xt_NFQUEUE.c

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/* iptables module for using new netfilter netlink queue
 *
 * (C) 2005 by Harald Welte <[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/module.h>
#include <linux/skbuff.h>

#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/jhash.h>

#include <linux/netfilter.h>
#include <linux/netfilter_arp.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_NFQUEUE.h>

MODULE_AUTHOR("Harald Welte <[email protected]>");
MODULE_DESCRIPTION("Xtables: packet forwarding to netlink");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_NFQUEUE");
MODULE_ALIAS("ip6t_NFQUEUE");
MODULE_ALIAS("arpt_NFQUEUE");

static u32 jhash_initval __read_mostly;
static bool rnd_inited __read_mostly;

static unsigned int
nfqueue_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
    const struct xt_NFQ_info *tinfo = par->targinfo;

    return NF_QUEUE_NR(tinfo->queuenum);
}

static u32 hash_v4(const struct sk_buff *skb)
{
    const struct iphdr *iph = ip_hdr(skb);

    /* packets in either direction go into same queue */
    if ((__force u32)iph->saddr < (__force u32)iph->daddr)
        return jhash_3words((__force u32)iph->saddr,
            (__force u32)iph->daddr, iph->protocol, jhash_initval);

    return jhash_3words((__force u32)iph->daddr,
            (__force u32)iph->saddr, iph->protocol, jhash_initval);
}

#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
static u32 hash_v6(const struct sk_buff *skb)
{
    const struct ipv6hdr *ip6h = ipv6_hdr(skb);
    u32 a, b, c;

    if ((__force u32)ip6h->saddr.s6_addr32[3] <
        (__force u32)ip6h->daddr.s6_addr32[3]) {
        a = (__force u32) ip6h->saddr.s6_addr32[3];
        b = (__force u32) ip6h->daddr.s6_addr32[3];
    } else {
        b = (__force u32) ip6h->saddr.s6_addr32[3];
        a = (__force u32) ip6h->daddr.s6_addr32[3];
    }

    if ((__force u32)ip6h->saddr.s6_addr32[1] <
        (__force u32)ip6h->daddr.s6_addr32[1])
        c = (__force u32) ip6h->saddr.s6_addr32[1];
    else
        c = (__force u32) ip6h->daddr.s6_addr32[1];

    return jhash_3words(a, b, c, jhash_initval);
}
#endif

static unsigned int
nfqueue_tg_v1(struct sk_buff *skb, const struct xt_action_param *par)
{
    const struct xt_NFQ_info_v1 *info = par->targinfo;
    u32 queue = info->queuenum;

    if (info->queues_total > 1) {
        if (par->family == NFPROTO_IPV4)
            queue = (((u64) hash_v4(skb) * info->queues_total) >>
                 32) + queue;
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
        else if (par->family == NFPROTO_IPV6)
            queue = (((u64) hash_v6(skb) * info->queues_total) >>
                 32) + queue;
#endif
    }
    return NF_QUEUE_NR(queue);
}

static unsigned int
nfqueue_tg_v2(struct sk_buff *skb, const struct xt_action_param *par)
{
    const struct xt_NFQ_info_v2 *info = par->targinfo;
    unsigned int ret = nfqueue_tg_v1(skb, par);

    if (info->bypass)
        ret |= NF_VERDICT_FLAG_QUEUE_BYPASS;
    return ret;
}

static int nfqueue_tg_check(const struct xt_tgchk_param *par)
{
    const struct xt_NFQ_info_v2 *info = par->targinfo;
    u32 maxid;

    if (unlikely(!rnd_inited)) {
        get_random_bytes(&jhash_initval, sizeof(jhash_initval));
        rnd_inited = true;
    }
    if (info->queues_total == 0) {
        pr_err("NFQUEUE: number of total queues is 0\n");
        return -EINVAL;
    }
    maxid = info->queues_total - 1 + info->queuenum;
    if (maxid > 0xffff) {
        pr_err("NFQUEUE: number of queues (%u) out of range (got %u)\n",
               info->queues_total, maxid);
        return -ERANGE;
    }
    if (par->target->revision == 2 && info->bypass > 1)
        return -EINVAL;
    return 0;
}

static struct xt_target nfqueue_tg_reg[] __read_mostly = {
    {
        .name       = "NFQUEUE",
        .family     = NFPROTO_UNSPEC,
        .target     = nfqueue_tg,
        .targetsize = sizeof(struct xt_NFQ_info),
        .me     = THIS_MODULE,
    },
    {
        .name       = "NFQUEUE",
        .revision   = 1,
        .family     = NFPROTO_UNSPEC,
        .checkentry = nfqueue_tg_check,
        .target     = nfqueue_tg_v1,
        .targetsize = sizeof(struct xt_NFQ_info_v1),
        .me     = THIS_MODULE,
    },
    {
        .name       = "NFQUEUE",
        .revision   = 2,
        .family     = NFPROTO_UNSPEC,
        .checkentry = nfqueue_tg_check,
        .target     = nfqueue_tg_v2,
        .targetsize = sizeof(struct xt_NFQ_info_v2),
        .me     = THIS_MODULE,
    },
};

static int __init nfqueue_tg_init(void)
{
    return xt_register_targets(nfqueue_tg_reg, ARRAY_SIZE(nfqueue_tg_reg));
}

static void __exit nfqueue_tg_exit(void)
{
    xt_unregister_targets(nfqueue_tg_reg, ARRAY_SIZE(nfqueue_tg_reg));
}

module_init(nfqueue_tg_init);
module_exit(nfqueue_tg_exit);