net/ipv6/tunnel6.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C)2003,2004 USAGI/WIDE Project
   4  *
   5  * Authors      Mitsuru KANDA  <mk@linux-ipv6.org>
   6  *              YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
   7  */
   8
   9 #define pr_fmt(fmt) "IPv6: " fmt
  10
  11 #include <linux/icmpv6.h>
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/slab.h>
  18 #include <net/ipv6.h>
  19 #include <net/protocol.h>
  20 #include <net/xfrm.h>
  21
  22 static struct xfrm6_tunnel __rcu *tunnel6_handlers __read_mostly;
  23 static struct xfrm6_tunnel __rcu *tunnel46_handlers __read_mostly;
  24 static struct xfrm6_tunnel __rcu *tunnelmpls6_handlers __read_mostly;
  25 static DEFINE_MUTEX(tunnel6_mutex);
  26
  27 static inline int xfrm6_tunnel_mpls_supported(void)
  28 {
  29         return IS_ENABLED(CONFIG_MPLS);
  30 }
  31
  32 int xfrm6_tunnel_register(struct xfrm6_tunnel *handler, unsigned short family)
  33 {
  34         struct xfrm6_tunnel __rcu **pprev;
  35         struct xfrm6_tunnel *t;
  36         int ret = -EEXIST;
  37         int priority = handler->priority;
  38
  39         mutex_lock(&tunnel6_mutex);
  40
  41         switch (family) {
  42         case AF_INET6:
  43                 pprev = &tunnel6_handlers;
  44                 break;
  45         case AF_INET:
  46                 pprev = &tunnel46_handlers;
  47                 break;
  48         case AF_MPLS:
  49                 pprev = &tunnelmpls6_handlers;
  50                 break;
  51         default:
  52                 goto err;
  53         }
  54
  55         for (; (t = rcu_dereference_protected(*pprev,
  56                         lockdep_is_held(&tunnel6_mutex))) != NULL;
  57              pprev = &t->next) {
  58                 if (t->priority > priority)
  59                         break;
  60                 if (t->priority == priority)
  61                         goto err;
  62         }
  63
  64         handler->next = *pprev;
  65         rcu_assign_pointer(*pprev, handler);
  66
  67         ret = 0;
  68
  69 err:
  70         mutex_unlock(&tunnel6_mutex);
  71
  72         return ret;
  73 }
  74 EXPORT_SYMBOL(xfrm6_tunnel_register);
  75
  76 int xfrm6_tunnel_deregister(struct xfrm6_tunnel *handler, unsigned short family)
  77 {
  78         struct xfrm6_tunnel __rcu **pprev;
  79         struct xfrm6_tunnel *t;
  80         int ret = -ENOENT;
  81
  82         mutex_lock(&tunnel6_mutex);
  83
  84         switch (family) {
  85         case AF_INET6:
  86                 pprev = &tunnel6_handlers;
  87                 break;
  88         case AF_INET:
  89                 pprev = &tunnel46_handlers;
  90                 break;
  91         case AF_MPLS:
  92                 pprev = &tunnelmpls6_handlers;
  93                 break;
  94         default:
  95                 goto err;
  96         }
  97
  98         for (; (t = rcu_dereference_protected(*pprev,
  99                         lockdep_is_held(&tunnel6_mutex))) != NULL;
 100              pprev = &t->next) {
 101                 if (t == handler) {
 102                         *pprev = handler->next;
 103                         ret = 0;
 104                         break;
 105                 }
 106         }
 107
 108 err:
 109         mutex_unlock(&tunnel6_mutex);
 110
 111         synchronize_net();
 112
 113         return ret;
 114 }
 115 EXPORT_SYMBOL(xfrm6_tunnel_deregister);
 116
 117 #define for_each_tunnel_rcu(head, handler)              \
 118         for (handler = rcu_dereference(head);           \
 119              handler != NULL;                           \
 120              handler = rcu_dereference(handler->next))  \
 121
 122 static int tunnelmpls6_rcv(struct sk_buff *skb)
 123 {
 124         struct xfrm6_tunnel *handler;
 125
 126         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 127                 goto drop;
 128
 129         for_each_tunnel_rcu(tunnelmpls6_handlers, handler)
 130                 if (!handler->handler(skb))
 131                         return 0;
 132
 133         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 134
 135 drop:
 136         kfree_skb(skb);
 137         return 0;
 138 }
 139
 140 static int tunnel6_rcv(struct sk_buff *skb)
 141 {
 142         struct xfrm6_tunnel *handler;
 143
 144         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 145                 goto drop;
 146
 147         for_each_tunnel_rcu(tunnel6_handlers, handler)
 148                 if (!handler->handler(skb))
 149                         return 0;
 150
 151         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 152
 153 drop:
 154         kfree_skb(skb);
 155         return 0;
 156 }
 157
 158 static int tunnel46_rcv(struct sk_buff *skb)
 159 {
 160         struct xfrm6_tunnel *handler;
 161
 162         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 163                 goto drop;
 164
 165         for_each_tunnel_rcu(tunnel46_handlers, handler)
 166                 if (!handler->handler(skb))
 167                         return 0;
 168
 169         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 170
 171 drop:
 172         kfree_skb(skb);
 173         return 0;
 174 }
 175
 176 static int tunnel6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 177                         u8 type, u8 code, int offset, __be32 info)
 178 {
 179         struct xfrm6_tunnel *handler;
 180
 181         for_each_tunnel_rcu(tunnel6_handlers, handler)
 182                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 183                         return 0;
 184
 185         return -ENOENT;
 186 }
 187
 188 static int tunnel46_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 189                          u8 type, u8 code, int offset, __be32 info)
 190 {
 191         struct xfrm6_tunnel *handler;
 192
 193         for_each_tunnel_rcu(tunnel46_handlers, handler)
 194                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 195                         return 0;
 196
 197         return -ENOENT;
 198 }
 199
 200 static int tunnelmpls6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 201                            u8 type, u8 code, int offset, __be32 info)
 202 {
 203         struct xfrm6_tunnel *handler;
 204
 205         for_each_tunnel_rcu(tunnelmpls6_handlers, handler)
 206                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 207                         return 0;
 208
 209         return -ENOENT;
 210 }
 211
 212 static const struct inet6_protocol tunnel6_protocol = {
 213         .handler        = tunnel6_rcv,
 214         .err_handler    = tunnel6_err,
 215         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 216 };
 217
 218 static const struct inet6_protocol tunnel46_protocol = {
 219         .handler        = tunnel46_rcv,
 220         .err_handler    = tunnel46_err,
 221         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 222 };
 223
 224 static const struct inet6_protocol tunnelmpls6_protocol = {
 225         .handler        = tunnelmpls6_rcv,
 226         .err_handler    = tunnelmpls6_err,
 227         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 228 };
 229
 230 static int __init tunnel6_init(void)
 231 {
 232         if (inet6_add_protocol(&tunnel6_protocol, IPPROTO_IPV6)) {
 233                 pr_err("%s: can't add protocol\n", __func__);
 234                 return -EAGAIN;
 235         }
 236         if (inet6_add_protocol(&tunnel46_protocol, IPPROTO_IPIP)) {
 237                 pr_err("%s: can't add protocol\n", __func__);
 238                 inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6);
 239                 return -EAGAIN;
 240         }
 241         if (xfrm6_tunnel_mpls_supported() &&
 242             inet6_add_protocol(&tunnelmpls6_protocol, IPPROTO_MPLS)) {
 243                 pr_err("%s: can't add protocol\n", __func__);
 244                 inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6);
 245                 inet6_del_protocol(&tunnel46_protocol, IPPROTO_IPIP);
 246                 return -EAGAIN;
 247         }
 248         return 0;
 249 }
 250
 251 static void __exit tunnel6_fini(void)
 252 {
 253         if (inet6_del_protocol(&tunnel46_protocol, IPPROTO_IPIP))
 254                 pr_err("%s: can't remove protocol\n", __func__);
 255         if (inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6))
 256                 pr_err("%s: can't remove protocol\n", __func__);
 257         if (xfrm6_tunnel_mpls_supported() &&
 258             inet6_del_protocol(&tunnelmpls6_protocol, IPPROTO_MPLS))
 259                 pr_err("%s: can't remove protocol\n", __func__);
 260 }
 261
 262 module_init(tunnel6_init);
 263 module_exit(tunnel6_fini);
 264 MODULE_LICENSE("GPL");