Grant memory views to pg_read_all_stats.

Grant privileges on views pg_backend_memory_contexts and
pg_shmem_allocations to the role pg_read_all_stats. Also grant on the
underlying functions that those views depend on.

Author: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Nathan Bossart <bossartn@amazon.com>
Discussion: https://postgr.es/m/CALj2ACWAZo3Ar_EVsn2Zf9irG+hYK3cmh1KWhZS_Od45nd01RA@mail.gmail.com

doc/src/sgml/catalogs.sgml

@@ -9916,7 +9916,8 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
 
   <para>
    By default, the <structname>pg_backend_memory_contexts</structname> view can be
-   read only by superusers.
+   read only by superusers or members of the <literal>pg_read_all_stats</literal>
+   role.
   </para>
  </sect1>
 
@@ -12746,7 +12747,8 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
 
   <para>
    By default, the <structname>pg_shmem_allocations</structname> view can be
-   read only by superusers.
+   read only by superusers or members of the <literal>pg_read_all_stats</literal>
+   role.
   </para>
  </sect1>
 

src/backend/catalog/system_views.sql

@@ -621,13 +621,17 @@ CREATE VIEW pg_shmem_allocations AS
     SELECT * FROM pg_get_shmem_allocations();
 
 REVOKE ALL ON pg_shmem_allocations FROM PUBLIC;
+GRANT SELECT ON pg_shmem_allocations TO pg_read_all_stats;
 REVOKE EXECUTE ON FUNCTION pg_get_shmem_allocations() FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION pg_get_shmem_allocations() TO pg_read_all_stats;
 
 CREATE VIEW pg_backend_memory_contexts AS
     SELECT * FROM pg_get_backend_memory_contexts();
 
 REVOKE ALL ON pg_backend_memory_contexts FROM PUBLIC;
+GRANT SELECT ON pg_backend_memory_contexts TO pg_read_all_stats;
 REVOKE EXECUTE ON FUNCTION pg_get_backend_memory_contexts() FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION pg_get_backend_memory_contexts() TO pg_read_all_stats;
 
 -- Statistics views
 

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202110271
+#define CATALOG_VERSION_NO	202110272
 
 #endif

src/test/regress/expected/privileges.out

@@ -2413,3 +2413,50 @@ REVOKE TRUNCATE ON lock_table FROM regress_locktable_user;
 -- clean up
 DROP TABLE lock_table;
 DROP USER regress_locktable_user;
+-- test to check privileges of system views pg_shmem_allocations and
+-- pg_backend_memory_contexts.
+-- switch to superuser
+\c -
+CREATE ROLE regress_readallstats;
+SELECT has_table_privilege('regress_readallstats','pg_backend_memory_contexts','SELECT'); -- no
+ has_table_privilege 
+---------------------
+ f
+(1 row)
+
+SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations','SELECT'); -- no
+ has_table_privilege 
+---------------------
+ f
+(1 row)
+
+GRANT pg_read_all_stats TO regress_readallstats;
+SELECT has_table_privilege('regress_readallstats','pg_backend_memory_contexts','SELECT'); -- yes
+ has_table_privilege 
+---------------------
+ t
+(1 row)
+
+SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations','SELECT'); -- yes
+ has_table_privilege 
+---------------------
+ t
+(1 row)
+
+-- run query to ensure that functions within views can be executed
+SET ROLE regress_readallstats;
+SELECT COUNT(*) >= 0 AS ok FROM pg_backend_memory_contexts;
+ ok 
+----
+ t
+(1 row)
+
+SELECT COUNT(*) >= 0 AS ok FROM pg_shmem_allocations;
+ ok 
+----
+ t
+(1 row)
+
+RESET ROLE;
+-- clean up
+DROP ROLE regress_readallstats;

src/test/regress/sql/privileges.sql

@@ -1476,3 +1476,28 @@ REVOKE TRUNCATE ON lock_table FROM regress_locktable_user;
 -- clean up
 DROP TABLE lock_table;
 DROP USER regress_locktable_user;
+
+-- test to check privileges of system views pg_shmem_allocations and
+-- pg_backend_memory_contexts.
+
+-- switch to superuser
+\c -
+
+CREATE ROLE regress_readallstats;
+
+SELECT has_table_privilege('regress_readallstats','pg_backend_memory_contexts','SELECT'); -- no
+SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations','SELECT'); -- no
+
+GRANT pg_read_all_stats TO regress_readallstats;
+
+SELECT has_table_privilege('regress_readallstats','pg_backend_memory_contexts','SELECT'); -- yes
+SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations','SELECT'); -- yes
+
+-- run query to ensure that functions within views can be executed
+SET ROLE regress_readallstats;
+SELECT COUNT(*) >= 0 AS ok FROM pg_backend_memory_contexts;
+SELECT COUNT(*) >= 0 AS ok FROM pg_shmem_allocations;
+RESET ROLE;
+
+-- clean up
+DROP ROLE regress_readallstats;