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(par->net, 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         rcu_read_unlock();
 175         return ret;
 176
 177 err_put_timeout:
 178         __xt_ct_tg_timeout_put(timeout);
 179 out:
 180         rcu_read_unlock();
 181         return ret;
 182 #else
 183         return -EOPNOTSUPP;
 184 #endif
 185 }
 186
 187 static u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
 188 {
 189         switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
 190                                XT_CT_ZONE_DIR_REPL)) {
 191         case XT_CT_ZONE_DIR_ORIG:
 192                 return NF_CT_ZONE_DIR_ORIG;
 193         case XT_CT_ZONE_DIR_REPL:
 194                 return NF_CT_ZONE_DIR_REPL;
 195         default:
 196                 return NF_CT_DEFAULT_ZONE_DIR;
 197         }
 198 }
 199
 200 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 201                           struct xt_ct_target_info_v1 *info)
 202 {
 203         struct nf_conntrack_zone zone;
 204         struct nf_conn *ct;
 205         int ret = -EOPNOTSUPP;
 206
 207         if (info->flags & XT_CT_NOTRACK) {
 208                 ct = NULL;
 209                 goto out;
 210         }
 211
 212 #ifndef CONFIG_NF_CONNTRACK_ZONES
 213         if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
 214                                          XT_CT_ZONE_DIR_REPL |
 215                                          XT_CT_ZONE_MARK))
 216                 goto err1;
 217 #endif
 218
 219         ret = nf_ct_l3proto_try_module_get(par->family);
 220         if (ret < 0)
 221                 goto err1;
 222
 223         memset(&zone, 0, sizeof(zone));
 224         zone.id = info->zone;
 225         zone.dir = xt_ct_flags_to_dir(info);
 226         if (info->flags & XT_CT_ZONE_MARK)
 227                 zone.flags |= NF_CT_FLAG_MARK;
 228
 229         ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
 230         if (!ct) {
 231                 ret = -ENOMEM;
 232                 goto err2;
 233         }
 234
 235         ret = 0;
 236         if ((info->ct_events || info->exp_events) &&
 237             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 238                                   GFP_KERNEL)) {
 239                 ret = -EINVAL;
 240                 goto err3;
 241         }
 242
 243         if (info->helper[0]) {
 244                 ret = xt_ct_set_helper(ct, info->helper, par);
 245                 if (ret < 0)
 246                         goto err3;
 247         }
 248
 249         if (info->timeout[0]) {
 250                 ret = xt_ct_set_timeout(ct, par, info->timeout);
 251                 if (ret < 0)
 252                         goto err3;
 253         }
 254         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 255         nf_conntrack_get(&ct->ct_general);
 256 out:
 257         info->ct = ct;
 258         return 0;
 259
 260 err3:
 261         nf_ct_tmpl_free(ct);
 262 err2:
 263         nf_ct_l3proto_module_put(par->family);
 264 err1:
 265         return ret;
 266 }
 267
 268 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
 269 {
 270         struct xt_ct_target_info *info = par->targinfo;
 271         struct xt_ct_target_info_v1 info_v1 = {
 272                 .flags          = info->flags,
 273                 .zone           = info->zone,
 274                 .ct_events      = info->ct_events,
 275                 .exp_events     = info->exp_events,
 276         };
 277         int ret;
 278
 279         if (info->flags & ~XT_CT_NOTRACK)
 280                 return -EINVAL;
 281
 282         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 283
 284         ret = xt_ct_tg_check(par, &info_v1);
 285         if (ret < 0)
 286                 return ret;
 287
 288         info->ct = info_v1.ct;
 289
 290         return ret;
 291 }
 292
 293 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 294 {
 295         struct xt_ct_target_info_v1 *info = par->targinfo;
 296
 297         if (info->flags & ~XT_CT_NOTRACK)
 298                 return -EINVAL;
 299
 300         return xt_ct_tg_check(par, par->targinfo);
 301 }
 302
 303 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
 304 {
 305         struct xt_ct_target_info_v1 *info = par->targinfo;
 306
 307         if (info->flags & ~XT_CT_MASK)
 308                 return -EINVAL;
 309
 310         return xt_ct_tg_check(par, par->targinfo);
 311 }
 312
 313 static void xt_ct_destroy_timeout(struct nf_conn *ct)
 314 {
 315 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 316         struct nf_conn_timeout *timeout_ext;
 317         typeof(nf_ct_timeout_put_hook) timeout_put;
 318
 319         rcu_read_lock();
 320         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 321
 322         if (timeout_put) {
 323                 timeout_ext = nf_ct_timeout_find(ct);
 324                 if (timeout_ext) {
 325                         timeout_put(timeout_ext->timeout);
 326                         RCU_INIT_POINTER(timeout_ext->timeout, NULL);
 327                 }
 328         }
 329         rcu_read_unlock();
 330 #endif
 331 }
 332
 333 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 334                              struct xt_ct_target_info_v1 *info)
 335 {
 336         struct nf_conn *ct = info->ct;
 337         struct nf_conn_help *help;
 338
 339         if (ct && !nf_ct_is_untracked(ct)) {
 340                 help = nfct_help(ct);
 341                 if (help)
 342                         module_put(help->helper->me);
 343
 344                 nf_ct_l3proto_module_put(par->family);
 345
 346                 xt_ct_destroy_timeout(ct);
 347                 nf_ct_put(info->ct);
 348         }
 349 }
 350
 351 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 352 {
 353         struct xt_ct_target_info *info = par->targinfo;
 354         struct xt_ct_target_info_v1 info_v1 = {
 355                 .flags          = info->flags,
 356                 .zone           = info->zone,
 357                 .ct_events      = info->ct_events,
 358                 .exp_events     = info->exp_events,
 359                 .ct             = info->ct,
 360         };
 361         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 362
 363         xt_ct_tg_destroy(par, &info_v1);
 364 }
 365
 366 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 367 {
 368         xt_ct_tg_destroy(par, par->targinfo);
 369 }
 370
 371 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 372         {
 373                 .name           = "CT",
 374                 .family         = NFPROTO_UNSPEC,
 375                 .targetsize     = sizeof(struct xt_ct_target_info),
 376                 .checkentry     = xt_ct_tg_check_v0,
 377                 .destroy        = xt_ct_tg_destroy_v0,
 378                 .target         = xt_ct_target_v0,
 379                 .table          = "raw",
 380                 .me             = THIS_MODULE,
 381         },
 382         {
 383                 .name           = "CT",
 384                 .family         = NFPROTO_UNSPEC,
 385                 .revision       = 1,
 386                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 387                 .checkentry     = xt_ct_tg_check_v1,
 388                 .destroy        = xt_ct_tg_destroy_v1,
 389                 .target         = xt_ct_target_v1,
 390                 .table          = "raw",
 391                 .me             = THIS_MODULE,
 392         },
 393         {
 394                 .name           = "CT",
 395                 .family         = NFPROTO_UNSPEC,
 396                 .revision       = 2,
 397                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 398                 .checkentry     = xt_ct_tg_check_v2,
 399                 .destroy        = xt_ct_tg_destroy_v1,
 400                 .target         = xt_ct_target_v1,
 401                 .table          = "raw",
 402                 .me             = THIS_MODULE,
 403         },
 404 };
 405
 406 static unsigned int
 407 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 408 {
 409         /* Previously seen (loopback)? Ignore. */
 410         if (skb->nfct != NULL)
 411                 return XT_CONTINUE;
 412
 413         skb->nfct = &nf_ct_untracked_get()->ct_general;
 414         skb->nfctinfo = IP_CT_NEW;
 415         nf_conntrack_get(skb->nfct);
 416
 417         return XT_CONTINUE;
 418 }
 419
 420 static int notrack_chk(const struct xt_tgchk_param *par)
 421 {
 422         if (!par->net->xt.notrack_deprecated_warning) {
 423                 pr_info("netfilter: NOTRACK target is deprecated, "
 424                         "use CT instead or upgrade iptables\n");
 425                 par->net->xt.notrack_deprecated_warning = true;
 426         }
 427         return 0;
 428 }
 429
 430 static struct xt_target notrack_tg_reg __read_mostly = {
 431         .name           = "NOTRACK",
 432         .revision       = 0,
 433         .family         = NFPROTO_UNSPEC,
 434         .checkentry     = notrack_chk,
 435         .target         = notrack_tg,
 436         .table          = "raw",
 437         .me             = THIS_MODULE,
 438 };
 439
 440 static int __init xt_ct_tg_init(void)
 441 {
 442         int ret;
 443
 444         ret = xt_register_target(&notrack_tg_reg);
 445         if (ret < 0)
 446                 return ret;
 447
 448         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 449         if (ret < 0) {
 450                 xt_unregister_target(&notrack_tg_reg);
 451                 return ret;
 452         }
 453         return 0;
 454 }
 455
 456 static void __exit xt_ct_tg_exit(void)
 457 {
 458         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 459         xt_unregister_target(&notrack_tg_reg);
 460 }
 461
 462 module_init(xt_ct_tg_init);
 463 module_exit(xt_ct_tg_exit);
 464
 465 MODULE_LICENSE("GPL");
 466 MODULE_DESCRIPTION("Xtables: connection tracking target");
 467 MODULE_ALIAS("ipt_CT");
 468 MODULE_ALIAS("ip6t_CT");
 469 MODULE_ALIAS("ipt_NOTRACK");
 470 MODULE_ALIAS("ip6t_NOTRACK");