--- /dev/null
+/*
+ * "TEE" target extension for Xtables
+ * Copyright © Sebastian Claßen, 2007
+ * Jan Engelhardt, 2007-2010
+ *
+ * based on ipt_ROUTE.c from Cédric de Launois
+ * <delaunois@info.ucl.be>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 or later, as published by the Free Software Foundation.
+ */
+#include <linux/ip.h>
+#include <linux/module.h>
+#include <linux/route.h>
+#include <linux/skbuff.h>
+#include <net/checksum.h>
+#include <net/icmp.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#include <net/route.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_TEE.h>
+
+#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
+# define WITH_CONNTRACK 1
+# include <net/netfilter/nf_conntrack.h>
+#endif
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+# define WITH_IPV6 1
+#endif
+
+static const union nf_inet_addr tee_zero_address;
+
+static struct net *pick_net(struct sk_buff *skb)
+{
+#ifdef CONFIG_NET_NS
+ const struct dst_entry *dst;
+
+ if (skb->dev != NULL)
+ return dev_net(skb->dev);
+ dst = skb_dst(skb);
+ if (dst != NULL && dst->dev != NULL)
+ return dev_net(dst->dev);
+#endif
+ return &init_net;
+}
+
+static bool tee_tg_route_oif(struct flowi *f, struct net *net,
+ const struct xt_tee_tginfo *info)
+{
+ const struct net_device *dev;
+
+ if (*info->oif != '\0')
+ return true;
+ dev = dev_get_by_name(net, info->oif);
+ if (dev == NULL)
+ return false;
+ f->oif = dev->ifindex;
+ return true;
+}
+
+static bool
+tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ struct net *net = pick_net(skb);
+ struct rtable *rt;
+ struct flowi fl;
+
+ memset(&fl, 0, sizeof(fl));
+ if (!tee_tg_route_oif(&fl, net, info))
+ return false;
+ fl.nl_u.ip4_u.daddr = info->gw.ip;
+ fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
+ fl.nl_u.ip4_u.scope = RT_SCOPE_UNIVERSE;
+ if (ip_route_output_key(net, &rt, &fl) != 0)
+ return false;
+
+ dst_release(skb_dst(skb));
+ skb_dst_set(skb, &rt->u.dst);
+ skb->dev = rt->u.dst.dev;
+ skb->protocol = htons(ETH_P_IP);
+ return true;
+}
+
+static unsigned int
+tee_tg4(struct sk_buff *skb, const struct xt_target_param *par)
+{
+ const struct xt_tee_tginfo *info = par->targinfo;
+ struct iphdr *iph;
+
+ /*
+ * Copy the skb, and route the copy. Will later return %XT_CONTINUE for
+ * the original skb, which should continue on its way as if nothing has
+ * happened. The copy should be independently delivered to the TEE
+ * --gateway.
+ */
+ skb = pskb_copy(skb, GFP_ATOMIC);
+ if (skb == NULL)
+ return XT_CONTINUE;
+
+#ifdef WITH_CONNTRACK
+ /* Avoid counting cloned packets towards the original connection. */
+ nf_conntrack_put(skb->nfct);
+ skb->nfct = &nf_conntrack_untracked.ct_general;
+ skb->nfctinfo = IP_CT_NEW;
+ nf_conntrack_get(skb->nfct);
+#endif
+ /*
+ * If we are in PREROUTING/INPUT, the checksum must be recalculated
+ * since the length could have changed as a result of defragmentation.
+ *
+ * We also decrease the TTL to mitigate potential TEE loops
+ * between two hosts.
+ *
+ * Set %IP_DF so that the original source is notified of a potentially
+ * decreased MTU on the clone route. IPv6 does this too.
+ */
+ iph = ip_hdr(skb);
+ iph->frag_off |= htons(IP_DF);
+ if (par->hooknum == NF_INET_PRE_ROUTING ||
+ par->hooknum == NF_INET_LOCAL_IN)
+ --iph->ttl;
+ ip_send_check(iph);
+
+ /*
+ * Xtables is not reentrant currently, so a choice has to be made:
+ * 1. return absolute verdict for the original and let the cloned
+ * packet travel through the chains
+ * 2. let the original continue travelling and not pass the clone
+ * to Xtables.
+ * #2 is chosen. Normally, we would use ip_local_out for the clone.
+ * Because iph->check is already correct and we don't pass it to
+ * Xtables anyway, a shortcut to dst_output [forwards to ip_output] can
+ * be taken. %IPSKB_REROUTED needs to be set so that ip_output does not
+ * invoke POSTROUTING on the cloned packet.
+ */
+ IPCB(skb)->flags |= IPSKB_REROUTED;
+ if (tee_tg_route4(skb, info))
+ ip_output(skb);
+ else
+ kfree_skb(skb);
+
+ return XT_CONTINUE;
+}
+
+#ifdef WITH_IPV6
+static bool
+tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
+{
+ const struct ipv6hdr *iph = ipv6_hdr(skb);
+ struct net *net = pick_net(skb);
+ struct dst_entry *dst;
+ struct flowi fl;
+
+ memset(&fl, 0, sizeof(fl));
+ if (!tee_tg_route_oif(&fl, net, info))
+ return false;
+ fl.nl_u.ip6_u.daddr = info->gw.in6;
+ fl.nl_u.ip6_u.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
+ (iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
+ dst = ip6_route_output(net, NULL, &fl);
+ if (dst == NULL)
+ return false;
+
+ dst_release(skb_dst(skb));
+ skb_dst_set(skb, dst);
+ skb->dev = dst->dev;
+ skb->protocol = htons(ETH_P_IPV6);
+ return true;
+}
+
+static unsigned int
+tee_tg6(struct sk_buff *skb, const struct xt_target_param *par)
+{
+ const struct xt_tee_tginfo *info = par->targinfo;
+
+ skb = pskb_copy(skb, GFP_ATOMIC);
+ if (skb == NULL)
+ return XT_CONTINUE;
+
+#ifdef WITH_CONNTRACK
+ nf_conntrack_put(skb->nfct);
+ skb->nfct = &nf_conntrack_untracked.ct_general;
+ skb->nfctinfo = IP_CT_NEW;
+ nf_conntrack_get(skb->nfct);
+#endif
+ if (par->hooknum == NF_INET_PRE_ROUTING ||
+ par->hooknum == NF_INET_LOCAL_IN) {
+ struct ipv6hdr *iph = ipv6_hdr(skb);
+ --iph->hop_limit;
+ }
+ IP6CB(skb)->flags |= IP6SKB_REROUTED;
+ if (tee_tg_route6(skb, info))
+ ip6_output(skb);
+ else
+ kfree_skb(skb);
+
+ return XT_CONTINUE;
+}
+#endif /* WITH_IPV6 */
+
+static int tee_tg_check(const struct xt_tgchk_param *par)
+{
+ const struct xt_tee_tginfo *info = par->targinfo;
+
+ if (info->oif[sizeof(info->oif)-1] != '\0')
+ return -EINVAL;
+ /* 0.0.0.0 and :: not allowed */
+ return (memcmp(&info->gw, &tee_zero_address,
+ sizeof(tee_zero_address)) == 0) ? -EINVAL : 0;
+}
+
+static struct xt_target tee_tg_reg[] __read_mostly = {
+ {
+ .name = "TEE",
+ .revision = 1,
+ .family = NFPROTO_IPV4,
+ .target = tee_tg4,
+ .targetsize = sizeof(struct xt_tee_tginfo),
+ .checkentry = tee_tg_check,
+ .me = THIS_MODULE,
+ },
+#ifdef WITH_IPV6
+ {
+ .name = "TEE",
+ .revision = 1,
+ .family = NFPROTO_IPV6,
+ .target = tee_tg6,
+ .targetsize = sizeof(struct xt_tee_tginfo),
+ .checkentry = tee_tg_check,
+ .me = THIS_MODULE,
+ },
+#endif
+};
+
+static int __init tee_tg_init(void)
+{
+ return xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
+}
+
+static void __exit tee_tg_exit(void)
+{
+ xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
+}
+
+module_init(tee_tg_init);
+module_exit(tee_tg_exit);
+MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
+MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
+MODULE_DESCRIPTION("Xtables: Reroute packet copy");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_TEE");
+MODULE_ALIAS("ip6t_TEE");
git://bbs.cooldavid.org / net-next-2.6.git / commitdiff