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/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 */