Document-level security (DLS)

Document-level security lets you restrict a role to a subset of documents in an index. The easiest way to get started with document- and field-level security is open OpenSearch Dashboards and choose Security. Then choose Roles, create a new role, and review the Index permissions section.

Simple roles

Document-level security uses the OpenSearch query DSL to define which documents a role grants access to. In OpenSearch Dashboards, choose an index pattern and provide a query in the Document level security section:

{
  "bool": {
    "must": {
      "match": {
        "genres": "Comedy"
      }
    }
  }
}

This query specifies that for the role to have access to a document, its genres field must include Comedy.

A typical request to the _search API includes { "query": { ... } } around the query, but in this case, you only need to specify the query itself.

In the REST API, you provide the query as a string, so you must escape your quotes. This role allows a user to read any document in any index with the field public set to true:

PUT _plugins/_security/api/roles/public_data
{
  "cluster_permissions": [
    "*"
  ],
  "index_permissions": [{
    "index_patterns": [
      "pub*"
    ],
    "dls": "{\"term\": { \"public\": true}}",
    "allowed_actions": [
      "read"
    ]
  }]
}

These queries can be as complex as you want, but we recommend keeping them simple to minimize the performance impact that the document-level security feature has on the cluster.

Parameter substitution

A number of variables exist that you can use to enforce rules based on the properties of a user. For example, ${user.name} is replaced with the name of the current user.

This rule allows a user to read any document where the username is a value of the readable_by field:

PUT _plugins/_security/api/roles/user_data
{
  "cluster_permissions": [
    "*"
  ],
  "index_permissions": [{
    "index_patterns": [
      "pub*"
    ],
    "dls": "{\"term\": { \"readable_by\": \"${user.name}\"}}",
    "allowed_actions": [
      "read"
    ]
  }]
}

This table lists substitutions.

Attribute-based security

You can use roles and parameter substitution with the terms_set query to enable attribute-based security.

Note that the security_attributes of the index need to be of type keyword.

User definition

PUT _plugins/_security/api/internalusers/user1
{
  "password": "asdf",
  "backend_roles": ["abac"],
  "attributes": {
    "permissions": "\"att1\", \"att2\", \"att3\""
  }
}

Role definition

PUT _plugins/_security/api/roles/abac
{
  "index_permissions": [{
    "index_patterns": [
      "*"
    ],
    "dls": "{\"terms_set\": {\"security_attributes\": {\"terms\": [${attr.internal.permissions}], \"minimum_should_match_script\": {\"source\": \"doc['security_attributes'].length\"}}}}",
    "allowed_actions": [
      "read"
    ]
  }]
}

Use term-level lookup queries (TLQs) with DLS

You can perform term-level lookup queries (TLQs) with document-level security (DLS) using either of two modes: adaptive or filter level. The default mode is adaptive, where OpenSearch automatically switches between Lucene-level or filter-level mode depending on whether or not there is a TLQ. DLS queries without TLQs are executed in Lucene-level mode, whereas DLS queries with TLQs are executed in filter-level mode.

By default, the security plugin detects if a DLS query contains a TLQ or not and chooses the appropriate mode automatically at runtime.

To learn more about OpenSearch queries, see Term-level queries.

How to set the DLS evaluation mode in opensearch.yml

By default, the DLS evaluation mode is set to adaptive. You can also explicitly set the mode in opensearch.yml with the plugins.security.dls.mode setting. Add a line to opensearch.yml with the desired evaluation mode. For example, to set it to filter level, add this line:

plugins.security.dls.mode: filter-level

DLS evaluation modes