nf_conntrack_timestamp.c

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/*
 * (C) 2010 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 (or any later at your option).
 */

#include <linux/netfilter.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/moduleparam.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_extend.h>
#include <net/netfilter/nf_conntrack_timestamp.h>

static bool nf_ct_tstamp __read_mostly;

module_param_named(tstamp, nf_ct_tstamp, bool, 0644);
MODULE_PARM_DESC(tstamp, "Enable connection tracking flow timestamping.");

#ifdef CONFIG_SYSCTL
static struct ctl_table tstamp_sysctl_table[] = {
    {
        .procname   = "nf_conntrack_timestamp",
        .data       = &init_net.ct.sysctl_tstamp,
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec,
    },
    {}
};
#endif /* CONFIG_SYSCTL */

static struct nf_ct_ext_type tstamp_extend __read_mostly = {
    .len    = sizeof(struct nf_conn_tstamp),
    .align  = __alignof__(struct nf_conn_tstamp),
    .id = NF_CT_EXT_TSTAMP,
};

#ifdef CONFIG_SYSCTL
static int nf_conntrack_tstamp_init_sysctl(struct net *net)
{
    struct ctl_table *table;

    table = kmemdup(tstamp_sysctl_table, sizeof(tstamp_sysctl_table),
            GFP_KERNEL);
    if (!table)
        goto out;

    table[0].data = &net->ct.sysctl_tstamp;

    net->ct.tstamp_sysctl_header = register_net_sysctl(net, "net/netfilter",
                               table);
    if (!net->ct.tstamp_sysctl_header) {
        printk(KERN_ERR "nf_ct_tstamp: can't register to sysctl.\n");
        goto out_register;
    }
    return 0;

out_register:
    kfree(table);
out:
    return -ENOMEM;
}

static void nf_conntrack_tstamp_fini_sysctl(struct net *net)
{
    struct ctl_table *table;

    table = net->ct.tstamp_sysctl_header->ctl_table_arg;
    unregister_net_sysctl_table(net->ct.tstamp_sysctl_header);
    kfree(table);
}
#else
static int nf_conntrack_tstamp_init_sysctl(struct net *net)
{
    return 0;
}

static void nf_conntrack_tstamp_fini_sysctl(struct net *net)
{
}
#endif

int nf_conntrack_tstamp_init(struct net *net)
{
    int ret;

    net->ct.sysctl_tstamp = nf_ct_tstamp;

    if (net_eq(net, &init_net)) {
        ret = nf_ct_extend_register(&tstamp_extend);
        if (ret < 0) {
            printk(KERN_ERR "nf_ct_tstamp: Unable to register "
                    "extension\n");
            goto out_extend_register;
        }
    }

    ret = nf_conntrack_tstamp_init_sysctl(net);
    if (ret < 0)
        goto out_sysctl;

    return 0;

out_sysctl:
    if (net_eq(net, &init_net))
        nf_ct_extend_unregister(&tstamp_extend);
out_extend_register:
    return ret;
}

void nf_conntrack_tstamp_fini(struct net *net)
{
    nf_conntrack_tstamp_fini_sysctl(net);
    if (net_eq(net, &init_net))
        nf_ct_extend_unregister(&tstamp_extend);
}