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/slab.h>
  16 #include <linux/mutex.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/stddef.h>
  19 #include <linux/err.h>
  20 #include <linux/percpu.h>
  21 #include <linux/notifier.h>
  22 #include <linux/kernel.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/rtnetlink.h>
  25
  26 #include <net/netfilter/nf_conntrack.h>
  27 #include <net/netfilter/nf_conntrack_l3proto.h>
  28 #include <net/netfilter/nf_conntrack_l4proto.h>
  29 #include <net/netfilter/nf_conntrack_core.h>
  30
  31 static struct nf_conntrack_l4proto __rcu **nf_ct_protos[PF_MAX] __read_mostly;
  32 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX] __read_mostly;
  33 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
  34
  35 static DEFINE_MUTEX(nf_ct_proto_mutex);
  36
  37 #ifdef CONFIG_SYSCTL
  38 static int
  39 nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_path *path,
  40                       struct ctl_table *table, unsigned int *users)
  41 {
  42         if (*header == NULL) {
  43                 *header = register_sysctl_paths(path, table);
  44                 if (*header == NULL)
  45                         return -ENOMEM;
  46         }
  47         if (users != NULL)
  48                 (*users)++;
  49         return 0;
  50 }
  51
  52 static void
  53 nf_ct_unregister_sysctl(struct ctl_table_header **header,
  54                         struct ctl_table *table, unsigned int *users)
  55 {
  56         if (users != NULL && --*users > 0)
  57                 return;
  58
  59         unregister_sysctl_table(*header);
  60         *header = NULL;
  61 }
  62 #endif
  63
  64 struct nf_conntrack_l4proto *
  65 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
  66 {
  67         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
  68                 return &nf_conntrack_l4proto_generic;
  69
  70         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
  71 }
  72 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  73
  74 /* this is guaranteed to always return a valid protocol helper, since
  75  * it falls back to generic_protocol */
  76 struct nf_conntrack_l3proto *
  77 nf_ct_l3proto_find_get(u_int16_t l3proto)
  78 {
  79         struct nf_conntrack_l3proto *p;
  80
  81         rcu_read_lock();
  82         p = __nf_ct_l3proto_find(l3proto);
  83         if (!try_module_get(p->me))
  84                 p = &nf_conntrack_l3proto_generic;
  85         rcu_read_unlock();
  86
  87         return p;
  88 }
  89 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
  90
  91 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
  92 {
  93         module_put(p->me);
  94 }
  95 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
  96
  97 int
  98 nf_ct_l3proto_try_module_get(unsigned short l3proto)
  99 {
 100         int ret;
 101         struct nf_conntrack_l3proto *p;
 102
 103 retry:  p = nf_ct_l3proto_find_get(l3proto);
 104         if (p == &nf_conntrack_l3proto_generic) {
 105                 ret = request_module("nf_conntrack-%d", l3proto);
 106                 if (!ret)
 107                         goto retry;
 108
 109                 return -EPROTOTYPE;
 110         }
 111
 112         return 0;
 113 }
 114 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 115
 116 void nf_ct_l3proto_module_put(unsigned short l3proto)
 117 {
 118         struct nf_conntrack_l3proto *p;
 119
 120         /* rcu_read_lock not necessary since the caller holds a reference, but
 121          * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
 122          */
 123         rcu_read_lock();
 124         p = __nf_ct_l3proto_find(l3proto);
 125         module_put(p->me);
 126         rcu_read_unlock();
 127 }
 128 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 129
 130 static int kill_l3proto(struct nf_conn *i, void *data)
 131 {
 132         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 133 }
 134
 135 static int kill_l4proto(struct nf_conn *i, void *data)
 136 {
 137         struct nf_conntrack_l4proto *l4proto;
 138         l4proto = (struct nf_conntrack_l4proto *)data;
 139         return nf_ct_protonum(i) == l4proto->l4proto &&
 140                nf_ct_l3num(i) == l4proto->l3proto;
 141 }
 142
 143 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 144 {
 145         int err = 0;
 146
 147 #ifdef CONFIG_SYSCTL
 148         if (l3proto->ctl_table != NULL) {
 149                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 150                                             l3proto->ctl_table_path,
 151                                             l3proto->ctl_table, NULL);
 152         }
 153 #endif
 154         return err;
 155 }
 156
 157 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 158 {
 159 #ifdef CONFIG_SYSCTL
 160         if (l3proto->ctl_table_header != NULL)
 161                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 162                                         l3proto->ctl_table, NULL);
 163 #endif
 164 }
 165
 166 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 167 {
 168         int ret = 0;
 169         struct nf_conntrack_l3proto *old;
 170
 171         if (proto->l3proto >= AF_MAX)
 172                 return -EBUSY;
 173
 174         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 175                 return -EINVAL;
 176
 177         mutex_lock(&nf_ct_proto_mutex);
 178         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 179                                         lockdep_is_held(&nf_ct_proto_mutex));
 180         if (old != &nf_conntrack_l3proto_generic) {
 181                 ret = -EBUSY;
 182                 goto out_unlock;
 183         }
 184
 185         ret = nf_ct_l3proto_register_sysctl(proto);
 186         if (ret < 0)
 187                 goto out_unlock;
 188
 189         if (proto->nlattr_tuple_size)
 190                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 191
 192         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 193
 194 out_unlock:
 195         mutex_unlock(&nf_ct_proto_mutex);
 196         return ret;
 197 }
 198 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 199
 200 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 201 {
 202         struct net *net;
 203
 204         BUG_ON(proto->l3proto >= AF_MAX);
 205
 206         mutex_lock(&nf_ct_proto_mutex);
 207         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 208                                          lockdep_is_held(&nf_ct_proto_mutex)
 209                                          ) != proto);
 210         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 211                            &nf_conntrack_l3proto_generic);
 212         nf_ct_l3proto_unregister_sysctl(proto);
 213         mutex_unlock(&nf_ct_proto_mutex);
 214
 215         synchronize_rcu();
 216
 217         /* Remove all contrack entries for this protocol */
 218         rtnl_lock();
 219         for_each_net(net)
 220                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
 221         rtnl_unlock();
 222 }
 223 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 224
 225 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 226 {
 227         int err = 0;
 228
 229 #ifdef CONFIG_SYSCTL
 230         if (l4proto->ctl_table != NULL) {
 231                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 232                                             nf_net_netfilter_sysctl_path,
 233                                             l4proto->ctl_table,
 234                                             l4proto->ctl_table_users);
 235                 if (err < 0)
 236                         goto out;
 237         }
 238 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 239         if (l4proto->ctl_compat_table != NULL) {
 240                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 241                                             nf_net_ipv4_netfilter_sysctl_path,
 242                                             l4proto->ctl_compat_table, NULL);
 243                 if (err == 0)
 244                         goto out;
 245                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 246                                         l4proto->ctl_table,
 247                                         l4proto->ctl_table_users);
 248         }
 249 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 250 out:
 251 #endif /* CONFIG_SYSCTL */
 252         return err;
 253 }
 254
 255 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 256 {
 257 #ifdef CONFIG_SYSCTL
 258         if (l4proto->ctl_table_header != NULL &&
 259             *l4proto->ctl_table_header != NULL)
 260                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 261                                         l4proto->ctl_table,
 262                                         l4proto->ctl_table_users);
 263 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 264         if (l4proto->ctl_compat_table_header != NULL)
 265                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 266                                         l4proto->ctl_compat_table, NULL);
 267 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 268 #endif /* CONFIG_SYSCTL */
 269 }
 270
 271 /* FIXME: Allow NULL functions and sub in pointers to generic for
 272    them. --RR */
 273 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 274 {
 275         int ret = 0;
 276
 277         if (l4proto->l3proto >= PF_MAX)
 278                 return -EBUSY;
 279
 280         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
 281                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 282                 return -EINVAL;
 283
 284         mutex_lock(&nf_ct_proto_mutex);
 285         if (!nf_ct_protos[l4proto->l3proto]) {
 286                 /* l3proto may be loaded latter. */
 287                 struct nf_conntrack_l4proto __rcu **proto_array;
 288                 int i;
 289
 290                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 291                                       sizeof(struct nf_conntrack_l4proto *),
 292                                       GFP_KERNEL);
 293                 if (proto_array == NULL) {
 294                         ret = -ENOMEM;
 295                         goto out_unlock;
 296                 }
 297
 298                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 299                         RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
 300
 301                 /* Before making proto_array visible to lockless readers,
 302                  * we must make sure its content is committed to memory.
 303                  */
 304                 smp_wmb();
 305
 306                 nf_ct_protos[l4proto->l3proto] = proto_array;
 307         } else if (rcu_dereference_protected(
 308                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 309                         lockdep_is_held(&nf_ct_proto_mutex)
 310                         ) != &nf_conntrack_l4proto_generic) {
 311                 ret = -EBUSY;
 312                 goto out_unlock;
 313         }
 314
 315         ret = nf_ct_l4proto_register_sysctl(l4proto);
 316         if (ret < 0)
 317                 goto out_unlock;
 318
 319         l4proto->nla_size = 0;
 320         if (l4proto->nlattr_size)
 321                 l4proto->nla_size += l4proto->nlattr_size();
 322         if (l4proto->nlattr_tuple_size)
 323                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 324
 325         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 326                            l4proto);
 327
 328 out_unlock:
 329         mutex_unlock(&nf_ct_proto_mutex);
 330         return ret;
 331 }
 332 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 333
 334 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 335 {
 336         struct net *net;
 337
 338         BUG_ON(l4proto->l3proto >= PF_MAX);
 339
 340         mutex_lock(&nf_ct_proto_mutex);
 341         BUG_ON(rcu_dereference_protected(
 342                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 343                         lockdep_is_held(&nf_ct_proto_mutex)
 344                         ) != l4proto);
 345         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 346                            &nf_conntrack_l4proto_generic);
 347         nf_ct_l4proto_unregister_sysctl(l4proto);
 348         mutex_unlock(&nf_ct_proto_mutex);
 349
 350         synchronize_rcu();
 351
 352         /* Remove all contrack entries for this protocol */
 353         rtnl_lock();
 354         for_each_net(net)
 355                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
 356         rtnl_unlock();
 357 }
 358 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
 359
 360 int nf_conntrack_proto_init(void)
 361 {
 362         unsigned int i;
 363         int err;
 364
 365         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
 366         if (err < 0)
 367                 return err;
 368
 369         for (i = 0; i < AF_MAX; i++)
 370                 rcu_assign_pointer(nf_ct_l3protos[i],
 371                                    &nf_conntrack_l3proto_generic);
 372         return 0;
 373 }
 374
 375 void nf_conntrack_proto_fini(void)
 376 {
 377         unsigned int i;
 378
 379         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
 380
 381         /* free l3proto protocol tables */
 382         for (i = 0; i < PF_MAX; i++)
 383                 kfree(nf_ct_protos[i]);
 384 }