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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
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 Claßen <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");
1/*
2 * "TEE" target extension for Xtables
3 * Copyright © Sebastian Claßen, 2007
4 * Jan Engelhardt, 2007-2010
5 *
6 * based on ipt_ROUTE.c from Cédric de Launois
7 * <delaunois@info.ucl.be>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * version 2 or later, as published by the Free Software Foundation.
12 */
13#include <linux/ip.h>
14#include <linux/module.h>
15#include <linux/percpu.h>
16#include <linux/route.h>
17#include <linux/skbuff.h>
18#include <linux/notifier.h>
19#include <net/checksum.h>
20#include <net/icmp.h>
21#include <net/ip.h>
22#include <net/ipv6.h>
23#include <net/ip6_route.h>
24#include <net/route.h>
25#include <linux/netfilter/x_tables.h>
26#include <linux/netfilter/xt_TEE.h>
27
28#if IS_ENABLED(CONFIG_NF_CONNTRACK)
29# define WITH_CONNTRACK 1
30# include <net/netfilter/nf_conntrack.h>
31#endif
32
33struct xt_tee_priv {
34 struct notifier_block notifier;
35 struct xt_tee_tginfo *tginfo;
36 int oif;
37};
38
39static const union nf_inet_addr tee_zero_address;
40static DEFINE_PER_CPU(bool, tee_active);
41
42static struct net *pick_net(struct sk_buff *skb)
43{
44#ifdef CONFIG_NET_NS
45 const struct dst_entry *dst;
46
47 if (skb->dev != NULL)
48 return dev_net(skb->dev);
49 dst = skb_dst(skb);
50 if (dst != NULL && dst->dev != NULL)
51 return dev_net(dst->dev);
52#endif
53 return &init_net;
54}
55
56static bool
57tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
58{
59 const struct iphdr *iph = ip_hdr(skb);
60 struct net *net = pick_net(skb);
61 struct rtable *rt;
62 struct flowi4 fl4;
63
64 memset(&fl4, 0, sizeof(fl4));
65 if (info->priv) {
66 if (info->priv->oif == -1)
67 return false;
68 fl4.flowi4_oif = info->priv->oif;
69 }
70 fl4.daddr = info->gw.ip;
71 fl4.flowi4_tos = RT_TOS(iph->tos);
72 fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
73 fl4.flowi4_flags = FLOWI_FLAG_KNOWN_NH;
74 rt = ip_route_output_key(net, &fl4);
75 if (IS_ERR(rt))
76 return false;
77
78 skb_dst_drop(skb);
79 skb_dst_set(skb, &rt->dst);
80 skb->dev = rt->dst.dev;
81 skb->protocol = htons(ETH_P_IP);
82 return true;
83}
84
85static unsigned int
86tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
87{
88 const struct xt_tee_tginfo *info = par->targinfo;
89 struct iphdr *iph;
90
91 if (__this_cpu_read(tee_active))
92 return XT_CONTINUE;
93 /*
94 * Copy the skb, and route the copy. Will later return %XT_CONTINUE for
95 * the original skb, which should continue on its way as if nothing has
96 * happened. The copy should be independently delivered to the TEE
97 * --gateway.
98 */
99 skb = pskb_copy(skb, GFP_ATOMIC);
100 if (skb == NULL)
101 return XT_CONTINUE;
102
103#ifdef WITH_CONNTRACK
104 /* Avoid counting cloned packets towards the original connection. */
105 nf_conntrack_put(skb->nfct);
106 skb->nfct = &nf_ct_untracked_get()->ct_general;
107 skb->nfctinfo = IP_CT_NEW;
108 nf_conntrack_get(skb->nfct);
109#endif
110 /*
111 * If we are in PREROUTING/INPUT, the checksum must be recalculated
112 * since the length could have changed as a result of defragmentation.
113 *
114 * We also decrease the TTL to mitigate potential TEE loops
115 * between two hosts.
116 *
117 * Set %IP_DF so that the original source is notified of a potentially
118 * decreased MTU on the clone route. IPv6 does this too.
119 */
120 iph = ip_hdr(skb);
121 iph->frag_off |= htons(IP_DF);
122 if (par->hooknum == NF_INET_PRE_ROUTING ||
123 par->hooknum == NF_INET_LOCAL_IN)
124 --iph->ttl;
125 ip_send_check(iph);
126
127 if (tee_tg_route4(skb, info)) {
128 __this_cpu_write(tee_active, true);
129 ip_local_out(skb);
130 __this_cpu_write(tee_active, false);
131 } else {
132 kfree_skb(skb);
133 }
134 return XT_CONTINUE;
135}
136
137#if IS_ENABLED(CONFIG_IPV6)
138static bool
139tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
140{
141 const struct ipv6hdr *iph = ipv6_hdr(skb);
142 struct net *net = pick_net(skb);
143 struct dst_entry *dst;
144 struct flowi6 fl6;
145
146 memset(&fl6, 0, sizeof(fl6));
147 if (info->priv) {
148 if (info->priv->oif == -1)
149 return false;
150 fl6.flowi6_oif = info->priv->oif;
151 }
152 fl6.daddr = info->gw.in6;
153 fl6.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
154 (iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
155 dst = ip6_route_output(net, NULL, &fl6);
156 if (dst->error) {
157 dst_release(dst);
158 return false;
159 }
160 skb_dst_drop(skb);
161 skb_dst_set(skb, dst);
162 skb->dev = dst->dev;
163 skb->protocol = htons(ETH_P_IPV6);
164 return true;
165}
166
167static unsigned int
168tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
169{
170 const struct xt_tee_tginfo *info = par->targinfo;
171
172 if (__this_cpu_read(tee_active))
173 return XT_CONTINUE;
174 skb = pskb_copy(skb, GFP_ATOMIC);
175 if (skb == NULL)
176 return XT_CONTINUE;
177
178#ifdef WITH_CONNTRACK
179 nf_conntrack_put(skb->nfct);
180 skb->nfct = &nf_ct_untracked_get()->ct_general;
181 skb->nfctinfo = IP_CT_NEW;
182 nf_conntrack_get(skb->nfct);
183#endif
184 if (par->hooknum == NF_INET_PRE_ROUTING ||
185 par->hooknum == NF_INET_LOCAL_IN) {
186 struct ipv6hdr *iph = ipv6_hdr(skb);
187 --iph->hop_limit;
188 }
189 if (tee_tg_route6(skb, info)) {
190 __this_cpu_write(tee_active, true);
191 ip6_local_out(skb);
192 __this_cpu_write(tee_active, false);
193 } else {
194 kfree_skb(skb);
195 }
196 return XT_CONTINUE;
197}
198#endif
199
200static int tee_netdev_event(struct notifier_block *this, unsigned long event,
201 void *ptr)
202{
203 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
204 struct xt_tee_priv *priv;
205
206 priv = container_of(this, struct xt_tee_priv, notifier);
207 switch (event) {
208 case NETDEV_REGISTER:
209 if (!strcmp(dev->name, priv->tginfo->oif))
210 priv->oif = dev->ifindex;
211 break;
212 case NETDEV_UNREGISTER:
213 if (dev->ifindex == priv->oif)
214 priv->oif = -1;
215 break;
216 case NETDEV_CHANGENAME:
217 if (!strcmp(dev->name, priv->tginfo->oif))
218 priv->oif = dev->ifindex;
219 else if (dev->ifindex == priv->oif)
220 priv->oif = -1;
221 break;
222 }
223
224 return NOTIFY_DONE;
225}
226
227static int tee_tg_check(const struct xt_tgchk_param *par)
228{
229 struct xt_tee_tginfo *info = par->targinfo;
230 struct xt_tee_priv *priv;
231
232 /* 0.0.0.0 and :: not allowed */
233 if (memcmp(&info->gw, &tee_zero_address,
234 sizeof(tee_zero_address)) == 0)
235 return -EINVAL;
236
237 if (info->oif[0]) {
238 if (info->oif[sizeof(info->oif)-1] != '\0')
239 return -EINVAL;
240
241 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
242 if (priv == NULL)
243 return -ENOMEM;
244
245 priv->tginfo = info;
246 priv->oif = -1;
247 priv->notifier.notifier_call = tee_netdev_event;
248 info->priv = priv;
249
250 register_netdevice_notifier(&priv->notifier);
251 } else
252 info->priv = NULL;
253
254 return 0;
255}
256
257static void tee_tg_destroy(const struct xt_tgdtor_param *par)
258{
259 struct xt_tee_tginfo *info = par->targinfo;
260
261 if (info->priv) {
262 unregister_netdevice_notifier(&info->priv->notifier);
263 kfree(info->priv);
264 }
265}
266
267static struct xt_target tee_tg_reg[] __read_mostly = {
268 {
269 .name = "TEE",
270 .revision = 1,
271 .family = NFPROTO_IPV4,
272 .target = tee_tg4,
273 .targetsize = sizeof(struct xt_tee_tginfo),
274 .checkentry = tee_tg_check,
275 .destroy = tee_tg_destroy,
276 .me = THIS_MODULE,
277 },
278#if IS_ENABLED(CONFIG_IPV6)
279 {
280 .name = "TEE",
281 .revision = 1,
282 .family = NFPROTO_IPV6,
283 .target = tee_tg6,
284 .targetsize = sizeof(struct xt_tee_tginfo),
285 .checkentry = tee_tg_check,
286 .destroy = tee_tg_destroy,
287 .me = THIS_MODULE,
288 },
289#endif
290};
291
292static int __init tee_tg_init(void)
293{
294 return xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
295}
296
297static void __exit tee_tg_exit(void)
298{
299 xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
300}
301
302module_init(tee_tg_init);
303module_exit(tee_tg_exit);
304MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
305MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
306MODULE_DESCRIPTION("Xtables: Reroute packet copy");
307MODULE_LICENSE("GPL");
308MODULE_ALIAS("ipt_TEE");
309MODULE_ALIAS("ip6t_TEE");