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/ipv6.h> 20 #include <linux/list.h> 21 #include <linux/slab.h> 22 #include <linux/socket.h> 23 #include <linux/spinlock.h> 24 #include <linux/types.h> 25 #include <linux/wait.h> 26 #include <linux/vmalloc.h> 27 28 #include <net/inet_connection_sock.h> 29 #include <net/inet_sock.h> 30 #include <net/sock.h> 31 #include <net/tcp_states.h> 32 33 #include <asm/atomic.h> 34 #include <asm/byteorder.h> 35 36 /* This is for all connections with a full identity, no wildcards. 37 * One chain is dedicated to TIME_WAIT sockets. 38 * I'll experiment with dynamic table growth later. 39 */ 40 struct inet_ehash_bucket { 41 struct hlist_head chain; 42 struct hlist_head twchain; 43 }; 44 45 /* There are a few simple rules, which allow for local port reuse by 46 * an application. In essence: 47 * 48 * 1) Sockets bound to different interfaces may share a local port. 49 * Failing that, goto test 2. 50 * 2) If all sockets have sk->sk_reuse set, and none of them are in 51 * TCP_LISTEN state, the port may be shared. 52 * Failing that, goto test 3. 53 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local 54 * address, and none of them are the same, the port may be 55 * shared. 56 * Failing this, the port cannot be shared. 57 * 58 * The interesting point, is test #2. This is what an FTP server does 59 * all day. To optimize this case we use a specific flag bit defined 60 * below. As we add sockets to a bind bucket list, we perform a 61 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN)) 62 * As long as all sockets added to a bind bucket pass this test, 63 * the flag bit will be set. 64 * The resulting situation is that tcp_v[46]_verify_bind() can just check 65 * for this flag bit, if it is set and the socket trying to bind has 66 * sk->sk_reuse set, we don't even have to walk the owners list at all, 67 * we return that it is ok to bind this socket to the requested local port. 68 * 69 * Sounds like a lot of work, but it is worth it. In a more naive 70 * implementation (ie. current FreeBSD etc.) the entire list of ports 71 * must be walked for each data port opened by an ftp server. Needless 72 * to say, this does not scale at all. With a couple thousand FTP 73 * users logged onto your box, isn't it nice to know that new data 74 * ports are created in O(1) time? I thought so. ;-) -DaveM 75 */ 76 struct inet_bind_bucket { 77 struct net *ib_net; 78 unsigned short port; 79 signed short fastreuse; 80 struct hlist_node node; 81 struct hlist_head owners; 82 }; 83 84 #define inet_bind_bucket_for_each(tb, node, head) \ 85 hlist_for_each_entry(tb, node, head, node) 86 87 struct inet_bind_hashbucket { 88 spinlock_t lock; 89 struct hlist_head chain; 90 }; 91 92 /* This is for listening sockets, thus all sockets which possess wildcards. */ 93 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 94 95 struct inet_hashinfo { 96 /* This is for sockets with full identity only. Sockets here will 97 * always be without wildcards and will have the following invariant: 98 * 99 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 100 * 101 * TIME_WAIT sockets use a separate chain (twchain). 102 */ 103 struct inet_ehash_bucket *ehash; 104 rwlock_t *ehash_locks; 105 unsigned int ehash_size; 106 unsigned int ehash_locks_mask; 107 108 /* Ok, let's try this, I give up, we do need a local binding 109 * TCP hash as well as the others for fast bind/connect. 110 */ 111 struct inet_bind_hashbucket *bhash; 112 113 unsigned int bhash_size; 114 /* Note : 4 bytes padding on 64 bit arches */ 115 116 /* All sockets in TCP_LISTEN state will be in here. This is the only 117 * table where wildcard'd TCP sockets can exist. Hash function here 118 * is just local port number. 119 */ 120 struct hlist_head listening_hash[INET_LHTABLE_SIZE]; 121 122 /* All the above members are written once at bootup and 123 * never written again _or_ are predominantly read-access. 124 * 125 * Now align to a new cache line as all the following members 126 * are often dirty. 127 */ 128 rwlock_t lhash_lock ____cacheline_aligned; 129 atomic_t lhash_users; 130 wait_queue_head_t lhash_wait; 131 struct kmem_cache *bind_bucket_cachep; 132 }; 133 134 static inline struct inet_ehash_bucket *inet_ehash_bucket( 135 struct inet_hashinfo *hashinfo, 136 unsigned int hash) 137 { 138 return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)]; 139 } 140 141 static inline rwlock_t *inet_ehash_lockp( 142 struct inet_hashinfo *hashinfo, 143 unsigned int hash) 144 { 145 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 146 } 147 148 static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo) 149 { 150 unsigned int i, size = 256; 151 #if defined(CONFIG_PROVE_LOCKING) 152 unsigned int nr_pcpus = 2; 153 #else 154 unsigned int nr_pcpus = num_possible_cpus(); 155 #endif 156 if (nr_pcpus >= 4) 157 size = 512; 158 if (nr_pcpus >= 8) 159 size = 1024; 160 if (nr_pcpus >= 16) 161 size = 2048; 162 if (nr_pcpus >= 32) 163 size = 4096; 164 if (sizeof(rwlock_t) != 0) { 165 #ifdef CONFIG_NUMA 166 if (size * sizeof(rwlock_t) > PAGE_SIZE) 167 hashinfo->ehash_locks = vmalloc(size * sizeof(rwlock_t)); 168 else 169 #endif 170 hashinfo->ehash_locks = kmalloc(size * sizeof(rwlock_t), 171 GFP_KERNEL); 172 if (!hashinfo->ehash_locks) 173 return ENOMEM; 174 for (i = 0; i < size; i++) 175 rwlock_init(&hashinfo->ehash_locks[i]); 176 } 177 hashinfo->ehash_locks_mask = size - 1; 178 return 0; 179 } 180 181 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 182 { 183 if (hashinfo->ehash_locks) { 184 #ifdef CONFIG_NUMA 185 unsigned int size = (hashinfo->ehash_locks_mask + 1) * 186 sizeof(rwlock_t); 187 if (size > PAGE_SIZE) 188 vfree(hashinfo->ehash_locks); 189 else 190 #endif 191 kfree(hashinfo->ehash_locks); 192 hashinfo->ehash_locks = NULL; 193 } 194 } 195 196 extern struct inet_bind_bucket * 197 inet_bind_bucket_create(struct kmem_cache *cachep, 198 struct net *net, 199 struct inet_bind_hashbucket *head, 200 const unsigned short snum); 201 extern void inet_bind_bucket_destroy(struct kmem_cache *cachep, 202 struct inet_bind_bucket *tb); 203 204 static inline int inet_bhashfn(const __u16 lport, const int bhash_size) 205 { 206 return lport & (bhash_size - 1); 207 } 208 209 extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 210 const unsigned short snum); 211 212 /* These can have wildcards, don't try too hard. */ 213 static inline int inet_lhashfn(const unsigned short num) 214 { 215 return num & (INET_LHTABLE_SIZE - 1); 216 } 217 218 static inline int inet_sk_listen_hashfn(const struct sock *sk) 219 { 220 return inet_lhashfn(inet_sk(sk)->num); 221 } 222 223 /* Caller must disable local BH processing. */ 224 extern void __inet_inherit_port(struct sock *sk, struct sock *child); 225 226 extern void inet_put_port(struct sock *sk); 227 228 extern void inet_listen_wlock(struct inet_hashinfo *hashinfo); 229 230 /* 231 * - We may sleep inside this lock. 232 * - If sleeping is not required (or called from BH), 233 * use plain read_(un)lock(&inet_hashinfo.lhash_lock). 234 */ 235 static inline void inet_listen_lock(struct inet_hashinfo *hashinfo) 236 { 237 /* read_lock synchronizes to candidates to writers */ 238 read_lock(&hashinfo->lhash_lock); 239 atomic_inc(&hashinfo->lhash_users); 240 read_unlock(&hashinfo->lhash_lock); 241 } 242 243 static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo) 244 { 245 if (atomic_dec_and_test(&hashinfo->lhash_users)) 246 wake_up(&hashinfo->lhash_wait); 247 } 248 249 extern void __inet_hash_nolisten(struct sock *sk); 250 extern void inet_hash(struct sock *sk); 251 extern void inet_unhash(struct sock *sk); 252 253 extern struct sock *__inet_lookup_listener(struct net *net, 254 struct inet_hashinfo *hashinfo, 255 const __be32 daddr, 256 const unsigned short hnum, 257 const int dif); 258 259 static inline struct sock *inet_lookup_listener(struct net *net, 260 struct inet_hashinfo *hashinfo, 261 __be32 daddr, __be16 dport, int dif) 262 { 263 return __inet_lookup_listener(net, hashinfo, daddr, ntohs(dport), dif); 264 } 265 266 /* Socket demux engine toys. */ 267 /* What happens here is ugly; there's a pair of adjacent fields in 268 struct inet_sock; __be16 dport followed by __u16 num. We want to 269 search by pair, so we combine the keys into a single 32bit value 270 and compare with 32bit value read from &...->dport. Let's at least 271 make sure that it's not mixed with anything else... 272 On 64bit targets we combine comparisons with pair of adjacent __be32 273 fields in the same way. 274 */ 275 typedef __u32 __bitwise __portpair; 276 #ifdef __BIG_ENDIAN 277 #define INET_COMBINED_PORTS(__sport, __dport) \ 278 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 279 #else /* __LITTLE_ENDIAN */ 280 #define INET_COMBINED_PORTS(__sport, __dport) \ 281 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 282 #endif 283 284 #if (BITS_PER_LONG == 64) 285 typedef __u64 __bitwise __addrpair; 286 #ifdef __BIG_ENDIAN 287 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 288 const __addrpair __name = (__force __addrpair) ( \ 289 (((__force __u64)(__be32)(__saddr)) << 32) | \ 290 ((__force __u64)(__be32)(__daddr))); 291 #else /* __LITTLE_ENDIAN */ 292 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 293 const __addrpair __name = (__force __addrpair) ( \ 294 (((__force __u64)(__be32)(__daddr)) << 32) | \ 295 ((__force __u64)(__be32)(__saddr))); 296 #endif /* __BIG_ENDIAN */ 297 #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 298 (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net) && \ 299 ((*((__addrpair *)&(inet_sk(__sk)->daddr))) == (__cookie)) && \ 300 ((*((__portpair *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 301 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 302 #define INET_TW_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 303 (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net) && \ 304 ((*((__addrpair *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ 305 ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 306 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 307 #else /* 32-bit arch */ 308 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) 309 #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif) \ 310 (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net) && \ 311 (inet_sk(__sk)->daddr == (__saddr)) && \ 312 (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ 313 ((*((__portpair *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 314 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 315 #define INET_TW_MATCH(__sk, __net, __hash,__cookie, __saddr, __daddr, __ports, __dif) \ 316 (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net) && \ 317 (inet_twsk(__sk)->tw_daddr == (__saddr)) && \ 318 (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ 319 ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 320 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 321 #endif /* 64-bit arch */ 322 323 /* 324 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 325 * not check it for lookups anymore, thanks Alexey. -DaveM 326 * 327 * Local BH must be disabled here. 328 */ 329 extern struct sock * __inet_lookup_established(struct net *net, 330 struct inet_hashinfo *hashinfo, 331 const __be32 saddr, const __be16 sport, 332 const __be32 daddr, const u16 hnum, const int dif); 333 334 static inline struct sock * 335 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 336 const __be32 saddr, const __be16 sport, 337 const __be32 daddr, const __be16 dport, 338 const int dif) 339 { 340 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 341 ntohs(dport), dif); 342 } 343 344 static inline struct sock *__inet_lookup(struct net *net, 345 struct inet_hashinfo *hashinfo, 346 const __be32 saddr, const __be16 sport, 347 const __be32 daddr, const __be16 dport, 348 const int dif) 349 { 350 u16 hnum = ntohs(dport); 351 struct sock *sk = __inet_lookup_established(net, hashinfo, 352 saddr, sport, daddr, hnum, dif); 353 354 return sk ? : __inet_lookup_listener(net, hashinfo, daddr, hnum, dif); 355 } 356 357 static inline struct sock *inet_lookup(struct net *net, 358 struct inet_hashinfo *hashinfo, 359 const __be32 saddr, const __be16 sport, 360 const __be32 daddr, const __be16 dport, 361 const int dif) 362 { 363 struct sock *sk; 364 365 local_bh_disable(); 366 sk = __inet_lookup(net, hashinfo, saddr, sport, daddr, dport, dif); 367 local_bh_enable(); 368 369 return sk; 370 } 371 372 extern int __inet_hash_connect(struct inet_timewait_death_row *death_row, 373 struct sock *sk, u32 port_offset, 374 int (*check_established)(struct inet_timewait_death_row *, 375 struct sock *, __u16, struct inet_timewait_sock **), 376 void (*hash)(struct sock *sk)); 377 extern int inet_hash_connect(struct inet_timewait_death_row *death_row, 378 struct sock *sk); 379 #endif /* _INET_HASHTABLES_H */ 380