linux/net/ipv6/inet6_hashtables.c
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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 *              Generic INET6 transport hashtables
   7 *
   8 * Authors:     Lotsa people, from code originally in tcp, generalised here
   9 *              by Arnaldo Carvalho de Melo <acme@mandriva.com>
  10 *
  11 *      This program is free software; you can redistribute it and/or
  12 *      modify it under the terms of the GNU General Public License
  13 *      as published by the Free Software Foundation; either version
  14 *      2 of the License, or (at your option) any later version.
  15 */
  16
  17#include <linux/module.h>
  18#include <linux/random.h>
  19
  20#include <net/inet_connection_sock.h>
  21#include <net/inet_hashtables.h>
  22#include <net/inet6_hashtables.h>
  23#include <net/secure_seq.h>
  24#include <net/ip.h>
  25
  26int __inet6_hash(struct sock *sk, struct inet_timewait_sock *tw)
  27{
  28        struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
  29        int twrefcnt = 0;
  30
  31        WARN_ON(!sk_unhashed(sk));
  32
  33        if (sk->sk_state == TCP_LISTEN) {
  34                struct inet_listen_hashbucket *ilb;
  35
  36                ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
  37                spin_lock(&ilb->lock);
  38                __sk_nulls_add_node_rcu(sk, &ilb->head);
  39                spin_unlock(&ilb->lock);
  40        } else {
  41                unsigned int hash;
  42                struct hlist_nulls_head *list;
  43                spinlock_t *lock;
  44
  45                sk->sk_hash = hash = inet6_sk_ehashfn(sk);
  46                list = &inet_ehash_bucket(hashinfo, hash)->chain;
  47                lock = inet_ehash_lockp(hashinfo, hash);
  48                spin_lock(lock);
  49                __sk_nulls_add_node_rcu(sk, list);
  50                if (tw) {
  51                        WARN_ON(sk->sk_hash != tw->tw_hash);
  52                        twrefcnt = inet_twsk_unhash(tw);
  53                }
  54                spin_unlock(lock);
  55        }
  56
  57        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
  58        return twrefcnt;
  59}
  60EXPORT_SYMBOL(__inet6_hash);
  61
  62/*
  63 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
  64 * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
  65 *
  66 * The sockhash lock must be held as a reader here.
  67 */
  68struct sock *__inet6_lookup_established(struct net *net,
  69                                        struct inet_hashinfo *hashinfo,
  70                                           const struct in6_addr *saddr,
  71                                           const __be16 sport,
  72                                           const struct in6_addr *daddr,
  73                                           const u16 hnum,
  74                                           const int dif)
  75{
  76        struct sock *sk;
  77        const struct hlist_nulls_node *node;
  78        const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
  79        /* Optimize here for direct hit, only listening connections can
  80         * have wildcards anyways.
  81         */
  82        unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
  83        unsigned int slot = hash & hashinfo->ehash_mask;
  84        struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
  85
  86
  87        rcu_read_lock();
  88begin:
  89        sk_nulls_for_each_rcu(sk, node, &head->chain) {
  90                /* For IPV6 do the cheaper port and family tests first. */
  91                if (INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
  92                        if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
  93                                goto begintw;
  94                        if (!INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
  95                                sock_put(sk);
  96                                goto begin;
  97                        }
  98                goto out;
  99                }
 100        }
 101        if (get_nulls_value(node) != slot)
 102                goto begin;
 103
 104begintw:
 105        /* Must check for a TIME_WAIT'er before going to listener hash. */
 106        sk_nulls_for_each_rcu(sk, node, &head->twchain) {
 107                if (INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
 108                        if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
 109                                sk = NULL;
 110                                goto out;
 111                        }
 112                        if (!INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
 113                                sock_put(sk);
 114                                goto begintw;
 115                        }
 116                        goto out;
 117                }
 118        }
 119        if (get_nulls_value(node) != slot)
 120                goto begintw;
 121        sk = NULL;
 122out:
 123        rcu_read_unlock();
 124        return sk;
 125}
 126EXPORT_SYMBOL(__inet6_lookup_established);
 127
 128static inline int compute_score(struct sock *sk, struct net *net,
 129                                const unsigned short hnum,
 130                                const struct in6_addr *daddr,
 131                                const int dif)
 132{
 133        int score = -1;
 134
 135        if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 136            sk->sk_family == PF_INET6) {
 137                const struct ipv6_pinfo *np = inet6_sk(sk);
 138
 139                score = 1;
 140                if (!ipv6_addr_any(&np->rcv_saddr)) {
 141                        if (!ipv6_addr_equal(&np->rcv_saddr, daddr))
 142                                return -1;
 143                        score++;
 144                }
 145                if (sk->sk_bound_dev_if) {
 146                        if (sk->sk_bound_dev_if != dif)
 147                                return -1;
 148                        score++;
 149                }
 150        }
 151        return score;
 152}
 153
 154struct sock *inet6_lookup_listener(struct net *net,
 155                struct inet_hashinfo *hashinfo, const struct in6_addr *daddr,
 156                const unsigned short hnum, const int dif)
 157{
 158        struct sock *sk;
 159        const struct hlist_nulls_node *node;
 160        struct sock *result;
 161        int score, hiscore;
 162        unsigned int hash = inet_lhashfn(net, hnum);
 163        struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
 164
 165        rcu_read_lock();
 166begin:
 167        result = NULL;
 168        hiscore = -1;
 169        sk_nulls_for_each(sk, node, &ilb->head) {
 170                score = compute_score(sk, net, hnum, daddr, dif);
 171                if (score > hiscore) {
 172                        hiscore = score;
 173                        result = sk;
 174                }
 175        }
 176        /*
 177         * if the nulls value we got at the end of this lookup is
 178         * not the expected one, we must restart lookup.
 179         * We probably met an item that was moved to another chain.
 180         */
 181        if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
 182                goto begin;
 183        if (result) {
 184                if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
 185                        result = NULL;
 186                else if (unlikely(compute_score(result, net, hnum, daddr,
 187                                  dif) < hiscore)) {
 188                        sock_put(result);
 189                        goto begin;
 190                }
 191        }
 192        rcu_read_unlock();
 193        return result;
 194}
 195
 196EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 197
 198struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
 199                          const struct in6_addr *saddr, const __be16 sport,
 200                          const struct in6_addr *daddr, const __be16 dport,
 201                          const int dif)
 202{
 203        struct sock *sk;
 204
 205        local_bh_disable();
 206        sk = __inet6_lookup(net, hashinfo, saddr, sport, daddr, ntohs(dport), dif);
 207        local_bh_enable();
 208
 209        return sk;
 210}
 211
 212EXPORT_SYMBOL_GPL(inet6_lookup);
 213
 214static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 215                                     struct sock *sk, const __u16 lport,
 216                                     struct inet_timewait_sock **twp)
 217{
 218        struct inet_hashinfo *hinfo = death_row->hashinfo;
 219        struct inet_sock *inet = inet_sk(sk);
 220        const struct ipv6_pinfo *np = inet6_sk(sk);
 221        const struct in6_addr *daddr = &np->rcv_saddr;
 222        const struct in6_addr *saddr = &np->daddr;
 223        const int dif = sk->sk_bound_dev_if;
 224        const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 225        struct net *net = sock_net(sk);
 226        const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
 227                                                inet->inet_dport);
 228        struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 229        spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 230        struct sock *sk2;
 231        const struct hlist_nulls_node *node;
 232        struct inet_timewait_sock *tw;
 233        int twrefcnt = 0;
 234
 235        spin_lock(lock);
 236
 237        /* Check TIME-WAIT sockets first. */
 238        sk_nulls_for_each(sk2, node, &head->twchain) {
 239                tw = inet_twsk(sk2);
 240
 241                if (INET6_TW_MATCH(sk2, net, hash, saddr, daddr, ports, dif)) {
 242                        if (twsk_unique(sk, sk2, twp))
 243                                goto unique;
 244                        else
 245                                goto not_unique;
 246                }
 247        }
 248        tw = NULL;
 249
 250        /* And established part... */
 251        sk_nulls_for_each(sk2, node, &head->chain) {
 252                if (INET6_MATCH(sk2, net, hash, saddr, daddr, ports, dif))
 253                        goto not_unique;
 254        }
 255
 256unique:
 257        /* Must record num and sport now. Otherwise we will see
 258         * in hash table socket with a funny identity. */
 259        inet->inet_num = lport;
 260        inet->inet_sport = htons(lport);
 261        sk->sk_hash = hash;
 262        WARN_ON(!sk_unhashed(sk));
 263        __sk_nulls_add_node_rcu(sk, &head->chain);
 264        if (tw) {
 265                twrefcnt = inet_twsk_unhash(tw);
 266                NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
 267        }
 268        spin_unlock(lock);
 269        if (twrefcnt)
 270                inet_twsk_put(tw);
 271        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 272
 273        if (twp) {
 274                *twp = tw;
 275        } else if (tw) {
 276                /* Silly. Should hash-dance instead... */
 277                inet_twsk_deschedule(tw, death_row);
 278
 279                inet_twsk_put(tw);
 280        }
 281        return 0;
 282
 283not_unique:
 284        spin_unlock(lock);
 285        return -EADDRNOTAVAIL;
 286}
 287
 288static inline u32 inet6_sk_port_offset(const struct sock *sk)
 289{
 290        const struct inet_sock *inet = inet_sk(sk);
 291        const struct ipv6_pinfo *np = inet6_sk(sk);
 292        return secure_ipv6_port_ephemeral(np->rcv_saddr.s6_addr32,
 293                                          np->daddr.s6_addr32,
 294                                          inet->inet_dport);
 295}
 296
 297int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 298                       struct sock *sk)
 299{
 300        return __inet_hash_connect(death_row, sk, inet6_sk_port_offset(sk),
 301                        __inet6_check_established, __inet6_hash);
 302}
 303
 304EXPORT_SYMBOL_GPL(inet6_hash_connect);
 305
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