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/secure_seq.h>
  24 #include <net/ip.h>
  25
  26 int __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 }
  60 EXPORT_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  */
  68 struct 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();
  88 begin:
  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
 104 begintw:
 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                                 inet_twsk_put(inet_twsk(sk));
 114                                 goto begintw;
 115                         }
 116                         goto out;
 117                 }
 118         }
 119         if (get_nulls_value(node) != slot)
 120                 goto begintw;
 121         sk = NULL;
 122 out:
 123         rcu_read_unlock();
 124         return sk;
 125 }
 126 EXPORT_SYMBOL(__inet6_lookup_established);
 127
 128 static 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
 154 struct 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();
 166 begin:
 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
 196 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 197
 198 struct 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
 212 EXPORT_SYMBOL_GPL(inet6_lookup);
 213
 214 static 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
 256 unique:
 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
 283 not_unique:
 284         spin_unlock(lock);
 285         return -EADDRNOTAVAIL;
 286 }
 287
 288 static 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
 297 int 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
 304 EXPORT_SYMBOL_GPL(inet6_hash_connect);