ipsec: Improve the handling of NAT-T keepalive messages

[vpp.git] / src / vnet / ipsec / ipsec_tun_in.c

diff --git a/src/vnet/ipsec/ipsec_tun_in.c b/src/vnet/ipsec/ipsec_tun_in.c
index 4f8af00..c414be0 100644 (file)
--- a/src/vnet/ipsec/ipsec_tun_in.c
+++ b/src/vnet/ipsec/ipsec_tun_in.c
@@ -186,18 +186,35 @@ ipsec_tun_protect_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
        {
          ip60 = (ip6_header_t *) ip40;
          esp0 = (esp_header_t *) (ip60 + 1);
-         hdr_sz0 = sizeof (ip6_header_t);
+         buf_rewind0 = hdr_sz0 = sizeof (ip6_header_t);
        }
       else
        {
-         /* NAT UDP port 4500 case, don't advance any more */
          if (ip40->protocol == IP_PROTOCOL_UDP)
            {
+             /* NAT UDP port 4500 case, don't advance any more */
              esp0 =
                (esp_header_t *) ((u8 *) ip40 + ip4_header_bytes (ip40) +
                                  sizeof (udp_header_t));
              hdr_sz0 = 0;
              buf_rewind0 = ip4_header_bytes (ip40) + sizeof (udp_header_t);
+
+             const udp_header_t *udp0 =
+               (udp_header_t *) ((u8 *) ip40 + ip4_header_bytes (ip40));
+
+             /* length 9 = sizeof(udp_header) + 1 byte of special SPI */
+             if (clib_net_to_host_u16 (udp0->length) == 9 &&
+                 esp0->spi_bytes[0] == 0xff)
+               {
+                 b[0]->error =
+                   node->errors[IPSEC_TUN_PROTECT_INPUT_ERROR_NAT_KEEPALIVE];
+
+                 next[0] = VNET_DEVICE_INPUT_NEXT_IP4_DROP;
+                 len0 = 0;
+
+                 vlib_buffer_advance (b[0], -buf_rewind0);
+                 goto trace00;
+               }
            }
          else
            {
@@ -213,15 +230,11 @@ ipsec_tun_protect_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
       if (len0 < sizeof (esp_header_t))
        {
-         if (esp0->spi_bytes[0] == 0xff)
-           b[0]->error =
-             node->errors[IPSEC_TUN_PROTECT_INPUT_ERROR_NAT_KEEPALIVE];
-         else
-           b[0]->error =
-             node->errors[IPSEC_TUN_PROTECT_INPUT_ERROR_TOO_SHORT];
+         b[0]->error = node->errors[IPSEC_TUN_PROTECT_INPUT_ERROR_TOO_SHORT];
 
          next[0] = is_ip6 ? VNET_DEVICE_INPUT_NEXT_IP6_DROP :
                             VNET_DEVICE_INPUT_NEXT_IP4_DROP;
+         vlib_buffer_advance (b[0], -buf_rewind0);
          goto trace00;
        }