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   1 /* tunnel4.c: Generic IP tunnel transformer.
   2  *
   3  * Copyright (C) 2003 David S. Miller (davem@redhat.com)
   4  */
   5
   6 #include <linux/init.h>
   7 #include <linux/module.h>
   8 #include <linux/mutex.h>
   9 #include <linux/netdevice.h>
  10 #include <linux/skbuff.h>
  11 #include <net/protocol.h>
  12 #include <net/xfrm.h>
  13
  14 static struct xfrm_tunnel *tunnel4_handlers;
  15 static DEFINE_MUTEX(tunnel4_mutex);
  16
  17 int xfrm4_tunnel_register(struct xfrm_tunnel *handler)
  18 {
  19         struct xfrm_tunnel **pprev;
  20         int ret = -EEXIST;
  21         int priority = handler->priority;
  22
  23         mutex_lock(&tunnel4_mutex);
  24
  25         for (pprev = &tunnel4_handlers; *pprev; pprev = &(*pprev)->next) {
  26                 if ((*pprev)->priority > priority)
  27                         break;
  28                 if ((*pprev)->priority == priority)
  29                         goto err;
  30         }
  31
  32         handler->next = *pprev;
  33         *pprev = handler;
  34
  35         ret = 0;
  36
  37 err:
  38         mutex_unlock(&tunnel4_mutex);
  39
  40         return ret;
  41 }
  42
  43 EXPORT_SYMBOL(xfrm4_tunnel_register);
  44
  45 int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler)
  46 {
  47         struct xfrm_tunnel **pprev;
  48         int ret = -ENOENT;
  49
  50         mutex_lock(&tunnel4_mutex);
  51
  52         for (pprev = &tunnel4_handlers; *pprev; pprev = &(*pprev)->next) {
  53                 if (*pprev == handler) {
  54                         *pprev = handler->next;
  55                         ret = 0;
  56                         break;
  57                 }
  58         }
  59
  60         mutex_unlock(&tunnel4_mutex);
  61
  62         synchronize_net();
  63
  64         return ret;
  65 }
  66
  67 EXPORT_SYMBOL(xfrm4_tunnel_deregister);
  68
  69 static int tunnel4_rcv(struct sk_buff *skb)
  70 {
  71         struct xfrm_tunnel *handler;
  72
  73         for (handler = tunnel4_handlers; handler; handler = handler->next)
  74                 if (!handler->handler(skb))
  75                         return 0;
  76
  77         kfree_skb(skb);
  78         return 0;
  79 }
  80
  81 static void tunnel4_err(struct sk_buff *skb, u32 info)
  82 {
  83         struct xfrm_tunnel *handler;
  84
  85         for (handler = tunnel4_handlers; handler; handler = handler->next)
  86                 if (!handler->err_handler(skb, info))
  87                         break;
  88 }
  89
  90 static struct net_protocol tunnel4_protocol = {
  91         .handler        =       tunnel4_rcv,
  92         .err_handler    =       tunnel4_err,
  93         .no_policy      =       1,
  94 };
  95
  96 static int __init tunnel4_init(void)
  97 {
  98         if (inet_add_protocol(&tunnel4_protocol, IPPROTO_IPIP)) {
  99                 printk(KERN_ERR "tunnel4 init: can't add protocol\n");
 100                 return -EAGAIN;
 101         }
 102         return 0;
 103 }
 104
 105 static void __exit tunnel4_fini(void)
 106 {
 107         if (inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP))
 108                 printk(KERN_ERR "tunnel4 close: can't remove protocol\n");
 109 }
 110
 111 module_init(tunnel4_init);
 112 module_exit(tunnel4_fini);
 113 MODULE_LICENSE("GPL");