net/ipv4/xfrm4_protocol.c

   1 /* xfrm4_protocol.c - Generic xfrm protocol multiplexer.
   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/tunnel4.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 <net/icmp.h>
  21 #include <net/ip.h>
  22 #include <net/protocol.h>
  23 #include <net/xfrm.h>
  24
  25 static struct xfrm4_protocol __rcu *esp4_handlers __read_mostly;
  26 static struct xfrm4_protocol __rcu *ah4_handlers __read_mostly;
  27 static struct xfrm4_protocol __rcu *ipcomp4_handlers __read_mostly;
  28 static DEFINE_MUTEX(xfrm4_protocol_mutex);
  29
  30 static inline struct xfrm4_protocol __rcu **proto_handlers(u8 protocol)
  31 {
  32         switch (protocol) {
  33         case IPPROTO_ESP:
  34                 return &esp4_handlers;
  35         case IPPROTO_AH:
  36                 return &ah4_handlers;
  37         case IPPROTO_COMP:
  38                 return &ipcomp4_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 static int xfrm4_rcv_cb(struct sk_buff *skb, u8 protocol, int err)
  50 {
  51         int ret;
  52         struct xfrm4_protocol *handler;
  53         struct xfrm4_protocol __rcu **head = proto_handlers(protocol);
  54
  55         if (!head)
  56                 return 0;
  57
  58         for_each_protocol_rcu(*head, handler)
  59                 if ((ret = handler->cb_handler(skb, err)) <= 0)
  60                         return ret;
  61
  62         return 0;
  63 }
  64
  65 int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
  66                     int encap_type)
  67 {
  68         int ret;
  69         struct xfrm4_protocol *handler;
  70         struct xfrm4_protocol __rcu **head = proto_handlers(nexthdr);
  71
  72         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
  73         XFRM_SPI_SKB_CB(skb)->family = AF_INET;
  74         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
  75
  76         if (!head)
  77                 goto out;
  78
  79         for_each_protocol_rcu(*head, handler)
  80                 if ((ret = handler->input_handler(skb, nexthdr, spi, encap_type)) != -EINVAL)
  81                         return ret;
  82
  83 out:
  84         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
  85
  86         kfree_skb(skb);
  87         return 0;
  88 }
  89 EXPORT_SYMBOL(xfrm4_rcv_encap);
  90
  91 static int xfrm4_esp_rcv(struct sk_buff *skb)
  92 {
  93         int ret;
  94         struct xfrm4_protocol *handler;
  95
  96         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
  97
  98         for_each_protocol_rcu(esp4_handlers, handler)
  99                 if ((ret = handler->handler(skb)) != -EINVAL)
 100                         return ret;
 101
 102         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 103
 104         kfree_skb(skb);
 105         return 0;
 106 }
 107
 108 static int xfrm4_esp_err(struct sk_buff *skb, u32 info)
 109 {
 110         struct xfrm4_protocol *handler;
 111
 112         for_each_protocol_rcu(esp4_handlers, handler)
 113                 if (!handler->err_handler(skb, info))
 114                         return 0;
 115
 116         return -ENOENT;
 117 }
 118
 119 static int xfrm4_ah_rcv(struct sk_buff *skb)
 120 {
 121         int ret;
 122         struct xfrm4_protocol *handler;
 123
 124         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
 125
 126         for_each_protocol_rcu(ah4_handlers, handler)
 127                 if ((ret = handler->handler(skb)) != -EINVAL)
 128                         return ret;
 129
 130         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 131
 132         kfree_skb(skb);
 133         return 0;
 134 }
 135
 136 static int xfrm4_ah_err(struct sk_buff *skb, u32 info)
 137 {
 138         struct xfrm4_protocol *handler;
 139
 140         for_each_protocol_rcu(ah4_handlers, handler)
 141                 if (!handler->err_handler(skb, info))
 142                         return 0;
 143
 144         return -ENOENT;
 145 }
 146
 147 static int xfrm4_ipcomp_rcv(struct sk_buff *skb)
 148 {
 149         int ret;
 150         struct xfrm4_protocol *handler;
 151
 152         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
 153
 154         for_each_protocol_rcu(ipcomp4_handlers, handler)
 155                 if ((ret = handler->handler(skb)) != -EINVAL)
 156                         return ret;
 157
 158         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 159
 160         kfree_skb(skb);
 161         return 0;
 162 }
 163
 164 static int xfrm4_ipcomp_err(struct sk_buff *skb, u32 info)
 165 {
 166         struct xfrm4_protocol *handler;
 167
 168         for_each_protocol_rcu(ipcomp4_handlers, handler)
 169                 if (!handler->err_handler(skb, info))
 170                         return 0;
 171
 172         return -ENOENT;
 173 }
 174
 175 static const struct net_protocol esp4_protocol = {
 176         .handler        =       xfrm4_esp_rcv,
 177         .err_handler    =       xfrm4_esp_err,
 178         .no_policy      =       1,
 179         .netns_ok       =       1,
 180 };
 181
 182 static const struct net_protocol ah4_protocol = {
 183         .handler        =       xfrm4_ah_rcv,
 184         .err_handler    =       xfrm4_ah_err,
 185         .no_policy      =       1,
 186         .netns_ok       =       1,
 187 };
 188
 189 static const struct net_protocol ipcomp4_protocol = {
 190         .handler        =       xfrm4_ipcomp_rcv,
 191         .err_handler    =       xfrm4_ipcomp_err,
 192         .no_policy      =       1,
 193         .netns_ok       =       1,
 194 };
 195
 196 static const struct xfrm_input_afinfo xfrm4_input_afinfo = {
 197         .family         =       AF_INET,
 198         .callback       =       xfrm4_rcv_cb,
 199 };
 200
 201 static inline const struct net_protocol *netproto(unsigned char protocol)
 202 {
 203         switch (protocol) {
 204         case IPPROTO_ESP:
 205                 return &esp4_protocol;
 206         case IPPROTO_AH:
 207                 return &ah4_protocol;
 208         case IPPROTO_COMP:
 209                 return &ipcomp4_protocol;
 210         }
 211
 212         return NULL;
 213 }
 214
 215 int xfrm4_protocol_register(struct xfrm4_protocol *handler,
 216                             unsigned char protocol)
 217 {
 218         struct xfrm4_protocol __rcu **pprev;
 219         struct xfrm4_protocol *t;
 220         bool add_netproto = false;
 221         int ret = -EEXIST;
 222         int priority = handler->priority;
 223
 224         if (!proto_handlers(protocol) || !netproto(protocol))
 225                 return -EINVAL;
 226
 227         mutex_lock(&xfrm4_protocol_mutex);
 228
 229         if (!rcu_dereference_protected(*proto_handlers(protocol),
 230                                        lockdep_is_held(&xfrm4_protocol_mutex)))
 231                 add_netproto = true;
 232
 233         for (pprev = proto_handlers(protocol);
 234              (t = rcu_dereference_protected(*pprev,
 235                         lockdep_is_held(&xfrm4_protocol_mutex))) != NULL;
 236              pprev = &t->next) {
 237                 if (t->priority < priority)
 238                         break;
 239                 if (t->priority == priority)
 240                         goto err;
 241         }
 242
 243         handler->next = *pprev;
 244         rcu_assign_pointer(*pprev, handler);
 245
 246         ret = 0;
 247
 248 err:
 249         mutex_unlock(&xfrm4_protocol_mutex);
 250
 251         if (add_netproto) {
 252                 if (inet_add_protocol(netproto(protocol), protocol)) {
 253                         pr_err("%s: can't add protocol\n", __func__);
 254                         ret = -EAGAIN;
 255                 }
 256         }
 257
 258         return ret;
 259 }
 260 EXPORT_SYMBOL(xfrm4_protocol_register);
 261
 262 int xfrm4_protocol_deregister(struct xfrm4_protocol *handler,
 263                               unsigned char protocol)
 264 {
 265         struct xfrm4_protocol __rcu **pprev;
 266         struct xfrm4_protocol *t;
 267         int ret = -ENOENT;
 268
 269         if (!proto_handlers(protocol) || !netproto(protocol))
 270                 return -EINVAL;
 271
 272         mutex_lock(&xfrm4_protocol_mutex);
 273
 274         for (pprev = proto_handlers(protocol);
 275              (t = rcu_dereference_protected(*pprev,
 276                         lockdep_is_held(&xfrm4_protocol_mutex))) != NULL;
 277              pprev = &t->next) {
 278                 if (t == handler) {
 279                         *pprev = handler->next;
 280                         ret = 0;
 281                         break;
 282                 }
 283         }
 284
 285         if (!rcu_dereference_protected(*proto_handlers(protocol),
 286                                        lockdep_is_held(&xfrm4_protocol_mutex))) {
 287                 if (inet_del_protocol(netproto(protocol), protocol) < 0) {
 288                         pr_err("%s: can't remove protocol\n", __func__);
 289                         ret = -EAGAIN;
 290                 }
 291         }
 292
 293         mutex_unlock(&xfrm4_protocol_mutex);
 294
 295         synchronize_net();
 296
 297         return ret;
 298 }
 299 EXPORT_SYMBOL(xfrm4_protocol_deregister);
 300
 301 void __init xfrm4_protocol_init(void)
 302 {
 303         xfrm_input_register_afinfo(&xfrm4_input_afinfo);
 304 }
 305 EXPORT_SYMBOL(xfrm4_protocol_init);