root/net/ipv6/netfilter/nf_dup_ipv6.c

DEFINITIONS

1. nf_dup_ipv6_route
2. nf_dup_ipv6

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * (C) 2007 by Sebastian Claßen <sebastian.classen@freenet.ag>
   4  * (C) 2007-2010 by Jan Engelhardt <jengelh@medozas.de>
   5  *
   6  * Extracted from xt_TEE.c
   7  */
   8 #include <linux/module.h>
   9 #include <linux/percpu.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/netfilter.h>
  12 #include <net/ipv6.h>
  13 #include <net/ip6_route.h>
  14 #include <net/netfilter/ipv6/nf_dup_ipv6.h>
  15 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  16 #include <net/netfilter/nf_conntrack.h>
  17 #endif
  18 
  19 static bool nf_dup_ipv6_route(struct net *net, struct sk_buff *skb,
  20                               const struct in6_addr *gw, int oif)
  21 {
  22         const struct ipv6hdr *iph = ipv6_hdr(skb);
  23         struct dst_entry *dst;
  24         struct flowi6 fl6;
  25 
  26         memset(&fl6, 0, sizeof(fl6));
  27         if (oif != -1)
  28                 fl6.flowi6_oif = oif;
  29 
  30         fl6.daddr = *gw;
  31         fl6.flowlabel = (__force __be32)(((iph->flow_lbl[0] & 0xF) << 16) |
  32                         (iph->flow_lbl[1] << 8) | iph->flow_lbl[2]);
  33         fl6.flowi6_flags = FLOWI_FLAG_KNOWN_NH;
  34         dst = ip6_route_output(net, NULL, &fl6);
  35         if (dst->error) {
  36                 dst_release(dst);
  37                 return false;
  38         }
  39         skb_dst_drop(skb);
  40         skb_dst_set(skb, dst);
  41         skb->dev      = dst->dev;
  42         skb->protocol = htons(ETH_P_IPV6);
  43 
  44         return true;
  45 }
  46 
  47 void nf_dup_ipv6(struct net *net, struct sk_buff *skb, unsigned int hooknum,
  48                  const struct in6_addr *gw, int oif)
  49 {
  50         if (this_cpu_read(nf_skb_duplicated))
  51                 return;
  52         skb = pskb_copy(skb, GFP_ATOMIC);
  53         if (skb == NULL)
  54                 return;
  55 
  56 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  57         nf_reset_ct(skb);
  58         nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
  59 #endif
  60         if (hooknum == NF_INET_PRE_ROUTING ||
  61             hooknum == NF_INET_LOCAL_IN) {
  62                 struct ipv6hdr *iph = ipv6_hdr(skb);
  63                 --iph->hop_limit;
  64         }
  65         if (nf_dup_ipv6_route(net, skb, gw, oif)) {
  66                 __this_cpu_write(nf_skb_duplicated, true);
  67                 ip6_local_out(net, skb->sk, skb);
  68                 __this_cpu_write(nf_skb_duplicated, false);
  69         } else {
  70                 kfree_skb(skb);
  71         }
  72 }
  73 EXPORT_SYMBOL_GPL(nf_dup_ipv6);
  74 
  75 MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
  76 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  77 MODULE_DESCRIPTION("nf_dup_ipv6: IPv6 packet duplication");
  78 MODULE_LICENSE("GPL");