access the same index, policy, and job. However, `Jane` cannot access or edit those resources or actions.

_security-plugin/access-control/users-roles.md

@@ -121,6 +121,8 @@ Role | Description
 `reports_full_access` | Grants full permissions to reports.
 `asynchronous_search_full_access` | Grants full permissions to all asynchronous search actions.
 `asynchronous_search_read_access` | Grants permissions to view asynchronous searches, but not to submit, modify, or delete async searches.
+`ism_read_access` | Grants users permissions to view policies and current index states, but they are unable to create, add, update, or remove policies.
+`ism_full_access` | Grants full permissions to all ISM actions.
 
 
 For more detailed summaries of the permissions for each role, reference their action groups against the descriptions in [Default action groups]({{site.url}}{{site.baseurl}}/security-plugin/access-control/default-action-groups/).