net/ipv6/inet6_hashtables.c

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