Merge branch 'VSOCK-add-vsockmon'

Stefan Hajnoczi says:

====================
VSOCK: vsockmon virtual device to monitor AF_VSOCK sockets.

v5:
 * Change vsock_deliver_tap() API to avoid unnecessary skb creation
   [Jorgen]
 * Fix skb leak when no taps are registered [Jorgen]
 * s/cpu_to_le16(pkt->hdr.op)/le16_to_cpu(pkt->hdr.op)/ [Michael]
 * Add af_vsock_tap.c and vsockmon.[ch] to MAINTAINERS
 * checkpatch.pl and sparse fixes

v4:
 * Add explicit reserved padding field to struct af_vsockmon_hdr and
   drop __attribute__((packed)) [Michael, DaveM]
 * Call synchronize_net() before module_put() [Michael]

v3:
 * Hook virtio_transport.c (guest driver), not just drivers/vhost/vsock.c (host
   driver)
 * Fix DEFAULT_MTU macro definition [Zhu Yanjun]
 * Rename af_vsockmon_hdr->t field ->transport for clarity
 * Update .ndo_get_stats64() return type since it has changed
 * Include missing <linux/module.h> header in af_vsock_tap.c

This is a continuation of Gerard Garcia's work on the vsockmon packet capture
interface for AF_VSOCK.  Packet capture is an essential feature for network
communication.  Gerard began addressing this feature gap in his Google Summer
of Code 2016 project.  I have cleaned up, rebased, and retested the v2 series
he posted previously.

The design follows the nlmon packet capture interface closely.  This is because
vsock has the same problem as netlink: there is no netdev on which packets can
be captured.  The nlmon driver is a synthetic netdev purely for the purpose of
enabling packet capture.  We follow the same approach here with vsockmon.

See include/uapi/linux/vsockmon.h in this series for details on the packet
layout.

How to try it:

1. Build tcpdump with vsockmon patches:

  $ git clone -b vsock https://github.com/stefanha/libpcap
  $ (cd libcap && ./configure && make)
  $ git clone -b vsock https://github.com/stefanha/tcpdump
  $ (cd tcpdump && ./configure && make)

2. Build nc-vsock (a netcat-like tool):

  $ git clone https://github.com/stefanha/nc-vsock
  $ (cd nc-vsock && make)

3. Launch a virtual machine:

  # modprobe vhost_vsock
  # qemu-system-x86_64 -M accel=kvm -m 1024 -cpu host \
      -drive if=virtio,file=test.img,format=raw \
      -device vhost-vsock-pci,guest-cid=3

  (Assumes guest is running a kernel with this patch)

4. Capture AF_VSOCK traffic in guest and/or host:

  # modprobe vsockmon
  # ip link add type vsockmon
  # ip link set vsockmon0 up
  # tcpdump -i vsockmon0 -vvv

5. Communicate!

  (host)$ nc-vsock -l 1234
  (guest)$ nc-vsock 2 1234
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 76 insertions, 0 deletions

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 584f9a647ad4..ab13f0743da8 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -153,5 +153,6 @@ void virtio_transport_free_pkt(struct virtio_vsock_pkt *pkt);
 void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt);
 u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 wanted);
 void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit);
+void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt);
 
 #endif /* _LINUX_VIRTIO_VSOCK_H */
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index f32ed9ac181a..f9fb566e75cf 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -188,4 +188,17 @@ struct sock *vsock_find_connected_socket(struct sockaddr_vm *src,
 void vsock_remove_sock(struct vsock_sock *vsk);
 void vsock_for_each_connected_socket(void (*fn)(struct sock *sk));
 
+/**** TAP ****/
+
+struct vsock_tap {
+	struct net_device *dev;
+	struct module *module;
+	struct list_head list;
+};
+
+int vsock_init_tap(void);
+int vsock_add_tap(struct vsock_tap *vt);
+int vsock_remove_tap(struct vsock_tap *vt);
+void vsock_deliver_tap(struct sk_buff *build_skb(void *opaque), void *opaque);
+
 #endif /* __AF_VSOCK_H__ */
diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index f8d9fed17ba9..6b0e2758585f 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -477,6 +477,7 @@ header-y += virtio_types.h
 header-y += virtio_vsock.h
 header-y += virtio_crypto.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/if_arp.h b/include/uapi/linux/if_arp.h
index 4d024d75d64b..cf73510b9238 100644
--- a/include/uapi/linux/if_arp.h
+++ b/include/uapi/linux/if_arp.h
@@ -95,6 +95,7 @@
 #define ARPHRD_IP6GRE	823		/* GRE over IPv6		*/
 #define ARPHRD_NETLINK	824		/* Netlink header		*/
 #define ARPHRD_6LOWPAN	825		/* IPv6 over LoWPAN             */
+#define ARPHRD_VSOCKMON	826		/* Vsock monitor header		*/
 
 #define ARPHRD_VOID	  0xFFFF	/* Void type, nothing is known */
 #define ARPHRD_NONE	  0xFFFE	/* zero header length */
diff --git a/include/uapi/linux/vsockmon.h b/include/uapi/linux/vsockmon.h
new file mode 100644
index 000000000000..a08b522ef597
--- /dev/null
+++ b/include/uapi/linux/vsockmon.h
@@ -0,0 +1,60 @@
+#ifndef _UAPI_VSOCKMON_H
+#define _UAPI_VSOCKMON_H
+
+#include <linux/virtio_vsock.h>
+
+/*
+ * vsockmon is the AF_VSOCK packet capture device.  Packets captured have the
+ * following layout:
+ *
+ *   +-----------------------------------+
+ *   |           vsockmon header         |
+ *   |      (struct af_vsockmon_hdr)     |
+ *   +-----------------------------------+
+ *   |          transport header         |
+ *   | (af_vsockmon_hdr->len bytes long) |
+ *   +-----------------------------------+
+ *   |              payload              |
+ *   |       (until end of packet)       |
+ *   +-----------------------------------+
+ *
+ * The vsockmon header is a transport-independent description of the packet.
+ * It duplicates some of the information from the transport header so that
+ * no transport-specific knowledge is necessary to process packets.
+ *
+ * The transport header is useful for low-level transport-specific packet
+ * analysis.  Transport type is given in af_vsockmon_hdr->transport and
+ * transport header length is given in af_vsockmon_hdr->len.
+ *
+ * If af_vsockmon_hdr->op is AF_VSOCK_OP_PAYLOAD then the payload follows the
+ * transport header.  Other ops do not have a payload.
+ */
+
+struct af_vsockmon_hdr {
+	__le64 src_cid;
+	__le64 dst_cid;
+	__le32 src_port;
+	__le32 dst_port;
+	__le16 op;			/* enum af_vsockmon_op */
+	__le16 transport;		/* enum af_vsockmon_transport */
+	__le16 len;			/* Transport header length */
+	__u8 reserved[2];
+};
+
+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_transport {
+	AF_VSOCK_TRANSPORT_UNKNOWN = 0,
+	AF_VSOCK_TRANSPORT_NO_INFO = 1,	/* No transport information */
+
+	/* Transport header type: struct virtio_vsock_hdr */
+	AF_VSOCK_TRANSPORT_VIRTIO = 2,
+};
+
+#endif