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/sock.h>
27#include <net/route.h>
28#include <net/tcp_states.h>
29#include <net/netns/hash.h>
30
31#include <linux/refcount.h>
32#include <asm/byteorder.h>
33
34/* This is for all connections with a full identity, no wildcards.
35 * The 'e' prefix stands for Establish, but we really put all sockets
36 * but LISTEN ones.
37 */
38struct inet_ehash_bucket {
39 struct hlist_nulls_head chain;
40};
41
42/* There are a few simple rules, which allow for local port reuse by
43 * an application. In essence:
44 *
45 * 1) Sockets bound to different interfaces may share a local port.
46 * Failing that, goto test 2.
47 * 2) If all sockets have sk->sk_reuse set, and none of them are in
48 * TCP_LISTEN state, the port may be shared.
49 * Failing that, goto test 3.
50 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
51 * address, and none of them are the same, the port may be
52 * shared.
53 * Failing this, the port cannot be shared.
54 *
55 * The interesting point, is test #2. This is what an FTP server does
56 * all day. To optimize this case we use a specific flag bit defined
57 * below. As we add sockets to a bind bucket list, we perform a
58 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
59 * As long as all sockets added to a bind bucket pass this test,
60 * the flag bit will be set.
61 * The resulting situation is that tcp_v[46]_verify_bind() can just check
62 * for this flag bit, if it is set and the socket trying to bind has
63 * sk->sk_reuse set, we don't even have to walk the owners list at all,
64 * we return that it is ok to bind this socket to the requested local port.
65 *
66 * Sounds like a lot of work, but it is worth it. In a more naive
67 * implementation (ie. current FreeBSD etc.) the entire list of ports
68 * must be walked for each data port opened by an ftp server. Needless
69 * to say, this does not scale at all. With a couple thousand FTP
70 * users logged onto your box, isn't it nice to know that new data
71 * ports are created in O(1) time? I thought so. ;-) -DaveM
72 */
73#define FASTREUSEPORT_ANY 1
74#define FASTREUSEPORT_STRICT 2
75
76struct inet_bind_bucket {
77 possible_net_t ib_net;
78 int l3mdev;
79 unsigned short port;
80 signed char fastreuse;
81 signed char fastreuseport;
82 kuid_t fastuid;
83#if IS_ENABLED(CONFIG_IPV6)
84 struct in6_addr fast_v6_rcv_saddr;
85#endif
86 __be32 fast_rcv_saddr;
87 unsigned short fast_sk_family;
88 bool fast_ipv6_only;
89 struct hlist_node node;
90 struct hlist_head owners;
91};
92
93static inline struct net *ib_net(struct inet_bind_bucket *ib)
94{
95 return read_pnet(&ib->ib_net);
96}
97
98#define inet_bind_bucket_for_each(tb, head) \
99 hlist_for_each_entry(tb, head, node)
100
101struct inet_bind_hashbucket {
102 spinlock_t lock;
103 struct hlist_head chain;
104};
105
106/* Sockets can be hashed in established or listening table.
107 * We must use different 'nulls' end-of-chain value for all hash buckets :
108 * A socket might transition from ESTABLISH to LISTEN state without
109 * RCU grace period. A lookup in ehash table needs to handle this case.
110 */
111#define LISTENING_NULLS_BASE (1U << 29)
112struct inet_listen_hashbucket {
113 spinlock_t lock;
114 struct hlist_nulls_head nulls_head;
115};
116
117/* This is for listening sockets, thus all sockets which possess wildcards. */
118#define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
119
120struct inet_hashinfo {
121 /* This is for sockets with full identity only. Sockets here will
122 * always be without wildcards and will have the following invariant:
123 *
124 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
125 *
126 */
127 struct inet_ehash_bucket *ehash;
128 spinlock_t *ehash_locks;
129 unsigned int ehash_mask;
130 unsigned int ehash_locks_mask;
131
132 /* Ok, let's try this, I give up, we do need a local binding
133 * TCP hash as well as the others for fast bind/connect.
134 */
135 struct kmem_cache *bind_bucket_cachep;
136 struct inet_bind_hashbucket *bhash;
137 unsigned int bhash_size;
138
139 /* The 2nd listener table hashed by local port and address */
140 unsigned int lhash2_mask;
141 struct inet_listen_hashbucket *lhash2;
142};
143
144static inline struct inet_listen_hashbucket *
145inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
146{
147 return &h->lhash2[hash & h->lhash2_mask];
148}
149
150static inline struct inet_ehash_bucket *inet_ehash_bucket(
151 struct inet_hashinfo *hashinfo,
152 unsigned int hash)
153{
154 return &hashinfo->ehash[hash & hashinfo->ehash_mask];
155}
156
157static inline spinlock_t *inet_ehash_lockp(
158 struct inet_hashinfo *hashinfo,
159 unsigned int hash)
160{
161 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
162}
163
164int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
165
166static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h)
167{
168 kfree(h->lhash2);
169 h->lhash2 = NULL;
170}
171
172static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
173{
174 kvfree(hashinfo->ehash_locks);
175 hashinfo->ehash_locks = NULL;
176}
177
178struct inet_bind_bucket *
179inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
180 struct inet_bind_hashbucket *head,
181 const unsigned short snum, int l3mdev);
182void inet_bind_bucket_destroy(struct kmem_cache *cachep,
183 struct inet_bind_bucket *tb);
184
185static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
186 const u32 bhash_size)
187{
188 return (lport + net_hash_mix(net)) & (bhash_size - 1);
189}
190
191void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
192 const unsigned short snum);
193
194/* Caller must disable local BH processing. */
195int __inet_inherit_port(const struct sock *sk, struct sock *child);
196
197void inet_put_port(struct sock *sk);
198
199void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
200 unsigned long numentries, int scale,
201 unsigned long low_limit,
202 unsigned long high_limit);
203int inet_hashinfo2_init_mod(struct inet_hashinfo *h);
204
205bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk);
206bool inet_ehash_nolisten(struct sock *sk, struct sock *osk,
207 bool *found_dup_sk);
208int __inet_hash(struct sock *sk, struct sock *osk);
209int inet_hash(struct sock *sk);
210void inet_unhash(struct sock *sk);
211
212struct sock *__inet_lookup_listener(struct net *net,
213 struct inet_hashinfo *hashinfo,
214 struct sk_buff *skb, int doff,
215 const __be32 saddr, const __be16 sport,
216 const __be32 daddr,
217 const unsigned short hnum,
218 const int dif, const int sdif);
219
220static inline struct sock *inet_lookup_listener(struct net *net,
221 struct inet_hashinfo *hashinfo,
222 struct sk_buff *skb, int doff,
223 __be32 saddr, __be16 sport,
224 __be32 daddr, __be16 dport, int dif, int sdif)
225{
226 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
227 daddr, ntohs(dport), dif, sdif);
228}
229
230/* Socket demux engine toys. */
231/* What happens here is ugly; there's a pair of adjacent fields in
232 struct inet_sock; __be16 dport followed by __u16 num. We want to
233 search by pair, so we combine the keys into a single 32bit value
234 and compare with 32bit value read from &...->dport. Let's at least
235 make sure that it's not mixed with anything else...
236 On 64bit targets we combine comparisons with pair of adjacent __be32
237 fields in the same way.
238*/
239#ifdef __BIG_ENDIAN
240#define INET_COMBINED_PORTS(__sport, __dport) \
241 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
242#else /* __LITTLE_ENDIAN */
243#define INET_COMBINED_PORTS(__sport, __dport) \
244 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
245#endif
246
247#ifdef __BIG_ENDIAN
248#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
249 const __addrpair __name = (__force __addrpair) ( \
250 (((__force __u64)(__be32)(__saddr)) << 32) | \
251 ((__force __u64)(__be32)(__daddr)))
252#else /* __LITTLE_ENDIAN */
253#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
254 const __addrpair __name = (__force __addrpair) ( \
255 (((__force __u64)(__be32)(__daddr)) << 32) | \
256 ((__force __u64)(__be32)(__saddr)))
257#endif /* __BIG_ENDIAN */
258
259static inline bool inet_match(struct net *net, const struct sock *sk,
260 const __addrpair cookie, const __portpair ports,
261 int dif, int sdif)
262{
263 if (!net_eq(sock_net(sk), net) ||
264 sk->sk_portpair != ports ||
265 sk->sk_addrpair != cookie)
266 return false;
267
268 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */
269 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif,
270 sdif);
271}
272
273/* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
274 * not check it for lookups anymore, thanks Alexey. -DaveM
275 */
276struct sock *__inet_lookup_established(struct net *net,
277 struct inet_hashinfo *hashinfo,
278 const __be32 saddr, const __be16 sport,
279 const __be32 daddr, const u16 hnum,
280 const int dif, const int sdif);
281
282static inline struct sock *
283 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
284 const __be32 saddr, const __be16 sport,
285 const __be32 daddr, const __be16 dport,
286 const int dif)
287{
288 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
289 ntohs(dport), dif, 0);
290}
291
292static inline struct sock *__inet_lookup(struct net *net,
293 struct inet_hashinfo *hashinfo,
294 struct sk_buff *skb, int doff,
295 const __be32 saddr, const __be16 sport,
296 const __be32 daddr, const __be16 dport,
297 const int dif, const int sdif,
298 bool *refcounted)
299{
300 u16 hnum = ntohs(dport);
301 struct sock *sk;
302
303 sk = __inet_lookup_established(net, hashinfo, saddr, sport,
304 daddr, hnum, dif, sdif);
305 *refcounted = true;
306 if (sk)
307 return sk;
308 *refcounted = false;
309 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
310 sport, daddr, hnum, dif, sdif);
311}
312
313static inline struct sock *inet_lookup(struct net *net,
314 struct inet_hashinfo *hashinfo,
315 struct sk_buff *skb, int doff,
316 const __be32 saddr, const __be16 sport,
317 const __be32 daddr, const __be16 dport,
318 const int dif)
319{
320 struct sock *sk;
321 bool refcounted;
322
323 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
324 dport, dif, 0, &refcounted);
325
326 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
327 sk = NULL;
328 return sk;
329}
330
331static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
332 struct sk_buff *skb,
333 int doff,
334 const __be16 sport,
335 const __be16 dport,
336 const int sdif,
337 bool *refcounted)
338{
339 struct sock *sk = skb_steal_sock(skb, refcounted);
340 const struct iphdr *iph = ip_hdr(skb);
341
342 if (sk)
343 return sk;
344
345 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
346 doff, iph->saddr, sport,
347 iph->daddr, dport, inet_iif(skb), sdif,
348 refcounted);
349}
350
351u32 inet6_ehashfn(const struct net *net,
352 const struct in6_addr *laddr, const u16 lport,
353 const struct in6_addr *faddr, const __be16 fport);
354
355static inline void sk_daddr_set(struct sock *sk, __be32 addr)
356{
357 sk->sk_daddr = addr; /* alias of inet_daddr */
358#if IS_ENABLED(CONFIG_IPV6)
359 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr);
360#endif
361}
362
363static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
364{
365 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
366#if IS_ENABLED(CONFIG_IPV6)
367 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr);
368#endif
369}
370
371int __inet_hash_connect(struct inet_timewait_death_row *death_row,
372 struct sock *sk, u64 port_offset,
373 int (*check_established)(struct inet_timewait_death_row *,
374 struct sock *, __u16,
375 struct inet_timewait_sock **));
376
377int inet_hash_connect(struct inet_timewait_death_row *death_row,
378 struct sock *sk);
379#endif /* _INET_HASHTABLES_H */
380

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