include/net/inet_hashtables.h

   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
  33 #include <asm/atomic.h>
  34 #include <asm/byteorder.h>
  35
  36 /* This is for all connections with a full identity, no wildcards.
  37  * One chain is dedicated to TIME_WAIT sockets.
  38  * I'll experiment with dynamic table growth later.
  39  */
  40 struct inet_ehash_bucket {
  41         struct hlist_head chain;
  42         struct hlist_head twchain;
  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         struct net              *ib_net;
  78         unsigned short          port;
  79         signed short            fastreuse;
  80         struct hlist_node       node;
  81         struct hlist_head       owners;
  82 };
  83
  84 #define inet_bind_bucket_for_each(tb, node, head) \
  85         hlist_for_each_entry(tb, node, head, node)
  86
  87 struct inet_bind_hashbucket {
  88         spinlock_t              lock;
  89         struct hlist_head       chain;
  90 };
  91
  92 /* This is for listening sockets, thus all sockets which possess wildcards. */
  93 #define INET_LHTABLE_SIZE       32      /* Yes, really, this is all you need. */
  94
  95 struct inet_hashinfo {
  96         /* This is for sockets with full identity only.  Sockets here will
  97          * always be without wildcards and will have the following invariant:
  98          *
  99          *          TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
 100          *
 101          * TIME_WAIT sockets use a separate chain (twchain).
 102          */
 103         struct inet_ehash_bucket        *ehash;
 104         rwlock_t                        *ehash_locks;
 105         unsigned int                    ehash_size;
 106         unsigned int                    ehash_locks_mask;
 107
 108         /* Ok, let's try this, I give up, we do need a local binding
 109          * TCP hash as well as the others for fast bind/connect.
 110          */
 111         struct inet_bind_hashbucket     *bhash;
 112
 113         unsigned int                    bhash_size;
 114         /* Note : 4 bytes padding on 64 bit arches */
 115
 116         /* All sockets in TCP_LISTEN state will be in here.  This is the only
 117          * table where wildcard'd TCP sockets can exist.  Hash function here
 118          * is just local port number.
 119          */
 120         struct hlist_head               listening_hash[INET_LHTABLE_SIZE];
 121
 122         /* All the above members are written once at bootup and
 123          * never written again _or_ are predominantly read-access.
 124          *
 125          * Now align to a new cache line as all the following members
 126          * are often dirty.
 127          */
 128         rwlock_t                        lhash_lock ____cacheline_aligned;
 129         atomic_t                        lhash_users;
 130         wait_queue_head_t               lhash_wait;
 131         struct kmem_cache                       *bind_bucket_cachep;
 132 };
 133
 134 static inline struct inet_ehash_bucket *inet_ehash_bucket(
 135         struct inet_hashinfo *hashinfo,
 136         unsigned int hash)
 137 {
 138         return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)];
 139 }
 140
 141 static inline rwlock_t *inet_ehash_lockp(
 142         struct inet_hashinfo *hashinfo,
 143         unsigned int hash)
 144 {
 145         return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
 146 }
 147
 148 static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
 149 {
 150         unsigned int i, size = 256;
 151 #if defined(CONFIG_PROVE_LOCKING)
 152         unsigned int nr_pcpus = 2;
 153 #else
 154         unsigned int nr_pcpus = num_possible_cpus();
 155 #endif
 156         if (nr_pcpus >= 4)
 157                 size = 512;
 158         if (nr_pcpus >= 8)
 159                 size = 1024;
 160         if (nr_pcpus >= 16)
 161                 size = 2048;
 162         if (nr_pcpus >= 32)
 163                 size = 4096;
 164         if (sizeof(rwlock_t) != 0) {
 165 #ifdef CONFIG_NUMA
 166                 if (size * sizeof(rwlock_t) > PAGE_SIZE)
 167                         hashinfo->ehash_locks = vmalloc(size * sizeof(rwlock_t));
 168                 else
 169 #endif
 170                 hashinfo->ehash_locks = kmalloc(size * sizeof(rwlock_t),
 171                                                 GFP_KERNEL);
 172                 if (!hashinfo->ehash_locks)
 173                         return ENOMEM;
 174                 for (i = 0; i < size; i++)
 175                         rwlock_init(&hashinfo->ehash_locks[i]);
 176         }
 177         hashinfo->ehash_locks_mask = size - 1;
 178         return 0;
 179 }
 180
 181 static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
 182 {
 183         if (hashinfo->ehash_locks) {
 184 #ifdef CONFIG_NUMA
 185                 unsigned int size = (hashinfo->ehash_locks_mask + 1) *
 186                                                         sizeof(rwlock_t);
 187                 if (size > PAGE_SIZE)
 188                         vfree(hashinfo->ehash_locks);
 189                 else
 190 #endif
 191                 kfree(hashinfo->ehash_locks);
 192                 hashinfo->ehash_locks = NULL;
 193         }
 194 }
 195
 196 extern struct inet_bind_bucket *
 197                     inet_bind_bucket_create(struct kmem_cache *cachep,
 198                                             struct net *net,
 199                                             struct inet_bind_hashbucket *head,
 200                                             const unsigned short snum);
 201 extern void inet_bind_bucket_destroy(struct kmem_cache *cachep,
 202                                      struct inet_bind_bucket *tb);
 203
 204 static inline int inet_bhashfn(const __u16 lport, const int bhash_size)
 205 {
 206         return lport & (bhash_size - 1);
 207 }
 208
 209 extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
 210                            const unsigned short snum);
 211
 212 /* These can have wildcards, don't try too hard. */
 213 static inline int inet_lhashfn(const unsigned short num)
 214 {
 215         return num & (INET_LHTABLE_SIZE - 1);
 216 }
 217
 218 static inline int inet_sk_listen_hashfn(const struct sock *sk)
 219 {
 220         return inet_lhashfn(inet_sk(sk)->num);
 221 }
 222
 223 /* Caller must disable local BH processing. */
 224 static inline void __inet_inherit_port(struct inet_hashinfo *table,
 225                                        struct sock *sk, struct sock *child)
 226 {
 227         const int bhash = inet_bhashfn(inet_sk(child)->num, table->bhash_size);
 228         struct inet_bind_hashbucket *head = &table->bhash[bhash];
 229         struct inet_bind_bucket *tb;
 230
 231         spin_lock(&head->lock);
 232         tb = inet_csk(sk)->icsk_bind_hash;
 233         sk_add_bind_node(child, &tb->owners);
 234         inet_csk(child)->icsk_bind_hash = tb;
 235         spin_unlock(&head->lock);
 236 }
 237
 238 static inline void inet_inherit_port(struct inet_hashinfo *table,
 239                                      struct sock *sk, struct sock *child)
 240 {
 241         local_bh_disable();
 242         __inet_inherit_port(table, sk, child);
 243         local_bh_enable();
 244 }
 245
 246 extern void inet_put_port(struct inet_hashinfo *table, struct sock *sk);
 247
 248 extern void inet_listen_wlock(struct inet_hashinfo *hashinfo);
 249
 250 /*
 251  * - We may sleep inside this lock.
 252  * - If sleeping is not required (or called from BH),
 253  *   use plain read_(un)lock(&inet_hashinfo.lhash_lock).
 254  */
 255 static inline void inet_listen_lock(struct inet_hashinfo *hashinfo)
 256 {
 257         /* read_lock synchronizes to candidates to writers */
 258         read_lock(&hashinfo->lhash_lock);
 259         atomic_inc(&hashinfo->lhash_users);
 260         read_unlock(&hashinfo->lhash_lock);
 261 }
 262
 263 static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo)
 264 {
 265         if (atomic_dec_and_test(&hashinfo->lhash_users))
 266                 wake_up(&hashinfo->lhash_wait);
 267 }
 268
 269 extern void __inet_hash(struct inet_hashinfo *hashinfo, struct sock *sk);
 270 extern void __inet_hash_nolisten(struct inet_hashinfo *hinfo, struct sock *sk);
 271
 272 static inline void inet_hash(struct inet_hashinfo *hashinfo, struct sock *sk)
 273 {
 274         if (sk->sk_state != TCP_CLOSE) {
 275                 local_bh_disable();
 276                 __inet_hash(hashinfo, sk);
 277                 local_bh_enable();
 278         }
 279 }
 280
 281 static inline void inet_unhash(struct inet_hashinfo *hashinfo, struct sock *sk)
 282 {
 283         rwlock_t *lock;
 284
 285         if (sk_unhashed(sk))
 286                 goto out;
 287
 288         if (sk->sk_state == TCP_LISTEN) {
 289                 local_bh_disable();
 290                 inet_listen_wlock(hashinfo);
 291                 lock = &hashinfo->lhash_lock;
 292         } else {
 293                 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 294                 write_lock_bh(lock);
 295         }
 296
 297         if (__sk_del_node_init(sk))
 298                 sock_prot_inuse_add(sk->sk_prot, -1);
 299         write_unlock_bh(lock);
 300 out:
 301         if (sk->sk_state == TCP_LISTEN)
 302                 wake_up(&hashinfo->lhash_wait);
 303 }
 304
 305 extern struct sock *__inet_lookup_listener(struct inet_hashinfo *hashinfo,
 306                                            const __be32 daddr,
 307                                            const unsigned short hnum,
 308                                            const int dif);
 309
 310 static inline struct sock *inet_lookup_listener(struct inet_hashinfo *hashinfo,
 311                                                 __be32 daddr, __be16 dport, int dif)
 312 {
 313         return __inet_lookup_listener(hashinfo, daddr, ntohs(dport), dif);
 314 }
 315
 316 /* Socket demux engine toys. */
 317 /* What happens here is ugly; there's a pair of adjacent fields in
 318    struct inet_sock; __be16 dport followed by __u16 num.  We want to
 319    search by pair, so we combine the keys into a single 32bit value
 320    and compare with 32bit value read from &...->dport.  Let's at least
 321    make sure that it's not mixed with anything else...
 322    On 64bit targets we combine comparisons with pair of adjacent __be32
 323    fields in the same way.
 324 */
 325 typedef __u32 __bitwise __portpair;
 326 #ifdef __BIG_ENDIAN
 327 #define INET_COMBINED_PORTS(__sport, __dport) \
 328         ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
 329 #else /* __LITTLE_ENDIAN */
 330 #define INET_COMBINED_PORTS(__sport, __dport) \
 331         ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
 332 #endif
 333
 334 #if (BITS_PER_LONG == 64)
 335 typedef __u64 __bitwise __addrpair;
 336 #ifdef __BIG_ENDIAN
 337 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 338         const __addrpair __name = (__force __addrpair) ( \
 339                                    (((__force __u64)(__be32)(__saddr)) << 32) | \
 340                                    ((__force __u64)(__be32)(__daddr)));
 341 #else /* __LITTLE_ENDIAN */
 342 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 343         const __addrpair __name = (__force __addrpair) ( \
 344                                    (((__force __u64)(__be32)(__daddr)) << 32) | \
 345                                    ((__force __u64)(__be32)(__saddr)));
 346 #endif /* __BIG_ENDIAN */
 347 #define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
 348         (((__sk)->sk_hash == (__hash))                          &&      \
 349          ((*((__addrpair *)&(inet_sk(__sk)->daddr))) == (__cookie))     &&      \
 350          ((*((__portpair *)&(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          ((*((__addrpair *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) &&     \
 355          ((*((__portpair *)&(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          ((*((__portpair *)&(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          ((*((__portpair *)&(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 extern struct sock * __inet_lookup_established(struct inet_hashinfo *hashinfo,
 380                 const __be32 saddr, const __be16 sport,
 381                 const __be32 daddr, const u16 hnum, const int dif);
 382
 383 static inline struct sock *
 384         inet_lookup_established(struct inet_hashinfo *hashinfo,
 385                                 const __be32 saddr, const __be16 sport,
 386                                 const __be32 daddr, const __be16 dport,
 387                                 const int dif)
 388 {
 389         return __inet_lookup_established(hashinfo, saddr, sport, daddr,
 390                                          ntohs(dport), dif);
 391 }
 392
 393 static inline struct sock *__inet_lookup(struct inet_hashinfo *hashinfo,
 394                                          const __be32 saddr, const __be16 sport,
 395                                          const __be32 daddr, const __be16 dport,
 396                                          const int dif)
 397 {
 398         u16 hnum = ntohs(dport);
 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 __be32 saddr, const __be16 sport,
 406                                        const __be32 daddr, const __be16 dport,
 407                                        const int dif)
 408 {
 409         struct sock *sk;
 410
 411         local_bh_disable();
 412         sk = __inet_lookup(hashinfo, saddr, sport, daddr, 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                 int (*check_established)(struct inet_timewait_death_row *,
 421                         struct sock *, __u16, struct inet_timewait_sock **),
 422                 void (*hash)(struct inet_hashinfo *, struct sock *));
 423 extern int inet_hash_connect(struct inet_timewait_death_row *death_row,
 424                              struct sock *sk);
 425 #endif /* _INET_HASHTABLES_H */