net/ipv4/tunnel4.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* tunnel4.c: Generic IP tunnel transformer.
   3  *
   4  * Copyright (C) 2003 David S. Miller (davem@redhat.com)
   5  */
   6
   7 #include <linux/init.h>
   8 #include <linux/module.h>
   9 #include <linux/mutex.h>
  10 #include <linux/mpls.h>
  11 #include <linux/netdevice.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/slab.h>
  14 #include <net/icmp.h>
  15 #include <net/ip.h>
  16 #include <net/protocol.h>
  17 #include <net/xfrm.h>
  18
  19 static struct xfrm_tunnel __rcu *tunnel4_handlers __read_mostly;
  20 static struct xfrm_tunnel __rcu *tunnel64_handlers __read_mostly;
  21 static struct xfrm_tunnel __rcu *tunnelmpls4_handlers __read_mostly;
  22 static DEFINE_MUTEX(tunnel4_mutex);
  23
  24 static inline struct xfrm_tunnel __rcu **fam_handlers(unsigned short family)
  25 {
  26         return (family == AF_INET) ? &tunnel4_handlers :
  27                 (family == AF_INET6) ? &tunnel64_handlers :
  28                 &tunnelmpls4_handlers;
  29 }
  30
  31 int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short family)
  32 {
  33         struct xfrm_tunnel __rcu **pprev;
  34         struct xfrm_tunnel *t;
  35
  36         int ret = -EEXIST;
  37         int priority = handler->priority;
  38
  39         mutex_lock(&tunnel4_mutex);
  40
  41         for (pprev = fam_handlers(family);
  42              (t = rcu_dereference_protected(*pprev,
  43                         lockdep_is_held(&tunnel4_mutex))) != NULL;
  44              pprev = &t->next) {
  45                 if (t->priority > priority)
  46                         break;
  47                 if (t->priority == priority)
  48                         goto err;
  49         }
  50
  51         handler->next = *pprev;
  52         rcu_assign_pointer(*pprev, handler);
  53
  54         ret = 0;
  55
  56 err:
  57         mutex_unlock(&tunnel4_mutex);
  58
  59         return ret;
  60 }
  61 EXPORT_SYMBOL(xfrm4_tunnel_register);
  62
  63 int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler, unsigned short family)
  64 {
  65         struct xfrm_tunnel __rcu **pprev;
  66         struct xfrm_tunnel *t;
  67         int ret = -ENOENT;
  68
  69         mutex_lock(&tunnel4_mutex);
  70
  71         for (pprev = fam_handlers(family);
  72              (t = rcu_dereference_protected(*pprev,
  73                         lockdep_is_held(&tunnel4_mutex))) != NULL;
  74              pprev = &t->next) {
  75                 if (t == handler) {
  76                         *pprev = handler->next;
  77                         ret = 0;
  78                         break;
  79                 }
  80         }
  81
  82         mutex_unlock(&tunnel4_mutex);
  83
  84         synchronize_net();
  85
  86         return ret;
  87 }
  88 EXPORT_SYMBOL(xfrm4_tunnel_deregister);
  89
  90 #define for_each_tunnel_rcu(head, handler)              \
  91         for (handler = rcu_dereference(head);           \
  92              handler != NULL;                           \
  93              handler = rcu_dereference(handler->next))  \
  94
  95 static int tunnel4_rcv(struct sk_buff *skb)
  96 {
  97         struct xfrm_tunnel *handler;
  98
  99         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 100                 goto drop;
 101
 102         for_each_tunnel_rcu(tunnel4_handlers, handler)
 103                 if (!handler->handler(skb))
 104                         return 0;
 105
 106         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 107
 108 drop:
 109         kfree_skb(skb);
 110         return 0;
 111 }
 112
 113 #if IS_ENABLED(CONFIG_INET_XFRM_TUNNEL)
 114 static int tunnel4_rcv_cb(struct sk_buff *skb, u8 proto, int err)
 115 {
 116         struct xfrm_tunnel __rcu *head;
 117         struct xfrm_tunnel *handler;
 118         int ret;
 119
 120         head = (proto == IPPROTO_IPIP) ? tunnel4_handlers : tunnel64_handlers;
 121
 122         for_each_tunnel_rcu(head, handler) {
 123                 if (handler->cb_handler) {
 124                         ret = handler->cb_handler(skb, err);
 125                         if (ret <= 0)
 126                                 return ret;
 127                 }
 128         }
 129
 130         return 0;
 131 }
 132
 133 static const struct xfrm_input_afinfo tunnel4_input_afinfo = {
 134         .family         =       AF_INET,
 135         .is_ipip        =       true,
 136         .callback       =       tunnel4_rcv_cb,
 137 };
 138 #endif
 139
 140 #if IS_ENABLED(CONFIG_IPV6)
 141 static int tunnel64_rcv(struct sk_buff *skb)
 142 {
 143         struct xfrm_tunnel *handler;
 144
 145         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 146                 goto drop;
 147
 148         for_each_tunnel_rcu(tunnel64_handlers, handler)
 149                 if (!handler->handler(skb))
 150                         return 0;
 151
 152         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 153
 154 drop:
 155         kfree_skb(skb);
 156         return 0;
 157 }
 158 #endif
 159
 160 #if IS_ENABLED(CONFIG_MPLS)
 161 static int tunnelmpls4_rcv(struct sk_buff *skb)
 162 {
 163         struct xfrm_tunnel *handler;
 164
 165         if (!pskb_may_pull(skb, sizeof(struct mpls_label)))
 166                 goto drop;
 167
 168         for_each_tunnel_rcu(tunnelmpls4_handlers, handler)
 169                 if (!handler->handler(skb))
 170                         return 0;
 171
 172         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 173
 174 drop:
 175         kfree_skb(skb);
 176         return 0;
 177 }
 178 #endif
 179
 180 static int tunnel4_err(struct sk_buff *skb, u32 info)
 181 {
 182         struct xfrm_tunnel *handler;
 183
 184         for_each_tunnel_rcu(tunnel4_handlers, handler)
 185                 if (!handler->err_handler(skb, info))
 186                         return 0;
 187
 188         return -ENOENT;
 189 }
 190
 191 #if IS_ENABLED(CONFIG_IPV6)
 192 static int tunnel64_err(struct sk_buff *skb, u32 info)
 193 {
 194         struct xfrm_tunnel *handler;
 195
 196         for_each_tunnel_rcu(tunnel64_handlers, handler)
 197                 if (!handler->err_handler(skb, info))
 198                         return 0;
 199
 200         return -ENOENT;
 201 }
 202 #endif
 203
 204 #if IS_ENABLED(CONFIG_MPLS)
 205 static int tunnelmpls4_err(struct sk_buff *skb, u32 info)
 206 {
 207         struct xfrm_tunnel *handler;
 208
 209         for_each_tunnel_rcu(tunnelmpls4_handlers, handler)
 210                 if (!handler->err_handler(skb, info))
 211                         return 0;
 212
 213         return -ENOENT;
 214 }
 215 #endif
 216
 217 static const struct net_protocol tunnel4_protocol = {
 218         .handler        =       tunnel4_rcv,
 219         .err_handler    =       tunnel4_err,
 220         .no_policy      =       1,
 221         .netns_ok       =       1,
 222 };
 223
 224 #if IS_ENABLED(CONFIG_IPV6)
 225 static const struct net_protocol tunnel64_protocol = {
 226         .handler        =       tunnel64_rcv,
 227         .err_handler    =       tunnel64_err,
 228         .no_policy      =       1,
 229         .netns_ok       =       1,
 230 };
 231 #endif
 232
 233 #if IS_ENABLED(CONFIG_MPLS)
 234 static const struct net_protocol tunnelmpls4_protocol = {
 235         .handler        =       tunnelmpls4_rcv,
 236         .err_handler    =       tunnelmpls4_err,
 237         .no_policy      =       1,
 238         .netns_ok       =       1,
 239 };
 240 #endif
 241
 242 static int __init tunnel4_init(void)
 243 {
 244         if (inet_add_protocol(&tunnel4_protocol, IPPROTO_IPIP))
 245                 goto err;
 246 #if IS_ENABLED(CONFIG_IPV6)
 247         if (inet_add_protocol(&tunnel64_protocol, IPPROTO_IPV6)) {
 248                 inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP);
 249                 goto err;
 250         }
 251 #endif
 252 #if IS_ENABLED(CONFIG_MPLS)
 253         if (inet_add_protocol(&tunnelmpls4_protocol, IPPROTO_MPLS)) {
 254                 inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP);
 255 #if IS_ENABLED(CONFIG_IPV6)
 256                 inet_del_protocol(&tunnel64_protocol, IPPROTO_IPV6);
 257 #endif
 258                 goto err;
 259         }
 260 #endif
 261 #if IS_ENABLED(CONFIG_INET_XFRM_TUNNEL)
 262         if (xfrm_input_register_afinfo(&tunnel4_input_afinfo)) {
 263                 inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP);
 264 #if IS_ENABLED(CONFIG_IPV6)
 265                 inet_del_protocol(&tunnel64_protocol, IPPROTO_IPV6);
 266 #endif
 267 #if IS_ENABLED(CONFIG_MPLS)
 268                 inet_del_protocol(&tunnelmpls4_protocol, IPPROTO_MPLS);
 269 #endif
 270                 goto err;
 271         }
 272 #endif
 273         return 0;
 274
 275 err:
 276         pr_err("%s: can't add protocol\n", __func__);
 277         return -EAGAIN;
 278 }
 279
 280 static void __exit tunnel4_fini(void)
 281 {
 282 #if IS_ENABLED(CONFIG_INET_XFRM_TUNNEL)
 283         if (xfrm_input_unregister_afinfo(&tunnel4_input_afinfo))
 284                 pr_err("tunnel4 close: can't remove input afinfo\n");
 285 #endif
 286 #if IS_ENABLED(CONFIG_MPLS)
 287         if (inet_del_protocol(&tunnelmpls4_protocol, IPPROTO_MPLS))
 288                 pr_err("tunnelmpls4 close: can't remove protocol\n");
 289 #endif
 290 #if IS_ENABLED(CONFIG_IPV6)
 291         if (inet_del_protocol(&tunnel64_protocol, IPPROTO_IPV6))
 292                 pr_err("tunnel64 close: can't remove protocol\n");
 293 #endif
 294         if (inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP))
 295                 pr_err("tunnel4 close: can't remove protocol\n");
 296 }
 297
 298 module_init(tunnel4_init);
 299 module_exit(tunnel4_fini);
 300 MODULE_LICENSE("GPL");