Merge tag 'for-linus-5.6b-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git...

[mirror_ubuntu-jammy-kernel.git] / net / sched / act_api.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net/sched/act_api.c  Packet action API.
 *
 * Author:      Jamal Hadi Salim
 */

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

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

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

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

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

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

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

int tcf_action_check_ctrlact(int action, struct tcf_proto *tp,
                             struct tcf_chain **newchain,
                             struct netlink_ext_ack *extack)
{
        int opcode = TC_ACT_EXT_OPCODE(action), ret = -EINVAL;
        u32 chain_index;

        if (!opcode)
                ret = action > TC_ACT_VALUE_MAX ? -EINVAL : 0;
        else if (opcode <= TC_ACT_EXT_OPCODE_MAX || action == TC_ACT_UNSPEC)
                ret = 0;
        if (ret) {
                NL_SET_ERR_MSG(extack, "invalid control action");
                goto end;
        }

        if (TC_ACT_EXT_CMP(action, TC_ACT_GOTO_CHAIN)) {
                chain_index = action & TC_ACT_EXT_VAL_MASK;
                if (!tp || !newchain) {
                        ret = -EINVAL;
                        NL_SET_ERR_MSG(extack,
                                       "can't goto NULL proto/chain");
                        goto end;
                }
                *newchain = tcf_chain_get_by_act(tp->chain->block, chain_index);
                if (!*newchain) {
                        ret = -ENOMEM;
                        NL_SET_ERR_MSG(extack,
                                       "can't allocate goto_chain");
                }
        }
end:
        return ret;
}
EXPORT_SYMBOL(tcf_action_check_ctrlact);

struct tcf_chain *tcf_action_set_ctrlact(struct tc_action *a, int action,
                                         struct tcf_chain *goto_chain)
{
        a->tcfa_action = action;
        goto_chain = rcu_replace_pointer(a->goto_chain, goto_chain, 1);
        return goto_chain;
}
EXPORT_SYMBOL(tcf_action_set_ctrlact);

/* XXX: For standalone actions, we don't need a RCU grace period either, because
 * actions are always connected to filters and filters are already destroyed in
 * RCU callbacks, so after a RCU grace period actions are already disconnected
 * from filters. Readers later can not find us.
 */
static void free_tcf(struct tc_action *p)
{
        struct tcf_chain *chain = rcu_dereference_protected(p->goto_chain, 1);

        free_percpu(p->cpu_bstats);
        free_percpu(p->cpu_bstats_hw);
        free_percpu(p->cpu_qstats);

        tcf_set_action_cookie(&p->act_cookie, NULL);
        if (chain)
                tcf_chain_put_by_act(chain);

        kfree(p);
}

static void tcf_action_cleanup(struct tc_action *p)
{
        if (p->ops->cleanup)
                p->ops->cleanup(p);

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

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

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

                tcf_action_cleanup(p);
                return 1;
        }

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

        return 0;
}

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

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

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

        return ret;
}
EXPORT_SYMBOL(__tcf_idr_release);

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

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

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

        return  nla_total_size(0) /* action number nested */
                + nla_total_size(IFNAMSIZ) /* TCA_ACT_KIND */
                + cookie_len /* TCA_ACT_COOKIE */
                + nla_total_size(0) /* TCA_ACT_STATS nested */
                + nla_total_size(sizeof(struct nla_bitfield32)) /* TCA_ACT_FLAGS */
                /* TCA_STATS_BASIC */
                + nla_total_size_64bit(sizeof(struct gnet_stats_basic))
                /* TCA_STATS_PKT64 */
                + nla_total_size_64bit(sizeof(u64))
                /* TCA_STATS_QUEUE */
                + nla_total_size_64bit(sizeof(struct gnet_stats_queue))
                + nla_total_size(0) /* TCA_OPTIONS nested */
                + nla_total_size(sizeof(struct tcf_t)); /* TCA_GACT_TM */
}

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

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

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

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

        mutex_lock(&idrinfo->lock);

        s_i = cb->args[0];

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

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

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

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

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

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

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

        return 0;
}

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

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

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

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

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

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

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

int tcf_idr_search(struct tc_action_net *tn, struct tc_action **a, u32 index)
{
        struct tcf_idrinfo *idrinfo = tn->idrinfo;
        struct tc_action *p;

        mutex_lock(&idrinfo->lock);
        p = idr_find(&idrinfo->action_idr, index);
        if (IS_ERR(p))
                p = NULL;
        else if (p)
                refcount_inc(&p->tcfa_refcnt);
        mutex_unlock(&idrinfo->lock);

        if (p) {
                *a = p;
                return true;
        }
        return false;
}
EXPORT_SYMBOL(tcf_idr_search);

static int tcf_idr_delete_index(struct tcf_idrinfo *idrinfo, u32 index)
{
        struct tc_action *p;
        int ret = 0;

        mutex_lock(&idrinfo->lock);
        p = idr_find(&idrinfo->action_idr, index);
        if (!p) {
                mutex_unlock(&idrinfo->lock);
                return -ENOENT;
        }

        if (!atomic_read(&p->tcfa_bindcnt)) {
                if (refcount_dec_and_test(&p->tcfa_refcnt)) {
                        struct module *owner = p->ops->owner;

                        WARN_ON(p != idr_remove(&idrinfo->action_idr,
                                                p->tcfa_index));
                        mutex_unlock(&idrinfo->lock);

                        tcf_action_cleanup(p);
                        module_put(owner);
                        return 0;
                }
                ret = 0;
        } else {
                ret = -EPERM;
        }

        mutex_unlock(&idrinfo->lock);
        return ret;
}

int tcf_idr_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, u32 flags)
{
        struct tc_action *p = kzalloc(ops->size, GFP_KERNEL);
        struct tcf_idrinfo *idrinfo = tn->idrinfo;
        int err = -ENOMEM;

        if (unlikely(!p))
                return -ENOMEM;
        refcount_set(&p->tcfa_refcnt, 1);
        if (bind)
                atomic_set(&p->tcfa_bindcnt, 1);

        if (cpustats) {
                p->cpu_bstats = netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
                if (!p->cpu_bstats)
                        goto err1;
                p->cpu_bstats_hw = netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
                if (!p->cpu_bstats_hw)
                        goto err2;
                p->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
                if (!p->cpu_qstats)
                        goto err3;
        }
        spin_lock_init(&p->tcfa_lock);
        p->tcfa_index = index;
        p->tcfa_tm.install = jiffies;
        p->tcfa_tm.lastuse = jiffies;
        p->tcfa_tm.firstuse = 0;
        p->tcfa_flags = flags;
        if (est) {
                err = gen_new_estimator(&p->tcfa_bstats, p->cpu_bstats,
                                        &p->tcfa_rate_est,
                                        &p->tcfa_lock, NULL, est);
                if (err)
                        goto err4;
        }

        p->idrinfo = idrinfo;
        p->ops = ops;
        *a = p;
        return 0;
err4:
        free_percpu(p->cpu_qstats);
err3:
        free_percpu(p->cpu_bstats_hw);
err2:
        free_percpu(p->cpu_bstats);
err1:
        kfree(p);
        return err;
}
EXPORT_SYMBOL(tcf_idr_create);

int tcf_idr_create_from_flags(struct tc_action_net *tn, u32 index,
                              struct nlattr *est, struct tc_action **a,
                              const struct tc_action_ops *ops, int bind,
                              u32 flags)
{
        /* Set cpustats according to actions flags. */
        return tcf_idr_create(tn, index, est, a, ops, bind,
                              !(flags & TCA_ACT_FLAGS_NO_PERCPU_STATS), flags);
}
EXPORT_SYMBOL(tcf_idr_create_from_flags);

void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a)
{
        struct tcf_idrinfo *idrinfo = tn->idrinfo;

        mutex_lock(&idrinfo->lock);
        /* Replace ERR_PTR(-EBUSY) allocated by tcf_idr_check_alloc */
        WARN_ON(!IS_ERR(idr_replace(&idrinfo->action_idr, a, a->tcfa_index)));
        mutex_unlock(&idrinfo->lock);
}
EXPORT_SYMBOL(tcf_idr_insert);

/* Cleanup idr index that was allocated but not initialized. */

void tcf_idr_cleanup(struct tc_action_net *tn, u32 index)
{
        struct tcf_idrinfo *idrinfo = tn->idrinfo;

        mutex_lock(&idrinfo->lock);
        /* Remove ERR_PTR(-EBUSY) allocated by tcf_idr_check_alloc */
        WARN_ON(!IS_ERR(idr_remove(&idrinfo->action_idr, index)));
        mutex_unlock(&idrinfo->lock);
}
EXPORT_SYMBOL(tcf_idr_cleanup);

/* Check if action with specified index exists. If actions is found, increments
 * its reference and bind counters, and return 1. Otherwise insert temporary
 * error pointer (to prevent concurrent users from inserting actions with same
 * index) and return 0.
 */

int tcf_idr_check_alloc(struct tc_action_net *tn, u32 *index,
                        struct tc_action **a, int bind)
{
        struct tcf_idrinfo *idrinfo = tn->idrinfo;
        struct tc_action *p;
        int ret;

again:
        mutex_lock(&idrinfo->lock);
        if (*index) {
                p = idr_find(&idrinfo->action_idr, *index);
                if (IS_ERR(p)) {
                        /* This means that another process allocated
                         * index but did not assign the pointer yet.
                         */
                        mutex_unlock(&idrinfo->lock);
                        goto again;
                }

                if (p) {
                        refcount_inc(&p->tcfa_refcnt);
                        if (bind)
                                atomic_inc(&p->tcfa_bindcnt);
                        *a = p;
                        ret = 1;
                } else {
                        *a = NULL;
                        ret = idr_alloc_u32(&idrinfo->action_idr, NULL, index,
                                            *index, GFP_KERNEL);
                        if (!ret)
                                idr_replace(&idrinfo->action_idr,
                                            ERR_PTR(-EBUSY), *index);
                }
        } else {
                *index = 1;
                *a = NULL;
                ret = idr_alloc_u32(&idrinfo->action_idr, NULL, index,
                                    UINT_MAX, GFP_KERNEL);
                if (!ret)
                        idr_replace(&idrinfo->action_idr, ERR_PTR(-EBUSY),
                                    *index);
        }
        mutex_unlock(&idrinfo->lock);
        return ret;
}
EXPORT_SYMBOL(tcf_idr_check_alloc);

void tcf_idrinfo_destroy(const struct tc_action_ops *ops,
                         struct tcf_idrinfo *idrinfo)
{
        struct idr *idr = &idrinfo->action_idr;
        struct tc_action *p;
        int ret;
        unsigned long id = 1;
        unsigned long tmp;

        idr_for_each_entry_ul(idr, p, tmp, id) {
                ret = __tcf_idr_release(p, false, true);
                if (ret == ACT_P_DELETED)
                        module_put(ops->owner);
                else if (ret < 0)
                        return;
        }
        idr_destroy(&idrinfo->action_idr);
}
EXPORT_SYMBOL(tcf_idrinfo_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;

        /* We have to register pernet ops before making the action ops visible,
         * otherwise tcf_action_init_1() could get a partially initialized
         * netns.
         */
        ret = register_pernet_subsys(ops);
        if (ret)
                return ret;

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

        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;

        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);
        if (!err)
                unregister_pernet_subsys(ops);
        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;
}

/*TCA_ACT_MAX_PRIO is 32, there count upto 32 */
#define TCA_ACT_MAX_PRIO_MASK 0x1FF
int tcf_action_exec(struct sk_buff *skb, struct tc_action **actions,
                    int nr_actions, struct tcf_result *res)
{
        u32 jmp_prgcnt = 0;
        u32 jmp_ttl = TCA_ACT_MAX_PRIO; /*matches actions per filter */
        int i;
        int ret = TC_ACT_OK;

        if (skb_skip_tc_classify(skb))
                return TC_ACT_OK;

restart_act_graph:
        for (i = 0; i < nr_actions; i++) {
                const struct tc_action *a = actions[i];

                if (jmp_prgcnt > 0) {
                        jmp_prgcnt -= 1;
                        continue;
                }
repeat:
                ret = a->ops->act(skb, a, res);
                if (ret == TC_ACT_REPEAT)
                        goto repeat;    /* we need a ttl - JHS */

                if (TC_ACT_EXT_CMP(ret, TC_ACT_JUMP)) {
                        jmp_prgcnt = ret & TCA_ACT_MAX_PRIO_MASK;
                        if (!jmp_prgcnt || (jmp_prgcnt > nr_actions)) {
                                /* faulty opcode, stop pipeline */
                                return TC_ACT_OK;
                        } else {
                                jmp_ttl -= 1;
                                if (jmp_ttl > 0)
                                        goto restart_act_graph;
                                else /* faulty graph, stop pipeline */
                                        return TC_ACT_OK;
                        }
                } else if (TC_ACT_EXT_CMP(ret, TC_ACT_GOTO_CHAIN)) {
                        if (unlikely(!rcu_access_pointer(a->goto_chain))) {
                                net_warn_ratelimited("can't go to NULL chain!\n");
                                return TC_ACT_SHOT;
                        }
                        tcf_action_goto_chain_exec(a, res);
                }

                if (ret != TC_ACT_PIPE)
                        break;
        }

        return ret;
}
EXPORT_SYMBOL(tcf_action_exec);

int tcf_action_destroy(struct tc_action *actions[], int bind)
{
        const struct tc_action_ops *ops;
        struct tc_action *a;
        int ret = 0, i;

        for (i = 0; i < TCA_ACT_MAX_PRIO && actions[i]; i++) {
                a = actions[i];
                actions[i] = NULL;
                ops = a->ops;
                ret = __tcf_idr_release(a, bind, true);
                if (ret == ACT_P_DELETED)
                        module_put(ops->owner);
                else if (ret < 0)
                        return ret;
        }
        return ret;
}

static int tcf_action_destroy_1(struct tc_action *a, int bind)
{
        struct tc_action *actions[] = { a, NULL };

        return tcf_action_destroy(actions, bind);
}

static int tcf_action_put(struct tc_action *p)
{
        return __tcf_action_put(p, false);
}

/* Put all actions in this array, skip those NULL's. */
static void tcf_action_put_many(struct tc_action *actions[])
{
        int i;

        for (i = 0; i < TCA_ACT_MAX_PRIO; i++) {
                struct tc_action *a = actions[i];
                const struct tc_action_ops *ops;

                if (!a)
                        continue;
                ops = a->ops;
                if (tcf_action_put(a))
                        module_put(ops->owner);
        }
}

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;
        struct tc_cookie *cookie;

        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;

        rcu_read_lock();
        cookie = rcu_dereference(a->act_cookie);
        if (cookie) {
                if (nla_put(skb, TCA_ACT_COOKIE, cookie->len, cookie->data)) {
                        rcu_read_unlock();
                        goto nla_put_failure;
                }
        }
        rcu_read_unlock();

        if (a->tcfa_flags) {
                struct nla_bitfield32 flags = { a->tcfa_flags,
                                                a->tcfa_flags, };

                if (nla_put(skb, TCA_ACT_FLAGS, sizeof(flags), &flags))
                        goto nla_put_failure;
        }

        nest = nla_nest_start_noflag(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 *actions[],
                    int bind, int ref)
{
        struct tc_action *a;
        int err = -EINVAL, i;
        struct nlattr *nest;

        for (i = 0; i < TCA_ACT_MAX_PRIO && actions[i]; i++) {
                a = actions[i];
                nest = nla_nest_start_noflag(skb, i + 1);
                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;
}

static struct tc_cookie *nla_memdup_cookie(struct nlattr **tb)
{
        struct tc_cookie *c = kzalloc(sizeof(*c), GFP_KERNEL);
        if (!c)
                return NULL;

        c->data = nla_memdup(tb[TCA_ACT_COOKIE], GFP_KERNEL);
        if (!c->data) {
                kfree(c);
                return NULL;
        }
        c->len = nla_len(tb[TCA_ACT_COOKIE]);

        return c;
}

static const u32 tca_act_flags_allowed = TCA_ACT_FLAGS_NO_PERCPU_STATS;
static const struct nla_policy tcf_action_policy[TCA_ACT_MAX + 1] = {
        [TCA_ACT_KIND]          = { .type = NLA_STRING },
        [TCA_ACT_INDEX]         = { .type = NLA_U32 },
        [TCA_ACT_COOKIE]        = { .type = NLA_BINARY,
                                    .len = TC_COOKIE_MAX_SIZE },
        [TCA_ACT_OPTIONS]       = { .type = NLA_NESTED },
        [TCA_ACT_FLAGS]         = { .type = NLA_BITFIELD32,
                                    .validation_data = &tca_act_flags_allowed },
};

struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
                                    struct nlattr *nla, struct nlattr *est,
                                    char *name, int ovr, int bind,
                                    bool rtnl_held,
                                    struct netlink_ext_ack *extack)
{
        struct nla_bitfield32 flags = { 0, 0 };
        struct tc_action *a;
        struct tc_action_ops *a_o;
        struct tc_cookie *cookie = NULL;
        char act_name[IFNAMSIZ];
        struct nlattr *tb[TCA_ACT_MAX + 1];
        struct nlattr *kind;
        int err;

        if (name == NULL) {
                err = nla_parse_nested_deprecated(tb, TCA_ACT_MAX, nla,
                                                  tcf_action_policy, extack);
                if (err < 0)
                        goto err_out;
                err = -EINVAL;
                kind = tb[TCA_ACT_KIND];
                if (!kind) {
                        NL_SET_ERR_MSG(extack, "TC action kind must be specified");
                        goto err_out;
                }
                if (nla_strlcpy(act_name, kind, IFNAMSIZ) >= IFNAMSIZ) {
                        NL_SET_ERR_MSG(extack, "TC action name too long");
                        goto err_out;
                }
                if (tb[TCA_ACT_COOKIE]) {
                        cookie = nla_memdup_cookie(tb);
                        if (!cookie) {
                                NL_SET_ERR_MSG(extack, "No memory to generate TC cookie");
                                err = -ENOMEM;
                                goto err_out;
                        }
                }
                if (tb[TCA_ACT_FLAGS])
                        flags = nla_get_bitfield32(tb[TCA_ACT_FLAGS]);
        } else {
                if (strlcpy(act_name, name, IFNAMSIZ) >= IFNAMSIZ) {
                        NL_SET_ERR_MSG(extack, "TC action name too long");
                        err = -EINVAL;
                        goto err_out;
                }
        }

        a_o = tc_lookup_action_n(act_name);
        if (a_o == NULL) {
#ifdef CONFIG_MODULES
                if (rtnl_held)
                        rtnl_unlock();
                request_module("act_%s", act_name);
                if (rtnl_held)
                        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
                NL_SET_ERR_MSG(extack, "Failed to load TC action module");
                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,
                                rtnl_held, tp, flags.value, extack);
        else
                err = a_o->init(net, nla, est, &a, ovr, bind, rtnl_held,
                                tp, flags.value, extack);
        if (err < 0)
                goto err_mod;

        if (!name && tb[TCA_ACT_COOKIE])
                tcf_set_action_cookie(&a->act_cookie, cookie);

        /* 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);

        if (TC_ACT_EXT_CMP(a->tcfa_action, TC_ACT_GOTO_CHAIN) &&
            !rcu_access_pointer(a->goto_chain)) {
                tcf_action_destroy_1(a, bind);
                NL_SET_ERR_MSG(extack, "can't use goto chain with NULL chain");
                return ERR_PTR(-EINVAL);
        }

        return a;

err_mod:
        module_put(a_o->owner);
err_out:
        if (cookie) {
                kfree(cookie->data);
                kfree(cookie);
        }
        return ERR_PTR(err);
}

/* Returns numbers of initialized actions or negative error. */

int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla,
                    struct nlattr *est, char *name, int ovr, int bind,
                    struct tc_action *actions[], size_t *attr_size,
                    bool rtnl_held, struct netlink_ext_ack *extack)
{
        struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
        struct tc_action *act;
        size_t sz = 0;
        int err;
        int i;

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

        for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
                act = tcf_action_init_1(net, tp, tb[i], est, name, ovr, bind,
                                        rtnl_held, extack);
                if (IS_ERR(act)) {
                        err = PTR_ERR(act);
                        goto err;
                }
                sz += tcf_action_fill_size(act);
                /* Start from index 0 */
                actions[i - 1] = act;
        }

        *attr_size = tcf_action_full_attrs_size(sz);
        return i - 1;

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

void tcf_action_update_stats(struct tc_action *a, u64 bytes, u32 packets,
                             bool drop, bool hw)
{
        if (a->cpu_bstats) {
                _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);

                if (drop)
                        this_cpu_ptr(a->cpu_qstats)->drops += packets;

                if (hw)
                        _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats_hw),
                                           bytes, packets);
                return;
        }

        _bstats_update(&a->tcfa_bstats, bytes, packets);
        if (drop)
                a->tcfa_qstats.drops += packets;
        if (hw)
                _bstats_update(&a->tcfa_bstats_hw, bytes, packets);
}
EXPORT_SYMBOL(tcf_action_update_stats);

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_basic_hw(NULL, &d, p->cpu_bstats_hw,
                                     &p->tcfa_bstats_hw) < 0 ||
            gnet_stats_copy_rate_est(&d, &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 tc_action *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_noflag(skb, TCA_ACT_TAB);
        if (!nest)
                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
tcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,
               struct tc_action *actions[], int event,
               struct netlink_ext_ack *extack)
{
        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, 1) <= 0) {
                NL_SET_ERR_MSG(extack, "Failed to fill netlink attributes while adding TC action");
                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 netlink_ext_ack *extack)
{
        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_deprecated(tb, TCA_ACT_MAX, nla,
                                          tcf_action_policy, extack);
        if (err < 0)
                goto err_out;

        err = -EINVAL;
        if (tb[TCA_ACT_INDEX] == NULL ||
            nla_len(tb[TCA_ACT_INDEX]) < sizeof(index)) {
                NL_SET_ERR_MSG(extack, "Invalid TC action index value");
                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 */
                NL_SET_ERR_MSG(extack, "Specified TC action kind not found");
                goto err_out;
        }
        err = -ENOENT;
        if (ops->lookup(net, &a, index) == 0) {
                NL_SET_ERR_MSG(extack, "TC action with specified index not found");
                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 netlink_ext_ack *extack)
{
        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)
                return err;

        b = skb_tail_pointer(skb);

        err = nla_parse_nested_deprecated(tb, TCA_ACT_MAX, nla,
                                          tcf_action_policy, extack);
        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 */
                NL_SET_ERR_MSG(extack, "Cannot flush unknown TC action");
                goto err_out;
        }

        nlh = nlmsg_put(skb, portid, n->nlmsg_seq, RTM_DELACTION,
                        sizeof(*t), 0);
        if (!nlh) {
                NL_SET_ERR_MSG(extack, "Failed to create TC action flush notification");
                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_noflag(skb, TCA_ACT_TAB);
        if (!nest) {
                NL_SET_ERR_MSG(extack, "Failed to add new netlink message");
                goto out_module_put;
        }

        err = ops->walk(net, skb, &dcb, RTM_DELACTION, ops, extack);
        if (err <= 0) {
                nla_nest_cancel(skb, nest);
                goto out_module_put;
        }

        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;
        if (err < 0)
                NL_SET_ERR_MSG(extack, "Failed to send TC action flush notification");

        return err;

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

static int tcf_action_delete(struct net *net, struct tc_action *actions[])
{
        int i;

        for (i = 0; i < TCA_ACT_MAX_PRIO && actions[i]; i++) {
                struct tc_action *a = actions[i];
                const struct tc_action_ops *ops = a->ops;
                /* Actions can be deleted concurrently so we must save their
                 * type and id to search again after reference is released.
                 */
                struct tcf_idrinfo *idrinfo = a->idrinfo;
                u32 act_index = a->tcfa_index;

                actions[i] = NULL;
                if (tcf_action_put(a)) {
                        /* last reference, action was deleted concurrently */
                        module_put(ops->owner);
                } else  {
                        int ret;

                        /* now do the delete */
                        ret = tcf_idr_delete_index(idrinfo, act_index);
                        if (ret < 0)
                                return ret;
                }
        }
        return 0;
}

static int
tcf_del_notify(struct net *net, struct nlmsghdr *n, struct tc_action *actions[],
               u32 portid, size_t attr_size, struct netlink_ext_ack *extack)
{
        int ret;
        struct sk_buff *skb;

        skb = alloc_skb(attr_size <= NLMSG_GOODSIZE ? NLMSG_GOODSIZE : attr_size,
                        GFP_KERNEL);
        if (!skb)
                return -ENOBUFS;

        if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, 0, RTM_DELACTION,
                         0, 2) <= 0) {
                NL_SET_ERR_MSG(extack, "Failed to fill netlink TC action attributes");
                kfree_skb(skb);
                return -EINVAL;
        }

        /* now do the delete */
        ret = tcf_action_delete(net, actions);
        if (ret < 0) {
                NL_SET_ERR_MSG(extack, "Failed to delete TC action");
                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, struct netlink_ext_ack *extack)
{
        int i, ret;
        struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
        struct tc_action *act;
        size_t attr_size = 0;
        struct tc_action *actions[TCA_ACT_MAX_PRIO] = {};

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

        if (event == RTM_DELACTION && n->nlmsg_flags & NLM_F_ROOT) {
                if (tb[1])
                        return tca_action_flush(net, tb[1], n, portid, extack);

                NL_SET_ERR_MSG(extack, "Invalid netlink attributes while flushing TC action");
                return -EINVAL;
        }

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

        attr_size = tcf_action_full_attrs_size(attr_size);

        if (event == RTM_GETACTION)
                ret = tcf_get_notify(net, portid, n, actions, event, extack);
        else { /* delete */
                ret = tcf_del_notify(net, n, actions, portid, attr_size, extack);
                if (ret)
                        goto err;
                return 0;
        }
err:
        tcf_action_put_many(actions);
        return ret;
}

static int
tcf_add_notify(struct net *net, struct nlmsghdr *n, struct tc_action *actions[],
               u32 portid, size_t attr_size, struct netlink_ext_ack *extack)
{
        struct sk_buff *skb;
        int err = 0;

        skb = alloc_skb(attr_size <= NLMSG_GOODSIZE ? NLMSG_GOODSIZE : attr_size,
                        GFP_KERNEL);
        if (!skb)
                return -ENOBUFS;

        if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, n->nlmsg_flags,
                         RTM_NEWACTION, 0, 0) <= 0) {
                NL_SET_ERR_MSG(extack, "Failed to fill netlink attributes while adding TC action");
                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,
                          struct netlink_ext_ack *extack)
{
        size_t attr_size = 0;
        int loop, ret;
        struct tc_action *actions[TCA_ACT_MAX_PRIO] = {};

        for (loop = 0; loop < 10; loop++) {
                ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0,
                                      actions, &attr_size, true, extack);
                if (ret != -EAGAIN)
                        break;
        }

        if (ret < 0)
                return ret;
        ret = tcf_add_notify(net, n, actions, portid, attr_size, extack);
        if (ovr)
                tcf_action_put_many(actions);

        return ret;
}

static u32 tcaa_root_flags_allowed = TCA_FLAG_LARGE_DUMP_ON;
static const struct nla_policy tcaa_policy[TCA_ROOT_MAX + 1] = {
        [TCA_ROOT_FLAGS] = { .type = NLA_BITFIELD32,
                             .validation_data = &tcaa_root_flags_allowed },
        [TCA_ROOT_TIME_DELTA]      = { .type = NLA_U32 },
};

static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
                         struct netlink_ext_ack *extack)
{
        struct net *net = sock_net(skb->sk);
        struct nlattr *tca[TCA_ROOT_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_deprecated(n, sizeof(struct tcamsg), tca,
                                     TCA_ROOT_MAX, NULL, extack);
        if (ret < 0)
                return ret;

        if (tca[TCA_ACT_TAB] == NULL) {
                NL_SET_ERR_MSG(extack, "Netlink action attributes missing");
                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;
                ret = tcf_action_add(net, tca[TCA_ACT_TAB], n, portid, ovr,
                                     extack);
                break;
        case RTM_DELACTION:
                ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
                                    portid, RTM_DELACTION, extack);
                break;
        case RTM_GETACTION:
                ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
                                    portid, RTM_GETACTION, extack);
                break;
        default:
                BUG();
        }

        return ret;
}

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

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

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

        if (tb[1] == NULL)
                return NULL;
        if (nla_parse_nested_deprecated(tb2, TCA_ACT_MAX, tb[1], tcf_action_policy, 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 *tb[TCA_ROOT_MAX + 1];
        struct nlattr *count_attr = NULL;
        unsigned long jiffy_since = 0;
        struct nlattr *kind = NULL;
        struct nla_bitfield32 bf;
        u32 msecs_since = 0;
        u32 act_count = 0;

        ret = nlmsg_parse_deprecated(cb->nlh, sizeof(struct tcamsg), tb,
                                     TCA_ROOT_MAX, tcaa_policy, cb->extack);
        if (ret < 0)
                return ret;

        kind = find_dump_kind(tb);
        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;

        cb->args[2] = 0;
        if (tb[TCA_ROOT_FLAGS]) {
                bf = nla_get_bitfield32(tb[TCA_ROOT_FLAGS]);
                cb->args[2] = bf.value;
        }

        if (tb[TCA_ROOT_TIME_DELTA]) {
                msecs_since = nla_get_u32(tb[TCA_ROOT_TIME_DELTA]);
        }

        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;

        if (msecs_since)
                jiffy_since = jiffies - msecs_to_jiffies(msecs_since);

        t = nlmsg_data(nlh);
        t->tca_family = AF_UNSPEC;
        t->tca__pad1 = 0;
        t->tca__pad2 = 0;
        cb->args[3] = jiffy_since;
        count_attr = nla_reserve(skb, TCA_ROOT_COUNT, sizeof(u32));
        if (!count_attr)
                goto out_module_put;

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

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

        if (ret > 0) {
                nla_nest_end(skb, nest);
                ret = skb->len;
                act_count = cb->args[1];
                memcpy(nla_data(count_attr), &act_count, sizeof(u32));
                cb->args[1] = 0;
        } 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, 0);
        rtnl_register(PF_UNSPEC, RTM_DELACTION, tc_ctl_action, NULL, 0);
        rtnl_register(PF_UNSPEC, RTM_GETACTION, tc_ctl_action, tc_dump_action,
                      0);

        return 0;
}

subsys_initcall(tc_action_init);