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/hotdata.h>
  18 #include <net/inet_connection_sock.h>
  19 #include <net/inet_hashtables.h>
  20 #include <net/inet6_hashtables.h>
  21 #include <net/secure_seq.h>
  22 #include <net/ip.h>
  23 #include <net/sock_reuseport.h>
  24 #include <net/tcp.h>
  25
  26 u32 inet6_ehashfn(const struct net *net,
  27                   const struct in6_addr *laddr, const u16 lport,
  28                   const struct in6_addr *faddr, const __be16 fport)
  29 {
  30         u32 lhash, fhash;
  31
  32         net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
  33         net_get_random_once(&tcp_ipv6_hash_secret, sizeof(tcp_ipv6_hash_secret));
  34
  35         lhash = (__force u32)laddr->s6_addr32[3];
  36         fhash = __ipv6_addr_jhash(faddr, tcp_ipv6_hash_secret);
  37
  38         return __inet6_ehashfn(lhash, lport, fhash, fport,
  39                                inet6_ehash_secret + net_hash_mix(net));
  40 }
  41 EXPORT_SYMBOL_GPL(inet6_ehashfn);
  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(const 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(net, sk, 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(net, sk, 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, const struct net *net,
  93                                 const unsigned short hnum,
  94                                 const struct in6_addr *daddr,
  95                                 const int dif, const int sdif)
  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 =  sk->sk_bound_dev_if ? 2 : 1;
 108                 if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 109                         score++;
 110         }
 111         return score;
 112 }
 113
 114 /**
 115  * inet6_lookup_reuseport() - execute reuseport logic on AF_INET6 socket if necessary.
 116  * @net: network namespace.
 117  * @sk: AF_INET6 socket, must be in TCP_LISTEN state for TCP or TCP_CLOSE for UDP.
 118  * @skb: context for a potential SK_REUSEPORT program.
 119  * @doff: header offset.
 120  * @saddr: source address.
 121  * @sport: source port.
 122  * @daddr: destination address.
 123  * @hnum: destination port in host byte order.
 124  * @ehashfn: hash function used to generate the fallback hash.
 125  *
 126  * Return: NULL if sk doesn't have SO_REUSEPORT set, otherwise a pointer to
 127  *         the selected sock or an error.
 128  */
 129 struct sock *inet6_lookup_reuseport(const struct net *net, struct sock *sk,
 130                                     struct sk_buff *skb, int doff,
 131                                     const struct in6_addr *saddr,
 132                                     __be16 sport,
 133                                     const struct in6_addr *daddr,
 134                                     unsigned short hnum,
 135                                     inet6_ehashfn_t *ehashfn)
 136 {
 137         struct sock *reuse_sk = NULL;
 138         u32 phash;
 139
 140         if (sk->sk_reuseport) {
 141                 phash = INDIRECT_CALL_INET(ehashfn, udp6_ehashfn, inet6_ehashfn,
 142                                            net, daddr, hnum, saddr, sport);
 143                 reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
 144         }
 145         return reuse_sk;
 146 }
 147 EXPORT_SYMBOL_GPL(inet6_lookup_reuseport);
 148
 149 /* called with rcu_read_lock() */
 150 static struct sock *inet6_lhash2_lookup(const struct net *net,
 151                 struct inet_listen_hashbucket *ilb2,
 152                 struct sk_buff *skb, int doff,
 153                 const struct in6_addr *saddr,
 154                 const __be16 sport, const struct in6_addr *daddr,
 155                 const unsigned short hnum, const int dif, const int sdif)
 156 {
 157         struct sock *sk, *result = NULL;
 158         struct hlist_nulls_node *node;
 159         int score, hiscore = 0;
 160
 161         sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) {
 162                 score = compute_score(sk, net, hnum, daddr, dif, sdif);
 163                 if (score > hiscore) {
 164                         result = inet6_lookup_reuseport(net, sk, skb, doff,
 165                                                         saddr, sport, daddr, hnum, inet6_ehashfn);
 166                         if (result)
 167                                 return result;
 168
 169                         result = sk;
 170                         hiscore = score;
 171                 }
 172         }
 173
 174         return result;
 175 }
 176
 177 struct sock *inet6_lookup_run_sk_lookup(const struct net *net,
 178                                         int protocol,
 179                                         struct sk_buff *skb, int doff,
 180                                         const struct in6_addr *saddr,
 181                                         const __be16 sport,
 182                                         const struct in6_addr *daddr,
 183                                         const u16 hnum, const int dif,
 184                                         inet6_ehashfn_t *ehashfn)
 185 {
 186         struct sock *sk, *reuse_sk;
 187         bool no_reuseport;
 188
 189         no_reuseport = bpf_sk_lookup_run_v6(net, protocol, saddr, sport,
 190                                             daddr, hnum, dif, &sk);
 191         if (no_reuseport || IS_ERR_OR_NULL(sk))
 192                 return sk;
 193
 194         reuse_sk = inet6_lookup_reuseport(net, sk, skb, doff,
 195                                           saddr, sport, daddr, hnum, ehashfn);
 196         if (reuse_sk)
 197                 sk = reuse_sk;
 198         return sk;
 199 }
 200 EXPORT_SYMBOL_GPL(inet6_lookup_run_sk_lookup);
 201
 202 struct sock *inet6_lookup_listener(const struct net *net,
 203                 struct inet_hashinfo *hashinfo,
 204                 struct sk_buff *skb, int doff,
 205                 const struct in6_addr *saddr,
 206                 const __be16 sport, const struct in6_addr *daddr,
 207                 const unsigned short hnum, const int dif, const int sdif)
 208 {
 209         struct inet_listen_hashbucket *ilb2;
 210         struct sock *result = NULL;
 211         unsigned int hash2;
 212
 213         /* Lookup redirect from BPF */
 214         if (static_branch_unlikely(&bpf_sk_lookup_enabled) &&
 215             hashinfo == net->ipv4.tcp_death_row.hashinfo) {
 216                 result = inet6_lookup_run_sk_lookup(net, IPPROTO_TCP, skb, doff,
 217                                                     saddr, sport, daddr, hnum, dif,
 218                                                     inet6_ehashfn);
 219                 if (result)
 220                         goto done;
 221         }
 222
 223         hash2 = ipv6_portaddr_hash(net, daddr, hnum);
 224         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 225
 226         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 227                                      saddr, sport, daddr, hnum,
 228                                      dif, sdif);
 229         if (result)
 230                 goto done;
 231
 232         /* Lookup lhash2 with in6addr_any */
 233         hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
 234         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 235
 236         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 237                                      saddr, sport, &in6addr_any, hnum,
 238                                      dif, sdif);
 239 done:
 240         if (IS_ERR(result))
 241                 return NULL;
 242         return result;
 243 }
 244 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 245
 246 struct sock *inet6_lookup(const struct net *net,
 247                           struct inet_hashinfo *hashinfo,
 248                           struct sk_buff *skb, int doff,
 249                           const struct in6_addr *saddr, const __be16 sport,
 250                           const struct in6_addr *daddr, const __be16 dport,
 251                           const int dif)
 252 {
 253         struct sock *sk;
 254         bool refcounted;
 255
 256         sk = __inet6_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
 257                             ntohs(dport), dif, 0, &refcounted);
 258         if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
 259                 sk = NULL;
 260         return sk;
 261 }
 262 EXPORT_SYMBOL_GPL(inet6_lookup);
 263
 264 static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 265                                      struct sock *sk, const __u16 lport,
 266                                      struct inet_timewait_sock **twp)
 267 {
 268         struct inet_hashinfo *hinfo = death_row->hashinfo;
 269         struct inet_sock *inet = inet_sk(sk);
 270         const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
 271         const struct in6_addr *saddr = &sk->sk_v6_daddr;
 272         const int dif = sk->sk_bound_dev_if;
 273         struct net *net = sock_net(sk);
 274         const int sdif = l3mdev_master_ifindex_by_index(net, dif);
 275         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 276         const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
 277                                                 inet->inet_dport);
 278         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 279         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 280         struct sock *sk2;
 281         const struct hlist_nulls_node *node;
 282         struct inet_timewait_sock *tw = NULL;
 283
 284         spin_lock(lock);
 285
 286         sk_nulls_for_each(sk2, node, &head->chain) {
 287                 if (sk2->sk_hash != hash)
 288                         continue;
 289
 290                 if (likely(inet6_match(net, sk2, saddr, daddr, ports,
 291                                        dif, sdif))) {
 292                         if (sk2->sk_state == TCP_TIME_WAIT) {
 293                                 tw = inet_twsk(sk2);
 294                                 if (sk->sk_protocol == IPPROTO_TCP &&
 295                                     tcp_twsk_unique(sk, sk2, twp))
 296                                         break;
 297                         }
 298                         goto not_unique;
 299                 }
 300         }
 301
 302         /* Must record num and sport now. Otherwise we will see
 303          * in hash table socket with a funny identity.
 304          */
 305         inet->inet_num = lport;
 306         inet->inet_sport = htons(lport);
 307         sk->sk_hash = hash;
 308         WARN_ON(!sk_unhashed(sk));
 309         __sk_nulls_add_node_rcu(sk, &head->chain);
 310         if (tw) {
 311                 sk_nulls_del_node_init_rcu((struct sock *)tw);
 312                 __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
 313         }
 314         spin_unlock(lock);
 315         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 316
 317         if (twp) {
 318                 *twp = tw;
 319         } else if (tw) {
 320                 /* Silly. Should hash-dance instead... */
 321                 inet_twsk_deschedule_put(tw);
 322         }
 323         return 0;
 324
 325 not_unique:
 326         spin_unlock(lock);
 327         return -EADDRNOTAVAIL;
 328 }
 329
 330 static u64 inet6_sk_port_offset(const struct sock *sk)
 331 {
 332         const struct inet_sock *inet = inet_sk(sk);
 333
 334         return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
 335                                           sk->sk_v6_daddr.s6_addr32,
 336                                           inet->inet_dport);
 337 }
 338
 339 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 340                        struct sock *sk)
 341 {
 342         u64 port_offset = 0;
 343
 344         if (!inet_sk(sk)->inet_num)
 345                 port_offset = inet6_sk_port_offset(sk);
 346         return __inet_hash_connect(death_row, sk, port_offset,
 347                                    __inet6_check_established);
 348 }
 349 EXPORT_SYMBOL_GPL(inet6_hash_connect);
 350
 351 int inet6_hash(struct sock *sk)
 352 {
 353         int err = 0;
 354
 355         if (sk->sk_state != TCP_CLOSE)
 356                 err = __inet_hash(sk, NULL);
 357
 358         return err;
 359 }
 360 EXPORT_SYMBOL_GPL(inet6_hash);