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/addrconf.h>
  21 #include <net/inet_connection_sock.h>
  22 #include <net/inet_hashtables.h>
  23 #include <net/inet6_hashtables.h>
  24 #include <net/secure_seq.h>
  25 #include <net/ip.h>
  26 #include <net/sock_reuseport.h>
  27
  28 u32 inet6_ehashfn(const struct net *net,
  29                   const struct in6_addr *laddr, const u16 lport,
  30                   const struct in6_addr *faddr, const __be16 fport)
  31 {
  32         static u32 inet6_ehash_secret __read_mostly;
  33         static u32 ipv6_hash_secret __read_mostly;
  34
  35         u32 lhash, fhash;
  36
  37         net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
  38         net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
  39
  40         lhash = (__force u32)laddr->s6_addr32[3];
  41         fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);
  42
  43         return __inet6_ehashfn(lhash, lport, fhash, fport,
  44                                inet6_ehash_secret + net_hash_mix(net));
  45 }
  46
  47 /*
  48  * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
  49  * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
  50  *
  51  * The sockhash lock must be held as a reader here.
  52  */
  53 struct sock *__inet6_lookup_established(struct net *net,
  54                                         struct inet_hashinfo *hashinfo,
  55                                            const struct in6_addr *saddr,
  56                                            const __be16 sport,
  57                                            const struct in6_addr *daddr,
  58                                            const u16 hnum,
  59                                            const int dif, const int sdif)
  60 {
  61         struct sock *sk;
  62         const struct hlist_nulls_node *node;
  63         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
  64         /* Optimize here for direct hit, only listening connections can
  65          * have wildcards anyways.
  66          */
  67         unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
  68         unsigned int slot = hash & hashinfo->ehash_mask;
  69         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
  70
  71
  72 begin:
  73         sk_nulls_for_each_rcu(sk, node, &head->chain) {
  74                 if (sk->sk_hash != hash)
  75                         continue;
  76                 if (!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))
  77                         continue;
  78                 if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
  79                         goto out;
  80
  81                 if (unlikely(!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))) {
  82                         sock_gen_put(sk);
  83                         goto begin;
  84                 }
  85                 goto found;
  86         }
  87         if (get_nulls_value(node) != slot)
  88                 goto begin;
  89 out:
  90         sk = NULL;
  91 found:
  92         return sk;
  93 }
  94 EXPORT_SYMBOL(__inet6_lookup_established);
  95
  96 static inline int compute_score(struct sock *sk, struct net *net,
  97                                 const unsigned short hnum,
  98                                 const struct in6_addr *daddr,
  99                                 const int dif, const int sdif, bool exact_dif)
 100 {
 101         int score = -1;
 102
 103         if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 104             sk->sk_family == PF_INET6) {
 105
 106                 score = 1;
 107                 if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
 108                         if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
 109                                 return -1;
 110                         score++;
 111                 }
 112                 if (sk->sk_bound_dev_if || exact_dif) {
 113                         bool dev_match = (sk->sk_bound_dev_if == dif ||
 114                                           sk->sk_bound_dev_if == sdif);
 115
 116                         if (exact_dif && !dev_match)
 117                                 return -1;
 118                         if (sk->sk_bound_dev_if && dev_match)
 119                                 score++;
 120                 }
 121                 if (sk->sk_incoming_cpu == raw_smp_processor_id())
 122                         score++;
 123         }
 124         return score;
 125 }
 126
 127 /* called with rcu_read_lock() */
 128 struct sock *inet6_lookup_listener(struct net *net,
 129                 struct inet_hashinfo *hashinfo,
 130                 struct sk_buff *skb, int doff,
 131                 const struct in6_addr *saddr,
 132                 const __be16 sport, const struct in6_addr *daddr,
 133                 const unsigned short hnum, const int dif, const int sdif)
 134 {
 135         unsigned int hash = inet_lhashfn(net, hnum);
 136         struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
 137         int score, hiscore = 0, matches = 0, reuseport = 0;
 138         bool exact_dif = inet6_exact_dif_match(net, skb);
 139         struct sock *sk, *result = NULL;
 140         u32 phash = 0;
 141
 142         sk_for_each(sk, &ilb->head) {
 143                 score = compute_score(sk, net, hnum, daddr, dif, sdif, exact_dif);
 144                 if (score > hiscore) {
 145                         reuseport = sk->sk_reuseport;
 146                         if (reuseport) {
 147                                 phash = inet6_ehashfn(net, daddr, hnum,
 148                                                       saddr, sport);
 149                                 result = reuseport_select_sock(sk, phash,
 150                                                                skb, doff);
 151                                 if (result)
 152                                         return result;
 153                                 matches = 1;
 154                         }
 155                         result = sk;
 156                         hiscore = score;
 157                 } else if (score == hiscore && reuseport) {
 158                         matches++;
 159                         if (reciprocal_scale(phash, matches) == 0)
 160                                 result = sk;
 161                         phash = next_pseudo_random32(phash);
 162                 }
 163         }
 164         return result;
 165 }
 166 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 167
 168 struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
 169                           struct sk_buff *skb, int doff,
 170                           const struct in6_addr *saddr, const __be16 sport,
 171                           const struct in6_addr *daddr, const __be16 dport,
 172                           const int dif)
 173 {
 174         struct sock *sk;
 175         bool refcounted;
 176
 177         sk = __inet6_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
 178                             ntohs(dport), dif, 0, &refcounted);
 179         if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
 180                 sk = NULL;
 181         return sk;
 182 }
 183 EXPORT_SYMBOL_GPL(inet6_lookup);
 184
 185 static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 186                                      struct sock *sk, const __u16 lport,
 187                                      struct inet_timewait_sock **twp)
 188 {
 189         struct inet_hashinfo *hinfo = death_row->hashinfo;
 190         struct inet_sock *inet = inet_sk(sk);
 191         const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
 192         const struct in6_addr *saddr = &sk->sk_v6_daddr;
 193         const int dif = sk->sk_bound_dev_if;
 194         struct net *net = sock_net(sk);
 195         const int sdif = l3mdev_master_ifindex_by_index(net, dif);
 196         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 197         const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
 198                                                 inet->inet_dport);
 199         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 200         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 201         struct sock *sk2;
 202         const struct hlist_nulls_node *node;
 203         struct inet_timewait_sock *tw = NULL;
 204
 205         spin_lock(lock);
 206
 207         sk_nulls_for_each(sk2, node, &head->chain) {
 208                 if (sk2->sk_hash != hash)
 209                         continue;
 210
 211                 if (likely(INET6_MATCH(sk2, net, saddr, daddr, ports,
 212                                        dif, sdif))) {
 213                         if (sk2->sk_state == TCP_TIME_WAIT) {
 214                                 tw = inet_twsk(sk2);
 215                                 if (twsk_unique(sk, sk2, twp))
 216                                         break;
 217                         }
 218                         goto not_unique;
 219                 }
 220         }
 221
 222         /* Must record num and sport now. Otherwise we will see
 223          * in hash table socket with a funny identity.
 224          */
 225         inet->inet_num = lport;
 226         inet->inet_sport = htons(lport);
 227         sk->sk_hash = hash;
 228         WARN_ON(!sk_unhashed(sk));
 229         __sk_nulls_add_node_rcu(sk, &head->chain);
 230         if (tw) {
 231                 sk_nulls_del_node_init_rcu((struct sock *)tw);
 232                 __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
 233         }
 234         spin_unlock(lock);
 235         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 236
 237         if (twp) {
 238                 *twp = tw;
 239         } else if (tw) {
 240                 /* Silly. Should hash-dance instead... */
 241                 inet_twsk_deschedule_put(tw);
 242         }
 243         return 0;
 244
 245 not_unique:
 246         spin_unlock(lock);
 247         return -EADDRNOTAVAIL;
 248 }
 249
 250 static u32 inet6_sk_port_offset(const struct sock *sk)
 251 {
 252         const struct inet_sock *inet = inet_sk(sk);
 253
 254         return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
 255                                           sk->sk_v6_daddr.s6_addr32,
 256                                           inet->inet_dport);
 257 }
 258
 259 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 260                        struct sock *sk)
 261 {
 262         u32 port_offset = 0;
 263
 264         if (!inet_sk(sk)->inet_num)
 265                 port_offset = inet6_sk_port_offset(sk);
 266         return __inet_hash_connect(death_row, sk, port_offset,
 267                                    __inet6_check_established);
 268 }
 269 EXPORT_SYMBOL_GPL(inet6_hash_connect);
 270
 271 int inet6_hash(struct sock *sk)
 272 {
 273         int err = 0;
 274
 275         if (sk->sk_state != TCP_CLOSE) {
 276                 local_bh_disable();
 277                 err = __inet_hash(sk, NULL);
 278                 local_bh_enable();
 279         }
 280
 281         return err;
 282 }
 283 EXPORT_SYMBOL_GPL(inet6_hash);