Built-in System Access Control#

A system access control plugin enforces authorization at a global level, before any connector level authorization. You can either use one of the built-in plugins in Presto or provide your own by following the guidelines in System Access Control. Presto offers three built-in plugins:

Plugin Name	Description
`allow-all` (default value)	All operations are permitted.
`read-only`	Operations that read data or metadata are permitted, but none of the operations that write data or metadata are allowed. See Read Only System Access Control for details.
`file`	Authorization checks are enforced using a config file specified by the configuration property `security.config-file`. See File Based System Access Control for details.

Allow All System Access Control#

All operations are permitted under this plugin. This plugin is enabled by default.

Read Only System Access Control#

Under this plugin, you are allowed to execute any operation that reads data or metadata, such as SELECT or SHOW. Setting system level or catalog level session properties is also permitted. However, any operation that writes data or metadata, such as CREATE, INSERT or DELETE, is prohibited. To use this plugin, add an etc/access-control.properties file with the following contents:

access-control.name=read-only

File Based System Access Control#

This plugin allows you to specify access control rules in a file. To use this plugin, add an etc/access-control.properties file containing two required properties: access-control.name, which must be equal to file, and security.config-file, which must be equal to the location of the config file. For example, if a config file named rules.json resides in etc, add an etc/access-control.properties with the following contents:

access-control.name=file
security.config-file=etc/rules.json

The config file is specified in JSON format.

It contains the rules defining which catalog can be accessed by which user (see Catalog Rules below).
The schema access rules defining which schema can be accessed by which user (see Schema Rules below).
The principal rules specifying what principals can identify as what users (see Principal Rules below).

This plugin currently supports catalog access control rules, schema access control rules and principal rules. If you want to limit access on a system level in any other way, you must implement a custom SystemAccessControl plugin (see System Access Control).

Refresh#

By default, when a change is made to the security.config-file, Presto must be restarted to load the changes. There is an optional property to refresh the properties without requiring a Presto restart. The refresh period is specified in the etc/access-control.properties:

security.refresh-period=1s

Catalog Rules#

These rules govern the catalogs particular users can access. The user is granted access to a catalog based on the first matching rule read from top to bottom. If no rule matches, access is denied. Each rule is composed of the following fields:

user (optional): regex to match against user name. Defaults to .*.
catalog (optional): regex to match against catalog name. Defaults to .*.
allow (required): string indicating whether a user has access to the catalog. This value can be all, read-only or none, and defaults to none. Setting this value to read-only has the same behavior as the read-only system access control plugin.

Note

By default, all users have access to the system catalog. You can override this behavior by adding a rule.

Boolean true and false are also supported as legacy values for allow, to support backwards compatibility. true maps to all, and false maps to none.

For example, if you want to allow only the user admin to access the mysql and the system catalog, allow all users to access the hive catalog, allow the user alice read-only access to the postgresql catalog, and deny all other access, you can use the following rules:

{
  "catalogs": [
    {
      "user": "admin",
      "catalog": "(mysql|system)",
      "allow": "all"
    },
    {
      "catalog": "hive",
      "allow": "all"
    },
    {
      "user": "alice",
      "catalog": "postgresql",
      "allow": "read-only"
    },
    {
      "catalog": "system",
      "allow": "none"
    }
  ]
}

Schema Rules#

These rules allow you to grant ownership of a schema. Having ownership of an schema allows users to execute DROP SCHEMA, ALTER SCHEMA and CREATE SCHEMA. The user is granted ownership of a schema, based on the first matching rule read from top to bottom. If no rule matches, ownership is not granted. Each rule is composed of the following fields:

user (optional): regex to match against user name. Defaults to .*.
schema (optional): regex to match against schema name. Defaults to .*.
owner (required): boolean indicating whether the user is to be considered an owner of the schema. Defaults to false.

For example, to provide ownership of all schemas to user admin, treat all users as owners of default schema and prevent user guest from ownership of any schema, you can use the following rules:

{
  "catalogs": [
    {
      "allow": true
    }
  ],
  "schemas": [
    {
      "user": "admin",
      "schema": ".*",
      "owner": true
    },
    {
      "user": "guest",
      "owner": false
    },
    {
      "schema": "default",
      "owner": true
    }
  ]
}

Principal Rules#

These rules serve to enforce a specific matching between a principal and a specified user name. The principal is granted authorization as a user based on the first matching rule read from top to bottom. If no rules are specified, no checks will be performed. If no rule matches, user authorization is denied. Each rule is composed of the following fields:

principal (required): regex to match and group against principal.
user (optional): regex to match against user name. If matched, it will grant or deny the authorization based on the value of allow.
principal_to_user (optional): replacement string to substitute against principal. If the result of the substitution is same as the user name, it will grant or deny the authorization based on the value of allow.
allow (required): boolean indicating whether a principal can be authorized as a user.

Note

You would at least specify one criterion in a principal rule. If you specify both criteria in a principal rule, it will return the desired conclusion when either of criteria is satisfied.

The following implements an exact matching of the full principal name for LDAP and Kerberos authentication:

{
  "catalogs": [
    {
      "allow": true
    }
  ],
  "principals": [
    {
      "principal": "(.*)",
      "principal_to_user": "$1",
      "allow": true
    },
    {
      "principal": "([^/]+)/?.*@.*",
      "principal_to_user": "$1",
      "allow": true
    }
  ]
}

If you want to allow users to use exactly the same name as their Kerberos principal name, and allow alice and bob to use a group principal named as group@example.net, you can use the following rules.

{
  "catalogs": [
    {
      "allow": true
    }
  ],
  "principals": [
    {
      "principal": "([^/]+)/?.*@example.net",
      "principal_to_user": "$1",
      "allow": true
    },
    {
      "principal": "group@example.net",
      "user": "alice|bob",
      "allow": true
    }
  ]
}