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 #include <linux/config.h> 18 19 #include <linux/interrupt.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/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 spinlock_t portalloc_lock; 129 kmem_cache_t *bind_bucket_cachep; 130 int port_rover; 131 }; 132 133 static inline unsigned int inet_ehashfn(const __u32 laddr, const __u16 lport, 134 const __u32 faddr, const __u16 fport) 135 { 136 unsigned int h = (laddr ^ lport) ^ (faddr ^ fport); 137 h ^= h >> 16; 138 h ^= h >> 8; 139 return h; 140 } 141 142 static inline int inet_sk_ehashfn(const struct sock *sk) 143 { 144 const struct inet_sock *inet = inet_sk(sk); 145 const __u32 laddr = inet->rcv_saddr; 146 const __u16 lport = inet->num; 147 const __u32 faddr = inet->daddr; 148 const __u16 fport = inet->dport; 149 150 return inet_ehashfn(laddr, lport, faddr, fport); 151 } 152 153 static inline struct inet_ehash_bucket *inet_ehash_bucket( 154 struct inet_hashinfo *hashinfo, 155 unsigned int hash) 156 { 157 return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)]; 158 } 159 160 extern struct inet_bind_bucket * 161 inet_bind_bucket_create(kmem_cache_t *cachep, 162 struct inet_bind_hashbucket *head, 163 const unsigned short snum); 164 extern void inet_bind_bucket_destroy(kmem_cache_t *cachep, 165 struct inet_bind_bucket *tb); 166 167 static inline int inet_bhashfn(const __u16 lport, const int bhash_size) 168 { 169 return lport & (bhash_size - 1); 170 } 171 172 extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 173 const unsigned short snum); 174 175 /* These can have wildcards, don't try too hard. */ 176 static inline int inet_lhashfn(const unsigned short num) 177 { 178 return num & (INET_LHTABLE_SIZE - 1); 179 } 180 181 static inline int inet_sk_listen_hashfn(const struct sock *sk) 182 { 183 return inet_lhashfn(inet_sk(sk)->num); 184 } 185 186 /* Caller must disable local BH processing. */ 187 static inline void __inet_inherit_port(struct inet_hashinfo *table, 188 struct sock *sk, struct sock *child) 189 { 190 const int bhash = inet_bhashfn(inet_sk(child)->num, table->bhash_size); 191 struct inet_bind_hashbucket *head = &table->bhash[bhash]; 192 struct inet_bind_bucket *tb; 193 194 spin_lock(&head->lock); 195 tb = inet_csk(sk)->icsk_bind_hash; 196 sk_add_bind_node(child, &tb->owners); 197 inet_csk(child)->icsk_bind_hash = tb; 198 spin_unlock(&head->lock); 199 } 200 201 static inline void inet_inherit_port(struct inet_hashinfo *table, 202 struct sock *sk, struct sock *child) 203 { 204 local_bh_disable(); 205 __inet_inherit_port(table, sk, child); 206 local_bh_enable(); 207 } 208 209 extern void inet_put_port(struct inet_hashinfo *table, struct sock *sk); 210 211 extern void inet_listen_wlock(struct inet_hashinfo *hashinfo); 212 213 /* 214 * - We may sleep inside this lock. 215 * - If sleeping is not required (or called from BH), 216 * use plain read_(un)lock(&inet_hashinfo.lhash_lock). 217 */ 218 static inline void inet_listen_lock(struct inet_hashinfo *hashinfo) 219 { 220 /* read_lock synchronizes to candidates to writers */ 221 read_lock(&hashinfo->lhash_lock); 222 atomic_inc(&hashinfo->lhash_users); 223 read_unlock(&hashinfo->lhash_lock); 224 } 225 226 static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo) 227 { 228 if (atomic_dec_and_test(&hashinfo->lhash_users)) 229 wake_up(&hashinfo->lhash_wait); 230 } 231 232 static inline void __inet_hash(struct inet_hashinfo *hashinfo, 233 struct sock *sk, const int listen_possible) 234 { 235 struct hlist_head *list; 236 rwlock_t *lock; 237 238 BUG_TRAP(sk_unhashed(sk)); 239 if (listen_possible && sk->sk_state == TCP_LISTEN) { 240 list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; 241 lock = &hashinfo->lhash_lock; 242 inet_listen_wlock(hashinfo); 243 } else { 244 struct inet_ehash_bucket *head; 245 sk->sk_hash = inet_sk_ehashfn(sk); 246 head = inet_ehash_bucket(hashinfo, sk->sk_hash); 247 list = &head->chain; 248 lock = &head->lock; 249 write_lock(lock); 250 } 251 __sk_add_node(sk, list); 252 sock_prot_inc_use(sk->sk_prot); 253 write_unlock(lock); 254 if (listen_possible && sk->sk_state == TCP_LISTEN) 255 wake_up(&hashinfo->lhash_wait); 256 } 257 258 static inline void inet_hash(struct inet_hashinfo *hashinfo, struct sock *sk) 259 { 260 if (sk->sk_state != TCP_CLOSE) { 261 local_bh_disable(); 262 __inet_hash(hashinfo, sk, 1); 263 local_bh_enable(); 264 } 265 } 266 267 static inline void inet_unhash(struct inet_hashinfo *hashinfo, struct sock *sk) 268 { 269 rwlock_t *lock; 270 271 if (sk_unhashed(sk)) 272 goto out; 273 274 if (sk->sk_state == TCP_LISTEN) { 275 local_bh_disable(); 276 inet_listen_wlock(hashinfo); 277 lock = &hashinfo->lhash_lock; 278 } else { 279 lock = &inet_ehash_bucket(hashinfo, sk->sk_hash)->lock; 280 write_lock_bh(lock); 281 } 282 283 if (__sk_del_node_init(sk)) 284 sock_prot_dec_use(sk->sk_prot); 285 write_unlock_bh(lock); 286 out: 287 if (sk->sk_state == TCP_LISTEN) 288 wake_up(&hashinfo->lhash_wait); 289 } 290 291 static inline int inet_iif(const struct sk_buff *skb) 292 { 293 return ((struct rtable *)skb->dst)->rt_iif; 294 } 295 296 extern struct sock *__inet_lookup_listener(const struct hlist_head *head, 297 const u32 daddr, 298 const unsigned short hnum, 299 const int dif); 300 301 /* Optimize the common listener case. */ 302 static inline struct sock * 303 inet_lookup_listener(struct inet_hashinfo *hashinfo, 304 const u32 daddr, 305 const unsigned short hnum, const int dif) 306 { 307 struct sock *sk = NULL; 308 const struct hlist_head *head; 309 310 read_lock(&hashinfo->lhash_lock); 311 head = &hashinfo->listening_hash[inet_lhashfn(hnum)]; 312 if (!hlist_empty(head)) { 313 const struct inet_sock *inet = inet_sk((sk = __sk_head(head))); 314 315 if (inet->num == hnum && !sk->sk_node.next && 316 (!inet->rcv_saddr || inet->rcv_saddr == daddr) && 317 (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) && 318 !sk->sk_bound_dev_if) 319 goto sherry_cache; 320 sk = __inet_lookup_listener(head, daddr, hnum, dif); 321 } 322 if (sk) { 323 sherry_cache: 324 sock_hold(sk); 325 } 326 read_unlock(&hashinfo->lhash_lock); 327 return sk; 328 } 329 330 /* Socket demux engine toys. */ 331 #ifdef __BIG_ENDIAN 332 #define INET_COMBINED_PORTS(__sport, __dport) \ 333 (((__u32)(__sport) << 16) | (__u32)(__dport)) 334 #else /* __LITTLE_ENDIAN */ 335 #define INET_COMBINED_PORTS(__sport, __dport) \ 336 (((__u32)(__dport) << 16) | (__u32)(__sport)) 337 #endif 338 339 #if (BITS_PER_LONG == 64) 340 #ifdef __BIG_ENDIAN 341 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 342 const __u64 __name = (((__u64)(__saddr)) << 32) | ((__u64)(__daddr)); 343 #else /* __LITTLE_ENDIAN */ 344 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 345 const __u64 __name = (((__u64)(__daddr)) << 32) | ((__u64)(__saddr)); 346 #endif /* __BIG_ENDIAN */ 347 #define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 348 (((__sk)->sk_hash == (__hash)) && \ 349 ((*((__u64 *)&(inet_sk(__sk)->daddr))) == (__cookie)) && \ 350 ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 351 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 352 #define INET_TW_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 353 (((__sk)->sk_hash == (__hash)) && \ 354 ((*((__u64 *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ 355 ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 356 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 357 #else /* 32-bit arch */ 358 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) 359 #define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif) \ 360 (((__sk)->sk_hash == (__hash)) && \ 361 (inet_sk(__sk)->daddr == (__saddr)) && \ 362 (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ 363 ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 364 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 365 #define INET_TW_MATCH(__sk, __hash,__cookie, __saddr, __daddr, __ports, __dif) \ 366 (((__sk)->sk_hash == (__hash)) && \ 367 (inet_twsk(__sk)->tw_daddr == (__saddr)) && \ 368 (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ 369 ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 370 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 371 #endif /* 64-bit arch */ 372 373 /* 374 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 375 * not check it for lookups anymore, thanks Alexey. -DaveM 376 * 377 * Local BH must be disabled here. 378 */ 379 static inline struct sock * 380 __inet_lookup_established(struct inet_hashinfo *hashinfo, 381 const u32 saddr, const u16 sport, 382 const u32 daddr, const u16 hnum, 383 const int dif) 384 { 385 INET_ADDR_COOKIE(acookie, saddr, daddr) 386 const __u32 ports = INET_COMBINED_PORTS(sport, hnum); 387 struct sock *sk; 388 const struct hlist_node *node; 389 /* Optimize here for direct hit, only listening connections can 390 * have wildcards anyways. 391 */ 392 unsigned int hash = inet_ehashfn(daddr, hnum, saddr, sport); 393 struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash); 394 395 prefetch(head->chain.first); 396 read_lock(&head->lock); 397 sk_for_each(sk, node, &head->chain) { 398 if (INET_MATCH(sk, hash, acookie, saddr, daddr, ports, dif)) 399 goto hit; /* You sunk my battleship! */ 400 } 401 402 /* Must check for a TIME_WAIT'er before going to listener hash. */ 403 sk_for_each(sk, node, &(head + hashinfo->ehash_size)->chain) { 404 if (INET_TW_MATCH(sk, hash, acookie, saddr, daddr, ports, dif)) 405 goto hit; 406 } 407 sk = NULL; 408 out: 409 read_unlock(&head->lock); 410 return sk; 411 hit: 412 sock_hold(sk); 413 goto out; 414 } 415 416 static inline struct sock *__inet_lookup(struct inet_hashinfo *hashinfo, 417 const u32 saddr, const u16 sport, 418 const u32 daddr, const u16 hnum, 419 const int dif) 420 { 421 struct sock *sk = __inet_lookup_established(hashinfo, saddr, sport, daddr, 422 hnum, dif); 423 return sk ? : inet_lookup_listener(hashinfo, daddr, hnum, dif); 424 } 425 426 static inline struct sock *inet_lookup(struct inet_hashinfo *hashinfo, 427 const u32 saddr, const u16 sport, 428 const u32 daddr, const u16 dport, 429 const int dif) 430 { 431 struct sock *sk; 432 433 local_bh_disable(); 434 sk = __inet_lookup(hashinfo, saddr, sport, daddr, ntohs(dport), dif); 435 local_bh_enable(); 436 437 return sk; 438 } 439 #endif /* _INET_HASHTABLES_H */ 440