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authorDana Rubin <dana.rubin@ravellosystems.com>2015-07-14 11:55:16 +0300
committerStefan Hajnoczi <stefanha@redhat.com>2015-07-20 17:39:05 +0100
commit80da311d81c389860bc387fbe6677c71f7a3c596 (patch)
tree05f1766811520c7c11d8a781ecebafd3f201e8fa
parentfcf0cdc362dd96cb8d2935b892d3dd9ab73ad393 (diff)
downloadqemu-arm-80da311d81c389860bc387fbe6677c71f7a3c596.tar.gz
net/vmxnet3: Fix RX TCP/UDP checksum on partially summed packets
Convert partially summed packets to be fully checksummed. In case csum offloaded packet, vmxnet3 implementation always passes an RxCompDesc with the "Checksum calculated and found correct" notification to the OS. This emulates the observed ESXi behavior. Therefore, if packet has the NEEDS_CSUM bit set, we must calculate and place a fully computed checksum into the tcp/udp header. Otherwise, the OS driver will receive a checksum-correct indication but with the actual tcp/udp checksum field having just the pseudo header csum value. If host OS performs forwarding, it will forward an incorrectly checksummed packet. Signed-off-by: Dana Rubin <dana.rubin@ravellosystems.com> Signed-off-by: Shmulik Ladkani <shmulik.ladkani@ravellosystems.com> Message-id: 1436864116-19154-3-git-send-email-shmulik.ladkani@ravellosystems.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-rw-r--r--hw/net/vmxnet3.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
index dd22a0a8cd..59b06b8412 100644
--- a/hw/net/vmxnet3.c
+++ b/hw/net/vmxnet3.c
@@ -885,6 +885,63 @@ vmxnet3_get_next_rx_descr(VMXNET3State *s, bool is_head,
}
}
+/* In case packet was csum offloaded (either NEEDS_CSUM or DATA_VALID),
+ * the implementation always passes an RxCompDesc with a "Checksum
+ * calculated and found correct" to the OS (cnc=0 and tuc=1, see
+ * vmxnet3_rx_update_descr). This emulates the observed ESXi behavior.
+ *
+ * Therefore, if packet has the NEEDS_CSUM set, we must calculate
+ * and place a fully computed checksum into the tcp/udp header.
+ * Otherwise, the OS driver will receive a checksum-correct indication
+ * (CHECKSUM_UNNECESSARY), but with the actual tcp/udp checksum field
+ * having just the pseudo header csum value.
+ *
+ * While this is not a problem if packet is destined for local delivery,
+ * in the case the host OS performs forwarding, it will forward an
+ * incorrectly checksummed packet.
+ */
+static void vmxnet3_rx_need_csum_calculate(struct VmxnetRxPkt *pkt,
+ const void *pkt_data,
+ size_t pkt_len)
+{
+ struct virtio_net_hdr *vhdr;
+ bool isip4, isip6, istcp, isudp;
+ uint8_t *data;
+ int len;
+
+ if (!vmxnet_rx_pkt_has_virt_hdr(pkt)) {
+ return;
+ }
+
+ vhdr = vmxnet_rx_pkt_get_vhdr(pkt);
+ if (!VMXNET_FLAG_IS_SET(vhdr->flags, VIRTIO_NET_HDR_F_NEEDS_CSUM)) {
+ return;
+ }
+
+ vmxnet_rx_pkt_get_protocols(pkt, &isip4, &isip6, &isudp, &istcp);
+ if (!(isip4 || isip6) || !(istcp || isudp)) {
+ return;
+ }
+
+ vmxnet3_dump_virt_hdr(vhdr);
+
+ /* Validate packet len: csum_start + scum_offset + length of csum field */
+ if (pkt_len < (vhdr->csum_start + vhdr->csum_offset + 2)) {
+ VMW_PKPRN("packet len:%d < csum_start(%d) + csum_offset(%d) + 2, "
+ "cannot calculate checksum",
+ len, vhdr->csum_start, vhdr->csum_offset);
+ return;
+ }
+
+ data = (uint8_t *)pkt_data + vhdr->csum_start;
+ len = pkt_len - vhdr->csum_start;
+ /* Put the checksum obtained into the packet */
+ stw_be_p(data + vhdr->csum_offset, net_raw_checksum(data, len));
+
+ vhdr->flags &= ~VIRTIO_NET_HDR_F_NEEDS_CSUM;
+ vhdr->flags |= VIRTIO_NET_HDR_F_DATA_VALID;
+}
+
static void vmxnet3_rx_update_descr(struct VmxnetRxPkt *pkt,
struct Vmxnet3_RxCompDesc *rxcd)
{
@@ -1898,6 +1955,7 @@ vmxnet3_receive(NetClientState *nc, const uint8_t *buf, size_t size)
if (vmxnet3_rx_filter_may_indicate(s, buf, size)) {
vmxnet_rx_pkt_set_protocols(s->rx_pkt, buf, size);
+ vmxnet3_rx_need_csum_calculate(s->rx_pkt, buf, size);
vmxnet_rx_pkt_attach_data(s->rx_pkt, buf, size, s->rx_vlan_stripping);
bytes_indicated = vmxnet3_indicate_packet(s) ? size : -1;
if (bytes_indicated < size) {