Require the schema qualification in pg_temp.type_name(arg).

Commit aa27977fe21a7dfa4da4376ad66ae37cb8f0d0b5 introduced this
restriction for pg_temp.function_name(arg); do likewise for types
created in temporary schemas.  Programs that this breaks should add
"pg_temp." schema qualification or switch to arg::type_name syntax.
Back-patch to 9.4 (all supported versions).

Reviewed by Tom Lane.  Reported by Tom Lane.

Security: CVE-2019-10208

4 files changed, 49 insertions, 5 deletions

diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index ac30f77f024..53ba8a3141a 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -753,13 +753,23 @@ RelationIsVisible(Oid relid)
 
 /*
  * TypenameGetTypid
+ *		Wrapper for binary compatibility.
+ */
+Oid
+TypenameGetTypid(const char *typname)
+{
+	return TypenameGetTypidExtended(typname, true);
+}
+
+/*
+ * TypenameGetTypidExtended
  *		Try to resolve an unqualified datatype name.
  *		Returns OID if type found in search path, else InvalidOid.
  *
  * This is essentially the same as RelnameGetRelid.
  */
 Oid
-TypenameGetTypid(const char *typname)
+TypenameGetTypidExtended(const char *typname, bool temp_ok)
 {
 	Oid			typid;
 	ListCell   *l;
@@ -770,6 +780,9 @@ TypenameGetTypid(const char *typname)
 	{
 		Oid			namespaceId = lfirst_oid(l);
 
+		if (!temp_ok && namespaceId == myTempNamespace)
+			continue;			/* do not look in temp namespace */
+
 		typid = GetSysCacheOid2(TYPENAMENSP,
 								PointerGetDatum(typname),
 								ObjectIdGetDatum(namespaceId));
diff --git a/src/backend/parser/parse_func.c b/src/backend/parser/parse_func.c
index 554ca9d8c47..044addd2501 100644
--- a/src/backend/parser/parse_func.c
+++ b/src/backend/parser/parse_func.c
@@ -1743,7 +1743,12 @@ FuncNameAsType(List *funcname)
 	Oid			result;
 	Type		typtup;
 
-	typtup = LookupTypeName(NULL, makeTypeNameFromNameList(funcname), NULL, false);
+	/*
+	 * temp_ok=false protects the <refsect1 id="sql-createfunction-security">
+	 * contract for writing SECURITY DEFINER functions safely.
+	 */
+	typtup = LookupTypeNameExtended(NULL, makeTypeNameFromNameList(funcname),
+									NULL, false, false);
 	if (typtup == NULL)
 		return InvalidOid;
 
diff --git a/src/backend/parser/parse_type.c b/src/backend/parser/parse_type.c
index 9db3553d80a..640cb1e153e 100644
--- a/src/backend/parser/parse_type.c
+++ b/src/backend/parser/parse_type.c
@@ -33,6 +33,18 @@ static int32 typenameTypeMod(ParseState *pstate, const TypeName *typeName,
 
 /*
  * LookupTypeName
+ *		Wrapper for typical case.
+ */
+Type
+LookupTypeName(ParseState *pstate, const TypeName *typeName,
+			   int32 *typmod_p, bool missing_ok)
+{
+	return LookupTypeNameExtended(pstate,
+								  typeName, typmod_p, true, missing_ok);
+}
+
+/*
+ * LookupTypeNameExtended
  *		Given a TypeName object, lookup the pg_type syscache entry of the type.
  *		Returns NULL if no such type can be found.  If the type is found,
  *		the typmod value represented in the TypeName struct is computed and
@@ -51,11 +63,17 @@ static int32 typenameTypeMod(ParseState *pstate, const TypeName *typeName,
  * found but is a shell, and there is typmod decoration, an error will be
  * thrown --- this is intentional.
  *
+ * If temp_ok is false, ignore types in the temporary namespace.  Pass false
+ * when the caller will decide, using goodness of fit criteria, whether the
+ * typeName is actually a type or something else.  If typeName always denotes
+ * a type (or denotes nothing), pass true.
+ *
  * pstate is only used for error location info, and may be NULL.
  */
 Type
-LookupTypeName(ParseState *pstate, const TypeName *typeName,
-			   int32 *typmod_p, bool missing_ok)
+LookupTypeNameExtended(ParseState *pstate,
+					   const TypeName *typeName, int32 *typmod_p,
+					   bool temp_ok, bool missing_ok)
 {
 	Oid			typoid;
 	HeapTuple	tup;
@@ -172,7 +190,7 @@ LookupTypeName(ParseState *pstate, const TypeName *typeName,
 		else
 		{
 			/* Unqualified type name, so search the search path */
-			typoid = TypenameGetTypid(typname);
+			typoid = TypenameGetTypidExtended(typname, temp_ok);
 		}
 
 		/* If an array reference, return the array type instead */
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index bef01cde86e..9f7eb2ba9f2 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -8583,6 +8583,14 @@ get_coercion_expr(Node *arg, deparse_context *context,
 		if (!PRETTY_PAREN(context))
 			appendStringInfoChar(buf, ')');
 	}
+
+	/*
+	 * Never emit resulttype(arg) functional notation. A pg_proc entry could
+	 * take precedence, and a resulttype in pg_temp would require schema
+	 * qualification that format_type_with_typemod() would usually omit. We've
+	 * standardized on arg::resulttype, but CAST(arg AS resulttype) notation
+	 * would work fine.
+	 */
 	appendStringInfo(buf, "::%s",
 					 format_type_with_typemod(resulttype, resulttypmod));
 }