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/mpls.h>
  10 #include <linux/netdevice.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/slab.h>
  13 #include <net/icmp.h>
  14 #include <net/ip.h>
  15 #include <net/protocol.h>
  16 #include <net/xfrm.h>
  17
  18 static struct xfrm_tunnel __rcu *tunnel4_handlers __read_mostly;
  19 static struct xfrm_tunnel __rcu *tunnel64_handlers __read_mostly;
  20 static struct xfrm_tunnel __rcu *tunnelmpls4_handlers __read_mostly;
  21 static DEFINE_MUTEX(tunnel4_mutex);
  22
  23 static inline struct xfrm_tunnel __rcu **fam_handlers(unsigned short family)
  24 {
  25         return (family == AF_INET) ? &tunnel4_handlers :
  26                 (family == AF_INET6) ? &tunnel64_handlers :
  27                 &tunnelmpls4_handlers;
  28 }
  29
  30 int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short family)
  31 {
  32         struct xfrm_tunnel __rcu **pprev;
  33         struct xfrm_tunnel *t;
  34
  35         int ret = -EEXIST;
  36         int priority = handler->priority;
  37
  38         mutex_lock(&tunnel4_mutex);
  39
  40         for (pprev = fam_handlers(family);
  41              (t = rcu_dereference_protected(*pprev,
  42                         lockdep_is_held(&tunnel4_mutex))) != NULL;
  43              pprev = &t->next) {
  44                 if (t->priority > priority)
  45                         break;
  46                 if (t->priority == priority)
  47                         goto err;
  48         }
  49
  50         handler->next = *pprev;
  51         rcu_assign_pointer(*pprev, handler);
  52
  53         ret = 0;
  54
  55 err:
  56         mutex_unlock(&tunnel4_mutex);
  57
  58         return ret;
  59 }
  60 EXPORT_SYMBOL(xfrm4_tunnel_register);
  61
  62 int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler, unsigned short family)
  63 {
  64         struct xfrm_tunnel __rcu **pprev;
  65         struct xfrm_tunnel *t;
  66         int ret = -ENOENT;
  67
  68         mutex_lock(&tunnel4_mutex);
  69
  70         for (pprev = fam_handlers(family);
  71              (t = rcu_dereference_protected(*pprev,
  72                         lockdep_is_held(&tunnel4_mutex))) != NULL;
  73              pprev = &t->next) {
  74                 if (t == handler) {
  75                         *pprev = handler->next;
  76                         ret = 0;
  77                         break;
  78                 }
  79         }
  80
  81         mutex_unlock(&tunnel4_mutex);
  82
  83         synchronize_net();
  84
  85         return ret;
  86 }
  87 EXPORT_SYMBOL(xfrm4_tunnel_deregister);
  88
  89 #define for_each_tunnel_rcu(head, handler)              \
  90         for (handler = rcu_dereference(head);           \
  91              handler != NULL;                           \
  92              handler = rcu_dereference(handler->next))  \
  93
  94 static int tunnel4_rcv(struct sk_buff *skb)
  95 {
  96         struct xfrm_tunnel *handler;
  97
  98         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  99                 goto drop;
 100
 101         for_each_tunnel_rcu(tunnel4_handlers, handler)
 102                 if (!handler->handler(skb))
 103                         return 0;
 104
 105         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 106
 107 drop:
 108         kfree_skb(skb);
 109         return 0;
 110 }
 111
 112 #if IS_ENABLED(CONFIG_IPV6)
 113 static int tunnel64_rcv(struct sk_buff *skb)
 114 {
 115         struct xfrm_tunnel *handler;
 116
 117         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 118                 goto drop;
 119
 120         for_each_tunnel_rcu(tunnel64_handlers, handler)
 121                 if (!handler->handler(skb))
 122                         return 0;
 123
 124         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 125
 126 drop:
 127         kfree_skb(skb);
 128         return 0;
 129 }
 130 #endif
 131
 132 #if IS_ENABLED(CONFIG_MPLS)
 133 static int tunnelmpls4_rcv(struct sk_buff *skb)
 134 {
 135         struct xfrm_tunnel *handler;
 136
 137         if (!pskb_may_pull(skb, sizeof(struct mpls_label)))
 138                 goto drop;
 139
 140         for_each_tunnel_rcu(tunnelmpls4_handlers, handler)
 141                 if (!handler->handler(skb))
 142                         return 0;
 143
 144         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 145
 146 drop:
 147         kfree_skb(skb);
 148         return 0;
 149 }
 150 #endif
 151
 152 static void tunnel4_err(struct sk_buff *skb, u32 info)
 153 {
 154         struct xfrm_tunnel *handler;
 155
 156         for_each_tunnel_rcu(tunnel4_handlers, handler)
 157                 if (!handler->err_handler(skb, info))
 158                         break;
 159 }
 160
 161 #if IS_ENABLED(CONFIG_IPV6)
 162 static void tunnel64_err(struct sk_buff *skb, u32 info)
 163 {
 164         struct xfrm_tunnel *handler;
 165
 166         for_each_tunnel_rcu(tunnel64_handlers, handler)
 167                 if (!handler->err_handler(skb, info))
 168                         break;
 169 }
 170 #endif
 171
 172 #if IS_ENABLED(CONFIG_MPLS)
 173 static void tunnelmpls4_err(struct sk_buff *skb, u32 info)
 174 {
 175         struct xfrm_tunnel *handler;
 176
 177         for_each_tunnel_rcu(tunnelmpls4_handlers, handler)
 178                 if (!handler->err_handler(skb, info))
 179                         break;
 180 }
 181 #endif
 182
 183 static const struct net_protocol tunnel4_protocol = {
 184         .handler        =       tunnel4_rcv,
 185         .err_handler    =       tunnel4_err,
 186         .no_policy      =       1,
 187         .netns_ok       =       1,
 188 };
 189
 190 #if IS_ENABLED(CONFIG_IPV6)
 191 static const struct net_protocol tunnel64_protocol = {
 192         .handler        =       tunnel64_rcv,
 193         .err_handler    =       tunnel64_err,
 194         .no_policy      =       1,
 195         .netns_ok       =       1,
 196 };
 197 #endif
 198
 199 #if IS_ENABLED(CONFIG_MPLS)
 200 static const struct net_protocol tunnelmpls4_protocol = {
 201         .handler        =       tunnelmpls4_rcv,
 202         .err_handler    =       tunnelmpls4_err,
 203         .no_policy      =       1,
 204         .netns_ok       =       1,
 205 };
 206 #endif
 207
 208 static int __init tunnel4_init(void)
 209 {
 210         if (inet_add_protocol(&tunnel4_protocol, IPPROTO_IPIP))
 211                 goto err;
 212 #if IS_ENABLED(CONFIG_IPV6)
 213         if (inet_add_protocol(&tunnel64_protocol, IPPROTO_IPV6)) {
 214                 inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP);
 215                 goto err;
 216         }
 217 #endif
 218 #if IS_ENABLED(CONFIG_MPLS)
 219         if (inet_add_protocol(&tunnelmpls4_protocol, IPPROTO_MPLS)) {
 220                 inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP);
 221 #if IS_ENABLED(CONFIG_IPV6)
 222                 inet_del_protocol(&tunnel64_protocol, IPPROTO_IPV6);
 223 #endif
 224                 goto err;
 225         }
 226 #endif
 227         return 0;
 228
 229 err:
 230         pr_err("%s: can't add protocol\n", __func__);
 231         return -EAGAIN;
 232 }
 233
 234 static void __exit tunnel4_fini(void)
 235 {
 236 #if IS_ENABLED(CONFIG_MPLS)
 237         if (inet_del_protocol(&tunnelmpls4_protocol, IPPROTO_MPLS))
 238                 pr_err("tunnelmpls4 close: can't remove protocol\n");
 239 #endif
 240 #if IS_ENABLED(CONFIG_IPV6)
 241         if (inet_del_protocol(&tunnel64_protocol, IPPROTO_IPV6))
 242                 pr_err("tunnel64 close: can't remove protocol\n");
 243 #endif
 244         if (inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP))
 245                 pr_err("tunnel4 close: can't remove protocol\n");
 246 }
 247
 248 module_init(tunnel4_init);
 249 module_exit(tunnel4_fini);
 250 MODULE_LICENSE("GPL");