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 <asm/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_head chain; 45 struct hlist_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 struct net *ib_net; 81 unsigned short port; 82 signed short fastreuse; 83 struct hlist_node node; 84 struct hlist_head owners; 85 }; 86 87 #define inet_bind_bucket_for_each(tb, node, head) \ 88 hlist_for_each_entry(tb, node, head, node) 89 90 struct inet_bind_hashbucket { 91 spinlock_t lock; 92 struct hlist_head chain; 93 }; 94 95 /* This is for listening sockets, thus all sockets which possess wildcards. */ 96 #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ 97 98 struct inet_hashinfo { 99 /* This is for sockets with full identity only. Sockets here will 100 * always be without wildcards and will have the following invariant: 101 * 102 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE 103 * 104 * TIME_WAIT sockets use a separate chain (twchain). 105 */ 106 struct inet_ehash_bucket *ehash; 107 rwlock_t *ehash_locks; 108 unsigned int ehash_size; 109 unsigned int ehash_locks_mask; 110 111 /* Ok, let's try this, I give up, we do need a local binding 112 * TCP hash as well as the others for fast bind/connect. 113 */ 114 struct inet_bind_hashbucket *bhash; 115 116 unsigned int bhash_size; 117 /* Note : 4 bytes padding on 64 bit arches */ 118 119 /* All sockets in TCP_LISTEN state will be in here. This is the only 120 * table where wildcard'd TCP sockets can exist. Hash function here 121 * is just local port number. 122 */ 123 struct hlist_head listening_hash[INET_LHTABLE_SIZE]; 124 125 /* All the above members are written once at bootup and 126 * never written again _or_ are predominantly read-access. 127 * 128 * Now align to a new cache line as all the following members 129 * are often dirty. 130 */ 131 rwlock_t lhash_lock ____cacheline_aligned; 132 atomic_t lhash_users; 133 wait_queue_head_t lhash_wait; 134 struct kmem_cache *bind_bucket_cachep; 135 }; 136 137 static inline struct inet_ehash_bucket *inet_ehash_bucket( 138 struct inet_hashinfo *hashinfo, 139 unsigned int hash) 140 { 141 return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)]; 142 } 143 144 static inline rwlock_t *inet_ehash_lockp( 145 struct inet_hashinfo *hashinfo, 146 unsigned int hash) 147 { 148 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask]; 149 } 150 151 static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo) 152 { 153 unsigned int i, size = 256; 154 #if defined(CONFIG_PROVE_LOCKING) 155 unsigned int nr_pcpus = 2; 156 #else 157 unsigned int nr_pcpus = num_possible_cpus(); 158 #endif 159 if (nr_pcpus >= 4) 160 size = 512; 161 if (nr_pcpus >= 8) 162 size = 1024; 163 if (nr_pcpus >= 16) 164 size = 2048; 165 if (nr_pcpus >= 32) 166 size = 4096; 167 if (sizeof(rwlock_t) != 0) { 168 #ifdef CONFIG_NUMA 169 if (size * sizeof(rwlock_t) > PAGE_SIZE) 170 hashinfo->ehash_locks = vmalloc(size * sizeof(rwlock_t)); 171 else 172 #endif 173 hashinfo->ehash_locks = kmalloc(size * sizeof(rwlock_t), 174 GFP_KERNEL); 175 if (!hashinfo->ehash_locks) 176 return ENOMEM; 177 for (i = 0; i < size; i++) 178 rwlock_init(&hashinfo->ehash_locks[i]); 179 } 180 hashinfo->ehash_locks_mask = size - 1; 181 return 0; 182 } 183 184 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo) 185 { 186 if (hashinfo->ehash_locks) { 187 #ifdef CONFIG_NUMA 188 unsigned int size = (hashinfo->ehash_locks_mask + 1) * 189 sizeof(rwlock_t); 190 if (size > PAGE_SIZE) 191 vfree(hashinfo->ehash_locks); 192 else 193 #endif 194 kfree(hashinfo->ehash_locks); 195 hashinfo->ehash_locks = NULL; 196 } 197 } 198 199 extern struct inet_bind_bucket * 200 inet_bind_bucket_create(struct kmem_cache *cachep, 201 struct net *net, 202 struct inet_bind_hashbucket *head, 203 const unsigned short snum); 204 extern void inet_bind_bucket_destroy(struct kmem_cache *cachep, 205 struct inet_bind_bucket *tb); 206 207 static inline int inet_bhashfn(struct net *net, 208 const __u16 lport, const int bhash_size) 209 { 210 return (lport + net_hash_mix(net)) & (bhash_size - 1); 211 } 212 213 extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 214 const unsigned short snum); 215 216 /* These can have wildcards, don't try too hard. */ 217 static inline int inet_lhashfn(struct net *net, const unsigned short num) 218 { 219 return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1); 220 } 221 222 static inline int inet_sk_listen_hashfn(const struct sock *sk) 223 { 224 return inet_lhashfn(sock_net(sk), inet_sk(sk)->num); 225 } 226 227 /* Caller must disable local BH processing. */ 228 extern void __inet_inherit_port(struct sock *sk, struct sock *child); 229 230 extern void inet_put_port(struct sock *sk); 231 232 extern void inet_listen_wlock(struct inet_hashinfo *hashinfo); 233 234 /* 235 * - We may sleep inside this lock. 236 * - If sleeping is not required (or called from BH), 237 * use plain read_(un)lock(&inet_hashinfo.lhash_lock). 238 */ 239 static inline void inet_listen_lock(struct inet_hashinfo *hashinfo) 240 { 241 /* read_lock synchronizes to candidates to writers */ 242 read_lock(&hashinfo->lhash_lock); 243 atomic_inc(&hashinfo->lhash_users); 244 read_unlock(&hashinfo->lhash_lock); 245 } 246 247 static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo) 248 { 249 if (atomic_dec_and_test(&hashinfo->lhash_users)) 250 wake_up(&hashinfo->lhash_wait); 251 } 252 253 extern void __inet_hash_nolisten(struct sock *sk); 254 extern void inet_hash(struct sock *sk); 255 extern void inet_unhash(struct sock *sk); 256 257 extern struct sock *__inet_lookup_listener(struct net *net, 258 struct inet_hashinfo *hashinfo, 259 const __be32 daddr, 260 const unsigned short hnum, 261 const int dif); 262 263 static inline struct sock *inet_lookup_listener(struct net *net, 264 struct inet_hashinfo *hashinfo, 265 __be32 daddr, __be16 dport, int dif) 266 { 267 return __inet_lookup_listener(net, hashinfo, daddr, ntohs(dport), dif); 268 } 269 270 /* Socket demux engine toys. */ 271 /* What happens here is ugly; there's a pair of adjacent fields in 272 struct inet_sock; __be16 dport followed by __u16 num. We want to 273 search by pair, so we combine the keys into a single 32bit value 274 and compare with 32bit value read from &...->dport. Let's at least 275 make sure that it's not mixed with anything else... 276 On 64bit targets we combine comparisons with pair of adjacent __be32 277 fields in the same way. 278 */ 279 typedef __u32 __bitwise __portpair; 280 #ifdef __BIG_ENDIAN 281 #define INET_COMBINED_PORTS(__sport, __dport) \ 282 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport))) 283 #else /* __LITTLE_ENDIAN */ 284 #define INET_COMBINED_PORTS(__sport, __dport) \ 285 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport))) 286 #endif 287 288 #if (BITS_PER_LONG == 64) 289 typedef __u64 __bitwise __addrpair; 290 #ifdef __BIG_ENDIAN 291 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 292 const __addrpair __name = (__force __addrpair) ( \ 293 (((__force __u64)(__be32)(__saddr)) << 32) | \ 294 ((__force __u64)(__be32)(__daddr))); 295 #else /* __LITTLE_ENDIAN */ 296 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ 297 const __addrpair __name = (__force __addrpair) ( \ 298 (((__force __u64)(__be32)(__daddr)) << 32) | \ 299 ((__force __u64)(__be32)(__saddr))); 300 #endif /* __BIG_ENDIAN */ 301 #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 302 (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net) && \ 303 ((*((__addrpair *)&(inet_sk(__sk)->daddr))) == (__cookie)) && \ 304 ((*((__portpair *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 305 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 306 #define INET_TW_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ 307 (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net) && \ 308 ((*((__addrpair *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ 309 ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 310 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 311 #else /* 32-bit arch */ 312 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) 313 #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif) \ 314 (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net) && \ 315 (inet_sk(__sk)->daddr == (__saddr)) && \ 316 (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ 317 ((*((__portpair *)&(inet_sk(__sk)->dport))) == (__ports)) && \ 318 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 319 #define INET_TW_MATCH(__sk, __net, __hash,__cookie, __saddr, __daddr, __ports, __dif) \ 320 (((__sk)->sk_hash == (__hash)) && sock_net((__sk)) == (__net) && \ 321 (inet_twsk(__sk)->tw_daddr == (__saddr)) && \ 322 (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ 323 ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ 324 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) 325 #endif /* 64-bit arch */ 326 327 /* 328 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need 329 * not check it for lookups anymore, thanks Alexey. -DaveM 330 * 331 * Local BH must be disabled here. 332 */ 333 extern struct sock * __inet_lookup_established(struct net *net, 334 struct inet_hashinfo *hashinfo, 335 const __be32 saddr, const __be16 sport, 336 const __be32 daddr, const u16 hnum, const int dif); 337 338 static inline struct sock * 339 inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo, 340 const __be32 saddr, const __be16 sport, 341 const __be32 daddr, const __be16 dport, 342 const int dif) 343 { 344 return __inet_lookup_established(net, hashinfo, saddr, sport, daddr, 345 ntohs(dport), dif); 346 } 347 348 static inline struct sock *__inet_lookup(struct net *net, 349 struct inet_hashinfo *hashinfo, 350 const __be32 saddr, const __be16 sport, 351 const __be32 daddr, const __be16 dport, 352 const int dif) 353 { 354 u16 hnum = ntohs(dport); 355 struct sock *sk = __inet_lookup_established(net, hashinfo, 356 saddr, sport, daddr, hnum, dif); 357 358 return sk ? : __inet_lookup_listener(net, hashinfo, daddr, hnum, dif); 359 } 360 361 static inline struct sock *inet_lookup(struct net *net, 362 struct inet_hashinfo *hashinfo, 363 const __be32 saddr, const __be16 sport, 364 const __be32 daddr, const __be16 dport, 365 const int dif) 366 { 367 struct sock *sk; 368 369 local_bh_disable(); 370 sk = __inet_lookup(net, hashinfo, saddr, sport, daddr, dport, dif); 371 local_bh_enable(); 372 373 return sk; 374 } 375 376 static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 377 struct sk_buff *skb, 378 const __be16 sport, 379 const __be16 dport) 380 { 381 struct sock *sk; 382 const struct iphdr *iph = ip_hdr(skb); 383 384 if (unlikely(sk = skb_steal_sock(skb))) 385 return sk; 386 else 387 return __inet_lookup(dev_net(skb->dst->dev), hashinfo, 388 iph->saddr, sport, 389 iph->daddr, dport, inet_iif(skb)); 390 } 391 392 extern int __inet_hash_connect(struct inet_timewait_death_row *death_row, 393 struct sock *sk, u32 port_offset, 394 int (*check_established)(struct inet_timewait_death_row *, 395 struct sock *, __u16, struct inet_timewait_sock **), 396 void (*hash)(struct sock *sk)); 397 extern int inet_hash_connect(struct inet_timewait_death_row *death_row, 398 struct sock *sk); 399 #endif /* _INET_HASHTABLES_H */ 400