fix insert permission views are not unique for long role names (fix #3444) (#3486)

* fix insert permission views are not unique for long role names, fix #3444
* Use GHC notes reference and improve comments

server/src-lib/Hasura/GraphQL/Execute/LiveQuery/Poll.hs

@@ -98,10 +98,17 @@ data Cohort
   -- result changed, then merge them in the map of existing subscribers
   }
 
+{- Note [Blake2b faster than SHA-256]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+At the time of writing, from https://blake2.net, it is stated,
+"BLAKE2 is a cryptographic hash function faster than MD5, SHA-1, SHA-2, and SHA-3,
+yet is at least as secure as the latest standard SHA-3".
+-}
+
 -- | A hash used to determine if the result changed without having to keep the entire result in
 -- memory. Using a cryptographic hash ensures that a hash collision is almost impossible: with 256
 -- bits, even if a subscription changes once per second for an entire year, the probability of a
--- hash collision is ~4.294417×10-63. We use Blake2b because it is faster than SHA-256
+-- hash collision is ~4.294417×10-63. See Note [Blake2b faster than SHA-256].
 newtype ResponseHash = ResponseHash { unResponseHash :: CH.Digest CH.Blake2b_256 }
   deriving (Show, Eq)
 

server/src-lib/Hasura/RQL/DDL/Permission.hs

@@ -66,6 +66,7 @@ import           Data.Aeson.Casing
 import           Data.Aeson.TH
 import           Language.Haskell.TH.Syntax         (Lift)
 
+import qualified Crypto.Hash                        as CH
 import qualified Data.HashMap.Strict                as HM
 import qualified Data.HashSet                       as HS
 import qualified Data.Text                          as T
@@ -84,12 +85,15 @@ type InsPermDef = PermDef InsPerm
 type CreateInsPerm = CreatePerm InsPerm
 
 buildViewName :: QualifiedTable -> RoleName -> PermType -> QualifiedTable
-buildViewName (QualifiedObject sn tn) rn pt =
-  QualifiedObject hdbViewsSchema $ TableName
-  (roleNameToTxt rn <> "__" <> T.pack (show pt) <> "__" <> snTxt <> "__" <> tnTxt)
+buildViewName qt rn pt = QualifiedObject hdbViewsSchema tableName
   where
-    snTxt = getSchemaTxt sn
-    tnTxt = getTableTxt tn
+    -- Generate a unique hash for view name from role name, permission type and qualified table.
+    -- See Note [Postgres identifier length limitations].
+    -- Black2b_224 generates 56 character hash. See Note [Blake2b faster than SHA-256].
+    -- Refer https://github.com/hasura/graphql-engine/issues/3444.
+    tableName = TableName $ T.pack $ show hash
+    hash :: CH.Digest CH.Blake2b_224 =
+      CH.hash $ txtToBs $ roleNameToTxt rn <> "__" <> T.pack (show pt) <> "__" <> qualObjectToText qt
 
 buildView :: QualifiedTable -> QualifiedTable -> Q.Query
 buildView tn vn =

server/src-lib/Hasura/SQL/Rewrite.hs

@@ -8,11 +8,14 @@ import           Hasura.Prelude
 import qualified Hasura.SQL.DML      as S
 import           Hasura.SQL.Types    (Iden (..))
 
+{- Note [Postgres identifier length limitations]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Postgres truncates identifiers to a maximum of 63 characters by default (see
+https://www.postgresql.org/docs/12/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS).
+-}
 
--- add an int as a prefix to all aliases.
--- This is needed in cases identifiers exceed 63 chars
--- as postgres only considers first 63 chars of
--- an identifier
+-- Prefix an Int to all aliases to preserve the uniqueness of identifiers.
+-- See Note [Postgres identifier length limitations].
 prefixNumToAliases :: S.Select -> S.Select
 prefixNumToAliases s =
   uSelect s `evalState` UniqSt 0 Map.empty

server/tests-py/queries/v1/permissions/create_author_insert_permission_long_role.yaml

@@ -0,0 +1,27 @@
+- description: Create insert permission for author table with long (> 63 chars) role
+  url: /v1/query
+  status: 200
+  response:
+    message: success
+  query:
+    type: create_insert_permission
+    args:
+      table: author
+      role: this.is.really.a.very.long.and.long.role.more.than.63.characters.one
+      permission:
+        columns: '*'
+        check: {}
+
+- description: Create insert permission for author table with long (> 63 chars) role
+  url: /v1/query
+  status: 200
+  response:
+    message: success
+  query:
+    type: create_insert_permission
+    args:
+      table: author
+      role: this.is.really.a.very.long.and.long.role.more.than.63.characters.two
+      permission:
+        columns: '*'
+        check: {}

server/tests-py/queries/v1/permissions/teardown.yaml

@@ -4,10 +4,6 @@ args:
 - type: run_sql
   args:
     sql: |
-      drop table article
-
-- type: run_sql
-  args:
-    sql: |
-      drop table author
-
+      DROP TABLE article;
+      DROP TABLE author;
+    cascade: true

server/tests-py/test_v1_queries.py

@@ -629,6 +629,9 @@ class TestCreatePermission(DefaultTestQueries):
     def test_create_permission_user_role_error(self, hge_ctx):
         check_query_f(hge_ctx, self.dir() + '/create_article_permission_role_user.yaml')
 
+    def test_create_author_insert_permission_long_role(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + '/create_author_insert_permission_long_role.yaml')
+
     @classmethod
     def dir(cls):
         return "queries/v1/permissions"