net/ipv6/inet6_hashtables.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              Generic INET6 transport hashtables
   8  *
   9  * Authors:     Lotsa people, from code originally in tcp, generalised here
  10  *              by Arnaldo Carvalho de Melo <acme@mandriva.com>
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/random.h>
  15
  16 #include <net/addrconf.h>
  17 #include <net/inet_connection_sock.h>
  18 #include <net/inet_hashtables.h>
  19 #include <net/inet6_hashtables.h>
  20 #include <net/secure_seq.h>
  21 #include <net/ip.h>
  22 #include <net/sock_reuseport.h>
  23
  24 u32 inet6_ehashfn(const struct net *net,
  25                   const struct in6_addr *laddr, const u16 lport,
  26                   const struct in6_addr *faddr, const __be16 fport)
  27 {
  28         static u32 inet6_ehash_secret __read_mostly;
  29         static u32 ipv6_hash_secret __read_mostly;
  30
  31         u32 lhash, fhash;
  32
  33         net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
  34         net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
  35
  36         lhash = (__force u32)laddr->s6_addr32[3];
  37         fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);
  38
  39         return __inet6_ehashfn(lhash, lport, fhash, fport,
  40                                inet6_ehash_secret + net_hash_mix(net));
  41 }
  42
  43 /*
  44  * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
  45  * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
  46  *
  47  * The sockhash lock must be held as a reader here.
  48  */
  49 struct sock *__inet6_lookup_established(struct net *net,
  50                                         struct inet_hashinfo *hashinfo,
  51                                            const struct in6_addr *saddr,
  52                                            const __be16 sport,
  53                                            const struct in6_addr *daddr,
  54                                            const u16 hnum,
  55                                            const int dif, const int sdif)
  56 {
  57         struct sock *sk;
  58         const struct hlist_nulls_node *node;
  59         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
  60         /* Optimize here for direct hit, only listening connections can
  61          * have wildcards anyways.
  62          */
  63         unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
  64         unsigned int slot = hash & hashinfo->ehash_mask;
  65         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
  66
  67
  68 begin:
  69         sk_nulls_for_each_rcu(sk, node, &head->chain) {
  70                 if (sk->sk_hash != hash)
  71                         continue;
  72                 if (!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))
  73                         continue;
  74                 if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
  75                         goto out;
  76
  77                 if (unlikely(!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))) {
  78                         sock_gen_put(sk);
  79                         goto begin;
  80                 }
  81                 goto found;
  82         }
  83         if (get_nulls_value(node) != slot)
  84                 goto begin;
  85 out:
  86         sk = NULL;
  87 found:
  88         return sk;
  89 }
  90 EXPORT_SYMBOL(__inet6_lookup_established);
  91
  92 static inline int compute_score(struct sock *sk, struct net *net,
  93                                 const unsigned short hnum,
  94                                 const struct in6_addr *daddr,
  95                                 const int dif, const int sdif, bool exact_dif)
  96 {
  97         int score = -1;
  98
  99         if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 100             sk->sk_family == PF_INET6) {
 101                 if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
 102                         return -1;
 103
 104                 if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
 105                         return -1;
 106
 107                 score = 1;
 108                 if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 109                         score++;
 110         }
 111         return score;
 112 }
 113
 114 /* called with rcu_read_lock() */
 115 static struct sock *inet6_lhash2_lookup(struct net *net,
 116                 struct inet_listen_hashbucket *ilb2,
 117                 struct sk_buff *skb, int doff,
 118                 const struct in6_addr *saddr,
 119                 const __be16 sport, const struct in6_addr *daddr,
 120                 const unsigned short hnum, const int dif, const int sdif)
 121 {
 122         bool exact_dif = inet6_exact_dif_match(net, skb);
 123         struct inet_connection_sock *icsk;
 124         struct sock *sk, *result = NULL;
 125         int score, hiscore = 0;
 126         u32 phash = 0;
 127
 128         inet_lhash2_for_each_icsk_rcu(icsk, &ilb2->head) {
 129                 sk = (struct sock *)icsk;
 130                 score = compute_score(sk, net, hnum, daddr, dif, sdif,
 131                                       exact_dif);
 132                 if (score > hiscore) {
 133                         if (sk->sk_reuseport) {
 134                                 phash = inet6_ehashfn(net, daddr, hnum,
 135                                                       saddr, sport);
 136                                 result = reuseport_select_sock(sk, phash,
 137                                                                skb, doff);
 138                                 if (result)
 139                                         return result;
 140                         }
 141                         result = sk;
 142                         hiscore = score;
 143                 }
 144         }
 145
 146         return result;
 147 }
 148
 149 struct sock *inet6_lookup_listener(struct net *net,
 150                 struct inet_hashinfo *hashinfo,
 151                 struct sk_buff *skb, int doff,
 152                 const struct in6_addr *saddr,
 153                 const __be16 sport, const struct in6_addr *daddr,
 154                 const unsigned short hnum, const int dif, const int sdif)
 155 {
 156         struct inet_listen_hashbucket *ilb2;
 157         struct sock *result = NULL;
 158         unsigned int hash2;
 159
 160         hash2 = ipv6_portaddr_hash(net, daddr, hnum);
 161         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 162
 163         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 164                                      saddr, sport, daddr, hnum,
 165                                      dif, sdif);
 166         if (result)
 167                 goto done;
 168
 169         /* Lookup lhash2 with in6addr_any */
 170         hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
 171         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 172
 173         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 174                                      saddr, sport, &in6addr_any, hnum,
 175                                      dif, sdif);
 176 done:
 177         if (IS_ERR(result))
 178                 return NULL;
 179         return result;
 180 }
 181 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 182
 183 struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
 184                           struct sk_buff *skb, int doff,
 185                           const struct in6_addr *saddr, const __be16 sport,
 186                           const struct in6_addr *daddr, const __be16 dport,
 187                           const int dif)
 188 {
 189         struct sock *sk;
 190         bool refcounted;
 191
 192         sk = __inet6_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
 193                             ntohs(dport), dif, 0, &refcounted);
 194         if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
 195                 sk = NULL;
 196         return sk;
 197 }
 198 EXPORT_SYMBOL_GPL(inet6_lookup);
 199
 200 static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 201                                      struct sock *sk, const __u16 lport,
 202                                      struct inet_timewait_sock **twp)
 203 {
 204         struct inet_hashinfo *hinfo = death_row->hashinfo;
 205         struct inet_sock *inet = inet_sk(sk);
 206         const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
 207         const struct in6_addr *saddr = &sk->sk_v6_daddr;
 208         const int dif = sk->sk_bound_dev_if;
 209         struct net *net = sock_net(sk);
 210         const int sdif = l3mdev_master_ifindex_by_index(net, dif);
 211         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 212         const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
 213                                                 inet->inet_dport);
 214         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 215         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 216         struct sock *sk2;
 217         const struct hlist_nulls_node *node;
 218         struct inet_timewait_sock *tw = NULL;
 219
 220         spin_lock(lock);
 221
 222         sk_nulls_for_each(sk2, node, &head->chain) {
 223                 if (sk2->sk_hash != hash)
 224                         continue;
 225
 226                 if (likely(INET6_MATCH(sk2, net, saddr, daddr, ports,
 227                                        dif, sdif))) {
 228                         if (sk2->sk_state == TCP_TIME_WAIT) {
 229                                 tw = inet_twsk(sk2);
 230                                 if (twsk_unique(sk, sk2, twp))
 231                                         break;
 232                         }
 233                         goto not_unique;
 234                 }
 235         }
 236
 237         /* Must record num and sport now. Otherwise we will see
 238          * in hash table socket with a funny identity.
 239          */
 240         inet->inet_num = lport;
 241         inet->inet_sport = htons(lport);
 242         sk->sk_hash = hash;
 243         WARN_ON(!sk_unhashed(sk));
 244         __sk_nulls_add_node_rcu(sk, &head->chain);
 245         if (tw) {
 246                 sk_nulls_del_node_init_rcu((struct sock *)tw);
 247                 __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
 248         }
 249         spin_unlock(lock);
 250         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 251
 252         if (twp) {
 253                 *twp = tw;
 254         } else if (tw) {
 255                 /* Silly. Should hash-dance instead... */
 256                 inet_twsk_deschedule_put(tw);
 257         }
 258         return 0;
 259
 260 not_unique:
 261         spin_unlock(lock);
 262         return -EADDRNOTAVAIL;
 263 }
 264
 265 static u32 inet6_sk_port_offset(const struct sock *sk)
 266 {
 267         const struct inet_sock *inet = inet_sk(sk);
 268
 269         return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
 270                                           sk->sk_v6_daddr.s6_addr32,
 271                                           inet->inet_dport);
 272 }
 273
 274 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 275                        struct sock *sk)
 276 {
 277         u32 port_offset = 0;
 278
 279         if (!inet_sk(sk)->inet_num)
 280                 port_offset = inet6_sk_port_offset(sk);
 281         return __inet_hash_connect(death_row, sk, port_offset,
 282                                    __inet6_check_established);
 283 }
 284 EXPORT_SYMBOL_GPL(inet6_hash_connect);
 285
 286 int inet6_hash(struct sock *sk)
 287 {
 288         int err = 0;
 289
 290         if (sk->sk_state != TCP_CLOSE) {
 291                 local_bh_disable();
 292                 err = __inet_hash(sk, NULL);
 293                 local_bh_enable();
 294         }
 295
 296         return err;
 297 }
 298 EXPORT_SYMBOL_GPL(inet6_hash);