// SPDX-License-Identifier: GPL-2.0-or-later

  /*

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

   *

   * 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 <net/pkt_cls.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);

  #define MIRRED_RECURSION_LIMIT    4
  static DEFINE_PER_CPU(unsigned int, mirred_rec_level);

  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 bool tcf_mirred_can_reinsert(int action)
  {
  	switch (action) {
  	case TC_ACT_SHOT:
  	case TC_ACT_STOLEN:
  	case TC_ACT_QUEUED:
  	case TC_ACT_TRAP:
  		return true;
  	}
  	return false;
  }

  static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m)
  {
  	return rcu_dereference_protected(m->tcfm_dev,
  					 lockdep_is_held(&m->tcf_lock));
  }

  static void tcf_mirred_release(struct tc_action *a)

  {

  	struct tcf_mirred *m = to_mirred(a);

  	struct net_device *dev;

  	spin_lock(&mirred_list_lock);

  	list_del(&m->tcfm_list);

  	spin_unlock(&mirred_list_lock);
  
  	/* last reference to action, no need to lock */
  	dev = rcu_dereference_protected(m->tcfm_dev, 1);

  	if (dev)
  		dev_put(dev);

  }

  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, bool rtnl_held,

  			   struct tcf_proto *tp,

  			   u32 flags, struct netlink_ext_ack *extack)

  {

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

  	struct nlattr *tb[TCA_MIRRED_MAX + 1];

  	struct tcf_chain *goto_ch = NULL;

  	bool mac_header_xmit = false;

  	struct tc_mirred *parm;

  	struct tcf_mirred *m;

  	struct net_device *dev;

  	bool exists = false;

  	int ret, err;

  	u32 index;

  	if (!nla) {
  		NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");

  		return -EINVAL;

  	}

  	ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla,
  					  mirred_policy, extack);

  	if (ret < 0)
  		return ret;

  	if (!tb[TCA_MIRRED_PARMS]) {
  		NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");

  		return -EINVAL;

  	}

  	parm = nla_data(tb[TCA_MIRRED_PARMS]);

  	index = parm->index;
  	err = tcf_idr_check_alloc(tn, &index, a, bind);

  	if (err < 0)
  		return err;
  	exists = err;

  	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);

  		else

  			tcf_idr_cleanup(tn, index);

  		NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");

  		return -EINVAL;
  	}

  	if (!exists) {

  		if (!parm->ifindex) {

  			tcf_idr_cleanup(tn, index);

  			NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");

  			return -EINVAL;

  		}

  		ret = tcf_idr_create_from_flags(tn, index, est, a,
  						&act_mirred_ops, bind, flags);

  		if (ret) {

  			tcf_idr_cleanup(tn, index);

  			return ret;

  		}

  		ret = ACT_P_CREATED;

  	} else if (!ovr) {

  		tcf_idr_release(*a, bind);

  		return -EEXIST;

  	}

  
  	m = to_mirred(*a);
  	if (ret == ACT_P_CREATED)
  		INIT_LIST_HEAD(&m->tcfm_list);

  	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
  	if (err < 0)
  		goto release_idr;

  	spin_lock_bh(&m->tcf_lock);

  
  	if (parm->ifindex) {
  		dev = dev_get_by_index(net, parm->ifindex);
  		if (!dev) {

  			spin_unlock_bh(&m->tcf_lock);

  			err = -ENODEV;
  			goto put_chain;

  		}
  		mac_header_xmit = dev_is_mac_header_xmit(dev);

  		dev = rcu_replace_pointer(m->tcfm_dev, dev,
  					  lockdep_is_held(&m->tcf_lock));

  		if (dev)
  			dev_put(dev);

  		m->tcfm_mac_header_xmit = mac_header_xmit;

  	}

  	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
  	m->tcfm_eaction = parm->eaction;

  	spin_unlock_bh(&m->tcf_lock);

  	if (goto_ch)
  		tcf_chain_put_by_act(goto_ch);

  	if (ret == ACT_P_CREATED) {

  		spin_lock(&mirred_list_lock);

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

  		spin_unlock(&mirred_list_lock);

  	}

  	return ret;

  put_chain:
  	if (goto_ch)
  		tcf_chain_put_by_act(goto_ch);
  release_idr:
  	tcf_idr_release(*a, bind);
  	return err;

  }

  static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
  			  struct tcf_result *res)

  {

  	struct tcf_mirred *m = to_mirred(a);

  	struct sk_buff *skb2 = skb;

  	bool m_mac_header_xmit;

  	struct net_device *dev;

  	unsigned int rec_level;

  	int retval, err = 0;

  	bool use_reinsert;
  	bool want_ingress;
  	bool is_redirect;

  	bool expects_nh;

  	int m_eaction;
  	int mac_len;

  	bool at_nh;

  	rec_level = __this_cpu_inc_return(mirred_rec_level);
  	if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
  		net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s
  ",
  				     netdev_name(skb->dev));
  		__this_cpu_dec(mirred_rec_level);
  		return TC_ACT_SHOT;
  	}

  	tcf_lastuse_update(&m->tcf_tm);

  	tcf_action_update_bstats(&m->common, skb);

  	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_bh(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;

  	}

  	/* we could easily avoid the clone only if called by ingress and clsact;
  	 * since we can't easily detect the clsact caller, skip clone only for
  	 * ingress - that covers the TC S/W datapath.
  	 */
  	is_redirect = tcf_mirred_is_act_redirect(m_eaction);
  	use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
  		       tcf_mirred_can_reinsert(retval);
  	if (!use_reinsert) {
  		skb2 = skb_clone(skb, GFP_ATOMIC);
  		if (!skb2)
  			goto out;
  	}

  	want_ingress = tcf_mirred_act_wants_ingress(m_eaction);

  
  	expects_nh = want_ingress || !m_mac_header_xmit;
  	at_nh = skb->data == skb_network_header(skb);
  	if (at_nh != expects_nh) {
  		mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
  			  skb_network_header(skb) - skb_mac_header(skb);
  		if (expects_nh) {
  			/* target device/action expect data at nh */

  			skb_pull_rcsum(skb2, mac_len);
  		} else {

  			/* target device/action expect data at mac */
  			skb_push_rcsum(skb2, mac_len);

  		}

  	}

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

  	/* mirror is always swallowed */

  	if (is_redirect) {

  		skb_set_redirected(skb2, skb2->tc_at_ingress);

  		/* let's the caller reinsert the packet, if possible */
  		if (use_reinsert) {
  			res->ingress = want_ingress;

  			if (skb_tc_reinsert(skb, res))
  				tcf_action_inc_overlimit_qstats(&m->common);

  			__this_cpu_dec(mirred_rec_level);

  			return TC_ACT_CONSUMED;

  		}

  	}

  	if (!want_ingress)

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

  	if (err) {

  out:

  		tcf_action_inc_overlimit_qstats(&m->common);

  		if (tcf_mirred_is_act_redirect(m_eaction))

  			retval = TC_ACT_SHOT;

  	}

  	__this_cpu_dec(mirred_rec_level);

  
  	return retval;

  }

  static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets,
  			     u64 drops, u64 lastuse, bool hw)

  {

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

  	tcf_action_update_stats(a, bytes, packets, drops, hw);

  	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,

  		.refcnt  = refcount_read(&m->tcf_refcnt) - ref,
  		.bindcnt = atomic_read(&m->tcf_bindcnt) - bind,

  	};

  	struct net_device *dev;

  	struct tcf_t t;

  	spin_lock_bh(&m->tcf_lock);

  	opt.action = m->tcf_action;
  	opt.eaction = m->tcfm_eaction;
  	dev = tcf_mirred_dev_dereference(m);
  	if (dev)
  		opt.ifindex = dev->ifindex;

  	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;

  	spin_unlock_bh(&m->tcf_lock);

  	return skb->len;

  nla_put_failure:

  	spin_unlock_bh(&m->tcf_lock);

  	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 netlink_ext_ack *extack)

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

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

  }

  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(&mirred_list_lock);

  		list_for_each_entry(m, &mirred_list, tcfm_list) {

  			spin_lock_bh(&m->tcf_lock);

  			if (tcf_mirred_dev_dereference(m) == 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(&m->tcf_lock);

  		}

  		spin_unlock(&mirred_list_lock);

  	}

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

  static void tcf_mirred_dev_put(void *priv)
  {
  	struct net_device *dev = priv;
  
  	dev_put(dev);
  }
  
  static struct net_device *
  tcf_mirred_get_dev(const struct tc_action *a,
  		   tc_action_priv_destructor *destructor)

  {

  	struct tcf_mirred *m = to_mirred(a);

  	struct net_device *dev;

  	rcu_read_lock();
  	dev = rcu_dereference(m->tcfm_dev);

  	if (dev) {

  		dev_hold(dev);

  		*destructor = tcf_mirred_dev_put;
  	}

  	rcu_read_unlock();

  	return dev;
  }

  static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
  {
  	return nla_total_size(sizeof(struct tc_mirred));
  }

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

  	.id		=	TCA_ID_MIRRED,

  	.owner		=	THIS_MODULE,

  	.act		=	tcf_mirred_act,

  	.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,

  	.get_fill_size	=	tcf_mirred_get_fill_size,

  	.size		=	sizeof(struct tcf_mirred),

  	.get_dev	=	tcf_mirred_get_dev,

  };
  
  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(net, tn, &act_mirred_ops);

  }

  static void __net_exit mirred_exit_net(struct list_head *net_list)

  {

  	tc_action_net_exit(net_list, mirred_net_id);

  }
  
  static struct pernet_operations mirred_net_ops = {
  	.init = mirred_init_net,

  	.exit_batch = 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
  ");

  	err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
  	if (err)
  		unregister_netdevice_notifier(&mirred_device_notifier);
  
  	return err;

  }

  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);