1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	"TEE" target extension for Xtables
4  *	Copyright © Sebastian Claßen, 2007
5  *	Jan Engelhardt, 2007-2010
6  *
7  *	based on ipt_ROUTE.c from Cédric 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 
21 struct xt_tee_priv {
22 	struct list_head	list;
23 	struct xt_tee_tginfo	*tginfo;
24 	int			oif;
25 };
26 
27 static unsigned int tee_net_id __read_mostly;
28 static const union nf_inet_addr tee_zero_address;
29 
30 struct tee_net {
31 	struct list_head priv_list;
32 	/* lock protects the priv_list */
33 	struct mutex lock;
34 };
35 
36 static unsigned int
tee_tg4(struct sk_buff * skb,const struct xt_action_param * par)37 tee_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)
48 static unsigned int
tee_tg6(struct sk_buff * skb,const struct xt_action_param * par)49 tee_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 
tee_netdev_event(struct notifier_block * this,unsigned long event,void * ptr)60 static 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 
tee_tg_check(const struct xt_tgchk_param * par)92 static 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 
tee_tg_destroy(const struct xt_tgdtor_param * par)132 static 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 
146 static 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 
tee_net_init(struct net * net)173 static 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 
182 static struct pernet_operations tee_net_ops = {
183 	.init = tee_net_init,
184 	.id   = &tee_net_id,
185 	.size = sizeof(struct tee_net),
186 };
187 
188 static struct notifier_block tee_netdev_notifier = {
189 	.notifier_call = tee_netdev_event,
190 };
191 
tee_tg_init(void)192 static 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 
210 unregister_targets:
211 	xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
212 cleanup_subsys:
213 	unregister_pernet_subsys(&tee_net_ops);
214 	return ret;
215 }
216 
tee_tg_exit(void)217 static 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 
224 module_init(tee_tg_init);
225 module_exit(tee_tg_exit);
226 MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
227 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
228 MODULE_DESCRIPTION("Xtables: Reroute packet copy");
229 MODULE_LICENSE("GPL");
230 MODULE_ALIAS("ipt_TEE");
231 MODULE_ALIAS("ip6t_TEE");
232