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
 153         /* Overload tuple linked list to put us in template list. */
 154         hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
 155                                  &par->net->ct.tmpl);
 156 out:
 157         info->ct = ct;
 158         return 0;
 159
 160 err3:
 161         nf_conntrack_free(ct);
 162 err2:
 163         nf_ct_l3proto_module_put(par->family);
 164 err1:
 165         return ret;
 166 }
 167
 168 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 169 static void __xt_ct_tg_timeout_put(struct ctnl_timeout *timeout)
 170 {
 171         typeof(nf_ct_timeout_put_hook) timeout_put;
 172
 173         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 174         if (timeout_put)
 175                 timeout_put(timeout);
 176 }
 177 #endif
 178
 179 static int
 180 xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
 181                   const char *timeout_name)
 182 {
 183 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 184         typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
 185         struct ctnl_timeout *timeout;
 186         struct nf_conn_timeout *timeout_ext;
 187         struct nf_conntrack_l4proto *l4proto;
 188         int ret = 0;
 189         u8 proto;
 190
 191         rcu_read_lock();
 192         timeout_find_get = rcu_dereference(nf_ct_timeout_find_get_hook);
 193         if (timeout_find_get == NULL) {
 194                 ret = -ENOENT;
 195                 pr_info("Timeout policy base is empty\n");
 196                 goto out;
 197         }
 198
 199         proto = xt_ct_find_proto(par);
 200         if (!proto) {
 201                 ret = -EINVAL;
 202                 pr_info("You must specify a L4 protocol, and not use "
 203                         "inversions on it.\n");
 204                 goto out;
 205         }
 206
 207         timeout = timeout_find_get(timeout_name);
 208         if (timeout == NULL) {
 209                 ret = -ENOENT;
 210                 pr_info("No such timeout policy \"%s\"\n", timeout_name);
 211                 goto out;
 212         }
 213
 214         if (timeout->l3num != par->family) {
 215                 ret = -EINVAL;
 216                 pr_info("Timeout policy `%s' can only be used by L3 protocol "
 217                         "number %d\n", timeout_name, timeout->l3num);
 218                 goto err_put_timeout;
 219         }
 220         /* Make sure the timeout policy matches any existing protocol tracker,
 221          * otherwise default to generic.
 222          */
 223         l4proto = __nf_ct_l4proto_find(par->family, proto);
 224         if (timeout->l4proto->l4proto != l4proto->l4proto) {
 225                 ret = -EINVAL;
 226                 pr_info("Timeout policy `%s' can only be used by L4 protocol "
 227                         "number %d\n",
 228                         timeout_name, timeout->l4proto->l4proto);
 229                 goto err_put_timeout;
 230         }
 231         timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
 232         if (timeout_ext == NULL)
 233                 ret = -ENOMEM;
 234
 235 err_put_timeout:
 236         __xt_ct_tg_timeout_put(timeout);
 237 out:
 238         rcu_read_unlock();
 239         return ret;
 240 #else
 241         return -EOPNOTSUPP;
 242 #endif
 243 }
 244
 245 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 246 {
 247         struct xt_ct_target_info_v1 *info = par->targinfo;
 248         struct nf_conntrack_tuple t;
 249         struct nf_conn *ct;
 250         int ret;
 251
 252         if (info->flags & ~XT_CT_NOTRACK)
 253                 return -EINVAL;
 254
 255         if (info->flags & XT_CT_NOTRACK) {
 256                 ct = nf_ct_untracked_get();
 257                 atomic_inc(&ct->ct_general.use);
 258                 goto out;
 259         }
 260
 261 #ifndef CONFIG_NF_CONNTRACK_ZONES
 262         if (info->zone)
 263                 goto err1;
 264 #endif
 265
 266         ret = nf_ct_l3proto_try_module_get(par->family);
 267         if (ret < 0)
 268                 goto err1;
 269
 270         memset(&t, 0, sizeof(t));
 271         ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
 272         ret = PTR_ERR(ct);
 273         if (IS_ERR(ct))
 274                 goto err2;
 275
 276         ret = 0;
 277         if ((info->ct_events || info->exp_events) &&
 278             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 279                                   GFP_KERNEL))
 280                 goto err3;
 281
 282         if (info->helper[0]) {
 283                 ret = xt_ct_set_helper(ct, info->helper, par);
 284                 if (ret < 0)
 285                         goto err3;
 286         }
 287
 288         if (info->timeout[0]) {
 289                 ret = xt_ct_set_timeout(ct, par, info->timeout);
 290                 if (ret < 0)
 291                         goto err3;
 292         }
 293
 294         __set_bit(IPS_TEMPLATE_BIT, &ct->status);
 295         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 296
 297         /* Overload tuple linked list to put us in template list. */
 298         hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
 299                                  &par->net->ct.tmpl);
 300 out:
 301         info->ct = ct;
 302         return 0;
 303
 304 err3:
 305         nf_conntrack_free(ct);
 306 err2:
 307         nf_ct_l3proto_module_put(par->family);
 308 err1:
 309         return ret;
 310 }
 311
 312 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 313 {
 314         struct xt_ct_target_info *info = par->targinfo;
 315         struct nf_conn *ct = info->ct;
 316         struct nf_conn_help *help;
 317
 318         if (!nf_ct_is_untracked(ct)) {
 319                 help = nfct_help(ct);
 320                 if (help)
 321                         module_put(help->helper->me);
 322
 323                 nf_ct_l3proto_module_put(par->family);
 324         }
 325         nf_ct_put(info->ct);
 326 }
 327
 328 static void xt_ct_destroy_timeout(struct nf_conn *ct)
 329 {
 330 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 331         struct nf_conn_timeout *timeout_ext;
 332         typeof(nf_ct_timeout_put_hook) timeout_put;
 333
 334         rcu_read_lock();
 335         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 336
 337         if (timeout_put) {
 338                 timeout_ext = nf_ct_timeout_find(ct);
 339                 if (timeout_ext)
 340                         timeout_put(timeout_ext->timeout);
 341         }
 342         rcu_read_unlock();
 343 #endif
 344 }
 345
 346 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 347 {
 348         struct xt_ct_target_info_v1 *info = par->targinfo;
 349         struct nf_conn *ct = info->ct;
 350         struct nf_conn_help *help;
 351
 352         if (!nf_ct_is_untracked(ct)) {
 353                 help = nfct_help(ct);
 354                 if (help)
 355                         module_put(help->helper->me);
 356
 357                 nf_ct_l3proto_module_put(par->family);
 358
 359                 xt_ct_destroy_timeout(ct);
 360         }
 361         nf_ct_put(info->ct);
 362 }
 363
 364 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 365         {
 366                 .name           = "CT",
 367                 .family         = NFPROTO_UNSPEC,
 368                 .targetsize     = sizeof(struct xt_ct_target_info),
 369                 .checkentry     = xt_ct_tg_check_v0,
 370                 .destroy        = xt_ct_tg_destroy_v0,
 371                 .target         = xt_ct_target_v0,
 372                 .table          = "raw",
 373                 .me             = THIS_MODULE,
 374         },
 375         {
 376                 .name           = "CT",
 377                 .family         = NFPROTO_UNSPEC,
 378                 .revision       = 1,
 379                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 380                 .checkentry     = xt_ct_tg_check_v1,
 381                 .destroy        = xt_ct_tg_destroy_v1,
 382                 .target         = xt_ct_target_v1,
 383                 .table          = "raw",
 384                 .me             = THIS_MODULE,
 385         },
 386 };
 387
 388 static unsigned int
 389 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 390 {
 391         /* Previously seen (loopback)? Ignore. */
 392         if (skb->nfct != NULL)
 393                 return XT_CONTINUE;
 394
 395         skb->nfct = &nf_ct_untracked_get()->ct_general;
 396         skb->nfctinfo = IP_CT_NEW;
 397         nf_conntrack_get(skb->nfct);
 398
 399         return XT_CONTINUE;
 400 }
 401
 402 static int notrack_chk(const struct xt_tgchk_param *par)
 403 {
 404         if (!par->net->xt.notrack_deprecated_warning) {
 405                 pr_info("netfilter: NOTRACK target is deprecated, "
 406                         "use CT instead or upgrade iptables\n");
 407                 par->net->xt.notrack_deprecated_warning = true;
 408         }
 409         return 0;
 410 }
 411
 412 static struct xt_target notrack_tg_reg __read_mostly = {
 413         .name           = "NOTRACK",
 414         .revision       = 0,
 415         .family         = NFPROTO_UNSPEC,
 416         .checkentry     = notrack_chk,
 417         .target         = notrack_tg,
 418         .table          = "raw",
 419         .me             = THIS_MODULE,
 420 };
 421
 422 static int __init xt_ct_tg_init(void)
 423 {
 424         int ret;
 425
 426         ret = xt_register_target(&notrack_tg_reg);
 427         if (ret < 0)
 428                 return ret;
 429
 430         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 431         if (ret < 0) {
 432                 xt_unregister_target(&notrack_tg_reg);
 433                 return ret;
 434         }
 435         return 0;
 436 }
 437
 438 static void __exit xt_ct_tg_exit(void)
 439 {
 440         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 441         xt_unregister_target(&notrack_tg_reg);
 442 }
 443
 444 module_init(xt_ct_tg_init);
 445 module_exit(xt_ct_tg_exit);
 446
 447 MODULE_LICENSE("GPL");
 448 MODULE_DESCRIPTION("Xtables: connection tracking target");
 449 MODULE_ALIAS("ipt_CT");
 450 MODULE_ALIAS("ip6t_CT");
 451 MODULE_ALIAS("ipt_NOTRACK");
 452 MODULE_ALIAS("ip6t_NOTRACK");