LXR linux/net/ipv6/netfilter/nf_dup

   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
  19static 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
  47void 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}
  73EXPORT_SYMBOL_GPL(nf_dup_ipv6);
  74
  75MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
  76MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  77MODULE_DESCRIPTION("nf_dup_ipv6: IPv6 packet duplication");
  78MODULE_LICENSE("GPL");
  79