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