Subject: [PATCH 9/12] L2 network namespace (v3): device to pass packets between namespaces

From: Dmitry Mishin <[email-masked]>
Date: Wed, 17 Jan 2007 19:14:00 +0300

A simple device to pass packets between a namespace and its child.

Signed-off-by: Dmitry Mishin <[email-masked]>

---
 drivers/net/Makefile     |    3 
 drivers/net/veth.c       |  321 +++++++++++++++++++++++++++++++++++++++++++++++
 net/core/net_namespace.c |    1 
 3 files changed, 325 insertions(+)

--- linux-2.6.20-rc4-mm1.net_ns.orig/drivers/net/Makefile
+++ linux-2.6.20-rc4-mm1.net_ns/drivers/net/Makefile
@@ -125,6 +125,9 @@ obj-$(CONFIG_SLIP) += slip.o
 obj-$(CONFIG_SLHC) += slhc.o
 
 obj-$(CONFIG_DUMMY) += dummy.o
+ifeq ($(CONFIG_NET_NS),y)
+obj-m += veth.o
+endif
 obj-$(CONFIG_IFB) += ifb.o
 obj-$(CONFIG_DE600) += de600.o
 obj-$(CONFIG_DE620) += de620.o
--- /dev/null
+++ linux-2.6.20-rc4-mm1.net_ns/drivers/net/veth.c
@@ -0,0 +1,321 @@
+/*
+ * Copyright (C) 2006  SWsoft
+ *
+ * Written by Andrey Savochkin <[email-masked]>,
+ * reusing code by Andrey Mirkin <[email-masked]>.
+ */
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/ctype.h>
+#include <asm/semaphore.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <net/dst.h>
+#include <net/xfrm.h>
+
+struct veth_struct
+{
+	struct net_device	*pair;
+	struct net_device_stats stats;
+};
+
+#define veth_from_netdev(dev) ((struct veth_struct *)(netdev_priv(dev)))
+
+/* ------------------------------------------------------------------- *
+ *
+ * Device functions
+ *
+ * ------------------------------------------------------------------- */
+
+static struct net_device_stats *get_stats(struct net_device *dev);
+static int veth_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct net_device_stats *stats;
+	struct veth_struct *entry;
+	struct net_device *rcv;
+	struct net_namespace *orig_net_ns;
+	int length;
+
+	stats = get_stats(dev);
+	entry = veth_from_netdev(dev);
+	rcv = entry->pair;
+
+	if (!(rcv->flags & IFF_UP))
+		/* Target namespace does not want to receive packets */
+		goto outf;
+
+	dst_release(skb->dst);
+	skb->dst = NULL;
+	secpath_reset(skb);
+	skb_orphan(skb);
+	nf_reset(skb);
+
+	orig_net_ns = push_net_ns(rcv->net_ns);
+	skb->dev = rcv;
+	skb->pkt_type = PACKET_HOST;
+	skb->protocol = eth_type_trans(skb, rcv);
+
+	length = skb->len;
+	stats->tx_bytes += length;
+	stats->tx_packets++;
+	stats = get_stats(rcv);
+	stats->rx_bytes += length;
+	stats->rx_packets++;
+
+	netif_rx(skb);
+	pop_net_ns(orig_net_ns);
+	return 0;
+
+outf:
+	stats->tx_dropped++;
+	kfree_skb(skb);
+	return 0;
+}
+
+static int veth_open(struct net_device *dev)
+{
+	return 0;
+}
+
+static int veth_close(struct net_device *dev)
+{
+	return 0;
+}
+
+static void veth_destructor(struct net_device *dev)
+{
+	free_netdev(dev);
+}
+
+static struct net_device_stats *get_stats(struct net_device *dev)
+{
+	return &veth_from_netdev(dev)->stats;
+}
+
+int veth_init_dev(struct net_device *dev)
+{
+	dev->hard_start_xmit = veth_xmit;
+	dev->open = veth_open;
+	dev->stop = veth_close;
+	dev->destructor = veth_destructor;
+	dev->get_stats = get_stats;
+
+	ether_setup(dev);
+
+	dev->tx_queue_len = 0;
+	return 0;
+}
+
+static void veth_setup(struct net_device *dev)
+{
+	dev->init = veth_init_dev;
+}
+
+static inline int is_veth_dev(struct net_device *dev)
+{
+	return dev->init == veth_init_dev;
+}
+
+/* ------------------------------------------------------------------- *
+ *
+ * Management interface
+ *
+ * ------------------------------------------------------------------- */
+
+struct net_device *veth_dev_alloc(char *name, char *addr)
+{
+	struct net_device *dev;
+
+	dev = alloc_netdev(sizeof(struct veth_struct), name, veth_setup);
+	if (dev != NULL) {
+		memcpy(dev->dev_addr, addr, ETH_ALEN);
+		dev->addr_len = ETH_ALEN;
+	}
+	return dev;
+}
+
+int veth_entry_add(char *parent_name, char *parent_addr,
+	struct net_namespace *parent_ns, char *child_name, char *child_addr,
+						struct net_namespace *child_ns)
+{
+	struct net_device *parent_dev, *child_dev;
+	int err;
+
+	err = -ENOMEM;
+	if ((parent_dev = veth_dev_alloc(parent_name, parent_addr)) == NULL)
+		goto out_alocp;
+	if ((child_dev = veth_dev_alloc(child_name, child_addr)) == NULL)
+		goto out_alocc;
+	veth_from_netdev(parent_dev)->pair = child_dev;
+	veth_from_netdev(child_dev)->pair = parent_dev;
+
+	/*
+	 * About serialization, see comments to veth_pair_del().
+	 */
+	rtnl_lock();
+	/* refcounts should be already upped, so, just put old ones */
+	put_net_ns(parent_dev->net_ns);
+	parent_dev->net_ns = parent_ns;
+	if ((err = register_netdevice(parent_dev)))
+		goto out_regp;
+
+	put_net_ns(child_dev->net_ns);
+	child_dev->net_ns = child_ns;
+	if ((err = register_netdevice(child_dev)))
+		goto out_regc;
+	rtnl_unlock();
+	return 0;
+
+out_regc:
+	unregister_netdevice(parent_dev);
+	rtnl_unlock();
+	free_netdev(child_dev);
+	return err;
+
+out_regp:
+	rtnl_unlock();
+	free_netdev(child_dev);
+out_alocc:
+	free_netdev(parent_dev);
+out_alocp:
+	return err;
+}
+
+static void veth_pair_del(struct net_device *parent_dev)
+{
+	struct net_device *child_dev;
+	struct net_namespace *parent_ns, *child_ns;
+
+	child_dev = veth_from_netdev(parent_dev)->pair;
+	get_net_ns(child_dev->net_ns);
+	child_ns = child_dev->net_ns;
+
+	dev_close(child_dev);
+	synchronize_net();
+	/*
+	 * Now child_dev does not send or receives anything.
+	 * This means child_dev->hard_start_xmit is not called anymore.
+	 */
+	unregister_netdevice(parent_dev);
+	/*
+	 * At this point child_dev has dead pointer to parent_dev.
+	 * But this pointer is not dereferenced.
+	 */
+	parent_ns = push_net_ns(child_ns);
+	unregister_netdevice(child_dev);
+	pop_net_ns(parent_ns);
+
+	put_net_ns(child_ns);
+}
+
+int veth_entry_del(char *parent_name)
+{
+	struct net_device *dev;
+
+	if ((dev = dev_get_by_name(parent_name)) == NULL)
+		return -ENODEV;
+
+	rtnl_lock();
+	veth_pair_del(dev);
+	dev_put(dev);
+	rtnl_unlock();
+
+	return 0;
+}
+
+void veth_entry_del_all(void)
+{
+	struct net_device **p, *dev;
+
+	rtnl_lock();
+	for (p = &dev_base; (dev = *p) != NULL; ) {
+		if (!is_veth_dev(dev)) {
+			p = &dev->next;
+			continue;
+		}
+
+		dev_hold(dev);
+		veth_pair_del(dev);
+		dev_put(dev);
+	}
+	rtnl_unlock();
+}
+
+/* ------------------------------------------------------------------- *
+ *
+ * Information in proc
+ *
+ * ------------------------------------------------------------------- */
+
+#ifdef CONFIG_PROC_FS
+
+#define ADDR_FMT "%02x:%02x:%02x:%02x:%02x:%02x"
+#define ADDR(x) (x)[0],(x)[1],(x)[2],(x)[3],(x)[4],(x)[5]
+#define ADDR_HDR "%-17s"
+
+static int veth_proc_show(struct seq_file *m,
+		struct net_device *dev, void *data)
+{
+	struct net_device *pair;
+
+	if (dev == SEQ_START_TOKEN) {
+		seq_puts(m, "Version: 1.0\n");
+		seq_printf(m, "%-*s " ADDR_HDR " %-*s " ADDR_HDR "\n",
+				IFNAMSIZ, "Name", "Address",
+				IFNAMSIZ, "PeerName", "PeerAddress");
+		return 0;
+	}
+
+	if (!is_veth_dev(dev))
+		return 0;
+
+	pair = veth_from_netdev(dev)->pair;
+	seq_printf(m, "%-*s " ADDR_FMT " %-*s " ADDR_FMT "\n",
+			IFNAMSIZ, dev->name, ADDR(dev->dev_addr),
+			IFNAMSIZ, pair->name, ADDR(pair->dev_addr));
+	return 0;
+}
+
+static int veth_proc_create(void)
+{
+	return netdev_proc_create("veth_list", &veth_proc_show, NULL,
+			THIS_MODULE);
+}
+
+static void veth_proc_remove(void)
+{
+	netdev_proc_remove("net/veth_list");
+}
+
+#else
+
+static inline int veth_proc_create(void) { return 0; }
+static inline void veth_proc_remove(void) { }
+
+#endif
+
+/* ------------------------------------------------------------------- *
+ *
+ * Module initialization
+ *
+ * ------------------------------------------------------------------- */
+
+int __init veth_init(void)
+{
+	veth_proc_create();
+	return 0;
+}
+
+void __exit veth_exit(void)
+{
+	veth_proc_remove();
+	veth_entry_del_all();
+}
+
+module_init(veth_init)
+module_exit(veth_exit)
+
+MODULE_DESCRIPTION("Virtual Ethernet Device");
+MODULE_LICENSE("GPL v2");
--- linux-2.6.20-rc4-mm1.net_ns.orig/net/core/net_namespace.c
+++ linux-2.6.20-rc4-mm1.net_ns/net/core/net_namespace.c
@@ -111,5 +111,6 @@ void free_net_ns(struct kref *kref)
 	ip_fib_struct_cleanup(ns);
 	kfree(ns);
 }
+EXPORT_SYMBOL_GPL(free_net_ns);
 
 #endif /* CONFIG_NET_NS */