nfnetlink_queue_ct.c

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/*
 * (C) 2012 by Pablo Neira Ayuso <[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/skbuff.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_queue.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nfnetlink_queue.h>

struct nf_conn *nfqnl_ct_get(struct sk_buff *entskb, size_t *size,
                 enum ip_conntrack_info *ctinfo)
{
    struct nfq_ct_hook *nfq_ct;
    struct nf_conn *ct;

    /* rcu_read_lock()ed by __nf_queue already. */
    nfq_ct = rcu_dereference(nfq_ct_hook);
    if (nfq_ct == NULL)
        return NULL;

    ct = nf_ct_get(entskb, ctinfo);
    if (ct) {
        if (!nf_ct_is_untracked(ct))
            *size += nfq_ct->build_size(ct);
        else
            ct = NULL;
    }
    return ct;
}

struct nf_conn *
nfqnl_ct_parse(const struct sk_buff *skb, const struct nlattr *attr,
           enum ip_conntrack_info *ctinfo)
{
    struct nfq_ct_hook *nfq_ct;
    struct nf_conn *ct;

    /* rcu_read_lock()ed by __nf_queue already. */
    nfq_ct = rcu_dereference(nfq_ct_hook);
    if (nfq_ct == NULL)
        return NULL;

    ct = nf_ct_get(skb, ctinfo);
    if (ct && !nf_ct_is_untracked(ct))
        nfq_ct->parse(attr, ct);

    return ct;
}

int nfqnl_ct_put(struct sk_buff *skb, struct nf_conn *ct,
         enum ip_conntrack_info ctinfo)
{
    struct nfq_ct_hook *nfq_ct;
    struct nlattr *nest_parms;
    u_int32_t tmp;

    nfq_ct = rcu_dereference(nfq_ct_hook);
    if (nfq_ct == NULL)
        return 0;

    nest_parms = nla_nest_start(skb, NFQA_CT | NLA_F_NESTED);
    if (!nest_parms)
        goto nla_put_failure;

    if (nfq_ct->build(skb, ct) < 0)
        goto nla_put_failure;

    nla_nest_end(skb, nest_parms);

    tmp = ctinfo;
    if (nla_put_be32(skb, NFQA_CT_INFO, htonl(tmp)))
        goto nla_put_failure;

    return 0;

nla_put_failure:
    return -1;
}

void nfqnl_ct_seq_adjust(struct sk_buff *skb, struct nf_conn *ct,
             enum ip_conntrack_info ctinfo, int diff)
{
    struct nfq_ct_nat_hook *nfq_nat_ct;

    nfq_nat_ct = rcu_dereference(nfq_ct_nat_hook);
    if (nfq_nat_ct == NULL)
        return;

    if ((ct->status & IPS_NAT_MASK) && diff)
        nfq_nat_ct->seq_adjust(skb, ct, ctinfo, diff);
}