act_gact.c

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/*
 * net/sched/gact.c Generic actions
 *
 *      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.
 *
 * copyright    Jamal Hadi Salim (2002-4)
 *
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/module.h>
#include <linux/init.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <linux/tc_act/tc_gact.h>
#include <net/tc_act/tc_gact.h>

#define GACT_TAB_MASK   15
static struct tcf_common *tcf_gact_ht[GACT_TAB_MASK + 1];
static u32 gact_idx_gen;
static DEFINE_RWLOCK(gact_lock);

static struct tcf_hashinfo gact_hash_info = {
    .htab   =   tcf_gact_ht,
    .hmask  =   GACT_TAB_MASK,
    .lock   =   &gact_lock,
};

#ifdef CONFIG_GACT_PROB
static int gact_net_rand(struct tcf_gact *gact)
{
    if (!gact->tcfg_pval || net_random() % gact->tcfg_pval)
        return gact->tcf_action;
    return gact->tcfg_paction;
}

static int gact_determ(struct tcf_gact *gact)
{
    if (!gact->tcfg_pval || gact->tcf_bstats.packets % gact->tcfg_pval)
        return gact->tcf_action;
    return gact->tcfg_paction;
}

typedef int (*g_rand)(struct tcf_gact *gact);
static g_rand gact_rand[MAX_RAND] = { NULL, gact_net_rand, gact_determ };
#endif /* CONFIG_GACT_PROB */

static const struct nla_policy gact_policy[TCA_GACT_MAX + 1] = {
    [TCA_GACT_PARMS]    = { .len = sizeof(struct tc_gact) },
    [TCA_GACT_PROB]     = { .len = sizeof(struct tc_gact_p) },
};

static int tcf_gact_init(struct nlattr *nla, struct nlattr *est,
             struct tc_action *a, int ovr, int bind)
{
    struct nlattr *tb[TCA_GACT_MAX + 1];
    struct tc_gact *parm;
    struct tcf_gact *gact;
    struct tcf_common *pc;
    int ret = 0;
    int err;
#ifdef CONFIG_GACT_PROB
    struct tc_gact_p *p_parm = NULL;
#endif

    if (nla == NULL)
        return -EINVAL;

    err = nla_parse_nested(tb, TCA_GACT_MAX, nla, gact_policy);
    if (err < 0)
        return err;

    if (tb[TCA_GACT_PARMS] == NULL)
        return -EINVAL;
    parm = nla_data(tb[TCA_GACT_PARMS]);

#ifndef CONFIG_GACT_PROB
    if (tb[TCA_GACT_PROB] != NULL)
        return -EOPNOTSUPP;
#else
    if (tb[TCA_GACT_PROB]) {
        p_parm = nla_data(tb[TCA_GACT_PROB]);
        if (p_parm->ptype >= MAX_RAND)
            return -EINVAL;
    }
#endif

    pc = tcf_hash_check(parm->index, a, bind, &gact_hash_info);
    if (!pc) {
        pc = tcf_hash_create(parm->index, est, a, sizeof(*gact),
                     bind, &gact_idx_gen, &gact_hash_info);
        if (IS_ERR(pc))
            return PTR_ERR(pc);
        ret = ACT_P_CREATED;
    } else {
        if (!ovr) {
            tcf_hash_release(pc, bind, &gact_hash_info);
            return -EEXIST;
        }
    }

    gact = to_gact(pc);

    spin_lock_bh(&gact->tcf_lock);
    gact->tcf_action = parm->action;
#ifdef CONFIG_GACT_PROB
    if (p_parm) {
        gact->tcfg_paction = p_parm->paction;
        gact->tcfg_pval    = p_parm->pval;
        gact->tcfg_ptype   = p_parm->ptype;
    }
#endif
    spin_unlock_bh(&gact->tcf_lock);
    if (ret == ACT_P_CREATED)
        tcf_hash_insert(pc, &gact_hash_info);
    return ret;
}

static int tcf_gact_cleanup(struct tc_action *a, int bind)
{
    struct tcf_gact *gact = a->priv;

    if (gact)
        return tcf_hash_release(&gact->common, bind, &gact_hash_info);
    return 0;
}

static int tcf_gact(struct sk_buff *skb, const struct tc_action *a,
            struct tcf_result *res)
{
    struct tcf_gact *gact = a->priv;
    int action = TC_ACT_SHOT;

    spin_lock(&gact->tcf_lock);
#ifdef CONFIG_GACT_PROB
    if (gact->tcfg_ptype)
        action = gact_rand[gact->tcfg_ptype](gact);
    else
        action = gact->tcf_action;
#else
    action = gact->tcf_action;
#endif
    gact->tcf_bstats.bytes += qdisc_pkt_len(skb);
    gact->tcf_bstats.packets++;
    if (action == TC_ACT_SHOT)
        gact->tcf_qstats.drops++;
    gact->tcf_tm.lastuse = jiffies;
    spin_unlock(&gact->tcf_lock);

    return action;
}

static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
{
    unsigned char *b = skb_tail_pointer(skb);
    struct tcf_gact *gact = a->priv;
    struct tc_gact opt = {
        .index   = gact->tcf_index,
        .refcnt  = gact->tcf_refcnt - ref,
        .bindcnt = gact->tcf_bindcnt - bind,
        .action  = gact->tcf_action,
    };
    struct tcf_t t;

    if (nla_put(skb, TCA_GACT_PARMS, sizeof(opt), &opt))
        goto nla_put_failure;
#ifdef CONFIG_GACT_PROB
    if (gact->tcfg_ptype) {
        struct tc_gact_p p_opt = {
            .paction = gact->tcfg_paction,
            .pval    = gact->tcfg_pval,
            .ptype   = gact->tcfg_ptype,
        };

        if (nla_put(skb, TCA_GACT_PROB, sizeof(p_opt), &p_opt))
            goto nla_put_failure;
    }
#endif
    t.install = jiffies_to_clock_t(jiffies - gact->tcf_tm.install);
    t.lastuse = jiffies_to_clock_t(jiffies - gact->tcf_tm.lastuse);
    t.expires = jiffies_to_clock_t(gact->tcf_tm.expires);
    if (nla_put(skb, TCA_GACT_TM, sizeof(t), &t))
        goto nla_put_failure;
    return skb->len;

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

static struct tc_action_ops act_gact_ops = {
    .kind       =   "gact",
    .hinfo      =   &gact_hash_info,
    .type       =   TCA_ACT_GACT,
    .capab      =   TCA_CAP_NONE,
    .owner      =   THIS_MODULE,
    .act        =   tcf_gact,
    .dump       =   tcf_gact_dump,
    .cleanup    =   tcf_gact_cleanup,
    .lookup     =   tcf_hash_search,
    .init       =   tcf_gact_init,
    .walk       =   tcf_generic_walker
};

MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
MODULE_DESCRIPTION("Generic Classifier actions");
MODULE_LICENSE("GPL");

static int __init gact_init_module(void)
{
#ifdef CONFIG_GACT_PROB
    pr_info("GACT probability on\n");
#else
    pr_info("GACT probability NOT on\n");
#endif
    return tcf_register_action(&act_gact_ops);
}

static void __exit gact_cleanup_module(void)
{
    tcf_unregister_action(&act_gact_ops);
}

module_init(gact_init_module);
module_exit(gact_cleanup_module);