kernel/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 EXPORT_SYMBOL(xfrm6_tunnel_register);
  68
  69 int xfrm6_tunnel_deregister(struct xfrm6_tunnel *handler, unsigned short family)
  70 {
  71         struct xfrm6_tunnel __rcu **pprev;
  72         struct xfrm6_tunnel *t;
  73         int ret = -ENOENT;
  74
  75         mutex_lock(&tunnel6_mutex);
  76
  77         for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
  78              (t = rcu_dereference_protected(*pprev,
  79                         lockdep_is_held(&tunnel6_mutex))) != NULL;
  80              pprev = &t->next) {
  81                 if (t == handler) {
  82                         *pprev = handler->next;
  83                         ret = 0;
  84                         break;
  85                 }
  86         }
  87
  88         mutex_unlock(&tunnel6_mutex);
  89
  90         synchronize_net();
  91
  92         return ret;
  93 }
  94 EXPORT_SYMBOL(xfrm6_tunnel_deregister);
  95
  96 #define for_each_tunnel_rcu(head, handler)              \
  97         for (handler = rcu_dereference(head);           \
  98              handler != NULL;                           \
  99              handler = rcu_dereference(handler->next))  \
 100
 101 static int tunnel6_rcv(struct sk_buff *skb)
 102 {
 103         struct xfrm6_tunnel *handler;
 104
 105         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 106                 goto drop;
 107
 108         for_each_tunnel_rcu(tunnel6_handlers, handler)
 109                 if (!handler->handler(skb))
 110                         return 0;
 111
 112         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 113
 114 drop:
 115         kfree_skb(skb);
 116         return 0;
 117 }
 118
 119 static int tunnel46_rcv(struct sk_buff *skb)
 120 {
 121         struct xfrm6_tunnel *handler;
 122
 123         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 124                 goto drop;
 125
 126         for_each_tunnel_rcu(tunnel46_handlers, handler)
 127                 if (!handler->handler(skb))
 128                         return 0;
 129
 130         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 131
 132 drop:
 133         kfree_skb(skb);
 134         return 0;
 135 }
 136
 137 static void tunnel6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 138                         u8 type, u8 code, int offset, __be32 info)
 139 {
 140         struct xfrm6_tunnel *handler;
 141
 142         for_each_tunnel_rcu(tunnel6_handlers, handler)
 143                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 144                         break;
 145 }
 146
 147 static const struct inet6_protocol tunnel6_protocol = {
 148         .handler        = tunnel6_rcv,
 149         .err_handler    = tunnel6_err,
 150         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 151 };
 152
 153 static const struct inet6_protocol tunnel46_protocol = {
 154         .handler        = tunnel46_rcv,
 155         .err_handler    = tunnel6_err,
 156         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 157 };
 158
 159 static int __init tunnel6_init(void)
 160 {
 161         if (inet6_add_protocol(&tunnel6_protocol, IPPROTO_IPV6)) {
 162                 pr_err("%s: can't add protocol\n", __func__);
 163                 return -EAGAIN;
 164         }
 165         if (inet6_add_protocol(&tunnel46_protocol, IPPROTO_IPIP)) {
 166                 pr_err("%s: can't add protocol\n", __func__);
 167                 inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6);
 168                 return -EAGAIN;
 169         }
 170         return 0;
 171 }
 172
 173 static void __exit tunnel6_fini(void)
 174 {
 175         if (inet6_del_protocol(&tunnel46_protocol, IPPROTO_IPIP))
 176                 pr_err("%s: can't remove protocol\n", __func__);
 177         if (inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6))
 178                 pr_err("%s: can't remove protocol\n", __func__);
 179 }
 180
 181 module_init(tunnel6_init);
 182 module_exit(tunnel6_fini);
 183 MODULE_LICENSE("GPL");