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 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_table *path,
  40                       struct ctl_table *table, unsigned int *users)
  41 {
  42         if (*header == NULL) {
  43                 *header = nf_register_sysctl_table(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         nf_unregister_sysctl_table(*header, table);
  59         *header = NULL;
  60 }
  61 #endif
  62
  63 struct nf_conntrack_l4proto *
  64 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
  65 {
  66         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
  67                 return &nf_conntrack_l4proto_generic;
  68
  69         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
  70 }
  71 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  72
  73 /* this is guaranteed to always return a valid protocol helper, since
  74  * it falls back to generic_protocol */
  75 struct nf_conntrack_l4proto *
  76 nf_ct_l4proto_find_get(u_int16_t l3proto, u_int8_t l4proto)
  77 {
  78         struct nf_conntrack_l4proto *p;
  79
  80         rcu_read_lock();
  81         p = __nf_ct_l4proto_find(l3proto, l4proto);
  82         if (!try_module_get(p->me))
  83                 p = &nf_conntrack_l4proto_generic;
  84         rcu_read_unlock();
  85
  86         return p;
  87 }
  88 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
  89
  90 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
  91 {
  92         module_put(p->me);
  93 }
  94 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
  95
  96 struct nf_conntrack_l3proto *
  97 nf_ct_l3proto_find_get(u_int16_t l3proto)
  98 {
  99         struct nf_conntrack_l3proto *p;
 100
 101         rcu_read_lock();
 102         p = __nf_ct_l3proto_find(l3proto);
 103         if (!try_module_get(p->me))
 104                 p = &nf_conntrack_l3proto_generic;
 105         rcu_read_unlock();
 106
 107         return p;
 108 }
 109 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
 110
 111 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
 112 {
 113         module_put(p->me);
 114 }
 115 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
 116
 117 int
 118 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 119 {
 120         int ret;
 121         struct nf_conntrack_l3proto *p;
 122
 123 retry:  p = nf_ct_l3proto_find_get(l3proto);
 124         if (p == &nf_conntrack_l3proto_generic) {
 125                 ret = request_module("nf_conntrack-%d", l3proto);
 126                 if (!ret)
 127                         goto retry;
 128
 129                 return -EPROTOTYPE;
 130         }
 131
 132         return 0;
 133 }
 134 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 135
 136 void nf_ct_l3proto_module_put(unsigned short l3proto)
 137 {
 138         struct nf_conntrack_l3proto *p;
 139
 140         /* rcu_read_lock not necessary since the caller holds a reference */
 141         p = __nf_ct_l3proto_find(l3proto);
 142         module_put(p->me);
 143 }
 144 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 145
 146 static int kill_l3proto(struct nf_conn *i, void *data)
 147 {
 148         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
 149                         ((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 (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum ==
 157                         l4proto->l4proto) &&
 158                (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
 159                         l4proto->l3proto);
 160 }
 161
 162 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 163 {
 164         int err = 0;
 165
 166 #ifdef CONFIG_SYSCTL
 167         if (l3proto->ctl_table != NULL) {
 168                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 169                                             l3proto->ctl_table_path,
 170                                             l3proto->ctl_table, NULL);
 171         }
 172 #endif
 173         return err;
 174 }
 175
 176 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 177 {
 178 #ifdef CONFIG_SYSCTL
 179         if (l3proto->ctl_table_header != NULL)
 180                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 181                                         l3proto->ctl_table, NULL);
 182 #endif
 183 }
 184
 185 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 186 {
 187         int ret = 0;
 188
 189         if (proto->l3proto >= AF_MAX)
 190                 return -EBUSY;
 191
 192         mutex_lock(&nf_ct_proto_mutex);
 193         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 194                 ret = -EBUSY;
 195                 goto out_unlock;
 196         }
 197
 198         ret = nf_ct_l3proto_register_sysctl(proto);
 199         if (ret < 0)
 200                 goto out_unlock;
 201
 202         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 203
 204 out_unlock:
 205         mutex_unlock(&nf_ct_proto_mutex);
 206         return ret;
 207 }
 208 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 209
 210 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 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         nf_ct_iterate_cleanup(kill_l3proto, proto);
 225 }
 226 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 227
 228 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 229 {
 230         int err = 0;
 231
 232 #ifdef CONFIG_SYSCTL
 233         if (l4proto->ctl_table != NULL) {
 234                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 235                                             nf_net_netfilter_sysctl_path,
 236                                             l4proto->ctl_table,
 237                                             l4proto->ctl_table_users);
 238                 if (err < 0)
 239                         goto out;
 240         }
 241 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 242         if (l4proto->ctl_compat_table != NULL) {
 243                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 244                                             nf_net_ipv4_netfilter_sysctl_path,
 245                                             l4proto->ctl_compat_table, NULL);
 246                 if (err == 0)
 247                         goto out;
 248                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 249                                         l4proto->ctl_table,
 250                                         l4proto->ctl_table_users);
 251         }
 252 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 253 out:
 254 #endif /* CONFIG_SYSCTL */
 255         return err;
 256 }
 257
 258 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 259 {
 260 #ifdef CONFIG_SYSCTL
 261         if (l4proto->ctl_table_header != NULL &&
 262             *l4proto->ctl_table_header != NULL)
 263                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 264                                         l4proto->ctl_table,
 265                                         l4proto->ctl_table_users);
 266 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 267         if (l4proto->ctl_compat_table_header != NULL)
 268                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 269                                         l4proto->ctl_compat_table, NULL);
 270 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 271 #endif /* CONFIG_SYSCTL */
 272 }
 273
 274 /* FIXME: Allow NULL functions and sub in pointers to generic for
 275    them. --RR */
 276 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 277 {
 278         int ret = 0;
 279
 280         if (l4proto->l3proto >= PF_MAX)
 281                 return -EBUSY;
 282
 283         mutex_lock(&nf_ct_proto_mutex);
 284 retry:
 285         if (nf_ct_protos[l4proto->l3proto]) {
 286                 if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
 287                                 != &nf_conntrack_l4proto_generic) {
 288                         ret = -EBUSY;
 289                         goto out_unlock;
 290                 }
 291         } else {
 292                 /* l3proto may be loaded latter. */
 293                 struct nf_conntrack_l4proto **proto_array;
 294                 int i;
 295
 296                 proto_array = (struct nf_conntrack_l4proto **)
 297                                 kmalloc(MAX_NF_CT_PROTO *
 298                                          sizeof(struct nf_conntrack_l4proto *),
 299                                         GFP_KERNEL);
 300                 if (proto_array == NULL) {
 301                         ret = -ENOMEM;
 302                         goto out_unlock;
 303                 }
 304                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 305                         proto_array[i] = &nf_conntrack_l4proto_generic;
 306
 307                 if (nf_ct_protos[l4proto->l3proto])
 308                         /* bad timing, but no problem */
 309                         kfree(proto_array);
 310                 else
 311                         nf_ct_protos[l4proto->l3proto] = proto_array;
 312
 313                 /*
 314                  * Just once because array is never freed until unloading
 315                  * nf_conntrack.ko
 316                  */
 317                 goto retry;
 318         }
 319
 320         ret = nf_ct_l4proto_register_sysctl(l4proto);
 321         if (ret < 0)
 322                 goto out_unlock;
 323
 324         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto], l4proto);
 325
 326 out_unlock:
 327         mutex_unlock(&nf_ct_proto_mutex);
 328         return ret;
 329 }
 330 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 331
 332 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 333 {
 334         BUG_ON(l4proto->l3proto >= PF_MAX);
 335
 336         mutex_lock(&nf_ct_proto_mutex);
 337         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 338         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 339                            &nf_conntrack_l4proto_generic);
 340         nf_ct_l4proto_unregister_sysctl(l4proto);
 341         mutex_unlock(&nf_ct_proto_mutex);
 342
 343         synchronize_rcu();
 344
 345         /* Remove all contrack entries for this protocol */
 346         nf_ct_iterate_cleanup(kill_l4proto, l4proto);
 347 }
 348 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
 349
 350 int nf_conntrack_proto_init(void)
 351 {
 352         unsigned int i;
 353         int err;
 354
 355         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
 356         if (err < 0)
 357                 return err;
 358
 359         for (i = 0; i < AF_MAX; i++)
 360                 rcu_assign_pointer(nf_ct_l3protos[i],
 361                                    &nf_conntrack_l3proto_generic);
 362         return 0;
 363 }
 364
 365 void nf_conntrack_proto_fini(void)
 366 {
 367         unsigned int i;
 368
 369         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
 370
 371         /* free l3proto protocol tables */
 372         for (i = 0; i < PF_MAX; i++)
 373                 kfree(nf_ct_protos[i]);
 374 }