0003-WIP-Add-injection-points-and-test-for-early-backend-.patch

From e893d2e53a9bde6ddf4462d9f8b206c51ebd40cb Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Mon, 24 Jun 2024 18:15:53 +0300
Subject: [PATCH 3/4] WIP: Add injection points and test for early backend
 startup errors

---
 src/backend/tcop/backend_startup.c            |  9 ++++
 src/backend/utils/misc/injection_point.c      | 33 +++++++++++-
 src/include/utils/injection_point.h           |  1 +
 src/interfaces/libpq/meson.build              |  1 +
 .../libpq/t/005_negotiate_encryption.pl       | 50 +++++++++++++++++++
 5 files changed, 92 insertions(+), 2 deletions(-)

diff --git a/src/backend/tcop/backend_startup.c b/src/backend/tcop/backend_startup.c
index cfa27551964..7b4a3e23458 100644
--- a/src/backend/tcop/backend_startup.c
+++ b/src/backend/tcop/backend_startup.c
@@ -33,6 +33,7 @@
 #include "tcop/backend_startup.h"
 #include "tcop/tcopprot.h"
 #include "utils/builtins.h"
+#include "utils/injection_point.h"
 #include "utils/memutils.h"
 #include "utils/ps_status.h"
 #include "utils/timeout.h"
@@ -160,6 +161,14 @@ BackendInitialize(ClientSocket *client_sock, CAC_state cac)
 
 	whereToSendOutput = DestRemote; /* now safe to ereport to client */
 
+	/* For testing client error handling */
+	INJECTION_POINT("backend-initialize");
+	if (IsInjectionPointAttached("backend-initialize-v2-error"))
+	{
+		FrontendProtocol = PG_PROTOCOL(2,0);
+		elog(FATAL, "protocol version 2 error triggered");
+	}
+
 	/* set these to empty in case they are needed before we set them up */
 	port->remote_host = "";
 	port->remote_port = "";
diff --git a/src/backend/utils/misc/injection_point.c b/src/backend/utils/misc/injection_point.c
index 5c2a0d2297e..d3995dfd6fc 100644
--- a/src/backend/utils/misc/injection_point.c
+++ b/src/backend/utils/misc/injection_point.c
@@ -24,6 +24,7 @@
 #include "port/pg_bitutils.h"
 #include "storage/fd.h"
 #include "storage/lwlock.h"
+#include "storage/proc.h"
 #include "storage/shmem.h"
 #include "utils/hsearch.h"
 #include "utils/injection_point.h"
@@ -281,6 +282,31 @@ InjectionPointDetach(const char *name)
 #endif
 }
 
+/*
+ * Test if an injection point is defined.
+ */
+bool
+IsInjectionPointAttached(const char *name)
+{
+#ifdef USE_INJECTION_POINTS
+	bool		found;
+
+	/* FIXME: just skip locking if we don't have a PGPROC entry yet. Obviously unsafe.. */
+	if (MyProc != NULL && IsUnderPostmaster)
+		LWLockAcquire(InjectionPointLock, LW_SHARED);
+
+	(void) hash_search(InjectionPointHash, name, HASH_FIND, &found);
+
+	if (MyProc != NULL && IsUnderPostmaster)
+		LWLockRelease(InjectionPointLock);
+
+	return found;
+#else
+	elog(ERROR, "Injection points are not supported by this build");
+	return false;				/* silence compiler */
+#endif
+}
+
 /*
  * Execute an injection point, if defined.
  *
@@ -296,11 +322,14 @@ InjectionPointRun(const char *name)
 	InjectionPointCallback injection_callback;
 	const void *private_data;
 
-	LWLockAcquire(InjectionPointLock, LW_SHARED);
+	/* FIXME: just skip locking if we don't have a PGPROC entry yet. Obviously unsafe.. */
+	if (MyProc != NULL && IsUnderPostmaster)
+		LWLockAcquire(InjectionPointLock, LW_SHARED);
 	entry_by_name = (InjectionPointEntry *)
 		hash_search(InjectionPointHash, name,
 					HASH_FIND, &found);
-	LWLockRelease(InjectionPointLock);
+	if (MyProc != NULL && IsUnderPostmaster)
+		LWLockRelease(InjectionPointLock);
 
 	/*
 	 * If not found, do nothing and remove it from the local cache if it
diff --git a/src/include/utils/injection_point.h b/src/include/utils/injection_point.h
index a61d5d44391..5715eefb31e 100644
--- a/src/include/utils/injection_point.h
+++ b/src/include/utils/injection_point.h
@@ -35,6 +35,7 @@ extern void InjectionPointAttach(const char *name,
 								 const void *private_data,
 								 int private_data_size);
 extern void InjectionPointRun(const char *name);
+extern bool IsInjectionPointAttached(const char *name);
 extern bool InjectionPointDetach(const char *name);
 
 #endif							/* INJECTION_POINT_H */
diff --git a/src/interfaces/libpq/meson.build b/src/interfaces/libpq/meson.build
index ed2a4048d18..7623aeadab7 100644
--- a/src/interfaces/libpq/meson.build
+++ b/src/interfaces/libpq/meson.build
@@ -121,6 +121,7 @@ tests += {
       't/005_negotiate_encryption.pl',
     ],
     'env': {
+      'enable_injection_points': get_option('injection_points') ? 'yes' : 'no',
       'with_ssl': ssl_library,
       'with_gssapi': gssapi.found() ? 'yes' : 'no',
       'with_krb_srvnam': 'postgres',
diff --git a/src/interfaces/libpq/t/005_negotiate_encryption.pl b/src/interfaces/libpq/t/005_negotiate_encryption.pl
index c3f70d31bc8..e6bea0f04f8 100644
--- a/src/interfaces/libpq/t/005_negotiate_encryption.pl
+++ b/src/interfaces/libpq/t/005_negotiate_encryption.pl
@@ -90,6 +90,8 @@ my $kerberos_enabled =
   $ENV{PG_TEST_EXTRA} && $ENV{PG_TEST_EXTRA} =~ /\bkerberos\b/;
 my $ssl_supported = $ENV{with_ssl} eq 'openssl';
 
+my $injection_points_supported = $ENV{enable_injection_points} eq 'yes';
+
 ###
 ### Prepare test server for GSSAPI and SSL authentication, with a few
 ### different test users and helper functions. We don't actually
@@ -155,6 +157,10 @@ $node->safe_psql('postgres', 'CREATE USER ssluser;');
 $node->safe_psql('postgres', 'CREATE USER nossluser;');
 $node->safe_psql('postgres', 'CREATE USER gssuser;');
 $node->safe_psql('postgres', 'CREATE USER nogssuser;');
+if ($injection_points_supported != 0)
+{
+	$node->safe_psql('postgres', 'CREATE EXTENSION injection_points;')
+}
 
 my $unixdir = $node->safe_psql('postgres', 'SHOW unix_socket_directories;');
 chomp($unixdir);
@@ -320,6 +326,27 @@ nossluser   .            disable      postgres       connect, authok
 		\@all_sslmodes, \@all_sslnegotiations,
 		parse_table($test_table));
 
+	if ($injection_points_supported != 0)
+	{
+		$node->safe_psql('postgres',
+						 "SELECT injection_points_attach('backend-initialize', 'error');",
+						 connstr => "user=localuser host=$unixdir");
+		connect_test(
+			$node,
+			"user=testuser sslmode=prefer",
+			'backenderror -> fail');
+		$node->restart;
+
+		$node->safe_psql('postgres',
+						 "SELECT injection_points_attach('backend-initialize-v2-error', 'error');",
+						 connstr => "user=localuser host=$unixdir");
+		connect_test(
+			$node,
+			"user=testuser sslmode=prefer",
+			'v2error -> fail');
+		$node->restart;
+	}
+
 	# Disable SSL again
 	$node->adjust_conf('postgresql.conf', 'ssl', 'off');
 	$node->reload;
@@ -403,6 +430,27 @@ nogssuser   disable      disable      postgres       connect, authok
 	test_matrix($node, $server_config, [ 'testuser', 'gssuser', 'nogssuser' ],
 		\@all_gssencmodes, $sslmodes, $sslnegotiations,
 		parse_table($test_table));
+
+	if ($injection_points_supported != 0)
+	{
+		$node->safe_psql('postgres',
+						 "SELECT injection_points_attach('backend-initialize', 'error');",
+						 connstr => "user=localuser host=$unixdir");
+		connect_test(
+			$node,
+			"user=testuser gssencmode=prefer sslmode=disable",
+			'backenderror, backenderror -> fail');
+		$node->restart;
+
+		$node->safe_psql('postgres',
+						 "SELECT injection_points_attach('backend-initialize-v2-error', 'error');",
+						 connstr => "user=localuser host=$unixdir");
+		connect_test(
+			$node,
+			"user=testuser gssencmode=prefer sslmode=disable",
+			'v2error -> fail');
+		$node->restart;
+	}
 }
 
 ###
@@ -750,6 +798,8 @@ sub parse_log_events
 		push @events, "gssreject" if $line =~ /GSSENCRequest rejected/;
 		push @events, "authfail" if $line =~ /no pg_hba.conf entry/;
 		push @events, "authok" if $line =~ /connection authenticated/;
+		push @events, "backenderror" if $line =~ /error triggered for injection point backend-/;
+		push @events, "v2error" if $line =~ /protocol version 2 error triggered/;
 	}
 
 	# No events at all is represented by "-"
-- 
2.39.2