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 #include <linux/rtnetlink.h>
  26
  27 #include <net/netfilter/nf_conntrack.h>
  28 #include <net/netfilter/nf_conntrack_l3proto.h>
  29 #include <net/netfilter/nf_conntrack_l4proto.h>
  30 #include <net/netfilter/nf_conntrack_core.h>
  31
  32 static struct nf_conntrack_l4proto **nf_ct_protos[PF_MAX] __read_mostly;
  33 struct nf_conntrack_l3proto *nf_ct_l3protos[AF_MAX] __read_mostly;
  34 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
  35
  36 static DEFINE_MUTEX(nf_ct_proto_mutex);
  37
  38 #ifdef CONFIG_SYSCTL
  39 static int
  40 nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_path *path,
  41                       struct ctl_table *table, unsigned int *users)
  42 {
  43         if (*header == NULL) {
  44                 *header = register_sysctl_paths(path, table);
  45                 if (*header == NULL)
  46                         return -ENOMEM;
  47         }
  48         if (users != NULL)
  49                 (*users)++;
  50         return 0;
  51 }
  52
  53 static void
  54 nf_ct_unregister_sysctl(struct ctl_table_header **header,
  55                         struct ctl_table *table, unsigned int *users)
  56 {
  57         if (users != NULL && --*users > 0)
  58                 return;
  59
  60         unregister_sysctl_table(*header);
  61         *header = NULL;
  62 }
  63 #endif
  64
  65 struct nf_conntrack_l4proto *
  66 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
  67 {
  68         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
  69                 return &nf_conntrack_l4proto_generic;
  70
  71         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
  72 }
  73 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  74
  75 /* this is guaranteed to always return a valid protocol helper, since
  76  * it falls back to generic_protocol */
  77 struct nf_conntrack_l4proto *
  78 nf_ct_l4proto_find_get(u_int16_t l3proto, u_int8_t l4proto)
  79 {
  80         struct nf_conntrack_l4proto *p;
  81
  82         rcu_read_lock();
  83         p = __nf_ct_l4proto_find(l3proto, l4proto);
  84         if (!try_module_get(p->me))
  85                 p = &nf_conntrack_l4proto_generic;
  86         rcu_read_unlock();
  87
  88         return p;
  89 }
  90 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
  91
  92 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
  93 {
  94         module_put(p->me);
  95 }
  96 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
  97
  98 struct nf_conntrack_l3proto *
  99 nf_ct_l3proto_find_get(u_int16_t l3proto)
 100 {
 101         struct nf_conntrack_l3proto *p;
 102
 103         rcu_read_lock();
 104         p = __nf_ct_l3proto_find(l3proto);
 105         if (!try_module_get(p->me))
 106                 p = &nf_conntrack_l3proto_generic;
 107         rcu_read_unlock();
 108
 109         return p;
 110 }
 111 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
 112
 113 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
 114 {
 115         module_put(p->me);
 116 }
 117 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
 118
 119 int
 120 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 121 {
 122         int ret;
 123         struct nf_conntrack_l3proto *p;
 124
 125 retry:  p = nf_ct_l3proto_find_get(l3proto);
 126         if (p == &nf_conntrack_l3proto_generic) {
 127                 ret = request_module("nf_conntrack-%d", l3proto);
 128                 if (!ret)
 129                         goto retry;
 130
 131                 return -EPROTOTYPE;
 132         }
 133
 134         return 0;
 135 }
 136 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 137
 138 void nf_ct_l3proto_module_put(unsigned short l3proto)
 139 {
 140         struct nf_conntrack_l3proto *p;
 141
 142         /* rcu_read_lock not necessary since the caller holds a reference */
 143         p = __nf_ct_l3proto_find(l3proto);
 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 nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 151 }
 152
 153 static int kill_l4proto(struct nf_conn *i, void *data)
 154 {
 155         struct nf_conntrack_l4proto *l4proto;
 156         l4proto = (struct nf_conntrack_l4proto *)data;
 157         return nf_ct_protonum(i) == l4proto->l4proto &&
 158                nf_ct_l3num(i) == l4proto->l3proto;
 159 }
 160
 161 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 162 {
 163         int err = 0;
 164
 165 #ifdef CONFIG_SYSCTL
 166         if (l3proto->ctl_table != NULL) {
 167                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 168                                             l3proto->ctl_table_path,
 169                                             l3proto->ctl_table, NULL);
 170         }
 171 #endif
 172         return err;
 173 }
 174
 175 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 176 {
 177 #ifdef CONFIG_SYSCTL
 178         if (l3proto->ctl_table_header != NULL)
 179                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 180                                         l3proto->ctl_table, NULL);
 181 #endif
 182 }
 183
 184 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 185 {
 186         int ret = 0;
 187
 188         if (proto->l3proto >= AF_MAX)
 189                 return -EBUSY;
 190
 191         mutex_lock(&nf_ct_proto_mutex);
 192         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 193                 ret = -EBUSY;
 194                 goto out_unlock;
 195         }
 196
 197         ret = nf_ct_l3proto_register_sysctl(proto);
 198         if (ret < 0)
 199                 goto out_unlock;
 200
 201         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 202
 203 out_unlock:
 204         mutex_unlock(&nf_ct_proto_mutex);
 205         return ret;
 206 }
 207 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 208
 209 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 210 {
 211         struct net *net;
 212
 213         BUG_ON(proto->l3proto >= AF_MAX);
 214
 215         mutex_lock(&nf_ct_proto_mutex);
 216         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
 217         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 218                            &nf_conntrack_l3proto_generic);
 219         nf_ct_l3proto_unregister_sysctl(proto);
 220         mutex_unlock(&nf_ct_proto_mutex);
 221
 222         synchronize_rcu();
 223
 224         /* Remove all contrack entries for this protocol */
 225         rtnl_lock();
 226         for_each_net(net)
 227                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
 228         rtnl_unlock();
 229 }
 230 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 231
 232 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 233 {
 234         int err = 0;
 235
 236 #ifdef CONFIG_SYSCTL
 237         if (l4proto->ctl_table != NULL) {
 238                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 239                                             nf_net_netfilter_sysctl_path,
 240                                             l4proto->ctl_table,
 241                                             l4proto->ctl_table_users);
 242                 if (err < 0)
 243                         goto out;
 244         }
 245 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 246         if (l4proto->ctl_compat_table != NULL) {
 247                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 248                                             nf_net_ipv4_netfilter_sysctl_path,
 249                                             l4proto->ctl_compat_table, NULL);
 250                 if (err == 0)
 251                         goto out;
 252                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 253                                         l4proto->ctl_table,
 254                                         l4proto->ctl_table_users);
 255         }
 256 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 257 out:
 258 #endif /* CONFIG_SYSCTL */
 259         return err;
 260 }
 261
 262 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 263 {
 264 #ifdef CONFIG_SYSCTL
 265         if (l4proto->ctl_table_header != NULL &&
 266             *l4proto->ctl_table_header != NULL)
 267                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 268                                         l4proto->ctl_table,
 269                                         l4proto->ctl_table_users);
 270 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 271         if (l4proto->ctl_compat_table_header != NULL)
 272                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 273                                         l4proto->ctl_compat_table, NULL);
 274 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 275 #endif /* CONFIG_SYSCTL */
 276 }
 277
 278 /* FIXME: Allow NULL functions and sub in pointers to generic for
 279    them. --RR */
 280 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 281 {
 282         int ret = 0;
 283
 284         if (l4proto->l3proto >= PF_MAX)
 285                 return -EBUSY;
 286
 287         mutex_lock(&nf_ct_proto_mutex);
 288         if (!nf_ct_protos[l4proto->l3proto]) {
 289                 /* l3proto may be loaded latter. */
 290                 struct nf_conntrack_l4proto **proto_array;
 291                 int i;
 292
 293                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 294                                       sizeof(struct nf_conntrack_l4proto *),
 295                                       GFP_KERNEL);
 296                 if (proto_array == NULL) {
 297                         ret = -ENOMEM;
 298                         goto out_unlock;
 299                 }
 300
 301                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 302                         proto_array[i] = &nf_conntrack_l4proto_generic;
 303                 nf_ct_protos[l4proto->l3proto] = proto_array;
 304         } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
 305                                         &nf_conntrack_l4proto_generic) {
 306                 ret = -EBUSY;
 307                 goto out_unlock;
 308         }
 309
 310         ret = nf_ct_l4proto_register_sysctl(l4proto);
 311         if (ret < 0)
 312                 goto out_unlock;
 313
 314         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 315                            l4proto);
 316
 317 out_unlock:
 318         mutex_unlock(&nf_ct_proto_mutex);
 319         return ret;
 320 }
 321 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 322
 323 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 324 {
 325         struct net *net;
 326
 327         BUG_ON(l4proto->l3proto >= PF_MAX);
 328
 329         mutex_lock(&nf_ct_proto_mutex);
 330         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 331         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 332                            &nf_conntrack_l4proto_generic);
 333         nf_ct_l4proto_unregister_sysctl(l4proto);
 334         mutex_unlock(&nf_ct_proto_mutex);
 335
 336         synchronize_rcu();
 337
 338         /* Remove all contrack entries for this protocol */
 339         rtnl_lock();
 340         for_each_net(net)
 341                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
 342         rtnl_unlock();
 343 }
 344 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
 345
 346 int nf_conntrack_proto_init(void)
 347 {
 348         unsigned int i;
 349         int err;
 350
 351         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
 352         if (err < 0)
 353                 return err;
 354
 355         for (i = 0; i < AF_MAX; i++)
 356                 rcu_assign_pointer(nf_ct_l3protos[i],
 357                                    &nf_conntrack_l3proto_generic);
 358         return 0;
 359 }
 360
 361 void nf_conntrack_proto_fini(void)
 362 {
 363         unsigned int i;
 364
 365         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
 366
 367         /* free l3proto protocol tables */
 368         for (i = 0; i < PF_MAX; i++)
 369                 kfree(nf_ct_protos[i]);
 370 }