net/sched/act_ipt.c

   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
  32 static struct tcf_common *tcf_ipt_ht[IPT_TAB_MASK + 1];
  33 static u32 ipt_idx_gen;
  34 static DEFINE_RWLOCK(ipt_lock);
  35
  36 static struct tcf_hashinfo ipt_hash_info = {
  37         .htab   =       tcf_ipt_ht,
  38         .hmask  =       IPT_TAB_MASK,
  39         .lock   =       &ipt_lock,
  40 };
  41
  42 static 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
  69 static 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
  80 static 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
  98 static 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
 105 static 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
 183 err3:
 184         kfree(t);
 185 err2:
 186         kfree(tname);
 187 err1:
 188         kfree(pc);
 189         return err;
 190 }
 191
 192 static int tcf_ipt_cleanup(struct tc_action *a, int bind)
 193 {
 194         struct tcf_ipt *ipt = a->priv;
 195         return tcf_ipt_release(ipt, bind);
 196 }
 197
 198 static int tcf_ipt(struct sk_buff *skb, const struct tc_action *a,
 199                    struct tcf_result *res)
 200 {
 201         int ret = 0, result = 0;
 202         struct tcf_ipt *ipt = a->priv;
 203         struct xt_action_param par;
 204
 205         if (skb_cloned(skb)) {
 206                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 207                         return TC_ACT_UNSPEC;
 208         }
 209
 210         spin_lock(&ipt->tcf_lock);
 211
 212         ipt->tcf_tm.lastuse = jiffies;
 213         bstats_update(&ipt->tcf_bstats, skb);
 214
 215         /* yes, we have to worry about both in and out dev
 216          * worry later - danger - this API seems to have changed
 217          * from earlier kernels
 218          */
 219         par.in       = skb->dev;
 220         par.out      = NULL;
 221         par.hooknum  = ipt->tcfi_hook;
 222         par.target   = ipt->tcfi_t->u.kernel.target;
 223         par.targinfo = ipt->tcfi_t->data;
 224         ret = par.target->target(skb, &par);
 225
 226         switch (ret) {
 227         case NF_ACCEPT:
 228                 result = TC_ACT_OK;
 229                 break;
 230         case NF_DROP:
 231                 result = TC_ACT_SHOT;
 232                 ipt->tcf_qstats.drops++;
 233                 break;
 234         case XT_CONTINUE:
 235                 result = TC_ACT_PIPE;
 236                 break;
 237         default:
 238                 if (net_ratelimit())
 239                         pr_notice("tc filter: Bogus netfilter code"
 240                                   " %d assume ACCEPT\n", ret);
 241                 result = TC_POLICE_OK;
 242                 break;
 243         }
 244         spin_unlock(&ipt->tcf_lock);
 245         return result;
 246
 247 }
 248
 249 static int tcf_ipt_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
 250 {
 251         unsigned char *b = skb_tail_pointer(skb);
 252         struct tcf_ipt *ipt = a->priv;
 253         struct xt_entry_target *t;
 254         struct tcf_t tm;
 255         struct tc_cnt c;
 256
 257         /* for simple targets kernel size == user size
 258          * user name = target name
 259          * for foolproof you need to not assume this
 260          */
 261
 262         t = kmemdup(ipt->tcfi_t, ipt->tcfi_t->u.user.target_size, GFP_ATOMIC);
 263         if (unlikely(!t))
 264                 goto nla_put_failure;
 265
 266         c.bindcnt = ipt->tcf_bindcnt - bind;
 267         c.refcnt = ipt->tcf_refcnt - ref;
 268         strcpy(t->u.user.name, ipt->tcfi_t->u.kernel.target->name);
 269
 270         NLA_PUT(skb, TCA_IPT_TARG, ipt->tcfi_t->u.user.target_size, t);
 271         NLA_PUT_U32(skb, TCA_IPT_INDEX, ipt->tcf_index);
 272         NLA_PUT_U32(skb, TCA_IPT_HOOK, ipt->tcfi_hook);
 273         NLA_PUT(skb, TCA_IPT_CNT, sizeof(struct tc_cnt), &c);
 274         NLA_PUT_STRING(skb, TCA_IPT_TABLE, ipt->tcfi_tname);
 275         tm.install = jiffies_to_clock_t(jiffies - ipt->tcf_tm.install);
 276         tm.lastuse = jiffies_to_clock_t(jiffies - ipt->tcf_tm.lastuse);
 277         tm.expires = jiffies_to_clock_t(ipt->tcf_tm.expires);
 278         NLA_PUT(skb, TCA_IPT_TM, sizeof (tm), &tm);
 279         kfree(t);
 280         return skb->len;
 281
 282 nla_put_failure:
 283         nlmsg_trim(skb, b);
 284         kfree(t);
 285         return -1;
 286 }
 287
 288 static struct tc_action_ops act_ipt_ops = {
 289         .kind           =       "ipt",
 290         .hinfo          =       &ipt_hash_info,
 291         .type           =       TCA_ACT_IPT,
 292         .capab          =       TCA_CAP_NONE,
 293         .owner          =       THIS_MODULE,
 294         .act            =       tcf_ipt,
 295         .dump           =       tcf_ipt_dump,
 296         .cleanup        =       tcf_ipt_cleanup,
 297         .lookup         =       tcf_hash_search,
 298         .init           =       tcf_ipt_init,
 299         .walk           =       tcf_generic_walker
 300 };
 301
 302 MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
 303 MODULE_DESCRIPTION("Iptables target actions");
 304 MODULE_LICENSE("GPL");
 305
 306 static int __init ipt_init_module(void)
 307 {
 308         return tcf_register_action(&act_ipt_ops);
 309 }
 310
 311 static void __exit ipt_cleanup_module(void)
 312 {
 313         tcf_unregister_action(&act_ipt_ops);
 314 }
 315
 316 module_init(ipt_init_module);
 317 module_exit(ipt_cleanup_module);