path: root/net/sched/act_api.c

/*
 * net/sched/act_api.c	Packet action 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.
 *
 * Author:	Jamal Hadi Salim
 *
 *
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/rhashtable.h>
#include <linux/list.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <net/sch_generic.h>
#include <net/pkt_cls.h>
#include <net/act_api.h>
#include <net/netlink.h>

static int tcf_action_goto_chain_init(struct tc_action *a, struct tcf_proto *tp)
{
	u32 chain_index = a->tcfa_action & TC_ACT_EXT_VAL_MASK;

	if (!tp)
		return -EINVAL;
	a->goto_chain = tcf_chain_get(tp->chain->block, chain_index, true);
	if (!a->goto_chain)
		return -ENOMEM;
	return 0;
}

static void tcf_action_goto_chain_fini(struct tc_action *a)
{
	tcf_chain_put(a->goto_chain);
}

static void tcf_action_goto_chain_exec(const struct tc_action *a,
				       struct tcf_result *res)
{
	const struct tcf_chain *chain = a->goto_chain;

	res->goto_tp = rcu_dereference_bh(chain->filter_chain);
}

static void tcf_free_cookie_rcu(struct rcu_head *p)
{
	struct tc_cookie *cookie = container_of(p, struct tc_cookie, rcu);

	kfree(cookie->data);
	kfree(cookie);
}

static void tcf_set_action_cookie(struct tc_cookie __rcu **old_cookie,
				  struct tc_cookie *new_cookie)
{
	struct tc_cookie *old;

	old = xchg(old_cookie, new_cookie);
	if (old)
		call_rcu(&old->rcu, tcf_free_cookie_rcu);
}

/* XXX: For standalone actions, we don't need a RCU grace period either, because
 * actions are always connected to filters and filters are already destroyed in
 * RCU callbacks, so after a RCU grace period actions are already disconnected
 * from filters. Readers later can not find us.
 */
static void free_tcf(struct tc_action *p)
{
	free_percpu(p->cpu_bstats);
	free_percpu(p->cpu_qstats);

	tcf_set_action_cookie(&p->act_cookie, NULL);
	if (p->goto_chain)
		tcf_action_goto_chain_fini(p);

	kfree(p);
}

static void tcf_idr_remove(struct tcf_idrinfo *idrinfo, struct tc_action *p)
{
	spin_lock(&idrinfo->lock);
	idr_remove(&idrinfo->action_idr, p->tcfa_index);
	spin_unlock(&idrinfo->lock);
	gen_kill_estimator(&p->tcfa_rate_est);
	free_tcf(p);
}

int __tcf_idr_release(struct tc_action *p, bool bind, bool strict)
{
	int ret = 0;

	ASSERT_RTNL();

	/* Release with strict==1 and bind==0 is only called through act API
	 * interface (classifiers always bind). Only case when action with
	 * positive reference count and zero bind count can exist is when it was
	 * also created with act API (unbinding last classifier will destroy the
	 * action if it was created by classifier). So only case when bind count
	 * can be changed after initial check is when unbound action is
	 * destroyed by act API while classifier binds to action with same id
	 * concurrently. This result either creation of new action(same behavior
	 * as before), or reusing existing action if concurrent process
	 * increments reference count before action is deleted. Both scenarios
	 * are acceptable.
	 */
	if (p) {
		if (bind)
			atomic_dec(&p->tcfa_bindcnt);
		else if (strict && atomic_read(&p->tcfa_bindcnt) > 0)
			return -EPERM;

		if (atomic_read(&p->tcfa_bindcnt) <= 0 &&
		    refcount_dec_and_test(&p->tcfa_refcnt)) {
			if (p->ops->cleanup)
				p->ops->cleanup(p);
			tcf_idr_remove(p->idrinfo, p);
			ret = ACT_P_DELETED;
		}
	}

	return ret;
}
EXPORT_SYMBOL(__tcf_idr_release);

static size_t tcf_action_shared_attrs_size(const struct tc_action *act)
{
	u32 cookie_len = 0;

	if (act->act_cookie)
		cookie_len = nla_total_size(act->act_cookie->len);

	return  nla_total_size(0) /* action number nested */
		+ nla_total_size(IFNAMSIZ) /* TCA_ACT_KIND