Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

Open Menu /net/ipv4/netfilter/ipt_REJECT.c 
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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>
 */
#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 = xt_hooknum(par);

	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(xt_net(par), 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_ratelimited("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_ratelimited("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);