xt_devgroup.c

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/*
 * Copyright (c) 2011 Patrick McHardy <[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/netdevice.h>

#include <linux/netfilter/xt_devgroup.h>
#include <linux/netfilter/x_tables.h>

MODULE_AUTHOR("Patrick McHardy <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Xtables: Device group match");
MODULE_ALIAS("ipt_devgroup");
MODULE_ALIAS("ip6t_devgroup");

static bool devgroup_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
    const struct xt_devgroup_info *info = par->matchinfo;

    if (info->flags & XT_DEVGROUP_MATCH_SRC &&
        (((info->src_group ^ par->in->group) & info->src_mask ? 1 : 0) ^
         ((info->flags & XT_DEVGROUP_INVERT_SRC) ? 1 : 0)))
        return false;

    if (info->flags & XT_DEVGROUP_MATCH_DST &&
        (((info->dst_group ^ par->out->group) & info->dst_mask ? 1 : 0) ^
         ((info->flags & XT_DEVGROUP_INVERT_DST) ? 1 : 0)))
        return false;

    return true;
}

static int devgroup_mt_checkentry(const struct xt_mtchk_param *par)
{
    const struct xt_devgroup_info *info = par->matchinfo;

    if (info->flags & ~(XT_DEVGROUP_MATCH_SRC | XT_DEVGROUP_INVERT_SRC |
                XT_DEVGROUP_MATCH_DST | XT_DEVGROUP_INVERT_DST))
        return -EINVAL;

    if (info->flags & XT_DEVGROUP_MATCH_SRC &&
        par->hook_mask & ~((1 << NF_INET_PRE_ROUTING) |
                   (1 << NF_INET_LOCAL_IN) |
                   (1 << NF_INET_FORWARD)))
        return -EINVAL;

    if (info->flags & XT_DEVGROUP_MATCH_DST &&
        par->hook_mask & ~((1 << NF_INET_FORWARD) |
                   (1 << NF_INET_LOCAL_OUT) |
                   (1 << NF_INET_POST_ROUTING)))
        return -EINVAL;

    return 0;
}

static struct xt_match devgroup_mt_reg __read_mostly = {
    .name       = "devgroup",
    .match      = devgroup_mt,
    .checkentry = devgroup_mt_checkentry,
    .matchsize  = sizeof(struct xt_devgroup_info),
    .family     = NFPROTO_UNSPEC,
    .me     = THIS_MODULE
};

static int __init devgroup_mt_init(void)
{
    return xt_register_match(&devgroup_mt_reg);
}

static void __exit devgroup_mt_exit(void)
{
    xt_unregister_match(&devgroup_mt_reg);
}

module_init(devgroup_mt_init);
module_exit(devgroup_mt_exit);