graphql-engine/server/src-lib/Hasura/RQL/DDL/Permission/Internal.hs
Karthikeyan Chinnakonda 92026b769f [Preview] Inherited roles for postgres read queries
fixes #3868

docker image - `hasura/graphql-engine:inherited-roles-preview-48b73a2de`

Note:

To be able to use the inherited roles feature, the graphql-engine should be started with the env variable `HASURA_GRAPHQL_EXPERIMENTAL_FEATURES` set to `inherited_roles`.

Introduction
------------

This PR implements the idea of multiple roles as presented in this [paper](https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/FGALanguageICDE07.pdf). The multiple roles feature in this PR can be used via inherited roles. An inherited role is a role which can be created by combining multiple singular roles. For example, if there are two roles `author` and `editor` configured in the graphql-engine, then we can create a inherited role with the name of `combined_author_editor` role which will combine the select permissions of the `author` and `editor` roles and then make GraphQL queries using the `combined_author_editor`.

How are select permissions of different roles are combined?
------------------------------------------------------------

A select permission includes 5 things:

1. Columns accessible to the role
2. Row selection filter
3. Limit
4. Allow aggregation
5. Scalar computed fields accessible to the role

 Suppose there are two roles, `role1` gives access to the `address` column with row filter `P1` and `role2` gives access to both the `address` and the `phone` column with row filter `P2` and we create a new role `combined_roles` which combines `role1` and `role2`.

Let's say the following GraphQL query is queried with the `combined_roles` role.

```graphql
query {
   employees {
     address
     phone
   }
}
```

This will translate to the following SQL query:

```sql

 select
    (case when (P1 or P2) then address else null end) as address,
    (case when P2 then phone else null end) as phone
 from employee
 where (P1 or P2)
```

The other parameters of the select permission will be combined in the following manner:

1. Limit - Minimum of the limits will be the limit of the inherited role
2. Allow aggregations - If any of the role allows aggregation, then the inherited role will allow aggregation
3. Scalar computed fields - same as table column fields, as in the above example

APIs for inherited roles:
----------------------

1. `add_inherited_role`

`add_inherited_role` is the [metadata API](https://hasura.io/docs/1.0/graphql/core/api-reference/index.html#schema-metadata-api) to create a new inherited role. It accepts two arguments

`role_name`: the name of the inherited role to be added (String)
`role_set`: list of roles that need to be combined (Array of Strings)

Example:

```json
{
  "type": "add_inherited_role",
  "args": {
      "role_name":"combined_user",
      "role_set":[
          "user",
          "user1"
      ]
  }
}
```

After adding the inherited role, the inherited role can be used like single roles like earlier

Note:

An inherited role can only be created with non-inherited/singular roles.

2. `drop_inherited_role`

The `drop_inherited_role` API accepts the name of the inherited role and drops it from the metadata. It accepts a single argument:

`role_name`: name of the inherited role to be dropped

Example:

```json

{
  "type": "drop_inherited_role",
  "args": {
      "role_name":"combined_user"
  }
}
```

Metadata
---------

The derived roles metadata will be included under the `experimental_features` key while exporting the metadata.

```json
{
  "experimental_features": {
    "derived_roles": [
      {
        "role_name": "manager_is_employee_too",
        "role_set": [
          "employee",
          "manager"
        ]
      }
    ]
  }
}
```

Scope
------

Only postgres queries and subscriptions are supported in this PR.

Important points:
-----------------

1. All columns exposed to an inherited role will be marked as `nullable`, this is done so that cell value nullification can be done.

TODOs
-------

- [ ] Tests
   - [ ] Test a GraphQL query running with a inherited role without enabling inherited roles in experimental features
   - [] Tests for aggregate queries, limit, computed fields, functions, subscriptions (?)
   - [ ] Introspection test with a inherited role (nullability changes in a inherited role)
- [ ] Docs
- [ ] Changelog

Co-authored-by: Vamshi Surabhi <6562944+0x777@users.noreply.github.com>
GitOrigin-RevId: 3b8ee1e11f5ceca80fe294f8c074d42fbccfec63
2021-03-08 11:15:10 +00:00

122 lines
3.5 KiB
Haskell

{-# LANGUAGE TypeFamilyDependencies #-}
module Hasura.RQL.DDL.Permission.Internal where
import Hasura.Prelude
import qualified Data.HashMap.Strict as M
import qualified Data.Text as T
import Control.Lens hiding ((.=))
import Data.Aeson.TH
import Data.Aeson.Types
import Data.Text.Extended
import Hasura.Backends.Postgres.Translate.BoolExp
import Hasura.RQL.Types
import Hasura.Server.Utils
import Hasura.Session
convColSpec :: FieldInfoMap (FieldInfo b) -> PermColSpec b -> [Column b]
convColSpec _ (PCCols cols) = cols
convColSpec cim PCStar = map pgiColumn $ getCols cim
permissionIsDefined
:: Maybe (RolePermInfo backend) -> PermAccessor backend a -> Bool
permissionIsDefined rpi pa =
isJust $ join $ rpi ^? _Just.permAccToLens pa
assertPermDefined
:: (Backend backend, MonadError QErr m)
=> RoleName
-> PermAccessor backend a
-> TableInfo backend
-> m ()
assertPermDefined role pa tableInfo =
unless (permissionIsDefined rpi pa) $ throw400 PermissionDenied $ mconcat
[ "'" <> tshow (permAccToType pa) <> "'"
, " permission on " <>> _tciName (_tiCoreInfo tableInfo)
, " for role " <>> role
, " does not exist"
]
where
rpi = M.lookup role $ _tiRolePermInfoMap tableInfo
askPermInfo
:: (Backend backend, MonadError QErr m)
=> TableInfo backend
-> RoleName
-> PermAccessor backend c
-> m c
askPermInfo tabInfo roleName pa =
(M.lookup roleName rpim >>= (^. permAccToLens pa))
`onNothing`
throw400 PermissionDenied
(mconcat
[ pt <> " permission on " <>> _tciName (_tiCoreInfo tabInfo)
, " for role " <>> roleName
, " does not exist"
])
where
pt = permTypeToCode $ permAccToType pa
rpim = _tiRolePermInfoMap tabInfo
type CreatePerm b a = WithTable b (PermDef a)
data CreatePermP1Res a
= CreatePermP1Res
{ cprInfo :: !a
, cprDeps :: ![SchemaDependency]
} deriving (Show, Eq)
procBoolExp
:: (QErrM m, TableCoreInfoRM b m, BackendMetadata b)
=> SourceName
-> TableName b
-> FieldInfoMap (FieldInfo b)
-> BoolExp b
-> m (AnnBoolExpPartialSQL b, [SchemaDependency])
procBoolExp source tn fieldInfoMap be = do
abe <- annBoolExp parseCollectableType fieldInfoMap $ unBoolExp be
let deps = getBoolExpDeps source tn abe
return (abe, deps)
getDepHeadersFromVal :: Value -> [Text]
getDepHeadersFromVal val = case val of
Object o -> parseObject o
_ -> parseOnlyString val
where
parseOnlyString v = case v of
(String t)
| isSessionVariable t -> [T.toLower t]
| isReqUserId t -> [userIdHeader]
| otherwise -> []
_ -> []
parseObject o =
concatMap getDepHeadersFromVal (M.elems o)
getDependentHeaders :: BoolExp b -> [Text]
getDependentHeaders (BoolExp boolExp) =
flip foldMap boolExp $ \(ColExp _ v) -> getDepHeadersFromVal v
data DropPerm b a
= DropPerm
{ dipSource :: !SourceName
, dipTable :: !(TableName b)
, dipRole :: !RoleName
} deriving (Generic)
deriving instance (Backend b) => Show (DropPerm b a)
deriving instance (Backend b) => Eq (DropPerm b a)
instance (Backend b) => ToJSON (DropPerm b a) where
toJSON = genericToJSON hasuraJSON{omitNothingFields=True}
instance (Backend b) => FromJSON (DropPerm b a) where
parseJSON = withObject "DropPerm" $ \o ->
DropPerm
<$> o .:? "source" .!= defaultSource
<*> o .: "table"
<*> o .: "role"
type family PermInfo (b :: BackendType) a = r | r -> a