Initial commit

package/kernel/trelay/src/Makefile

@@ -0,0 +1 @@
+obj-m   := trelay.o

package/kernel/trelay/src/trelay.c

@@ -0,0 +1,294 @@
+/*
+ * trelay.c: Trivial Ethernet Relay
+ *
+ * Copyright (C) 2012 Felix Fietkau <nbd@nbd.name>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <linux/debugfs.h>
+
+#define trelay_log(loglevel, tr, fmt, ...) \
+	printk(loglevel "trelay: %s <-> %s: " fmt "\n", \
+		tr->dev1->name, tr->dev2->name, ##__VA_ARGS__);
+
+static LIST_HEAD(trelay_devs);
+static struct dentry *debugfs_dir;
+
+struct trelay {
+	struct list_head list;
+	struct net_device *dev1, *dev2;
+	struct dentry *debugfs;
+	int to_remove;
+	char name[];
+};
+
+rx_handler_result_t trelay_handle_frame(struct sk_buff **pskb)
+{
+	struct net_device *dev;
+	struct sk_buff *skb = *pskb;
+
+	dev = rcu_dereference(skb->dev->rx_handler_data);
+	if (!dev)
+		return RX_HANDLER_PASS;
+
+	if (skb->protocol == htons(ETH_P_PAE))
+		return RX_HANDLER_PASS;
+
+	skb_push(skb, ETH_HLEN);
+	skb->dev = dev;
+	skb_forward_csum(skb);
+	dev_queue_xmit(skb);
+
+	return RX_HANDLER_CONSUMED;
+}
+
+static int trelay_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	return 0;
+}
+
+static int trelay_do_remove(struct trelay *tr)
+{
+	list_del(&tr->list);
+
+	/* First and before all, ensure that the debugfs file is removed
+	 * to prevent dangling pointer in file->private_data */
+	debugfs_remove_recursive(tr->debugfs);
+
+	dev_put(tr->dev1);
+	dev_put(tr->dev2);
+
+	netdev_rx_handler_unregister(tr->dev1);
+	netdev_rx_handler_unregister(tr->dev2);
+
+	trelay_log(KERN_INFO, tr, "stopped");
+
+	kfree(tr);
+
+	return 0;
+}
+
+static struct trelay *trelay_find(struct net_device *dev)
+{
+	struct trelay *tr;
+
+	list_for_each_entry(tr, &trelay_devs, list) {
+		if (tr->dev1 == dev || tr->dev2 == dev)
+			return tr;
+	}
+	return NULL;
+}
+
+static int tr_device_event(struct notifier_block *unused, unsigned long event,
+			   void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct trelay *tr;
+
+	if (event != NETDEV_UNREGISTER)
+		goto out;
+
+	tr = trelay_find(dev);
+	if (!tr)
+		goto out;
+
+	trelay_do_remove(tr);
+
+out:
+	return NOTIFY_DONE;
+}
+
+static ssize_t trelay_remove_write(struct file *file, const char __user *ubuf,
+				   size_t count, loff_t *ppos)
+{
+	struct trelay *tr = file->private_data;
+	tr->to_remove = 1;
+
+	return count;
+}
+
+static int trelay_remove_release(struct inode *inode, struct file *file)
+{
+	struct trelay *tr, *tmp;
+
+	/* This is the only file op that is called outside debugfs_use_file_*()
+	 * context which means that: (1) this file can be removed and
+	 * (2) file->private_data may no longer be valid */
+	rtnl_lock();
+	list_for_each_entry_safe(tr, tmp, &trelay_devs, list)
+		if (tr->to_remove)
+			trelay_do_remove(tr);
+	rtnl_unlock();
+
+	return 0;
+}
+
+static const struct file_operations fops_remove = {
+	.owner = THIS_MODULE,
+	.open = trelay_open,
+	.write = trelay_remove_write,
+	.llseek = default_llseek,
+	.release = trelay_remove_release,
+};
+
+
+static int trelay_do_add(char *name, char *devn1, char *devn2)
+{
+	struct net_device *dev1, *dev2;
+	struct trelay *tr, *tr1;
+	int ret;
+
+	tr = kzalloc(sizeof(*tr) + strlen(name) + 1, GFP_KERNEL);
+	if (!tr)
+		return -ENOMEM;
+
+	rtnl_lock();
+	rcu_read_lock();
+
+	ret = -EEXIST;
+	list_for_each_entry(tr1, &trelay_devs, list) {
+		if (!strcmp(tr1->name, name))
+			goto out;
+	}
+
+	ret = -ENOENT;
+	dev1 = dev_get_by_name_rcu(&init_net, devn1);
+	dev2 = dev_get_by_name_rcu(&init_net, devn2);
+	if (!dev1 || !dev2)
+		goto out;
+
+	ret = netdev_rx_handler_register(dev1, trelay_handle_frame, dev2);
+	if (ret < 0)
+		goto out;
+
+	ret = netdev_rx_handler_register(dev2, trelay_handle_frame, dev1);
+	if (ret < 0) {
+		netdev_rx_handler_unregister(dev1);
+		goto out;
+	}
+
+	dev_hold(dev1);
+	dev_hold(dev2);
+
+	strcpy(tr->name, name);
+	tr->dev1 = dev1;
+	tr->dev2 = dev2;
+	list_add_tail(&tr->list, &trelay_devs);
+
+	trelay_log(KERN_INFO, tr, "started");
+
+	tr->debugfs = debugfs_create_dir(name, debugfs_dir);
+	debugfs_create_file("remove", S_IWUSR, tr->debugfs, tr, &fops_remove);
+	ret = 0;
+
+out:
+	rcu_read_unlock();
+	rtnl_unlock();
+	if (ret < 0)
+		kfree(tr);
+
+	return ret;
+}
+
+static ssize_t trelay_add_write(struct file *file, const char __user *ubuf,
+				size_t count, loff_t *ppos)
+{
+	char buf[256];
+	char *dev1, *dev2, *tmp;
+	ssize_t len, ret;
+
+	len = min(count, sizeof(buf) - 1);
+	if (copy_from_user(buf, ubuf, len))
+		return -EFAULT;
+
+	buf[len] = 0;
+
+	if ((tmp = strchr(buf, '\n')))
+		*tmp = 0;
+
+	dev1 = strchr(buf, ',');
+	if (!dev1)
+		return -EINVAL;
+
+	*(dev1++) = 0;
+
+	dev2 = strchr(dev1, ',');
+	if (!dev2)
+		return -EINVAL;
+
+	*(dev2++) = 0;
+	if (strchr(dev2, ','))
+		return -EINVAL;
+
+	if (!strlen(buf) || !strlen(dev1) || !strlen(dev2))
+		return -EINVAL;
+
+	ret = trelay_do_add(buf, dev1, dev2);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static const struct file_operations fops_add = {
+	.owner = THIS_MODULE,
+	.write = trelay_add_write,
+	.llseek = default_llseek,
+};
+
+static struct notifier_block tr_dev_notifier = {
+	.notifier_call = tr_device_event
+};
+
+static int __init trelay_init(void)
+{
+	int ret;
+
+	debugfs_dir = debugfs_create_dir("trelay", NULL);
+	if (!debugfs_dir)
+		return -ENOMEM;
+
+	debugfs_create_file("add", S_IWUSR, debugfs_dir, NULL, &fops_add);
+
+	ret = register_netdevice_notifier(&tr_dev_notifier);
+	if (ret < 0)
+		goto error;
+
+	return 0;
+
+error:
+	debugfs_remove_recursive(debugfs_dir);
+	return ret;
+}
+
+static void __exit trelay_exit(void)
+{
+	struct trelay *tr, *tmp;
+
+	unregister_netdevice_notifier(&tr_dev_notifier);
+
+	rtnl_lock();
+	list_for_each_entry_safe(tr, tmp, &trelay_devs, list)
+		trelay_do_remove(tr);
+	rtnl_unlock();
+
+	debugfs_remove_recursive(debugfs_dir);
+}
+
+module_init(trelay_init);
+module_exit(trelay_exit);
+MODULE_LICENSE("GPL");