Add GUC checks for ssl_min_protocol_version and ssl_max_protocol_version

michaelpq · michaelpq · commit ac2dcca5dfe6 · 2020-01-18T12:32:55.000+09:00
Mixing incorrect bounds set in the SSL context leads to confusing error messages generated by OpenSSL which are hard to act on. New checks are added within the GUC machinery to improve the user experience as they apply to any SSL implementation, not only OpenSSL, and doing the checks beforehand avoids the creation of a SSL during a reload (or startup) which we know will never be used anyway. Backpatch down to 12, as those parameters have been introduced by e73e67c. Author: Michael Paquier Reviewed-by: Daniel Gustafsson Discussion: https://postgr.es/m/20200114035420.GE1515@paquier.xyz Backpatch-through: 12
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
@@ -201,6 +201,10 @@ static bool check_cluster_name(char **newval, void **extra, GucSource source);
 static const char *show_unix_socket_permissions(void);
 static const char *show_log_file_mode(void);
 static const char *show_data_directory_mode(void);
+static bool check_ssl_min_protocol_version(int *newval, void **extra,
+										   GucSource source);
+static bool check_ssl_max_protocol_version(int *newval, void **extra,
+										   GucSource source);
 static bool check_recovery_target_timeline(char **newval, void **extra, GucSource source);
 static void assign_recovery_target_timeline(const char *newval, void *extra);
 static bool check_recovery_target(char **newval, void **extra, GucSource source);
@@ -4522,7 +4526,7 @@ static struct config_enum ConfigureNamesEnum[] =
 		&ssl_min_protocol_version,
 		PG_TLS1_VERSION,
 		ssl_protocol_versions_info + 1, /* don't allow PG_TLS_ANY */
-		NULL, NULL, NULL
+		check_ssl_min_protocol_version, NULL, NULL
 	},
 
 	{
@@ -4534,7 +4538,7 @@ static struct config_enum ConfigureNamesEnum[] =
 		&ssl_max_protocol_version,
 		PG_TLS_ANY,
 		ssl_protocol_versions_info,
-		NULL, NULL, NULL
+		check_ssl_max_protocol_version, NULL, NULL
 	},
 
 	/* End-of-list marker */
@@ -11462,6 +11466,49 @@ show_data_directory_mode(void)
 	return buf;
 }
 
+static bool
+check_ssl_min_protocol_version(int *newval, void **extra, GucSource source)
+{
+	int			new_ssl_min_protocol_version = *newval;
+
+	/* PG_TLS_ANY is not supported for the minimum bound */
+	Assert(new_ssl_min_protocol_version > PG_TLS_ANY);
+
+	if (ssl_max_protocol_version &&
+		new_ssl_min_protocol_version > ssl_max_protocol_version)
+	{
+		GUC_check_errhint("\"%s\" cannot be higher than \"%s\".",
+						  "ssl_min_protocol_version",
+						  "ssl_max_protocol_version");
+		GUC_check_errcode(ERRCODE_INVALID_PARAMETER_VALUE);
+		return false;
+	}
+
+	return true;
+}
+
+static bool
+check_ssl_max_protocol_version(int *newval, void **extra, GucSource source)
+{
+	int			new_ssl_max_protocol_version = *newval;
+
+	/* if PG_TLS_ANY, there is no need to check the bounds */
+	if (new_ssl_max_protocol_version == PG_TLS_ANY)
+		return true;
+
+	if (ssl_min_protocol_version &&
+		ssl_min_protocol_version > new_ssl_max_protocol_version)
+	{
+		GUC_check_errhint("\"%s\" cannot be lower than \"%s\".",
+						  "ssl_max_protocol_version",
+						  "ssl_min_protocol_version");
+		GUC_check_errcode(ERRCODE_INVALID_PARAMETER_VALUE);
+		return false;
+	}
+
+	return true;
+}
+
 static bool
 check_recovery_target_timeline(char **newval, void **extra, GucSource source)
 {
diff --git a/src/test/ssl/t/001_ssltests.pl b/src/test/ssl/t/001_ssltests.pl
@@ -13,7 +13,7 @@
 
 if ($ENV{with_openssl} eq 'yes')
 {
-	plan tests => 75;
+	plan tests => 77;
 }
 else
 {
@@ -87,6 +87,24 @@
 	'restart succeeds with password-protected key file');
 $node->_update_pid(1);
 
+# Test compatibility of SSL protocols.
+# TLSv1.1 is lower than TLSv1.2, so it won't work.
+$node->append_conf(
+	'postgresql.conf',
+	qq{ssl_min_protocol_version='TLSv1.2'
+ssl_max_protocol_version='TLSv1.1'});
+command_fails(
+	[ 'pg_ctl', '-D', $node->data_dir, '-l', $node->logfile, 'restart' ],
+	'restart fails with incorrect SSL protocol bounds');
+# Go back to the defaults, this works.
+$node->append_conf(
+	'postgresql.conf',
+	qq{ssl_min_protocol_version='TLSv1'
+ssl_max_protocol_version=''});
+command_ok(
+	[ 'pg_ctl', '-D', $node->data_dir, '-l', $node->logfile, 'restart' ],
+	'restart succeeds with correct SSL protocol bounds');
+
 ### Run client-side tests.
 ###
 ### Test that libpq accepts/rejects the connection correctly, depending
diff --git a/src/test/ssl/t/SSLServer.pm b/src/test/ssl/t/SSLServer.pm
@@ -128,7 +128,7 @@ sub configure_test_server_for_ssl
 	print $conf "log_statement=all\n";
 
 	# enable SSL and set up server key
-	print $conf "include 'sslconfig.conf'";
+	print $conf "include 'sslconfig.conf'\n";
 
 	close $conf;
 
