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 27 #include <net/inet_connection_sock.h> 28 #include <net/inet_sock.h> 29 #include <net/route.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 * New scheme, half the table is for TIME_WAIT, the other half is 38 * for the rest. I'll experiment with dynamic table growth later. 39 */ 40 struct inet_ehash_bucket { 41 rwlock_t lock; 42 struct hlist_head chain; 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 unsigned short port; 78 signed short fastreuse; 79 struct hlist_node node; 80 struct hlist_head owners; 81 }; 82 83 #define inet_bind_bucket_for_each(tb, node, head) \ 84 hlist_for_each_entry(tb, node, head, node) 85 86 struct inet_bind_hashbucket { 87 spinlock_t lock; 88 struct hlist_head chain; 89 }; 90 91 /* This is for listening sockets, thus all sockets which possess wildcards. */ 92 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 93 94 struct inet_hashinfo { 95 /* This is for sockets with full identity only. Sockets here will 96 * always be without wildcards and will have the following invariant: 97 * 98 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 99 * 100 * First half of the table is for sockets not in TIME_WAIT, second half 101 * is for TIME_WAIT sockets only. 102 */ 103 struct inet_ehash_bucket *ehash; 104 105 /* Ok, let's try this, I give up, we do need a local binding 106 * TCP hash as well as the others for fast bind/connect. 107 */ 108 struct inet_bind_hashbucket *bhash; 109 110 int bhash_size; 111 unsigned int ehash_size; 112 113 /* All sockets in TCP_LISTEN state will be in here. This is the only 114 * table where wildcard'd TCP sockets can exist. Hash function here 115 * is just local port number. 116 */ 117 struct hlist_head listening_hash[INET_LHTABLE_SIZE]; 118 119 /* All the above members are written once at bootup and 120 * never written again _or_ are predominantly read-access. 121 * 122 * Now align to a new cache line as all the following members 123 * are often dirty. 124 */ 125 rwlock_t lhash_lock ____cacheline_aligned; 126 atomic_t lhash_users; 127 wait_queue_head_t lhash_wait; 128 kmem_cache_t *bind_bucket_cachep; 129 }; 130 131 static inline struct inet_ehash_bucket *inet_ehash_bucket( 132 struct inet_hashinfo *hashinfo, 133 unsigned int hash) 134 { 135 return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)]; 136 } 137 138 extern struct inet_bind_bucket * 139 inet_bind_bucket_create(kmem_cache_t *cachep, 140 struct inet_bind_hashbucket *head, 141 const unsigned short snum); 142 extern void inet_bind_bucket_destroy(kmem_cache_t *cachep, 143 struct inet_bind_bucket *tb); 144 145 static inline int inet_bhashfn(const __u16 lport, const int bhash_size) 146 { 147 return lport & (bhash_size - 1); 148 } 149 150 extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 151 const unsigned short snum); 152 153 /* These can have wildcards, don't try too hard. */ 154 static inline int inet_lhashfn(const unsigned short num) 155 { 156 return num & (INET_LHTABLE_SIZE - 1); 157 } 158 159 static inline int inet_sk_listen_hashfn(const struct sock *sk) 160 { 161 return inet_lhashfn(inet_sk(sk)->num); 162 } 163 164 /* Caller must disable local BH processing. */ 165 static inline void __inet_inherit_port(struct inet_hashinfo *table, 166 struct sock *sk, struct sock *child) 167 { 168 const int bhash = inet_bhashfn(inet_sk(child)->num, table->bhash_size); 169 struct inet_bind_hashbucket *head = &table->bhash[bhash]; 170 struct inet_bind_bucket *tb; 171 172 spin_lock(&head->lock); 173 tb = inet_csk(sk)->icsk_bind_hash; 174 sk_add_bind_node(child, &tb->owners); 175 inet_csk(child)->icsk_bind_hash = tb; 176 spin_unlock(&head->lock); 177 } 178 179 static inline void inet_inherit_port(struct inet_hashinfo *table, 180 struct sock *sk, struct sock *child) 181 { 182 local_bh_disable(); 183 __inet_inherit_port(table, sk, child); 184 local_bh_enable(); 185 } 186 187 extern void inet_put_port(struct inet_hashinfo *table, struct sock *sk); 188 189 extern void inet_listen_wlock(struct inet_hashinfo *hashinfo); 190 191 /* 192 * - We may sleep inside this lock. 193 * - If sleeping is not required (or called from BH), 194 * use plain read_(un)lock(&inet_hashinfo.lhash_lock). 195 */ 196 static inline void inet_listen_lock(struct inet_hashinfo *hashinfo) 197 { 198 /* read_lock synchronizes to candidates to writers */ 199 read_lock(&hashinfo->lhash_lock); 200 atomic_inc(&hashinfo->lhash_users); 201 read_unlock(&hashinfo->lhash_lock); 202 } 203 204 static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo) 205 { 206 if (atomic_dec_and_test(&hashinfo->lhash_users)) 207 wake_up(&hashinfo->lhash_wait); 208 } 209 210 static inline void __inet_hash(struct inet_hashinfo *hashinfo, 211 struct sock *sk, const int listen_possible) 212 { 213 struct hlist_head *list; 214 rwlock_t *lock; 215 216 BUG_TRAP(sk_unhashed(sk)); 217 if (listen_possible && sk->sk_state == TCP_LISTEN) { 218 list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; 219 lock = &hashinfo->lhash_lock; 220 inet_listen_wlock(hashinfo); 221 } else { 222 struct inet_ehash_bucket *head; 223 sk->sk_hash = inet_sk_ehashfn(sk); 224 head = inet_ehash_bucket(hashinfo, sk->sk_hash); 225 list = &head->chain; 226 lock = &head->lock; 227 write_lock(lock); 228 } 229 __sk_add_node(sk, list); 230 sock_prot_inc_use(sk->sk_prot); 231 write_unlock(lock); 232 if (listen_possible && sk->sk_state == TCP_LISTEN) 233 wake_up(&hashinfo->lhash_wait); 234 } 235 236 static inline void inet_hash(struct inet_hashinfo *hashinfo, struct sock *sk) 237 { 238 if (sk->sk_state != TCP_CLOSE) { 239 local_bh_disable(); 240 __inet_hash(hashinfo, sk, 1); 241 local_bh_enable(); 242 } 243 } 244 245 static inline void inet_unhash(struct inet_hashinfo *hashinfo, struct sock *sk) 246 { 247 rwlock_t *lock; 248 249 if (sk_unhashed(sk)) 250 goto out; 251 252 if (sk->sk_state == TCP_LISTEN) { 253 local_bh_disable(); 254 inet_listen_wlock(hashinfo); 255 lock = &hashinfo->lhash_lock; 256 } else { 257 lock = &inet_ehash_bucket(hashinfo, sk->sk_hash)->lock; 258 write_lock_bh(lock); 259 } 260 261 if (__sk_del_node_init(sk)) 262 sock_prot_dec_use(sk->sk_prot); 263 write_unlock_bh(lock); 264 out: 265 if (sk->sk_state == TCP_LISTEN) 266 wake_up(&hashinfo->lhash_wait); 267 } 268 269 static inline int inet_iif(const struct sk_buff *skb) 270 { 271 return ((struct rtable *)skb->dst)->rt_iif; 272 } 273 274 extern struct sock *__inet_lookup_listener(const struct hlist_head *head, 275 const u32 daddr, 276 const unsigned short hnum, 277 const int dif); 278 279 /* Optimize the common listener case. */ 280 static inline struct sock * 281 inet_lookup_listener(struct inet_hashinfo *hashinfo, 282 const u32 daddr, 283 const unsigned short hnum, const int dif) 284 { 285 struct sock *sk = NULL; 286 const struct hlist_head *head; 287 288 read_lock(&hashinfo->lhash_lock); 289 head = &hashinfo->listening_hash[inet_lhashfn(hnum)]; 290 if (!hlist_empty(head)) { 291 const struct inet_sock *inet = inet_sk((sk = __sk_head(head))); 292 293 if (inet->num == hnum && !sk->sk_node.next && 294 (!inet->rcv_saddr || inet->rcv_saddr == daddr) && 295 (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) && 296 !sk->sk_bound_dev_if) 297 goto sherry_cache; 298 sk = __inet_lookup_listener(head, daddr, hnum, dif); 299 } 300 if (sk) { 301 sherry_cache: 302 sock_hold(sk); 303 } 304 read_unlock(&hashinfo->lhash_lock); 305 return sk; 306 } 307 308 /* Socket demux engine toys. */ 309 #ifdef __BIG_ENDIAN 310 #define INET_COMBINED_PORTS(__sport, __dport) \ 311 (((__u32)(__sport) << 16) | (__u32)(__dport)) 312 #else /* __LITTLE_ENDIAN */ 313 #define INET_COMBINED_PORTS(__sport, __dport) \ 314 (((__u32)(__dport) << 16) | (__u32)(__sport)) 315 #endif 316 317 #if (BITS_PER_LONG == 64) 318 #ifdef __BIG_ENDIAN 319 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 320 const __u64 __name = (((__u64)(__saddr)) << 32) | ((__u64)(__daddr)); 321 #else /* __LITTLE_ENDIAN */ 322 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 323 const __u64 __name = (((__u64)(__daddr)) << 32) | ((__u64)(__saddr)); 324 #endif /* __BIG_ENDIAN */ 325 #define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 326 (((__sk)->sk_hash == (__hash)) && \ 327 ((*((__u64 *)&(inet_sk(__sk)->daddr))) == (__cookie)) && \ 328 ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 329 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 330 #define INET_TW_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 331 (((__sk)->sk_hash == (__hash)) && \ 332 ((*((__u64 *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ 333 ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 334 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 335 #else /* 32-bit arch */ 336 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) 337 #define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif) \ 338 (((__sk)->sk_hash == (__hash)) && \ 339 (inet_sk(__sk)->daddr == (__saddr)) && \ 340 (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ 341 ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 342 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 343 #define INET_TW_MATCH(__sk, __hash,__cookie, __saddr, __daddr, __ports, __dif) \ 344 (((__sk)->sk_hash == (__hash)) && \ 345 (inet_twsk(__sk)->tw_daddr == (__saddr)) && \ 346 (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ 347 ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 348 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 349 #endif /* 64-bit arch */ 350 351 /* 352 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 353 * not check it for lookups anymore, thanks Alexey. -DaveM 354 * 355 * Local BH must be disabled here. 356 */ 357 static inline struct sock * 358 __inet_lookup_established(struct inet_hashinfo *hashinfo, 359 const u32 saddr, const u16 sport, 360 const u32 daddr, const u16 hnum, 361 const int dif) 362 { 363 INET_ADDR_COOKIE(acookie, saddr, daddr) 364 const __u32 ports = INET_COMBINED_PORTS(sport, hnum); 365 struct sock *sk; 366 const struct hlist_node *node; 367 /* Optimize here for direct hit, only listening connections can 368 * have wildcards anyways. 369 */ 370 unsigned int hash = inet_ehashfn(daddr, hnum, saddr, sport); 371 struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash); 372 373 prefetch(head->chain.first); 374 read_lock(&head->lock); 375 sk_for_each(sk, node, &head->chain) { 376 if (INET_MATCH(sk, hash, acookie, saddr, daddr, ports, dif)) 377 goto hit; /* You sunk my battleship! */ 378 } 379 380 /* Must check for a TIME_WAIT'er before going to listener hash. */ 381 sk_for_each(sk, node, &(head + hashinfo->ehash_size)->chain) { 382 if (INET_TW_MATCH(sk, hash, acookie, saddr, daddr, ports, dif)) 383 goto hit; 384 } 385 sk = NULL; 386 out: 387 read_unlock(&head->lock); 388 return sk; 389 hit: 390 sock_hold(sk); 391 goto out; 392 } 393 394 static inline struct sock *__inet_lookup(struct inet_hashinfo *hashinfo, 395 const u32 saddr, const u16 sport, 396 const u32 daddr, const u16 hnum, 397 const int dif) 398 { 399 struct sock *sk = __inet_lookup_established(hashinfo, saddr, sport, daddr, 400 hnum, dif); 401 return sk ? : inet_lookup_listener(hashinfo, daddr, hnum, dif); 402 } 403 404 static inline struct sock *inet_lookup(struct inet_hashinfo *hashinfo, 405 const u32 saddr, const u16 sport, 406 const u32 daddr, const u16 dport, 407 const int dif) 408 { 409 struct sock *sk; 410 411 local_bh_disable(); 412 sk = __inet_lookup(hashinfo, saddr, sport, daddr, ntohs(dport), dif); 413 local_bh_enable(); 414 415 return sk; 416 } 417 418 extern int inet_hash_connect(struct inet_timewait_death_row *death_row, 419 struct sock *sk); 420 #endif /* _INET_HASHTABLES_H */ 421