diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 0c5415b..42c43b6 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -330,6 +330,14 @@ config NET_VRF
This option enables the support for mapping interfaces into VRF's. The
support enables VRF devices.
+config VSOCKMON
+ tristate "Virtual vsock monitoring device"
+ depends on VHOST_VSOCK
+ ---help---
+ This option enables a monitoring net device for vsock sockets. It is
+ mostly intended for developers or support to debug vsock issues. If
+ unsure, say N.
+
endif # NET_CORE
config SUNGEM_PHY
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 7336cbd..e2188d4 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_GENEVE) += geneve.o
obj-$(CONFIG_GTP) += gtp.o
obj-$(CONFIG_NLMON) += nlmon.o
obj-$(CONFIG_NET_VRF) += vrf.o
+obj-$(CONFIG_VSOCKMON) += vsockmon.o
#
# Networking Drivers
diff --git a/drivers/net/vsockmon.c b/drivers/net/vsockmon.c
new file mode 100644
index 0000000..9ad4f0a
--- /dev/null
+++ b/drivers/net/vsockmon.c
@@ -0,0 +1,168 @@
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/if_arp.h>
+#include <net/rtnetlink.h>
+#include <net/sock.h>
+#include <net/af_vsock.h>
+#include <uapi/linux/vsockmon.h>
+#include <linux/virtio_vsock.h>
+
+/* Virtio transport max packet size plus header */
+#define DEFAULT_MTU VIRTIO_VSOCK_MAX_PKT_BUF_SIZE + sizeof(struct af_vsockmon_hdr);
+
+struct pcpu_lstats {
+ u64 rx_packets;
+ u64 rx_bytes;
+ struct u64_stats_sync syncp;
+};
+
+static int vsockmon_dev_init(struct net_device *dev)
+{
+ dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
+ return dev->lstats == NULL ? -ENOMEM : 0;
+}
+
+static void vsockmon_dev_uninit(struct net_device *dev)
+{
+ free_percpu(dev->lstats);
+}
+
+struct vsockmon {
+ struct vsock_tap vt;
+};
+
+static int vsockmon_open(struct net_device *dev)
+{
+ struct vsockmon *vsockmon = netdev_priv(dev);
+
+ vsockmon->vt.dev = dev;
+ vsockmon->vt.module = THIS_MODULE;
+ return vsock_add_tap(&vsockmon->vt);
+}
+
+static int vsockmon_close(struct net_device *dev) {
+ struct vsockmon *vsockmon = netdev_priv(dev);
+
+ return vsock_remove_tap(&vsockmon->vt);
+}
+
+static netdev_tx_t vsockmon_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ int len = skb->len;
+ struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
+
+ u64_stats_update_begin(&stats->syncp);
+ stats->rx_bytes += len;
+ stats->rx_packets++;
+ u64_stats_update_end(&stats->syncp);
+
+ dev_kfree_skb(skb);
+
+ return NETDEV_TX_OK;
+}
+
+static struct rtnl_link_stats64 *
+vsockmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
+{
+ int i;
+ u64 bytes = 0, packets = 0;
+
+ for_each_possible_cpu(i) {
+ const struct pcpu_lstats *vstats;
+ u64 tbytes, tpackets;
+ unsigned int start;
+
+ vstats = per_cpu_ptr(dev->lstats, i);
+
+ do {
+ start = u64_stats_fetch_begin_irq(&vstats->syncp);
+ tbytes = vstats->rx_bytes;
+ tpackets = vstats->rx_packets;
+ } while (u64_stats_fetch_retry_irq(&vstats->syncp, start));
+
+ packets += tpackets;
+ bytes += tbytes;
+ }
+
+ stats->rx_packets = packets;
+ stats->tx_packets = 0;
+
+ stats->rx_bytes = bytes;
+ stats->tx_bytes = 0;
+
+ return stats;
+}
+
+static int vsockmon_is_valid_mtu(int new_mtu)
+{
+ return new_mtu >= (int) sizeof(struct af_vsockmon_hdr);
+}
+
+static int vsockmon_change_mtu(struct net_device *dev, int new_mtu)
+{
+ if (!vsockmon_is_valid_mtu(new_mtu))
+ return -EINVAL;
+
+ dev->mtu = new_mtu;
+ return 0;
+}
+
+static const struct net_device_ops vsockmon_ops = {
+ .ndo_init = vsockmon_dev_init,
+ .ndo_uninit = vsockmon_dev_uninit,
+ .ndo_open = vsockmon_open,
+ .ndo_stop = vsockmon_close,
+ .ndo_start_xmit = vsockmon_xmit,
+ .ndo_get_stats64 = vsockmon_get_stats64,
+ .ndo_change_mtu = vsockmon_change_mtu,
+};
+
+static u32 always_on(struct net_device *dev)
+{
+ return 1;
+}
+
+static const struct ethtool_ops vsockmon_ethtool_ops = {
+ .get_link = always_on,
+};
+
+static void vsockmon_setup(struct net_device *dev)
+{
+ dev->type = ARPHRD_VSOCKMON;
+ dev->priv_flags |= IFF_NO_QUEUE;
+
+ dev->netdev_ops = &vsockmon_ops;
+ dev->ethtool_ops = &vsockmon_ethtool_ops;
+ dev->destructor = free_netdev;
+
+ dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
+ NETIF_F_HIGHDMA | NETIF_F_LLTX;
+
+ dev->flags = IFF_NOARP;
+
+ dev->mtu = DEFAULT_MTU;
+}
+
+static struct rtnl_link_ops vsockmon_link_ops __read_mostly = {
+ .kind = "vsockmon",
+ .priv_size = sizeof(struct vsockmon),
+ .setup = vsockmon_setup,
+};
+
+static __init int vsockmon_register(void)
+{
+ return rtnl_link_register(&vsockmon_link_ops);
+}
+
+static __exit void vsockmon_unregister(void)
+{
+ rtnl_link_unregister(&vsockmon_link_ops);
+}
+
+module_init(vsockmon_register);
+module_exit(vsockmon_unregister);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Gerard Garcia <ggarcia@deic.uab.cat>");
+MODULE_DESCRIPTION("Vsock monitoring device. Based on nlmon device.");
+MODULE_ALIAS_RTNL_LINK("vsockmon");diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index 185f8ea..ef7f878 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -456,6 +456,7 @@ header-y += virtio_scsi.h
header-y += virtio_types.h
header-y += virtio_vsock.h
header-y += vm_sockets.h
+header-y += vsockmon.h
header-y += vt.h
header-y += vtpm_proxy.h
header-y += wait.h
diff --git a/include/uapi/linux/vsockmon.h b/include/uapi/linux/vsockmon.h
new file mode 100644
index 0000000..0e9c54e
--- /dev/null
+++ b/include/uapi/linux/vsockmon.h
@@ -0,0 +1,38 @@
+#ifndef _UAPI_VSOCKMON_H
+#define _UAPI_VSOCKMON_H
+
+#include <linux/virtio_vsock.h>
+
+/*
+ * Structure of packets received through the vsockmon device.
+ *
+ * Note that after the vsockmon header comes the transport header (len bytes and
+ * type specified by t) and if the packet op is AF_VSOCK_OP_PAYLOAD then comes
+ * the payload.
+ */
+
+struct af_vsockmon_hdr {
+ __le64 src_cid;
+ __le64 dst_cid;
+ __le32 src_port;
+ __le32 dst_port;
+ __le16 op; /* enum af_vsockmon_op */
+ __le16 t; /* enum af_vosckmon_t */
+ __le16 len; /* Transport header length */
+} __attribute__((packed));
+
+enum af_vsockmon_op {
+ AF_VSOCK_OP_UNKNOWN = 0,
+ AF_VSOCK_OP_CONNECT = 1,
+ AF_VSOCK_OP_DISCONNECT = 2,
+ AF_VSOCK_OP_CONTROL = 3,
+ AF_VSOCK_OP_PAYLOAD = 4,
+};
+
+enum af_vsockmon_t {
+ AF_VSOCK_T_UNKNOWN = 0,
+ AF_VSOCK_T_NO_INFO = 1, /* No transport information */
+ AF_VSOCK_T_VIRTIO = 2, /* Virtio transport header (struct virtio_vsock_hdr) */
+};
+
+#endif--
2.9.1