linux/net/netfilter/xt_CT.c
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   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
  23static 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        /* special case the untracked ct : we want the percpu object */
  30        if (!ct)
  31                ct = nf_ct_untracked_get();
  32        atomic_inc(&ct->ct_general.use);
  33        skb->nfct = &ct->ct_general;
  34        skb->nfctinfo = IP_CT_NEW;
  35
  36        return XT_CONTINUE;
  37}
  38
  39static 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
  48static 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
  57static 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
  75static int
  76xt_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#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 108static 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
 118static int
 119xt_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        struct ctnl_timeout *timeout;
 125        struct nf_conn_timeout *timeout_ext;
 126        struct nf_conntrack_l4proto *l4proto;
 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(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 == NULL)
 172                ret = -ENOMEM;
 173
 174err_put_timeout:
 175        __xt_ct_tg_timeout_put(timeout);
 176out:
 177        rcu_read_unlock();
 178        return ret;
 179#else
 180        return -EOPNOTSUPP;
 181#endif
 182}
 183
 184static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 185                          struct xt_ct_target_info_v1 *info)
 186{
 187        struct nf_conntrack_tuple t;
 188        struct nf_conn *ct;
 189        int ret = -EOPNOTSUPP;
 190
 191        if (info->flags & XT_CT_NOTRACK) {
 192                ct = NULL;
 193                goto out;
 194        }
 195
 196#ifndef CONFIG_NF_CONNTRACK_ZONES
 197        if (info->zone)
 198                goto err1;
 199#endif
 200
 201        ret = nf_ct_l3proto_try_module_get(par->family);
 202        if (ret < 0)
 203                goto err1;
 204
 205        memset(&t, 0, sizeof(t));
 206        ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
 207        ret = PTR_ERR(ct);
 208        if (IS_ERR(ct))
 209                goto err2;
 210
 211        ret = 0;
 212        if ((info->ct_events || info->exp_events) &&
 213            !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 214                                  GFP_KERNEL))
 215                goto err3;
 216
 217        if (info->helper[0]) {
 218                ret = xt_ct_set_helper(ct, info->helper, par);
 219                if (ret < 0)
 220                        goto err3;
 221        }
 222
 223        if (info->timeout[0]) {
 224                ret = xt_ct_set_timeout(ct, par, info->timeout);
 225                if (ret < 0)
 226                        goto err3;
 227        }
 228
 229        __set_bit(IPS_TEMPLATE_BIT, &ct->status);
 230        __set_bit(IPS_CONFIRMED_BIT, &ct->status);
 231
 232        /* Overload tuple linked list to put us in template list. */
 233        hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
 234                                 &par->net->ct.tmpl);
 235out:
 236        info->ct = ct;
 237        return 0;
 238
 239err3:
 240        nf_conntrack_free(ct);
 241err2:
 242        nf_ct_l3proto_module_put(par->family);
 243err1:
 244        return ret;
 245}
 246
 247static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
 248{
 249        struct xt_ct_target_info *info = par->targinfo;
 250        struct xt_ct_target_info_v1 info_v1 = {
 251                .flags          = info->flags,
 252                .zone           = info->zone,
 253                .ct_events      = info->ct_events,
 254                .exp_events     = info->exp_events,
 255        };
 256        int ret;
 257
 258        if (info->flags & ~XT_CT_NOTRACK)
 259                return -EINVAL;
 260
 261        memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 262
 263        ret = xt_ct_tg_check(par, &info_v1);
 264        if (ret < 0)
 265                return ret;
 266
 267        info->ct = info_v1.ct;
 268
 269        return ret;
 270}
 271
 272static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
 273{
 274        struct xt_ct_target_info_v1 *info = par->targinfo;
 275
 276        if (info->flags & ~XT_CT_NOTRACK)
 277                return -EINVAL;
 278
 279        return xt_ct_tg_check(par, par->targinfo);
 280}
 281
 282static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
 283{
 284        struct xt_ct_target_info_v1 *info = par->targinfo;
 285
 286        if (info->flags & ~XT_CT_MASK)
 287                return -EINVAL;
 288
 289        return xt_ct_tg_check(par, par->targinfo);
 290}
 291
 292static void xt_ct_destroy_timeout(struct nf_conn *ct)
 293{
 294#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 295        struct nf_conn_timeout *timeout_ext;
 296        typeof(nf_ct_timeout_put_hook) timeout_put;
 297
 298        rcu_read_lock();
 299        timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 300
 301        if (timeout_put) {
 302                timeout_ext = nf_ct_timeout_find(ct);
 303                if (timeout_ext)
 304                        timeout_put(timeout_ext->timeout);
 305        }
 306        rcu_read_unlock();
 307#endif
 308}
 309
 310static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 311                             struct xt_ct_target_info_v1 *info)
 312{
 313        struct nf_conn *ct = info->ct;
 314        struct nf_conn_help *help;
 315
 316        if (ct && !nf_ct_is_untracked(ct)) {
 317                help = nfct_help(ct);
 318                if (help)
 319                        module_put(help->helper->me);
 320
 321                nf_ct_l3proto_module_put(par->family);
 322
 323                xt_ct_destroy_timeout(ct);
 324                nf_ct_put(info->ct);
 325        }
 326}
 327
 328static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
 329{
 330        struct xt_ct_target_info *info = par->targinfo;
 331        struct xt_ct_target_info_v1 info_v1 = {
 332                .flags          = info->flags,
 333                .zone           = info->zone,
 334                .ct_events      = info->ct_events,
 335                .exp_events     = info->exp_events,
 336                .ct             = info->ct,
 337        };
 338        memcpy(info_v1.helper, info->helper, sizeof(info->helper));
 339
 340        xt_ct_tg_destroy(par, &info_v1);
 341}
 342
 343static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
 344{
 345        xt_ct_tg_destroy(par, par->targinfo);
 346}
 347
 348static struct xt_target xt_ct_tg_reg[] __read_mostly = {
 349        {
 350                .name           = "CT",
 351                .family         = NFPROTO_UNSPEC,
 352                .targetsize     = sizeof(struct xt_ct_target_info),
 353                .checkentry     = xt_ct_tg_check_v0,
 354                .destroy        = xt_ct_tg_destroy_v0,
 355                .target         = xt_ct_target_v0,
 356                .table          = "raw",
 357                .me             = THIS_MODULE,
 358        },
 359        {
 360                .name           = "CT",
 361                .family         = NFPROTO_UNSPEC,
 362                .revision       = 1,
 363                .targetsize     = sizeof(struct xt_ct_target_info_v1),
 364                .checkentry     = xt_ct_tg_check_v1,
 365                .destroy        = xt_ct_tg_destroy_v1,
 366                .target         = xt_ct_target_v1,
 367                .table          = "raw",
 368                .me             = THIS_MODULE,
 369        },
 370        {
 371                .name           = "CT",
 372                .family         = NFPROTO_UNSPEC,
 373                .revision       = 2,
 374                .targetsize     = sizeof(struct xt_ct_target_info_v1),
 375                .checkentry     = xt_ct_tg_check_v2,
 376                .destroy        = xt_ct_tg_destroy_v1,
 377                .target         = xt_ct_target_v1,
 378                .table          = "raw",
 379                .me             = THIS_MODULE,
 380        },
 381};
 382
 383static unsigned int
 384notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 385{
 386        /* Previously seen (loopback)? Ignore. */
 387        if (skb->nfct != NULL)
 388                return XT_CONTINUE;
 389
 390        skb->nfct = &nf_ct_untracked_get()->ct_general;
 391        skb->nfctinfo = IP_CT_NEW;
 392        nf_conntrack_get(skb->nfct);
 393
 394        return XT_CONTINUE;
 395}
 396
 397static int notrack_chk(const struct xt_tgchk_param *par)
 398{
 399        if (!par->net->xt.notrack_deprecated_warning) {
 400                pr_info("netfilter: NOTRACK target is deprecated, "
 401                        "use CT instead or upgrade iptables\n");
 402                par->net->xt.notrack_deprecated_warning = true;
 403        }
 404        return 0;
 405}
 406
 407static struct xt_target notrack_tg_reg __read_mostly = {
 408        .name           = "NOTRACK",
 409        .revision       = 0,
 410        .family         = NFPROTO_UNSPEC,
 411        .checkentry     = notrack_chk,
 412        .target         = notrack_tg,
 413        .table          = "raw",
 414        .me             = THIS_MODULE,
 415};
 416
 417static int __init xt_ct_tg_init(void)
 418{
 419        int ret;
 420
 421        ret = xt_register_target(&notrack_tg_reg);
 422        if (ret < 0)
 423                return ret;
 424
 425        ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 426        if (ret < 0) {
 427                xt_unregister_target(&notrack_tg_reg);
 428                return ret;
 429        }
 430        return 0;
 431}
 432
 433static void __exit xt_ct_tg_exit(void)
 434{
 435        xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
 436        xt_unregister_target(&notrack_tg_reg);
 437}
 438
 439module_init(xt_ct_tg_init);
 440module_exit(xt_ct_tg_exit);
 441
 442MODULE_LICENSE("GPL");
 443MODULE_DESCRIPTION("Xtables: connection tracking target");
 444MODULE_ALIAS("ipt_CT");
 445MODULE_ALIAS("ip6t_CT");
 446MODULE_ALIAS("ipt_NOTRACK");
 447MODULE_ALIAS("ip6t_NOTRACK");
 448
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