2010-04-19 06:17:47 -06:00
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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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2010-04-19 08:06:52 -06:00
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#include <linux/percpu.h>
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2010-04-19 06:17:47 -06:00
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#include <linux/route.h>
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#include <linux/skbuff.h>
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2010-04-20 07:07:32 -06:00
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#include <linux/notifier.h>
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2010-04-19 06:17:47 -06:00
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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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2011-12-11 19:58:24 -07:00
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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2010-04-19 06:17:47 -06:00
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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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2010-04-20 07:07:32 -06:00
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struct xt_tee_priv {
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struct notifier_block notifier;
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struct xt_tee_tginfo *tginfo;
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int oif;
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};
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2010-04-19 06:17:47 -06:00
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static const union nf_inet_addr tee_zero_address;
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2010-04-19 08:06:52 -06:00
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static DEFINE_PER_CPU(bool, tee_active);
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2010-04-19 06:17:47 -06:00
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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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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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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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2011-03-11 23:12:47 -07:00
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struct flowi4 fl4;
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2010-04-19 06:17:47 -06:00
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2011-03-11 23:12:47 -07:00
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memset(&fl4, 0, sizeof(fl4));
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2010-04-20 07:07:32 -06:00
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if (info->priv) {
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if (info->priv->oif == -1)
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return false;
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2011-03-11 23:12:47 -07:00
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fl4.flowi4_oif = info->priv->oif;
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2010-04-20 07:07:32 -06:00
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}
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2011-03-11 23:12:47 -07:00
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fl4.daddr = info->gw.ip;
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fl4.flowi4_tos = RT_TOS(iph->tos);
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fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
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rt = ip_route_output_key(net, &fl4);
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2011-03-02 15:31:35 -07:00
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if (IS_ERR(rt))
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2010-04-19 06:17:47 -06:00
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return false;
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2010-05-28 04:41:17 -06:00
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skb_dst_drop(skb);
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2010-06-11 00:31:35 -06:00
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skb_dst_set(skb, &rt->dst);
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skb->dev = rt->dst.dev;
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2010-04-19 06:17:47 -06:00
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skb->protocol = htons(ETH_P_IP);
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return true;
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}
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static unsigned int
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2009-07-05 11:43:26 -06:00
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tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
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2010-04-19 06:17:47 -06:00
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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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2010-04-19 08:06:52 -06:00
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if (percpu_read(tee_active))
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return XT_CONTINUE;
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2010-04-19 06:17:47 -06:00
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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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#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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2010-06-08 08:09:52 -06:00
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skb->nfct = &nf_ct_untracked_get()->ct_general;
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2010-04-19 06:17:47 -06:00
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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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2010-04-19 08:06:52 -06:00
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if (tee_tg_route4(skb, info)) {
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percpu_write(tee_active, true);
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ip_local_out(skb);
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percpu_write(tee_active, false);
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} else {
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2010-04-19 06:17:47 -06:00
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kfree_skb(skb);
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2010-04-19 08:06:52 -06:00
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}
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2010-04-19 06:17:47 -06:00
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return XT_CONTINUE;
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}
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2011-12-10 02:48:31 -07:00
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#if IS_ENABLED(CONFIG_IPV6)
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2010-04-19 06:17:47 -06:00
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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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2011-03-12 14:22:43 -07:00
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struct flowi6 fl6;
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2010-04-19 06:17:47 -06:00
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2011-03-12 14:22:43 -07:00
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memset(&fl6, 0, sizeof(fl6));
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2010-04-20 07:07:32 -06:00
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if (info->priv) {
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if (info->priv->oif == -1)
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return false;
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2011-03-12 14:22:43 -07:00
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fl6.flowi6_oif = info->priv->oif;
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2010-04-20 07:07:32 -06:00
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}
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2011-03-12 14:22:43 -07:00
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fl6.daddr = info->gw.in6;
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fl6.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
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2010-11-12 11:43:55 -07:00
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(iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
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2011-03-12 14:22:43 -07:00
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dst = ip6_route_output(net, NULL, &fl6);
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2010-04-19 06:17:47 -06:00
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if (dst == NULL)
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return false;
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2010-05-28 04:41:17 -06:00
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skb_dst_drop(skb);
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2010-04-19 06:17:47 -06:00
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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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static unsigned int
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2009-07-05 11:43:26 -06:00
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tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
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2010-04-19 06:17:47 -06:00
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{
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const struct xt_tee_tginfo *info = par->targinfo;
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2010-04-19 08:06:52 -06:00
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if (percpu_read(tee_active))
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return XT_CONTINUE;
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2010-04-19 06:17:47 -06:00
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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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#ifdef WITH_CONNTRACK
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nf_conntrack_put(skb->nfct);
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2010-06-08 08:09:52 -06:00
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skb->nfct = &nf_ct_untracked_get()->ct_general;
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2010-04-19 06:17:47 -06:00
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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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2010-04-19 08:06:52 -06:00
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if (tee_tg_route6(skb, info)) {
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percpu_write(tee_active, true);
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ip6_local_out(skb);
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percpu_write(tee_active, false);
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} else {
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2010-04-19 06:17:47 -06:00
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kfree_skb(skb);
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2010-04-19 08:06:52 -06:00
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}
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2010-04-19 06:17:47 -06:00
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return XT_CONTINUE;
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}
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2011-12-10 02:48:31 -07:00
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#endif
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2010-04-19 06:17:47 -06:00
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2010-04-20 07:07:32 -06:00
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static int tee_netdev_event(struct notifier_block *this, unsigned long event,
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void *ptr)
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{
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struct net_device *dev = ptr;
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struct xt_tee_priv *priv;
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priv = container_of(this, struct xt_tee_priv, notifier);
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switch (event) {
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case NETDEV_REGISTER:
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if (!strcmp(dev->name, priv->tginfo->oif))
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priv->oif = dev->ifindex;
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break;
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case NETDEV_UNREGISTER:
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if (dev->ifindex == priv->oif)
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priv->oif = -1;
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break;
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case NETDEV_CHANGENAME:
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if (!strcmp(dev->name, priv->tginfo->oif))
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priv->oif = dev->ifindex;
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else if (dev->ifindex == priv->oif)
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priv->oif = -1;
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break;
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}
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return NOTIFY_DONE;
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}
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2010-04-19 06:17:47 -06:00
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static int tee_tg_check(const struct xt_tgchk_param *par)
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{
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2010-04-20 07:07:32 -06:00
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struct xt_tee_tginfo *info = par->targinfo;
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struct xt_tee_priv *priv;
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2010-04-19 06:17:47 -06:00
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/* 0.0.0.0 and :: not allowed */
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2010-04-20 07:07:32 -06:00
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if (memcmp(&info->gw, &tee_zero_address,
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sizeof(tee_zero_address)) == 0)
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return -EINVAL;
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if (info->oif[0]) {
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if (info->oif[sizeof(info->oif)-1] != '\0')
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return -EINVAL;
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priv = kzalloc(sizeof(*priv), GFP_KERNEL);
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if (priv == NULL)
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return -ENOMEM;
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priv->tginfo = info;
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priv->oif = -1;
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priv->notifier.notifier_call = tee_netdev_event;
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info->priv = priv;
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register_netdevice_notifier(&priv->notifier);
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} else
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info->priv = NULL;
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return 0;
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}
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static void tee_tg_destroy(const struct xt_tgdtor_param *par)
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{
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struct xt_tee_tginfo *info = par->targinfo;
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if (info->priv) {
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unregister_netdevice_notifier(&info->priv->notifier);
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kfree(info->priv);
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}
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2010-04-19 06:17:47 -06:00
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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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2010-04-20 07:07:32 -06:00
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.destroy = tee_tg_destroy,
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2010-04-19 06:17:47 -06:00
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.me = THIS_MODULE,
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},
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2011-12-10 02:48:31 -07:00
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#if IS_ENABLED(CONFIG_IPV6)
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2010-04-19 06:17:47 -06:00
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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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2010-04-20 07:07:32 -06:00
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.destroy = tee_tg_destroy,
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2010-04-19 06:17:47 -06:00
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.me = THIS_MODULE,
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},
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#endif
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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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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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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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