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@@ -0,0 +1,256 @@
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+/*
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+ * "TEE" target extension for Xtables
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+ * Copyright © Sebastian Claßen, 2007
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+ * Jan Engelhardt, 2007-2010
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+ *
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+ * based on ipt_ROUTE.c from Cédric de Launois
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+ * <delaunois@info.ucl.be>
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License
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+ * version 2 or later, as published by the Free Software Foundation.
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+ */
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+#include <linux/ip.h>
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+#include <linux/module.h>
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+#include <linux/route.h>
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+#include <linux/skbuff.h>
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+#include <net/checksum.h>
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+#include <net/icmp.h>
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+#include <net/ip.h>
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+#include <net/ipv6.h>
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+#include <net/ip6_route.h>
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+#include <net/route.h>
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+#include <linux/netfilter/x_tables.h>
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+#include <linux/netfilter/xt_TEE.h>
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+
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+#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
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+# define WITH_CONNTRACK 1
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+# include <net/netfilter/nf_conntrack.h>
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+#endif
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+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
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+# define WITH_IPV6 1
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+#endif
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+
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+static const union nf_inet_addr tee_zero_address;
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+
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+static struct net *pick_net(struct sk_buff *skb)
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+{
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+#ifdef CONFIG_NET_NS
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+ const struct dst_entry *dst;
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+
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+ if (skb->dev != NULL)
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+ return dev_net(skb->dev);
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+ dst = skb_dst(skb);
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+ if (dst != NULL && dst->dev != NULL)
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+ return dev_net(dst->dev);
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+#endif
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+ return &init_net;
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+}
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+
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+static bool tee_tg_route_oif(struct flowi *f, struct net *net,
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+ const struct xt_tee_tginfo *info)
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+{
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+ const struct net_device *dev;
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+
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+ if (*info->oif != '\0')
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+ return true;
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+ dev = dev_get_by_name(net, info->oif);
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+ if (dev == NULL)
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+ return false;
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+ f->oif = dev->ifindex;
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+ return true;
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+}
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+
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+static bool
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+tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
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+{
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+ const struct iphdr *iph = ip_hdr(skb);
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+ struct net *net = pick_net(skb);
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+ struct rtable *rt;
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+ struct flowi fl;
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+
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+ memset(&fl, 0, sizeof(fl));
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+ if (!tee_tg_route_oif(&fl, net, info))
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+ return false;
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+ fl.nl_u.ip4_u.daddr = info->gw.ip;
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+ fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
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+ fl.nl_u.ip4_u.scope = RT_SCOPE_UNIVERSE;
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+ if (ip_route_output_key(net, &rt, &fl) != 0)
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+ return false;
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+
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+ dst_release(skb_dst(skb));
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+ skb_dst_set(skb, &rt->u.dst);
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+ skb->dev = rt->u.dst.dev;
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+ skb->protocol = htons(ETH_P_IP);
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+ return true;
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+}
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+
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+static unsigned int
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+tee_tg4(struct sk_buff *skb, const struct xt_target_param *par)
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+{
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+ const struct xt_tee_tginfo *info = par->targinfo;
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+ struct iphdr *iph;
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+
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+ /*
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+ * Copy the skb, and route the copy. Will later return %XT_CONTINUE for
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+ * the original skb, which should continue on its way as if nothing has
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+ * happened. The copy should be independently delivered to the TEE
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+ * --gateway.
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+ */
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+ skb = pskb_copy(skb, GFP_ATOMIC);
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+ if (skb == NULL)
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+ return XT_CONTINUE;
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+
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+#ifdef WITH_CONNTRACK
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+ /* Avoid counting cloned packets towards the original connection. */
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+ nf_conntrack_put(skb->nfct);
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+ skb->nfct = &nf_conntrack_untracked.ct_general;
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+ skb->nfctinfo = IP_CT_NEW;
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+ nf_conntrack_get(skb->nfct);
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+#endif
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+ /*
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+ * If we are in PREROUTING/INPUT, the checksum must be recalculated
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+ * since the length could have changed as a result of defragmentation.
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+ *
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+ * We also decrease the TTL to mitigate potential TEE loops
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+ * between two hosts.
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+ *
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+ * Set %IP_DF so that the original source is notified of a potentially
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+ * decreased MTU on the clone route. IPv6 does this too.
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+ */
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+ iph = ip_hdr(skb);
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+ iph->frag_off |= htons(IP_DF);
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+ if (par->hooknum == NF_INET_PRE_ROUTING ||
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+ par->hooknum == NF_INET_LOCAL_IN)
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+ --iph->ttl;
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+ ip_send_check(iph);
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+
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+ /*
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+ * Xtables is not reentrant currently, so a choice has to be made:
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+ * 1. return absolute verdict for the original and let the cloned
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+ * packet travel through the chains
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+ * 2. let the original continue travelling and not pass the clone
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+ * to Xtables.
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+ * #2 is chosen. Normally, we would use ip_local_out for the clone.
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+ * Because iph->check is already correct and we don't pass it to
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+ * Xtables anyway, a shortcut to dst_output [forwards to ip_output] can
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+ * be taken. %IPSKB_REROUTED needs to be set so that ip_output does not
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+ * invoke POSTROUTING on the cloned packet.
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+ */
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+ IPCB(skb)->flags |= IPSKB_REROUTED;
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+ if (tee_tg_route4(skb, info))
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+ ip_output(skb);
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+ else
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+ kfree_skb(skb);
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+
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+ return XT_CONTINUE;
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+}
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+
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+#ifdef WITH_IPV6
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+static bool
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+tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
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+{
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+ const struct ipv6hdr *iph = ipv6_hdr(skb);
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+ struct net *net = pick_net(skb);
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+ struct dst_entry *dst;
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+ struct flowi fl;
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+
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+ memset(&fl, 0, sizeof(fl));
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+ if (!tee_tg_route_oif(&fl, net, info))
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+ return false;
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+ fl.nl_u.ip6_u.daddr = info->gw.in6;
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+ fl.nl_u.ip6_u.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
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+ (iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
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+ dst = ip6_route_output(net, NULL, &fl);
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+ if (dst == NULL)
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+ return false;
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+
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+ dst_release(skb_dst(skb));
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+ skb_dst_set(skb, dst);
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+ skb->dev = dst->dev;
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+ skb->protocol = htons(ETH_P_IPV6);
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+ return true;
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+}
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+
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+static unsigned int
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+tee_tg6(struct sk_buff *skb, const struct xt_target_param *par)
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+{
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+ const struct xt_tee_tginfo *info = par->targinfo;
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+
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+ skb = pskb_copy(skb, GFP_ATOMIC);
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+ if (skb == NULL)
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+ return XT_CONTINUE;
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+
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+#ifdef WITH_CONNTRACK
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+ nf_conntrack_put(skb->nfct);
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+ skb->nfct = &nf_conntrack_untracked.ct_general;
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+ skb->nfctinfo = IP_CT_NEW;
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+ nf_conntrack_get(skb->nfct);
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+#endif
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+ if (par->hooknum == NF_INET_PRE_ROUTING ||
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+ par->hooknum == NF_INET_LOCAL_IN) {
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+ struct ipv6hdr *iph = ipv6_hdr(skb);
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+ --iph->hop_limit;
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+ }
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+ IP6CB(skb)->flags |= IP6SKB_REROUTED;
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+ if (tee_tg_route6(skb, info))
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+ ip6_output(skb);
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+ else
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+ kfree_skb(skb);
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+
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+ return XT_CONTINUE;
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+}
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+#endif /* WITH_IPV6 */
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+
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+static int tee_tg_check(const struct xt_tgchk_param *par)
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+{
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+ const struct xt_tee_tginfo *info = par->targinfo;
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+
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+ if (info->oif[sizeof(info->oif)-1] != '\0')
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+ return -EINVAL;
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+ /* 0.0.0.0 and :: not allowed */
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+ return (memcmp(&info->gw, &tee_zero_address,
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+ sizeof(tee_zero_address)) == 0) ? -EINVAL : 0;
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+}
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+
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+static struct xt_target tee_tg_reg[] __read_mostly = {
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+ {
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+ .name = "TEE",
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+ .revision = 1,
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+ .family = NFPROTO_IPV4,
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+ .target = tee_tg4,
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+ .targetsize = sizeof(struct xt_tee_tginfo),
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+ .checkentry = tee_tg_check,
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+ .me = THIS_MODULE,
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+ },
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+#ifdef WITH_IPV6
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+ {
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+ .name = "TEE",
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+ .revision = 1,
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+ .family = NFPROTO_IPV6,
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+ .target = tee_tg6,
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+ .targetsize = sizeof(struct xt_tee_tginfo),
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+ .checkentry = tee_tg_check,
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+ .me = THIS_MODULE,
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+ },
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+#endif
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+};
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+
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+static int __init tee_tg_init(void)
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+{
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+ return xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
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+}
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+
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+static void __exit tee_tg_exit(void)
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+{
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+ xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
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+}
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+
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+module_init(tee_tg_init);
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+module_exit(tee_tg_exit);
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+MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
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+MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
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+MODULE_DESCRIPTION("Xtables: Reroute packet copy");
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+MODULE_LICENSE("GPL");
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+MODULE_ALIAS("ipt_TEE");
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+MODULE_ALIAS("ip6t_TEE");
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