VSOCK: Add vsockmon device

Add vsockmon virtual network device that receives packets from the vsock
transports and exposes them to user space.

Based on the nlmon device.

Signed-off-by: Gerard Garcia <ggarcia@deic.uab.cat>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 179 insertions, 0 deletions

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 100fbdc9b95c..83a1616903f8 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -355,6 +355,14 @@ 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 57fc47ad5ab3..b2f6556d8848 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -30,6 +30,7 @@ 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 000000000000..7f0136f2dd9d
--- /dev/null
+++ b/drivers/net/vsockmon.c
@@ -0,0 +1,170 @@
+#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);
+	if (!dev->lstats)
+		return -ENOMEM;
+	return 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 void
+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;
+}
+
+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");