text: /*
   * net/sched/cls_api.c	Packet classifier API.
   *
   *		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>
   *
   * Changes:
   *
   * Eduardo J. Blanco <ejbs@netlabs.com.uy> :990222: kmod support
   *
   */
  
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/err.h>
  #include <linux/skbuff.h>
  #include <linux/init.h>
  #include <linux/kmod.h>
  #include <linux/slab.h>
  #include <linux/idr.h>
  #include <net/net_namespace.h>
  #include <net/sock.h>
  #include <net/netlink.h>
  #include <net/pkt_sched.h>
  #include <net/pkt_cls.h>
  
  /* The list of all installed classifier types */
  static LIST_HEAD(tcf_proto_base);
  
  /* Protects list of registered TC modules. It is pure SMP lock. */
  static DEFINE_RWLOCK(cls_mod_lock);
  
  /* Find classifier type by string name */
  
  static const struct tcf_proto_ops *tcf_proto_lookup_ops(const char *kind)
  {
  	const struct tcf_proto_ops *t, *res = NULL;
  
  	if (kind) {
  		read_lock(&cls_mod_lock);
  		list_for_each_entry(t, &tcf_proto_base, head) {
  			if (strcmp(kind, t->kind) == 0) {
  				if (try_module_get(t->owner))
  					res = t;
  				break;
  			}
  		}
  		read_unlock(&cls_mod_lock);
  	}
  	return res;
  }
  
  /* Register(unregister) new classifier type */
  
  int register_tcf_proto_ops(struct tcf_proto_ops *ops)
  {
  	struct tcf_proto_ops *t;
  	int rc = -EEXIST;
  
  	write_lock(&cls_mod_lock);
  	list_for_each_entry(t, &tcf_proto_base, head)
  		if (!strcmp(ops->kind, t->kind))
  			goto out;
  
  	list_add_tail(&ops->head, &tcf_proto_base);
  	rc = 0;
  out:
  	write_unlock(&cls_mod_lock);
  	return rc;
  }
  EXPORT_SYMBOL(register_tcf_proto_ops);
  
  static struct workqueue_struct *tc_filter_wq;
  
  int unregister_tcf_proto_ops(struct tcf_proto_ops *ops)
  {
  	struct tcf_proto_ops *t;
  	int rc = -ENOENT;
  
  	/* Wait for outstanding call_rcu()s, if any, from a
  	 * tcf_proto_ops's destroy() handler.
  	 */
  	rcu_barrier();
  	flush_workqueue(tc_filter_wq);
  
  	write_lock(&cls_mod_lock);
  	list_for_each_entry(t, &tcf_proto_base, head) {
  		if (t == ops) {
  			list_del(&t->head);
  			rc = 0;
  			break;
  		}
  	}
  	write_unlock(&cls_mod_lock);
  	return rc;
  }
  EXPORT_SYMBOL(unregister_tcf_proto_ops);
  
  bool tcf_queue_work(struct rcu_work *rwork, work_func_t func)
  {
  	INIT_RCU_WORK(rwork, func);
  	return queue_rcu_work(tc_filter_wq, rwork);
  }
  EXPORT_SYMBOL(tcf_queue_work);
  
  /* Select new prio value from the range, managed by kernel. */
  
  static inline u32 tcf_auto_prio(struct tcf_proto *tp)
  {
  	u32 first = TC_H_MAKE(0xC0000000U, 0U);
  
  	if (tp)
  		first = tp->prio - 1;
  
  	return TC_H_MAJ(first);
  }
  
  static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol,
  					  u32 prio, struct tcf_chain *chain,
  					  struct netlink_ext_ack *extack)
  {
  	struct tcf_proto *tp;
  	int err;
  
  	tp = kzalloc(sizeof(*tp), GFP_KERNEL);
  	if (!tp)
  		return ERR_PTR(-ENOBUFS);
  
  	err = -ENOENT;
  	tp->ops = tcf_proto_lookup_ops(kind);
  	if (!tp->ops) {
  #ifdef CONFIG_MODULES
  		rtnl_unlock();
  		request_module("cls_%s", kind);
  		rtnl_lock();
  		tp->ops = tcf_proto_lookup_ops(kind);
  		/* We dropped the RTNL semaphore in order to perform
  		 * the module load. So, even if we succeeded in loading
  		 * the module we have to replay the request. We indicate
  		 * this using -EAGAIN.
  		 */
  		if (tp->ops) {
  			module_put(tp->ops->owner);
  			err = -EAGAIN;
  		} else {
  			NL_SET_ERR_MSG(extack, "TC classifier not found");
  			err = -ENOENT;
  		}
  #endif
  		goto errout;
  	}
  	tp->classify = tp->ops->classify;
  	tp->protocol = protocol;
  	tp->prio = prio;
  	tp->chain = chain;
  
  	err = tp->ops->init(tp);
  	if (err) {
  		module_put(tp->ops->owner);
  		goto errout;
  	}
  	return tp;
  
  errout:
  	kfree(tp);
  	return ERR_PTR(err);
  }
  
  static void tcf_proto_destroy(struct tcf_proto *tp,
  			      struct netlink_ext_ack *extack)
  {
  	tp->ops->destroy(tp, extack);
  	module_put(tp->ops->owner);
  	kfree_rcu(tp, rcu);
  }
  
  struct tcf_filter_chain_list_item {
  	struct list_head list;
  	tcf_chain_head_change_t *chain_head_change;
  	void *chain_head_change_priv;
  };
  
  static struct tcf_chain *tcf_chain_create(struct tcf_block *block,
  					  u32 chain_index)
  {
  	struct tcf_chain *chain;
  
  	chain = kzalloc(sizeof(*chain), GFP_KERNEL);
  	if (!chain)
  		return NULL;
  	INIT_LIST_HEAD(&chain->filter_chain_list);
  	list_add_tail(&chain->list, &block->chain_list);
  	chain->block = block;
  	chain->index = chain_index;
  	chain->refcnt = 1;
  	return chain;
  }
  
  static void tcf_chain_head_change_item(struct tcf_filter_chain_list_item *item,
  				       struct tcf_proto *tp_head)
  {
  	if (item->chain_head_change)
  		item->chain_head_change(tp_head, item->chain_head_change_priv);
  }
  static void tcf_chain_head_change(struct tcf_chain *chain,
  				  struct tcf_proto *tp_head)
  {
  	struct tcf_filter_chain_list_item *item;
  
  	list_for_each_entry(item, &chain->filter_chain_list, list)
  		tcf_chain_head_change_item(item, tp_head);
  }
  
  static void tcf_chain_flush(struct tcf_chain *chain)
  {
  	struct tcf_proto *tp = rtnl_dereference(chain->filter_chain);
  
  	tcf_chain_head_change(chain, NULL);
  	while (tp) {
  		RCU_INIT_POINTER(chain->filter_chain, tp->next);
  		tcf_proto_destroy(tp, NULL);
  		tp = rtnl_dereference(chain->filter_chain);
  		tcf_chain_put(chain);
  	}
  }
  
  static void tcf_chain_destroy(struct tcf_chain *chain)
  {
  	struct tcf_block *block = chain->block;
  
  	list_del(&chain->list);
  	kfree(chain);
  	if (list_empty(&block->chain_list))
  		kfree(block);
  }
  
  static void tcf_chain_hold(struct tcf_chain *chain)
  {
  	++chain->refcnt;
  }
  
  struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index,
  				bool create)
  {
  	struct tcf_chain *chain;
  
  	list_for_each_entry(chain, &block->chain_list, list) {
  		if (chain->index == chain_index) {
  			tcf_chain_hold(chain);
  			return chain;
  		}
  	}
  
  	return create ? tcf_chain_create(block, chain_index) : NULL;
  }
  EXPORT_SYMBOL(tcf_chain_get);
  
  void tcf_chain_put(struct tcf_chain *chain)
  {
  	if (--chain->refcnt == 0)
  		tcf_chain_destroy(chain);
  }
  EXPORT_SYMBOL(tcf_chain_put);
  
  static bool tcf_block_offload_in_use(struct tcf_block *block)
  {
  	return block->offloadcnt;
  }
  
  static int tcf_block_offload_cmd(struct tcf_block *block,
  				 struct net_device *dev,
  				 struct tcf_block_ext_info *ei,
  				 enum tc_block_command command)
  {
  	struct tc_block_offload bo = {};
  
  	bo.command = command;
  	bo.binder_type = ei->binder_type;
  	bo.block = block;
  	return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_BLOCK, &bo);
  }
  
  static int tcf_block_offload_bind(struct tcf_block *block, struct Qdisc *q,
  				  struct tcf_block_ext_info *ei)
  {
  	struct net_device *dev = q->dev_queue->dev;
  	int err;
  
  	if (!dev->netdev_ops->ndo_setup_tc)
  		goto no_offload_dev_inc;
  
  	/* If tc offload feature is disabled and the block we try to bind
  	 * to already has some offloaded filters, forbid to bind.
  	 */
  	if (!tc_can_offload(dev) && tcf_block_offload_in_use(block))
  		return -EOPNOTSUPP;
  
  	err = tcf_block_offload_cmd(block, dev, ei, TC_BLOCK_BIND);
  	if (err == -EOPNOTSUPP)
  		goto no_offload_dev_inc;
  	return err;
  
  no_offload_dev_inc:
  	if (tcf_block_offload_in_use(block))
  		return -EOPNOTSUPP;
  	block->nooffloaddevcnt++;
  	return 0;
  }
  
  static void tcf_block_offload_unbind(struct tcf_block *block, struct Qdisc *q,
  				     struct tcf_block_ext_info *ei)
  {
  	struct net_device *dev = q->dev_queue->dev;
  	int err;
  
  	if (!dev->netdev_ops->ndo_setup_tc)
  		goto no_offload_dev_dec;
  	err = tcf_block_offload_cmd(block, dev, ei, TC_BLOCK_UNBIND);
  	if (err == -EOPNOTSUPP)
  		goto no_offload_dev_dec;
  	return;
  
  no_offload_dev_dec:
  	WARN_ON(block->nooffloaddevcnt-- == 0);
  }
  
  static int
  tcf_chain_head_change_cb_add(struct tcf_chain *chain,
  			     struct tcf_block_ext_info *ei,
  			     struct netlink_ext_ack *extack)
  {
  	struct tcf_filter_chain_list_item *item;
  
  	item = kmalloc(sizeof(*item), GFP_KERNEL);
  	if (!item) {
  		NL_SET_ERR_MSG(extack, "Memory allocation for head change callback item failed");
  		return -ENOMEM;
  	}
  	item->chain_head_change = ei->chain_head_change;
  	item->chain_head_change_priv = ei->chain_head_change_priv;
  	if (chain->filter_chain)
  		tcf_chain_head_change_item(item, chain->filter_chain);
  	list_add(&item->list, &chain->filter_chain_list);
  	return 0;
  }
  
  static void
  tcf_chain_head_change_cb_del(struct tcf_chain *chain,
  			     struct tcf_block_ext_info *ei)
  {
  	struct tcf_filter_chain_list_item *item;
  
  	list_for_each_entry(item, &chain->filter_chain_list, list) {
  		if ((!ei->chain_head_change && !ei->chain_head_change_priv) ||
  		    (item->chain_head_change == ei->chain_head_change &&
  		     item->chain_head_change_priv == ei->chain_head_change_priv)) {
  			tcf_chain_head_change_item(item, NULL);
  			list_del(&item->list);
  			kfree(item);
  			return;
  		}
  	}
  	WARN_ON(1);
  }
  
  struct tcf_net {
  	struct idr idr;
  };
  
  static unsigned int tcf_net_id;
  
  static int tcf_block_insert(struct tcf_block *block, struct net *net,
  			    struct netlink_ext_ack *extack)
  {
  	struct tcf_net *tn = net_generic(net, tcf_net_id);
  
  	return idr_alloc_u32(&tn->idr, block, &block->index, block->index,
  			     GFP_KERNEL);
  }
  
  static void tcf_block_remove(struct tcf_block *block, struct net *net)
  {
  	struct tcf_net *tn = net_generic(net, tcf_net_id);
  
  	idr_remove(&tn->idr, block->index);
  }
  
  static struct tcf_block *tcf_block_create(struct net *net, struct Qdisc *q,
  					  u32 block_index,
  					  struct netlink_ext_ack *extack)
  {
  	struct tcf_block *block;
  	struct tcf_chain *chain;
  	int err;
  
  	block = kzalloc(sizeof(*block), GFP_KERNEL);
  	if (!block) {
  		NL_SET_ERR_MSG(extack, "Memory allocation for block failed");
  		return ERR_PTR(-ENOMEM);
  	}
  	INIT_LIST_HEAD(&block->chain_list);
  	INIT_LIST_HEAD(&block->cb_list);
  	INIT_LIST_HEAD(&block->owner_list);
  
  	/* Create chain 0 by default, it has to be always present. */
  	chain = tcf_chain_create(block, 0);
  	if (!chain) {
  		NL_SET_ERR_MSG(extack, "Failed to create new tcf chain");
  		err = -ENOMEM;
  		goto err_chain_create;
  	}
  	block->refcnt = 1;
  	block->net = net;
  	block->index = block_index;
  
  	/* Don't store q pointer for blocks which are shared */
  	if (!tcf_block_shared(block))
  		block->q = q;
  	return block;
  
  err_chain_create:
  	kfree(block);
  	return ERR_PTR(err);
  }
  
  static struct tcf_block *tcf_block_lookup(struct net *net, u32 block_index)
  {
  	struct tcf_net *tn = net_generic(net, tcf_net_id);
  
  	return idr_find(&tn->idr, block_index);
  }
  
  /* Find tcf block.
   * Set q, parent, cl when appropriate.
   */
  
  static struct tcf_block *tcf_block_find(struct net *net, struct Qdisc **q,
  					u32 *parent, unsigned long *cl,
  					int ifindex, u32 block_index,
  					struct netlink_ext_ack *extack)
  {
  	struct tcf_block *block;
  
  	if (ifindex == TCM_IFINDEX_MAGIC_BLOCK) {
  		block = tcf_block_lookup(net, block_index);
  		if (!block) {
  			NL_SET_ERR_MSG(extack, "Block of given index was not found");
  			return ERR_PTR(-EINVAL);
  		}
  	} else {
  		const struct Qdisc_class_ops *cops;
  		struct net_device *dev;
  
  		/* Find link */
  		dev = __dev_get_by_index(net, ifindex);
  		if (!dev)
  			return ERR_PTR(-ENODEV);
  
  		/* Find qdisc */
  		if (!*parent) {
  			*q = dev->qdisc;
  			*parent = (*q)->handle;
  		} else {
  			*q = qdisc_lookup(dev, TC_H_MAJ(*parent));
  			if (!*q) {
  				NL_SET_ERR_MSG(extack, "Parent Qdisc doesn't exists");
  				return ERR_PTR(-EINVAL);
  			}
  		}
  
  		/* Is it classful? */
  		cops = (*q)->ops->cl_ops;
  		if (!cops) {
  			NL_SET_ERR_MSG(extack, "Qdisc not classful");
  			return ERR_PTR(-EINVAL);
  		}
  
  		if (!cops->tcf_block) {
  			NL_SET_ERR_MSG(extack, "Class doesn't support blocks");
  			return ERR_PTR(-EOPNOTSUPP);
  		}
  
  		/* Do we search for filter, attached to class? */
  		if (TC_H_MIN(*parent)) {
  			*cl = cops->find(*q, *parent);
  			if (*cl == 0) {
  				NL_SET_ERR_MSG(extack, "Specified class doesn't exist");
  				return ERR_PTR(-ENOENT);
  			}
  		}
  
  		/* And the last stroke */
  		block = cops->tcf_block(*q, *cl, extack);
  		if (!block)
  			return ERR_PTR(-EINVAL);
  		if (tcf_block_shared(block)) {
  			NL_SET_ERR_MSG(extack, "This filter block is shared. Please use the block index to manipulate the filters");
  			return ERR_PTR(-EOPNOTSUPP);
  		}
  	}
  
  	return block;
  }
  
  static struct tcf_chain *tcf_block_chain_zero(struct tcf_block *block)
  {
  	return list_first_entry(&block->chain_list, struct tcf_chain, list);
  }
  
  struct tcf_block_owner_item {
  	struct list_head list;
  	struct Qdisc *q;
  	enum tcf_block_binder_type binder_type;
  };
  
  static void
  tcf_block_owner_netif_keep_dst(struct tcf_block *block,
  			       struct Qdisc *q,
  			       enum tcf_block_binder_type binder_type)
  {
  	if (block->keep_dst &&
  	    binder_type != TCF_BLOCK_BINDER_TYPE_CLSACT_INGRESS &&
  	    binder_type != TCF_BLOCK_BINDER_TYPE_CLSACT_EGRESS)
  		netif_keep_dst(qdisc_dev(q));
  }
  
  void tcf_block_netif_keep_dst(struct tcf_block *block)
  {
  	struct tcf_block_owner_item *item;
  
  	block->keep_dst = true;
  	list_for_each_entry(item, &block->owner_list, list)
  		tcf_block_owner_netif_keep_dst(block, item->q,
  					       item->binder_type);
  }
  EXPORT_SYMBOL(tcf_block_netif_keep_dst);
  
  static int tcf_block_owner_add(struct tcf_block *block,
  			       struct Qdisc *q,
  			       enum tcf_block_binder_type binder_type)
  {
  	struct tcf_block_owner_item *item;
  
  	item = kmalloc(sizeof(*item), GFP_KERNEL);
  	if (!item)
  		return -ENOMEM;
  	item->q = q;
  	item->binder_type = binder_type;
  	list_add(&item->list, &block->owner_list);
  	return 0;
  }
  
  static void tcf_block_owner_del(struct tcf_block *block,
  				struct Qdisc *q,
  				enum tcf_block_binder_type binder_type)
  {
  	struct tcf_block_owner_item *item;
  
  	list_for_each_entry(item, &block->owner_list, list) {
  		if (item->q == q && item->binder_type == binder_type) {
  			list_del(&item->list);
  			kfree(item);
  			return;
  		}
  	}
  	WARN_ON(1);
  }
  
  int tcf_block_get_ext(struct tcf_block **p_block, struct Qdisc *q,
  		      struct tcf_block_ext_info *ei,
  		      struct netlink_ext_ack *extack)
  {
  	struct net *net = qdisc_net(q);
  	struct tcf_block *block = NULL;
  	bool created = false;
  	int err;
  
  	if (ei->block_index) {
  		/* block_index not 0 means the shared block is requested */
  		block = tcf_block_lookup(net, ei->block_index);
  		if (block)
  			block->refcnt++;
  	}
  
  	if (!block) {
  		block = tcf_block_create(net, q, ei->block_index, extack);
  		if (IS_ERR(block))
  			return PTR_ERR(block);
  		created = true;
  		if (tcf_block_shared(block)) {
  			err = tcf_block_insert(block, net, extack);
  			if (err)
  				goto err_block_insert;
  		}
  	}
  
  	err = tcf_block_owner_add(block, q, ei->binder_type);
  	if (err)
  		goto err_block_owner_add;
  
  	tcf_block_owner_netif_keep_dst(block, q, ei->binder_type);
  
  	err = tcf_chain_head_change_cb_add(tcf_block_chain_zero(block),
  					   ei, extack);
  	if (err)
  		goto err_chain_head_change_cb_add;
  
  	err = tcf_block_offload_bind(block, q, ei);
  	if (err)
  		goto err_block_offload_bind;
  
  	*p_block = block;
  	return 0;
  
  err_block_offload_bind:
  	tcf_chain_head_change_cb_del(tcf_block_chain_zero(block), ei);
  err_chain_head_change_cb_add:
  	tcf_block_owner_del(block, q, ei->binder_type);
  err_block_owner_add:
  	if (created) {
  		if (tcf_block_shared(block))
  			tcf_block_remove(block, net);
  err_block_insert:
  		kfree(tcf_block_chain_zero(block));
  		kfree(block);
  	} else {
  		block->refcnt--;
  	}
  	return err;
  }
  EXPORT_SYMBOL(tcf_block_get_ext);
  
  static void tcf_chain_head_change_dflt(struct tcf_proto *tp_head, void *priv)
  {
  	struct tcf_proto __rcu **p_filter_chain = priv;
  
  	rcu_assign_pointer(*p_filter_chain, tp_head);
  }
  
  int tcf_block_get(struct tcf_block **p_block,
  		  struct tcf_proto __rcu **p_filter_chain, struct Qdisc *q,
  		  struct netlink_ext_ack *extack)
  {
  	struct tcf_block_ext_info ei = {
  		.chain_head_change = tcf_chain_head_change_dflt,
  		.chain_head_change_priv = p_filter_chain,
  	};
  
  	WARN_ON(!p_filter_chain);
  	return tcf_block_get_ext(p_block, q, &ei, extack);
  }
  EXPORT_SYMBOL(tcf_block_get);
  
  /* XXX: Standalone actions are not allowed to jump to any chain, and bound
   * actions should be all removed after flushing.
   */
  void tcf_block_put_ext(struct tcf_block *block, struct Qdisc *q,
  		       struct tcf_block_ext_info *ei)
  {
  	struct tcf_chain *chain, *tmp;
  
  	if (!block)
  		return;
  	tcf_chain_head_change_cb_del(tcf_block_chain_zero(block), ei);
  	tcf_block_owner_del(block, q, ei->binder_type);
  
  	if (--block->refcnt == 0) {
  		if (tcf_block_shared(block))
  			tcf_block_remove(block, block->net);
  
  		/* Hold a refcnt for all chains, so that they don't disappear
  		 * while we are iterating.
  		 */
  		list_for_each_entry(chain, &block->chain_list, list)
  			tcf_chain_hold(chain);
  
  		list_for_each_entry(chain, &block->chain_list, list)
  			tcf_chain_flush(chain);
  	}
  
  	tcf_block_offload_unbind(block, q, ei);
  
  	if (block->refcnt == 0) {
  		/* At this point, all the chains should have refcnt >= 1. */
  		list_for_each_entry_safe(chain, tmp, &block->chain_list, list)
  			tcf_chain_put(chain);
  
  		/* Finally, put chain 0 and allow block to be freed. */
  		tcf_chain_put(tcf_block_chain_zero(block));
  	}
  }
  EXPORT_SYMBOL(tcf_block_put_ext);
  
  void tcf_block_put(struct tcf_block *block)
  {
  	struct tcf_block_ext_info ei = {0, };
  
  	if (!block)
  		return;
  	tcf_block_put_ext(block, block->q, &ei);
  }
  
  EXPORT_SYMBOL(tcf_block_put);
  
  struct tcf_block_cb {
  	struct list_head list;
  	tc_setup_cb_t *cb;
  	void *cb_ident;
  	void *cb_priv;
  	unsigned int refcnt;
  };
  
  void *tcf_block_cb_priv(struct tcf_block_cb *block_cb)
  {
  	return block_cb->cb_priv;
  }
  EXPORT_SYMBOL(tcf_block_cb_priv);
  
  struct tcf_block_cb *tcf_block_cb_lookup(struct tcf_block *block,
  					 tc_setup_cb_t *cb, void *cb_ident)
  {	struct tcf_block_cb *block_cb;
  
  	list_for_each_entry(block_cb, &block->cb_list, list)
  		if (block_cb->cb == cb && block_cb->cb_ident == cb_ident)
  			return block_cb;
  	return NULL;
  }
  EXPORT_SYMBOL(tcf_block_cb_lookup);
  
  void tcf_block_cb_incref(struct tcf_block_cb *block_cb)
  {
  	block_cb->refcnt++;
  }
  EXPORT_SYMBOL(tcf_block_cb_incref);
  
  unsigned int tcf_block_cb_decref(struct tcf_block_cb *block_cb)
  {
  	return --block_cb->refcnt;
  }
  EXPORT_SYMBOL(tcf_block_cb_decref);
  
  struct tcf_block_cb *__tcf_block_cb_register(struct tcf_block *block,
  					     tc_setup_cb_t *cb, void *cb_ident,
  					     void *cb_priv)
  {
  	struct tcf_block_cb *block_cb;
  
  	/* At this point, playback of previous block cb calls is not supported,
  	 * so forbid to register to block which already has some offloaded
  	 * filters present.
  	 */
  	if (tcf_block_offload_in_use(block))
  		return ERR_PTR(-EOPNOTSUPP);
  
  	block_cb = kzalloc(sizeof(*block_cb), GFP_KERNEL);
  	if (!block_cb)
  		return ERR_PTR(-ENOMEM);
  	block_cb->cb = cb;
  	block_cb->cb_ident = cb_ident;
  	block_cb->cb_priv = cb_priv;
  	list_add(&block_cb->list, &block->cb_list);
  	return block_cb;
  }
  EXPORT_SYMBOL(__tcf_block_cb_register);
  
  int tcf_block_cb_register(struct tcf_block *block,
  			  tc_setup_cb_t *cb, void *cb_ident,
  			  void *cb_priv)
  {
  	struct tcf_block_cb *block_cb;
  
  	block_cb = __tcf_block_cb_register(block, cb, cb_ident, cb_priv);
  	return IS_ERR(block_cb) ? PTR_ERR(block_cb) : 0;
  }
  EXPORT_SYMBOL(tcf_block_cb_register);
  
  void __tcf_block_cb_unregister(struct tcf_block_cb *block_cb)
  {
  	list_del(&block_cb->list);
  	kfree(block_cb);
  }
  EXPORT_SYMBOL(__tcf_block_cb_unregister);
  
  void tcf_block_cb_unregister(struct tcf_block *block,
  			     tc_setup_cb_t *cb, void *cb_ident)
  {
  	struct tcf_block_cb *block_cb;
  
  	block_cb = tcf_block_cb_lookup(block, cb, cb_ident);
  	if (!block_cb)
  		return;
  	__tcf_block_cb_unregister(block_cb);
  }
  EXPORT_SYMBOL(tcf_block_cb_unregister);
  
  static int tcf_block_cb_call(struct tcf_block *block, enum tc_setup_type type,
  			     void *type_data, bool err_stop)
  {
  	struct tcf_block_cb *block_cb;
  	int ok_count = 0;
  	int err;
  
  	/* Make sure all netdevs sharing this block are offload-capable. */
  	if (block->nooffloaddevcnt && err_stop)
  		return -EOPNOTSUPP;
  
  	list_for_each_entry(block_cb, &block->cb_list, list) {
  		err = block_cb->cb(type, type_data, block_cb->cb_priv);
  		if (err) {
  			if (err_stop)
  				return err;
  		} else {
  			ok_count++;
  		}
  	}
  	return ok_count;
  }
  
  /* Main classifier routine: scans classifier chain attached
   * to this qdisc, (optionally) tests for protocol and asks
   * specific classifiers.
   */
  int tcf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
  		 struct tcf_result *res, bool compat_mode)
  {
  	__be16 protocol = tc_skb_protocol(skb);
  #ifdef CONFIG_NET_CLS_ACT
  	const int max_reclassify_loop = 4;
  	const struct tcf_proto *orig_tp = tp;
  	const struct tcf_proto *first_tp;
  	int limit = 0;
  
  reclassify:
  #endif
  	for (; tp; tp = rcu_dereference_bh(tp->next)) {
  		int err;
  
  		if (tp->protocol != protocol &&
  		    tp->protocol != htons(ETH_P_ALL))
  			continue;
  
  		err = tp->classify(skb, tp, res);
  #ifdef CONFIG_NET_CLS_ACT
  		if (unlikely(err == TC_ACT_RECLASSIFY && !compat_mode)) {
  			first_tp = orig_tp;
  			goto reset;
  		} else if (unlikely(TC_ACT_EXT_CMP(err, TC_ACT_GOTO_CHAIN))) {
  			first_tp = res->goto_tp;
  			goto reset;
  		}
  #endif
  		if (err >= 0)
  			return err;
  	}
  
  	return TC_ACT_UNSPEC; /* signal: continue lookup */
  #ifdef CONFIG_NET_CLS_ACT
  reset:
  	if (unlikely(limit++ >= max_reclassify_loop)) {
  		net_notice_ratelimited("%u: reclassify loop, rule prio %u, protocol %02x\n",
  				       tp->chain->block->index,
  				       tp->prio & 0xffff,
  				       ntohs(tp->protocol));
  		return TC_ACT_SHOT;
  	}
  
  	tp = first_tp;
  	protocol = tc_skb_protocol(skb);
  	goto reclassify;
  #endif
  }
  EXPORT_SYMBOL(tcf_classify);
  
  struct tcf_chain_info {
  	struct tcf_proto __rcu **pprev;
  	struct tcf_proto __rcu *next;
  };
  
  static struct tcf_proto *tcf_chain_tp_prev(struct tcf_chain_info *chain_info)
  {
  	return rtnl_dereference(*chain_info->pprev);
  }
  
  static void tcf_chain_tp_insert(struct tcf_chain *chain,
  				struct tcf_chain_info *chain_info,
  				struct tcf_proto *tp)
  {
  	if (*chain_info->pprev == chain->filter_chain)
  		tcf_chain_head_change(chain, tp);
  	RCU_INIT_POINTER(tp->next, tcf_chain_tp_prev(chain_info));
  	rcu_assign_pointer(*chain_info->pprev, tp);
  	tcf_chain_hold(chain);
  }
  
  static void tcf_chain_tp_remove(struct tcf_chain *chain,
  				struct tcf_chain_info *chain_info,
  				struct tcf_proto *tp)
  {
  	struct tcf_proto *next = rtnl_dereference(chain_info->next);
  
  	if (tp == chain->filter_chain)
  		tcf_chain_head_change(chain, next);
  	RCU_INIT_POINTER(*chain_info->pprev, next);
  	tcf_chain_put(chain);
  }
  
  static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,
  					   struct tcf_chain_info *chain_info,
  					   u32 protocol, u32 prio,
  					   bool prio_allocate)
  {
  	struct tcf_proto **pprev;
  	struct tcf_proto *tp;
  
  	/* Check the chain for existence of proto-tcf with this priority */
  	for (pprev = &chain->filter_chain;
  	     (tp = rtnl_dereference(*pprev)); pprev = &tp->next) {
  		if (tp->prio >= prio) {
  			if (tp->prio == prio) {
  				if (prio_allocate ||
  				    (tp->protocol != protocol && protocol))
  					return ERR_PTR(-EINVAL);
  			} else {
  				tp = NULL;
  			}
  			break;
  		}
  	}
  	chain_info->pprev = pprev;
  	chain_info->next = tp ? tp->next : NULL;
  	return tp;
  }
  
  static int tcf_fill_node(struct net *net, struct sk_buff *skb,
  			 struct tcf_proto *tp, struct tcf_block *block,
  			 struct Qdisc *q, u32 parent, void *fh,
  			 u32 portid, u32 seq, u16 flags, int event)
  {
  	struct tcmsg *tcm;
  	struct nlmsghdr  *nlh;
  	unsigned char *b = skb_tail_pointer(skb);
  
  	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*tcm), flags);
  	if (!nlh)
  		goto out_nlmsg_trim;
  	tcm = nlmsg_data(nlh);
  	tcm->tcm_family = AF_UNSPEC;
  	tcm->tcm__pad1 = 0;
  	tcm->tcm__pad2 = 0;
  	if (q) {
  		tcm->tcm_ifindex = qdisc_dev(q)->ifindex;
  		tcm->tcm_parent = parent;
  	} else {
  		tcm->tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
  		tcm->tcm_block_index = block->index;
  	}
  	tcm->tcm_info = TC_H_MAKE(tp->prio, tp->protocol);
  	if (nla_put_string(skb, TCA_KIND, tp->ops->kind))
  		goto nla_put_failure;
  	if (nla_put_u32(skb, TCA_CHAIN, tp->chain->index))
  		goto nla_put_failure;
  	if (!fh) {
  		tcm->tcm_handle = 0;
  	} else {
  		if (tp->ops->dump && tp->ops->dump(net, tp, fh, skb, tcm) < 0)
  			goto nla_put_failure;
  	}
  	nlh->nlmsg_len = skb_tail_pointer(skb) - b;
  	return skb->len;
  
  out_nlmsg_trim:
  nla_put_failure:
  	nlmsg_trim(skb, b);
  	return -1;
  }
  
  static int tfilter_notify(struct net *net, struct sk_buff *oskb,
  			  struct nlmsghdr *n, struct tcf_proto *tp,
  			  struct tcf_block *block, struct Qdisc *q,
  			  u32 parent, void *fh, int event, bool unicast)
  {
  	struct sk_buff *skb;
  	u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
  
  	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
  	if (!skb)
  		return -ENOBUFS;
  
  	if (tcf_fill_node(net, skb, tp, block, q, parent, fh, portid,
  			  n->nlmsg_seq, n->nlmsg_flags, event) <= 0) {
  		kfree_skb(skb);
  		return -EINVAL;
  	}
  
  	if (unicast)
  		return netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
  
  	return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
  			      n->nlmsg_flags & NLM_F_ECHO);
  }
  
  static int tfilter_del_notify(struct net *net, struct sk_buff *oskb,
  			      struct nlmsghdr *n, struct tcf_proto *tp,
  			      struct tcf_block *block, struct Qdisc *q,
  			      u32 parent, void *fh, bool unicast, bool *last,
  			      struct netlink_ext_ack *extack)
  {
  	struct sk_buff *skb;
  	u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
  	int err;
  
  	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
  	if (!skb)
  		return -ENOBUFS;
  
  	if (tcf_fill_node(net, skb, tp, block, q, parent, fh, portid,
  			  n->nlmsg_seq, n->nlmsg_flags, RTM_DELTFILTER) <= 0) {
  		NL_SET_ERR_MSG(extack, "Failed to build del event notification");
  		kfree_skb(skb);
  		return -EINVAL;
  	}
  
  	err = tp->ops->delete(tp, fh, last, extack);
  	if (err) {
  		kfree_skb(skb);
  		return err;
  	}
  
  	if (unicast)
  		return netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
  
  	err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
  			     n->nlmsg_flags & NLM_F_ECHO);
  	if (err < 0)
  		NL_SET_ERR_MSG(extack, "Failed to send filter delete notification");
  	return err;
  }
  
  static void tfilter_notify_chain(struct net *net, struct sk_buff *oskb,
  				 struct tcf_block *block, struct Qdisc *q,
  				 u32 parent, struct nlmsghdr *n,
  				 struct tcf_chain *chain, int event)
  {
  	struct tcf_proto *tp;
  
  	for (tp = rtnl_dereference(chain->filter_chain);
  	     tp; tp = rtnl_dereference(tp->next))
  		tfilter_notify(net, oskb, n, tp, block,
  			       q, parent, 0, event, false);
  }
  
  static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
  			  struct netlink_ext_ack *extack)
  {
  	struct net *net = sock_net(skb->sk);
  	struct nlattr *tca[TCA_MAX + 1];
  	struct tcmsg *t;
  	u32 protocol;
  	u32 prio;
  	bool prio_allocate;
  	u32 parent;
  	u32 chain_index;
  	struct Qdisc *q = NULL;
  	struct tcf_chain_info chain_info;
  	struct tcf_chain *chain = NULL;
  	struct tcf_block *block;
  	struct tcf_proto *tp;
  	unsigned long cl;
  	void *fh;
  	int err;
  	int tp_created;
  
  	if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
  		return -EPERM;
  
  replay:
  	tp_created = 0;
  
  	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL, extack);
  	if (err < 0)
  		return err;
  
  	t = nlmsg_data(n);
  	protocol = TC_H_MIN(t->tcm_info);
  	prio = TC_H_MAJ(t->tcm_info);
  	prio_allocate = false;
  	parent = t->tcm_parent;
  	cl = 0;
  
  	if (prio == 0) {
  		/* If no priority is provided by the user,
  		 * we allocate one.
  		 */
  		if (n->nlmsg_flags & NLM_F_CREATE) {
  			prio = TC_H_MAKE(0x80000000U, 0U);
  			prio_allocate = true;
  		} else {
  			NL_SET_ERR_MSG(extack, "Invalid filter command with priority of zero");
  			return -ENOENT;
  		}
  	}
  
  	/* Find head of filter chain. */
  
  	block = tcf_block_find(net, &q, &parent, &cl,
  			       t->tcm_ifindex, t->tcm_block_index, extack);
  	if (IS_ERR(block)) {
  		err = PTR_ERR(block);
  		goto errout;
  	}
  
  	chain_index = tca[TCA_CHAIN] ? nla_get_u32(tca[TCA_CHAIN]) : 0;
  	if (chain_index > TC_ACT_EXT_VAL_MASK) {
  		NL_SET_ERR_MSG(extack, "Specified chain index exceeds upper limit");
  		err = -EINVAL;
  		goto errout;
  	}
  	chain = tcf_chain_get(block, chain_index, true);
  	if (!chain) {
  		NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");
  		err = -ENOMEM;
  		goto errout;
  	}
  
  	tp = tcf_chain_tp_find(chain, &chain_info, protocol,
  			       prio, prio_allocate);
  	if (IS_ERR(tp)) {
  		NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");
  		err = PTR_ERR(tp);
  		goto errout;
  	}
  
  	if (tp == NULL) {
  		/* Proto-tcf does not exist, create new one */
  
  		if (tca[TCA_KIND] == NULL || !protocol) {
  			NL_SET_ERR_MSG(extack, "Filter kind and protocol must be specified");
  			err = -EINVAL;
  			goto errout;
  		}
  
  		if (!(n->nlmsg_flags & NLM_F_CREATE)) {
  			NL_SET_ERR_MSG(extack, "Need both RTM_NEWTFILTER and NLM_F_CREATE to create a new filter");
  			err = -ENOENT;
  			goto errout;
  		}
  
  		if (prio_allocate)
  			prio = tcf_auto_prio(tcf_chain_tp_prev(&chain_info));
  
  		tp = tcf_proto_create(nla_data(tca[TCA_KIND]),
  				      protocol, prio, chain, extack);
  		if (IS_ERR(tp)) {
  			err = PTR_ERR(tp);
  			goto errout;
  		}
  		tp_created = 1;
  	} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind)) {
  		NL_SET_ERR_MSG(extack, "Specified filter kind does not match existing one");
  		err = -EINVAL;
  		goto errout;
  	}
  
  	fh = tp->ops->get(tp, t->tcm_handle);
  
  	if (!fh) {
  		if (!(n->nlmsg_flags & NLM_F_CREATE)) {
  			NL_SET_ERR_MSG(extack, "Need both RTM_NEWTFILTER and NLM_F_CREATE to create a new filter");
  			err = -ENOENT;
  			goto errout;
  		}
  	} else if (n->nlmsg_flags & NLM_F_EXCL) {
  		NL_SET_ERR_MSG(extack, "Filter already exists");
  		err = -EEXIST;
  		goto errout;
  	}
  
  	err = tp->ops->change(net, skb, tp, cl, t->tcm_handle, tca, &fh,
  			      n->nlmsg_flags & NLM_F_CREATE ? TCA_ACT_NOREPLACE : TCA_ACT_REPLACE,
  			      extack);
  	if (err == 0) {
  		if (tp_created)
  			tcf_chain_tp_insert(chain, &chain_info, tp);
  		tfilter_notify(net, skb, n, tp, block, q, parent, fh,
  			       RTM_NEWTFILTER, false);
  	} else {
  		if (tp_created)
  			tcf_proto_destroy(tp, NULL);
  	}
  
  errout:
  	if (chain)
  		tcf_chain_put(chain);
  	if (err == -EAGAIN)
  		/* Replay the request. */
  		goto replay;
  	return err;
  }
  
  static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
  			  struct netlink_ext_ack *extack)
  {
  	struct net *net = sock_net(skb->sk);
  	struct nlattr *tca[TCA_MAX + 1];
  	struct tcmsg *t;
  	u32 protocol;
  	u32 prio;
  	u32 parent;
  	u32 chain_index;
  	struct Qdisc *q = NULL;
  	struct tcf_chain_info chain_info;
  	struct tcf_chain *chain = NULL;
  	struct tcf_block *block;
  	struct tcf_proto *tp = NULL;
  	unsigned long cl = 0;
  	void *fh = NULL;
  	int err;
  
  	if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
  		return -EPERM;
  
  	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL, extack);
  	if (err < 0)
  		return err;
  
  	t = nlmsg_data(n);
  	protocol = TC_H_MIN(t->tcm_info);
  	prio = TC_H_MAJ(t->tcm_info);
  	parent = t->tcm_parent;
  
  	if (prio == 0 && (protocol || t->tcm_handle || tca[TCA_KIND])) {
  		NL_SET_ERR_MSG(extack, "Cannot flush filters with protocol, handle or kind set");
  		return -ENOENT;
  	}
  
  	/* Find head of filter chain. */
  
  	block = tcf_block_find(net, &q, &parent, &cl,
  			       t->tcm_ifindex, t->tcm_block_index, extack);
  	if (IS_ERR(block)) {
  		err = PTR_ERR(block);
  		goto errout;
  	}
  
  	chain_index = tca[TCA_CHAIN] ? nla_get_u32(tca[TCA_CHAIN]) : 0;
  	if (chain_index > TC_ACT_EXT_VAL_MASK) {
  		NL_SET_ERR_MSG(extack, "Specified chain index exceeds upper limit");
  		err = -EINVAL;
  		goto errout;
  	}
  	chain = tcf_chain_get(block, chain_index, false);
  	if (!chain) {
  		NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");
  		err = -EINVAL;
  		goto errout;
  	}
  
  	if (prio == 0) {
  		tfilter_notify_chain(net, skb, block, q, parent, n,
  				     chain, RTM_DELTFILTER);
  		tcf_chain_flush(chain);
  		err = 0;
  		goto errout;
  	}
  
  	tp = tcf_chain_tp_find(chain, &chain_info, protocol,
  			       prio, false);
  	if (!tp || IS_ERR(tp)) {
  		NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");
  		err = tp ? PTR_ERR(tp) : -ENOENT;
  		goto errout;
  	} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind)) {
  		NL_SET_ERR_MSG(extack, "Specified filter kind does not match existing one");
  		err = -EINVAL;
  		goto errout;
  	}
  
  	fh = tp->ops->get(tp, t->tcm_handle);
  
  	if (!fh) {
  		if (t->tcm_handle == 0) {
  			tcf_chain_tp_remove(chain, &chain_info, tp);
  			tfilter_notify(net, skb, n, tp, block, q, parent, fh,
  				       RTM_DELTFILTER, false);
  			tcf_proto_destroy(tp, extack);
  			err = 0;
  		} else {
  			NL_SET_ERR_MSG(extack, "Specified filter handle not found");
  			err = -ENOENT;
  		}
  	} else {
  		bool last;
  
  		err = tfilter_del_notify(net, skb, n, tp, block,
  					 q, parent, fh, false, &last,
  					 extack);
  		if (err)
  			goto errout;
  		if (last) {
  			tcf_chain_tp_remove(chain, &chain_info, tp);
  			tcf_proto_destroy(tp, extack);
  		}
  	}
  
  errout:
  	if (chain)
  		tcf_chain_put(chain);
  	return err;
  }
  
  static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
  			  struct netlink_ext_ack *extack)
  {
  	struct net *net = sock_net(skb->sk);
  	struct nlattr *tca[TCA_MAX + 1];
  	struct tcmsg *t;
  	u32 protocol;
  	u32 prio;
  	u32 parent;
  	u32 chain_index;
  	struct Qdisc *q = NULL;
  	struct tcf_chain_info chain_info;
  	struct tcf_chain *chain = NULL;
  	struct tcf_block *block;
  	struct tcf_proto *tp = NULL;
  	unsigned long cl = 0;
  	void *fh = NULL;
  	int err;
  
  	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL, extack);
  	if (err < 0)
  		return err;
  
  	t = nlmsg_data(n);
  	protocol = TC_H_MIN(t->tcm_info);
  	prio = TC_H_MAJ(t->tcm_info);
  	parent = t->tcm_parent;
  
  	if (prio == 0) {
  		NL_SET_ERR_MSG(extack, "Invalid filter command with priority of zero");
  		return -ENOENT;
  	}
  
  	/* Find head of filter chain. */
  
  	block = tcf_block_find(net, &q, &parent, &cl,
  			       t->tcm_ifindex, t->tcm_block_index, extack);
  	if (IS_ERR(block)) {
  		err = PTR_ERR(block);
  		goto errout;
  	}
  
  	chain_index = tca[TCA_CHAIN] ? nla_get_u32(tca[TCA_CHAIN]) : 0;
  	if (chain_index > TC_ACT_EXT_VAL_MASK) {
  		NL_SET_ERR_MSG(extack, "Specified chain index exceeds upper limit");
  		err = -EINVAL;
  		goto errout;
  	}
  	chain = tcf_chain_get(block, chain_index, false);
  	if (!chain) {
  		NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");
  		err = -EINVAL;
  		goto errout;
  	}
  
  	tp = tcf_chain_tp_find(chain, &chain_info, protocol,
  			       prio, false);
  	if (!tp || IS_ERR(tp)) {
  		NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");
  		err = tp ? PTR_ERR(tp) : -ENOENT;
  		goto errout;
  	} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind)) {
  		NL_SET_ERR_MSG(extack, "Specified filter kind does not match existing one");
  		err = -EINVAL;
  		goto errout;
  	}
  
  	fh = tp->ops->get(tp, t->tcm_handle);
  
  	if (!fh) {
  		NL_SET_ERR_MSG(extack, "Specified filter handle not found");
  		err = -ENOENT;
  	} else {
  		err = tfilter_notify(net, skb, n, tp, block, q, parent,
  				     fh, RTM_NEWTFILTER, true);
  		if (err < 0)
  			NL_SET_ERR_MSG(extack, "Failed to send filter notify message");
  	}
  
  errout:
  	if (chain)
  		tcf_chain_put(chain);
  	return err;
  }
  
  struct tcf_dump_args {
  	struct tcf_walker w;
  	struct sk_buff *skb;
  	struct netlink_callback *cb;
  	struct tcf_block *block;
  	struct Qdisc *q;
  	u32 parent;
  };
  
  static int tcf_node_dump(struct tcf_proto *tp, void *n, struct tcf_walker *arg)
  {
  	struct tcf_dump_args *a = (void *)arg;
  	struct net *net = sock_net(a->skb->sk);
  
  	return tcf_fill_node(net, a->skb, tp, a->block, a->q, a->parent,
  			     n, NETLINK_CB(a->cb->skb).portid,
  			     a->cb->nlh->nlmsg_seq, NLM_F_MULTI,
  			     RTM_NEWTFILTER);
  }
  
  static bool tcf_chain_dump(struct tcf_chain *chain, struct Qdisc *q, u32 parent,
  			   struct sk_buff *skb, struct netlink_callback *cb,
  			   long index_start, long *p_index)
  {
  	struct net *net = sock_net(skb->sk);
  	struct tcf_block *block = chain->block;
  	struct tcmsg *tcm = nlmsg_data(cb->nlh);
  	struct tcf_dump_args arg;
  	struct tcf_proto *tp;
  
  	for (tp = rtnl_dereference(chain->filter_chain);
  	     tp; tp = rtnl_dereference(tp->next), (*p_index)++) {
  		if (*p_index < index_start)
  			continue;
  		if (TC_H_MAJ(tcm->tcm_info) &&
  		    TC_H_MAJ(tcm->tcm_info) != tp->prio)
  			continue;
  		if (TC_H_MIN(tcm->tcm_info) &&
  		    TC_H_MIN(tcm->tcm_info) != tp->protocol)
  			continue;
  		if (*p_index > index_start)
  			memset(&cb->args[1], 0,
  			       sizeof(cb->args) - sizeof(cb->args[0]));
  		if (cb->args[1] == 0) {
  			if (tcf_fill_node(net, skb, tp, block, q, parent, 0,
  					  NETLINK_CB(cb->skb).portid,
  					  cb->nlh->nlmsg_seq, NLM_F_MULTI,
  					  RTM_NEWTFILTER) <= 0)
  				return false;
  
  			cb->args[1] = 1;
  		}
  		if (!tp->ops->walk)
  			continue;
  		arg.w.fn = tcf_node_dump;
  		arg.skb = skb;
  		arg.cb = cb;
  		arg.block = block;
  		arg.q = q;
  		arg.parent = parent;
  		arg.w.stop = 0;
  		arg.w.skip = cb->args[1] - 1;
  		arg.w.count = 0;
  		tp->ops->walk(tp, &arg.w);
  		cb->args[1] = arg.w.count + 1;
  		if (arg.w.stop)
  			return false;
  	}
  	return true;
  }
  
  /* called with RTNL */
  static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
  {
  	struct net *net = sock_net(skb->sk);
  	struct nlattr *tca[TCA_MAX + 1];
  	struct Qdisc *q = NULL;
  	struct tcf_block *block;
  	struct tcf_chain *chain;
  	struct tcmsg *tcm = nlmsg_data(cb->nlh);
  	long index_start;
  	long index;
  	u32 parent;
  	int err;
  
  	if (nlmsg_len(cb->nlh) < sizeof(*tcm))
  		return skb->len;
  
  	err = nlmsg_parse(cb->nlh, sizeof(*tcm), tca, TCA_MAX, NULL, NULL);
  	if (err)
  		return err;
  
  	if (tcm->tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK) {
  		block = tcf_block_lookup(net, tcm->tcm_block_index);
  		if (!block)
  			goto out;
  		/* If we work with block index, q is NULL and parent value
  		 * will never be used in the following code. The check
  		 * in tcf_fill_node prevents it. However, compiler does not
  		 * see that far, so set parent to zero to silence the warning
  		 * about parent being uninitialized.
  		 */
  		parent = 0;
  	} else {
  		const struct Qdisc_class_ops *cops;
  		struct net_device *dev;
  		unsigned long cl = 0;
  
  		dev = __dev_get_by_index(net, tcm->tcm_ifindex);
  		if (!dev)
  			return skb->len;
  
  		parent = tcm->tcm_parent;
  		if (!parent) {
  			q = dev->qdisc;
  			parent = q->handle;
  		} else {
  			q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));
  		}
  		if (!q)
  			goto out;
  		cops = q->ops->cl_ops;
  		if (!cops)
  			goto out;
  		if (!cops->tcf_block)
  			goto out;
  		if (TC_H_MIN(tcm->tcm_parent)) {
  			cl = cops->find(q, tcm->tcm_parent);
  			if (cl == 0)
  				goto out;
  		}
  		block = cops->tcf_block(q, cl, NULL);
  		if (!block)
  			goto out;
  		if (tcf_block_shared(block))
  			q = NULL;
  	}
  
  	index_start = cb->args[0];
  	index = 0;
  
  	list_for_each_entry(chain, &block->chain_list, list) {
  		if (tca[TCA_CHAIN] &&
  		    nla_get_u32(tca[TCA_CHAIN]) != chain->index)
  			continue;
  		if (!tcf_chain_dump(chain, q, parent, skb, cb,
  				    index_start, &index)) {
  			err = -EMSGSIZE;
  			break;
  		}
  	}
  
  	cb->args[0] = index;
  
  out:
  	/* If we did no progress, the error (EMSGSIZE) is real */
  	if (skb->len == 0 && err)
  		return err;
  	return skb->len;
  }
  
  void tcf_exts_destroy(struct tcf_exts *exts)
  {
  #ifdef CONFIG_NET_CLS_ACT
  	LIST_HEAD(actions);
  
  	ASSERT_RTNL();
  	tcf_exts_to_list(exts, &actions);
  	tcf_action_destroy(&actions, TCA_ACT_UNBIND);
  	kfree(exts->actions);
  	exts->nr_actions = 0;
  #endif
  }
  EXPORT_SYMBOL(tcf_exts_destroy);
  
  int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb,
  		      struct nlattr *rate_tlv, struct tcf_exts *exts, bool ovr,
  		      struct netlink_ext_ack *extack)
  {
  #ifdef CONFIG_NET_CLS_ACT
  	{
  		struct tc_action *act;
  		size_t attr_size = 0;
  
  		if (exts->police && tb[exts->police]) {
  			act = tcf_action_init_1(net, tp, tb[exts->police],
  						rate_tlv, "police", ovr,
  						TCA_ACT_BIND, extack);
  			if (IS_ERR(act))
  				return PTR_ERR(act);
  
  			act->type = exts->type = TCA_OLD_COMPAT;
  			exts->actions[0] = act;
  			exts->nr_actions = 1;
  		} else if (exts->action && tb[exts->action]) {
  			LIST_HEAD(actions);
  			int err, i = 0;
  
  			err = tcf_action_init(net, tp, tb[exts->action],
  					      rate_tlv, NULL, ovr, TCA_ACT_BIND,
  					      &actions, &attr_size, extack);
  			if (err)
  				return err;
  			list_for_each_entry(act, &actions, list)
  				exts->actions[i++] = act;
  			exts->nr_actions = i;
  		}
  		exts->net = net;
  	}
  #else
  	if ((exts->action && tb[exts->action]) ||
  	    (exts->police && tb[exts->police])) {
  		NL_SET_ERR_MSG(extack, "Classifier actions are not supported per compile options (CONFIG_NET_CLS_ACT)");
  		return -EOPNOTSUPP;
  	}
  #endif
  
  	return 0;
  }
  EXPORT_SYMBOL(tcf_exts_validate);
  
  void tcf_exts_change(struct tcf_exts *dst, struct tcf_exts *src)
  {
  #ifdef CONFIG_NET_CLS_ACT
  	struct tcf_exts old = *dst;
  
  	*dst = *src;
  	tcf_exts_destroy(&old);
  #endif
  }
  EXPORT_SYMBOL(tcf_exts_change);
  
  #ifdef CONFIG_NET_CLS_ACT
  static struct tc_action *tcf_exts_first_act(struct tcf_exts *exts)
  {
  	if (exts->nr_actions == 0)
  		return NULL;
  	else
  		return exts->actions[0];
  }
  #endif
  
  int tcf_exts_dump(struct sk_buff *skb, struct tcf_exts *exts)
  {
  #ifdef CONFIG_NET_CLS_ACT
  	struct nlattr *nest;
  
  	if (exts->action && tcf_exts_has_actions(exts)) {
  		/*
  		 * again for backward compatible mode - we want
  		 * to work with both old and new modes of entering
  		 * tc data even if iproute2  was newer - jhs
  		 */
  		if (exts->type != TCA_OLD_COMPAT) {
  			LIST_HEAD(actions);
  
  			nest = nla_nest_start(skb, exts->action);
  			if (nest == NULL)
  				goto nla_put_failure;
  
  			tcf_exts_to_list(exts, &actions);
  			if (tcf_action_dump(skb, &actions, 0, 0) < 0)
  				goto nla_put_failure;
  			nla_nest_end(skb, nest);
  		} else if (exts->police) {
  			struct tc_action *act = tcf_exts_first_act(exts);
  			nest = nla_nest_start(skb, exts->police);
  			if (nest == NULL || !act)
  				goto nla_put_failure;
  			if (tcf_action_dump_old(skb, act, 0, 0) < 0)
  				goto nla_put_failure;
  			nla_nest_end(skb, nest);
  		}
  	}
  	return 0;
  
  nla_put_failure:
  	nla_nest_cancel(skb, nest);
  	return -1;
  #else
  	return 0;
  #endif
  }
  EXPORT_SYMBOL(tcf_exts_dump);
  
  
  int tcf_exts_dump_stats(struct sk_buff *skb, struct tcf_exts *exts)
  {
  #ifdef CONFIG_NET_CLS_ACT
  	struct tc_action *a = tcf_exts_first_act(exts);
  	if (a != NULL && tcf_action_copy_stats(skb, a, 1) < 0)
  		return -1;
  #endif
  	return 0;
  }
  EXPORT_SYMBOL(tcf_exts_dump_stats);
  
  static int tc_exts_setup_cb_egdev_call(struct tcf_exts *exts,
  				       enum tc_setup_type type,
  				       void *type_data, bool err_stop)
  {
  	int ok_count = 0;
  #ifdef CONFIG_NET_CLS_ACT
  	const struct tc_action *a;
  	struct net_device *dev;
  	int i, ret;
  
  	if (!tcf_exts_has_actions(exts))
  		return 0;
  
  	for (i = 0; i < exts->nr_actions; i++) {
  		a = exts->actions[i];
  		if (!a->ops->get_dev)
  			continue;
  		dev = a->ops->get_dev(a);
  		if (!dev)
  			continue;
  		ret = tc_setup_cb_egdev_call(dev, type, type_data, err_stop);
  		if (ret < 0)
  			return ret;
  		ok_count += ret;
  	}
  #endif
  	return ok_count;
  }
  
  int tc_setup_cb_call(struct tcf_block *block, struct tcf_exts *exts,
  		     enum tc_setup_type type, void *type_data, bool err_stop)
  {
  	int ok_count;
  	int ret;
  
  	ret = tcf_block_cb_call(block, type, type_data, err_stop);
  	if (ret < 0)
  		return ret;
  	ok_count = ret;
  
  	if (!exts || ok_count)
  		return ok_count;
  	ret = tc_exts_setup_cb_egdev_call(exts, type, type_data, err_stop);
  	if (ret < 0)
  		return ret;
  	ok_count += ret;
  
  	return ok_count;
  }
  EXPORT_SYMBOL(tc_setup_cb_call);
  
  static __net_init int tcf_net_init(struct net *net)
  {
  	struct tcf_net *tn = net_generic(net, tcf_net_id);
  
  	idr_init(&tn->idr);
  	return 0;
  }
  
  static void __net_exit tcf_net_exit(struct net *net)
  {
  	struct tcf_net *tn = net_generic(net, tcf_net_id);
  
  	idr_destroy(&tn->idr);
  }
  
  static struct pernet_operations tcf_net_ops = {
  	.init = tcf_net_init,
  	.exit = tcf_net_exit,
  	.id   = &tcf_net_id,
  	.size = sizeof(struct tcf_net),
  };
  
  static int __init tc_filter_init(void)
  {
  	int err;
  
  	tc_filter_wq = alloc_ordered_workqueue("tc_filter_workqueue", 0);
  	if (!tc_filter_wq)
  		return -ENOMEM;
  
  	err = register_pernet_subsys(&tcf_net_ops);
  	if (err)
  		goto err_register_pernet_subsys;
  
  	rtnl_register(PF_UNSPEC, RTM_NEWTFILTER, tc_new_tfilter, NULL, 0);
  	rtnl_register(PF_UNSPEC, RTM_DELTFILTER, tc_del_tfilter, NULL, 0);
  	rtnl_register(PF_UNSPEC, RTM_GETTFILTER, tc_get_tfilter,
  		      tc_dump_tfilter, 0);
  
  	return 0;
  
  err_register_pernet_subsys:
  	destroy_workqueue(tc_filter_wq);
  	return err;
  }
  
  subsys_initcall(tc_filter_init);
  