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 #ifdef CONFIG_SYSCTL
  36 static DEFINE_MUTEX(nf_ct_proto_sysctl_mutex);
  37
  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 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         preempt_disable();
  81         p = __nf_ct_l4proto_find(l3proto, l4proto);
  82         if (!try_module_get(p->me))
  83                 p = &nf_conntrack_l4proto_generic;
  84         preempt_enable();
  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         preempt_disable();
 102         p = __nf_ct_l3proto_find(l3proto);
 103         if (!try_module_get(p->me))
 104                 p = &nf_conntrack_l3proto_generic;
 105         preempt_enable();
 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         preempt_disable();
 141         p = __nf_ct_l3proto_find(l3proto);
 142         preempt_enable();
 143
 144         module_put(p->me);
 145 }
 146 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 147
 148 static int kill_l3proto(struct nf_conn *i, void *data)
 149 {
 150         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
 151                         ((struct nf_conntrack_l3proto *)data)->l3proto);
 152 }
 153
 154 static int kill_l4proto(struct nf_conn *i, void *data)
 155 {
 156         struct nf_conntrack_l4proto *l4proto;
 157         l4proto = (struct nf_conntrack_l4proto *)data;
 158         return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum ==
 159                         l4proto->l4proto) &&
 160                (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
 161                         l4proto->l3proto);
 162 }
 163
 164 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 165 {
 166         int err = 0;
 167
 168 #ifdef CONFIG_SYSCTL
 169         mutex_lock(&nf_ct_proto_sysctl_mutex);
 170         if (l3proto->ctl_table != NULL) {
 171                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 172                                             l3proto->ctl_table_path,
 173                                             l3proto->ctl_table, NULL);
 174         }
 175         mutex_unlock(&nf_ct_proto_sysctl_mutex);
 176 #endif
 177         return err;
 178 }
 179
 180 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 181 {
 182 #ifdef CONFIG_SYSCTL
 183         mutex_lock(&nf_ct_proto_sysctl_mutex);
 184         if (l3proto->ctl_table_header != NULL)
 185                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 186                                         l3proto->ctl_table, NULL);
 187         mutex_unlock(&nf_ct_proto_sysctl_mutex);
 188 #endif
 189 }
 190
 191 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 192 {
 193         int ret = 0;
 194
 195         if (proto->l3proto >= AF_MAX) {
 196                 ret = -EBUSY;
 197                 goto out;
 198         }
 199
 200         write_lock_bh(&nf_conntrack_lock);
 201         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 202                 ret = -EBUSY;
 203                 goto out_unlock;
 204         }
 205         nf_ct_l3protos[proto->l3proto] = proto;
 206         write_unlock_bh(&nf_conntrack_lock);
 207
 208         ret = nf_ct_l3proto_register_sysctl(proto);
 209         if (ret < 0)
 210                 nf_conntrack_l3proto_unregister(proto);
 211         return ret;
 212
 213 out_unlock:
 214         write_unlock_bh(&nf_conntrack_lock);
 215 out:
 216         return ret;
 217 }
 218 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 219
 220 int nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 221 {
 222         int ret = 0;
 223
 224         if (proto->l3proto >= AF_MAX) {
 225                 ret = -EBUSY;
 226                 goto out;
 227         }
 228
 229         write_lock_bh(&nf_conntrack_lock);
 230         if (nf_ct_l3protos[proto->l3proto] != proto) {
 231                 write_unlock_bh(&nf_conntrack_lock);
 232                 ret = -EBUSY;
 233                 goto out;
 234         }
 235
 236         nf_ct_l3protos[proto->l3proto] = &nf_conntrack_l3proto_generic;
 237         write_unlock_bh(&nf_conntrack_lock);
 238
 239         nf_ct_l3proto_unregister_sysctl(proto);
 240
 241         /* Somebody could be still looking at the proto in bh. */
 242         synchronize_net();
 243
 244         /* Remove all contrack entries for this protocol */
 245         nf_ct_iterate_cleanup(kill_l3proto, proto);
 246
 247 out:
 248         return ret;
 249 }
 250 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 251
 252 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 253 {
 254         int err = 0;
 255
 256 #ifdef CONFIG_SYSCTL
 257         mutex_lock(&nf_ct_proto_sysctl_mutex);
 258         if (l4proto->ctl_table != NULL) {
 259                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 260                                             nf_net_netfilter_sysctl_path,
 261                                             l4proto->ctl_table,
 262                                             l4proto->ctl_table_users);
 263                 if (err < 0)
 264                         goto out;
 265         }
 266 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 267         if (l4proto->ctl_compat_table != NULL) {
 268                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 269                                             nf_net_ipv4_netfilter_sysctl_path,
 270                                             l4proto->ctl_compat_table, NULL);
 271                 if (err == 0)
 272                         goto out;
 273                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 274                                         l4proto->ctl_table,
 275                                         l4proto->ctl_table_users);
 276         }
 277 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 278 out:
 279         mutex_unlock(&nf_ct_proto_sysctl_mutex);
 280 #endif /* CONFIG_SYSCTL */
 281         return err;
 282 }
 283
 284 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 285 {
 286 #ifdef CONFIG_SYSCTL
 287         mutex_lock(&nf_ct_proto_sysctl_mutex);
 288         if (l4proto->ctl_table_header != NULL &&
 289             *l4proto->ctl_table_header != NULL)
 290                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 291                                         l4proto->ctl_table,
 292                                         l4proto->ctl_table_users);
 293 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 294         if (l4proto->ctl_compat_table_header != NULL)
 295                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 296                                         l4proto->ctl_compat_table, NULL);
 297 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 298         mutex_unlock(&nf_ct_proto_sysctl_mutex);
 299 #endif /* CONFIG_SYSCTL */
 300 }
 301
 302 /* FIXME: Allow NULL functions and sub in pointers to generic for
 303    them. --RR */
 304 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 305 {
 306         int ret = 0;
 307
 308         if (l4proto->l3proto >= PF_MAX) {
 309                 ret = -EBUSY;
 310                 goto out;
 311         }
 312
 313         if (l4proto == &nf_conntrack_l4proto_generic)
 314                 return nf_ct_l4proto_register_sysctl(l4proto);
 315
 316 retry:
 317         write_lock_bh(&nf_conntrack_lock);
 318         if (nf_ct_protos[l4proto->l3proto]) {
 319                 if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
 320                                 != &nf_conntrack_l4proto_generic) {
 321                         ret = -EBUSY;
 322                         goto out_unlock;
 323                 }
 324         } else {
 325                 /* l3proto may be loaded latter. */
 326                 struct nf_conntrack_l4proto **proto_array;
 327                 int i;
 328
 329                 write_unlock_bh(&nf_conntrack_lock);
 330
 331                 proto_array = (struct nf_conntrack_l4proto **)
 332                                 kmalloc(MAX_NF_CT_PROTO *
 333                                          sizeof(struct nf_conntrack_l4proto *),
 334                                         GFP_KERNEL);
 335                 if (proto_array == NULL) {
 336                         ret = -ENOMEM;
 337                         goto out;
 338                 }
 339                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 340                         proto_array[i] = &nf_conntrack_l4proto_generic;
 341
 342                 write_lock_bh(&nf_conntrack_lock);
 343                 if (nf_ct_protos[l4proto->l3proto]) {
 344                         /* bad timing, but no problem */
 345                         write_unlock_bh(&nf_conntrack_lock);
 346                         kfree(proto_array);
 347                 } else {
 348                         nf_ct_protos[l4proto->l3proto] = proto_array;
 349                         write_unlock_bh(&nf_conntrack_lock);
 350                 }
 351
 352                 /*
 353                  * Just once because array is never freed until unloading
 354                  * nf_conntrack.ko
 355                  */
 356                 goto retry;
 357         }
 358
 359         nf_ct_protos[l4proto->l3proto][l4proto->l4proto] = l4proto;
 360         write_unlock_bh(&nf_conntrack_lock);
 361
 362         ret = nf_ct_l4proto_register_sysctl(l4proto);
 363         if (ret < 0)
 364                 nf_conntrack_l4proto_unregister(l4proto);
 365         return ret;
 366
 367 out_unlock:
 368         write_unlock_bh(&nf_conntrack_lock);
 369 out:
 370         return ret;
 371 }
 372 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 373
 374 int nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 375 {
 376         int ret = 0;
 377
 378         if (l4proto->l3proto >= PF_MAX) {
 379                 ret = -EBUSY;
 380                 goto out;
 381         }
 382
 383         if (l4proto == &nf_conntrack_l4proto_generic) {
 384                 nf_ct_l4proto_unregister_sysctl(l4proto);
 385                 goto out;
 386         }
 387
 388         write_lock_bh(&nf_conntrack_lock);
 389         if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
 390             != l4proto) {
 391                 write_unlock_bh(&nf_conntrack_lock);
 392                 ret = -EBUSY;
 393                 goto out;
 394         }
 395         nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
 396                 = &nf_conntrack_l4proto_generic;
 397         write_unlock_bh(&nf_conntrack_lock);
 398
 399         nf_ct_l4proto_unregister_sysctl(l4proto);
 400
 401         /* Somebody could be still looking at the proto in bh. */
 402         synchronize_net();
 403
 404         /* Remove all contrack entries for this protocol */
 405         nf_ct_iterate_cleanup(kill_l4proto, l4proto);
 406
 407 out:
 408         return ret;
 409 }
 410 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);