virtio: fix the tcp/udp checksum offloads

Some vhost-backend calculates the wrong checksum in
case of tcp/udp offload when driver resets tcp/udp
checksum field to '0'.

Type: fix

Change-Id: I1d2a9b95b3d5cc1decac38027104a04df2af4680
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>

diff --git a/src/vnet/devices/virtio/device.c b/src/vnet/devices/virtio/device.c
index 76f8558..e812b37 100644 (file)
--- a/src/vnet/devices/virtio/device.c
+++ b/src/vnet/devices/virtio/device.c
@@ -159,18 +159,10 @@ set_checksum_offsets (vlib_main_t * vm, virtio_if_t * vif, vlib_buffer_t * b,
       hdr->csum_start = gho.l4_hdr_offset;     // 0x22;
       if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
        {
-         tcp_header_t *tcp =
-           (tcp_header_t *) (vlib_buffer_get_current (b) +
-                             gho.l4_hdr_offset);
-         tcp->checksum = 0;
          hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
        }
       else if (b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM)
        {
-         udp_header_t *udp =
-           (udp_header_t *) (vlib_buffer_get_current (b) +
-                             gho.l4_hdr_offset);
-         udp->checksum = 0;
          hdr->csum_offset = STRUCT_OFFSET_OF (udp_header_t, checksum);
        }
 
@@ -190,18 +182,10 @@ set_checksum_offsets (vlib_main_t * vm, virtio_if_t * vif, vlib_buffer_t * b,
       hdr->csum_start = gho.l4_hdr_offset;     // 0x36;
       if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
        {
-         tcp_header_t *tcp =
-           (tcp_header_t *) (vlib_buffer_get_current (b) +
-                             gho.l4_hdr_offset);
-         tcp->checksum = 0;
          hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
        }
       else if (b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM)
        {
-         udp_header_t *udp =
-           (udp_header_t *) (vlib_buffer_get_current (b) +
-                             gho.l4_hdr_offset);
-         udp->checksum = 0;
          hdr->csum_offset = STRUCT_OFFSET_OF (udp_header_t, checksum);
        }
     }
@@ -226,15 +210,10 @@ add_buffer_to_slot (vlib_main_t * vm, virtio_if_t * vif,
       if (b->flags & VNET_BUFFER_F_IS_IP4)
        {
          ip4_header_t *ip4;
-         tcp_header_t *tcp;
          gso_header_offset_t gho = vnet_gso_header_offset_parser (b, 0);
          hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
          hdr->gso_size = vnet_buffer2 (b)->gso_size;
          hdr->hdr_len = gho.l4_hdr_offset + gho.l4_hdr_sz;
-         tcp =
-           (tcp_header_t *) (vlib_buffer_get_current (b) +
-                             gho.l4_hdr_offset);
-         tcp->checksum = 0;
          hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
          hdr->csum_start = gho.l4_hdr_offset;  // 0x22;
          hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
@@ -250,16 +229,11 @@ add_buffer_to_slot (vlib_main_t * vm, virtio_if_t * vif,
        }
       else if (b->flags & VNET_BUFFER_F_IS_IP6)
        {
-         tcp_header_t *tcp;
          gso_header_offset_t gho = vnet_gso_header_offset_parser (b, 1);
          hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
          hdr->gso_size = vnet_buffer2 (b)->gso_size;
          hdr->hdr_len = gho.l4_hdr_offset + gho.l4_hdr_sz;
          hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-         tcp =
-           (tcp_header_t *) (vlib_buffer_get_current (b) +
-                             gho.l4_hdr_offset);
-         tcp->checksum = 0;
          hdr->csum_start = gho.l4_hdr_offset;  // 0x36;
          hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
        }

diff --git a/src/vnet/devices/virtio/node.c b/src/vnet/devices/virtio/node.c
index 78a8dd5..3bb2366 100644 (file)
--- a/src/vnet/devices/virtio/node.c
+++ b/src/vnet/devices/virtio/node.c
@@ -201,7 +201,6 @@ virtio_needs_csum (vlib_buffer_t * b0, struct virtio_net_hdr_v1 *hdr,
                                                vnet_buffer
                                                (b0)->l4_hdr_offset);
          *l4_hdr_sz = tcp_header_bytes (tcp);
-         tcp->checksum = 0;
        }
       else if (*l4_proto == IP_PROTOCOL_UDP)
        {
@@ -210,7 +209,6 @@ virtio_needs_csum (vlib_buffer_t * b0, struct virtio_net_hdr_v1 *hdr,
                                                vnet_buffer
                                                (b0)->l4_hdr_offset);
          *l4_hdr_sz = sizeof (*udp);
-         udp->checksum = 0;
        }
     }