Remove superuser checks in pgstattuple

Now that we track initial privileges on extension objects and changes to
those permissions, we can drop the superuser() checks from the various
functions which are part of the pgstattuple extension and rely on the
GRANT system to control access to those functions.

Since a pg_upgrade will preserve the version of the extension which
existed prior to the upgrade, we can't simply modify the existing
functions but instead need to create new functions which remove the
checks and update the SQL-level functions to use the new functions
(and to REVOKE EXECUTE rights on those functions from PUBLIC).

Thanks to Tom and Andres for adding support for extensions to follow
update paths (see: 40b449a), allowing this patch to be much smaller
since no new base version script needed to be included.

Approach suggested by Noah.

Reviewed by Michael Paquier.

Author: sfrost

contrib/pgstattuple/Makefile

@@ -4,9 +4,10 @@ MODULE_big	= pgstattuple
 OBJS		= pgstattuple.o pgstatindex.o pgstatapprox.o $(WIN32RES)
 
 EXTENSION = pgstattuple
-DATA = pgstattuple--1.4.sql pgstattuple--1.3--1.4.sql \
-	pgstattuple--1.2--1.3.sql pgstattuple--1.1--1.2.sql \
-	pgstattuple--1.0--1.1.sql pgstattuple--unpackaged--1.0.sql
+DATA = pgstattuple--1.4.sql pgstattuple--1.4--1.5.sql \
+	pgstattuple--1.3--1.4.sql pgstattuple--1.2--1.3.sql \
+	pgstattuple--1.1--1.2.sql pgstattuple--1.0--1.1.sql \
+	pgstattuple--unpackaged--1.0.sql
 PGFILEDESC = "pgstattuple - tuple-level statistics"
 
 REGRESS = pgstattuple

contrib/pgstattuple/pgstatapprox.c

@@ -29,6 +29,9 @@
 #include "commands/vacuum.h"
 
 PG_FUNCTION_INFO_V1(pgstattuple_approx);
+PG_FUNCTION_INFO_V1(pgstattuple_approx_v1_5);
+
+Datum pgstattuple_approx_internal(Oid relid, FunctionCallInfo fcinfo);
 
 typedef struct output_type
 {
@@ -204,11 +207,42 @@ statapprox_heap(Relation rel, output_type *stat)
 
 /*
  * Returns estimated live/dead tuple statistics for the given relid.
+ *
+ * The superuser() check here must be kept as the library might be upgraded
+ * without the extension being upgraded, meaning that in pre-1.5 installations
+ * these functions could be called by any user.
  */
 Datum
 pgstattuple_approx(PG_FUNCTION_ARGS)
 {
 	Oid			relid = PG_GETARG_OID(0);
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 (errmsg("must be superuser to use pgstattuple functions"))));
+
+	PG_RETURN_DATUM(pgstattuple_approx_internal(relid, fcinfo));
+}
+
+/*
+ * As of pgstattuple version 1.5, we no longer need to check if the user
+ * is a superuser because we REVOKE EXECUTE on the SQL function from PUBLIC.
+ * Users can then grant access to it based on their policies.
+ *
+ * Otherwise identical to pgstattuple_approx (above).
+ */
+Datum
+pgstattuple_approx_v1_5(PG_FUNCTION_ARGS)
+{
+	Oid			relid = PG_GETARG_OID(0);
+
+	PG_RETURN_DATUM(pgstattuple_approx_internal(relid, fcinfo));
+}
+
+Datum
+pgstattuple_approx_internal(Oid relid, FunctionCallInfo fcinfo)
+{
 	Relation	rel;
 	output_type stat = {0};
 	TupleDesc	tupdesc;
@@ -217,11 +251,6 @@ pgstattuple_approx(PG_FUNCTION_ARGS)
 	HeapTuple	ret;
 	int			i = 0;
 
-	if (!superuser())
-		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 (errmsg("must be superuser to use pgstattuple functions"))));
-
 	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
 		elog(ERROR, "return type must be a row type");
 

contrib/pgstattuple/pgstatindex.c

@@ -54,6 +54,14 @@ PG_FUNCTION_INFO_V1(pg_relpages);
 PG_FUNCTION_INFO_V1(pg_relpagesbyid);
 PG_FUNCTION_INFO_V1(pgstatginindex);
 
+PG_FUNCTION_INFO_V1(pgstatindex_v1_5);
+PG_FUNCTION_INFO_V1(pgstatindexbyid_v1_5);
+PG_FUNCTION_INFO_V1(pg_relpages_v1_5);
+PG_FUNCTION_INFO_V1(pg_relpagesbyid_v1_5);
+PG_FUNCTION_INFO_V1(pgstatginindex_v1_5);
+
+Datum pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo);
+
 #define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
 #define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID)
 #define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
@@ -99,6 +107,10 @@ static Datum pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo);
  * pgstatindex()
  *
  * Usage: SELECT * FROM pgstatindex('t1_pkey');
+ *
+ * The superuser() check here must be kept as the library might be upgraded
+ * without the extension being upgraded, meaning that in pre-1.5 installations
+ * these functions could be called by any user.
  * ------------------------------------------------------
  */
 Datum
@@ -119,6 +131,31 @@ pgstatindex(PG_FUNCTION_ARGS)
 	PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
 }
 
+/*
+ * As of pgstattuple version 1.5, we no longer need to check if the user
+ * is a superuser because we REVOKE EXECUTE on the function from PUBLIC.
+ * Users can then grant access to it based on their policies.
+ *
+ * Otherwise identical to pgstatindex (above).
+ */
+Datum
+pgstatindex_v1_5(PG_FUNCTION_ARGS)
+{
+	text	   *relname = PG_GETARG_TEXT_P(0);
+	Relation	rel;
+	RangeVar   *relrv;
+
+	relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
+	rel = relation_openrv(relrv, AccessShareLock);
+
+	PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
+}
+
+/*
+ * The superuser() check here must be kept as the library might be upgraded
+ * without the extension being upgraded, meaning that in pre-1.5 installations
+ * these functions could be called by any user.
+ */
 Datum
 pgstatindexbyid(PG_FUNCTION_ARGS)
 {
@@ -135,6 +172,18 @@ pgstatindexbyid(PG_FUNCTION_ARGS)
 	PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
 }
 
+/* No need for superuser checks in v1.5, see above */
+Datum
+pgstatindexbyid_v1_5(PG_FUNCTION_ARGS)
+{
+	Oid			relid = PG_GETARG_OID(0);
+	Relation	rel;
+
+	rel = relation_open(relid, AccessShareLock);
+
+	PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
+}
+
 static Datum
 pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
 {
@@ -292,6 +341,8 @@ pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
  *
  * Usage: SELECT pg_relpages('t1');
  *		  SELECT pg_relpages('t1_pkey');
+ *
+ * Must keep superuser() check, see above.
  * --------------------------------------------------------
  */
 Datum
@@ -319,6 +370,28 @@ pg_relpages(PG_FUNCTION_ARGS)
 	PG_RETURN_INT64(relpages);
 }
 
+/* No need for superuser checks in v1.5, see above */
+Datum
+pg_relpages_v1_5(PG_FUNCTION_ARGS)
+{
+	text	   *relname = PG_GETARG_TEXT_P(0);
+	int64		relpages;
+	Relation	rel;
+	RangeVar   *relrv;
+
+	relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
+	rel = relation_openrv(relrv, AccessShareLock);
+
+	/* note: this will work OK on non-local temp tables */
+
+	relpages = RelationGetNumberOfBlocks(rel);
+
+	relation_close(rel, AccessShareLock);
+
+	PG_RETURN_INT64(relpages);
+}
+
+/* Must keep superuser() check, see above. */
 Datum
 pg_relpagesbyid(PG_FUNCTION_ARGS)
 {
@@ -342,16 +415,58 @@ pg_relpagesbyid(PG_FUNCTION_ARGS)
 	PG_RETURN_INT64(relpages);
 }
 
+/* No need for superuser checks in v1.5, see above */
+Datum
+pg_relpagesbyid_v1_5(PG_FUNCTION_ARGS)
+{
+	Oid			relid = PG_GETARG_OID(0);
+	int64		relpages;
+	Relation	rel;
+
+	rel = relation_open(relid, AccessShareLock);
+
+	/* note: this will work OK on non-local temp tables */
+
+	relpages = RelationGetNumberOfBlocks(rel);
+
+	relation_close(rel, AccessShareLock);
+
+	PG_RETURN_INT64(relpages);
+}
+
 /* ------------------------------------------------------
  * pgstatginindex()
  *
  * Usage: SELECT * FROM pgstatginindex('ginindex');
+ *
+ * Must keep superuser() check, see above.
  * ------------------------------------------------------
  */
 Datum
 pgstatginindex(PG_FUNCTION_ARGS)
 {
 	Oid			relid = PG_GETARG_OID(0);
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 (errmsg("must be superuser to use pgstattuple functions"))));
+
+	PG_RETURN_DATUM(pgstatginindex_internal(relid, fcinfo));
+}
+
+/* No need for superuser checks in v1.5, see above */
+Datum
+pgstatginindex_v1_5(PG_FUNCTION_ARGS)
+{
+	Oid			relid = PG_GETARG_OID(0);
+
+	PG_RETURN_DATUM(pgstatginindex_internal(relid, fcinfo));
+}
+
+Datum
+pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo)
+{
 	Relation	rel;
 	Buffer		buffer;
 	Page		page;
@@ -363,11 +478,6 @@ pgstatginindex(PG_FUNCTION_ARGS)
 	bool		nulls[3] = {false, false, false};
 	Datum		result;
 
-	if (!superuser())
-		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 (errmsg("must be superuser to use pgstattuple functions"))));
-
 	rel = relation_open(relid, AccessShareLock);
 
 	if (!IS_INDEX(rel) || !IS_GIN(rel))
@@ -415,5 +525,5 @@ pgstatginindex(PG_FUNCTION_ARGS)
 	tuple = heap_form_tuple(tupleDesc, values, nulls);
 	result = HeapTupleGetDatum(tuple);
 
-	PG_RETURN_DATUM(result);
+	return (result);
 }

contrib/pgstattuple/pgstattuple--1.4--1.5.sql

@@ -0,0 +1,111 @@
+/* contrib/pgstattuple/pgstattuple--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pgstattuple UPDATE TO '1.5'" to load this file. \quit
+
+CREATE OR REPLACE FUNCTION pgstattuple(IN relname text,
+    OUT table_len BIGINT,		-- physical table length in bytes
+    OUT tuple_count BIGINT,		-- number of live tuples
+    OUT tuple_len BIGINT,		-- total tuples length in bytes
+    OUT tuple_percent FLOAT8,		-- live tuples in %
+    OUT dead_tuple_count BIGINT,	-- number of dead tuples
+    OUT dead_tuple_len BIGINT,		-- total dead tuples length in bytes
+    OUT dead_tuple_percent FLOAT8,	-- dead tuples in %
+    OUT free_space BIGINT,		-- free space in bytes
+    OUT free_percent FLOAT8)		-- free space in %
+AS 'MODULE_PATHNAME', 'pgstattuple_v1_5'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pgstattuple(text) FROM PUBLIC;
+
+CREATE OR REPLACE FUNCTION pgstatindex(IN relname text,
+    OUT version INT,
+    OUT tree_level INT,
+    OUT index_size BIGINT,
+    OUT root_block_no BIGINT,
+    OUT internal_pages BIGINT,
+    OUT leaf_pages BIGINT,
+    OUT empty_pages BIGINT,
+    OUT deleted_pages BIGINT,
+    OUT avg_leaf_density FLOAT8,
+    OUT leaf_fragmentation FLOAT8)
+AS 'MODULE_PATHNAME', 'pgstatindex_v1_5'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pgstatindex(text) FROM PUBLIC;
+
+CREATE OR REPLACE FUNCTION pg_relpages(IN relname text)
+RETURNS BIGINT
+AS 'MODULE_PATHNAME', 'pg_relpages_v1_5'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pg_relpages(text) FROM PUBLIC;
+
+/* New stuff in 1.1 begins here */
+
+CREATE OR REPLACE FUNCTION pgstatginindex(IN relname regclass,
+    OUT version INT4,
+    OUT pending_pages INT4,
+    OUT pending_tuples BIGINT)
+AS 'MODULE_PATHNAME', 'pgstatginindex_v1_5'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pgstatginindex(regclass) FROM PUBLIC;
+
+/* New stuff in 1.2 begins here */
+
+CREATE OR REPLACE FUNCTION pgstattuple(IN reloid regclass,
+    OUT table_len BIGINT,		-- physical table length in bytes
+    OUT tuple_count BIGINT,		-- number of live tuples
+    OUT tuple_len BIGINT,		-- total tuples length in bytes
+    OUT tuple_percent FLOAT8,		-- live tuples in %
+    OUT dead_tuple_count BIGINT,	-- number of dead tuples
+    OUT dead_tuple_len BIGINT,		-- total dead tuples length in bytes
+    OUT dead_tuple_percent FLOAT8,	-- dead tuples in %
+    OUT free_space BIGINT,		-- free space in bytes
+    OUT free_percent FLOAT8)		-- free space in %
+AS 'MODULE_PATHNAME', 'pgstattuplebyid_v1_5'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pgstattuple(regclass) FROM PUBLIC;
+
+CREATE OR REPLACE FUNCTION pgstatindex(IN relname regclass,
+    OUT version INT,
+    OUT tree_level INT,
+    OUT index_size BIGINT,
+    OUT root_block_no BIGINT,
+    OUT internal_pages BIGINT,
+    OUT leaf_pages BIGINT,
+    OUT empty_pages BIGINT,
+    OUT deleted_pages BIGINT,
+    OUT avg_leaf_density FLOAT8,
+    OUT leaf_fragmentation FLOAT8)
+AS 'MODULE_PATHNAME', 'pgstatindexbyid_v1_5'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pgstatindex(regclass) FROM PUBLIC;
+
+CREATE OR REPLACE FUNCTION pg_relpages(IN relname regclass)
+RETURNS BIGINT
+AS 'MODULE_PATHNAME', 'pg_relpagesbyid_v1_5'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pg_relpages(regclass) FROM PUBLIC;
+
+/* New stuff in 1.3 begins here */
+
+CREATE OR REPLACE FUNCTION pgstattuple_approx(IN reloid regclass,
+    OUT table_len BIGINT,               -- physical table length in bytes
+    OUT scanned_percent FLOAT8,         -- what percentage of the table's pages was scanned
+    OUT approx_tuple_count BIGINT,      -- estimated number of live tuples
+    OUT approx_tuple_len BIGINT,        -- estimated total length in bytes of live tuples
+    OUT approx_tuple_percent FLOAT8,    -- live tuples in % (based on estimate)
+    OUT dead_tuple_count BIGINT,        -- exact number of dead tuples
+    OUT dead_tuple_len BIGINT,          -- exact total length in bytes of dead tuples
+    OUT dead_tuple_percent FLOAT8,      -- dead tuples in % (based on estimate)
+    OUT approx_free_space BIGINT,       -- estimated free space in bytes
+    OUT approx_free_percent FLOAT8)     -- free space in % (based on estimate)
+AS 'MODULE_PATHNAME', 'pgstattuple_approx_v1_5'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pgstattuple_approx(regclass) FROM PUBLIC;