net/ipv6/xfrm6_protocol.c

   1 /* xfrm6_protocol.c - Generic xfrm protocol multiplexer for ipv6.
   2  *
   3  * Copyright (C) 2013 secunet Security Networks AG
   4  *
   5  * Author:
   6  * Steffen Klassert <steffen.klassert@secunet.com>
   7  *
   8  * Based on:
   9  * net/ipv4/xfrm4_protocol.c
  10  *
  11  *      This program is free software; you can redistribute it and/or
  12  *      modify it under the terms of the GNU General Public License
  13  *      as published by the Free Software Foundation; either version
  14  *      2 of the License, or (at your option) any later version.
  15  */
  16
  17 #include <linux/init.h>
  18 #include <linux/mutex.h>
  19 #include <linux/skbuff.h>
  20 #include <linux/icmpv6.h>
  21 #include <net/ipv6.h>
  22 #include <net/protocol.h>
  23 #include <net/xfrm.h>
  24
  25 static struct xfrm6_protocol __rcu *esp6_handlers __read_mostly;
  26 static struct xfrm6_protocol __rcu *ah6_handlers __read_mostly;
  27 static struct xfrm6_protocol __rcu *ipcomp6_handlers __read_mostly;
  28 static DEFINE_MUTEX(xfrm6_protocol_mutex);
  29
  30 static inline struct xfrm6_protocol __rcu **proto_handlers(u8 protocol)
  31 {
  32         switch (protocol) {
  33         case IPPROTO_ESP:
  34                 return &esp6_handlers;
  35         case IPPROTO_AH:
  36                 return &ah6_handlers;
  37         case IPPROTO_COMP:
  38                 return &ipcomp6_handlers;
  39         }
  40
  41         return NULL;
  42 }
  43
  44 #define for_each_protocol_rcu(head, handler)            \
  45         for (handler = rcu_dereference(head);           \
  46              handler != NULL;                           \
  47              handler = rcu_dereference(handler->next))  \
  48
  49 int xfrm6_rcv_cb(struct sk_buff *skb, u8 protocol, int err)
  50 {
  51         int ret;
  52         struct xfrm6_protocol *handler;
  53         struct xfrm6_protocol __rcu **head = proto_handlers(protocol);
  54
  55         if (!head)
  56                 return 0;
  57
  58         for_each_protocol_rcu(*proto_handlers(protocol), handler)
  59                 if ((ret = handler->cb_handler(skb, err)) <= 0)
  60                         return ret;
  61
  62         return 0;
  63 }
  64 EXPORT_SYMBOL(xfrm6_rcv_cb);
  65
  66 static int xfrm6_esp_rcv(struct sk_buff *skb)
  67 {
  68         int ret;
  69         struct xfrm6_protocol *handler;
  70
  71         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
  72
  73         for_each_protocol_rcu(esp6_handlers, handler)
  74                 if ((ret = handler->handler(skb)) != -EINVAL)
  75                         return ret;
  76
  77         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
  78
  79         kfree_skb(skb);
  80         return 0;
  81 }
  82
  83 static int xfrm6_esp_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
  84                           u8 type, u8 code, int offset, __be32 info)
  85 {
  86         struct xfrm6_protocol *handler;
  87
  88         for_each_protocol_rcu(esp6_handlers, handler)
  89                 if (!handler->err_handler(skb, opt, type, code, offset, info))
  90                         return 0;
  91
  92         return -ENOENT;
  93 }
  94
  95 static int xfrm6_ah_rcv(struct sk_buff *skb)
  96 {
  97         int ret;
  98         struct xfrm6_protocol *handler;
  99
 100         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
 101
 102         for_each_protocol_rcu(ah6_handlers, handler)
 103                 if ((ret = handler->handler(skb)) != -EINVAL)
 104                         return ret;
 105
 106         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 107
 108         kfree_skb(skb);
 109         return 0;
 110 }
 111
 112 static int xfrm6_ah_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 113                          u8 type, u8 code, int offset, __be32 info)
 114 {
 115         struct xfrm6_protocol *handler;
 116
 117         for_each_protocol_rcu(ah6_handlers, handler)
 118                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 119                         return 0;
 120
 121         return -ENOENT;
 122 }
 123
 124 static int xfrm6_ipcomp_rcv(struct sk_buff *skb)
 125 {
 126         int ret;
 127         struct xfrm6_protocol *handler;
 128
 129         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
 130
 131         for_each_protocol_rcu(ipcomp6_handlers, handler)
 132                 if ((ret = handler->handler(skb)) != -EINVAL)
 133                         return ret;
 134
 135         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 136
 137         kfree_skb(skb);
 138         return 0;
 139 }
 140
 141 static int xfrm6_ipcomp_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 142                              u8 type, u8 code, int offset, __be32 info)
 143 {
 144         struct xfrm6_protocol *handler;
 145
 146         for_each_protocol_rcu(ipcomp6_handlers, handler)
 147                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 148                         return 0;
 149
 150         return -ENOENT;
 151 }
 152
 153 static const struct inet6_protocol esp6_protocol = {
 154         .handler        =       xfrm6_esp_rcv,
 155         .err_handler    =       xfrm6_esp_err,
 156         .flags          =       INET6_PROTO_NOPOLICY,
 157 };
 158
 159 static const struct inet6_protocol ah6_protocol = {
 160         .handler        =       xfrm6_ah_rcv,
 161         .err_handler    =       xfrm6_ah_err,
 162         .flags          =       INET6_PROTO_NOPOLICY,
 163 };
 164
 165 static const struct inet6_protocol ipcomp6_protocol = {
 166         .handler        =       xfrm6_ipcomp_rcv,
 167         .err_handler    =       xfrm6_ipcomp_err,
 168         .flags          =       INET6_PROTO_NOPOLICY,
 169 };
 170
 171 static const struct xfrm_input_afinfo xfrm6_input_afinfo = {
 172         .family         =       AF_INET6,
 173         .callback       =       xfrm6_rcv_cb,
 174 };
 175
 176 static inline const struct inet6_protocol *netproto(unsigned char protocol)
 177 {
 178         switch (protocol) {
 179         case IPPROTO_ESP:
 180                 return &esp6_protocol;
 181         case IPPROTO_AH:
 182                 return &ah6_protocol;
 183         case IPPROTO_COMP:
 184                 return &ipcomp6_protocol;
 185         }
 186
 187         return NULL;
 188 }
 189
 190 int xfrm6_protocol_register(struct xfrm6_protocol *handler,
 191                             unsigned char protocol)
 192 {
 193         struct xfrm6_protocol __rcu **pprev;
 194         struct xfrm6_protocol *t;
 195         bool add_netproto = false;
 196         int ret = -EEXIST;
 197         int priority = handler->priority;
 198
 199         if (!proto_handlers(protocol) || !netproto(protocol))
 200                 return -EINVAL;
 201
 202         mutex_lock(&xfrm6_protocol_mutex);
 203
 204         if (!rcu_dereference_protected(*proto_handlers(protocol),
 205                                        lockdep_is_held(&xfrm6_protocol_mutex)))
 206                 add_netproto = true;
 207
 208         for (pprev = proto_handlers(protocol);
 209              (t = rcu_dereference_protected(*pprev,
 210                         lockdep_is_held(&xfrm6_protocol_mutex))) != NULL;
 211              pprev = &t->next) {
 212                 if (t->priority < priority)
 213                         break;
 214                 if (t->priority == priority)
 215                         goto err;
 216         }
 217
 218         handler->next = *pprev;
 219         rcu_assign_pointer(*pprev, handler);
 220
 221         ret = 0;
 222
 223 err:
 224         mutex_unlock(&xfrm6_protocol_mutex);
 225
 226         if (add_netproto) {
 227                 if (inet6_add_protocol(netproto(protocol), protocol)) {
 228                         pr_err("%s: can't add protocol\n", __func__);
 229                         ret = -EAGAIN;
 230                 }
 231         }
 232
 233         return ret;
 234 }
 235 EXPORT_SYMBOL(xfrm6_protocol_register);
 236
 237 int xfrm6_protocol_deregister(struct xfrm6_protocol *handler,
 238                               unsigned char protocol)
 239 {
 240         struct xfrm6_protocol __rcu **pprev;
 241         struct xfrm6_protocol *t;
 242         int ret = -ENOENT;
 243
 244         if (!proto_handlers(protocol) || !netproto(protocol))
 245                 return -EINVAL;
 246
 247         mutex_lock(&xfrm6_protocol_mutex);
 248
 249         for (pprev = proto_handlers(protocol);
 250              (t = rcu_dereference_protected(*pprev,
 251                         lockdep_is_held(&xfrm6_protocol_mutex))) != NULL;
 252              pprev = &t->next) {
 253                 if (t == handler) {
 254                         *pprev = handler->next;
 255                         ret = 0;
 256                         break;
 257                 }
 258         }
 259
 260         if (!rcu_dereference_protected(*proto_handlers(protocol),
 261                                        lockdep_is_held(&xfrm6_protocol_mutex))) {
 262                 if (inet6_del_protocol(netproto(protocol), protocol) < 0) {
 263                         pr_err("%s: can't remove protocol\n", __func__);
 264                         ret = -EAGAIN;
 265                 }
 266         }
 267
 268         mutex_unlock(&xfrm6_protocol_mutex);
 269
 270         synchronize_net();
 271
 272         return ret;
 273 }
 274 EXPORT_SYMBOL(xfrm6_protocol_deregister);
 275
 276 int __init xfrm6_protocol_init(void)
 277 {
 278         return xfrm_input_register_afinfo(&xfrm6_input_afinfo);
 279 }
 280
 281 void xfrm6_protocol_fini(void)
 282 {
 283         xfrm_input_unregister_afinfo(&xfrm6_input_afinfo);
 284 }