/*
   * net/sched/ipt.c	iptables target interface
   *
   *TODO: Add other tables. For now we only support the ipv4 table targets
   *
   *		This program is free software; you can redistribute it and/or
   *		modify it under the terms of the GNU General Public License
   *		as published by the Free Software Foundation; either version
   *		2 of the License, or (at your option) any later version.
   *
   * Copyright:	Jamal Hadi Salim (2002-4)
   */

  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/string.h>

  #include <linux/errno.h>

  #include <linux/skbuff.h>
  #include <linux/rtnetlink.h>
  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/slab.h>

  #include <net/netlink.h>

  #include <net/pkt_sched.h>
  #include <linux/tc_act/tc_ipt.h>
  #include <net/tc_act/tc_ipt.h>
  
  #include <linux/netfilter_ipv4/ip_tables.h>

  #define IPT_TAB_MASK     15
  static struct tcf_common *tcf_ipt_ht[IPT_TAB_MASK + 1];
  static u32 ipt_idx_gen;

  static DEFINE_RWLOCK(ipt_lock);

  static struct tcf_hashinfo ipt_hash_info = {
  	.htab	=	tcf_ipt_ht,
  	.hmask	=	IPT_TAB_MASK,
  	.lock	=	&ipt_lock,
  };

  static int ipt_init_target(struct xt_entry_target *t, char *table, unsigned int hook)

  {

  	struct xt_tgchk_param par;

  	struct xt_target *target;

  	int ret = 0;

  	target = xt_request_find_target(AF_INET, t->u.user.name,
  					t->u.user.revision);

  	if (IS_ERR(target))
  		return PTR_ERR(target);

  	t->u.kernel.target = target;

  	par.table     = table;
  	par.entryinfo = NULL;
  	par.target    = target;
  	par.targinfo  = t->data;
  	par.hook_mask = hook;

  	par.family    = NFPROTO_IPV4;

  	ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);

  	if (ret < 0) {

  		module_put(t->u.kernel.target->me);

  		return ret;

  	}

  	return 0;

  }

  static void ipt_destroy_target(struct xt_entry_target *t)

  {

  	struct xt_tgdtor_param par = {
  		.target   = t->u.kernel.target,
  		.targinfo = t->data,
  	};
  	if (par.target->destroy != NULL)
  		par.target->destroy(&par);
  	module_put(par.target->me);

  }

  static int tcf_ipt_release(struct tcf_ipt *ipt, int bind)

  {
  	int ret = 0;

  	if (ipt) {

  		if (bind)

  			ipt->tcf_bindcnt--;
  		ipt->tcf_refcnt--;
  		if (ipt->tcf_bindcnt <= 0 && ipt->tcf_refcnt <= 0) {
  			ipt_destroy_target(ipt->tcfi_t);
  			kfree(ipt->tcfi_tname);
  			kfree(ipt->tcfi_t);
  			tcf_hash_destroy(&ipt->common, &ipt_hash_info);

  			ret = ACT_P_DELETED;
  		}
  	}
  	return ret;
  }

  static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
  	[TCA_IPT_TABLE]	= { .type = NLA_STRING, .len = IFNAMSIZ },
  	[TCA_IPT_HOOK]	= { .type = NLA_U32 },
  	[TCA_IPT_INDEX]	= { .type = NLA_U32 },

  	[TCA_IPT_TARG]	= { .len = sizeof(struct xt_entry_target) },

  };

  static int tcf_ipt_init(struct nlattr *nla, struct nlattr *est,

  			struct tc_action *a, int ovr, int bind)

  {

  	struct nlattr *tb[TCA_IPT_MAX + 1];

  	struct tcf_ipt *ipt;
  	struct tcf_common *pc;

  	struct xt_entry_target *td, *t;

  	char *tname;
  	int ret = 0, err;
  	u32 hook = 0;
  	u32 index = 0;

  	if (nla == NULL)

  		return -EINVAL;

  	err = nla_parse_nested(tb, TCA_IPT_MAX, nla, ipt_policy);

  	if (err < 0)
  		return err;

  	if (tb[TCA_IPT_HOOK] == NULL)

  		return -EINVAL;

  	if (tb[TCA_IPT_TARG] == NULL)

  		return -EINVAL;

  	td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);

  	if (nla_len(tb[TCA_IPT_TARG]) < td->u.target_size)

  		return -EINVAL;

  	if (tb[TCA_IPT_INDEX] != NULL)

  		index = nla_get_u32(tb[TCA_IPT_INDEX]);

  	pc = tcf_hash_check(index, a, bind, &ipt_hash_info);
  	if (!pc) {
  		pc = tcf_hash_create(index, est, a, sizeof(*ipt), bind,
  				     &ipt_idx_gen, &ipt_hash_info);

  		if (IS_ERR(pc))

  			return PTR_ERR(pc);

  		ret = ACT_P_CREATED;
  	} else {
  		if (!ovr) {

  			tcf_ipt_release(to_ipt(pc), bind);

  			return -EEXIST;
  		}
  	}

  	ipt = to_ipt(pc);

  	hook = nla_get_u32(tb[TCA_IPT_HOOK]);

  
  	err = -ENOMEM;
  	tname = kmalloc(IFNAMSIZ, GFP_KERNEL);

  	if (unlikely(!tname))

  		goto err1;

  	if (tb[TCA_IPT_TABLE] == NULL ||
  	    nla_strlcpy(tname, tb[TCA_IPT_TABLE], IFNAMSIZ) >= IFNAMSIZ)

  		strcpy(tname, "mangle");

  	t = kmemdup(td, td->u.target_size, GFP_KERNEL);

  	if (unlikely(!t))

  		goto err2;

  	err = ipt_init_target(t, tname, hook);
  	if (err < 0)

  		goto err3;

  	spin_lock_bh(&ipt->tcf_lock);

  	if (ret != ACT_P_CREATED) {

  		ipt_destroy_target(ipt->tcfi_t);
  		kfree(ipt->tcfi_tname);
  		kfree(ipt->tcfi_t);

  	}

  	ipt->tcfi_tname = tname;
  	ipt->tcfi_t     = t;
  	ipt->tcfi_hook  = hook;
  	spin_unlock_bh(&ipt->tcf_lock);

  	if (ret == ACT_P_CREATED)

  		tcf_hash_insert(pc, &ipt_hash_info);

  	return ret;
  
  err3:
  	kfree(t);
  err2:
  	kfree(tname);
  err1:

  	kfree(pc);

  	return err;
  }

  static int tcf_ipt_cleanup(struct tc_action *a, int bind)

  {

  	struct tcf_ipt *ipt = a->priv;
  	return tcf_ipt_release(ipt, bind);

  }

  static int tcf_ipt(struct sk_buff *skb, const struct tc_action *a,

  		   struct tcf_result *res)

  {
  	int ret = 0, result = 0;

  	struct tcf_ipt *ipt = a->priv;

  	struct xt_action_param par;

  
  	if (skb_cloned(skb)) {
  		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
  			return TC_ACT_UNSPEC;
  	}

  	spin_lock(&ipt->tcf_lock);

  	ipt->tcf_tm.lastuse = jiffies;

  	bstats_update(&ipt->tcf_bstats, skb);

  
  	/* yes, we have to worry about both in and out dev

  	 * worry later - danger - this API seems to have changed
  	 * from earlier kernels
  	 */

  	par.in       = skb->dev;
  	par.out      = NULL;
  	par.hooknum  = ipt->tcfi_hook;
  	par.target   = ipt->tcfi_t->u.kernel.target;
  	par.targinfo = ipt->tcfi_t->data;
  	ret = par.target->target(skb, &par);

  	switch (ret) {
  	case NF_ACCEPT:
  		result = TC_ACT_OK;
  		break;
  	case NF_DROP:
  		result = TC_ACT_SHOT;

  		ipt->tcf_qstats.drops++;

  		break;

  	case XT_CONTINUE:

  		result = TC_ACT_PIPE;
  		break;
  	default:
  		if (net_ratelimit())

  			pr_notice("tc filter: Bogus netfilter code"
  				  " %d assume ACCEPT
  ", ret);

  		result = TC_POLICE_OK;
  		break;
  	}

  	spin_unlock(&ipt->tcf_lock);

  	return result;
  
  }

  static int tcf_ipt_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)

  {

  	unsigned char *b = skb_tail_pointer(skb);

  	struct tcf_ipt *ipt = a->priv;

  	struct xt_entry_target *t;

  	struct tcf_t tm;
  	struct tc_cnt c;

  
  	/* for simple targets kernel size == user size

  	 * user name = target name
  	 * for foolproof you need to not assume this
  	 */

  	t = kmemdup(ipt->tcfi_t, ipt->tcfi_t->u.user.target_size, GFP_ATOMIC);

  	if (unlikely(!t))

  		goto nla_put_failure;

  	c.bindcnt = ipt->tcf_bindcnt - bind;
  	c.refcnt = ipt->tcf_refcnt - ref;

  	strcpy(t->u.user.name, ipt->tcfi_t->u.kernel.target->name);

  	NLA_PUT(skb, TCA_IPT_TARG, ipt->tcfi_t->u.user.target_size, t);

  	NLA_PUT_U32(skb, TCA_IPT_INDEX, ipt->tcf_index);
  	NLA_PUT_U32(skb, TCA_IPT_HOOK, ipt->tcfi_hook);

  	NLA_PUT(skb, TCA_IPT_CNT, sizeof(struct tc_cnt), &c);

  	NLA_PUT_STRING(skb, TCA_IPT_TABLE, ipt->tcfi_tname);

  	tm.install = jiffies_to_clock_t(jiffies - ipt->tcf_tm.install);
  	tm.lastuse = jiffies_to_clock_t(jiffies - ipt->tcf_tm.lastuse);
  	tm.expires = jiffies_to_clock_t(ipt->tcf_tm.expires);

  	NLA_PUT(skb, TCA_IPT_TM, sizeof (tm), &tm);

  	kfree(t);
  	return skb->len;

  nla_put_failure:

  	nlmsg_trim(skb, b);

  	kfree(t);
  	return -1;
  }
  
  static struct tc_action_ops act_ipt_ops = {
  	.kind		=	"ipt",

  	.hinfo		=	&ipt_hash_info,

  	.type		=	TCA_ACT_IPT,
  	.capab		=	TCA_CAP_NONE,
  	.owner		=	THIS_MODULE,
  	.act		=	tcf_ipt,
  	.dump		=	tcf_ipt_dump,
  	.cleanup	=	tcf_ipt_cleanup,
  	.lookup		=	tcf_hash_search,
  	.init		=	tcf_ipt_init,
  	.walk		=	tcf_generic_walker
  };
  
  MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
  MODULE_DESCRIPTION("Iptables target actions");
  MODULE_LICENSE("GPL");

  static int __init ipt_init_module(void)

  {
  	return tcf_register_action(&act_ipt_ops);
  }

  static void __exit ipt_cleanup_module(void)

  {
  	tcf_unregister_action(&act_ipt_ops);
  }
  
  module_init(ipt_init_module);
  module_exit(ipt_cleanup_module);