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