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                 if (sk->sk_hash != hash)
  91                         continue;
  92                 if (likely(INET6_MATCH(sk, net, saddr, daddr, ports, dif))) {
  93                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
  94                                 goto begintw;
  95                         if (unlikely(!INET6_MATCH(sk, net, saddr, daddr,
  96                                                   ports, dif))) {
  97                                 sock_put(sk);
  98                                 goto begin;
  99                         }
 100                 goto out;
 101                 }
 102         }
 103         if (get_nulls_value(node) != slot)
 104                 goto begin;
 105
 106 begintw:
 107         /* Must check for a TIME_WAIT'er before going to listener hash. */
 108         sk_nulls_for_each_rcu(sk, node, &head->twchain) {
 109                 if (sk->sk_hash != hash)
 110                         continue;
 111                 if (likely(INET6_TW_MATCH(sk, net, saddr, daddr,
 112                                           ports, dif))) {
 113                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
 114                                 sk = NULL;
 115                                 goto out;
 116                         }
 117                         if (unlikely(!INET6_TW_MATCH(sk, net, saddr, daddr,
 118                                                      ports, dif))) {
 119                                 sock_put(sk);
 120                                 goto begintw;
 121                         }
 122                         goto out;
 123                 }
 124         }
 125         if (get_nulls_value(node) != slot)
 126                 goto begintw;
 127         sk = NULL;
 128 out:
 129         rcu_read_unlock();
 130         return sk;
 131 }
 132 EXPORT_SYMBOL(__inet6_lookup_established);
 133
 134 static inline int compute_score(struct sock *sk, struct net *net,
 135                                 const unsigned short hnum,
 136                                 const struct in6_addr *daddr,
 137                                 const int dif)
 138 {
 139         int score = -1;
 140
 141         if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 142             sk->sk_family == PF_INET6) {
 143                 const struct ipv6_pinfo *np = inet6_sk(sk);
 144
 145                 score = 1;
 146                 if (!ipv6_addr_any(&np->rcv_saddr)) {
 147                         if (!ipv6_addr_equal(&np->rcv_saddr, daddr))
 148                                 return -1;
 149                         score++;
 150                 }
 151                 if (sk->sk_bound_dev_if) {
 152                         if (sk->sk_bound_dev_if != dif)
 153                                 return -1;
 154                         score++;
 155                 }
 156         }
 157         return score;
 158 }
 159
 160 struct sock *inet6_lookup_listener(struct net *net,
 161                 struct inet_hashinfo *hashinfo, const struct in6_addr *saddr,
 162                 const __be16 sport, const struct in6_addr *daddr,
 163                 const unsigned short hnum, const int dif)
 164 {
 165         struct sock *sk;
 166         const struct hlist_nulls_node *node;
 167         struct sock *result;
 168         int score, hiscore, matches = 0, reuseport = 0;
 169         u32 phash = 0;
 170         unsigned int hash = inet_lhashfn(net, hnum);
 171         struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
 172
 173         rcu_read_lock();
 174 begin:
 175         result = NULL;
 176         hiscore = 0;
 177         sk_nulls_for_each(sk, node, &ilb->head) {
 178                 score = compute_score(sk, net, hnum, daddr, dif);
 179                 if (score > hiscore) {
 180                         hiscore = score;
 181                         result = sk;
 182                         reuseport = sk->sk_reuseport;
 183                         if (reuseport) {
 184                                 phash = inet6_ehashfn(net, daddr, hnum,
 185                                                       saddr, sport);
 186                                 matches = 1;
 187                         }
 188                 } else if (score == hiscore && reuseport) {
 189                         matches++;
 190                         if (((u64)phash * matches) >> 32 == 0)
 191                                 result = sk;
 192                         phash = next_pseudo_random32(phash);
 193                 }
 194         }
 195         /*
 196          * if the nulls value we got at the end of this lookup is
 197          * not the expected one, we must restart lookup.
 198          * We probably met an item that was moved to another chain.
 199          */
 200         if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
 201                 goto begin;
 202         if (result) {
 203                 if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
 204                         result = NULL;
 205                 else if (unlikely(compute_score(result, net, hnum, daddr,
 206                                   dif) < hiscore)) {
 207                         sock_put(result);
 208                         goto begin;
 209                 }
 210         }
 211         rcu_read_unlock();
 212         return result;
 213 }
 214
 215 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 216
 217 struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
 218                           const struct in6_addr *saddr, const __be16 sport,
 219                           const struct in6_addr *daddr, const __be16 dport,
 220                           const int dif)
 221 {
 222         struct sock *sk;
 223
 224         local_bh_disable();
 225         sk = __inet6_lookup(net, hashinfo, saddr, sport, daddr, ntohs(dport), dif);
 226         local_bh_enable();
 227
 228         return sk;
 229 }
 230
 231 EXPORT_SYMBOL_GPL(inet6_lookup);
 232
 233 static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 234                                      struct sock *sk, const __u16 lport,
 235                                      struct inet_timewait_sock **twp)
 236 {
 237         struct inet_hashinfo *hinfo = death_row->hashinfo;
 238         struct inet_sock *inet = inet_sk(sk);
 239         const struct ipv6_pinfo *np = inet6_sk(sk);
 240         const struct in6_addr *daddr = &np->rcv_saddr;
 241         const struct in6_addr *saddr = &np->daddr;
 242         const int dif = sk->sk_bound_dev_if;
 243         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 244         struct net *net = sock_net(sk);
 245         const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
 246                                                 inet->inet_dport);
 247         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 248         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 249         struct sock *sk2;
 250         const struct hlist_nulls_node *node;
 251         struct inet_timewait_sock *tw;
 252         int twrefcnt = 0;
 253
 254         spin_lock(lock);
 255
 256         /* Check TIME-WAIT sockets first. */
 257         sk_nulls_for_each(sk2, node, &head->twchain) {
 258                 if (sk2->sk_hash != hash)
 259                         continue;
 260
 261                 if (likely(INET6_TW_MATCH(sk2, net, saddr, daddr,
 262                                           ports, dif))) {
 263                         tw = inet_twsk(sk2);
 264                         if (twsk_unique(sk, sk2, twp))
 265                                 goto unique;
 266                         else
 267                                 goto not_unique;
 268                 }
 269         }
 270         tw = NULL;
 271
 272         /* And established part... */
 273         sk_nulls_for_each(sk2, node, &head->chain) {
 274                 if (sk2->sk_hash != hash)
 275                         continue;
 276                 if (likely(INET6_MATCH(sk2, net, saddr, daddr, ports, dif)))
 277                         goto not_unique;
 278         }
 279
 280 unique:
 281         /* Must record num and sport now. Otherwise we will see
 282          * in hash table socket with a funny identity. */
 283         inet->inet_num = lport;
 284         inet->inet_sport = htons(lport);
 285         sk->sk_hash = hash;
 286         WARN_ON(!sk_unhashed(sk));
 287         __sk_nulls_add_node_rcu(sk, &head->chain);
 288         if (tw) {
 289                 twrefcnt = inet_twsk_unhash(tw);
 290                 NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
 291         }
 292         spin_unlock(lock);
 293         if (twrefcnt)
 294                 inet_twsk_put(tw);
 295         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 296
 297         if (twp) {
 298                 *twp = tw;
 299         } else if (tw) {
 300                 /* Silly. Should hash-dance instead... */
 301                 inet_twsk_deschedule(tw, death_row);
 302
 303                 inet_twsk_put(tw);
 304         }
 305         return 0;
 306
 307 not_unique:
 308         spin_unlock(lock);
 309         return -EADDRNOTAVAIL;
 310 }
 311
 312 static inline u32 inet6_sk_port_offset(const struct sock *sk)
 313 {
 314         const struct inet_sock *inet = inet_sk(sk);
 315         const struct ipv6_pinfo *np = inet6_sk(sk);
 316         return secure_ipv6_port_ephemeral(np->rcv_saddr.s6_addr32,
 317                                           np->daddr.s6_addr32,
 318                                           inet->inet_dport);
 319 }
 320
 321 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 322                        struct sock *sk)
 323 {
 324         return __inet_hash_connect(death_row, sk, inet6_sk_port_offset(sk),
 325                         __inet6_check_established, __inet6_hash);
 326 }
 327
 328 EXPORT_SYMBOL_GPL(inet6_hash_connect);