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 inline int xt_ct_target(struct sk_buff *skb, struct nf_conn *ct)
  24 {
  25         /* Previously seen (loopback)? Ignore. */
  26         if (skb->nfct != NULL)
  27                 return XT_CONTINUE;
  28
  29         /* special case the untracked ct : we want the percpu object */
  30         if (!ct)
  31                 ct = nf_ct_untracked_get();
  32         atomic_inc(&ct->ct_general.use);
  33         skb->nfct = &ct->ct_general;
  34         skb->nfctinfo = IP_CT_NEW;
  35
  36         return XT_CONTINUE;
  37 }
  38
  39 static unsigned int xt_ct_target_v0(struct sk_buff *skb,
  40                                     const struct xt_action_param *par)
  41 {
  42         const struct xt_ct_target_info *info = par->targinfo;
  43         struct nf_conn *ct = info->ct;
  44
  45         return xt_ct_target(skb, ct);
  46 }
  47
  48 static unsigned int xt_ct_target_v1(struct sk_buff *skb,
  49                                     const struct xt_action_param *par)
  50 {
  51         const struct xt_ct_target_info_v1 *info = par->targinfo;
  52         struct nf_conn *ct = info->ct;
  53
  54         return xt_ct_target(skb, ct);
  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 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 108 static void __xt_ct_tg_timeout_put(struct ctnl_timeout *timeout)
 109 {
 110         typeof(nf_ct_timeout_put_hook) timeout_put;
 111
 112         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 113         if (timeout_put)
 114                 timeout_put(timeout);
 115 }
 116 #endif
 117
 118 static int
 119 xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
 120                   const char *timeout_name)
 121 {
 122 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 123         typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
 124         struct ctnl_timeout *timeout;
 125         struct nf_conn_timeout *timeout_ext;
 126         struct nf_conntrack_l4proto *l4proto;
 127         int ret = 0;
 128         u8 proto;
 129
 130         rcu_read_lock();
 131         timeout_find_get = rcu_dereference(nf_ct_timeout_find_get_hook);
 132         if (timeout_find_get == NULL) {
 133                 ret = -ENOENT;
 134                 pr_info("Timeout policy base is empty\n");
 135                 goto out;
 136         }
 137
 138         proto = xt_ct_find_proto(par);
 139         if (!proto) {
 140                 ret = -EINVAL;
 141                 pr_info("You must specify a L4 protocol, and not use "
 142                         "inversions on it.\n");
 143                 goto out;
 144         }
 145
 146         timeout = timeout_find_get(timeout_name);
 147         if (timeout == NULL) {
 148                 ret = -ENOENT;
 149                 pr_info("No such timeout policy \"%s\"\n", timeout_name);
 150                 goto out;
 151         }
 152
 153         if (timeout->l3num != par->family) {
 154                 ret = -EINVAL;
 155                 pr_info("Timeout policy `%s' can only be used by L3 protocol "
 156                         "number %d\n", timeout_name, timeout->l3num);
 157                 goto err_put_timeout;
 158         }
 159         /* Make sure the timeout policy matches any existing protocol tracker,
 160          * otherwise default to generic.
 161          */
 162         l4proto = __nf_ct_l4proto_find(par->family, proto);
 163         if (timeout->l4proto->l4proto != l4proto->l4proto) {
 164                 ret = -EINVAL;
 165                 pr_info("Timeout policy `%s' can only be used by L4 protocol "
 166                         "number %d\n",
 167                         timeout_name, timeout->l4proto->l4proto);
 168                 goto err_put_timeout;
 169         }
 170         timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
 171         if (timeout_ext == NULL)
 172                 ret = -ENOMEM;
 173
 174 err_put_timeout:
 175         __xt_ct_tg_timeout_put(timeout);
 176 out:
 177         rcu_read_unlock();
 178         return ret;
 179 #else
 180         return -EOPNOTSUPP;
 181 #endif
 182 }
 183
 184 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 185                           struct xt_ct_target_info_v1 *info)
 186 {
 187         struct nf_conntrack_tuple t;
 188         struct nf_conn *ct;
 189         int ret = -EOPNOTSUPP;
 190
 191         if (info->flags & XT_CT_NOTRACK) {
 192                 ct = NULL;
 193                 goto out;
 194         }
 195
 196 #ifndef CONFIG_NF_CONNTRACK_ZONES
 197         if (info->zone)
 198                 goto err1;
 199 #endif
 200
 201         ret = nf_ct_l3proto_try_module_get(par->family);
 202         if (ret < 0)
 203                 goto err1;
 204
 205         memset(&t, 0, sizeof(t));
 206         ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
 207         ret = PTR_ERR(ct);
 208         if (IS_ERR(ct))
 209                 goto err2;
 210
 211         ret = 0;
 212         if ((info->ct_events || info->exp_events) &&
 213             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 214                                   GFP_KERNEL))
 215                 goto err3;
 216
 217         if (info->helper[0]) {
 218                 ret = xt_ct_set_helper(ct, info->helper, par);
 219                 if (ret < 0)
 220                         goto err3;
 221         }
 222
 223         if (info->timeout[0]) {
 224                 ret = xt_ct_set_timeout(ct, par, info->timeout);
 225                 if (ret < 0)
 226                         goto err3;
 227         }
 228
 229         __set_bit(IPS_TEMPLATE_BIT, &ct->status);
 230         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 231
 232         /* Overload tuple linked list to put us in template list. */
 233         hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
 234                                  &par->net->ct.tmpl);
 235 out:
 236         info->ct = ct;
 237         return 0;
 238
 239 err3:
 240         nf_conntrack_free(ct);
 241 err2:
 242         nf_ct_l3proto_module_put(par->family);
 243 err1:
 244         return ret;
 245 }
 246
 247 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
 248 {
 249         struct xt_ct_target_info *info = par->targinfo;
 250         struct xt_ct_target_info_v1 info_v1 = {
 251                 .flags          = info->flags,
 252                 .zone           = info->zone,
 253                 .ct_events      = info->ct_events,
 254                 .exp_events     = info->exp_events,
 255         };
 256         int ret;
 257
 258         if (info->flags & ~XT_CT_NOTRACK)
 259                 return -EINVAL;
 260
 261         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 262
 263         ret = xt_ct_tg_check(par, &info_v1);
 264         if (ret < 0)
 265                 return ret;
 266
 267         info->ct = info_v1.ct;
 268
 269         return ret;
 270 }
 271
 272 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 273 {
 274         struct xt_ct_target_info_v1 *info = par->targinfo;
 275
 276         if (info->flags & ~XT_CT_NOTRACK)
 277                 return -EINVAL;
 278
 279         return xt_ct_tg_check(par, par->targinfo);
 280 }
 281
 282 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
 283 {
 284         struct xt_ct_target_info_v1 *info = par->targinfo;
 285
 286         if (info->flags & ~XT_CT_MASK)
 287                 return -EINVAL;
 288
 289         return xt_ct_tg_check(par, par->targinfo);
 290 }
 291
 292 static void xt_ct_destroy_timeout(struct nf_conn *ct)
 293 {
 294 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 295         struct nf_conn_timeout *timeout_ext;
 296         typeof(nf_ct_timeout_put_hook) timeout_put;
 297
 298         rcu_read_lock();
 299         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 300
 301         if (timeout_put) {
 302                 timeout_ext = nf_ct_timeout_find(ct);
 303                 if (timeout_ext)
 304                         timeout_put(timeout_ext->timeout);
 305         }
 306         rcu_read_unlock();
 307 #endif
 308 }
 309
 310 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 311                              struct xt_ct_target_info_v1 *info)
 312 {
 313         struct nf_conn *ct = info->ct;
 314         struct nf_conn_help *help;
 315
 316         if (ct && !nf_ct_is_untracked(ct)) {
 317                 help = nfct_help(ct);
 318                 if (help)
 319                         module_put(help->helper->me);
 320
 321                 nf_ct_l3proto_module_put(par->family);
 322
 323                 xt_ct_destroy_timeout(ct);
 324                 nf_ct_put(info->ct);
 325         }
 326 }
 327
 328 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 329 {
 330         struct xt_ct_target_info *info = par->targinfo;
 331         struct xt_ct_target_info_v1 info_v1 = {
 332                 .flags          = info->flags,
 333                 .zone           = info->zone,
 334                 .ct_events      = info->ct_events,
 335                 .exp_events     = info->exp_events,
 336                 .ct             = info->ct,
 337         };
 338         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 339
 340         xt_ct_tg_destroy(par, &info_v1);
 341 }
 342
 343 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 344 {
 345         xt_ct_tg_destroy(par, par->targinfo);
 346 }
 347
 348 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 349         {
 350                 .name           = "CT",
 351                 .family         = NFPROTO_UNSPEC,
 352                 .targetsize     = sizeof(struct xt_ct_target_info),
 353                 .checkentry     = xt_ct_tg_check_v0,
 354                 .destroy        = xt_ct_tg_destroy_v0,
 355                 .target         = xt_ct_target_v0,
 356                 .table          = "raw",
 357                 .me             = THIS_MODULE,
 358         },
 359         {
 360                 .name           = "CT",
 361                 .family         = NFPROTO_UNSPEC,
 362                 .revision       = 1,
 363                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 364                 .checkentry     = xt_ct_tg_check_v1,
 365                 .destroy        = xt_ct_tg_destroy_v1,
 366                 .target         = xt_ct_target_v1,
 367                 .table          = "raw",
 368                 .me             = THIS_MODULE,
 369         },
 370         {
 371                 .name           = "CT",
 372                 .family         = NFPROTO_UNSPEC,
 373                 .revision       = 2,
 374                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 375                 .checkentry     = xt_ct_tg_check_v2,
 376                 .destroy        = xt_ct_tg_destroy_v1,
 377                 .target         = xt_ct_target_v1,
 378                 .table          = "raw",
 379                 .me             = THIS_MODULE,
 380         },
 381 };
 382
 383 static unsigned int
 384 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 385 {
 386         /* Previously seen (loopback)? Ignore. */
 387         if (skb->nfct != NULL)
 388                 return XT_CONTINUE;
 389
 390         skb->nfct = &nf_ct_untracked_get()->ct_general;
 391         skb->nfctinfo = IP_CT_NEW;
 392         nf_conntrack_get(skb->nfct);
 393
 394         return XT_CONTINUE;
 395 }
 396
 397 static int notrack_chk(const struct xt_tgchk_param *par)
 398 {
 399         if (!par->net->xt.notrack_deprecated_warning) {
 400                 pr_info("netfilter: NOTRACK target is deprecated, "
 401                         "use CT instead or upgrade iptables\n");
 402                 par->net->xt.notrack_deprecated_warning = true;
 403         }
 404         return 0;
 405 }
 406
 407 static struct xt_target notrack_tg_reg __read_mostly = {
 408         .name           = "NOTRACK",
 409         .revision       = 0,
 410         .family         = NFPROTO_UNSPEC,
 411         .checkentry     = notrack_chk,
 412         .target         = notrack_tg,
 413         .table          = "raw",
 414         .me             = THIS_MODULE,
 415 };
 416
 417 static int __init xt_ct_tg_init(void)
 418 {
 419         int ret;
 420
 421         ret = xt_register_target(&notrack_tg_reg);
 422         if (ret < 0)
 423                 return ret;
 424
 425         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 426         if (ret < 0) {
 427                 xt_unregister_target(&notrack_tg_reg);
 428                 return ret;
 429         }
 430         return 0;
 431 }
 432
 433 static void __exit xt_ct_tg_exit(void)
 434 {
 435         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 436         xt_unregister_target(&notrack_tg_reg);
 437 }
 438
 439 module_init(xt_ct_tg_init);
 440 module_exit(xt_ct_tg_exit);
 441
 442 MODULE_LICENSE("GPL");
 443 MODULE_DESCRIPTION("Xtables: connection tracking target");
 444 MODULE_ALIAS("ipt_CT");
 445 MODULE_ALIAS("ip6t_CT");
 446 MODULE_ALIAS("ipt_NOTRACK");
 447 MODULE_ALIAS("ip6t_NOTRACK");