blob: 1d16c0f28df00d17c38a52bfeff23c0a1bca0142 [file] [log] [blame]
/*
* This is a module which is used for rejecting packets.
*/
/* (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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/icmp.h>
#include <net/icmp.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_REJECT.h>
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
#include <linux/netfilter_bridge.h>
#endif
#include <net/netfilter/ipv4/nf_reject.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv4");
static unsigned int
reject_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct ipt_reject_info *reject = par->targinfo;
int hook = par->hooknum;
switch (reject->with) {
case IPT_ICMP_NET_UNREACHABLE:
nf_send_unreach(skb, ICMP_NET_UNREACH, hook);
break;
case IPT_ICMP_HOST_UNREACHABLE:
nf_send_unreach(skb, ICMP_HOST_UNREACH, hook);
break;
case IPT_ICMP_PROT_UNREACHABLE:
nf_send_unreach(skb, ICMP_PROT_UNREACH, hook);
break;
case IPT_ICMP_PORT_UNREACHABLE:
nf_send_unreach(skb, ICMP_PORT_UNREACH, hook);
break;
case IPT_ICMP_NET_PROHIBITED:
nf_send_unreach(skb, ICMP_NET_ANO, hook);
break;
case IPT_ICMP_HOST_PROHIBITED:
nf_send_unreach(skb, ICMP_HOST_ANO, hook);
break;
case IPT_ICMP_ADMIN_PROHIBITED:
nf_send_unreach(skb, ICMP_PKT_FILTERED, hook);
break;
case IPT_TCP_RESET:
nf_send_reset(par->net, skb, hook);
case IPT_ICMP_ECHOREPLY:
/* Doesn't happen. */
break;
}
return NF_DROP;
}
static int reject_tg_check(const struct xt_tgchk_param *par)
{
const struct ipt_reject_info *rejinfo = par->targinfo;
const struct ipt_entry *e = par->entryinfo;
if (rejinfo->with == IPT_ICMP_ECHOREPLY) {
pr_info("ECHOREPLY no longer supported.\n");
return -EINVAL;
} else if (rejinfo->with == IPT_TCP_RESET) {
/* Must specify that it's a TCP packet */
if (e->ip.proto != IPPROTO_TCP ||
(e->ip.invflags & XT_INV_PROTO)) {
pr_info("TCP_RESET invalid for non-tcp\n");
return -EINVAL;
}
}
return 0;
}
static struct xt_target reject_tg_reg __read_mostly = {
.name = "REJECT",
.family = NFPROTO_IPV4,
.target = reject_tg,
.targetsize = sizeof(struct ipt_reject_info),
.table = "filter",
.hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) |
(1 << NF_INET_LOCAL_OUT),
.checkentry = reject_tg_check,
.me = THIS_MODULE,
};
static int __init reject_tg_init(void)
{
return xt_register_target(&reject_tg_reg);
}
static void __exit reject_tg_exit(void)
{
xt_unregister_target(&reject_tg_reg);
}
module_init(reject_tg_init);
module_exit(reject_tg_exit);