act_mirred.c

Go to the documentation of this file.

/*
 * net/sched/mirred.c   packet mirroring and redirect 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.
 *
 * Authors: Jamal Hadi Salim (2002-4)
 *
 * TODO: Add ingress support (and socket redirect support)
 *
 */

#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 <linux/gfp.h>
#include <net/net_namespace.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <linux/tc_act/tc_mirred.h>
#include <net/tc_act/tc_mirred.h>

#include <linux/if_arp.h>

#define MIRRED_TAB_MASK     7
static struct tcf_common *tcf_mirred_ht[MIRRED_TAB_MASK + 1];
static u32 mirred_idx_gen;
static DEFINE_RWLOCK(mirred_lock);
static LIST_HEAD(mirred_list);

static struct tcf_hashinfo mirred_hash_info = {
    .htab   =   tcf_mirred_ht,
    .hmask  =   MIRRED_TAB_MASK,
    .lock   =   &mirred_lock,
};

static int tcf_mirred_release(struct tcf_mirred *m, int bind)
{
    if (m) {
        if (bind)
            m->tcf_bindcnt--;
        m->tcf_refcnt--;
        if (!m->tcf_bindcnt && m->tcf_refcnt <= 0) {
            list_del(&m->tcfm_list);
            if (m->tcfm_dev)
                dev_put(m->tcfm_dev);
            tcf_hash_destroy(&m->common, &mirred_hash_info);
            return 1;
        }
    }
    return 0;
}

static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
    [TCA_MIRRED_PARMS]  = { .len = sizeof(struct tc_mirred) },
};

static int tcf_mirred_init(struct nlattr *nla, struct nlattr *est,
               struct tc_action *a, int ovr, int bind)
{
    struct nlattr *tb[TCA_MIRRED_MAX + 1];
    struct tc_mirred *parm;
    struct tcf_mirred *m;
    struct tcf_common *pc;
    struct net_device *dev;
    int ret, ok_push = 0;

    if (nla == NULL)
        return -EINVAL;
    ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy);
    if (ret < 0)
        return ret;
    if (tb[TCA_MIRRED_PARMS] == NULL)
        return -EINVAL;
    parm = nla_data(tb[TCA_MIRRED_PARMS]);
    switch (parm->eaction) {
    case TCA_EGRESS_MIRROR:
    case TCA_EGRESS_REDIR:
        break;
    default:
        return -EINVAL;
    }
    if (parm->ifindex) {
        dev = __dev_get_by_index(&init_net, parm->ifindex);
        if (dev == NULL)
            return -ENODEV;
        switch (dev->type) {
        case ARPHRD_TUNNEL:
        case ARPHRD_TUNNEL6:
        case ARPHRD_SIT:
        case ARPHRD_IPGRE:
        case ARPHRD_VOID:
        case ARPHRD_NONE:
            ok_push = 0;
            break;
        default:
            ok_push = 1;
            break;
        }
    } else {
        dev = NULL;
    }

    pc = tcf_hash_check(parm->index, a, bind, &mirred_hash_info);
    if (!pc) {
        if (dev == NULL)
            return -EINVAL;
        pc = tcf_hash_create(parm->index, est, a, sizeof(*m), bind,
                     &mirred_idx_gen, &mirred_hash_info);
        if (IS_ERR(pc))
            return PTR_ERR(pc);
        ret = ACT_P_CREATED;
    } else {
        if (!ovr) {
            tcf_mirred_release(to_mirred(pc), bind);
            return -EEXIST;
        }
    }
    m = to_mirred(pc);

    spin_lock_bh(&m->tcf_lock);
    m->tcf_action = parm->action;
    m->tcfm_eaction = parm->eaction;
    if (dev != NULL) {
        m->tcfm_ifindex = parm->ifindex;
        if (ret != ACT_P_CREATED)
            dev_put(m->tcfm_dev);
        dev_hold(dev);
        m->tcfm_dev = dev;
        m->tcfm_ok_push = ok_push;
    }
    spin_unlock_bh(&m->tcf_lock);
    if (ret == ACT_P_CREATED) {
        list_add(&m->tcfm_list, &mirred_list);
        tcf_hash_insert(pc, &mirred_hash_info);
    }

    return ret;
}

static int tcf_mirred_cleanup(struct tc_action *a, int bind)
{
    struct tcf_mirred *m = a->priv;

    if (m)
        return tcf_mirred_release(m, bind);
    return 0;
}

static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
              struct tcf_result *res)
{
    struct tcf_mirred *m = a->priv;
    struct net_device *dev;
    struct sk_buff *skb2;
    u32 at;
    int retval, err = 1;

    spin_lock(&m->tcf_lock);
    m->tcf_tm.lastuse = jiffies;
    bstats_update(&m->tcf_bstats, skb);

    dev = m->tcfm_dev;
    if (!dev) {
        printk_once(KERN_NOTICE "tc mirred: target device is gone\n");
        goto out;
    }

    if (!(dev->flags & IFF_UP)) {
        net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
                       dev->name);
        goto out;
    }

    at = G_TC_AT(skb->tc_verd);
    skb2 = skb_act_clone(skb, GFP_ATOMIC, m->tcf_action);
    if (skb2 == NULL)
        goto out;

    if (!(at & AT_EGRESS)) {
        if (m->tcfm_ok_push)
            skb_push(skb2, skb2->dev->hard_header_len);
    }

    /* mirror is always swallowed */
    if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
        skb2->tc_verd = SET_TC_FROM(skb2->tc_verd, at);

    skb2->skb_iif = skb->dev->ifindex;
    skb2->dev = dev;
    err = dev_queue_xmit(skb2);

out:
    if (err) {
        m->tcf_qstats.overlimits++;
        if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
            retval = TC_ACT_SHOT;
        else
            retval = m->tcf_action;
    } else
        retval = m->tcf_action;
    spin_unlock(&m->tcf_lock);

    return retval;
}

static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
{
    unsigned char *b = skb_tail_pointer(skb);
    struct tcf_mirred *m = a->priv;
    struct tc_mirred opt = {
        .index   = m->tcf_index,
        .action  = m->tcf_action,
        .refcnt  = m->tcf_refcnt - ref,
        .bindcnt = m->tcf_bindcnt - bind,
        .eaction = m->tcfm_eaction,
        .ifindex = m->tcfm_ifindex,
    };
    struct tcf_t t;

    if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
        goto nla_put_failure;
    t.install = jiffies_to_clock_t(jiffies - m->tcf_tm.install);
    t.lastuse = jiffies_to_clock_t(jiffies - m->tcf_tm.lastuse);
    t.expires = jiffies_to_clock_t(m->tcf_tm.expires);
    if (nla_put(skb, TCA_MIRRED_TM, sizeof(t), &t))
        goto nla_put_failure;
    return skb->len;

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

static int mirred_device_event(struct notifier_block *unused,
                   unsigned long event, void *ptr)
{
    struct net_device *dev = ptr;
    struct tcf_mirred *m;

    if (event == NETDEV_UNREGISTER)
        list_for_each_entry(m, &mirred_list, tcfm_list) {
            if (m->tcfm_dev == dev) {
                dev_put(dev);
                m->tcfm_dev = NULL;
            }
        }

    return NOTIFY_DONE;
}

static struct notifier_block mirred_device_notifier = {
    .notifier_call = mirred_device_event,
};


static struct tc_action_ops act_mirred_ops = {
    .kind       =   "mirred",
    .hinfo      =   &mirred_hash_info,
    .type       =   TCA_ACT_MIRRED,
    .capab      =   TCA_CAP_NONE,
    .owner      =   THIS_MODULE,
    .act        =   tcf_mirred,
    .dump       =   tcf_mirred_dump,
    .cleanup    =   tcf_mirred_cleanup,
    .lookup     =   tcf_hash_search,
    .init       =   tcf_mirred_init,
    .walk       =   tcf_generic_walker
};

MODULE_AUTHOR("Jamal Hadi Salim(2002)");
MODULE_DESCRIPTION("Device Mirror/redirect actions");
MODULE_LICENSE("GPL");

static int __init mirred_init_module(void)
{
    int err = register_netdevice_notifier(&mirred_device_notifier);
    if (err)
        return err;

    pr_info("Mirror/redirect action on\n");
    return tcf_register_action(&act_mirred_ops);
}

static void __exit mirred_cleanup_module(void)
{
    unregister_netdevice_notifier(&mirred_device_notifier);
    tcf_unregister_action(&act_mirred_ops);
}

module_init(mirred_init_module);
module_exit(mirred_cleanup_module);