nft_chain_route_ipv4.c revision 9370761c56b66aa5c65e069a7b010111a025018d 
1/*
2 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
3 * Copyright (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/list.h>
13#include <linux/skbuff.h>
14#include <linux/netlink.h>
15#include <linux/netfilter.h>
16#include <linux/netfilter_ipv4.h>
17#include <linux/netfilter/nfnetlink.h>
18#include <linux/netfilter/nf_tables.h>
19#include <net/netfilter/nf_tables.h>
20#include <net/route.h>
21#include <net/ip.h>
22
23static unsigned int nf_route_table_hook(const struct nf_hook_ops *ops,
24					struct sk_buff *skb,
25					const struct net_device *in,
26					const struct net_device *out,
27					int (*okfn)(struct sk_buff *))
28{
29	unsigned int ret;
30	u32 mark;
31	__be32 saddr, daddr;
32	u_int8_t tos;
33	const struct iphdr *iph;
34
35	/* root is playing with raw sockets. */
36	if (skb->len < sizeof(struct iphdr) ||
37	    ip_hdrlen(skb) < sizeof(struct iphdr))
38		return NF_ACCEPT;
39
40	mark = skb->mark;
41	iph = ip_hdr(skb);
42	saddr = iph->saddr;
43	daddr = iph->daddr;
44	tos = iph->tos;
45
46	ret = nft_do_chain(ops, skb, in, out, okfn);
47	if (ret != NF_DROP && ret != NF_QUEUE) {
48		iph = ip_hdr(skb);
49
50		if (iph->saddr != saddr ||
51		    iph->daddr != daddr ||
52		    skb->mark != mark ||
53		    iph->tos != tos)
54			if (ip_route_me_harder(skb, RTN_UNSPEC))
55				ret = NF_DROP;
56	}
57	return ret;
58}
59
60static struct nf_chain_type nft_chain_route_ipv4 = {
61	.family		= NFPROTO_IPV4,
62	.name		= "route",
63	.type		= NFT_CHAIN_T_ROUTE,
64	.hook_mask	= (1 << NF_INET_LOCAL_OUT),
65	.fn		= {
66		[NF_INET_LOCAL_OUT]	= nf_route_table_hook,
67	},
68	.me		= THIS_MODULE,
69};
70
71static int __init nft_chain_route_init(void)
72{
73	return nft_register_chain_type(&nft_chain_route_ipv4);
74}
75
76static void __exit nft_chain_route_exit(void)
77{
78	nft_unregister_chain_type(&nft_chain_route_ipv4);
79}
80
81module_init(nft_chain_route_init);
82module_exit(nft_chain_route_exit);
83
84MODULE_LICENSE("GPL");
85MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
86MODULE_ALIAS_NFT_CHAIN(AF_INET, "route");
87