[RFC v2 0/3] vsockmon: virtual device to monitor AF_VSOCK sockets.

[RFC v2 0/3] vsockmon: virtual device to monitor AF_VSOCK sockets.

[ggarcia]

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

v2:
 * Various simple fixes from the comments received to the first RFC.
 * Do not clone skb, instead take ownership before transmitting.
 * Split tap functions from af_vsock.c.
 * Simplify vsockmon header to remove unnecessary padding and set little endian byte order.

Additionally, we are implementing a tcpdump printer (RFC: http://lists.sandelman.ca/pipermail/tcpdump-workers/2016-June/000546.html, patches: https://github.com/GerardGarcia/tcpdump/tree/vsock) and a wireshark dissector (in progress) to be able to easily monitor vsockmon devices. 

Overview:

Virtual socket transports operate at kernel level therefore, there is no easy way to see the traffic exchanged between virtual machines and hypervisors that communicate using AF_VSOCK sockets. In addition, being able to see the control messages exchanged by the transports may be useful for debugging and optimization purposes. This patch adds a virtual device that may be used to see the traffic exchanged between virtual machines and hypervisors through AF_VSOCK sockets.

Its structure is based on the nlmon device and this version just targets the virtio transport, but support for the VMCI transport can be easily implemented. The vsockmon header consists of two structs: a generic header and a header specific to the transport. The generic header allows to follow an AF_VSOCK stream without having to understand the details of the transport while the transport header gives more detail which may be useful for troubleshooting and debugging.

The repository https://github.com/GerardGarcia/linux/tree/vsockmon implements these patches over the Stefan Hajnoczi vsock-next repository https://github.com/stefanha/linux/tree/vsock-next where the virtio trasnport is implemented. In the repository there is also a simple program that shows the traffic from a vsockmon device: https://github.com/GerardGarcia/linux/blob/vsockmon/vsockmon.c that can be used for testing.

Any thoughts and comments will be greatly appreciated.

Thanks to Stefan Hajnoczi for his help.

Gerard

Gerard Garcia (3):
  vsockmon: Add tap functions
  vsockmon: Add vsockmon device
  vsockmon: Add vsock hooks

 drivers/net/Kconfig           |   8 ++
 drivers/net/Makefile          |   1 +
 drivers/net/vsockmon.c        | 167 ++++++++++++++++++++++++++++++++++++++++++
 drivers/vhost/vsock.c         |  73 ++++++++++++++++++
 include/net/af_vsock.h        |  13 ++++
 include/uapi/linux/Kbuild     |   1 +
 include/uapi/linux/if_arp.h   |   1 +
 include/uapi/linux/vsockmon.h |  35 +++++++++
 net/vmw_vsock/Makefile        |   2 +-
 net/vmw_vsock/af_vsock_tap.c  | 112 ++++++++++++++++++++++++++++
 10 files changed, 412 insertions(+), 1 deletion(-)
 create mode 100644 drivers/net/vsockmon.c
 create mode 100644 include/uapi/linux/vsockmon.h
 create mode 100644 net/vmw_vsock/af_vsock_tap.c

-- 
2.9.0

[RFC v2 1/3] vsockmon: Add tap functions

[ggarcia]

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

Signed-off-by: Gerard Garcia <ggarcia@deic.uab.cat>
---
 include/net/af_vsock.h       |  13 +++++
 include/uapi/linux/if_arp.h  |   1 +
 net/vmw_vsock/Makefile       |   2 +-
 net/vmw_vsock/af_vsock_tap.c | 112 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 net/vmw_vsock/af_vsock_tap.c

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 15694c9..5bd7487 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -187,4 +187,17 @@ struct sock *vsock_find_connected_socket(struct sockaddr_vm *src,
 					 struct sockaddr_vm *dst);
 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 *skb);
+
 #endif /* __AF_VSOCK_H__ */
diff --git a/include/uapi/linux/if_arp.h b/include/uapi/linux/if_arp.h
index 4d024d7..cf73510 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/net/vmw_vsock/Makefile b/net/vmw_vsock/Makefile
index cf4c294..4dc3094 100644
--- a/net/vmw_vsock/Makefile
+++ b/net/vmw_vsock/Makefile
@@ -3,7 +3,7 @@ obj-$(CONFIG_VMWARE_VMCI_VSOCKETS) += vmw_vsock_vmci_transport.o
 obj-$(CONFIG_VIRTIO_VSOCKETS) += virtio_transport.o
 obj-$(CONFIG_VIRTIO_VSOCKETS_COMMON) += virtio_transport_common.o
 
-vsock-y += af_vsock.o vsock_addr.o
+vsock-y += af_vsock.o af_vsock_tap.o vsock_addr.o
 
 vmw_vsock_vmci_transport-y += vmci_transport.o vmci_transport_notify.o \
 	vmci_transport_notify_qstate.o
diff --git a/net/vmw_vsock/af_vsock_tap.c b/net/vmw_vsock/af_vsock_tap.c
new file mode 100644
index 0000000..a92aaff
--- /dev/null
+++ b/net/vmw_vsock/af_vsock_tap.c
@@ -0,0 +1,112 @@
+/*
+ * Tap functions for AF_VSOCK sockets.
+ *
+ * Code based on net/netlink/af_netlink.c tap functions.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <net/af_vsock.h>
+
+static DEFINE_SPINLOCK(vsock_tap_lock);
+static struct list_head vsock_tap_all __read_mostly =
+				LIST_HEAD_INIT(vsock_tap_all);
+
+int vsock_add_tap(struct vsock_tap *vt) {
+	if (unlikely(vt->dev->type != ARPHRD_VSOCKMON))
+		return -EINVAL;
+
+	__module_get(vt->module);
+
+	spin_lock(&vsock_tap_lock);
+	list_add_rcu(&vt->list, &vsock_tap_all);
+	spin_unlock(&vsock_tap_lock);
+
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vsock_add_tap);
+
+int __vsock_remove_tap(struct vsock_tap *vt) {
+	bool found = false;
+	struct vsock_tap *tmp;
+
+	spin_lock(&vsock_tap_lock);
+
+	list_for_each_entry(tmp, &vsock_tap_all, list) {
+		if (vt == tmp) {
+			list_del_rcu(&vt->list);
+			found = true;
+			goto out;
+		}
+	}
+
+	pr_warn("__vsock_remove_tap: %p not found\n", vt);
+out:
+	spin_unlock(&vsock_tap_lock);
+
+	if (found)
+		module_put(vt->module);
+
+	return found ? 0 : -ENODEV;
+}
+
+int vsock_remove_tap(struct vsock_tap *vt)
+{
+	int ret;
+
+	ret = __vsock_remove_tap(vt);
+	synchronize_net();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vsock_remove_tap);
+
+static int __vsock_deliver_tap_skb(struct sk_buff *skb,
+				     struct net_device *dev)
+{
+	int ret = 0;
+
+	if (skb) {
+		dev_hold(dev);
+		/* Take skb ownership so it is not consumed in dev_queue_xmit.
+		 * dev_queue_xmit will drop a reference so the reference count
+		 * will reset.
+		 */
+		skb_get(skb);
+		skb->dev = dev;
+		ret = dev_queue_xmit(skb);
+		if (unlikely(ret > 0))
+			ret = net_xmit_errno(ret);
+
+		dev_put(dev);
+	}
+
+	return ret;
+}
+
+static void __vsock_deliver_tap(struct sk_buff *skb)
+{
+	int ret;
+	struct vsock_tap *tmp;
+
+	list_for_each_entry_rcu(tmp, &vsock_tap_all, list) {
+		ret = __vsock_deliver_tap_skb(skb, tmp->dev);
+		if (unlikely(ret))
+			break;
+	}
+}
+
+void vsock_deliver_tap(struct sk_buff *skb)
+{
+	rcu_read_lock();
+
+	if (unlikely(!list_empty(&vsock_tap_all)))
+		__vsock_deliver_tap(skb);
+
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(vsock_deliver_tap);
-- 
2.9.0

[RFC v2 2/3] vsockmon: Add vsockmon device

[ggarcia]

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

Signed-off-by: Gerard Garcia <ggarcia@deic.uab.cat>
---
 drivers/net/Kconfig           |   8 ++
 drivers/net/Makefile          |   1 +
 drivers/net/vsockmon.c        | 167 ++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/Kbuild     |   1 +
 include/uapi/linux/vsockmon.h |  35 +++++++++
 5 files changed, 212 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..7deeba0
--- /dev/null
+++ b/drivers/net/vsockmon.c
@@ -0,0 +1,167 @@
+#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>
+
+/* Virtio transport max packet size plus header */
+#define DEFAULT_MTU 1024 * 64 + 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 5f047d2..b1836cc 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -454,6 +454,7 @@ 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 += wait.h
 header-y += wanrouter.h
diff --git a/include/uapi/linux/vsockmon.h b/include/uapi/linux/vsockmon.h
new file mode 100644
index 0000000..29a761c
--- /dev/null
+++ b/include/uapi/linux/vsockmon.h
@@ -0,0 +1,35 @@
+#ifndef _UAPI_VSOCKMON_H
+#define _UAPI_VSOCKMON_H
+
+#include <linux/virtio_vsock.h>
+
+/* Structure of packets received trought the vsockmon device.
+ */
+
+struct af_vsockmon_hdr {
+	__le64 src_cid;
+	__le32 src_port;
+	__le64 dst_cid;
+	__le32 dst_port;
+	__le16 op;			/* enum af_vsockmon_op */
+	__le16 t;			/* enum af_vosckmon_t */
+	union {
+		struct virtio_vsock_hdr virtio_hdr;
+	} t_hdr;
+};
+
+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 */
+};
+
+#endif
-- 
2.9.0

[RFC v2 3/3] vsockmon: Add vsock hooks

[ggarcia]

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

Signed-off-by: Gerard Garcia <ggarcia@deic.uab.cat>
---
 drivers/vhost/vsock.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 17bfe4e..e8621cc 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -14,8 +14,10 @@
 #include <net/sock.h>
 #include <linux/virtio_vsock.h>
 #include <linux/vhost.h>
+#include <linux/skbuff.h>
 
 #include <net/af_vsock.h>
+#include <uapi/linux/vsockmon.h>
 #include "vhost.h"
 
 #define VHOST_VSOCK_DEFAULT_HOST_CID	2
@@ -45,6 +47,69 @@ struct vhost_vsock {
 	u32 guest_cid;
 };
 
+static struct sk_buff *
+virtio_vsock_pkt_to_skb(struct virtio_vsock_pkt *pkt)
+{
+	struct sk_buff *skb;
+	struct af_vsockmon_hdr *hdr;
+	void *payload;
+
+	u32 skb_len = sizeof(struct af_vsockmon_hdr) + pkt->len;
+
+	skb = alloc_skb(skb_len, GFP_ATOMIC);
+	if (!skb)
+		return NULL;
+
+	skb_reserve(skb, sizeof(struct af_vsockmon_hdr));
+
+	if (pkt->len) {
+		payload = skb_put(skb, pkt->len);
+		memcpy(payload, pkt->buf, pkt->len);
+	}
+
+	hdr = (struct af_vsockmon_hdr *) skb_push(skb, sizeof(*hdr));
+
+	hdr->src_cid = pkt->hdr.src_cid;
+	hdr->src_port = pkt->hdr.src_port;
+	hdr->dst_cid = pkt->hdr.dst_cid;
+	hdr->dst_port = pkt->hdr.dst_port;
+	hdr->t = AF_VSOCK_T_VIRTIO;
+
+	switch(pkt->hdr.op) {
+		case VIRTIO_VSOCK_OP_REQUEST:
+		case VIRTIO_VSOCK_OP_RESPONSE:
+			hdr->op = AF_VSOCK_OP_CONNECT;
+			break;
+		case VIRTIO_VSOCK_OP_RST:
+		case VIRTIO_VSOCK_OP_SHUTDOWN:
+			hdr->op = AF_VSOCK_OP_DISCONNECT;
+			break;
+		case VIRTIO_VSOCK_OP_RW:
+			hdr->op = AF_VSOCK_OP_PAYLOAD;
+			break;
+		case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
+		case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
+			hdr->op = AF_VSOCK_OP_CONTROL;
+			break;
+		default:
+			hdr->op = AF_VSOCK_OP_UNKNOWN;
+			break;
+	}
+
+	hdr->t_hdr.virtio_hdr = pkt->hdr;
+
+	return skb;
+}
+
+static void vsock_deliver_tap_pkt(struct virtio_vsock_pkt *pkt)
+{
+	struct sk_buff *skb = virtio_vsock_pkt_to_skb(pkt);
+	if (skb) {
+		vsock_deliver_tap(skb);
+		kfree_skb(skb);
+	}
+}
+
 static u32 vhost_transport_get_local_cid(void)
 {
 	return VHOST_VSOCK_DEFAULT_HOST_CID;
@@ -147,6 +212,11 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
 
 		vsock->total_tx_buf -= pkt->len;
 
+		/* Deliver to monitoring devices all correctly transmitted
+		 * packets.
+		 */
+		vsock_deliver_tap_pkt(pkt);
+
 		virtio_transport_free_pkt(pkt);
 	}
 	if (added)
@@ -367,6 +437,9 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
 			continue;
 		}
 
+		/* Deliver to monitoring devices all received packets */
+		vsock_deliver_tap_pkt(pkt);
+
 		/* Only accept correctly addressed packets */
 		if (le64_to_cpu(pkt->hdr.src_cid) == vsock->guest_cid)
 			virtio_transport_recv_pkt(pkt);
-- 
2.9.0

Re: [RFC v2 3/3] vsockmon: Add vsock hooks

[Sergei Shtylyov]

Hello.

On 6/22/2016 7:11 PM, ggarcia@abra.uab.cat wrote:

> From: Gerard Garcia <ggarcia@deic.uab.cat>
>
> Signed-off-by: Gerard Garcia <ggarcia@deic.uab.cat>
> ---
>  drivers/vhost/vsock.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 73 insertions(+)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 17bfe4e..e8621cc 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
[...]
> @@ -45,6 +47,69 @@ struct vhost_vsock {
>  	u32 guest_cid;
>  };
>
> +static struct sk_buff *
> +virtio_vsock_pkt_to_skb(struct virtio_vsock_pkt *pkt)
> +{
> +	struct sk_buff *skb;
> +	struct af_vsockmon_hdr *hdr;
> +	void *payload;
> +
> +	u32 skb_len = sizeof(struct af_vsockmon_hdr) + pkt->len;
> +
> +	skb = alloc_skb(skb_len, GFP_ATOMIC);
> +	if (!skb)
> +		return NULL;
> +
> +	skb_reserve(skb, sizeof(struct af_vsockmon_hdr));
> +
> +	if (pkt->len) {
> +		payload = skb_put(skb, pkt->len);
> +		memcpy(payload, pkt->buf, pkt->len);
> +	}
> +
> +	hdr = (struct af_vsockmon_hdr *) skb_push(skb, sizeof(*hdr));
> +
> +	hdr->src_cid = pkt->hdr.src_cid;
> +	hdr->src_port = pkt->hdr.src_port;
> +	hdr->dst_cid = pkt->hdr.dst_cid;
> +	hdr->dst_port = pkt->hdr.dst_port;
> +	hdr->t = AF_VSOCK_T_VIRTIO;
> +
> +	switch(pkt->hdr.op) {
> +		case VIRTIO_VSOCK_OP_REQUEST:
> +		case VIRTIO_VSOCK_OP_RESPONSE:
> +			hdr->op = AF_VSOCK_OP_CONNECT;
> +			break;
> +		case VIRTIO_VSOCK_OP_RST:
> +		case VIRTIO_VSOCK_OP_SHUTDOWN:
> +			hdr->op = AF_VSOCK_OP_DISCONNECT;
> +			break;
> +		case VIRTIO_VSOCK_OP_RW:
> +			hdr->op = AF_VSOCK_OP_PAYLOAD;
> +			break;
> +		case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
> +		case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
> +			hdr->op = AF_VSOCK_OP_CONTROL;
> +			break;
> +		default:
> +			hdr->op = AF_VSOCK_OP_UNKNOWN;
> +			break;
> +	}

    CodingStyle: *switch* and *case* should be at the same indentation level.

[...]

MBR, Sergei

Re: [RFC v2 1/3] vsockmon: Add tap functions

[Stefan Hajnoczi]

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On Wed, Jun 22, 2016 at 06:11:00PM +0200, ggarcia@abra.uab.cat wrote:
> +int __vsock_remove_tap(struct vsock_tap *vt) {

This function should be static, it's not used outside this source file.

> +static int __vsock_deliver_tap_skb(struct sk_buff *skb,
> +				     struct net_device *dev)
> +{
> +	int ret = 0;
> +
> +	if (skb) {
> +		dev_hold(dev);

I don't understand the need for this dev_hold()/dev_put().  Can anyone
explain why it is necessary?

> +		/* Take skb ownership so it is not consumed in dev_queue_xmit.
> +		 * dev_queue_xmit will drop a reference so the reference count
> +		 * will reset.
> +		 */
> +		skb_get(skb);
> +		skb->dev = dev;
> +		ret = dev_queue_xmit(skb);
> +		if (unlikely(ret > 0))
> +			ret = net_xmit_errno(ret);
> +
> +		dev_put(dev);
> +	}
> +
> +	return ret;
> +}

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Re: [RFC v2 3/3] vsockmon: Add vsock hooks

[Stefan Hajnoczi]

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On Wed, Jun 22, 2016 at 06:11:02PM +0200, ggarcia@abra.uab.cat wrote:
> +	hdr = (struct af_vsockmon_hdr *) skb_push(skb, sizeof(*hdr));
> +
> +	hdr->src_cid = pkt->hdr.src_cid;
> +	hdr->src_port = pkt->hdr.src_port;
> +	hdr->dst_cid = pkt->hdr.dst_cid;
> +	hdr->dst_port = pkt->hdr.dst_port;
> +	hdr->t = AF_VSOCK_T_VIRTIO;
> +
> +	switch(pkt->hdr.op) {
> +		case VIRTIO_VSOCK_OP_REQUEST:
> +		case VIRTIO_VSOCK_OP_RESPONSE:
> +			hdr->op = AF_VSOCK_OP_CONNECT;
> +			break;
> +		case VIRTIO_VSOCK_OP_RST:
> +		case VIRTIO_VSOCK_OP_SHUTDOWN:
> +			hdr->op = AF_VSOCK_OP_DISCONNECT;
> +			break;
> +		case VIRTIO_VSOCK_OP_RW:
> +			hdr->op = AF_VSOCK_OP_PAYLOAD;
> +			break;
> +		case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
> +		case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
> +			hdr->op = AF_VSOCK_OP_CONTROL;
> +			break;
> +		default:
> +			hdr->op = AF_VSOCK_OP_UNKNOWN;
> +			break;
> +	}

hdr->t and hdr->op need cpu_to_le*() to ensure little-endianness.

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