act_api.c

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/*
 * 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 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, a, 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 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, 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 nlattr *nla, struct nlmsghdr *n, u32 portid)
{
    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 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];
    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, 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 = a->ops->walk(skb, &dcb, RTM_DELACTION, a);
    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(a->ops->owner);
    kfree(a);
    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(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 portid, 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, portid);
        else
            return -EINVAL;
    }

    for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
        act = tcf_action_get_1(tb[i], n, portid);
        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, portid, 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, portid, 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, portid, 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 portid, 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_put(skb, portid, seq, event, sizeof(*t), flags);
    if (!nlh)
        goto out_kfree_skb;
    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_kfree_skb;

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

    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, portid, RTNLGRP_TC, flags & NLM_F_ECHO);
    if (err > 0)
        err = 0;
    return err;

out_kfree_skb:
    kfree_skb(skb);
    return -1;
}


static int
tcf_action_add(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
           u32 portid, 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, portid, 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 portid = skb ? NETLINK_CB(skb).portid : 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, 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 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 out_module_put;
    }

    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(skb, cb, RTM_GETACTION, &a);
    if (ret < 0)
        goto out_module_put;

    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).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);