linux/net/sched/act_ipt.c
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   1/*
   2 * net/sched/ipt.c     iptables target interface
   3 *
   4 *TODO: Add other tables. For now we only support the ipv4 table targets
   5 *
   6 *              This program is free software; you can redistribute it and/or
   7 *              modify it under the terms of the GNU General Public License
   8 *              as published by the Free Software Foundation; either version
   9 *              2 of the License, or (at your option) any later version.
  10 *
  11 * Copyright:   Jamal Hadi Salim (2002-4)
  12 */
  13
  14#include <linux/types.h>
  15#include <linux/kernel.h>
  16#include <linux/string.h>
  17#include <linux/errno.h>
  18#include <linux/skbuff.h>
  19#include <linux/rtnetlink.h>
  20#include <linux/module.h>
  21#include <linux/init.h>
  22#include <linux/slab.h>
  23#include <net/netlink.h>
  24#include <net/pkt_sched.h>
  25#include <linux/tc_act/tc_ipt.h>
  26#include <net/tc_act/tc_ipt.h>
  27
  28#include <linux/netfilter_ipv4/ip_tables.h>
  29
  30
  31#define IPT_TAB_MASK     15
  32static struct tcf_common *tcf_ipt_ht[IPT_TAB_MASK + 1];
  33static u32 ipt_idx_gen;
  34static DEFINE_RWLOCK(ipt_lock);
  35
  36static struct tcf_hashinfo ipt_hash_info = {
  37        .htab   =       tcf_ipt_ht,
  38        .hmask  =       IPT_TAB_MASK,
  39        .lock   =       &ipt_lock,
  40};
  41
  42static int ipt_init_target(struct xt_entry_target *t, char *table, unsigned int hook)
  43{
  44        struct xt_tgchk_param par;
  45        struct xt_target *target;
  46        int ret = 0;
  47
  48        target = xt_request_find_target(AF_INET, t->u.user.name,
  49                                        t->u.user.revision);
  50        if (IS_ERR(target))
  51                return PTR_ERR(target);
  52
  53        t->u.kernel.target = target;
  54        par.table     = table;
  55        par.entryinfo = NULL;
  56        par.target    = target;
  57        par.targinfo  = t->data;
  58        par.hook_mask = hook;
  59        par.family    = NFPROTO_IPV4;
  60
  61        ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
  62        if (ret < 0) {
  63                module_put(t->u.kernel.target->me);
  64                return ret;
  65        }
  66        return 0;
  67}
  68
  69static void ipt_destroy_target(struct xt_entry_target *t)
  70{
  71        struct xt_tgdtor_param par = {
  72                .target   = t->u.kernel.target,
  73                .targinfo = t->data,
  74        };
  75        if (par.target->destroy != NULL)
  76                par.target->destroy(&par);
  77        module_put(par.target->me);
  78}
  79
  80static int tcf_ipt_release(struct tcf_ipt *ipt, int bind)
  81{
  82        int ret = 0;
  83        if (ipt) {
  84                if (bind)
  85                        ipt->tcf_bindcnt--;
  86                ipt->tcf_refcnt--;
  87                if (ipt->tcf_bindcnt <= 0 && ipt->tcf_refcnt <= 0) {
  88                        ipt_destroy_target(ipt->tcfi_t);
  89                        kfree(ipt->tcfi_tname);
  90                        kfree(ipt->tcfi_t);
  91                        tcf_hash_destroy(&ipt->common, &ipt_hash_info);
  92                        ret = ACT_P_DELETED;
  93                }
  94        }
  95        return ret;
  96}
  97
  98static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
  99        [TCA_IPT_TABLE] = { .type = NLA_STRING, .len = IFNAMSIZ },
 100        [TCA_IPT_HOOK]  = { .type = NLA_U32 },
 101        [TCA_IPT_INDEX] = { .type = NLA_U32 },
 102        [TCA_IPT_TARG]  = { .len = sizeof(struct xt_entry_target) },
 103};
 104
 105static int tcf_ipt_init(struct nlattr *nla, struct nlattr *est,
 106                        struct tc_action *a, int ovr, int bind)
 107{
 108        struct nlattr *tb[TCA_IPT_MAX + 1];
 109        struct tcf_ipt *ipt;
 110        struct tcf_common *pc;
 111        struct xt_entry_target *td, *t;
 112        char *tname;
 113        int ret = 0, err;
 114        u32 hook = 0;
 115        u32 index = 0;
 116
 117        if (nla == NULL)
 118                return -EINVAL;
 119
 120        err = nla_parse_nested(tb, TCA_IPT_MAX, nla, ipt_policy);
 121        if (err < 0)
 122                return err;
 123
 124        if (tb[TCA_IPT_HOOK] == NULL)
 125                return -EINVAL;
 126        if (tb[TCA_IPT_TARG] == NULL)
 127                return -EINVAL;
 128
 129        td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);
 130        if (nla_len(tb[TCA_IPT_TARG]) < td->u.target_size)
 131                return -EINVAL;
 132
 133        if (tb[TCA_IPT_INDEX] != NULL)
 134                index = nla_get_u32(tb[TCA_IPT_INDEX]);
 135
 136        pc = tcf_hash_check(index, a, bind, &ipt_hash_info);
 137        if (!pc) {
 138                pc = tcf_hash_create(index, est, a, sizeof(*ipt), bind,
 139                                     &ipt_idx_gen, &ipt_hash_info);
 140                if (IS_ERR(pc))
 141                        return PTR_ERR(pc);
 142                ret = ACT_P_CREATED;
 143        } else {
 144                if (!ovr) {
 145                        tcf_ipt_release(to_ipt(pc), bind);
 146                        return -EEXIST;
 147                }
 148        }
 149        ipt = to_ipt(pc);
 150
 151        hook = nla_get_u32(tb[TCA_IPT_HOOK]);
 152
 153        err = -ENOMEM;
 154        tname = kmalloc(IFNAMSIZ, GFP_KERNEL);
 155        if (unlikely(!tname))
 156                goto err1;
 157        if (tb[TCA_IPT_TABLE] == NULL ||
 158            nla_strlcpy(tname, tb[TCA_IPT_TABLE], IFNAMSIZ) >= IFNAMSIZ)
 159                strcpy(tname, "mangle");
 160
 161        t = kmemdup(td, td->u.target_size, GFP_KERNEL);
 162        if (unlikely(!t))
 163                goto err2;
 164
 165        err = ipt_init_target(t, tname, hook);
 166        if (err < 0)
 167                goto err3;
 168
 169        spin_lock_bh(&ipt->tcf_lock);
 170        if (ret != ACT_P_CREATED) {
 171                ipt_destroy_target(ipt->tcfi_t);
 172                kfree(ipt->tcfi_tname);
 173                kfree(ipt->tcfi_t);
 174        }
 175        ipt->tcfi_tname = tname;
 176        ipt->tcfi_t     = t;
 177        ipt->tcfi_hook  = hook;
 178        spin_unlock_bh(&ipt->tcf_lock);
 179        if (ret == ACT_P_CREATED)
 180                tcf_hash_insert(pc, &ipt_hash_info);
 181        return ret;
 182
 183err3:
 184        kfree(t);
 185err2:
 186        kfree(tname);
 187err1:
 188        if (ret == ACT_P_CREATED) {
 189                if (est)
 190                        gen_kill_estimator(&pc->tcfc_bstats,
 191                                           &pc->tcfc_rate_est);
 192                kfree_rcu(pc, tcfc_rcu);
 193        }
 194        return err;
 195}
 196
 197static int tcf_ipt_cleanup(struct tc_action *a, int bind)
 198{
 199        struct tcf_ipt *ipt = a->priv;
 200        return tcf_ipt_release(ipt, bind);
 201}
 202
 203static int tcf_ipt(struct sk_buff *skb, const struct tc_action *a,
 204                   struct tcf_result *res)
 205{
 206        int ret = 0, result = 0;
 207        struct tcf_ipt *ipt = a->priv;
 208        struct xt_action_param par;
 209
 210        if (skb_cloned(skb)) {
 211                if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 212                        return TC_ACT_UNSPEC;
 213        }
 214
 215        spin_lock(&ipt->tcf_lock);
 216
 217        ipt->tcf_tm.lastuse = jiffies;
 218        bstats_update(&ipt->tcf_bstats, skb);
 219
 220        /* yes, we have to worry about both in and out dev
 221         * worry later - danger - this API seems to have changed
 222         * from earlier kernels
 223         */
 224        par.in       = skb->dev;
 225        par.out      = NULL;
 226        par.hooknum  = ipt->tcfi_hook;
 227        par.target   = ipt->tcfi_t->u.kernel.target;
 228        par.targinfo = ipt->tcfi_t->data;
 229        ret = par.target->target(skb, &par);
 230
 231        switch (ret) {
 232        case NF_ACCEPT:
 233                result = TC_ACT_OK;
 234                break;
 235        case NF_DROP:
 236                result = TC_ACT_SHOT;
 237                ipt->tcf_qstats.drops++;
 238                break;
 239        case XT_CONTINUE:
 240                result = TC_ACT_PIPE;
 241                break;
 242        default:
 243                net_notice_ratelimited("tc filter: Bogus netfilter code %d assume ACCEPT\n",
 244                                       ret);
 245                result = TC_POLICE_OK;
 246                break;
 247        }
 248        spin_unlock(&ipt->tcf_lock);
 249        return result;
 250
 251}
 252
 253static int tcf_ipt_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
 254{
 255        unsigned char *b = skb_tail_pointer(skb);
 256        struct tcf_ipt *ipt = a->priv;
 257        struct xt_entry_target *t;
 258        struct tcf_t tm;
 259        struct tc_cnt c;
 260
 261        /* for simple targets kernel size == user size
 262         * user name = target name
 263         * for foolproof you need to not assume this
 264         */
 265
 266        t = kmemdup(ipt->tcfi_t, ipt->tcfi_t->u.user.target_size, GFP_ATOMIC);
 267        if (unlikely(!t))
 268                goto nla_put_failure;
 269
 270        c.bindcnt = ipt->tcf_bindcnt - bind;
 271        c.refcnt = ipt->tcf_refcnt - ref;
 272        strcpy(t->u.user.name, ipt->tcfi_t->u.kernel.target->name);
 273
 274        if (nla_put(skb, TCA_IPT_TARG, ipt->tcfi_t->u.user.target_size, t) ||
 275            nla_put_u32(skb, TCA_IPT_INDEX, ipt->tcf_index) ||
 276            nla_put_u32(skb, TCA_IPT_HOOK, ipt->tcfi_hook) ||
 277            nla_put(skb, TCA_IPT_CNT, sizeof(struct tc_cnt), &c) ||
 278            nla_put_string(skb, TCA_IPT_TABLE, ipt->tcfi_tname))
 279                goto nla_put_failure;
 280        tm.install = jiffies_to_clock_t(jiffies - ipt->tcf_tm.install);
 281        tm.lastuse = jiffies_to_clock_t(jiffies - ipt->tcf_tm.lastuse);
 282        tm.expires = jiffies_to_clock_t(ipt->tcf_tm.expires);
 283        if (nla_put(skb, TCA_IPT_TM, sizeof (tm), &tm))
 284                goto nla_put_failure;
 285        kfree(t);
 286        return skb->len;
 287
 288nla_put_failure:
 289        nlmsg_trim(skb, b);
 290        kfree(t);
 291        return -1;
 292}
 293
 294static struct tc_action_ops act_ipt_ops = {
 295        .kind           =       "ipt",
 296        .hinfo          =       &ipt_hash_info,
 297        .type           =       TCA_ACT_IPT,
 298        .capab          =       TCA_CAP_NONE,
 299        .owner          =       THIS_MODULE,
 300        .act            =       tcf_ipt,
 301        .dump           =       tcf_ipt_dump,
 302        .cleanup        =       tcf_ipt_cleanup,
 303        .lookup         =       tcf_hash_search,
 304        .init           =       tcf_ipt_init,
 305        .walk           =       tcf_generic_walker
 306};
 307
 308MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
 309MODULE_DESCRIPTION("Iptables target actions");
 310MODULE_LICENSE("GPL");
 311
 312static int __init ipt_init_module(void)
 313{
 314        return tcf_register_action(&act_ipt_ops);
 315}
 316
 317static void __exit ipt_cleanup_module(void)
 318{
 319        tcf_unregister_action(&act_ipt_ops);
 320}
 321
 322module_init(ipt_init_module);
 323module_exit(ipt_cleanup_module);
 324
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