2 * "TEE" target extension for Xtables
3 * Copyright © Sebastian Claßen, 2007
4 * Jan Engelhardt, 2007-2010
6 * based on ipt_ROUTE.c from Cédric de Launois
7 * <delaunois@info.ucl.be>
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.
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>
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>
28 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
29 # define WITH_CONNTRACK 1
30 # include <net/netfilter/nf_conntrack.h>
32 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
37 struct notifier_block notifier;
38 struct xt_tee_tginfo *tginfo;
42 static const union nf_inet_addr tee_zero_address;
43 static DEFINE_PER_CPU(bool, tee_active);
45 static struct net *pick_net(struct sk_buff *skb)
48 const struct dst_entry *dst;
51 return dev_net(skb->dev);
53 if (dst != NULL && dst->dev != NULL)
54 return dev_net(dst->dev);
60 tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
62 const struct iphdr *iph = ip_hdr(skb);
63 struct net *net = pick_net(skb);
67 memset(&fl4, 0, sizeof(fl4));
69 if (info->priv->oif == -1)
71 fl4.flowi4_oif = info->priv->oif;
73 fl4.daddr = info->gw.ip;
74 fl4.flowi4_tos = RT_TOS(iph->tos);
75 fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
76 rt = ip_route_output_key(net, &fl4);
81 skb_dst_set(skb, &rt->dst);
82 skb->dev = rt->dst.dev;
83 skb->protocol = htons(ETH_P_IP);
88 tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
90 const struct xt_tee_tginfo *info = par->targinfo;
93 if (percpu_read(tee_active))
96 * Copy the skb, and route the copy. Will later return %XT_CONTINUE for
97 * the original skb, which should continue on its way as if nothing has
98 * happened. The copy should be independently delivered to the TEE
101 skb = pskb_copy(skb, GFP_ATOMIC);
105 #ifdef WITH_CONNTRACK
106 /* Avoid counting cloned packets towards the original connection. */
107 nf_conntrack_put(skb->nfct);
108 skb->nfct = &nf_ct_untracked_get()->ct_general;
109 skb->nfctinfo = IP_CT_NEW;
110 nf_conntrack_get(skb->nfct);
113 * If we are in PREROUTING/INPUT, the checksum must be recalculated
114 * since the length could have changed as a result of defragmentation.
116 * We also decrease the TTL to mitigate potential TEE loops
119 * Set %IP_DF so that the original source is notified of a potentially
120 * decreased MTU on the clone route. IPv6 does this too.
123 iph->frag_off |= htons(IP_DF);
124 if (par->hooknum == NF_INET_PRE_ROUTING ||
125 par->hooknum == NF_INET_LOCAL_IN)
129 if (tee_tg_route4(skb, info)) {
130 percpu_write(tee_active, true);
132 percpu_write(tee_active, false);
141 tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
143 const struct ipv6hdr *iph = ipv6_hdr(skb);
144 struct net *net = pick_net(skb);
145 struct dst_entry *dst;
148 memset(&fl, 0, sizeof(fl));
150 if (info->priv->oif == -1)
152 fl.flowi_oif = info->priv->oif;
154 fl.fl6_dst = info->gw.in6;
155 fl.fl6_flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
156 (iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
157 dst = ip6_route_output(net, NULL, &fl);
162 skb_dst_set(skb, dst);
164 skb->protocol = htons(ETH_P_IPV6);
169 tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
171 const struct xt_tee_tginfo *info = par->targinfo;
173 if (percpu_read(tee_active))
175 skb = pskb_copy(skb, GFP_ATOMIC);
179 #ifdef WITH_CONNTRACK
180 nf_conntrack_put(skb->nfct);
181 skb->nfct = &nf_ct_untracked_get()->ct_general;
182 skb->nfctinfo = IP_CT_NEW;
183 nf_conntrack_get(skb->nfct);
185 if (par->hooknum == NF_INET_PRE_ROUTING ||
186 par->hooknum == NF_INET_LOCAL_IN) {
187 struct ipv6hdr *iph = ipv6_hdr(skb);
190 if (tee_tg_route6(skb, info)) {
191 percpu_write(tee_active, true);
193 percpu_write(tee_active, false);
199 #endif /* WITH_IPV6 */
201 static int tee_netdev_event(struct notifier_block *this, unsigned long event,
204 struct net_device *dev = ptr;
205 struct xt_tee_priv *priv;
207 priv = container_of(this, struct xt_tee_priv, notifier);
209 case NETDEV_REGISTER:
210 if (!strcmp(dev->name, priv->tginfo->oif))
211 priv->oif = dev->ifindex;
213 case NETDEV_UNREGISTER:
214 if (dev->ifindex == priv->oif)
217 case NETDEV_CHANGENAME:
218 if (!strcmp(dev->name, priv->tginfo->oif))
219 priv->oif = dev->ifindex;
220 else if (dev->ifindex == priv->oif)
228 static int tee_tg_check(const struct xt_tgchk_param *par)
230 struct xt_tee_tginfo *info = par->targinfo;
231 struct xt_tee_priv *priv;
233 /* 0.0.0.0 and :: not allowed */
234 if (memcmp(&info->gw, &tee_zero_address,
235 sizeof(tee_zero_address)) == 0)
239 if (info->oif[sizeof(info->oif)-1] != '\0')
242 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
248 priv->notifier.notifier_call = tee_netdev_event;
251 register_netdevice_notifier(&priv->notifier);
258 static void tee_tg_destroy(const struct xt_tgdtor_param *par)
260 struct xt_tee_tginfo *info = par->targinfo;
263 unregister_netdevice_notifier(&info->priv->notifier);
268 static struct xt_target tee_tg_reg[] __read_mostly = {
272 .family = NFPROTO_IPV4,
274 .targetsize = sizeof(struct xt_tee_tginfo),
275 .checkentry = tee_tg_check,
276 .destroy = tee_tg_destroy,
283 .family = NFPROTO_IPV6,
285 .targetsize = sizeof(struct xt_tee_tginfo),
286 .checkentry = tee_tg_check,
287 .destroy = tee_tg_destroy,
293 static int __init tee_tg_init(void)
295 return xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
298 static void __exit tee_tg_exit(void)
300 xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
303 module_init(tee_tg_init);
304 module_exit(tee_tg_exit);
305 MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
306 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
307 MODULE_DESCRIPTION("Xtables: Reroute packet copy");
308 MODULE_LICENSE("GPL");
309 MODULE_ALIAS("ipt_TEE");
310 MODULE_ALIAS("ip6t_TEE");