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 #include <linux/vmalloc.h>
28 
29 #include <net/inet_connection_sock.h>
30 #include <net/inet_sock.h>
31 #include <net/sock.h>
32 #include <net/route.h>
33 #include <net/tcp_states.h>
34 #include <net/netns/hash.h>
35 
36 #include <linux/atomic.h>
37 #include <asm/byteorder.h>
38 
39 /* This is for all connections with a full identity, no wildcards.
40  * One chain is dedicated to TIME_WAIT sockets.
41  * I'll experiment with dynamic table growth later.
42  */
43 struct inet_ehash_bucket {
44 	struct hlist_nulls_head chain;
45 	struct hlist_nulls_head twchain;
46 };
47 
48 /* There are a few simple rules, which allow for local port reuse by
49  * an application.  In essence:
50  *
51  *	1) Sockets bound to different interfaces may share a local port.
52  *	   Failing that, goto test 2.
53  *	2) If all sockets have sk->sk_reuse set, and none of them are in
54  *	   TCP_LISTEN state, the port may be shared.
55  *	   Failing that, goto test 3.
56  *	3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
57  *	   address, and none of them are the same, the port may be
58  *	   shared.
59  *	   Failing this, the port cannot be shared.
60  *
61  * The interesting point, is test #2.  This is what an FTP server does
62  * all day.  To optimize this case we use a specific flag bit defined
63  * below.  As we add sockets to a bind bucket list, we perform a
64  * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
65  * As long as all sockets added to a bind bucket pass this test,
66  * the flag bit will be set.
67  * The resulting situation is that tcp_v[46]_verify_bind() can just check
68  * for this flag bit, if it is set and the socket trying to bind has
69  * sk->sk_reuse set, we don't even have to walk the owners list at all,
70  * we return that it is ok to bind this socket to the requested local port.
71  *
72  * Sounds like a lot of work, but it is worth it.  In a more naive
73  * implementation (ie. current FreeBSD etc.) the entire list of ports
74  * must be walked for each data port opened by an ftp server.  Needless
75  * to say, this does not scale at all.  With a couple thousand FTP
76  * users logged onto your box, isn't it nice to know that new data
77  * ports are created in O(1) time?  I thought so. ;-)	-DaveM
78  */
79 struct inet_bind_bucket {
80 #ifdef CONFIG_NET_NS
81 	struct net		*ib_net;
82 #endif
83 	unsigned short		port;
84 	signed short		fastreuse;
85 	int			num_owners;
86 	struct hlist_node	node;
87 	struct hlist_head	owners;
88 };
89 
ib_net(struct inet_bind_bucket * ib)90 static inline struct net *ib_net(struct inet_bind_bucket *ib)
91 {
92 	return read_pnet(&ib->ib_net);
93 }
94 
95 #define inet_bind_bucket_for_each(tb, pos, head) \
96 	hlist_for_each_entry(tb, pos, head, node)
97 
98 struct inet_bind_hashbucket {
99 	spinlock_t		lock;
100 	struct hlist_head	chain;
101 };
102 
103 /*
104  * Sockets can be hashed in established or listening table
105  * We must use different 'nulls' end-of-chain value for listening
106  * hash table, or we might find a socket that was closed and
107  * reallocated/inserted into established hash table
108  */
109 #define LISTENING_NULLS_BASE (1U << 29)
110 struct inet_listen_hashbucket {
111 	spinlock_t		lock;
112 	struct hlist_nulls_head	head;
113 };
114 
115 /* This is for listening sockets, thus all sockets which possess wildcards. */
116 #define INET_LHTABLE_SIZE	32	/* Yes, really, this is all you need. */
117 
118 struct inet_hashinfo {
119 	/* This is for sockets with full identity only.  Sockets here will
120 	 * always be without wildcards and will have the following invariant:
121 	 *
122 	 *          TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
123 	 *
124 	 * TIME_WAIT sockets use a separate chain (twchain).
125 	 */
126 	struct inet_ehash_bucket	*ehash;
127 	spinlock_t			*ehash_locks;
128 	unsigned int			ehash_mask;
129 	unsigned int			ehash_locks_mask;
130 
131 	/* Ok, let's try this, I give up, we do need a local binding
132 	 * TCP hash as well as the others for fast bind/connect.
133 	 */
134 	struct inet_bind_hashbucket	*bhash;
135 
136 	unsigned int			bhash_size;
137 	/* 4 bytes hole on 64 bit */
138 
139 	struct kmem_cache		*bind_bucket_cachep;
140 
141 	/* All the above members are written once at bootup and
142 	 * never written again _or_ are predominantly read-access.
143 	 *
144 	 * Now align to a new cache line as all the following members
145 	 * might be often dirty.
146 	 */
147 	/* All sockets in TCP_LISTEN state will be in here.  This is the only
148 	 * table where wildcard'd TCP sockets can exist.  Hash function here
149 	 * is just local port number.
150 	 */
151 	struct inet_listen_hashbucket	listening_hash[INET_LHTABLE_SIZE]
152 					____cacheline_aligned_in_smp;
153 
154 	atomic_t			bsockets;
155 };
156 
inet_ehash_bucket(struct inet_hashinfo * hashinfo,unsigned int hash)157 static inline struct inet_ehash_bucket *inet_ehash_bucket(
158 	struct inet_hashinfo *hashinfo,
159 	unsigned int hash)
160 {
161 	return &hashinfo->ehash[hash & hashinfo->ehash_mask];
162 }
163 
inet_ehash_lockp(struct inet_hashinfo * hashinfo,unsigned int hash)164 static inline spinlock_t *inet_ehash_lockp(
165 	struct inet_hashinfo *hashinfo,
166 	unsigned int hash)
167 {
168 	return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
169 }
170 
inet_ehash_locks_alloc(struct inet_hashinfo * hashinfo)171 static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
172 {
173 	unsigned int i, size = 256;
174 #if defined(CONFIG_PROVE_LOCKING)
175 	unsigned int nr_pcpus = 2;
176 #else
177 	unsigned int nr_pcpus = num_possible_cpus();
178 #endif
179 	if (nr_pcpus >= 4)
180 		size = 512;
181 	if (nr_pcpus >= 8)
182 		size = 1024;
183 	if (nr_pcpus >= 16)
184 		size = 2048;
185 	if (nr_pcpus >= 32)
186 		size = 4096;
187 	if (sizeof(spinlock_t) != 0) {
188 #ifdef CONFIG_NUMA
189 		if (size * sizeof(spinlock_t) > PAGE_SIZE)
190 			hashinfo->ehash_locks = vmalloc(size * sizeof(spinlock_t));
191 		else
192 #endif
193 		hashinfo->ehash_locks =	kmalloc(size * sizeof(spinlock_t),
194 						GFP_KERNEL);
195 		if (!hashinfo->ehash_locks)
196 			return ENOMEM;
197 		for (i = 0; i < size; i++)
198 			spin_lock_init(&hashinfo->ehash_locks[i]);
199 	}
200 	hashinfo->ehash_locks_mask = size - 1;
201 	return 0;
202 }
203 
inet_ehash_locks_free(struct inet_hashinfo * hashinfo)204 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
205 {
206 	if (hashinfo->ehash_locks) {
207 #ifdef CONFIG_NUMA
208 		unsigned int size = (hashinfo->ehash_locks_mask + 1) *
209 							sizeof(spinlock_t);
210 		if (size > PAGE_SIZE)
211 			vfree(hashinfo->ehash_locks);
212 		else
213 #endif
214 		kfree(hashinfo->ehash_locks);
215 		hashinfo->ehash_locks = NULL;
216 	}
217 }
218 
219 extern struct inet_bind_bucket *
220 		    inet_bind_bucket_create(struct kmem_cache *cachep,
221 					    struct net *net,
222 					    struct inet_bind_hashbucket *head,
223 					    const unsigned short snum);
224 extern void inet_bind_bucket_destroy(struct kmem_cache *cachep,
225 				     struct inet_bind_bucket *tb);
226 
inet_bhashfn(struct net * net,const __u16 lport,const int bhash_size)227 static inline int inet_bhashfn(struct net *net,
228 		const __u16 lport, const int bhash_size)
229 {
230 	return (lport + net_hash_mix(net)) & (bhash_size - 1);
231 }
232 
233 extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
234 			   const unsigned short snum);
235 
236 /* These can have wildcards, don't try too hard. */
inet_lhashfn(struct net * net,const unsigned short num)237 static inline int inet_lhashfn(struct net *net, const unsigned short num)
238 {
239 	return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
240 }
241 
inet_sk_listen_hashfn(const struct sock * sk)242 static inline int inet_sk_listen_hashfn(const struct sock *sk)
243 {
244 	return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
245 }
246 
247 /* Caller must disable local BH processing. */
248 extern int __inet_inherit_port(struct sock *sk, struct sock *child);
249 
250 extern void inet_put_port(struct sock *sk);
251 
252 void inet_hashinfo_init(struct inet_hashinfo *h);
253 
254 extern int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw);
255 extern void inet_hash(struct sock *sk);
256 extern void inet_unhash(struct sock *sk);
257 
258 extern struct sock *__inet_lookup_listener(struct net *net,
259 					   struct inet_hashinfo *hashinfo,
260 					   const __be32 daddr,
261 					   const unsigned short hnum,
262 					   const int dif);
263 
inet_lookup_listener(struct net * net,struct inet_hashinfo * hashinfo,__be32 daddr,__be16 dport,int dif)264 static inline struct sock *inet_lookup_listener(struct net *net,
265 		struct inet_hashinfo *hashinfo,
266 		__be32 daddr, __be16 dport, int dif)
267 {
268 	return __inet_lookup_listener(net, hashinfo, daddr, ntohs(dport), dif);
269 }
270 
271 /* Socket demux engine toys. */
272 /* What happens here is ugly; there's a pair of adjacent fields in
273    struct inet_sock; __be16 dport followed by __u16 num.  We want to
274    search by pair, so we combine the keys into a single 32bit value
275    and compare with 32bit value read from &...->dport.  Let's at least
276    make sure that it's not mixed with anything else...
277    On 64bit targets we combine comparisons with pair of adjacent __be32
278    fields in the same way.
279 */
280 typedef __u32 __bitwise __portpair;
281 #ifdef __BIG_ENDIAN
282 #define INET_COMBINED_PORTS(__sport, __dport) \
283 	((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
284 #else /* __LITTLE_ENDIAN */
285 #define INET_COMBINED_PORTS(__sport, __dport) \
286 	((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
287 #endif
288 
289 #if (BITS_PER_LONG == 64)
290 typedef __u64 __bitwise __addrpair;
291 #ifdef __BIG_ENDIAN
292 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
293 	const __addrpair __name = (__force __addrpair) ( \
294 				   (((__force __u64)(__be32)(__saddr)) << 32) | \
295 				   ((__force __u64)(__be32)(__daddr)));
296 #else /* __LITTLE_ENDIAN */
297 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
298 	const __addrpair __name = (__force __addrpair) ( \
299 				   (((__force __u64)(__be32)(__daddr)) << 32) | \
300 				   ((__force __u64)(__be32)(__saddr)));
301 #endif /* __BIG_ENDIAN */
302 #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
303 	(((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) &&	\
304 	 ((*((__addrpair *)&(inet_sk(__sk)->inet_daddr))) == (__cookie))  &&	\
305 	 ((*((__portpair *)&(inet_sk(__sk)->inet_dport))) == (__ports))   &&	\
306 	 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
307 #define INET_TW_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
308 	(((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) &&	\
309 	 ((*((__addrpair *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) &&	\
310 	 ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) &&	\
311 	 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
312 #else /* 32-bit arch */
313 #define INET_ADDR_COOKIE(__name, __saddr, __daddr)
314 #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)	\
315 	(((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net))	&&	\
316 	 (inet_sk(__sk)->inet_daddr	== (__saddr))		&&	\
317 	 (inet_sk(__sk)->inet_rcv_saddr	== (__daddr))		&&	\
318 	 ((*((__portpair *)&(inet_sk(__sk)->inet_dport))) == (__ports))	&&	\
319 	 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
320 #define INET_TW_MATCH(__sk, __net, __hash,__cookie, __saddr, __daddr, __ports, __dif)	\
321 	(((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net))	&&	\
322 	 (inet_twsk(__sk)->tw_daddr	== (__saddr))		&&	\
323 	 (inet_twsk(__sk)->tw_rcv_saddr	== (__daddr))		&&	\
324 	 ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) &&	\
325 	 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
326 #endif /* 64-bit arch */
327 
328 /*
329  * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
330  * not check it for lookups anymore, thanks Alexey. -DaveM
331  *
332  * Local BH must be disabled here.
333  */
334 extern struct sock * __inet_lookup_established(struct net *net,
335 		struct inet_hashinfo *hashinfo,
336 		const __be32 saddr, const __be16 sport,
337 		const __be32 daddr, const u16 hnum, const int dif);
338 
339 static inline struct sock *
inet_lookup_established(struct net * net,struct inet_hashinfo * hashinfo,const __be32 saddr,const __be16 sport,const __be32 daddr,const __be16 dport,const int dif)340 	inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
341 				const __be32 saddr, const __be16 sport,
342 				const __be32 daddr, const __be16 dport,
343 				const int dif)
344 {
345 	return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
346 					 ntohs(dport), dif);
347 }
348 
__inet_lookup(struct net * net,struct inet_hashinfo * hashinfo,const __be32 saddr,const __be16 sport,const __be32 daddr,const __be16 dport,const int dif)349 static inline struct sock *__inet_lookup(struct net *net,
350 					 struct inet_hashinfo *hashinfo,
351 					 const __be32 saddr, const __be16 sport,
352 					 const __be32 daddr, const __be16 dport,
353 					 const int dif)
354 {
355 	u16 hnum = ntohs(dport);
356 	struct sock *sk = __inet_lookup_established(net, hashinfo,
357 				saddr, sport, daddr, hnum, dif);
358 
359 	return sk ? : __inet_lookup_listener(net, hashinfo, daddr, hnum, dif);
360 }
361 
inet_lookup(struct net * net,struct inet_hashinfo * hashinfo,const __be32 saddr,const __be16 sport,const __be32 daddr,const __be16 dport,const int dif)362 static inline struct sock *inet_lookup(struct net *net,
363 				       struct inet_hashinfo *hashinfo,
364 				       const __be32 saddr, const __be16 sport,
365 				       const __be32 daddr, const __be16 dport,
366 				       const int dif)
367 {
368 	struct sock *sk;
369 
370 	local_bh_disable();
371 	sk = __inet_lookup(net, hashinfo, saddr, sport, daddr, dport, dif);
372 	local_bh_enable();
373 
374 	return sk;
375 }
376 
__inet_lookup_skb(struct inet_hashinfo * hashinfo,struct sk_buff * skb,const __be16 sport,const __be16 dport)377 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
378 					     struct sk_buff *skb,
379 					     const __be16 sport,
380 					     const __be16 dport)
381 {
382 	struct sock *sk;
383 	const struct iphdr *iph = ip_hdr(skb);
384 
385 	if (unlikely(sk = skb_steal_sock(skb)))
386 		return sk;
387 	else
388 		return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo,
389 				     iph->saddr, sport,
390 				     iph->daddr, dport, inet_iif(skb));
391 }
392 
393 extern int __inet_hash_connect(struct inet_timewait_death_row *death_row,
394 		struct sock *sk,
395 		u32 port_offset,
396 		int (*check_established)(struct inet_timewait_death_row *,
397 			struct sock *, __u16, struct inet_timewait_sock **),
398 		int (*hash)(struct sock *sk, struct inet_timewait_sock *twp));
399 
400 extern int inet_hash_connect(struct inet_timewait_death_row *death_row,
401 			     struct sock *sk);
402 #endif /* _INET_HASHTABLES_H */
403