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 
18 static inline void
nft_netdev_set_pktinfo_ipv4(struct nft_pktinfo * pkt,struct sk_buff * skb,const struct nf_hook_state * state)19 nft_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 
49 static inline void
__nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo * pkt,struct sk_buff * skb,const struct nf_hook_state * state)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 
nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo * pkt,struct sk_buff * skb,const struct nf_hook_state * state)83 static 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 
91 static unsigned int
nft_do_chain_netdev(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)92 nft_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 
112 static 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 
nf_tables_netdev_init_net(struct net * net)123 static 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;
135 err:
136 	kfree(net->nft.netdev);
137 	return -ENOMEM;
138 }
139 
nf_tables_netdev_exit_net(struct net * net)140 static void nf_tables_netdev_exit_net(struct net *net)
141 {
142 	nft_unregister_afinfo(net->nft.netdev);
143 	kfree(net->nft.netdev);
144 }
145 
146 static struct pernet_operations nf_tables_netdev_net_ops = {
147 	.init	= nf_tables_netdev_init_net,
148 	.exit	= nf_tables_netdev_exit_net,
149 };
150 
151 static 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 
nft_netdev_event(unsigned long event,struct nft_af_info * afi,struct net_device * dev,struct nft_table * table,struct nft_base_chain * basechain)159 static 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 
nf_tables_netdev_event(struct notifier_block * this,unsigned long event,void * ptr)198 static 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 
226 static struct notifier_block nf_tables_netdev_notifier = {
227 	.notifier_call	= nf_tables_netdev_event,
228 };
229 
nf_tables_netdev_init(void)230 static 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 
nf_tables_netdev_exit(void)244 static 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 
251 module_init(nf_tables_netdev_init);
252 module_exit(nf_tables_netdev_exit);
253 
254 MODULE_LICENSE("GPL");
255 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
256 MODULE_ALIAS_NFT_FAMILY(5); /* NFPROTO_NETDEV */
257