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("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                 nf_conntrack_helper_put(helper);
 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         const struct nf_conntrack_l4proto *l4proto;
 125         struct ctnl_timeout *timeout;
 126         struct nf_conn_timeout *timeout_ext;
 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) {
 172                 ret = -ENOMEM;
 173                 goto err_put_timeout;
 174         }
 175
 176         rcu_read_unlock();
 177         return ret;
 178
 179 err_put_timeout:
 180         __xt_ct_tg_timeout_put(timeout);
 181 out:
 182         rcu_read_unlock();
 183         return ret;
 184 #else
 185         return -EOPNOTSUPP;
 186 #endif
 187 }
 188
 189 static u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
 190 {
 191         switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
 192                                XT_CT_ZONE_DIR_REPL)) {
 193         case XT_CT_ZONE_DIR_ORIG:
 194                 return NF_CT_ZONE_DIR_ORIG;
 195         case XT_CT_ZONE_DIR_REPL:
 196                 return NF_CT_ZONE_DIR_REPL;
 197         default:
 198                 return NF_CT_DEFAULT_ZONE_DIR;
 199         }
 200 }
 201
 202 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 203                           struct xt_ct_target_info_v1 *info)
 204 {
 205         struct nf_conntrack_zone zone;
 206         struct nf_conn_help *help;
 207         struct nf_conn *ct;
 208         int ret = -EOPNOTSUPP;
 209
 210         if (info->flags & XT_CT_NOTRACK) {
 211                 ct = NULL;
 212                 goto out;
 213         }
 214
 215 #ifndef CONFIG_NF_CONNTRACK_ZONES
 216         if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
 217                                          XT_CT_ZONE_DIR_REPL |
 218                                          XT_CT_ZONE_MARK))
 219                 goto err1;
 220 #endif
 221
 222         ret = nf_ct_netns_get(par->net, par->family);
 223         if (ret < 0)
 224                 goto err1;
 225
 226         memset(&zone, 0, sizeof(zone));
 227         zone.id = info->zone;
 228         zone.dir = xt_ct_flags_to_dir(info);
 229         if (info->flags & XT_CT_ZONE_MARK)
 230                 zone.flags |= NF_CT_FLAG_MARK;
 231
 232         ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
 233         if (!ct) {
 234                 ret = -ENOMEM;
 235                 goto err2;
 236         }
 237
 238         ret = 0;
 239         if ((info->ct_events || info->exp_events) &&
 240             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 241                                   GFP_KERNEL)) {
 242                 ret = -EINVAL;
 243                 goto err3;
 244         }
 245
 246         if (info->helper[0]) {
 247                 ret = xt_ct_set_helper(ct, info->helper, par);
 248                 if (ret < 0)
 249                         goto err3;
 250         }
 251
 252         if (info->timeout[0]) {
 253                 ret = xt_ct_set_timeout(ct, par, info->timeout);
 254                 if (ret < 0)
 255                         goto err4;
 256         }
 257         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 258         nf_conntrack_get(&ct->ct_general);
 259 out:
 260         info->ct = ct;
 261         return 0;
 262
 263 err4:
 264         help = nfct_help(ct);
 265         if (help)
 266                 nf_conntrack_helper_put(help->helper);
 267 err3:
 268         nf_ct_tmpl_free(ct);
 269 err2:
 270         nf_ct_netns_put(par->net, par->family);
 271 err1:
 272         return ret;
 273 }
 274
 275 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
 276 {
 277         struct xt_ct_target_info *info = par->targinfo;
 278         struct xt_ct_target_info_v1 info_v1 = {
 279                 .flags          = info->flags,
 280                 .zone           = info->zone,
 281                 .ct_events      = info->ct_events,
 282                 .exp_events     = info->exp_events,
 283         };
 284         int ret;
 285
 286         if (info->flags & ~XT_CT_NOTRACK)
 287                 return -EINVAL;
 288
 289         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 290
 291         ret = xt_ct_tg_check(par, &info_v1);
 292         if (ret < 0)
 293                 return ret;
 294
 295         info->ct = info_v1.ct;
 296
 297         return ret;
 298 }
 299
 300 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 301 {
 302         struct xt_ct_target_info_v1 *info = par->targinfo;
 303
 304         if (info->flags & ~XT_CT_NOTRACK)
 305                 return -EINVAL;
 306
 307         return xt_ct_tg_check(par, par->targinfo);
 308 }
 309
 310 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
 311 {
 312         struct xt_ct_target_info_v1 *info = par->targinfo;
 313
 314         if (info->flags & ~XT_CT_MASK)
 315                 return -EINVAL;
 316
 317         return xt_ct_tg_check(par, par->targinfo);
 318 }
 319
 320 static void xt_ct_destroy_timeout(struct nf_conn *ct)
 321 {
 322 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 323         struct nf_conn_timeout *timeout_ext;
 324         typeof(nf_ct_timeout_put_hook) timeout_put;
 325
 326         rcu_read_lock();
 327         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 328
 329         if (timeout_put) {
 330                 timeout_ext = nf_ct_timeout_find(ct);
 331                 if (timeout_ext) {
 332                         timeout_put(timeout_ext->timeout);
 333                         RCU_INIT_POINTER(timeout_ext->timeout, NULL);
 334                 }
 335         }
 336         rcu_read_unlock();
 337 #endif
 338 }
 339
 340 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 341                              struct xt_ct_target_info_v1 *info)
 342 {
 343         struct nf_conn *ct = info->ct;
 344         struct nf_conn_help *help;
 345
 346         if (ct) {
 347                 help = nfct_help(ct);
 348                 if (help)
 349                         nf_conntrack_helper_put(help->helper);
 350
 351                 nf_ct_netns_put(par->net, par->family);
 352
 353                 xt_ct_destroy_timeout(ct);
 354                 nf_ct_put(info->ct);
 355         }
 356 }
 357
 358 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 359 {
 360         struct xt_ct_target_info *info = par->targinfo;
 361         struct xt_ct_target_info_v1 info_v1 = {
 362                 .flags          = info->flags,
 363                 .zone           = info->zone,
 364                 .ct_events      = info->ct_events,
 365                 .exp_events     = info->exp_events,
 366                 .ct             = info->ct,
 367         };
 368         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 369
 370         xt_ct_tg_destroy(par, &info_v1);
 371 }
 372
 373 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 374 {
 375         xt_ct_tg_destroy(par, par->targinfo);
 376 }
 377
 378 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 379         {
 380                 .name           = "CT",
 381                 .family         = NFPROTO_UNSPEC,
 382                 .targetsize     = sizeof(struct xt_ct_target_info),
 383                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 384                 .checkentry     = xt_ct_tg_check_v0,
 385                 .destroy        = xt_ct_tg_destroy_v0,
 386                 .target         = xt_ct_target_v0,
 387                 .table          = "raw",
 388                 .me             = THIS_MODULE,
 389         },
 390         {
 391                 .name           = "CT",
 392                 .family         = NFPROTO_UNSPEC,
 393                 .revision       = 1,
 394                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 395                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 396                 .checkentry     = xt_ct_tg_check_v1,
 397                 .destroy        = xt_ct_tg_destroy_v1,
 398                 .target         = xt_ct_target_v1,
 399                 .table          = "raw",
 400                 .me             = THIS_MODULE,
 401         },
 402         {
 403                 .name           = "CT",
 404                 .family         = NFPROTO_UNSPEC,
 405                 .revision       = 2,
 406                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 407                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 408                 .checkentry     = xt_ct_tg_check_v2,
 409                 .destroy        = xt_ct_tg_destroy_v1,
 410                 .target         = xt_ct_target_v1,
 411                 .table          = "raw",
 412                 .me             = THIS_MODULE,
 413         },
 414 };
 415
 416 static unsigned int
 417 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 418 {
 419         /* Previously seen (loopback)? Ignore. */
 420         if (skb->_nfct != 0)
 421                 return XT_CONTINUE;
 422
 423         nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 424
 425         return XT_CONTINUE;
 426 }
 427
 428 static int notrack_chk(const struct xt_tgchk_param *par)
 429 {
 430         if (!par->net->xt.notrack_deprecated_warning) {
 431                 pr_info("netfilter: NOTRACK target is deprecated, "
 432                         "use CT instead or upgrade iptables\n");
 433                 par->net->xt.notrack_deprecated_warning = true;
 434         }
 435         return 0;
 436 }
 437
 438 static struct xt_target notrack_tg_reg __read_mostly = {
 439         .name           = "NOTRACK",
 440         .revision       = 0,
 441         .family         = NFPROTO_UNSPEC,
 442         .checkentry     = notrack_chk,
 443         .target         = notrack_tg,
 444         .table          = "raw",
 445         .me             = THIS_MODULE,
 446 };
 447
 448 static int __init xt_ct_tg_init(void)
 449 {
 450         int ret;
 451
 452         ret = xt_register_target(&notrack_tg_reg);
 453         if (ret < 0)
 454                 return ret;
 455
 456         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 457         if (ret < 0) {
 458                 xt_unregister_target(&notrack_tg_reg);
 459                 return ret;
 460         }
 461         return 0;
 462 }
 463
 464 static void __exit xt_ct_tg_exit(void)
 465 {
 466         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 467         xt_unregister_target(&notrack_tg_reg);
 468 }
 469
 470 module_init(xt_ct_tg_init);
 471 module_exit(xt_ct_tg_exit);
 472
 473 MODULE_LICENSE("GPL");
 474 MODULE_DESCRIPTION("Xtables: connection tracking target");
 475 MODULE_ALIAS("ipt_CT");
 476 MODULE_ALIAS("ip6t_CT");
 477 MODULE_ALIAS("ipt_NOTRACK");
 478 MODULE_ALIAS("ip6t_NOTRACK");