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 static int
 107 xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
 108                   const char *timeout_name)
 109 {
 110 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 111         const struct nf_conntrack_l4proto *l4proto;
 112         u8 proto;
 113
 114         proto = xt_ct_find_proto(par);
 115         if (!proto) {
 116                 pr_info_ratelimited("You must specify a L4 protocol and not "
 117                                     "use inversions on it");
 118                 return -EINVAL;
 119         }
 120         l4proto = nf_ct_l4proto_find(proto);
 121         return nf_ct_set_timeout(par->net, ct, par->family, l4proto->l4proto,
 122                                  timeout_name);
 123
 124 #else
 125         return -EOPNOTSUPP;
 126 #endif
 127 }
 128
 129 static u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
 130 {
 131         switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
 132                                XT_CT_ZONE_DIR_REPL)) {
 133         case XT_CT_ZONE_DIR_ORIG:
 134                 return NF_CT_ZONE_DIR_ORIG;
 135         case XT_CT_ZONE_DIR_REPL:
 136                 return NF_CT_ZONE_DIR_REPL;
 137         default:
 138                 return NF_CT_DEFAULT_ZONE_DIR;
 139         }
 140 }
 141
 142 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 143                           struct xt_ct_target_info_v1 *info)
 144 {
 145         struct nf_conntrack_zone zone;
 146         struct nf_conn_help *help;
 147         struct nf_conn *ct;
 148         int ret = -EOPNOTSUPP;
 149
 150         if (info->flags & XT_CT_NOTRACK) {
 151                 ct = NULL;
 152                 goto out;
 153         }
 154
 155 #ifndef CONFIG_NF_CONNTRACK_ZONES
 156         if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
 157                                          XT_CT_ZONE_DIR_REPL |
 158                                          XT_CT_ZONE_MARK))
 159                 goto err1;
 160 #endif
 161
 162         ret = nf_ct_netns_get(par->net, par->family);
 163         if (ret < 0)
 164                 goto err1;
 165
 166         memset(&zone, 0, sizeof(zone));
 167         zone.id = info->zone;
 168         zone.dir = xt_ct_flags_to_dir(info);
 169         if (info->flags & XT_CT_ZONE_MARK)
 170                 zone.flags |= NF_CT_FLAG_MARK;
 171
 172         ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
 173         if (!ct) {
 174                 ret = -ENOMEM;
 175                 goto err2;
 176         }
 177
 178         ret = 0;
 179         if ((info->ct_events || info->exp_events) &&
 180             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 181                                   GFP_KERNEL)) {
 182                 ret = -EINVAL;
 183                 goto err3;
 184         }
 185
 186         if (info->helper[0]) {
 187                 if (strnlen(info->helper, sizeof(info->helper)) == sizeof(info->helper)) {
 188                         ret = -ENAMETOOLONG;
 189                         goto err3;
 190                 }
 191
 192                 ret = xt_ct_set_helper(ct, info->helper, par);
 193                 if (ret < 0)
 194                         goto err3;
 195         }
 196
 197         if (info->timeout[0]) {
 198                 if (strnlen(info->timeout, sizeof(info->timeout)) == sizeof(info->timeout)) {
 199                         ret = -ENAMETOOLONG;
 200                         goto err4;
 201                 }
 202
 203                 ret = xt_ct_set_timeout(ct, par, info->timeout);
 204                 if (ret < 0)
 205                         goto err4;
 206         }
 207         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 208         nf_conntrack_get(&ct->ct_general);
 209 out:
 210         info->ct = ct;
 211         return 0;
 212
 213 err4:
 214         help = nfct_help(ct);
 215         if (help)
 216                 nf_conntrack_helper_put(help->helper);
 217 err3:
 218         nf_ct_tmpl_free(ct);
 219 err2:
 220         nf_ct_netns_put(par->net, par->family);
 221 err1:
 222         return ret;
 223 }
 224
 225 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
 226 {
 227         struct xt_ct_target_info *info = par->targinfo;
 228         struct xt_ct_target_info_v1 info_v1 = {
 229                 .flags          = info->flags,
 230                 .zone           = info->zone,
 231                 .ct_events      = info->ct_events,
 232                 .exp_events     = info->exp_events,
 233         };
 234         int ret;
 235
 236         if (info->flags & ~XT_CT_NOTRACK)
 237                 return -EINVAL;
 238
 239         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 240
 241         ret = xt_ct_tg_check(par, &info_v1);
 242         if (ret < 0)
 243                 return ret;
 244
 245         info->ct = info_v1.ct;
 246
 247         return ret;
 248 }
 249
 250 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 251 {
 252         struct xt_ct_target_info_v1 *info = par->targinfo;
 253
 254         if (info->flags & ~XT_CT_NOTRACK)
 255                 return -EINVAL;
 256
 257         return xt_ct_tg_check(par, par->targinfo);
 258 }
 259
 260 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
 261 {
 262         struct xt_ct_target_info_v1 *info = par->targinfo;
 263
 264         if (info->flags & ~XT_CT_MASK)
 265                 return -EINVAL;
 266
 267         return xt_ct_tg_check(par, par->targinfo);
 268 }
 269
 270 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 271                              struct xt_ct_target_info_v1 *info)
 272 {
 273         struct nf_conn *ct = info->ct;
 274         struct nf_conn_help *help;
 275
 276         if (ct) {
 277                 help = nfct_help(ct);
 278                 if (help)
 279                         nf_conntrack_helper_put(help->helper);
 280
 281                 nf_ct_netns_put(par->net, par->family);
 282
 283                 nf_ct_destroy_timeout(ct);
 284                 nf_ct_put(info->ct);
 285         }
 286 }
 287
 288 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 289 {
 290         struct xt_ct_target_info *info = par->targinfo;
 291         struct xt_ct_target_info_v1 info_v1 = {
 292                 .flags          = info->flags,
 293                 .zone           = info->zone,
 294                 .ct_events      = info->ct_events,
 295                 .exp_events     = info->exp_events,
 296                 .ct             = info->ct,
 297         };
 298         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 299
 300         xt_ct_tg_destroy(par, &info_v1);
 301 }
 302
 303 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 304 {
 305         xt_ct_tg_destroy(par, par->targinfo);
 306 }
 307
 308 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 309         {
 310                 .name           = "CT",
 311                 .family         = NFPROTO_UNSPEC,
 312                 .targetsize     = sizeof(struct xt_ct_target_info),
 313                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 314                 .checkentry     = xt_ct_tg_check_v0,
 315                 .destroy        = xt_ct_tg_destroy_v0,
 316                 .target         = xt_ct_target_v0,
 317                 .table          = "raw",
 318                 .me             = THIS_MODULE,
 319         },
 320         {
 321                 .name           = "CT",
 322                 .family         = NFPROTO_UNSPEC,
 323                 .revision       = 1,
 324                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 325                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 326                 .checkentry     = xt_ct_tg_check_v1,
 327                 .destroy        = xt_ct_tg_destroy_v1,
 328                 .target         = xt_ct_target_v1,
 329                 .table          = "raw",
 330                 .me             = THIS_MODULE,
 331         },
 332         {
 333                 .name           = "CT",
 334                 .family         = NFPROTO_UNSPEC,
 335                 .revision       = 2,
 336                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
 337                 .usersize       = offsetof(struct xt_ct_target_info, ct),
 338                 .checkentry     = xt_ct_tg_check_v2,
 339                 .destroy        = xt_ct_tg_destroy_v1,
 340                 .target         = xt_ct_target_v1,
 341                 .table          = "raw",
 342                 .me             = THIS_MODULE,
 343         },
 344 };
 345
 346 static unsigned int
 347 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 348 {
 349         /* Previously seen (loopback)? Ignore. */
 350         if (skb->_nfct != 0)
 351                 return XT_CONTINUE;
 352
 353         nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 354
 355         return XT_CONTINUE;
 356 }
 357
 358 static int notrack_chk(const struct xt_tgchk_param *par)
 359 {
 360         if (!par->net->xt.notrack_deprecated_warning) {
 361                 pr_info("netfilter: NOTRACK target is deprecated, "
 362                         "use CT instead or upgrade iptables\n");
 363                 par->net->xt.notrack_deprecated_warning = true;
 364         }
 365         return 0;
 366 }
 367
 368 static struct xt_target notrack_tg_reg __read_mostly = {
 369         .name           = "NOTRACK",
 370         .revision       = 0,
 371         .family         = NFPROTO_UNSPEC,
 372         .checkentry     = notrack_chk,
 373         .target         = notrack_tg,
 374         .table          = "raw",
 375         .me             = THIS_MODULE,
 376 };
 377
 378 static int __init xt_ct_tg_init(void)
 379 {
 380         int ret;
 381
 382         ret = xt_register_target(&notrack_tg_reg);
 383         if (ret < 0)
 384                 return ret;
 385
 386         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 387         if (ret < 0) {
 388                 xt_unregister_target(&notrack_tg_reg);
 389                 return ret;
 390         }
 391         return 0;
 392 }
 393
 394 static void __exit xt_ct_tg_exit(void)
 395 {
 396         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 397         xt_unregister_target(&notrack_tg_reg);
 398 }
 399
 400 module_init(xt_ct_tg_init);
 401 module_exit(xt_ct_tg_exit);
 402
 403 MODULE_LICENSE("GPL");
 404 MODULE_DESCRIPTION("Xtables: connection tracking target");
 405 MODULE_ALIAS("ipt_CT");
 406 MODULE_ALIAS("ip6t_CT");
 407 MODULE_ALIAS("ipt_NOTRACK");
 408 MODULE_ALIAS("ip6t_NOTRACK");