net/netfilter/nf_conntrack_proto.c

   1 /* L3/L4 protocol support for nf_conntrack. */
   2
   3 /* (C) 1999-2001 Paul `Rusty' Russell
   4  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   5  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/netfilter.h>
  14 #include <linux/module.h>
  15 #include <linux/mutex.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/stddef.h>
  18 #include <linux/err.h>
  19 #include <linux/percpu.h>
  20 #include <linux/notifier.h>
  21 #include <linux/kernel.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/rtnetlink.h>
  24
  25 #include <net/netfilter/nf_conntrack.h>
  26 #include <net/netfilter/nf_conntrack_l3proto.h>
  27 #include <net/netfilter/nf_conntrack_l4proto.h>
  28 #include <net/netfilter/nf_conntrack_core.h>
  29
  30 static struct nf_conntrack_l4proto **nf_ct_protos[PF_MAX] __read_mostly;
  31 struct nf_conntrack_l3proto *nf_ct_l3protos[AF_MAX] __read_mostly;
  32 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
  33
  34 static DEFINE_MUTEX(nf_ct_proto_mutex);
  35
  36 #ifdef CONFIG_SYSCTL
  37 static int
  38 nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_path *path,
  39                       struct ctl_table *table, unsigned int *users)
  40 {
  41         if (*header == NULL) {
  42                 *header = register_sysctl_paths(path, table);
  43                 if (*header == NULL)
  44                         return -ENOMEM;
  45         }
  46         if (users != NULL)
  47                 (*users)++;
  48         return 0;
  49 }
  50
  51 static void
  52 nf_ct_unregister_sysctl(struct ctl_table_header **header,
  53                         struct ctl_table *table, unsigned int *users)
  54 {
  55         if (users != NULL && --*users > 0)
  56                 return;
  57
  58         unregister_sysctl_table(*header);
  59         *header = NULL;
  60 }
  61 #endif
  62
  63 struct nf_conntrack_l4proto *
  64 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
  65 {
  66         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
  67                 return &nf_conntrack_l4proto_generic;
  68
  69         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
  70 }
  71 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  72
  73 /* this is guaranteed to always return a valid protocol helper, since
  74  * it falls back to generic_protocol */
  75 struct nf_conntrack_l3proto *
  76 nf_ct_l3proto_find_get(u_int16_t l3proto)
  77 {
  78         struct nf_conntrack_l3proto *p;
  79
  80         rcu_read_lock();
  81         p = __nf_ct_l3proto_find(l3proto);
  82         if (!try_module_get(p->me))
  83                 p = &nf_conntrack_l3proto_generic;
  84         rcu_read_unlock();
  85
  86         return p;
  87 }
  88 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
  89
  90 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
  91 {
  92         module_put(p->me);
  93 }
  94 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
  95
  96 int
  97 nf_ct_l3proto_try_module_get(unsigned short l3proto)
  98 {
  99         int ret;
 100         struct nf_conntrack_l3proto *p;
 101
 102 retry:  p = nf_ct_l3proto_find_get(l3proto);
 103         if (p == &nf_conntrack_l3proto_generic) {
 104                 ret = request_module("nf_conntrack-%d", l3proto);
 105                 if (!ret)
 106                         goto retry;
 107
 108                 return -EPROTOTYPE;
 109         }
 110
 111         return 0;
 112 }
 113 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 114
 115 void nf_ct_l3proto_module_put(unsigned short l3proto)
 116 {
 117         struct nf_conntrack_l3proto *p;
 118
 119         /* rcu_read_lock not necessary since the caller holds a reference */
 120         p = __nf_ct_l3proto_find(l3proto);
 121         module_put(p->me);
 122 }
 123 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 124
 125 static int kill_l3proto(struct nf_conn *i, void *data)
 126 {
 127         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 128 }
 129
 130 static int kill_l4proto(struct nf_conn *i, void *data)
 131 {
 132         struct nf_conntrack_l4proto *l4proto;
 133         l4proto = (struct nf_conntrack_l4proto *)data;
 134         return nf_ct_protonum(i) == l4proto->l4proto &&
 135                nf_ct_l3num(i) == l4proto->l3proto;
 136 }
 137
 138 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 139 {
 140         int err = 0;
 141
 142 #ifdef CONFIG_SYSCTL
 143         if (l3proto->ctl_table != NULL) {
 144                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 145                                             l3proto->ctl_table_path,
 146                                             l3proto->ctl_table, NULL);
 147         }
 148 #endif
 149         return err;
 150 }
 151
 152 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 153 {
 154 #ifdef CONFIG_SYSCTL
 155         if (l3proto->ctl_table_header != NULL)
 156                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 157                                         l3proto->ctl_table, NULL);
 158 #endif
 159 }
 160
 161 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 162 {
 163         int ret = 0;
 164
 165         if (proto->l3proto >= AF_MAX)
 166                 return -EBUSY;
 167
 168         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 169                 return -EINVAL;
 170
 171         mutex_lock(&nf_ct_proto_mutex);
 172         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 173                 ret = -EBUSY;
 174                 goto out_unlock;
 175         }
 176
 177         ret = nf_ct_l3proto_register_sysctl(proto);
 178         if (ret < 0)
 179                 goto out_unlock;
 180
 181         if (proto->nlattr_tuple_size)
 182                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 183
 184         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 185
 186 out_unlock:
 187         mutex_unlock(&nf_ct_proto_mutex);
 188         return ret;
 189 }
 190 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 191
 192 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 193 {
 194         struct net *net;
 195
 196         BUG_ON(proto->l3proto >= AF_MAX);
 197
 198         mutex_lock(&nf_ct_proto_mutex);
 199         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
 200         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 201                            &nf_conntrack_l3proto_generic);
 202         nf_ct_l3proto_unregister_sysctl(proto);
 203         mutex_unlock(&nf_ct_proto_mutex);
 204
 205         synchronize_rcu();
 206
 207         /* Remove all contrack entries for this protocol */
 208         rtnl_lock();
 209         for_each_net(net)
 210                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
 211         rtnl_unlock();
 212 }
 213 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 214
 215 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 216 {
 217         int err = 0;
 218
 219 #ifdef CONFIG_SYSCTL
 220         if (l4proto->ctl_table != NULL) {
 221                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 222                                             nf_net_netfilter_sysctl_path,
 223                                             l4proto->ctl_table,
 224                                             l4proto->ctl_table_users);
 225                 if (err < 0)
 226                         goto out;
 227         }
 228 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 229         if (l4proto->ctl_compat_table != NULL) {
 230                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 231                                             nf_net_ipv4_netfilter_sysctl_path,
 232                                             l4proto->ctl_compat_table, NULL);
 233                 if (err == 0)
 234                         goto out;
 235                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 236                                         l4proto->ctl_table,
 237                                         l4proto->ctl_table_users);
 238         }
 239 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 240 out:
 241 #endif /* CONFIG_SYSCTL */
 242         return err;
 243 }
 244
 245 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 246 {
 247 #ifdef CONFIG_SYSCTL
 248         if (l4proto->ctl_table_header != NULL &&
 249             *l4proto->ctl_table_header != NULL)
 250                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 251                                         l4proto->ctl_table,
 252                                         l4proto->ctl_table_users);
 253 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 254         if (l4proto->ctl_compat_table_header != NULL)
 255                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 256                                         l4proto->ctl_compat_table, NULL);
 257 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 258 #endif /* CONFIG_SYSCTL */
 259 }
 260
 261 /* FIXME: Allow NULL functions and sub in pointers to generic for
 262    them. --RR */
 263 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 264 {
 265         int ret = 0;
 266
 267         if (l4proto->l3proto >= PF_MAX)
 268                 return -EBUSY;
 269
 270         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
 271                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 272                 return -EINVAL;
 273
 274         mutex_lock(&nf_ct_proto_mutex);
 275         if (!nf_ct_protos[l4proto->l3proto]) {
 276                 /* l3proto may be loaded latter. */
 277                 struct nf_conntrack_l4proto **proto_array;
 278                 int i;
 279
 280                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 281                                       sizeof(struct nf_conntrack_l4proto *),
 282                                       GFP_KERNEL);
 283                 if (proto_array == NULL) {
 284                         ret = -ENOMEM;
 285                         goto out_unlock;
 286                 }
 287
 288                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 289                         proto_array[i] = &nf_conntrack_l4proto_generic;
 290                 nf_ct_protos[l4proto->l3proto] = proto_array;
 291         } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
 292                                         &nf_conntrack_l4proto_generic) {
 293                 ret = -EBUSY;
 294                 goto out_unlock;
 295         }
 296
 297         ret = nf_ct_l4proto_register_sysctl(l4proto);
 298         if (ret < 0)
 299                 goto out_unlock;
 300
 301         l4proto->nla_size = 0;
 302         if (l4proto->nlattr_size)
 303                 l4proto->nla_size += l4proto->nlattr_size();
 304         if (l4proto->nlattr_tuple_size)
 305                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 306
 307         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 308                            l4proto);
 309
 310 out_unlock:
 311         mutex_unlock(&nf_ct_proto_mutex);
 312         return ret;
 313 }
 314 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 315
 316 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 317 {
 318         struct net *net;
 319
 320         BUG_ON(l4proto->l3proto >= PF_MAX);
 321
 322         mutex_lock(&nf_ct_proto_mutex);
 323         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 324         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 325                            &nf_conntrack_l4proto_generic);
 326         nf_ct_l4proto_unregister_sysctl(l4proto);
 327         mutex_unlock(&nf_ct_proto_mutex);
 328
 329         synchronize_rcu();
 330
 331         /* Remove all contrack entries for this protocol */
 332         rtnl_lock();
 333         for_each_net(net)
 334                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
 335         rtnl_unlock();
 336 }
 337 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
 338
 339 int nf_conntrack_proto_init(void)
 340 {
 341         unsigned int i;
 342         int err;
 343
 344         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
 345         if (err < 0)
 346                 return err;
 347
 348         for (i = 0; i < AF_MAX; i++)
 349                 rcu_assign_pointer(nf_ct_l3protos[i],
 350                                    &nf_conntrack_l3proto_generic);
 351         return 0;
 352 }
 353
 354 void nf_conntrack_proto_fini(void)
 355 {
 356         unsigned int i;
 357
 358         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
 359
 360         /* free l3proto protocol tables */
 361         for (i = 0; i < PF_MAX; i++)
 362                 kfree(nf_ct_protos[i]);
 363 }