root/net/ipv4/netfilter/iptable_raw.c

DEFINITIONS

1. ipt_hook
2. ipt_local_hook
3. iptable_raw_net_init
4. iptable_raw_net_exit
5. iptable_raw_init
6. iptable_raw_fini

/*
 * 'raw' table, which is the very first hooked in at PRE_ROUTING and LOCAL_OUT .
 *
 * Copyright (C) 2003 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
 */
#include <linux/module.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <net/ip.h>

#define RAW_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT))

static struct
{
        struct ipt_replace repl;
        struct ipt_standard entries[2];
        struct ipt_error term;
} initial_table __net_initdata = {
        .repl = {
                .name = "raw",
                .valid_hooks = RAW_VALID_HOOKS,
                .num_entries = 3,
                .size = sizeof(struct ipt_standard) * 2 + sizeof(struct ipt_error),
                .hook_entry = {
                        [NF_INET_PRE_ROUTING] = 0,
                        [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard)
                },
                .underflow = {
                        [NF_INET_PRE_ROUTING] = 0,
                        [NF_INET_LOCAL_OUT]  = sizeof(struct ipt_standard)
                },
        },
        .entries = {
                IPT_STANDARD_INIT(NF_ACCEPT),   /* PRE_ROUTING */
                IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_OUT */
        },
        .term = IPT_ERROR_INIT,                 /* ERROR */
};

static struct xt_table packet_raw = {
        .name = "raw",
        .valid_hooks =  RAW_VALID_HOOKS,
        .lock = __RW_LOCK_UNLOCKED(packet_raw.lock),
        .me = THIS_MODULE,
        .af = AF_INET,
};

/* The work comes in here from netfilter.c. */
static unsigned int
ipt_hook(unsigned int hook,
         struct sk_buff *skb,
         const struct net_device *in,
         const struct net_device *out,
         int (*okfn)(struct sk_buff *))
{
        return ipt_do_table(skb, hook, in, out,
                            dev_net(in)->ipv4.iptable_raw);
}

static unsigned int
ipt_local_hook(unsigned int hook,
               struct sk_buff *skb,
               const struct net_device *in,
               const struct net_device *out,
               int (*okfn)(struct sk_buff *))
{
        /* root is playing with raw sockets. */
        if (skb->len < sizeof(struct iphdr) ||
            ip_hdrlen(skb) < sizeof(struct iphdr)) {
                if (net_ratelimit())
                        printk("iptable_raw: ignoring short SOCK_RAW "
                               "packet.\n");
                return NF_ACCEPT;
        }
        return ipt_do_table(skb, hook, in, out,
                            dev_net(out)->ipv4.iptable_raw);
}

/* 'raw' is the very first table. */
static struct nf_hook_ops ipt_ops[] __read_mostly = {
        {
                .hook = ipt_hook,
                .pf = PF_INET,
                .hooknum = NF_INET_PRE_ROUTING,
                .priority = NF_IP_PRI_RAW,
                .owner = THIS_MODULE,
        },
        {
                .hook = ipt_local_hook,
                .pf = PF_INET,
                .hooknum = NF_INET_LOCAL_OUT,
                .priority = NF_IP_PRI_RAW,
                .owner = THIS_MODULE,
        },
};

static int __net_init iptable_raw_net_init(struct net *net)
{
        /* Register table */
        net->ipv4.iptable_raw =
                ipt_register_table(net, &packet_raw, &initial_table.repl);
        if (IS_ERR(net->ipv4.iptable_raw))
                return PTR_ERR(net->ipv4.iptable_raw);
        return 0;
}

static void __net_exit iptable_raw_net_exit(struct net *net)
{
        ipt_unregister_table(net->ipv4.iptable_raw);
}

static struct pernet_operations iptable_raw_net_ops = {
        .init = iptable_raw_net_init,
        .exit = iptable_raw_net_exit,
};

static int __init iptable_raw_init(void)
{
        int ret;

        ret = register_pernet_subsys(&iptable_raw_net_ops);
        if (ret < 0)
                return ret;

        /* Register hooks */
        ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
        if (ret < 0)
                goto cleanup_table;

        return ret;

 cleanup_table:
        unregister_pernet_subsys(&iptable_raw_net_ops);
        return ret;
}

static void __exit iptable_raw_fini(void)
{
        nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
        unregister_pernet_subsys(&iptable_raw_net_ops);
}

module_init(iptable_raw_init);
module_exit(iptable_raw_fini);
MODULE_LICENSE("GPL");