[v2,2/3] VSOCK: Add vsockmon device

From: Gerard Garcia <ggarcia@deic.uab.cat>

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>
---
 drivers/net/Kconfig           |   8 ++
 drivers/net/Makefile          |   1 +
 drivers/net/vsockmon.c        | 168 ++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/Kbuild     |   1 +
 include/uapi/linux/vsockmon.h |  38 ++++++++++
 5 files changed, 216 insertions(+)
 create mode 100644 drivers/net/vsockmon.c
 create mode 100644 include/uapi/linux/vsockmon.h

+#define DEFAULT_MTU (VIRTIO_VSOCK_MAX_PKT_BUF_SIZE + sizeof(struct
af_vsockmon_hdr));

It is better.

On Sat, Aug 13, 2016 at 6:21 PM,  <ggarcia@abra.uab.cat> wrote:
> From: Gerard Garcia <ggarcia@deic.uab.cat>
>
> 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>
> ---
>  drivers/net/Kconfig           |   8 ++
>  drivers/net/Makefile          |   1 +
>  drivers/net/vsockmon.c        | 168 ++++++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/Kbuild     |   1 +
>  include/uapi/linux/vsockmon.h |  38 ++++++++++
>  5 files changed, 216 insertions(+)
>  create mode 100644 drivers/net/vsockmon.c
>  create mode 100644 include/uapi/linux/vsockmon.h
>
> 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
>