net/netfilter/xt_CT.c

   1 /*
   2  * Copyright (c) 2010 Patrick McHardy <kaber@trash.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9 #include <linux/module.h>
  10 #include <linux/gfp.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/netfilter_ipv4/ip_tables.h>
  13 #include <linux/netfilter_ipv6/ip6_tables.h>
  14 #include <linux/netfilter/x_tables.h>
  15 #include <linux/netfilter/xt_CT.h>
  16 #include <net/netfilter/nf_conntrack.h>
  17 #include <net/netfilter/nf_conntrack_l4proto.h>
  18 #include <net/netfilter/nf_conntrack_helper.h>
  19 #include <net/netfilter/nf_conntrack_ecache.h>
  20 #include <net/netfilter/nf_conntrack_timeout.h>
  21 #include <net/netfilter/nf_conntrack_zones.h>
  22
  23 static unsigned int xt_ct_target_v0(struct sk_buff *skb,
  24                                     const struct xt_action_param *par)
  25 {
  26         const struct xt_ct_target_info *info = par->targinfo;
  27         struct nf_conn *ct = info->ct;
  28
  29         /* Previously seen (loopback)? Ignore. */
  30         if (skb->nfct != NULL)
  31                 return XT_CONTINUE;
  32
  33         atomic_inc(&ct->ct_general.use);
  34         skb->nfct = &ct->ct_general;
  35         skb->nfctinfo = IP_CT_NEW;
  36
  37         return XT_CONTINUE;
  38 }
  39
  40 static unsigned int xt_ct_target_v1(struct sk_buff *skb,
  41                                     const struct xt_action_param *par)
  42 {
  43         const struct xt_ct_target_info_v1 *info = par->targinfo;
  44         struct nf_conn *ct = info->ct;
  45
  46         /* Previously seen (loopback)? Ignore. */
  47         if (skb->nfct != NULL)
  48                 return XT_CONTINUE;
  49
  50         atomic_inc(&ct->ct_general.use);
  51         skb->nfct = &ct->ct_general;
  52         skb->nfctinfo = IP_CT_NEW;
  53
  54         return XT_CONTINUE;
  55 }
  56
  57 static u8 xt_ct_find_proto(const struct xt_tgchk_param *par)
  58 {
  59         if (par->family == NFPROTO_IPV4) {
  60                 const struct ipt_entry *e = par->entryinfo;
  61
  62                 if (e->ip.invflags & IPT_INV_PROTO)
  63                         return 0;
  64                 return e->ip.proto;
  65         } else if (par->family == NFPROTO_IPV6) {
  66                 const struct ip6t_entry *e = par->entryinfo;
  67
  68                 if (e->ipv6.invflags & IP6T_INV_PROTO)
  69                         return 0;
  70                 return e->ipv6.proto;
  71         } else
  72                 return 0;
  73 }
  74
  75 static int
  76 xt_ct_set_helper(struct nf_conn *ct, const char *helper_name,
  77                  const struct xt_tgchk_param *par)
  78 {
  79         struct nf_conntrack_helper *helper;
  80         struct nf_conn_help *help;
  81         u8 proto;
  82
  83         proto = xt_ct_find_proto(par);
  84         if (!proto) {
  85                 pr_info("You must specify a L4 protocol, and not use "
  86                         "inversions on it.\n");
  87                 return -ENOENT;
  88         }
  89
  90         helper = nf_conntrack_helper_try_module_get(helper_name, par->family,
  91                                                     proto);
  92         if (helper == NULL) {
  93                 pr_info("No such helper \"%s\"\n", helper_name);
  94                 return -ENOENT;
  95         }
  96
  97         help = nf_ct_helper_ext_add(ct, helper, GFP_KERNEL);
  98         if (help == NULL) {
  99                 module_put(helper->me);
 100                 return -ENOMEM;
 101         }
 102
 103         help->helper = helper;
 104         return 0;
 105 }
 106
 107 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
 108 {
 109         struct xt_ct_target_info *info = par->targinfo;
 110         struct nf_conntrack_tuple t;
 111         struct nf_conn *ct;
 112         int ret;
 113
 114         if (info->flags & ~XT_CT_NOTRACK)
 115                 return -EINVAL;
 116
 117         if (info->flags & XT_CT_NOTRACK) {
 118                 ct = nf_ct_untracked_get();
 119                 atomic_inc(&ct->ct_general.use);
 120                 goto out;
 121         }
 122
 123 #ifndef CONFIG_NF_CONNTRACK_ZONES
 124         if (info->zone)
 125                 goto err1;
 126 #endif
 127
 128         ret = nf_ct_l3proto_try_module_get(par->family);
 129         if (ret < 0)
 130                 goto err1;
 131
 132         memset(&t, 0, sizeof(t));
 133         ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
 134         ret = PTR_ERR(ct);
 135         if (IS_ERR(ct))
 136                 goto err2;
 137
 138         ret = 0;
 139         if ((info->ct_events || info->exp_events) &&
 140             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 141                                   GFP_KERNEL))
 142                 goto err3;
 143
 144         if (info->helper[0]) {
 145                 ret = xt_ct_set_helper(ct, info->helper, par);
 146                 if (ret < 0)
 147                         goto err3;
 148         }
 149
 150         __set_bit(IPS_TEMPLATE_BIT, &ct->status);
 151         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 152 out:
 153         info->ct = ct;
 154         return 0;
 155
 156 err3:
 157         nf_conntrack_free(ct);
 158 err2:
 159         nf_ct_l3proto_module_put(par->family);
 160 err1:
 161         return ret;
 162 }
 163
 164 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 165 static void __xt_ct_tg_timeout_put(struct ctnl_timeout *timeout)
 166 {
 167         typeof(nf_ct_timeout_put_hook) timeout_put;
 168
 169         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 170         if (timeout_put)
 171                 timeout_put(timeout);
 172 }
 173 #endif
 174
 175 static int
 176 xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
 177                   const char *timeout_name)
 178 {
 179 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 180         typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
 181         struct ctnl_timeout *timeout;
 182         struct nf_conn_timeout *timeout_ext;
 183         const struct ipt_entry *e = par->entryinfo;
 184         struct nf_conntrack_l4proto *l4proto;
 185         int ret = 0;
 186
 187         rcu_read_lock();
 188         timeout_find_get = rcu_dereference(nf_ct_timeout_find_get_hook);
 189         if (timeout_find_get == NULL) {
 190                 ret = -ENOENT;
 191                 pr_info("Timeout policy base is empty\n");
 192                 goto out;
 193         }
 194
 195         if (e->ip.invflags & IPT_INV_PROTO) {
 196                 ret = -EINVAL;
 197                 pr_info("You cannot use inversion on L4 protocol\n");
 198                 goto out;
 199         }
 200
 201         timeout = timeout_find_get(timeout_name);
 202         if (timeout == NULL) {
 203                 ret = -ENOENT;
 204                 pr_info("No such timeout policy \"%s\"\n", timeout_name);
 205                 goto out;
 206         }
 207
 208         if (timeout->l3num != par->family) {
 209                 ret = -EINVAL;
 210                 pr_info("Timeout policy `%s' can only be used by L3 protocol "
 211                         "number %d\n", timeout_name, timeout->l3num);
 212                 goto err_put_timeout;
 213         }
 214         /* Make sure the timeout policy matches any existing protocol tracker,
 215          * otherwise default to generic.
 216          */
 217         l4proto = __nf_ct_l4proto_find(par->family, e->ip.proto);
 218         if (timeout->l4proto->l4proto != l4proto->l4proto) {
 219                 ret = -EINVAL;
 220                 pr_info("Timeout policy `%s' can only be used by L4 protocol "
 221                         "number %d\n",
 222                         timeout_name, timeout->l4proto->l4proto);
 223                 goto err_put_timeout;
 224         }
 225         timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
 226         if (timeout_ext == NULL)
 227                 ret = -ENOMEM;
 228
 229 err_put_timeout:
 230         __xt_ct_tg_timeout_put(timeout);
 231 out:
 232         rcu_read_unlock();
 233         return ret;
 234 #else
 235         return -EOPNOTSUPP;
 236 #endif
 237 }
 238
 239 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 240 {
 241         struct xt_ct_target_info_v1 *info = par->targinfo;
 242         struct nf_conntrack_tuple t;
 243         struct nf_conn *ct;
 244         int ret;
 245
 246         if (info->flags & ~XT_CT_NOTRACK)
 247                 return -EINVAL;
 248
 249         if (info->flags & XT_CT_NOTRACK) {
 250                 ct = nf_ct_untracked_get();
 251                 atomic_inc(&ct->ct_general.use);
 252                 goto out;
 253         }
 254
 255 #ifndef CONFIG_NF_CONNTRACK_ZONES
 256         if (info->zone)
 257                 goto err1;
 258 #endif
 259
 260         ret = nf_ct_l3proto_try_module_get(par->family);
 261         if (ret < 0)
 262                 goto err1;
 263
 264         memset(&t, 0, sizeof(t));
 265         ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
 266         ret = PTR_ERR(ct);
 267         if (IS_ERR(ct))
 268                 goto err2;
 269
 270         ret = 0;
 271         if ((info->ct_events || info->exp_events) &&
 272             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 273                                   GFP_KERNEL))
 274                 goto err3;
 275
 276         if (info->helper[0]) {
 277                 ret = xt_ct_set_helper(ct, info->helper, par);
 278                 if (ret < 0)
 279                         goto err3;
 280         }
 281
 282         if (info->timeout[0]) {
 283                 ret = xt_ct_set_timeout(ct, par, info->timeout);
 284                 if (ret < 0)
 285                         goto err3;
 286         }
 287
 288         __set_bit(IPS_TEMPLATE_BIT, &ct->status);
 289         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 290 out:
 291         info->ct = ct;
 292         return 0;
 293
 294 err3:
 295         nf_conntrack_free(ct);
 296 err2:
 297         nf_ct_l3proto_module_put(par->family);
 298 err1:
 299         return ret;
 300 }
 301
 302 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 303 {
 304         struct xt_ct_target_info *info = par->targinfo;
 305         struct nf_conn *ct = info->ct;
 306         struct nf_conn_help *help;
 307
 308         if (!nf_ct_is_untracked(ct)) {
 309                 help = nfct_help(ct);
 310                 if (help)
 311                         module_put(help->helper->me);
 312
 313                 nf_ct_l3proto_module_put(par->family);
 314         }
 315         nf_ct_put(info->ct);
 316 }
 317
 318 static void xt_ct_destroy_timeout(struct nf_conn *ct)
 319 {
 320 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 321         struct nf_conn_timeout *timeout_ext;
 322         typeof(nf_ct_timeout_put_hook) timeout_put;
 323
 324         rcu_read_lock();
 325         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 326
 327         if (timeout_put) {
 328                 timeout_ext = nf_ct_timeout_find(ct);
 329                 if (timeout_ext)
 330                         timeout_put(timeout_ext->timeout);
 331         }
 332         rcu_read_unlock();
 333 #endif
 334 }
 335
 336 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 337 {
 338         struct xt_ct_target_info_v1 *info = par->targinfo;
 339         struct nf_conn *ct = info->ct;
 340         struct nf_conn_help *help;
 341
 342         if (!nf_ct_is_untracked(ct)) {
 343                 help = nfct_help(ct);
 344                 if (help)
 345                         module_put(help->helper->me);
 346
 347                 nf_ct_l3proto_module_put(par->family);
 348
 349                 xt_ct_destroy_timeout(ct);
 350         }
 351         nf_ct_put(info->ct);
 352 }
 353
 354 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 355         {
 356                 .name           = "CT",
 357                 .family         = NFPROTO_UNSPEC,
 358                 .targetsize     = sizeof(struct xt_ct_target_info),
 359                 .checkentry     = xt_ct_tg_check_v0,
 360                 .destroy        = xt_ct_tg_destroy_v0,
 361                 .target         = xt_ct_target_v0,
 362                 .table          = "raw",
 363                 .me             = THIS_MODULE,
 364         },
 365         {
 366                 .name           = "CT",
 367                 .family         = NFPROTO_UNSPEC,
 368                 .revision       = 1,
 369                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 370                 .checkentry     = xt_ct_tg_check_v1,
 371                 .destroy        = xt_ct_tg_destroy_v1,
 372                 .target         = xt_ct_target_v1,
 373                 .table          = "raw",
 374                 .me             = THIS_MODULE,
 375         },
 376 };
 377
 378 static int __init xt_ct_tg_init(void)
 379 {
 380         return xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 381 }
 382
 383 static void __exit xt_ct_tg_exit(void)
 384 {
 385         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 386 }
 387
 388 module_init(xt_ct_tg_init);
 389 module_exit(xt_ct_tg_exit);
 390
 391 MODULE_LICENSE("GPL");
 392 MODULE_DESCRIPTION("Xtables: connection tracking target");
 393 MODULE_ALIAS("ipt_CT");
 394 MODULE_ALIAS("ip6t_CT");