1/*
2 * INET		An implementation of the TCP/IP protocol suite for the LINUX
3 *		operating system.  INET is implemented using the BSD Socket
4 *		interface as the means of communication with the user level.
5 *
6 *		Generic INET6 transport hashtables
7 *
8 * Authors:	Lotsa people, from code originally in tcp, generalised here
9 *		by Arnaldo Carvalho de Melo <acme@mandriva.com>
10 *
11 *	This program is free software; you can redistribute it and/or
12 *      modify it under the terms of the GNU General Public License
13 *      as published by the Free Software Foundation; either version
14 *      2 of the License, or (at your option) any later version.
15 */
16
17#include <linux/module.h>
18#include <linux/random.h>
19
20#include <net/inet_connection_sock.h>
21#include <net/inet_hashtables.h>
22#include <net/inet6_hashtables.h>
23#include <net/secure_seq.h>
24#include <net/ip.h>
25
26u32 inet6_ehashfn(const struct net *net,
27		  const struct in6_addr *laddr, const u16 lport,
28		  const struct in6_addr *faddr, const __be16 fport)
29{
30	static u32 inet6_ehash_secret __read_mostly;
31	static u32 ipv6_hash_secret __read_mostly;
32
33	u32 lhash, fhash;
34
35	net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
36	net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
37
38	lhash = (__force u32)laddr->s6_addr32[3];
39	fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);
40
41	return __inet6_ehashfn(lhash, lport, fhash, fport,
42			       inet6_ehash_secret + net_hash_mix(net));
43}
44
45/*
46 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
47 * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
48 *
49 * The sockhash lock must be held as a reader here.
50 */
51struct sock *__inet6_lookup_established(struct net *net,
52					struct inet_hashinfo *hashinfo,
53					   const struct in6_addr *saddr,
54					   const __be16 sport,
55					   const struct in6_addr *daddr,
56					   const u16 hnum,
57					   const int dif)
58{
59	struct sock *sk;
60	const struct hlist_nulls_node *node;
61	const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
62	/* Optimize here for direct hit, only listening connections can
63	 * have wildcards anyways.
64	 */
65	unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
66	unsigned int slot = hash & hashinfo->ehash_mask;
67	struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
68
69
70	rcu_read_lock();
71begin:
72	sk_nulls_for_each_rcu(sk, node, &head->chain) {
73		if (sk->sk_hash != hash)
74			continue;
75		if (!INET6_MATCH(sk, net, saddr, daddr, ports, dif))
76			continue;
77		if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
78			goto out;
79
80		if (unlikely(!INET6_MATCH(sk, net, saddr, daddr, ports, dif))) {
81			sock_gen_put(sk);
82			goto begin;
83		}
84		goto found;
85	}
86	if (get_nulls_value(node) != slot)
87		goto begin;
88out:
89	sk = NULL;
90found:
91	rcu_read_unlock();
92	return sk;
93}
94EXPORT_SYMBOL(__inet6_lookup_established);
95
96static inline int compute_score(struct sock *sk, struct net *net,
97				const unsigned short hnum,
98				const struct in6_addr *daddr,
99				const int dif)
100{
101	int score = -1;
102
103	if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
104	    sk->sk_family == PF_INET6) {
105
106		score = 1;
107		if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
108			if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
109				return -1;
110			score++;
111		}
112		if (sk->sk_bound_dev_if) {
113			if (sk->sk_bound_dev_if != dif)
114				return -1;
115			score++;
116		}
117	}
118	return score;
119}
120
121struct sock *inet6_lookup_listener(struct net *net,
122		struct inet_hashinfo *hashinfo, const struct in6_addr *saddr,
123		const __be16 sport, const struct in6_addr *daddr,
124		const unsigned short hnum, const int dif)
125{
126	struct sock *sk;
127	const struct hlist_nulls_node *node;
128	struct sock *result;
129	int score, hiscore, matches = 0, reuseport = 0;
130	u32 phash = 0;
131	unsigned int hash = inet_lhashfn(net, hnum);
132	struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
133
134	rcu_read_lock();
135begin:
136	result = NULL;
137	hiscore = 0;
138	sk_nulls_for_each(sk, node, &ilb->head) {
139		score = compute_score(sk, net, hnum, daddr, dif);
140		if (score > hiscore) {
141			hiscore = score;
142			result = sk;
143			reuseport = sk->sk_reuseport;
144			if (reuseport) {
145				phash = inet6_ehashfn(net, daddr, hnum,
146						      saddr, sport);
147				matches = 1;
148			}
149		} else if (score == hiscore && reuseport) {
150			matches++;
151			if (reciprocal_scale(phash, matches) == 0)
152				result = sk;
153			phash = next_pseudo_random32(phash);
154		}
155	}
156	/*
157	 * if the nulls value we got at the end of this lookup is
158	 * not the expected one, we must restart lookup.
159	 * We probably met an item that was moved to another chain.
160	 */
161	if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
162		goto begin;
163	if (result) {
164		if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
165			result = NULL;
166		else if (unlikely(compute_score(result, net, hnum, daddr,
167				  dif) < hiscore)) {
168			sock_put(result);
169			goto begin;
170		}
171	}
172	rcu_read_unlock();
173	return result;
174}
175EXPORT_SYMBOL_GPL(inet6_lookup_listener);
176
177struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
178			  const struct in6_addr *saddr, const __be16 sport,
179			  const struct in6_addr *daddr, const __be16 dport,
180			  const int dif)
181{
182	struct sock *sk;
183
184	local_bh_disable();
185	sk = __inet6_lookup(net, hashinfo, saddr, sport, daddr, ntohs(dport), dif);
186	local_bh_enable();
187
188	return sk;
189}
190EXPORT_SYMBOL_GPL(inet6_lookup);
191
192static int __inet6_check_established(struct inet_timewait_death_row *death_row,
193				     struct sock *sk, const __u16 lport,
194				     struct inet_timewait_sock **twp)
195{
196	struct inet_hashinfo *hinfo = death_row->hashinfo;
197	struct inet_sock *inet = inet_sk(sk);
198	const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
199	const struct in6_addr *saddr = &sk->sk_v6_daddr;
200	const int dif = sk->sk_bound_dev_if;
201	const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
202	struct net *net = sock_net(sk);
203	const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
204						inet->inet_dport);
205	struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
206	spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
207	struct sock *sk2;
208	const struct hlist_nulls_node *node;
209	struct inet_timewait_sock *tw = NULL;
210	int twrefcnt = 0;
211
212	spin_lock(lock);
213
214	sk_nulls_for_each(sk2, node, &head->chain) {
215		if (sk2->sk_hash != hash)
216			continue;
217
218		if (likely(INET6_MATCH(sk2, net, saddr, daddr, ports, dif))) {
219			if (sk2->sk_state == TCP_TIME_WAIT) {
220				tw = inet_twsk(sk2);
221				if (twsk_unique(sk, sk2, twp))
222					break;
223			}
224			goto not_unique;
225		}
226	}
227
228	/* Must record num and sport now. Otherwise we will see
229	 * in hash table socket with a funny identity.
230	 */
231	inet->inet_num = lport;
232	inet->inet_sport = htons(lport);
233	sk->sk_hash = hash;
234	WARN_ON(!sk_unhashed(sk));
235	__sk_nulls_add_node_rcu(sk, &head->chain);
236	if (tw) {
237		twrefcnt = inet_twsk_unhash(tw);
238		NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
239	}
240	spin_unlock(lock);
241	if (twrefcnt)
242		inet_twsk_put(tw);
243	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
244
245	if (twp) {
246		*twp = tw;
247	} else if (tw) {
248		/* Silly. Should hash-dance instead... */
249		inet_twsk_deschedule(tw);
250
251		inet_twsk_put(tw);
252	}
253	return 0;
254
255not_unique:
256	spin_unlock(lock);
257	return -EADDRNOTAVAIL;
258}
259
260static inline u32 inet6_sk_port_offset(const struct sock *sk)
261{
262	const struct inet_sock *inet = inet_sk(sk);
263
264	return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
265					  sk->sk_v6_daddr.s6_addr32,
266					  inet->inet_dport);
267}
268
269int inet6_hash_connect(struct inet_timewait_death_row *death_row,
270		       struct sock *sk)
271{
272	return __inet_hash_connect(death_row, sk, inet6_sk_port_offset(sk),
273				   __inet6_check_established);
274}
275EXPORT_SYMBOL_GPL(inet6_hash_connect);
276