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 extern struct inet_hashinfo tcp_hashinfo;
  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         static u32 inet6_ehash_secret __read_mostly;
  31         static u32 ipv6_hash_secret __read_mostly;
  32
  33         u32 lhash, fhash;
  34
  35         net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
  36         net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
  37
  38         lhash = (__force u32)laddr->s6_addr32[3];
  39         fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);
  40
  41         return __inet6_ehashfn(lhash, lport, fhash, fport,
  42                                inet6_ehash_secret + net_hash_mix(net));
  43 }
  44
  45 /*
  46  * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
  47  * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
  48  *
  49  * The sockhash lock must be held as a reader here.
  50  */
  51 struct sock *__inet6_lookup_established(struct net *net,
  52                                         struct inet_hashinfo *hashinfo,
  53                                            const struct in6_addr *saddr,
  54                                            const __be16 sport,
  55                                            const struct in6_addr *daddr,
  56                                            const u16 hnum,
  57                                            const int dif, const int sdif)
  58 {
  59         struct sock *sk;
  60         const struct hlist_nulls_node *node;
  61         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
  62         /* Optimize here for direct hit, only listening connections can
  63          * have wildcards anyways.
  64          */
  65         unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
  66         unsigned int slot = hash & hashinfo->ehash_mask;
  67         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
  68
  69
  70 begin:
  71         sk_nulls_for_each_rcu(sk, node, &head->chain) {
  72                 if (sk->sk_hash != hash)
  73                         continue;
  74                 if (!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))
  75                         continue;
  76                 if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
  77                         goto out;
  78
  79                 if (unlikely(!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))) {
  80                         sock_gen_put(sk);
  81                         goto begin;
  82                 }
  83                 goto found;
  84         }
  85         if (get_nulls_value(node) != slot)
  86                 goto begin;
  87 out:
  88         sk = NULL;
  89 found:
  90         return sk;
  91 }
  92 EXPORT_SYMBOL(__inet6_lookup_established);
  93
  94 static inline int compute_score(struct sock *sk, struct net *net,
  95                                 const unsigned short hnum,
  96                                 const struct in6_addr *daddr,
  97                                 const int dif, const int sdif)
  98 {
  99         int score = -1;
 100
 101         if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
 102             sk->sk_family == PF_INET6) {
 103                 if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
 104                         return -1;
 105
 106                 if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
 107                         return -1;
 108
 109                 score =  sk->sk_bound_dev_if ? 2 : 1;
 110                 if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 111                         score++;
 112         }
 113         return score;
 114 }
 115
 116 static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk,
 117                                             struct sk_buff *skb, int doff,
 118                                             const struct in6_addr *saddr,
 119                                             __be16 sport,
 120                                             const struct in6_addr *daddr,
 121                                             unsigned short hnum)
 122 {
 123         struct sock *reuse_sk = NULL;
 124         u32 phash;
 125
 126         if (sk->sk_reuseport) {
 127                 phash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
 128                 reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
 129         }
 130         return reuse_sk;
 131 }
 132
 133 /* called with rcu_read_lock() */
 134 static struct sock *inet6_lhash2_lookup(struct net *net,
 135                 struct inet_listen_hashbucket *ilb2,
 136                 struct sk_buff *skb, int doff,
 137                 const struct in6_addr *saddr,
 138                 const __be16 sport, const struct in6_addr *daddr,
 139                 const unsigned short hnum, const int dif, const int sdif)
 140 {
 141         struct inet_connection_sock *icsk;
 142         struct sock *sk, *result = NULL;
 143         int score, hiscore = 0;
 144
 145         inet_lhash2_for_each_icsk_rcu(icsk, &ilb2->head) {
 146                 sk = (struct sock *)icsk;
 147                 score = compute_score(sk, net, hnum, daddr, dif, sdif);
 148                 if (score > hiscore) {
 149                         result = lookup_reuseport(net, sk, skb, doff,
 150                                                   saddr, sport, daddr, hnum);
 151                         if (result)
 152                                 return result;
 153
 154                         result = sk;
 155                         hiscore = score;
 156                 }
 157         }
 158
 159         return result;
 160 }
 161
 162 static inline struct sock *inet6_lookup_run_bpf(struct net *net,
 163                                                 struct inet_hashinfo *hashinfo,
 164                                                 struct sk_buff *skb, int doff,
 165                                                 const struct in6_addr *saddr,
 166                                                 const __be16 sport,
 167                                                 const struct in6_addr *daddr,
 168                                                 const u16 hnum)
 169 {
 170         struct sock *sk, *reuse_sk;
 171         bool no_reuseport;
 172
 173         if (hashinfo != &tcp_hashinfo)
 174                 return NULL; /* only TCP is supported */
 175
 176         no_reuseport = bpf_sk_lookup_run_v6(net, IPPROTO_TCP,
 177                                             saddr, sport, daddr, hnum, &sk);
 178         if (no_reuseport || IS_ERR_OR_NULL(sk))
 179                 return sk;
 180
 181         reuse_sk = lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum);
 182         if (reuse_sk)
 183                 sk = reuse_sk;
 184         return sk;
 185 }
 186
 187 struct sock *inet6_lookup_listener(struct net *net,
 188                 struct inet_hashinfo *hashinfo,
 189                 struct sk_buff *skb, int doff,
 190                 const struct in6_addr *saddr,
 191                 const __be16 sport, const struct in6_addr *daddr,
 192                 const unsigned short hnum, const int dif, const int sdif)
 193 {
 194         struct inet_listen_hashbucket *ilb2;
 195         struct sock *result = NULL;
 196         unsigned int hash2;
 197
 198         /* Lookup redirect from BPF */
 199         if (static_branch_unlikely(&bpf_sk_lookup_enabled)) {
 200                 result = inet6_lookup_run_bpf(net, hashinfo, skb, doff,
 201                                               saddr, sport, daddr, hnum);
 202                 if (result)
 203                         goto done;
 204         }
 205
 206         hash2 = ipv6_portaddr_hash(net, daddr, hnum);
 207         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 208
 209         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 210                                      saddr, sport, daddr, hnum,
 211                                      dif, sdif);
 212         if (result)
 213                 goto done;
 214
 215         /* Lookup lhash2 with in6addr_any */
 216         hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
 217         ilb2 = inet_lhash2_bucket(hashinfo, hash2);
 218
 219         result = inet6_lhash2_lookup(net, ilb2, skb, doff,
 220                                      saddr, sport, &in6addr_any, hnum,
 221                                      dif, sdif);
 222 done:
 223         if (IS_ERR(result))
 224                 return NULL;
 225         return result;
 226 }
 227 EXPORT_SYMBOL_GPL(inet6_lookup_listener);
 228
 229 struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
 230                           struct sk_buff *skb, int doff,
 231                           const struct in6_addr *saddr, const __be16 sport,
 232                           const struct in6_addr *daddr, const __be16 dport,
 233                           const int dif)
 234 {
 235         struct sock *sk;
 236         bool refcounted;
 237
 238         sk = __inet6_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
 239                             ntohs(dport), dif, 0, &refcounted);
 240         if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))
 241                 sk = NULL;
 242         return sk;
 243 }
 244 EXPORT_SYMBOL_GPL(inet6_lookup);
 245
 246 static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 247                                      struct sock *sk, const __u16 lport,
 248                                      struct inet_timewait_sock **twp)
 249 {
 250         struct inet_hashinfo *hinfo = death_row->hashinfo;
 251         struct inet_sock *inet = inet_sk(sk);
 252         const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
 253         const struct in6_addr *saddr = &sk->sk_v6_daddr;
 254         const int dif = sk->sk_bound_dev_if;
 255         struct net *net = sock_net(sk);
 256         const int sdif = l3mdev_master_ifindex_by_index(net, dif);
 257         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 258         const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
 259                                                 inet->inet_dport);
 260         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 261         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 262         struct sock *sk2;
 263         const struct hlist_nulls_node *node;
 264         struct inet_timewait_sock *tw = NULL;
 265
 266         spin_lock(lock);
 267
 268         sk_nulls_for_each(sk2, node, &head->chain) {
 269                 if (sk2->sk_hash != hash)
 270                         continue;
 271
 272                 if (likely(INET6_MATCH(sk2, net, saddr, daddr, ports,
 273                                        dif, sdif))) {
 274                         if (sk2->sk_state == TCP_TIME_WAIT) {
 275                                 tw = inet_twsk(sk2);
 276                                 if (twsk_unique(sk, sk2, twp))
 277                                         break;
 278                         }
 279                         goto not_unique;
 280                 }
 281         }
 282
 283         /* Must record num and sport now. Otherwise we will see
 284          * in hash table socket with a funny identity.
 285          */
 286         inet->inet_num = lport;
 287         inet->inet_sport = htons(lport);
 288         sk->sk_hash = hash;
 289         WARN_ON(!sk_unhashed(sk));
 290         __sk_nulls_add_node_rcu(sk, &head->chain);
 291         if (tw) {
 292                 sk_nulls_del_node_init_rcu((struct sock *)tw);
 293                 __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
 294         }
 295         spin_unlock(lock);
 296         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 297
 298         if (twp) {
 299                 *twp = tw;
 300         } else if (tw) {
 301                 /* Silly. Should hash-dance instead... */
 302                 inet_twsk_deschedule_put(tw);
 303         }
 304         return 0;
 305
 306 not_unique:
 307         spin_unlock(lock);
 308         return -EADDRNOTAVAIL;
 309 }
 310
 311 static u32 inet6_sk_port_offset(const struct sock *sk)
 312 {
 313         const struct inet_sock *inet = inet_sk(sk);
 314
 315         return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
 316                                           sk->sk_v6_daddr.s6_addr32,
 317                                           inet->inet_dport);
 318 }
 319
 320 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 321                        struct sock *sk)
 322 {
 323         u32 port_offset = 0;
 324
 325         if (!inet_sk(sk)->inet_num)
 326                 port_offset = inet6_sk_port_offset(sk);
 327         return __inet_hash_connect(death_row, sk, port_offset,
 328                                    __inet6_check_established);
 329 }
 330 EXPORT_SYMBOL_GPL(inet6_hash_connect);
 331
 332 int inet6_hash(struct sock *sk)
 333 {
 334         int err = 0;
 335
 336         if (sk->sk_state != TCP_CLOSE) {
 337                 local_bh_disable();
 338                 err = __inet_hash(sk, NULL);
 339                 local_bh_enable();
 340         }
 341
 342         return err;
 343 }
 344 EXPORT_SYMBOL_GPL(inet6_hash);