From e5528f708fcd75135a46146da97d338d5c763843 Mon Sep 17 00:00:00 2001
From: Ajin Cherian <ajinc@fast.au.fujitsu.com>
Date: Mon, 15 May 2023 04:34:40 -0400
Subject: [PATCH v2] Fix issue where the "copy" command does not adhere to the
 run_as_owner setting.

Make sure that "copy" command used during tablesync also respects the run_as_owner
setting.
---
 src/backend/replication/logical/tablesync.c       | 14 +++++
 src/test/subscription/t/033_run_as_table_owner.pl | 64 +++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/src/backend/replication/logical/tablesync.c b/src/backend/replication/logical/tablesync.c
index 0c71ae9..a8d3c47 100644
--- a/src/backend/replication/logical/tablesync.c
+++ b/src/backend/replication/logical/tablesync.c
@@ -120,6 +120,7 @@
 #include "utils/rls.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/usercontext.h"
 
 static bool table_states_valid = false;
 static List *table_states_not_ready = NIL;
@@ -1253,6 +1254,8 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
 	char		originname[NAMEDATALEN];
 	RepOriginId originid;
 	bool		must_use_password;
+	UserContext	ucxt;
+	bool		run_as_owner;
 
 	/* Check the state of the table synchronization. */
 	StartTransactionCommand();
@@ -1456,6 +1459,14 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
 						originname)));
 	}
 
+	/*
+	 * Make sure that the copy command runs as the table owner, unless
+	 * the user has opted out of that behaviour.
+	 */
+	run_as_owner = MySubscription->runasowner;
+	if (!run_as_owner)
+		SwitchToUntrustedUser(rel->rd_rel->relowner, &ucxt);
+
 	/* Now do the initial data copy */
 	PushActiveSnapshot(GetTransactionSnapshot());
 	copy_table(rel);
@@ -1469,6 +1480,9 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
 						res->err)));
 	walrcv_clear_result(res);
 
+	if(!run_as_owner)
+		RestoreUserContext(&ucxt);
+
 	table_close(rel, NoLock);
 
 	/* Make the copy visible. */
diff --git a/src/test/subscription/t/033_run_as_table_owner.pl b/src/test/subscription/t/033_run_as_table_owner.pl
index cabc8a7..91a95f8 100644
--- a/src/test/subscription/t/033_run_as_table_owner.pl
+++ b/src/test/subscription/t/033_run_as_table_owner.pl
@@ -68,6 +68,14 @@ sub revoke_superuser
   ALTER ROLE $role NOSUPERUSER));
 }
 
+sub grant_superuser
+{
+	my ($role) = @_;
+	$node_subscriber->safe_psql(
+	'postgres', qq(
+  ALTER ROLE $role SUPERUSER));
+}
+
 # Create publisher and subscriber nodes with schemas owned and published by
 # "regress_alice" but subscribed and replicated by different role
 # "regress_admin".  For partitioned tables, layout the partitions differently
@@ -201,4 +209,60 @@ expect_replication("alice.unpartitioned", 3, 7, 13,
 	"with INHERIT but not SET ROLE can replicate"
 );
 
+$node_subscriber->safe_psql(
+	    'postgres', qq(
+		DROP SUBSCRIPTION admin_sub;
+));
+
+grant_superuser("regress_admin");
+
+# When a SUBSCRIPTION is created with run_as_owner as false,
+# then replication runs as the owner of the table, and should not have
+# permission to access tables that are not accessible to the owner of the
+# table being replicated.
+# Create a table owned by regress_admin which regress_alice does not
+# have permission to access.
+$node_subscriber->safe_psql(
+	'postgres', qq(
+SET SESSION AUTHORIZATION regress_admin;
+CREATE TABLE admin_audit (i integer);
+));
+
+# Create a trigger on table alice.unpartitioned that writes
+# to a table that regress_alice does not have permission.
+$node_subscriber->safe_psql(
+ 		'postgres', qq(
+SET SESSION AUTHORIZATION regress_alice;
+CREATE OR REPLACE FUNCTION alice.alice_audit()
+RETURNS trigger AS
+\$\$
+	BEGIN
+	insert into public.admin_audit values(2);
+	RETURN NEW;
+	END;
+\$\$
+LANGUAGE 'plpgsql';
+CREATE TRIGGER ALICE_TRIGGER AFTER INSERT ON alice.unpartitioned FOR EACH ROW
+EXECUTE PROCEDURE alice.alice_audit();
+ALTER TABLE alice.unpartitioned ENABLE ALWAYS TRIGGER ALICE_TRIGGER;
+));
+
+# Create subscription with run_as_owner = false.
+$node_subscriber->safe_psql(
+		'postgres', qq(
+SET SESSION AUTHORIZATION regress_admin;
+CREATE SUBSCRIPTION admin_sub CONNECTION '$publisher_connstr' PUBLICATION alice
+	WITH (run_as_owner = false, password_required = false);
+));
+
+# This should fail in the copy stage of the tablesync.
+expect_failure(
+	"admin_audit",
+	0,
+	'',
+	'',
+	qr/ERROR: ( [A-Z0-9]+:)? permission denied for table admin_audit/msi,
+	"with run_as_owner false cannot access table without permission"
+);
+
 done_testing();
-- 
1.8.3.1