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