/*
 * 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/act_api.h>
#include <net/netlink.h>

static void free_tcf(struct rcu_head *head)
{
        struct tc_action *p = container_of(head, struct tc_action, tcfa_rcu);

        free_percpu(p->cpu_bstats);
        free_percpu(p->cpu_qstats);
        kfree(p);
}

static void tcf_hash_destroy(struct tcf_hashinfo *hinfo, struct tc_action *p)
{
        spin_lock_bh(&hinfo->lock);
        hlist_del(&p->tcfa_head);
        spin_unlock_bh(&hinfo->lock);
        gen_kill_estimator(&p->tcfa_bstats,
                           &p->tcfa_rate_est);
        /*
         * gen_estimator est_timer() might access p->tcfa_lock
         * or bstats, wait a RCU grace period before freeing p
         */
        call_rcu(&p->tcfa_rcu, free_tcf);
}

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

        if (p) {
                if (bind)
                        p->tcfa_bindcnt--;
                else if (strict && p->tcfa_bindcnt > 0)
                        return -EPERM;

                p->tcfa_refcnt--;
                if (p->tcfa_bindcnt <= 0 && p->tcfa_refcnt <= 0) {
                        if (p->ops->cleanup)
                                p->ops->cleanup(p, bind);
                        tcf_hash_destroy(p->hinfo, p);
                        ret = ACT_P_DELETED;
                }
        }

        return ret;
}
EXPORT_SYMBOL(__tcf_hash_release);

static int tcf_dump_walker(struct tcf_hashinfo *hinfo, struct sk_buff *skb,
                           struct netlink_callback *cb)
{
        int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;
        struct nlattr *nest;

        spin_lock_bh(&hinfo->lock);

        s_i = cb->args[0];

        for (i = 0; i < (hinfo->hmask + 1); i++) {
                struct hlist_head *head;
                struct tc_action *p;

                head = &hinfo->htab[tcf_hash(i, hinfo->hmask)];

                hlist_for_each_entry_rcu(p, head, tcfa_head) {
                        index++;
                        if (index < s_i)
                                continue;

                        nest = nla_nest_start(skb, n_i);
                        if (nest == NULL)
                                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 (n_i >= TCA_ACT_MAX_PRIO)
                                goto done;
                }
        }
done:
        spin_unlock_bh(&hinfo->lock);
        if (n_i)
                cb->args[0] += n_i;
        return n_i;

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

static int tcf_del_walker(struct tcf_hashinfo *hinfo, struct sk_buff *skb,
                          const struct tc_action_ops *ops)
{
        struct nlattr *nest;
        int i = 0, n_i = 0;
        int ret = -EINVAL;

        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;
        for (i = 0; i < (hinfo->hmask + 1); i++) {
                struct hlist_head *head;
                struct hlist_node *n;
                struct tc_action *p;

                head = &hinfo->htab[tcf_hash(i, hinfo->hmask)];
                hlist_for_each_entry_safe(p, n, head, tcfa_head) {
                        ret = __tcf_hash_release(p, false, true);
                        if (ret == ACT_P_DELETED) {
                                module_put(p->ops->owner);
                                n_i++;
                        } else if (ret < 0)
                                goto nla_put_failure;
                }
        }
        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 tcf_hashinfo *hinfo = tn->hinfo;

        if (type == RTM_DELACTION) {
                return tcf_del_walker(hinfo, skb, ops);
        } else if (type == RTM_GETACTION) {
                return tcf_dump_walker(hinfo, skb, cb);
        } else {
                WARN(1, "tcf_generic_walker: unknown action %d\n", type);
                return -EINVAL;
        }
}
EXPORT_SYMBOL(tcf_generic_walker);

static struct tc_action *tcf_hash_lookup(u32 index, struct tcf_hashinfo *hinfo)
{
        struct tc_action *p = NULL;
        struct hlist_head *head;

        spin_lock_bh(&hinfo->lock);
        head = &hinfo->htab[tcf_hash(index, hinfo->hmask)];
        hlist_for_each_entry_rcu(p, head, tcfa_head)
                if (p->tcfa_index == index)
                        break;
        spin_unlock_bh(&hinfo->lock);

        return p;
}

u32 tcf_hash_new_index(struct tc_action_net *tn)
{
        struct tcf_hashinfo *hinfo = tn->hinfo;
        u32 val = hinfo->index;

        do {
                if (++val == 0)
                        val = 1;
        } while (tcf_hash_lookup(val, hinfo));

        hinfo->index = val;
        return val;
}
EXPORT_SYMBOL(tcf_hash_new_index);

int tcf_hash_search(struct tc_action_net *tn, struct tc_action **a, u32 index)
{
        struct tcf_hashinfo *hinfo = tn->hinfo;
        struct tc_action *p = tcf_hash_lookup(index, hinfo);

        if (p) {
                *a = p;
                return 1;
        }
        return 0;
}
EXPORT_SYMBOL(tcf_hash_search);

bool tcf_hash_check(struct tc_action_net *tn, u32 index, struct tc_action **a,
                    int bind)
{
        struct tcf_hashinfo *hinfo = tn->hinfo;
        struct tc_action *p = NULL;

        if (index && (p = tcf_hash_lookup(index, hinfo)) != NULL) {
                if (bind)
                        p->tcfa_bindcnt++;
                p->tcfa_refcnt++;
                *a = p;
                return true;
        }
        return false;
}
EXPORT_SYMBOL(tcf_hash_check);

void tcf_hash_cleanup(struct tc_action *a, struct nlattr *est)
{
        if (est)
                gen_kill_estimator(&a->tcfa_bstats,
                                   &a->tcfa_rate_est);
        call_rcu(&a->tcfa_rcu, free_tcf);
}
EXPORT_SYMBOL(tcf_hash_cleanup);

int tcf_hash_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
                    struct tc_action **a, const struct tc_action_ops *ops,
                    int bind, bool cpustats)
{
        struct tc_action *p = kzalloc(ops->size, GFP_KERNEL);
        struct tcf_hashinfo *hinfo = tn->hinfo;
        int err = -ENOMEM;

        if (unlikely(!p))
                return -ENOMEM;
        p->tcfa_refcnt = 1;
        if (bind)
                p->tcfa_bindcnt = 1;

        if (cpustats) {
                p->cpu_bstats = netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
                if (!p->cpu_bstats) {
err1:
                        kfree(p);
                        return err;
                }
                p->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
                if (!p->cpu_qstats) {
err2:
                        free_percpu(p->cpu_bstats);
                        goto err1;
                }
        }
        spin_lock_init(&p->tcfa_lock);
        INIT_HLIST_NODE(&p->tcfa_head);
        p->tcfa_index = index ? index : tcf_hash_new_index(tn);
        p->tcfa_tm.install = jiffies;
        p->tcfa_tm.lastuse = jiffies;
        p->tcfa_tm.firstuse = 0;
        if (est) {
                err = gen_new_estimator(&p->tcfa_bstats, p->cpu_bstats,
                                        &p->tcfa_rate_est,
                                        &p->tcfa_lock, NULL, est);
                if (err) {
                        free_percpu(p->cpu_qstats);
                        goto err2;
                }
        }

        p->hinfo = hinfo;
        p->ops = ops;
        INIT_LIST_HEAD(&p->list);
        *a = p;
        return 0;
}
EXPORT_SYMBOL(tcf_hash_create);

void tcf_hash_insert(struct tc_action_net *tn, struct tc_action *a)
{
        struct tcf_hashinfo *hinfo = tn->hinfo;
        unsigned int h = tcf_hash(a->tcfa_index, hinfo->hmask);

        spin_lock_bh(&hinfo->lock);
        hlist_add_head(&a->tcfa_head, &hinfo->htab[h]);
        spin_unlock_bh(&hinfo->lock);
}
EXPORT_SYMBOL(tcf_hash_insert);

void tcf_hashinfo_destroy(const struct tc_action_ops *ops,
                          struct tcf_hashinfo *hinfo)
{
        int i;

        for (i = 0; i < hinfo->hmask + 1; i++) {
                struct tc_action *p;
                struct hlist_node *n;

                hlist_for_each_entry_safe(p, n, &hinfo->htab[i], tcfa_head) {
                        int ret;

                        ret = __tcf_hash_release(p, false, true);
                        if (ret == ACT_P_DELETED)
                                module_put(ops->owner);
                        else if (ret < 0)
                                return;
                }
        }
        kfree(hinfo->htab);
}
EXPORT_SYMBOL(tcf_hashinfo_destroy);

static LIST_HEAD(act_base);
static DEFINE_RWLOCK(act_mod_lock);

int tcf_register_action(struct tc_action_ops *act,
                        struct pernet_operations *ops)
{
        struct tc_action_ops *a;
        int ret;

        if (!act->act || !act->dump || !act->init || !act->walk || !act->lookup)
                return -EINVAL;

        write_lock(&act_mod_lock);
        list_for_each_entry(a, &act_base, head) {
                if (act->type == a->type || (strcmp(act->kind, a->kind) == 0)) {
                        write_unlock(&act_mod_lock);
                        return -EEXIST;
                }
        }
        list_add_tail(&act->head, &act_base);
        write_unlock(&act_mod_lock);

        ret = register_pernet_subsys(ops);
        if (ret) {
                tcf_unregister_action(act, ops);
                return ret;
        }

        return 0;
}
EXPORT_SYMBOL(tcf_register_action);

int tcf_unregister_action(struct tc_action_ops *act,
                          struct pernet_operations *ops)
{
        struct tc_action_ops *a;
        int err = -ENOENT;

        unregister_pernet_subsys(ops);

        write_lock(&act_mod_lock);
        list_for_each_entry(a, &act_base, head) {
                if (a == act) {
                        list_del(&act->head);
                        err = 0;
                        break;
                }
        }
        write_unlock(&act_mod_lock);
        return err;
}
EXPORT_SYMBOL(tcf_unregister_action);

/* lookup by name */
static struct tc_action_ops *tc_lookup_action_n(char *kind)
{
        struct tc_action_ops *a, *res = NULL;

        if (kind) {
                read_lock(&act_mod_lock);
                list_for_each_entry(a, &act_base, head) {
                        if (strcmp(kind, a->kind) == 0) {
                                if (try_module_get(a->owner))
                                        res = a;
                                break;
                        }
                }
                read_unlock(&act_mod_lock);
        }
        return res;
}

/* lookup by nlattr */
static struct tc_action_ops *tc_lookup_action(struct nlattr *kind)
{
        struct tc_action_ops *a, *res = NULL;

        if (kind) {
                read_lock(&act_mod_lock);
                list_for_each_entry(a, &act_base, head) {
                        if (nla_strcmp(kind, a->kind) == 0) {
                                if (try_module_get(a->owner))
                                        res = a;
                                break;
                        }
                }
                read_unlock(&act_mod_lock);
        }
        return res;
}

int tcf_action_exec(struct sk_buff *skb, struct tc_action **actions,
                    int nr_actions, struct tcf_result *res)
{
        int ret = -1, i;

        if (skb->tc_verd & TC_NCLS) {
                skb->tc_verd = CLR_TC_NCLS(skb->tc_verd);
                ret = TC_ACT_OK;
                goto exec_done;
        }
        for (i = 0; i < nr_actions; i++) {
                const struct tc_action *a = actions[i];

repeat:
                ret = a->ops->act(skb, a, res);
                if (ret == TC_ACT_REPEAT)
                        goto repeat;    /* we need a ttl - JHS */
                if (ret != TC_ACT_PIPE)
                        goto exec_done;
        }
exec_done:
        return ret;
}
EXPORT_SYMBOL(tcf_action_exec);

int tcf_action_destroy(struct list_head *actions, int bind)
{
        struct tc_action *a, *tmp;
        int ret = 0;

        list_for_each_entry_safe(a, tmp, actions, list) {
                ret = __tcf_hash_release(a, bind, true);
                if (ret == ACT_P_DELETED)
                        module_put(a->ops->owner);
                else if (ret < 0)
                        return ret;
        }
        return ret;
}

int
tcf_action_dump_old(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
{
        return a->ops->dump(skb, a, bind, ref);
}

int
tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
{
        int err = -EINVAL;
        unsigned char *b = skb_tail_pointer(skb);
        struct nlattr *nest;

        if (nla_put_string(skb, TCA_KIND, a->ops->kind))
                goto nla_put_failure;
        if (tcf_action_copy_stats(skb, a, 0))
                goto nla_put_failure;
        nest = nla_nest_start(skb, TCA_OPTIONS);
        if (nest == NULL)
                goto nla_put_failure;
        err = tcf_action_dump_old(skb, a, bind, ref);
        if (err > 0) {
                nla_nest_end(skb, nest);
                return err;
        }

nla_put_failure:
        nlmsg_trim(skb, b);
        return -1;
}
EXPORT_SYMBOL(tcf_action_dump_1);

int tcf_action_dump(struct sk_buff *skb, struct list_head *actions,
                    int bind, int ref)
{
        struct tc_action *a;
        int err = -EINVAL;
        struct nlattr *nest;

        list_for_each_entry(a, actions, list) {
                nest = nla_nest_start(skb, a->order);
                if (nest == NULL)
                        goto nla_put_failure;
                err = tcf_action_dump_1(skb, a, bind, ref);
                if (err < 0)
                        goto errout;
                nla_nest_end(skb, nest);
        }

        return 0;

nla_put_failure:
        err = -EINVAL;
errout:
        nla_nest_cancel(skb, nest);
        return err;
}

struct tc_action *tcf_action_init_1(struct net *net, struct nlattr *nla,
                                    struct nlattr *est, char *name, int ovr,
                                    int bind)
{
        struct tc_action *a;
        struct tc_action_ops *a_o;
        char act_name[IFNAMSIZ];
        struct nlattr *tb[TCA_ACT_MAX + 1];
        struct nlattr *kind;
        int err;

        if (name == NULL) {
                err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL);
                if (err < 0)
                        goto err_out;
                err = -EINVAL;
                kind = tb[TCA_ACT_KIND];
                if (kind == NULL)
                        goto err_out;
                if (nla_strlcpy(act_name, kind, IFNAMSIZ) >= IFNAMSIZ)
                        goto err_out;
        } else {
                err = -EINVAL;
                if (strlcpy(act_name, name, IFNAMSIZ) >= IFNAMSIZ)
                        goto err_out;
        }

        a_o = tc_lookup_action_n(act_name);
        if (a_o == NULL) {
#ifdef CONFIG_MODULES
                rtnl_unlock();
                request_module("act_%s", act_name);
                rtnl_lock();

                a_o = tc_lookup_action_n(act_name);

                /* We dropped the RTNL semaphore in order to
                 * perform the module load.  So, even if we
                 * succeeded in loading the module we have to
                 * tell the caller to replay the request.  We
                 * indicate this using -EAGAIN.
                 */
                if (a_o != NULL) {
                        err = -EAGAIN;
                        goto err_mod;
                }
#endif
                err = -ENOENT;
                goto err_out;
        }

        /* backward compatibility for policer */
        if (name == NULL)
                err = a_o->init(net, tb[TCA_ACT_OPTIONS], est, &a, ovr, bind);
        else
                err = a_o->init(net, nla, est, &a, ovr, bind);
        if (err < 0)
                goto err_mod;

        /* module count goes up only when brand new policy is created
         * if it exists and is only bound to in a_o->init() then
         * ACT_P_CREATED is not returned (a zero is).
         */
        if (err != ACT_P_CREATED)
                module_put(a_o->owner);

        return a;

err_mod:
        module_put(a_o->owner);
err_out:
        return ERR_PTR(err);
}

int tcf_action_init(struct net *net, struct nlattr *nla,
                                  struct nlattr *est, char *name, int ovr,
                                  int bind, struct list_head *actions)
{
        struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
        struct tc_action *act;
        int err;
        int i;

        err = nla_parse_nested(tb, TCA_ACT_MAX_PRIO, nla, NULL);
        if (err < 0)
                return err;

        for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
                act = tcf_action_init_1(net, tb[i], est, name, ovr, bind);
                if (IS_ERR(act)) {
                        err = PTR_ERR(act);
                        goto err;
                }
                act->order = i;
                list_add_tail(&act->list, actions);
        }
        return 0;

err:
        tcf_action_destroy(actions, bind);
        return err;
}

int tcf_action_copy_stats(struct sk_buff *skb, struct tc_action *p,
                          int compat_mode)
{
        int err = 0;
        struct gnet_dump d;

        if (p == NULL)
                goto errout;

        /* compat_mode being true specifies a call that is supposed
         * to add additional backward compatibility statistic TLVs.
         */
        if (compat_mode) {
                if (p->type == TCA_OLD_COMPAT)
                        err = gnet_stats_start_copy_compat(skb, 0,
                                                           TCA_STATS,
                                                           TCA_XSTATS,
                                                           &p->tcfa_lock, &d,
                                                           TCA_PAD);
                else
                        return 0;
        } else
                err = gnet_stats_start_copy(skb, TCA_ACT_STATS,
                                            &p->tcfa_lock, &d, TCA_ACT_PAD);

        if (err < 0)
                goto errout;

        if (gnet_stats_copy_basic(NULL, &d, p->cpu_bstats, &p->tcfa_bstats) < 0 ||
            gnet_stats_copy_rate_est(&d, &p->tcfa_bstats,
                                     &p->tcfa_rate_est) < 0 ||
            gnet_stats_copy_queue(&d, p->cpu_qstats,
                                  &p->tcfa_qstats,
                                  p->tcfa_qstats.qlen) < 0)
                goto errout;

        if (gnet_stats_finish_copy(&d) < 0)
                goto errout;

        return 0;

errout:
        return -1;
}

static int tca_get_fill(struct sk_buff *skb, struct list_head *actions,
                        u32 portid, u32 seq, u16 flags, int event, int bind,
                        int ref)
{
        struct tcamsg *t;
        struct nlmsghdr *nlh;
        unsigned char *b = skb_tail_pointer(skb);
        struct nlattr *nest;

        nlh = nlmsg_put(skb, portid, seq, event, sizeof(*t), flags);
        if (!nlh)
                goto out_nlmsg_trim;
        t = nlmsg_data(nlh);
        t->tca_family = AF_UNSPEC;
        t->tca__pad1 = 0;
        t->tca__pad2 = 0;

        nest = nla_nest_start(skb, TCA_ACT_TAB);
        if (nest == NULL)
                goto out_nlmsg_trim;

        if (tcf_action_dump(skb, actions, bind, ref) < 0)
                goto out_nlmsg_trim;

        nla_nest_end(skb, nest);

        nlh->nlmsg_len = skb_tail_pointer(skb) - b;
        return skb->len;

out_nlmsg_trim:
        nlmsg_trim(skb, b);
        return -1;
}

static int
act_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,
               struct list_head *actions, int event)
{
        struct sk_buff *skb;

        skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
        if (!skb)
                return -ENOBUFS;
        if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, 0, event,
                         0, 0) <= 0) {
                kfree_skb(skb);
                return -EINVAL;
        }

        return rtnl_unicast(skb, net, portid);
}

static struct tc_action *tcf_action_get_1(struct net *net, struct nlattr *nla,
                                          struct nlmsghdr *n, u32 portid)
{
        struct nlattr *tb[TCA_ACT_MAX + 1];
        const struct tc_action_ops *ops;
        struct tc_action *a;
        int index;
        int err;

        err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL);
        if (err < 0)
                goto err_out;

        err = -EINVAL;
        if (tb[TCA_ACT_INDEX] == NULL ||
            nla_len(tb[TCA_ACT_INDEX]) < sizeof(index))
                goto err_out;
        index = nla_get_u32(tb[TCA_ACT_INDEX]);

        err = -EINVAL;
        ops = tc_lookup_action(tb[TCA_ACT_KIND]);
        if (!ops) /* could happen in batch of actions */
                goto err_out;
        err = -ENOENT;
        if (ops->lookup(net, &a, index) == 0)
                goto err_mod;

        module_put(ops->owner);
        return a;

err_mod:
        module_put(ops->owner);
err_out:
        return ERR_PTR(err);
}

static int tca_action_flush(struct net *net, struct nlattr *nla,
                            struct nlmsghdr *n, u32 portid)
{
        struct sk_buff *skb;
        unsigned char *b;
        struct nlmsghdr *nlh;
        struct tcamsg *t;
        struct netlink_callback dcb;
        struct nlattr *nest;
        struct nlattr *tb[TCA_ACT_MAX + 1];
        const struct tc_action_ops *ops;
        struct nlattr *kind;
        int err = -ENOMEM;

        skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
        if (!skb) {
                pr_debug("tca_action_flush: failed skb alloc\n");
                return err;
        }

        b = skb_tail_pointer(skb);

        err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL);
        if (err < 0)
                goto err_out;

        err = -EINVAL;
        kind = tb[TCA_ACT_KIND];
        ops = tc_lookup_action(kind);
        if (!ops) /*some idjot trying to flush unknown action */
                goto err_out;

        nlh = nlmsg_put(skb, portid, n->nlmsg_seq, RTM_DELACTION,
                        sizeof(*t), 0);
        if (!nlh)
                goto out_module_put;
        t = nlmsg_data(nlh);
        t->tca_family = AF_UNSPEC;
        t->tca__pad1 = 0;
        t->tca__pad2 = 0;

        nest = nla_nest_start(skb, TCA_ACT_TAB);
        if (nest == NULL)
                goto out_module_put;

        err = ops->walk(net, skb, &dcb, RTM_DELACTION, ops);
        if (err < 0)
                goto out_module_put;
        if (err == 0)
                goto noflush_out;

        nla_nest_end(skb, nest);

        nlh->nlmsg_len = skb_tail_pointer(skb) - b;
        nlh->nlmsg_flags |= NLM_F_ROOT;
        module_put(ops->owner);
        err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
                             n->nlmsg_flags & NLM_F_ECHO);
        if (err > 0)
                return 0;

        return err;

out_module_put:
        module_put(ops->owner);
err_out:
noflush_out:
        kfree_skb(skb);
        return err;
}

static int
tcf_del_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
               u32 portid)
{
        int ret;
        struct sk_buff *skb;

        skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
        if (!skb)
                return -ENOBUFS;

        if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, 0, RTM_DELACTION,
                         0, 1) <= 0) {
                kfree_skb(skb);
                return -EINVAL;
        }

        /* now do the delete */
        ret = tcf_action_destroy(actions, 0);
        if (ret < 0) {
                kfree_skb(skb);
                return ret;
        }

        ret = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
                             n->nlmsg_flags & NLM_F_ECHO);
        if (ret > 0)
                return 0;
        return ret;
}

static int
tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
              u32 portid, int event)
{
        int i, ret;
        struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
        struct tc_action *act;
        LIST_HEAD(actions);

        ret = nla_parse_nested(tb, TCA_ACT_MAX_PRIO, nla, NULL);
        if (ret < 0)
                return ret;

        if (event == RTM_DELACTION && n->nlmsg_flags & NLM_F_ROOT) {
                if (tb[1] != NULL)
                        return tca_action_flush(net, tb[1], n, portid);
                else
                        return -EINVAL;
        }

        for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
                act = tcf_action_get_1(net, tb[i], n, portid);
                if (IS_ERR(act)) {
                        ret = PTR_ERR(act);
                        goto err;
                }
                act->order = i;
                list_add_tail(&act->list, &actions);
        }

        if (event == RTM_GETACTION)
                ret = act_get_notify(net, portid, n, &actions, event);
        else { /* delete */
                ret = tcf_del_notify(net, n, &actions, portid);
                if (ret)
                        goto err;
                return ret;
        }
err:
        tcf_action_destroy(&actions, 0);
        return ret;
}

static int
tcf_add_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
               u32 portid)
{
        struct sk_buff *skb;
        int err = 0;

        skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
        if (!skb)
                return -ENOBUFS;

        if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, n->nlmsg_flags,
                         RTM_NEWACTION, 0, 0) <= 0) {
                kfree_skb(skb);
                return -EINVAL;
        }

        err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
                             n->nlmsg_flags & NLM_F_ECHO);
        if (err > 0)
                err = 0;
        return err;
}

static int
tcf_action_add(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
               u32 portid, int ovr)
{
        int ret = 0;
        LIST_HEAD(actions);

        ret = tcf_action_init(net, nla, NULL, NULL, ovr, 0, &actions);
        if (ret)
                return ret;

        return tcf_add_notify(net, n, &actions, portid);
}

static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n)
{
        struct net *net = sock_net(skb->sk);
        struct nlattr *tca[TCA_ACT_MAX + 1];
        u32 portid = skb ? NETLINK_CB(skb).portid : 0;
        int ret = 0, ovr = 0;

        if ((n->nlmsg_type != RTM_GETACTION) &&
            !netlink_capable(skb, CAP_NET_ADMIN))
                return -EPERM;

        ret = nlmsg_parse(n, sizeof(struct tcamsg), tca, TCA_ACT_MAX, NULL);
        if (ret < 0)
                return ret;

        if (tca[TCA_ACT_TAB] == NULL) {
                pr_notice("tc_ctl_action: received NO action attribs\n");
                return -EINVAL;
        }

        /* n->nlmsg_flags & NLM_F_CREATE */
        switch (n->nlmsg_type) {
        case RTM_NEWACTION:
                /* we are going to assume all other flags
                 * imply create only if it doesn't exist
                 * Note that CREATE | EXCL implies that
                 * but since we want avoid ambiguity (eg when flags
                 * is zero) then just set this
                 */
                if (n->nlmsg_flags & NLM_F_REPLACE)
                        ovr = 1;
replay:
                ret = tcf_action_add(net, tca[TCA_ACT_TAB], n, portid, ovr);
                if (ret == -EAGAIN)
                        goto replay;
                break;
        case RTM_DELACTION:
                ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
                                    portid, RTM_DELACTION);
                break;
        case RTM_GETACTION:
                ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
                                    portid, RTM_GETACTION);
                break;
        default:
                BUG();
        }

        return ret;
}

static struct nlattr *
find_dump_kind(const struct nlmsghdr *n)
{
        struct nlattr *tb1, *tb2[TCA_ACT_MAX + 1];
        struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
        struct nlattr *nla[TCAA_MAX + 1];
        struct nlattr *kind;

        if (nlmsg_parse(n, sizeof(struct tcamsg), nla, TCAA_MAX, NULL) < 0)
                return NULL;

        tb1 = nla[TCA_ACT_TAB];
        if (tb1 == NULL)
                return NULL;

        if (nla_parse(tb, TCA_ACT_MAX_PRIO, nla_data(tb1),
                      NLMSG_ALIGN(nla_len(tb1)), NULL) < 0)
                return NULL;

        if (tb[1] == NULL)
                return NULL;
        if (nla_parse(tb2, TCA_ACT_MAX, nla_data(tb[1]),
                      nla_len(tb[1]), NULL) < 0)
                return NULL;
        kind = tb2[TCA_ACT_KIND];

        return kind;
}

static int
tc_dump_action(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct net *net = sock_net(skb->sk);
        struct nlmsghdr *nlh;
        unsigned char *b = skb_tail_pointer(skb);
        struct nlattr *nest;
        struct tc_action_ops *a_o;
        int ret = 0;
        struct tcamsg *t = (struct tcamsg *) nlmsg_data(cb->nlh);
        struct nlattr *kind = find_dump_kind(cb->nlh);

        if (kind == NULL) {
                pr_info("tc_dump_action: action bad kind\n");
                return 0;
        }

        a_o = tc_lookup_action(kind);
        if (a_o == NULL)
                return 0;

        nlh = nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
                        cb->nlh->nlmsg_type, sizeof(*t), 0);
        if (!nlh)
                goto out_module_put;
        t = nlmsg_data(nlh);
        t->tca_family = AF_UNSPEC;
        t->tca__pad1 = 0;
        t->tca__pad2 = 0;

        nest = nla_nest_start(skb, TCA_ACT_TAB);
        if (nest == NULL)
                goto out_module_put;

        ret = a_o->walk(net, skb, cb, RTM_GETACTION, a_o);
        if (ret < 0)
                goto out_module_put;

        if (ret > 0) {
                nla_nest_end(skb, nest);
                ret = skb->len;
        } else
                nlmsg_trim(skb, b);

        nlh->nlmsg_len = skb_tail_pointer(skb) - b;
        if (NETLINK_CB(cb->skb).portid && ret)
                nlh->nlmsg_flags |= NLM_F_MULTI;
        module_put(a_o->owner);
        return skb->len;

out_module_put:
        module_put(a_o->owner);
        nlmsg_trim(skb, b);
        return skb->len;
}

static int __init tc_action_init(void)
{
        rtnl_register(PF_UNSPEC, RTM_NEWACTION, tc_ctl_action, NULL, NULL);
        rtnl_register(PF_UNSPEC, RTM_DELACTION, tc_ctl_action, NULL, NULL);
        rtnl_register(PF_UNSPEC, RTM_GETACTION, tc_ctl_action, tc_dump_action,
                      NULL);

        return 0;
}

subsys_initcall(tc_action_init);