/*
   * net/sched/police.c	Input police filter.
   *
   *		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.
   *
   * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   * 		J Hadi Salim (action changes)
   */
  
  #include <linux/module.h>
  #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/init.h>
  #include <linux/slab.h>
  #include <net/act_api.h>
  #include <net/netlink.h>
  
  struct tcf_police {
  	struct tcf_common	common;
  	int			tcfp_result;
  	u32			tcfp_ewma_rate;
  	s64			tcfp_burst;
  	u32			tcfp_mtu;
  	s64			tcfp_toks;
  	s64			tcfp_ptoks;
  	s64			tcfp_mtu_ptoks;
  	s64			tcfp_t_c;
  	struct psched_ratecfg	rate;
  	bool			rate_present;
  	struct psched_ratecfg	peak;
  	bool			peak_present;
  };
  #define to_police(pc)	\
  	container_of(pc, struct tcf_police, common)
  
  #define POL_TAB_MASK     15
  static struct tcf_hashinfo police_hash_info;
  
  /* old policer structure from before tc actions */
  struct tc_police_compat {
  	u32			index;
  	int			action;
  	u32			limit;
  	u32			burst;
  	u32			mtu;
  	struct tc_ratespec	rate;
  	struct tc_ratespec	peakrate;
  };
  
  /* Each policer is serialized by its individual spinlock */
  
  static int tcf_act_police_walker(struct sk_buff *skb, struct netlink_callback *cb,
  			      int type, struct tc_action *a)
  {
  	struct tcf_hashinfo *hinfo = a->ops->hinfo;
  	struct hlist_head *head;
  	struct tcf_common *p;
  	int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;
  	struct nlattr *nest;
  
  	spin_lock_bh(&hinfo->lock);
  
  	s_i = cb->args[0];
  
  	for (i = 0; i < (POL_TAB_MASK + 1); i++) {
  		head = &hinfo->htab[tcf_hash(i, POL_TAB_MASK)];
  
  		hlist_for_each_entry_rcu(p, head, tcfc_head) {
  			index++;
  			if (index < s_i)
  				continue;
  			a->priv = p;
  			a->order = index;
  			nest = nla_nest_start(skb, a->order);
  			if (nest == NULL)
  				goto nla_put_failure;
  			if (type == RTM_DELACTION)
  				err = tcf_action_dump_1(skb, a, 0, 1);
  			else
  				err = tcf_action_dump_1(skb, a, 0, 0);
  			if (err < 0) {
  				index--;
  				nla_nest_cancel(skb, nest);
  				goto done;
  			}
  			nla_nest_end(skb, nest);
  			n_i++;
  		}
  	}
  done:
  	spin_unlock_bh(&hinfo->lock);
  	if (n_i)
  		cb->args[0] += n_i;
  	return n_i;
  
  nla_put_failure:
  	nla_nest_cancel(skb, nest);
  	goto done;
  }
  
  static const struct nla_policy police_policy[TCA_POLICE_MAX + 1] = {
  	[TCA_POLICE_RATE]	= { .len = TC_RTAB_SIZE },
  	[TCA_POLICE_PEAKRATE]	= { .len = TC_RTAB_SIZE },
  	[TCA_POLICE_AVRATE]	= { .type = NLA_U32 },
  	[TCA_POLICE_RESULT]	= { .type = NLA_U32 },
  };
  
  static int tcf_act_police_locate(struct net *net, struct nlattr *nla,
  				 struct nlattr *est, struct tc_action *a,
  				 int ovr, int bind)
  {
  	unsigned int h;
  	int ret = 0, err;
  	struct nlattr *tb[TCA_POLICE_MAX + 1];
  	struct tc_police *parm;
  	struct tcf_police *police;
  	struct qdisc_rate_table *R_tab = NULL, *P_tab = NULL;
  	struct tcf_hashinfo *hinfo = a->ops->hinfo;
  	int size;
  
  	if (nla == NULL)
  		return -EINVAL;
  
  	err = nla_parse_nested(tb, TCA_POLICE_MAX, nla, police_policy);
  	if (err < 0)
  		return err;
  
  	if (tb[TCA_POLICE_TBF] == NULL)
  		return -EINVAL;
  	size = nla_len(tb[TCA_POLICE_TBF]);
  	if (size != sizeof(*parm) && size != sizeof(struct tc_police_compat))
  		return -EINVAL;
  	parm = nla_data(tb[TCA_POLICE_TBF]);
  
  	if (parm->index) {
  		if (tcf_hash_search(a, parm->index)) {
  			police = to_police(a->priv);
  			if (bind) {
  				police->tcf_bindcnt += 1;
  				police->tcf_refcnt += 1;
  				return 0;
  			}
  			if (ovr)
  				goto override;
  			/* not replacing */
  			return -EEXIST;
  		}
  	}
  
  	police = kzalloc(sizeof(*police), GFP_KERNEL);
  	if (police == NULL)
  		return -ENOMEM;
  	ret = ACT_P_CREATED;
  	police->tcf_refcnt = 1;
  	spin_lock_init(&police->tcf_lock);
  	if (bind)
  		police->tcf_bindcnt = 1;
  override:
  	if (parm->rate.rate) {
  		err = -ENOMEM;
  		R_tab = qdisc_get_rtab(&parm->rate, tb[TCA_POLICE_RATE]);
  		if (R_tab == NULL)
  			goto failure;
  
  		if (parm->peakrate.rate) {
  			P_tab = qdisc_get_rtab(&parm->peakrate,
  					       tb[TCA_POLICE_PEAKRATE]);
  			if (P_tab == NULL)
  				goto failure;
  		}
  	}
  
  	spin_lock_bh(&police->tcf_lock);
  	if (est) {
  		err = gen_replace_estimator(&police->tcf_bstats,
  					    &police->tcf_rate_est,
  					    &police->tcf_lock, est);
  		if (err)
  			goto failure_unlock;
  	} else if (tb[TCA_POLICE_AVRATE] &&
  		   (ret == ACT_P_CREATED ||
  		    !gen_estimator_active(&police->tcf_bstats,
  					  &police->tcf_rate_est))) {
  		err = -EINVAL;
  		goto failure_unlock;
  	}
  
  	/* No failure allowed after this point */
  	police->tcfp_mtu = parm->mtu;
  	if (police->tcfp_mtu == 0) {
  		police->tcfp_mtu = ~0;
  		if (R_tab)
  			police->tcfp_mtu = 255 << R_tab->rate.cell_log;
  	}
  	if (R_tab) {
  		police->rate_present = true;
  		psched_ratecfg_precompute(&police->rate, &R_tab->rate, 0);
  		qdisc_put_rtab(R_tab);
  	} else {
  		police->rate_present = false;
  	}
  	if (P_tab) {
  		police->peak_present = true;
  		psched_ratecfg_precompute(&police->peak, &P_tab->rate, 0);
  		qdisc_put_rtab(P_tab);
  	} else {
  		police->peak_present = false;
  	}
  
  	if (tb[TCA_POLICE_RESULT])
  		police->tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);
  	police->tcfp_burst = PSCHED_TICKS2NS(parm->burst);
  	police->tcfp_toks = police->tcfp_burst;
  	if (police->peak_present) {
  		police->tcfp_mtu_ptoks = (s64) psched_l2t_ns(&police->peak,
  							     police->tcfp_mtu);
  		police->tcfp_ptoks = police->tcfp_mtu_ptoks;
  	}
  	police->tcf_action = parm->action;
  
  	if (tb[TCA_POLICE_AVRATE])
  		police->tcfp_ewma_rate = nla_get_u32(tb[TCA_POLICE_AVRATE]);
  
  	spin_unlock_bh(&police->tcf_lock);
  	if (ret != ACT_P_CREATED)
  		return ret;
  
  	police->tcfp_t_c = ktime_to_ns(ktime_get());
  	police->tcf_index = parm->index ? parm->index :
  		tcf_hash_new_index(a->ops->hinfo);
  	h = tcf_hash(police->tcf_index, POL_TAB_MASK);
  	spin_lock_bh(&hinfo->lock);
  	hlist_add_head(&police->tcf_head, &hinfo->htab[h]);
  	spin_unlock_bh(&hinfo->lock);
  
  	a->priv = police;
  	return ret;
  
  failure_unlock:
  	spin_unlock_bh(&police->tcf_lock);
  failure:
  	qdisc_put_rtab(P_tab);
  	qdisc_put_rtab(R_tab);
  	if (ret == ACT_P_CREATED)
  		kfree(police);
  	return err;
  }
  
  static int tcf_act_police_cleanup(struct tc_action *a, int bind)
  {
  	struct tcf_police *p = a->priv;
  	if (p)
  		return tcf_hash_release(&p->common, bind, &police_hash_info);
  	return 0;
  }
  
  static int tcf_act_police(struct sk_buff *skb, const struct tc_action *a,
  			  struct tcf_result *res)
  {
  	struct tcf_police *police = a->priv;
  	s64 now;
  	s64 toks;
  	s64 ptoks = 0;
  
  	spin_lock(&police->tcf_lock);
  
  	bstats_update(&police->tcf_bstats, skb);
  
  	if (police->tcfp_ewma_rate &&
  	    police->tcf_rate_est.bps >= police->tcfp_ewma_rate) {
  		police->tcf_qstats.overlimits++;
  		if (police->tcf_action == TC_ACT_SHOT)
  			police->tcf_qstats.drops++;
  		spin_unlock(&police->tcf_lock);
  		return police->tcf_action;
  	}
  
  	if (qdisc_pkt_len(skb) <= police->tcfp_mtu) {
  		if (!police->rate_present) {
  			spin_unlock(&police->tcf_lock);
  			return police->tcfp_result;
  		}
  
  		now = ktime_to_ns(ktime_get());
  		toks = min_t(s64, now - police->tcfp_t_c,
  			     police->tcfp_burst);
  		if (police->peak_present) {
  			ptoks = toks + police->tcfp_ptoks;
  			if (ptoks > police->tcfp_mtu_ptoks)
  				ptoks = police->tcfp_mtu_ptoks;
  			ptoks -= (s64) psched_l2t_ns(&police->peak,
  						     qdisc_pkt_len(skb));
  		}
  		toks += police->tcfp_toks;
  		if (toks > police->tcfp_burst)
  			toks = police->tcfp_burst;
  		toks -= (s64) psched_l2t_ns(&police->rate, qdisc_pkt_len(skb));
  		if ((toks|ptoks) >= 0) {
  			police->tcfp_t_c = now;
  			police->tcfp_toks = toks;
  			police->tcfp_ptoks = ptoks;
  			spin_unlock(&police->tcf_lock);
  			return police->tcfp_result;
  		}
  	}
  
  	police->tcf_qstats.overlimits++;
  	if (police->tcf_action == TC_ACT_SHOT)
  		police->tcf_qstats.drops++;
  	spin_unlock(&police->tcf_lock);
  	return police->tcf_action;
  }
  
  static int
  tcf_act_police_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
  {
  	unsigned char *b = skb_tail_pointer(skb);
  	struct tcf_police *police = a->priv;
  	struct tc_police opt = {
  		.index = police->tcf_index,
  		.action = police->tcf_action,
  		.mtu = police->tcfp_mtu,
  		.burst = PSCHED_NS2TICKS(police->tcfp_burst),
  		.refcnt = police->tcf_refcnt - ref,
  		.bindcnt = police->tcf_bindcnt - bind,
  	};
  
  	if (police->rate_present)
  		psched_ratecfg_getrate(&opt.rate, &police->rate);
  	if (police->peak_present)
  		psched_ratecfg_getrate(&opt.peakrate, &police->peak);
  	if (nla_put(skb, TCA_POLICE_TBF, sizeof(opt), &opt))
  		goto nla_put_failure;
  	if (police->tcfp_result &&
  	    nla_put_u32(skb, TCA_POLICE_RESULT, police->tcfp_result))
  		goto nla_put_failure;
  	if (police->tcfp_ewma_rate &&
  	    nla_put_u32(skb, TCA_POLICE_AVRATE, police->tcfp_ewma_rate))
  		goto nla_put_failure;
  	return skb->len;
  
  nla_put_failure:
  	nlmsg_trim(skb, b);
  	return -1;
  }
  
  MODULE_AUTHOR("Alexey Kuznetsov");
  MODULE_DESCRIPTION("Policing actions");
  MODULE_LICENSE("GPL");
  
  static struct tc_action_ops act_police_ops = {
  	.kind		=	"police",
  	.hinfo		=	&police_hash_info,
  	.type		=	TCA_ID_POLICE,
  	.owner		=	THIS_MODULE,
  	.act		=	tcf_act_police,
  	.dump		=	tcf_act_police_dump,
  	.cleanup	=	tcf_act_police_cleanup,
  	.init		=	tcf_act_police_locate,
  	.walk		=	tcf_act_police_walker
  };
  
  static int __init
  police_init_module(void)
  {
  	int err = tcf_hashinfo_init(&police_hash_info, POL_TAB_MASK);
  	if (err)
  		return err;
  	err = tcf_register_action(&act_police_ops);
  	if (err)
  		tcf_hashinfo_destroy(&police_hash_info);
  	return err;
  }
  
  static void __exit
  police_cleanup_module(void)
  {
  	tcf_hashinfo_destroy(&police_hash_info);
  	tcf_unregister_action(&act_police_ops);
  }
  
  module_init(police_init_module);
  module_exit(police_cleanup_module);