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