3.5. 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:

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 principal rules specifying what principals can identify as what users (see Principal Rules below).

This plugin currently only supports catalog 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): boolean indicating whether a user has access to the catalog

Note

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

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, and deny all other access, you can use the following rules:

{
  "catalogs": [
    {
      "user": "admin",
      "catalog": "(mysql|system)",
      "allow": true
    },
    {
      "catalog": "hive",
      "allow": true
    },
    {
      "catalog": "system",
      "allow": false
    }
  ]
}

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 the extractly 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
    }
  ]
}