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 * Authors: Lotsa people, from code originally in tcp
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 */
13
14#ifndef _INET_HASHTABLES_H
15#define _INET_HASHTABLES_H
16
17
18#include <linux/interrupt.h>
19#include <linux/ip.h>
20#include <linux/ipv6.h>
21#include <linux/list.h>
22#include <linux/slab.h>
23#include <linux/socket.h>
24#include <linux/spinlock.h>
25#include <linux/types.h>
26#include <linux/wait.h>
27
28#include <net/inet_connection_sock.h>
29#include <net/inet_sock.h>
30#include <net/sock.h>
31#include <net/route.h>
32#include <net/tcp_states.h>
33#include <net/netns/hash.h>
34
35#include <linux/refcount.h>
36#include <asm/byteorder.h>
37
38/* This is for all connections with a full identity, no wildcards.
39 * The 'e' prefix stands for Establish, but we really put all sockets
40 * but LISTEN ones.
41 */
42struct inet_ehash_bucket {
43 struct hlist_nulls_head chain;
44};
45
46/* There are a few simple rules, which allow for local port reuse by
47 * an application. In essence:
48 *
49 * 1) Sockets bound to different interfaces may share a local port.
50 * Failing that, goto test 2.
51 * 2) If all sockets have sk->sk_reuse set, and none of them are in
52 * TCP_LISTEN state, the port may be shared.
53 * Failing that, goto test 3.
54 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
55 * address, and none of them are the same, the port may be
56 * shared.
57 * Failing this, the port cannot be shared.
58 *
59 * The interesting point, is test #2. This is what an FTP server does
60 * all day. To optimize this case we use a specific flag bit defined
61 * below. As we add sockets to a bind bucket list, we perform a
62 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
63 * As long as all sockets added to a bind bucket pass this test,
64 * the flag bit will be set.
65 * The resulting situation is that tcp_v[46]_verify_bind() can just check
66 * for this flag bit, if it is set and the socket trying to bind has
67 * sk->sk_reuse set, we don't even have to walk the owners list at all,
68 * we return that it is ok to bind this socket to the requested local port.
69 *
70 * Sounds like a lot of work, but it is worth it. In a more naive
71 * implementation (ie. current FreeBSD etc.) the entire list of ports
72 * must be walked for each data port opened by an ftp server. Needless
73 * to say, this does not scale at all. With a couple thousand FTP
74 * users logged onto your box, isn't it nice to know that new data
75 * ports are created in O(1) time? I thought so. ;-) -DaveM
76 */
77#define FASTREUSEPORT_ANY 1
78#define FASTREUSEPORT_STRICT 2
79
80struct inet_bind_bucket {
81 possible_net_t ib_net;
82 unsigned short port;
83 signed char fastreuse;
84 signed char fastreuseport;
85 kuid_t fastuid;
86#if IS_ENABLED(CONFIG_IPV6)
87 struct in6_addr fast_v6_rcv_saddr;
88#endif
89 __be32 fast_rcv_saddr;
90 unsigned short fast_sk_family;
91 bool fast_ipv6_only;
92 struct hlist_node node;
93 struct hlist_head owners;
94};
95
96static inline struct net *ib_net(struct inet_bind_bucket *ib)
97{
98 return read_pnet(&ib->ib_net);
99}
100
101#define inet_bind_bucket_for_each(tb, head) \
102 hlist_for_each_entry(tb, head, node)
103
104struct inet_bind_hashbucket {
105 spinlock_t lock;
106 struct hlist_head chain;
107};
108
109/*
110 * Sockets can be hashed in established or listening table
111 */
112struct inet_listen_hashbucket {
113 spinlock_t lock;
114 unsigned int count;
115 struct hlist_head head;
116};
117
118/* This is for listening sockets, thus all sockets which possess wildcards. */
119#define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
120
121struct inet_hashinfo {
122 /* This is for sockets with full identity only. Sockets here will
123 * always be without wildcards and will have the following invariant:
124 *
125 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
126 *
127 */
128 struct inet_ehash_bucket *ehash;
129 spinlock_t *ehash_locks;
130 unsigned int ehash_mask;
131 unsigned int ehash_locks_mask;
132
133 /* Ok, let's try this, I give up, we do need a local binding
134 * TCP hash as well as the others for fast bind/connect.
135 */
136 struct kmem_cache *bind_bucket_cachep;
137 struct inet_bind_hashbucket *bhash;
138 unsigned int bhash_size;
139
140 /* The 2nd listener table hashed by local port and address */
141 unsigned int lhash2_mask;
142 struct inet_listen_hashbucket *lhash2;
143
144 /* All the above members are written once at bootup and
145 * never written again _or_ are predominantly read-access.
146 *
147 * Now align to a new cache line as all the following members
148 * might be often dirty.
149 */
150 /* All sockets in TCP_LISTEN state will be in listening_hash.
151 * This is the only table where wildcard'd TCP sockets can
152 * exist. listening_hash is only hashed by local port number.
153 * If lhash2 is initialized, the same socket will also be hashed
154 * to lhash2 by port and address.
155 */
156 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE]
157 ____cacheline_aligned_in_smp;
158};
159
160#define inet_lhash2_for_each_icsk_rcu(__icsk, list) \
161 hlist_for_each_entry_rcu(__icsk, list, icsk_listen_portaddr_node)
162
163static inline struct inet_listen_hashbucket *
164inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
165{
166 return &h->lhash2[hash & h->lhash2_mask];
167}
168
169static inline struct inet_ehash_bucket *inet_ehash_bucket(
170 struct inet_hashinfo *hashinfo,
171 unsigned int hash)
172{
173 return &hashinfo->ehash[hash & hashinfo->ehash_mask];
174}
175
176static inline spinlock_t *inet_ehash_lockp(
177 struct inet_hashinfo *hashinfo,
178 unsigned int hash)
179{
180 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
181}
182
183int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
184
185static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
186{
187 kvfree(hashinfo->ehash_locks);
188 hashinfo->ehash_locks = NULL;
189}
190
191struct inet_bind_bucket *
192inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
193 struct inet_bind_hashbucket *head,
194 const unsigned short snum);
195void inet_bind_bucket_destroy(struct kmem_cache *cachep,
196 struct inet_bind_bucket *tb);
197
198static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
199 const u32 bhash_size)
200{
201 return (lport + net_hash_mix(net)) & (bhash_size - 1);
202}
203
204void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
205 const unsigned short snum);
206
207/* These can have wildcards, don't try too hard. */
208static inline u32 inet_lhashfn(const struct net *net, const unsigned short num)
209{
210 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
211}
212
213static inline int inet_sk_listen_hashfn(const struct sock *sk)
214{
215 return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
216}
217
218/* Caller must disable local BH processing. */
219int __inet_inherit_port(const struct sock *sk, struct sock *child);
220
221void inet_put_port(struct sock *sk);
222
223void inet_hashinfo_init(struct inet_hashinfo *h);
224void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
225 unsigned long numentries, int scale,
226 unsigned long low_limit,
227 unsigned long high_limit);
228
229bool inet_ehash_insert(struct sock *sk, struct sock *osk);
230bool inet_ehash_nolisten(struct sock *sk, struct sock *osk);
231int __inet_hash(struct sock *sk, struct sock *osk);
232int inet_hash(struct sock *sk);
233void inet_unhash(struct sock *sk);
234
235struct sock *__inet_lookup_listener(struct net *net,
236 struct inet_hashinfo *hashinfo,
237 struct sk_buff *skb, int doff,
238 const __be32 saddr, const __be16 sport,
239 const __be32 daddr,
240 const unsigned short hnum,
241 const int dif, const int sdif);
242
243static inline struct sock *inet_lookup_listener(struct net *net,
244 struct inet_hashinfo *hashinfo,
245 struct sk_buff *skb, int doff,
246 __be32 saddr, __be16 sport,
247 __be32 daddr, __be16 dport, int dif, int sdif)
248{
249 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
250 daddr, ntohs(dport), dif, sdif);
251}
252
253/* Socket demux engine toys. */
254/* What happens here is ugly; there's a pair of adjacent fields in
255 struct inet_sock; __be16 dport followed by __u16 num. We want to
256 search by pair, so we combine the keys into a single 32bit value
257 and compare with 32bit value read from &...->dport. Let's at least
258 make sure that it's not mixed with anything else...
259 On 64bit targets we combine comparisons with pair of adjacent __be32
260 fields in the same way.
261*/
262#ifdef __BIG_ENDIAN
263#define INET_COMBINED_PORTS(__sport, __dport) \
264 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
265#else /* __LITTLE_ENDIAN */
266#define INET_COMBINED_PORTS(__sport, __dport) \
267 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
268#endif
269
270#if (BITS_PER_LONG == 64)
271#ifdef __BIG_ENDIAN
272#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
273 const __addrpair __name = (__force __addrpair) ( \
274 (((__force __u64)(__be32)(__saddr)) << 32) | \
275 ((__force __u64)(__be32)(__daddr)))
276#else /* __LITTLE_ENDIAN */
277#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
278 const __addrpair __name = (__force __addrpair) ( \
279 (((__force __u64)(__be32)(__daddr)) << 32) | \
280 ((__force __u64)(__be32)(__saddr)))
281#endif /* __BIG_ENDIAN */
282#define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
283 (((__sk)->sk_portpair == (__ports)) && \
284 ((__sk)->sk_addrpair == (__cookie)) && \
285 (!(__sk)->sk_bound_dev_if || \
286 ((__sk)->sk_bound_dev_if == (__dif)) || \
287 ((__sk)->sk_bound_dev_if == (__sdif))) && \
288 net_eq(sock_net(__sk), (__net)))
289#else /* 32-bit arch */
290#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
291 const int __name __deprecated __attribute__((unused))
292
293#define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
294 (((__sk)->sk_portpair == (__ports)) && \
295 ((__sk)->sk_daddr == (__saddr)) && \
296 ((__sk)->sk_rcv_saddr == (__daddr)) && \
297 (!(__sk)->sk_bound_dev_if || \
298 ((__sk)->sk_bound_dev_if == (__dif)) || \
299 ((__sk)->sk_bound_dev_if == (__sdif))) && \
300 net_eq(sock_net(__sk), (__net)))
301#endif /* 64-bit arch */
302
303/* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
304 * not check it for lookups anymore, thanks Alexey. -DaveM
305 */
306struct sock *__inet_lookup_established(struct net *net,
307 struct inet_hashinfo *hashinfo,
308 const __be32 saddr, const __be16 sport,
309 const __be32 daddr, const u16 hnum,
310 const int dif, const int sdif);
311
312static inline struct sock *
313 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
314 const __be32 saddr, const __be16 sport,
315 const __be32 daddr, const __be16 dport,
316 const int dif)
317{
318 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
319 ntohs(dport), dif, 0);
320}
321
322static inline struct sock *__inet_lookup(struct net *net,
323 struct inet_hashinfo *hashinfo,
324 struct sk_buff *skb, int doff,
325 const __be32 saddr, const __be16 sport,
326 const __be32 daddr, const __be16 dport,
327 const int dif, const int sdif,
328 bool *refcounted)
329{
330 u16 hnum = ntohs(dport);
331 struct sock *sk;
332
333 sk = __inet_lookup_established(net, hashinfo, saddr, sport,
334 daddr, hnum, dif, sdif);
335 *refcounted = true;
336 if (sk)
337 return sk;
338 *refcounted = false;
339 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
340 sport, daddr, hnum, dif, sdif);
341}
342
343static inline struct sock *inet_lookup(struct net *net,
344 struct inet_hashinfo *hashinfo,
345 struct sk_buff *skb, int doff,
346 const __be32 saddr, const __be16 sport,
347 const __be32 daddr, const __be16 dport,
348 const int dif)
349{
350 struct sock *sk;
351 bool refcounted;
352
353 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
354 dport, dif, 0, &refcounted);
355
356 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
357 sk = NULL;
358 return sk;
359}
360
361static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
362 struct sk_buff *skb,
363 int doff,
364 const __be16 sport,
365 const __be16 dport,
366 const int sdif,
367 bool *refcounted)
368{
369 struct sock *sk = skb_steal_sock(skb);
370 const struct iphdr *iph = ip_hdr(skb);
371
372 *refcounted = true;
373 if (sk)
374 return sk;
375
376 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
377 doff, iph->saddr, sport,
378 iph->daddr, dport, inet_iif(skb), sdif,
379 refcounted);
380}
381
382u32 inet6_ehashfn(const struct net *net,
383 const struct in6_addr *laddr, const u16 lport,
384 const struct in6_addr *faddr, const __be16 fport);
385
386static inline void sk_daddr_set(struct sock *sk, __be32 addr)
387{
388 sk->sk_daddr = addr; /* alias of inet_daddr */
389#if IS_ENABLED(CONFIG_IPV6)
390 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr);
391#endif
392}
393
394static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
395{
396 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
397#if IS_ENABLED(CONFIG_IPV6)
398 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr);
399#endif
400}
401
402int __inet_hash_connect(struct inet_timewait_death_row *death_row,
403 struct sock *sk, u32 port_offset,
404 int (*check_established)(struct inet_timewait_death_row *,
405 struct sock *, __u16,
406 struct inet_timewait_sock **));
407
408int inet_hash_connect(struct inet_timewait_death_row *death_row,
409 struct sock *sk);
410#endif /* _INET_HASHTABLES_H */
411