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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 bhash2;
92 struct rcu_head rcu;
93};
94
95struct inet_bind2_bucket {
96 possible_net_t ib_net;
97 int l3mdev;
98 unsigned short port;
99#if IS_ENABLED(CONFIG_IPV6)
100 unsigned short addr_type;
101 struct in6_addr v6_rcv_saddr;
102#define rcv_saddr v6_rcv_saddr.s6_addr32[3]
103#else
104 __be32 rcv_saddr;
105#endif
106 /* Node in the bhash2 inet_bind_hashbucket chain */
107 struct hlist_node node;
108 struct hlist_node bhash_node;
109 /* List of sockets hashed to this bucket */
110 struct hlist_head owners;
111 signed char fastreuse;
112 signed char fastreuseport;
113};
114
115static inline struct net *ib_net(const struct inet_bind_bucket *ib)
116{
117 return read_pnet(&ib->ib_net);
118}
119
120static inline struct net *ib2_net(const struct inet_bind2_bucket *ib)
121{
122 return read_pnet(&ib->ib_net);
123}
124
125#define inet_bind_bucket_for_each(tb, head) \
126 hlist_for_each_entry(tb, head, node)
127
128struct inet_bind_hashbucket {
129 spinlock_t lock;
130 struct hlist_head chain;
131};
132
133/* Sockets can be hashed in established or listening table.
134 * We must use different 'nulls' end-of-chain value for all hash buckets :
135 * A socket might transition from ESTABLISH to LISTEN state without
136 * RCU grace period. A lookup in ehash table needs to handle this case.
137 */
138#define LISTENING_NULLS_BASE (1U << 29)
139struct inet_listen_hashbucket {
140 spinlock_t lock;
141 struct hlist_nulls_head nulls_head;
142};
143
144/* This is for listening sockets, thus all sockets which possess wildcards. */
145#define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
146
147struct inet_hashinfo {
148 /* This is for sockets with full identity only. Sockets here will
149 * always be without wildcards and will have the following invariant:
150 *
151 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
152 *
153 */
154 struct inet_ehash_bucket *ehash;
155 spinlock_t *ehash_locks;
156 unsigned int ehash_mask;
157 unsigned int ehash_locks_mask;
158
159 /* Ok, let's try this, I give up, we do need a local binding
160 * TCP hash as well as the others for fast bind/connect.
161 */
162 struct kmem_cache *bind_bucket_cachep;
163 /* This bind table is hashed by local port */
164 struct inet_bind_hashbucket *bhash;
165 struct kmem_cache *bind2_bucket_cachep;
166 /* This bind table is hashed by local port and sk->sk_rcv_saddr (ipv4)
167 * or sk->sk_v6_rcv_saddr (ipv6). This 2nd bind table is used
168 * primarily for expediting bind conflict resolution.
169 */
170 struct inet_bind_hashbucket *bhash2;
171 unsigned int bhash_size;
172
173 /* The 2nd listener table hashed by local port and address */
174 unsigned int lhash2_mask;
175 struct inet_listen_hashbucket *lhash2;
176
177 bool pernet;
178} ____cacheline_aligned_in_smp;
179
180static inline struct inet_hashinfo *tcp_get_hashinfo(const struct sock *sk)
181{
182 return sock_net(sk)->ipv4.tcp_death_row.hashinfo;
183}
184
185static inline struct inet_listen_hashbucket *
186inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
187{
188 return &h->lhash2[hash & h->lhash2_mask];
189}
190
191static inline struct inet_ehash_bucket *inet_ehash_bucket(
192 struct inet_hashinfo *hashinfo,
193 unsigned int hash)
194{
195 return &hashinfo->ehash[hash & hashinfo->ehash_mask];
196}
197
198static inline spinlock_t *inet_ehash_lockp(
199 struct inet_hashinfo *hashinfo,
200 unsigned int hash)
201{
202 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
203}
204
205int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
206
207static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
208{
209 kvfree(hashinfo->ehash_locks);
210 hashinfo->ehash_locks = NULL;
211}
212
213struct inet_hashinfo *inet_pernet_hashinfo_alloc(struct inet_hashinfo *hashinfo,
214 unsigned int ehash_entries);
215void inet_pernet_hashinfo_free(struct inet_hashinfo *hashinfo);
216
217struct inet_bind_bucket *
218inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
219 struct inet_bind_hashbucket *head,
220 const unsigned short snum, int l3mdev);
221void inet_bind_bucket_destroy(struct inet_bind_bucket *tb);
222
223bool inet_bind_bucket_match(const struct inet_bind_bucket *tb,
224 const struct net *net, unsigned short port,
225 int l3mdev);
226
227struct inet_bind2_bucket *
228inet_bind2_bucket_create(struct kmem_cache *cachep, struct net *net,
229 struct inet_bind_hashbucket *head,
230 struct inet_bind_bucket *tb,
231 const struct sock *sk);
232
233void inet_bind2_bucket_destroy(struct kmem_cache *cachep,
234 struct inet_bind2_bucket *tb);
235
236struct inet_bind2_bucket *
237inet_bind2_bucket_find(const struct inet_bind_hashbucket *head,
238 const struct net *net,
239 unsigned short port, int l3mdev,
240 const struct sock *sk);
241
242bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb,
243 const struct net *net, unsigned short port,
244 int l3mdev, const struct sock *sk);
245
246static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
247 const u32 bhash_size)
248{
249 return (lport + net_hash_mix(net)) & (bhash_size - 1);
250}
251
252static inline struct inet_bind_hashbucket *
253inet_bhashfn_portaddr(const struct inet_hashinfo *hinfo, const struct sock *sk,
254 const struct net *net, unsigned short port)
255{
256 u32 hash;
257
258#if IS_ENABLED(CONFIG_IPV6)
259 if (sk->sk_family == AF_INET6)
260 hash = ipv6_portaddr_hash(net, &sk->sk_v6_rcv_saddr, port);
261 else
262#endif
263 hash = ipv4_portaddr_hash(net, sk->sk_rcv_saddr, port);
264 return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)];
265}
266
267static inline bool inet_use_hash2_on_bind(const struct sock *sk)
268{
269#if IS_ENABLED(CONFIG_IPV6)
270 if (sk->sk_family == AF_INET6) {
271 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
272 return false;
273
274 if (!ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
275 return true;
276 }
277#endif
278 return sk->sk_rcv_saddr != htonl(INADDR_ANY);
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);
303
304bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk);
305bool inet_ehash_nolisten(struct sock *sk, struct sock *osk,
306 bool *found_dup_sk);
307int inet_hash(struct sock *sk);
308void inet_unhash(struct sock *sk);
309
310struct sock *__inet_lookup_listener(const struct net *net,
311 struct sk_buff *skb, int doff,
312 const __be32 saddr, const __be16 sport,
313 const __be32 daddr,
314 const unsigned short hnum,
315 const int dif, const int sdif);
316
317static inline struct sock *inet_lookup_listener(struct net *net,
318 struct sk_buff *skb, int doff,
319 __be32 saddr, __be16 sport,
320 __be32 daddr, __be16 dport,
321 int dif, int sdif)
322{
323 return __inet_lookup_listener(net, skb, doff, saddr, sport,
324 daddr, ntohs(dport), dif, sdif);
325}
326
327/* Socket demux engine toys. */
328/* What happens here is ugly; there's a pair of adjacent fields in
329 struct inet_sock; __be16 dport followed by __u16 num. We want to
330 search by pair, so we combine the keys into a single 32bit value
331 and compare with 32bit value read from &...->dport. Let's at least
332 make sure that it's not mixed with anything else...
333 On 64bit targets we combine comparisons with pair of adjacent __be32
334 fields in the same way.
335*/
336#ifdef __BIG_ENDIAN
337#define INET_COMBINED_PORTS(__sport, __dport) \
338 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
339#else /* __LITTLE_ENDIAN */
340#define INET_COMBINED_PORTS(__sport, __dport) \
341 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
342#endif
343
344#ifdef __BIG_ENDIAN
345#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
346 const __addrpair __name = (__force __addrpair) ( \
347 (((__force __u64)(__be32)(__saddr)) << 32) | \
348 ((__force __u64)(__be32)(__daddr)))
349#else /* __LITTLE_ENDIAN */
350#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
351 const __addrpair __name = (__force __addrpair) ( \
352 (((__force __u64)(__be32)(__daddr)) << 32) | \
353 ((__force __u64)(__be32)(__saddr)))
354#endif /* __BIG_ENDIAN */
355
356static inline bool inet_match(const struct net *net, const struct sock *sk,
357 const __addrpair cookie, const __portpair ports,
358 int dif, int sdif)
359{
360 if (!net_eq(sock_net(sk), net) ||
361 READ_ONCE(sk->sk_portpair) != ports ||
362 sk->sk_addrpair != cookie)
363 return false;
364
365 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */
366 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif,
367 sdif);
368}
369
370/* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
371 * not check it for lookups anymore, thanks Alexey. -DaveM
372 */
373struct sock *__inet_lookup_established(const struct net *net,
374 const __be32 saddr, const __be16 sport,
375 const __be32 daddr, const u16 hnum,
376 const int dif, const int sdif);
377
378typedef u32 (inet_ehashfn_t)(const struct net *net,
379 const __be32 laddr, const __u16 lport,
380 const __be32 faddr, const __be16 fport);
381
382inet_ehashfn_t inet_ehashfn;
383
384INDIRECT_CALLABLE_DECLARE(inet_ehashfn_t udp_ehashfn);
385
386struct sock *inet_lookup_reuseport(const struct net *net, struct sock *sk,
387 struct sk_buff *skb, int doff,
388 __be32 saddr, __be16 sport,
389 __be32 daddr, unsigned short hnum,
390 inet_ehashfn_t *ehashfn);
391
392struct sock *inet_lookup_run_sk_lookup(const struct net *net,
393 int protocol,
394 struct sk_buff *skb, int doff,
395 __be32 saddr, __be16 sport,
396 __be32 daddr, u16 hnum, const int dif,
397 inet_ehashfn_t *ehashfn);
398
399static inline struct sock *inet_lookup_established(struct net *net,
400 const __be32 saddr, const __be16 sport,
401 const __be32 daddr, const __be16 dport,
402 const int dif)
403{
404 return __inet_lookup_established(net, saddr, sport, daddr,
405 ntohs(dport), dif, 0);
406}
407
408static inline struct sock *__inet_lookup(struct net *net,
409 struct sk_buff *skb, int doff,
410 const __be32 saddr, const __be16 sport,
411 const __be32 daddr, const __be16 dport,
412 const int dif, const int sdif,
413 bool *refcounted)
414{
415 u16 hnum = ntohs(dport);
416 struct sock *sk;
417
418 sk = __inet_lookup_established(net, saddr, sport,
419 daddr, hnum, dif, sdif);
420 *refcounted = true;
421 if (sk)
422 return sk;
423 *refcounted = false;
424 return __inet_lookup_listener(net, skb, doff, saddr,
425 sport, daddr, hnum, dif, sdif);
426}
427
428static inline struct sock *inet_lookup(struct net *net,
429 struct sk_buff *skb, int doff,
430 const __be32 saddr, const __be16 sport,
431 const __be32 daddr, const __be16 dport,
432 const int dif)
433{
434 struct sock *sk;
435 bool refcounted;
436
437 sk = __inet_lookup(net, skb, doff, saddr, sport, daddr,
438 dport, dif, 0, &refcounted);
439
440 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
441 sk = NULL;
442 return sk;
443}
444
445static inline
446struct sock *inet_steal_sock(struct net *net, struct sk_buff *skb, int doff,
447 const __be32 saddr, const __be16 sport,
448 const __be32 daddr, const __be16 dport,
449 bool *refcounted, inet_ehashfn_t *ehashfn)
450{
451 struct sock *sk, *reuse_sk;
452 bool prefetched;
453
454 sk = skb_steal_sock(skb, refcounted, &prefetched);
455 if (!sk)
456 return NULL;
457
458 if (!prefetched || !sk_fullsock(sk))
459 return sk;
460
461 if (sk->sk_protocol == IPPROTO_TCP) {
462 if (sk->sk_state != TCP_LISTEN)
463 return sk;
464 } else if (sk->sk_protocol == IPPROTO_UDP) {
465 if (sk->sk_state != TCP_CLOSE)
466 return sk;
467 } else {
468 return sk;
469 }
470
471 reuse_sk = inet_lookup_reuseport(net, sk, skb, doff,
472 saddr, sport, daddr, ntohs(dport),
473 ehashfn);
474 if (!reuse_sk)
475 return sk;
476
477 /* We've chosen a new reuseport sock which is never refcounted. This
478 * implies that sk also isn't refcounted.
479 */
480 WARN_ON_ONCE(*refcounted);
481
482 return reuse_sk;
483}
484
485static inline struct sock *__inet_lookup_skb(struct sk_buff *skb,
486 int doff,
487 const __be16 sport,
488 const __be16 dport,
489 const int sdif,
490 bool *refcounted)
491{
492 struct net *net = skb_dst_dev_net_rcu(skb);
493 const struct iphdr *iph = ip_hdr(skb);
494 struct sock *sk;
495
496 sk = inet_steal_sock(net, skb, doff, iph->saddr, sport, iph->daddr, dport,
497 refcounted, inet_ehashfn);
498 if (IS_ERR(sk))
499 return NULL;
500 if (sk)
501 return sk;
502
503 return __inet_lookup(net, skb, doff, iph->saddr, sport,
504 iph->daddr, dport, inet_iif(skb), sdif,
505 refcounted);
506}
507
508static inline void sk_daddr_set(struct sock *sk, __be32 addr)
509{
510 sk->sk_daddr = addr; /* alias of inet_daddr */
511#if IS_ENABLED(CONFIG_IPV6)
512 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr);
513#endif
514}
515
516static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
517{
518 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
519#if IS_ENABLED(CONFIG_IPV6)
520 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr);
521#endif
522}
523
524int __inet_hash_connect(struct inet_timewait_death_row *death_row,
525 struct sock *sk, u64 port_offset,
526 u32 hash_port0,
527 int (*check_established)(struct inet_timewait_death_row *,
528 struct sock *, __u16,
529 struct inet_timewait_sock **,
530 bool rcu_lookup,
531 u32 hash));
532
533int inet_hash_connect(struct inet_timewait_death_row *death_row,
534 struct sock *sk);
535#endif /* _INET_HASHTABLES_H */