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 <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_by_act(tp->chain->block, chain_index);
	if (!a->goto_chain)
		return -ENOMEM;
	return 0;
}

static void tcf_action_goto_chain_fini(struct tc_action *a)
{
	tcf_chain_put_by_act(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((__force struct tc_cookie **)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_bstats_hw);
	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_action_cleanup(struct tc_action *p)
{
	if (p->ops->cleanup)
		p->ops->cleanup(p);

	gen_kill_estimator(&p->tcfa_rate_est);
	free_tcf(p);
}

static int __tcf_action_put(struct tc_action *p, bool bind)
{
	struct tcf_idrinfo *idrinfo = p->idrinfo;

	if (refcount_dec_and_mutex_lock(&p->tcfa_refcnt, &idrinfo->lock)) {
		if (bind)
			atomic_dec(&p->tcfa_bindcnt);
		idr_remove(&idrinfo->action_idr, p->tcfa_index);
		mutex_unlock(&idrinfo->lock);

		tcf_action_cleanup(p);
		return 1;
	}

	if (bind)
		atomic_dec(&p->tcfa_bindcnt);

	return 0;
}

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

	/* 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 && strict && atomic_read(&p->tcfa_bindcnt) > 0)
			return -EPERM;

		if (__tcf_action_put(p, bind))
			ret = ACT_P_DELETED;
	}

	return ret;
}
EXPORT_SYMBOL(__tcf_idr_release);

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

	rcu_read_lock();
	act_cookie = rcu_dereference(act->act_cookie);

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

	return  nla_total_size(0) /* action number nested */
		+ nla_total_size(IFNAMSIZ) /* TCA_ACT_KIND */
		+ cookie_len /* TCA_ACT_COOKIE */
		+ nla_total_size(0) /* TCA_ACT_STATS nested */
		/* TCA_STATS_BASIC */
		+ nla_total_size_64bit(sizeof(struct gnet_stats_basic))
		/* TCA_STATS_QUEUE */
		+ nla_total_size_64bit(sizeof(struct gnet_stats_queue))
		+ nla_total_size(0) /* TCA_OPTIONS nested */
		+ nla_total_size(sizeof(struct tcf_t)); /* TCA_GACT_TM */
}

static size_t tcf_action_full_attrs_size(size_t sz)
{
	return NLMSG_HDRLEN                     /* struct nlmsghdr */
		+ sizeof(struct tcamsg)
		+ nla_total_size(0)             /* TCA_ACT_TAB nested */
		+ sz;
}

static size_t tcf_action_fill_size(const struct tc_action *act)
{
	size_t sz = tcf_action_shared_attrs_size(act);

	if (act->ops->get_fill_size)
		return act->ops->get_fill_size(act) + sz;
	return sz;
}

static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
			   struct netlink_callback *cb)
{
	int err = 0, index = -1, s_i = 0, n_i = 0;
	u32 act_flags = cb->args[2];
	unsigned long jiffy_since = cb->args[3];
	struct nlattr *nest;
	struct idr *idr = &idrinfo->action_idr;
	struct tc_action *p;
	unsigned long id = 1;

	mutex_lock(&idrinfo->lock);

	s_i = cb->args[0];

	idr_for_each_entry_ul(idr, p, id) {
		index++;
		if (index < s_i)
			continue;

		if (jiffy_since &&
		    time_after(jiffy_since,
			       (unsigned long)p->tcfa_tm.lastuse))
			continue;

		nest = nla_nest_start(skb, n_i);
		if (!nest) {
			index--;
			goto nla_put_failure;
		}
		err = tcf_action_dump_1(skb, p, 0, 0);
		if (err < 0) {
			index--;
			nlmsg_trim(skb, nest);
			goto done;
		}
		nla_nest_end(skb, nest);
		n_i++;
		if (!(act_flags & TCA_FLAG_LARGE_DUMP_ON) &&
		    n_i >= TCA_ACT_MAX_PRIO)
			goto done;
	}
done:
	if (index >= 0)
		cb->args[0] = index + 1;

	mutex_unlock(&idrinfo->lock);
	if (n_i) {
		if (act_flags & TCA_FLAG_LARGE_DUMP_ON)
			cb->args[1] = n_i;
	}
	return n_i;

nla_put_failure:
	nla_nest_cancel(skb, nest);
	goto done;
}

static int tcf_idr_release_unsafe(struct tc_action *p)
{
	if (atomic_read(&p->tcfa_bindcnt) > 0)
		return -EPERM;

	if (refcount_dec_and_test(&p->tcfa_refcnt)) {
		idr_remove(&p->idrinfo->action_idr, p->tcfa_index);
		tcf_action_cleanup(p);
		return ACT_P_DELETED;
	}

	return 0;
}

static int tcf_del_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
			  const struct tc_action_ops *ops)
{
	struct nlattr *nest;
	int n_i = 0;
	int ret = -EINVAL;
	struct idr *idr = &idrinfo->action_idr;
	struct tc_action *p;
	unsigned long id = 1;

	nest = nla_nest_start(skb, 0);
	if (nest == NULL)
		goto nla_put_failure;
	if (nla_put_string(skb, TCA_KIND, ops->kind))
		goto nla_put_failure;

	mutex_lock(&idrinfo->lock);
	idr_for_each_entry_ul(idr, p, id) {
		ret = tcf_idr_release_unsafe(p);
		if (ret == ACT_P_DELETED) {
			module_put(ops->owner);
			n_i++;
		} else if (ret < 0) {
			mutex_unlock(&idrinfo->lock);
			goto nla_put_failure;
		}
	}
	mutex_unlock(&idrinfo->lock);

	if (nla_put_u32(skb, TCA_FCNT, n_i))
		goto nla_put_failure;
	nla_nest_end(skb, nest);

	return n_i;
nla_put_failure:
	nla_nest_cancel(skb, nest);
	return ret;
}

int tcf_generic_walker(struct tc_action_net *tn, struct sk_buff *skb,
		       struct netlink_callback *cb, int type,
		       const struct tc_action_ops *ops,
		       struct netlink_ext_ack *extack)
{
	struct tcf_idrinfo *idrinfo = tn->idrinfo;

	if (type