1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * (C) 2007 by Sebastian Cla��en <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 Cla��en <sebastian.classen@freenet.ag>");
76MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
77MODULE_DESCRIPTION("nf_dup_ipv6: IPv6 packet duplication");
78MODULE_LICENSE("GPL");
79