wireguard: compute checksum for outer ipv6 header

Type: fix

Signed-off-by: Artem Glazychev <artem.glazychev@xored.com>
Change-Id: I477e92712e441c91789afdf9be389d967acfa799

3 files changed, 127 insertions, 11 deletions

diff --git a/src/plugins/wireguard/wireguard_output_tun.c b/src/plugins/wireguard/wireguard_output_tun.c
index d1b1d6bb8f0..f613d6c0c16 100644
--- a/src/plugins/wireguard/wireguard_output_tun.c
+++ b/src/plugins/wireguard/wireguard_output_tun.c
@@ -307,6 +307,22 @@ error:
   return ret;
 }
 
+static_always_inline void
+wg_calc_checksum (vlib_main_t *vm, vlib_buffer_t *b)
+{
+  int bogus = 0;
+  u8 ip_ver_out = (*((u8 *) vlib_buffer_get_current (b)) >> 4);
+
+  /* IPv6 UDP checksum is mandatory */
+  if (ip_ver_out == 6)
+    {
+      ip6_header_t *ip6 =
+	(ip6_header_t *) ((u8 *) vlib_buffer_get_current (b));
+      udp_header_t *udp = ip6_next_header (ip6);
+      udp->checksum = ip6_tcp_udp_icmp_compute_checksum (vm, b, ip6, &bogus);
+    }
+}
+
 /* is_ip4 - inner header flag */
 always_inline uword
 wg_output_tun_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
@@ -555,6 +571,14 @@ wg_output_tun_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
       /* wg-output-process-ops */
       wg_output_process_ops (vm, node, ptd->crypto_ops, sync_bufs, nexts,
 			     drop_next);
+
+      int n_left_from_sync_bufs = n_sync;
+      while (n_left_from_sync_bufs > 0)
+	{
+	  n_left_from_sync_bufs--;
+	  wg_calc_checksum (vm, sync_bufs[n_left_from_sync_bufs]);
+	}
+
       vlib_buffer_enqueue_to_next (vm, node, sync_bi, nexts, n_sync);
     }
   if (n_async)
@@ -627,6 +651,11 @@ wg_output_tun_post (vlib_main_t *vm, vlib_node_runtime_t *node,
       next[2] = (wg_post_data (b[2]))->next_index;
       next[3] = (wg_post_data (b[3]))->next_index;
 
+      wg_calc_checksum (vm, b[0]);
+      wg_calc_checksum (vm, b[1]);
+      wg_calc_checksum (vm, b[2]);
+      wg_calc_checksum (vm, b[3]);
+
       if (PREDICT_FALSE (node->flags & VLIB_NODE_FLAG_TRACE))
 	{
 	  if (b[0]->flags & VLIB_BUFFER_IS_TRACED)
@@ -671,6 +700,8 @@ wg_output_tun_post (vlib_main_t *vm, vlib_node_runtime_t *node,
 
   while (n_left > 0)
     {
+      wg_calc_checksum (vm, b[0]);
+
       next[0] = (wg_post_data (b[0]))->next_index;
       if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE) &&
 			 (b[0]->flags & VLIB_BUFFER_IS_TRACED)))
diff --git a/src/plugins/wireguard/wireguard_send.c b/src/plugins/wireguard/wireguard_send.c
index adfa5cac3de..72fa11034bf 100644
--- a/src/plugins/wireguard/wireguard_send.c
+++ b/src/plugins/wireguard/wireguard_send.c
@@ -41,7 +41,8 @@ ip46_enqueue_packet (vlib_main_t *vm, u32 bi0, int is_ip4)
 }
 
 static void
-wg_buffer_prepend_rewrite (vlib_buffer_t *b0, const u8 *rewrite, u8 is_ip4)
+wg_buffer_prepend_rewrite (vlib_main_t *vm, vlib_buffer_t *b0,
+			   const u8 *rewrite, u8 is_ip4)
 {
   if (is_ip4)
     {
@@ -72,6 +73,13 @@ wg_buffer_prepend_rewrite (vlib_buffer_t *b0, const u8 *rewrite, u8 is_ip4)
 
       hdr6->ip6.payload_length = hdr6->udp.length =
 	clib_host_to_net_u16 (b0->current_length - sizeof (ip6_header_t));
+
+      /* IPv6 UDP checksum is mandatory */
+      int bogus = 0;
+      ip6_header_t *ip6_0 = &(hdr6->ip6);
+      hdr6->udp.checksum =
+	ip6_tcp_udp_icmp_compute_checksum (vm, b0, ip6_0, &bogus);
+      ASSERT (bogus == 0);
     }
 }
 
@@ -93,7 +101,7 @@ wg_create_buffer (vlib_main_t *vm, const u8 *rewrite, const u8 *packet,
 
   b0->current_length = packet_len;
 
-  wg_buffer_prepend_rewrite (b0, rewrite, is_ip4);
+  wg_buffer_prepend_rewrite (vm, b0, rewrite, is_ip4);
 
   return true;
 }
diff --git a/test/test_wireguard.py b/test/test_wireguard.py
index b12330ac5bb..80ebdd89aa6 100644
--- a/test/test_wireguard.py
+++ b/test/test_wireguard.py
@@ -375,12 +375,13 @@ class VppWgPeer(VppObject):
         if is_ip6 is False:
             self._test.assertEqual(p[IP].src, self.itf.src)
             self._test.assertEqual(p[IP].dst, self.endpoint)
+            self._test.assert_packet_checksums_valid(p)
         else:
             self._test.assertEqual(p[IPv6].src, self.itf.src)
             self._test.assertEqual(p[IPv6].dst, self.endpoint)
+            self._test.assert_packet_checksums_valid(p, False)
         self._test.assertEqual(p[UDP].sport, self.itf.port)
         self._test.assertEqual(p[UDP].dport, self.port)
-        self._test.assert_packet_checksums_valid(p)
 
     def consume_init(self, p, tx_itf, is_ip6=False, is_mac2=False):
         self.noise.set_as_responder()
@@ -466,17 +467,16 @@ class VppWgPeer(VppObject):
     def encrypt_transport(self, p):
         return self.noise.encrypt(bytes(p))
 
-    def validate_encapped(self, rxs, tx, is_ip6=False):
+    def validate_encapped(self, rxs, tx, is_tunnel_ip6=False, is_transport_ip6=False):
         for rx in rxs:
-            if is_ip6 is False:
-                rx = IP(self.decrypt_transport(rx, is_ip6=is_ip6))
-
+            rx = self.decrypt_transport(rx, is_tunnel_ip6)
+            if is_transport_ip6 is False:
+                rx = IP(rx)
                 # check the original packet is present
                 self._test.assertEqual(rx[IP].dst, tx[IP].dst)
                 self._test.assertEqual(rx[IP].ttl, tx[IP].ttl - 1)
             else:
-                rx = IPv6(self.decrypt_transport(rx, is_ip6=is_ip6))
-
+                rx = IPv6(rx)
                 # check the original packet is present
                 self._test.assertEqual(rx[IPv6].dst, tx[IPv6].dst)
                 self._test.assertEqual(rx[IPv6].hlim, tx[IPv6].hlim - 1)
@@ -1222,7 +1222,7 @@ class TestWg(VppTestCase):
         rxs = self.send_and_expect(self.pg0, [p], self.pg1)
 
         # verify the data packet
-        peer_1.validate_encapped(rxs, p, is_ip6=is_ip6)
+        peer_1.validate_encapped(rxs, p, is_tunnel_ip6=is_ip6, is_transport_ip6=is_ip6)
 
         # remove configs
         r1.remove_vpp_config()
@@ -1246,7 +1246,7 @@ class TestWg(VppTestCase):
         self._test_wg_peer_roaming_on_data_tmpl(is_async=True, is_ip6=True)
 
     def test_wg_peer_resp(self):
-        """Send handshake response"""
+        """Send handshake response IPv4 tunnel"""
         port = 12323
 
         # Create interfaces
@@ -1323,6 +1323,83 @@ class TestWg(VppTestCase):
         peer_1.remove_vpp_config()
         wg0.remove_vpp_config()
 
+    def test_wg_peer_resp_ipv6(self):
+        """Send handshake response IPv6 tunnel"""
+        port = 12323
+
+        # Create interfaces
+        wg0 = VppWgInterface(self, self.pg1.local_ip6, port).add_vpp_config()
+        wg0.admin_up()
+        wg0.config_ip4()
+
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+
+        peer_1 = VppWgPeer(
+            self, wg0, self.pg1.remote_ip6, port + 1, ["10.11.3.0/24"]
+        ).add_vpp_config()
+        self.assertEqual(len(self.vapi.wireguard_peers_dump()), 1)
+
+        r1 = VppIpRoute(
+            self, "10.11.3.0", 24, [VppRoutePath("10.11.3.1", wg0.sw_if_index)]
+        ).add_vpp_config()
+
+        # wait for the peer to send a handshake
+        rx = self.pg1.get_capture(1, timeout=2)
+
+        # consume the handshake in the noise protocol and
+        # generate the response
+        resp = peer_1.consume_init(rx[0], self.pg1, is_ip6=True)
+
+        # send the response, get keepalive
+        rxs = self.send_and_expect(self.pg1, [resp], self.pg1)
+
+        for rx in rxs:
+            b = peer_1.decrypt_transport(rx, True)
+            self.assertEqual(0, len(b))
+
+        # send a packets that are routed into the tunnel
+        p = (
+            Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac)
+            / IP(src=self.pg0.remote_ip4, dst="10.11.3.2")
+            / UDP(sport=555, dport=556)
+            / Raw(b"\x00" * 80)
+        )
+
+        rxs = self.send_and_expect(self.pg0, p * 2, self.pg1)
+        peer_1.validate_encapped(rxs, p, True)
+
+        # send packets into the tunnel, expect to receive them on
+        # the other side
+        p = [
+            (
+                peer_1.mk_tunnel_header(self.pg1, True)
+                / Wireguard(message_type=4, reserved_zero=0)
+                / WireguardTransport(
+                    receiver_index=peer_1.sender,
+                    counter=ii,
+                    encrypted_encapsulated_packet=peer_1.encrypt_transport(
+                        (
+                            IP(src="10.11.3.1", dst=self.pg0.remote_ip4, ttl=20)
+                            / UDP(sport=222, dport=223)
+                            / Raw()
+                        )
+                    ),
+                )
+            )
+            for ii in range(255)
+        ]
+
+        rxs = self.send_and_expect(self.pg1, p, self.pg0)
+
+        for rx in rxs:
+            self.assertEqual(rx[IP].dst, self.pg0.remote_ip4)
+            self.assertEqual(rx[IP].ttl, 19)
+
+        r1.remove_vpp_config()
+        peer_1.remove_vpp_config()
+        wg0.remove_vpp_config()
+
     def test_wg_peer_v4o4(self):
         """Test v4o4"""