1// SPDX-License-Identifier: GPL-2.0-only
2#include <net/netfilter/nf_tproxy.h>
3#include <linux/module.h>
4#include <net/inet6_hashtables.h>
5#include <net/addrconf.h>
6#include <net/udp.h>
7#include <net/tcp.h>
8
9const struct in6_addr *
10nf_tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
11	      const struct in6_addr *daddr)
12{
13	struct inet6_dev *indev;
14	struct inet6_ifaddr *ifa;
15	struct in6_addr *laddr;
16
17	if (!ipv6_addr_any(user_laddr))
18		return user_laddr;
19	laddr = NULL;
20
21	indev = __in6_dev_get(skb->dev);
22	if (indev) {
23		read_lock_bh(&indev->lock);
24		list_for_each_entry(ifa, &indev->addr_list, if_list) {
25			if (ifa->flags & (IFA_F_TENTATIVE | IFA_F_DEPRECATED))
26				continue;
27
28			laddr = &ifa->addr;
29			break;
30		}
31		read_unlock_bh(&indev->lock);
32	}
33
34	return laddr ? laddr : daddr;
35}
36EXPORT_SYMBOL_GPL(nf_tproxy_laddr6);
37
38struct sock *
39nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
40			 struct net *net,
41			 const struct in6_addr *laddr,
42			 const __be16 lport,
43			 struct sock *sk)
44{
45	const struct ipv6hdr *iph = ipv6_hdr(skb);
46	struct tcphdr _hdr, *hp;
47
48	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
49	if (hp == NULL) {
50		inet_twsk_put(inet_twsk(sk));
51		return NULL;
52	}
53
54	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
55		/* SYN to a TIME_WAIT socket, we'd rather redirect it
56		 * to a listener socket if there's one */
57		struct sock *sk2;
58
59		sk2 = nf_tproxy_get_sock_v6(net, skb, thoff, tproto,
60					    &iph->saddr,
61					    nf_tproxy_laddr6(skb, laddr, &iph->daddr),
62					    hp->source,
63					    lport ? lport : hp->dest,
64					    skb->dev, NF_TPROXY_LOOKUP_LISTENER);
65		if (sk2) {
66			nf_tproxy_twsk_deschedule_put(inet_twsk(sk));
67			sk = sk2;
68		}
69	}
70
71	return sk;
72}
73EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait6);
74
75struct sock *
76nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff,
77		      const u8 protocol,
78		      const struct in6_addr *saddr, const struct in6_addr *daddr,
79		      const __be16 sport, const __be16 dport,
80		      const struct net_device *in,
81		      const enum nf_tproxy_lookup_t lookup_type)
82{
83	struct inet_hashinfo *hinfo = net->ipv4.tcp_death_row.hashinfo;
84	struct sock *sk;
85
86	switch (protocol) {
87	case IPPROTO_TCP: {
88		struct tcphdr _hdr, *hp;
89
90		hp = skb_header_pointer(skb, thoff,
91					sizeof(struct tcphdr), &_hdr);
92		if (hp == NULL)
93			return NULL;
94
95		switch (lookup_type) {
96		case NF_TPROXY_LOOKUP_LISTENER:
97			sk = inet6_lookup_listener(net, hinfo, skb,
98						   thoff + __tcp_hdrlen(hp),
99						   saddr, sport,
100						   daddr, ntohs(dport),
101						   in->ifindex, 0);
102
103			if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
104				sk = NULL;
105			/* NOTE: we return listeners even if bound to
106			 * 0.0.0.0, those are filtered out in
107			 * xt_socket, since xt_TPROXY needs 0 bound
108			 * listeners too
109			 */
110			break;
111		case NF_TPROXY_LOOKUP_ESTABLISHED:
112			sk = __inet6_lookup_established(net, hinfo, saddr, sport, daddr,
113							ntohs(dport), in->ifindex, 0);
114			break;
115		default:
116			BUG();
117		}
118		break;
119		}
120	case IPPROTO_UDP:
121		sk = udp6_lib_lookup(net, saddr, sport, daddr, dport,
122				     in->ifindex);
123		if (sk) {
124			int connected = (sk->sk_state == TCP_ESTABLISHED);
125			int wildcard = ipv6_addr_any(&sk->sk_v6_rcv_saddr);
126
127			/* NOTE: we return listeners even if bound to
128			 * 0.0.0.0, those are filtered out in
129			 * xt_socket, since xt_TPROXY needs 0 bound
130			 * listeners too
131			 */
132			if ((lookup_type == NF_TPROXY_LOOKUP_ESTABLISHED && (!connected || wildcard)) ||
133			    (lookup_type == NF_TPROXY_LOOKUP_LISTENER && connected)) {
134				sock_put(sk);
135				sk = NULL;
136			}
137		}
138		break;
139	default:
140		WARN_ON(1);
141		sk = NULL;
142	}
143
144	pr_debug("tproxy socket lookup: proto %u %pI6:%u -> %pI6:%u, lookup type: %d, sock %p\n",
145		 protocol, saddr, ntohs(sport), daddr, ntohs(dport), lookup_type, sk);
146
147	return sk;
148}
149EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v6);
150
151MODULE_LICENSE("GPL");
152MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs");
153MODULE_DESCRIPTION("Netfilter IPv6 transparent proxy support");
154