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/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 */
  43struct inet_ehash_bucket {
  44        struct hlist_nulls_head chain;
  45        struct hlist_nulls_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 */
  79struct inet_bind_bucket {
  80#ifdef CONFIG_NET_NS
  81        struct net              *ib_net;
  82#endif
  83        unsigned short          port;
  84        signed short            fastreuse;
  85        int                     num_owners;
  86        struct hlist_node       node;
  87        struct hlist_head       owners;
  88};
  89
  90static inline struct net *ib_net(struct inet_bind_bucket *ib)
  91{
  92        return read_pnet(&ib->ib_net);
  93}
  94
  95#define inet_bind_bucket_for_each(tb, pos, head) \
  96        hlist_for_each_entry(tb, pos, head, node)
  97
  98struct inet_bind_hashbucket {
  99        spinlock_t              lock;
 100        struct hlist_head       chain;
 101};
 102
 103/*
 104 * Sockets can be hashed in established or listening table
 105 * We must use different 'nulls' end-of-chain value for listening
 106 * hash table, or we might find a socket that was closed and
 107 * reallocated/inserted into established hash table
 108 */
 109#define LISTENING_NULLS_BASE (1U << 29)
 110struct inet_listen_hashbucket {
 111        spinlock_t              lock;
 112        struct hlist_nulls_head head;
 113};
 114
 115/* This is for listening sockets, thus all sockets which possess wildcards. */
 116#define INET_LHTABLE_SIZE       32      /* Yes, really, this is all you need. */
 117
 118struct inet_hashinfo {
 119        /* This is for sockets with full identity only.  Sockets here will
 120         * always be without wildcards and will have the following invariant:
 121         *
 122         *          TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
 123         *
 124         * TIME_WAIT sockets use a separate chain (twchain).
 125         */
 126        struct inet_ehash_bucket        *ehash;
 127        spinlock_t                      *ehash_locks;
 128        unsigned int                    ehash_mask;
 129        unsigned int                    ehash_locks_mask;
 130
 131        /* Ok, let's try this, I give up, we do need a local binding
 132         * TCP hash as well as the others for fast bind/connect.
 133         */
 134        struct inet_bind_hashbucket     *bhash;
 135
 136        unsigned int                    bhash_size;
 137        /* 4 bytes hole on 64 bit */
 138
 139        struct kmem_cache               *bind_bucket_cachep;
 140
 141        /* All the above members are written once at bootup and
 142         * never written again _or_ are predominantly read-access.
 143         *
 144         * Now align to a new cache line as all the following members
 145         * might be often dirty.
 146         */
 147        /* All sockets in TCP_LISTEN state will be in here.  This is the only
 148         * table where wildcard'd TCP sockets can exist.  Hash function here
 149         * is just local port number.
 150         */
 151        struct inet_listen_hashbucket   listening_hash[INET_LHTABLE_SIZE]
 152                                        ____cacheline_aligned_in_smp;
 153
 154        atomic_t                        bsockets;
 155};
 156
 157static inline struct inet_ehash_bucket *inet_ehash_bucket(
 158        struct inet_hashinfo *hashinfo,
 159        unsigned int hash)
 160{
 161        return &hashinfo->ehash[hash & hashinfo->ehash_mask];
 162}
 163
 164static inline spinlock_t *inet_ehash_lockp(
 165        struct inet_hashinfo *hashinfo,
 166        unsigned int hash)
 167{
 168        return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
 169}
 170
 171static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
 172{
 173        unsigned int i, size = 256;
 174#if defined(CONFIG_PROVE_LOCKING)
 175        unsigned int nr_pcpus = 2;
 176#else
 177        unsigned int nr_pcpus = num_possible_cpus();
 178#endif
 179        if (nr_pcpus >= 4)
 180                size = 512;
 181        if (nr_pcpus >= 8)
 182                size = 1024;
 183        if (nr_pcpus >= 16)
 184                size = 2048;
 185        if (nr_pcpus >= 32)
 186                size = 4096;
 187        if (sizeof(spinlock_t) != 0) {
 188#ifdef CONFIG_NUMA
 189                if (size * sizeof(spinlock_t) > PAGE_SIZE)
 190                        hashinfo->ehash_locks = vmalloc(size * sizeof(spinlock_t));
 191                else
 192#endif
 193                hashinfo->ehash_locks = kmalloc(size * sizeof(spinlock_t),
 194                                                GFP_KERNEL);
 195                if (!hashinfo->ehash_locks)
 196                        return ENOMEM;
 197                for (i = 0; i < size; i++)
 198                        spin_lock_init(&hashinfo->ehash_locks[i]);
 199        }
 200        hashinfo->ehash_locks_mask = size - 1;
 201        return 0;
 202}
 203
 204static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
 205{
 206        if (hashinfo->ehash_locks) {
 207#ifdef CONFIG_NUMA
 208                unsigned int size = (hashinfo->ehash_locks_mask + 1) *
 209                                                        sizeof(spinlock_t);
 210                if (size > PAGE_SIZE)
 211                        vfree(hashinfo->ehash_locks);
 212                else
 213#endif
 214                kfree(hashinfo->ehash_locks);
 215                hashinfo->ehash_locks = NULL;
 216        }
 217}
 218
 219extern struct inet_bind_bucket *
 220                    inet_bind_bucket_create(struct kmem_cache *cachep,
 221                                            struct net *net,
 222                                            struct inet_bind_hashbucket *head,
 223                                            const unsigned short snum);
 224extern void inet_bind_bucket_destroy(struct kmem_cache *cachep,
 225                                     struct inet_bind_bucket *tb);
 226
 227static inline int inet_bhashfn(struct net *net,
 228                const __u16 lport, const int bhash_size)
 229{
 230        return (lport + net_hash_mix(net)) & (bhash_size - 1);
 231}
 232
 233extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
 234                           const unsigned short snum);
 235
 236/* These can have wildcards, don't try too hard. */
 237static inline int inet_lhashfn(struct net *net, const unsigned short num)
 238{
 239        return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
 240}
 241
 242static inline int inet_sk_listen_hashfn(const struct sock *sk)
 243{
 244        return inet_lhashfn(sock_net(sk), inet_sk(sk)->inet_num);
 245}
 246
 247/* Caller must disable local BH processing. */
 248extern void __inet_inherit_port(struct sock *sk, struct sock *child);
 249
 250extern void inet_put_port(struct sock *sk);
 251
 252void inet_hashinfo_init(struct inet_hashinfo *h);
 253
 254extern int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw);
 255extern void inet_hash(struct sock *sk);
 256extern void inet_unhash(struct sock *sk);
 257
 258extern struct sock *__inet_lookup_listener(struct net *net,
 259                                           struct inet_hashinfo *hashinfo,
 260                                           const __be32 daddr,
 261                                           const unsigned short hnum,
 262                                           const int dif);
 263
 264static inline struct sock *inet_lookup_listener(struct net *net,
 265                struct inet_hashinfo *hashinfo,
 266                __be32 daddr, __be16 dport, int dif)
 267{
 268        return __inet_lookup_listener(net, hashinfo, daddr, ntohs(dport), dif);
 269}
 270
 271/* Socket demux engine toys. */
 272/* What happens here is ugly; there's a pair of adjacent fields in
 273   struct inet_sock; __be16 dport followed by __u16 num.  We want to
 274   search by pair, so we combine the keys into a single 32bit value
 275   and compare with 32bit value read from &...->dport.  Let's at least
 276   make sure that it's not mixed with anything else...
 277   On 64bit targets we combine comparisons with pair of adjacent __be32
 278   fields in the same way.
 279*/
 280typedef __u32 __bitwise __portpair;
 281#ifdef __BIG_ENDIAN
 282#define INET_COMBINED_PORTS(__sport, __dport) \
 283        ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
 284#else /* __LITTLE_ENDIAN */
 285#define INET_COMBINED_PORTS(__sport, __dport) \
 286        ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
 287#endif
 288
 289#if (BITS_PER_LONG == 64)
 290typedef __u64 __bitwise __addrpair;
 291#ifdef __BIG_ENDIAN
 292#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 293        const __addrpair __name = (__force __addrpair) ( \
 294                                   (((__force __u64)(__be32)(__saddr)) << 32) | \
 295                                   ((__force __u64)(__be32)(__daddr)));
 296#else /* __LITTLE_ENDIAN */
 297#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 298        const __addrpair __name = (__force __addrpair) ( \
 299                                   (((__force __u64)(__be32)(__daddr)) << 32) | \
 300                                   ((__force __u64)(__be32)(__saddr)));
 301#endif /* __BIG_ENDIAN */
 302#define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
 303        (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) &&    \
 304         ((*((__addrpair *)&(inet_sk(__sk)->inet_daddr))) == (__cookie))  &&    \
 305         ((*((__portpair *)&(inet_sk(__sk)->inet_dport))) == (__ports))   &&    \
 306         (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
 307#define INET_TW_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
 308        (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) &&    \
 309         ((*((__addrpair *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) &&     \
 310         ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) &&      \
 311         (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
 312#else /* 32-bit arch */
 313#define INET_ADDR_COOKIE(__name, __saddr, __daddr)
 314#define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)     \
 315        (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net))       &&      \
 316         (inet_sk(__sk)->inet_daddr     == (__saddr))           &&      \
 317         (inet_sk(__sk)->inet_rcv_saddr == (__daddr))           &&      \
 318         ((*((__portpair *)&(inet_sk(__sk)->inet_dport))) == (__ports)) &&      \
 319         (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
 320#define INET_TW_MATCH(__sk, __net, __hash,__cookie, __saddr, __daddr, __ports, __dif)   \
 321        (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net))       &&      \
 322         (inet_twsk(__sk)->tw_daddr     == (__saddr))           &&      \
 323         (inet_twsk(__sk)->tw_rcv_saddr == (__daddr))           &&      \
 324         ((*((__portpair *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) &&      \
 325         (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
 326#endif /* 64-bit arch */
 327
 328/*
 329 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
 330 * not check it for lookups anymore, thanks Alexey. -DaveM
 331 *
 332 * Local BH must be disabled here.
 333 */
 334extern struct sock * __inet_lookup_established(struct net *net,
 335                struct inet_hashinfo *hashinfo,
 336                const __be32 saddr, const __be16 sport,
 337                const __be32 daddr, const u16 hnum, const int dif);
 338
 339static inline struct sock *
 340        inet_lookup_established(struct net *net, struct inet_hashinfo *hashinfo,
 341                                const __be32 saddr, const __be16 sport,
 342                                const __be32 daddr, const __be16 dport,
 343                                const int dif)
 344{
 345        return __inet_lookup_established(net, hashinfo, saddr, sport, daddr,
 346                                         ntohs(dport), dif);
 347}
 348
 349static inline struct sock *__inet_lookup(struct net *net,
 350                                         struct inet_hashinfo *hashinfo,
 351                                         const __be32 saddr, const __be16 sport,
 352                                         const __be32 daddr, const __be16 dport,
 353                                         const int dif)
 354{
 355        u16 hnum = ntohs(dport);
 356        struct sock *sk = __inet_lookup_established(net, hashinfo,
 357                                saddr, sport, daddr, hnum, dif);
 358
 359        return sk ? : __inet_lookup_listener(net, hashinfo, daddr, hnum, dif);
 360}
 361
 362static inline struct sock *inet_lookup(struct net *net,
 363                                       struct inet_hashinfo *hashinfo,
 364                                       const __be32 saddr, const __be16 sport,
 365                                       const __be32 daddr, const __be16 dport,
 366                                       const int dif)
 367{
 368        struct sock *sk;
 369
 370        local_bh_disable();
 371        sk = __inet_lookup(net, hashinfo, saddr, sport, daddr, dport, dif);
 372        local_bh_enable();
 373
 374        return sk;
 375}
 376
 377static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
 378                                             struct sk_buff *skb,
 379                                             const __be16 sport,
 380                                             const __be16 dport)
 381{
 382        struct sock *sk;
 383        const struct iphdr *iph = ip_hdr(skb);
 384
 385        if (unlikely(sk = skb_steal_sock(skb)))
 386                return sk;
 387        else
 388                return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo,
 389                                     iph->saddr, sport,
 390                                     iph->daddr, dport, inet_iif(skb));
 391}
 392
 393extern int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 394                struct sock *sk,
 395                u32 port_offset,
 396                int (*check_established)(struct inet_timewait_death_row *,
 397                        struct sock *, __u16, struct inet_timewait_sock **),
 398                int (*hash)(struct sock *sk, struct inet_timewait_sock *twp));
 399
 400extern int inet_hash_connect(struct inet_timewait_death_row *death_row,
 401                             struct sock *sk);
 402#endif /* _INET_HASHTABLES_H */
 403
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