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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 defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
29# define WITH_CONNTRACK 1
30# include <net/netfilter/nf_conntrack.h>
31#endif
32#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
33# define WITH_IPV6 1
34#endif
35
36struct xt_tee_priv {
37 struct notifier_block notifier;
38 struct xt_tee_tginfo *tginfo;
39 int oif;
40};
41
42static const union nf_inet_addr tee_zero_address;
43static DEFINE_PER_CPU(bool, tee_active);
44
45static struct net *pick_net(struct sk_buff *skb)
46{
47#ifdef CONFIG_NET_NS
48 const struct dst_entry *dst;
49
50 if (skb->dev != NULL)
51 return dev_net(skb->dev);
52 dst = skb_dst(skb);
53 if (dst != NULL && dst->dev != NULL)
54 return dev_net(dst->dev);
55#endif
56 return &init_net;
57}
58
59static bool
60tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
61{
62 const struct iphdr *iph = ip_hdr(skb);
63 struct net *net = pick_net(skb);
64 struct rtable *rt;
65 struct flowi fl;
66
67 memset(&fl, 0, sizeof(fl));
68 if (info->priv) {
69 if (info->priv->oif == -1)
70 return false;
71 fl.oif = info->priv->oif;
72 }
73 fl.nl_u.ip4_u.daddr = info->gw.ip;
74 fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
75 fl.nl_u.ip4_u.scope = RT_SCOPE_UNIVERSE;
76 if (ip_route_output_key(net, &rt, &fl) != 0)
77 return false;
78
79 skb_dst_drop(skb);
80 skb_dst_set(skb, &rt->u.dst);
81 skb->dev = rt->u.dst.dev;
82 skb->protocol = htons(ETH_P_IP);
83 return true;
84}
85
86static unsigned int
87tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
88{
89 const struct xt_tee_tginfo *info = par->targinfo;
90 struct iphdr *iph;
91
92 if (percpu_read(tee_active))
93 return XT_CONTINUE;
94
95
96
97
98
99
100 skb = pskb_copy(skb, GFP_ATOMIC);
101 if (skb == NULL)
102 return XT_CONTINUE;
103
104#ifdef WITH_CONNTRACK
105
106 nf_conntrack_put(skb->nfct);
107 skb->nfct = &nf_conntrack_untracked.ct_general;
108 skb->nfctinfo = IP_CT_NEW;
109 nf_conntrack_get(skb->nfct);
110#endif
111
112
113
114
115
116
117
118
119
120
121 iph = ip_hdr(skb);
122 iph->frag_off |= htons(IP_DF);
123 if (par->hooknum == NF_INET_PRE_ROUTING ||
124 par->hooknum == NF_INET_LOCAL_IN)
125 --iph->ttl;
126 ip_send_check(iph);
127
128 if (tee_tg_route4(skb, info)) {
129 percpu_write(tee_active, true);
130 ip_local_out(skb);
131 percpu_write(tee_active, false);
132 } else {
133 kfree_skb(skb);
134 }
135 return XT_CONTINUE;
136}
137
138#ifdef WITH_IPV6
139static bool
140tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
141{
142 const struct ipv6hdr *iph = ipv6_hdr(skb);
143 struct net *net = pick_net(skb);
144 struct dst_entry *dst;
145 struct flowi fl;
146
147 memset(&fl, 0, sizeof(fl));
148 if (info->priv) {
149 if (info->priv->oif == -1)
150 return false;
151 fl.oif = info->priv->oif;
152 }
153 fl.nl_u.ip6_u.daddr = info->gw.in6;
154 fl.nl_u.ip6_u.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
155 (iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
156 dst = ip6_route_output(net, NULL, &fl);
157 if (dst == NULL)
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 (percpu_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_conntrack_untracked.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 percpu_write(tee_active, true);
191 ip6_local_out(skb);
192 percpu_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#ifdef WITH_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 ClaÃen <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
