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