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
  54         for_each_protocol_rcu(*proto_handlers(protocol), handler)
  55                 if ((ret = handler->cb_handler(skb, err)) <= 0)
  56                         return ret;
  57
  58         return 0;
  59 }
  60 EXPORT_SYMBOL(xfrm4_rcv_cb);
  61
  62 int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
  63                     int encap_type)
  64 {
  65         int ret;
  66         struct xfrm4_protocol *handler;
  67
  68         XFRM_SPI_SKB_CB(skb)->family = AF_INET;
  69         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
  70
  71         for_each_protocol_rcu(*proto_handlers(nexthdr), handler)
  72                 if ((ret = handler->input_handler(skb, nexthdr, spi, encap_type)) != -EINVAL)
  73                         return ret;
  74
  75         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
  76
  77         kfree_skb(skb);
  78         return 0;
  79 }
  80 EXPORT_SYMBOL(xfrm4_rcv_encap);
  81
  82 static int xfrm4_esp_rcv(struct sk_buff *skb)
  83 {
  84         int ret;
  85         struct xfrm4_protocol *handler;
  86
  87         for_each_protocol_rcu(esp4_handlers, handler)
  88                 if ((ret = handler->handler(skb)) != -EINVAL)
  89                         return ret;
  90
  91         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
  92
  93         kfree_skb(skb);
  94         return 0;
  95 }
  96
  97 static void xfrm4_esp_err(struct sk_buff *skb, u32 info)
  98 {
  99         struct xfrm4_protocol *handler;
 100
 101         for_each_protocol_rcu(esp4_handlers, handler)
 102                 if (!handler->err_handler(skb, info))
 103                         break;
 104 }
 105
 106 static int xfrm4_ah_rcv(struct sk_buff *skb)
 107 {
 108         int ret;
 109         struct xfrm4_protocol *handler;
 110
 111         for_each_protocol_rcu(ah4_handlers, handler)
 112                 if ((ret = handler->handler(skb)) != -EINVAL)
 113                         return ret;;
 114
 115         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 116
 117         kfree_skb(skb);
 118         return 0;
 119 }
 120
 121 static void xfrm4_ah_err(struct sk_buff *skb, u32 info)
 122 {
 123         struct xfrm4_protocol *handler;
 124
 125         for_each_protocol_rcu(ah4_handlers, handler)
 126                 if (!handler->err_handler(skb, info))
 127                         break;
 128 }
 129
 130 static int xfrm4_ipcomp_rcv(struct sk_buff *skb)
 131 {
 132         int ret;
 133         struct xfrm4_protocol *handler;
 134
 135         for_each_protocol_rcu(ipcomp4_handlers, handler)
 136                 if ((ret = handler->handler(skb)) != -EINVAL)
 137                         return ret;
 138
 139         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 140
 141         kfree_skb(skb);
 142         return 0;
 143 }
 144
 145 static void xfrm4_ipcomp_err(struct sk_buff *skb, u32 info)
 146 {
 147         struct xfrm4_protocol *handler;
 148
 149         for_each_protocol_rcu(ipcomp4_handlers, handler)
 150                 if (!handler->err_handler(skb, info))
 151                         break;
 152 }
 153
 154 static const struct net_protocol esp4_protocol = {
 155         .handler        =       xfrm4_esp_rcv,
 156         .err_handler    =       xfrm4_esp_err,
 157         .no_policy      =       1,
 158         .netns_ok       =       1,
 159 };
 160
 161 static const struct net_protocol ah4_protocol = {
 162         .handler        =       xfrm4_ah_rcv,
 163         .err_handler    =       xfrm4_ah_err,
 164         .no_policy      =       1,
 165         .netns_ok       =       1,
 166 };
 167
 168 static const struct net_protocol ipcomp4_protocol = {
 169         .handler        =       xfrm4_ipcomp_rcv,
 170         .err_handler    =       xfrm4_ipcomp_err,
 171         .no_policy      =       1,
 172         .netns_ok       =       1,
 173 };
 174
 175 static inline const struct net_protocol *netproto(unsigned char protocol)
 176 {
 177         switch (protocol) {
 178         case IPPROTO_ESP:
 179                 return &esp4_protocol;
 180         case IPPROTO_AH:
 181                 return &ah4_protocol;
 182         case IPPROTO_COMP:
 183                 return &ipcomp4_protocol;
 184         }
 185
 186         return NULL;
 187 }
 188
 189 int xfrm4_protocol_register(struct xfrm4_protocol *handler,
 190                             unsigned char protocol)
 191 {
 192         struct xfrm4_protocol __rcu **pprev;
 193         struct xfrm4_protocol *t;
 194         bool add_netproto = false;
 195
 196         int ret = -EEXIST;
 197         int priority = handler->priority;
 198
 199         mutex_lock(&xfrm4_protocol_mutex);
 200
 201         if (!rcu_dereference_protected(*proto_handlers(protocol),
 202                                        lockdep_is_held(&xfrm4_protocol_mutex)))
 203                 add_netproto = true;
 204
 205         for (pprev = proto_handlers(protocol);
 206              (t = rcu_dereference_protected(*pprev,
 207                         lockdep_is_held(&xfrm4_protocol_mutex))) != NULL;
 208              pprev = &t->next) {
 209                 if (t->priority < priority)
 210                         break;
 211                 if (t->priority == priority)
 212                         goto err;
 213         }
 214
 215         handler->next = *pprev;
 216         rcu_assign_pointer(*pprev, handler);
 217
 218         ret = 0;
 219
 220 err:
 221         mutex_unlock(&xfrm4_protocol_mutex);
 222
 223         if (add_netproto) {
 224                 if (inet_add_protocol(netproto(protocol), protocol)) {
 225                         pr_err("%s: can't add protocol\n", __func__);
 226                         ret = -EAGAIN;
 227                 }
 228         }
 229
 230         return ret;
 231 }
 232 EXPORT_SYMBOL(xfrm4_protocol_register);
 233
 234 int xfrm4_protocol_deregister(struct xfrm4_protocol *handler,
 235                               unsigned char protocol)
 236 {
 237         struct xfrm4_protocol __rcu **pprev;
 238         struct xfrm4_protocol *t;
 239         int ret = -ENOENT;
 240
 241         mutex_lock(&xfrm4_protocol_mutex);
 242
 243         for (pprev = proto_handlers(protocol);
 244              (t = rcu_dereference_protected(*pprev,
 245                         lockdep_is_held(&xfrm4_protocol_mutex))) != NULL;
 246              pprev = &t->next) {
 247                 if (t == handler) {
 248                         *pprev = handler->next;
 249                         ret = 0;
 250                         break;
 251                 }
 252         }
 253
 254         if (!rcu_dereference_protected(*proto_handlers(protocol),
 255                                        lockdep_is_held(&xfrm4_protocol_mutex))) {
 256                 if (inet_del_protocol(netproto(protocol), protocol) < 0) {
 257                         pr_err("%s: can't remove protocol\n", __func__);
 258                         ret = -EAGAIN;
 259                 }
 260         }
 261
 262         mutex_unlock(&xfrm4_protocol_mutex);
 263
 264         synchronize_net();
 265
 266         return ret;
 267 }
 268 EXPORT_SYMBOL(xfrm4_protocol_deregister);