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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
95
96
97
98
99 skb = pskb_copy(skb, GFP_ATOMIC);
100 if (skb == NULL)
101 return XT_CONTINUE;
102
103#ifdef WITH_CONNTRACK
104
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
112
113
114
115
116
117
118
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 = 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
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");
310
