1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * Authors: Lotsa people, from code originally in tcp
8 */
9
10#ifndef _INET_HASHTABLES_H
11#define _INET_HASHTABLES_H
12
13
14#include <linux/interrupt.h>
15#include <linux/ip.h>
16#include <linux/ipv6.h>
17#include <linux/list.h>
18#include <linux/slab.h>
19#include <linux/socket.h>
20#include <linux/spinlock.h>
21#include <linux/types.h>
22#include <linux/wait.h>
23
24#include <net/inet_connection_sock.h>
25#include <net/inet_sock.h>
26#include <net/ip.h>
27#include <net/sock.h>
28#include <net/route.h>
29#include <net/tcp_states.h>
30#include <net/netns/hash.h>
31
32#include <linux/refcount.h>
33#include <asm/byteorder.h>
34
35/* This is for all connections with a full identity, no wildcards.
36 * The 'e' prefix stands for Establish, but we really put all sockets
37 * but LISTEN ones.
38 */
39struct inet_ehash_bucket {
40 struct hlist_nulls_head chain;
41};
42
43/* There are a few simple rules, which allow for local port reuse by
44 * an application. In essence:
45 *
46 * 1) Sockets bound to different interfaces may share a local port.
47 * Failing that, goto test 2.
48 * 2) If all sockets have sk->sk_reuse set, and none of them are in
49 * TCP_LISTEN state, the port may be shared.
50 * Failing that, goto test 3.
51 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
52 * address, and none of them are the same, the port may be
53 * shared.
54 * Failing this, the port cannot be shared.
55 *
56 * The interesting point, is test #2. This is what an FTP server does
57 * all day. To optimize this case we use a specific flag bit defined
58 * below. As we add sockets to a bind bucket list, we perform a
59 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
60 * As long as all sockets added to a bind bucket pass this test,
61 * the flag bit will be set.
62 * The resulting situation is that tcp_v[46]_verify_bind() can just check
63 * for this flag bit, if it is set and the socket trying to bind has
64 * sk->sk_reuse set, we don't even have to walk the owners list at all,
65 * we return that it is ok to bind this socket to the requested local port.
66 *
67 * Sounds like a lot of work, but it is worth it. In a more naive
68 * implementation (ie. current FreeBSD etc.) the entire list of ports
69 * must be walked for each data port opened by an ftp server. Needless
70 * to say, this does not scale at all. With a couple thousand FTP
71 * users logged onto your box, isn't it nice to know that new data
72 * ports are created in O(1) time? I thought so. ;-) -DaveM
73 */
74#define FASTREUSEPORT_ANY 1
75#define FASTREUSEPORT_STRICT 2
76
77struct inet_bind_bucket {
78 possible_net_t ib_net;
79 int l3mdev;
80 unsigned short port;
81 signed char fastreuse;
82 signed char fastreuseport;
83 kuid_t fastuid;
84#if IS_ENABLED(CONFIG_IPV6)
85 struct in6_addr fast_v6_rcv_saddr;
86#endif
87 __be32 fast_rcv_saddr;
88 unsigned short fast_sk_family;
89 bool fast_ipv6_only;
90 struct hlist_node node;
91 struct hlist_head owners;
92};
93
94struct inet_bind2_bucket {
95 possible_net_t ib_net;
96 int l3mdev;
97 unsigned short port;
98#if IS_ENABLED(CONFIG_IPV6)
99 unsigned short family;
100#endif
101 union {
102#if IS_ENABLED(CONFIG_IPV6)
103 struct in6_addr v6_rcv_saddr;
104#endif
105 __be32 rcv_saddr;
106 };
107 /* Node in the bhash2 inet_bind_hashbucket chain */
108 struct hlist_node node;
109 /* List of sockets hashed to this bucket */
110 struct hlist_head owners;
111 /* bhash has twsk in owners, but bhash2 has twsk in
112 * deathrow not to add a member in struct sock_common.
113 */
114 struct hlist_head deathrow;
115};
116
117static inline struct net *ib_net(const struct inet_bind_bucket *ib)
118{
119 return read_pnet(pnet: &ib->ib_net);
120}
121
122static inline struct net *ib2_net(const struct inet_bind2_bucket *ib)
123{
124 return read_pnet(pnet: &ib->ib_net);
125}
126
127#define inet_bind_bucket_for_each(tb, head) \
128 hlist_for_each_entry(tb, head, node)
129
130struct inet_bind_hashbucket {
131 spinlock_t lock;
132 struct hlist_head chain;
133};
134
135/* Sockets can be hashed in established or listening table.
136 * We must use different 'nulls' end-of-chain value for all hash buckets :
137 * A socket might transition from ESTABLISH to LISTEN state without
138 * RCU grace period. A lookup in ehash table needs to handle this case.
139 */
140#define LISTENING_NULLS_BASE (1U << 29)
141struct inet_listen_hashbucket {
142 spinlock_t lock;
143 struct hlist_nulls_head nulls_head;
144};
145
146/* This is for listening sockets, thus all sockets which possess wildcards. */
147#define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
148
149struct inet_hashinfo {
150 /* This is for sockets with full identity only. Sockets here will
151 * always be without wildcards and will have the following invariant:
152 *
153 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
154 *
155 */
156 struct inet_ehash_bucket *ehash;
157 spinlock_t *ehash_locks;
158 unsigned int ehash_mask;
159 unsigned int ehash_locks_mask;
160
161 /* Ok, let's try this, I give up, we do need a local binding
162 * TCP hash as well as the others for fast bind/connect.
163 */
164 struct kmem_cache *bind_bucket_cachep;
165 /* This bind table is hashed by local port */
166 struct inet_bind_hashbucket *bhash;
167 struct kmem_cache *bind2_bucket_cachep;
168 /* This bind table is hashed by local port and sk->sk_rcv_saddr (ipv4)
169 * or sk->sk_v6_rcv_saddr (ipv6). This 2nd bind table is used
170 * primarily for expediting bind conflict resolution.
171 */
172 struct inet_bind_hashbucket *bhash2;
173 unsigned int bhash_size;
174
175 /* The 2nd listener table hashed by local port and address */
176 unsigned int lhash2_mask;
177 struct inet_listen_hashbucket *lhash2;
178
179 bool pernet;
180} ____cacheline_aligned_in_smp;
181
182static inline struct inet_hashinfo *tcp_or_dccp_get_hashinfo(const struct sock *sk)
183{
184#if IS_ENABLED(CONFIG_IP_DCCP)
185 return sk->sk_prot->h.hashinfo ? :
186 sock_net(sk)->ipv4.tcp_death_row.hashinfo;
187#else
188 return sock_net(sk)->ipv4.tcp_death_row.hashinfo;
189#endif
190}
191
192static inline struct inet_listen_hashbucket *
193inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
194{
195 return &h->lhash2[hash & h->lhash2_mask];
196}
197
198static inline struct inet_ehash_bucket *inet_ehash_bucket(
199 struct inet_hashinfo *hashinfo,
200 unsigned int hash)
201{
202 return &hashinfo->ehash[hash & hashinfo->ehash_mask];
203}
204
205static inline spinlock_t *inet_ehash_lockp(
206 struct inet_hashinfo *hashinfo,
207 unsigned int hash)
208{
209 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
210}
211
212int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
213
214static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h)
215{
216 kfree(objp: h->lhash2);
217 h->lhash2 = NULL;
218}
219
220static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
221{
222 kvfree(addr: hashinfo->ehash_locks);
223 hashinfo->ehash_locks = NULL;
224}
225
226struct inet_hashinfo *inet_pernet_hashinfo_alloc(struct inet_hashinfo *hashinfo,
227 unsigned int ehash_entries);
228void inet_pernet_hashinfo_free(struct inet_hashinfo *hashinfo);
229
230struct inet_bind_bucket *
231inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
232 struct inet_bind_hashbucket *head,
233 const unsigned short snum, int l3mdev);
234void inet_bind_bucket_destroy(struct kmem_cache *cachep,
235 struct inet_bind_bucket *tb);
236
237bool inet_bind_bucket_match(const struct inet_bind_bucket *tb,
238 const struct net *net, unsigned short port,
239 int l3mdev);
240
241struct inet_bind2_bucket *
242inet_bind2_bucket_create(struct kmem_cache *cachep, struct net *net,
243 struct inet_bind_hashbucket *head,
244 unsigned short port, int l3mdev,
245 const struct sock *sk);
246
247void inet_bind2_bucket_destroy(struct kmem_cache *cachep,
248 struct inet_bind2_bucket *tb);
249
250struct inet_bind2_bucket *
251inet_bind2_bucket_find(const struct inet_bind_hashbucket *head,
252 const struct net *net,
253 unsigned short port, int l3mdev,
254 const struct sock *sk);
255
256bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb,
257 const struct net *net, unsigned short port,
258 int l3mdev, const struct sock *sk);
259
260static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
261 const u32 bhash_size)
262{
263 return (lport + net_hash_mix(net)) & (bhash_size - 1);
264}
265
266static inline struct inet_bind_hashbucket *
267inet_bhashfn_portaddr(const struct inet_hashinfo *hinfo, const struct sock *sk,
268 const struct net *net, unsigned short port)
269{
270 u32 hash;
271
272#if IS_ENABLED(CONFIG_IPV6)
273 if (sk->sk_family == AF_INET6)
274 hash = ipv6_portaddr_hash(net, addr6: &sk->sk_v6_rcv_saddr, port);
275 else
276#endif
277 hash = ipv4_portaddr_hash(net, saddr: sk->sk_rcv_saddr, port);
278 return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)];
279}
280
281struct inet_bind_hashbucket *
282inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, int port);
283
284/* This should be called whenever a socket's sk_rcv_saddr (ipv4) or
285 * sk_v6_rcv_saddr (ipv6) changes after it has been binded. The socket's
286 * rcv_saddr field should already have been updated when this is called.
287 */
288int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family);
289void inet_bhash2_reset_saddr(struct sock *sk);
290
291void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
292 struct inet_bind2_bucket *tb2, unsigned short port);
293
294/* Caller must disable local BH processing. */
295int __inet_inherit_port(const struct sock *sk, struct sock *child);
296
297void inet_put_port(struct sock *sk);
298
299void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
300 unsigned long numentries, int scale,
301 unsigned long low_limit,
302 unsigned long high_limit);
303int inet_hashinfo2_init_mod(struct inet_hashinfo *h);
304
305bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk);
306bool inet_ehash_nolisten(struct sock *sk, struct sock *osk,
307 bool *found_dup_sk);
308int __inet_hash(struct sock *sk, struct sock *osk);
309int inet_hash(struct sock *sk);
310void inet_unhash(struct sock *sk);
311
312struct sock *__inet_lookup_listener(struct net *net,
313 struct inet_hashinfo *hashinfo,
314 struct sk_buff *skb, int doff,
315 const __be32 saddr, const __be16 sport,
316 const __be32 daddr,
317 const unsigned short hnum,
318 const int dif, const int sdif);
319
320static inline struct sock *inet_lookup_listener(struct net *net,
321 struct inet_hashinfo *hashinfo,
322 struct sk_buff *skb, int doff,
323 __be32 saddr, __be16 sport,
324 __be32 daddr, __be16 dport, int dif, int sdif)
325{
326 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
327 daddr, ntohs(dport), dif, sdif);
328}
329
330/* Socket demux engine toys. */
331/* What happens here is ugly; there's a pair of adjacent fields in
332 struct inet_sock; __be16 dport followed by __u16 num. We want to
333 search by pair, so we combine the keys into a single 32bit value
334 and compare with 32bit value read from &...->dport. Let's at least
335 make sure that it's not mixed with anything else...
336 On 64bit targets we combine comparisons with pair of adjacent __be32
337 fields in the same way.
338*/
339#ifdef __BIG_ENDIAN
340#define INET_COMBINED_PORTS(__sport, __dport) \
341 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
342#else /* __LITTLE_ENDIAN */
343#define INET_COMBINED_PORTS(__sport, __dport) \
344 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
345#endif
346
347#ifdef __BIG_ENDIAN
348#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
349 const __addrpair __name = (__force __addrpair) ( \
350 (((__force __u64)(__be32)(__saddr)) << 32) | \
351 ((__force __u64)(__be32)(__daddr)))
352#else /* __LITTLE_ENDIAN */
353#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
354 const __addrpair __name = (__force __addrpair) ( \
355 (((__force __u64)(__be32)(__daddr)) << 32) | \
356 ((__force __u64)(__be32)(__saddr)))
357#endif /* __BIG_ENDIAN */
358
359static inline bool inet_match(struct net *net, const struct sock *sk,
360 const __addrpair cookie, const __portpair ports,
361 int dif, int sdif)
362{
363 if (!net_eq(net1: sock_net(sk), net2: net) ||
364 sk->sk_portpair != ports ||
365 sk->sk_addrpair != cookie)
366 return false;
367
368 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */
369 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif,
370 sdif);
371}
372
373/* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
374 * not check it for lookups anymore, thanks Alexey. -DaveM
375 */
376struct sock *__inet_lookup_established(struct net *net,
377 struct inet_hashinfo *hashinfo,
378 const __be32 saddr, const __be16 sport,
379 const __be32 daddr, const u16 hnum,
380 const int dif, const int sdif);
381
382typedef u32 (inet_ehashfn_t)(const struct net *net,
383 const __be32 laddr, const __u16 lport,
384 const __be32 faddr, const __be16 fport);
385
386inet_ehashfn_t inet_ehashfn;
387
388INDIRECT_CALLABLE_DECLARE(inet_ehashfn_t udp_ehashfn);
389
390struct sock *inet_lookup_reuseport(struct net *net, struct sock *sk,
391 struct sk_buff *skb, int doff,
392 __be32 saddr, __be16 sport,
393 __be32 daddr, unsigned short hnum,
394 inet_ehashfn_t *ehashfn);
395
396struct sock *inet_lookup_run_sk_lookup(struct net *net,
397 int protocol,
398 struct sk_buff *skb, int doff,
399 __be32 saddr, __be16 sport,
400 __be32 daddr, u16 hnum, const int dif,
401 inet_ehashfn_t *ehashfn);
402
403static inline struct sock *
404 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
405 const __be32 saddr, const __be16 sport,
406 const __be32 daddr, const __be16 dport,
407 const int dif)
408{
409 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
410 ntohs(dport), dif, sdif: 0);
411}
412
413static inline struct sock *__inet_lookup(struct net *net,
414 struct inet_hashinfo *hashinfo,
415 struct sk_buff *skb, int doff,
416 const __be32 saddr, const __be16 sport,
417 const __be32 daddr, const __be16 dport,
418 const int dif, const int sdif,
419 bool *refcounted)
420{
421 u16 hnum = ntohs(dport);
422 struct sock *sk;
423
424 sk = __inet_lookup_established(net, hashinfo, saddr, sport,
425 daddr, hnum, dif, sdif);
426 *refcounted = true;
427 if (sk)
428 return sk;
429 *refcounted = false;
430 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
431 sport, daddr, hnum, dif, sdif);
432}
433
434static inline struct sock *inet_lookup(struct net *net,
435 struct inet_hashinfo *hashinfo,
436 struct sk_buff *skb, int doff,
437 const __be32 saddr, const __be16 sport,
438 const __be32 daddr, const __be16 dport,
439 const int dif)
440{
441 struct sock *sk;
442 bool refcounted;
443
444 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
445 dport, dif, sdif: 0, refcounted: &refcounted);
446
447 if (sk && !refcounted && !refcount_inc_not_zero(r: &sk->sk_refcnt))
448 sk = NULL;
449 return sk;
450}
451
452static inline
453struct sock *inet_steal_sock(struct net *net, struct sk_buff *skb, int doff,
454 const __be32 saddr, const __be16 sport,
455 const __be32 daddr, const __be16 dport,
456 bool *refcounted, inet_ehashfn_t *ehashfn)
457{
458 struct sock *sk, *reuse_sk;
459 bool prefetched;
460
461 sk = skb_steal_sock(skb, refcounted, prefetched: &prefetched);
462 if (!sk)
463 return NULL;
464
465 if (!prefetched || !sk_fullsock(sk))
466 return sk;
467
468 if (sk->sk_protocol == IPPROTO_TCP) {
469 if (sk->sk_state != TCP_LISTEN)
470 return sk;
471 } else if (sk->sk_protocol == IPPROTO_UDP) {
472 if (sk->sk_state != TCP_CLOSE)
473 return sk;
474 } else {
475 return sk;
476 }
477
478 reuse_sk = inet_lookup_reuseport(net, sk, skb, doff,
479 saddr, sport, daddr, ntohs(dport),
480 ehashfn);
481 if (!reuse_sk)
482 return sk;
483
484 /* We've chosen a new reuseport sock which is never refcounted. This
485 * implies that sk also isn't refcounted.
486 */
487 WARN_ON_ONCE(*refcounted);
488
489 return reuse_sk;
490}
491
492static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
493 struct sk_buff *skb,
494 int doff,
495 const __be16 sport,
496 const __be16 dport,
497 const int sdif,
498 bool *refcounted)
499{
500 struct net *net = dev_net(dev: skb_dst(skb)->dev);
501 const struct iphdr *iph = ip_hdr(skb);
502 struct sock *sk;
503
504 sk = inet_steal_sock(net, skb, doff, saddr: iph->saddr, sport, daddr: iph->daddr, dport,
505 refcounted, ehashfn: inet_ehashfn);
506 if (IS_ERR(ptr: sk))
507 return NULL;
508 if (sk)
509 return sk;
510
511 return __inet_lookup(net, hashinfo, skb,
512 doff, saddr: iph->saddr, sport,
513 daddr: iph->daddr, dport, dif: inet_iif(skb), sdif,
514 refcounted);
515}
516
517static inline void sk_daddr_set(struct sock *sk, __be32 addr)
518{
519 sk->sk_daddr = addr; /* alias of inet_daddr */
520#if IS_ENABLED(CONFIG_IPV6)
521 ipv6_addr_set_v4mapped(addr, v4mapped: &sk->sk_v6_daddr);
522#endif
523}
524
525static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
526{
527 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
528#if IS_ENABLED(CONFIG_IPV6)
529 ipv6_addr_set_v4mapped(addr, v4mapped: &sk->sk_v6_rcv_saddr);
530#endif
531}
532
533int __inet_hash_connect(struct inet_timewait_death_row *death_row,
534 struct sock *sk, u64 port_offset,
535 int (*check_established)(struct inet_timewait_death_row *,
536 struct sock *, __u16,
537 struct inet_timewait_sock **));
538
539int inet_hash_connect(struct inet_timewait_death_row *death_row,
540 struct sock *sk);
541#endif /* _INET_HASHTABLES_H */
542

source code of linux/include/net/inet_hashtables.h