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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/atomic.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 */
42 struct 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 struct inet_bind_bucket {
78 possible_net_t ib_net;
79 unsigned short port;
80 signed char fastreuse;
81 signed char fastreuseport;
82 kuid_t fastuid;
83 int num_owners;
84 struct hlist_node node;
85 struct hlist_head owners;
86 };
87
88 static inline struct net *ib_net(struct inet_bind_bucket *ib)
89 {
90 return read_pnet(&ib->ib_net);
91 }
92
93 #define inet_bind_bucket_for_each(tb, head) \
94 hlist_for_each_entry(tb, head, node)
95
96 struct inet_bind_hashbucket {
97 spinlock_t lock;
98 struct hlist_head chain;
99 };
100
101 /*
102 * Sockets can be hashed in established or listening table
103 */
104 struct inet_listen_hashbucket {
105 spinlock_t lock;
106 struct hlist_head head;
107 };
108
109 /* This is for listening sockets, thus all sockets which possess wildcards. */
110 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
111
112 struct inet_hashinfo {
113 /* This is for sockets with full identity only. Sockets here will
114 * always be without wildcards and will have the following invariant:
115 *
116 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
117 *
118 */
119 struct inet_ehash_bucket *ehash;
120 spinlock_t *ehash_locks;
121 unsigned int ehash_mask;
122 unsigned int ehash_locks_mask;
123
124 /* Ok, let's try this, I give up, we do need a local binding
125 * TCP hash as well as the others for fast bind/connect.
126 */
127 struct inet_bind_hashbucket *bhash;
128
129 unsigned int bhash_size;
130 /* 4 bytes hole on 64 bit */
131
132 struct kmem_cache *bind_bucket_cachep;
133
134 /* All the above members are written once at bootup and
135 * never written again _or_ are predominantly read-access.
136 *
137 * Now align to a new cache line as all the following members
138 * might be often dirty.
139 */
140 /* All sockets in TCP_LISTEN state will be in here. This is the only
141 * table where wildcard'd TCP sockets can exist. Hash function here
142 * is just local port number.
143 */
144 struct inet_listen_hashbucket listening_hash[INET_LHTABLE_SIZE]
145 ____cacheline_aligned_in_smp;
146 };
147
148 static inline struct inet_ehash_bucket *inet_ehash_bucket(
149 struct inet_hashinfo *hashinfo,
150 unsigned int hash)
151 {
152 return &hashinfo->ehash[hash & hashinfo->ehash_mask];
153 }
154
155 static inline spinlock_t *inet_ehash_lockp(
156 struct inet_hashinfo *hashinfo,
157 unsigned int hash)
158 {
159 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
160 }
161
162 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
163
164 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
165 {
166 kvfree(hashinfo->ehash_locks);
167 hashinfo->ehash_locks = NULL;
168 }
169
170 struct inet_bind_bucket *
171 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
172 struct inet_bind_hashbucket *head,
173 const unsigned short snum);
174 void inet_bind_bucket_destroy(struct kmem_cache *cachep,
175 struct inet_bind_bucket *tb);
176
177 static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
178 const u32 bhash_size)
179 {
180 return (lport + net_hash_mix(net)) & (bhash_size - 1);
181 }
182
183 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
184 const unsigned short snum);
185
186 /* These can have wildcards, don't try too hard. */
187 static inline u32 inet_lhashfn(const struct net *net, const unsigned short num)
188 {
189 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
190 }
191
192 static inline int inet_sk_listen_hashfn(const struct sock *sk)
193 {
194 return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
195 }
196
197 /* Caller must disable local BH processing. */
198 int __inet_inherit_port(const struct sock *sk, struct sock *child);
199
200 void inet_put_port(struct sock *sk);
201
202 void inet_hashinfo_init(struct inet_hashinfo *h);
203
204 bool inet_ehash_insert(struct sock *sk, struct sock *osk);
205 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk);
206 int __inet_hash(struct sock *sk, struct sock *osk,
207 int (*saddr_same)(const struct sock *sk1,
208 const struct sock *sk2,
209 bool match_wildcard));
210 int inet_hash(struct sock *sk);
211 void inet_unhash(struct sock *sk);
212
213 struct sock *__inet_lookup_listener(struct net *net,
214 struct inet_hashinfo *hashinfo,
215 struct sk_buff *skb, int doff,
216 const __be32 saddr, const __be16 sport,
217 const __be32 daddr,
218 const unsigned short hnum,
219 const int dif);
220
221 static inline struct sock *inet_lookup_listener(struct net *net,
222 struct inet_hashinfo *hashinfo,
223 struct sk_buff *skb, int doff,
224 __be32 saddr, __be16 sport,
225 __be32 daddr, __be16 dport, int dif)
226 {
227 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
228 daddr, ntohs(dport), dif);
229 }
230
231 /* Socket demux engine toys. */
232 /* What happens here is ugly; there's a pair of adjacent fields in
233 struct inet_sock; __be16 dport followed by __u16 num. We want to
234 search by pair, so we combine the keys into a single 32bit value
235 and compare with 32bit value read from &...->dport. Let's at least
236 make sure that it's not mixed with anything else...
237 On 64bit targets we combine comparisons with pair of adjacent __be32
238 fields in the same way.
239 */
240 #ifdef __BIG_ENDIAN
241 #define INET_COMBINED_PORTS(__sport, __dport) \
242 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
243 #else /* __LITTLE_ENDIAN */
244 #define INET_COMBINED_PORTS(__sport, __dport) \
245 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
246 #endif
247
248 #if (BITS_PER_LONG == 64)
249 #ifdef __BIG_ENDIAN
250 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
251 const __addrpair __name = (__force __addrpair) ( \
252 (((__force __u64)(__be32)(__saddr)) << 32) | \
253 ((__force __u64)(__be32)(__daddr)))
254 #else /* __LITTLE_ENDIAN */
255 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
256 const __addrpair __name = (__force __addrpair) ( \
257 (((__force __u64)(__be32)(__daddr)) << 32) | \
258 ((__force __u64)(__be32)(__saddr)))
259 #endif /* __BIG_ENDIAN */
260 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \
261 (((__sk)->sk_portpair == (__ports)) && \
262 ((__sk)->sk_addrpair == (__cookie)) && \
263 (!(__sk)->sk_bound_dev_if || \
264 ((__sk)->sk_bound_dev_if == (__dif))) && \
265 net_eq(sock_net(__sk), (__net)))
266 #else /* 32-bit arch */
267 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
268 const int __name __deprecated __attribute__((unused))
269
270 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif) \
271 (((__sk)->sk_portpair == (__ports)) && \
272 ((__sk)->sk_daddr == (__saddr)) && \
273 ((__sk)->sk_rcv_saddr == (__daddr)) && \
274 (!(__sk)->sk_bound_dev_if || \
275 ((__sk)->sk_bound_dev_if == (__dif))) && \
276 net_eq(sock_net(__sk), (__net)))
277 #endif /* 64-bit arch */
278
279 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
280 * not check it for lookups anymore, thanks Alexey. -DaveM
281 */
282 struct sock *__inet_lookup_established(struct net *net,
283 struct inet_hashinfo *hashinfo,
284 const __be32 saddr, const __be16 sport,
285 const __be32 daddr, const u16 hnum,
286 const int dif);
287
288 static inline struct sock *
289 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
290 const __be32 saddr, const __be16 sport,
291 const __be32 daddr, const __be16 dport,
292 const int dif)
293 {
294 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
295 ntohs(dport), dif);
296 }
297
298 static inline struct sock *__inet_lookup(struct net *net,
299 struct inet_hashinfo *hashinfo,
300 struct sk_buff *skb, int doff,
301 const __be32 saddr, const __be16 sport,
302 const __be32 daddr, const __be16 dport,
303 const int dif,
304 bool *refcounted)
305 {
306 u16 hnum = ntohs(dport);
307 struct sock *sk;
308
309 sk = __inet_lookup_established(net, hashinfo, saddr, sport,
310 daddr, hnum, dif);
311 *refcounted = true;
312 if (sk)
313 return sk;
314 *refcounted = false;
315 return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
316 sport, daddr, hnum, dif);
317 }
318
319 static inline struct sock *inet_lookup(struct net *net,
320 struct inet_hashinfo *hashinfo,
321 struct sk_buff *skb, int doff,
322 const __be32 saddr, const __be16 sport,
323 const __be32 daddr, const __be16 dport,
324 const int dif)
325 {
326 struct sock *sk;
327 bool refcounted;
328
329 sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
330 dport, dif, &refcounted);
331
332 if (sk && !refcounted && !atomic_inc_not_zero(&sk->sk_refcnt))
333 sk = NULL;
334 return sk;
335 }
336
337 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
338 struct sk_buff *skb,
339 int doff,
340 const __be16 sport,
341 const __be16 dport,
342 bool *refcounted)
343 {
344 struct sock *sk = skb_steal_sock(skb);
345 const struct iphdr *iph = ip_hdr(skb);
346
347 *refcounted = true;
348 if (sk)
349 return sk;
350
351 return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
352 doff, iph->saddr, sport,
353 iph->daddr, dport, inet_iif(skb),
354 refcounted);
355 }
356
357 u32 sk_ehashfn(const struct sock *sk);
358 u32 inet6_ehashfn(const struct net *net,
359 const struct in6_addr *laddr, const u16 lport,
360 const struct in6_addr *faddr, const __be16 fport);
361
362 static inline void sk_daddr_set(struct sock *sk, __be32 addr)
363 {
364 sk->sk_daddr = addr; /* alias of inet_daddr */
365 #if IS_ENABLED(CONFIG_IPV6)
366 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_daddr);
367 #endif
368 }
369
370 static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
371 {
372 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
373 #if IS_ENABLED(CONFIG_IPV6)
374 ipv6_addr_set_v4mapped(addr, &sk->sk_v6_rcv_saddr);
375 #endif
376 }
377
378 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
379 struct sock *sk, u32 port_offset,
380 int (*check_established)(struct inet_timewait_death_row *,
381 struct sock *, __u16,
382 struct inet_timewait_sock **));
383
384 int inet_hash_connect(struct inet_timewait_death_row *death_row,
385 struct sock *sk);
386 #endif /* _INET_HASHTABLES_H */