net/ipv6/tunnel6.c

   1 /*
   2  * Copyright (C)2003,2004 USAGI/WIDE Project
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  *
  17  * Authors      Mitsuru KANDA  <mk@linux-ipv6.org>
  18  *              YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
  19  */
  20
  21 #define pr_fmt(fmt) "IPv6: " fmt
  22
  23 #include <linux/icmpv6.h>
  24 #include <linux/init.h>
  25 #include <linux/module.h>
  26 #include <linux/mutex.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/slab.h>
  30 #include <net/ipv6.h>
  31 #include <net/protocol.h>
  32 #include <net/xfrm.h>
  33
  34 static struct xfrm6_tunnel __rcu *tunnel6_handlers __read_mostly;
  35 static struct xfrm6_tunnel __rcu *tunnel46_handlers __read_mostly;
  36 static DEFINE_MUTEX(tunnel6_mutex);
  37
  38 int xfrm6_tunnel_register(struct xfrm6_tunnel *handler, unsigned short family)
  39 {
  40         struct xfrm6_tunnel __rcu **pprev;
  41         struct xfrm6_tunnel *t;
  42         int ret = -EEXIST;
  43         int priority = handler->priority;
  44
  45         mutex_lock(&tunnel6_mutex);
  46
  47         for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
  48              (t = rcu_dereference_protected(*pprev,
  49                         lockdep_is_held(&tunnel6_mutex))) != NULL;
  50              pprev = &t->next) {
  51                 if (t->priority > priority)
  52                         break;
  53                 if (t->priority == priority)
  54                         goto err;
  55         }
  56
  57         handler->next = *pprev;
  58         rcu_assign_pointer(*pprev, handler);
  59
  60         ret = 0;
  61
  62 err:
  63         mutex_unlock(&tunnel6_mutex);
  64
  65         return ret;
  66 }
  67
  68 EXPORT_SYMBOL(xfrm6_tunnel_register);
  69
  70 int xfrm6_tunnel_deregister(struct xfrm6_tunnel *handler, unsigned short family)
  71 {
  72         struct xfrm6_tunnel __rcu **pprev;
  73         struct xfrm6_tunnel *t;
  74         int ret = -ENOENT;
  75
  76         mutex_lock(&tunnel6_mutex);
  77
  78         for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
  79              (t = rcu_dereference_protected(*pprev,
  80                         lockdep_is_held(&tunnel6_mutex))) != NULL;
  81              pprev = &t->next) {
  82                 if (t == handler) {
  83                         *pprev = handler->next;
  84                         ret = 0;
  85                         break;
  86                 }
  87         }
  88
  89         mutex_unlock(&tunnel6_mutex);
  90
  91         synchronize_net();
  92
  93         return ret;
  94 }
  95
  96 EXPORT_SYMBOL(xfrm6_tunnel_deregister);
  97
  98 #define for_each_tunnel_rcu(head, handler)              \
  99         for (handler = rcu_dereference(head);           \
 100              handler != NULL;                           \
 101              handler = rcu_dereference(handler->next))  \
 102
 103 static int tunnel6_rcv(struct sk_buff *skb)
 104 {
 105         struct xfrm6_tunnel *handler;
 106
 107         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 108                 goto drop;
 109
 110         for_each_tunnel_rcu(tunnel6_handlers, handler)
 111                 if (!handler->handler(skb))
 112                         return 0;
 113
 114         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 115
 116 drop:
 117         kfree_skb(skb);
 118         return 0;
 119 }
 120
 121 static int tunnel46_rcv(struct sk_buff *skb)
 122 {
 123         struct xfrm6_tunnel *handler;
 124
 125         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 126                 goto drop;
 127
 128         for_each_tunnel_rcu(tunnel46_handlers, handler)
 129                 if (!handler->handler(skb))
 130                         return 0;
 131
 132         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 133
 134 drop:
 135         kfree_skb(skb);
 136         return 0;
 137 }
 138
 139 static void tunnel6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 140                         u8 type, u8 code, int offset, __be32 info)
 141 {
 142         struct xfrm6_tunnel *handler;
 143
 144         for_each_tunnel_rcu(tunnel6_handlers, handler)
 145                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 146                         break;
 147 }
 148
 149 static const struct inet6_protocol tunnel6_protocol = {
 150         .handler        = tunnel6_rcv,
 151         .err_handler    = tunnel6_err,
 152         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 153 };
 154
 155 static const struct inet6_protocol tunnel46_protocol = {
 156         .handler        = tunnel46_rcv,
 157         .err_handler    = tunnel6_err,
 158         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 159 };
 160
 161 static int __init tunnel6_init(void)
 162 {
 163         if (inet6_add_protocol(&tunnel6_protocol, IPPROTO_IPV6)) {
 164                 pr_err("%s: can't add protocol\n", __func__);
 165                 return -EAGAIN;
 166         }
 167         if (inet6_add_protocol(&tunnel46_protocol, IPPROTO_IPIP)) {
 168                 pr_err("%s: can't add protocol\n", __func__);
 169                 inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6);
 170                 return -EAGAIN;
 171         }
 172         return 0;
 173 }
 174
 175 static void __exit tunnel6_fini(void)
 176 {
 177         if (inet6_del_protocol(&tunnel46_protocol, IPPROTO_IPIP))
 178                 pr_err("%s: can't remove protocol\n", __func__);
 179         if (inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6))
 180                 pr_err("%s: can't remove protocol\n", __func__);
 181 }
 182
 183 module_init(tunnel6_init);
 184 module_exit(tunnel6_fini);
 185 MODULE_LICENSE("GPL");