path: root/meta-oe/recipes-dbs/postgresql/files/CVE-2022-2625.patch

From 84375c1db25ef650902cf80712495fc514b0ff63 Mon Sep 17 00:00:00 2001
From: Hitendra Prajapati <hprajapati@mvista.com>
Date: Thu, 13 Oct 2022 10:35:32 +0530
Subject: [PATCH] CVE-2022-2625

Upstream-Status: Backport [https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=5579726bd60a6e7afb04a3548bced348cd5ffd89]
CVE: CVE-2022-2625
Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
---
 doc/src/sgml/extend.sgml                      |  11 --
 src/backend/catalog/pg_collation.c            |  49 ++++--
 src/backend/catalog/pg_depend.c               |  74 ++++++++-
 src/backend/catalog/pg_operator.c             |   2 +-
 src/backend/catalog/pg_type.c                 |   7 +-
 src/backend/commands/createas.c               |  18 ++-
 src/backend/commands/foreigncmds.c            |  19 ++-
 src/backend/commands/schemacmds.c             |  25 ++-
 src/backend/commands/sequence.c               |   8 +
 src/backend/commands/statscmds.c              |   4 +
 src/backend/commands/view.c                   |  16 +-
 src/backend/parser/parse_utilcmd.c            |  10 ++
 src/include/catalog/dependency.h              |   2 +
 src/test/modules/test_extensions/Makefile     |   5 +-
 .../expected/test_extensions.out              | 153 ++++++++++++++++++
 .../test_extensions/sql/test_extensions.sql   | 110 +++++++++++++
 .../test_ext_cine--1.0--1.1.sql               |  26 +++
 .../test_extensions/test_ext_cine--1.0.sql    |  25 +++
 .../test_extensions/test_ext_cine.control     |   3 +
 .../test_extensions/test_ext_cor--1.0.sql     |  20 +++
 .../test_extensions/test_ext_cor.control      |   3 +
 21 files changed, 540 insertions(+), 50 deletions(-)
 create mode 100644 src/test/modules/test_extensions/test_ext_cine--1.0--1.1.sql
 create mode 100644 src/test/modules/test_extensions/test_ext_cine--1.0.sql
 create mode 100644 src/test/modules/test_extensions/test_ext_cine.control
 create mode 100644 src/test/modules/test_extensions/test_ext_cor--1.0.sql
 create mode 100644 src/test/modules/test_extensions/test_ext_cor.control

diff --git a/doc/src/sgml/extend.sgml b/doc/src/sgml/extend.sgml
index 53f2638..bcc7a80 100644
--- a/doc/src/sgml/extend.sgml
+++ b/doc/src/sgml/extend.sgml
@@ -1109,17 +1109,6 @@ SELECT * FROM pg_extension_update_paths('<replaceable>extension_name</replaceabl
       <varname>search_path</varname>.  However, no mechanism currently exists
       to require that.
      </para>
-
-     <para>
-      Do <emphasis>not</emphasis> use <command>CREATE OR REPLACE
-      FUNCTION</command>, except in an update script that must change the
-      definition of a function that is known to be an extension member
-      already.  (Likewise for other <literal>OR REPLACE</literal> options.)
-      Using <literal>OR REPLACE</literal> unnecessarily not only has a risk
-      of accidentally overwriting someone else's function, but it creates a
-      security hazard since the overwritten function would still be owned by
-      its original owner, who could modify it.
-     </para>
     </sect3>
    </sect2>
 
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index dd99d53..ba4c3ef 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -78,15 +78,25 @@ CollationCreate(const char *collname, Oid collnamespace,
 	 * friendlier error message.  The unique index provides a backstop against
 	 * race conditions.
 	 */
-	if (SearchSysCacheExists3(COLLNAMEENCNSP,
-							  PointerGetDatum(collname),
-							  Int32GetDatum(collencoding),
-							  ObjectIdGetDatum(collnamespace)))
+	oid = GetSysCacheOid3(COLLNAMEENCNSP,
+						  Anum_pg_collation_oid,
+						  PointerGetDatum(collname),
+						  Int32GetDatum(collencoding),
+						  ObjectIdGetDatum(collnamespace));
+	if (OidIsValid(oid))
 	{
 		if (quiet)
 			return InvalidOid;
 		else if (if_not_exists)
 		{
+			/*
+			 * If we are in an extension script, insist that the pre-existing
+			 * object be a member of the extension, to avoid security risks.
+			 */
+			ObjectAddressSet(myself, CollationRelationId, oid);
+			checkMembershipInCurrentExtension(&myself);
+
+			/* OK to skip */
 			ereport(NOTICE,
 					(errcode(ERRCODE_DUPLICATE_OBJECT),
 					 collencoding == -1
@@ -116,16 +126,19 @@ CollationCreate(const char *collname, Oid collnamespace,
 	 * so we take a ShareRowExclusiveLock earlier, to protect against
 	 * concurrent changes fooling this check.
 	 */
-	if ((collencoding == -1 &&
-		 SearchSysCacheExists3(COLLNAMEENCNSP,
-							   PointerGetDatum(collname),
-							   Int32GetDatum(GetDatabaseEncoding()),
-							   ObjectIdGetDatum(collnamespace))) ||
-		(collencoding != -1 &&
-		 SearchSysCacheExists3(COLLNAMEENCNSP,
-							   PointerGetDatum(collname),
-							   Int32GetDatum(-1),
-							   ObjectIdGetDatum(collnamespace))))
+	if (collencoding == -1)
+		oid = GetSysCacheOid3(COLLNAMEENCNSP,
+							  Anum_pg_collation_oid,
+							  PointerGetDatum(collname),
+							  Int32GetDatum(GetDatabaseEncoding()),
+							  ObjectIdGetDatum(collnamespace));
+	else
+		oid = GetSysCacheOid3(COLLNAMEENCNSP,
+							  Anum_pg_collation_oid,
+							  PointerGetDatum(collname),
+							  Int32GetDatum(-1),
+							  ObjectIdGetDatum(collnamespace));
+	if (OidIsValid(oid))
 	{
 		if (quiet)
 		{
@@ -134,6 +147,14 @@ CollationCreate(const char *collname, Oid collnamespace,
 		}
 		else if (if_not_exists)
 		{
+			/*
+			 * If we are in an extension script, insist that the pre-existing
+			 * object be a member of the extension, to avoid security risks.
+			 */
+			ObjectAddressSet(myself, CollationRelationId, oid);
+			checkMembershipInCurrentExtension(&myself);
+
+			/* OK to skip */
 			table_close(rel, NoLock);
 			ereport(NOTICE,
 					(errcode(ERRCODE_DUPLICATE_OBJECT),
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index 9ffadbb..71c7cef 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -124,15 +124,23 @@ recordMultipleDependencies(const ObjectAddress *depender,
 
 /*
  * If we are executing a CREATE EXTENSION operation, mark the given object
- * as being a member of the extension.  Otherwise, do nothing.
+ * as being a member of the extension, or check that it already is one.
+ * Otherwise, do nothing.
  *
  * This must be called during creation of any user-definable object type
  * that could be a member of an extension.
  *
- * If isReplace is true, the object already existed (or might have already
- * existed), so we must check for a pre-existing extension membership entry.
- * Passing false is a guarantee that the object is newly created, and so
- * could not already be a member of any extension.
+ * isReplace must be true if the object already existed, and false if it is
+ * newly created.  In the former case we insist that it already be a member
+ * of the current extension.  In the latter case we can skip checking whether
+ * it is already a member of any extension.
+ *
+ * Note: isReplace = true is typically used when updating a object in
+ * CREATE OR REPLACE and similar commands.  We used to allow the target
+ * object to not already be an extension member, instead silently absorbing
+ * it into the current extension.  However, this was both error-prone
+ * (extensions might accidentally overwrite free-standing objects) and
+ * a security hazard (since the object would retain its previous ownership).
  */
 void
 recordDependencyOnCurrentExtension(const ObjectAddress *object,
@@ -150,6 +158,12 @@ recordDependencyOnCurrentExtension(const ObjectAddress *object,
 		{
 			Oid			oldext;
 
+			/*
+			 * Side note: these catalog lookups are safe only because the
+			 * object is a pre-existing one.  In the not-isReplace case, the
+			 * caller has most likely not yet done a CommandCounterIncrement
+			 * that would make the new object visible.
+			 */
 			oldext = getExtensionOfObject(object->classId, object->objectId);
 			if (OidIsValid(oldext))
 			{
@@ -163,6 +177,13 @@ recordDependencyOnCurrentExtension(const ObjectAddress *object,
 								getObjectDescription(object),
 								get_extension_name(oldext))));
 			}
+			/* It's a free-standing object, so reject */
+			ereport(ERROR,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("%s is not a member of extension \"%s\"",
+							getObjectDescription(object),
+							get_extension_name(CurrentExtensionObject)),
+					 errdetail("An extension is not allowed to replace an object that it does not own.")));
 		}
 
 		/* OK, record it as a member of CurrentExtensionObject */
@@ -174,6 +195,49 @@ recordDependencyOnCurrentExtension(const ObjectAddress *object,
 	}
 }
 
+/*
+ * If we are executing a CREATE EXTENSION operation, check that the given
+ * object is a member of the extension, and throw an error if it isn't.
+ * Otherwise, do nothing.
+ *
+ * This must be called whenever a CREATE IF NOT EXISTS operation (for an
+ * object type that can be an extension member) has found that an object of
+ * the desired name already exists.  It is insecure for an extension to use
+ * IF NOT EXISTS except when the conflicting object is already an extension
+ * member; otherwise a hostile user could substitute an object with arbitrary
+ * properties.
+ */
+void
+checkMembershipInCurrentExtension(const ObjectAddress *object)
+{
+	/*
+	 * This is actually the same condition tested in
+	 * recordDependencyOnCurrentExtension; but we want to issue a
+	 * differently-worded error, and anyway it would be pretty confusing to
+	 * call recordDependencyOnCurrentExtension in these circumstances.
+	 */
+
+	/* Only whole objects can be extension members */
+	Assert(object->objectSubId == 0);
+
+	if (creating_extension)
+	{
+		Oid			oldext;
+
+		oldext = getExtensionOfObject(object->classId, object->objectId);
+		/* If already a member of this extension, OK */
+		if (oldext == CurrentExtensionObject)
+			return;
+		/* Else complain */
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("%s is not a member of extension \"%s\"",
+						getObjectDescription(object),
+						get_extension_name(CurrentExtensionObject)),
+				 errdetail("An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.")));
+	}
+}
+
 /*
  * deleteDependencyRecordsFor -- delete all records with given depender
  * classId/objectId.  Returns the number of records deleted.
diff --git a/src/backend/catalog/pg_operator.c b/src/backend/catalog/pg_operator.c
index bcaa26c..84784e6 100644
--- a/src/backend/catalog/pg_operator.c
+++ b/src/backend/catalog/pg_operator.c
@@ -867,7 +867,7 @@ makeOperatorDependencies(HeapTuple tuple, bool isUpdate)
 							oper->oprowner);
 
 	/* Dependency on extension */
-	recordDependencyOnCurrentExtension(&myself, true);
+	recordDependencyOnCurrentExtension(&myself, isUpdate);
 
 	return myself;
 }
diff --git a/src/backend/catalog/pg_type.c b/src/backend/catalog/pg_type.c
index 2a51501..3ff017f 100644
--- a/src/backend/catalog/pg_type.c
+++ b/src/backend/catalog/pg_type.c
@@ -528,10 +528,9 @@ TypeCreate(Oid newTypeOid,
  * If rebuild is true, we remove existing dependencies and rebuild them
  * from scratch.  This is needed for ALTER TYPE, and also when replacing
  * a shell type.  We don't remove an existing extension dependency, though.
- * (That means an extension can't absorb a shell type created in another
- * extension, nor ALTER a type created by another extension.  Also, if it
- * replaces a free-standing shell type or ALTERs a free-standing type,
- * that type will become a member of the extension.)
+ * That means an extension can't absorb a shell type that is free-standing
+ * or belongs to another extension, nor ALTER a type that is free-standing or
+ * belongs to another extension.
  */
 void
 GenerateTypeDependencies(Oid typeObjectId,
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 4c1d909..a68d945 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -243,15 +243,27 @@ ExecCreateTableAs(CreateTableAsStmt *stmt, const char *queryString,
 	if (stmt->if_not_exists)
 	{
 		Oid			nspid;
+		Oid			oldrelid;
 
-		nspid = RangeVarGetCreationNamespace(stmt->into->rel);
+		nspid = RangeVarGetCreationNamespace(into->rel);
 
-		if (get_relname_relid(stmt->into->rel->relname, nspid))
+		oldrelid = get_relname_relid(into->rel->relname, nspid);
+		if (OidIsValid(oldrelid))
 		{
+			/*
+			 * The relation exists and IF NOT EXISTS has been specified.
+			 *
+			 * If we are in an extension script, insist that the pre-existing
+			 * object be a member of the extension, to avoid security risks.
+			 */
+			ObjectAddressSet(address, RelationRelationId, oldrelid);
+			checkMembershipInCurrentExtension(&address);
+
+			/* OK to skip */
 			ereport(NOTICE,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists, skipping",
-							stmt->into->rel->relname)));
+							into->rel->relname)));
 			return InvalidObjectAddress;
 		}
 	}
diff --git a/src/backend/commands/foreigncmds.c b/src/backend/commands/foreigncmds.c
index d7bc6e3..bc583c6 100644
--- a/src/backend/commands/foreigncmds.c
+++ b/src/backend/commands/foreigncmds.c
@@ -887,13 +887,22 @@ CreateForeignServer(CreateForeignServerStmt *stmt)
 	ownerId = GetUserId();
 
 	/*
-	 * Check that there is no other foreign server by this name. Do nothing if
-	 * IF NOT EXISTS was enforced.
+	 * Check that there is no other foreign server by this name.  If there is
+	 * one, do nothing if IF NOT EXISTS was specified.
 	 */
-	if (GetForeignServerByName(stmt->servername, true) != NULL)
+	srvId = get_foreign_server_oid(stmt->servername, true);
+	if (OidIsValid(srvId))
 	{
 		if (stmt->if_not_exists)
 		{
+			/*
+			 * If we are in an extension script, insist that the pre-existing
+			 * object be a member of the extension, to avoid security risks.
+			 */
+			ObjectAddressSet(myself, ForeignServerRelationId, srvId);
+			checkMembershipInCurrentExtension(&myself);
+
+			/* OK to skip */
 			ereport(NOTICE,
 					(errcode(ERRCODE_DUPLICATE_OBJECT),
 					 errmsg("server \"%s\" already exists, skipping",
@@ -1182,6 +1191,10 @@ CreateUserMapping(CreateUserMappingStmt *stmt)
 	{
 		if (stmt->if_not_exists)
 		{
+			/*
+			 * Since user mappings aren't members of extensions (see comments
+			 * below), no need for checkMembershipInCurrentExtension here.
+			 */
 			ereport(NOTICE,
 					(errcode(ERRCODE_DUPLICATE_OBJECT),
 					 errmsg("user mapping for \"%s\" already exists for server \"%s\", skipping",
diff --git a/src/backend/commands/schemacmds.c b/src/backend/commands/schemacmds.c
index 6cf94a3..6bc4edc 100644
--- a/src/backend/commands/schemacmds.c
+++ b/src/backend/commands/schemacmds.c
@@ -113,14 +113,25 @@ CreateSchemaCommand(CreateSchemaStmt *stmt, const char *queryString,
 	 * the permissions checks, but since CREATE TABLE IF NOT EXISTS makes its
 	 * creation-permission check first, we do likewise.
 	 */
-	if (stmt->if_not_exists &&
-		SearchSysCacheExists1(NAMESPACENAME, PointerGetDatum(schemaName)))
+	if (stmt->if_not_exists)
 	{
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_SCHEMA),
-				 errmsg("schema \"%s\" already exists, skipping",
-						schemaName)));
-		return InvalidOid;
+		namespaceId = get_namespace_oid(schemaName, true);
+		if (OidIsValid(namespaceId))
+		{
+			/*
+			 * If we are in an extension script, insist that the pre-existing
+			 * object be a member of the extension, to avoid security risks.
+			 */
+			ObjectAddressSet(address, NamespaceRelationId, namespaceId);
+			checkMembershipInCurrentExtension(&address);
+
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_SCHEMA),
+					 errmsg("schema \"%s\" already exists, skipping",
+							schemaName)));
+			return InvalidOid;
+		}
 	}
 
 	/*
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index 0960b33..0577184 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -149,6 +149,14 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 		RangeVarGetAndCheckCreationNamespace(seq->sequence, NoLock, &seqoid);
 		if (OidIsValid(seqoid))
 		{
+			/*
+			 * If we are in an extension script, insist that the pre-existing
+			 * object be a member of the extension, to avoid security risks.
+			 */
+			ObjectAddressSet(address, RelationRelationId, seqoid);
+			checkMembershipInCurrentExtension(&address);
+
+			/* OK to skip */
 			ereport(NOTICE,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists, skipping",
diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index 5678d31..409cf28 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -173,6 +173,10 @@ CreateStatistics(CreateStatsStmt *stmt)
 	{
 		if (stmt->if_not_exists)
 		{
+			/*
+			 * Since stats objects aren't members of extensions (see comments
+			 * below), no need for checkMembershipInCurrentExtension here.
+			 */
 			ereport(NOTICE,
 					(errcode(ERRCODE_DUPLICATE_OBJECT),
 					 errmsg("statistics object \"%s\" already exists, skipping",
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 87ed453..dd7cc97 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -205,7 +205,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		CommandCounterIncrement();
 
 		/*
-		 * Finally update the view options.
+		 * Update the view's options.
 		 *
 		 * The new options list replaces the existing options list, even if
 		 * it's empty.
@@ -218,8 +218,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
 		AlterTableInternal(viewOid, atcmds, true);
 
+		/*
+		 * There is very little to do here to update the view's dependencies.
+		 * Most view-level dependency relationships, such as those on the
+		 * owner, schema, and associated composite type, aren't changing.
+		 * Because we don't allow changing type or collation of an existing
+		 * view column, those dependencies of the existing columns don't
+		 * change either, while the AT_AddColumnToView machinery took care of
+		 * adding such dependencies for new view columns.  The dependencies of
+		 * the view's query could have changed arbitrarily, but that was dealt
+		 * with inside StoreViewQuery.  What remains is only to check that
+		 * view replacement is allowed when we're creating an extension.
+		 */
 		ObjectAddressSet(address, RelationRelationId, viewOid);
 
+		recordDependencyOnCurrentExtension(&address, true);
+
 		/*
 		 * Seems okay, so return the OID of the pre-existing view.
 		 */
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 44aa38a..8f4d940 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -206,6 +206,16 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	 */
 	if (stmt->if_not_exists && OidIsValid(existing_relid))
 	{
+		/*
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddress address;
+
+		ObjectAddressSet(address, RelationRelationId, existing_relid);
+		checkMembershipInCurrentExtension(&address);
+
+		/* OK to skip */
 		ereport(NOTICE,
 				(errcode(ERRCODE_DUPLICATE_TABLE),
 				 errmsg("relation \"%s\" already exists, skipping",
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index 8b1e3aa..27c7509 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -201,6 +201,8 @@ extern void recordMultipleDependencies(const ObjectAddress *depender,
 extern void recordDependencyOnCurrentExtension(const ObjectAddress *object,
 											   bool isReplace);
 
+extern void checkMembershipInCurrentExtension(const ObjectAddress *object);
+
 extern long deleteDependencyRecordsFor(Oid classId, Oid objectId,
 									   bool skipExtensionDeps);
 
diff --git a/src/test/modules/test_extensions/Makefile b/src/test/modules/test_extensions/Makefile
index d18108e..7428f15 100644
--- a/src/test/modules/test_extensions/Makefile
+++ b/src/test/modules/test_extensions/Makefile
@@ -4,10 +4,13 @@ MODULE = test_extensions
 PGFILEDESC = "test_extensions - regression testing for EXTENSION support"
 
 EXTENSION = test_ext1 test_ext2 test_ext3 test_ext4 test_ext5 test_ext6 \
-            test_ext7 test_ext8 test_ext_cyclic1 test_ext_cyclic2
+            test_ext7 test_ext8 test_ext_cine test_ext_cor \
+            test_ext_cyclic1 test_ext_cyclic2
 DATA = test_ext1--1.0.sql test_ext2--1.0.sql test_ext3--1.0.sql \
        test_ext4--1.0.sql test_ext5--1.0.sql test_ext6--1.0.sql \
        test_ext7--1.0.sql test_ext7--1.0--2.0.sql test_ext8--1.0.sql \
+       test_ext_cine--1.0.sql test_ext_cine--1.0--1.1.sql \
+       test_ext_cor--1.0.sql \
        test_ext_cyclic1--1.0.sql test_ext_cyclic2--1.0.sql
 
 REGRESS = test_extensions test_extdepend
diff --git a/src/test/modules/test_extensions/expected/test_extensions.out b/src/test/modules/test_extensions/expected/test_extensions.out
index b5cbdfc..1e91640 100644
--- a/src/test/modules/test_extensions/expected/test_extensions.out
+++ b/src/test/modules/test_extensions/expected/test_extensions.out
@@ -154,3 +154,156 @@ DROP TABLE test_ext4_tab;
 DROP FUNCTION create_extension_with_temp_schema();
 RESET client_min_messages;
 \unset SHOW_CONTEXT
+-- It's generally bad style to use CREATE OR REPLACE unnecessarily.
+-- Test what happens if an extension does it anyway.
+-- Replacing a shell type or operator is sort of like CREATE OR REPLACE;
+-- check that too.
+CREATE FUNCTION ext_cor_func() RETURNS text
+  AS $$ SELECT 'ext_cor_func: original'::text $$ LANGUAGE sql;
+CREATE EXTENSION test_ext_cor;  -- fail
+ERROR:  function ext_cor_func() is not a member of extension "test_ext_cor"
+DETAIL:  An extension is not allowed to replace an object that it does not own.
+SELECT ext_cor_func();
+      ext_cor_func      
+------------------------
+ ext_cor_func: original
+(1 row)
+
+DROP FUNCTION ext_cor_func();
+CREATE VIEW ext_cor_view AS
+  SELECT 'ext_cor_view: original'::text AS col;
+CREATE EXTENSION test_ext_cor;  -- fail
+ERROR:  view ext_cor_view is not a member of extension "test_ext_cor"
+DETAIL:  An extension is not allowed to replace an object that it does not own.
+SELECT ext_cor_func();
+ERROR:  function ext_cor_func() does not exist
+LINE 1: SELECT ext_cor_func();
+               ^
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+SELECT * FROM ext_cor_view;
+          col           
+------------------------
+ ext_cor_view: original
+(1 row)
+
+DROP VIEW ext_cor_view;
+CREATE TYPE test_ext_type;
+CREATE EXTENSION test_ext_cor;  -- fail
+ERROR:  type test_ext_type is not a member of extension "test_ext_cor"
+DETAIL:  An extension is not allowed to replace an object that it does not own.
+DROP TYPE test_ext_type;
+-- this makes a shell "point <<@@ polygon" operator too
+CREATE OPERATOR @@>> ( PROCEDURE = poly_contain_pt,
+  LEFTARG = polygon, RIGHTARG = point,
+  COMMUTATOR = <<@@ );
+CREATE EXTENSION test_ext_cor;  -- fail
+ERROR:  operator <<@@(point,polygon) is not a member of extension "test_ext_cor"
+DETAIL:  An extension is not allowed to replace an object that it does not own.
+DROP OPERATOR <<@@ (point, polygon);
+CREATE EXTENSION test_ext_cor;  -- now it should work
+SELECT ext_cor_func();
+         ext_cor_func         
+------------------------------
+ ext_cor_func: from extension
+(1 row)
+
+SELECT * FROM ext_cor_view;
+             col              
+------------------------------
+ ext_cor_view: from extension
+(1 row)
+
+SELECT 'x'::test_ext_type;
+ test_ext_type 
+---------------
+ x
+(1 row)
+
+SELECT point(0,0) <<@@ polygon(circle(point(0,0),1));
+ ?column? 
+----------
+ t
+(1 row)
+
+\dx+ test_ext_cor
+Objects in extension "test_ext_cor"
+      Object description      
+------------------------------
+ function ext_cor_func()
+ operator <<@@(point,polygon)
+ type test_ext_type
+ view ext_cor_view
+(4 rows)
+
+--
+-- CREATE IF NOT EXISTS is an entirely unsound thing for an extension
+-- to be doing, but let's at least plug the major security hole in it.
+--
+CREATE COLLATION ext_cine_coll
+  ( LC_COLLATE = "C", LC_CTYPE = "C" );
+CREATE EXTENSION test_ext_cine;  -- fail
+ERROR:  collation ext_cine_coll is not a member of extension "test_ext_cine"
+DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
+DROP COLLATION ext_cine_coll;
+CREATE MATERIALIZED VIEW ext_cine_mv AS SELECT 11 AS f1;
+CREATE EXTENSION test_ext_cine;  -- fail
+ERROR:  materialized view ext_cine_mv is not a member of extension "test_ext_cine"
+DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
+DROP MATERIALIZED VIEW ext_cine_mv;
+CREATE FOREIGN DATA WRAPPER dummy;
+CREATE SERVER ext_cine_srv FOREIGN DATA WRAPPER dummy;
+CREATE EXTENSION test_ext_cine;  -- fail
+ERROR:  server ext_cine_srv is not a member of extension "test_ext_cine"
+DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
+DROP SERVER ext_cine_srv;
+CREATE SCHEMA ext_cine_schema;
+CREATE EXTENSION test_ext_cine;  -- fail
+ERROR:  schema ext_cine_schema is not a member of extension "test_ext_cine"
+DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
+DROP SCHEMA ext_cine_schema;
+CREATE SEQUENCE ext_cine_seq;
+CREATE EXTENSION test_ext_cine;  -- fail
+ERROR:  sequence ext_cine_seq is not a member of extension "test_ext_cine"
+DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
+DROP SEQUENCE ext_cine_seq;
+CREATE TABLE ext_cine_tab1 (x int);
+CREATE EXTENSION test_ext_cine;  -- fail
+ERROR:  table ext_cine_tab1 is not a member of extension "test_ext_cine"
+DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
+DROP TABLE ext_cine_tab1;
+CREATE TABLE ext_cine_tab2 AS SELECT 42 AS y;
+CREATE EXTENSION test_ext_cine;  -- fail
+ERROR:  table ext_cine_tab2 is not a member of extension "test_ext_cine"
+DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
+DROP TABLE ext_cine_tab2;
+CREATE EXTENSION test_ext_cine;
+\dx+ test_ext_cine
+Objects in extension "test_ext_cine"
+        Object description         
+-----------------------------------
+ collation ext_cine_coll
+ foreign-data wrapper ext_cine_fdw
+ materialized view ext_cine_mv
+ schema ext_cine_schema
+ sequence ext_cine_seq
+ server ext_cine_srv
+ table ext_cine_tab1
+ table ext_cine_tab2
+(8 rows)
+
+ALTER EXTENSION test_ext_cine UPDATE TO '1.1';
+\dx+ test_ext_cine
+Objects in extension "test_ext_cine"
+        Object description         
+-----------------------------------
+ collation ext_cine_coll
+ foreign-data wrapper ext_cine_fdw
+ materialized view ext_cine_mv
+ schema ext_cine_schema
+ sequence ext_cine_seq
+ server ext_cine_srv
+ table ext_cine_tab1
+ table ext_cine_tab2
+ table ext_cine_tab3
+(9 rows)
+
diff --git a/src/test/modules/test_extensions/sql/test_extensions.sql b/src/test/modules/test_extensions/sql/test_extensions.sql
index f505466..b3d4579 100644
--- a/src/test/modules/test_extensions/sql/test_extensions.sql
+++ b/src/test/modules/test_extensions/sql/test_extensions.sql
@@ -93,3 +93,113 @@ DROP TABLE test_ext4_tab;
 DROP FUNCTION create_extension_with_temp_schema();
 RESET client_min_messages;
 \unset SHOW_CONTEXT
+
+-- It's generally bad style to use CREATE OR REPLACE unnecessarily.
+-- Test what happens if an extension does it anyway.
+-- Replacing a shell type or operator is sort of like CREATE OR REPLACE;
+-- check that too.
+
+CREATE FUNCTION ext_cor_func() RETURNS text
+  AS $$ SELECT 'ext_cor_func: original'::text $$ LANGUAGE sql;
+
+CREATE EXTENSION test_ext_cor;  -- fail
+
+SELECT ext_cor_func();
+
+DROP FUNCTION ext_cor_func();
+
+CREATE VIEW ext_cor_view AS
+  SELECT 'ext_cor_view: original'::text AS col;
+
+CREATE EXTENSION test_ext_cor;  -- fail
+
+SELECT ext_cor_func();
+
+SELECT * FROM ext_cor_view;
+
+DROP VIEW ext_cor_view;
+
+CREATE TYPE test_ext_type;
+
+CREATE EXTENSION test_ext_cor;  -- fail
+
+DROP TYPE test_ext_type;
+
+-- this makes a shell "point <<@@ polygon" operator too
+CREATE OPERATOR @@>> ( PROCEDURE = poly_contain_pt,
+  LEFTARG = polygon, RIGHTARG = point,
+  COMMUTATOR = <<@@ );
+
+CREATE EXTENSION test_ext_cor;  -- fail
+
+DROP OPERATOR <<@@ (point, polygon);
+
+CREATE EXTENSION test_ext_cor;  -- now it should work
+
+SELECT ext_cor_func();
+
+SELECT * FROM ext_cor_view;
+
+SELECT 'x'::test_ext_type;
+
+SELECT point(0,0) <<@@ polygon(circle(point(0,0),1));
+
+\dx+ test_ext_cor
+
+--
+-- CREATE IF NOT EXISTS is an entirely unsound thing for an extension
+-- to be doing, but let's at least plug the major security hole in it.
+--
+
+CREATE COLLATION ext_cine_coll
+  ( LC_COLLATE = "C", LC_CTYPE = "C" );
+
+CREATE EXTENSION test_ext_cine;  -- fail
+
+DROP COLLATION ext_cine_coll;
+
+CREATE MATERIALIZED VIEW ext_cine_mv AS SELECT 11 AS f1;
+
+CREATE EXTENSION test_ext_cine;  -- fail
+
+DROP MATERIALIZED VIEW ext_cine_mv;
+
+CREATE FOREIGN DATA WRAPPER dummy;
+
+CREATE SERVER ext_cine_srv FOREIGN DATA WRAPPER dummy;
+
+CREATE EXTENSION test_ext_cine;  -- fail
+
+DROP SERVER ext_cine_srv;
+
+CREATE SCHEMA ext_cine_schema;
+
+CREATE EXTENSION test_ext_cine;  -- fail
+
+DROP SCHEMA ext_cine_schema;
+
+CREATE SEQUENCE ext_cine_seq;
+
+CREATE EXTENSION test_ext_cine;  -- fail
+
+DROP SEQUENCE ext_cine_seq;
+
+CREATE TABLE ext_cine_tab1 (x int);
+
+CREATE EXTENSION test_ext_cine;  -- fail
+
+DROP TABLE ext_cine_tab1;
+
+CREATE TABLE ext_cine_tab2 AS SELECT 42 AS y;
+
+CREATE EXTENSION test_ext_cine;  -- fail
+
+DROP TABLE ext_cine_tab2;
+
+CREATE EXTENSION test_ext_cine;
+
+\dx+ test_ext_cine
+
+ALTER EXTENSION test_ext_cine UPDATE TO '1.1';
+
+\dx+ test_ext_cine
diff --git a/src/test/modules/test_extensions/test_ext_cine--1.0--1.1.sql b/src/test/modules/test_extensions/test_ext_cine--1.0--1.1.sql
new file mode 100644
index 0000000..6dadfd2
--- /dev/null
+++ b/src/test/modules/test_extensions/test_ext_cine--1.0--1.1.sql
@@ -0,0 +1,26 @@
+/* src/test/modules/test_extensions/test_ext_cine--1.0--1.1.sql */
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION test_ext_cine UPDATE TO '1.1'" to load this file. \quit
+
+--
+-- These are the same commands as in the 1.0 script; we expect them
+-- to do nothing.
+--
+
+CREATE COLLATION IF NOT EXISTS ext_cine_coll
+  ( LC_COLLATE = "POSIX", LC_CTYPE = "POSIX" );
+
+CREATE MATERIALIZED VIEW IF NOT EXISTS ext_cine_mv AS SELECT 42 AS f1;
+
+CREATE SERVER IF NOT EXISTS ext_cine_srv FOREIGN DATA WRAPPER ext_cine_fdw;
+
+CREATE SCHEMA IF NOT EXISTS ext_cine_schema;
+
+CREATE SEQUENCE IF NOT EXISTS ext_cine_seq;
+
+CREATE TABLE IF NOT EXISTS ext_cine_tab1 (x int);
+
+CREATE TABLE IF NOT EXISTS ext_cine_tab2 AS SELECT 42 AS y;
+
+-- just to verify the script ran
+CREATE TABLE ext_cine_tab3 (z int);
diff --git a/src/test/modules/test_extensions/test_ext_cine--1.0.sql b/src/test/modules/test_extensions/test_ext_cine--1.0.sql
new file mode 100644
index 0000000..01408ff
--- /dev/null
+++ b/src/test/modules/test_extensions/test_ext_cine--1.0.sql
@@ -0,0 +1,25 @@
+/* src/test/modules/test_extensions/test_ext_cine--1.0.sql */
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION test_ext_cine" to load this file. \quit
+
+--
+-- CREATE IF NOT EXISTS is an entirely unsound thing for an extension
+-- to be doing, but let's at least plug the major security hole in it.
+--
+
+CREATE COLLATION IF NOT EXISTS ext_cine_coll
+  ( LC_COLLATE = "POSIX", LC_CTYPE = "POSIX" );
+
+CREATE MATERIALIZED VIEW IF NOT EXISTS ext_cine_mv AS SELECT 42 AS f1;
+
+CREATE FOREIGN DATA WRAPPER ext_cine_fdw;
+
+CREATE SERVER IF NOT EXISTS ext_cine_srv FOREIGN DATA WRAPPER ext_cine_fdw;
+
+CREATE SCHEMA IF NOT EXISTS ext_cine_schema;
+
+CREATE SEQUENCE IF NOT EXISTS ext_cine_seq;
+
+CREATE TABLE IF NOT EXISTS ext_cine_tab1 (x int);
+
+CREATE TABLE IF NOT EXISTS ext_cine_tab2 AS SELECT 42 AS y;
diff --git a/src/test/modules/test_extensions/test_ext_cine.control b/src/test/modules/test_extensions/test_ext_cine.control
new file mode 100644
index 0000000..ced713b
--- /dev/null
+++ b/src/test/modules/test_extensions/test_ext_cine.control
@@ -0,0 +1,3 @@
+comment = 'Test extension using CREATE IF NOT EXISTS'
+default_version = '1.0'
+relocatable = true
diff --git a/src/test/modules/test_extensions/test_ext_cor--1.0.sql b/src/test/modules/test_extensions/test_ext_cor--1.0.sql
new file mode 100644
index 0000000..2e8d89c
--- /dev/null
+++ b/src/test/modules/test_extensions/test_ext_cor--1.0.sql
@@ -0,0 +1,20 @@
+/* src/test/modules/test_extensions/test_ext_cor--1.0.sql */
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION test_ext_cor" to load this file. \quit
+
+-- It's generally bad style to use CREATE OR REPLACE unnecessarily.
+-- Test what happens if an extension does it anyway.
+
+CREATE OR REPLACE FUNCTION ext_cor_func() RETURNS text
+  AS $$ SELECT 'ext_cor_func: from extension'::text $$ LANGUAGE sql;
+
+CREATE OR REPLACE VIEW ext_cor_view AS
+  SELECT 'ext_cor_view: from extension'::text AS col;
+
+-- These are for testing replacement of a shell type/operator, which works
+-- enough like an implicit OR REPLACE to be important to check.
+
+CREATE TYPE test_ext_type AS ENUM('x', 'y');
+
+CREATE OPERATOR <<@@ ( PROCEDURE = pt_contained_poly,
+  LEFTARG = point, RIGHTARG = polygon );
diff --git a/src/test/modules/test_extensions/test_ext_cor.control b/src/test/modules/test_extensions/test_ext_cor.control
new file mode 100644
index 0000000..0e972e5
--- /dev/null
+++ b/src/test/modules/test_extensions/test_ext_cor.control
@@ -0,0 +1,3 @@
+comment = 'Test extension using CREATE OR REPLACE'
+default_version = '1.0'
+relocatable = true
-- 
2.25.1