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 void 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                         break;
  91 }
  92
  93 static int xfrm6_ah_rcv(struct sk_buff *skb)
  94 {
  95         int ret;
  96         struct xfrm6_protocol *handler;
  97
  98         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
  99
 100         for_each_protocol_rcu(ah6_handlers, handler)
 101                 if ((ret = handler->handler(skb)) != -EINVAL)
 102                         return ret;
 103
 104         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 105
 106         kfree_skb(skb);
 107         return 0;
 108 }
 109
 110 static void xfrm6_ah_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 111                          u8 type, u8 code, int offset, __be32 info)
 112 {
 113         struct xfrm6_protocol *handler;
 114
 115         for_each_protocol_rcu(ah6_handlers, handler)
 116                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 117                         break;
 118 }
 119
 120 static int xfrm6_ipcomp_rcv(struct sk_buff *skb)
 121 {
 122         int ret;
 123         struct xfrm6_protocol *handler;
 124
 125         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
 126
 127         for_each_protocol_rcu(ipcomp6_handlers, handler)
 128                 if ((ret = handler->handler(skb)) != -EINVAL)
 129                         return ret;
 130
 131         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 132
 133         kfree_skb(skb);
 134         return 0;
 135 }
 136
 137 static void xfrm6_ipcomp_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 138                              u8 type, u8 code, int offset, __be32 info)
 139 {
 140         struct xfrm6_protocol *handler;
 141
 142         for_each_protocol_rcu(ipcomp6_handlers, handler)
 143                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 144                         break;
 145 }
 146
 147 static const struct inet6_protocol esp6_protocol = {
 148         .handler        =       xfrm6_esp_rcv,
 149         .err_handler    =       xfrm6_esp_err,
 150         .flags          =       INET6_PROTO_NOPOLICY,
 151 };
 152
 153 static const struct inet6_protocol ah6_protocol = {
 154         .handler        =       xfrm6_ah_rcv,
 155         .err_handler    =       xfrm6_ah_err,
 156         .flags          =       INET6_PROTO_NOPOLICY,
 157 };
 158
 159 static const struct inet6_protocol ipcomp6_protocol = {
 160         .handler        =       xfrm6_ipcomp_rcv,
 161         .err_handler    =       xfrm6_ipcomp_err,
 162         .flags          =       INET6_PROTO_NOPOLICY,
 163 };
 164
 165 static struct xfrm_input_afinfo xfrm6_input_afinfo = {
 166         .family         =       AF_INET6,
 167         .owner          =       THIS_MODULE,
 168         .callback       =       xfrm6_rcv_cb,
 169 };
 170
 171 static inline const struct inet6_protocol *netproto(unsigned char protocol)
 172 {
 173         switch (protocol) {
 174         case IPPROTO_ESP:
 175                 return &esp6_protocol;
 176         case IPPROTO_AH:
 177                 return &ah6_protocol;
 178         case IPPROTO_COMP:
 179                 return &ipcomp6_protocol;
 180         }
 181
 182         return NULL;
 183 }
 184
 185 int xfrm6_protocol_register(struct xfrm6_protocol *handler,
 186                             unsigned char protocol)
 187 {
 188         struct xfrm6_protocol __rcu **pprev;
 189         struct xfrm6_protocol *t;
 190         bool add_netproto = false;
 191         int ret = -EEXIST;
 192         int priority = handler->priority;
 193
 194         if (!proto_handlers(protocol) || !netproto(protocol))
 195                 return -EINVAL;
 196
 197         mutex_lock(&xfrm6_protocol_mutex);
 198
 199         if (!rcu_dereference_protected(*proto_handlers(protocol),
 200                                        lockdep_is_held(&xfrm6_protocol_mutex)))
 201                 add_netproto = true;
 202
 203         for (pprev = proto_handlers(protocol);
 204              (t = rcu_dereference_protected(*pprev,
 205                         lockdep_is_held(&xfrm6_protocol_mutex))) != NULL;
 206              pprev = &t->next) {
 207                 if (t->priority < priority)
 208                         break;
 209                 if (t->priority == priority)
 210                         goto err;
 211         }
 212
 213         handler->next = *pprev;
 214         rcu_assign_pointer(*pprev, handler);
 215
 216         ret = 0;
 217
 218 err:
 219         mutex_unlock(&xfrm6_protocol_mutex);
 220
 221         if (add_netproto) {
 222                 if (inet6_add_protocol(netproto(protocol), protocol)) {
 223                         pr_err("%s: can't add protocol\n", __func__);
 224                         ret = -EAGAIN;
 225                 }
 226         }
 227
 228         return ret;
 229 }
 230 EXPORT_SYMBOL(xfrm6_protocol_register);
 231
 232 int xfrm6_protocol_deregister(struct xfrm6_protocol *handler,
 233                               unsigned char protocol)
 234 {
 235         struct xfrm6_protocol __rcu **pprev;
 236         struct xfrm6_protocol *t;
 237         int ret = -ENOENT;
 238
 239         if (!proto_handlers(protocol) || !netproto(protocol))
 240                 return -EINVAL;
 241
 242         mutex_lock(&xfrm6_protocol_mutex);
 243
 244         for (pprev = proto_handlers(protocol);
 245              (t = rcu_dereference_protected(*pprev,
 246                         lockdep_is_held(&xfrm6_protocol_mutex))) != NULL;
 247              pprev = &t->next) {
 248                 if (t == handler) {
 249                         *pprev = handler->next;
 250                         ret = 0;
 251                         break;
 252                 }
 253         }
 254
 255         if (!rcu_dereference_protected(*proto_handlers(protocol),
 256                                        lockdep_is_held(&xfrm6_protocol_mutex))) {
 257                 if (inet6_del_protocol(netproto(protocol), protocol) < 0) {
 258                         pr_err("%s: can't remove protocol\n", __func__);
 259                         ret = -EAGAIN;
 260                 }
 261         }
 262
 263         mutex_unlock(&xfrm6_protocol_mutex);
 264
 265         synchronize_net();
 266
 267         return ret;
 268 }
 269 EXPORT_SYMBOL(xfrm6_protocol_deregister);
 270
 271 int __init xfrm6_protocol_init(void)
 272 {
 273         return xfrm_input_register_afinfo(&xfrm6_input_afinfo);
 274 }
 275
 276 void xfrm6_protocol_fini(void)
 277 {
 278         xfrm_input_unregister_afinfo(&xfrm6_input_afinfo);
 279 }