package/trelay/src/trelay.c

   1 /*
   2  * trelay.c: Trivial Ethernet Relay
   3  *
   4  * Copyright (C) 2012 Felix Fietkau <nbd@openwrt.org>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version 2
   9  * of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16 #include <linux/module.h>
  17 #include <linux/list.h>
  18 #include <linux/mutex.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/rtnetlink.h>
  21 #include <linux/debugfs.h>
  22
  23 static LIST_HEAD(trelay_devs);
  24 static struct dentry *debugfs_dir;
  25
  26 struct trelay {
  27         struct list_head list;
  28         struct net_device *dev1, *dev2;
  29         struct dentry *debugfs;
  30         char name[];
  31 };
  32
  33 rx_handler_result_t trelay_handle_frame(struct sk_buff **pskb)
  34 {
  35         struct net_device *dev;
  36         struct sk_buff *skb = *pskb;
  37
  38         dev = rcu_dereference(skb->dev->rx_handler_data);
  39         if (!dev)
  40                 return RX_HANDLER_PASS;
  41
  42         if (skb->protocol == htons(ETH_P_PAE))
  43                 return RX_HANDLER_PASS;
  44
  45         skb_push(skb, ETH_HLEN);
  46         skb->dev = dev;
  47         skb_forward_csum(skb);
  48         dev_queue_xmit(skb);
  49
  50         return RX_HANDLER_CONSUMED;
  51 }
  52
  53 static int trelay_open(struct inode *inode, struct file *file)
  54 {
  55         file->private_data = inode->i_private;
  56         return 0;
  57 }
  58
  59 static int trelay_do_remove(struct trelay *tr)
  60 {
  61         list_del(&tr->list);
  62
  63         dev_put(tr->dev1);
  64         dev_put(tr->dev2);
  65
  66         netdev_rx_handler_unregister(tr->dev1);
  67         netdev_rx_handler_unregister(tr->dev2);
  68
  69         debugfs_remove_recursive(tr->debugfs);
  70         kfree(tr);
  71
  72         return 0;
  73 }
  74
  75 static struct trelay *trelay_find(struct net_device *dev)
  76 {
  77         struct trelay *tr;
  78
  79         list_for_each_entry(tr, &trelay_devs, list) {
  80                 if (tr->dev1 == dev || tr->dev2 == dev)
  81                         return tr;
  82         }
  83         return NULL;
  84 }
  85
  86 static int tr_device_event(struct notifier_block *unused, unsigned long event,
  87                            void *ptr)
  88 {
  89         struct net_device *dev = ptr;
  90         struct trelay *tr;
  91
  92         if (event != NETDEV_UNREGISTER)
  93                 goto out;
  94
  95         tr = trelay_find(dev);
  96         if (!tr)
  97                 goto out;
  98
  99         trelay_do_remove(tr);
 100
 101 out:
 102         return NOTIFY_DONE;
 103 }
 104
 105 static ssize_t trelay_remove_write(struct file *file, const char __user *ubuf,
 106                                    size_t count, loff_t *ppos)
 107 {
 108         struct trelay *tr = file->private_data;
 109         int ret;
 110
 111         rtnl_lock();
 112         ret = trelay_do_remove(tr);
 113         rtnl_unlock();
 114
 115         if (ret < 0)
 116                  return ret;
 117
 118         return count;
 119 }
 120
 121 static const struct file_operations fops_remove = {
 122         .owner = THIS_MODULE,
 123         .open = trelay_open,
 124         .write = trelay_remove_write,
 125         .llseek = default_llseek,
 126 };
 127
 128
 129 static int trelay_do_add(char *name, char *devn1, char *devn2)
 130 {
 131         struct net_device *dev1, *dev2;
 132         struct trelay *tr, *tr1;
 133         int ret;
 134
 135         tr = kzalloc(sizeof(*tr) + strlen(name) + 1, GFP_KERNEL);
 136         if (!tr)
 137                 return -ENOMEM;
 138
 139         rtnl_lock();
 140         rcu_read_lock();
 141
 142         ret = -EEXIST;
 143         list_for_each_entry(tr1, &trelay_devs, list) {
 144                 if (!strcmp(tr1->name, name))
 145                         goto out;
 146         }
 147
 148         ret = -ENOENT;
 149         dev1 = dev_get_by_name_rcu(&init_net, devn1);
 150         dev2 = dev_get_by_name_rcu(&init_net, devn2);
 151         if (!dev1 || !dev2)
 152                 goto out;
 153
 154         ret = netdev_rx_handler_register(dev1, trelay_handle_frame, dev2);
 155         if (ret < 0)
 156                 goto out;
 157
 158         ret = netdev_rx_handler_register(dev2, trelay_handle_frame, dev1);
 159         if (ret < 0) {
 160                 netdev_rx_handler_unregister(dev1);
 161                 goto out;
 162         }
 163
 164         dev_hold(dev1);
 165         dev_hold(dev2);
 166
 167         strcpy(tr->name, name);
 168         tr->dev1 = dev1;
 169         tr->dev2 = dev2;
 170         list_add_tail(&tr->list, &trelay_devs);
 171
 172         tr->debugfs = debugfs_create_dir(name, debugfs_dir);
 173         debugfs_create_file("remove", S_IWUSR, tr->debugfs, tr, &fops_remove);
 174         ret = 0;
 175
 176 out:
 177         rcu_read_unlock();
 178         rtnl_unlock();
 179         if (ret < 0)
 180                 kfree(tr);
 181
 182         return ret;
 183 }
 184
 185 static ssize_t trelay_add_write(struct file *file, const char __user *ubuf,
 186                                 size_t count, loff_t *ppos)
 187 {
 188         char buf[256];
 189         char *dev1, *dev2, *tmp;
 190         ssize_t len, ret;
 191
 192         len = min(count, sizeof(buf) - 1);
 193         if (copy_from_user(buf, ubuf, len))
 194                 return -EFAULT;
 195
 196         buf[len] = 0;
 197
 198         if ((tmp = strchr(buf, '\n')))
 199                 *tmp = 0;
 200
 201         dev1 = strchr(buf, ',');
 202         if (!dev1)
 203                 return -EINVAL;
 204
 205         *(dev1++) = 0;
 206
 207         dev2 = strchr(dev1, ',');
 208         if (!dev2)
 209                 return -EINVAL;
 210
 211         *(dev2++) = 0;
 212         if (strchr(dev2, ','))
 213                 return -EINVAL;
 214
 215         if (!strlen(buf) || !strlen(dev1) || !strlen(dev2))
 216                 return -EINVAL;
 217
 218         ret = trelay_do_add(buf, dev1, dev2);
 219         if (ret < 0)
 220                 return ret;
 221
 222         return count;
 223 }
 224
 225 static const struct file_operations fops_add = {
 226         .owner = THIS_MODULE,
 227         .write = trelay_add_write,
 228         .llseek = default_llseek,
 229 };
 230
 231 static struct notifier_block tr_dev_notifier = {
 232         .notifier_call = tr_device_event
 233 };
 234
 235 static int __init trelay_init(void)
 236 {
 237         int ret;
 238
 239         debugfs_dir = debugfs_create_dir("trelay", NULL);
 240         if (!debugfs_dir)
 241                 return -ENOMEM;
 242
 243         debugfs_create_file("add", S_IWUSR, debugfs_dir, NULL, &fops_add);
 244
 245         ret = register_netdevice_notifier(&tr_dev_notifier);
 246         if (ret < 0)
 247                 goto error;
 248
 249         return 0;
 250
 251 error:
 252         debugfs_remove_recursive(debugfs_dir);
 253         return ret;
 254 }
 255
 256 static void __exit trelay_exit(void)
 257 {
 258         struct trelay *tr, *tmp;
 259
 260         unregister_netdevice_notifier(&tr_dev_notifier);
 261
 262         rtnl_lock();
 263         list_for_each_entry_safe(tr, tmp, &trelay_devs, list)
 264                 trelay_do_remove(tr);
 265         rtnl_unlock();
 266
 267         debugfs_remove_recursive(debugfs_dir);
 268 }
 269
 270 module_init(trelay_init);
 271 module_exit(trelay_exit);
 272 MODULE_LICENSE("GPL");