root/net/ipv4/netfilter/nf_defrag_ipv4.c

DEFINITIONS

1. nf_ct_ipv4_gather_frags
2. ipv4_conntrack_defrag
3. nf_defrag_init
4. nf_defrag_fini
5. nf_defrag_ipv4_enable

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 *
 * 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/types.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/route.h>
#include <net/ip.h>

#include <linux/netfilter_ipv4.h>
#include <net/netfilter/ipv4/nf_defrag_ipv4.h>

/* Returns new sk_buff, or NULL */
static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
{
        int err;

        skb_orphan(skb);

        local_bh_disable();
        err = ip_defrag(skb, user);
        local_bh_enable();

        if (!err)
                ip_send_check(ip_hdr(skb));

        return err;
}

static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
                                          struct sk_buff *skb,
                                          const struct net_device *in,
                                          const struct net_device *out,
                                          int (*okfn)(struct sk_buff *))
{
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
        /* Previously seen (loopback)?  Ignore.  Do this before
           fragment check. */
        if (skb->nfct)
                return NF_ACCEPT;
#endif

        /* Gather fragments. */
        if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
                if (nf_ct_ipv4_gather_frags(skb,
                                            hooknum == NF_INET_PRE_ROUTING ?
                                            IP_DEFRAG_CONNTRACK_IN :
                                            IP_DEFRAG_CONNTRACK_OUT))
                        return NF_STOLEN;
        }
        return NF_ACCEPT;
}

static struct nf_hook_ops ipv4_defrag_ops[] = {
        {
                .hook           = ipv4_conntrack_defrag,
                .owner          = THIS_MODULE,
                .pf             = PF_INET,
                .hooknum        = NF_INET_PRE_ROUTING,
                .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
        },
        {
                .hook           = ipv4_conntrack_defrag,
                .owner          = THIS_MODULE,
                .pf             = PF_INET,
                .hooknum        = NF_INET_LOCAL_OUT,
                .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
        },
};

static int __init nf_defrag_init(void)
{
        return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
}

static void __exit nf_defrag_fini(void)
{
        nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
}

void nf_defrag_ipv4_enable(void)
{
}
EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);

module_init(nf_defrag_init);
module_exit(nf_defrag_fini);

MODULE_LICENSE("GPL");