From: Daniel Lezcano <dlezcano@fr.ibm.com>

For debug purpose only, this is not intended to be included. 
Add /sys/kernel/debug/net_ns.

Creation of network namespace:

echo <level> > /sys/kernel/debug/net_ns/start

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

---
 fs/debugfs/Makefile |    2 
 fs/debugfs/net_ns.c |  335 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 net/Kconfig         |    4 
 3 files changed, 340 insertions(+), 1 deletion(-)

Index: 2.6.20-rc4-mm1/fs/debugfs/Makefile
===================================================================
--- 2.6.20-rc4-mm1.orig/fs/debugfs/Makefile
+++ 2.6.20-rc4-mm1/fs/debugfs/Makefile
@@ -1,4 +1,4 @@
 debugfs-objs	:= inode.o file.o
 
 obj-$(CONFIG_DEBUG_FS)	+= debugfs.o
-
+obj-$(CONFIG_NET_NS_DEBUG) += net_ns.o
Index: 2.6.20-rc4-mm1/fs/debugfs/net_ns.c
===================================================================
--- /dev/null
+++ 2.6.20-rc4-mm1/fs/debugfs/net_ns.c
@@ -0,0 +1,335 @@
+/*
+ *  net_ns.c - adds a net_ns/ directory to debug NET namespaces
+ *
+ *  Author: Daniel Lezcano <dlezcano@fr.ibm.com>
+ *
+ *     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, version 2 of the
+ *     License.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/pagemap.h>
+#include <linux/debugfs.h>
+#include <linux/sched.h>
+#include <linux/netdevice.h>
+#include <linux/inetdevice.h>
+#include <linux/syscalls.h>
+#include <linux/net_namespace.h>
+#include <linux/rtnetlink.h>
+
+static struct dentry *net_ns_dentry;
+static struct dentry *net_ns_dentry_dev;
+static struct dentry *net_ns_dentry_start;
+static struct dentry *net_ns_dentry_info;
+
+static ssize_t net_ns_dev_read_file(struct file *file, char __user *user_buf,
+				    size_t count, loff_t *ppos)
+{
+	return 0;
+}
+
+static ssize_t net_ns_dev_write_file(struct file *file,
+				     const char __user *user_buf,
+				     size_t count, loff_t *ppos)
+{
+	return 0;
+}
+
+static int net_ns_dev_open_file(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+static int net_ns_start_open_file(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+static ssize_t net_ns_start_read_file(struct file *file, char __user *user_buf,
+				      size_t count, loff_t *ppos)
+{
+	return 0;
+}
+
+static ssize_t net_ns_start_write_file(struct file *file,
+				       const char __user *user_buf,
+				       size_t count, loff_t *ppos)
+{
+	int err;
+	size_t len;
+	const char __user *p;
+	char c;
+	unsigned long flags;
+	struct net_namespace *net, *new_net;
+ 	struct nsproxy *new_nsproxy = NULL, *old_nsproxy = NULL;
+
+	if (current_net_ns != &init_net_ns)
+		return -EBUSY;
+
+	len = 0;
+	p = user_buf;
+	while (len < count) {
+		if (get_user(c, p++))
+			return -EFAULT;
+		if (c == 0 || c == '\n')
+			break;
+		len++;
+	}
+
+	if (len > 1)
+		return -EINVAL;
+
+	if (copy_from_user(&c, user_buf, sizeof(c)))
+		return -EFAULT;
+
+	if (c != '2' && c != '3')
+		return -EINVAL;
+
+	flags = (c=='2'?CLONE_NEWNET2:CLONE_NEWNET3);
+ 	err = unshare_net_ns(flags, &new_net);
+	if (err)
+		return err;
+
+ 	old_nsproxy = current->nsproxy;
+ 	new_nsproxy = dup_namespaces(old_nsproxy);
+
+ 	if (!new_nsproxy) {
+ 		put_net_ns(new_net);
+ 		task_unlock(current);
+ 		return -ENOMEM;
+ 	}
+
+ 	task_lock(current);
+
+ 	if (new_nsproxy) {
+ 		current->nsproxy = new_nsproxy;
+ 		new_nsproxy = old_nsproxy;
+ 	}
+
+ 	net = current->nsproxy->net_ns;
+ 	current->nsproxy->net_ns = new_net;
+	pop_net_ns(new_net);
+ 	new_net = net;
+
+ 	task_unlock(current);
+
+ 	put_nsproxy(new_nsproxy);
+ 	put_net_ns(new_net);
+
+	return count;
+}
+
+static int net_ns_info_open_file(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+static ssize_t net_ns_info_read_file(struct file *file, char __user *user_buf,
+				     size_t count, loff_t *ppos)
+{
+	const unsigned int length = 256;
+	size_t len;
+	char buff[length];
+	char *level;
+	struct net_namespace *net_ns = current_net_ns;
+	struct nsproxy *ns = current->nsproxy;
+
+	if (*ppos < 0)
+		return -EINVAL;
+	if (*ppos >= count)
+		return 0;
+	if (!count)
+		return 0;
+
+	switch (net_ns->level) {
+	case NET_NS_LEVEL2:
+		level = "layer 2";
+		break;
+	case NET_NS_LEVEL3:
+		level = "layer 3";
+		break;
+	default:
+		level = "unknown";
+		break;
+	}
+
+ 	sprintf(buff,
+ 		"nsproxy: %p\nnsproxy refcnt: %d\nnet_ns: %p\nnet_ns refcnt: %d\nlevel: %s\n",
+ 		ns,
+ 		atomic_read(&ns->count),
+ 		net_ns,
+ 		atomic_read(&net_ns->kref.refcount),
+ 		level);
+
+	len = strlen(buff);
+	if (len > count)
+		len = count;
+
+	if (copy_to_user(user_buf, buff, len))
+		return -EINVAL;
+
+	*ppos += count;
+
+	return count;
+}
+
+static ssize_t net_ns_info_write_file(struct file *file,
+				      const char __user *user_buf,
+				      size_t count, loff_t *ppos)
+{
+	struct net_namespace *net_ns = current_net_ns;
+	struct net_device *dev;
+	struct in_device *in_dev;
+	struct in_ifaddr **ifap = NULL;
+	struct in_ifaddr *ifa = NULL;
+	char *colon;
+	int err;
+
+	char buff[1024];
+	char *eth, *addr, *s;
+	__be32 address = 0;
+	__be32 p;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	if (net_ns->level != NET_NS_LEVEL3)
+		return -EPERM;
+
+	if (count > sizeof(buff))
+		return -EINVAL;
+
+	if (copy_from_user(buff, user_buf, count))
+		return -EFAULT;
+
+	buff[count] = '\0';
+
+        eth = buff;
+        s = strchr(eth, ' ');
+        if (!s)
+                return -EINVAL;
+        *s = 0;
+
+        addr = s + 1;
+        s = strchr(addr, '.');
+        if (!s)
+                return -EINVAL;
+        *s = 0;
+        p = simple_strtoul(addr, NULL, 0);
+        ((char *)&address)[3] = p;
+        addr = s + 1;
+
+        s = strchr(addr, '.');
+        if (!s)
+                return -EINVAL;
+        *s = 0;
+        p = simple_strtoul(addr, NULL, 0);
+        ((char *)&address)[2] = p;
+        addr = s + 1;
+
+        s = strchr(addr, '.');
+        if (!s)
+                return -EINVAL;
+        *s = 0;
+        p = simple_strtoul(addr, NULL, 0);
+        ((char *)&address)[1] = p;
+        addr = s + 1;
+
+        p = simple_strtoul(addr, NULL, 0);
+        ((char *)&address)[0]  = p;
+
+	colon = strchr(eth, ':');
+	if (colon)
+		*colon = 0;
+
+        address = htonl(address);
+
+	rtnl_lock();
+
+	err = -ENODEV;
+	dev = __dev_get_by_name(eth);
+	if (!dev)
+		goto out;
+
+	if (colon)
+		*colon = ':';
+
+	err = -EADDRNOTAVAIL;
+	in_dev = __in_dev_get_rtnl(dev);
+	if (!in_dev)
+		goto out;
+
+	for (ifap = &in_dev->ifa_list; (ifa = *ifap) != NULL;
+	     ifap = &ifa->ifa_next)
+		if (!strcmp(eth, ifa->ifa_label) &&
+		    address == ifa->ifa_local)
+			break;
+	if (!ifa)
+		goto out;
+
+	ifa->ifa_net_ns = net_ns;
+
+	err = count;
+out:
+	rtnl_unlock();
+	return err;
+}
+
+
+static struct file_operations net_ns_dev_fops = {
+       .read =         net_ns_dev_read_file,
+       .write =        net_ns_dev_write_file,
+       .open =         net_ns_dev_open_file,
+};
+
+static struct file_operations net_ns_start_fops = {
+       .read =         net_ns_start_read_file,
+       .write =        net_ns_start_write_file,
+       .open =         net_ns_start_open_file,
+};
+
+static struct file_operations net_ns_info_fops = {
+       .read =         net_ns_info_read_file,
+       .write =        net_ns_info_write_file,
+       .open =         net_ns_info_open_file,
+};
+
+static int __init net_ns_init(void)
+{
+	net_ns_dentry = debugfs_create_dir("net_ns", NULL);
+
+	net_ns_dentry_dev = debugfs_create_file("dev", 0444,
+						net_ns_dentry,
+						NULL,
+						&net_ns_dev_fops);
+
+	net_ns_dentry_start = debugfs_create_file("start", 0666,
+						  net_ns_dentry,
+						  NULL,
+						  &net_ns_start_fops);
+
+	net_ns_dentry_info = debugfs_create_file("info", 0444,
+						 net_ns_dentry,
+						 NULL,
+						 &net_ns_info_fops);
+
+	return 0;
+}
+
+static void __exit net_ns_exit(void)
+{
+	debugfs_remove(net_ns_dentry_info);
+	debugfs_remove(net_ns_dentry_start);
+	debugfs_remove(net_ns_dentry_dev);
+	debugfs_remove(net_ns_dentry);
+}
+
+module_init(net_ns_init);
+module_exit(net_ns_exit);
+
+MODULE_DESCRIPTION("NET namespace debugfs");
+MODULE_AUTHOR("Daniel Lezcano <dlezcano@fr.ibm.com>");
+MODULE_LICENSE("GPL");
Index: 2.6.20-rc4-mm1/net/Kconfig
===================================================================
--- 2.6.20-rc4-mm1.orig/net/Kconfig
+++ 2.6.20-rc4-mm1/net/Kconfig
@@ -60,6 +60,10 @@
 
 	  Short answer: say Y.
 
+config NET_NS_DEBUG
+	bool "Debug fs for network namespace"
+	depends on DEBUG_FS && NET_NS
+
 if INET
 source "net/ipv4/Kconfig"
 source "net/ipv6/Kconfig"

-- 
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