root/net/netfilter/xt_CONNSECMARK.c

DEFINITIONS

1. secmark_save
2. secmark_restore
3. connsecmark_tg
4. connsecmark_tg_check
5. connsecmark_tg_destroy
6. connsecmark_tg_init
7. connsecmark_tg_exit

/*
 * This module is used to copy security markings from packets
 * to connections, and restore security markings from connections
 * back to packets.  This would normally be performed in conjunction
 * with the SECMARK target and state match.
 *
 * Based somewhat on CONNMARK:
 *   Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
 *    by Henrik Nordstrom <hno@marasystems.com>
 *
 * (C) 2006,2008 Red Hat, Inc., James Morris <jmorris@redhat.com>
 *
 * 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/netfilter/x_tables.h>
#include <linux/netfilter/xt_CONNSECMARK.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_ecache.h>

#define PFX "CONNSECMARK: "

MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
MODULE_DESCRIPTION("Xtables: target for copying between connection and security mark");
MODULE_ALIAS("ipt_CONNSECMARK");
MODULE_ALIAS("ip6t_CONNSECMARK");

/*
 * If the packet has a security mark and the connection does not, copy
 * the security mark from the packet to the connection.
 */
static void secmark_save(const struct sk_buff *skb)
{
        if (skb->secmark) {
                struct nf_conn *ct;
                enum ip_conntrack_info ctinfo;

                ct = nf_ct_get(skb, &ctinfo);
                if (ct && !ct->secmark) {
                        ct->secmark = skb->secmark;
                        nf_conntrack_event_cache(IPCT_SECMARK, ct);
                }
        }
}

/*
 * If packet has no security mark, and the connection does, restore the
 * security mark from the connection to the packet.
 */
static void secmark_restore(struct sk_buff *skb)
{
        if (!skb->secmark) {
                const struct nf_conn *ct;
                enum ip_conntrack_info ctinfo;

                ct = nf_ct_get(skb, &ctinfo);
                if (ct && ct->secmark)
                        skb->secmark = ct->secmark;
        }
}

static unsigned int
connsecmark_tg(struct sk_buff *skb, const struct xt_target_param *par)
{
        const struct xt_connsecmark_target_info *info = par->targinfo;

        switch (info->mode) {
        case CONNSECMARK_SAVE:
                secmark_save(skb);
                break;

        case CONNSECMARK_RESTORE:
                secmark_restore(skb);
                break;

        default:
                BUG();
        }

        return XT_CONTINUE;
}

static bool connsecmark_tg_check(const struct xt_tgchk_param *par)
{
        const struct xt_connsecmark_target_info *info = par->targinfo;

        if (strcmp(par->table, "mangle") != 0 &&
            strcmp(par->table, "security") != 0) {
                printk(KERN_INFO PFX "target only valid in the \'mangle\' "
                       "or \'security\' tables, not \'%s\'.\n", par->table);
                return false;
        }

        switch (info->mode) {
        case CONNSECMARK_SAVE:
        case CONNSECMARK_RESTORE:
                break;

        default:
                printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
                return false;
        }

        if (nf_ct_l3proto_try_module_get(par->family) < 0) {
                printk(KERN_WARNING "can't load conntrack support for "
                                    "proto=%u\n", par->family);
                return false;
        }
        return true;
}

static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
{
        nf_ct_l3proto_module_put(par->family);
}

static struct xt_target connsecmark_tg_reg __read_mostly = {
        .name       = "CONNSECMARK",
        .revision   = 0,
        .family     = NFPROTO_UNSPEC,
        .checkentry = connsecmark_tg_check,
        .destroy    = connsecmark_tg_destroy,
        .target     = connsecmark_tg,
        .targetsize = sizeof(struct xt_connsecmark_target_info),
        .me         = THIS_MODULE,
};

static int __init connsecmark_tg_init(void)
{
        return xt_register_target(&connsecmark_tg_reg);
}

static void __exit connsecmark_tg_exit(void)
{
        xt_unregister_target(&connsecmark_tg_reg);
}

module_init(connsecmark_tg_init);
module_exit(connsecmark_tg_exit);