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Subject[RFC] [patch 6/6] [Network namespace] Network namespace debugfs
This patch is for testing purpose. It allows to read which network
devices are accessible and to add a network device to the view.
This RFC hack is purely for discussing the best way to do that.

After unsharing with CLONE_NEWNET flag:
--------------------------------------
To see which devices are accessible:
cat /sys/kernel/debug/net_ns/dev
To add a device:
echo eth1 > /sys/kernel/debug/net_ns/dev
This functionnality is intended to be implemented in an higher level
container configuration.

Replace-Subject: [Network namespace] Network namespace debugfs
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
--
fs/debugfs/Makefile | 2
fs/debugfs/net_ns.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++++
net/Kconfig | 4 +
3 files changed, 146 insertions(+), 1 deletion(-)
Index: 2.6-mm/fs/debugfs/Makefile
===================================================================
--- 2.6-mm.orig/fs/debugfs/Makefile
+++ 2.6-mm/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-mm/fs/debugfs/net_ns.c
===================================================================
--- /dev/null
+++ 2.6-mm/fs/debugfs/net_ns.c
@@ -0,0 +1,141 @@
+/*
+ * net_ns.c - adds a net_ns/ directory to debug NET namespaces
+ *
+ * Copyright (C) 2006 IBM
+ *
+ * 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/net_ns.h>
+
+static struct dentry *net_ns_dentry;
+static struct dentry *net_ns_dentry_dev;
+
+static ssize_t net_ns_dev_read_file(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ size_t len;
+ char *buf;
+ struct net_ns_dev_list *devlist = &(net_ns()->dev_list);
+ struct net_ns_dev *db;
+ struct net_device *dev;
+ struct list_head *l;
+
+ if (*ppos < 0)
+ return -EINVAL;
+ if (*ppos >= count)
+ return 0;
+
+ /* It's for debug, everything should fit */
+ buf = kmalloc(4096, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+ buf[0] = '\0';
+
+ read_lock(&devlist->lock);
+ list_for_each(l, &devlist->list) {
+ db = list_entry(l, struct net_ns_dev, list);
+ dev = db->dev;
+ strcat(buf,dev->name);
+ strcat(buf,"\n");
+ }
+ read_unlock(&devlist->lock);
+
+ len = strlen(buf);
+
+ if (len > count)
+ len = count;
+
+ if (copy_to_user(user_buf, buf, len)) {
+ kfree(buf);
+ return -EFAULT;
+ }
+
+ *ppos += count;
+ kfree(buf);
+
+ return count;
+}
+
+static ssize_t net_ns_dev_write_file(struct file *file,
+ const char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ int ret;
+ size_t len;
+ const char __user *p;
+ char c;
+ char devname[IFNAMSIZ];
+ struct net_ns_dev_list *dev_list = &(net_ns()->dev_list);
+
+ len = 0;
+ p = user_buf;
+ while (len < count) {
+ if (get_user(c, p++))
+ return -EFAULT;
+ if (c == 0 || c == '\n')
+ break;
+ len++;
+ }
+
+ if (len >= IFNAMSIZ)
+ return -EINVAL;
+
+ if (copy_from_user(devname, user_buf, len))
+ return -EFAULT;
+
+ devname[len] = '\0';
+
+ ret = net_ns_dev_add(devname, dev_list);
+ if (ret)
+ return ret;
+
+ *ppos += count;
+ return count;
+}
+
+static int net_ns_dev_open_file(struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+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 int __init net_ns_init(void)
+{
+ net_ns_dentry = debugfs_create_dir("net_ns", NULL);
+
+ net_ns_dentry_dev = debugfs_create_file("dev", 0666,
+ net_ns_dentry,
+ NULL,
+ &net_ns_dev_fops);
+ return 0;
+}
+
+static void __exit net_ns_exit(void)
+{
+ 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-mm/net/Kconfig
===================================================================
--- 2.6-mm.orig/net/Kconfig
+++ 2.6-mm/net/Kconfig
@@ -69,6 +69,10 @@ config NET_NS
vservers, to use network namespaces to provide isolated
network for different servers. If unsure, say N.

+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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