/*

   * net/sched/act_mirred.c	packet mirroring and redirect actions

   *
   *		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:	Jamal Hadi Salim (2002-4)
   *
   * TODO: Add ingress support (and socket redirect support)
   *
   */

  #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/gfp.h>

  #include <linux/if_arp.h>

  #include <net/net_namespace.h>

  #include <net/netlink.h>

  #include <net/pkt_sched.h>
  #include <linux/tc_act/tc_mirred.h>
  #include <net/tc_act/tc_mirred.h>

  static LIST_HEAD(mirred_list);

  static DEFINE_SPINLOCK(mirred_list_lock);

  static bool tcf_mirred_is_act_redirect(int action)
  {
  	return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
  }

  static bool tcf_mirred_act_wants_ingress(int action)

  {
  	switch (action) {
  	case TCA_EGRESS_REDIR:
  	case TCA_EGRESS_MIRROR:

  		return false;

  	case TCA_INGRESS_REDIR:
  	case TCA_INGRESS_MIRROR:

  		return true;

  	default:
  		BUG();
  	}
  }

  static void tcf_mirred_release(struct tc_action *a, int bind)

  {

  	struct tcf_mirred *m = to_mirred(a);

  	struct net_device *dev;

  	/* We could be called either in a RCU callback or with RTNL lock held. */
  	spin_lock_bh(&mirred_list_lock);

  	list_del(&m->tcfm_list);

  	dev = rcu_dereference_protected(m->tcfm_dev, 1);

  	if (dev)
  		dev_put(dev);

  	spin_unlock_bh(&mirred_list_lock);

  }

  static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  	[TCA_MIRRED_PARMS]	= { .len = sizeof(struct tc_mirred) },
  };

  static unsigned int mirred_net_id;

  static struct tc_action_ops act_mirred_ops;

  static int tcf_mirred_init(struct net *net, struct nlattr *nla,

  			   struct nlattr *est, struct tc_action **a, int ovr,

  			   int bind)

  {

  	struct tc_action_net *tn = net_generic(net, mirred_net_id);

  	struct nlattr *tb[TCA_MIRRED_MAX + 1];

  	bool mac_header_xmit = false;

  	struct tc_mirred *parm;

  	struct tcf_mirred *m;

  	struct net_device *dev;

  	bool exists = false;

  	int ret;

  	if (nla == NULL)

  		return -EINVAL;

  	ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, NULL);

  	if (ret < 0)
  		return ret;

  	if (tb[TCA_MIRRED_PARMS] == NULL)

  		return -EINVAL;

  	parm = nla_data(tb[TCA_MIRRED_PARMS]);

  	exists = tcf_idr_check(tn, parm->index, a, bind);

  	if (exists && bind)
  		return 0;

  	switch (parm->eaction) {
  	case TCA_EGRESS_MIRROR:
  	case TCA_EGRESS_REDIR:

  	case TCA_INGRESS_REDIR:
  	case TCA_INGRESS_MIRROR:

  		break;
  	default:

  		if (exists)

  			tcf_idr_release(*a, bind);

  		return -EINVAL;
  	}

  	if (parm->ifindex) {

  		dev = __dev_get_by_index(net, parm->ifindex);

  		if (dev == NULL) {
  			if (exists)

  				tcf_idr_release(*a, bind);

  			return -ENODEV;

  		}

  		mac_header_xmit = dev_is_mac_header_xmit(dev);

  	} else {
  		dev = NULL;

  	}

  	if (!exists) {

  		if (dev == NULL)

  			return -EINVAL;

  		ret = tcf_idr_create(tn, parm->index, est, a,
  				     &act_mirred_ops, bind, true);

  		if (ret)
  			return ret;

  		ret = ACT_P_CREATED;
  	} else {

  		tcf_idr_release(*a, bind);

  		if (!ovr)

  			return -EEXIST;

  	}

  	m = to_mirred(*a);

  	ASSERT_RTNL();

  	m->tcf_action = parm->action;
  	m->tcfm_eaction = parm->eaction;

  	if (dev != NULL) {

  		m->tcfm_ifindex = parm->ifindex;

  		if (ret != ACT_P_CREATED)

  			dev_put(rcu_dereference_protected(m->tcfm_dev, 1));

  		dev_hold(dev);

  		rcu_assign_pointer(m->tcfm_dev, dev);

  		m->tcfm_mac_header_xmit = mac_header_xmit;

  	}

  	if (ret == ACT_P_CREATED) {

  		spin_lock_bh(&mirred_list_lock);

  		list_add(&m->tcfm_list, &mirred_list);

  		spin_unlock_bh(&mirred_list_lock);

  		tcf_idr_insert(tn, *a);

  	}

  	return ret;
  }

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

  		      struct tcf_result *res)

  {

  	struct tcf_mirred *m = to_mirred(a);

  	bool m_mac_header_xmit;

  	struct net_device *dev;

  	struct sk_buff *skb2;

  	int retval, err = 0;
  	int m_eaction;
  	int mac_len;

  	tcf_lastuse_update(&m->tcf_tm);

  	bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);

  	rcu_read_lock();

  	m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
  	m_eaction = READ_ONCE(m->tcfm_eaction);

  	retval = READ_ONCE(m->tcf_action);
  	dev = rcu_dereference(m->tcfm_dev);
  	if (unlikely(!dev)) {
  		pr_notice_once("tc mirred: target device is gone
  ");

  		goto out;
  	}

  	if (unlikely(!(dev->flags & IFF_UP))) {

  		net_notice_ratelimited("tc mirred to Houston: device %s is down
  ",
  				       dev->name);

  		goto out;

  	}

  	skb2 = skb_clone(skb, GFP_ATOMIC);

  	if (!skb2)

  		goto out;

  	/* If action's target direction differs than filter's direction,
  	 * and devices expect a mac header on xmit, then mac push/pull is
  	 * needed.
  	 */

  	if (skb_at_tc_ingress(skb) != tcf_mirred_act_wants_ingress(m_eaction) &&

  	    m_mac_header_xmit) {
  		if (!skb_at_tc_ingress(skb)) {

  			/* caught at egress, act ingress: pull mac */
  			mac_len = skb_network_header(skb) - skb_mac_header(skb);
  			skb_pull_rcsum(skb2, mac_len);
  		} else {
  			/* caught at ingress, act egress: push mac */

  			skb_push_rcsum(skb2, skb->mac_len);

  		}

  	}

  
  	/* mirror is always swallowed */

  	if (tcf_mirred_is_act_redirect(m_eaction)) {
  		skb2->tc_redirected = 1;
  		skb2->tc_from_ingress = skb2->tc_at_ingress;
  	}

  	skb2->skb_iif = skb->dev->ifindex;

  	skb2->dev = dev;

  	if (!tcf_mirred_act_wants_ingress(m_eaction))

  		err = dev_queue_xmit(skb2);
  	else
  		err = netif_receive_skb(skb2);

  	if (err) {

  out:
  		qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));

  		if (tcf_mirred_is_act_redirect(m_eaction))

  			retval = TC_ACT_SHOT;

  	}
  	rcu_read_unlock();

  
  	return retval;

  }

  static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
  			     u64 lastuse)
  {

  	struct tcf_mirred *m = to_mirred(a);
  	struct tcf_t *tm = &m->tcf_tm;

  	_bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);

  	tm->lastuse = max_t(u64, tm->lastuse, lastuse);

  }

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

  {

  	unsigned char *b = skb_tail_pointer(skb);

  	struct tcf_mirred *m = to_mirred(a);

  	struct tc_mirred opt = {
  		.index   = m->tcf_index,
  		.action  = m->tcf_action,
  		.refcnt  = m->tcf_refcnt - ref,
  		.bindcnt = m->tcf_bindcnt - bind,
  		.eaction = m->tcfm_eaction,
  		.ifindex = m->tcfm_ifindex,
  	};

  	struct tcf_t t;

  	if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
  		goto nla_put_failure;

  
  	tcf_tm_dump(&t, &m->tcf_tm);

  	if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))

  		goto nla_put_failure;

  	return skb->len;

  nla_put_failure:

  	nlmsg_trim(skb, b);

  	return -1;
  }

  static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
  			     struct netlink_callback *cb, int type,

  			     const struct tc_action_ops *ops)

  {
  	struct tc_action_net *tn = net_generic(net, mirred_net_id);

  	return tcf_generic_walker(tn, skb, cb, type, ops);

  }

  static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)

  {
  	struct tc_action_net *tn = net_generic(net, mirred_net_id);

  	return tcf_idr_search(tn, a, index);

  }

  static int mirred_device_event(struct notifier_block *unused,
  			       unsigned long event, void *ptr)
  {

  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

  	struct tcf_mirred *m;

  	ASSERT_RTNL();

  	if (event == NETDEV_UNREGISTER) {
  		spin_lock_bh(&mirred_list_lock);

  		list_for_each_entry(m, &mirred_list, tcfm_list) {

  			if (rcu_access_pointer(m->tcfm_dev) == dev) {

  				dev_put(dev);

  				/* Note : no rcu grace period necessary, as
  				 * net_device are already rcu protected.
  				 */
  				RCU_INIT_POINTER(m->tcfm_dev, NULL);

  			}
  		}

  		spin_unlock_bh(&mirred_list_lock);
  	}

  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block mirred_device_notifier = {
  	.notifier_call = mirred_device_event,
  };

  static int tcf_mirred_device(const struct tc_action *a, struct net *net,
  			     struct net_device **mirred_dev)
  {
  	int ifindex = tcf_mirred_ifindex(a);
  
  	*mirred_dev = __dev_get_by_index(net, ifindex);

  	if (!*mirred_dev)

  		return -EINVAL;
  	return 0;
  }

  static struct tc_action_ops act_mirred_ops = {
  	.kind		=	"mirred",
  	.type		=	TCA_ACT_MIRRED,

  	.owner		=	THIS_MODULE,
  	.act		=	tcf_mirred,

  	.stats_update	=	tcf_stats_update,

  	.dump		=	tcf_mirred_dump,

  	.cleanup	=	tcf_mirred_release,

  	.init		=	tcf_mirred_init,

  	.walk		=	tcf_mirred_walker,
  	.lookup		=	tcf_mirred_search,

  	.size		=	sizeof(struct tcf_mirred),

  	.get_dev	=	tcf_mirred_device,

  };
  
  static __net_init int mirred_init_net(struct net *net)
  {
  	struct tc_action_net *tn = net_generic(net, mirred_net_id);

  	return tc_action_net_init(tn, &act_mirred_ops);

  }
  
  static void __net_exit mirred_exit_net(struct net *net)
  {
  	struct tc_action_net *tn = net_generic(net, mirred_net_id);
  
  	tc_action_net_exit(tn);
  }
  
  static struct pernet_operations mirred_net_ops = {
  	.init = mirred_init_net,
  	.exit = mirred_exit_net,
  	.id   = &mirred_net_id,
  	.size = sizeof(struct tc_action_net),

  };
  
  MODULE_AUTHOR("Jamal Hadi Salim(2002)");
  MODULE_DESCRIPTION("Device Mirror/redirect actions");
  MODULE_LICENSE("GPL");

  static int __init mirred_init_module(void)

  {

  	int err = register_netdevice_notifier(&mirred_device_notifier);
  	if (err)
  		return err;

  	pr_info("Mirror/redirect action on
  ");

  	return tcf_register_action(&act_mirred_ops, &mirred_net_ops);

  }

  static void __exit mirred_cleanup_module(void)

  {

  	tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);

  	unregister_netdevice_notifier(&mirred_device_notifier);

  }
  
  module_init(mirred_init_module);
  module_exit(mirred_cleanup_module);