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 != 0)
  27                 return XT_CONTINUE;
  28
  29         if (ct) {
  30                 atomic_inc(&ct->ct_general.use);
  31                 nf_ct_set(skb, ct, IP_CT_NEW);
  32         } else {
  33                 nf_ct_set(skb, ct, IP_CT_UNTRACKED);
  34         }
  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_ratelimited("You must specify a L4 protocol and not use inversions on it\n");
  86                 return -ENOENT;
  87         }
  88
  89         helper = nf_conntrack_helper_try_module_get(helper_name, par->family,
  90                                                     proto);
  91         if (helper == NULL) {
  92                 pr_info_ratelimited("No such helper \"%s\"\n", helper_name);
  93                 return -ENOENT;
  94         }
  95
  96         help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
  97         if (help == NULL) {
  98                 nf_conntrack_helper_put(helper);
  99                 return -ENOMEM;
 100         }
 101
 102         help->helper = helper;
 103         return 0;
 104 }
 105
 106 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 107 static void __xt_ct_tg_timeout_put(struct nf_ct_timeout *timeout)
 108 {
 109         typeof(nf_ct_timeout_put_hook) timeout_put;
 110
 111         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 112         if (timeout_put)
 113                 timeout_put(timeout);
 114 }
 115 #endif
 116
 117 static int
 118 xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
 119                   const char *timeout_name)
 120 {
 121 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 122         typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
 123         const struct nf_conntrack_l4proto *l4proto;
 124         struct nf_ct_timeout *timeout;
 125         struct nf_conn_timeout *timeout_ext;
 126         const char *errmsg = NULL;
 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                 errmsg = "Timeout policy base is empty";
 135                 goto out;
 136         }
 137
 138         proto = xt_ct_find_proto(par);
 139         if (!proto) {
 140                 ret = -EINVAL;
 141                 errmsg = "You must specify a L4 protocol and not use inversions on it";
 142                 goto out;
 143         }
 144
 145         timeout = timeout_find_get(par->net, timeout_name);
 146         if (timeout == NULL) {
 147                 ret = -ENOENT;
 148                 pr_info_ratelimited("No such timeout policy \"%s\"\n",
 149                                     timeout_name);
 150                 goto out;
 151         }
 152
 153         if (timeout->l3num != par->family) {
 154                 ret = -EINVAL;
 155                 pr_info_ratelimited("Timeout policy `%s' can only be used by L%d protocol number %d\n",
 156                                     timeout_name, 3, 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(proto);
 163         if (timeout->l4proto->l4proto != l4proto->l4proto) {
 164                 ret = -EINVAL;
 165                 pr_info_ratelimited("Timeout policy `%s' can only be used by L%d protocol number %d\n",
 166                                     timeout_name, 4, timeout->l4proto->l4proto);
 167                 goto err_put_timeout;
 168         }
 169         timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
 170         if (!timeout_ext) {
 171                 ret = -ENOMEM;
 172                 goto err_put_timeout;
 173         }
 174
 175         rcu_read_unlock();
 176         return ret;
 177
 178 err_put_timeout:
 179         __xt_ct_tg_timeout_put(timeout);
 180 out:
 181         rcu_read_unlock();
 182         if (errmsg)
 183                 pr_info_ratelimited("%s\n", errmsg);
 184         return ret;
 185 #else
 186         return -EOPNOTSUPP;
 187 #endif
 188 }
 189
 190 static u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
 191 {
 192         switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
 193                                XT_CT_ZONE_DIR_REPL)) {
 194         case XT_CT_ZONE_DIR_ORIG:
 195                 return NF_CT_ZONE_DIR_ORIG;
 196         case XT_CT_ZONE_DIR_REPL:
 197                 return NF_CT_ZONE_DIR_REPL;
 198         default:
 199                 return NF_CT_DEFAULT_ZONE_DIR;
 200         }
 201 }
 202
 203 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 204                           struct xt_ct_target_info_v1 *info)
 205 {
 206         struct nf_conntrack_zone zone;
 207         struct nf_conn_help *help;
 208         struct nf_conn *ct;
 209         int ret = -EOPNOTSUPP;
 210
 211         if (info->flags & XT_CT_NOTRACK) {
 212                 ct = NULL;
 213                 goto out;
 214         }
 215
 216 #ifndef CONFIG_NF_CONNTRACK_ZONES
 217         if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
 218                                          XT_CT_ZONE_DIR_REPL |
 219                                          XT_CT_ZONE_MARK))
 220                 goto err1;
 221 #endif
 222
 223         ret = nf_ct_netns_get(par->net, par->family);
 224         if (ret < 0)
 225                 goto err1;
 226
 227         memset(&zone, 0, sizeof(zone));
 228         zone.id = info->zone;
 229         zone.dir = xt_ct_flags_to_dir(info);
 230         if (info->flags & XT_CT_ZONE_MARK)
 231                 zone.flags |= NF_CT_FLAG_MARK;
 232
 233         ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
 234         if (!ct) {
 235                 ret = -ENOMEM;
 236                 goto err2;
 237         }
 238
 239         ret = 0;
 240         if ((info->ct_events || info->exp_events) &&
 241             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 242                                   GFP_KERNEL)) {
 243                 ret = -EINVAL;
 244                 goto err3;
 245         }
 246
 247         if (info->helper[0]) {
 248                 if (strnlen(info->helper, sizeof(info->helper)) == sizeof(info->helper)) {
 249                         ret = -ENAMETOOLONG;
 250                         goto err3;
 251                 }
 252
 253                 ret = xt_ct_set_helper(ct, info->helper, par);
 254                 if (ret < 0)
 255                         goto err3;
 256         }
 257
 258         if (info->timeout[0]) {
 259                 if (strnlen(info->timeout, sizeof(info->timeout)) == sizeof(info->timeout)) {
 260                         ret = -ENAMETOOLONG;
 261                         goto err4;
 262                 }
 263
 264                 ret = xt_ct_set_timeout(ct, par, info->timeout);
 265                 if (ret < 0)
 266                         goto err4;
 267         }
 268         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 269         nf_conntrack_get(&ct->ct_general);
 270 out:
 271         info->ct = ct;
 272         return 0;
 273
 274 err4:
 275         help = nfct_help(ct);
 276         if (help)
 277                 nf_conntrack_helper_put(help->helper);
 278 err3:
 279         nf_ct_tmpl_free(ct);
 280 err2:
 281         nf_ct_netns_put(par->net, par->family);
 282 err1:
 283         return ret;
 284 }
 285
 286 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
 287 {
 288         struct xt_ct_target_info *info = par->targinfo;
 289         struct xt_ct_target_info_v1 info_v1 = {
 290                 .flags          = info->flags,
 291                 .zone           = info->zone,
 292                 .ct_events      = info->ct_events,
 293                 .exp_events     = info->exp_events,
 294         };
 295         int ret;
 296
 297         if (info->flags & ~XT_CT_NOTRACK)
 298                 return -EINVAL;
 299
 300         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 301
 302         ret = xt_ct_tg_check(par, &info_v1);
 303         if (ret < 0)
 304                 return ret;
 305
 306         info->ct = info_v1.ct;
 307
 308         return ret;
 309 }
 310
 311 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 312 {
 313         struct xt_ct_target_info_v1 *info = par->targinfo;
 314
 315         if (info->flags & ~XT_CT_NOTRACK)
 316                 return -EINVAL;
 317
 318         return xt_ct_tg_check(par, par->targinfo);
 319 }
 320
 321 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
 322 {
 323         struct xt_ct_target_info_v1 *info = par->targinfo;
 324
 325         if (info->flags & ~XT_CT_MASK)
 326                 return -EINVAL;
 327
 328         return xt_ct_tg_check(par, par->targinfo);
 329 }
 330
 331 static void xt_ct_destroy_timeout(struct nf_conn *ct)
 332 {
 333 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 334         struct nf_conn_timeout *timeout_ext;
 335         typeof(nf_ct_timeout_put_hook) timeout_put;
 336
 337         rcu_read_lock();
 338         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 339
 340         if (timeout_put) {
 341                 timeout_ext = nf_ct_timeout_find(ct);
 342                 if (timeout_ext) {
 343                         timeout_put(timeout_ext->timeout);
 344                         RCU_INIT_POINTER(timeout_ext->timeout, NULL);
 345                 }
 346         }
 347         rcu_read_unlock();
 348 #endif
 349 }
 350
 351 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 352                              struct xt_ct_target_info_v1 *info)
 353 {
 354         struct nf_conn *ct = info->ct;
 355         struct nf_conn_help *help;
 356
 357         if (ct) {
 358                 help = nfct_help(ct);
 359                 if (help)
 360                         nf_conntrack_helper_put(help->helper);
 361
 362                 nf_ct_netns_put(par->net, par->family);
 363
 364                 xt_ct_destroy_timeout(ct);
 365                 nf_ct_put(info->ct);
 366         }
 367 }
 368
 369 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 370 {
 371         struct xt_ct_target_info *info = par->targinfo;
 372         struct xt_ct_target_info_v1 info_v1 = {
 373                 .flags          = info->flags,
 374                 .zone           = info->zone,
 375                 .ct_events      = info->ct_events,
 376                 .exp_events     = info->exp_events,
 377                 .ct             = info->ct,
 378         };
 379         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 380
 381         xt_ct_tg_destroy(par, &info_v1);
 382 }
 383
 384 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 385 {
 386         xt_ct_tg_destroy(par, par->targinfo);
 387 }
 388
 389 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 390         {
 391                 .name           = "CT",
 392                 .family         = NFPROTO_UNSPEC,
 393                 .targetsize     = sizeof(struct xt_ct_target_info),
 394                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 395                 .checkentry     = xt_ct_tg_check_v0,
 396                 .destroy        = xt_ct_tg_destroy_v0,
 397                 .target         = xt_ct_target_v0,
 398                 .table          = "raw",
 399                 .me             = THIS_MODULE,
 400         },
 401         {
 402                 .name           = "CT",
 403                 .family         = NFPROTO_UNSPEC,
 404                 .revision       = 1,
 405                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 406                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 407                 .checkentry     = xt_ct_tg_check_v1,
 408                 .destroy        = xt_ct_tg_destroy_v1,
 409                 .target         = xt_ct_target_v1,
 410                 .table          = "raw",
 411                 .me             = THIS_MODULE,
 412         },
 413         {
 414                 .name           = "CT",
 415                 .family         = NFPROTO_UNSPEC,
 416                 .revision       = 2,
 417                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 418                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 419                 .checkentry     = xt_ct_tg_check_v2,
 420                 .destroy        = xt_ct_tg_destroy_v1,
 421                 .target         = xt_ct_target_v1,
 422                 .table          = "raw",
 423                 .me             = THIS_MODULE,
 424         },
 425 };
 426
 427 static unsigned int
 428 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 429 {
 430         /* Previously seen (loopback)? Ignore. */
 431         if (skb->_nfct != 0)
 432                 return XT_CONTINUE;
 433
 434         nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 435
 436         return XT_CONTINUE;
 437 }
 438
 439 static int notrack_chk(const struct xt_tgchk_param *par)
 440 {
 441         if (!par->net->xt.notrack_deprecated_warning) {
 442                 pr_info("netfilter: NOTRACK target is deprecated, "
 443                         "use CT instead or upgrade iptables\n");
 444                 par->net->xt.notrack_deprecated_warning = true;
 445         }
 446         return 0;
 447 }
 448
 449 static struct xt_target notrack_tg_reg __read_mostly = {
 450         .name           = "NOTRACK",
 451         .revision       = 0,
 452         .family         = NFPROTO_UNSPEC,
 453         .checkentry     = notrack_chk,
 454         .target         = notrack_tg,
 455         .table          = "raw",
 456         .me             = THIS_MODULE,
 457 };
 458
 459 static int __init xt_ct_tg_init(void)
 460 {
 461         int ret;
 462
 463         ret = xt_register_target(&notrack_tg_reg);
 464         if (ret < 0)
 465                 return ret;
 466
 467         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 468         if (ret < 0) {
 469                 xt_unregister_target(&notrack_tg_reg);
 470                 return ret;
 471         }
 472         return 0;
 473 }
 474
 475 static void __exit xt_ct_tg_exit(void)
 476 {
 477         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 478         xt_unregister_target(&notrack_tg_reg);
 479 }
 480
 481 module_init(xt_ct_tg_init);
 482 module_exit(xt_ct_tg_exit);
 483
 484 MODULE_LICENSE("GPL");
 485 MODULE_DESCRIPTION("Xtables: connection tracking target");
 486 MODULE_ALIAS("ipt_CT");
 487 MODULE_ALIAS("ip6t_CT");
 488 MODULE_ALIAS("ipt_NOTRACK");
 489 MODULE_ALIAS("ip6t_NOTRACK");