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         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 171                 return -EINVAL;
 172
 173         mutex_lock(&nf_ct_proto_mutex);
 174         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 175                 ret = -EBUSY;
 176                 goto out_unlock;
 177         }
 178
 179         ret = nf_ct_l3proto_register_sysctl(proto);
 180         if (ret < 0)
 181                 goto out_unlock;
 182
 183         if (proto->nlattr_tuple_size)
 184                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 185
 186         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 187
 188 out_unlock:
 189         mutex_unlock(&nf_ct_proto_mutex);
 190         return ret;
 191 }
 192 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 193
 194 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 195 {
 196         struct net *net;
 197
 198         BUG_ON(proto->l3proto >= AF_MAX);
 199
 200         mutex_lock(&nf_ct_proto_mutex);
 201         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
 202         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 203                            &nf_conntrack_l3proto_generic);
 204         nf_ct_l3proto_unregister_sysctl(proto);
 205         mutex_unlock(&nf_ct_proto_mutex);
 206
 207         synchronize_rcu();
 208
 209         /* Remove all contrack entries for this protocol */
 210         rtnl_lock();
 211         for_each_net(net)
 212                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
 213         rtnl_unlock();
 214 }
 215 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 216
 217 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 218 {
 219         int err = 0;
 220
 221 #ifdef CONFIG_SYSCTL
 222         if (l4proto->ctl_table != NULL) {
 223                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 224                                             nf_net_netfilter_sysctl_path,
 225                                             l4proto->ctl_table,
 226                                             l4proto->ctl_table_users);
 227                 if (err < 0)
 228                         goto out;
 229         }
 230 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 231         if (l4proto->ctl_compat_table != NULL) {
 232                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 233                                             nf_net_ipv4_netfilter_sysctl_path,
 234                                             l4proto->ctl_compat_table, NULL);
 235                 if (err == 0)
 236                         goto out;
 237                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 238                                         l4proto->ctl_table,
 239                                         l4proto->ctl_table_users);
 240         }
 241 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 242 out:
 243 #endif /* CONFIG_SYSCTL */
 244         return err;
 245 }
 246
 247 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 248 {
 249 #ifdef CONFIG_SYSCTL
 250         if (l4proto->ctl_table_header != NULL &&
 251             *l4proto->ctl_table_header != NULL)
 252                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 253                                         l4proto->ctl_table,
 254                                         l4proto->ctl_table_users);
 255 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 256         if (l4proto->ctl_compat_table_header != NULL)
 257                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 258                                         l4proto->ctl_compat_table, NULL);
 259 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 260 #endif /* CONFIG_SYSCTL */
 261 }
 262
 263 /* FIXME: Allow NULL functions and sub in pointers to generic for
 264    them. --RR */
 265 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 266 {
 267         int ret = 0;
 268
 269         if (l4proto->l3proto >= PF_MAX)
 270                 return -EBUSY;
 271
 272         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
 273                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 274                 return -EINVAL;
 275
 276         mutex_lock(&nf_ct_proto_mutex);
 277         if (!nf_ct_protos[l4proto->l3proto]) {
 278                 /* l3proto may be loaded latter. */
 279                 struct nf_conntrack_l4proto **proto_array;
 280                 int i;
 281
 282                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 283                                       sizeof(struct nf_conntrack_l4proto *),
 284                                       GFP_KERNEL);
 285                 if (proto_array == NULL) {
 286                         ret = -ENOMEM;
 287                         goto out_unlock;
 288                 }
 289
 290                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 291                         proto_array[i] = &nf_conntrack_l4proto_generic;
 292                 nf_ct_protos[l4proto->l3proto] = proto_array;
 293         } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
 294                                         &nf_conntrack_l4proto_generic) {
 295                 ret = -EBUSY;
 296                 goto out_unlock;
 297         }
 298
 299         ret = nf_ct_l4proto_register_sysctl(l4proto);
 300         if (ret < 0)
 301                 goto out_unlock;
 302
 303         l4proto->nla_size = 0;
 304         if (l4proto->nlattr_size)
 305                 l4proto->nla_size += l4proto->nlattr_size();
 306         if (l4proto->nlattr_tuple_size)
 307                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 308
 309         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 310                            l4proto);
 311
 312 out_unlock:
 313         mutex_unlock(&nf_ct_proto_mutex);
 314         return ret;
 315 }
 316 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 317
 318 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 319 {
 320         struct net *net;
 321
 322         BUG_ON(l4proto->l3proto >= PF_MAX);
 323
 324         mutex_lock(&nf_ct_proto_mutex);
 325         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 326         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 327                            &nf_conntrack_l4proto_generic);
 328         nf_ct_l4proto_unregister_sysctl(l4proto);
 329         mutex_unlock(&nf_ct_proto_mutex);
 330
 331         synchronize_rcu();
 332
 333         /* Remove all contrack entries for this protocol */
 334         rtnl_lock();
 335         for_each_net(net)
 336                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
 337         rtnl_unlock();
 338 }
 339 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
 340
 341 int nf_conntrack_proto_init(void)
 342 {
 343         unsigned int i;
 344         int err;
 345
 346         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
 347         if (err < 0)
 348                 return err;
 349
 350         for (i = 0; i < AF_MAX; i++)
 351                 rcu_assign_pointer(nf_ct_l3protos[i],
 352                                    &nf_conntrack_l3proto_generic);
 353         return 0;
 354 }
 355
 356 void nf_conntrack_proto_fini(void)
 357 {
 358         unsigned int i;
 359
 360         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
 361
 362         /* free l3proto protocol tables */
 363         for (i = 0; i < PF_MAX; i++)
 364                 kfree(nf_ct_protos[i]);
 365 }