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         atomic_inc(&ct->ct_general.use);
  30         skb->nfct = &ct->ct_general;
  31         skb->nfctinfo = IP_CT_NEW;
  32
  33         return XT_CONTINUE;
  34 }
  35
  36 static unsigned int xt_ct_target_v0(struct sk_buff *skb,
  37                                     const struct xt_action_param *par)
  38 {
  39         const struct xt_ct_target_info *info = par->targinfo;
  40         struct nf_conn *ct = info->ct;
  41
  42         return xt_ct_target(skb, ct);
  43 }
  44
  45 static unsigned int xt_ct_target_v1(struct sk_buff *skb,
  46                                     const struct xt_action_param *par)
  47 {
  48         const struct xt_ct_target_info_v1 *info = par->targinfo;
  49         struct nf_conn *ct = info->ct;
  50
  51         return xt_ct_target(skb, ct);
  52 }
  53
  54 static u8 xt_ct_find_proto(const struct xt_tgchk_param *par)
  55 {
  56         if (par->family == NFPROTO_IPV4) {
  57                 const struct ipt_entry *e = par->entryinfo;
  58
  59                 if (e->ip.invflags & IPT_INV_PROTO)
  60                         return 0;
  61                 return e->ip.proto;
  62         } else if (par->family == NFPROTO_IPV6) {
  63                 const struct ip6t_entry *e = par->entryinfo;
  64
  65                 if (e->ipv6.invflags & IP6T_INV_PROTO)
  66                         return 0;
  67                 return e->ipv6.proto;
  68         } else
  69                 return 0;
  70 }
  71
  72 static int
  73 xt_ct_set_helper(struct nf_conn *ct, const char *helper_name,
  74                  const struct xt_tgchk_param *par)
  75 {
  76         struct nf_conntrack_helper *helper;
  77         struct nf_conn_help *help;
  78         u8 proto;
  79
  80         proto = xt_ct_find_proto(par);
  81         if (!proto) {
  82                 pr_info("You must specify a L4 protocol, and not use "
  83                         "inversions on it.\n");
  84                 return -ENOENT;
  85         }
  86
  87         helper = nf_conntrack_helper_try_module_get(helper_name, par->family,
  88                                                     proto);
  89         if (helper == NULL) {
  90                 pr_info("No such helper \"%s\"\n", helper_name);
  91                 return -ENOENT;
  92         }
  93
  94         help = nf_ct_helper_ext_add(ct, helper, GFP_KERNEL);
  95         if (help == NULL) {
  96                 module_put(helper->me);
  97                 return -ENOMEM;
  98         }
  99
 100         help->helper = helper;
 101         return 0;
 102 }
 103
 104 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 105 static void __xt_ct_tg_timeout_put(struct ctnl_timeout *timeout)
 106 {
 107         typeof(nf_ct_timeout_put_hook) timeout_put;
 108
 109         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 110         if (timeout_put)
 111                 timeout_put(timeout);
 112 }
 113 #endif
 114
 115 static int
 116 xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
 117                   const char *timeout_name)
 118 {
 119 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 120         typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
 121         struct ctnl_timeout *timeout;
 122         struct nf_conn_timeout *timeout_ext;
 123         struct nf_conntrack_l4proto *l4proto;
 124         int ret = 0;
 125         u8 proto;
 126
 127         rcu_read_lock();
 128         timeout_find_get = rcu_dereference(nf_ct_timeout_find_get_hook);
 129         if (timeout_find_get == NULL) {
 130                 ret = -ENOENT;
 131                 pr_info("Timeout policy base is empty\n");
 132                 goto out;
 133         }
 134
 135         proto = xt_ct_find_proto(par);
 136         if (!proto) {
 137                 ret = -EINVAL;
 138                 pr_info("You must specify a L4 protocol, and not use "
 139                         "inversions on it.\n");
 140                 goto out;
 141         }
 142
 143         timeout = timeout_find_get(timeout_name);
 144         if (timeout == NULL) {
 145                 ret = -ENOENT;
 146                 pr_info("No such timeout policy \"%s\"\n", timeout_name);
 147                 goto out;
 148         }
 149
 150         if (timeout->l3num != par->family) {
 151                 ret = -EINVAL;
 152                 pr_info("Timeout policy `%s' can only be used by L3 protocol "
 153                         "number %d\n", timeout_name, timeout->l3num);
 154                 goto err_put_timeout;
 155         }
 156         /* Make sure the timeout policy matches any existing protocol tracker,
 157          * otherwise default to generic.
 158          */
 159         l4proto = __nf_ct_l4proto_find(par->family, proto);
 160         if (timeout->l4proto->l4proto != l4proto->l4proto) {
 161                 ret = -EINVAL;
 162                 pr_info("Timeout policy `%s' can only be used by L4 protocol "
 163                         "number %d\n",
 164                         timeout_name, timeout->l4proto->l4proto);
 165                 goto err_put_timeout;
 166         }
 167         timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
 168         if (timeout_ext == NULL)
 169                 ret = -ENOMEM;
 170
 171 err_put_timeout:
 172         __xt_ct_tg_timeout_put(timeout);
 173 out:
 174         rcu_read_unlock();
 175         return ret;
 176 #else
 177         return -EOPNOTSUPP;
 178 #endif
 179 }
 180
 181 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 182                           struct xt_ct_target_info_v1 *info)
 183 {
 184         struct nf_conntrack_tuple t;
 185         struct nf_conn *ct;
 186         int ret = -EOPNOTSUPP;
 187
 188         if (info->flags & XT_CT_NOTRACK) {
 189                 ct = nf_ct_untracked_get();
 190                 atomic_inc(&ct->ct_general.use);
 191                 goto out;
 192         }
 193
 194 #ifndef CONFIG_NF_CONNTRACK_ZONES
 195         if (info->zone)
 196                 goto err1;
 197 #endif
 198
 199         ret = nf_ct_l3proto_try_module_get(par->family);
 200         if (ret < 0)
 201                 goto err1;
 202
 203         memset(&t, 0, sizeof(t));
 204         ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
 205         ret = PTR_ERR(ct);
 206         if (IS_ERR(ct))
 207                 goto err2;
 208
 209         ret = 0;
 210         if ((info->ct_events || info->exp_events) &&
 211             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 212                                   GFP_KERNEL))
 213                 goto err3;
 214
 215         if (info->helper[0]) {
 216                 ret = xt_ct_set_helper(ct, info->helper, par);
 217                 if (ret < 0)
 218                         goto err3;
 219         }
 220
 221         if (info->timeout[0]) {
 222                 ret = xt_ct_set_timeout(ct, par, info->timeout);
 223                 if (ret < 0)
 224                         goto err3;
 225         }
 226
 227         __set_bit(IPS_TEMPLATE_BIT, &ct->status);
 228         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 229
 230         /* Overload tuple linked list to put us in template list. */
 231         hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
 232                                  &par->net->ct.tmpl);
 233 out:
 234         info->ct = ct;
 235         return 0;
 236
 237 err3:
 238         nf_conntrack_free(ct);
 239 err2:
 240         nf_ct_l3proto_module_put(par->family);
 241 err1:
 242         return ret;
 243 }
 244
 245 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
 246 {
 247         struct xt_ct_target_info *info = par->targinfo;
 248         struct xt_ct_target_info_v1 info_v1 = {
 249                 .flags          = info->flags,
 250                 .zone           = info->zone,
 251                 .ct_events      = info->ct_events,
 252                 .exp_events     = info->exp_events,
 253         };
 254         int ret;
 255
 256         if (info->flags & ~XT_CT_NOTRACK)
 257                 return -EINVAL;
 258
 259         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 260
 261         ret = xt_ct_tg_check(par, &info_v1);
 262         if (ret < 0)
 263                 return ret;
 264
 265         info->ct = info_v1.ct;
 266
 267         return ret;
 268 }
 269
 270 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 271 {
 272         struct xt_ct_target_info_v1 *info = par->targinfo;
 273
 274         if (info->flags & ~XT_CT_NOTRACK)
 275                 return -EINVAL;
 276
 277         return xt_ct_tg_check(par, par->targinfo);
 278 }
 279
 280 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
 281 {
 282         struct xt_ct_target_info_v1 *info = par->targinfo;
 283
 284         if (info->flags & ~XT_CT_MASK)
 285                 return -EINVAL;
 286
 287         return xt_ct_tg_check(par, par->targinfo);
 288 }
 289
 290 static void xt_ct_destroy_timeout(struct nf_conn *ct)
 291 {
 292 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 293         struct nf_conn_timeout *timeout_ext;
 294         typeof(nf_ct_timeout_put_hook) timeout_put;
 295
 296         rcu_read_lock();
 297         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 298
 299         if (timeout_put) {
 300                 timeout_ext = nf_ct_timeout_find(ct);
 301                 if (timeout_ext)
 302                         timeout_put(timeout_ext->timeout);
 303         }
 304         rcu_read_unlock();
 305 #endif
 306 }
 307
 308 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 309                              struct xt_ct_target_info_v1 *info)
 310 {
 311         struct nf_conn *ct = info->ct;
 312         struct nf_conn_help *help;
 313
 314         if (!nf_ct_is_untracked(ct)) {
 315                 help = nfct_help(ct);
 316                 if (help)
 317                         module_put(help->helper->me);
 318
 319                 nf_ct_l3proto_module_put(par->family);
 320
 321                 xt_ct_destroy_timeout(ct);
 322         }
 323         nf_ct_put(info->ct);
 324 }
 325
 326 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 327 {
 328         struct xt_ct_target_info *info = par->targinfo;
 329         struct xt_ct_target_info_v1 info_v1 = {
 330                 .flags          = info->flags,
 331                 .zone           = info->zone,
 332                 .ct_events      = info->ct_events,
 333                 .exp_events     = info->exp_events,
 334                 .ct             = info->ct,
 335         };
 336         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 337
 338         xt_ct_tg_destroy(par, &info_v1);
 339 }
 340
 341 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 342 {
 343         xt_ct_tg_destroy(par, par->targinfo);
 344 }
 345
 346 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 347         {
 348                 .name           = "CT",
 349                 .family         = NFPROTO_UNSPEC,
 350                 .targetsize     = sizeof(struct xt_ct_target_info),
 351                 .checkentry     = xt_ct_tg_check_v0,
 352                 .destroy        = xt_ct_tg_destroy_v0,
 353                 .target         = xt_ct_target_v0,
 354                 .table          = "raw",
 355                 .me             = THIS_MODULE,
 356         },
 357         {
 358                 .name           = "CT",
 359                 .family         = NFPROTO_UNSPEC,
 360                 .revision       = 1,
 361                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 362                 .checkentry     = xt_ct_tg_check_v1,
 363                 .destroy        = xt_ct_tg_destroy_v1,
 364                 .target         = xt_ct_target_v1,
 365                 .table          = "raw",
 366                 .me             = THIS_MODULE,
 367         },
 368         {
 369                 .name           = "CT",
 370                 .family         = NFPROTO_UNSPEC,
 371                 .revision       = 2,
 372                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 373                 .checkentry     = xt_ct_tg_check_v2,
 374                 .destroy        = xt_ct_tg_destroy_v1,
 375                 .target         = xt_ct_target_v1,
 376                 .table          = "raw",
 377                 .me             = THIS_MODULE,
 378         },
 379 };
 380
 381 static unsigned int
 382 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 383 {
 384         /* Previously seen (loopback)? Ignore. */
 385         if (skb->nfct != NULL)
 386                 return XT_CONTINUE;
 387
 388         skb->nfct = &nf_ct_untracked_get()->ct_general;
 389         skb->nfctinfo = IP_CT_NEW;
 390         nf_conntrack_get(skb->nfct);
 391
 392         return XT_CONTINUE;
 393 }
 394
 395 static int notrack_chk(const struct xt_tgchk_param *par)
 396 {
 397         if (!par->net->xt.notrack_deprecated_warning) {
 398                 pr_info("netfilter: NOTRACK target is deprecated, "
 399                         "use CT instead or upgrade iptables\n");
 400                 par->net->xt.notrack_deprecated_warning = true;
 401         }
 402         return 0;
 403 }
 404
 405 static struct xt_target notrack_tg_reg __read_mostly = {
 406         .name           = "NOTRACK",
 407         .revision       = 0,
 408         .family         = NFPROTO_UNSPEC,
 409         .checkentry     = notrack_chk,
 410         .target         = notrack_tg,
 411         .table          = "raw",
 412         .me             = THIS_MODULE,
 413 };
 414
 415 static int __init xt_ct_tg_init(void)
 416 {
 417         int ret;
 418
 419         ret = xt_register_target(&notrack_tg_reg);
 420         if (ret < 0)
 421                 return ret;
 422
 423         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 424         if (ret < 0) {
 425                 xt_unregister_target(&notrack_tg_reg);
 426                 return ret;
 427         }
 428         return 0;
 429 }
 430
 431 static void __exit xt_ct_tg_exit(void)
 432 {
 433         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 434         xt_unregister_target(&notrack_tg_reg);
 435 }
 436
 437 module_init(xt_ct_tg_init);
 438 module_exit(xt_ct_tg_exit);
 439
 440 MODULE_LICENSE("GPL");
 441 MODULE_DESCRIPTION("Xtables: connection tracking target");
 442 MODULE_ALIAS("ipt_CT");
 443 MODULE_ALIAS("ip6t_CT");
 444 MODULE_ALIAS("ipt_NOTRACK");
 445 MODULE_ALIAS("ip6t_NOTRACK");