xref: /openbmc/linux/net/ipv6/inet6_hashtables.c (revision a06c488d)
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 
26 u32 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  */
51 struct 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();
71 begin:
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;
88 out:
89 	sk = NULL;
90 found:
91 	rcu_read_unlock();
92 	return sk;
93 }
94 EXPORT_SYMBOL(__inet6_lookup_established);
95 
96 static 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 		if (sk->sk_incoming_cpu == raw_smp_processor_id())
118 			score++;
119 	}
120 	return score;
121 }
122 
123 struct sock *inet6_lookup_listener(struct net *net,
124 		struct inet_hashinfo *hashinfo, const struct in6_addr *saddr,
125 		const __be16 sport, const struct in6_addr *daddr,
126 		const unsigned short hnum, const int dif)
127 {
128 	struct sock *sk;
129 	const struct hlist_nulls_node *node;
130 	struct sock *result;
131 	int score, hiscore, matches = 0, reuseport = 0;
132 	u32 phash = 0;
133 	unsigned int hash = inet_lhashfn(net, hnum);
134 	struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
135 
136 	rcu_read_lock();
137 begin:
138 	result = NULL;
139 	hiscore = 0;
140 	sk_nulls_for_each(sk, node, &ilb->head) {
141 		score = compute_score(sk, net, hnum, daddr, dif);
142 		if (score > hiscore) {
143 			hiscore = score;
144 			result = sk;
145 			reuseport = sk->sk_reuseport;
146 			if (reuseport) {
147 				phash = inet6_ehashfn(net, daddr, hnum,
148 						      saddr, sport);
149 				matches = 1;
150 			}
151 		} else if (score == hiscore && reuseport) {
152 			matches++;
153 			if (reciprocal_scale(phash, matches) == 0)
154 				result = sk;
155 			phash = next_pseudo_random32(phash);
156 		}
157 	}
158 	/*
159 	 * if the nulls value we got at the end of this lookup is
160 	 * not the expected one, we must restart lookup.
161 	 * We probably met an item that was moved to another chain.
162 	 */
163 	if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
164 		goto begin;
165 	if (result) {
166 		if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
167 			result = NULL;
168 		else if (unlikely(compute_score(result, net, hnum, daddr,
169 				  dif) < hiscore)) {
170 			sock_put(result);
171 			goto begin;
172 		}
173 	}
174 	rcu_read_unlock();
175 	return result;
176 }
177 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
178 
179 struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
180 			  const struct in6_addr *saddr, const __be16 sport,
181 			  const struct in6_addr *daddr, const __be16 dport,
182 			  const int dif)
183 {
184 	struct sock *sk;
185 
186 	local_bh_disable();
187 	sk = __inet6_lookup(net, hashinfo, saddr, sport, daddr, ntohs(dport), dif);
188 	local_bh_enable();
189 
190 	return sk;
191 }
192 EXPORT_SYMBOL_GPL(inet6_lookup);
193 
194 static int __inet6_check_established(struct inet_timewait_death_row *death_row,
195 				     struct sock *sk, const __u16 lport,
196 				     struct inet_timewait_sock **twp)
197 {
198 	struct inet_hashinfo *hinfo = death_row->hashinfo;
199 	struct inet_sock *inet = inet_sk(sk);
200 	const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
201 	const struct in6_addr *saddr = &sk->sk_v6_daddr;
202 	const int dif = sk->sk_bound_dev_if;
203 	const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
204 	struct net *net = sock_net(sk);
205 	const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
206 						inet->inet_dport);
207 	struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
208 	spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
209 	struct sock *sk2;
210 	const struct hlist_nulls_node *node;
211 	struct inet_timewait_sock *tw = NULL;
212 
213 	spin_lock(lock);
214 
215 	sk_nulls_for_each(sk2, node, &head->chain) {
216 		if (sk2->sk_hash != hash)
217 			continue;
218 
219 		if (likely(INET6_MATCH(sk2, net, saddr, daddr, ports, dif))) {
220 			if (sk2->sk_state == TCP_TIME_WAIT) {
221 				tw = inet_twsk(sk2);
222 				if (twsk_unique(sk, sk2, twp))
223 					break;
224 			}
225 			goto not_unique;
226 		}
227 	}
228 
229 	/* Must record num and sport now. Otherwise we will see
230 	 * in hash table socket with a funny identity.
231 	 */
232 	inet->inet_num = lport;
233 	inet->inet_sport = htons(lport);
234 	sk->sk_hash = hash;
235 	WARN_ON(!sk_unhashed(sk));
236 	__sk_nulls_add_node_rcu(sk, &head->chain);
237 	if (tw) {
238 		sk_nulls_del_node_init_rcu((struct sock *)tw);
239 		NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
240 	}
241 	spin_unlock(lock);
242 	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
243 
244 	if (twp) {
245 		*twp = tw;
246 	} else if (tw) {
247 		/* Silly. Should hash-dance instead... */
248 		inet_twsk_deschedule_put(tw);
249 	}
250 	return 0;
251 
252 not_unique:
253 	spin_unlock(lock);
254 	return -EADDRNOTAVAIL;
255 }
256 
257 static u32 inet6_sk_port_offset(const struct sock *sk)
258 {
259 	const struct inet_sock *inet = inet_sk(sk);
260 
261 	return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
262 					  sk->sk_v6_daddr.s6_addr32,
263 					  inet->inet_dport);
264 }
265 
266 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
267 		       struct sock *sk)
268 {
269 	u32 port_offset = 0;
270 
271 	if (!inet_sk(sk)->inet_num)
272 		port_offset = inet6_sk_port_offset(sk);
273 	return __inet_hash_connect(death_row, sk, port_offset,
274 				   __inet6_check_established);
275 }
276 EXPORT_SYMBOL_GPL(inet6_hash_connect);
277