1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *	"TEE" target extension for Xtables
4 *	Copyright �� Sebastian Cla��en, 2007
5 *	Jan Engelhardt, 2007-2010
6 *
7 *	based on ipt_ROUTE.c from C��dric de Launois
8 *	<delaunois@info.ucl.be>
9 */
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/route.h>
13#include <linux/netfilter/x_tables.h>
14#include <net/net_namespace.h>
15#include <net/netns/generic.h>
16#include <net/route.h>
17#include <net/netfilter/ipv4/nf_dup_ipv4.h>
18#include <net/netfilter/ipv6/nf_dup_ipv6.h>
19#include <linux/netfilter/xt_TEE.h>
20
21struct xt_tee_priv {
22	struct list_head	list;
23	struct xt_tee_tginfo	*tginfo;
24	int			oif;
25};
26
27static unsigned int tee_net_id __read_mostly;
28static const union nf_inet_addr tee_zero_address;
29
30struct tee_net {
31	struct list_head priv_list;
32	/* lock protects the priv_list */
33	struct mutex lock;
34};
35
36static unsigned int
37tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
38{
39	const struct xt_tee_tginfo *info = par->targinfo;
40	int oif = info->priv ? info->priv->oif : 0;
41
42	nf_dup_ipv4(xt_net(par), skb, xt_hooknum(par), &info->gw.in, oif);
43
44	return XT_CONTINUE;
45}
46
47#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
48static unsigned int
49tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
50{
51	const struct xt_tee_tginfo *info = par->targinfo;
52	int oif = info->priv ? info->priv->oif : 0;
53
54	nf_dup_ipv6(xt_net(par), skb, xt_hooknum(par), &info->gw.in6, oif);
55
56	return XT_CONTINUE;
57}
58#endif
59
60static int tee_netdev_event(struct notifier_block *this, unsigned long event,
61			    void *ptr)
62{
63	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
64	struct net *net = dev_net(dev);
65	struct tee_net *tn = net_generic(net, tee_net_id);
66	struct xt_tee_priv *priv;
67
68	mutex_lock(&tn->lock);
69	list_for_each_entry(priv, &tn->priv_list, list) {
70		switch (event) {
71		case NETDEV_REGISTER:
72			if (!strcmp(dev->name, priv->tginfo->oif))
73				priv->oif = dev->ifindex;
74			break;
75		case NETDEV_UNREGISTER:
76			if (dev->ifindex == priv->oif)
77				priv->oif = -1;
78			break;
79		case NETDEV_CHANGENAME:
80			if (!strcmp(dev->name, priv->tginfo->oif))
81				priv->oif = dev->ifindex;
82			else if (dev->ifindex == priv->oif)
83				priv->oif = -1;
84			break;
85		}
86	}
87	mutex_unlock(&tn->lock);
88
89	return NOTIFY_DONE;
90}
91
92static int tee_tg_check(const struct xt_tgchk_param *par)
93{
94	struct tee_net *tn = net_generic(par->net, tee_net_id);
95	struct xt_tee_tginfo *info = par->targinfo;
96	struct xt_tee_priv *priv;
97
98	/* 0.0.0.0 and :: not allowed */
99	if (memcmp(&info->gw, &tee_zero_address,
100		   sizeof(tee_zero_address)) == 0)
101		return -EINVAL;
102
103	if (info->oif[0]) {
104		struct net_device *dev;
105
106		if (info->oif[sizeof(info->oif)-1] != '\0')
107			return -EINVAL;
108
109		priv = kzalloc(sizeof(*priv), GFP_KERNEL);
110		if (priv == NULL)
111			return -ENOMEM;
112
113		priv->tginfo  = info;
114		priv->oif     = -1;
115		info->priv    = priv;
116
117		dev = dev_get_by_name(par->net, info->oif);
118		if (dev) {
119			priv->oif = dev->ifindex;
120			dev_put(dev);
121		}
122		mutex_lock(&tn->lock);
123		list_add(&priv->list, &tn->priv_list);
124		mutex_unlock(&tn->lock);
125	} else
126		info->priv = NULL;
127
128	static_key_slow_inc(&xt_tee_enabled);
129	return 0;
130}
131
132static void tee_tg_destroy(const struct xt_tgdtor_param *par)
133{
134	struct tee_net *tn = net_generic(par->net, tee_net_id);
135	struct xt_tee_tginfo *info = par->targinfo;
136
137	if (info->priv) {
138		mutex_lock(&tn->lock);
139		list_del(&info->priv->list);
140		mutex_unlock(&tn->lock);
141		kfree(info->priv);
142	}
143	static_key_slow_dec(&xt_tee_enabled);
144}
145
146static struct xt_target tee_tg_reg[] __read_mostly = {
147	{
148		.name       = "TEE",
149		.revision   = 1,
150		.family     = NFPROTO_IPV4,
151		.target     = tee_tg4,
152		.targetsize = sizeof(struct xt_tee_tginfo),
153		.usersize   = offsetof(struct xt_tee_tginfo, priv),
154		.checkentry = tee_tg_check,
155		.destroy    = tee_tg_destroy,
156		.me         = THIS_MODULE,
157	},
158#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
159	{
160		.name       = "TEE",
161		.revision   = 1,
162		.family     = NFPROTO_IPV6,
163		.target     = tee_tg6,
164		.targetsize = sizeof(struct xt_tee_tginfo),
165		.usersize   = offsetof(struct xt_tee_tginfo, priv),
166		.checkentry = tee_tg_check,
167		.destroy    = tee_tg_destroy,
168		.me         = THIS_MODULE,
169	},
170#endif
171};
172
173static int __net_init tee_net_init(struct net *net)
174{
175	struct tee_net *tn = net_generic(net, tee_net_id);
176
177	INIT_LIST_HEAD(&tn->priv_list);
178	mutex_init(&tn->lock);
179	return 0;
180}
181
182static struct pernet_operations tee_net_ops = {
183	.init = tee_net_init,
184	.id   = &tee_net_id,
185	.size = sizeof(struct tee_net),
186};
187
188static struct notifier_block tee_netdev_notifier = {
189	.notifier_call = tee_netdev_event,
190};
191
192static int __init tee_tg_init(void)
193{
194	int ret;
195
196	ret = register_pernet_subsys(&tee_net_ops);
197	if (ret < 0)
198		return ret;
199
200	ret = xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
201	if (ret < 0)
202		goto cleanup_subsys;
203
204	ret = register_netdevice_notifier(&tee_netdev_notifier);
205	if (ret < 0)
206		goto unregister_targets;
207
208	return 0;
209
210unregister_targets:
211	xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
212cleanup_subsys:
213	unregister_pernet_subsys(&tee_net_ops);
214	return ret;
215}
216
217static void __exit tee_tg_exit(void)
218{
219	unregister_netdevice_notifier(&tee_netdev_notifier);
220	xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
221	unregister_pernet_subsys(&tee_net_ops);
222}
223
224module_init(tee_tg_init);
225module_exit(tee_tg_exit);
226MODULE_AUTHOR("Sebastian Cla��en <sebastian.classen@freenet.ag>");
227MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
228MODULE_DESCRIPTION("Xtables: Reroute packet copy");
229MODULE_LICENSE("GPL");
230MODULE_ALIAS("ipt_TEE");
231MODULE_ALIAS("ip6t_TEE");
232