mirror of
https://github.com/hasura/graphql-engine.git
synced 2024-12-22 15:01:39 +03:00
267 lines
10 KiB
ReStructuredText
267 lines
10 KiB
ReStructuredText
.. meta::
|
|
:description: Configure permission rules in Hasura
|
|
:keywords: hasura, docs, authorization, permissions, rules
|
|
|
|
.. _permission_rules:
|
|
|
|
Configuring Permission Rules
|
|
============================
|
|
|
|
.. contents:: Table of contents
|
|
:backlinks: none
|
|
:depth: 3
|
|
:local:
|
|
|
|
Introduction
|
|
------------
|
|
|
|
Access control rules in Hasura are defined at a role, table and action (*insert, update, select, delete*)
|
|
level granularity:
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/permission-rule-granularity.png
|
|
:alt: Access control rules in Hasura
|
|
|
|
Requests to Hasura should contain the reserved session variable ``X-Hasura-Role`` to indicate the requesting
|
|
user's role, and the table and action information is inferred from the request itself. This information is used
|
|
to determine the right permission rule to be applied (*if one has been defined*) to the incoming request.
|
|
|
|
Hasura converts GraphQL queries (*or mutations/subscriptions*) into a single SQL query that is executed on the
|
|
configured database instance.
|
|
Hasura also includes constraints from permission rules in the SQL query itself.
|
|
|
|
Permissions are essentially a combination of **boolean expressions** and **column selections** that impose
|
|
constraints on the data being returned or modified.
|
|
|
|
Let's take a look at the different configuration options available to define a permission rule. Permission
|
|
rules are defined for each role, table, operation (*insert, select, update, delete*) by using the console
|
|
or the :ref:`metadata APIs for permissions <api_permission>`.
|
|
|
|
Operation permissions
|
|
---------------------
|
|
|
|
**Select** permissions
|
|
^^^^^^^^^^^^^^^^^^^^^^
|
|
For ``select`` operations or for GraphQL queries, you can configure the following:
|
|
|
|
* :ref:`row-level-permissions`
|
|
|
|
* :ref:`col-level-permissions`
|
|
|
|
* :ref:`aggr-query-permissions`
|
|
|
|
* :ref:`limit-rows-permissions`
|
|
|
|
|
|
**Insert** permissions
|
|
^^^^^^^^^^^^^^^^^^^^^^
|
|
For ``insert`` operations or for GraphQL mutations of the type *insert*, you can configure the following:
|
|
|
|
* :ref:`row-level-permissions`
|
|
|
|
* :ref:`col-level-permissions`
|
|
|
|
* :ref:`col-presets-permissions`
|
|
|
|
* :ref:`backend-only-permissions`
|
|
|
|
**Update** permissions
|
|
^^^^^^^^^^^^^^^^^^^^^^
|
|
For ``update`` operations or for GraphQL mutations of the type *update*, you can configure the following:
|
|
|
|
* :ref:`row-level-permissions`
|
|
|
|
* :ref:`col-level-permissions`
|
|
|
|
* :ref:`col-presets-permissions`
|
|
|
|
**Delete** permissions
|
|
^^^^^^^^^^^^^^^^^^^^^^
|
|
For ``delete`` operations or for GraphQL mutations of the type *delete*, you can configure the following:
|
|
|
|
* :ref:`row-level-permissions`
|
|
|
|
Permission categories
|
|
---------------------
|
|
|
|
.. _row-level-permissions:
|
|
|
|
Row-level permissions
|
|
^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
Row-level premissions are **boolean expressions** that help you restrict access to rows depending on the
|
|
operation being performed. E.g. in the case of ``select``, your boolean expression is run on every row to
|
|
determine whether that row can be read. In the case of ``insert``, the boolean expression determines whether or not the mutation is allowed.
|
|
|
|
Row-level permissions are defined using operators, static values, values in columns (*including those in
|
|
related tables or nested objects*) and session variables.
|
|
|
|
Using column operators to build rules
|
|
*************************************
|
|
|
|
Type-based operators (*depending on the column type*) are available for constructing row-level permissions.
|
|
You can use the same operators that you use to :ref:`filter query results <filter_queries>`
|
|
along with a few others to define permission rules.
|
|
|
|
See the :ref:`API reference <MetadataOperator>` for a list of all supported column operators.
|
|
|
|
**For example**, the following two images illustrate the different operators available for ``integer`` and ``text``
|
|
types:
|
|
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/operators-for-integer-types.png
|
|
:width: 40%
|
|
:alt: Column operators for integer types
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/operators-for-text-types.png
|
|
:width: 40%
|
|
:alt: Column operators for text types
|
|
|
|
Using boolean expressions
|
|
*************************
|
|
|
|
The following is an example of a simple boolean expression to restrict access for ``select`` to rows where
|
|
the value in the ``id`` column is greater than 10:
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/simple-boolean-expression.png
|
|
:alt: Using boolean expressions to build rules
|
|
|
|
You can construct more complex boolean expressions using the ``_and``, ``_or`` and ``not`` operators:
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/boolean-operators.png
|
|
:alt: Using more complex boolean expressions to build rules
|
|
|
|
**For example**, using the ``_and`` operator, you can construct a rule to restrict access for ``select`` to rows where
|
|
the value in the ``id`` column is greater than 10 **and** the value in the ``name`` column starts with "a"
|
|
or "A":
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/composite-boolean-expression.png
|
|
:alt: Example of a rule with the _and operator
|
|
|
|
Using session variables
|
|
***********************
|
|
|
|
Session variables that have been resolved from authentication tokens by either your authentication webhook or
|
|
by Hasura using the JWT configuration are available for constructing row-level permissions.
|
|
|
|
**For example**, to allow an ``author`` to access only their articles, you can use the ``X-Hasura-User-ID`` session variable
|
|
to construct a rule to restrict access for ``select`` to rows in the ``articles`` table where the value in the
|
|
``id`` column is equal to the value in the session variable (*assuming this variable is being used to indicate
|
|
the author's ID*):
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/session-variables-in-permissions-simple-example.png
|
|
:alt: Using session variables to build rules
|
|
|
|
.. _relationships-in-permissions:
|
|
|
|
Using relationships or nested objects
|
|
*************************************
|
|
|
|
You can leverage :ref:`relationships <relationships>` to define permission rules with fields
|
|
from a nested object.
|
|
|
|
**For example**, let's say you have an object relationship called ``agent`` from the ``authors`` table to another table
|
|
called ``agent`` (*an author can have an agent*) and we want to allow users with the role ``agent`` to access
|
|
the details of the authors who they manage in ``authors`` table. We can define the following permission rule
|
|
that uses the aforementioned object relationship:
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/nested-object-permission-simple-example.png
|
|
:alt: Using a nested object to build rules
|
|
|
|
This permission rule reads as "*if the author's agent's* ``id`` *is the same as the requesting user's*
|
|
``id`` *, allow access to the author's details*."
|
|
|
|
|
|
.. admonition:: Array and object relationships work similarly
|
|
|
|
- The above example would have worked even if the relationship were an array relationship. In our example,
|
|
the corresponding rule for an array relationship would have read "*if any of this author's agents'* ``id``
|
|
*is the same as the requesting user's* ``id`` *, allow access to the author's details*".
|
|
|
|
- You can also check out this more elaborate :ref:`example<nested-object-permissions-example>`.
|
|
|
|
.. _unrelated-tables-in-permissions:
|
|
|
|
Using unrelated tables / views
|
|
******************************
|
|
|
|
You can use the ``_exists`` operator to set a permission rule based on tables/views that are not related to
|
|
our table.
|
|
|
|
**For example**, say we want to allow a user to ``insert`` an ``article`` only if the value of the ``allow_article_create``
|
|
column in the ``users`` table is set to ``true``. Let's assume the user's id is passed in the ``X-Hasura-User-ID``
|
|
session variable.
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/exists-permission-example.png
|
|
:alt: Use an unrelated table to build rules
|
|
|
|
This permission rule reads as "*if there exists a row in the table* ``users`` *whose* ``id`` *is the same as the requesting user's*
|
|
``id`` *and has the* ``allow_article_create`` *column set to true, allow access to insert articles*."
|
|
|
|
.. _col-level-permissions:
|
|
|
|
Column-level permissions
|
|
^^^^^^^^^^^^^^^^^^^^^^^^
|
|
Column-level permissions determine access to columns in the rows that are accessible based on row-level
|
|
permissions. These permissions are simple selections:
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/column-level-permissions.png
|
|
:alt: Column level permissions
|
|
|
|
In this example, the role ``author`` has only partial access to columns of the accessible rows for
|
|
the ``select`` operation.
|
|
|
|
.. _limit-rows-permissions:
|
|
|
|
Row fetch limit
|
|
^^^^^^^^^^^^^^^
|
|
|
|
In the case of ``select`` operations, the number of rows to be returned in the response can be limited
|
|
using this configuration:
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/limit-rows-for-select.png
|
|
:alt: Row fetch limit
|
|
|
|
In the above example, this configuration restricts the number of accessible rows (*based on the rule*:
|
|
``{"id":{"_eq":"X-Hasura-User-Id"}}``) to 20.
|
|
|
|
.. _aggr-query-permissions:
|
|
|
|
Aggregation queries permissions
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
In the case of ``select`` operations, access to :ref:`aggregation queries <aggregation_queries>`
|
|
can be restricted for a given role using this configuration.
|
|
|
|
.. thumbnail:: ../../../../img/graphql/manual/auth/aggregation-query-permissions.png
|
|
:alt: Aggregation queries permissions
|
|
|
|
In the above example, the role ``user`` is allowed to make aggregation queries.
|
|
|
|
.. _col-presets-permissions:
|
|
|
|
Column presets
|
|
^^^^^^^^^^^^^^
|
|
|
|
While this is strictly not a permission configuration, defining
|
|
:ref:`role-based column presets <column_presets>` on any column automatically
|
|
removes access to it. This preset can be defined for ``insert`` and ``update`` operations. This configuration
|
|
is also very useful to avoid sending sensitive user-information in the query and leverage session variables
|
|
or static data instead.
|
|
|
|
.. _backend-only-permissions:
|
|
|
|
Backend only
|
|
^^^^^^^^^^^^
|
|
|
|
If a permission is marked as ``backend_only``, the mutation is accessible to the
|
|
given role only if ``x-hasura-use-backend-only-permissions`` session variable exists and is set to ``true``
|
|
and request is made with ``x-hasura-admin-secret`` set if any auth is configured.
|
|
|
|
This might be useful if you would like to hide a mutation from the public facing API but allow access to it
|
|
via a "trusted backend".
|
|
|
|
.. note::
|
|
|
|
Setting ``backend-only`` is currently available for insert mutations only.
|
|
|