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 **nf_ct_protos[PF_MAX] __read_mostly;
  32 struct nf_conntrack_l3proto *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 */
 121         p = __nf_ct_l3proto_find(l3proto);
 122         module_put(p->me);
 123 }
 124 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 125
 126 static int kill_l3proto(struct nf_conn *i, void *data)
 127 {
 128         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 129 }
 130
 131 static int kill_l4proto(struct nf_conn *i, void *data)
 132 {
 133         struct nf_conntrack_l4proto *l4proto;
 134         l4proto = (struct nf_conntrack_l4proto *)data;
 135         return nf_ct_protonum(i) == l4proto->l4proto &&
 136                nf_ct_l3num(i) == l4proto->l3proto;
 137 }
 138
 139 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 140 {
 141         int err = 0;
 142
 143 #ifdef CONFIG_SYSCTL
 144         if (l3proto->ctl_table != NULL) {
 145                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 146                                             l3proto->ctl_table_path,
 147                                             l3proto->ctl_table, NULL);
 148         }
 149 #endif
 150         return err;
 151 }
 152
 153 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 154 {
 155 #ifdef CONFIG_SYSCTL
 156         if (l3proto->ctl_table_header != NULL)
 157                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 158                                         l3proto->ctl_table, NULL);
 159 #endif
 160 }
 161
 162 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 163 {
 164         int ret = 0;
 165
 166         if (proto->l3proto >= AF_MAX)
 167                 return -EBUSY;
 168
 169         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 170                 return -EINVAL;
 171
 172         mutex_lock(&nf_ct_proto_mutex);
 173         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 174                 ret = -EBUSY;
 175                 goto out_unlock;
 176         }
 177
 178         ret = nf_ct_l3proto_register_sysctl(proto);
 179         if (ret < 0)
 180                 goto out_unlock;
 181
 182         if (proto->nlattr_tuple_size)
 183                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 184
 185         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 186
 187 out_unlock:
 188         mutex_unlock(&nf_ct_proto_mutex);
 189         return ret;
 190 }
 191 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 192
 193 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 194 {
 195         struct net *net;
 196
 197         BUG_ON(proto->l3proto >= AF_MAX);
 198
 199         mutex_lock(&nf_ct_proto_mutex);
 200         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
 201         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 202                            &nf_conntrack_l3proto_generic);
 203         nf_ct_l3proto_unregister_sysctl(proto);
 204         mutex_unlock(&nf_ct_proto_mutex);
 205
 206         synchronize_rcu();
 207
 208         /* Remove all contrack entries for this protocol */
 209         rtnl_lock();
 210         for_each_net(net)
 211                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
 212         rtnl_unlock();
 213 }
 214 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 215
 216 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 217 {
 218         int err = 0;
 219
 220 #ifdef CONFIG_SYSCTL
 221         if (l4proto->ctl_table != NULL) {
 222                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 223                                             nf_net_netfilter_sysctl_path,
 224                                             l4proto->ctl_table,
 225                                             l4proto->ctl_table_users);
 226                 if (err < 0)
 227                         goto out;
 228         }
 229 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 230         if (l4proto->ctl_compat_table != NULL) {
 231                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 232                                             nf_net_ipv4_netfilter_sysctl_path,
 233                                             l4proto->ctl_compat_table, NULL);
 234                 if (err == 0)
 235                         goto out;
 236                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 237                                         l4proto->ctl_table,
 238                                         l4proto->ctl_table_users);
 239         }
 240 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 241 out:
 242 #endif /* CONFIG_SYSCTL */
 243         return err;
 244 }
 245
 246 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 247 {
 248 #ifdef CONFIG_SYSCTL
 249         if (l4proto->ctl_table_header != NULL &&
 250             *l4proto->ctl_table_header != NULL)
 251                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 252                                         l4proto->ctl_table,
 253                                         l4proto->ctl_table_users);
 254 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 255         if (l4proto->ctl_compat_table_header != NULL)
 256                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 257                                         l4proto->ctl_compat_table, NULL);
 258 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 259 #endif /* CONFIG_SYSCTL */
 260 }
 261
 262 /* FIXME: Allow NULL functions and sub in pointers to generic for
 263    them. --RR */
 264 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 265 {
 266         int ret = 0;
 267
 268         if (l4proto->l3proto >= PF_MAX)
 269                 return -EBUSY;
 270
 271         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
 272                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 273                 return -EINVAL;
 274
 275         mutex_lock(&nf_ct_proto_mutex);
 276         if (!nf_ct_protos[l4proto->l3proto]) {
 277                 /* l3proto may be loaded latter. */
 278                 struct nf_conntrack_l4proto **proto_array;
 279                 int i;
 280
 281                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 282                                       sizeof(struct nf_conntrack_l4proto *),
 283                                       GFP_KERNEL);
 284                 if (proto_array == NULL) {
 285                         ret = -ENOMEM;
 286                         goto out_unlock;
 287                 }
 288
 289                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 290                         proto_array[i] = &nf_conntrack_l4proto_generic;
 291                 nf_ct_protos[l4proto->l3proto] = proto_array;
 292         } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
 293                                         &nf_conntrack_l4proto_generic) {
 294                 ret = -EBUSY;
 295                 goto out_unlock;
 296         }
 297
 298         ret = nf_ct_l4proto_register_sysctl(l4proto);
 299         if (ret < 0)
 300                 goto out_unlock;
 301
 302         l4proto->nla_size = 0;
 303         if (l4proto->nlattr_size)
 304                 l4proto->nla_size += l4proto->nlattr_size();
 305         if (l4proto->nlattr_tuple_size)
 306                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 307
 308         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 309                            l4proto);
 310
 311 out_unlock:
 312         mutex_unlock(&nf_ct_proto_mutex);
 313         return ret;
 314 }
 315 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 316
 317 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 318 {
 319         struct net *net;
 320
 321         BUG_ON(l4proto->l3proto >= PF_MAX);
 322
 323         mutex_lock(&nf_ct_proto_mutex);
 324         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 325         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 326                            &nf_conntrack_l4proto_generic);
 327         nf_ct_l4proto_unregister_sysctl(l4proto);
 328         mutex_unlock(&nf_ct_proto_mutex);
 329
 330         synchronize_rcu();
 331
 332         /* Remove all contrack entries for this protocol */
 333         rtnl_lock();
 334         for_each_net(net)
 335                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
 336         rtnl_unlock();
 337 }
 338 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
 339
 340 int nf_conntrack_proto_init(void)
 341 {
 342         unsigned int i;
 343         int err;
 344
 345         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
 346         if (err < 0)
 347                 return err;
 348
 349         for (i = 0; i < AF_MAX; i++)
 350                 rcu_assign_pointer(nf_ct_l3protos[i],
 351                                    &nf_conntrack_l3proto_generic);
 352         return 0;
 353 }
 354
 355 void nf_conntrack_proto_fini(void)
 356 {
 357         unsigned int i;
 358
 359         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
 360
 361         /* free l3proto protocol tables */
 362         for (i = 0; i < PF_MAX; i++)
 363                 kfree(nf_ct_protos[i]);
 364 }