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 EXPORT_SYMBOL_GPL(inet6_ehashfn);
  43
  44 /*
  45  * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
  46  * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
  47  *
  48  * The sockhash lock must be held as a reader here.
  49  */
  50 struct sock *__inet6_lookup_established(struct net *net,
  51                                         struct inet_hashinfo *hashinfo,
  52                                            const struct in6_addr *saddr,
  53                                            const __be16 sport,
  54                                            const struct in6_addr *daddr,
  55                                            const u16 hnum,
  56                                            const int dif, const int sdif)
  57 {
  58         struct sock *sk;
  59         const struct hlist_nulls_node *node;
  60         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
  61         /* Optimize here for direct hit, only listening connections can
  62          * have wildcards anyways.
  63          */
  64         unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
  65         unsigned int slot = hash & hashinfo->ehash_mask;
  66         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
  67
  68
  69 begin:
  70         sk_nulls_for_each_rcu(sk, node, &head->chain) {
  71                 if (sk->sk_hash != hash)
  72                         continue;
  73                 if (!inet6_match(net, sk, saddr, daddr, ports, dif, sdif))
  74                         continue;
  75                 if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
  76                         goto out;
  77
  78                 if (unlikely(!inet6_match(net, sk, saddr, daddr, ports, dif, sdif))) {
  79                         sock_gen_put(sk);
  80                         goto begin;
  81                 }
  82                 goto found;
  83         }
  84         if (get_nulls_value(node) != slot)
  85                 goto begin;
  86 out:
  87         sk = NULL;
  88 found:
  89         return sk;
  90 }
  91 EXPORT_SYMBOL(__inet6_lookup_established);
  92
  93 static inline int compute_score(struct sock *sk, struct net *net,
  94                                 const unsigned short hnum,
  95                                 const struct in6_addr *daddr,
  96                                 const int dif, const int sdif)
  97 {
  98         int score = -1;
  99
 100         if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 101             sk->sk_family == PF_INET6) {
 102                 if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
 103                         return -1;
 104
 105                 if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
 106                         return -1;
 107
 108                 score =  sk->sk_bound_dev_if ? 2 : 1;
 109                 if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 110                         score++;
 111         }
 112         return score;
 113 }
 114
 115 /**
 116  * inet6_lookup_reuseport() - execute reuseport logic on AF_INET6 socket if necessary.
 117  * @net: network namespace.
 118  * @sk: AF_INET6 socket, must be in TCP_LISTEN state for TCP or TCP_CLOSE for UDP.
 119  * @skb: context for a potential SK_REUSEPORT program.
 120  * @doff: header offset.
 121  * @saddr: source address.
 122  * @sport: source port.
 123  * @daddr: destination address.
 124  * @hnum: destination port in host byte order.
 125  * @ehashfn: hash function used to generate the fallback hash.
 126  *
 127  * Return: NULL if sk doesn't have SO_REUSEPORT set, otherwise a pointer to
 128  *         the selected sock or an error.
 129  */
 130 struct sock *inet6_lookup_reuseport(struct net *net, struct sock *sk,
 131                                     struct sk_buff *skb, int doff,
 132                                     const struct in6_addr *saddr,
 133                                     __be16 sport,
 134                                     const struct in6_addr *daddr,
 135                                     unsigned short hnum,
 136                                     inet6_ehashfn_t *ehashfn)
 137 {
 138         struct sock *reuse_sk = NULL;
 139         u32 phash;
 140
 141         if (sk->sk_reuseport) {
 142                 phash = INDIRECT_CALL_INET(ehashfn, udp6_ehashfn, inet6_ehashfn,
 143                                            net, daddr, hnum, saddr, sport);
 144                 reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
 145         }
 146         return reuse_sk;
 147 }
 148 EXPORT_SYMBOL_GPL(inet6_lookup_reuseport);
 149
 150 /* called with rcu_read_lock() */
 151 static struct sock *inet6_lhash2_lookup(struct net *net,
 152                 struct inet_listen_hashbucket *ilb2,
 153                 struct sk_buff *skb, int doff,
 154                 const struct in6_addr *saddr,
 155                 const __be16 sport, const struct in6_addr *daddr,
 156                 const unsigned short hnum, const int dif, const int sdif)
 157 {
 158         struct sock *sk, *result = NULL;
 159         struct hlist_nulls_node *node;
 160         int score, hiscore = 0;
 161
 162         sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) {
 163                 score = compute_score(sk, net, hnum, daddr, dif, sdif);
 164                 if (score > hiscore) {
 165                         result = inet6_lookup_reuseport(net, sk, skb, doff,
 166                                                         saddr, sport, daddr, hnum, inet6_ehashfn);
 167                         if (result)
 168                                 return result;
 169
 170                         result = sk;
 171                         hiscore = score;
 172                 }
 173         }
 174
 175         return result;
 176 }
 177
 178 struct sock *inet6_lookup_run_sk_lookup(struct net *net,
 179                                         int protocol,
 180                                         struct sk_buff *skb, int doff,
 181                                         const struct in6_addr *saddr,
 182                                         const __be16 sport,
 183                                         const struct in6_addr *daddr,
 184                                         const u16 hnum, const int dif,
 185                                         inet6_ehashfn_t *ehashfn)
 186 {
 187         struct sock *sk, *reuse_sk;
 188         bool no_reuseport;
 189
 190         no_reuseport = bpf_sk_lookup_run_v6(net, protocol, saddr, sport,
 191                                             daddr, hnum, dif, &sk);
 192         if (no_reuseport || IS_ERR_OR_NULL(sk))
 193                 return sk;
 194
 195         reuse_sk = inet6_lookup_reuseport(net, sk, skb, doff,
 196                                           saddr, sport, daddr, hnum, ehashfn);
 197         if (reuse_sk)
 198                 sk = reuse_sk;
 199         return sk;
 200 }
 201 EXPORT_SYMBOL_GPL(inet6_lookup_run_sk_lookup);
 202
 203 struct sock *inet6_lookup_listener(struct net *net,
 204                 struct inet_hashinfo *hashinfo,
 205                 struct sk_buff *skb, int doff,
 206                 const struct in6_addr *saddr,
 207                 const __be16 sport, const struct in6_addr *daddr,
 208                 const unsigned short hnum, const int dif, const int sdif)
 209 {
 210         struct inet_listen_hashbucket *ilb2;
 211         struct sock *result = NULL;
 212         unsigned int hash2;
 213
 214         /* Lookup redirect from BPF */
 215         if (static_branch_unlikely(&bpf_sk_lookup_enabled) &&
 216             hashinfo == net->ipv4.tcp_death_row.hashinfo) {
 217                 result = inet6_lookup_run_sk_lookup(net, IPPROTO_TCP, skb, doff,
 218                                                     saddr, sport, daddr, hnum, dif,
 219                                                     inet6_ehashfn);
 220                 if (result)
 221                         goto done;
 222         }
 223
 224         hash2 = ipv6_portaddr_hash(net, daddr, hnum);
 225         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 226
 227         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 228                                      saddr, sport, daddr, hnum,
 229                                      dif, sdif);
 230         if (result)
 231                 goto done;
 232
 233         /* Lookup lhash2 with in6addr_any */
 234         hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
 235         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 236
 237         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 238                                      saddr, sport, &in6addr_any, hnum,
 239                                      dif, sdif);
 240 done:
 241         if (IS_ERR(result))
 242                 return NULL;
 243         return result;
 244 }
 245 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 246
 247 struct sock *inet6_lookup(struct net *net, 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 (twsk_unique(sk, sk2, twp))
 295                                         break;
 296                         }
 297                         goto not_unique;
 298                 }
 299         }
 300
 301         /* Must record num and sport now. Otherwise we will see
 302          * in hash table socket with a funny identity.
 303          */
 304         inet->inet_num = lport;
 305         inet->inet_sport = htons(lport);
 306         sk->sk_hash = hash;
 307         WARN_ON(!sk_unhashed(sk));
 308         __sk_nulls_add_node_rcu(sk, &head->chain);
 309         if (tw) {
 310                 sk_nulls_del_node_init_rcu((struct sock *)tw);
 311                 __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
 312         }
 313         spin_unlock(lock);
 314         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 315
 316         if (twp) {
 317                 *twp = tw;
 318         } else if (tw) {
 319                 /* Silly. Should hash-dance instead... */
 320                 inet_twsk_deschedule_put(tw);
 321         }
 322         return 0;
 323
 324 not_unique:
 325         spin_unlock(lock);
 326         return -EADDRNOTAVAIL;
 327 }
 328
 329 static u64 inet6_sk_port_offset(const struct sock *sk)
 330 {
 331         const struct inet_sock *inet = inet_sk(sk);
 332
 333         return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
 334                                           sk->sk_v6_daddr.s6_addr32,
 335                                           inet->inet_dport);
 336 }
 337
 338 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 339                        struct sock *sk)
 340 {
 341         u64 port_offset = 0;
 342
 343         if (!inet_sk(sk)->inet_num)
 344                 port_offset = inet6_sk_port_offset(sk);
 345         return __inet_hash_connect(death_row, sk, port_offset,
 346                                    __inet6_check_established);
 347 }
 348 EXPORT_SYMBOL_GPL(inet6_hash_connect);
 349
 350 int inet6_hash(struct sock *sk)
 351 {
 352         int err = 0;
 353
 354         if (sk->sk_state != TCP_CLOSE)
 355                 err = __inet_hash(sk, NULL);
 356
 357         return err;
 358 }
 359 EXPORT_SYMBOL_GPL(inet6_hash);