/*
 * 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>

void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo)
{
        unsigned int h = tcf_hash(p->tcfc_index, hinfo->hmask);
        struct tcf_common **p1p;

        for (p1p = &hinfo->htab[h]; *p1p; p1p = &(*p1p)->tcfc_next) {
                if (*p1p == p) {
                        write_lock_bh(hinfo->lock);
                        *p1p = p->tcfc_next;
                        write_unlock_bh(hinfo->lock);
                        gen_kill_estimator(&p->tcfc_bstats,
                                           &p->tcfc_rate_est);
                        /*
                         * gen_estimator est_timer() might access p->tcfc_lock
                         * or bstats, wait a RCU grace period before freeing p
                         */
                        kfree_rcu(p, tcfc_rcu);
                        return;
                }
        }
        WARN_ON(1);
}
EXPORT_SYMBOL(tcf_hash_destroy);

int tcf_hash_release(struct tcf_common *p, int bind,
                     struct tcf_hashinfo *hinfo)
{
        int ret = 0;

        if (p) {
                if (bind)
                        p->tcfc_bindcnt--;

                p->tcfc_refcnt--;
                if (p->tcfc_bindcnt <= 0 && p->tcfc_refcnt <= 0) {
                        tcf_hash_destroy(p, hinfo);
                        ret = 1;
                }
        }
        return ret;
}
EXPORT_SYMBOL(tcf_hash_release);

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

        read_lock_bh(hinfo->lock);

        s_i = cb->args[0];

        for (i = 0; i < (hinfo->hmask + 1); i++) {
                p = hinfo->htab[tcf_hash(i, hinfo->hmask)];

                for (; p; p = p->tcfc_next) {
                        index++;
                        if (index < s_i)
                                continue;
                        a->priv = p;
                        a->order = n_i;

                        nest = nla_nest_start(skb, a->order);
                        if (nest == NULL)
                                goto nla_put_failure;
                        err = tcf_action_dump_1(skb, a, 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:
        read_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 sk_buff *skb, struct tc_action *a,
                          struct tcf_hashinfo *hinfo)
{
        struct tcf_common *p, *s_p;
        struct nlattr *nest;
        int i = 0, n_i = 0;

        nest = nla_nest_start(skb, a->order);
        if (nest == NULL)
                goto nla_put_failure;
        if (nla_put_string(skb, TCA_KIND, a->ops->kind))
                goto nla_put_failure;
        for (i = 0; i < (hinfo->hmask + 1); i++) {
                p = hinfo->htab[tcf_hash(i, hinfo->hmask)];

                while (p != NULL) {
                        s_p = p->tcfc_next;
                        if (ACT_P_DELETED == tcf_hash_release(p, 0, hinfo))
                                module_put(a->ops->owner);
                        n_i++;
                        p = s_p;
                }
        }
        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 -EINVAL;
}

int tcf_generic_walker(struct sk_buff *skb, struct netlink_callback *cb,
                       int type, struct tc_action *a)
{
        struct tcf_hashinfo *hinfo = a->ops->hinfo;

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

struct tcf_common *tcf_hash_lookup(u32 index, struct tcf_hashinfo *hinfo)
{
        struct tcf_common *p;

        read_lock_bh(hinfo->lock);
        for (p = hinfo->htab[tcf_hash(index, hinfo->hmask)]; p;
             p = p->tcfc_next) {
                if (p->tcfc_index == index)
                        break;
        }
        read_unlock_bh(hinfo->lock);

        return p;
}
EXPORT_SYMBOL(tcf_hash_lookup);

u32 tcf_hash_new_index(u32 *idx_gen, struct tcf_hashinfo *hinfo)
{
        u32 val = *idx_gen;

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

        return (*idx_gen = val);
}
EXPORT_SYMBOL(tcf_hash_new_index);

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

        if (p) {
                a->priv = p;
                return 1;
        }
        return 0;
}
EXPORT_SYMBOL(tcf_hash_search);

struct tcf_common *tcf_hash_check(u32 index, struct tc_action *a, int bind,
                                  struct tcf_hashinfo *hinfo)
{
        struct tcf_common *p = NULL;
        if (index && (p = tcf_hash_lookup(index, hinfo)) != NULL) {
                if (bind)
                        p->tcfc_bindcnt++;
                p->tcfc_refcnt++;
                a->priv = p;
        }
        return p;
}
EXPORT_SYMBOL(tcf_hash_check);

struct tcf_common *tcf_hash_create(u32 index, struct nlattr *est,
                                   struct tc_action *a, int size, int bind,
                                   u32 *idx_gen, struct tcf_hashinfo *hinfo)
{
        struct tcf_common *p = kzalloc(size, GFP_KERNEL);

        if (unlikely(!p))
                return ERR_PTR(-ENOMEM);
        p->tcfc_refcnt = 1;
        if (bind)
                p->tcfc_bindcnt = 1;

        spin_lock_init(&p->tcfc_lock);
        p->tcfc_index = index ? index : tcf_hash_new_index(idx_gen, hinfo);
        p->tcfc_tm.install = jiffies;
        p->tcfc_tm.lastuse = jiffies;
        if (est) {
                int err = gen_new_estimator(&p->tcfc_bstats, &p->tcfc_rate_est,
                                            &p->tcfc_lock, est);
                if (err) {
                        kfree(p);
                        return ERR_PTR(err);
                }
        }

        a->priv = (void *) p;
        return p;
}
EXPORT_SYMBOL(tcf_hash_create);

void tcf_hash_insert(struct tcf_common *p, struct tcf_hashinfo *hinfo)
{
        unsigned int h = tcf_hash(p->tcfc_index, hinfo->hmask);

        write_lock_bh(hinfo->lock);
        p->tcfc_next = hinfo->htab[h];
        hinfo->htab[h] = p;
        write_unlock_bh(hinfo->lock);
}
EXPORT_SYMBOL(tcf_hash_insert);

static struct tc_action_ops *act_base = NULL;
static DEFINE_RWLOCK(act_mod_lock);

int tcf_register_action(struct tc_action_ops *act)
{
        struct tc_action_ops *a, **ap;

        write_lock(&act_mod_lock);
        for (ap = &act_base; (a = *ap) != NULL; ap = &a->next) {
                if (act->type == a->type || (strcmp(act->kind, a->kind) == 0)) {
                        write_unlock(&act_mod_lock);
                        return -EEXIST;
                }
        }
        act->next = NULL;
        *ap = act;
        write_unlock(&act_mod_lock);
        return 0;
}
EXPORT_SYMBOL(tcf_register_action);

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

        write_lock(&act_mod_lock);
        for (ap = &act_base; (a = *ap) != NULL; ap = &a->next)
                if (a == act)
                        break;
        if (a) {
                *ap = a->next;
                a->next = NULL;
                err = 0;
        }
        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 = NULL;

        if (kind) {
                read_lock(&act_mod_lock);
                for (a = act_base; a; a = a->next) {
                        if (strcmp(kind, a->kind) == 0) {
                                if (!try_module_get(a->owner)) {
                                        read_unlock(&act_mod_lock);
                                        return NULL;
                                }
                                break;
                        }
                }
                read_unlock(&act_mod_lock);
        }
        return a;
}

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

        if (kind) {
                read_lock(&act_mod_lock);
                for (a = act_base; a; a = a->next) {
                        if (nla_strcmp(kind, a->kind) == 0) {
                                if (!try_module_get(a->owner)) {
                                        read_unlock(&act_mod_lock);
                                        return NULL;
                                }
                                break;
                        }
                }
                read_unlock(&act_mod_lock);
        }
        return a;
}

#if 0
/* lookup by id */
static struct tc_action_ops *tc_lookup_action_id(u32 type)
{
        struct tc_action_ops *a = NULL;

        if (type) {
                read_lock(&act_mod_lock);
                for (a = act_base; a; a = a->next) {
                        if (a->type == type) {
                                if (!try_module_get(a->owner)) {
                                        read_unlock(&act_mod_lock);
                                        return NULL;
                                }
                                break;
                        }
                }
                read_unlock(&act_mod_lock);
        }
        return a;
}
#endif

int tcf_action_exec(struct sk_buff *skb, const struct tc_action *act,
                    struct tcf_result *res)
{
        const struct tc_action *a;
        int ret = -1;

        if (skb->tc_verd & TC_NCLS) {
                skb->tc_verd = CLR_TC_NCLS(skb->tc_verd);
                ret = TC_ACT_OK;
                goto exec_done;
        }
        while ((a = act) != NULL) {
repeat:
                if (a->ops && a->ops->act) {
                        ret = a->ops->act(skb, a, res);
                        if (TC_MUNGED & skb->tc_verd) {
                                /* copied already, allow trampling */
                                skb->tc_verd = SET_TC_OK2MUNGE(skb->tc_verd);
                                skb->tc_verd = CLR_TC_MUNGED(skb->tc_verd);
                        }
                        if (ret == TC_ACT_REPEAT)
                                goto repeat;    /* we need a ttl - JHS */
                        if (ret != TC_ACT_PIPE)
                                goto exec_done;
                }
                act = a->next;
        }
exec_done:
        return ret;
}
EXPORT_SYMBOL(tcf_action_exec);

void tcf_action_destroy(struct tc_action *act, int bind)
{
        struct tc_action *a;

        for (a = act; a; a = act) {
                if (a->ops && a->ops->cleanup) {
                        if (a->ops->cleanup(a, bind) == ACT_P_DELETED)
                                module_put(a->ops->owner);
                        act = act->next;
                        kfree(a);
                } else {
                        /*FIXME: Remove later - catch insertion bugs*/
                        WARN(1, "tcf_action_destroy: BUG? destroying NULL ops\n");
                        act = act->next;
                        kfree(a);
                }
        }
}

int
tcf_action_dump_old(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
{
        int err = -EINVAL;

        if (a->ops == NULL || a->ops->dump == NULL)
                return err;
        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 (a->ops == NULL || a->ops->dump == NULL)
                return err;

        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 tc_action *act, int bind, int ref)
{
        struct tc_action *a;
        int err = -EINVAL;
        struct nlattr *nest;

        while ((a = act) != NULL) {
                act = a->next;
                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 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;
        }

        err = -ENOMEM;
        a = kzalloc(sizeof(*a), GFP_KERNEL);
        if (a == NULL)
                goto err_mod;

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

        /* 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);
        a->ops = a_o;

        return a;

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

struct tc_action *tcf_action_init(struct nlattr *nla, struct nlattr *est,
                                  char *name, int ovr, int bind)
{
        struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
        struct tc_action *head = NULL, *act, *act_prev = NULL;
        int err;
        int i;

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

        for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
                act = tcf_action_init_1(tb[i], est, name, ovr, bind);
                if (IS_ERR(act))
                        goto err;
                act->order = i;

                if (head == NULL)
                        head = act;
                else
                        act_prev->next = act;
                act_prev = act;
        }
        return head;

err:
        if (head != NULL)
                tcf_action_destroy(head, bind);
        return act;
}

int tcf_action_copy_stats(struct sk_buff *skb, struct tc_action *a,
                          int compat_mode)
{
        int err = 0;
        struct gnet_dump d;
        struct tcf_act_hdr *h = a->priv;

        if (h == NULL)
                goto errout;

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

        if (err < 0)
                goto errout;

        if (a->ops != NULL && a->ops->get_stats != NULL)
                if (a->ops->get_stats(skb, a) < 0)
                        goto errout;

        if (gnet_stats_copy_basic(&d, &h->tcf_bstats) < 0 ||
            gnet_stats_copy_rate_est(&d, &h->tcf_bstats,
                                     &h->tcf_rate_est) < 0 ||
            gnet_stats_copy_queue(&d, &h->tcf_qstats) < 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 tc_action *a, u32 pid, 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_NEW(skb, pid, seq, event, sizeof(*t), flags);

        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 nla_put_failure;

        if (tcf_action_dump(skb, a, bind, ref) < 0)
                goto nla_put_failure;

        nla_nest_end(skb, nest);

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

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

static int
act_get_notify(struct net *net, u32 pid, struct nlmsghdr *n,
               struct tc_action *a, int event)
{
        struct sk_buff *skb;

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

        return rtnl_unicast(skb, net, pid);
}

static struct tc_action *
tcf_action_get_1(struct nlattr *nla, struct nlmsghdr *n, u32 pid)
{
        struct nlattr *tb[TCA_ACT_MAX + 1];
        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 = -ENOMEM;
        a = kzalloc(sizeof(struct tc_action), GFP_KERNEL);
        if (a == NULL)
                goto err_out;

        err = -EINVAL;
        a->ops = tc_lookup_action(tb[TCA_ACT_KIND]);
        if (a->ops == NULL)
                goto err_free;
        if (a->ops->lookup == NULL)
                goto err_mod;
        err = -ENOENT;
        if (a->ops->lookup(a, index) == 0)
                goto err_mod;

        module_put(a->ops->owner);
        return a;

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

static void cleanup_a(struct tc_action *act)
{
        struct tc_action *a;

        for (a = act; a; a = act) {
                act = a->next;
                kfree(a);
        }
}

static struct tc_action *create_a(int i)
{
        struct tc_action *act;

        act = kzalloc(sizeof(*act), GFP_KERNEL);
        if (act == NULL) {
                pr_debug("create_a: failed to alloc!\n");
                return NULL;
        }
        act->order = i;
        return act;
}

static int tca_action_flush(struct net *net, struct nlattr *nla,
                            struct nlmsghdr *n, u32 pid)
{
        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];
        struct nlattr *kind;
        struct tc_action *a = create_a(0);
        int err = -ENOMEM;

        if (a == NULL) {
                pr_debug("tca_action_flush: couldnt create tc_action\n");
                return err;
        }

        skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
        if (!skb) {
                pr_debug("tca_action_flush: failed skb alloc\n");
                kfree(a);
                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];
        a->ops = tc_lookup_action(kind);
        if (a->ops == NULL)
                goto err_out;

        nlh = NLMSG_PUT(skb, pid, n->nlmsg_seq, RTM_DELACTION, sizeof(*t));
        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 nla_put_failure;

        err = a->ops->walk(skb, &dcb, RTM_DELACTION, a);
        if (err < 0)
                goto nla_put_failure;
        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(a->ops->owner);
        kfree(a);
        err = rtnetlink_send(skb, net, pid, RTNLGRP_TC,
                             n->nlmsg_flags & NLM_F_ECHO);
        if (err > 0)
                return 0;

        return err;

nla_put_failure:
nlmsg_failure:
        module_put(a->ops->owner);
err_out:
noflush_out:
        kfree_skb(skb);
        kfree(a);
        return err;
}

static int
tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
              u32 pid, int event)
{
        int i, ret;
        struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
        struct tc_action *head = NULL, *act, *act_prev = NULL;

        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, pid);
                else
                        return -EINVAL;
        }

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

                if (head == NULL)
                        head = act;
                else
                        act_prev->next = act;
                act_prev = act;
        }

        if (event == RTM_GETACTION)
                ret = act_get_notify(net, pid, n, head, event);
        else { /* delete */
                struct sk_buff *skb;

                skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
                if (!skb) {
                        ret = -ENOBUFS;
                        goto err;
                }

                if (tca_get_fill(skb, head, pid, n->nlmsg_seq, 0, event,
                                 0, 1) <= 0) {
                        kfree_skb(skb);
                        ret = -EINVAL;
                        goto err;
                }

                /* now do the delete */
                tcf_action_destroy(head, 0);
                ret = rtnetlink_send(skb, net, pid, RTNLGRP_TC,
                                     n->nlmsg_flags & NLM_F_ECHO);
                if (ret > 0)
                        return 0;
                return ret;
        }
err:
        cleanup_a(head);
        return ret;
}

static int tcf_add_notify(struct net *net, struct tc_action *a,
                          u32 pid, u32 seq, int event, u16 flags)
{
        struct tcamsg *t;
        struct nlmsghdr *nlh;
        struct sk_buff *skb;
        struct nlattr *nest;
        unsigned char *b;
        int err = 0;

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

        b = skb_tail_pointer(skb);

        nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*t), flags);
        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 nla_put_failure;

        if (tcf_action_dump(skb, a, 0, 0) < 0)
                goto nla_put_failure;

        nla_nest_end(skb, nest);

        nlh->nlmsg_len = skb_tail_pointer(skb) - b;
        NETLINK_CB(skb).dst_group = RTNLGRP_TC;

        err = rtnetlink_send(skb, net, pid, RTNLGRP_TC, flags & NLM_F_ECHO);
        if (err > 0)
                err = 0;
        return err;

nla_put_failure:
nlmsg_failure:
        kfree_skb(skb);
        return -1;
}


static int
tcf_action_add(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
               u32 pid, int ovr)
{
        int ret = 0;
        struct tc_action *act;
        struct tc_action *a;
        u32 seq = n->nlmsg_seq;

        act = tcf_action_init(nla, NULL, NULL, ovr, 0);
        if (act == NULL)
                goto done;
        if (IS_ERR(act)) {
                ret = PTR_ERR(act);
                goto done;
        }

        /* dump then free all the actions after update; inserted policy
         * stays intact
         */
        ret = tcf_add_notify(net, act, pid, seq, RTM_NEWACTION, n->nlmsg_flags);
        for (a = act; a; a = act) {
                act = a->next;
                kfree(a);
        }
done:
        return ret;
}

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

        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, pid, ovr);
                if (ret == -EAGAIN)
                        goto replay;
                break;
        case RTM_DELACTION:
                ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
                                    pid, RTM_DELACTION);
                break;
        case RTM_GETACTION:
                ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
                                    pid, 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 nlmsghdr *nlh;
        unsigned char *b = skb_tail_pointer(skb);
        struct nlattr *nest;
        struct tc_action_ops *a_o;
        struct tc_action a;
        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;

        memset(&a, 0, sizeof(struct tc_action));
        a.ops = a_o;

        if (a_o->walk == NULL) {
                WARN(1, "tc_dump_action: %s !capable of dumping table\n",
                     a_o->kind);
                goto nla_put_failure;
        }

        nlh = NLMSG_PUT(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
                        cb->nlh->nlmsg_type, sizeof(*t));
        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 nla_put_failure;

        ret = a_o->walk(skb, cb, RTM_GETACTION, &a);
        if (ret < 0)
                goto nla_put_failure;

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

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

nla_put_failure:
nlmsg_failure:
        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);