1/*
2 * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9#include <linux/init.h>
10#include <linux/module.h>
11#include <linux/netdevice.h>
12#include <net/netfilter/nf_tables.h>
13#include <linux/ip.h>
14#include <linux/ipv6.h>
15#include <net/netfilter/nf_tables_ipv4.h>
16#include <net/netfilter/nf_tables_ipv6.h>
17
18static inline void
19nft_netdev_set_pktinfo_ipv4(struct nft_pktinfo *pkt,
20			    struct sk_buff *skb,
21			    const struct nf_hook_state *state)
22{
23	struct iphdr *iph, _iph;
24	u32 len, thoff;
25
26	nft_set_pktinfo(pkt, skb, state);
27
28	iph = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*iph),
29				 &_iph);
30	if (!iph)
31		return;
32
33	iph = ip_hdr(skb);
34	if (iph->ihl < 5 || iph->version != 4)
35		return;
36
37	len = ntohs(iph->tot_len);
38	thoff = iph->ihl * 4;
39	if (skb->len < len)
40		return;
41	else if (len < thoff)
42		return;
43
44	pkt->tprot = iph->protocol;
45	pkt->xt.thoff = thoff;
46	pkt->xt.fragoff = ntohs(iph->frag_off) & IP_OFFSET;
47}
48
49static inline void
50__nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
51			      struct sk_buff *skb,
52			      const struct nf_hook_state *state)
53{
54#if IS_ENABLED(CONFIG_IPV6)
55	struct ipv6hdr *ip6h, _ip6h;
56	unsigned int thoff = 0;
57	unsigned short frag_off;
58	int protohdr;
59	u32 pkt_len;
60
61	ip6h = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*ip6h),
62				  &_ip6h);
63	if (!ip6h)
64		return;
65
66	if (ip6h->version != 6)
67		return;
68
69	pkt_len = ntohs(ip6h->payload_len);
70	if (pkt_len + sizeof(*ip6h) > skb->len)
71		return;
72
73	protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, NULL);
74	if (protohdr < 0)
75                return;
76
77	pkt->tprot = protohdr;
78	pkt->xt.thoff = thoff;
79	pkt->xt.fragoff = frag_off;
80#endif
81}
82
83static inline void nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
84					       struct sk_buff *skb,
85					       const struct nf_hook_state *state)
86{
87	nft_set_pktinfo(pkt, skb, state);
88	__nft_netdev_set_pktinfo_ipv6(pkt, skb, state);
89}
90
91static unsigned int
92nft_do_chain_netdev(void *priv, struct sk_buff *skb,
93		    const struct nf_hook_state *state)
94{
95	struct nft_pktinfo pkt;
96
97	switch (skb->protocol) {
98	case htons(ETH_P_IP):
99		nft_netdev_set_pktinfo_ipv4(&pkt, skb, state);
100		break;
101	case htons(ETH_P_IPV6):
102		nft_netdev_set_pktinfo_ipv6(&pkt, skb, state);
103		break;
104	default:
105		nft_set_pktinfo(&pkt, skb, state);
106		break;
107	}
108
109	return nft_do_chain(&pkt, priv);
110}
111
112static struct nft_af_info nft_af_netdev __read_mostly = {
113	.family		= NFPROTO_NETDEV,
114	.nhooks		= NF_NETDEV_NUMHOOKS,
115	.owner		= THIS_MODULE,
116	.flags		= NFT_AF_NEEDS_DEV,
117	.nops		= 1,
118	.hooks		= {
119		[NF_NETDEV_INGRESS]	= nft_do_chain_netdev,
120	},
121};
122
123static int nf_tables_netdev_init_net(struct net *net)
124{
125	net->nft.netdev = kmalloc(sizeof(struct nft_af_info), GFP_KERNEL);
126	if (net->nft.netdev == NULL)
127		return -ENOMEM;
128
129	memcpy(net->nft.netdev, &nft_af_netdev, sizeof(nft_af_netdev));
130
131	if (nft_register_afinfo(net, net->nft.netdev) < 0)
132		goto err;
133
134	return 0;
135err:
136	kfree(net->nft.netdev);
137	return -ENOMEM;
138}
139
140static void nf_tables_netdev_exit_net(struct net *net)
141{
142	nft_unregister_afinfo(net->nft.netdev);
143	kfree(net->nft.netdev);
144}
145
146static struct pernet_operations nf_tables_netdev_net_ops = {
147	.init	= nf_tables_netdev_init_net,
148	.exit	= nf_tables_netdev_exit_net,
149};
150
151static const struct nf_chain_type nft_filter_chain_netdev = {
152	.name		= "filter",
153	.type		= NFT_CHAIN_T_DEFAULT,
154	.family		= NFPROTO_NETDEV,
155	.owner		= THIS_MODULE,
156	.hook_mask	= (1 << NF_NETDEV_INGRESS),
157};
158
159static void nft_netdev_event(unsigned long event, struct nft_af_info *afi,
160			     struct net_device *dev, struct nft_table *table,
161			     struct nft_base_chain *basechain)
162{
163	switch (event) {
164	case NETDEV_REGISTER:
165		if (strcmp(basechain->dev_name, dev->name) != 0)
166			return;
167
168		BUG_ON(!(basechain->flags & NFT_BASECHAIN_DISABLED));
169
170		dev_hold(dev);
171		basechain->ops[0].dev = dev;
172		basechain->flags &= ~NFT_BASECHAIN_DISABLED;
173		if (!(table->flags & NFT_TABLE_F_DORMANT))
174			nft_register_basechain(basechain, afi->nops);
175		break;
176	case NETDEV_UNREGISTER:
177		if (strcmp(basechain->dev_name, dev->name) != 0)
178			return;
179
180		BUG_ON(basechain->flags & NFT_BASECHAIN_DISABLED);
181
182		if (!(table->flags & NFT_TABLE_F_DORMANT))
183			nft_unregister_basechain(basechain, afi->nops);
184
185		dev_put(basechain->ops[0].dev);
186		basechain->ops[0].dev = NULL;
187		basechain->flags |= NFT_BASECHAIN_DISABLED;
188		break;
189	case NETDEV_CHANGENAME:
190		if (dev->ifindex != basechain->ops[0].dev->ifindex)
191			return;
192
193		strncpy(basechain->dev_name, dev->name, IFNAMSIZ);
194		break;
195	}
196}
197
198static int nf_tables_netdev_event(struct notifier_block *this,
199				  unsigned long event, void *ptr)
200{
201	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
202	struct nft_af_info *afi;
203	struct nft_table *table;
204	struct nft_chain *chain;
205
206	nfnl_lock(NFNL_SUBSYS_NFTABLES);
207	list_for_each_entry(afi, &dev_net(dev)->nft.af_info, list) {
208		if (afi->family != NFPROTO_NETDEV)
209			continue;
210
211		list_for_each_entry(table, &afi->tables, list) {
212			list_for_each_entry(chain, &table->chains, list) {
213				if (!(chain->flags & NFT_BASE_CHAIN))
214					continue;
215
216				nft_netdev_event(event, afi, dev, table,
217						 nft_base_chain(chain));
218			}
219		}
220	}
221	nfnl_unlock(NFNL_SUBSYS_NFTABLES);
222
223	return NOTIFY_DONE;
224}
225
226static struct notifier_block nf_tables_netdev_notifier = {
227	.notifier_call	= nf_tables_netdev_event,
228};
229
230static int __init nf_tables_netdev_init(void)
231{
232	int ret;
233
234	nft_register_chain_type(&nft_filter_chain_netdev);
235	ret = register_pernet_subsys(&nf_tables_netdev_net_ops);
236	if (ret < 0)
237		nft_unregister_chain_type(&nft_filter_chain_netdev);
238
239	register_netdevice_notifier(&nf_tables_netdev_notifier);
240
241	return ret;
242}
243
244static void __exit nf_tables_netdev_exit(void)
245{
246	unregister_netdevice_notifier(&nf_tables_netdev_notifier);
247	unregister_pernet_subsys(&nf_tables_netdev_net_ops);
248	nft_unregister_chain_type(&nft_filter_chain_netdev);
249}
250
251module_init(nf_tables_netdev_init);
252module_exit(nf_tables_netdev_exit);
253
254MODULE_LICENSE("GPL");
255MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
256MODULE_ALIAS_NFT_FAMILY(5); /* NFPROTO_NETDEV */
257