net/ipv4/tunnel4.c

   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/icmp.h>
  12 #include <net/ip.h>
  13 #include <net/protocol.h>
  14 #include <net/xfrm.h>
  15
  16 static struct xfrm_tunnel *tunnel4_handlers;
  17 static DEFINE_MUTEX(tunnel4_mutex);
  18
  19 int xfrm4_tunnel_register(struct xfrm_tunnel *handler)
  20 {
  21         struct xfrm_tunnel **pprev;
  22         int ret = -EEXIST;
  23         int priority = handler->priority;
  24
  25         mutex_lock(&tunnel4_mutex);
  26
  27         for (pprev = &tunnel4_handlers; *pprev; pprev = &(*pprev)->next) {
  28                 if ((*pprev)->priority > priority)
  29                         break;
  30                 if ((*pprev)->priority == priority)
  31                         goto err;
  32         }
  33
  34         handler->next = *pprev;
  35         *pprev = handler;
  36
  37         ret = 0;
  38
  39 err:
  40         mutex_unlock(&tunnel4_mutex);
  41
  42         return ret;
  43 }
  44
  45 EXPORT_SYMBOL(xfrm4_tunnel_register);
  46
  47 int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler)
  48 {
  49         struct xfrm_tunnel **pprev;
  50         int ret = -ENOENT;
  51
  52         mutex_lock(&tunnel4_mutex);
  53
  54         for (pprev = &tunnel4_handlers; *pprev; pprev = &(*pprev)->next) {
  55                 if (*pprev == handler) {
  56                         *pprev = handler->next;
  57                         ret = 0;
  58                         break;
  59                 }
  60         }
  61
  62         mutex_unlock(&tunnel4_mutex);
  63
  64         synchronize_net();
  65
  66         return ret;
  67 }
  68
  69 EXPORT_SYMBOL(xfrm4_tunnel_deregister);
  70
  71 static int tunnel4_rcv(struct sk_buff *skb)
  72 {
  73         struct xfrm_tunnel *handler;
  74
  75         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  76                 goto drop;
  77
  78         for (handler = tunnel4_handlers; handler; handler = handler->next)
  79                 if (!handler->handler(skb))
  80                         return 0;
  81
  82         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
  83
  84 drop:
  85         kfree_skb(skb);
  86         return 0;
  87 }
  88
  89 static void tunnel4_err(struct sk_buff *skb, u32 info)
  90 {
  91         struct xfrm_tunnel *handler;
  92
  93         for (handler = tunnel4_handlers; handler; handler = handler->next)
  94                 if (!handler->err_handler(skb, info))
  95                         break;
  96 }
  97
  98 static struct net_protocol tunnel4_protocol = {
  99         .handler        =       tunnel4_rcv,
 100         .err_handler    =       tunnel4_err,
 101         .no_policy      =       1,
 102 };
 103
 104 static int __init tunnel4_init(void)
 105 {
 106         if (inet_add_protocol(&tunnel4_protocol, IPPROTO_IPIP)) {
 107                 printk(KERN_ERR "tunnel4 init: can't add protocol\n");
 108                 return -EAGAIN;
 109         }
 110         return 0;
 111 }
 112
 113 static void __exit tunnel4_fini(void)
 114 {
 115         if (inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP))
 116                 printk(KERN_ERR "tunnel4 close: can't remove protocol\n");
 117 }
 118
 119 module_init(tunnel4_init);
 120 module_exit(tunnel4_fini);
 121 MODULE_LICENSE("GPL");