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
26static unsigned int inet6_ehashfn(struct net *net,
27				  const struct in6_addr *laddr,
28				  const u16 lport,
29				  const struct in6_addr *faddr,
30				  const __be16 fport)
31{
32	static u32 inet6_ehash_secret __read_mostly;
33	static u32 ipv6_hash_secret __read_mostly;
34
35	u32 lhash, fhash;
36
37	net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
38	net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
39
40	lhash = (__force u32)laddr->s6_addr32[3];
41	fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);
42
43	return __inet6_ehashfn(lhash, lport, fhash, fport,
44			       inet6_ehash_secret + net_hash_mix(net));
45}
46
47static int inet6_sk_ehashfn(const struct sock *sk)
48{
49	const struct inet_sock *inet = inet_sk(sk);
50	const struct in6_addr *laddr = &sk->sk_v6_rcv_saddr;
51	const struct in6_addr *faddr = &sk->sk_v6_daddr;
52	const __u16 lport = inet->inet_num;
53	const __be16 fport = inet->inet_dport;
54	struct net *net = sock_net(sk);
55
56	return inet6_ehashfn(net, laddr, lport, faddr, fport);
57}
58
59int __inet6_hash(struct sock *sk, struct inet_timewait_sock *tw)
60{
61	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
62	int twrefcnt = 0;
63
64	WARN_ON(!sk_unhashed(sk));
65
66	if (sk->sk_state == TCP_LISTEN) {
67		struct inet_listen_hashbucket *ilb;
68
69		ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
70		spin_lock(&ilb->lock);
71		__sk_nulls_add_node_rcu(sk, &ilb->head);
72		spin_unlock(&ilb->lock);
73	} else {
74		unsigned int hash;
75		struct hlist_nulls_head *list;
76		spinlock_t *lock;
77
78		sk->sk_hash = hash = inet6_sk_ehashfn(sk);
79		list = &inet_ehash_bucket(hashinfo, hash)->chain;
80		lock = inet_ehash_lockp(hashinfo, hash);
81		spin_lock(lock);
82		__sk_nulls_add_node_rcu(sk, list);
83		if (tw) {
84			WARN_ON(sk->sk_hash != tw->tw_hash);
85			twrefcnt = inet_twsk_unhash(tw);
86		}
87		spin_unlock(lock);
88	}
89
90	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
91	return twrefcnt;
92}
93EXPORT_SYMBOL(__inet6_hash);
94
95/*
96 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
97 * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
98 *
99 * The sockhash lock must be held as a reader here.
100 */
101struct sock *__inet6_lookup_established(struct net *net,
102					struct inet_hashinfo *hashinfo,
103					   const struct in6_addr *saddr,
104					   const __be16 sport,
105					   const struct in6_addr *daddr,
106					   const u16 hnum,
107					   const int dif)
108{
109	struct sock *sk;
110	const struct hlist_nulls_node *node;
111	const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
112	/* Optimize here for direct hit, only listening connections can
113	 * have wildcards anyways.
114	 */
115	unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
116	unsigned int slot = hash & hashinfo->ehash_mask;
117	struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
118
119
120	rcu_read_lock();
121begin:
122	sk_nulls_for_each_rcu(sk, node, &head->chain) {
123		if (sk->sk_hash != hash)
124			continue;
125		if (!INET6_MATCH(sk, net, saddr, daddr, ports, dif))
126			continue;
127		if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
128			goto out;
129
130		if (unlikely(!INET6_MATCH(sk, net, saddr, daddr, ports, dif))) {
131			sock_gen_put(sk);
132			goto begin;
133		}
134		goto found;
135	}
136	if (get_nulls_value(node) != slot)
137		goto begin;
138out:
139	sk = NULL;
140found:
141	rcu_read_unlock();
142	return sk;
143}
144EXPORT_SYMBOL(__inet6_lookup_established);
145
146static inline int compute_score(struct sock *sk, struct net *net,
147				const unsigned short hnum,
148				const struct in6_addr *daddr,
149				const int dif)
150{
151	int score = -1;
152
153	if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
154	    sk->sk_family == PF_INET6) {
155
156		score = 1;
157		if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
158			if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
159				return -1;
160			score++;
161		}
162		if (sk->sk_bound_dev_if) {
163			if (sk->sk_bound_dev_if != dif)
164				return -1;
165			score++;
166		}
167	}
168	return score;
169}
170
171struct sock *inet6_lookup_listener(struct net *net,
172		struct inet_hashinfo *hashinfo, const struct in6_addr *saddr,
173		const __be16 sport, const struct in6_addr *daddr,
174		const unsigned short hnum, const int dif)
175{
176	struct sock *sk;
177	const struct hlist_nulls_node *node;
178	struct sock *result;
179	int score, hiscore, matches = 0, reuseport = 0;
180	u32 phash = 0;
181	unsigned int hash = inet_lhashfn(net, hnum);
182	struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
183
184	rcu_read_lock();
185begin:
186	result = NULL;
187	hiscore = 0;
188	sk_nulls_for_each(sk, node, &ilb->head) {
189		score = compute_score(sk, net, hnum, daddr, dif);
190		if (score > hiscore) {
191			hiscore = score;
192			result = sk;
193			reuseport = sk->sk_reuseport;
194			if (reuseport) {
195				phash = inet6_ehashfn(net, daddr, hnum,
196						      saddr, sport);
197				matches = 1;
198			}
199		} else if (score == hiscore && reuseport) {
200			matches++;
201			if (reciprocal_scale(phash, matches) == 0)
202				result = sk;
203			phash = next_pseudo_random32(phash);
204		}
205	}
206	/*
207	 * if the nulls value we got at the end of this lookup is
208	 * not the expected one, we must restart lookup.
209	 * We probably met an item that was moved to another chain.
210	 */
211	if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
212		goto begin;
213	if (result) {
214		if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
215			result = NULL;
216		else if (unlikely(compute_score(result, net, hnum, daddr,
217				  dif) < hiscore)) {
218			sock_put(result);
219			goto begin;
220		}
221	}
222	rcu_read_unlock();
223	return result;
224}
225EXPORT_SYMBOL_GPL(inet6_lookup_listener);
226
227struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
228			  const struct in6_addr *saddr, const __be16 sport,
229			  const struct in6_addr *daddr, const __be16 dport,
230			  const int dif)
231{
232	struct sock *sk;
233
234	local_bh_disable();
235	sk = __inet6_lookup(net, hashinfo, saddr, sport, daddr, ntohs(dport), dif);
236	local_bh_enable();
237
238	return sk;
239}
240EXPORT_SYMBOL_GPL(inet6_lookup);
241
242static int __inet6_check_established(struct inet_timewait_death_row *death_row,
243				     struct sock *sk, const __u16 lport,
244				     struct inet_timewait_sock **twp)
245{
246	struct inet_hashinfo *hinfo = death_row->hashinfo;
247	struct inet_sock *inet = inet_sk(sk);
248	const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
249	const struct in6_addr *saddr = &sk->sk_v6_daddr;
250	const int dif = sk->sk_bound_dev_if;
251	const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
252	struct net *net = sock_net(sk);
253	const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
254						inet->inet_dport);
255	struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
256	spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
257	struct sock *sk2;
258	const struct hlist_nulls_node *node;
259	struct inet_timewait_sock *tw = NULL;
260	int twrefcnt = 0;
261
262	spin_lock(lock);
263
264	sk_nulls_for_each(sk2, node, &head->chain) {
265		if (sk2->sk_hash != hash)
266			continue;
267
268		if (likely(INET6_MATCH(sk2, net, saddr, daddr, ports, dif))) {
269			if (sk2->sk_state == TCP_TIME_WAIT) {
270				tw = inet_twsk(sk2);
271				if (twsk_unique(sk, sk2, twp))
272					break;
273			}
274			goto not_unique;
275		}
276	}
277
278	/* Must record num and sport now. Otherwise we will see
279	 * in hash table socket with a funny identity.
280	 */
281	inet->inet_num = lport;
282	inet->inet_sport = htons(lport);
283	sk->sk_hash = hash;
284	WARN_ON(!sk_unhashed(sk));
285	__sk_nulls_add_node_rcu(sk, &head->chain);
286	if (tw) {
287		twrefcnt = inet_twsk_unhash(tw);
288		NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
289	}
290	spin_unlock(lock);
291	if (twrefcnt)
292		inet_twsk_put(tw);
293	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
294
295	if (twp) {
296		*twp = tw;
297	} else if (tw) {
298		/* Silly. Should hash-dance instead... */
299		inet_twsk_deschedule(tw, death_row);
300
301		inet_twsk_put(tw);
302	}
303	return 0;
304
305not_unique:
306	spin_unlock(lock);
307	return -EADDRNOTAVAIL;
308}
309
310static inline u32 inet6_sk_port_offset(const struct sock *sk)
311{
312	const struct inet_sock *inet = inet_sk(sk);
313
314	return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
315					  sk->sk_v6_daddr.s6_addr32,
316					  inet->inet_dport);
317}
318
319int inet6_hash_connect(struct inet_timewait_death_row *death_row,
320		       struct sock *sk)
321{
322	return __inet_hash_connect(death_row, sk, inet6_sk_port_offset(sk),
323			__inet6_check_established, __inet6_hash);
324}
325EXPORT_SYMBOL_GPL(inet6_hash_connect);
326