1 /* SPDX-License-Identifier: GPL-2.0-or-later */
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.
7 * Authors: Lotsa people, from code originally in tcp
10 #ifndef _INET_HASHTABLES_H
11 #define _INET_HASHTABLES_H
14 #include <linux/interrupt.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>
24 #include <net/inet_connection_sock.h>
25 #include <net/inet_sock.h>
27 #include <net/route.h>
28 #include <net/tcp_states.h>
29 #include <net/netns/hash.h>
31 #include <linux/refcount.h>
32 #include <asm/byteorder.h>
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
38 struct inet_ehash_bucket {
39 struct hlist_nulls_head chain;
42 /* There are a few simple rules, which allow for local port reuse by
43 * an application. In essence:
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
53 * Failing this, the port cannot be shared.
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.
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
73 #define FASTREUSEPORT_ANY 1
74 #define FASTREUSEPORT_STRICT 2
76 struct inet_bind_bucket {
77 possible_net_t ib_net;
80 signed char fastreuse;
81 signed char fastreuseport;
83 #if IS_ENABLED(CONFIG_IPV6)
84 struct in6_addr fast_v6_rcv_saddr;
86 __be32 fast_rcv_saddr;
87 unsigned short fast_sk_family;
89 struct hlist_node node;
90 struct hlist_head owners;
93 static inline struct net *ib_net(struct inet_bind_bucket *ib)
95 return read_pnet(&ib->ib_net);
98 #define inet_bind_bucket_for_each(tb, head) \
99 hlist_for_each_entry(tb, head, node)
101 struct inet_bind_hashbucket {
103 struct hlist_head chain;
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.
111 #define LISTENING_NULLS_BASE (1U << 29)
112 struct inet_listen_hashbucket {
116 struct hlist_head head;
117 struct hlist_nulls_head nulls_head;
121 /* This is for listening sockets, thus all sockets which possess wildcards. */
122 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
124 struct inet_hashinfo {
125 /* This is for sockets with full identity only. Sockets here will
126 * always be without wildcards and will have the following invariant:
128 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
131 struct inet_ehash_bucket *ehash;
132 spinlock_t *ehash_locks;
133 unsigned int ehash_mask;
134 unsigned int ehash_locks_mask;
136 /* Ok, let's try this, I give up, we do need a local binding
137 * TCP hash as well as the others for fast bind/connect.
139 struct kmem_cache *bind_bucket_cachep;
140 struct inet_bind_hashbucket *bhash;
141 unsigned int bhash_size;
143 /* The 2nd listener table hashed by local port and address */
144 unsigned int lhash2_mask;
145 struct inet_listen_hashbucket *lhash2;
147 /* All the above members are written once at bootup and
148 * never written again _or_ are predominantly read-access.
150 * Now align to a new cache line as all the following members
151 * might be often dirty.
153 /* All sockets in TCP_LISTEN state will be in listening_hash.
154 * This is the only table where wildcard'd TCP sockets can
155 * exist. listening_hash is only hashed by local port number.
156 * If lhash2 is initialized, the same socket will also be hashed
157 * to lhash2 by port and address.
159 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE]
160 ____cacheline_aligned_in_smp;
163 #define inet_lhash2_for_each_icsk_continue(__icsk) \
164 hlist_for_each_entry_continue(__icsk, icsk_listen_portaddr_node)
166 #define inet_lhash2_for_each_icsk(__icsk, list) \
167 hlist_for_each_entry(__icsk, list, icsk_listen_portaddr_node)
169 #define inet_lhash2_for_each_icsk_rcu(__icsk, list) \
170 hlist_for_each_entry_rcu(__icsk, list, icsk_listen_portaddr_node)
172 static inline struct inet_listen_hashbucket *
173 inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
175 return &h->lhash2[hash & h->lhash2_mask];
178 static inline struct inet_ehash_bucket *inet_ehash_bucket(
179 struct inet_hashinfo *hashinfo,
182 return &hashinfo->ehash[hash & hashinfo->ehash_mask];
185 static inline spinlock_t *inet_ehash_lockp(
186 struct inet_hashinfo *hashinfo,
189 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
192 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
194 static inline void inet_hashinfo2_free_mod(struct inet_hashinfo *h)
200 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
202 kvfree(hashinfo->ehash_locks);
203 hashinfo->ehash_locks = NULL;
206 struct inet_bind_bucket *
207 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
208 struct inet_bind_hashbucket *head,
209 const unsigned short snum, int l3mdev);
210 void inet_bind_bucket_destroy(struct kmem_cache *cachep,
211 struct inet_bind_bucket *tb);
213 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
214 const u32 bhash_size)
216 return (lport + net_hash_mix(net)) & (bhash_size - 1);
219 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
220 const unsigned short snum);
222 /* These can have wildcards, don't try too hard. */
223 static inline u32 inet_lhashfn(const struct net *net, const unsigned short num)
225 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
228 static inline int inet_sk_listen_hashfn(const struct sock *sk)
230 return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
233 /* Caller must disable local BH processing. */
234 int __inet_inherit_port(const struct sock *sk, struct sock *child);
236 void inet_put_port(struct sock *sk);
238 void inet_hashinfo_init(struct inet_hashinfo *h);
239 void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
240 unsigned long numentries, int scale,
241 unsigned long low_limit,
242 unsigned long high_limit);
243 int inet_hashinfo2_init_mod(struct inet_hashinfo *h);
245 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk);
246 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk,
248 int __inet_hash(struct sock *sk, struct sock *osk);
249 int inet_hash(struct sock *sk);
250 void inet_unhash(struct sock *sk);
252 struct sock *__inet_lookup_listener(struct net *net,
253 struct inet_hashinfo *hashinfo,
254 struct sk_buff *skb, int doff,
255 const __be32 saddr, const __be16 sport,
257 const unsigned short hnum,
258 const int dif, const int sdif);
260 static inline struct sock *inet_lookup_listener(struct net *net,
261 struct inet_hashinfo *hashinfo,
262 struct sk_buff *skb, int doff,
263 __be32 saddr, __be16 sport,
264 __be32 daddr, __be16 dport, int dif, int sdif)
266 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
267 daddr, ntohs(dport), dif, sdif);
270 /* Socket demux engine toys. */
271 /* What happens here is ugly; there's a pair of adjacent fields in
272 struct inet_sock; __be16 dport followed by __u16 num. We want to
273 search by pair, so we combine the keys into a single 32bit value
274 and compare with 32bit value read from &...->dport. Let's at least
275 make sure that it's not mixed with anything else...
276 On 64bit targets we combine comparisons with pair of adjacent __be32
277 fields in the same way.
280 #define INET_COMBINED_PORTS(__sport, __dport) \
281 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
282 #else /* __LITTLE_ENDIAN */
283 #define INET_COMBINED_PORTS(__sport, __dport) \
284 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
288 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
289 const __addrpair __name = (__force __addrpair) ( \
290 (((__force __u64)(__be32)(__saddr)) << 32) | \
291 ((__force __u64)(__be32)(__daddr)))
292 #else /* __LITTLE_ENDIAN */
293 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
294 const __addrpair __name = (__force __addrpair) ( \
295 (((__force __u64)(__be32)(__daddr)) << 32) | \
296 ((__force __u64)(__be32)(__saddr)))
297 #endif /* __BIG_ENDIAN */
299 static inline bool INET_MATCH(struct net *net, const struct sock *sk,
300 const __addrpair cookie, const __portpair ports,
303 if (!net_eq(sock_net(sk), net) ||
304 sk->sk_portpair != ports ||
305 sk->sk_addrpair != cookie)
308 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */
309 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif,
313 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
314 * not check it for lookups anymore, thanks Alexey. -DaveM
316 struct sock *__inet_lookup_established(struct net *net,
317 struct inet_hashinfo *hashinfo,
318 const __be32 saddr, const __be16 sport,
319 const __be32 daddr, const u16 hnum,
320 const int dif, const int sdif);
322 static inline struct sock *
323 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
324 const __be32 saddr, const __be16 sport,
325 const __be32 daddr, const __be16 dport,
328 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
329 ntohs(dport), dif, 0);
332 static inline struct sock *__inet_lookup(struct net *net,
333 struct inet_hashinfo *hashinfo,
334 struct sk_buff *skb, int doff,
335 const __be32 saddr, const __be16 sport,
336 const __be32 daddr, const __be16 dport,
337 const int dif, const int sdif,
340 u16 hnum = ntohs(dport);
343 sk = __inet_lookup_established(net, hashinfo, saddr, sport,
344 daddr, hnum, dif, sdif);
349 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
350 sport, daddr, hnum, dif, sdif);
353 static inline struct sock *inet_lookup(struct net *net,
354 struct inet_hashinfo *hashinfo,
355 struct sk_buff *skb, int doff,
356 const __be32 saddr, const __be16 sport,
357 const __be32 daddr, const __be16 dport,
363 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
364 dport, dif, 0, &refcounted);
366 if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
371 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
379 struct sock *sk = skb_steal_sock(skb, refcounted);
380 const struct iphdr *iph = ip_hdr(skb);
385 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
386 doff, iph->saddr, sport,
387 iph->daddr, dport, inet_iif(skb), sdif,
391 u32 inet6_ehashfn(const struct net *net,
392 const struct in6_addr *laddr, const u16 lport,
393 const struct in6_addr *faddr, const __be16 fport);
395 static inline void sk_daddr_set(struct sock *sk, __be32 addr)
397 sk->sk_daddr = addr; /* alias of inet_daddr */
398 #if IS_ENABLED(CONFIG_IPV6)
399 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr);
403 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
405 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
406 #if IS_ENABLED(CONFIG_IPV6)
407 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr);
411 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
412 struct sock *sk, u64 port_offset,
413 int (*check_established)(struct inet_timewait_death_row *,
414 struct sock *, __u16,
415 struct inet_timewait_sock **));
417 int inet_hash_connect(struct inet_timewait_death_row *death_row,
419 #endif /* _INET_HASHTABLES_H */