Make security barrier views automatically updatable

Views which are marked as security_barrier must have their quals
applied before any user-defined quals are called, to prevent
user-defined functions from being able to see rows which the
security barrier view is intended to prevent them from seeing.

Remove the restriction on security barrier views being automatically
updatable by adding a new securityQuals list to the RTE structure
which keeps track of the quals from security barrier views at each
level, independently of the user-supplied quals.  When RTEs are
later discovered which have securityQuals populated, they are turned
into subquery RTEs which are marked as security_barrier to prevent
any user-supplied quals being pushed down (modulo LEAKPROOF quals).

Dean Rasheed, reviewed by Craig Ringer, Simon Riggs, KaiGai Kohei

doc/src/sgml/ref/create_view.sgml

@@ -323,12 +323,6 @@ CREATE VIEW vista AS SELECT text 'Hello World' AS hello;
        or set-returning functions.
       </para>
      </listitem>
-
-     <listitem>
-      <para>
-       The view must not have the <literal>security_barrier</> property.
-      </para>
-     </listitem>
     </itemizedlist>
    </para>
 
@@ -361,6 +355,19 @@ CREATE VIEW vista AS SELECT text 'Hello World' AS hello;
     such rows that are not visible through the view.
    </para>
 
+   <para>
+    If an automatically updatable view is marked with the
+    <literal>security_barrier</> property then all the view's <literal>WHERE</>
+    conditions (and any conditions using operators which are marked as LEAKPROOF)
+    will always be evaluated before any conditions that a user of the view has
+    added.   See <xref linkend="rules-privileges"> for full details.  Note that,
+    due to this, rows which are not ultimately returned (because they do not
+    pass the user's <literal>WHERE</> conditions) may still end up being locked.
+    <command>EXPLAIN</command> can be used to see which conditions are
+    applied at the relation level (and therefore do not lock rows) and which are
+    not.
+   </para>
+
    <para>
     A more complex view that does not satisfy all these conditions is
     read-only by default: the system will not allow an insert, update, or

src/backend/commands/tablecmds.c

@@ -8910,7 +8910,6 @@ ATExecSetRelOptions(Relation rel, List *defList, AlterTableType operation,
 		List	   *view_options = untransformRelOptions(newOptions);
 		ListCell   *cell;
 		bool		check_option = false;
-		bool		security_barrier = false;
 
 		foreach(cell, view_options)
 		{
@@ -8918,8 +8917,6 @@ ATExecSetRelOptions(Relation rel, List *defList, AlterTableType operation,
 
 			if (pg_strcasecmp(defel->defname, "check_option") == 0)
 				check_option = true;
-			if (pg_strcasecmp(defel->defname, "security_barrier") == 0)
-				security_barrier = defGetBoolean(defel);
 		}
 
 		/*
@@ -8929,8 +8926,7 @@ ATExecSetRelOptions(Relation rel, List *defList, AlterTableType operation,
 		if (check_option)
 		{
 			const char *view_updatable_error =
-				view_query_is_auto_updatable(view_query,
-											 security_barrier, true);
+				view_query_is_auto_updatable(view_query, true);
 
 			if (view_updatable_error)
 				ereport(ERROR,

src/backend/commands/view.c

@@ -396,7 +396,6 @@ DefineView(ViewStmt *stmt, const char *queryString)
 	RangeVar   *view;
 	ListCell   *cell;
 	bool		check_option;
-	bool		security_barrier;
 
 	/*
 	 * Run parse analysis to convert the raw parse tree to a Query.  Note this
@@ -451,7 +450,6 @@ DefineView(ViewStmt *stmt, const char *queryString)
 	 * specified.
 	 */
 	check_option = false;
-	security_barrier = false;
 
 	foreach(cell, stmt->options)
 	{
@@ -459,8 +457,6 @@ DefineView(ViewStmt *stmt, const char *queryString)
 
 		if (pg_strcasecmp(defel->defname, "check_option") == 0)
 			check_option = true;
-		if (pg_strcasecmp(defel->defname, "security_barrier") == 0)
-			security_barrier = defGetBoolean(defel);
 	}
 
 	/*
@@ -470,7 +466,7 @@ DefineView(ViewStmt *stmt, const char *queryString)
 	if (check_option)
 	{
 		const char *view_updatable_error =
-			view_query_is_auto_updatable(viewParse, security_barrier, true);
+			view_query_is_auto_updatable(viewParse, true);
 
 		if (view_updatable_error)
 			ereport(ERROR,

src/backend/nodes/copyfuncs.c

@@ -1998,6 +1998,7 @@ _copyRangeTblEntry(const RangeTblEntry *from)
 	COPY_SCALAR_FIELD(checkAsUser);
 	COPY_BITMAPSET_FIELD(selectedCols);
 	COPY_BITMAPSET_FIELD(modifiedCols);
+	COPY_NODE_FIELD(securityQuals);
 
 	return newnode;
 }

src/backend/nodes/equalfuncs.c

@@ -2296,6 +2296,7 @@ _equalRangeTblEntry(const RangeTblEntry *a, const RangeTblEntry *b)
 	COMPARE_SCALAR_FIELD(checkAsUser);
 	COMPARE_BITMAPSET_FIELD(selectedCols);
 	COMPARE_BITMAPSET_FIELD(modifiedCols);
+	COMPARE_NODE_FIELD(securityQuals);
 
 	return true;
 }

src/backend/nodes/nodeFuncs.c

@@ -2020,6 +2020,9 @@ range_table_walker(List *rtable,
 					return true;
 				break;
 		}
+
+		if (walker(rte->securityQuals, context))
+			return true;
 	}
 	return false;
 }
@@ -2755,6 +2758,7 @@ range_table_mutator(List *rtable,
 				MUTATE(newrte->values_lists, rte->values_lists, List *);
 				break;
 		}
+		MUTATE(newrte->securityQuals, rte->securityQuals, List *);
 		newrt = lappend(newrt, newrte);
 	}
 	return newrt;

src/backend/nodes/outfuncs.c

@@ -2409,6 +2409,7 @@ _outRangeTblEntry(StringInfo str, const RangeTblEntry *node)
 	WRITE_OID_FIELD(checkAsUser);
 	WRITE_BITMAPSET_FIELD(selectedCols);
 	WRITE_BITMAPSET_FIELD(modifiedCols);
+	WRITE_NODE_FIELD(securityQuals);
 }
 
 static void

src/backend/nodes/readfuncs.c

@@ -1252,6 +1252,7 @@ _readRangeTblEntry(void)
 	READ_OID_FIELD(checkAsUser);
 	READ_BITMAPSET_FIELD(selectedCols);
 	READ_BITMAPSET_FIELD(modifiedCols);
+	READ_NODE_FIELD(securityQuals);
 
 	READ_DONE();
 }

src/backend/optimizer/plan/planner.c

@@ -915,6 +915,12 @@ inheritance_planner(PlannerInfo *root)
 		/* Generate plan */
 		subplan = grouping_planner(&subroot, 0.0 /* retrieve all tuples */ );
 
+		/*
+		 * Planning may have modified the query result relation (if there
+		 * were security barrier quals on the result RTE).
+		 */
+		appinfo->child_relid = subroot.parse->resultRelation;
+
 		/*
 		 * If this child rel was excluded by constraint exclusion, exclude it
 		 * from the result plan.
@@ -932,9 +938,40 @@ inheritance_planner(PlannerInfo *root)
 		if (final_rtable == NIL)
 			final_rtable = subroot.parse->rtable;
 		else
-			final_rtable = list_concat(final_rtable,
+		{
+			List	   *tmp_rtable = NIL;
+			ListCell   *cell1, *cell2;
+
+			/*
+			 * Check to see if any of the original RTEs were turned into
+			 * subqueries during planning.  Currently, this should only ever
+			 * happen due to securityQuals being involved which push a
+			 * relation down under a subquery, to ensure that the security
+			 * barrier quals are evaluated first.
+			 *
+			 * When this happens, we want to use the new subqueries in the
+			 * final rtable.
+			 */
+			forboth(cell1, final_rtable, cell2, subroot.parse->rtable)
+			{
+				RangeTblEntry *rte1 = (RangeTblEntry *) lfirst(cell1);
+				RangeTblEntry *rte2 = (RangeTblEntry *) lfirst(cell2);
+
+				if (rte1->rtekind == RTE_RELATION &&
+					rte2->rtekind == RTE_SUBQUERY)
+				{
+					/* Should only be when there are securityQuals today */
+					Assert(rte1->securityQuals != NIL);
+					tmp_rtable = lappend(tmp_rtable, rte2);
+				}
+				else
+					tmp_rtable = lappend(tmp_rtable, rte1);
+			}
+
+			final_rtable = list_concat(tmp_rtable,
 									   list_copy_tail(subroot.parse->rtable,
 												 list_length(final_rtable)));
+		}
 
 		/*
 		 * We need to collect all the RelOptInfos from all child plans into
@@ -1162,6 +1199,12 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 		/* Preprocess targetlist */
 		tlist = preprocess_targetlist(root, tlist);
 
+		/*
+		 * Expand any rangetable entries that have security barrier quals.
+		 * This may add new security barrier subquery RTEs to the rangetable.
+		 */
+		expand_security_quals(root, tlist);
+
 		/*
 		 * Locate any window functions in the tlist.  (We don't need to look
 		 * anywhere else, since expressions used in ORDER BY will be in there

src/backend/optimizer/prep/Makefile

@@ -12,6 +12,6 @@ subdir = src/backend/optimizer/prep
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = prepjointree.o prepqual.o preptlist.o prepunion.o
+OBJS = prepjointree.o prepqual.o prepsecurity.o preptlist.o prepunion.o
 
 include $(top_srcdir)/src/backend/common.mk

src/backend/optimizer/prep/prepunion.c

@@ -55,6 +55,7 @@ typedef struct
 {
 	PlannerInfo *root;
 	AppendRelInfo *appinfo;
+	int			sublevels_up;
 } adjust_appendrel_attrs_context;
 
 static Plan *recurse_set_operations(Node *setOp, PlannerInfo *root,
@@ -1580,8 +1581,9 @@ translate_col_privs(const Bitmapset *parent_privs,
  *	  child rel instead.  We also update rtindexes appearing outside Vars,
  *	  such as resultRelation and jointree relids.
  *
- * Note: this is only applied after conversion of sublinks to subplans,
- * so we don't need to cope with recursion into sub-queries.
+ * Note: this is applied after conversion of sublinks to subplans in the
+ * query jointree, but there may still be sublinks in the security barrier
+ * quals of RTEs, so we do need to cope with recursion into sub-queries.
  *
  * Note: this is not hugely different from what pullup_replace_vars() does;
  * maybe we should try to fold the two routines together.
@@ -1594,9 +1596,12 @@ adjust_appendrel_attrs(PlannerInfo *root, Node *node, AppendRelInfo *appinfo)
 
 	context.root = root;
 	context.appinfo = appinfo;
+	context.sublevels_up = 0;
 
 	/*
-	 * Must be prepared to start with a Query or a bare expression tree.
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, go straight to query_tree_walker to make sure that
+	 * sublevels_up doesn't get incremented prematurely.
 	 */
 	if (node && IsA(node, Query))
 	{
@@ -1635,7 +1640,7 @@ adjust_appendrel_attrs_mutator(Node *node,
 	{
 		Var		   *var = (Var *) copyObject(node);
 
-		if (var->varlevelsup == 0 &&
+		if (var->varlevelsup == context->sublevels_up &&
 			var->varno == appinfo->parent_relid)
 		{
 			var->varno = appinfo->child_relid;
@@ -1652,6 +1657,7 @@ adjust_appendrel_attrs_mutator(Node *node,
 				if (newnode == NULL)
 					elog(ERROR, "attribute %d of relation \"%s\" does not exist",
 						 var->varattno, get_rel_name(appinfo->parent_reloid));
+				((Var *) newnode)->varlevelsup += context->sublevels_up;
 				return newnode;
 			}
 			else if (var->varattno == 0)
@@ -1694,10 +1700,16 @@ adjust_appendrel_attrs_mutator(Node *node,
 					RowExpr    *rowexpr;
 					List	   *fields;
 					RangeTblEntry *rte;
+					ListCell   *lc;
 
 					rte = rt_fetch(appinfo->parent_relid,
 								   context->root->parse->rtable);
 					fields = (List *) copyObject(appinfo->translated_vars);
+					foreach(lc, fields)
+					{
+						Var		   *field = (Var *) lfirst(lc);
+						field->varlevelsup += context->sublevels_up;
+					}
 					rowexpr = makeNode(RowExpr);
 					rowexpr->args = fields;
 					rowexpr->row_typeid = var->vartype;
@@ -1716,7 +1728,8 @@ adjust_appendrel_attrs_mutator(Node *node,
 	{
 		CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node);
 
-		if (cexpr->cvarno == appinfo->parent_relid)
+		if (context->sublevels_up == 0 &&
+			cexpr->cvarno == appinfo->parent_relid)
 			cexpr->cvarno = appinfo->child_relid;
 		return (Node *) cexpr;
 	}
@@ -1724,7 +1737,8 @@ adjust_appendrel_attrs_mutator(Node *node,
 	{
 		RangeTblRef *rtr = (RangeTblRef *) copyObject(node);
 
-		if (rtr->rtindex == appinfo->parent_relid)
+		if (context->sublevels_up == 0 &&
+			rtr->rtindex == appinfo->parent_relid)
 			rtr->rtindex = appinfo->child_relid;
 		return (Node *) rtr;
 	}
@@ -1737,7 +1751,8 @@ adjust_appendrel_attrs_mutator(Node *node,
 											  adjust_appendrel_attrs_mutator,
 												 (void *) context);
 		/* now fix JoinExpr's rtindex (probably never happens) */
-		if (j->rtindex == appinfo->parent_relid)
+		if (context->sublevels_up == 0 &&
+			j->rtindex == appinfo->parent_relid)
 			j->rtindex = appinfo->child_relid;
 		return (Node *) j;
 	}
@@ -1750,7 +1765,7 @@ adjust_appendrel_attrs_mutator(Node *node,
 											  adjust_appendrel_attrs_mutator,
 														 (void *) context);
 		/* now fix PlaceHolderVar's relid sets */
-		if (phv->phlevelsup == 0)
+		if (phv->phlevelsup == context->sublevels_up)
 			phv->phrels = adjust_relid_set(phv->phrels,
 										   appinfo->parent_relid,
 										   appinfo->child_relid);
@@ -1822,12 +1837,29 @@ adjust_appendrel_attrs_mutator(Node *node,
 		return (Node *) newinfo;
 	}
 
-	/*
-	 * NOTE: we do not need to recurse into sublinks, because they should
-	 * already have been converted to subplans before we see them.
-	 */
-	Assert(!IsA(node, SubLink));
-	Assert(!IsA(node, Query));
+	if (IsA(node, Query))
+	{
+		/*
+		 * Recurse into sublink subqueries. This should only be possible in
+		 * security barrier quals of top-level RTEs. All other sublinks should
+		 * have already been converted to subplans during expression
+		 * preprocessing, but this doesn't happen for security barrier quals,
+		 * since they are destined to become quals of a subquery RTE, which
+		 * will be recursively planned, and so should not be preprocessed at
+		 * this stage.
+		 *
+		 * We don't explicitly Assert() for securityQuals here simply because
+		 * it's not trivial to do so.
+		 */
+		Query	   *newnode;
+
+		context->sublevels_up++;
+		newnode = query_tree_mutator((Query *) node,
+									 adjust_appendrel_attrs_mutator,
+									 (void *) context, 0);
+		context->sublevels_up--;
+		return (Node *) newnode;
+	}
 
 	return expression_tree_mutator(node, adjust_appendrel_attrs_mutator,
 								   (void *) context);

src/backend/rewrite/rewriteHandler.c

@@ -2023,8 +2023,7 @@ view_col_is_auto_updatable(RangeTblRef *rtr, TargetEntry *tle)
  * updatable.
  */
 const char *
-view_query_is_auto_updatable(Query *viewquery, bool security_barrier,
-							 bool check_cols)
+view_query_is_auto_updatable(Query *viewquery, bool check_cols)
 {
 	RangeTblRef *rtr;
 	RangeTblEntry *base_rte;
@@ -2097,14 +2096,6 @@ view_query_is_auto_updatable(Query *viewquery, bool security_barrier,
 	if (expression_returns_set((Node *) viewquery->targetList))
 		return gettext_noop("Views that return set-returning functions are not automatically updatable.");
 
-	/*
-	 * For now, we also don't support security-barrier views, because of the
-	 * difficulty of keeping upper-level qual expressions away from
-	 * lower-level data.  This might get relaxed in the future.
-	 */
-	if (security_barrier)
-		return gettext_noop("Security-barrier views are not automatically updatable.");
-
 	/*
 	 * The view query should select from a single base relation, which must be
 	 * a table or another view.
@@ -2353,9 +2344,7 @@ relation_is_updatable(Oid reloid,
 	{
 		Query	   *viewquery = get_view_query(rel);
 
-		if (view_query_is_auto_updatable(viewquery,
-										 RelationIsSecurityView(rel),
-										 false) == NULL)
+		if (view_query_is_auto_updatable(viewquery, false) == NULL)
 		{
 			Bitmapset  *updatable_cols;
 			int			auto_events;
@@ -2510,7 +2499,6 @@ rewriteTargetView(Query *parsetree, Relation view)
 
 	auto_update_detail =
 		view_query_is_auto_updatable(viewquery,
-									 RelationIsSecurityView(view),
 									 parsetree->commandType != CMD_DELETE);
 
 	if (auto_update_detail)
@@ -2713,6 +2701,14 @@ rewriteTargetView(Query *parsetree, Relation view)
 	new_rte->modifiedCols = adjust_view_column_set(view_rte->modifiedCols,
 												   view_targetlist);
 
+	/*
+	 * Move any security barrier quals from the view RTE onto the new target
+	 * RTE.  Any such quals should now apply to the new target RTE and will not
+	 * reference the original view RTE in the rewritten query.
+	 */
+	new_rte->securityQuals = view_rte->securityQuals;
+	view_rte->securityQuals = NIL;
+
 	/*
 	 * For UPDATE/DELETE, rewriteTargetListUD will have added a wholerow junk
 	 * TLE for the view to the end of the targetlist, which we no longer need.
@@ -2793,6 +2789,10 @@ rewriteTargetView(Query *parsetree, Relation view)
 	 * only adjust their varnos to reference the new target (just the same as
 	 * we did with the view targetlist).
 	 *
+	 * Note that there is special-case handling for the quals of a security
+	 * barrier view, since they need to be kept separate from any user-supplied
+	 * quals, so these quals are kept on the new target RTE.
+	 *
 	 * For INSERT, the view's quals can be ignored in the main query.
 	 */
 	if (parsetree->commandType != CMD_INSERT &&
@@ -2801,7 +2801,25 @@ rewriteTargetView(Query *parsetree, Relation view)
 		Node	   *viewqual = (Node *) copyObject(viewquery->jointree->quals);
 
 		ChangeVarNodes(viewqual, base_rt_index, new_rt_index, 0);
-		AddQual(parsetree, (Node *) viewqual);
+
+		if (RelationIsSecurityView(view))
+		{
+			/*
+			 * Note: the parsetree has been mutated, so the new_rte pointer is
+			 * stale and needs to be re-computed.
+			 */
+			new_rte = rt_fetch(new_rt_index, parsetree->rtable);
+			new_rte->securityQuals = lcons(viewqual, new_rte->securityQuals);
+
+			/*
+			 * Make sure that the query is marked correctly if the added qual
+			 * has sublinks.
+			 */
+			if (!parsetree->hasSubLinks)
+				parsetree->hasSubLinks = checkExprHasSubLink(viewqual);
+		}
+		else
+			AddQual(parsetree, (Node *) viewqual);
 	}
 
 	/*
@@ -2863,9 +2881,8 @@ rewriteTargetView(Query *parsetree, Relation view)
 				 * Make sure that the query is marked correctly if the added
 				 * qual has sublinks.  We can skip this check if the query is
 				 * already marked, or if the command is an UPDATE, in which
-				 * case the same qual will have already been added to the
-				 * query's WHERE clause, and AddQual will have already done
-				 * this check.
+				 * case the same qual will have already been added, and this
+				 * check will already have been done.
 				 */
 				if (!parsetree->hasSubLinks &&
 					parsetree->commandType != CMD_UPDATE)

src/include/nodes/parsenodes.h

@@ -801,6 +801,7 @@ typedef struct RangeTblEntry
 	Oid			checkAsUser;	/* if valid, check access as this role */
 	Bitmapset  *selectedCols;	/* columns needing SELECT permission */
 	Bitmapset  *modifiedCols;	/* columns needing INSERT/UPDATE permission */
+	List	   *securityQuals;	/* any security barrier quals to apply */
 } RangeTblEntry;
 
 /*

src/include/optimizer/prep.h

@@ -35,6 +35,11 @@ extern Relids get_relids_for_join(PlannerInfo *root, int joinrelid);
 extern Node *negate_clause(Node *node);
 extern Expr *canonicalize_qual(Expr *qual);
 
+/*
+ * prototypes for prepsecurity.c
+ */
+extern void expand_security_quals(PlannerInfo *root, List *tlist);
+
 /*
  * prototypes for preptlist.c
  */

src/include/rewrite/rewriteHandler.h

@@ -25,7 +25,6 @@ extern void AcquireRewriteLocks(Query *parsetree,
 extern Node *build_column_default(Relation rel, int attrno);
 extern Query *get_view_query(Relation view);
 extern const char *view_query_is_auto_updatable(Query *viewquery,
-										 bool security_barrier,
 										 bool check_cols);
 extern int	relation_is_updatable(Oid reloid,
 						  bool include_triggers,

src/test/regress/expected/create_view.out

@@ -252,7 +252,7 @@ CREATE VIEW mysecview4 WITH (security_barrier)
        AS SELECT * FROM tbl1 WHERE a <> 0;
 CREATE VIEW mysecview5 WITH (security_barrier=100)	-- Error
        AS SELECT * FROM tbl1 WHERE a > 100;
-ERROR:  security_barrier requires a Boolean value
+ERROR:  invalid value for boolean option "security_barrier": 100
 CREATE VIEW mysecview6 WITH (invalid_option)		-- Error
        AS SELECT * FROM tbl1 WHERE a < 100;
 ERROR:  unrecognized parameter "invalid_option"

src/test/regress/sql/updatable_views.sql

@@ -25,12 +25,10 @@ CREATE VIEW rw_view14 AS SELECT ctid, a, b FROM base_tbl; -- System columns may
 CREATE VIEW rw_view15 AS SELECT a, upper(b) FROM base_tbl; -- Expression/function may be part of an updatable view
 CREATE VIEW rw_view16 AS SELECT a, b, a AS aa FROM base_tbl; -- Repeated column may be part of an updatable view
 CREATE VIEW ro_view17 AS SELECT * FROM ro_view1; -- Base relation not updatable
-CREATE VIEW ro_view18 WITH (security_barrier = true)
-  AS SELECT * FROM base_tbl; -- Security barrier views not updatable
-CREATE VIEW ro_view19 AS SELECT * FROM (VALUES(1)) AS tmp(a); -- VALUES in rangetable
+CREATE VIEW ro_view18 AS SELECT * FROM (VALUES(1)) AS tmp(a); -- VALUES in rangetable
 CREATE SEQUENCE seq;
-CREATE VIEW ro_view20 AS SELECT * FROM seq; -- View based on a sequence
-CREATE VIEW ro_view21 AS SELECT a, b, generate_series(1, a) g FROM base_tbl; -- SRF in targetlist not supported
+CREATE VIEW ro_view19 AS SELECT * FROM seq; -- View based on a sequence
+CREATE VIEW ro_view20 AS SELECT a, b, generate_series(1, a) g FROM base_tbl; -- SRF in targetlist not supported
 
 SELECT table_name, is_insertable_into
   FROM information_schema.tables
@@ -87,13 +85,12 @@ SELECT * FROM base_tbl;
 DELETE FROM rw_view16 WHERE a=-3; -- should be OK
 -- Read-only views
 INSERT INTO ro_view17 VALUES (3, 'ROW 3');
-INSERT INTO ro_view18 VALUES (3, 'ROW 3');
-DELETE FROM ro_view19;
-UPDATE ro_view20 SET max_value=1000;
-UPDATE ro_view21 SET b=upper(b);
+DELETE FROM ro_view18;
+UPDATE ro_view19 SET max_value=1000;
+UPDATE ro_view20 SET b=upper(b);
 
 DROP TABLE base_tbl CASCADE;
-DROP VIEW ro_view10, ro_view12, ro_view19;
+DROP VIEW ro_view10, ro_view12, ro_view18;
 DROP SEQUENCE seq CASCADE;
 
 -- simple updatable view
@@ -828,3 +825,166 @@ CREATE VIEW rw_view2 AS
   SELECT * FROM rw_view1 WHERE a > b WITH LOCAL CHECK OPTION;
 INSERT INTO rw_view2 VALUES (2,3); -- ok, but not in view (doesn't fail rw_view2's check)
 DROP TABLE base_tbl CASCADE;
+
+-- security barrier view
+
+CREATE TABLE base_tbl (person text, visibility text);
+INSERT INTO base_tbl VALUES ('Tom', 'public'),
+                            ('Dick', 'private'),
+                            ('Harry', 'public');
+
+CREATE VIEW rw_view1 AS
+  SELECT person FROM base_tbl WHERE visibility = 'public';
+
+CREATE FUNCTION snoop(anyelement)
+RETURNS boolean AS
+$$
+BEGIN
+  RAISE NOTICE 'snooped value: %', $1;
+  RETURN true;
+END;
+$$
+LANGUAGE plpgsql COST 0.000001;
+
+CREATE OR REPLACE FUNCTION leakproof(anyelement)
+RETURNS boolean AS
+$$
+BEGIN
+  RETURN true;
+END;
+$$
+LANGUAGE plpgsql STRICT IMMUTABLE LEAKPROOF;
+
+SELECT * FROM rw_view1 WHERE snoop(person);
+UPDATE rw_view1 SET person=person WHERE snoop(person);
+DELETE FROM rw_view1 WHERE NOT snoop(person);
+
+ALTER VIEW rw_view1 SET (security_barrier = true);
+
+SELECT table_name, is_insertable_into
+  FROM information_schema.tables
+ WHERE table_name = 'rw_view1';
+
+SELECT table_name, is_updatable, is_insertable_into
+  FROM information_schema.views
+ WHERE table_name = 'rw_view1';
+
+SELECT table_name, column_name, is_updatable
+  FROM information_schema.columns
+ WHERE table_name = 'rw_view1'
+ ORDER BY ordinal_position;
+
+SELECT * FROM rw_view1 WHERE snoop(person);
+UPDATE rw_view1 SET person=person WHERE snoop(person);
+DELETE FROM rw_view1 WHERE NOT snoop(person);
+
+EXPLAIN (costs off) SELECT * FROM rw_view1 WHERE snoop(person);
+EXPLAIN (costs off) UPDATE rw_view1 SET person=person WHERE snoop(person);
+EXPLAIN (costs off) DELETE FROM rw_view1 WHERE NOT snoop(person);
+
+-- security barrier view on top of security barrier view
+
+CREATE VIEW rw_view2 WITH (security_barrier = true) AS
+  SELECT * FROM rw_view1 WHERE snoop(person);
+
+SELECT table_name, is_insertable_into
+  FROM information_schema.tables
+ WHERE table_name = 'rw_view2';
+
+SELECT table_name, is_updatable, is_insertable_into
+  FROM information_schema.views
+ WHERE table_name = 'rw_view2';
+
+SELECT table_name, column_name, is_updatable
+  FROM information_schema.columns
+ WHERE table_name = 'rw_view2'
+ ORDER BY ordinal_position;
+
+SELECT * FROM rw_view2 WHERE snoop(person);
+UPDATE rw_view2 SET person=person WHERE snoop(person);
+DELETE FROM rw_view2 WHERE NOT snoop(person);
+
+EXPLAIN (costs off) SELECT * FROM rw_view2 WHERE snoop(person);
+EXPLAIN (costs off) UPDATE rw_view2 SET person=person WHERE snoop(person);
+EXPLAIN (costs off) DELETE FROM rw_view2 WHERE NOT snoop(person);
+
+DROP TABLE base_tbl CASCADE;
+
+-- security barrier view on top of table with rules
+
+CREATE TABLE base_tbl(id int PRIMARY KEY, data text, deleted boolean);
+INSERT INTO base_tbl VALUES (1, 'Row 1', false), (2, 'Row 2', true);
+
+CREATE RULE base_tbl_ins_rule AS ON INSERT TO base_tbl
+  WHERE EXISTS (SELECT 1 FROM base_tbl t WHERE t.id = new.id)
+  DO INSTEAD
+    UPDATE base_tbl SET data = new.data, deleted = false WHERE id = new.id;
+
+CREATE RULE base_tbl_del_rule AS ON DELETE TO base_tbl
+  DO INSTEAD
+    UPDATE base_tbl SET deleted = true WHERE id = old.id;
+
+CREATE VIEW rw_view1 WITH (security_barrier=true) AS
+  SELECT id, data FROM base_tbl WHERE NOT deleted;
+
+SELECT * FROM rw_view1;
+
+EXPLAIN (costs off) DELETE FROM rw_view1 WHERE id = 1 AND snoop(data);
+DELETE FROM rw_view1 WHERE id = 1 AND snoop(data);
+
+EXPLAIN (costs off) INSERT INTO rw_view1 VALUES (2, 'New row 2');
+INSERT INTO rw_view1 VALUES (2, 'New row 2');
+
+SELECT * FROM base_tbl;
+
+DROP TABLE base_tbl CASCADE;
+
+-- security barrier view based on inheiritance set
+CREATE TABLE t1 (a int, b float, c text);
+CREATE INDEX t1_a_idx ON t1(a);
+INSERT INTO t1
+SELECT i,i,'t1' FROM generate_series(1,10) g(i);
+
+CREATE TABLE t11 (d text) INHERITS (t1);
+CREATE INDEX t11_a_idx ON t11(a);
+INSERT INTO t11
+SELECT i,i,'t11','t11d' FROM generate_series(1,10) g(i);
+
+CREATE TABLE t12 (e int[]) INHERITS (t1);
+CREATE INDEX t12_a_idx ON t12(a);
+INSERT INTO t12
+SELECT i,i,'t12','{1,2}'::int[] FROM generate_series(1,10) g(i);
+
+CREATE TABLE t111 () INHERITS (t11, t12);
+CREATE INDEX t111_a_idx ON t111(a);
+INSERT INTO t111
+SELECT i,i,'t111','t111d','{1,1,1}'::int[] FROM generate_series(1,10) g(i);
+
+CREATE VIEW v1 WITH (security_barrier=true) AS
+SELECT *, (SELECT d FROM t11 WHERE t11.a = t1.a LIMIT 1) AS d
+FROM t1
+WHERE a > 5 AND EXISTS(SELECT 1 FROM t12 WHERE t12.a = t1.a);
+
+SELECT * FROM v1 WHERE a=3; -- should not see anything
+SELECT * FROM v1 WHERE a=8;
+
+EXPLAIN (VERBOSE, COSTS OFF)
+UPDATE v1 SET a=100 WHERE snoop(a) AND leakproof(a) AND a = 3;
+UPDATE v1 SET a=100 WHERE snoop(a) AND leakproof(a) AND a = 3;
+
+SELECT * FROM v1 WHERE a=100; -- Nothing should have been changed to 100
+SELECT * FROM t1 WHERE a=100; -- Nothing should have been changed to 100
+
+EXPLAIN (VERBOSE, COSTS OFF)
+UPDATE v1 SET a=a+1 WHERE snoop(a) AND leakproof(a) AND a = 8;
+UPDATE v1 SET a=a+1 WHERE snoop(a) AND leakproof(a) AND a = 8;
+
+SELECT * FROM v1 WHERE b=8;
+
+DELETE FROM v1 WHERE snoop(a) AND leakproof(a); -- should not delete everything, just where a>5
+
+TABLE t1; -- verify all a<=5 are intact
+
+DROP TABLE t1, t11, t12, t111 CASCADE;
+DROP FUNCTION snoop(anyelement);
+DROP FUNCTION leakproof(anyelement);