LXR linux/net/ipv6/netfilter/nf_dup

   1/*
   2 * (C) 2007 by Sebastian Claßen <sebastian.classen@freenet.ag>
   3 * (C) 2007-2010 by Jan Engelhardt <jengelh@medozas.de>
   4 *
   5 * Extracted from xt_TEE.c
   6 *
   7 * This program is free software; you can redistribute it and/or modify it
   8 * under the terms of the GNU General Public License version 2 or later, as
   9 * published by the Free Software Foundation.
  10 */
  11#include <linux/module.h>
  12#include <linux/percpu.h>
  13#include <linux/skbuff.h>
  14#include <linux/netfilter.h>
  15#include <net/ipv6.h>
  16#include <net/ip6_route.h>
  17#include <net/netfilter/ipv6/nf_dup_ipv6.h>
  18#if IS_ENABLED(CONFIG_NF_CONNTRACK)
  19#include <net/netfilter/nf_conntrack.h>
  20#endif
  21
  22static bool nf_dup_ipv6_route(struct net *net, struct sk_buff *skb,
  23                              const struct in6_addr *gw, int oif)
  24{
  25        const struct ipv6hdr *iph = ipv6_hdr(skb);
  26        struct dst_entry *dst;
  27        struct flowi6 fl6;
  28
  29        memset(&fl6, 0, sizeof(fl6));
  30        if (oif != -1)
  31                fl6.flowi6_oif = oif;
  32
  33        fl6.daddr = *gw;
  34        fl6.flowlabel = (__force __be32)(((iph->flow_lbl[0] & 0xF) << 16) |
  35                        (iph->flow_lbl[1] << 8) | iph->flow_lbl[2]);
  36        fl6.flowi6_flags = FLOWI_FLAG_KNOWN_NH;
  37        dst = ip6_route_output(net, NULL, &fl6);
  38        if (dst->error) {
  39                dst_release(dst);
  40                return false;
  41        }
  42        skb_dst_drop(skb);
  43        skb_dst_set(skb, dst);
  44        skb->dev      = dst->dev;
  45        skb->protocol = htons(ETH_P_IPV6);
  46
  47        return true;
  48}
  49
  50void nf_dup_ipv6(struct net *net, struct sk_buff *skb, unsigned int hooknum,
  51                 const struct in6_addr *gw, int oif)
  52{
  53        if (this_cpu_read(nf_skb_duplicated))
  54                return;
  55        skb = pskb_copy(skb, GFP_ATOMIC);
  56        if (skb == NULL)
  57                return;
  58
  59#if IS_ENABLED(CONFIG_NF_CONNTRACK)
  60        nf_reset(skb);
  61        nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
  62#endif
  63        if (hooknum == NF_INET_PRE_ROUTING ||
  64            hooknum == NF_INET_LOCAL_IN) {
  65                struct ipv6hdr *iph = ipv6_hdr(skb);
  66                --iph->hop_limit;
  67        }
  68        if (nf_dup_ipv6_route(net, skb, gw, oif)) {
  69                __this_cpu_write(nf_skb_duplicated, true);
  70                ip6_local_out(net, skb->sk, skb);
  71                __this_cpu_write(nf_skb_duplicated, false);
  72        } else {
  73                kfree_skb(skb);
  74        }
  75}
  76EXPORT_SYMBOL_GPL(nf_dup_ipv6);
  77
  78MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
  79MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  80MODULE_DESCRIPTION("nf_dup_ipv6: IPv6 packet duplication");
  81MODULE_LICENSE("GPL");
  82