ipsec: T8022: Fix invalid automatic dynamic prefix assignment for transport mode tunnels

smoketest/scripts/cli/test_vpn_ipsec.py

@@ -419,6 +419,91 @@ def test_site_to_site_with_default_ts(self):
         for line in swanctl_conf_lines:
             self.assertIn(line, swanctl_conf)
 
+    def test_site_to_site_gre_over_ipsec(self):
+        """Test GRE over IPsec site‑to‑site configuration with transport mode ESP"""
+
+        tunnel_id = '100'
+        local_address = '172.168.99.2'
+
+        # Interfaces
+        base_tun_path = tunnel_path + [f'tun{tunnel_id}']
+        self.cli_set(base_tun_path + ['address', '10.12.0.1/30'])
+        self.cli_set(base_tun_path + ['encapsulation', 'gre'])
+        self.cli_set(base_tun_path + ['remote', peer_ip])
+        self.cli_set(base_tun_path + ['source-address', local_address])
+        self.cli_set(ethernet_path + [interface, 'vif', vif, 'address', 'dhcp'])
+
+        # Authentication (PSK)
+        base_psk_path = base_path + ['authentication', 'psk']
+        self.cli_set(base_psk_path + [peer_name, 'id', local_address])
+        self.cli_set(base_psk_path + [peer_name, 'id', peer_ip])
+        self.cli_set(base_psk_path + [peer_name, 'secret', secret])
+
+        # ESP group
+        base_esp_path = base_path + ['esp-group', esp_group]
+        self.cli_set(base_esp_path + ['lifetime', '3600'])
+        self.cli_set(base_esp_path + ['mode', 'transport'])
+        self.cli_set(base_esp_path + ['pfs', 'dh-group14'])
+        self.cli_set(base_esp_path + ['proposal', '10', 'encryption', 'aes256'])
+        self.cli_set(base_esp_path + ['proposal', '10', 'hash', 'sha1'])
+
+        # IKE group
+        base_ike_path = base_path + ['ike-group', ike_group]
+        self.cli_set(base_ike_path + ['close-action', 'none'])
+        self.cli_set(base_ike_path + ['dead-peer-detection', 'action', 'restart'])
+        self.cli_set(base_ike_path + ['dead-peer-detection', 'interval', '10'])
+        self.cli_set(base_ike_path + ['key-exchange', 'ikev2'])
+        self.cli_set(base_ike_path + ['lifetime', '28800'])
+        self.cli_set(base_ike_path + ['proposal', '10', 'dh-group', '5'])
+        self.cli_set(base_ike_path + ['proposal', '10', 'encryption', 'aes256'])
+        self.cli_set(base_ike_path + ['proposal', '10', 'hash', 'sha1'])
+
+        # IPsec interface binding
+        self.cli_set(base_path + ['interface', interface])
+
+        # Site‑to‑site peer
+        peer_path = base_path + ['site-to-site', 'peer', peer_name]
+        self.cli_set(peer_path + ['authentication', 'mode', 'pre-shared-secret'])
+        self.cli_set(peer_path + ['authentication', 'local-id', local_address])
+        self.cli_set(peer_path + ['authentication', 'remote-id', peer_ip])
+        self.cli_set(peer_path + ['connection-type', 'initiate'])
+        self.cli_set(peer_path + ['default-esp-group', esp_group])
+        self.cli_set(peer_path + ['ike-group', ike_group])
+        self.cli_set(peer_path + ['local-address', local_address])
+        self.cli_set(peer_path + ['remote-address', peer_ip])
+        self.cli_set(peer_path + ['tunnel', tunnel_id, 'protocol', 'gre'])
+
+        # Commit and verify
+        self.cli_commit()
+
+        # Verify strongSwan configuration
+        swanctl_conf = read_file(swanctl_file)
+        swanctl_conf_lines = [
+            'version = 2',
+            'auth = psk',
+            'proposals = aes128-sha1-modp1024,aes256-sha1-modp1536',
+            'esp_proposals = aes128-sha1-modp2048,aes256-sha1-modp2048',
+            'life_time = 3600s',
+            'mode = transport',  # ensure transport mode is used
+            f'{peer_name}-tunnel-{tunnel_id}',
+            f'local_ts = {local_address}[gre/]',  # GRE tunnel source/target
+            f'remote_ts = {peer_ip}[gre/]',
+            f'local_addrs = {local_address} # dhcp:no',
+            f'remote_addrs = {peer_ip}',
+        ]
+        for line in swanctl_conf_lines:
+            with self.subTest(line=line):
+                self.assertIn(line, swanctl_conf)
+
+        # Verify validation of local/remote prefix
+        base_tun_path = peer_path + ['tunnel', tunnel_id]
+        self.cli_set(base_tun_path + ['local', 'prefix', '10.1.2.0/24'])
+        self.cli_set(base_tun_path + ['remote', 'prefix', '10.4.5.0/24'])
+
+        err_msg = 'Local/remote prefix cannot be used with ESP transport mode on tunnel'
+        with self.assertRaisesRegex(ConfigSessionError, err_msg):
+            self.cli_commit()
+
     def test_site_to_site_vti(self):
         local_address = '192.0.2.10'
         vti = 'vti10'

src/conf_mode/vpn_ipsec.py

@@ -80,6 +80,54 @@
 
 DHCP_HOOK_IFLIST = '/tmp/ipsec_dhcp_interfaces'
 
+
+def _cleanup_default_prefixes(ipsec: dict, default_values: dict):
+    """
+    Remove default local/remote prefixes from tunnels
+    that use 'transport' mode ESP and do not have explicit prefix definitions
+    """
+    site_to_site = dict_search_args(ipsec, 'site_to_site', 'peer') or {}
+
+    for peer, peer_conf in site_to_site.items():
+        tunnels = dict_search_args(peer_conf, 'tunnel') or {}
+        for tunnel, tunnel_conf in tunnels.items():
+            # Determine ESP group name - prefer specific over default
+            tunnel_esp_group = dict_search_args(tunnel_conf, 'esp_group')
+            default_esp_group = dict_search_args(peer_conf, 'default_esp_group')
+            esp_group_name = tunnel_esp_group or default_esp_group
+            if not esp_group_name:
+                continue
+
+            # Fetch ESP group details
+            esp_group = dict_search_args(ipsec, 'esp_group', esp_group_name)
+            if not esp_group:
+                continue
+
+            # Only act if ESP group is in transport mode
+            if dict_search_args(esp_group, 'mode') != 'transport':
+                continue
+
+            # Look for local and remote prefixes
+            local_prefixes = dict_search_args(tunnel_conf, 'local', 'prefix')
+            remote_prefixes = dict_search_args(tunnel_conf, 'remote', 'prefix')
+
+            tunnel_defaults = dict_search_args(
+                default_values, 'site_to_site', 'peer', peer, 'tunnel', tunnel
+            )
+            if not tunnel_defaults:
+                continue
+
+            # Safely remove missing prefixes
+            if not local_prefixes:
+                local_default = dict_search_args(tunnel_defaults, 'local')
+                if local_default and 'prefix' in local_default:
+                    del local_default['prefix']
+
+            if not remote_prefixes:
+                remote_default = dict_search_args(tunnel_defaults, 'remote')
+                if remote_default and 'prefix' in remote_default:
+                    del remote_default['prefix']
+
 def get_config(config=None):
     if config:
         conf = config
@@ -114,6 +162,9 @@ def get_config(config=None):
             if 'dead_peer_detection' not in ike:
                 del default_values['ike_group'][name]['dead_peer_detection']
 
+    # Clean up default prefixes for ESP transport-mode tunnels
+    _cleanup_default_prefixes(ipsec, default_values)
+
     ipsec = config_dict_merge(default_values, ipsec)
 
     ipsec['dhcp_interfaces'] = set()