em_ipset.c

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/*
 * net/sched/em_ipset.c ipset ematch
 *
 * Copyright (c) 2012 Florian Westphal <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 */

#include <linux/gfp.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/netfilter/xt_set.h>
#include <linux/ipv6.h>
#include <net/ip.h>
#include <net/pkt_cls.h>

static int em_ipset_change(struct tcf_proto *tp, void *data, int data_len,
               struct tcf_ematch *em)
{
    struct xt_set_info *set = data;
    ip_set_id_t index;

    if (data_len != sizeof(*set))
        return -EINVAL;

    index = ip_set_nfnl_get_byindex(set->index);
    if (index == IPSET_INVALID_ID)
        return -ENOENT;

    em->datalen = sizeof(*set);
    em->data = (unsigned long)kmemdup(data, em->datalen, GFP_KERNEL);
    if (em->data)
        return 0;

    ip_set_nfnl_put(index);
    return -ENOMEM;
}

static void em_ipset_destroy(struct tcf_proto *p, struct tcf_ematch *em)
{
    const struct xt_set_info *set = (const void *) em->data;
    if (set) {
        ip_set_nfnl_put(set->index);
        kfree((void *) em->data);
    }
}

static int em_ipset_match(struct sk_buff *skb, struct tcf_ematch *em,
              struct tcf_pkt_info *info)
{
    struct ip_set_adt_opt opt;
    struct xt_action_param acpar;
    const struct xt_set_info *set = (const void *) em->data;
    struct net_device *dev, *indev = NULL;
    int ret, network_offset;

    switch (skb->protocol) {
    case htons(ETH_P_IP):
        acpar.family = NFPROTO_IPV4;
        if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
            return 0;
        acpar.thoff = ip_hdrlen(skb);
        break;
    case htons(ETH_P_IPV6):
        acpar.family = NFPROTO_IPV6;
        if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
            return 0;
        /* doesn't call ipv6_find_hdr() because ipset doesn't use thoff, yet */
        acpar.thoff = sizeof(struct ipv6hdr);
        break;
    default:
        return 0;
    }

    acpar.hooknum = 0;

    opt.family = acpar.family;
    opt.dim = set->dim;
    opt.flags = set->flags;
    opt.cmdflags = 0;
    opt.timeout = ~0u;

    network_offset = skb_network_offset(skb);
    skb_pull(skb, network_offset);

    dev = skb->dev;

    rcu_read_lock();

    if (dev && skb->skb_iif)
        indev = dev_get_by_index_rcu(dev_net(dev), skb->skb_iif);

    acpar.in      = indev ? indev : dev;
    acpar.out     = dev;

    ret = ip_set_test(set->index, skb, &acpar, &opt);

    rcu_read_unlock();

    skb_push(skb, network_offset);
    return ret;
}

static struct tcf_ematch_ops em_ipset_ops = {
    .kind     = TCF_EM_IPSET,
    .change   = em_ipset_change,
    .destroy  = em_ipset_destroy,
    .match    = em_ipset_match,
    .owner    = THIS_MODULE,
    .link     = LIST_HEAD_INIT(em_ipset_ops.link)
};

static int __init init_em_ipset(void)
{
    return tcf_em_register(&em_ipset_ops);
}

static void __exit exit_em_ipset(void)
{
    tcf_em_unregister(&em_ipset_ops);
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Florian Westphal <[email protected]>");
MODULE_DESCRIPTION("TC extended match for IP sets");

module_init(init_em_ipset);
module_exit(exit_em_ipset);

MODULE_ALIAS_TCF_EMATCH(TCF_EM_IPSET);