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: &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(dst);
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 local_bh_disable();
51 if (current->in_nf_duplicate)
52 goto out;
53 skb = pskb_copy(skb, GFP_ATOMIC);
54 if (skb == NULL)
55 goto out;
56
57#if IS_ENABLED(CONFIG_NF_CONNTRACK)
58 nf_reset_ct(skb);
59 nf_ct_set(skb, NULL, info: IP_CT_UNTRACKED);
60#endif
61 if (hooknum == NF_INET_PRE_ROUTING ||
62 hooknum == NF_INET_LOCAL_IN) {
63 struct ipv6hdr *iph = ipv6_hdr(skb);
64 --iph->hop_limit;
65 }
66 if (nf_dup_ipv6_route(net, skb, gw, oif)) {
67 current->in_nf_duplicate = true;
68 ip6_local_out(net, sk: skb->sk, skb);
69 current->in_nf_duplicate = false;
70 } else {
71 kfree_skb(skb);
72 }
73out:
74 local_bh_enable();
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

source code of linux/net/ipv6/netfilter/nf_dup_ipv6.c