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         mutex_lock(&nf_ct_proto_mutex);
 168         if (l3proto->ctl_table != NULL) {
 169                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 170                                             l3proto->ctl_table_path,
 171                                             l3proto->ctl_table, NULL);
 172         }
 173         mutex_unlock(&nf_ct_proto_mutex);
 174 #endif
 175         return err;
 176 }
 177
 178 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 179 {
 180 #ifdef CONFIG_SYSCTL
 181         mutex_lock(&nf_ct_proto_mutex);
 182         if (l3proto->ctl_table_header != NULL)
 183                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 184                                         l3proto->ctl_table, NULL);
 185         mutex_unlock(&nf_ct_proto_mutex);
 186 #endif
 187 }
 188
 189 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 190 {
 191         int ret = 0;
 192
 193         if (proto->l3proto >= AF_MAX) {
 194                 ret = -EBUSY;
 195                 goto out;
 196         }
 197
 198         mutex_lock(&nf_ct_proto_mutex);
 199         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 200                 ret = -EBUSY;
 201                 goto out_unlock;
 202         }
 203         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 204         mutex_unlock(&nf_ct_proto_mutex);
 205
 206         ret = nf_ct_l3proto_register_sysctl(proto);
 207         if (ret < 0)
 208                 nf_conntrack_l3proto_unregister(proto);
 209         return ret;
 210
 211 out_unlock:
 212         mutex_unlock(&nf_ct_proto_mutex);
 213 out:
 214         return ret;
 215 }
 216 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 217
 218 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 219 {
 220         BUG_ON(proto->l3proto >= AF_MAX);
 221
 222         mutex_lock(&nf_ct_proto_mutex);
 223         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
 224         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 225                            &nf_conntrack_l3proto_generic);
 226         mutex_unlock(&nf_ct_proto_mutex);
 227         synchronize_rcu();
 228
 229         nf_ct_l3proto_unregister_sysctl(proto);
 230
 231         /* Remove all contrack entries for this protocol */
 232         nf_ct_iterate_cleanup(kill_l3proto, proto);
 233 }
 234 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 235
 236 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 237 {
 238         int err = 0;
 239
 240 #ifdef CONFIG_SYSCTL
 241         mutex_lock(&nf_ct_proto_mutex);
 242         if (l4proto->ctl_table != NULL) {
 243                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 244                                             nf_net_netfilter_sysctl_path,
 245                                             l4proto->ctl_table,
 246                                             l4proto->ctl_table_users);
 247                 if (err < 0)
 248                         goto out;
 249         }
 250 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 251         if (l4proto->ctl_compat_table != NULL) {
 252                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 253                                             nf_net_ipv4_netfilter_sysctl_path,
 254                                             l4proto->ctl_compat_table, NULL);
 255                 if (err == 0)
 256                         goto out;
 257                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 258                                         l4proto->ctl_table,
 259                                         l4proto->ctl_table_users);
 260         }
 261 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 262 out:
 263         mutex_unlock(&nf_ct_proto_mutex);
 264 #endif /* CONFIG_SYSCTL */
 265         return err;
 266 }
 267
 268 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 269 {
 270 #ifdef CONFIG_SYSCTL
 271         mutex_lock(&nf_ct_proto_mutex);
 272         if (l4proto->ctl_table_header != NULL &&
 273             *l4proto->ctl_table_header != NULL)
 274                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 275                                         l4proto->ctl_table,
 276                                         l4proto->ctl_table_users);
 277 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 278         if (l4proto->ctl_compat_table_header != NULL)
 279                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 280                                         l4proto->ctl_compat_table, NULL);
 281 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 282         mutex_unlock(&nf_ct_proto_mutex);
 283 #endif /* CONFIG_SYSCTL */
 284 }
 285
 286 /* FIXME: Allow NULL functions and sub in pointers to generic for
 287    them. --RR */
 288 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 289 {
 290         int ret = 0;
 291
 292         if (l4proto->l3proto >= PF_MAX) {
 293                 ret = -EBUSY;
 294                 goto out;
 295         }
 296
 297         if (l4proto == &nf_conntrack_l4proto_generic)
 298                 return nf_ct_l4proto_register_sysctl(l4proto);
 299
 300         mutex_lock(&nf_ct_proto_mutex);
 301 retry:
 302         if (nf_ct_protos[l4proto->l3proto]) {
 303                 if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
 304                                 != &nf_conntrack_l4proto_generic) {
 305                         ret = -EBUSY;
 306                         goto out_unlock;
 307                 }
 308         } else {
 309                 /* l3proto may be loaded latter. */
 310                 struct nf_conntrack_l4proto **proto_array;
 311                 int i;
 312
 313                 proto_array = (struct nf_conntrack_l4proto **)
 314                                 kmalloc(MAX_NF_CT_PROTO *
 315                                          sizeof(struct nf_conntrack_l4proto *),
 316                                         GFP_KERNEL);
 317                 if (proto_array == NULL) {
 318                         ret = -ENOMEM;
 319                         goto out_unlock;
 320                 }
 321                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 322                         proto_array[i] = &nf_conntrack_l4proto_generic;
 323
 324                 if (nf_ct_protos[l4proto->l3proto])
 325                         /* bad timing, but no problem */
 326                         kfree(proto_array);
 327                 else
 328                         nf_ct_protos[l4proto->l3proto] = proto_array;
 329
 330                 /*
 331                  * Just once because array is never freed until unloading
 332                  * nf_conntrack.ko
 333                  */
 334                 goto retry;
 335         }
 336
 337         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto], l4proto);
 338         mutex_unlock(&nf_ct_proto_mutex);
 339
 340         ret = nf_ct_l4proto_register_sysctl(l4proto);
 341         if (ret < 0)
 342                 nf_conntrack_l4proto_unregister(l4proto);
 343         return ret;
 344
 345 out_unlock:
 346         mutex_unlock(&nf_ct_proto_mutex);
 347 out:
 348         return ret;
 349 }
 350 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 351
 352 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 353 {
 354         BUG_ON(l4proto->l3proto >= PF_MAX);
 355
 356         if (l4proto == &nf_conntrack_l4proto_generic) {
 357                 nf_ct_l4proto_unregister_sysctl(l4proto);
 358                 return;
 359         }
 360
 361         mutex_lock(&nf_ct_proto_mutex);
 362         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 363         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 364                            &nf_conntrack_l4proto_generic);
 365         mutex_unlock(&nf_ct_proto_mutex);
 366         synchronize_rcu();
 367
 368         nf_ct_l4proto_unregister_sysctl(l4proto);
 369
 370         /* Remove all contrack entries for this protocol */
 371         nf_ct_iterate_cleanup(kill_l4proto, l4proto);
 372 }
 373 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);