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/slab.h>
  16 #include <linux/mutex.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/stddef.h>
  20 #include <linux/err.h>
  21 #include <linux/percpu.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/notifier.h>
  24 #include <linux/kernel.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/rtnetlink.h>
  27
  28 #include <net/netfilter/nf_conntrack.h>
  29 #include <net/netfilter/nf_conntrack_l3proto.h>
  30 #include <net/netfilter/nf_conntrack_l4proto.h>
  31 #include <net/netfilter/nf_conntrack_core.h>
  32
  33 static struct nf_conntrack_l4proto **nf_ct_protos[PF_MAX] __read_mostly;
  34 struct nf_conntrack_l3proto *nf_ct_l3protos[AF_MAX] __read_mostly;
  35 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
  36
  37 static DEFINE_MUTEX(nf_ct_proto_mutex);
  38
  39 #ifdef CONFIG_SYSCTL
  40 static int
  41 nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_path *path,
  42                       struct ctl_table *table, unsigned int *users)
  43 {
  44         if (*header == NULL) {
  45                 *header = register_sysctl_paths(path, table);
  46                 if (*header == NULL)
  47                         return -ENOMEM;
  48         }
  49         if (users != NULL)
  50                 (*users)++;
  51         return 0;
  52 }
  53
  54 static void
  55 nf_ct_unregister_sysctl(struct ctl_table_header **header,
  56                         struct ctl_table *table, unsigned int *users)
  57 {
  58         if (users != NULL && --*users > 0)
  59                 return;
  60
  61         unregister_sysctl_table(*header);
  62         *header = NULL;
  63 }
  64 #endif
  65
  66 struct nf_conntrack_l4proto *
  67 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
  68 {
  69         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
  70                 return &nf_conntrack_l4proto_generic;
  71
  72         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
  73 }
  74 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  75
  76 /* this is guaranteed to always return a valid protocol helper, since
  77  * it falls back to generic_protocol */
  78 struct nf_conntrack_l3proto *
  79 nf_ct_l3proto_find_get(u_int16_t l3proto)
  80 {
  81         struct nf_conntrack_l3proto *p;
  82
  83         rcu_read_lock();
  84         p = __nf_ct_l3proto_find(l3proto);
  85         if (!try_module_get(p->me))
  86                 p = &nf_conntrack_l3proto_generic;
  87         rcu_read_unlock();
  88
  89         return p;
  90 }
  91 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
  92
  93 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
  94 {
  95         module_put(p->me);
  96 }
  97 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
  98
  99 int
 100 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 101 {
 102         int ret;
 103         struct nf_conntrack_l3proto *p;
 104
 105 retry:  p = nf_ct_l3proto_find_get(l3proto);
 106         if (p == &nf_conntrack_l3proto_generic) {
 107                 ret = request_module("nf_conntrack-%d", l3proto);
 108                 if (!ret)
 109                         goto retry;
 110
 111                 return -EPROTOTYPE;
 112         }
 113
 114         return 0;
 115 }
 116 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 117
 118 void nf_ct_l3proto_module_put(unsigned short l3proto)
 119 {
 120         struct nf_conntrack_l3proto *p;
 121
 122         /* rcu_read_lock not necessary since the caller holds a reference */
 123         p = __nf_ct_l3proto_find(l3proto);
 124         module_put(p->me);
 125 }
 126 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 127
 128 static int kill_l3proto(struct nf_conn *i, void *data)
 129 {
 130         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 131 }
 132
 133 static int kill_l4proto(struct nf_conn *i, void *data)
 134 {
 135         struct nf_conntrack_l4proto *l4proto;
 136         l4proto = (struct nf_conntrack_l4proto *)data;
 137         return nf_ct_protonum(i) == l4proto->l4proto &&
 138                nf_ct_l3num(i) == l4proto->l3proto;
 139 }
 140
 141 static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
 142 {
 143         int err = 0;
 144
 145 #ifdef CONFIG_SYSCTL
 146         if (l3proto->ctl_table != NULL) {
 147                 err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
 148                                             l3proto->ctl_table_path,
 149                                             l3proto->ctl_table, NULL);
 150         }
 151 #endif
 152         return err;
 153 }
 154
 155 static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
 156 {
 157 #ifdef CONFIG_SYSCTL
 158         if (l3proto->ctl_table_header != NULL)
 159                 nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
 160                                         l3proto->ctl_table, NULL);
 161 #endif
 162 }
 163
 164 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 165 {
 166         int ret = 0;
 167
 168         if (proto->l3proto >= AF_MAX)
 169                 return -EBUSY;
 170
 171         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 172                 return -EINVAL;
 173
 174         mutex_lock(&nf_ct_proto_mutex);
 175         if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
 176                 ret = -EBUSY;
 177                 goto out_unlock;
 178         }
 179
 180         ret = nf_ct_l3proto_register_sysctl(proto);
 181         if (ret < 0)
 182                 goto out_unlock;
 183
 184         if (proto->nlattr_tuple_size)
 185                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 186
 187         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 188
 189 out_unlock:
 190         mutex_unlock(&nf_ct_proto_mutex);
 191         return ret;
 192 }
 193 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
 194
 195 void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 196 {
 197         struct net *net;
 198
 199         BUG_ON(proto->l3proto >= AF_MAX);
 200
 201         mutex_lock(&nf_ct_proto_mutex);
 202         BUG_ON(nf_ct_l3protos[proto->l3proto] != proto);
 203         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 204                            &nf_conntrack_l3proto_generic);
 205         nf_ct_l3proto_unregister_sysctl(proto);
 206         mutex_unlock(&nf_ct_proto_mutex);
 207
 208         synchronize_rcu();
 209
 210         /* Remove all contrack entries for this protocol */
 211         rtnl_lock();
 212         for_each_net(net)
 213                 nf_ct_iterate_cleanup(net, kill_l3proto, proto);
 214         rtnl_unlock();
 215 }
 216 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 217
 218 static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
 219 {
 220         int err = 0;
 221
 222 #ifdef CONFIG_SYSCTL
 223         if (l4proto->ctl_table != NULL) {
 224                 err = nf_ct_register_sysctl(l4proto->ctl_table_header,
 225                                             nf_net_netfilter_sysctl_path,
 226                                             l4proto->ctl_table,
 227                                             l4proto->ctl_table_users);
 228                 if (err < 0)
 229                         goto out;
 230         }
 231 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 232         if (l4proto->ctl_compat_table != NULL) {
 233                 err = nf_ct_register_sysctl(&l4proto->ctl_compat_table_header,
 234                                             nf_net_ipv4_netfilter_sysctl_path,
 235                                             l4proto->ctl_compat_table, NULL);
 236                 if (err == 0)
 237                         goto out;
 238                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 239                                         l4proto->ctl_table,
 240                                         l4proto->ctl_table_users);
 241         }
 242 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 243 out:
 244 #endif /* CONFIG_SYSCTL */
 245         return err;
 246 }
 247
 248 static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
 249 {
 250 #ifdef CONFIG_SYSCTL
 251         if (l4proto->ctl_table_header != NULL &&
 252             *l4proto->ctl_table_header != NULL)
 253                 nf_ct_unregister_sysctl(l4proto->ctl_table_header,
 254                                         l4proto->ctl_table,
 255                                         l4proto->ctl_table_users);
 256 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 257         if (l4proto->ctl_compat_table_header != NULL)
 258                 nf_ct_unregister_sysctl(&l4proto->ctl_compat_table_header,
 259                                         l4proto->ctl_compat_table, NULL);
 260 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 261 #endif /* CONFIG_SYSCTL */
 262 }
 263
 264 /* FIXME: Allow NULL functions and sub in pointers to generic for
 265    them. --RR */
 266 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 267 {
 268         int ret = 0;
 269
 270         if (l4proto->l3proto >= PF_MAX)
 271                 return -EBUSY;
 272
 273         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
 274                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 275                 return -EINVAL;
 276
 277         mutex_lock(&nf_ct_proto_mutex);
 278         if (!nf_ct_protos[l4proto->l3proto]) {
 279                 /* l3proto may be loaded latter. */
 280                 struct nf_conntrack_l4proto **proto_array;
 281                 int i;
 282
 283                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 284                                       sizeof(struct nf_conntrack_l4proto *),
 285                                       GFP_KERNEL);
 286                 if (proto_array == NULL) {
 287                         ret = -ENOMEM;
 288                         goto out_unlock;
 289                 }
 290
 291                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 292                         proto_array[i] = &nf_conntrack_l4proto_generic;
 293                 nf_ct_protos[l4proto->l3proto] = proto_array;
 294         } else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
 295                                         &nf_conntrack_l4proto_generic) {
 296                 ret = -EBUSY;
 297                 goto out_unlock;
 298         }
 299
 300         ret = nf_ct_l4proto_register_sysctl(l4proto);
 301         if (ret < 0)
 302                 goto out_unlock;
 303
 304         l4proto->nla_size = 0;
 305         if (l4proto->nlattr_size)
 306                 l4proto->nla_size += l4proto->nlattr_size();
 307         if (l4proto->nlattr_tuple_size)
 308                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 309
 310         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 311                            l4proto);
 312
 313 out_unlock:
 314         mutex_unlock(&nf_ct_proto_mutex);
 315         return ret;
 316 }
 317 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
 318
 319 void nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 320 {
 321         struct net *net;
 322
 323         BUG_ON(l4proto->l3proto >= PF_MAX);
 324
 325         mutex_lock(&nf_ct_proto_mutex);
 326         BUG_ON(nf_ct_protos[l4proto->l3proto][l4proto->l4proto] != l4proto);
 327         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 328                            &nf_conntrack_l4proto_generic);
 329         nf_ct_l4proto_unregister_sysctl(l4proto);
 330         mutex_unlock(&nf_ct_proto_mutex);
 331
 332         synchronize_rcu();
 333
 334         /* Remove all contrack entries for this protocol */
 335         rtnl_lock();
 336         for_each_net(net)
 337                 nf_ct_iterate_cleanup(net, kill_l4proto, l4proto);
 338         rtnl_unlock();
 339 }
 340 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_unregister);
 341
 342 int nf_conntrack_proto_init(void)
 343 {
 344         unsigned int i;
 345         int err;
 346
 347         err = nf_ct_l4proto_register_sysctl(&nf_conntrack_l4proto_generic);
 348         if (err < 0)
 349                 return err;
 350
 351         for (i = 0; i < AF_MAX; i++)
 352                 rcu_assign_pointer(nf_ct_l3protos[i],
 353                                    &nf_conntrack_l3proto_generic);
 354         return 0;
 355 }
 356
 357 void nf_conntrack_proto_fini(void)
 358 {
 359         unsigned int i;
 360
 361         nf_ct_l4proto_unregister_sysctl(&nf_conntrack_l4proto_generic);
 362
 363         /* free l3proto protocol tables */
 364         for (i = 0; i < PF_MAX; i++)
 365                 kfree(nf_ct_protos[i]);
 366 }