git.oblomov.eu Git - linux-2.6/blob - 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/skbuff.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/stddef.h>
  19 #include <linux/err.h>
  20 #include <linux/percpu.h>
  21 #include <linux/moduleparam.h>
  22 #include <linux/notifier.h>
  23 #include <linux/kernel.h>
  24 #include <linux/netdevice.h>
  25 #include <linux/rtnetlink.h>
  26
  27 #include <net/netfilter/nf_conntrack.h>
  28 #include <net/netfilter/nf_conntrack_l3proto.h>
  29 #include <net/netfilter/nf_conntrack_l4proto.h>
  30 #include <net/netfilter/nf_conntrack_core.h>
  31
  32 static struct nf_conntrack_l4proto **nf_ct_protos[PF_MAX] __read_mostly;
  33 struct nf_conntrack_l3proto *nf_ct_l3protos[AF_MAX] __read_mostly;
  34 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
  35
  36 static DEFINE_MUTEX(nf_ct_proto_mutex);
  37
  38 #ifdef CONFIG_SYSCTL
  39 static int
  40 nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_path *path,
  41                       struct ctl_table *table, unsigned int *users)
  42 {
  43         if (*header == NULL) {
  44                 *header = register_sysctl_paths(path, table);
  45                 if (*header == NULL)
  46                         return -ENOMEM;
  47         }
  48         if (users != NULL)
  49                 (*users)++;
  50         return 0;
  51 }
  52
  53 static void
  54 nf_ct_unregister_sysctl(struct ctl_table_header **header,
  55                         struct ctl_table *table, unsigned int *users)
  56 {
  57         if (users != NULL && --*users > 0)
  58                 return;
  59
  60         unregister_sysctl_table(*header);
  61         *header = NULL;
  62 }
  63 #endif
  64
  65 struct nf_conntrack_l4proto *
  66 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
  67 {
  68         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
  69                 return &nf_conntrack_l4proto_generic;
  70
  71         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
  72 }
  73 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  74
  75 /* this is guaranteed to always return a valid protocol helper, since
  76  * it falls back to generic_protocol */
  77 struct nf_conntrack_l3proto *
  78 nf_ct_l3proto_find_get(u_int16_t l3proto)
  79 {
  80         struct nf_conntrack_l3proto *p;
  81
  82         rcu_read_lock();
  83         p = __nf_ct_l3proto_find(l3proto);
  84         if (!try_module_get(p->me))
  85                 p = &nf_conntrack_l3proto_generic;
  86         rcu_read_unlock();
  87
  88         return p;
  89 }
  90 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
  91
  92 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
  93 {
  94         module_put(p->me);
  95 }
  96 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
  97
  98 int
  99 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 100 {
 101         int ret;
 102         struct nf_conntrack_l3proto *p;
 103
 104 retry:  p = nf_ct_l3proto_find_get(l3proto);
 105         if (p == &nf_conntrack_l3proto_generic) {
 106                 ret = request_module("nf_conntrack-%d", l3proto);
 107                 if (!ret)
 108                         goto retry;
 109
 110                 return -EPROTOTYPE;
 111         }
 112
 113         return 0;
 114 }
 115 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 116
 117 void nf_ct_l3proto_module_put(unsigned short l3proto)
 118 {
 119         struct nf_conntrack_l3proto *p;
 120
 121         /* rcu_read_lock not necessary since the caller holds a reference */
 122         p = __nf_ct_l3proto_find(l3proto);
 123         module_put(p->me);
 124 }
 125 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 126
 127 static int kill_l3proto(struct nf_conn *i, void *data)
 128 {
 129         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 130 }
 131
 132 static int kill_l4proto(struct nf_conn *i, void *data)
 133 {
 134         struct nf_conntrack_l4proto *l4proto;
 135         l4proto = (struct nf_conntrack_l4proto *)data;
 136         return nf_ct_protonum(i) == l4proto->l4proto &&
 137                nf_ct_l3num(i) == l4proto->l3proto;
 138 }
 139
 140 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 141 {
 142         int err = 0;
 143
 144 #ifdef CONFIG_SYSCTL
 145         if (l3proto->ctl_table != NULL) {
 146                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 147                                             l3proto->ctl_table_path,
 148                                             l3proto->ctl_table, NULL);
 149         }
 150 #endif
 151         return err;
 152 }
 153
 154 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 155 {
 156 #ifdef CONFIG_SYSCTL
 157         if (l3proto->ctl_table_header != NULL)
 158                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 159                                         l3proto->ctl_table, NULL);
 160 #endif
 161 }
 162
 163 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 164 {
 165         int ret = 0;
 166
 167         if (proto->l3proto >= AF_MAX)
 168                 return -EBUSY;
 169
 170         mutex_lock(&nf_ct_proto_mutex);
 171         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 172                 ret = -EBUSY;
 173                 goto out_unlock;
 174         }
 175
 176         ret = nf_ct_l3proto_register_sysctl(proto);
 177         if (ret < 0)
 178                 goto out_unlock;
 179
 180         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 181
 182 out_unlock:
 183         mutex_unlock(&nf_ct_proto_mutex);
 184         return ret;
 185 }
 186 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 187
 188 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 189 {
 190         struct net *net;
 191
 192         BUG_ON(proto->l3proto >= AF_MAX);
 193
 194         mutex_lock(&nf_ct_proto_mutex);
 195         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
 196         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 197                            &nf_conntrack_l3proto_generic);
 198         nf_ct_l3proto_unregister_sysctl(proto);
 199         mutex_unlock(&nf_ct_proto_mutex);
 200
 201         synchronize_rcu();
 202
 203         /* Remove all contrack entries for this protocol */
 204         rtnl_lock();
 205         for_each_net(net)
 206                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
 207         rtnl_unlock();
 208 }
 209 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 210
 211 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 212 {
 213         int err = 0;
 214
 215 #ifdef CONFIG_SYSCTL
 216         if (l4proto->ctl_table != NULL) {
 217                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 218                                             nf_net_netfilter_sysctl_path,
 219                                             l4proto->ctl_table,
 220                                             l4proto->ctl_table_users);
 221                 if (err < 0)
 222                         goto out;
 223         }
 224 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 225         if (l4proto->ctl_compat_table != NULL) {
 226                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 227                                             nf_net_ipv4_netfilter_sysctl_path,
 228                                             l4proto->ctl_compat_table, NULL);
 229                 if (err == 0)
 230                         goto out;
 231                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 232                                         l4proto->ctl_table,
 233                                         l4proto->ctl_table_users);
 234         }
 235 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 236 out:
 237 #endif /* CONFIG_SYSCTL */
 238         return err;
 239 }
 240
 241 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 242 {
 243 #ifdef CONFIG_SYSCTL
 244         if (l4proto->ctl_table_header != NULL &&
 245             *l4proto->ctl_table_header != NULL)
 246                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 247                                         l4proto->ctl_table,
 248                                         l4proto->ctl_table_users);
 249 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 250         if (l4proto->ctl_compat_table_header != NULL)
 251                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 252                                         l4proto->ctl_compat_table, NULL);
 253 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 254 #endif /* CONFIG_SYSCTL */
 255 }
 256
 257 /* FIXME: Allow NULL functions and sub in pointers to generic for
 258    them. --RR */
 259 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 260 {
 261         int ret = 0;
 262
 263         if (l4proto->l3proto >= PF_MAX)
 264                 return -EBUSY;
 265
 266         mutex_lock(&nf_ct_proto_mutex);
 267         if (!nf_ct_protos[l4proto->l3proto]) {
 268                 /* l3proto may be loaded latter. */
 269                 struct nf_conntrack_l4proto **proto_array;
 270                 int i;
 271
 272                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 273                                       sizeof(struct nf_conntrack_l4proto *),
 274                                       GFP_KERNEL);
 275                 if (proto_array == NULL) {
 276                         ret = -ENOMEM;
 277                         goto out_unlock;
 278                 }
 279
 280                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 281                         proto_array[i] = &nf_conntrack_l4proto_generic;
 282                 nf_ct_protos[l4proto->l3proto] = proto_array;
 283         } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
 284                                         &nf_conntrack_l4proto_generic) {
 285                 ret = -EBUSY;
 286                 goto out_unlock;
 287         }
 288
 289         ret = nf_ct_l4proto_register_sysctl(l4proto);
 290         if (ret < 0)
 291                 goto out_unlock;
 292
 293         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 294                            l4proto);
 295
 296 out_unlock:
 297         mutex_unlock(&nf_ct_proto_mutex);
 298         return ret;
 299 }
 300 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 301
 302 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 303 {
 304         struct net *net;
 305
 306         BUG_ON(l4proto->l3proto >= PF_MAX);
 307
 308         mutex_lock(&nf_ct_proto_mutex);
 309         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 310         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 311                            &nf_conntrack_l4proto_generic);
 312         nf_ct_l4proto_unregister_sysctl(l4proto);
 313         mutex_unlock(&nf_ct_proto_mutex);
 314
 315         synchronize_rcu();
 316
 317         /* Remove all contrack entries for this protocol */
 318         rtnl_lock();
 319         for_each_net(net)
 320                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
 321         rtnl_unlock();
 322 }
 323 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
 324
 325 int nf_conntrack_proto_init(void)
 326 {
 327         unsigned int i;
 328         int err;
 329
 330         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
 331         if (err < 0)
 332                 return err;
 333
 334         for (i = 0; i < AF_MAX; i++)
 335                 rcu_assign_pointer(nf_ct_l3protos[i],
 336                                    &nf_conntrack_l3proto_generic);
 337         return 0;
 338 }
 339
 340 void nf_conntrack_proto_fini(void)
 341 {
 342         unsigned int i;
 343
 344         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
 345
 346         /* free l3proto protocol tables */
 347         for (i = 0; i < PF_MAX; i++)
 348                 kfree(nf_ct_protos[i]);
 349 }