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
  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_l4proto *
  77 nf_ct_l4proto_find_get(u_int16_t l3proto, u_int8_t l4proto)
  78 {
  79         struct nf_conntrack_l4proto *p;
  80
  81         rcu_read_lock();
  82         p = __nf_ct_l4proto_find(l3proto, l4proto);
  83         if (!try_module_get(p->me))
  84                 p = &nf_conntrack_l4proto_generic;
  85         rcu_read_unlock();
  86
  87         return p;
  88 }
  89 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
  90
  91 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
  92 {
  93         module_put(p->me);
  94 }
  95 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
  96
  97 struct nf_conntrack_l3proto *
  98 nf_ct_l3proto_find_get(u_int16_t l3proto)
  99 {
 100         struct nf_conntrack_l3proto *p;
 101
 102         rcu_read_lock();
 103         p = __nf_ct_l3proto_find(l3proto);
 104         if (!try_module_get(p->me))
 105                 p = &nf_conntrack_l3proto_generic;
 106         rcu_read_unlock();
 107
 108         return p;
 109 }
 110 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
 111
 112 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
 113 {
 114         module_put(p->me);
 115 }
 116 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
 117
 118 int
 119 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 120 {
 121         int ret;
 122         struct nf_conntrack_l3proto *p;
 123
 124 retry:  p = nf_ct_l3proto_find_get(l3proto);
 125         if (p == &nf_conntrack_l3proto_generic) {
 126                 ret = request_module("nf_conntrack-%d", l3proto);
 127                 if (!ret)
 128                         goto retry;
 129
 130                 return -EPROTOTYPE;
 131         }
 132
 133         return 0;
 134 }
 135 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 136
 137 void nf_ct_l3proto_module_put(unsigned short l3proto)
 138 {
 139         struct nf_conntrack_l3proto *p;
 140
 141         /* rcu_read_lock not necessary since the caller holds a reference */
 142         p = __nf_ct_l3proto_find(l3proto);
 143         module_put(p->me);
 144 }
 145 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 146
 147 static int kill_l3proto(struct nf_conn *i, void *data)
 148 {
 149         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 150 }
 151
 152 static int kill_l4proto(struct nf_conn *i, void *data)
 153 {
 154         struct nf_conntrack_l4proto *l4proto;
 155         l4proto = (struct nf_conntrack_l4proto *)data;
 156         return nf_ct_protonum(i) == l4proto->l4proto &&
 157                nf_ct_l3num(i) == l4proto->l3proto;
 158 }
 159
 160 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 161 {
 162         int err = 0;
 163
 164 #ifdef CONFIG_SYSCTL
 165         if (l3proto->ctl_table != NULL) {
 166                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 167                                             l3proto->ctl_table_path,
 168                                             l3proto->ctl_table, NULL);
 169         }
 170 #endif
 171         return err;
 172 }
 173
 174 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 175 {
 176 #ifdef CONFIG_SYSCTL
 177         if (l3proto->ctl_table_header != NULL)
 178                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 179                                         l3proto->ctl_table, NULL);
 180 #endif
 181 }
 182
 183 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 184 {
 185         int ret = 0;
 186
 187         if (proto->l3proto >= AF_MAX)
 188                 return -EBUSY;
 189
 190         mutex_lock(&nf_ct_proto_mutex);
 191         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 192                 ret = -EBUSY;
 193                 goto out_unlock;
 194         }
 195
 196         ret = nf_ct_l3proto_register_sysctl(proto);
 197         if (ret < 0)
 198                 goto out_unlock;
 199
 200         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 201
 202 out_unlock:
 203         mutex_unlock(&nf_ct_proto_mutex);
 204         return ret;
 205 }
 206 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 207
 208 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 209 {
 210         struct net *net;
 211
 212         BUG_ON(proto->l3proto >= AF_MAX);
 213
 214         mutex_lock(&nf_ct_proto_mutex);
 215         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
 216         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 217                            &nf_conntrack_l3proto_generic);
 218         nf_ct_l3proto_unregister_sysctl(proto);
 219         mutex_unlock(&nf_ct_proto_mutex);
 220
 221         synchronize_rcu();
 222
 223         /* Remove all contrack entries for this protocol */
 224         for_each_net(net)
 225                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
 226 }
 227 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 228
 229 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 230 {
 231         int err = 0;
 232
 233 #ifdef CONFIG_SYSCTL
 234         if (l4proto->ctl_table != NULL) {
 235                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 236                                             nf_net_netfilter_sysctl_path,
 237                                             l4proto->ctl_table,
 238                                             l4proto->ctl_table_users);
 239                 if (err < 0)
 240                         goto out;
 241         }
 242 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 243         if (l4proto->ctl_compat_table != NULL) {
 244                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 245                                             nf_net_ipv4_netfilter_sysctl_path,
 246                                             l4proto->ctl_compat_table, NULL);
 247                 if (err == 0)
 248                         goto out;
 249                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 250                                         l4proto->ctl_table,
 251                                         l4proto->ctl_table_users);
 252         }
 253 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 254 out:
 255 #endif /* CONFIG_SYSCTL */
 256         return err;
 257 }
 258
 259 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 260 {
 261 #ifdef CONFIG_SYSCTL
 262         if (l4proto->ctl_table_header != NULL &&
 263             *l4proto->ctl_table_header != NULL)
 264                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 265                                         l4proto->ctl_table,
 266                                         l4proto->ctl_table_users);
 267 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 268         if (l4proto->ctl_compat_table_header != NULL)
 269                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 270                                         l4proto->ctl_compat_table, NULL);
 271 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 272 #endif /* CONFIG_SYSCTL */
 273 }
 274
 275 /* FIXME: Allow NULL functions and sub in pointers to generic for
 276    them. --RR */
 277 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 278 {
 279         int ret = 0;
 280
 281         if (l4proto->l3proto >= PF_MAX)
 282                 return -EBUSY;
 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 **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                         proto_array[i] = &nf_conntrack_l4proto_generic;
 300                 nf_ct_protos[l4proto->l3proto] = proto_array;
 301         } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
 302                                         &nf_conntrack_l4proto_generic) {
 303                 ret = -EBUSY;
 304                 goto out_unlock;
 305         }
 306
 307         ret = nf_ct_l4proto_register_sysctl(l4proto);
 308         if (ret < 0)
 309                 goto out_unlock;
 310
 311         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 312                            l4proto);
 313
 314 out_unlock:
 315         mutex_unlock(&nf_ct_proto_mutex);
 316         return ret;
 317 }
 318 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 319
 320 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 321 {
 322         struct net *net;
 323
 324         BUG_ON(l4proto->l3proto >= PF_MAX);
 325
 326         mutex_lock(&nf_ct_proto_mutex);
 327         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 328         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 329                            &nf_conntrack_l4proto_generic);
 330         nf_ct_l4proto_unregister_sysctl(l4proto);
 331         mutex_unlock(&nf_ct_proto_mutex);
 332
 333         synchronize_rcu();
 334
 335         /* Remove all contrack entries for this protocol */
 336         for_each_net(net)
 337                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
 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 }